Influence of timing and magnitude of arterial wave reflection on left ventricular relaxation

The influence of timing and magnitude of arterial wave reflection (WR) on a fterload-dependent relaxation was evaluated in patients with a variety of h eart diseases (group 1, age< 30 yr; group 2, age> 40 yr) and in dogs. While both femoral arteries were compressed (FC), WR returned just after the dic rotic notch (early diastole) in group 1 but before the dicrotic notch (late systole) in group 2. The time constant of the left ventricular pressure de cay (tau) was shortened during FC in group 1, whereas it was prolonged in g roup 2. In dogs, a constriction of the thoracic aorta induced a late systol ic augmentation of WR with a prolongation of tau (cf. group 2), whereas con striction of the lower abdominal aorta induced an early diastolic augmentat ion of WR with a shortening of tau (cf. group 1). With aortic constriction, coronary flow increased, and there was a close correlation between the pea k change in backward aortic pressure and that in coronary flow regardless o f the timing of WR. Thus the time at which WR returns during the cardiac cy cle may have an important effect on left ventricular relaxation and coronar y flow.