Tetralogy of Fallot

Tetralogy of Fallot refers to a rare combination of malformations in the heart. These congenital heart defects result from abnormalities in the heart's structures that occur during fetal development. Tetralogy of Fallot results in reduced capacity of the heart to pump oxygenated blood to the body.

Tetralogy of Fallot: Congenital Defects

Tetralogy of Fallot involves four specific congenital defects in the heart:

• Overriding aorta (aorta placed directly above the ventricular septal defect, rather than over the left ventricle)
• Pulmonary stenosis (a narrowing of the valve between the right ventricle and the pulmonary artery, which carries blood to the lungs)
• Right ventricular hypertrophy (thickening of heart muscle)
• Ventricular septal defect (a hole in the wall between the left and right ventricles).

Effects of Tetralogy of Fallot

The specific heart defect combination in tetralogy of Fallot patients results in inadequate blood oxygenation and the pumping of deoxygenated blood to the body.

Pulmonary stenosis prevents sufficient blood from reaching the lungs, causing inadequate blood oxygenation. The ventricular septal heart defect allows oxygenated blood from the left ventricle to mix with deoxygenated blood from the right ventricle. Placement of the aorta above this heart defect causes the heart to pump both oxygenated and deoxygenated blood to the body (as the deoxygenated blood is not contained within the right ventricle).

Cyanosis, or a bluish tint to the skin and lips, indicative of inadequate blood oxygenation, can be evident in individuals with tetralogy of Fallot. Other symptoms of these congenital defects may include:

• Failure to thrive
• Fatigue
• Heart murmur
• Shortness of breath
• "Tet spells," or rapid loss of oxygen saturation in the blood.

Tetralogy of Fallot Treatment

Tetralogy of Fallot must be repaired with open-heart surgery; the structural congenital defects are too significant to be repaired through a less-invasive procedure such as cardiac catheterization.

An early, temporary surgery may be performed in some cases, which involves inserting a shunt to increase blood flow to the lungs. However, all children with tetralogy of Fallot must eventually undergo intracardiac repair. This process repairs the ventricular septal defect and widens the pulmonary valve and artery to increase blood flow to the lungs.

This procedure increases the amount of oxygenated blood that can be pumped to the body. The repair is typically performed in early infancy, and timing depends on the severity of the pulmonary stenosis heart defect.

Tetralogy of Fallot Complications

If these congenital heart defects are properly detected and repaired early on, children may lead relatively normal lives. However, complications are possible, and can include the following:

• Arrhythmia: Arrhythmia, or an irregular heartbeat, may develop after surgery.
• Chronic Pulmonary Regurgitation: Children can also experience chronic pulmonary regurgitation, or leakage through the pulmonary valve.
• Need for additional surgery: Some children may eventually need another surgery, which can include placement of an artificial valve.

No matter what the outcome of the surgery, affected children need close medical monitoring by a cardiologist, and may have to restrict levels of physical activity.

Resources

American Heart Association. (n.d.). Tetralogy of fallot. Retrieved April 11, 2010, from: http://www.americanheart.org/presenter.jhtml?identifier=11071.

Mayo Clinic. (n.d.). Tetralogy of fallot. Retrieved April 11, 2010, from: http://www.mayoclinic.com/health/tetralogy-of-fallot/DS00615.

National Heart Lung and Blood Institute. (2009). Tetralogy of fallot. Retrieved April 11, 2010, http://www.nhlbi.nih.gov/health/dci/Diseases/tof/tof_what.html.