Early and late effects of the coronary bypass operation on cardiac contractility and coordination

Abstract

In 100 cases of coronary heart disease, cardiac contractility was studied before and after coronary bypass by a flow method, the force ballistocardiogram, and by a pressure method, the carotid pulse derivative. The two methods gave very similar results in most cases, and the agreement of their averages was impressive. A marked increase in cardiac strength, reaching its maximum a month or two after operation, followed the procedure in most cases. Cardiac coordination was also improved at this time in many subjects, but complete cardiac normality was very rarely attained. This early postoperative improvement was greater in hearts judged to be weak before operation than in those judged to be normal in strength. The early cardiac improvement was seldom held in its entirety, but usually declined at a rate, which, if continued, would abolish the postoperative improvement in about three years. This rate of cardiac decline was many times faster than that found in healthy persons or in unoperated cases of mild angina as age advanced. Nevertheless, in over 1 3 of our cases followed for a year and a half or longer, their hearts were still stronger or better coordinated, or both, than they had been before operation, and there is reason to believe that the decline was leveling. At their last test, the great majority of patients still reported that subjective improvement in their angina continued. This subjective improvement was significantly related to objective improvement of cardiac contractility in our data, but there was one striking exception to this rule. Previous studies of results following internal mammary artery ligation and the Vineberg procedure afford an important control to the present work.