I will answer the sample USMLE Step 2 CK Questions with Explanations. These questions are available at USMLE.org
A 48-year-old man is brought to the emergency department by ambulance 45 minutes after he collapsed at home. He did not have loss of consciousness. He has a 6-week history of shortness of breath and severe fatigue when he walks 20 to 30 feet. During the past 6 weeks, he also has had a 5-kg (11-lb) weight gain despite a decreased appetite. He has no history of serious illness. He cannot remember his last visit to a physician. His only medication is ibuprofen for intermittent mild headaches. His father died of “heart problems” at the age of 78 years. The patient has smoked one pack of cigarettes daily for 22 years. He has consumed 24 cans of beer weekly for 20 years. He works as a painting and drywall contractor but was unable to work last week because of fatigue. Temperature is 36.8°C (98.2°F), pulse is 100/min and regular, respirations are 16/min, and blood pressure is 90/55 mm Hg while supine. Pulse oximetry on 4 L/min of oxygen by nasal cannula shows an oxygen saturation of 91%. On examination, crackles are heard halfway up the lung fields bilaterally. An S3 is heard; no murmurs are heard. The liver span is 5 cm. There is moderate pitting edema of the calves and ankle swelling bilaterally. Echocardiography is most likely to show which of the following findings?
(A) A large pericardial effusion
(B) Dilated cardiomyopathy
(C) Left ventricular hypertrophy
(D) Paradoxical septal motion
(E) Regional wall motion abnormality
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Answer
This patient’s presentation is most consistent with heart failure, likely due to dilated cardiomyopathy (DCM). Several clinical features support this diagnosis:
- Symptoms of Heart Failure: The patient has a 6-week history of shortness of breath, severe fatigue, and weight gain despite a decreased appetite. These are common symptoms of heart failure, especially with fluid retention.
- Signs of Fluid Overload: Crackles in the lungs, pitting edema, and ankle swelling suggest pulmonary congestion and peripheral edema, which are associated with heart failure.
- Cardiac Examination Findings: The presence of an S3 heart sound is indicative of increased filling pressures and left ventricular dysfunction, which are characteristic of heart failure.
- Vital Signs and History: Low blood pressure (90/55 mm Hg), tachycardia (pulse of 100/min), smoking history, heavy alcohol use, and a family history of heart disease are all risk factors for developing cardiomyopathy.
Echocardiography in this case is most likely to show dilated cardiomyopathy, which is characterized by left ventricular dilation and systolic dysfunction. Dilated cardiomyopathy can result from chronic alcohol abuse, which can lead to direct myocardial toxicity, or from other causes such as viral infections, genetic predisposition, or uncontrolled hypertension.
The correct answer is B