Evaluation and initial treatment of supraventricular tachycardia

A 24-year-old woman presents to the emergency department with the sole symptom of "a racing heart," which began abruptly while she was eating dinner. She reports having had prior episodes of palpitations that resolved spontaneously. In the emergency room, her blood pressure is 84/60 mm Hg. An electrocardiogram (ECG) reveals a regular narrow-complex tachycardia at a rate of 190 beats per minute without clear atrial activity (P waves). How should this case be managed?