Limited sanguineous reperfusion reduces ventricular fibrillation following intermittent cold crystalloid cardioplegic arrest

Abstract

Background: Cold crystalloid cardioplegic arrest remains a well recognised method of myocardial protection. This strategy does not allow for a controlled hyperkalaemic sanguineous reperfusate, known as a “hot shot” which is administered under constant flow and pressure conditions in order to limit reperfusion injury. We investigated the use of intermittent, antegrade cold crystalloid cardioplegia (St Thomas’ I solution) combined with a limited flow normokalaemic sanguineous reperfusion and measured the outcome in terms of the incidence of reperfusion ventricular fibrillation. Methods: Patients requiring coronary revascularization of at least two coronary arteries, including an internal thoracic artery (ITA) anastomosis, were studied in this prospective randomized trial. Myocardial protection was by intermittent, antegrade cold crystalloid cardioplegia. In the control group (n=100), after completion of the distal anastomoses, the heart was reperfused by releasing the aortic and ITA clamps concomitantly. In the study group (n=100) the ITA was allowed to perfuse the heart for 3 minutes before the aortic cross-clamp was removed. The presence of reperfusion ventricular fibrillation from the moment of reperfusion until weaning from cardiopulmonary bypass was recorded. Results: Mean ischaemic times varied marginally between the study and control groups (study 35.60±8.65, control 35.79±10.64, p=0.89). The incidence of ventricular fibrillation decreased with an increase in the number of grafts and was significantly lower in the study group (double grafts 2/9, 22.2% vs 19/25, 76.0% p=0.004; triple grafts 2/39, 4.9% vs 16/33, 48.5% p<0.001; and quadruple grafts 2/45, 4.4% vs 13/35, 28.7% p<0.001). Conclusions: This strategy of myocardial protection combines the advantages of conventional crystalloid cardioplegia with the added benefit of limited sanguineous reperfusion. It is cost-effective and simple to apply. The results suggest a beneficial effect with regard to reperfusion-induced injury, as evidenced by a significantly reduced incidence of reperfusion ventricular fibrillation.