Welcome to MedSmarter’s USMLE Style Question Break Down of the Week. For those preparing for the USMLE Step 1, this week we break down a high-yield Cardiology question. As always you want to begin with reading the last sentence of the vignette first to get an understanding of what the question is asking for.
Question Break Down of the Week:
A 75-year-old male with a past medical history of type 2 diabetes mellitus, a body mass index of 30 kg/m2, and a previous myocardial infarction 15 years ago presents to the emergency department with crushing substernal chest pain radiating to his neck and jaw. An ECG reveals ST-segment elevation in leads V3 and V4. Emergency cardiac catheterization with percutaneous coronary intervention (PCI) shows a 99% occlusion of his left anterior descending artery. The patient remains stable after PCI, and echocardiography shows a mildly impaired ejection fraction (EF) of 43%. Five days later, the patient becomes acutely hypotensive and dyspneic, and physical examination reveals a high-pitched holosystolic murmur, loudest at the apex and radiating to the axilla, that had not been heard on previous exams. An emergency echocardiogram shows an EF of 25%. This patient has developed which of the following?
A) Aortic Stenosis
B) Dressler’s Syndrome
C) Ruptured Interventricular Septum
D) Ruptured Left Ventricular Free Wall
E) Ruptured Papillary Muscle
F) Ventricular Aneurysm
The correct answer choice is E: This patient has suffered a rupture of one of the two left ventricular papillary muscles, a complication that may occur 3–10 days after an acute MI, when the infarcted area of the myocardium is replaced with granulation tissue and thus is the weakest. Without the anchor of the papillary muscle, there is severe acute mitral valve regurgitation, diagnosed by a new holosystolic “blowing murmur” that is loudest at the apex and radiates to the axilla, a severely reduced stroke volume (hypotension with EF of 25%), and evidence of pulmonary edema (dyspnea).
Did you think the answer was different?
Did you think that the correct answer choice was other than E? You can view this video for a deeper discussion of why B, C, D, and E were not the correct answer choices.
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