Which Of The Following Is A Component Of The Tetralogy Of Fallot?

Which Of The Following Is A Component Of The Tetralogy Of Fallot?

• A. Pulmonary Stenosis
• B. Patent Foramen Ovale
• C. Atrial Septal Defect
• D. Ductus Arteriosus

Answer: (A)

Pulmonary stenosis is one of the defining features of Tetralogy of Fallot. The obstruction to the right ventricular outflow tract reduces blood flow to the lungs and promotes a right-to-left shunt across a ventricular septal defect, which drives the cyanosis seen in TOF. The other options do not constitute core components of the tetralogy: a patent foramen ovale and an atrial septal defect are defects at the atrial level, not part of the four characteristic features; the ductus arteriosus is a fetal vessel that normally closes after birth and is not a component of the tetralogy. Therefore, pulmonary stenosis best fits as the component listed.

Pulmonary stenosis is one of the defining features of Tetralogy of Fallot. The obstruction to the right ventricular outflow tract reduces blood flow to the lungs and promotes a right-to-left shunt across a ventricular septal defect, which drives the cyanosis seen in TOF. The other options do not constitute core components of the tetralogy: a patent foramen ovale and an atrial septal defect are defects at the atrial level, not part of the four characteristic features; the ductus arteriosus is a fetal vessel that normally closes after birth and is not a component of the tetralogy. Therefore, pulmonary stenosis best fits as the component listed.