Tetralogy of fallot

Tetralogy of Fallot

Description, Causes and Risk Factors:

Tetralogy of Fallot is classified as a cyanotic heart defect because the condition causes low oxygen levels in the blood. This leads to cyanosis (a bluish-purple color to the skin). There are about 5 cases of Tetralogy of Fallot out of every 10,000 live births accounting for about 5% of all congenital heart disease.

The classic form of tetralogy includes four related 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.

  • A thickened muscular wall of the right ventricle (right ventricular hypertrophy).

Anyone can get Fallot's but it is commoner in certain conditions, such as DiGeorge syndrome (22q11 deletion). It can be inherited and so run in families. Whatever the cause of Fallot's tetralogy, it is present from birth and, in fact, from very early on in the pregnancy (possibly the 7th week after conception).

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

Tetralogy of Fallot is rare, but it is the most common form of cyanotic congenital heart disease. Patients with tetraology of Fallot have a higher incidence of major non-heart congenital defects.

Risk Factors:

    Alcoholism in the mother.

  • Diabetes.

  • Mother who is over 40 years old.

  • Poor nutrition during pregnancy.

  • Rubella or other viral illnesses during pregnancy.

There is a high incidence of chromosomal disorders in children with tetralogy of Fallot, such as Down syndrome and DiGeorge syndrome (a condition that causes heart defects, low calcium levels, and immune deficiency).


    Cyanosis, which becomes more pronounced when the baby is upset.

  • Clubbing of fingers (skin or bone enlargement around the fingernails).

  • Difficult feeding (poor feeding habits).

  • Failure to gain weight.

  • Passing out.

  • Poor development.

  • Squatting during episodes of cyanosis.


Similar to many complex congenital heart diseases,tetralogy of Fallot is frequently diagnosed during fetal life. For those with severely obstructed pulmonaryblood ?ow, fetal diagnosis allows better planning ofperinatal management and facilitates early prostaglandintherapy to maintain ductal patency, thus avoidinglife-threatening cyanosis in the early newborn period.Nonetheless, most children present with the conditionafter birth. Although an experienced pediatrician orcardiologist usually suspects the diagnosis clinically,transthoracic cross-sectional echocardiography providesa comprehensive description of the intracardiac anatomy. With the exception of patients with majoraortopulmonary collateral arteries and rare cases inwhom echocardiographic assessment is incomplete, anyother diagnostic investigations (e.g., cardiac catheterisation)are now rarely done before palliative or correctivesurgery.


Most cases can be corrected with surgery. Surgery to repair Tetralogy of Fallot is done when the infant is very young. 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.

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 to have the valve replaced.

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

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.


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