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Wednesday, Dec 03, 2008 | 01:49 PM
Madisons Foundation - Moms And Dads In Search Of Needed Support
Tetralogy of Fallot (TOF)
Monday, 18 August 2003
Last Updated Thursday, 05 February 2004
What
Tetralogy of Fallot (TOF) is the leading cause of cyanosis, a blue coloration of the skin, in children due to a complex heart defect that evolves while the baby is being formed before birth. There are four main heart defects present in TOF, forming a "tetralogy": 1. Ventricular septal defect (VSD)- is a hole in the wall between the lower chambers (the ventricles), which lets oxygen-poor blood mix with oxygen-rich blood. As a result, blood pumped to the entire body contains less oxygen. 2. Pulmonary stenosis (PS)- is a narrowed opening of the pulmonary artery from the lower right ventricle limits the amount of blood flow to the lungs. An abnormal pulmonary valve is also usually present and these obstructions determine the severity of the cyanosis in the child. 3.Overriding aorta- is the major artery from the heart that straddles the septum (wall) and sits in between the two lower chambers (the ventricles). This lets oxygen-poor blood flow into the body. 4. Right ventricular hypertrophy (RVH)- hypertrophy simply means overgrowth. In this case it refers to a thickened and enlarged heart muscle in the lower-right chamber (the right ventricle) which leads to poor function. Together, these defects make the level of oxygen in the blood too low and the heart function too inefficient. When oxygen-poor blood is pumped into the body, the skin and the fingers, toes, and lips may appear blue. This condition is called cyanosis and the degree of cyanosis depends on how narrow the pulmonary artery has become. Please also see the diagrams presented by the websites listed at the end of this article.Who
TOF is usually diagnosed during the newborn period. In milder cases, children do not present with cyanosis and their symptoms may be perceived as the result of a ventricular septal defect. TOF represents approximately 6% of cases of congenital heart disease.Signs and Symptoms
Symptoms of TOF include the following-
- cyanosis- a hallmark of TOF, develops within the first few years of life due to the decrease in oxygen to the extremities (fingers, toes, lips etc). Please note that normal children may also have cyanosis in these areas. However, children with TOF have a more extensive cyanosis which includes the chest and face.
- Cyanotic or "blue spells" (tet spells)- Some newborns with TOF, usually between the ages of 2 to 4 months, have sudden episodes of cyanosis called "blue spells" or "tet spells". These spells occur when the amount of blood going to the lungs decreases and the blood is less oxygenated, and is more likely to occur with crying, exertion (ie, straining) and after waking up. These spells may last minutes to hours, resolving spontaneously or leading to fainting, seizures or loss of consciousness. Placing the child in the squatting, knee to chest position can help to stop the tet spell by increasing oxygenation to the body.
- Older Children with TOF may experience dyspnea (difficulty breathing) on exertion, decreasing their ability to exercise, have difficulty eating, have growth retardation and club-shaped fingernails, all from poor oxygenation to the body tissues. Squatting with shortness of breath is uniquely characteristic of the child with TOF who runs or exercises beyond capacity.
Possible Causes
The exact cause of TOF is unknown, however, alcohol or thalidomide use during pregnancy has been associated with this anomaly. Both parents and physicians should keep in mind that nearly 16% of children with TOF may have other associated symptoms such as abnormalities of penis (hypospadius), kidney, musculosketeletal system, and cleft lip and palate. These are only a few examples of the areas that need to be assessed with an associated TOF in mind.Diagnosis
The first clue leading to diagnosis of TOF is the presence of a heart murmur related to a VSD and/or the presence of cyanosis in the child's torso. There are a variety of imaging studies that can be done with your child to assess the cardiac defects such as a chest X-ray, however, the most definitive diagnosis is through an echocardiogram which shows the beating heart and its structures. Cardiac catheterization may also be necessary for further assessment (measures oxygenation in the various chambers of the heart) and preparation for repair. In children with TOF, lab tests will also reveal decreased oxygen saturation, and an increased hematocrit (RBC volume/blood volume) over 60% indicating polycythemia (increase in red blood cells) which increases the risk of a clot (thrombosis) formation.Treatment
Treatments include the following- 1. Tet spell: If your baby becomes blue, you should comfort your baby by picking him or her up and pulling the knees up to the chest. This will help blood get to the lungs more easily. If your baby does not regain color quickly after comfort and pulling the knees up, you should go to the closest emergency room. 2.Temporary surgical correction (Blalock-Taussig procedure) - increases pulmonary blood flow by placing a shunt (connection) between the subclavian artery to the pulmonary artery so that deoxygenated blood from the body can travel directly to lungs, bypassing the obstructed area. 3.Corrective surgery- to close the Ventricular Septal defect and open up the narrowed right ventricle outflow at the pulmonary artery area will thus allow increased oxygenation of the blood to the tissues. Because this is a much more invasive, delicate procedure, doctors usually wait till the infant's heart has grown larger before attempting this surgery. Antibiotics are needed to prevent infections to the heart before any dental work is performed.Prognosis
Children with TOF in general have a very good prognosis after the fully corrective surgery is done, and they often grow up to lead active fruitful lives. Surgical success in relieving the obstructed blood flow from the right ventricle will thus determine correction of the cyanotic condition and the ability to exert the body without undue fatigue.Connect with other parents
In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.Weblinks
American Heart Association
A great summary of TOF and diagrams of surgical repair, ongoing medical care for TOF and possible complications of the surgeries.
Texas Heart Institute
A nice summary of the TOF with links to other informative sites.
Simple diagrams of TOF and consequences of blood flow