NONMEDICAL MANAGEMENT OF ANGINA PECTORIS



Coronary artery bypass surgery is useful to re­lieve angina unresponsive to medical therapy and, in certain subgroups, to prolong life. Coro­nary artery bypass surgery may be combined with aneurysmectomy in patients with refractory car­diac arrhythmias, congestive heart failure, or re­current emboli due to a large ventricular aneu­rysm. Coronary artery bypass alone usually does not improve left ventricular function sufficiently to treat patients in whom congestive heart failure is the major manifestation of ischemic heart dis­ease. Intractable, chronic ventricular arrhythmias also are not usually abolished by revasculariza­tion alone and require resection of the tachycardia focus.

Coronary artery bypass grafting most commonly involves harvesting saphenous veins from the legs to anastomose from the ascending aorta to the cor­onary artery at a site distal to the obstruction. The veins are reversed in direction to permit the flow of blood past the venous valves. As many major arterial branches as possible are grafted beyond significant obstructions. Internal mammary grafts demonstrate a superior long-term patency compared with saphenous grafts. Both the left and right internal mammary arteries may be dissected free and anastomosed to a coronary artery distal to its obstruction. The proximal take-off of the in­ternal mammary artery remains intact from the subclavian artery. Internal mammary grafts are most commonly anastomosed to the left anterior descending coronary artery vessels. The distal coronary vessels must be at least 1 to 2 mm in diameter to accept a bypass graft, and the flow distal to the occlusion, determined at the time of coronary arteriography, should be sufficient to maintain flow in the grafts so that thrombosis is unlikely to occur. Left ventricular dysfunction in­creases the risk of surgery but does not necessarily contraindicate surgery if chest pain is refractory. Perioperative mortality is approximately 0.7 per cent for those with normal left ventricular function and 1.8 per cent for those with abnormal ventricular function. Surgical mortality in pa­tients with left main coronary artery disease is ap­proximately 2.5 per cent, and if left ventricular function is abnormal, approaches 4 per cent. Sur­gical mortality increases with age, reaching 2 per cent in patients older than 65 years. The incidence of perioperative myocardial infarction is reported to be 5. to 10 per cent. Chest pain is completely relieved in approximately 65 per cent of patients, and significant improvement in pain occurs in an additional 25 per cent. The remaining patients are either not improved (5 per cent) or worse (5 per cent] after surgery. Approximately 2 to 4 per cent of patients per year have a recurrence of angina, due either to obstruction of the grafts or to pro­gressive atherosclerosis in the native arteries. If angina recurs either early or late after surgery, re­peat catheterization may be indicated if surgery or angioplasty is deemed necessary. Repeat op­erations carry a higher surgical risk and less suc­cessfully relieve pain.