USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

Which cardiac anomaly can lead to Eisenmenger's syndrome with cyanosis and clubbing?

1. Coarctation of the aorta

2. Patent ductus arteriosus

3. Aortic stenosis

4. Mitral stenosis

The correct answer is: Patent ductus arteriosus

Eisenmenger's syndrome is a consequence of significant left-to-right shunting of blood, commonly due to conditions that cause pulmonary hypertension. The key feature of this syndrome is that over time, the increased blood flow to the lungs leads to vascular changes that can subsequently result in a reversal of blood flow, causing right-to-left shunting and resulting in cyanosis and clubbing. Patent ductus arteriosus (PDA) is a condition where there is a persistent connection between the aorta and the pulmonary artery after birth, which typically allows oxygenated blood to flow from the aorta into the pulmonary artery. If the PDA is large, it increases the workload on the right side of the heart and leads to increased pulmonary blood flow. Over time, if left untreated, this can cause pulmonary hypertension and ultimately reverse the shunt, leading to cyanosis and clubbing, hallmark signs of Eisenmenger’s syndrome. In contrast, conditions such as coarctation of the aorta, aortic stenosis, and mitral stenosis do not primarily cause a significant left-to-right shunt that would lead to Eisenmenger's syndrome. Coarctation of the aorta might cause upper body hypertension and lower body perfusion issues