Optimal timing of the second stage of palliation for hypoplastic left heart syndrome facilitated through home monitoring, and the results of early cavopulmonary anastomosis

For children with hypoplastic left heart syndrome, contemporary management over three stages includes a window of high risk for sudden death between the initial stage of palliation, the Norwood operation itself, and the second stage, creation of the bidirectional superior cavopulmonary connection. The risk is highest at a time when patients have been discharged from the hospital to grow and prepare for the second stage, and has persisted despite the remarkable improvements in immediate postoperative and hospital survival after the initial surgery. Potential contributing factors to the increased vulnerability to sudden death between the stages include the limited circulatory reserve inherent in the parallel circulations supported by a functionally univentricular heart, the reliance on a prosthetic shunt which is susceptible to thrombosis, and congenital or acquired anatomical cardiovascular abnormalities such as aortic atresia, residual obstruction in the aortic arch, tricuspid valvar insufficiency, or right ventricular dysfunction.