Tetralogy of Fallot Overview: ventricular septal defect, aorta, thick muscle right ventricle

Tetralogy of Fallot - What it is

Tetralogy of Fallot (TOF) consists of four defects.

A hole (ventricular septal defect) between the two lower heart chambers (ventricles).
There is an obstruction from the right ventricle to the lung caused by thick muscle (infundibular stenosis) and/or narrowing of the pulmonary valve (pulmonary stenosis).
The aorta, which is the major artery that supplies oxygen-rich blood to the body, lies over the ventricular septal defect (overriding aorta).
The muscle of the right ventricle becomes thick (right ventricular hypertrophy).

Less oxygenated ‘blue’ blood returning to the right side of the heart is mixed with the oxygenated ‘red’ blood from the left side of the heart through the hole and into the overriding aorta. Babies with unrepaired TOF are often blue. Sometimes, the pulmonary valve is also completely obstructed (pulmonary atresia).

Associated problems can include an atrial septal defect (hole between the two upper heart chambers) and abnormalities of the coronary arteries.

Common problems which can remain after repair can include:

Residual pulmonary valve narrowing or leaking (Pulmonary stenosis or regurgitation)
Branch pulmonary artery narrowing (Pulmonary artery stenosis)
Abnormal heart rhythms (Arrhythmias)
Aortic valve leaking (Aortic regurgitation)