Tetralogy of Fallot
Anatomic hallmark is anterior malalignment of infundibular (outlet) septum, which results in
- A large and unrestrictive ventricular septal defect (VSD)
- Various degrees of right ventricular outflow tract obstruction (RVOTO)
- Overriding aorta
- Right ventricular hypertrophy (RVH) secondary to exposure to systemic pressure
- The most common cyanotic congenital heart disease
- 3.5–10% of all congenital heart disease
About 20% of cases of tetralogy of Fallot are associated with a chromosome 22q11 microdeletion or duplication.
- Severity of clinical signs and symptoms depends on the degree of RVOTO and related right-to-left shunt at the VSD.
- Physiology is a spectrum ranging from too little pulmonary blood flow and right-to-left shunt at the VSD due to severe RVOT obstruction (“blue tet”) to moderate pulmonary overcirculation and left-to-right shunt at the VSD with minimal RVOTO (“pink tet”).
Commonly Associated Conditions
- May be associated with other syndromes including trisomy 21, Alagille syndrome, fetal alcohol syndrome, and those involving a variety of limb abnormalities
- Tetralogy of Fallot may also be associated with midline abdominal defects (e.g., omphalocele) as in the pentalogy of Cantrell.
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