Prevention of cardiac complications in peripheral vascular surgery.

The prevalence of severe coronary artery disease in peripheral vascular patients exceeds 50 per cent. It is therefore not surprising that complications of coronary artery disease are the most common causes of mortality following peripheral vascular operations. If the incidence of cardiac complications is to be reduced, it is first necessary to identify patients at risk through screening tests that will reliably detect hemodynamically important coronary occlusive disease. The operative risk can then be reduced by modifying the magnitude of the procedure, taking measures that can enhance the tolerance for a specific operation, or employing a combination of both. Screening methods in current use include risk factor analysis, exercise testing, routine coronary angiography, and dipyridamole thallium-201 scintigraphy. The risk factor approach has the advantage of being widely applicable since it makes use of historical, physical, and electrocardiographic findings that are already familiar to surgeons and anesthesiologists. It is also inexpensive. However, it may overlook the patient who has no symptoms of coronary artery disease, possibly as a result of the sedentary lifestyle imposed by complications of peripheral vascular disease. The electrocardiographically monitored stress test will identify the asymptomatic patient with occult coronary disease and is helpful in predicting operative risk. However, a meaningful test is dependent on the patient's ability to exercise--an activity that is frequently limited by claudication, amputation, or arthritis. Exercise testing also suffers from a lack of sensitivity and specificity when compared with coronary arteriography. Routine preoperative coronary angiography overcomes the exercise limitation of treadmill testing but is not widely applicable as a screening test for reasons of cost and inherent risk. Dipyridamole thallium-201 scanning, on the other hand, is safe and of relatively low cost and does not require exercise. Further, it has a high degree of sensitivity and specificity when compared with coronary arteriography. It appears to be an accurate predictor of postoperative cardiac complications.