Fontan’s operation is a palliative surgical procedure used to treat congenital heart defects known as single ventricle anomalies. This term is used to describe a group of cardiac defects that differ from each other, but share the common feature that only one of the two ventricles is of adequate size to function normally. Some of the anomalies include tricuspid atresia, hypoplastic right heart syndrome, and double inlet left ventricle. All of these defects will generally undergo staged reconstructive procedures ultimately resulting in a “Fontan circulation.”

In the normal heart, each ventricle (lower chamber of the heart) does a separate job. The right ventricle pumps blood to the lungs, and the left ventricle pumps blood to the body. In a single ventricle heart, there is only one ventricle large enough to do the normal job of pumping the blood. This requires assigning the single ventricle to do the harder work of the heart which is to pump blood to the body. The job of getting blood to the lungs must be done without a pump. Different procedures may be necessary to achieve this goal depending on each patient and their needs.

The type of operation needed is quite varied depending on the cardiac defect. Generally, it takes three stages to achieve Fontan circulation. The first stage, usually performed in the first weeks of life, involves regulating the amount of blood flow to the lungs. If blood flow to the lungs is excessive, then a band can be placed around the pulmonary artery (the main lung vessel) to control the flow and protect the lungs from high pressure. This procedure is called pulmonary artery (PA) banding. If there is an inadequate supply of blood to the lungs, then a Blalock-Taussig shunt procedure would take place. This involves using a patient’s blood vessel or a shunt made from synthetic material and connecting it between the subclavian (a branch of the aorta) and the pulmonary artery.

The next stage is performed around 4-12 months of age. During the Glenn operation (hemi-Fontan), the superior vena cava (vessel that drains blood from the head and upper body back to the heart) is removed from the heart and sewn to the pulmonary artery. The shunt and band placed in a previous procedure may be removed at this time.

The third and final stage is the Fontan completion operation. This procedure is usually done around 2-3 years of age. During the operation, the inferior vena cava (vessel that returns blood to the heart from the lower part of the body) is connected to the pulmonary artery. Until now, this blood has bypassed the lungs and has been pumped to the body resulting in oxygen levels lower than normal. The two most common methods of the Fontan operation are the lateral tunnel and extra-cardiac technique. In the lateral tunnel method, a tunnel-like patch is placed inside the right atrium. It is then attached to the pulmonary artery directing the blood returning from the inferior vena cava. In the extra-cardiac method, the inferior vena cava is connected to a synthetic tube and is sewn to the pulmonary artery, routing the blood flow outside the heart.