Tetralogy of Fallot

Overview

Tetralogy of Fallot is a congenital heart defect made up of four problems that occur together: a hole between the lower chambers (ventricular septal defect), narrowing of the path from the heart to the lungs (pulmonary stenosis), a thickened right pumping chamber, and an aorta positioned over both lower chambers. Together these allow oxygen-poor blood to be pumped to the body.

Because less oxygen reaches the tissues, babies may have a bluish tint to the skin and lips, a condition called cyanosis. Tetralogy of Fallot is one of the more common cyanotic heart defects, and with modern surgery most children do well and reach adulthood.

Symptoms

Symptoms depend on how much blood flow to the lungs is reduced and often appear in early infancy.

• Bluish color of the skin, lips, or nails (cyanosis)
• Shortness of breath and rapid breathing, especially during feeding
• Poor weight gain and tiring easily
• A heart murmur
• Fussiness and fatigue

Tet spells: Some infants have sudden episodes of deep blue color, rapid breathing, and irritability, often when crying or feeding. A severe spell can cause limpness or fainting and is a medical emergency requiring immediate care. Parents are often taught to recognize these spells and to comfort and position the baby, such as bringing the knees toward the chest, while seeking help. Knowing the signs in advance can make a real difference during an episode.

Causes

Tetralogy of Fallot develops during fetal heart formation. In most cases the exact cause is unknown, but several factors are associated with a higher risk.

• Genetic factors: It can occur with certain genetic conditions, including Down syndrome and a chromosome 22q11 deletion.
• Conditions during pregnancy: Viral illness, poor nutrition, alcohol use, or certain exposures may contribute.
• Maternal factors: Diabetes and older maternal age are linked to higher risk.

The defect usually arises from a combination of factors rather than a single cause.

Risk Factors

• Genetic conditions such as Down syndrome or 22q11 deletion syndrome
• A family history of congenital heart defects
• Maternal viral illness during pregnancy, such as rubella
• Alcohol use or poor nutrition during pregnancy
• Maternal diabetes

Diagnosis

Tetralogy of Fallot is sometimes found before birth and otherwise soon after, when cyanosis or a murmur prompts testing.

• Echocardiogram: The key test, showing all four defects and blood flow.
• Pulse oximetry: Measures blood oxygen and may flag the problem in newborn screening.
• Electrocardiogram (ECG) and chest X-ray: Show heart rhythm and the characteristic heart shape.
• Prenatal ultrasound: Can detect the defect during pregnancy, allowing the family and care team to prepare.
• Oxygen saturation monitoring: Helps gauge how much blood flow to the lungs is reduced.

Treatment

Tetralogy of Fallot is treated with surgery, which most children undergo in the first year of life.

• Corrective open-heart surgery: Closes the hole between the ventricles and relieves the narrowing to the lungs, allowing oxygen-rich blood to flow normally.
• Temporary shunt: In some infants a smaller initial procedure improves blood flow to the lungs until full repair can be done.
• Managing tet spells: Comforting the baby and specific positioning can help during a spell while seeking emergency care.

After repair, lifelong follow-up with a heart specialist is important, as some people need further procedures over time. As children grow, the valve and vessel leading to the lungs may need attention, and some adults who had tetralogy of Fallot repaired in childhood eventually need a pulmonary valve replacement. Heart rhythm problems can also develop later in life and are watched for during follow-up. Despite these considerations, the outlook has improved dramatically with modern surgery, and most people who had the defect repaired in childhood live active, productive lives. Regular check-ups with a specialist in adult congenital heart disease help catch and manage any issues early.

When to See a Doctor

A child with known or suspected tetralogy of Fallot needs care from a pediatric heart team. Call emergency services or seek immediate care if a baby:

• Turns deeply blue or gray, especially during a spell
• Becomes limp, unresponsive, or faints
• Has severe difficulty breathing
• Is feeding very poorly or not gaining weight, which needs prompt evaluation

Related Topics

Frequently Asked Questions

References

1. Centers for Disease Control and Prevention (CDC). Tetralogy of Fallot.
2. Mayo Clinic. Tetralogy of Fallot.
3. MedlinePlus, U.S. National Library of Medicine. Tetralogy of Fallot.