Comparison between preload recruitable stroke work and the end-systolic pressure-volume relationship in man

We compared linearity, inotropic sensitivity (using dobutamine) and afterload dependency (using captopril) of contractile indices derived from the end-systolic pressure-volume relationship (ESPVR) and preload recruitable stroke work (PRSW) in man. We investigated 60 patients, 39 with normal (EF > or = 50%, group 1) and 21 with decreased ventricular function (EF < 50%, group 2). Variably loaded P-V loops were constructed by conductance catheters with vena caval occlusions. The slopes of the ESPVR (Emax) and PRSW (Mw) were assessed by linear regression analysis. The correlation coefficients of the ESPVR (r = 0.964) and PRSW (r = 0.976) were both very high, but the Z-value of the ESPVR was lower than for PRSW. During the control period, normalized Emax and Mw were significantly higher in group 1 than group 2 (Emax: 4.6 +/- 2.3 vs 2.8 +/- 0.8 mm Hg ml-1 m-2, Mw: 109 +/- 31 vs 86 +/- 28 10(3) dyn cm-2. After dobutamine, Emax and Mw increased significantly both in group 1 (128% and 124% vs control respectively) and in group 2 (132% and 130% respectively). After captopril, the ESPVR tended to shift to the right with a decrease in afterload; PRSW was unchanged. We conclude that PRSW may be a more linear and reliable index for evaluation of contractility in man.