Tetralogy of Fallot (TOF or "TET") is a complex condition of several congenital (present at birth) defects that occur due to abnormal development of the fetal heart during the first 8 weeks of pregnancy. These problems include the following:
"Tetralogy" refers to four heart problems. The fourth problem is that the right ventricle becomes enlarged as it tries to pump blood past the obstruction into the pulmonary artery.
Normally, oxygen-poor (blue) blood returns to the right atrium from the body, travels to the right ventricle, then is pumped through the pulmonary artery into the lungs where it receives oxygen. Oxygen-rich (red) blood returns to the left atrium from the lungs, passes into the left ventricle, and then is pumped through the aorta out to the body.
In tetralogy of Fallot, blood flow within the heart varies, and is largely dependent on the size of the ventricular septal defect, and how severe the obstruction in the right ventricle is.
According to the National Heart, Lung, and Blood Institute (NHLBI), tetralogy of Fallot affects about 5 of every 10,000 babies and occurs equally in boys and in girls.
Some congenital heart defects may have a genetic link, either occurring due to a defect in a gene, a chromosome abnormality, or environmental exposure, causing heart problems to occur more often in certain families.
Maternal abuse of alcohol during pregnancy, leading to fetal alcohol syndrome (FAS), is linked to tetralogy of Fallot. Mothers who take medications to control seizures and mothers with phenylketonuria (PKU) are also more likely to have a baby with tetralogy of Fallot.
Most of the time, this heart defect occurs sporadically (by chance), with no clear reason evident for its development.
The amount of oxygen-poor (blue) blood that passes through the VSD to the left side of the heart varies. If the right ventricle obstruction is severe, or if the pressure in the lungs is high, a large amount of oxygen-poor (blue) blood passes through the VSD, mixes with the oxygen-rich (red) blood in the left ventricle, and is pumped to the body. The more blood that goes through the VSD, the less blood that goes through the pulmonary artery to the lungs, and the less oxygen-rich (red) blood that returns to the right side of the heart. Soon, nearly all the blood in the left ventricle is oxygen-poor (blue). This is an emergency situation, as the body will not have enough oxygen to meet its needs.
Some situations, such as crying, increase the pressure in the lungs temporarily, and increasing blueness might be noted as a baby with tetralogy of Fallot cries. In other situations, the pathway from the right ventricle to the pulmonary artery becomes tighter, preventing much blood from passing that way, and allowing oxygen-poor (blue) blood to flow through the VSD into the left heart circulation. Both of these situations are nicknamed "TET spells." Sometimes, steps can be taken to lessen the pressure or the obstruction, and allow more blood to flow into the lungs and less through the VSD. These steps, however, are not always effective.
The following are the most common symptoms of tetralogy of Fallot. However, each child may experience symptoms differently. Symptoms may include:
Any of these can be symptoms of tetralogy of Fallot. The symptoms of tetralogy of Fallot may resemble other medical conditions or heart problems. Always consult your child's physician for a diagnosis.
Your child's physician may have heard a heart murmur during a physical examination, and referred your child to a pediatric cardiologist for a diagnosis. A heart murmur is simply a noise caused by the turbulence of blood flowing through the obstruction from the right ventricle to the pulmonary artery. Symptoms your child exhibits will also help with the diagnosis.
A pediatric cardiologist specializes in the diagnosis and medical management of congenital heart defects, as well as heart problems that may develop later in childhood. The cardiologist will perform a physical examination, listening to the heart and lungs, and make other observations that help in the diagnosis. The location within the chest that the murmur is heard best, as well as the loudness and quality of the murmur (harsh, blowing, etc.) will give the cardiologist an initial idea of which heart problem your child may have. Diagnostic testing for congenital heart disease varies by the child's age, clinical condition, and institutional preferences. Some tests that may be recommended include the following:
Specific treatment for tetralogy of Fallot will be determined by your child's physician based on:
Tetralogy of Fallot is treated by surgical repair of the defects. A team of cardiac surgeons performs the surgery, usually before an infant is 1 year old. In many cases, the repair is made at around 6 months of age, or even a little earlier. Repairing the heart defects will allow oxygen-poor (blue) blood to travel its normal route through the pulmonary artery to receive oxygen.
The operation is performed under general anesthesia, and involves the following:
Children will spend time in the intensive care unit (ICU) after tetralogy of Fallot repair. During the first several hours after surgery, your child will be very drowsy from the anesthesia that was used during the operation, and from medications given to relax him/her and to help with pain. As time goes by, your child will become more alert.
While your child is in the ICU, special equipment will be used to help him or her recover, and may include the following:
Your child may need other equipment not mentioned here to provide support while in the ICU, or afterwards. The hospital staff will explain all of the necessary equipment to you.
Your child will be kept as comfortable as possible with several different medications; some of which relieve pain, and some of which relieve anxiety. The staff will also be asking for your input as to how best to soothe and comfort your child.
After discharge from the ICU, your child will recuperate on another hospital unit for a few days before going home. You will learn how to care for your child at home before your child is discharged. Your child may need to take medications for a while at home, and these will be explained to you. The staff will give you instructions regarding medications, activity limitations, and follow-up appointments before your child is discharged.
Pain medications, such as acetaminophen or ibuprofen, may be recommended to keep your child comfortable at home. Your child's physician will discuss pain control before your child is discharged from the hospital.
After surgery, older children usually have a fair tolerance for activity. Your child may become tired easily, and sleep more right after surgery, but, within a few weeks, your child should be fully recovered.
Most children who have had a tetralogy of Fallot surgical repair will live healthy lives. Activity levels, appetite, and growth will eventually return to normal in most children. Your child's cardiologist may recommend that antibiotics be given to prevent bacterial endocarditis after discharge from the hospital.
After initial repair of tetralogy of Fallot, pulmonary valve replacement is often indicated in the second or third decade of life to prevent complications such as enlargement of the right ventricle, dysrhythmias, and heart failure. For women wishing to have children, pre-conception evaluation by echocardiogram and/or magnetic resonance imaging (MRI) is recommended.
Consult your child's physicians regarding the specific outlook for your child.
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