Single Ventricle Heart Defects and Effect of Surgical Treatment on Prognosis

Abstract

Hypoplastic left heart syndrome (HLHS) is characterized by underdevelopment of the left heart with significant hypoplasia of the left ventricle including atresia, stenosis or hypoplasia of the aortic or mitral valve (or both valves), and hypoplasia of the ascending aorta and aortic arch. The anatomic defects of HLHS result in the support of the right ventricle for both the pulmonary and systemic circulation. Survival is dependent on a patent ductusarteriosus (PDA) for systemic perfusion, and an adequate atrial septal defect (ASD) for sufficient mixing of oxygenated and deoxygenated blood. The diagnosis of HLHS is made by echocardiography. Antenatal diagnosis is possible during a routine obstetrical ultrasound screening in the 2nd trimester of pregnancy. The timing and severity of presentation vary in neonates who are not diagnosed prenatally, and are dependent on the presence and size of an ASD and patency of the ductusarteriosus. Physical findings that are commonly observed in the natural course of HLHS include cyanosis, respiratory distress, cool extremities, and decreased peripheral pulses. If untreated, 95 percent of patients with HLHS die as neonates (first 30 days of life). With the advancement of medical intervention and the introduction of the staged palliative surgical repair, five-year survival rates have improved to 65 percent.