Glossary of Terms
Tetralogy of Fallot
Tetralogy of Fallot includes four structural anomalies:
- ventricular septal defect (VSD)
- dextroposition or overriding of the aorta
- right ventricular outflow obstruction or pulmonary stenosis
- right ventricular hypertrophy
Of the four defects, pulmonary stenosis and VSD are the most important because they cause cyanosis (blood not being able to be oxygenated). The pulmonary stenosis causes right ventricular hypertrophy. This causes unoxygenated blood to be shunted through the VSD into the left ventricle where it is mixed. Thus, the ventricle pumps arterial blood with an abnormally low oxygen saturation to the systemic tissues and causes cyanosis.