[Effects of coronary stenosis and mean aortic pressure on coronary blood flow, poststenotic coronary pressure, and reactive hyperemia].

Six dogs were subjected to an acute stenosis of the left anterior descending coronary artery. The mean aortic pressure was fixed with a windkessel and an occluder on four different levels. A significant decrease of coronary blood flow and poststenotic coronary pressure was closely related to the level of mean aortic pressure. With lower aortic pressure the decrease occurred earlier than with higher aortic pressure. A 50% stenosis did not significantly influence coronary flow and poststenotic coronary pressure. A 90% stenosis resulted in decrease below 10% of control. In a range of aortic pressure between 60 and 140 mm Hg reactive hyperemia was significantly diminished at a 60% stenosis. Reactive hyperemia was completely abolished when coronary stenosis was 90%.