Tetralogy of Fallot

Description

Tetralogy of Fallot was originally described as a combination of four abnormalities: ventricular septal defect (VSD), right ventricular outflow tract obstruction, overriding aorta and right ventricular hypertrophy. There is typically an anterior malalignement of the conal septum. The right ventricular hypertrophy is a consequence of the overriding aorta exposing the RV to systemic pressures, the large VSD equalizing pressure +/- RVOT obstruction. The VSD is a perimembranous defect. In some cases, TOF can be associated with complete atresia of the pulmonary valve (TOF-Pulmonary Atresia) or with coronary anomalies. The rare form of TOF with absent pulmonary valve is associated with an absent / rudimentary pulmonary annulus which is stenotic. Because of the free pulmonary insufficiency, there is progressive dilation (aneurysmal) of the pulmonary arteries, which may lead to severe obstruction of the airways. Some are associated with an absent ductus.

Case 1: Tetralogy of Fallot (TOF) no pulmonary stenosis

Apical views indicating the Tetralofy of Fallot, the large perimembranous central ventricular septal defect with aortic override. The mild deviation of the conal septum with no significant obstruction and the pulmonary valve and main pulmonary artery of normal size without obstruction.

Subcostal views showing the aorta override and the mild deviation of the conal septum

Small patent arterial duct (PDA) measuring 0.21 cm, shunting briefly right to left in early systole and left to right most of the cardiac cycle.

Case 2: Tetralogy of Fallot (TOF) mild pulmonary stenosis

PLAX with sweep in 2D and in Colour indicating the overriding Aorta and the malalignement ventricular septal defect

Apical view with sweep in 2D and 2D colour showing the overriding aorta, malalignement VSD and some mild aortic insufficiency.

Case 3: Tetralogy of Fallot (TOF) with major aortopulmonary collateral arteries (MAPCAs)

MAPCAs by colour flow

Apical views by 2D and 2D-Colour showing the VSD and the overriding aorta with flow from LV and RV going to the Aorta

Subcostal view for visualization of the VSD, Pulmonary valvular atresia (virtual) and some MAPCAs observed by Colour

Catheterism indicating the MAPCAs

Presentation on TOF - Absent Valve by Louise Gervais and Jean-Francois Trudel