Sudden Lightheadedness in the Cardiac Observation Unit

You are leading a rapid response in a cardiac observation unit. A 67-year-old man reports sudden palpitations and lightheadedness. He is alert and answers questions appropriately. His pulse is regular at 166/min, blood pressure is 116/72 mm Hg, respiratory rate is 20/min, and oxygen saturation is 96% on room air. He denies chest discomfort and shortness of breath. There are no signs of shock or acute heart failure. A nurse, cardiac monitor, functioning peripheral IV, emergency medications, and a monitor/defibrillator are immediately available.