Coronary Artery Disease USMLE Step 1 Practice Question
A 68-year-old man presents with acute substernal chest pain radiating to his left arm for 2 hours. Vital signs: BP 142/88 mmHg, HR 102 bpm, RR 20, temp 37.2°C, SpO2 98% on room air. He denies dyspnea. ECG shows ST elevation in leads II, III, aVF. Troponin I is elevated at 2.4 ng/mL. He takes aspirin and metoprolol chronically. Which ion is primarily responsible for the rapid depolarization during phase 0 of the ventricular action potential?
Answer choices
- AMagnesium through T type channels
- BSodium through fast voltage gated channelsCorrect answer
- CCalcium through L type channels
- DPotassium through delayed rectifier channels
- EChloride through ligand gated channels
- FCalcium through fast voltage gated channels
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