ASSESSMENT OF TRANSMYOCARDIAL PERFUSION IN ALLIGATOR HEARTS

Background Techniques for achieving myocardial perfusion directly from the left ventricular chamber are currently under investigation. Altho ugh originally based on the anatomy of reptilian hearts, which are ric h in transmural channels and reported to have a poorly developed coron ary vasculature, the blood Bow capacity of a transmyocardial blood sup ply has not been studied in these hearts. With the ultimate goal of pr oviding insight into the potential for achieving transmyocardial perfu sion in human hearts, we studied the relative contribution of transmyo cardial and coronary perfusion in alligator hearts. Methods and Result s After explantation from six American alligators, the left ventricle was instrumented, and coronary arteries were perfused with oxygenated physiological solution. Using microspheres to estimate regional myocar dial perfusion in the beating hearts, we show that although the epicar dium was well perfused by the coronary arteries (0.20 +/- 0.08 versus 0.07 +/- 0.01 mL . min(-1). g(-1) owing to flow from the ventricular c hamber), a significant proportion of endocardial perfusion was from th e ventricular chamber (0.21 +/- 0.07 mL . min(-1). g(-1) from the left ventricle versus 0.13 +/- 0.04 mL . min(-1). g(-1) from coronary arte ries). Conclusions A significant amount of direct transmyocardial perf usion is present in alligator hearts. The conditions that apparently p ermit this situation in reptilian hearts are reviewed, and their impli cations for aiding in the optimization of techniques for achieving tra nsmyocardial flow in humans are discussed.