Comparison of the solutions of Bretschneider, St. Thomas' Hospital and the National Institutes of Health for cardioplegic protection during moderate hypothermic arrest

We evaluated three cardioplegic solutions, Bretschneider's cardioplegic solution (HTK), St. Thomas' Hospital solution (STH) and the solution of the National Institutes of Health (MH), a solution with added nitroglycerin and lidocaine, for their ability to minimize ischemia-reperfusion injury in a working rat heart model. After cardioplegic arrest at 4 degrees C and subsequent 45 min of ischemic storage at 25 degrees C the function recovery of hearts was examined during 1 h of normothermic crystalloid reperfusion using Krebs-Henseleit buffer as perfusion medium. We noted a significantly better preservation of the maximum (+dp/dt(max)) and minimum (-dp/dt(max)) velocity of pressure development and a significantly higher coronary flow with the use of HTK (2,657 mm Hg/s, 2,122 mm Hg/s, 17 ml/min) compared to STH (1,600 mm Hg/s, p < 0.05; 1,591 mm Hg/s, p < 0.05; 11 ml/min, p < 0.05), and an intermediate level of preservation of hemodynamic parameters with NIH (2,149 mm Hg/s, 1,766 mm Hg/s, 12 ml/min). Concerning the cardiac output, however, no major difference was found between the HTK (41 ml/min), the STH (34 ml/min) and the NIH group (36 ml/min). The decay of the myocardial energy charge was significantly lower in both the HTK and the NIH group as compared with conservation in STH solution. Lactate was lowest in the HTK group, CK and LDH releases in the effusate remained lowest after HTK and NIH preservation. The data of this study suggest that HTK and MH most perfectly reduce the impairment of myocardial function and provide better myocardial protection during ischemic arrest at 25 degrees C and superior recovery compared to STH solution.