Is repeated administration of blood-cardioplegia really necessary?

The aim of this work was to question the necessity of repeated administration of warm blood cardioplegia in modern cardiac surgery. A consecutive series of 4014 patients underwent cardiosurgical procedures in the period from January 2001 to December 2006 in our centre, where modified Calafiore warm blood-cardioplegic solution was used. 1708 patients received a single shot of cardioplegia instead of repeated blood cardioplegia (every 20 min). A multivariate analysis was performed using logistic regression models to reveal the statistical significance of the effect of single-shot cardioplegia on the occurrence of: death, intraoperative need of inotropics, intraoperative intra-aortic balloon pump (IABP), postoperative infarction, arrhythmia, postoperative need for inotropics and postoperative IABP. The results showed statistical insignificance concerning mortality (P=0.704), intraoperative IABP (P=0.247), postoperative inotropics (P=0.273), postoperative IABP (P=0.678), postoperative arrhythmia (P=0.661). Single-shot cardioplegia showed a positive effect concerning postoperative myocardial infarction (P=0.003). However, it showed an unfavourable effect concerning intraoperative inotropics (P=0.038) and postoperative dialysis (P=0.015). The clinical safety of the first shot of warm blood cardioplegia might be exceeding 20 min. In the light of increasingly short cross-clamping time, the safety of the first shot might be long enough to cover the whole cross-clamping time.