Some congenital heart defects alter how blood flows through the heart. One example is tetralogy of Fallot, a rare defect that occurs in only four out of every 10,000 babies born. It is named after Etienne-Louis Arthur Fallot, who first described this condition in 1888.
Tetralogy of Fallot is characterized by four heart defects that cause insufficient blood to reach the lungs and oxygen-depleted blood to be sent to the body. This combination of anatomical defects results in cyanosis (blue skin, nails, toes and lips) and can eventually weaken the heart. The four abnormalities associated with tetralogy of Fallot are:
- Ventricular septal defect. This is a hole in the wall (septa) that separates the heart’s two lower chambers or ventricles. The opening permits deoxygenated blood from the right ventricle to mix with oxygen-rich blood from the left ventricle, lowering the oxygen in blood delivered to the body.
- Pulmonary stenosis. This is an abnormal narrowing of the heart valve that sits between the right ventricle and the pulmonary artery. In a heart that functions normally, oxygen-poor blood from the right ventricle travels through the pulmonary valve and pulmonary artery to the lungs, where it receives oxygen. With pulmonary stenosis, however, the valve is narrowed. This increases the heart’s workload and decreases the amount of blood that flows to the lungs.
- Right ventricular hypertrophy. Because of the heart’s increased workload, the muscle of the right ventricle starts to thicken. This can lead to heart failure.
- Overriding aorta. This defect occurs when the aorta is located over the ventricular septal defect, rather than its normal spot over the left ventricle. Poorly oxygenated blood is sent to the body rather than being routed into the pulmonary artery, where it would normally travel to the lungs to pick up oxygen.
While no specific cause has been found, this condition may result from a combination of genetic and environmental factors. Circumstances that increase the risk for tetralogy of Fallot in a baby include maternal age over 40 and exposure to rubella or other viruses during pregnancy. Diabetes, poor nutrition and excessive alcohol use during pregnancy are also linked to the condition.
Symptoms of Tetralogy of Fallot
Symptoms associated with tetralogy of Fallot typically occur by the time an infant is just a few weeks old, including:
- Cyanosis (skin that turns blue)
- Difficulty breathing and tiring during feeding
- Heart murmur (an unusual whooshing sound made by the heart)
Diagnosis of Tetralogy of Fallot
A diagnosis can be made by an echocardiogram, which is an ultrasound that shows the structural abnormalities associated with tetralogy of Fallot. Frequently, an EKG is also performed to evaluate the heart’s electrical activity, heart rate and rhythm.
Occasionally, patients with tetralogy of Fallot require more invasive techniques such as cardiac catheterization to help diagnose and plan for surgical repair. During a cardiac catheterization, a small diameter tube is inserted into the neck or groin and maneuvered through the heart and blood vessels under x-ray guidance. The tube is equipped to give important information about how the blood flows through the heart. It can also measure oxygen levels within the heart and blood vessels.
The structural defects associated with tetralogy of Fallot require surgical repair. The timing of surgery depends on the severity of the abnormalities as well as a baby’s general health, weight and stability.
If a baby is weak or has not gained sufficient weight, a temporary surgery can be effective in raising the blood oxygen level. This involves placing a shunt (a small tube) between two blood vessels that lead from the heart. This shunt allows more blood to flow to the lungs to receive oxygen.
Once a baby is healthy enough for the full surgery, doctors widen the narrowed pulmonary valve and pulmonary artery and close the ventricular septal defect with a patch during open-heart surgery. If a baby previously received a shunt, it is removed during the full repair.
Cardiac surgeons at Riley at IU Health employ the newest technologies and innovations in treating tetralogy of Fallot, offering better outcomes for more infants. Even after a successful open-heart surgery, all children born with tetralogy of Fallot require lifelong medical management.
Key Points to Remember
Key Points to Remember
- Tetralogy of Fallot is a combination of four heart defects that alter the flow of blood through the heart. Together, these defects limit the volume and flow of blood to the lungs, resulting in oxygen-deficient blood flowing through the body.
- Cyanosis, lethargy and breathing difficulties are often seen in patients with tetralogy of Fallot.
- This condition is treatable with open-heart surgery, however, the patient will require cardiac care throughout their life.
- Cardiac surgeons at Riley at IU Health employ the newest technologies and innovations in treating tetralogy of Fallot, offering better outcomes for more infants.
Support Services & Resources
Support Services & Resources
Visit these resources to find services and learn more about congenital heart defects.
Riley at IU Health offers a broad range of supportive services to make life better for families who choose us for their children's care.
The CDC is the nation’s health protection agency and provides information to help Americans understand and/or prevent diseases, including tetralogy of Fallot.
As part of the National Institutes of Health, the National Heart, Lung and Blood Institute advances research and understanding of heart, lung and blood diseases and shares easy-to-digest information about congenital heart defects such as tetralogy of Fallot.
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