Tetralogy of Fallot

Key Features

Essentials of Diagnosis

• Five features are characteristic:

  • Ventricular septal defect (VSD)

  • Concentric right ventricular hypertrophy (RVH)

  • Right ventricular (RV) outflow obstruction due to infundibular stenosis

  • Overriding aorta (requires < 50% of the aorta to override the septum) in half

  • A right-sided aortic arch in 25%

• Most adult patients have undergone surgical repair, usually with an RV outflow patch and VSD closure; if patch overrides the pulmonary valve annulus, pulmonary regurgitation is common

• Physical examination may be deceptive after classic tetralogy repair, with severe pulmonary valve regurgitation often present if a transannular patch was used

• Echocardiography/Doppler may underestimate significant pulmonary valve regurgitation; be wary if the RV is enlarged

• Arrhythmias are common; periodic ambulatory monitoring is recommended

• Serious arrhythmias and sudden death may occur if the QRS is wide or the RV becomes quite large or both

General Considerations

• If there is an associated atrial septal defect (ASD), the complex is called pentalogy of Fallot

• Pulmonary valve stenosis may also be present, usually due to either a bicuspid pulmonary valve or RV outflow hypoplasia

• The aorta can be enlarged and aortic regurgitation may occur

• If > 50% of the aorta overrides into the RV outflow tract, the anatomy is referred to as a double outlet RV

• Two vascular abnormalities are common

  • An inconsequential right-sided aortic arch (in 25%)

  • Anomalous left anterior descending coronary artery from the right cusp (7–9%)

Clinical Findings

Symptoms and Signs

• Most adult patients in whom tetralogy of Fallot has been repaired are relatively asymptomatic unless right heart failure or arrhythmias occur

• Physical examination should check both arms for any loss of pulse from a prior shunt procedure in infancy

• Jugular venous pulsations (JVP) may reveal

  • An increased a wave from poor RV compliance

  • A c-v wave due to tricuspid regurgitation (rarely)

• The precordium may be active

• P₂ may or may not be audible

• A right-sided gallop may be heard

• A residual VSD or persistent pulmonary outflow or aortic regurgitation murmur may be heard

• The insertion site of a prior Blalock or other shunt may create a stenotic area in the branch pulmonary artery (PA) causing a continuous murmur

• Pulmonary arterial stenotic bruits may best be heard on the lateral chest wall

Diagnosis

Imaging Studies

• Chest radiograph shows

  • A classic boot-shaped heart with prominence of the RV and a concavity in the RV outflow tract

  • An enlarged and right-sided aorta

• Echocardiography/Doppler

  • Establishes the diagnosis by noting the unrestricted (large) VSD, the RV infundibular stenosis, and the enlarged aorta

  • Provides data regarding the amount of residual pulmonary valve regurgitation if a transannular patch is present, RV and LV function, and the presence of aortic regurgitation in patients ...