Limited Sanguineous Reperfusion Reduces Ventricular Fibrillation Following Intermittent Cold Crystalloid Cardioplegic Arrest

Introduction A still and bloodless operative field provides the surgeon with optimal conditions to perform delicate coronary anastomosis, while effective myocardial protection avoids myocardial injury during this process.1 Cold crystalloid cardioplegia has been the cornerstone of this strategy by inducing electromechanical arrest and further reducing oxygen demand with hypothermia.2 In spite of demonstrable improvements attributed to blood-based hyperkalaemic solutions,3,4 including superior preservation of myocardial and coronary endothelial function, 5,6 especially in the setting of a dysfunctional or ischaemic myocardium,7-9 crystalloid solutions remain in widespread use. The technique of warm substrate-enhanced sanguineous reperfusion, delivered under controlled flow and pressure, is recognized as a valuable adjunct to blood-based cardioplegia, but is not part of the crystalloid protocol. Popularly known as the ‘hot shot’, it provides endogenous oxygen free radical scavengers and prevents myocardial substrate derangement.10,11 However, simple normokalaemic blood reperfusion, under certain conditions, and without substrate enhancement, may still attenuate reperfusion injury by providing acid-base homeostasis via the bicarbonate buffering system.12 The method of its administration may partly reproduce the controlled pressure and flow conditions in the hot shot, by limiting the initial blood flow during early reperfusion.