COMPARISON BETWEEN REGIONAL MYOCARDIAL PERFUSION RESERVE AND CORONARYFLOW RESERVE IN THE CANINE HEART

Diameter stenosis and flow reserve are indices of morphological and fu nctional severity of coronary artery stenosis. Flow reserve can be det ermined at coronary arterial or at myocardial level. In the preserve o f functional collateral circulation, coronary flow reserve and myocard ial perfusion reserve may differ. We studied coronary flow, coronary f low reserve and myocardial perfusion reserve in an open chest dog mode l with intact collateral circulation, before and after induction of co ronary artery stenosis. Coronary flow was determined with perivascular ultrasonic flow probes and myocardial perfusion reserve from digital angiographic images, in the stenotic as well as the adjacent nor-steno tic coronary arteries. Before induction of a stenosis, a significant c orrelation existed between coronary flow reserve and myocardial perfus ion reserve of the left anterior descending (r=0.59; P<0.005) and the left circumflex arteries (r=0.84, P<0.005). In stenotic arteries, coro nary flow reserve and myocardial perfusion reserve decreased significa ntly (P<0.005), but in the adjacent non-stenotic arteries coronary flo w reserve was not affected. Myocardial perfusion reserve in the non-st enotic adjacent left anterior descending artery decreased significantl y (P<0.05) and no correlation was found between coronary flow reserve and myocardial perfusion reserve, whereas in the adjacent non-stenotic left circumflex artery there was no statistically significant decreas e (4.1+/-1.6-->3.5+/-1.4) but there was a good correlation between cor onary flow reserve and myocardial perfusion reserve (r=0.85; P<0.005). This study demonstrates that, in the presence of a stenosis and funct ioning collateral circulation, coronary flow reserve is not a reliable predictor of myocardial perfusion reserve; both parameters provide mu tually complementary information.