Myocardial blood flow in coronary artery disease. Effect of right atrial pacing and nitroglycerin.

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 dis-