Cyclic Tachycardia and Hypotension

A 60-year-old man presented to the emergency department with multiple episodes of palpitations, dyspnea, diaphoresis, and lightheadedness. One episode was associated with a syncopal event 1 week before admission. His symptoms recurred during hospitalization, at which time telemetry documented a narrow complex tachycardia at 160 bpm accompanied by hypotension. During the next 24 hours, he developed sinus tachycardia and hypotension followed by normal sinus rhythm and hypertension, which alternated in a cyclic pattern with a periodicity of ≈8 minutes (Figure …