Tetralogy of Fallot
What is Tetralogy of Fallot?
Tetralogy of Fallot is the most common cyanotic heart defect, representing 15% of all congenital heart disease. "Cyanosis" refers to the blue tinge that the lips and fingers develop when the blood circulating in the body is not fully filled with oxygen.
The normal heart has four chambers, two upper chambers called atria, and two lower chambers called ventricles. The job of each chamber is different, but, in general, the atria receive blood into the heart, and the ventricles pump blood out of the heart. The flow of blood out of each chamber is controlled by a valve, which keeps blood flowing in one direction. The left and right sides of the heart are separated by a muscle called a septum.
In Tetralogy of Fallot, there are four components which are abnormal: (1) A ventricular septal defect (VSD) is a hole between the two ventricles; (2) Pulmonary artery stenosis is a narrowing of the artery which goes from the heart to the lungs, making it difficult to get blood into the lungs for oxygenation. Some of the blood in the right ventricle will avoid this tight spot by going across the VSD to the left side. The blood in the right ventricle is unoxygenated (blue); thus some blue blood crosses over to the left ventricle, mixes with normal oxygenated blood, and then gets pumped out to the body; (3) The outflow from the left side of the heart appears large; this is called an over-riding aorta; (4) The right side of the heart pumps extra-hard against a constricted pulmonary artery, and develops right ventricular hypertrophy.
What will happen during pregnancy?
Tetralogy of Fallot is a very rare birth defect, representing 0.04% of all live births. 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.
Surgical Treatment
Some children with Tetralogy of Fallot, have very little blood flow going to the lungs after birth. These children will require a procedure called a Blalock-Taussig shunt prior to leaving the hospital. This shunt allows additional blood flow to go the lungs. This is a temporizing procedure, and the child will need to return to the hospital at 4-9 months of age to have a full repair.
A full repair for Tetralogy of Fallot consists of placing a patch over the ventricular septal defect to close the hole; cutting away the narrowed area under the pulmonary valve; and possible patching of the pulmonary artery to make it larger. This repair usually happens between 4-6 months of age.
The Center team will help care for you and your infant with Tetralogy of Fallot. The Center will develop a comprehensive plan with all of the physicians and specialists involved in the care of you and your newborn before, during, and after delivery.
To learn more about Tetralogy of Fallot, please visit the Children's Heart Institute at Children's Memorial Hermann Hospital.
Note: This information regarding your condition is meant to be a helpful, informative introduction. Because every newborn is different, this may not be applicable to all cases, especially if there are additional defects. Your team of experts at the Center will provide you with information specific to your pregnancy.