REVERSAL OF VENTRICULAR CONTRACTURE DURING HYPOTHERMIC CARDIOPLEGIC ARREST

Ventricular contracture was produced in isolated perfused rat hearts b y a novel method using repeated administration of an anoxic cold hyper kalemic cardioplegia solution. Contracture could be reversed by reperf usion with the same solution, without calcium (Group 1), oxygenated (G roup 2), or oxygenated and calcium free (Group 3). Group 1 hearts unde rwent partial reversal of contracture; in Group 2, contracture was rev ersed more completely, but the effect was transient. Hearts in Group 3 had contracture reversed completely to a level lower than prearrest e nd diastolic pressure. Hearts in contracture were profoundly depleted of high-energy phosphates (ATP, 9% of control; creatine phosphate, 27% ) and the success of contracture reversal was parallelled by the exten t to which each solution repleted ATP and PCr. Ventricular contracture produced by energy depletion is rapidly reversed by restoration of ox ygen to the myocardium. Reducing extracellular calcium by acalcemic pe rfusion is ineffective as an isolated measure but is synergistic with reoxygenation and enhances contracture reversal. (C) 1994 Academic Pre ss, Inc.