European versus North American cardioplegia: comparison of Bretschneider's and Roe's cardioplegic solutions in a canine model of cardiopulmonary bypass.

Roe's and Bretschneider's crystalloid cardioplegic solutions were compared in a canine model of total cardiopulmonary bypass with 4.5 hours of hypothermic (27 degrees C) ischemic arrest and 60 minutes of reperfusion. Bretschneider's solution (Group I, six dogs) preserved tissue adenosine triphosphate (ATP) near control levels and maintained coronary effluent pH near 7.0 throughout the ischemic interval, while Roe's solution (Group II, six dogs) allowed progressive acidosis and depletion of ATP (P less than 0.005 versus control). Group I had supranormal left ventricular function during reperfusion (greater than 100% of pre-arrest function) but Group II regained only 40-75% of pre-arrest function. Group I had 2.82% +/- 3.61% necrosis of heart mass and Group II 9.33% +/- 8.26 (P less than 0.10). We conclude that Bretschneider's solution provided better myocardial protection than Roe's solution. The development of acidosis in the Roe group suggests that the more effective buffering of Bretschneider's solution with histidine is the probable basis for its superiority.