TOTAL ARTERIAL COMPLIANCE ESTIMATED BY STROKE VOLUME TO AORTIC PULSE PRESSURE RATIO IN HUMANS

On the basis of the windkessel model, the stroke volume-to-aortic puls e pressure ratio (SV/PP) has been proposed as an estimate of total art erial compliance, but recent studies have questioned this approximatio n. Aortic pressure was obtained at rest in 31 adults undergoing cardia c catheterization (47 +/- 14 yr): controls (n = 7), patients with dila ted cardiomyopathy (n = 10), and patients with other cardiac diseases (n = 14). me calculated PP, mean aortic pressure (MAoP), heart period (T), SV (thermodilution cardiac output/ heart rate), total peripheral resistance (R), total arterial compliance estimated by area method (C- area), and the time constant of aortic pressure decay in diastole (RCa rea). In the overall population (n = 31), there was no significant dif ference between SV/PP and C-area. SV/PP was linearly related to C-area (SV/PP = 0.99C(area) + 0.05; r = 0.98; P < 0,001); the slope and inte rcept did not differ fr om unity and zero, respectively. Similar resul ts were obtained in the three subgroups. These results implied that PP /MAoP and T/RCarea, were proportionally related (T/RCarea = 1.18PP/MAo P - 0.07; r = 0.96; P < 0.001). We conclude that for humans at rest re liable estimate of C-area and 2) T normalized by the time constant of aortic pressure decay in diastole was proportionally related to PP/MAo P. This last relationship could be considered an aspect of the couplin g between the left ventricle and its load.