Surgical therapy for the univentricular heart.

The natural history of the univentricular physiology is determined primarily by the presence (severity) or absence of obstruction to pulmonary blood flow and secondarily by the single ventricular cardiomyopathy that develops in response to chronic volume overload. Important obstruction to pulmonary blood flow will affect survival because of severe hypoxia and may necessitate surgical treatment (systemic to pulmonary artery shunt or cavopulmonary shunt depending on the age of the patient and a host of other factors). In the absence of significant obstruction to pulmonary blood flow, the symptomatology is one of congestive heart failure with later development of irreversible pulmonary vascular disease. In this situation, a pulmonary artery band is indicated to limit pulmonary blood flow and reduce pulmonary artery pressures to acceptable levels. Even in the presence of significant limitation of pulmonary blood flow, the single ventricle is a volume-loaded ventricle as it receives both pulmonary and systemic venous return. Chronic volume overload and persistent hypoxia is detrimental to ventricular function and gradually lead to the development of atrioventricular valve incompetence. Complete separation of oxygenated and deoxygenated blood may be obtained by ventricular septation in suitable cases (beyond the scope of this presentation) or by systemic venous diversion to the pulmonary (the Fontan circulation) arteries thus achieving complete oxygenation simultaneous with abolition of any recirculation.