Heart Failure USMLE Step 1 Practice Question
A 76-year-old man with a history of heart failure and atrial fibrillation presents with dyspnea and peripheral edema. Vital signs show BP 148/92 mmHg, HR 118 bpm, RR 22/min, and SpO2 92% on room air. Echocardiography reveals ejection fraction of 35%. He denies chest pain. He is started on digoxin. Which of the following best describes the primary direct molecular action of this drug on cardiac myocytes?
Answer choices
- AL type calcium channel blockade
- BAdenosine A1 receptor activation
- CDigoxin inhibition of Na+/K+ ATPaseCorrect answer
- DBeta 1 receptor antagonism
- EAmiodarone potassium channel blockade
- FPhosphodiesterase-3 inhibition leading to increased cardiac contractility
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