Myocardial Blood Flow in Coronary Artery Disease

Sixteen patients, 10 with significant three-vessel coronary artery disease (>50% occlusion of each vessel) and six without coronary disease, had nutrient myocardial blood flow, cardiac output, pressure time/min and arterial pressure determinations at rest, with atrial pacing and with right atrial pacing plus nitroglycerin. In the patients with coronary disease, nutrient myocardial blood decreased an average of 16% (P < 0.001) with pacing alone but increased by 22% (P < 0.001) from the pacing flows with the addition of 0.4 mg sublingual nitroglycerin at the same pacing rate. The directional changes in myocardial blood flow were unrelated to perfusion pressure or pressure work. In the patients without coronary disease, opposite effects were observed. With right atrial pacing, nutrient myocardial blood flow increased by 23% (P < 0.02). With the addition of nitroglycerin, myocardial blood flow decreased by 15% (P < 0.02). These changes were directionally related to changes in pressure-work of the heart It is suggested that the findings in this study are consistent with observations made in the experimental animal which indicate that the effect of nitroglycerin may be partly due to a redistribution of myocardial blood flow.