Tricuspid Atresia is one of the so-called Single Ventricle congenital heart diseases. Single Ventricle refers to the congenital heart defects in which the heart functionally has only one pumping chamber. Examples are Tricuspid Atresia, Hypoplastic Left Heart Ventricle, Double Inlet Left Ventricle, and Double Outlet Right Ventricle. Other defects (e.g. some forms of Atrioventricular Canal Defect and Pulmonary Atresia) may create single ventricle conditions in the heart.

Adult patients with these defects will usually have had a Fontan Operation. In cases where early treatment consisted of a Glenn procedure and/or the insertion of a shunt between the systemic circulation and the pulmonary artery (e. g. modified or classic Blalock-Taussig Shunt), the patients may be candidates for the Fontan in later life. Very rarely, a person with Single Ventricle reaches adulthood without treatment and without symptoms. These patients may or may not receive the Fontan, depending on an assessment of the relative risks and benefits.

Most patients who have not had the Fontan Operation will begin to show symptoms of cyanosis (external blueness caused by oxygen-poor arterial blood), fatigue, arrhythmias, and/or exercise intolerance, generally because of insufficient blood flow to the lungs through the pulmonary artery. They will also have a heart murmur because of pulmonary stenosis (narrowing of the outflow tract through which blood flows from the heart to the lungs) and/or because of atrioventricular valve dysfunction (the valve that connects the functioning ventricle with an atrium). If these symptoms are severe, the Fontan Operation will be performed, but only if certain conditions are met:

· pulmonary artery pressure is acceptably low
· the pulmonary arteries are sufficiently well formed
· there is no pulmonary vascular obstructive disease (PVOD)
· the systemic ventricle is functioning adequately

These criteria will be evaluated through a variety of tests. A chest x-ray, echocardiogram, and MRI (Magnetic Resonance Imaging) will show left ventricular function and other aspects of anatomy and cardiovascular condition. An electrocardiogram (ECG) is used to check for the presence of arrhythmias (irregular heartbeats). In addition, a cardiac catheterization procedure will be used to take hemodynamic measurements (blood pressures and concentrations of oxygen and other gases) in the pulmonary arteries and to evaluate their structure.

The long term prognosis after the Fontan for single ventricle patients is better than for other treatments, and improvements of surgical technique continue to be made. Life-long medical monitoring is required.

Patients that had early forms of the Fontan repair are at risk for worsening heart failure, arrhythmias, and stroke. These patients should be followed frequently and evaluated for conversion to newer forms of the Fontan to limit further atrial dilation (enlargement).