EFFICACY OF LACTOBIONATE-ENRICHED CARDIOPLEGIC SOLUTION IN PRESERVINGCOMPLIANCE OF COLD-STORED HEART-TRANSPLANTS

Cardioplegic solutions of the extracellular type are commonly used as storage media for heart transplants. Because this type of formulation was not originally designed for preventing hypothermically induced ede ma, we assessed the effects of supplementing a standard, extracellular -like cardioplegic solution with the high molecular weight impermeant lactobionate on water content and postischemic compliance of isolated rat hearts. In one series of experiments, hearts were immersed in eith er a standard cardioplegic solution of the extracellular type or in th e same solution supplemented with lactobionate (80 mmol/L). Hearts wer e then processed for measurements of water content after 4 hours, 6 ho urs, and 8 hours of storage at 4-degrees-C. In a second series of expe riments, hearts were stored in the same solutions for 4 hours and 8 ho urs and subsequently reperfused for 1 hour on a Langendorff column, at which time left ventricular pressure-volume curves were constructed a nd compared with those obtained during the preischemic perfusion. Lact obionate-treated hearts gained significantly less water than controls after 4 hours and 6 hours of storage, but the difference was no longer significant at the 8-hour time point. In contrast, the treated group yielded a significantly better recovery of compliance after both 4 hou rs and 8 hours of storage, suggesting that lactobionate might exert pr otective effects in addition to those caused by its impermeant propert ies, possibly involving calcium chelation and subsequent limitation of calcium-dependent contracture. Extracellular-type cardioplegic soluti ons are attractive because a single solution can be used during all ph ases of the transplantation procedure. Our results suggest, however, t hat for enhancing their effectiveness in preserving compliance of card iac grafts, their formulation needs to be tailored to the specific nee ds of the cold-stored heart, which implies, among other things, that i t incorporates high molecular weight impermeants.