Heart Failure USMLE Step 1 Practice Question
A 62-year-old man with a 10-year history of hypertension presents with progressive dyspnea on exertion, orthopnea, and bilateral ankle edema over the past 3 months. Physical examination reveals a displaced point of maximal impulse, an S3 gallop, and crackles at bilateral lung bases. Echocardiography shows a left ventricular ejection fraction of 35%. Which of the following neurohormonal mechanisms is primarily responsible for the progressive worsening of his condition?
Answer choices
- AReduced angiotensin II production decreasing peripheral vascular resistance
- BDecreased sympathetic nervous system activity reducing cardiac contractility
- CActivation of the renin-angiotensin-aldosterone system leading to sodium retention and vasoconstrictionCorrect answer
- DInhibition of antidiuretic hormone secretion promoting excessive diuresis
- EIncreased natriuretic peptide levels causing severe hyponatremia
- FIncreased parasympathetic nervous system tone causing bradycardia and reduced cardiac output
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