Tetralogy of Fallot

This condition results from a single error: the conus septum develops too far anteriorly giving rise to two unequally proportioned vessels- - a large aorta and a smaller stenotic pulmonary trunk. The four main characteristics of Tetralogy of Fallot are:

• (1) pulmonary stenosis
• (2) ventricular septal defect (VSD) of the membranous portion (the septum is displaced too far anteriorly to contribute to the septum)
• (3) overriding aorta (the aorta straddles the VSD)
• (4) right ventricular hypertrophy due to the shunting of blood from left to right. (The pressure in the right ventricle is increased causing the walls of the right ventricle to expand.)

Figure

• AO = Aorta
• PT = Pulmonary trunk (stenotic)
• RV/LV = Right and left ventricles