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Tetralogy of Fallot

Tetralogy of Fallot: Prenatal Diagnosis and Management During Pregnancy

What is Tetralogy of Fallot?

Tetralogy of Fallot is a common heart defect and the most common cyanotic heart defect. Cyanosis refers to the bluish tint of the lips and fingers when the blood which circulates in the body is not fully saturated with oxygen. Fully oxygenated blood is bright red; blood which is not is dark blue-purple.

There are two main pumping chambers (ventricles) in the heart. The right ventricle receives unoxygenated blood from the body and pumps it to the lungs. The left ventricle receives oxygenated blood from the lungs and pumps it to the body. Separating these two chambers is a wall (septum). Ordinarily, there is no mixing of the blood between the two ventricles.

In tetralogy of Fallot, there is a ventricular septal defect (VSD), a hole between the two ventricles. There is also obstruction at the outlet of the right heart as it sends blood to the lungs. It can be difficult for the blood to get through this area. Since blood tends to follow the path of least resistance, some of the blood in the right ventricle will avoid this tight area by going across the VSD to the left ventricle. The blood in the right ventricle is unoxygenated (blue) - some blue blood crosses over to the left ventricle and gets pumped out to the body. This is why children with tetralogy of Fallot are often blue.

Children with tetralogy of Fallot may be more or less blue depending on the amount of obstruction at the outlet of the right ventricle. If that artery is mildly narrow, a near-normal amount of blood may go the lungs to get oxygenated. In this situation, the child's oxygen levels may be normal. These children tend to grow well and be active. Symptoms are minimal or absent. If the obstruction is severe, children may be quite blue. They may also have problems with feeding and growing. Some children will have episodes where they get much bluer than usual ("tet spells"). Children who have spells usually undergo corrective surgery soon after the onset of the spells.

What will happen during pregnancy?

Prenatal diagnosis is usually based on an ultrasound that examines the fetal heart. Once the condition is suspected, a targeted ultrasound is performed to rule out the presence of associated anomalies. A specialized ultrasound of the fetal heart, called an echocardiogram, will be performed, and an amniocentesis to look for genetic abnormalities may be recommended. Although the ultrasound may be suggestive that there is an abnormality, the diagnosis will be confirmed after birth.

Your pregnancy will be closely monitored. The Center coordinator will keep you in contact with all of the appropriate physicians and specialists as well as coordinating the care for you and your baby after delivery.

Will a fetal treatment be required?

Currently, there are no fetal treatments for Tetralogy of Fallot. You should continue to be closely followed by your obstetrician and pediatric cardiologist.

What special considerations should be made for delivery?

Type of delivery - Typically, a cesarean delivery is not necessary unless there are other factors determined by your obstetrician. A delivery plan will be carefully developed by your team at the Center and will be discussed with you and your obstetrician.

Place of delivery - The baby should be delivered at a hospital that is well prepared to handle babies with congenital heart defects. There should be a neonatal intensive care unit with the capability to provide specialized care and pediatric cardiovascular surgery services.

Time of delivery - There is usually no reason to intentionally induce early delivery.

What will happen at birth?

Immediately following delivery, doctors will carefully evaluate your baby. In most cases, there is no immediate danger to the infant. Parents and family should be able to see and hold the newborn prior to transfer to the neonatal intensive care unit. The baby will be stabilized in a neonatal intensive care unit and your pediatric cardiologist and neonatologist will evaluate the baby. The newborn may need help with breathing and blood pressure.

Most children with Tetralogy of Fallot do not require a surgery prior to discharge from the nursery; however, a small number of children will require a surgery prior to leaving the hospital.

Treatment

Unless there is an unusual complicating factor, all children with tetralogy of Fallot should undergo correction, even those with mild symptoms. Surgery involves closure of the ventricular septal defect with a patch along with relief of the obstruction of blood flow to the lungs. The technique used to open the artery will vary with the size of the patient and the severity of the narrowing. Surgery is done using a vertical incision on the chest. It is necessary to place patients on the heart-lung machine during surgery.

Most children stay in the hospital 4-12 days after repair of tetralogy of Fallot. Children often leave the hospital on some medications, but these can sometimes be discontinued within a couple of months after surgery.

Most children do very well for many years after surgery for tetralogy of Fallot. However, the surgery cannot be considered a true "cure." In normal hearts, there are usually two valves on the right side of the heart, to keep blood going in the correct direction. Most children only have one valve on the right side after surgery for tetralogy of Fallot. Usually, this does not cause any problems. In some, however, the right side of the heart may become overburdened and may need another operation years after the original repair. This happens to a small percent of patients, but it is enough reason to make sure that all children who have tetralogy of Fallot are followed regularly by a cardiologist.

Contact Us

Pediatric Cardiology Clinic
University of Texas Health Science Center Professional Building
6410 Fannin, Suite 500
Houston, TX 77030

Phone: (832) 325-6516

Pediatric Cardiovascular Surgery Clinic
University of Texas Health Science Center Professional Building
6410 Fannin, Suite 950
Houston, TX 77030

Phone: (713) 500-7339

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Note: This page is meant to be a helpful, informative introduction on the subject of tetralogy of Fallot. The information may not be applicable to all cases, especially if there are additional defects. It is not meant to replace the opinion of a personal physician.