Which feature is a characteristic of Tetralogy of Fallot?

Which feature is a characteristic of Tetralogy of Fallot?

• A. Aortic stenosis
• B. Pulmonary stenosis
• C. Mitral valve prolapse
• D. Coarctation

Answer: (B)

Pulmonary stenosis is the feature that defines Tetralogy of Fallot’s physiologic problem. The obstruction of the right ventricular outflow tract raises right-sided pressures, which promotes a right-to-left shunt across a ventricular septal defect and markedly reduces blood flow to the lungs. This combination underlies the characteristic cyanosis seen in TOF. The other components—an overriding aorta, a large VSD, and right ventricular hypertrophy—complete the syndrome, but the pulmonary stenosis is the key driver of the abnormal hemodynamics. The other options (aortic stenosis, mitral valve prolapse, coarctation) are not part of Tetralogy of Fallot.

Pulmonary stenosis is the feature that defines Tetralogy of Fallot’s physiologic problem. The obstruction of the right ventricular outflow tract raises right-sided pressures, which promotes a right-to-left shunt across a ventricular septal defect and markedly reduces blood flow to the lungs. This combination underlies the characteristic cyanosis seen in TOF. The other components—an overriding aorta, a large VSD, and right ventricular hypertrophy—complete the syndrome, but the pulmonary stenosis is the key driver of the abnormal hemodynamics. The other options (aortic stenosis, mitral valve prolapse, coarctation) are not part of Tetralogy of Fallot.