The vasopressor phenylephrine (Neo-Synephrine) is indicated for paroxysmal supraventricular tachycardia (PSVT). Have there been any studies comparing phenylephrine with adenosine?
—Manuel A. Fonseca, DO, Florence, S.C.

Phenylephrine can be an effective treatment for PSVT. There are several case reports of its use for PSVT in patients with Wolff Parkinson White syndrome, including cases in which the tachycardia was refractory to other treatments. Phenylephrine stimulates the arterial baroreceptors and therefore decreases vagal output. In a study looking at various vagal maneuvers, phenylephrine evoked the greatest increase in vagal tone (Am J Cardiol. 1980;46:655-664). I am not aware of any published studies that have compared phenylephrine with adenosine in this setting.
—Norma M. Keller, MD (109-18)

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