Modified perfusion and loading technique of the isolated canine heart.

The technique of donor perfusion of the isolated canine heart is described. It is carried out with the aid of a specially developed system providing both retrograde resuscitational coronary perfusion of the heart which sustained ischemia and perfusion with functional volume-systolic loadings of the left ventricle of the working heart under nearly physiologic conditions. This technique was used in the first group of experiments (control) to study the performance of the heart which did not sustain ischemia, and in two groups of experiments with cardioplegia. In the experiments of group II the corrected autologous blood which served as perfusate had the following composition: Hb 8.3 g%; K+ 2.4 mEq/l; pH 7.7; osmolarity 307 mosm/l; pO2 250-450 mm Hg; temperature 13-15 degree C. The hearts were preserved for 2 h following single-dose perfusion . In the experiments of group III the corrected autologous blood had the following composition: Hb 8 g%; K+ 20-25 mEq/l; pH 7.7; osmolarity 320 mosm/l; pO2 300-500 mm Hg; temperature 13-15 degrees C. Coronary perfusion was carried out every 20 min during the 2-hour preservation period. The studies of coronary hemodynamics and cardiac function using the developed system showed practically identical results in groups I and III. In group II deep depression of myocardial function due to ischemic injury was found. The presented data on a comparative assessment of cardiac function in three groups of experiments demonstrate the high value of the developed technique of perfusion and functional loading of the myocardium.