Understanding Tetralogy of Fallot

Congenital Heart Disease is the most common severe abnormality occurring in the fetus. The incidence of CHD is about 50 per 1,000 live births. The majority of fetuses with CHD have no known risk factors. Diagnosing these problems during pregnancy allows physicians and nurses to provide more education, counseling and support to the expectant mother and improves outcomes.

Recently, the public became familiar with a congenital heart defect called Tetralogy of Fallot after talk show host Jimmy Kimmel’s son was diagnosed with the condition. As a result of the publicity surrounding this, many of the mothers coming to King’s Daughters want to know more about the condition and, of course, whether their baby is at risk.

TOF occurs rarely – about one of every 2,000 babies born have the condition. Symptoms include episodes of bluish color to the skin. Affected babies may have difficulty breathing, become limp, and occasionally lose consciousness. A heart murmur may be heard on physical exam.

The cause of TOF is unknown. Risk factors include diabetes, being over age 40, contracting rubella during pregnancy, and alcohol use. With TOF, there are four defects that may occur within the heart:

1. A ventricular septal defect. Basically, a hole in the tissue separating the left and right ventricles
2. Pulmonary stenosis, in which the exit from the right ventricle is narrowed.
3. Right ventricular hypertrophy, or enlargement of the right ventricle.
4. An overriding aorta, which allows blood from both ventricles to enter the aorta.

TOF is typically treated by open heart surgery in the first year of life. Timing of the surgery depends on the baby’s symptoms and size.

This condition and most congenital abnormalities can be found by prenatal ultrasound scans. Keep in mind, though that the fetal heart is about the size of a nickel and thus, the structures of the heart are quite small.

King’s Daughters Maternal Fetal Medicine department specializes in fetal echocardiography and Level II ultrasounds. Our two registered Fetal Echo Sonographers, Debbie Arnett and Dee Howard work closely with University of Louisville Pediatric Cardiologists and University of Kentucky Maternal Fetal Medicine specialists to provide care for CHD patients.

Fetal echocardiography can be ordered by the healthcare provider. For more information, contact the fetal echocardiographers at (606) 408-9798.