Tetralogy of Fallot
Tetralogy of Fallot is a type of congenital heart defect. Congenital means that it is present at birth.
Tet; TOF; Congenital heart defect - tetralogy; Cyanotic heart disease - tetralogy; Birth defect - tetralogy
Tetralogy of Fallot causes low oxygen levels in the blood. This leads to cyanosis (a bluish-purple color to the skin).
The classic form includes four defects of the heart and its major blood vessels:
- Ventricular septal defect (hole between the right and left ventricles)
- Narrowing of the pulmonary outflow tract (the valve and artery that connect the heart with the lungs)
- Overriding aorta (the artery that carries oxygen-rich blood to the body) that is shifted over the right ventricle and ventricular septal defect, instead of coming out only from the left ventricle
- Thickened wall of the right ventricle (right ventricular hypertrophy)
Tetralogy of Fallot is rare, but it is the most common form of cyanotic congenital heart disease. It occurs equally as often in males and females. People with tetralogy of Fallot are more likely to also have other congenital defects.
The cause of most congenital heart defects is unknown. Many factors seem to be involved.
Factors that increase the risk for this condition during pregnancy include:
- Alcoholism in the mother
- Mother who is over 40 years old
- Poor nutrition during pregnancy
- Rubella or other viral illnesses during pregnancy
Children with tetralogy of Fallot are more likely to have chromosome disorders, such as Down syndrome, Alagille syndrome, and DiGeorge syndrome (a condition that causes heart defects, low calcium levels, and poor immune function).
- Blue color to the skin (cyanosis),which gets worse when the baby is upset
- Clubbing of fingers (skin or bone enlargement around the fingernails)
- Difficulty feeding (poor feeding habits)
- Failure to gain weight
- Passing out
- Poor development
- Squatting during episodes of cyanosis
Exams and Tests
A physical exam with a stethoscope almost always reveals a heart murmur.
Tests may include:
- Chest x-ray
- Complete blood count (CBC)
- Electrocardiogram (EKG)
- MRI of the heart (generally after surgery)
Surgery to repair tetralogy of Fallot is done when the infant is very young, typically before 6 months of age. Sometimes, more than one surgery is needed. When more than one surgery is used, the first surgery is done to help increase blood flow to the lungs.
Surgery to correct the problem may be done at a later time. Often only one corrective surgery is performed in the first few months of life. Corrective surgery is done to widen part of the narrowed pulmonary tract and close the ventricular septal defect with a patch.
Most cases can be corrected with surgery. Babies who have surgery usually do well. More than 90% survive to adulthood and live active, healthy, and productive lives. Without surgery, death often occurs by the time the person reaches age 20.
People who have continued, severe leakiness of the pulmonary valve may need to have the valve replaced.
Regular follow-up with a cardiologist is strongly recommended.
Complications may include:
- Delayed growth and development
- Irregular heart rhythms (arrhythmias)
- Seizures during periods when there is not enough oxygen
- Death from cardiac arrest, even after surgical repair
When to Contact a Medical Professional
Call your health care provider if new unexplained symptoms develop or the child is having an episode of cyanosis (blue skin).
If a child with tetralogy of Fallot becomes blue, immediately place the child on their side or back and put the knees up to the chest. Calm the child and seek medical attention right away.
There is no known prevention.
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Kliegman RM, Stanton BF, St. Geme JW, Schor NF. Cyanotic congenital heart lesions: lesions associated with decreased pulmonary blood flow. In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 430.
Webb GD, Smallhorn JF, Therrien J, Redington AN. Congenital heart disease. In: Mann DL, Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 10th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 62.
Reviewed By: Steven Kang, MD, Director, Cardiac Electrophysiology, Alta Bates Summit Medical Center, Stanford Healthcare, Oakland, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.