Intravenous adenosine in the emergency department management of paroxysmal supraventricular tachycardia.

STUDY PURPOSE: To evaluate the efficacy of adenosine in the treatment of emergency department patients with spontaneous paroxysmal supraventricular tachycardia (PSVT).

DESIGN: An eight-month prospective outcome study.

POPULATION: Patients 16 or more years old with PSVT by surface ECG criteria. Patients were excluded if there was clinical or hemodynamic evidence of hypoperfusion.

MEASUREMENTS: Patient age, sex, PSVT rate, pretreatment blood pressure, history of cardiac disease, chronic drug therapy, and response to IV adenosine.

RESULTS: Twenty-three patients with 27 episodes of suspected PSVT met inclusion criteria. After IV adenosine, two patients were found to have atrial flutter, and one was found to have ventricular tachycardia. Twenty-four episodes of PSVT were diagnosed in the remaining 21 patients. There were eight male and 13 female patients with a mean age of 51 +/- 19 years (range, 16 to 80 years). Sixteen patients related a history of cardiovascular disease. The mean QRS rate during PSVT was 181 +/- 23. Twenty-three of 24 episodes (96%) were converted to sinus rhythm within 20 to 45 seconds of adenosine therapy. However, 13 of 23 of initial conversions (57%) were followed by recurrence of PSVT within five minutes. All 13 recurrences required therapy with other antiarrhythmic drugs for conversion to and maintenance of sinus rhythm. Complications of adenosine were noted in only four patients and were transient and clinically unimportant.

CONCLUSION: IV adenosine effectively terminates PSVT in ED patients with spontaneous PSVT; recurrence of PSVT after adenosine is common in the ED population and should be treated with other antiarrhythmic agents, not repeated doses of adenosine; adenosine is useful in the differential diagnosis of tachyarrhythmias; and doubling the initial dose of adenosine to 12 mg would increase the likelihood of conversion with the first dose.