Age-dependent and hypoxia-related differences in myocardial protection during pediatric open heart surgery

Background-Current cardioplegic protection techniques used in pediatric car diac surgery do not take into consideration age and cyanotic differences. T he aim of the present work was to address this question by monitoring clini cal outcome, myocardial metabolism, and reperfusion injury in pediatric pat ients protected by cold-crystalloid cardioplegia. Methods and Results-Fifty-eight patients (31 children and 27 infants) with or without hypoxic stress (cyanosis) undergoing open heart surgery with col d-crystalloid cardioplegia were included in the study. Clinical outcome mea sures assessed included inotropic and ventilatory support, intensive care, and hospital stay. Ischemia-induced changes in metabolism (adenine nucleoti des, purines, lactate, and amino acids) were determined in ventricular biop sies collected at the beginning and end of ischemic time (cross-clamp time) . Reperfusion injury was assessed by measuring postoperative serial release of troponin I. Evidence was observed of ischemic stress during cardioplegi c arrest in children and infants as shown by significant changes in cellula r metabolites. Compared with infants, children had significantly less reper fusion injury and better clinical outcome, and these factors were related t o duration of ischemic time. Cyanosis did not influence outcome in infants, but cyanotic children showed worse reperfusion injury and clinical outcome than acyanotic children. Conclusions-Extent of myocardial protection with cold-crystalloid cardiople gia in pediatric open heart surgery is dependent on age and degree of cyano sis.