NA+ H+ EXCHANGE INHIBITION IMPROVES LONG-TERM MYOCARDIAL PRESERVATION/

Background. Na+/H+ exchange plays an important role in the ionic chang es observed during myocardial ischemia and reperfusion. We investigate d the cardioprotective efficacy of a selective Na+/H+ exchange inhibit or, -3-methylsulfonyl-benzoylguanidin-methanesulfonate (HOE642), in a canine model of long-term heart preservation. Methods. Canine donor he arts were stored for 24 hours in hyperkalemic crystalloid cardioplegic solution; in cardioplegic solution enriched with HOE642; in cardiople gic solution enriched with HOE642, with donor and recipient treated wi th HOE642; in standard cardioplegic solution, with donor and recipient treated with HOE642; or in standard cardioplegic solution, with only the recipient treated. After orthotopic transplantation, pressure-volu me relationships were obtained and dogs were weaned from bypass. Morph ology was studied. Results. Myocardial compliance was well preserved w hen donor and recipient were treated. These groups had the lowest myoc ardial water content, and no morphologic signs of irreversible damage. In these groups, weaning from cardiopulmonary bypass was successful i n 10 of 10 animals, with a cardiac index around 2 L.min(-). m(-2). Onl y 3 of 5 animals in each of the other three groups could be weaned, wi th significantly lower cardiac indices. Conclusions. Treatment with HO E642 in both donor and recipient improves myocardial compliance, postw eaning cardiac index, and ultrastructure of donor hearts preserved for 24 hours and orthotopically transplanted. (C) 1998 by The Society of Thoracic Surgeons.