Tetralogy of Fallot
National Organization for Rare Disorders, Inc.
It is possible that the main title of the report Tetralogy of Fallot is not the name you expected.
Tetralogy of Fallot is the most common form of cyanotic congenital heart disease. Cyanosis is the abnormal bluish discoloration of the skin that occurs because of low levels of circulating oxygen in the blood. Tetralogy of Fallot consists of the combination of four different heart defects: a ventricular septal defect (VSD); obstructed outflow of blood from the right ventricle to the lungs (pulmonary stenosis); a displaced aorta, which causes blood to flow into the aorta from both the right and left ventricles (dextroposition or overriding aorta); and abnormal enlargement of the right ventricle (right ventricular hypertrophy). The severity of the symptoms is related to the degree of blood flow obstruction from the right ventricle.
The normal heart has four chambers. The two upper chambers known as atria are separated from each other by a fibrous partition known as the atrial septum. The two lower chambers are known as ventricles and are separated from each other by the ventricular septum. Valves connect the atria (left and right) to their respective ventricles. The valves allow for blood to be pumped through the chambers. Blood travels from the right ventricle through the pulmonary artery to the lungs where it receives oxygen. The blood returns to the heart through pulmonary veins and enters the left ventricle. The left ventricle sends the now oxygen-filled blood into the main artery of the body (aorta). The aorta sends the blood throughout the body.
Ventricular Septal Defect
The heart has an inner wall that separates the two chambers, called a septum. The septum stops mixing of the blood between the two sides. A ventricular septal defect is a hole in the septum that causes oxygen-rich blood (left ventricle) and the oxygen-poor blood (right ventricle) to mix.
This defect is the narrowing of the pulmonary valve, which flows oxygen poor blood into the pulmonary artery and from there the blood travels to the lungs to pick up oxygen. Pulmonary stenosis is when the pulmonary valve cannot open fully, making the heart work harder and results in a lack of blood reaching the lung.
Right Ventricular Hypertrophy
The muscle of the right ventricle is thicker due to the right side of the heart receiving excessive blood flow from the left side of the heart through the ventricular septal defect and working harder.
In a normal heart, the aorta is attached to the left ventricle and allows oxygen-rich blood to flow throughout the body. In a tetralogy of Fallot heart, the aorta is located between both the left and the right ventricle. This causes oxygen-poor blood from the right ventricle to flow into the aorta instead of the pulmonary artery. If infants with tetralogy of Fallot are not treated, the symptoms usually become progressively more severe. Blood flow to the lungs may be further decreased and severe cyanosis may cause life-threatening complications. The exact cause of tetralogy of Fallot is not known.
Adult Congenital Heart Association
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American Heart Association
- 7272 Greenville Avenue
- Dallas, TX 75231
- Tel: (214)784-7212
- Fax: (214)784-1307
- Tel: (800)242-8721
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Congenital Heart Information Network (C.H.I.N.)
- P.O. Box 3397
- Margate City, NJ 08402-0397
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- Website: http://www.tchin.org
Genetic and Rare Diseases (GARD) Information Center
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- Gaithersburg, MD 20898-8126
- Tel: (301)251-4925
- Fax: (301)251-4911
- Tel: (888)205-2311
- Website: http://rarediseases.info.nih.gov/GARD/
Kids With Heart ~ National Association for Children's Heart Disorders, Inc.
- 1578 Careful Dr.
- Green Bay, WI 54304
- Tel: (920)498-0058
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Little Hearts, Inc.
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NIH/National Heart, Lung and Blood Institute
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- Bethesda, MD 20892-0105
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- Website: http://www.nhlbi.nih.gov/
For a Complete Report
This is an abstract of a report from the National Organization for Rare Disorders (NORD). For a full-text version of this report, go to www.rarediseases.org and click on Rare Disease Database under "Rare Disease Information".
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Last Updated: 8/18/2016
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