USMLE Step 2 - Question 12

A 36 year old female with no past medical history presents to her primary care office a complaint of chest pains for the past few months. She states that intermiittently she has a feeling that she is going to die and develops severe chest pains and palpitations. The pain is substernal, pressure-like, and radiating to her left arm. It can last for minutes or hours at a time. Her blood pressure is 120/80, heart rate 80, and respirations 20. Physical examination reveals normal lung sounds, no murmurs, and a mid-systolic click that moves to early systole with standing from a squatting position. Her ECG is normal. Which of the following is the most likely diagnosis?

A. Mitral valve regurgitation

B. Myocardial ischemia

C. Mitral valve prolapse

D. Mitral valve stenosis

Mitral valve prolapse (MVP) is quite common in young females. There is a strong association bewtween mitral valve prolapse and anxiety/panic disorders which has been well described and is thought to be due to adrenergic hypersensativity. A majority of cases are completely benign without any cardiac ramifications. A smaller percentage of patients develop mitral valve dysfunction leading to mitral regurgitation which may require surgical valve repair (remember repair is preferred over replacement if possible). There will only be a murmur associated with mitral valve prolapse if there is concominant mitral valve regurgitation. The patient in question #12 did not have a murmur, this there is likely no significant regurgitation. Certain maneuvers can be done to verify that the extra-systolic heart sound is indeed a click of mitral valve prolapse. When the patient stands from a squatting position all of the blood pools in the legs decreasing the left ventricular filling which in turn decreases the left ventricular volume causing the click to move earlier in systole. The opposite occurs with squatting from a standing position.