Con: Deep hypothermic circulatory arrest must be used selectively and discreetly

Abstract

F OR SEVERAL DECADES, surgical teams have used the protective benefits of deep hypothermia (16°C to 2OT) for repair of complex heart defects during surgery.‘~5 Early clinical success using this technique led to the additional application of total circulatory arrest for intracardiac repair.6 Currently, the application of deep hypothermic circulatory arrest (DHCA) includes its use for intracardiac repair of congenital heart defects in infancy, acquired aortic arch disease in adults, and certain neurosurgical procedures. The putative advantages of DHCA include the shortening of overall cardiopulmonary bypass (CPB) time; a more exacting anatomic repair in a bloodless, cannulafree operative field; and the ability to perform operations on the aortic arch that otherwise cannot be repaired.’ As superb surgical results for complex congenital and acquired heart defects have been achieved, this progress has now led to the examination of the quality of life of patients surviving these operations. While the development and success of the modern pump-oxygenator in clinical practice has been truly remarkable, advances in cerebral protection during cardiac surgery have neither come as quickly nor gone as far as those in myocardial protection. As perioperative death (usually cardiac in origin) has declined over time, even in high-risk patient populations, postoperative neuropsychological dysfunction has emerged as an increasingly important aspect of cardiac surgical morbidity. With the availability of sophisticated techniques for examining the central nervous system and the growing concern for the quality of life, the effects of DHCA have become more widely investigated in recent years. The initial interest in this technique is now being met with mixed enthusiasm. The avoidance of DHCA at some institutions in favor of continuous, low-flow CPB is reflective of the concern for DHCA and its potential for neuropsychological injury. Because the brain is the organ most vulnerable to ischemia, concern has been expressed over the years regarding the safety of DHCA, specifically, the effect of DHCA on brain structure and function. Despite the routine clinical application of DHCA, now into its third decade, the technique is largely empirical, and mechanisms of cellular integrity and protection are poorly understoodP