Interrelations between coronary artery pressure, myocardial metabolism and coronary blood flow.

Characteristically, the coronary circulation has been studied in the time-honored way of varying a single experimental variable while attempting to hold other hemodynamic variables constant. This has produced two-dimensional descriptions of coronary physiology where coronary blood flow vs. coronary artery perfusion pressure, or coronary blood flow vs. myocardial oxygen consumption, are plotted. However, the physiology is more complicated than these plots can show, because coronary blood flow and myocardial metabolism interact. Accordingly, a three-dimensional analysis of coronary physiology has been made where coronary artery pressure and myocardial oxygen consumption are the primary determinants of coronary blood flow, but interactions among all three variables are included. Data on coronary autoregulation and myocardial oxygen consumption have been combined, while maintaining mass balance, to form a three-dimensional surface that describes local metabolic control of coronary blood flow. Using this description of state in three dimensions, simulations of coronary physiology with and without coronary artery stenosis were performed which provide insight into the simultaneous variations in coronary artery pressure, myocardial metabolism and coronary blood flow.