Heart efficiency from uncalibrated intraventricular pressure-admittance diagrams (DPY)

Using the pressure-admittance diagram (DPY) as an estimator of the pressure-volume diagram (DPV), the authors obtained ventricular efficiency from the area encompassed by the loop (stroke work, SW) divided by the total PYA area (equivalent to PVA), i.e., the area surrounded by the end-diastolic curve, the systolic segment of the diagram, and the end-systolic line. The basic concept underlying this calculation derives from the linear relationship between cardiac oxygen consumption and PVA, as reported by H. Suga et al. (1981). In five animals under control conditions, values ranged, as expected, from 17.6% to 28.1%, showing a significant increase (p<0.05) after an inotropic maneuver (range: 21.2%-40.0%). The diagrams need not be calibrated in absolute terms, which is an attractive feature.<>