IMPROVING FUNCTION OF HEARTS PRESERVED FOR 24 HOURS BY CONTROLLING REPERFUSION (1979)

SUMMARY With the use of an extracorporeal working dog heart preparation, we studied whether the function of hearts undergoing 24 hr of 4 C ischemic arrest is improved by initially reperfusing the hearts with a modified blood perfusate. Hearts were arrested and cooled to 4 C using either a modified extracellular solution (DKS) or a modified Collins solution. After 24 hr at 4 C the preserved hearts were perfused with either normal blood at 35 C or with a cardioplegic blood perfusate at 20 C. Five or more hearts were included in each of the four subgroups. The subgroups subjected to the modified blood perfusate were switched to normal blood perfusion after an initial 45 min of perfusion at an arterial blood pressure of 45 to 50 mm Hg Hearts preserved with the modified Collins solution when perfused only with normal blood attained an average left ventricular (LV) function of 75% of control, while the hearts preserved by the same method but reperfused initially with blood cardioplegia attained 93% of control LV function (P < 0.01). Hearts preserved for 24 hr with the DKS solution maintained synchronous beats but did not work when perfused with normal blood, but functioned at 40% of control levels when initially reperfused with blood cardioplegia Hearts preserved with modified Collins and initially reperfused with blood cardioplegia had tissue levels of Na and K not significantly different from control hearts; the ratio of [K]/[Na] being 1.5 Hearts preserved by the same method but reperfused only with normal blood had significantly higher tissue levels of Na than control hearts, the ratio of [K]/[Na] being only 1.1. All hearts preserved with DKS for 24 hr lost K and gained Na By using a modified Collins preservation solution and by controlling the reperfusion environment, dog hearts were preserved for 24 hr with nearly normal LV function Our current cardiac preservation techniques allow 5 hr to transport hearts from nearby cities to our cardiac transplantation center, thereby dramatically increasing the chances that the recipient will receive a heart before dying. The capability of preserving the heart for 24 hr would greatly increase the donor pool and allow us to take advantage of LD matching Both our laboratory (1) and others (2-5) have described techniques permitting the heart to undergo 24 hr of ischemic storage and still function. Furthermore, we have shown that canine hearts stored for 24 hr in a modified Collins solution at 4 C can support the life of recipient dogs for several days after orthotopic transplantation. However, despite these encouraging results, the present preservation techniques are unsatisfactory Left ventricular function is considerably depressed following preservation, and some hearts become hemorrhagic following reperfusion (1-3,5). In addition, recovery time of left ventricular function after reperfusion is excessive, being 2½ hr or longer (1). Therefore, we have attempted to improve the function of hearts stored for extended periods, and to decrease the damage suffered by the hearts. Our studies show that the ultimate function of preserved hearts can be improved by controlling the immediate reperfusion environment, and that recovery times can be shortened