Quantification of O2 consumption and arterial pressure as independent determinants of coronary flow.

The steady-state relationship between coronary arterial blood flow (CBF) and both myocardial O2 consumption (MVO2) and coronary arterial pressure (P) was explored in anesthetized dogs and goats. Both species were subjected to constant pressure perfusion of the left main coronary artery by an external pressure-controlling circuit. In addition a group of goats was studied with normal aortic perfusion using an occluder around the left main coronary artery to vary coronary arterial pressure. The statistical analysis revealed that despite the direct effect of P on MVO2 (the Gregg effect) the effects of both variables on CBF were independent and linear over a wide range of P and MVO2 so that multiple regression analysis with a linear equation (CBF = a X P + b X MVO2 + c) gave an excellent fit which was not improved by the introduction of an addition interactive term b3MVO2 X P. The mean correlation coefficient for all animals was greater than 0.9. From these data we conclude that any factor regulating coronary arterial flow would be influenced by both MVO2 and perfusion pressure in an independent way. This study characterizes the stationary behavior of local coronary flow control. Hence, it specifies quantitatively the relations to be predicted by hypotheses aiming to explain this control mechanism.