Sudden Palpitations in the Emergency Department

You are leading the care team in the emergency department. A 54-year-old woman reports a sudden racing heartbeat and lightheadedness that began about 20 minutes ago. She is alert and speaking clearly. Her pulse is regular at 178/min, blood pressure is 112/74 mm Hg, respiratory rate is 18/min, and oxygen saturation is 97% on room air. She denies chest discomfort and shortness of breath. A nurse, cardiac monitor, IV supplies, emergency medications, and a monitor/defibrillator are immediately available.