New arteries for old

Abstract

The internal thoracic artery has emerged as the coronary bypass graft of choice. Initially it was favored because of proximity to the anterior descending artery, little discrepancy in size between graft and recipient vessels, and high early patency rate. Later investigation showed relative freedom from arterial degeneration. In contrast to the 40-60% patency rate for vein grafts at 10-12 years postoperatively, the arterial graft patency exceeds 90%. Theories about protection from atherosclerosis are now directed toward vasoactive properties of the arterial wall. Exercise scintigraphic studies indicate that flow from a thoracic artery graft to the anterior descending artery relieves ischemia at peak myocardial demand. As expected, an arterial conduit that provides consistently high long-term patency also significantly improves 10-year survival in patients with one-, two-, or three-vessel disease. This extended longevity applies to patients with normal and abnormal left ventricular function. Late myocardial infarction, reoperation, and hospitalization for cardiac causes are significantly reduced by performance of an internal thoracic artery graft to the anterior descending coronary artery. These results have stimulated greater usage of these arterial grafts as bilateral, free, and sequential anastomoses. Preliminary reports indicate that patency related to expanded use is similar to that obtained with an in situ left thoracic artery graft. Indications and relative contraindications to arterial grafting in context of these current findings are discussed in this overview.