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What is Tetralogy of Fallot?

Tetralogy of Fallot is a congenital heart defect that involves a combination of four abnormalities in the heart that affects blood flow to the lungs. The flow of blood through the pulmonary valve of the heart is obstructed, so the oxygenated and deoxygenated blood from both ventricles of the heart mix together through a hole in the bottom chamber of the heart.

 

The Four Abnormalities in Tetralogy of Fallot


Pulmonary Valvar and Infundibular Stenosis

Where blood flows out of the right ventricle, there is narrowing, mostly caused by the overgrowth of the heart muscle wall. This narrowing varies from person to person with Tetralogy of Fallot—sometimes it’s minor and sometimes severe.

Ventricular septal defect

There is a hole between the two bottom chambers (ventricles) of the heart. This is usually a single, large hole.


Overriding aorta

The aorta straddles over the ventricular septum. This is called “override.” The amount of override varies—anywhere from 5% to 95% of the aortic valve could be connected to the right ventricle.


Right ventricular hypertrophy

The right ventricle is more muscular than normal, because the right ventricular wall increases in size to deal with the obstructed blood flow. If a child is born with Tetralogy of Fallot, he or she may have bluish skin because of decreased oxygen in the blood. There may be other symptoms such as difficulty in feeding, cyanotic (Tet) spells, and a failure to gain weight or develop at a normal rate. Tetralogy of Fallot can be associated with other conditions such as Down Syndrome or DiGeorge Syndrome. A severe variant of Tetralogy of Fallot is with pulmonary atresia—this means there is a complete obstruction (atresia) of flow out of the right ventricle. Blood shifts completely from the right ventricle to the left, and then the left ventricle pumps it through the aorta.

How is Tetralogy of Fallot diagnosed during pregnancy?

If your physician suspects a heart defect, a fetal cardiologist will perform a fetal echocardiogram to view the heart and its anatomy. With this imaging the Fetal Heart Program team can see the severity of the heart defect, and put together a plan for the best course of action.

How is Tetralogy of Fallot managed during pregnancy?

After diagnosing Tetralogy of Fallot during your pregnancy, our team monitors your baby closely during pregnancy and helps prepare for delivery. Some babies with Tetralogy of Fallot may need surgery in the neonatal period, but many others may not require surgery until four to six months of age. How does Tetralogy of Fallot impact delivery? Most babies with Tetralogy of Fallot can be delivered by whatever route the mother desires, usually vaginally. It is best for these babies to be delivered at a medical center where there is immediate access to a team of pediatric cardiologists and neonatologists, along with an established NICU (Neonatal Intensive Care Unit).

What are the treatments and surgeries for Tetralogy of Fallot?

The type of treatments and surgery necessary depends on the severity of the heart defect. Those with Tetralogy of Fallot may also require additional surgery later in life, but overall have very good outcomes. Shunting: For patients with more severe variants of Tetralogy of Fallot, the surgeon can create a shunt from a systemic artery to the pulmonary artery that directs more blood flow to the lungs. This relieves symptoms of severe cyanosis. Total surgical repair: The surgeon performs a resection of the muscle in the right ventricular outflow tract, opens up the pulmonary valve and closes the ventricular septal defect. This open-heart surgery is often performed around four to six months of age.

What happens after surgery?

Many children who have had surgery to treat Tetralogy of Fallot recover and grow normally. Depending on how severe the heart defect is, your child may need additional surgeries, medications, or other treatments later in life. What is the long-term prognosis for children with Tetralogy of Fallot? The long-term prognosis after surgery for Tetralogy of Fallot is very good in most cases. After total surgical repair, most patients have good or even excellent cardiac function and can exercise normally. In fact, Olympic snowboarder Shaun White and Australian cricketer Beau Casson are two examples of children born with Tetralogy of Fallot who are now world-class athletes!