Coronary Graft Flow and Glucose Tolerance: Evidence Against the Existence of Myocardial Microvascular Disease

Abstract

Patients having coronary bypass for stable angina pectoris were grouped on the basis of the two hour plasma sugar of the glucose tolerance test: Group I, 120 mgs% (159 grafts); Group II, 120-150 (93 grafts); Group III, 150-200 (131 grafts) and Group IV, 200 (57 grafts) or patients receiving therapy for diabetes mellitus (10 patients, 21 grafts). Five of 10 diabetic patients had genetic evidence of diabetes and an average duration of therapy of 6.5 years. Blood flow was measured in 461 grafts with an electromagnetic flow probe after discontinuation of cardiopulmonary bypass in a stable state, after a 30 second graft occlusion and after injection of 15 mg of papaverine into the graft. Mean arterial pressure, graft flow and coronary resistance for each succeeding group did not vary significantly when compared with Group I. Analysis of phasic flow in 10 grafts to the left anterior descending indicates that the same proportion of flow occurs during systole and diastole in the basal state and after pappaverine. Coronary flow and resistance in patients with abnormal glucose metabolism and maturity onset diabetes do not provide evidence for the existence of myocardial microangiopathy.