Paroxysmal supraventricular tachycardia (PSVT) is a sudden-onset tachyarrhythmia that can cause palpitations, chest discomfort, and dyspnea. JAMA Associate Editor David Simel, MD, MHS, discusses the diagnosis and treatment of patients with PSVT with author Paul Zei, MD, of Harvard University. Related Content: Diagnosis and Management of Paroxysmal Supraventricular Tachycardia Modified Valsalva Maneuver (video) Carotid Sinus Massage (video)