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Fallot tetralogy

In medicine, the tetralogy of Fallot (described by Etienne Fallot, 1850 - 1911, Marseille) is a significant and complex congenital heart defect. more...

Fabry's disease
Factor V Leiden mutation
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Fallot tetralogy
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Fanconi syndrome
Fanconi's anemia
Farber's disease
Fatal familial insomnia
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Fitz-Hugh-Curtis syndrome
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Fountain syndrome
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Fraser syndrome
FRAXA syndrome
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Frontotemporal dementia
Fructose intolerance

The term blue baby syndrome is sometimes applied to the tetralogy of Fallot, but is less specific and includes other conditions.

Four malformations

It involves four different heart malformations:

  1. A ventricular septal defect (VSD): a hole between the two bottom chambers (ventricles) of the heart.
  2. Pulmonic stenosis: Right ventricular outflow tract obstruction, a narrowing at or just below the pulmonary valve.
  3. Overriding aorta: The aorta is positioned over the VSD instead of in the left ventricle.
  4. Right ventricular hypertrophy: The right ventricle is more muscular than normal.

Pseudotruncus arteriosus is a particularly severe variant of the tetralogy of Fallot, in which there is complete obstruction of the right ventricular outflow tract. In these individuals, there is complete right to left shunting of blood. The lungs are perfused via collaterals from the systemic arteries. These individuals are severely cyanotic and will have a continuous murmur on physical exam due to the collateral circulation to the lungs.


The tetralogy of Fallot generally results in low oxygenation of blood due to mixing of oxygenated and deoxygenated blood in the left ventricle and preferential flow of blood from the ventricles to the aorta because of obstruction to flow through the pulmonary valve. This is known as a right-to-left shunt. It is often evidenced by a bluish tint to the baby's skin (cyanosis). However there are "pink Fallots" in which the degree of obstruction in the pulmonary tract (right ventricular outflow, pulmonary valve and pulmonary arteries) is low. Blood flows preferentially from the ventricles to the lungs and only minimal desaturation occurs in the systemic circulation because of mixing of saturated and desaturated blood in the ventricles. This degree of desaturation may be undetectable to the eye and requires a pulse oximeter to identify it.

Even children who are generally not too deeply cyanosed (blue) may develop acute severe cyanosis or hypoxic "tet spells". The precise mechanism of spelling is in doubt but certainly this is a dangerous event and presumably results from an increase in resistance to blood flow to the lungs with increased preferential flow of desaturated blood to the body. Such spells may be treated with beta-blockers such as propranolol, but acute episodes may require rapid intervention with oxygen, morphine (to reduce ventilatory drive) and phenylephrine (to increase blood pressure). There are also simple procedures such as knee-chest position which reduces systemic venous return (to reduce the right-to-left shunting), increases systemic vascular resistance (and hence blood pressure) and provides a calming effect when the procedure is performed by the parent.


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Early Surgical Management Of Tetralogy Of Fallot - Abstract
From CHEST, 10/1/99 by Shabir Bhimji

Purpose: The current impetus towards early surgical repair of tetralogy of Fallot is controversial and prompted us to review 155 infants who were operated at our institution over an 8 year period.

Methods: 155 infants and young children underwent primary repair of tetralogy of Fallot over an 8-year period. There were 81 girls and 74 boys. Cyanosis and "Tet" spells were present in 23% of infants. Thirteen percent of infants had undergone a prior Blalock-Taussig shunt. Excluded from the study were 5 infants because of complex congenital heart lesions. The mean age at the time of repair was 5.2 months. Pulmonary stenosis was present in 77% and pulmonary atresia was seen in 23% of infants. The transatrial approach was used in 77% and the transventricular approach in 23% of infants. Repair included transannular patch (TAP), homograft reconstruction or infundibular resection with patch. Mean follow up with Doppler echocardiography or cardiac catheterization was for 6.3 years.

Results: There were only two early deaths. The mean ICU stay was 5.6 days. Arthythmias were present in 48% of patients. TAP was required in 46% of infants, infundibular resection with patch in 32% and homograft reconstruction in 22%. Re-intervention for pulmonary artery patch reconstruction was required in 33% of infants over a 2-year period. The majority of patients are asymptomatic and in New York Heart Classification 1. Actuarial survival was 98% at 1 year and 96% at 5 years.

Conclusion: Tetralogy of Fallot can be repaired in infants at an early age with minimal morbidity and mortality. The favored approach is transatrial and early palliation does not compromise primary repair.

Shabir Bhimji, MD(*) and V H Moore. Medical College of Georgia, Augusta, GA.

COPYRIGHT 1999 American College of Chest Physicians
COPYRIGHT 2000 Gale Group

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