The Fontan is an open-heart surgery used to treat a variety of cardiac defects that are present at birth (congenital heart defects). It is commonly used on children who have been born with either no separation between the right and left ventricles of the heart (a ventricular septal defect), with only one functional ventricle or the lack of development of one or more heart valves. The common factor is that the patient has only one functioning ventricle or, because of the nature of the defect, the patient is best served by being left with only one functioning ventricle.

During this operation, surgeons create a passageway that allows blood to bypass the right ventricle, which is usually responsible for pumping oxygen–poor blood to the lungs for fresh oxygen. By routing blood around the right ventricle, surgeons are able to adapt the right ventricle to pump oxygen-rich blood to the body if the left ventricle is unable to. In other cases in which the left ventricle is healthy, but the right ventricle is too small to pump blood or is totally missing, the Fontan procedure may be performed simply to bypass circulation around the under-performing right ventricle.

There are two stages to the Fontan, which are usually performed at two different times in a young patient’s life to allow the body to adjust to the new blood flow. Each stage requires between several days and about three weeks of recovery time in the hospital.

Although the Fontan is often lifesaving, it also carries a number of risks. Family members are encouraged to discuss all the risks and benefits of the procedure with their pediatric cardiologist.