[Significance of myocardial blood flow and metabolism in valvular aortic stenosis for the indication for operation (author's transl)].

Coronary venous blood flow measured by continuous thermodilution, myocardial oxygen consumption and lactate extraction rate were estimated at rest and during graded heart rate exercise in 21 patients with compensated aortic valve stenosis and in 10 patients without heart disease. Significant differences between the groups were found only in coronary sinus flow, however not in coronary perfusion related to 100 g of left ventricular muscle mass. As regards indication for operation patients with aortic valve stenosis were differentiated according to transvalvular pressure differences. Pressure gradients of more than 90 mm Hg (n = 5) were associated with significant lowering of weight-related myocardial perfusion and oxygen consumption and high lactate production during stimulation. This evidence of myocardial ischaemia was also seen in 3 out of 11 patients with a pressure gradient between 51 and 90 mm Hg. The rest of the patients showed no significantly different measurements in comparison with the control group. Thus insufficient myocardial perfusion during exercise is likely in patients with transvalvular pressure differences of more than 90 mm/Hg and possible when the difference is more than 50 mm Hg.