Arrhythmias USMLE Step 1 Practice Question
A 74-year-old man with severe COPD hospitalized for acute dyspnea receives albuterol and ipratropium nebulizers. He develops palpitations and dyspnea. Vital signs: BP 142/88, HR 128 and irregular, RR 22, SpO2 89% on 2L oxygen, temperature 37.2°C. Physical examination reveals an irregularly irregular pulse with no murmurs. ECG demonstrates narrow QRS complexes with at least three distinct P-wave morphologies. Serum potassium is 3.2 mEq/L. Which diagnosis best explains these findings?
Answer choices
- AAtrial flutter
- BVentricular tachycardia
- CAtrial fibrillation
- DAV nodal reentrant tachycardia
- EMultifocal atrial tachycardiaCorrect answer
- FSinus tachycardia with premature atrial contractions
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