Tetralogy of Fallot

Tetralogy of Fallot, or TOF, is one of the most common forms of complex congenital heart defects that causes cyanosis, or a blue baby. Tetralogy of Fallot is comprised of four separate components. The first one is a ventricular septal defect (VSD). The second one is pulmonary stenosis (PS). The third component is right ventricular hypertrophy, which is an increase in the size of the right ventricle. The final component is an overriding aorta (Ao), which means that the aorta lies directly over the ventricular septal defect.

The ventricular septal defect is usually large and blood flows from the right ventricle through this VSD into the left ventricle. This occurs because of the resistance of blood flow through the pulmonary valve. Once the blood flows into the left ventricle, it is ejected into the aorta and delivers de-oxygenated blood into the body. Because there is de-oxygenated blood being delivered to the body, these babies may appear cyanotic, or "blue". This cyanosis may increase in severity with crying, agitation or bowel movements.

Open heart surgery is needed to correct this defect

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