USMLE Step 3 - Question 48

A 45 year old prostitute presents to the emergency department with increased shortness of breath and lower extremity edema slowly worsening over a few months. Her temperature is 37.2, blood pressure 140/60, heart rate 100, and respirations 20. Physical examination reveals a II/IV short early diastolic murmur at the right upper sternal border loudest in end-expiration while having her lean forward. Laboratory studies are normal. Which of the following is the most likely diagnosis?

A. Bicuspid aortic valve

B. Aortic valve endocarditis

C. Aortic dissection

D. Syphilitic aortitis

This patient has aortic valve regurgitation which is causing congestive heart failure symptoms. The location of the murmur at the right upper sternal border implies that the problem is due to aortic root dilation resulting in failure of the aortic valve leaflets to coapt resulting in the aortic regurgitation. An organic problem with the aortic valve leaflets (bicuspid or destruction from endocarditis) would cause an aortic regurgitation murmur to be located at the left lower sternal border (Erb’s point). Thus, syphilitic aortitis is the most likely cause. Remember that treponema pallidum can infect the vaso vasorum (the small arteries that supply the wall of the aorta) resulting in aortic aneurysms, most commonly in the aortic root and ascending thoracic aorta. While aortic dissection also causes dilation of the aortic root and aortic regurgitation, she does not have any chest pains or other symptoms concerning for this diagnosis.