The use of vagal stimulation to halt supraventricular tachycardia is a standard medical therapy. Two methods of vagal stimulation, the Valsalva maneuver and carotid sinus massage, have been used in urgent situations. Lim and associates compared the success rates of these two methods of vagal stimulation in terminating spontaneous supraventricular tachycardia in an emergency department setting.

All patients with supraventricular tachycardia whose rhythm did not reveal obvious atrial flutter, atrial fibrillation or sinus tachycardia and who were hemodynamically stable were randomly assigned to undergo either the Valsalva maneuver or carotid sinus massage. Those who had carotid sinus massage were further randomized to undergo either right or left carotid sinus massage first. If the tachycardia was not terminated by the first method of vagal stimulation, the alternative maneuver was attempted. The Valsalva maneuver was performed by blowing into a mouthpiece with sustained resistance for 30 seconds or more. Carotid sinus massage was performed in the standard manner for 10 seconds with the head tilted to the opposite side. If both methods of vagal stimulation failed, patients were managed with pharmacotherapy or cardioversion. All patients in whom rhythm conversion occurred were monitored by continuous electrocardiography for an additional two hours. If there was no recurrence during the observation period, the patient was discharged with an outpatient appointment.

A total of 148 episodes of supraventricular tachycardia occurred among 126 patients. The success rate as the initial vagal technique was 19.4 percent (12 of 62 patients) for the Valsalva maneuver and 10.5 percent (nine of 86 patients) for carotid sinus massage. The difference was not statistically significant. The success rate with right carotid sinus massage was the same as that for left carotid sinus massage. In some cases, the alternative maneuver was successful when the initial attempt failed. There was no significant difference in success rates between the two techniques as alternative maneuvers.

Three patients whose rhythm converted with the Valsalva maneuver had recurrence during observation. One of the patients whose rhythm converted with carotid sinus massage had recurrence during observation. Reported complications of carotid sinus massage include ventricular fibrillation, monoplegia, hemiplegia and cervicomediastinal hematoma. The only reported complication of the Valsalva maneuver is hypotension from straining.

The authors conclude that vagal maneuvers are safe and efficacious in ending about 25 percent of spontaneous supraventricular tachycardias if performed properly. Some evidence indicates that the Valsalva maneuver is more efficacious in men and that carotid sinus massage is more efficacious in older patients.