Beneficial effect of additional cardioplegia flush during hypothermic static cardiac preservation.

Background. The effects of various preservative solutions and methods have been studied to prolong the safety period of cardiac preservation. In this study, we used cardioplegic solution (CS) during cardiac preservation and investigated how flush CS yields good preservation of isolated hearts compared with only cold immersion. Methods. Male Wistar rat hearts were arrested with 4°C St. Thomas crystalloid CS. All hearts were immersed for 6 hr in a 4°C Euro-Collins solution. Hearts were classified into seven groups by period and number of infusions of CS (20 ml/kg) during simple immersion of hearts. Infusion of CS during preservation was not used for group I. Infusion was performed at two hours after starting immersion for group II, at 3 hr for group III, at 4 hr for group IV, at 5 hr for group V, every hour for group VI, and every 2 hr for group VII. After preservation, the hearts were reperfused with blood using a support rat. Myocardial adenosine triphosphate was measured immediately after immersion of hearts. Biochemical examination of coronary effluents was performed at 15 min after reperfusion, and cardiac function was evaluated at 40 min after reperfusion. Myocardial specimens were subsequently taken for measurement of water content. Results. Percentage recovery of left ventricular developed pressure and dp/dt in groups III, VI, and VII were higher than those in group I at each balloon volume, and left ventricular end-diastolic pressure in these groups was also significantly lower than that in group I. Levels of creatine kinase-MB and lactate in groups VI and VII after reperfusion were significantly lower than those in group I. Myocardial adenosine triphosphate was significantly better preserved in groups III, IV, VI, and VII than in group I. However, no significant difference in cardiac function or myocardial adenosine triphosphate was found among groups III, IV, VI, and VII. Conclusions. The use of CS during cardiac preservation is effective in preserving cardiac function and myocardial enzymes, and infusion may be sufficient if performed once-only at 3 or 4 hr from starting immersion in 6 hr storage of isolated rat hearts.