An Index for Estimation of Oxygen Consumption in Rat Heart by Hemodynamic Parameters

To find a suitable index for the estimation of O2 consumption of rat hearts by use of hemodynamic parameters, isolated hearts were perfused under different working conditions. Coronary flow, arteriovenous O2 difference, cardiac output, and ventricular pressure curve were recorded and continuously fed into a computer. O2 consumption and different hemodynamic parameters such as dP/dtmax, maximum ventricular pressure, pressure-time integral, and heart rate were computed on-line. With the use of these data of 64 different steady states, numerous formulas containing hemodynamic parameters were tested with respect to their ability to predict O2 consumption. The best fit of the data was obtained by a linear combination of the products of rate times dP/dtmax and rate times pressure-time integral of one beat (r = 0.993). Indexes containing approximations of wall stress were not found to improve the predictive ability.