Oxygen consumption and pressure-volume area of abnormal contractions in canine heart

Oxygen consumption rates (VO2) of isovolumic and normally ejecting contractions are closely correlated with their systolic pressure-volume areas (PVA) in a stable canine left ventricle. PVA is the area in the pressure-volume (PV) diagram that is circumscribed by the end-systolic and end-diastolic PV relation curves and the systolic segment of the PV loop trajectory. We studied whether VO2s of abnormally loaded ejecting contractions were similarly correlated with their PVAs. Various abnormally ejecting contractions were produced in the left ventricle of the cross-circulated canine heart. VO2 and PVA data of the various abnormal contractions and the isovolumic and normally ejecting contractions were pooled together, to which the correlation and regression analyses were applied. They could be fitted by a linear regression analyses were applied. They could be fitted by a linear regression line with a high correlation coefficient and a slight scatter in each heart. We therefore conclude that PVA is the primary correlate of VO2, not only in the isovolumic and normally ejecting contractions but also in various abnormally loaded contractions in a given canine left ventricle with a stable contractile state.