Use of nifedipine during cardiac surgery for improved myocardial protection

The combined results of extended clinical trials conducted in two centers following successful laboratory trials are evaluated. From a population of 4,777 patients who underwent open heart surgery, 205 high-risk patients were selected for study. One hundred seventy patients (3.6 percent) were given nifedipine in cardioplegic solution. The remaining 35 patients served as control subjects and were compared with 39 treated patients in the randomized subset of 74. One third of the patients underwent valve replacement, one quarter underwent coronary artery bypass, and 40 percent underwent combinations of valve replacement, coronary artery bypass, and other procedures. Characteristically, the third group had a 50 percent increase in end-diastolic volumes and low cardiac indexes (1.7 +/- 0.1 liters/minute/m2). Average cross-clamp time was 77 minutes. At one center, an extracellular hyperkalemic-type solution was used to deliver an average dose of 407 +/- 22 micrograms nifedipine per patient. At the other center, a low-sodium hyperkalemic solution was used, and the average nifedipine dose was 476 +/- 22 micrograms. Hemodynamic studies in the randomized subset demonstrated approximately a twofold improvement in the treated group in cardiac index, stroke volume, stroke work index, and pulmonary vascular resistance following cardiopulmonary bypass. The incidence of acute low cardiac output death was 4 percent versus 11 percent in the control group. Survival for all treated patients was 86 percent. It is concluded that the addition of nifedipine reduced the incidence of acute global cardiac failure in the immediate postoperative interval.