High volume perfusion

Abstract

Modern operative myocardial management strategies have evolved considerably in the brief 35 year history of cardiac surgery supported by extracorporeal circulation. From the early techniques employing normothermic ischemia (‘clamp and run’) to a variety of hypothermic cardioplegic ischemic modalities (crystalloid vs. blood, intermittent vs. continuous, antegrade vs. retrograde), to the novel modern approach of nonischemic warm continuous blood cardioplegia, the cardiac surgeon continues to seek an optimal operative environment in which to conduct complicated cardiac and major vascular repairs. The initial and, indeed, ongoing goal of all myoprotective strategies is not only to provide a quiet, bloodless operative field for a prolonged time in which to effect the desired surgical repair, but also to minimize any ischemic damage to the heart, thereby preserving biochemical and mechanical cardiac function postoperatively. Simply stated, the goal is to maintain myocardial energy and substrate supply in excess of electromechanical and biochemical demand during the time of operation. Thus, modern operative myocardial management strategies optimize the relationship of energy supply to consumption by maintaining aerobic (or anaerobic) substrate metabolism. The capacity of the myocardium to provide metabolic activity in excess of demand will be dependent upon not only the temperature and composition of the perfusate administered during the aortic cross-clamp interval, but also on the distribution, duration and volume of the perfusion. Hence, the topic ‘High volume perfusion’ presented in this chapter.