Scenario: A 60-year-old man was admitted with exacerbated chronic obstructive pulmonary disease attributed to community-acquired right lower lobe pneumonia. His medical history was significant due to hypertension, diabetes, and a 40 pack/year history of smoking tobacco. His treatment included noninvasive ventilation, antibiotics, intravenous steroids, and aerosolized bronchodilators. On the second day he developed asymptomatic tachycardia at 160/min (A). A carotid sinus massage was attempted with no response, so intravenous adenosine (6 mg) was administered. This led to ventricular standstill with low voltage sawtooth waves (B). The patient reported flushing and increased shortness of breath, but the ventricles spontaneously recovered and the cardiac rhythm reverted to the narrow complex tachycardia (C).

(A) Narrow complex supraventricular tachycardia (SVT) at 150/min; (B) ventricular standstill with saw tooth pattern (F waves) indicative of atrial activity, with 2 escape beats; (C) atrial flutter of more than 150/min with...

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