The Fontan procedure is a surgical procedure that is done for people with only one functional ventricle in the heart. This occurs as part of complex defects in the heart from birth (congenital heart disease) that renders one side of the heart ineffective to carry out its normal function.

The normal human circulation has two ventricles – the left ventricle that pumps oxygenated blood to all organs of the body, and the right ventricle that collects the deoxygenated blood and pumps it to the lungs.

The Fontan procedure lets the deoxygenated blood from the lower part of the body go directly to the blood vessels that carry blood to the lungs (pulmonary arteries) without entering the heart. This operation usually follows another surgery (bidirectional Glenn shunt, abbreviated BDG) which directs the deoxygenated blood from the upper part of the body to the pulmonary arteries without entering the heart.

Following the Fontan procedure (also called total cavopulmonary connection, abbreviated TCPC), the entire venous blood carrying deoxygenated blood from all the other body organs directly pass to the lung bed for oxygenation. This means that the only blood that enters the cardiac chambers is the oxygenated blood that return from the lungs through the pulmonary veins. This ensures the supply of normally oxygenated blood to all parts of the body.

Children between 3 to 15 years (usually 4 to 7 years) who are born with a single ventricle type of heart disease may need a Fontan procedure. The Fontan procedure is the last of a series of procedures done for candidates who are found to be suitable for the same. Before the Fontan procedure, the child would usually have undergone a bidirectional Glenn shunt surgery that directs the oxygen-poor venous blood from the upper body to the lungs. Several patients may have undergone other procedures as the first stage of a three-staged palliation that culminates with the Fontan procedure. The first stage procedure in these situations may include Blalock-Taussig-Thomas (BTT) shunt, patent ductus arteriosus stenting, pulmonary artery banding, or the Norwood procedure.

Some of the heart defects that often require palliation along the Fontan pathway include:

1. Tricuspid atresia
2. Hypoplastic right heart syndrome
3. Pulmonary atresia with intact ventricular septum
4. Hypoplastic left heart syndrome
5. Single ventricle
6. Unbalanced atrioventricular septal defects

Complex univentricular congenital heart diseases account for nearly two-thirds of critical congenital heart diseases in the newborn period with a reported incidence of 0.25 per 1000 live births. Every year, SCTIMST performs between 60 – 75 Fontan procedures and 80 – 100 bidirectional Glenn shunt procedures.

Children who have undergone bidirectional Glenn shunt are followed up in the Cardiology and cardiac surgery departments and evaluated for candidacy of Fontan procedure at every follow up. These children are evaluated by clinical examination and investigations including chest radiograph, electrocardiogram, echocardiogram. Other tests including cardiac catheterization and computed tomography are also considered during preoperative evaluation of suitability for the Fontan procedure. Cardiac magnetic resonance imaging may rarely be required.

The children who are scheduled for a Fontan procedure will be followed up in the Fontan clinic. The caregivers will be educated regarding the Fontan procedure and comprehensive rehabilitative measures. Preoperative patient optimization is be done by a multidisciplinary holistic approach guided by the institutional protocol.

The Fontan procedure is a surgery done in the operating theatre. The cardiac anesthesia team ensures that the procedure is done safely under deep sleep without pain. The surgeons do the operation by connecting the child’s circulation to a bypass machine that does the work of the heart and the lungs while complete the surgery. A Fontan procedure may take between four to five hours before the child is shifted to the postoperative cardiac intensive care.

After Fontan procedure, the child is managed in the postoperative intensive care. After gradual de-escalation, the child is shifted to the step-down intensive care and thereafter to the ward. Specific attention is given to pulmonary rehabilitation and early ambulation. The child is discharged on blood thinning medication called an oral anticoagulant (Warfarin or acenocoumarol) with counselling on periodic monitoring and monitoring a blood test called prothrombin time international normalized ratio (PT-INR).

1. The Fontan procedure improves the level of oxygen in the child’s blood. This improves the oxygen delivery to all organs and improves effort tolerance.
2. The Fontan procedure reduces the workload of the solitary ventricle.
3. It reduces the amount of mixing of oxygenated and de-oxygenated blood in the body.
4. It permits survival of children with complex congenital heart diseases to survive into adulthood. The 10-year survival for Fontan procedure is over 90%.

Some of the early complications of a Fontan procedure include:

1. Pleural effusions
2. Heart failure
3. Abnormal heart rhythm
4. Kidney dysfunction

Some of the late complications of a Fontan procedure include:

1. Digestion relation abnormalities that may result in loss of proteins from the gut.
2. Liver dysfunction
3. Clot formation in the Fontan circulation
4. Heart failure
5. Fluid leak in the airways

The Fontan procedure inherently lacks a pump in the venous circulation and functions at relatively higher pressure in the veins. Over a long period of time, cardiac output can be low after a Fontan procedure. When the body is no longer able to adjust to the altered circulation, the circulation is then deemed a failed Fontan. These patients may then need a heart transplant.