A clinical application of histidine buffered cardioplegia

Blood cardioplegia has been widely accepted due to better oxygen delivery, pH buffering and free radical scavenge. We have found that a crystalloid cardioplegia solution formulated to accelerate anaerobic glycolysis with high buffering capacity. To conserve blood cardioplegia, we formulated a crystalloid cardiopletia containing 100 mM histidine for buffering. This cardioplegia (HBS) was compared to cold blood cardioplegia in patients requiring open heart surgery. Eighty patients including HBS (n = 28), and CBC (n = 40) were involved in this study. Left ventricular end-systolic elastance (Emax; mmHg/cm3) was evaluated pre- and postoperatively. Cardiac index and inotropic requirement were also monitored at 1, 3, and 12 hours after cardiopulmonary bypass. There was no death in either group. All hearts returned to previous rhythm in HBS group, whereas total 12 DC cardioversions were requested in 6 patients. Emax was significantly higher in HBS group (5.2 +/- 0.6 mmHg/cm3) than in CBC group (3.4 +/- 0.4 mmHg/cm3). Cardiac index was also significantly higher in HBS group postoperatively than in CBC group with lower inotropic requirements. We conclude that histidine containing crystalloid cardioplegia provides excellent recovery of cardiac performance with lower inotropic requirements in open heart surgery. The ease of use, and lack of blood are other important advantages of this crystalloid cardioplegia.