CD-ROM Today 1996 January/CD-ROM Today 1996 January.iso/dp/0426/04260.txt

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$Unique_ID{BRK04260}
$Pretitle{}
$Title{Tetralogy of Fallot}
$Subject{Tetralogy of Fallot Pseudotruncus Arteriosus Pink Tetralogy of Fallot
Acyanotic Tetralogy of Fallot }
$Volume{}
$Log{}

Copyright (C) 1986 National Organization for Rare Disorders, Inc.

170:
Tetralogy of Fallot

** IMPORTANT **
It is possible that the main title of the article (Tetralogy of Fallot)
is not the name you expected.  Please check the SYNONYMS listing to find the
alternate names and disorder subdivisions covered by this article.

Synonyms

DISORDER SUBDIVISIONS

     Pseudotruncus Arteriosus
     Pink Tetralogy of Fallot, also known as Acyanotic Tetralogy of Fallot

General Discussion

** REMINDER **
The information contained in the Rare Disease Database is provided for
educational purposes only.  It should not be used for diagnostic or treatment
purposes.  If you wish to obtain more information about this disorder, please
contact your personal physician and/or the agencies listed in the "Resources"
section of this report.


Tetralogy of Fallot is a form of congenital heart disease.  It consists
of four defects.  These defects are:

     1.  A ventricular septal defect
     2.  Obstructed outflow of the blood from the right ventricle to the lungs
     3.  A displaced aorta so that it receives blood from both the right and
left ventricles
     4.  Enlargement of the right ventricle.

In addition to poor oxygen saturation which is due to poor blood flow to
the lungs, symptoms are similar to those of severe ventricular septal defects
(please see Rare Disease Database article on Ventricular Septal Defects).
The degree of obstruction of blood flow to the lungs determines the severity
of this disorder.  Untreated Tetralogy of Fallot sometimes progresses
becoming more severe as the child grows.  In particular, the lungs can be
permanently damaged by the abnormal pulmonary blood pressures generated by
the ventricular septal defect.  The patterns and quality of the sounds of the
beating heart, electrocardiographic (EKG) and echocardiographic findings, and
information from cardiac catheterization aid in diagnosis and therapy.

Symptoms

Infants with Tetralogy of Fallot show symptoms from birth or within the first
year of life.  They may not feed well often due to excessive fatigue; they
gain weight slowly and grow poorly.  With exertion, the children have severe,
potentially life threatening attacks of breathlessness and hypoxia (lack of
oxygen); they may assume a characteristic squatting posture which seems to
help them to breathe somewhat during these episodes.  Other signs of
insufficient oxygen delivery to the tissues include cyanosis (a bluish
coloration of the skin), clubbing of the finger tips, proliferation of red
blood cells.  A characteristic shape of the heart is usually visible on
x-rays.

In general the symptoms associated with large ventricular defects consist
of poor delivery of oxygen and congestive heart failure, characterized by
swelling and fluid retention in the lungs and body.  Rapid, "ineffectual",
heartbeat and great difficulty breathing may also be present.  (Please see
article on Ventricular Septal Defects for a more complete discussion of the
normal heart and the symptoms associated with large ventricular defects.)

The displacement of the aorta, the large artery leaving the heart and
branching into all the other arteries serving the body, also causes oxygen
unsaturated blood to reach the tissues.

Impaired outflow from the right ventricle usually results from an
obstruction of the valve between the heart and the pulmonary artery, or from
a narrowing of the channel at the top of right ventricle through which the
blood passes to the pulmonary valve.  When these obstructions are severe, the
disorder is sometimes known as Pseudotruncus Arteriosus rather than Tetralogy
of Fallot.  Blood flow to the lung is reduced and a large fraction of the
deoxygenated venous blood from the systemic veins moves almost directly into
the aorta and back into the systemic circulation.  The hypertrophy
(enlargement) of the right ventricle is associated with the inability of the
blood to pass easily into the pulmonary artery.

Heart defects seem to predispose patients to respiratory infections and
bacterial infection of the inner lining of the heart (bacterial
endocarditis).  Bacterial endocarditis seems to occur more often with small or
moderates sized septal defects.  These infections should be avoided,
particularly since resulting damage is likely to worsen the patient's
condition.

Other complications of this kind of congenital heart disease include iron
deficiency anemia, coagulation defects, a susceptibility to embolisms in the
systemic circulation and to cerebral infarctions (destruction of tissue due
to interrupted circulation) and abscesses.

Causes

The causes of the arrest in embryonic development resulting in congenital
heart disease are poorly understood.  In general, only about 10% of the cases
appear to be hereditary, although this seems to be higher in Tetralogy of
Fallot.  Maternal rubella (measles), alcoholism, or diabetes are sometimes
associated with heart defects.  Ostium primum defects often occur in
individuals with Down's Syndrome and certain other chromosomal abnormalities.

Affected Population

About 1% of live births have some kind of congenital heart defect; of these,
about 10 % have Tetralogy of Fallot.  Males are affected more often than
females.

Related Disorders

Other congenital heart defects include atrial and isolated ventricular septal
defects, valve defects of various kinds, malformations of the large vessels
entering and leaving the heart, and anomalous positions of the heart in the
chest.

Therapies:  Standard

The definitive treatment for Tetralogy of Fallot is surgical.  Total
correction of the defects is best delayed until later in childhood,
preferably around the age of 4 or 5 years.  Intermediate, palliative measures
that can be taken in infancy or early childhood include anastomosis of the
aorta or the subclavian artery and the pulmonary artery.

Presurgical, palliative treatment includes medication such as digitalis
to treat arrhythmias, excessively rapid heart beat, and heart failure.
Sodium restriction, diuretics and rest are also effective in treating
congestive heart failure.  Respiratory infections are treated vigorously, and
antibiotics are given prophylactically with such procedures as tooth
extractions to reduce the risk of developing bacterial endocarditis.  Severe
hypoxic spells may require the administration of oxygen, morphine and other
drugs to improve oxygen concentration.

Therapies:  Investigational

This disease entry is based upon medical information available through March
1987.  Since NORD's resources are limited, it is not possible to keep every
entry in the Rare Disease Database completely current and accurate.  Please
check with the agencies listed in the Resources section for the most current
information about this disorder.

Resources

For more information on Tetralogy of Fallot, please contact:

     National Organization for Rare Disorders (NORD)
     P.O. Box 8923
     New Fairfield, CT  06812-1783
     [phone]

     American Heart Association
     7320 Greenville Avenue
     Dallas, TX 75231
     [phone]

     NIH/National Heart, Lung and Blood Institute
     9000 Rockville Pike
     Bethesda, MD  20892
     [phone]

     American Lung Association
     1740 Broadway
     New York, NY 10019
     [phone]

For information on genetics and genetic counseling referrals, please
contact:

     March of Dimes Birth Defects Foundation
     1275 Mamaroneck Avenue
     White Plains, NY  10605
     [phone]

     Alliance of Genetic Support Groups
     35 Wisconsin Circle, Suite 440
     Chevy Chase, MD  20815
     (800) 336-GENE
     [phone]

References

Petersdorf, Robert G., et al, editors, Harrison's Principles of Internal
Medicine, tenth edition.  New York:  McGraw-Hill 1983, pp. 1383-96.