Health Encyclopedia

Tetralogy of Fallot

Definition

Tetralogy of Fallot refers to a group of four types of heart defects present at birth (congenital).

Alternative Names

TET; TOF

Causes, incidence, and risk factors

Tetralogy of Fallot is classified as a cyanotic heart defect because the condition causes low oxygen levels in the blood, which leads to cyanosis (a bluish-purple coloration to the skin).

The classic form of Tetralogy includes 4 defects within the heart structures:

Ventricular septal defect (hole between the right and left ventricles)
Narrowing of the pulmonary outflow tract (tube that connects the heart with the lungs)
An aorta (tube that carries oxygenated blood to the body) that grows from both ventricles, rather than exclusively from the left ventricle
A thickened muscular wall of the right ventricle (right ventricular hypertrophy)

At birth, infants may not show the signs of the cyanosis, but later may develop sudden frightening episodes (called "Tet spells") of bluish skin from crying or feeding.

Tetralogy of Fallot is considered rare. Patients with tetraology of Fallot have a higher incidence of major non-heart congenital defects.

The cause of most congenital heart defects is unknown. Multiple factors seem to be involved. Prenatal factors associated with higher than normal risk for this condition include maternal rubella or other viral illnesses during pregnancy, poor prenatal nutrition, maternal alcoholism, mother over 40 years old, and diabetes.

There is a high incidence of chromosomal disorders in children with tetralogy of Fallot, such as Down syndrome and Di George's syndrome (a partial gene deletion that results in heart defects, low calcium levels, and immune deficiency.)

Symptoms

Difficult feeding (poor feeding habits)
Failure to gain weight
Poor development
Cyanosis which becomes more pronounced during periods of agitation
Passing out
Sudden death
Clubbing of fingers (skin or bone enlargement around the finger nails)
Squatting during episodes of cyanosis
Stroke

Signs and tests

A physical examination with a stethoscope almost always reveals a heart murmur.

Tests may include:

EKG (electrocardiogram) may show the thickening of the right ventricle muscle
CBC may show an increase in red blood cells
Chest x-ray may show a "boot shaped" heart and dark lungs
Cardiac catheterization helps show blood vessels in the lungs and heart
Echocardiogram provides a definite diagnosis
MRI of the heart (generally after surgery)

Treatment

Surgery to repair heart defects is always done when the infant is very young. Sometimes more than one surgery is needed. The first surgery may be done to help increase blood flow to the lungs. Surgery to correct the problem may be done at a later time. (Generally, a definitive 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.

Tips for parents of children with tetralogy of Fallot:

If a child does become blue, immediately place the child on his or her side and put the knees up to the chest. Calm the baby and seek medical attention immediately
Feed the child slowly
Give smaller, more frequent meals
Decrease the child's anxiety by remaining calm
Minimize crying by trying to anticipate the child's needs
Recruit others to care for the child to prevent yourself from becoming exhausted

Expectations (prognosis)

Most cases can be corrected with surgery. Babies who have surgery usually do well. Ninety percent survive to adulthood and live active, healthy, and productive lives. Without surgery, death usually occurs by the time the person reaches age 20.

Patients who have continued, severe leakiness of the pulmonary valve may need the valve replaced.

Regular follow up with a cardiologist to monitor for life-threatening arrhythmias (irregular heart rhythms) is recommended.

Complications

Delayed growth and development
Seizures during periods of insufficient oxygen
Arrhythmias
Death

Calling your health care provider

Call your health care provider if new unexplained symptoms develop or if the patient is having an episode of cyanosis (blue skin).

Prevention

There is no known prevention.

References

Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 8th ed. St. Louis, Mo; WB Saunders; 2007.

Review Date:12/10/2007
Reviewed By:David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.; and Mark A Fogel, MD, FACC, FAAP, Associate Professor of Pediatrics and Radiology, Director of Cardiac MR, The Children's Hospital of Philadelphia.

ADAM Quality A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial process. A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The Agency for Health Care Administration (Agency) and this website do not claim the information on, or referred to by, this site is error free. This site may include links to websites of other government agencies or private groups. Our Agency and this website do not control such sites and are not responsible for their content. Reference to or links to any other group, product, service, or information does not mean our Agency or this website approves of that group, product, service, or information.

Additionally, while health information provided through this website may be a valuable resource for the public, it is not designed to offer medical advice. Talk with your doctor about medical care questions you may have.