[Effect of nicardipine hydrochloride on myocardial protection in "in situ isolated dog heart"].

This study was undertaken to determine the effect of nicardipine hydrochloride on myocardial protection in "In situ isolated dog heart". To assess the myocardial function, recovery of the left ventricular function, myocardial water content and myocardial ultrastructure were evaluated before 90-minute cardiac arrest and after 60-minute reperfusion. Isovolemic left ventricular function was evaluated with an intraventricular balloon method (balloon volume, 5-20 ml) using a preparation of "In situ isolated dog heart". The spontaneous cardiac beat after 90-minute cardiac arrest was obtained in 71.4% (5 out of 7 dogs) at the cases with a cold potassium cardioplegic solution (K:23 mEq/L, Na: 25.2 mEq/L) with nicardipine hydrochloride (0.25 mg/L), nicardipine group. At the cases with a cold potassium cardioplegic solution without the nicardipine, control group, however, 100% (7 out of 7 dogs) needed the countershock to get the spontaneous cardiac beat. The nicardipine group showed significantly better recovery results of LVSP, positive dp/dt and negative dp/dt as compared to the control group. The left ventricular distensibility and LVEDP were well-maintained in the nicardipine group. The control group demonstrated a significant increase of myocardial water content after 60-minute reperfusion. The electron microscopic findings revealed that the myocardial ultrastructure in the nicardipine group were less injured as compared to that of the control group. It was concluded that the cold potassium cardioplegic solution with the nicardipine hydrochloride offers superior myocardial protection as compared to that without the nicardipine and is useful in clinical trial.