Hypoplastic left heart syndrome.

HLHS is a complex developmental malformation of the left ventricle, aorta, and associated valves. Survival beyond neonatal life is the exception in untreated infants. The prognosis, however, is no longer hopeless. Newer surgical strategies of staged palliative reconstruction and heart replacement by transplantation appear promising. These options on occasion will become complementary in the management of individual patients. Those children surviving Fontan operations are frequently able to lead NYHA Class I or II lives without drugs, while transplant recipients will require one or more immunoregulative medications indefinitely. Exercise tolerance and work capacity following the Fontan procedure are reported to be 40 to 60 per cent of expected normals. Full functional capacity of successfully palliated children may never be normal. In contrast, exercise capability after heart transplantation is generally better than that following a Fontan operation, with cardiac ejection fractions approaching normal for age. Durability of these new management technologies will make inappropriate the traditional "do nothing" approach to HLHS in all but a few cases.