Postoperative neurodevelopmental outcome of patients with hypoplastic left heart complex: hybrid versus Norwood strategy

Abstract

Besides survival, the neurological status of patients after surgical treatment of congenital heart defect constitutes the most important indicator of the outcome in the current era. Nowadays, it is well documented in the literature a state of immaturity of the brain in neonates born with congenital heart disease that makes them particularly susceptible either to newly occurring brain damage or to worsening of pre-existing brain lesions when subjected to cardiopulmonary bypass surgery [1]. This susceptibility would be further enhanced by special techniques used for the reconstruction of the aortic arch, namely the deep hypothermic circulatory arrest or the antegrade lateral cerebral perfusion [2]. This is the main explanation of the clear tendency of some centres to pursue the treatment of congenital heart disease less aggressively than in the past, by restoring traditional palliative techniques or introducing modern interventional tools, all designed to appeal to the extracorporeal circulation, whenever possible, beyond the terms of the fateful neonatal period [3]. The rationale for the hybrid procedure for treatment at the first stage of hypoplastic left heart complex should be exactly that. In spite of such rationale, literature provides controversial data regarding both survival and myocardial performance in patients undergoing hybrid procedure compared with those treated with Norwood operation. For instance, although avoiding cardiopulmonary bypass and cardioplegic arrest, the early postoperative haemodynamic profile of the hybrid procedure has been reported as not being superior to the Norwood in terms of cardiac output and pulmonary blood flow. As a matter of fact, the acute pressure load imposed by the bilateral banding to the already volume-loaded right ventricle would play a detrimental effect on myocardial performance both directly and mediated by increased circulating vasocontrictors. The resultant increase in systemic vascular resistance would be responsible for a potential for pulmonary overcirculation, with somehow elevated Qp:Qs ratios, the major benefit of the hybrid procedure residing in the avoidance of high VO2 states rather then tight control of Qp [4]. The paper by Knirsch et al .[ 5] provides further data to the evidence that deprive the hybrid procedure of the role of panacea revealing a substantial overlap of data regarding the neurodeve