TEMPOROSPATIAL HETEROGENEITY OF MYOCARDIAL PERFUSION AND BLOOD-VOLUMEIN THE PORCINE HEART WALL

Spatial heterogeneity of myocardial perfusion has been recognized for many years. Whether this is primarily the result of heterogeneity of p arameters such as myocardial metabolism, of intramyocardial mechanical forces, or of vasomotor function within the myocardial microcirculati on, is not clear. A practical problem is that it has been almost impos sible to measure any two of these parameters simultaneously in the sam e piece of myocardium so that an unambiguous correlation, much less a cause-and-effect relationship, has been difficult to establish. In thi s study of six anesthetized pigs, we propose that whole-body computed tomography is a method for providing the simultaneous measurement of h eterogeneity of myocardial perfusion (F) and myocardial blood volume ( rho). The first finding was that the empirical relationship rho = AF BF0.5 between myocardial blood flow (F) and intramyocardial blood vol ume (rho) is maintained over a range of sizes of regions of interest ( approximately 1 to 0.125 cm(3)) within the myocardium of each individu al animal despite the spatial heterogeneity of the F and the rho value s. The value of A ranges from 0.014 to 0.021 min and of B ranges from 0.061 to 0.076 ml(0.5) g(-0.5) min(0.5). A second finding was that the pattern of spatial heterogeneity of F and of rho remained reasonably stable over at least a 1 h period. (C) 1998 Biomedical Engineering Soc iety.