The Cardiac Patient & Surgery

Patients with known or suspected cardiac disease undergoing general surgery present a common management problem. Anesthesia and surgery are often associated with marked fluctuations of heart rate and blood pressure, changes in intravascular volume, myocardial ischemia or depression, arrhythmias, decreased oxygenation, increased sympathetic nervous system activity, and alterations in medical regimens and pharmacokinetics. Even with careful monitoring and management, the perioperative period can be very stressful to cardiac patients.

The risk of surgery in patients with heart disease depends primarily on three factors: the type of operation, the nature of the heart disease, and the degree of preoperative stability. The type of anesthesia is less important, though halothane, enflurane, and barbiturates are more severe myocardial depressants, whereas narcotics have little depressive effect. Spinal and epidural anesthesia were previously thought to be preferable in patients with heart disease, but this has not proved to be the case.

The highest-risk procedures are surgery of the aorta and vascular procedures, in part because these patients often have associated severe coronary disease but also because marked blood pressure and volume changes are common.

Major abdominal and thoracic surgery are also associated with substantial cardiovascular risk, especially in older patients with associated cardiovascular disease.

Numerous studies have evaluated the excess risk of surgery in patients with various cardiac diseases. Recent (within 3 months) myocardial infarction, unstable angina, congestive heart failure, and significant aortic stenosis are associated with substantial increases in operative morbidity and mortality rates. Any degree of instability in these conditions magnifies the potential risk. Stable angina, especially in an inactive individual, is also associated with a higher operative risk. Although less common, cyanotic congenital heart disease and severe primary or secondary pulmonary hypertension pose great risks during major surgery. In patients with any of these problems, the risk-to-benefit ratio of the planned surgery should be carefully examined. If the procedure is necessary but elective, consideration should be given to delaying it until full recovery postinfarction and correction or optimal stabilization of the other conditions are achieved. Hypertension should be at least moderately controlled. Patients with severe angina should have increased medical therapy or be considered for revascularization before noncardiac surgery. Symptomatic arrhythmias, nonsustained ventricular tachycardia, or high-grade atrioventricular block and cardiac failure should be treated optimally.

Clinical assessment provides the most useful guidance in determining the risk of noncardiac surgery. Important indicators of high risk have been discussed above. Patients with known but clinically stable heart disease, such as angina pectoris or prior myocardial infarction, are at intermediate risk, particularly for major operations such as vascular surgery. If a history or symptoms of heart failure are present, assessment of left ventricular function can be very helpful in perioperative management. Although frequently advocated, further noninvasive testing for myocardial ischemia for the purpose of risk stratification is probably overutilized. Tests such as stress myocardial perfusion scintigraphy or dobutamine echocardiography should be reserved for situations in which the results may alter patient management. There is no evidence that prophylactic revascularization by either PTCA or coronary artery bypass surgery alters long-term outcome in patients undergoing noncardiac surgical procedures without the usual indications for PTCA or CABG. Only in the case of major vascular operations is perioperative mortality and morbidity high enough that prophylactic PTCA or CABG should be considered.