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 pulse pressure ratio (SV/PP) has been proposed as an estimate of total arterial compliance, but recent studies have questioned this approximation. Aortic pressure was obtained at rest in 31 adults undergoing cardiac catheterization (47 +/- 14 yr): controls (n = 7), patients with dilated 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 (RCarea). In the overall population (n = 31), there was no significant difference 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 intercept did not differ fr om unity and zero, respectively. Similar results were obtained in the three subgroups. These results implied that PP/MAoP and T/RCarea, were proportionally related (T/RCarea = 1.18PP/MAoP - 0.07; r = 0.96; P < 0.001). We conclude that for humans at rest reliable estimate of C-area and 2) T normalized by the time constant of aortic pressure decay in diastole was proportionally related to PP/MAoP. This last relationship could be considered an aspect of the coupling between the left ventricle and its load.