Tetralogy of Fallot

In Tetralogy of Fallot (right ventricular outflow tract obstruction, ventricular septal defect, right ventriuclar hypertrophy, over-riding aorta) the severity of clincial presentation is dependent upon the degree of obstruction to the right ventricular outflow tract. This is often dynamic (muscular bulge below the pulmonary valve) and will ultimately determine the degree of right to left shunting (and hence cyanosis etc.).

The degree of obstruction often progresses after birth and therefore children may present at a later date (although usually within the first two years).