Regression of cardiac oxygen consumption on ventricular pressure-volume area in dog

Left ventricular systolic pressure-volume area (PVA) has been reported to be a reliable predictor of cardiac oxygen consumption rate per beat (VO2) in a given heart with a stable inotropic background. PVA is the specific area in the pressure-volume (PV) diagram, consisting of the area (EW) within the PV loop and the area (PE) bound by the end-systolic and end-diastolic PV lines and the relaxation segment of the PV loop. EW and PE correspond to the external mechanical work and the end-systolic elastic potential energy in the ventricular wall, respectively. We determined the optimal combination of EW and PE for the best prediction of VO2, using the linear multiple regression analysis. From EW, PE, and VO2, data of many isovolumic and ejecting contractions, the optimal coefficients of EW and PE were 1.67 +/- 0.43 (SD; 7 hearts) and 1.74 +/- 0.49 (10(-5) ml O2/mmHg . ml), virtually identical to each other, corroborating that PVA, i.e., a simple sum of EW and PE, can reliably predict VO2 of a given heart in a stable contractile state.