Real time analog computation of left ventricular systolic pressure volume area as predictor of oxygen consumption.

An analog circuit was devised for real time determination of the left ventricular systolic pressure volume area (PVA), which we had recently identified as a reliable predictor of cardiac oxygen consumption rate per beat. PVA is the specific area in the pressure-volume diagram that is bounded by the end-systolic and end-diastolic pressure-volume relationship lines and the systolic segment of the pressure-volume loop trajectory of the left ventricle. The computed PVA was compared with PVA obtained as usual by planimetry. Correlation coefficient between the two PVA's was 0.997 (N=31, P less than 0.001) and the standard error of mean of the difference between th two PVA's was as small as practically negligible 8 mmHg ml in the PVA range from 0 to 2,000 mmHg ml. We concluded that this PVA analog computer can be used for real time determination of PVA, expediting the future studies of the relationship between PVA and cardiac oxygen consumption.