Hypoplastic Left Heart Syndrome and Variants

Hypoplastic left heart syndrome (HLHSHypoplastic left heart syndrome (HLHS)) is a rare congenital heart diseaseCongenital heart disease in which the left ventricleVentricles and supporting structures are underdeveloped and unable to support the systemic circulation. The condition is universally fatal if untreated. Many patients are now identified prenatally but undiagnosed patients may present postnatally on routine neonatal screening or with respiratory distress and hemodynamic shock following PDAPersistent ductus arteriosus (PDA) closure. Peri-operative management is dependent on maintaining unobstructed systemic outflow, optimizing cardiac output, and balancing of systemic and pulmonary circulations. Surgical correction is not possible, and most patients undergo staged surgical single ventricleSingle ventricle palliation toward a FontanFontan physiology. The Norwood procedure is the first stage surgery and pulmonary blood flow can be achieved with RVBorderline right ventricle (RV)-PA conduit or modified BTT shunt with similar long-term outcomes; the RVBorderline right ventricle (RV)-PA conduit being most common. A hybrid procedureHybrid procedure or primary transplantation are reserved for high-risk subgroups. Restrictive atrial septum may lead to arterialization of pulmonary veinsPulmonary veins and pulmonary lymphangiectasia and portends poor prognosis. Fetal interventions considered to improve patient outcomes include balloon dilation or stenting of intact or severely restrictive atrial communicationRestrictive atrial communication and aortic valvuloplasty.