Tetralogy of Fallot (TOF)
Definition
Embryologically, a single defect with hypoplasia of the conus causing:
Infants may initially have a L --> R shunt and therefore are not cyanotic but the RVOTO is
progressive, resulting in increasing R --> L shunting with hypoxemia and cyanosis
Epidemiology
Clinical Features
Symptoms
Signs
Management
Investigations
Treatment
Source
Toronto Notes 2012
Embryologically, a single defect with hypoplasia of the conus causing:
- VSD
- Right ventricle (RV) outflow tract obstruction (RVOTO) (e.g. pulmonary stenosis)
- Overriding aorta
- RVH
Infants may initially have a L --> R shunt and therefore are not cyanotic but the RVOTO is
progressive, resulting in increasing R --> L shunting with hypoxemia and cyanosis
Epidemiology
- 10% of all CHD, most common cyanotic heart defect diagnosed beyond infancy
- Peak incidence at 2-4 months of age
Clinical Features
Symptoms
- Hypoxic "tet" spells
- Paroxysm of rapid and deep breathing, irritability and crying
- Hyperpnea, increasing cyanosis
- If severe may lead to seizures, loss of consciousness, death (rare)
Signs
- Clubbing
- Single loud S2 due to severe pulmonary stenosis (i.e. RVOTO)
Management
- 0 2, knee-chest position, fluid bolus, morphine sulfate, propanolol
Investigations
- ECG: RAD, RVH
- CXR: boot shaped heart (small PA, RVH), decreased pulmonary vasculature, right aortic arch (in 20%)
Treatment
- Surgical repair
Source
Toronto Notes 2012