Definition

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

Causes, incidence, and risk factors

Tetralogy of Fallot is classified as a cyanotic heart defect because the condition causes too little 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 occurs in approximately 5 out of 10,000 infants.

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

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

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, and a surgery to correct the problem is done at a later time. 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
• 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 that have surgery usually do well. Without surgery, death usually occurs when 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

Prevention

There is no known prevention.