American Board of Internal Medicine (ABIM) Certification Practice Exam

What is a characteristic sign of coarctation of the aorta?

1. Bilateral lower extremity pulse equalization

2. Brachial-femoral pulse delay

3. Presence of an audible rubbing sound

4. Decreased blood pressure in the arms

The correct answer is: Brachial-femoral pulse delay

In coarctation of the aorta, a characteristic sign is the brachial-femoral pulse delay. This condition involves a narrowing of the aorta, typically just distal to the left subclavian artery, which leads to differential blood flow. When the aorta is coarcted, the left arm and head receive adequate blood supply due to their proximity to the heart, resulting in a strong brachial pulse. However, the femoral pulse may be weaker and delayed due to the obstruction, leading to a notable difference in timing when comparing pulses in the upper and lower extremities. This understanding is critical in clinical practice as recognizing the brachial-femoral pulse delay can help prompt further investigation or imaging to confirm the diagnosis of coarctation of the aorta. The other options do not accurately represent the typical presentation associated with this condition. In particular, bilateral lower extremity pulse equalization would suggest no obstruction in blood flow, while the presence of an audible rubbing sound is more indicative of pericarditis. Decreased blood pressure in the arms would not be expected; typically, blood pressure may be higher in the arms compared to the legs due to the narrowed segment of the aorta.