USMLE Step 3 - Question 16

A 26 year old female with no past medical history presents to her primary care office with a complaint of palpitations for the past few months. She states that they occur intermittently and are not associated with dizziness, syncope, or chest pains. 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 associated with this cardiac disorder?

A. Marfan's syndrome

B. Congenital coronary anomalies

C. Sudden cardiac death

D. Ventricular tachycardia

This patient on physical examination has mitral valve prolapse (MVP) which is quite common in young females. There is a strong association between MVP and anxiety/panic disorders which has been well described and is thought to be due to adrenergic hypersensitivity which can also cause palpitations. 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 concomitant mitral valve regurgitation.

The patient in question #16 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 MVP. 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. Remember MVP is a common manifestation of connective tissues diseases such as Marfan's syndrome. Despite prior debate, there is no evidence that patient's with MVP have an increased risk of sudden cardiac death, from ventricular tachycardia or other rhythm disorders.

MVP