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CHAPTER, , 60, , Acquired Heart Disease:, Coronary Insufficiency, Shuab Omer, Faisel G. Bakaeen, , OUTLINE, Coronary Artery Anatomy and Physiology, Anatomic Considerations, Physiology and Regulation of Coronary Blood Flow, History of Coronary Artery Bypass Surgery, Atherosclerotic Coronary Artery Disease, Pathogenesis, Fixed Coronary Obstructions, Clinical Manifestations and Diagnosis of Coronary Artery, Disease, Clinical Presentation, Physical Examination, Diagnostic Testing, Cardiac Catheterization and Intervention, Indications for Coronary Artery Revascularization, Coronary Artery Bypass Grafting Versus Contemporaneous, Medical Therapy, Percutaneous Coronary Intervention Versus Medical Therapy, Coronary Artery Bypass Grafting Versus Balloon Angioplasty, or Bare-Metal Stents, Coronary Artery Bypass Grafting Versus Drug-Eluting Stents, Left Main Coronary Artery Disease, Proximal LAD Artery Disease, Completeness of Revascularization, Left Ventricular Systolic Dysfunction, Revascularization Options for Previous CABG, Unstable Angina/Non–ST-Segment Elevation Myocardial, Infarction, ST-Segment Elevation Myocardial Infarction–Acute, Myocardial Infarction, Preoperative Evaluation, Technique of Myocardial Revascularization: Conventional, On-Pump Cardiopulmonary Bypass, , Adjuncts to Coronary Artery Bypass Grafting, Transesophageal Echocardiography, Inotropes and Pharmacotherapy, Intraaortic Balloon Pump, Postoperative Care, Pulmonary Care, Discharge From the Intensive Care Unit, Outcomes, Medical Adjuncts for Postoperative Management, Alternative Methods for Myocardial Revascularization, Cardiopulmonary Bypass With Hypothermic Fibrillatory, Arrest, On-Pump Beating-Heart Bypass, Off-Pump Coronary Artery Bypass Grafting, Minimally Invasive Direct Coronary Artery Bypass, Robotics: Totally Endoscopic Coronary Artery Bypass, Transmyocardial Laser Revascularization, Hybrid Procedures, Technical Aspects of Reoperative Coronary Artery Bypass, Grafting, Mechanical Complications of Coronary Artery Disease, Left Ventricular Aneurysm, Ventricular Septal Defect, Mitral Regurgitation, Coronary Artery Bypass Grafting and Special Populations of, Patients, Patients With Diabetes, Older Patients, Women, Patients With Renal Disease, Obese Patients, Acknowledgments, , Ischemic heart disease (IHD) is the predominant public health, problem worldwide. Coronary heart disease (43.8%) is the leading cause of death attributable to cardiovascular disease (CVD) in, the United States, followed by stroke (16.8%), high blood pressure (9.4%), heart failure (9.0%), diseases of the arteries (3.1%),, and other CVDs (17.9%)., It is estimated that by 2035, more than 130 million adults in, the U.S. population (45.1%) are projected to have some form of, CVD, and total costs of CVD are expected to reach $1.1 trillion, in 2035, with direct medical costs projected to reach $748.7 billion and indirect costs estimated to reach $368 billion.1–3, , Despite recent advances in percutaneous intervention, coronary artery bypass grafting (CABG) still remains the most effective, treatment for coronary artery disease (CAD) and is the most commonly performed open cardiac procedure in the United States., , CORONARY ARTERY ANATOMY AND PHYSIOLOGY, Anatomic Considerations, The coronary arteries, the predominant blood supply to the heart,, arise from the sinuses of Valsalva. They are the first arterial branches, of the aorta, and two are usually present. The coronary arteries are, , 1679, Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1680, , SECTION XI Chest, TABLE 60.1 Anatomic architecture of, , coronary arteries., NAMED VESSELS, , BRANCHES, , Left main coronary artery, , Left anterior descending, Circumflex coronary, Ramus intermedius, Diagonal arteries, Septal perforators, Obtuse marginal branches, Left posterolateral artery, Acute marginal artery, Posterior descending artery, Right posterolateral artery, , Left anterior descending, Circumflex coronary artery, Right coronary artery, , LM, CA, RC, LAD, Diag., OM, , Acute, PD, , FIG. 60.1 Anatomy of normal coronary artery vasculature. CA, Circumflex artery; LAD, left anterior descending; LM, left main; OM, obtuse marginal; PD, posterior descending; RC, right coronary., , designated right and left according to the embryologic chamber that, they predominantly supply. The left coronary artery (LCA) arises, from the left coronary sinus, which is located posterior; the right, coronary artery (RCA) arises from the right coronary sinus, which is, located anterior. The LCA, also called the left main coronary artery,, averages approximately 2 to 3 cm in length and courses in a left, posterolateral direction, winding behind the main pulmonary artery, trunk and then splitting into the left anterior descending (LAD) and, left circumflex arteries. The LAD courses in an anterolateral direction to the left of the pulmonary trunk and runs anteriorly over the, interventricular septum. The diagonal branches of the LAD supply, the anterolateral wall of the left ventricle (LV). The LAD is considered the most important surgical vessel because it supplies more than, 50% of the LV mass and most of the interventricular septum. The, LAD has several septal perforating branches that supply the interventricular septum from its anterior aspect. The LAD extends over, the interventricular septum up to the apex of the heart, where it may, form an anastomosis with the posterior descending artery (PDA),, which is typically a branch of the right coronary system (Fig. 60.1)., The circumflex artery passes in the atrioventricular (AV) groove, and gives off the obtuse marginal branches that extend toward, but do not quite reach the apex of the heart. The obtuse marginal, branches are designated numerically from proximal to distal. The, circumflex coronary artery usually terminates as the left posterolateral branch after taking a perpendicular turn toward the apex., The term ramus intermedius is used to designate a dominant coronary vessel that arises from the occasional trifurcation of the LCA., This branch can be intramyocardial and difficult to locate at times., The RCA supplies most of the right ventricle as well as the, posterior part of the LV. The RCA emerges from its ostium in the, right coronary sinus and passes deep in the right AV groove. At, the superior end of the acute margin of the heart, the RCA turns, , posteriorly toward the crux and usually bifurcates into the PDA, over the posterior interventricular sulcus and right posterolateral, artery. The RCA also supplies multiple right ventricular branches, (i.e., the acute marginal branches). On occasion, the PDA arises, from both the RCA and LCA, and the circulation is considered, to be codominant. The AV node artery arises from the RCA in, approximately 90% of patients. The sinoatrial node artery arises, from the proximal RCA in 50% of patients. Although the source, of the PDA is often used clinically to define dominance of circulation in the heart, anatomists define it according to where the, sinoatrial node artery arises. Table 60.1 summarizes the hierarchy, of the coronary artery anatomy., All the epicardial conductance vessels and septal perforators, from the LAD give rise to a multitude of branches, termed resistance vessels, that penetrate into the ventricular wall. These vessels play a crucial role in oxygen and nutrient exchange with the, myocardium by forming a rich capillary plexus. This plexus offers, a low-resistance sink that allows arterial blood flow to increase, unimpeded when oxygen demand rises. This is important because, the myocardial vascular bed extracts oxygen at its full capacity,, even in low-demand circumstances, thereby allowing no margin, for further oxygen extraction when demand is high., An intricate network of veins drains the coronary circulation,, and the venous circulation can be divided into three systems: the, coronary sinus and its tributaries, the anterior right ventricular, veins, and the thebesian veins. The coronary sinus predominantly, drains the LV and receives 85% of coronary venous blood. It lies, within the posterior AV groove and empties into the right atrium., The anterior right ventricular veins travel across the right ventricular surface to the right AV groove, where they enter directly into, the right atrium or form the small cardiac vein, which enters into, the right atrium directly or joins the coronary sinus just proximal, to its orifice. The thebesian veins are small venous tributaries that, drain directly into the cardiac chambers and exit primarily into the, right atrium and right ventricle. Understanding of the anatomy, of the coronary sinus is essential for placement of the retrograde, cardioplegia cannula during cardiopulmonary bypass (CPB)., , Physiology and Regulation of Coronary Blood Flow, Aortic pressure is a driving force in the maintenance of myocardial perfusion. During resting conditions, coronary blood flow, is maintained at a fairly constant level over a wide range of aortic, perfusion pressures (70–180 mm Hg) through the process of, autoregulation., Because the myocardium has a high rate of energy use, normal, coronary blood flow averages 225 mL/min (0.7–0.9 mL per gram, of myocardium per minute) and delivers 0.1 mL/g/min of oxygen, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, BOX 60.1, , blood flow., •, •, •, •, •, •, •, , Unique features of coronary, ,  utoregulated over wide pressure ranges, A, Blood flow: 0.7–0.9 mL per gram of myocardium per minute, 75% oxygen extraction, Coronary sinus blood is the most deoxygenated blood in the body, 4- to 7-fold increase in flow with increased demand, 60% blood flow occurs during diastole, Flow-limited oxygen supply, , to the myocardium. Under normal conditions, more than 75% of, the delivered oxygen is extracted in the coronary capillary bed, so, any additional oxygen demand can be met only by increasing the, flow rate. This highlights the importance of unobstructed coronary blood flow for proper myocardial function. Box 60.1 summarizes the unique features of coronary blood flow., In response to increased load, such as that caused by strenuous exercise, the healthy heart can increase myocardial blood flow, four- to sevenfold. Blood flow is increased through several mechanisms. Local metabolic neurohumoral factors cause coronary vasodilation when stress and metabolic demand increase, thereby, lowering the coronary vascular resistance. This results in increased, delivery of oxygen-rich blood, mimicking the phenomenon of, reactive hyperemia. When a transient occlusion to the coronary, artery is released (e.g., during the performance of a beating-heart, operation), blood flow immediately rises to exceed the normal, baseline flow and then gradually returns to its baseline level. The, autoregulatory mechanism responsible is guided by several metabolic factors, including carbon dioxide, oxygen tension, hydrogen, ions, lactate, potassium ions, and adenosine. Adenosine, a potent, vasodilator and a degradation product of adenosine triphosphate,, accumulates in the interstitial space and relaxes vascular smooth, muscle. This results in vasomotor relaxation, coronary vasodilation, and increased blood flow. Another substance that plays an, important role is nitric oxide, which is produced by the endothelium. Without the endothelium, coronary arteries do not autoregulate, suggesting that the mechanism for vasodilation and reactive, hyperemia is endothelium dependent., Extravascular compression of the coronaries during systole also, plays an important role in the regulation of blood flow. During, systole, the intracavitary pressures generated in the LV wall exceed, intracoronary pressure, and blood flow is impeded. Hence, approximately 60% of coronary blood flow occurs during diastole. During, exercise, increased heart rate and reduced diastolic time can compromise flow time, but this can be offset by vasodilatory mechanisms of the coronary vessels. Buildup of atherosclerotic plaques and, fixed coronary occlusion significantly impair coronary arterial compensatory mechanisms while heart rate is elevated. This forms the, basis for exercise-induced stress tests, in which abnormal physiologic, responses to increased physical activity unmask underlying CAD., , HISTORY OF CORONARY ARTERY BYPASS, SURGERY, One of the first attempts at myocardial revascularization was made, by Arthur Vineberg from Canada.4 He operated on a series of, patients who presented with symptoms of myocardial ischemia, and implanted the left internal mammary artery (LIMA) into the, myocardium by creating a pocket. The operation did not entail a, direct anastomosis to any coronary vessel and was performed on a, beating heart through a left anterolateral thoracotomy. Dr. David, , 1681, , TABLE 60.2 Evolution of surgical coronary, , artery interventions: timeline., 1950, , A. Vineberg, , 1953, , J. H. Gibbon, , 1962, 1964, 1964, , F. M. Sones, M. E. DeBakey, T. Sondergaard, , 1964, , D. A. Cooley, , 1968, , R. Favoloro, , 1973, 1979, , V. Subramanian, G. Buckberg, , Direct implantation of mammary artery into, myocardium, First successful use of cardiopulmonary bypass, machine, Successful cineangiography, First successful coronary artery bypass grafting, Introduced routine use of cardioplegia for, myocardial protection, Routine use of normothermic arrest for all, cardiac cases, First large series showing success of coronary, artery bypass grafting, Beating-heart coronary artery bypass grafting, First use of blood cardioplegia as preferred, method for arrested myocardial protection, , Sabiston, Jr., performed the first CABG with venous grafting on, April 4, 1962, in a patient with an occluded RCA. A saphenous, vein graft (SVG) was taken from the leg and anastomosed from, the ascending aorta to the RCA. Unfortunately, the patient had a, stroke and died shortly thereafter. Michael DeBakey performed a, successful aortocoronary SVG in 1964. At the Cleveland Clinic,, Mason Sones, who is credited with inventing cardiac catheterization, and cardiac surgeon, Rene Favaloro, helped establish CABG, surgery as a planned and consistent therapy in patients with angiographically documented CAD., The development of the heart-lung machine and its successful, clinical use by John Heysham Gibbon in the 1950s, along with, the advancement of cardioplegia techniques in later years by Gerald Buckberg, allowed surgeons to perform coronary anastomosis, on an arrested (nonbeating) heart with a relatively bloodless field,, thus increasing the safety and accuracy of the coronary bypass., In the 1990s, the advent of devices that could atraumatically stabilize the heart provided another pathway for the development, of off-pump techniques of myocardial revascularization. Today,, an armamentarium of techniques ranging from conventional onpump CABG to minimally invasive robotic and percutaneous approaches is available to manage CAD. Table 60.2 summarizes the, timeline of major historical events in the development of surgery, for myocardial revascularization., , ATHEROSCLEROTIC CORONARY ARTERY DISEASE, Coronary atherosclerosis is a process that begins early in the patient’s life. Epicardial conductance vessels are the most susceptible, and intramyocardial arteries, the least. Risk factors for atherosclerosis include elevated plasma levels of total cholesterol and lowdensity lipoprotein cholesterol, cigarette smoking, hypertension,, diabetes mellitus, advanced age, low plasma levels of high-density, lipoprotein cholesterol, and family history of premature CAD., Epidemiologic evidence suggests that coronary artery atherosclerosis is closely linked to the metabolism of lipids, specifically, low-density lipoprotein cholesterol. The development of lipid-lowering drugs has resulted in a significant reduction in mortality. In, one observational study of patients who received statin therapy and, were known to have CAD, statin treatment was associated with, improved survival in all age groups. The greatest survival benefit, was found in those patients in the highest quartile of plasma levels, of high-sensitivity C-reactive protein, a biomarker of inflammation, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1682, , SECTION XI Chest, Modality, MRI, Ultrasound, Fluorescence, PET, Target, , +, +, –, –, , +, +, +, +, , +, +, +, +, , +, –, +, +, , +, ±, –, –, , +, +, +, +, , Flow-mediated, vasodilation, , Adhesion, molecules, , Macrophages, , MMPs, Cathepsin, , Lipid core, Fibrous cap, , αvβ3 integrin, , Fibrin, Platelets αIIbβ3 integrin, Tissue factor, , Endothelial, dysfunction, , Endothelial, activation, , Inflammation, , Proteolysis, Apoptosis, , Angiogenesis, , Thrombosis, , Process, , +, +, +, +, , Thrombus, Fibrous cap, Monocyte, recruitment, , ↓NO, production, , Lipid-rich, necrotic core, , Internal elastic, lamina, , Angiogenesis, , Approximate, I, American Heart, Association lesion stage, , II, , III, , IV, , V, , αvβ3 integrin, , Apoptotic cell, , Collagen fibril, , Endothelial cell, , MMP, , Platelet, , Smooth muscle cell, , VCAM1, ICAM, selectins, , Fibrin, , VI, , Foam cell, , LDL, , FIG. 60.2 Components of atherosclerotic plaque. Thinning of the fibrous cap eventually results in plaque, rupture and extrusion of highly thrombogenic lipid-laden material into the coronary artery. This causes an acute, occlusion of the coronary artery, resulting in myocardial infarction. (Adapted from Choudhury RP, Fuster V, Fayad, ZA. Molecular, cellular and functional imaging of atherothrombosis. Nat Rev Drug Discov. 2004;3:913–925.), ICAM, Intercellular adhesion molecule; LDL, low-density lipoprotein; MMP, matrix metallopeptidases; MRI,, magnetic resonance imaging; PET, positron emission tomography; VCAM1, vascular cell adhesion molecule 1., , and CAD. Animal and human studies have demonstrated that, statin therapy also modifies the lipid composition within plaques, by lowering the amount of low-density lipoprotein cholesterol and, stabilizing the plaque through various mechanisms, including reduced macrophage accumulation, collagen degradation, reduced, smooth muscle cell protease expression, and decreased tissue factor, expression., , Pathogenesis, The primary cause of CAD is endothelial injury induced by an, inflammatory wall response and lipid deposition. There is evidence that an inflammatory response is involved in all stages of the, disease, from early lipid deposition to plaque formation, plaque, rupture, and coronary artery thrombosis. Vulnerable or high-risk, plaques that are prone to rupture have the following characteristics: a large, eccentric, soft lipid core; a thin fibrous cap; inflammation within the cap and adventitia; increased plaque neovascularity; and evidence of outward or positive vessel remodeling., Thinner fibrous caps are at a higher risk for rupture, probably because of an imbalance between the synthesis and the degradation of, the extracellular matrix in the fibrous cap that results in an overall decrease in the collagen and matrix components (Fig. 60.2). Increased, matrix breakdown caused by matrix degradation by an inflammatory, cell-mediated metalloproteinase or reduced production of extracellular matrix results in thinner fibrous caps. Not all plaque ruptures, are symptomatic; whether they are depends on the thrombogenicity, of the plaque’s components. Tissue factor within the lipid core of, , the plaque, secreted by activated macrophages, is one of the most, potent thrombogenic stimuli. Rupture of a vulnerable plaque may be, spontaneous or caused by extreme physical activity, severe emotional, distress, exposure to drugs, cold exposure, or acute infection., , Fixed Coronary Obstructions, More than 90% of patients with stable IHD (SIHD) have advanced coronary atherosclerosis caused by a fixed obstruction., Atherosclerotic plaques of the coronary arteries are concentric, (25%) or eccentric (75%). Eccentric lesions compromise only a, portion of the lumen; through vascular remodeling, the arterial, lumen may remain patent until late in the disease process. The, impact of an arterial stenosis on coronary blood flow can be appreciated in the context of the Poiseuille law. Reductions in luminal, diameter up to 60% have minimal impact on flow, but when the, cross-sectional area of the vessel has decreased by 75% or more,, coronary blood flow is significantly compromised. Clinically, this, loss of flow often coincides with the onset of exertional angina. A, 90% reduction in luminal diameter results in resting angina., , CLINICAL MANIFESTATIONS AND DIAGNOSIS OF, CORONARY ARTERY DISEASE, Clinical Presentation, Clinically, IHD has two predominant modes of presentation:, • Stable angina, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, • A,  cute coronary syndrome: ST-segment elevation myocardial infarction (STEMI) and its complications, non-STEMI, (NSTEMI), and unstable angina (UA), Anginal pain is the main presenting symptom of IHD. It typically lasts minutes. The location is usually substernal, and pain, can radiate to the neck, jaw, epigastrium, or arms. Anginal pain is, precipitated by exertion or emotional stress and relieved by rest., Sublingual nitroglycerin also usually relieves angina within 30 seconds to several minutes., On presentation, angina must be classified as stable or unstable., Patients are said to be having UA if the pain is increasing (in frequency, intensity, or duration) or occurring at rest. Such patients, should be transferred promptly to an emergency department., Patients, especially female and elderly patients, sometimes, present with atypical symptoms, such as nausea, vomiting,, midepigastric discomfort, or sharp (atypical) chest pain. In the, Women’s Ischemic Syndrome Evaluation (WISE) study, 65% of, women with ischemia presented with atypical symptoms.5, The term acute coronary syndrome has evolved to refer to a, constellation of clinical symptoms that represent myocardial ischemia. It encompasses both STEMI and NSTEMI. Myocardial, infarction (MI) often is manifested as crushing chest pain that, may be associated with nausea, diaphoresis, anxiety, and dyspnea., Symptoms of the hypoperfusion that follows MI may include dizziness, fatigue, and vomiting. Heart rate and blood pressure may, be initially normal, but both increase in response to the duration, and severity of pain. Loss of blood pressure is indicative of cardiogenic shock and indicates a poorer prognosis. At least 40% of the, ventricular mass must be involved for cardiogenic shock to occur., Mechanical complications of MI include acute ventricular septal defect (VSD), papillary muscle rupture, and free ventricular, rupture. They usually occur approximately 7 to 10 days after the, initial MI., , Physical Examination, Some clinical findings are generic and are related to the systemic, manifestations of atherosclerosis. Eye examination may reveal a copper wire sign, retinal hematoma or thrombosis secondary to vascular, occlusive disease, and hypertension. Corneal arcus and xanthelasma, are features noticed in cases of hypercholesterolemia. Other clinical, manifestations are caused by sequelae of CAD (Box 60.2)., A thorough vascular evaluation is essential for any patient who, presents with CAD because atherosclerosis is a systemic process., In addition, if surgery is being planned, the extremities should be, evaluated for any previous surgical scars or fractures that could, potentially preclude conduit harvest., , Diagnostic Testing, Biochemical Studies, Patients suspected of having an acute coronary syndrome should undergo appropriate blood testing. Levels of creatine kinase muscle and, brain subunits (CK-MB) and troponin T or I should be assessed at, least 6 to 12 hours apart. Additional laboratory tests include a complete blood count, comprehensive metabolic panel, and lipid profile, (total cholesterol, triglycerides, low-density lipoprotein cholesterol,, high-density lipoprotein cholesterol). Elevated brain natriuretic peptide and C-reactive protein levels suggest a worse outcome., Chest Radiography, The chest radiograph is helpful in identifying causes of chest, discomfort or pain other than CAD. Chest radiography does, not detect CAD directly; it only identifies sequelae, such as, , BOX 60.2, , disease., , 1683, , Sequelae of coronary artery, , Clinical Manifestations, • Abnormal neck vein pulsations, which may be seen in patients with secondor third-degree heart block or CHF, • Bradycardia—a subtle presentation of ischemia involving the right coronary territories and a possible sign of heart block, • Weak or thready pulse suggestive of ectopic or premature ventricular beats, • Third heart sound that is noted with elevated left ventricular filling pressures/CHF, • Fourth heart sound, which is commonly heard in patients with acute and, chronic CAD, • Mitral regurgitant heart murmurs caused by ischemic papillary muscles, • Ejection systolic murmur indicative of aortic stenosis, which can contribute, to coronary ischemia, • Holosystolic murmurs caused by ventricular septal rupture, • Manifestations of CHF, such as rales, hepatomegaly, right upper abdominal, quadrant tenderness, ascites, and marked peripheral and presacral edema, CAD, Coronary artery disease; CHF, congestive heart failure., , cardiomegaly, pulmonary edema, and pleural effusions, that are, indicative of heart failure. From a surgical standpoint, preoperative chest radiography is important because it can identify obvious, abnormalities, such as porcelain aorta, lung masses, effusion, and, pneumonias, that may affect further workup or prompt a change, in operative strategy., Resting Electrocardiography, A 12-lead resting electrocardiogram (ECG) should be obtained, in all patients with suspected IHD or sequelae thereof. The, ECG is evaluated for evidence of LV hypertrophy, ST-segment, depression or elevation, ectopic beats, or Q waves. In addition,, arrhythmias (atrial fibrillation or ventricular tachycardia) and, conduction defects (left anterior fascicular block, right bundle, branch block, left bundle branch block) are suggestive of CAD, and MI. Persistent ST-segment elevation or an evolving Q wave, is consistent with myocardial injury and ongoing ischemia., Fifty percent of patients with significant CAD nonetheless have, normal electrocardiographic results, and 50% of ECG recordings obtained during chest pain at rest will be normal, indicating the inaccuracy of the test. Patients with SIHD tend to, have a worse prognosis if they have the following abnormalities, on a resting ECG: evidence of prior MI, especially Q waves in, multiple leads or an R wave in V1 indicating a posterior infarction; persistent ST-T wave inversions, particularly in leads V1, to V3; left bundle branch block, bifascicular block, second- or, third-degree AV block, or ventricular tachyarrhythmia; or LV, hypertrophy.6, Functional (Stress) Tests, In patients with suspected stable ischemic CAD, functional or, stress testing is used to detect inducible ischemia. These are the, most common noninvasive tests used to diagnose SIHD (Box, 60.3). All functional tests rely on the principle of inducing cardiac ischemia by using exercise or pharmacologic stress agents,, which increase myocardial work and oxygen demand, or by causing vasodilation-elicited heterogeneity in induced coronary flow., Whether ischemia is induced, however, depends on the severity of, both the stress imposed (e.g., submaximal exercise can fail to produce ischemia) and the flow disturbance. Approximately 70% of, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1684, , SECTION XI Chest, , Stress tests to identify coronary, artery disease., BOX 60.3, , Exercise Stress ECG, • Bruce protocol, • Five 3-minute bouts of treadmill exercise, • Determines the ischemia threshold, • 12 metabolic equivalents of energy expenditure needed for complete test, • Low cost and short duration, • Highly sensitive in multivessel disease, Limitations, • Suboptimal sensitivity, • Low detection rate of one-vessel disease, • Nondiagnostic with abnormal baseline ECG, • Poor specificity in premenopausal women, • Many cannot accomplish the 12 metabolic equivalents for a complete test, or an appropriate heart rate response, Exercise and Pharmacologic Stress SPECT Perfusion, Imaging, • Simultaneous evaluation of perfusion and function, • Higher sensitivity and specificity than exercise ECG, • Quantitative image analysis, Limitations, • Long procedure time with Technetium-99m, • Higher cost, • Radiation exposure, • Poor-quality images in obese patients, Exercise and Pharmacologic Stress Echocardiography, • Higher sensitivity and specificity than exercise ECG, • Comparable value with dobutamine stress, • Short examination time, • Identification of structural cardiac abnormalities, • Simultaneous evaluation of perfusion with contrast agents, • No radiation, Limitations, • Decreased sensitivity for detection of one-vessel disease or mild stenosis, • Highly operator dependent, • No quantitative image analysis, • Poor imaging in some patients, • Infarct zone poorly defined, ECG, Electrocardiogram; SPECT, single-photon emission computed, tomography., , coronary stenoses are not detected by functional testing. Because, abnormalities of regional or global ventricular function occur later, in the ischemic cascade, they are more likely to indicate severe stenosis; thus, such abnormalities have a higher diagnostic specificity, for SIHD than do perfusion defects, such as those seen on nuclear, myocardial perfusion imaging (MPI)., Exercise versus pharmacologic testing. In patients capable, of performing routine activities of daily living without difficulty,, exercise testing is preferred to pharmacologic testing because it, induces greater physiologic stress than drugs can. This may make, exercise testing the better means of detecting ischemia as well as, providing a correlation to a patient’s daily symptom burden and, physical work capacity not offered by pharmacologic stress testing., , The treadmill protocols initiate exercise at 3.2 to 4.7 metabolic, equivalents of the task (METs) and increase by several METs every 2 to 3 minutes of exercise (e.g., modified or standard Bruce, protocol). Performance of most activities of daily living requires, approximately 4 to 5 METs of physical work. Patients unable to, perform moderate physical activity and those with disabling comorbidities should undergo pharmacologic stress imaging instead., Diagnostic accuracy of stress testing for SIHD, , Exercise electrocardiography (Bruce protocol). The criterion, for diagnosis of ischemia is an ECG showing 1-mm horizontal or, downsloping (at 80 milliseconds after the J point) ST-segment depression at peak exercise. The diagnostic sensitivity and specificity, of this sign is 61%. It is lower in women than in men7,8 and lower, than that of stress imaging modalities., Exercise and pharmacologic stress echocardiography. These, tests rely on detecting new or worsening wall motion abnormalities and changes in global LV function during or immediately, ­after stress. In addition to the detection of inducible wall motion, abnormalities, most stress echocardiography includes screening, images to evaluate resting ventricular function and valvular abnormalities., Pharmacologic stress echocardiography is usually performed, using dobutamine with an end point of producing wall motion, abnormalities. Vasodilator agents such as adenosine can be used, to the same effect., The diagnostic sensitivity is 70% to 85% for exercise and 85%, to 90% for pharmacologic stress echocardiography. The use of intravenous ultrasound contrast agents, by improving endocardial, border delineation, can result in improved diagnostic accuracy., Exercise and pharmacologic stress nuclear myocardial perfusion imaging. Myocardial perfusion single-photon emission, computed tomography (SPECT) generally is performed with, rest and with stress. Technetium-99m agents are generally used;, one of these, thallium Tl 201, has limited applications (e.g., viability) because of its higher radiation exposure. Pharmacologic, stress is generally induced with vasodilator agents administered by, continuous infusion (adenosine, dipyridamole) or bolus injection, (regadenoson)., The diagnostic end point of nuclear MPI is a reduction in myocardial perfusion after stress. The diagnostic accuracy for detection, of obstructive CAD of exercise and pharmacologic stress nuclear, MPI has been studied in detail.9,10 Studies suggest that nuclear, MPI’s sensitivity ranges from 82% to 88% for exercise and 88% to, 91% for pharmacologic stress, and its diagnostic specificity ranges, from 70% to 88% and 75% to 90% for exercise and pharmacologic stress nuclear MPI, respectively., For myocardial perfusion SPECT, global reductions in myocardial perfusion, such as in the patients with left main or three-vessel, CAD, can result in balanced reduction and an underestimation of, ischemic burden., Echocardiography, From a surgical standpoint, most patients with SIHD should undergo preoperative echocardiography. Echocardiography provides, information not only for surgical planning but also regarding, prognosis. A resting left ventricular ejection fraction (LVEF) of, 35% is associated with an annual mortality rate of 3% per year., Resting two-dimensional Doppler echocardiography provides information on cardiac structure and function, including identifying, the mechanism of heart failure and differentiating systolic from, diastolic LV dysfunction. Echocardiography can identify LV or, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, , 1685, , left atrial dilation, identify aortic stenosis (a potential non-CAD, cause of angina-like chest pain), measure pulmonary artery pressure, quantify mitral regurgitation, identify LV aneurysm, identify, LV thrombus (which increases the risk of death), and measure LV, mass and the ratio of wall thickness to chamber radius—all of, which predict cardiac events and mortality.11,12, Multidetector Computed Tomography, From a surgical standpoint, multidetector computed tomography, (CT) has two pertinent applications in the management of CAD:, to detect CAD and to inform the planning of grafting sites for, CABG by providing additional information about coronary lesions, especially calcification and the course of coronary arteries., It also gives additional pertinent information about aortic disease, and calcification, which might profoundly influence surgical decision making. However, the timing of cardiac CT should be carefully weighed against the risk of renal injury as a result of contrast, nephropathy. Although revascularization decisions are currently, made on the basis of coronary angiography, there have been tremendous improvements in temporal and spatial resolution of cardiac CT that make it useful for this purpose as well. Coronary, CT angiography (CCTA) can now provide high-quality images, of the coronary arteries.13 When it is performed with 64-slice CT,, CCTA has a sensitivity of 93% to 97% and a specificity of 80% to, 90% for detecting obstructive CAD.14–17, The potential advantages of CCTA over standard functional, testing for CAD screening include the high negative predictive, value of CCTA for obstructive CAD. This can reassure caregivers, that it is a sensible strategy to provide guideline-directed medical, therapy (GDMT) and to defer consideration of revascularization., Among the greatest potential advantages of CCTA over conventional angiography, in addition to documentation of stenotic, lesions, is that CCTA can assess remodeling and identify nonobstructive plaque, including calcified, noncalcified, and mixed, plaque.18, , FIG. 60.3 Left coronary angiogram showing hemodynamically severe, lesions in the left anterior descending artery (small arrow) and the circumflex artery (large arrow)., , Magnetic Resonance Imaging, Myocardial first-pass perfusion magnetic resonance imaging has, been considered a good alternative to nuclear cardiac ischemia, and viability testing. However, the procedure has not gained widespread popularity because special training and expertise are required to perform this type of imaging and to interpret the results., , Cardiac Catheterization and Intervention, Coronary catheterization is the “gold standard” for diagnosis of, CAD. Coronary angiography defines coronary anatomy, including the location, length, diameter, and contour of the epicardial, coronary arteries; the presence and severity of coronary luminal, obstructions; the nature of the obstruction; the presence and extent, of angiographically visible collateral flow; and coronary blood flow., The classification for defining coronary anatomy that is still, used today was developed for the Coronary Artery Surgery Study, (CASS)19 and further modified by the Balloon Angioplasty Revascularization Investigation (BARI) study group.20 This scheme, assumes that there are three major coronary arteries: the LAD, the, circumflex, and the RCA, with a right-dominant, left-dominant,, or codominant circulation. The extent of disease is defined as, one-vessel, two-vessel, three-vessel, or left main disease; a luminal diameter reduction of at least 70% is considered to be significant stenosis (Figs. 60.3 and 60.4). Left main disease, however,, is defined as stenosis of at least 50% (Fig. 60.5). Despite being, recognized as the traditional gold standard for clinical assessment, , FIG. 60.4 Right coronary angiogram showing hemodynamically significant lesion (arrow). The right coronary artery terminates as a posterior descending artery in the right dominant system., , of coronary atherosclerosis, this test is not without limitations., There is marked variation in interobserver reliability, and investigators have found only 70% overall agreement among readers, with regard to the severity of stenosis; this was reduced to 51%, when restricted to coronary vessels rated as having some stenosis, by any reader. Also, angiography provides only anatomic data and, is not a reliable indicator of the functional significance of a given, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1686, , SECTION XI Chest, Fractional Flow Reserve, Angiography can underestimate the severity of CAD, especially, LCA disease.24,25 This underestimation may be due to the lack of, a reference segment or to very ostial or distal disease. Therefore,, in cases with intermediate lesions, FFR has emerged as a helpful, modality., FFR is measured by passing a sensor guidewire into the LAD or, circumflex vessels for LCA lesions. Thereafter, the flow reserve in, the artery is checked by using adenosine to induce hyperemia in the, coronary system. An FFR below 0.75 is considered to signify ischemia-producing lesions. Some studies have used a threshold of 0.8., , FIG. 60.5 Coronary angiogram showing critical left main coronary artery, stenosis (arrow)., , coronary stenosis unless a technique such as fractional flow reserve, (FFR) is used to provide information about the physiologic effects, of the stenosis. FFR is measured by passing a sensor guidewire, into the LAD or circumflex vessels for LCA lesions. Thereafter,, the flow reserve in the artery is checked by using adenosine to, induce hyperemia in the coronary system, which is discussed in, the next section on FFR. In addition, angiography cannot distinguish between vulnerable and stable plaques. In angiographic, studies performed before and after acute events and early after, MI, plaques causing UA and MI commonly were found to be, 50% obstructive before the acute event and were therefore angiographically “silent.”19,20 Diagnostic testing methods to identify, vulnerable plaque and, therefore, the patient’s risk of MI are being, intensely studied, but no gold standard has yet emerged. Despite, these limitations of coronary angiography, the extent and severity, of CAD as revealed angiographically remain important predictors, of long-term patient outcomes.21,22, In the CASS registry23 of medically treated patients, the 12year survival rate of patients with normal coronary arteries was, 91% compared with 74% for those with one-vessel disease, 59%, for those with two-vessel disease, and 40% for those with threevessel disease., Importantly, besides informing the decision whether to intervene surgically or with percutaneous coronary intervention (PCI),, the salient characteristics of coronary lesions (e.g., stenosis severity, length, and complexity and presence of thrombus), the number of lesions threatening regions of contracting myocardium, the, effect of collaterals, and the volume of jeopardized viable myocardium also can afford some insight into the potential consequences, of subsequent vessel occlusion and therefore the haste with which, surgery should be scheduled., PCI techniques in current use include balloon dilation, stentsupported dilation, atherectomy and plaque ablation with a variety of devices, thrombectomy with aspiration devices, specialized, imaging, and physiologic assessment with intracoronary devices., Coronary artery stents were the first substantial breakthrough, in the prevention of restenosis after angioplasty. Although stent, recoil and compression are not completely insignificant problems,, the greatest cause of lumen loss in stented coronary arteries is neointimal hyperplasia. This is the principal mechanism of in-stent, stenosis and results from inappropriate cell proliferation—hence,, the advent of cytotoxic drug-eluting stents (DESs)., , Intravascular Ultrasonography, Intravascular ultrasonography (IVUS) provides high-quality crosssectional images of the coronary system. It is done by inserting an, IVUS wire into the LAD or circumflex artery and gradually pulling it out while obtaining real-time images of the coronary system., In indeterminate lesions of the LCA, an IVUS minimum luminal, diameter of 2.8 or a minimum luminal area of 6 mm2 suggests a, physiologically significant lesion., Hybrid Imaging, Hybrid imaging has the potential of taking coronary artery assessment one step further by combining the advantages of two, different modalities to give both anatomic and physiologic information in one snapshot. Hybrid imaging can combine positron, emission tomography (PET) and CT or SPECT and CT, thus, allowing combined anatomic and functional testing. In addition,, novel scanning techniques make it possible to use CCTA alone, to assess perfusion and FFR, in addition to coronary anatomy., Interestingly, these combined assessments can produce a fused, image in which physiologic information about flow is combined, with information about the anatomic extent and severity of CAD,, plaque composition, and arterial remodeling. Robust evidence to, support the use of hybrid imaging is lacking at this point, despite, its reported accuracy in predicting cardiac events with both ischemic and anatomic markers. The strength of combined imaging, is that it provides anatomic information to guide the interpretation of ischemic and scarred myocardium as well as information, to guide therapeutic decision-making. Hybrid imaging also can, overcome technical limitations of myocardial perfusion SPECT, or myocardial perfusion PET by providing anatomic correlates to, guide interpretative accuracy, and it can provide the functional, information that an anatomic technique like CCTA or magnetic, resonance angiography lacks; however, use of hybrid techniques, requires increasing the radiation dose., , INDICATIONS FOR CORONARY ARTERY, REVASCULARIZATION, Per the most current American College of Cardiology/American, Heart Association guidelines, the only class Ia indication for PCI, is acute STEMI. In all other indications, CABG has superior class, based on current evidence (Table 60.3). These guidelines are based, on the existing literature, which spans four decades. Many of the, studies on which current recommendations are based were conducted in the 1970s and 1980s., , Coronary Artery Bypass Grafting Versus, Contemporaneous Medical Therapy, In the 1970s and 1980s, three landmark randomized controlled, trials (RCTs) established the survival benefit of CABG compared, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, , 1687, , TABLE 60.3 Guidelines for coronary revascularization., CORONARY ARTERY LESIONS, Unprotected Left Main, CABG, PCI, , RECOMMENDATIONS, I, IIa—For SIHD when both of the following are present:, • Cardiac catheterization reveals a low risk of PCI procedural complications, with a high likelihood of good long-term outcome (low SYNTAX score 22,, ostial or trunk left main)., • Significantly increased risk of adverse surgical outcomes (STS-predicted risk, of operative mortality 5%), IIa—For UA/NSTEMI if not a CABG candidate, IIa—For STEMI when distal coronary flow is TIMI flow grade 3 and PCI can be, performed more rapidly and safely than CABG, IIb—For SIHD when both of the following are present:, • Cardiac catheterization reveals a low to intermediate risk of PCI procedural, complications and an intermediate to high likelihood of good long-term, outcome (low–intermediate SYNTAX score of 33, bifurcation left main), • Increased risk of adverse surgical outcomes (moderate–severe COPD, disability, from prior stroke, or prior cardiac surgery; STS-predicted operative mortality 2%), III: Harm—For SIHD in patients (versus performing CABG) with unfavorable, anatomy for PCI and who are good candidates for CABG, , Three-Vessel Disease With or Without Proximal LAD Artery Disease, CABG, I, IIa—It is reasonable to choose CABG over PCI in patients with complex threevessel CAD (SYNTAX score 22) who are good candidates for surgery, PCI, IIb—Of uncertain benefit, Two-Vessel Disease With Proximal LAD Artery Disease, CABG, I, PCI, IIb—Of uncertain benefit, Two-Vessel Disease Without Proximal LAD Artery Disease, CABG, IIa—With extensive ischemia, IIb—Of uncertain benefit without extensive ischemia, PCI, IIb—Of uncertain benefit, One-Vessel Proximal LAD Artery Disease, CABG, IIa—With LIMA for long-term benefit, PCI, IIb—Of uncertain benefit, One-Vessel Disease Without Proximal LAD Artery Involvement, CABG, III: Harm, PCI, III: Harm, LV Dysfunction, CABG, IIa—LVEF 35% to 50%, IIb—LVEF 35% without significant left main CAD, PCI, Insufficient data, Survivors of Sudden Cardiac Death With Presumed IschemiaMediated VT, CABG, I, PCI, I, No Anatomic or Physiologic Criteria for Revascularization, CABG, III: Harm, PCI, III: Harm, Class I: benefit ≫> risk. Procedure should be performed., Class IIa: benefit ≫ risk. Additional studies with focused objectives needed. It is reasonable to perform procedure., Class IIb: benefit ≥ risk. Additional studies with broader objectives and additional registry data may be needed. Procedure treatment may be, considered., Class III: no benefit or, Class III: harm, From Reference 28., CABG, Coronary artery bypass grafting (major adverse events occurred less frequently with CABG); CAD, coronary artery disease; COPD, chronic, obstructive pulmonary disease; LAD, left anterior descending; LIMA, left internal mammary artery; LV, left ventricle; LVEF, left ventricular ejection, fraction; PCI, percutaneous coronary intervention; SIHD, stable ischemic heart disease; STEMI, ST-elevation myocardial infarction; STS, Society, of Thoracic Surgeons; SYNTAX, Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery; TIMI, thrombolysis in, myocardial infarction; UA/NSTEMI, unstable angina/non–ST-elevation myocardial infarction; VT, ventricular tachycardia., Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1688, , SECTION XI Chest, , with medical therapy without revascularization in certain patients with SIHD: the Veterans Affairs Cooperative Study,26 European Coronary Surgery Study,27 and CASS.22 Subsequently, a, 1994 metaanalysis of seven studies in which 2649 patients were, randomly assigned to medical therapy or CABG24 showed that, CABG offered a survival advantage over medical therapy for patients with LCA or three-vessel CAD. The studies also established, that CABG is more effective than medical therapy for relieving, anginal symptoms. These studies have been replicated only once, during the past decade. In Medicine, Angioplasty, or Surgery, Study II (MASS II), patients with multivessel CAD who were, treated with CABG were less likely than those treated with medical therapy to have a subsequent MI, to need additional revascularization, or to experience cardiac death in the 10 years after, randomization.25 Surgical techniques and medical therapy have, improved substantially during the intervening years. Some critics, state that if CABG were compared with GDMT in RCTs today,, the relative benefits in terms of survival and angina relief observed, several decades ago might no longer be observed. However, it, should also be understood that the concurrent administration of, GDMT, which most post–cardiac surgery patients now receive,, may also substantially improve long-term outcomes in patients, treated with CABG in comparison with those receiving medical therapy alone. Thus, the survival difference might still favor, CABG over GDMT., , Percutaneous Coronary Intervention Versus Medical, Therapy, Although contemporary interventional treatments have lowered, the risk of restenosis compared with earlier techniques, metaanalyses have not shown that the use of bare-metal stents (BMS), confers a survival advantage over balloon angioplasty26,27 or that, the use of DES confers a survival advantage over BMS.28 Evaluation of trials of PCI conducted during the last 30 years show that,, despite improvements in PCI technology and pharmacotherapy,, PCI has not reduced the risk of death or MI in patients without, recent acute coronary syndrome. The findings from individual, studies and systematic reviews of PCI versus medical therapy can, be summarized as follows:, • PCI reduces the incidence of angina, • PCI has not been demonstrated to improve survival in stable, patients, • PCI may increase the short-term risk of MI, • PCI does not lower the long-term risk of MI, , Coronary Artery Bypass Grafting Versus Balloon, Angioplasty or Bare-Metal Stents, From a review of multiple RCTs comparing CABG with balloon, angioplasty or BMS, the following conclusions can be drawn28:, • Survival was similar for CABG and PCI (with balloon angioplasty or BMS) at 1 year and 5 years. Survival was similar for, CABG and PCI in patients with one-vessel CAD (including, those with disease of the proximal portion of the LAD artery), or with multivessel CAD, • Incidence of MI was similar at 5 years, • Procedural stroke occurred more commonly with CABG than, with PCI (1.2% vs. 0.6%), • Relief of angina was more effective with CABG than with PCI, at 1 year and 5 years, • At 1 year after the index procedure, repeated coronary revascularization was performed less often after CABG than after, PCI (3.8% vs. 26.5%). This was also found after 5 years of, , follow-up (9.8% vs. 46.1%). This difference was more pronounced with balloon angioplasty than with BMS., , Coronary Artery Bypass Grafting Versus Drug-Eluting, Stents, Multiple observational studies comparing CABG and DES implantation have been published, but most of them had short (12–, 24 months) follow-up periods. A large RCT comparing CABG, and DES implantation in patients with three-vessel or left main, disease has been published, called the Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery, (SYNTAX) trial, in which 1800 patients (of a total of 4337 who, were screened) were randomly assigned to undergo DES implantation or CABG. Major adverse cardiac events (a composite of, death, stroke, MI, or repeated revascularization during the 3 years, after randomization) occurred less frequently in CABG patients, (20.2%) than in DES patients (28.0%; P = 0.001). The rates of, death and stroke were similar; however, MI (3.6% for CABG,, 7.1% for DES) and repeated revascularization (10.7% for CABG,, 19.7% for DES) were more likely to occur with DES implantation. In SYNTAX, the extent of CAD was assessed by using the, SYNTAX score, which is based on the location, severity, and extent of coronary stenoses, with a low score indicating less complicated anatomic CAD. In post hoc analyses, a low score was, defined as 22 or lower; intermediate, 23 to 32; and high, 33 or, higher. The occurrence of major adverse cardiac events correlated, with the SYNTAX score for DES patients but not for those undergoing CABG. At 12-month follow-up, the primary end point was, similar for CABG and DES in those with a low SYNTAX score., In contrast, major adverse cardiac events occurred more often after, DES implantation than after CABG in those with an intermediate or high SYNTAX score. At 3 years of follow-up, the mortality, rate was greater in patients with three-vessel CAD treated with, PCI than in those treated with CABG (6.2% vs. 2.9%). The differences in major adverse cardiac events of those treated with PCI, or CABG increased with an increasing SYNTAX score. Although, the utility of using a SYNTAX score in everyday clinical practice, remains uncertain, it seems reasonable to conclude from SYNTAX, and other data that the outcomes of patients undergoing PCI or, CABG in those with relatively uncomplicated and lesser degrees, of CAD are comparable, whereas in those with complex and diffuse CAD, CABG appears to be preferable. At 5-year follow-up, a, similar trend was seen, with CABG superior to PCI for intermediate or high SYNTAX scores.29, , Left Main Coronary Artery Disease, CABG or PCI Versus Medical Therapy for Left Main CAD, CABG confers a survival benefit over medical therapy in patients, with LCA CAD. Subgroup analyses from RCTs performed three, decades ago demonstrated a 66% reduction in relative risk of, death with CABG, with the benefit extending to 10 years.23,24, Studies Comparing PCI Versus CABG for Left Main CAD, Of all patients undergoing coronary angiography, approximately, 4% are found to have LCA CAD, 80% of whom have s­ ignificant, (70% diameter) stenoses in other epicardial coronary arteries., Published cohort studies have found that major clinical o­ utcomes, for ostial LCA are similar with PCI or CABG 1 year after revascularization and that mortality rates are similar at 1 year, 2, years, and 5 years of follow-up; however, the risk of needing target ­vessel revascularization is significantly higher with stenting, than with CABG., , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, Multiple RCTs have looked at this topic: the SYNTAX trial,29, the Study of Unprotected Left Main Stenting versus Bypass Surgery (LE MANS) trial, the Premier of Randomized Comparison, of Bypass Surgery versus Angioplasty Using Sirolimus-Eluting, Stent in Patients with Left Main Coronary Artery Disease (PRECOMBAT) trial, the Percutaneous Coronary Angioplasty Versus, CABG in Treatment of Unprotected Left Main Stenosis (NOBLE) trial,30 and the Everolimus-Eluting Stents or Bypass Surgery, for Left Main Coronary Artery Disease (EXCEL) trial.31 The results from these RCTs suggest (but do not definitively prove) that, major clinical outcomes in selected patients with LCA CAD are, similar with CABG and PCI at 1- to 2-year follow-up, but repeated revascularization rates are higher after PCI than after CABG., RCTs with extended follow-up of 5 years are required to provide, definitive conclusions about the optimal treatment of LCA CAD., In the NOBLE trial comparing PCI versus CABG, Kaplan-Meier, 5-year estimates of major adverse cardiac event (MACE) were 28%, for PCI (121 events) and 18% for CABG (80 events) (hazard ratio, 1.51; 95% confidence interval, 1.13–2.00), exceeding the limit, for noninferiority, and CABG was significantly better than PCI (P, = 0.0044). As-treated estimates were 28% versus 18% (1.48, 1.11–, 1.98; P = 0.0069). Comparing PCI with CABG, 5-year estimates, were 11% versus 9% (1.08, 0.67–1.74; P = 0.84) for all-cause mortality, 6% versus 2% (2.87, 1.40–5.89; P = 0.0040) for nonprocedural MI, 15% versus 10% (1.50, 1.04–2.17; P = 0.0304) for any, revascularization, and 5% versus 2% (2.20, 0.91–5.36; P = 0.08) for, stroke.30, Revascularization Options for LCA CAD, Although CABG has been considered the gold standard for unprotected LCA CAD revascularization, PCI has more recently, emerged as a possible alternative mode of revascularization in carefully selected patients. Lesion location is an important determinant when PCI is considered for unprotected LCA CAD. Stenting, of the LCA ostium or trunk is more straightforward than treatment of distal bifurcation or trifurcation stenoses, which generally requires a greater degree of operator experience and expertise., In addition, PCI of bifurcation disease is associated with higher, restenosis rates than PCI of disease confined to the ostium or, trunk. Although lesion location influences technical success and, long-term outcomes after PCI, location exerts a negligible influence on the success of CABG. In subgroup analyses, patients with, LCA CAD and a SYNTAX score of 33 with more complex or, extensive CAD had a higher mortality rate with PCI than with, CABG. Physicians can estimate operative risk for all CABG candidates by using a standard instrument, such as the risk calculator from the Society of Thoracic Surgeons (STS) database. These, considerations are important factors when one is choosing among, revascularization strategies for unprotected LCA CAD and have, been factored into revascularization recommendations. Use of a, Heart Team approach has been recommended in cases in which, the choice of revascularization is not straightforward. The patient’s, ability to tolerate and to comply with dual antiplatelet therapy, is also an important consideration in revascularization decisions., Experts have recommended immediate PCI for unprotected, LCA CAD in the setting of STEMI. The impetus for such a, strategy is greatest when LCA CAD is the site of the culprit lesion, antegrade coronary flow is diminished (e.g., thrombolysis, in MI flow grade 0, 1, or 2), the patient is hemodynamically unstable, and it is believed that PCI can be performed more quickly, than CABG. When possible, the interventional cardiologist and, cardiac surgeon should decide together on the optimal form of, , 1689, , revascularization for these patients, although it is recognized that, they are usually critically ill and therefore not amenable to a prolonged deliberation or discussion of treatment options., , Proximal LAD Artery Disease, Multiple studies have suggested that CABG confers a survival advantage over contemporaneous medical therapy for patients with, disease in the proximal segment of the LAD artery. Cohort studies, and RCTs, as well as collaborative analyses and metaanalyses, have, shown that PCI and CABG result in similar survival rates in these, patients., , Completeness of Revascularization, Most patients undergoing CABG receive complete or nearly, complete revascularization, which seems to influence long-term, prognosis positively.32,33 In contrast, complete revascularization is, accomplished less often in patients receiving PCI (e.g., in 70% of, patients), and the extent to which the incomplete initial revascularization influences outcome is less clear. Rates of late survival, and survival free of MI appear to be similar in patients with and, without complete revascularization after PCI. Nevertheless, the, need for subsequent CABG is usually higher in those whose initial, revascularization procedure was incomplete (compared with those, with complete revascularization) after PCI., , Left Ventricular Systolic Dysfunction, Several older studies and a metaanalysis of the data from these, studies reported that patients with LV systolic dysfunction (predominantly mild to moderate in severity) had better survival with, CABG than with medical therapy alone. In the Surgical Treatment, for Ischemic Heart Failure (STICH) trial of CABG and GDMT, in patients with an LVEF of 35% with or without viability testing, both treatments resulted in similar rates of survival (i.e., freedom from death from any cause, the study’s primary outcome), after 5 years of follow-up. In the same study at 10 years, the rates, of death from any cause, death from cardiovascular causes, and, death from any cause or hospitalization for cardiovascular causes, were significantly lower among patients who underwent CABG, in addition to receiving medical therapy than among those who, received medical therapy.34,35, Only limited data are available comparing PCI with medical, therapy in patients with LV systolic dysfunction. The data that, exist at present on revascularization in patients with CAD and, LV systolic dysfunction are more robust for CABG than for PCI,, although data from contemporary RCTs in this population of patients are lacking., The choice of revascularization method in patients with CAD, and LV systolic dysfunction is best based on clinical variables, (e.g., coronary anatomy, presence of diabetes mellitus, presence, of chronic kidney disease), magnitude of LV systolic dysfunction,, preferences of the patient, clinical judgment, and consultation between the interventional cardiologist and the cardiac surgeon., , Revascularization Options for Previous CABG, In patients with recurrent angina after CABG, repeated revascularization is most likely to improve survival in patients at highest risk,, such as those with obstruction of the proximal LAD artery and, extensive anterior ischemia. Patients with ischemia in other locations and those with a patent LIMA to the LAD artery are unlikely, to experience a survival benefit from repeated revascularization.36, Cohort studies comparing PCI and CABG among post-CABG, patients report similar rates of midterm and long-term survival, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1690, , SECTION XI Chest, , after the two procedures. In patients with previous CABG who, are referred for revascularization for medically refractory ischemia,, factors that may support the choice of repeated CABG include vessels unsuitable for PCI, multiple diseased bypass grafts, availability, of the internal mammary artery (IMA) for grafting of chronically, occluded coronary arteries, and good distal targets for bypass graft, placement. Factors favoring PCI over CABG include limited areas, of ischemia causing symptoms, suitable PCI targets, patent graft, to the LAD artery, poor CABG targets, and comorbid conditions., , Unstable Angina/Non–ST-Segment Elevation Myocardial, Infarction, The main difference between treating a patient with SIHD and a, patient with UA/NSTEMI is that the impetus for revascularization, is stronger in the treatment of UA/NSTEMI because myocardial, ischemia occurring as part of an acute coronary syndrome is potentially life-threatening, and associated angina symptoms are more, likely to be reduced with a revascularization procedure than with, GDMT.37 Thus, the indications for revascularization are strengthened by the acuity of presentation, the extent of ischemia, and the, likelihood of achieving full revascularization. The choice of revascularization method is generally dictated by the same considerations, used to decide between PCI or CABG for patients with SIHD., , ST-Segment Elevation Myocardial Infarction–Acute, Myocardial Infarction, Percutaneous Coronary Intervention Versus Medical, Management for Acute Myocardial Infarction, In general, PCI confers a greater survival advantage than thrombolytics as an initial treatment for STEMI–acute MI (AMI), and, the use of delayed PCI as an adjunct to therapy, including therapy, with thrombolytics, does not affect survival. In the Global Use of, Strategies to Open Occluded Coronary Arteries in Acute Coronary Syndromes (GUSTO) IIb trial,38 the 30-day rate of the composite end point of death, nonfatal MI, and nonfatal disabling, stroke was 9.6% for PCI patients and 13.7% for recipients of, thrombolytics., Prospective observational data collected from the Second National Registry of Myocardial Infarction between June 1994 and, March 1998 included data from a cohort of 27,080 consecutive, patients with AMI associated with ST-segment elevation or left, bundle branch block. These patients were all treated with primary, angioplasty. The study revealed that the adjusted odds of mortality were significantly higher (62% vs. 41%) for patients with, door-to-balloon times longer than 2 hours. The longer the doorto-balloon time, the higher the mortality risk, emphasizing that, door-to-balloon time has a significant impact on outcomes for, patients with AMI.39, On the basis of this evidence, PCI facilities have been required, to establish a target door-to-balloon time of no longer than 90, minutes. Depending on the available facilities in a particular region, it is the responsibility of emergency medical services personnel to determine whether that goal can be achieved by transferring, the patient to a PCI-capable facility. If this cannot be accomplished, a medical management strategy should be considered,, with the goal being a door-to-needle time of 30 minutes or less.40, Role of Coronary Artery Bypass Grafting, Although an increasing number of patients undergo catheterization early after AMI, the initial treatment is directed by the, interventionalist, which has significantly diminished the role of, , emergency CABG. In general, patients who undergo CABG early, after AMI are sicker, and efforts to improve myocardial function, are typically refractory to medical therapy. These patients typically, have a higher incidence of comorbidities and are more likely to, require intraaortic balloon pump (IABP) insertion. The optimal, timing of CABG after AMI is not well established. A review of, California discharge data identified 9476 patients who were hospitalized for AMI and subsequently underwent CABG. Of these,, 4676 (49%) were in the early CABG group and 4800 (51%) were, in the late CABG group. The mortality rate was highest (8.2%), among patients who underwent CABG on day 0 and declined to, a nadir of 3.0% among patients who underwent CABG on day, 3. The mean time to CABG was 3.2 days. Early CABG was an, independent predictor of mortality, suggesting that CABG may, best be deferred for 3 days or more after admission for AMI in, nonurgent cases.41, The Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock (SHOCK) trial has shown the survival, advantage of emergency revascularization versus initial medical stabilization in patients in whom cardiogenic shock developed after, AMI. A subanalysis that compared the effects of PCI and CABG, on 30-day and 1-year survival showed that survival rates were similar at both time points. Among SHOCK trial patients randomly, assigned to undergo emergency revascularization, those treated, with CABG had a greater prevalence of diabetes and worse CAD, than those treated with PCI. However, survival rates were similar., In patients with AMI, CABG is usually performed in conjunction with an operation to treat a specific complication, such as, refractory postinfarction angina, papillary muscle rupture with, mitral regurgitation, and infarction VSD. The rationale for urgent, or emergent surgery is often based on high early mortality risk, from mechanical complications., , Preoperative Evaluation, The success of coronary artery revascularization depends on proper workup and patient selection. Currently, a multidisciplinary approach with cardiologists and cardiac surgeons is needed to give, the patient the most appropriate form of revascularization based, on guidelines (Fig. 60.6). Comorbidities that affect CABG outcomes and that are typically incorporated into risk models include, age, gender, urgency of the procedure, ejection fraction, need for, mechanical circulatory support, MI, smoking status, use of immunosuppressive drugs, prior coronary interventions, hypertension,, diabetes, peripheral vascular disease (PVD), and cerebrovascular, disease. In addition, the severity of angina, as designated by the, Canadian Cardiovascular Society classification of angina, and the, New York Heart Association classification of congestive heart failure (CHF) are important risk variables., The following are essential components of a preoperative workup for CABG patients:, • Detailed history and physical examination, including conduit, evaluation, • Review of medications, including angiotensin-converting enzyme inhibitors, beta blockers, antiplatelet agents, and anticoagulants, • Carotid duplex ultrasonography in patients who have clinical, bruit or are at high risk for cerebrovascular disease, • Cardiac echocardiography to evaluate ventricular function and, the structural integrity of valves and chambers, • Cardiac viability study in patients with depressed LVEF, chronic total occlusions, frailty, and high-risk operations to decide, between PCI and CABG, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, , 1691, , PRESENCE OF CAD, With anatomic indication for revascularization, , Surgical risk stratification by multidisciplinary team, Prohibitive or high risk for CABG such as:, NO, , ADVANCED COPD on HOME O2,, FRAIL,, DEMENTIA, RECENT HEMORRHAGIC, STROKE,, CHILD B OR C CIRRHOSIS,, ADVANCED CANCER WITH SHORT LIFE, EXPECTANCY,, NONVIABLE MYOCARDIUM., PROHIBITIVE SURGICAL RISK, , YES, , PCI VS MEDICAL, MANAGEMENT, , Unprotected Left, Main, , 3V, CAD, , 2V, CAD, Prox., LAD, , 1 V CAD, Prox., LAD, , LV, DYSFUNCTION, , SCD, survivor, , CABG: 1A, PCI: IIB(Ostial or, trunk), , CABG: I, PCI: IIB, , CABG: I, PCI: IIB, , CABG: IIA, PCI: IIB, , CABG: IIA, PCI:, Uncertain, , CABG: I, PCI: I, , FIG. 60.6 Surgical decision-making tree for coronary revascularization. CABG, Coronary artery bypass grafting;, CAD, coronary artery disease; COPD, chronic obstructive pulmonary disease; LAD, left anterior descending;, LV, left ventricle; PCI, percutaneous coronary intervention; SCD, sudden cardiac death (sudden cardiac arrest)., , • C,  ardiac catheterization to delineate the coronary anatomy, • Chest radiography, • Coagulation and platelet profile, comprehensive metabolic, panel, and complete blood count, Depending on the findings of these tests, patients may need, additional workup. In emergency circumstances, several of these, tests may be skipped so that immediate revascularization can be, performed., , Technique of Myocardial Revascularization:, Conventional On-Pump Cardiopulmonary Bypass, Box 60.4 outlines all the major steps of an on-pump CABG operation., Positioning and Draping, General anesthesia with a single-lumen endotracheal tube is the, anesthetic technique of choice. After anesthetic induction and, placement of necessary access and monitoring lines, the patient, is positioned supine, with or without a roll underneath the shoulder blades according to the surgeon’s preference. The arms are, tucked beside the patient with appropriate padding to minimize, the chance of any nerve injury. A warming blanket is typically, , placed underneath the patient to assist in rewarming after controlled hypothermia during CPB. The entire chest, abdomen, and, lower extremities are prepared. Circumferential preparation of, the lower extremities is important because the leg may have to be, maneuvered during harvesting of the saphenous vein conduit. If, radial artery harvesting is being contemplated, the arm also has to, be circumferentially prepared and positioned 90 degrees from the, bedside on an arm board because most patients have a multilumen, central line in the internal jugular vein or a Swan-Ganz catheter., Anchor points on the drapes are designated appropriately to allow, CPB circuit lines to be secured without compromising sterility., Cardiopulmonary Bypass, CPB is the establishment of extracorporeal oxygenation and perfusion of the human body by diverting all returning venous blood, from the body to the heart-lung machine and returning the oxygenated blood in a controlled, pressurized manner. In essence,, most blood flow to the heart and lungs is bypassed. Establishment, of CPB is a critical step for any major cardiac procedure and allows complete control of the operation., The basic components of an extracorporeal heart pump circuit, are venous cannulas to drain the returning venous blood, venous, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1692, , SECTION XI Chest, , reservoir that collects blood by gravity, oxygenator and heat exchanger, perfusion pump, blood filter in the arterial line, and, arterial cannula (Fig. 60.7). The blood conduits are designed to, , Major steps in on-pump, coronary artery bypass grafting., BOX 60.4, , • Induction of anesthesia and establishment of intraoperative monitoring adjuncts, • Positioning and draping, • Median sternotomy or appropriate approach, • Harvest and evaluation of blood conduits, • Heparinization and cannulation for cardiopulmonary bypass, • Establishment of cardiopulmonary bypass, • Myocardial arrest and protection, • Identification of target vessels and construction of distal anastomoses, • Restoration of myocardial electromechanical activity, • Creation of proximal anastomoses, • Weaning from cardiopulmonary bypass, • Evaluation for and establishment of necessary adjuncts—inotropes, intraaortic balloon pump, pacing wires, • Reversal of anticoagulation and establishment of hemostasis, • Evaluation of surgical sites and establishment of surgical drainage, • Closure of sternotomy, , minimize turbulence, cavitation, and changes in blood flow velocity, which are detrimental to the integrity of component blood, cells. Because the circuit contains a dead space created by the tubing and pump, a certain volume of nonblood solution is necessary, to prime the pump and tubing. The priming solution consists of a, balanced salt solution and, often, a starch solution. Homologous, blood or fresh-frozen plasma may be added if the patient is anemic, or if a bleeding problem is anticipated. The circuit has multiple, access ports or sites from which to obtain blood samples for laboratory studies and into which to infuse blood, blood products,, crystalloids, or drugs., Supplemental components include a cardiotomy suction system to collect undiluted or clean blood from open cardiac chambers and the surgical field. This blood is filtered, de-aired, and returned to the bypass pump. Diluted field blood and blood that has, mixed with inflammatory cytokines or fat are collected through a, separate device that concentrates washed red cells before returning, them directly to the patient., A cardioplegia infusion device consists of a separate pump, reservoir, and heat exchanger. It is used to deliver cold, potassiumenriched blood or crystalloid solutions into the coronary circulation to arrest and to protect the heart., Use of CPB requires suppression of the clotting cascade with, heparin because the surgical wound and components of the bypass pump are powerful stimuli for thrombus formation. A strict, , Sump, , Antegrade, cardioplegia, , Retrograde, cardioplegia, Venous, reservoir, Gravity, drain, Cardioplegia pump, , Centrifugal pump, , Oxygenator, , Heat exchanger, , FIG. 60.7 Schematic of total cardiopulmonary bypass circuit. All returning venous blood is siphoned into a, venous reservoir and is oxygenated, and temperature is regulated before being pumped back through a centrifugal pump into the arterial circulation. The most common site for inflow cannulation is the ascending aorta;, alternative sites include the femoral arteries and the right axillary artery in special circumstances. A parallel circuit derives oxygenated blood that is mixed with cold (4°C) cardioplegia solution in a 4:1 ratio and administered, in antegrade or retrograde fashion to induce cardiac arrest. Cardioplegia solution is administered antegrade into, the aortic root and retrograde through the coronary sinus. During the retrograde administration of cardioplegia, solution, the efflux of blood from the coronary ostium is siphoned off through the sump drain, a return parallel, circuit connected to the venous reservoir (not shown) that also helps to keep the heart decompressed during, the arrest phase., , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, anticoagulation protocol should be enforced before CPB is initiated. The pump prime is premixed with 4 U/mL heparin, and the, patient is systemically heparinized with 300 U/kg before cannulation. An activated clotting time obtained approximately 3 minutes, after heparin administration should be more than 400 seconds, before cannulation is begun and should be maintained for more, than 450 seconds throughout CPB, with intermittent doses given, as needed during the operation., The usual pumps are roller head pumps, which consist of circumferential tubing that is compressed by a roller on the outside,, thereby forcing blood in one direction. This pump mechanism is, associated with higher rates of hemolysis compared with centrifugal, pumps, so roller head pumps are used only in cardiotomy suction, and cardioplegia pumps. The main systemic pump is a centrifugal, pump that consists of a vortex polyurethane-embedded magnetic, cone housed in a conical chamber. The vortex spins at approximately 2000 to 5000 rpm, thereby generating enough centrifugal force to pump blood. Because the flow is entirely caused by a, nonturbulent vortex generated by a finless cone, this mechanism is, almost atraumatic to the blood cells and is therefore associated with, less hemolysis than the roller head pump mechanism (Fig. 60.8)., Neurologic Protection During Cardiopulmonary Bypass, The incidence of stroke after CPB is approximately 1.5%, but neurocognitive deficits are more frequent. Thus, several steps should, be taken during CPB to minimize the risk of neurologic insult,, including maintaining adequate cerebral perfusion, minimizing, fat microemboli by eliminating the unnecessary use of cardiotomy, suction, minimizing aortic manipulation by using single-clamp, techniques when feasible, and instituting moderate hypothermia., The oxygen consumption of a patient on CPB at normal temperatures averages 80 to 125 mL/min/m2, similar to that of an, anesthetized adult not on bypass. However, with the use of hypothermia, the oxygen consumption is markedly lower, and the flow, rate can be reduced to less than 2.2 L/min/m2. This is because, the mean oxygen consumption of the body decreases by 50% for, every 10°C decrease in body temperature. Below 28°C, a flow rate, of 1.6 L/min/m2 may be safe for as long as 2 hours. Significant, , FIG. 60.8 Main centrifugal pump used in most cardiopulmonary bypass, circuits. The entire unit is sterile molded and contains a finless cone that, spins at 2000 to 5000 rpm, generating a powerful yet nonturbulent vortex. A flow meter (shown) must be used with these pumps because the, ultimate volume of flow depends on outflow resistance rather than on, pump speed. The conventional roller head pumps are still used for the, auxiliary circuits, such as cardiotomy suction and cardioplegia circuits., , 1693, , disadvantages of using systemic hypothermia to accommodate, lower flow rates include the extra time required to rewarm the, patient and associated changes in the reactivity of blood elements,, particularly platelets. These changes may increase the rewarmed, patient’s propensity for bleeding., Median Sternotomy, The most common approach for performing CABG is a median, sternotomy, although anterolateral thoracotomy is used in certain, circumstances. A traditional sternotomy incision commences at, the midpoint of the manubrium and is carried down to the xiphoid. The sternum is split through the middle with a sternal saw., It is essential that gentle upward force and a backward tilt be applied to the saw to prevent it from engaging the lung or soft tissues, in the anterior mediastinum. Once the sternotomy is completed,, the periosteum of the posterior table is cauterized, and a passive, hemostatic agent such as bone wax or a reconstituted mixture, of vancomycin may be used to prevent bleeding from the marrow. The most important consideration during the sternotomy is, staying in the midline because the most common cause of sternal, dehiscence is an off-midline sternotomy and the consequent technically suboptimal closure. Other potential problems associated, with the sternotomy include indirect injury to the liver and direct, injury to the heart, innominate vein, and lungs., Conduit Choice and Harvesting, Left internal mammary artery. In a seminal study from the, Cleveland Clinic, Loop and colleagues42 have shown improved, 10-year survival in patients who received a LIMA graft; patients, who received an SVG had 1.6 times the risk of death that LIMA, graft recipients had. The long-term patency rate of the LIMA graft, has been shown to be approximately 95% and 90% at 10 and 20, years, respectively. The best patency rates are achieved when the, LIMA is used as an in situ pedicled graft and is anastomosed to, the LAD., Bilateral internal mammary artery. Observational studies from, major CABG centers suggested that the use of bilateral IMA, (BIMA) grafts improves survival and significantly reduces the, need for reoperation without increasing mortality. However, early, results from a randomized trial demonstrated that compared with, SVGs, BIMA grafts are associated with a higher (twofold) incidence of deep sternal wound infection. BIMA grafts are best used, by experienced surgeons in younger, nondiabetic, nonobese patients. Four major studies that tilted the balance in favor of BIMA, grafts were the two Cleveland Clinic studies (1999 and 2004),, in which propensity scores were used to match single and BIMA, graft recipients; the Oxford metaanalysis (2001); and a retrospective study from Japan (2001). Skeletonization of the IMA grafts, may reduce the wound complication rate., The ART trial has revealed no significant difference in mortality and cardiovascular events with the use if BIMA at 5 years., At 10-year follow-up of the ART trial among patients who were, scheduled for CABG and had been randomly assigned to undergo, bilateral or single internal-thoracic-artery grafting, there was no, significant difference between-group difference in the rate of death, from any cause at 10 years in the intention-to-treat analysis.43, The IMA is harvested after the sternotomy is completed. A specially designed mammary retractor is used to elevate the appropriate, hemithorax, typically the left for harvesting the LIMA. Adequately, exposing the undersurface of the sternum is essential for successful, harvest of the IMA (Fig. 60.9). The artery may be harvested as a, pedicle that includes the two venae comitantes and surrounding soft, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1694, , SECTION XI Chest, , Sternum, Anterior, intercostal, branches, Left internal, mammary, artery, Accompanying, internal, Phrenic mammary vein, nerve, Subclavian vein Left lung, , Left internal, mammary, artery bypass, Saphenous, vein, bypass, , FIG. 60.9 Surgeon’s view of the left internal mammary artery (LIMA), as it is being harvested. A mammary retractor is used to elevate the left, hemithorax to provide adequate visualization. The LIMA is dissected, away from the chest wall as a pedicle with its accompanying venae comitantes. Low-voltage electrocautery with no-touch technique is crucial, for the atraumatic harvest of this important conduit. Understanding of its, relation to the phrenic nerve and subclavian veins is important to avoid, injury to these structures during LIMA harvest., , tissue from the level of the subclavian vein to the level of the bifurcation of the artery into the superior epigastric and musculophrenic, branches. The alternative method of harvesting is the skeletonized, harvest, in which only the IMA is dissected away from the chest wall., The basic principle of harvesting the IMA relies exclusively on, the no-touch technique, use of low-voltage electrocautery, and, clipping of the anterior intercostal branches. Care must be taken, during the harvest to identify the course of the phrenic nerves, and to avoid injury to them. This is particularly important while, harvesting the right IMA because the phrenic nerve is more closely, related to it at the level of the second or third intercostal space., The IMA is a fragile vessel, and direct handling or undue traction, should be avoided because it may cause traumatic dissection of the, vessel. The distal end of the IMA should be divided only after the, patient is fully heparinized to avoid thrombosis of the conduit., Once the IMA is divided, the distal end is spatulated appropriately to fashion the anastomosis., Greater saphenous vein. Vein grafts have a patency rate of 90%, at 1 year.44 Beyond 5 years after surgery, graft atherosclerosis develops in a substantial number of SVGs. Historically, by 10 years,, only 60% to 70% of SVGs are patent, and 50% of those have, angiographic evidence of atherosclerosis., While the sternotomy is being done, a separate team begins, harvesting saphenous or radial artery conduits. Saphenous vein, harvesting can be performed by open or endoscopic techniques., The conventional method of open vein harvesting involves making a long incision along the entire length of the harvested vein., Alternatively, a bridging technique can be used in which multiple, 1- to 2-inch incisions are made, with intact bridges of skin between them. The most common complications associated with, long open incisions are pain, slow wound healing, and dehiscence,, which is compounded by the fact that a significant number of, CABG patients have diabetes or PVD. The use of endoscopic or, bridging techniques significantly alleviates but does not entirely eliminate these problems. There are some centers that avoid, endoscopic vein harvesting entirely on the assumption that the, technique is too traumatic to the vein itself, may be associated, with intimal trauma, and may impair the long-term patency of, the conduit. However, a recent randomized trial (REGROUP), , Saphenous, vein, bypass, , FIG. 60.10 Typical configuration for a three-vessel coronary artery bypass. The left internal mammary artery is anastomosed to the left anterior, descending artery. Aortocoronary bypasses are created with reversed saphenous vein to the distal right coronary artery and an obtuse marginal, branch of the circumflex coronary artery. The circumflex coronary artery, is usually avoided as a target for bypass because its location well inside, the atrioventricular groove makes it difficult to visualize., , demonstrated the safety and efficacy of endoscopic vein harvesting.45 These reports were based on post hoc analyses of data from, trials designed to address other aspects of coronary revascularization. Once the vein is extracted and the branches are ligated, the, graft is soaked in a heparin solution while awaiting implantation., The veins are typically used in a reversed fashion and hence may, not require valvotomy. A typical configuration of a three-vessel, coronary artery bypass graft is shown in Fig. 60.10., Alternative conduits may be needed in patients who have had, previous coronary bypass, peripheral vascular surgery with the use, of vein conduits, or lower extremity amputations and in those who, have unusable saphenous vein conduits because of severe varicosities of the saphenous vein. Other manifestations of venous insufficiency or disease may also pose problems. In addition, patients, who have severely calcified ascending aortas may not be amenable, to a vein-based aortocoronary bypass because anastomosis to the ascending aorta is complicated. In these cases, alternative bypass strategies include total arterial revascularization with BIMA pedicles, (Fig. 60.11). In addition, the IMA may be used as the main conduit, from which further arterial conduits may be Christmas-treed in an, off-pump setup so that any aortic manipulation is avoided., Other conduits, , Radial artery. The radial artery graft is easily harvested and, can reach all coronary territories, making it an attractive option, for an arterial conduit. Both the Radial Artery Patency Study and, the Radial Artery versus Saphenous Vein Patency study showed, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, , Right, internal, mammary, artery, bypass, , Left internal, mammary, artery, bypass, , Radial, artery, bypass, , FIG. 60.11 Total arterial revascularization by use of bilateral mammary, artery and radial artery conduits. The right internal mammary artery, bypassed to an obtuse marginal branch, is routed behind the aorta, and the, pulmonary artery is routed through the transverse sinus., , radial artery grafts to have better patency than SVGs on 5-year, angiographic follow-up. However, the radial artery is associated, with a significantly higher incidence of conduit spasm and string, sign. In addition, to date, no study has shown a survival advantage, of radial artery over SVG grafting. Also, patency is much worse if, the radial grafts are not placed on critically stenotic vessels., Gastroepiploic artery. The gastroepiploic artery is rarely used, today, although some centers in Asia still use gastroepiploic grafts, and continue to report acceptable outcomes associated with them., Evidence from RCTs and a recent metaanalysis suggests that the, saphenous vein has better early (6-month) and midterm (3-year), graft patency than the right gastroepiploic artery when it is used, for RCA revascularization., Total Arterial Revascularization, More than 90% of all CABG operations performed in the United, States, United Kingdom, and Australia involve only one arterial, graft.46,47 The LIMA and SVG remain the standard CABG grafts;, SVGs account for most of the conduits used. In an effort to ameliorate the shortcomings of SVGs, which are vulnerable to atherosclerosis and stenosis over time, some centers have been heavily, emphasizing total arterial revascularization in which the LIMA,, right IMA, and radial arteries are used., Results from retrospective series have shown some survival, benefit with total arterial revascularization, as would be expected., However, there are certain pragmatic reasons that total arterial revascularization has not totally replaced the use of SVGs:, • Concern about arterial spasm: Arterial grafts, particularly radial grafts, are prone to spasm, and their use necessitates vasodilator administration, , 1695, , • U,  se of arterial grafts appropriate only for severely stenotic arteries as they are more vulnerable to competitive flow compared to veins: Most experts would not use a radial graft unless, there is at least 70% stenosis and probably 90% or more for, larger vessels such as the main right coronary, • Inadequate length: As an in situ graft, the right IMA is typically not long enough to reach the PDA, mid or distal circumflex,, or distal LAD and cannot be used easily as a sequential graft. It, can, however, be used as a free graft, • Concern about sternal nonunion and mediastinitis: There is a, higher risk of sternal nonunion and mediastinitis with the use, of BIMA grafts versus SVGs. Most experts will not use BIMA, grafts in patients with poorly controlled diabetes, severe PVD,, use of steroids, severe chronic obstructive pulmonary disease,, or morbid obesity. Also, in the event that BIMA is used, most, would recommend the skeletonized technique of BIMA harvest with preservation of the intercostal blood supply, • Longer operative times: Using BIMA grafts obviously prolongs, operative times, Because of all these practical considerations, multiarterial revascularization has not become as popular as would be expected,, and most surgeons would offer total arterial revascularization only, to younger patients because of their longer life expectancy., Cannulation for Cardiopulmonary Bypass, Cannulation for the establishment of CPB commences after, conduit harvest and preparation are completed, the pericardium is opened, and the thymus is divided along the embryologic fusion plane. The patient is fully heparinized at a dose of, 3 mg/kg. A purse-string is created on the anterior surface of, the distal ascending aorta at the cannulation site. The aortic, purse-string should involve only a partial thickness of the aorta, incorporating the adventitia and media but entirely avoiding the intimal layer. It is essential that the cannulation site be, free of calcified plaques or atheroma to minimize the chance, of embolization and cannulation site bleeding. Manual palpation, the commonly practiced method of assessment, is unreliable. Doppler transesophageal or epiaortic ultrasonographic, guidance should be used whenever aortic disease is suspected., Also, the presence of calcium elsewhere in the ascending aorta, may preclude safe clamp application. Although cannulation of, the aorta may be a simple task, loss of control of the aortic, cannulation site or inadvertent dissection could lead to a disastrous situation., With a sharp scalpel, the adventitia is teased, and a full-thickness stab incision is made. The aortic cannula is inserted with the, outflow bevel aimed toward the aortic arch. Tourniquet snares are, used to secure the cannula in position and are tied. After the cannula is de-aired, it is connected to the arterial line of the CPB, circuit. Alternative sites of arterial cannulation include the femoral artery and right axillary artery, which are used in reoperations, or cases in which concomitant complex aortic and arch reconstruction may be required. Axillary artery cannulation is usually, achieved with an 8-mm graft anastomosed end to side to the axillary artery., For venous cannulation, a purse-string is then placed around, the right atrial appendage. The tip of this appendage is amputated,, and a dual-stage venous cannula is inserted and positioned with, the tip at the level of the diaphragm. The basket of the dual-stage, cannula should rest in the main chamber of the right atrium to, capture drainage from the superior vena cava into the right atrium, (Figs. 60.12 and 60.13)., , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1696, , SECTION XI Chest, , Aortic, cannula, , Pulmonary artery, , Aortic, crossclamp, Ascending, aorta, , Venous, cannula, , Antegrade, cardioplegia, cannula, Retrograde, cardioplegia, cannula, , FIG. 60.12 Surgeon’s view of the heart after cannulation. The crossclamp isolates the aortic root and coronary vessels from the rest of the, systemic circulation. This allows administration of cardioplegia solution in, a closed circuit and prevents the systemic blood from washing the cardioplegia solution out of the coronary system during the arrest phase. Applying the cross-clamp prevents active blood flow through the coronary, arteries and thus allows the surgeon to perform the distal anastomoses, in a bloodless field., , FIG. 60.13 Aortic cannula (top): The specially designed tip is angulated, to allow laminar flow of blood into the aortic arch. Dual-stage venous cannula (bottom): The first stage is the fenestrated basket that usually rests, at the level of the hepatic veins and captures all venous return from the inferior vena cava. The second-stage basket is located such that it remains, within the right atrium and captures venous return from the superior vena, cava, azygos vein, coronary sinus, and direct collateral drainage into the, right atrium. The venous drainage is a passive siphon aided by gravity., , Cardiac Arrest and Myocardial Protection, The initiation of CPB allows the heart to be stopped. To achieve, cardiac arrest, a large dose of potassium solution (cardioplegia), is injected into the coronary vessels. This requires the coronary, blood flow to be completely isolated from the systemic circulation, which is done by applying a cross-clamp to the ascending, aorta proximal to the aortic cannula., There are several different delivery options for cardioplegia solutions. One involves taking a balanced approach; the cardioplegia, solution is administered antegrade through the ascending aorta, proximal to the cross-clamp and then retrograde through a coronary sinus catheter inserted through a purse-string suture placed, in the right atrium by use of special cannulas (Fig. 60.14). The extensive collateralization among the coronary veins and arteries and, the paucity of valves in the coronary vein system ensure a relatively, , FIG. 60.14 Retrograde cardioplegia cannula (bottom) used to administer cardioplegia solution into the coronary sinus. The self-inflating balloon, distends, forming a seal only when cardioplegia solution is administered., Antegrade cardioplegia cannula (top) used to administer cardioplegia solution into the aortic root. The side port functions as a sump., , homogeneous distribution of cardioplegia solution when the retrograde approach is used. Patients with high-grade proximal lesions, especially those with suboptimal collateral vessels, may, benefit from the application of both techniques. After the initial, administration of cardioplegia solution, additional doses are usually administered every 15 to 20 minutes., An antegrade cardioplegia line with a Y-connector to the circuit is inserted into the ascending aorta. This allows antegrade, administration of cardioplegia solution and also sumping and decompression of the ascending aorta while cardioplegia solution is, administered retrogradely into the coronary sinus. The sump drain, also functions to keep the coronary arteries free of any blood, thus, providing the surgeon with a bloodless field in which to fashion, the distal anastomoses. In addition, the sump drain performs the, important function of decompressing the LV while the heart is, arrested (see Figs. 60.7 and 60.12)., The most important task for ensuring myocardial protection, is establishing complete diastolic arrest with an unloaded heart., In this state, the myocardial consumption of adenosine triphosphate is extremely low and allows maximal preservation of myocytes. In conventional CABG with total CPB, the decompression, of the ventricle by off-loading, systemic cooling, topical cooling,, and diastolic arrest of the heart with potassium cardioplegia solution serves to decrease myocardial oxygen consumption. Approximately 40% of the myocardial metabolic demand is eliminated, when total CPB is established before diastolic arrest and cooling, are instituted., Target Identification and Distal Anastomosis, Once successful diastolic arrest of the heart is accomplished, the, target coronary arteries to be bypassed are identified. Some of the, epicardial conductance vessels are intramyocardial and therefore, may not be directly visible. Once a target vessel is identified, it is, opened with a sharp blade. Typically, the arteriotomy is approximately 5 mm long. The conduit, which is prepared and spatulated, is then grafted in an end-to-side fashion with running 7-0, or 8-0 Prolene suture. This component of the operation is technically the most challenging and requires precision. The flow and, integrity of each vein conduit are tested by flushing it with cold, blood or cardioplegia solution mix. The LIMA to left descending, artery anastomosis is usually the last one to be performed (Fig., 60.15) because it is best to avoid manipulating the heart once this, anastomosis is completed in case avulsion of the LIMA conduit, occurs. Bypassing the PDA and obtuse marginal targets requires, lifting the apex of the heart out of the pericardium., , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, , 1697, , Left internal, mammary artery, bypass, , Saphenous, vein bypass, , FIG. 60.16 Alternative configuration for a three-vessel coronary artery, , FIG. 60.15 Technique of constructing the distal anastomoses: left internal mammary artery to left anterior descending artery, magnified surgeon’s view. A 5-mm longitudinal arteriotomy is made on the coronary, artery to be bypassed. The distal end of the left internal mammary artery, is spatulated to an appropriate size match. A 7-0 Prolene suture is used to, create the anastomosis with a parachuting technique., , Typically, a single segment of conduit is anastomosed to each, planned distal target. On occasion, a single conduit can be used to, supply blood to two targets, which is known as a sequential anastomosis. This is a good technique to use when there is a shortage of, available vein conduits or when the target vessels are small; in these, cases, use of this technique ensures a higher rate of blood flow through, the vein conduit, reducing the risk of graft thrombosis (Fig. 60.16)., As the last distal anastomosis is being completed, the patient is, warmed back to physiologic temperature. The cross-clamp is released after the final dose of warm cardioplegia solution is administered, which helps in scavenging the accumulated free radicals in, the myocardium. A partial clamp is then applied to the ascending, aorta, and the proximal anastomoses are constructed in an end-toside fashion with running 5-0 Prolene suture. If there are concerns, about the quality of the aorta, use of a partial clamp is typically, avoided in favor of a single-clamp technique, which involves constructing the proximal anastomoses on an arrested heart, as for the, distal anastomoses., In patients in whom the ascending aorta is calcified or a free, IMA pedicle needs to be used, a branching pattern of proximal, anastomoses is made. This conserves vein length to a certain extent, but also minimizes the number of aortotomies, especially if the ascending aorta is short or a concomitant aortic procedure has been, performed. The ascending aorta is allowed to de-air as the aortic, clamp is released, after which the vein grafts are de-aired., , bypass. The left internal mammary artery is anastomosed sequentially to, a diagonal branch and to the distal left anterior descending artery. Aortocoronary bypasses are constructed with reversed saphenous vein in, sequential configuration to the left posterolateral artery and an obtuse, marginal branch of the circumflex coronary artery. The ideal configuration, depends on the extent and distribution of the coronary blockages., , Separation from Cardiopulmonary Bypass, Separation from CPB commences once the following physiologic, criteria have been met:, • Resumption of rhythmic electromechanical activity, • Attainment of physiologic temperature above 36.5°C, • Availability of adequate reserve blood volume, • Restoration of normal systemic potassium levels, • Resumption of ventilation with an acceptable arterial blood gas, level, A few other actions that may be considered at this point are, placement of temporary pacing wires and insertion of an IABP, if, needed. Typically, the CPB flows are progressively decreased as the, following parameters are closely observed:, • Data from the Swan-Ganz catheter, • Direct visual observations of cardiac function and chamber, volume, • The transesophageal echocardiogram, Most patients have a transient systemic inflammatory response,, causing vasodilation that becomes more pronounced as they are, warmed. Thus, restoration of volume with intravascular fluids or, administration of vasopressors may be necessary to maintain systemic blood pressure. Inotropic agents may be used if ventricular, function is not adequate. Separating patients from CPB is primarily the surgeon’s responsibility but requires dynamic communication with the perfusionist and anesthesiologist., After CPB is discontinued, the venous cannula is removed and, the purse-string is tied down. Once it is confirmed that the heart is, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1698, , SECTION XI Chest, , providing satisfactory perfusion, protamine is administered. Close, monitoring is needed because adverse reactions to protamine, range from transient hypotension to fatal anaphylaxis. Such reactions necessitate the resumption of CPB., , pressure, cardiac output, and peripheral perfusion while minimizing myocardial stress. Urine output is the most reliable indicator, of peripheral organ perfusion., , Hemostasis, As protamine is being administered, hemostasis is expeditiously, accomplished. As the patient rewarms, blood vessels that had been, hemostatic may dilate and rebleed. Persistent bleeding should, alert the surgeon to the following possible causes: aspects of the, surgical technique, platelet dysfunction, inadequate protamine reversal, and hypothermia. The administration of blood and blood, products may be necessary., , For patients whose profound myocardial dysfunction is unresponsive to volume resuscitation and significant pharmacologic therapy, IABP support may be indicated. The IABP is a special Silastic, balloon with a capacity of 40 to 60 mL that is positioned in the, descending aorta just beyond the origin of the left subclavian artery. The balloon is designed to be actively inflated and deflated, during each cardiac cycle; its timing is controlled by a specially designed computer with input from an arterial line tracing or ECG., Intra-aortic balloon counterpulsation has the benefit of decreasing, myocardial work and oxygen consumption while increasing coronary perfusion., The balloon is actively deflated just before systolic contraction begins, thereby decreasing LV impedance and assisting in, the ejection of blood. The balloon then actively inflates at the, time of aortic valve closure; that is, it is timed to occur at the, dicrotic notch of the arterial line tracing. This increases the, diastolic perfusion pressure and improves coronary blood flow,, both of which decrease the time-tension index and increase the, diastolic pressure-time index, thereby increasing the myocardial, oxygen supply-to-demand ratio. The use of IABP is absolutely, contraindicated in patients with aortic regurgitation and aortic, dissection. It is relatively contraindicated in patients with PVD, or aortic aneurysm., , Sternal Closure and Completion of Surgery, The chest tube and temporary pacing wires should be checked for, appropriate positioning. The sternum is approximated with stainless steel wires. The soft tissues and skin are closed in layers with, absorbable sutures., , ADJUNCTS TO CORONARY ARTERY BYPASS, GRAFTING, Transesophageal Echocardiography, Use of transesophageal echocardiography (TEE) enables the, assessment of ventricular wall motion abnormalities and the, detection of any chamber or valve anomalies that may change, the strategy of the operation. Examples of TEE findings that, may affect the conduct of the operation include an incidentally, discovered large patent foramen ovale or fibroelastoma of the, valves. New-onset or worsening mitral regurgitation after CABG, suggests inferior wall ischemia and may indicate reevaluation of, the bypass grafts or valve repair or replacement. Also, TEE helps, in assessing ejection fraction and the volume status of the heart, after surgery., , Inotropes and Pharmacotherapy, Cardioplegic arrest causes transient myocardial ischemia and lactic acid accumulation. After perfusion is reestablished, the ventricles are stiffer and require higher filling pressures to maintain, adequate stroke volume. Also, CPB may cause significant third, spacing and vasodilation. Thus, epinephrine as an inotropic agent, is ideal to maintain adequate contractility in the initial recovery, phase and during separation from CPB. Alpha agonists such as, norepinephrine, phenylephrine, and vasopressin may be used to, counteract the effects of inflammatory vasodilation. In patients, with depressed myocardial function, such as left- or right-sided, heart failure, dobutamine or a phosphodiesterase inhibitor such, as milrinone may be required to enhance myocardial contractility, and to decrease afterload or pulmonary vascular resistance. Because hypotension is a common side effect of these drugs, the systemic volume must be adequate, and an alpha agonist may be required. Calcium channel blockers or nitroglycerin may be needed, in patients with preexisting hypertension., It is essential to maintain a mean arterial pressure higher than, 60 mm Hg in the initial postoperative period, but hypertension, should be avoided because it puts stress on a myocardium that is, trying to recover and increases the risk of bleeding from anastomotic suture lines. Blood pressure management requires a thorough understanding of physiologic and pharmacologic principles., It is a balancing act geared toward maintaining adequate systemic, , Intraaortic Balloon Pump, , POSTOPERATIVE CARE, Postoperative care in the intensive care unit (ICU) begins with, a thorough physical and hemodynamic assessment. Mediastinal, chest tube drainage should be recorded and assessed hourly. Initial, ventilator settings should be set to match those in the operating, room. Further adjustments in ventilator settings are made according to the postoperative blood gases. High positive end-expiratory pressure should be avoided in patients with hemodynamic, instability. The ideal mode of ventilation is that with which the, surgical or intensive care team is comfortable. A portable chest, radiograph is obtained to confirm the position of the endotracheal, tube, central lines, Swan-Ganz catheter, and IABP and to identify, any pneumothorax, atelectasis, pulmonary edema, or pleural effusions. Initial laboratory studies should include hemoglobin, hematocrit, electrolyte, blood urea nitrogen, creatinine, and arterial, blood gas levels and platelet count, prothrombin time, and partial, thromboplastin time., The patient should have an ECG monitor that can assess ST-T, wave abnormalities; an arterial line to measure arterial blood pressure; and a line to measure central venous pressure, pulse oximetry, and core temperature. In select patients, pulmonary artery, pressures and cardiac output are monitored continuously with a, Swan-Ganz catheter. Neurologic assessment should be completed, as soon as the patient wakes up to ensure that no cerebrovascular, accident has occurred., The primary considerations during the first 12 hours after the, operation should be maintaining adequate blood pressure and cardiac output, correcting coagulation defects and electrolyte levels,, stabilizing intravascular volume, and normalizing the peripheral, vascular resistance. This often involves administration of crystalloid solutions, blood or blood products, inotropic agents, calcium,, and vasodilators or vasoconstrictors., , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, , 1699, , Some of the goals in the postoperative period are as follows:, • A,  voiding marked elevations in blood pressure, • Maintaining adequate perfusion pressure (60–80 mm Hg), • Maintaining core body temperature higher than 36.5°C by, warming the patient with forced hot air blankets, • Maintaining adequate cardiac output and a cardiac index of, 2.2 L/min/m2, • Keeping mixed venous oxygenation at 60%, • Reducing afterload, as appropriate, to minimize myocardial, work, • Volume resuscitation with crystalloid or blood products, as, necessary, • Maintaining hemoglobin level higher than 8 g/dL, or higher, than 10 g/dL in older patients or those with severe cerebrovascular disease, • Maintaining homeostatic pH. Metabolic acidosis may be, caused by hypoperfusion from low cardiac output, poor resuscitation, hypovolemia, or end-organ ischemia from embolism., • Monitoring neurologic and peripheral vascular status, • Maintaining a sinus or perfusing rhythm at a rate of 70 to 100, beats/min, • Monitoring for and treating postoperative cardiac arrhythmias, • Ensuring adequate pain control to minimize fluctuations in, blood pressure and myocardial stress, • Keeping blood glucose levels below 180 mg/dL. Standardized, insulin-infusion regimens should be initiated, if needed, , In cardiac surgery, operative mortality has traditionally included, 30-day and in-hospital mortality. The mortality figure for CABG, is 1% to 3% in most modern series. Risk-adjusted outcomes have, become the gold standard for reporting and comparing cardiac, surgery outcomes. The STS database is the largest and most authoritative voluntary national database to date. The STS has developed a risk calculator that estimates morbidity and mortality for, a given patient’s risk profile. The observed-to-expected mortality, ratio for a given surgeon or institution can then be determined., , Pulmonary Care, , Tamponade. Pericardial tamponade is caused by the formation, of pericardial clot and compression of the heart. The condition, should be suspected if there is evidence of low cardiac output,, hypotension coincident with tachycardia, and elevated central, venous pressure. The quantity of mediastinal drainage is an unreliable predictor of tamponade, although an abrupt decline in, mediastinal chest tube drainage should raise suspicion of tamponade caused by absence of an exit path for the blood. Widening, of the mediastinum on chest radiography and echocardiographic, evidence of a pericardial effusion should confirm the diagnosis., If a Swan-Ganz catheter is in place and right- and left-sided, heart pressures are monitored, the central venous pressure and, pulmonary capillary wedge pressure are usually elevated and, equal. The earliest manifestation of tamponade is an acute drop in, mixed venous oxygen saturation. After the diagnosis is made, the, patient should be returned to the operating room for evacuation, of the clot and relief of the compression. If the patient’s condition, is rapidly deteriorating, the sternotomy incision may have to be, reopened at the bedside., Postoperative bleeding. The combination of heparinization,, hypothermia, CPB, and protamine reversal is associated with increased risk for bleeding after CABG. Post-CABG bleeding that, requires transfusion or reoperation is associated with a significant, increase in morbidity and mortality risk. A minority of patients, having cardiac procedures (15%–20%) consume more than 80%, of all blood products transfused at operation. Blood must be, viewed as a scarce resource that carries significant risks and unproven benefits. There is a high-risk subset of patients who require, multiple preventive measures to reduce the chance of postoperative bleeding. Nine variables stand out as important indicators of, risk (Box 60.5)., Available evidence-based blood conservation techniques include the following:, • Administration of drugs that increase preoperative blood volume (e.g., erythropoietin) or decrease postoperative bleeding, , It is desirable to separate patients from the ventilator as soon as, they awaken, are hemodynamically stable with minimal chest tube, drainage, and can maintain a satisfactory spontaneous tidal volume and respiratory rate. Coughing and deep breathing exercises, with appropriate sternal precautions are essential for postoperative recovery. Suboptimal postoperative pulmonary function may, indicate additional therapy, including the use of bronchodilators,, mucolytics, and chest physical therapy. Although β-adrenergic, bronchodilators and N-acetylcysteine are useful adjuncts, they, also can induce atrial fibrillation., After extubation, it is important to provide the patient with, sufficient pain relief to minimize emotional distress, poor coughing, and reluctance to begin ambulation. Unrelieved pain can also, be a source of tachycardia, hypertension, myocardial ischemia, atelectasis, hypoxia, and pneumonia., , Discharge From the Intensive Care Unit, Before the patient leaves the ICU, unnecessary lines and catheters, should be removed. Chest tubes are removed approximately 48, hours postoperatively, when the combined drainage is less than, 200 mL per shift and chest radiography reveals no effusion. Removal of temporary atrial and ventricular pacing wires is often, deferred to the third postoperative day., , Outcomes, Hospital Mortality, Seven core variables—emergency of operation, age, prior heart, surgery, gender, LVEF, percentage stenosis of LCA, and number of, major coronary arteries with more than 70% stenosis—have the, greatest impact on CABG mortality. Other variables are important but have minimal impact when added to these core variables;, these include recent MI (<1 week), angina severity, ventricular arrhythmia, CHF, mitral regurgitation, diabetes, PVD, renal insufficiency, and creatinine level., , Long-Term Survival, Survival after CABG is related to cardiac and noncardiac comorbidities. Risk factors for atherosclerosis, particularly cigarette, smoking, hypercholesterolemia, hypertension, and diabetes, are, associated with decreased survival., In no longitudinal study has CABG obliterated the negative, impact of abnormal LV function on late survival. Incomplete revascularization is associated with decreased survival, whereas complete revascularization, the use of the LIMA, and, in some studies,, the use of BIMA are associated with improved survival., The CASS documented overall survival of 96%, 90%, 74%,, 56%, and 45% at 1, 5, 10, 15, and 18 postoperative years, respectively. These figures are inferior to those for the age-matched U.S., population and for modern series of patients who receive single or, bilateral mammary grafts., Morbidity, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1700, , SECTION XI Chest, , BOX 60.5, , bleeding., , Risk factors for postoperative, , • A,  dvanced age, • L ow preoperative red blood cell volume (preoperative anemia or small body, size), • Preoperative antiplatelet or antithrombotic drugs, • Reoperative or complex procedures, • Emergency operations, • Noncardiac patient comorbidities, • Renal failure, • Chronic obstructive pulmonary disease, • Congestive heart failure, , Causes of immediate, postoperative bleeding., BOX 60.6, , Surgical, • Conduit, • Anastomoses, • Cannulation sites, • Mammary bed, • Thymic veins, • Pericardial edge, • Sternal wire sites, Platelet dysfunction, Inadequate protamine reversal, Hypothermia, , (e.g., ε-aminocaproic acid). Aprotinin is currently banned in, the United States because some studies have associated it with, increased mortality, stroke, and renal failure when it is administered to cardiac surgery patients, • Intraoperative blood salvage and blood-sparing interventions, • Interventions that protect the patient’s own blood from the, stress of operation (e.g., autologous predonation, normovolemic hemodilution), • Institution-specific blood transfusion algorithms supplemented with point-of-care testing, Despite efforts at blood conservation to limit perioperative, bleeding and blood transfusions, 2% to 3% of patients will require reexploration for bleeding, and as many as 20% will have, excessive bleeding and blood transfusion postoperatively. Bleeding, of more than 500 mL in the first hour or persistent bleeding of, more than 200 mL/hr for 4 hours is an indication for mediastinal, exploration. Exploration is also indicated if a large hemothorax is, identified on chest radiography or pericardial tamponade occurs., Usually, a specific bleeding site is not identified. Box 60.6 summarizes the common causes of immediate postoperative bleeding., Neurologic complications. There are two types of neurologic, deficits after CABG: type I deficit, which is a focal neurologic, deficit; and type II deficit, which is manifested as nonspecific, encephalopathy. In a 1996 multi-institutional prospective study,, 6% of patients had these adverse outcomes, which were evenly, distributed between the two types of deficit. Associated mortality was 20% for type I, which was twice the mortality for type, II deficit. Age (especially >70 years) and hypertension are consistent risk factors for both types. History of previous neurologic, , abnormality, diabetes, and atherosclerosis of the aorta are risk factors for type I. Significant atherosclerosis of the ascending aorta, mandates a surgical approach that will minimize the possibility of, atherosclerotic emboli. Patients with concomitant carotid stenosis are at an elevated risk for neurologic complications. One approach used in such patients involves a staged procedure in which, the more symptomatic and more critical vascular bed is addressed, first. Otherwise, a combined approach may be used, but this poses, a greater overall risk., Mediastinitis. The incidence of deep sternal wound infection, is 1% to 2% in modern-era CABG. Risk factors include obesity,, reoperation, diabetes, and duration and complexity of operation., Using a BIMA graft can increase the risk of sternal wound complications in high-risk patients. The use of perioperative antibiotics, and a strict protocol aimed at controlling the blood glucose level, to less than 180 mg/dL by continuous intravenous infusion of, insulin has been shown to reduce the incidence of mediastinitis, significantly. Early debridement and muscle flap closure improve, outcome. More recently, good outcomes have also been reported, with the use of wound vacuum-assisted closures after adequate, debridement., Renal dysfunction. Mangano and coworkers have reported a, 7.7% incidence of postoperative renal dysfunction in CABG patients and mortality rates of 0.9%, 19%, and 63% in patients, without postoperative renal dysfunction, patients with postoperative renal dysfunction but without need for dialysis, and patients, who required dialysis, respectively. The 63% figure was confirmed, in a large Veterans Administration study., , Medical Adjuncts for Postoperative Management, The following drugs are considered essential components of the, postoperative management of CABG patients:, • Aspirin administration, 81 to 325 mg orally or rectally, is begun on the same day after CABG, unless the patient is bleeding, because of platelet dysfunction. This is a quality-of-care index, and has been shown to improve long-term graft patency, • Beta blocker administration should begin after all inotropes, have been discontinued. The goal is to maintain a heart rate of, 60 to 80 beats/min and adequate mean perfusion pressures, • Afterload reduction is important in all patients with a low, LVEF. Afterload reduction is commenced after all inotropes, are discontinued and adequate beta blockade is achieved. The, angiotensin-converting enzyme inhibitors are first-line drugs, for afterload reduction. Creatinine levels should be monitored, • For antiarrhythmic treatment, amiodarone is used in many cardiac centers as prophylaxis against or treatment of atrial fibrillation. This drug should be used with caution in patients with, preexisting interstitial lung disease and those taking warfarin., A prolonged Q-T interval is a contraindication, • Administration of furosemide, a diuretic, is begun on the first, postoperative day; the goal is to maintain a negative fluid balance. Chest radiography, creatinine levels, physical examination, and input-output charts help guide the dose of furosemide, , ALTERNATIVE METHODS FOR MYOCARDIAL, REVASCULARIZATION, Cardiopulmonary Bypass With Hypothermic Fibrillatory, Arrest, Hypothermic fibrillatory arrest is a good on-pump alternative to, conventional cardioplegic arrest and avoids the use of the aortic, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, cross-clamp. Although cardioplegic arrest offers maximal myocardial protection while providing a stable, immobile target for the, distal anastomoses, not all patients are amenable to cardioplegiabased arrest. In patients with an extensively calcified aorta, crossclamp application may be precarious and associated with an elevated incidence of stroke., In these cases, a hypothermic fibrillatory arrest strategy may, be used in which aortic manipulation is minimized. Once CPB is, initiated, the patient is cooled to 28°C. The heart typically begins, fibrillating at approximately 32°C. An LV sump is usually introduced through the right superior pulmonary vein to ensure LV decompression. Handling of the distal and proximal targets is similar, to off-pump CABG (OPCAB) techniques because the coronary, arteries are still fully perfused while the anastomoses are being, performed. Vessel loops or occluders may be needed. In patients, with extensive aortic calcification, there may not be any room to, place an aortic cannula in or a proximal vein graft on the ascending aorta. In these cases, the right axillary artery may be used for, arterial perfusion, and the saphenous vein can be anastomosed to, the innominate artery if it is free of disease, or a total arterial vascularization approach should be considered with the use of one or, both mammary arteries., Once the anastomoses are completed, the patient is rewarmed, to physiologic temperature and the heart is defibrillated into sinus, rhythm. The use of hypothermic fibrillatory arrest is contraindicated in patients with significant aortic valve incompetence because the ventricle would distend with the regurgitant blood once, fibrillation sets in, and no stroke volume is generated. Increased, ventricular wall tension and energy consumption could lead to, myocardial ischemia., , On-Pump Beating-Heart Bypass, On-pump beating-heart bypass is a selective strategy used for patients who have a very low LVEF and have suffered a recent MI., The logic behind this approach is that the myocardium is severely, compromised and would poorly tolerate further ischemic compromise. Despite currently available techniques for myocardial, protection, cardioplegic arrest is always associated with a certain, degree of ischemia. This is especially true in patients with severe, CAD and a stunned myocardium, in whom uniform protection of, the ventricle with cardioplegia may be difficult to achieve, and an, on-pump beating-heart strategy can be considered. The coronary, arteries continue to be perfused, and exposure and handling of, the anastomoses are similar to those for OPCAB. The use of CPB, offloads the ventricle and offers a safety margin to manipulate the, heart and to visualize all the targets that need to be bypassed. Use, of IABP should be considered for most of these patients because, their hemodynamic state is precarious to begin with., , Off-Pump Coronary Artery Bypass Grafting, The main rationale for using OPCAB was to avoid the adverse effects of CPB related to the systemic inflammatory response caused, by contact of blood components with the surface of the bypass, circuit. This hypothesis, although not supported by much sound, scientific clinical data, spawned the belief that CPB contributed, to various adverse outcomes, including postoperative bleeding,, neurocognitive dysfunction, thromboembolism, fluid retention,, and reversible organ dysfunction. Because OPCAB eliminated the, use of a CPB circuit and could potentially reduce some of these, pump-associated complications, there was a great enthusiasm for, OPCAB. In fact, throughout Asia and particularly in India, 95%, of CABG operations are still performed off-pump., , 1701, , In a nationwide review of the STS database by Bakaeen and, colleagues, the use of off-pump procedures peaked in 2002 (23%), and again in 2008 (21%), followed by a progressive decline in, off-pump frequency to 17% by 2012. Interestingly, after 2008,, off-pump rates declined among both high-volume and intermediate-volume centers and surgeons, and currently in the United, States, this technique is used in fewer than one in five patients, who undergo surgical coronary revascularization. A minority of, surgeons and centers, however, continue to perform OPCAB in, most of their patients., This decline in OPCAB is presumably due not only to the procedure’s technical complexity and steep learning curve but also,, and more important, to the decreased long-term patency, higher, rate of incomplete revascularization, and inferior long-term survival associated with OPCAB., Data from multiple studies have not supported the belief that, OPCAB decreases inflammatory mediator release. Some investigators have shown that even though complement activation may, be reduced, there is no difference in production of cytokines and, chemokines that modulate neutrophils and platelets.43,48 In addition, myocardial ischemia by itself activates complement such as, C5b-9. Thus, great caution should be used in interpreting studies, regarding activation of the inflammatory cascade., The Randomized On/Off Bypass (ROOBY) trial was a prospective RCT of CABG and OPCAB that involved 2203 patients, at 18 Veterans Affairs medical centers. There was no difference, in 30-day mortality or short-term major adverse cardiovascular, events. The OPCAB patients received significantly fewer grafts per, patient. One-year rates of cardiac-related death (8.8% vs. 5.9%;, P = 0.01) and major adverse events (9.9% vs. 7.4%; P = 0.04), were significantly higher in the OPCAB group. Furthermore, graft, patency was significantly lower in the OPCAB group (82.6% vs., 87.8%; P < 0.001). The results did not differ when the operation, was performed by a resident or attending physician or by a highor low-volume surgeon., The Surgical Management of Arterial Revascularization Therapy (SMART) trial examined long-term survival and graft patency, in a prospective RCT involving 297 patients who underwent, isolated elective CABG or OPCAB. After 7.5 years of follow-up,, there was no difference in mortality or late graft patency between, OPCAB and on-pump CABG. Although recurrent angina was, more common in the OPCAB group, this difference did not reach, statistical significance. Hence, this study, performed by one of the, world’s experts in OPCAB surgery, could not demonstrate any, superiority of OPCAB over on-pump CABG., Another prospective study, the Coronary Artery Bypass Surgery Off or On Pump Revascularization Study (CORONARY), trial, involved 4752 patients randomly assigned to either CABG, or OPCAB at 79 centers in 19 countries. There were no significant, differences in the incidence of recurrent angina between the OPCAB (0.9%) and CABG (1.0%) groups, but the need for repeated, revascularization was higher in the OPCAB group, and the difference approached statistical significance (1.4% OPCAB vs. 0.8%, CABG; P = 0.07)., The CORONARY trial included twice as many participants, as the ROOBY trial. Each off-pump procedure was performed by, an experienced surgeon who had more than 2 years of experience, and had performed more than 100 OPCAB cases. Trainees were, not allowed to be the primary surgeon. The rate of crossover from, the off-pump to the on-pump group was lower in the CORONARY trial (7.9% versus 12.4%), suggesting a higher level of, surgical expertise. Despite the improved technical experience of, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1702, , SECTION XI Chest, , highly qualified off-pump surgeons, the need for revascularization, remained higher in the off-pump group., In the German Off-Pump Coronary Artery Bypass Grafts in, Elderly Patients (GOPCADE) trial, patients aged 75 years and, older scheduled for isolated bypass surgery were randomly assigned to on-pump or off-pump surgery. The trial was undertaken, to attempt to define the potential benefits of OPCAB in an elderly group of high-risk patients with multiple comorbidities., The study involved 2539 patients from 12 centers. The primary, end point was the composite of death or major adverse events, (MI, cerebrovascular accident, acute renal failure requiring renal replacement therapy, or need for repeated revascularization), within 30 days and within 12 months after surgery. The secondary, end points included operating room time, duration of mechanical ventilation, transfusion requirements, and ICU and hospital, length of stay., There was no difference in the primary composite end point, (7.0% off-pump vs. 8.0% on-pump; P = 0.40). However, additional revascularization procedures within 30 days were more frequent in the off-pump group (1.3% vs. 0.3%; P = 0.03). Patients, in the off-pump group were less likely to receive blood products;, however, the study had no protocols to determine when transfusions should be given. There was no difference in any of the other, secondary end points. The mean number of grafts was significantly lower in the off-pump group (2.7 vs. 2.8; P < 0.001). The investigators concluded that OPCAB did not improve outcomes in, these elderly high-risk patients. Furthermore, concerns were raised, that the increased need for early repeated revascularization and the, decreased number of grafts in the off-pump group would lead to, an increased incidence of future cardiovascular events, thus exposing these elderly patients to increased morbidity and mortality., These findings have dampened the enthusiasm for OPCAB at, most centers. However, it is our practice to offer OPCAB to patients with single-vessel CAD in the LAD system., The technique and operative strategy of OPCAB differ significantly from those of on-pump CABG. Certain adjuncts are needed to provide adequate exposure of the coronary vessels. Because, the heart is fully contractile and maintaining systemic perfusion,, the manipulation should proceed in a planned and systematic, manner. Both the pleural spaces are opened to allow the heart to, rotate into either side to allow the surgeon to visualize the targets,, especially the lateral and inferior wall. The more critical areas of, the myocardium are revascularized first, which minimizes ischemia time, improves myocardial reserve, and permits more complex manipulation of the heart for the other targets. Mammary, artery–based pedicles are typically approached first because these, do not require a proximal anastomosis, thus providing immediate, coronary blood flow to the bypassed vessel., Once the target vessel is selected, a small area of the coronary, artery is exposed proximal and distal to the planned area of anastomosis to allow placement of vessel loops or bulldog clamps for, proximal and distal control. A coronary occluder may also be, used. Two stabilizers are used to stabilize the myocardium (Fig., 60.17). The fork-octopus has a suction padded tip and is attached, to a multifunctional arm. The fork is positioned so that the limbs, straddle the coronary target, and suction is applied, which attaches the device to the myocardium while the arm is secured in position. The other device consists of a suction cup that is applied to, the apex of the heart and is used to lift it out of the chest to expose, its posterior aspect. A sling attached to the posterior pericardium, allows the heart to be elevated out and enhances visualization of, the posterior targets., , FIG. 60.17 Off-pump coronary artery bypass with vacuum-assisted, multiarticulating arms to position and to stabilize the myocardium. This, minimizes the movement of the heart, allowing the surgeon to feasibly, perform the distal anastomoses. Here, the stabilizer is positioned in preparation for creating a bypass to the left anterior descending artery., , Full heparinization is not needed; in general, 50% of the usual, dose is used. Success of the operation requires coordinated efforts, between the surgeon and anesthesiologist so that adequate systemic perfusion is maintained throughout the operation while allowing a comfortable milieu in which the surgeon can operate., Short-acting beta blockers to slow the heart rate and alpha constrictors to maintain systemic perfusion pressures are important, adjuncts for this procedure., The postoperative management of OPCAB patients is significantly different from that of patients who undergo conventional, CABG, primarily because of the reduced inflammatory effects,, which are more prominent in patients who have undergone CPB., The OPCAB patients do not manifest the vasodilatory response or, massive fluid shifts seen with CPB. Rather, these patients are more, like those who have undergone major general surgery and require, early deep venous thrombosis and balanced postoperative fluid, management. In our practice, all patients who undergo OPCAB, are given aspirin and clopidogrel (Plavix) on the day of surgery., , Minimally Invasive Direct Coronary Artery Bypass, Minimally invasive direct coronary artery bypass (MIDCAB) describes any technique of coronary artery bypass that uses a minimally invasive approach, such as an anterolateral thoracotomy (Fig., 60.18), ministernotomy, or subxiphoid approach, without the use, of a robot. Most MIDCABs are performed on the beating heart, and involve vascularization of the anterior wall. A metaanalysis of, all published outcome studies of MIDCAB grafting performed, from January 1995 through October 2007 has revealed early and, late (>30 days) death rates of 1.3% and 3.2%, respectively. Of, the grafts that were studied angiographically immediately after, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. 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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, , Left internal, mammary, pedicle, , Left, anterior, descending, artery, Pericardium, , Off-pump vacuumassisted stabilizer, , FIG. 60.18 Left thoracotomy approach for performing off-pump left internal mammary to left anterior descending bypass. This is commonly, used in the minimally invasive direct coronary artery bypass approach., Multiarticulating stabilizers are essential for this technique., , surgery, 4.2% were occluded and 6.6% had a significant stenosis (50%–99%). At 6-month follow-up, 3.6% were occluded and, 7.2% had significant stenosis. Long-term follow-up results and, further prospective RCTs comparing MIDCABs with standard, revascularization procedures in large patient cohorts are needed., Although MIDCAB offers several advantages, such as the avoidance of sternotomy and CPB, it is subject to the same limitations, as OPCAB in addition to its own technical challenges and limited, revascularization territory., , Robotics: Totally Endoscopic Coronary Artery Bypass, With the popularity of robotic technology in other surgical specialties, robotic totally endoscopic coronary artery bypass (TECAB), has been in use at select centers. Robotically assisted microsurgical, systems have the theoretical advantage of enhancing surgical dexterity and minimizing the invasiveness of otherwise conventional, coronary artery surgery. The da Vinci system (Intuitive Surgical,, Mountain View, CA) is the most commonly used system. It consists of three major components: surgeon-device interface module,, computer controller, and specific patient interface instrumentation. It allows real-time surgical manipulation of tissue, advanced, dexterity in multiple degrees of freedom, and optical magnification of the operative field, all through minimal access ports. The, technology has seen significant use in valve repair operations and, other surgical specialties as well., With regard to coronary artery bypass, TECAB can be performed on-pump or totally off-pump, and multivessel TECAB is, currently a reality. However, operating times and conversion rates, are much higher with this technology. More important, it is technically more difficult and expensive, and it has a steep learning, curve. Long-term data regarding its durability and safety are unavailable at this point., In the largest TECAB series to date (about 500 cases), success, and safety rates were 80% (n = 400) and 95% (n = 474), respectively. Intraoperative conversion to larger thoracic incisions was, required in 49 (10%) patients. The median operative time was, 305 minutes (range, 112–1050 minutes), and the mean lengths, , 1703, , of stay in the ICU and in the hospital were 23 hours (range, 11–, 1048 hours) and 6 days (range, 2–4 days), respectively. Independent predictors of success were single-vessel TECAB (P = 0.004),, arrested-heart TECAB (P = 0.027), non–learning curve case (P =, 0.049), and transthoracic assistance (P = 0.035). The only independent predictor of safety was EuroSCORE (P = 0.002). Interestingly, the mean time per anastomosis was 27 minutes (range,, 10–100 minutes), which is significantly longer than an average, surgeon would take to accomplish an open anastomosis (i.e., well, below 10 minutes per anastomosis). Also, the LIMA injury rate, was high (n = 24; 5%).49 All these data point to less than perfect, procedures and technology that require further development before they can replace open CABG, which has an excellent track, record and is a proven and reproducible procedure., The current limitations of robotic TECAB include its lack of, applicability to all patients, prolonged operating room time, limited access to all vessels, difficulty in achieving multiarterial coronary grafting, cost, and limited training opportunities. However,, over time, robotic surgery is likely to become a niche specialty for, a subset of surgeons who treat a specific population of patients., , Transmyocardial Laser Revascularization, Patients with chronic, severe angina refractory to medical therapy, who cannot be completely revascularized with percutaneous catheter intervention or CABG present clinical challenges. Transmyocardial laser revascularization (TMLR), either as sole therapy or, as an adjunct to CABG surgery, may be appropriate for some of, these patients. The STS Evidence-Based Workforce has reviewed, available evidence and recommends the use of TMLR for patients, with an LVEF greater than 0.30 and Canadian Cardiovascular, Society class III or class IV angina that is refractory to maximal, medical therapy. These patients should have reversible ischemia of, the LV free wall and CAD corresponding to the regions of myocardial ischemia. In all regions of the myocardium, the CAD must, not be amenable to CABG or PCI., The TMLR procedure uses a high-energy laser beam to create, myocardial transmural channels that were originally thought to, provide direct access to oxygenated blood in the LV cavity. This, is no longer considered to be the mechanism whereby TMLR, reduces the symptoms of IHD. Although some local neovascularization has been documented, the magnitude of changes does, not account for any substantive increases in myocardial perfusion., One mechanism that has been proposed relates to a local effect, on cardiac neuronal signaling. It has been hypothesized that local, tissue injury by TMLR damages ventricular sensory neurons and, autonomic efferent axons, which leads to local cardiac denervation, and anginal relief. Regardless of the mechanism, TMLR therapy is, associated with a reproducible improvement in symptoms. Patients, who undergo TMLR show a persistent improvement in Canadian, Cardiovascular Society angina class. This improvement is observed, in 60% to 80% of patients within 6 months after the operation., , Hybrid Procedures, It is generally accepted that the LIMA to LAD anastomosis is the, single most important component of CABG and confers longterm benefits unmatched by those of any other intervention., State-of-the-art PCIs with DES have produced outcomes competitive with those of vein grafts to non-LAD targets. This has led to, an integrated approach to coronary revascularization, termed the, hybrid procedure. The hybrid procedure consists of a minimally, invasive LIMA to LAD anastomosis in conjunction with PCI of, non–LAD-obstructed coronary arteries., , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1704, , SECTION XI Chest, , This approach has met with initial success, but many potential, pitfalls exist. The procedural costs may be greater than those of, either CABG or DES implantation alone. The timing and staging, of the procedures are uncertain, and limited data are available on, long-term outcomes., , Vascular clamp on, internal mammary, , Previous left internal, mammary conduit, New reversed, saphenous vein graft, , Technical Aspects of Reoperative Coronary Artery, Bypass Grafting, Within 5 years, 15% of CABG patients experience a recurrence, of symptoms, typically angina. This increases to approximately, 40% within 10 years. Recurrent symptoms almost always indicate, either progression of disease in the native coronary circulation or, graft disease. In most cases, the indications for coronary angiography, PCI with or without stenting, or repeated CABG are the, same as for the first operation. Patients who are considered candidates for reoperative CABG are usually older, have more diffuse, CAD, and have diminished ventricular function. Factors that increase the risk for reoperation include the absence of an IMA graft,, younger age at the time of the index operation, prior incomplete, revascularization, CHF, and New York Heart Association class III, or class IV angina., The technical aspects of reoperative CABG differ significantly, from those of the index procedure. Reentry into the chest and, dissection of the old grafts are sometimes challenging. Preparation for femoral cannulation for femorofemoral bypass or axillary, cannulation should be considered with preemptive availability of, blood products. Redo sternotomy is typically completed with an, oscillating saw or after the heart is dissected away from the sternum through a subxiphoid approach. Injury to the right ventricle, or to the aorta or vein grafts is of potential concern. A poorly, placed LIMA graft from the prior operation is also at risk during the sternotomy. If a cardiac or vascular injury is identified, an, assistant holds the sternum together to prevent further bleeding,, and expeditious cannulation of alternative sites is begun with the, institution of CPB. Preoperative CT scans are helpful in planning, the operation., Once the sternotomy is completed, the rest of the adherent, cardiac structures are dissected away from the underside of the, sternum to allow placement of a sternal retractor. No retractor, should be placed unless the heart is adequately dissected away; this, will result in disruption of the aorta or right ventricle, which may, be difficult to control., The next steps are geared toward establishing sites for cannulation. The right atrium and aorta are dissected first; then, the rest, of the heart is dissected away from the pericardium, which may be, performed on CPB. The areas of previous cannulation and vein, grafts are the most adherent regions, whereas the diaphragmatic, aspect is least adherent and provides a good starting point to gain, entry into the correct plane., Manipulation of the old grafts should be kept to a minimum, to avoid distal coronary bed microembolization. Isolation of the, LIMA pedicle is often necessary and should be carefully performed with the ability to start bypass rapidly if an inadvertent, injury occurs (Fig. 60.19). The rest of the operation proceeds, in a similar fashion to primary CABG and can be performed, on-pump or off-pump. In some cases, the procedure can be, performed through a left anterolateral thoracotomy approach., Typically, this approach is used in patients with previous mediastinitis or multiple sternotomies or when an extensive area, of the heart is adherent to the sternum, precluding a safe entry., The vein conduit is anastomosed to the descending aorta in these, cases (Fig. 60.20)., , Old saphenous, vein grafts, , FIG. 60.19 Redo coronary artery bypass grafting. The cannulation is, similar to that used in a first-time coronary artery bypass operation in, most cases. However, identification of coronary targets is much more difficult because of scarring. The course of the prior grafts is useful in identifying the targets. In addition to clamping of the aorta above the previous, vein grafts, the left internal mammary pedicle should be dissected and, clamped separately, if feasible. A single-clamp technique is preferred because it avoids the tedious and potentially dangerous dissection around, the proximal aorta that may be needed to place a partial side-biting clamp., , To summarize, some of the unique difficulties that can be encountered in redo CABG are as follows:, • Injury to heart during sternotomy, • Injury to mammary pedicle, • Limited space on ascending aorta for placement of new grafts, • Inability to identify distal targets because of scars and adhesions, • Limited availability of conduits, • Increased risk of perioperative MI because atheroembolic embolization from diseased vein grafts and diffuse CAD preclude, optimal cardioplegia, • Increased bleeding because of higher inflammatory response, and a more raw surface, • Injury to pulmonary artery during cross-clamping of the aorta, In most published series, the mortality rate of reoperative, CABG patients exceeds that of primary CABG patients., , MECHANICAL COMPLICATIONS OF CORONARY, ARTERY DISEASE, Left Ventricular Aneurysm, The incidence of ventricular aneurysm after AMI has been declining because of early interventional therapies. Of LV aneurysms,, 90% are the result of a transmural MI secondary to an acute occlusion of the LAD. Patients may develop an aneurysm (pseudoaneurysm) as early as 48 hours after infarction, but most patients, develop one within weeks. Approximately two thirds of patients, who develop ventricular aneurysms remain asymptomatic., The 10-year survival rate is 90% for asymptomatic patients and, 50% for symptomatic patients. The most common causes of death, are arrhythmias (>40%), CHF (>30%), and recurrent MI (>10%)., The risk of thromboembolism is low, so long-term anticoagulation is not recommended unless there is a mural thrombus. The, , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, , 1705, , Old saphenous, vein graft, , New saphenous vein graft, , FIG. 60.20 Left thoracotomy approach for recurrent coronary artery disease. This approach avoids the hazards, of a difficult redo sternotomy and is used as an alternative in some cases. New saphenous vein graft: descending thoracic aorta to obtuse marginal bypass., , diagnosis is usually made by echocardiography. Thallium imaging, or PET is useful for determining the extent of the aneurysm and, viability of adjacent regions., Surgery for LV aneurysm is indicated if the patient is scheduled, to undergo CABG for symptomatic CAD, there is contained rupture or evidence of a false aneurysm, or the patient has a thromboembolic event despite anticoagulation. The 5-year postoperative, survival rate has been reported to range between 60% and 80%., In general, surgical repair or resection in conjunction with CABG, results in angina relief and resolution of heart failure symptoms, for most patients., Surgical ventricular restoration is a technical term that describes, the surgical resection of the aneurysm and reconstruction of the, native ventricular geometric shape. This is ideally performed with, CPB and without cardioplegic arrest as long as the aortic valve is, competent. The aneurysm is usually recognized by the paradoxical, movement of the walls compared with the rest of the viable LV, myocardium. The aneurysm is opened, and a purse-string Fontan, stitch is placed at the junction of the viable and nonviable myocardium, which can be manually palpated on the beating heart. A, Dacron or bovine pericardial patch is used to exclude the aneurysm, and the aneurysm is closed over the patch. Two potentially, acute complications that require surgical intervention are postinfarction VSD and postinfarction mitral regurgitation caused by, papillary muscle rupture., , Ventricular Septal Defect, This occurs in less than 1% of patients and is associated with acute, LAD occlusion. The defect is more common in men than in women (3:2) and typically is manifested within 2 to 4 days of the infarction. However, a VSD that occurs in the first 6 weeks after an, , infarct is still considered acute. The VSD is usually located in the, anterior or apical aspect of the ventricular septum. Approximately, 25% of affected patients have a posterior VSD caused by an inferior wall MI due to occlusion of the RCA system or a distal branch, LCA. A full-thickness infarct is a prerequisite for VSD formation., A new, loud, systolic cardiac murmur after an MI suggests the diagnosis; echocardiography is effective for determining the size and, character of the VSD as well as the degree of left-to-right shunting. Right-sided heart catheterization typically shows an increase, in oxygen saturation levels in the right ventricle and pulmonary, artery. The defect is usually approximately 1 to 2 cm in size., After the diagnosis is established, patients should undergo immediate left-sided heart catheterization to characterize the degree, of CAD and the magnitude of LV dysfunction and to detect any, mitral valve insufficiency. Approximately 60% of patients with an, infarction VSD have significant CAD in an unrelated vessel. The, mortality rate in untreated patients is high; 25% of patients die, within 24 hours of refractory heart failure. Survival rates of patients at 1 week, 1 month, and longer than 1 year are 50%, 20%,, and less than 3%, respectively., Patients who are considered candidates for surgery should be, treated early with closure of the defect and concomitant CABG. In, the absence of refractory heart failure and hemodynamic instability, the survival rate may be as high as 75%. The infarct exclusion, technique is used to repair the VSD and is one of the most technically challenging procedures. The LV is opened longitudinally on, the infarct, and the defect is evaluated. Multiple VSDs may be, present, and necrotic myocardium is debrided to viable tissue. A, prosthetic Dacron patch or bovine pericardium is then sutured to, the LV side of the septal defect and brought out through the ventriculotomy, where it is incorporated into the closure (Fig. 60.21)., , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1706, , SECTION XI Chest, , Ventriculotomy, Patch, Felt buttress, , Anterior surface, of heart, , FIG. 60.21 Infarct exclusion technique for repair of acute ventricular, septal defect secondary to acute myocardial infarction. A ventriculotomy, is made through the zone of infarct, and all necrotic muscle is debrided., The repair is accomplished with a patch placed on the left ventricular, aspect of the septum. Felt buttresses are used to reinforce the closure of, the ventriculotomy, and it is essential that all sutures be incorporated into, healthy myocardium to ensure durability of the repair., , In this method, the posterior aspect of the patch is thus anchored, to the remnant viable septum, and the anterior aspect is incorporated with the free ventricular wall, forming the neo–interventricular septum. Felt strips are used to buttress the closure., In addition to the traditional repair of postinfarction VSD,, there has been recent enthusiasm about transcatheter closure of, postinfarction VSD. This obviates a pump run in an otherwise, tenuous patient. In both patients treated surgically and with transcatheter closure, temporary circulatory support in the form of extracorporeal membrane oxygenation or ventricular assist device, can be lifesaving., , Mitral Regurgitation, Approximately 40% of patients who sustain an AMI develop, chronic ischemic mitral regurgitation (IMR) detectable by color, flow Doppler echocardiography. In 3% to 4% of cases, the degree, of mitral regurgitation is moderate or severe., The cause of chronic IMR is ischemic papillary muscle dysfunction and LV dilation associated with mitral annular dilation, and restriction of the posterior leaflet. The operation for chronic, IMR is usually performed on an elective basis. It consists of complete myocardial revascularization and mitral valve repair with the, use of an annuloplasty ring., Acute IMR may result from papillary muscle necrosis and rupture caused by occlusion of the overlying epicardial arteries that, give rise to the penetrating vessels that supply the papillary muscles. The posterior papillary muscle is involved three to six times, , Cross-section, of heart, , FIG. 60.22 Mechanical complication of acute myocardial infarction., Acute papillary muscle rupture (shown here) and acute ventricular septal defect are two sequelae in a patient with extensive zones of infarct., Acute papillary muscle rupture results in acute mitral regurgitation that is, manifested as cardiogenic shock and immediate pulmonary decompensation. If the patient is a surgical candidate, mitral valve replacement is, the only option., , more often than the anterior muscle (Fig. 60.22), and either the, entire trunk of the muscle or one of the heads to which chordae, attach may rupture partially or totally., In most cases, prompt surgical intervention provides the best, chance for survival. Predictors of in-hospital death include CHF,, renal insufficiency, and multivessel CAD. Emergent surgical, treatment usually involves mitral valve replacement and concomitant CABG. The hospital mortality rate may be as high as, 50% in acute cases. Mitral repair should not be attempted in, such cases because it may not be feasible in papillary muscle, rupture; it requires prolonging the cross-clamp time (compared, with replacement), which is not ideal in acute cases. Operations, on patients with acute mechanical complications from MI are, challenging; the surgeon has to anticipate and be prepared for, placement of an LV assist device if the patient cannot be separated from CPB (Fig. 60.23)., , CORONARY ARTERY BYPASS GRAFTING AND, SPECIAL POPULATIONS OF PATIENTS, Patients With Diabetes, Mortality and morbidity rates after CABG are higher in diabetic, patients than in the general population. The BARI trial showed, that diabetic patients with multivessel disease benefit more from, CABG than from any other treatment. Similarly, the FREEDOM, trial also demonstrated superiority of CABG over PCI., , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, , 1707, , Patients With Renal Disease, Renal insufficiency is also an independent risk factor for mortality, after CABG. A preoperative serum creatinine level higher than 1.4, to 2.5 mg/dL is independently associated with a twofold increase, in mortality. In a retrospective study of 59,576 patients who underwent CABG or PCI, CABG had a survival benefit in patients with, a serum creatinine level higher than 2.5 mg/dL. The 1-, 2-, and, 3-year survival rates were 84.1%, 77.4%, and 65.9%, respectively,, for CABG compared with 70.8%, 51.9%, and 46.1%, respectively,, for PCI. This effect was more dramatic in diabetic patients., , Obese Patients, The incidence of postoperative renal failure, prolonged ventilation, and sternal wound infection is significantly higher in obese, patients than in normal-weight patients. Both extremes of weight, are risk factors for CABG-related mortality., , ACKNOWLEDGMENTS, We would like to acknowledge Scott Weldon and Michael DeLaflor for graphic services, and Johnny Airheart for photographic, support., , SELECTED REFERENCES, FIG. 60.23 An axial flow left ventricular assist device, which can be, used as temporary mechanical support or a bridge to transplantation for, a patient in end-stage cardiomyopathy due to coronary artery disease not, amenable to bypass surgery. The inflow of blood into the pump is from, the apex of the left ventricle. The blood is then pumped into the ascending aorta through specially designed grafts that are incorporated into the, pump. The axial flow pumps are less bulky and relatively easy to implant., They have only a single moving part, which is the axial impeller., , Older Patients, Approximately 10% of patients who undergo CABG are older than, 80 years. Older age is an independent predictor of surgical morbidity, and mortality and a nonroutine discharge status. Although CABG, should not be denied to patients on the basis of age alone, it should be, considered during risk assessment. Appropriate arrangements should, be made beforehand with the expectation that only one in five postoperative patients will be able to go home without additional support., , Women, Although women in every age group have a lower incidence of, CAD than men, CAD is still the leading cause of death in women, in the United States. Historically, serious manifestations and associated complications of CAD in women were considered uncommon. Examination of the STS database in two separate studies, has revealed that the operative mortality rate is higher in women,, 3.2% versus 2.6% in men., With evolving strategies, studies have been designed to evaluate, specific aspects of coronary artery bypass that would benefit women., For example, OPCAB has produced favorable outcomes in women., A review of 42,477 patients in the STS National Cardiac Database, revealed that women have a significantly greater adjusted risk of, death and prolonged ventilation and longer length of stay than do, men who undergo on-pump CABG. In contrast, among OPCAB, cases, women had a lower risk of reexploration than men did and a, similar risk of death, MI, and prolonged ventilation and hospital stay., , Chu D, Bakaeen FG, Dao TK, et al. On-pump versus off-pump, coronary artery bypass grafting in a cohort of 63,000 patients., Ann Thorac Surg. 2009;87:1820–1826., This study was a nationwide comparison of on-pump versus, off-pump coronary artery bypass surgery in the United States., The study highlighted the fact that off-pump coronary artery bypass does not produce lower postoperative mortality or stroke, rates than conventional on-pump coronary artery bypass. Furthermore, off-pump coronary artery bypass was associated, with longer hospital stays and higher hospital costs., , Edwards FH, Carey JS, Grover FL, et al. Impact of gender on, coronary bypass operative mortality. Ann Thorac Surg., 1998;66:125–131., This study analyzed the outcomes of more than 300,000 patients from the Society of Thoracic Surgeons database and, used multivariate analysis and risk model stratification to examine the outcomes of female patients. Female gender was, shown to be an independent predictor of higher mortality in, low- to moderate-risk patients but not in high-risk patients., , Influence of diabetes on 5-year mortality and morbidity in a randomized trial comparing CABG and PTCA in patients with, multivessel disease: the Bypass Angioplasty Revascularization, Investigation (BARI). Circulation. 1997;96:1761–1769., Follow-up results from the initial randomized controlled trial established that patients with treated diabetes mellitus who were, assigned to undergo coronary artery bypass grafting (CABG), had a striking reduction in mortality compared with patients, who underwent percutaneous transluminal coronary angioplasty. This benefit was attributed predominantly to the use of the, left internal mammary artery conduit in CABG., , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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1708, , SECTION XI Chest, , Loop FD, Lytle BW, Cosgrove DM, et al. Influence of the internal-mammary-artery graft on 10-year survival and other cardiac events. N Engl J Med. 1986;314:1–6., This retrospective study of 5931 coronary artery bypass grafting patients operated on at a single institution compared the, outcomes of patients who had an internal mammary artery, (IMA) graft with those of patients who had only vein grafts. The, findings of this landmark study established the superiority of, the IMA over any other conduit. During a 10-year period, patients who had only vein grafts had a 1.6 times higher risk of, mortality than those who had mammary grafts., , Lopes RD, Hafley GE, Allen KB, et al. Endoscopic versus open, vein-graft harvesting in coronary-artery bypass surgery. N Engl, J Med. 2009;361:235–244., This retrospective study evaluated the effects of endoscopic, vein harvesting on the rate of vein graft failure and on clinical, outcomes. Endoscopic vein harvesting was shown to be independently associated with vein graft failure and adverse clinical, outcomes compared with open vein harvesting., , Parisi AF, Khuri S, Deupree RH, et al. Medical compared with, surgical management of unstable angina: 5-year mortality and, morbidity in the Veterans Administration Study. Circulation., 1989;80:1176–1189., This prospective, multicenter Veterans Administration randomized controlled trial compared surgical and medical management, and established that, for patients with triple-vessel coronary disease, surgical intervention better promotes survival than medical, management., , Peduzzi P, Kamina A, Detre K. Twenty-two-year follow-up in the, VA Cooperative Study of Coronary Artery Bypass Surgery for, Stable Angina. Am J Cardiol. 1998;81:1393–1399., This study compared the 22-year results of initial coronary artery, bypass grafting surgery with saphenous vein grafts with those, of initial medical therapy with regard to survival, the incidences, of myocardial infarction (MI) and reoperation, and symptomatic, status in 686 patients with stable angina who participated in the, Veterans Affairs Cooperative Study of Coronary Artery Bypass, Surgery. This trial provided strong evidence that initial bypass, surgery did not improve survival for low-risk patients and did, not reduce the overall risk of MI. The early survival benefit with, surgery in high-risk patients did not translate to comparable, long-term survival rates for both treatment groups., , This was a landmark contemporary study of percutaneous coronary intervention (PCI) with drug-eluting stents versus coronary, artery bypass grafting (CABG). The primary end point was a major adverse cardiac or cerebrovascular event (i.e., death from any, cause, stroke, myocardial infarction (MI), or repeated revascularization) during the 12-month period after randomization. Rates of, major adverse cardiac or cerebrovascular events at 12 months, were significantly higher in the PCI group (17.8% vs. 12.4% for, CABG; P = 0.002), in large part because of an increased rate of, repeated revascularization (13.5% vs. 5.9%; P < 0.001); as a result, the criterion for noninferiority was not met. At 12 months,, the rates of death and MI were similar between the two groups;, stroke was significantly more likely to occur with CABG (2.2%, vs. 0.6% with PCI; P = 0.003). The investigators concluded that, CABG remains the standard of care for patients with three-vessel, or left coronary artery disease because the use of CABG, compared with PCI, resulted in lower rates of the combined end point, of major adverse cardiac or cerebrovascular events at 1 year., , Serruys PW, Ong AT, van Herwerden LA, et al. Five-year outcomes after coronary stenting versus bypass surgery for the, treatment of multivessel disease: the final analysis of the, Arterial Revascularization Therapies Study (ARTS) randomized trial. J Am Coll Cardiol. 2005;46:575–581., The final results of the Arterial Revasularization Therapies Study, were summarized and showed that the overall rate of major, adverse cardiac and cerebrovascular events was higher in patients who underwent coronary artery stenting than in those, who underwent coronary artery bypass grafting. This difference was driven by the increased need for repeated revascularization in the stent group., , Shroyer AL, Grover FL, Hattler B, et al. On-pump versus, off-pump coronary-artery bypass surgery. N Engl J Med., 2009;361:1827–1837., This study was a randomized, multicenter Veterans Affairs trial, that compared conventional coronary artery bypass grafting, with off-pump coronary artery bypass (OPCAB) in 2203 patients. The primary end point was a composite of death from, any cause, repeated revascularization, or nonfatal myocardial, infarction within 1 year after surgery. At 1-year follow-up, the, OPCAB patients had worse composite outcomes and poorer, graft patency. The presumed benefit of fewer neuropsychological adverse outcomes was not found in OPCAB patients., , Taggart DP, Altman DG, Gray AM, et al. Randomized trial of, bilateral versus single internal-thoracic-artery grafts. N Engl J, Med. 2016;375:2540–2549., , Serruys PW, Morice MC, Kappetein AP, et al. Percutaneous coronary intervention versus coronary-artery bypass grafting for, severe. N Engl J Med. 2009;360:961–972., , Downloaded for Abhishek Srivastava ([email protected]) at Fortis Escorts Heart Institute and Research Centre from ClinicalKey.com by, Elsevier on November 03, 2021. For personal use only. No other uses without permission. Copyright ©2021. Elsevier Inc. All rights reserved.

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CHAPTER 60 Acquired Heart Disease: Coronary Insufficiency, , The use of bilateral internal thoracic (mammary) arteries for, coronary artery bypass grafting (CABG) may improve long-term, outcomes as compared with the use of a single internal t­ horacic, artery plus vein grafts. Patients undergoing CABG were randomized to undergo single or bilateral internal thoracic artery grafting, in 28 cardiac surgical centers in 7 countries. Among patients, undergoing CABG, there was no significant difference between, those receiving single internal thoracic artery grafts and those, receiving bilateral internal thoracic artery grafts regarding mortality or the rates of cardiovascular events at 5 years of followup. There were more sternal wound complications with bilateral, internal thoracic artery grafting than with single internal thoracic, artery grafting. Ten-year follow-up is ongoing., , Velazquez EJ, Lee KL, Jones RH, et al. Coronary-artery bypass, surgery in patients with ischemic cardiomyopathy. N Engl J, Med. 2016;374:1511–1520., The survival benefit of a strategy of coronary artery bypass, grafting (CABG) added to guideline-directed medical therapy, as, compared with medical therapy alone, in patients with coronary, artery disease, heart failure, and severe left ventricular systolic, dysfunction remains unclear. This study randomized patients, with very low ejection fraction (<35%) to GDMT vs. CABG. At, 10 years in a cohort of patients with ischemic cardiomyopathy,, the rates of death from any cause, death from cardiovascular, causes, and death from any cause or hospitalization for cardiovascular causes were significantly lower over 10 years among, patients who underwent CABG in addition to receiving medical, therapy than among those who received medical therapy alone., , White HD, Assmann SF, Sanborn TA, et al. Comparison of percutaneous coronary intervention and coronary artery bypass, grafting after acute myocardial infarction complicated by, cardiogenic shock: results from the Should We Emergently, Revascularize Occluded Coronaries for Cardiogenic Shock, (SHOCK) trial. Circulation. 2005;112:1992–2001., This randomized controlled trial was designed to compare coronary artery bypass grafting (CABG) surgery with percutaneous, coronary intervention in patients who presented with cardiogenic shock. The trial evaluated 30-day and 1-year mortality, and found comparable results between the two groups, even, though the CABG patients had a higher prevalence of diabetes, and worse coronary artery disease preoperatively., , REFERENCES, 1. Benjamin EJ, Virani SS, Callaway CW, et al. Heart disease and, stroke statistics—2018 update: a report from the American, Heart Association. Circulation. 2018;137:e67–e492., 2. Ford ES, Capewell S. 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