Autonomic Pharmacology USMLE Step 1 Practice Question
A 62-year-old man with a history of hypertension presents to the emergency department with a 3-week history of progressive dyspnea on exertion, orthopnea, and lower extremity edema. Vital signs are BP 158/94 mmHg, HR 110 bpm, RR 22/min, and SpO2 92% on room air. Physical examination reveals bibasilar crackles, an elevated jugular venous pressure, and 2+ pitting ankle edema. A transthoracic echocardiogram demonstrates a left ventricular ejection fraction of 32% with global hypokinesis. BNP is 520 pg/mL. After stabilization with diuretics, the cardiologist initiates carvedilol, a mixed β1-adrenergic and α-adrenergic receptor antagonist. Which of the following best explains the therapeutic benefit of this agent in this patient's condition?
Answer choices
- AIncreased myocardial contractility through enhanced calcium channel activity
- BDecreased myocardial oxygen demand by reducing heart rate and contractilityCorrect answer
- CPromotion of coronary artery vasodilation through direct smooth muscle relaxation
- DInhibition of the parasympathetic nervous system to increase cardiac output
- EEnhanced atrioventricular nodal conduction to improve diastolic filling
- FReduction of preload through selective alpha-1 blockade-mediated systemic vasodilation
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