Abstract
Despite recent progress in surgical outcomes for congenital malformations in neonates and young infants, postoperative myocardial dysfunction due to ischemic-reperfusion injury remains a major contributor to morbidity and mortality in the settings of increasingly complex surgical procedures and longer ischemic duration.
A wide variety of clinical profiles of pediatric patients in addition to a number of conflicting experimental results concerning the role of cardioplegia in immature hearts may preclude a definitive conclusion to determine the most favorable cardioplegic strategy in the field of pediatric myocardial protection.
Recently, randomized comparative clinical trials were conducted to compare crystalloid and blood cardioplegia (BCP) for pediatric heart surgery, and the majority of studies demonstrated superior cardioprotective effects of BCP coupled with terminal warm BCP in terms of a reduction in biochemical injury, including myocardial ATP content and cardiac troponin release, at least in the selected categories of patients (i.e., prolonged aortic clamping and cyanotic patients). Nevertheless, the multi-institutional randomized study with an appropriate stratification according to the patient age, ischemic time, and type of procedure will be mandatory in order to conclude the true role of individual cardioplegic solution. In view of suboptimal myocardial protection by the standard cardioplegic solution of immature hearts, which are associated with the unique structural and functional characteristics and often exacerbated by preoperative hypoxia and pressure and volume overload, a recent trend in investigations has been oriented towards the development of the cardioplegic solution specialized for pediatric hearts (i.e., del Nido solution containing lidocaine and magnesium). Furthermore, a novel concept of myocardial protection, including normokalemic polarizing arrest with adenosine and lidocaine to substitute for the standard depolarizing cardioplegia and ischemic pre/post conditioning as a supplementary therapeutic modality has been tested clinically in pediatric open-heart surgery.
