Health Library

Tetralogy of Fallot

How is Tetralogy of Fallot Diagnosed?

When a newborn with significant cyanosis is first seen, they are often placed on supplemental oxygen. The increased oxygen improves the child's oxygen levels in cases of lung disease, but breathing extra oxygen will have little effect on the oxygen levels of a child with tetralogy of Fallot.

Failure to respond to oxygen is often the first clue to suspect a cyanotic cardiac defect. Infants with tetralogy of Fallot can have normal oxygen levels if the pulmonary stenosis is mild (referred to as "pink" tetralogy of Fallot). In these children, the first clue to suggest a cardiac defect is detection of a loud murmur when the infant is examined.

Once congenital heart disease is suspected, echocardiography can rapidly and accurately demonstrate the four related defects characteristic of tetralogy of Fallot.

Cardiac catheterization is occasionally required to evaluate the size and distribution of the pulmonary arteries. Catheterization can also demonstrate whether patients have pulmonary blood flow supplied by an abnormal blood vessel from the aorta (aortopulmonary collateral).

How is Tetralogy of Fallot Treated?

Once tetralogy of Fallot is diagnosed, the immediate management focuses on determining whether the child's oxygen levels are in a safe range.

If oxygen levels are critically low soon after birth, a prostaglandin infusion is usually initiated to keep the ductus arteriosus open, which will provide additional pulmonary blood flow and increase the child's oxygen level.

Infants who need a prostaglandin infusion to have adequate oxygen levels will usually require surgical intervention in the neonatal period. Infants with normal oxygen levels or only mild cyanosis are usually able to go home in the first week of life.

Complete repair is usually done electively when children are 4-6 months of age, as long as the oxygen levels remain adequate. Progressive or sudden decreases in oxygen saturation may prompt earlier corrective repair.

Surgical correction of the defect is always necessary. Occasionally, patients will require a surgical palliative procedure before the final correction.

Corrective repair of tetralogy of Fallot involves closure of the ventricular septal defect with a synthetic Dacron patch so that the blood can flow normally from the left ventricle to the aorta.

The narrowing of the pulmonary valve and right ventricular outflow tract is then augmented (enlarged) by a combination of cutting away (resecting) obstructive muscle tissue in the right ventricle and enlarging the outflow pathway with a patch.

In some babies, however, the coronary arteries will branch across the right ventricular outflow tract where the patch would normally be placed. In these babies, an incision in this area to place the patch would damage the coronary artery, so this cannot safely be done.

When this occurs, a hole is made in the front surface of the right ventricle (avoiding the coronary artery) and a conduit (tube) is sewn from the right ventricle to the bifurcation of the pulmonary arteries to provide unobstructed blood flow from the right ventricle to the lungs.

How is Tetralogy of Fallot Managed in Adults and Adolescents?

Most adult patients with tetralogy of Fallot have had surgery to repair it in childhood. In some patients, the pulmonary valve is able to be preserved and they have no ongoing problems. Unfortunately, the majority do have issues; the most important one is leakage (regurgitation) of the pulmonary valve. This can enlarge the right heart chambers and lead to limitations in physical activity as well as heart rhythm abnormalities and occasionally sudden cardiac death.

Most patients with repaired tetralogy should have regular (usually annual) evaluation by a congenital heart expert. Pulmonary regurgitation can be treated with a tissue valve replacement. In many cases, pulmonary valves can be replaced using valves inserted through catheters (such as a Melody valve) rather than through a surgical procedure. This is usually a low-risk procedure that can allow the heart to shrink again and improve the patient's quality of life and life expectancy. These artificial pulmonary valves usually last many years in adult patients, but require expert surveillance.

Learn more about the Adolescent and Adult Congenital Heart Disease Program.

What is the Prognosis for Children With Tetralogy of Fallot?

Survival of children with tetralogy of Fallot has improved dramatically. In the absence of additional risk factors, more than 95% of infants with tetralogy of Fallot successfully undergo surgery in the first year of life.

Surgical repair is more difficult when the pulmonary arteries are critically small or when the lung blood flow is supplied predominantly by aortopulmonary collaterals.

Most babies are fairly sick in the first few days after surgery, since the right ventricle is "stiff" from the previous hypertrophy (thickness) and because an incision is made into the muscle of the ventricle, making the muscle temporarily weaker.

This right ventricular dysfunction usually improves significantly in the days following surgery. Patients may also have rhythm problems after surgery.

An abnormally fast rhythm (called junctional tachycardia) may occur and may require treatment with medication or the use of a temporary pacemaker. This abnormal rhythm is usually temporary and the rhythm generally will return to normal as the right ventricle recovers.

Patients are also at risk for slow heart rates after surgery due to heart block. Heart block may be caused by injury to or inflammation of the conduction system in the heart. In many patients, the conduction improves and normal rhythm returns. Rarely, a permanent pacemaker may be necessary.

Since normal circulation is produced by the tetralogy of Fallot repair procedure, long-term cardiac function is usually excellent.

However, the repair usually leaves the child with a leaky (insufficient) pulmonary valve. In this situation, after the right ventricle pumps blood out to the pulmonary arteries, some of the blood will flow back into the right ventricle. This creates extra volume in the right ventricle forcing it to work harder and become dilated.

In a small percentage of children, this pulmonary insufficiency can lead to diminished function of the right ventricle. Symptoms of fatigue, especially with exercise, may develop. In these cases, replacement of the pulmonary valve is often recommended, typically in the teenage years or in young adulthood.

Patients who have had repair of tetralogy of Fallot can also redevelop a narrowing in the right ventricular outflow area or in the branch (left or right) pulmonary arteries, which will cause the right ventricle to pump at abnormally high pressures.

If these problems occur, additional surgical intervention to further widen the outflow tract or pulmonary arteries may be necessary. Narrowing of the pulmonary arteries can sometimes be treated without surgery, with balloon dilation of the vessels during cardiac catheterization.

Long-term follow up with a cardiologist to detect recurrent or new problems as early as possible is essential. Follow-up visits in the cardiology clinic usually consist of a physical examination, electrocardiogram and periodic echocardiography. In addition, these visits will also include occasional cardiac MRI scans, exercise stress tests and Holter evaluations as a child reaches the teenage and adult years.