The left ventricular end-systolic pressure-volume ratio. Studies during changes in load and inotropism in the human

Ascending aortic pressures and left ventricular volumes were measured simultaneously in 65 patients in the basal state and during changes:(1)in load by sodium nitroprusside (n = 21) or by angiotensin (n = 6), (2) in inotropism by post-extra-systolic potentiation (PESP)(n = 18) and increase in heart rate (atrial pacing)(n = 20). Thirty patients had normal hearts (group I), 35 had or had had the symptoms left ventricular failure complicating the course of an idiopathic cardiomyopathy (group II). All were in sinus rhythm. The slope of the end-systolic pressure (ESP)—end-systolic volume (ESV) relationship (ETS) and the ESP/ESV. ratio (EES) were greater in group I than in group II. There was no difference between ETS and EES. EES discriminated the normal patients from those with cardiomyopathy as well as (dp/dt) max, [dp/dt)/Pt] max, EF or VCF. In the two groups, EES was independent of loading changes. This ratio increased after post-extra-systolic potentiation and during atrial pacing. Two findings in patients with ventricular failure were unexplained: (1) in 1/3 of the patients EES did not correspond to the maximum value of the instantaneous pressure-volume ratio: (2)the Vd was higher in group II than in group I and close to 48 ml.