The initial pharmacologic therapy of choice in this stable patient (refer to Q 87) is

Vagotonic maneuvers such as carotid massage or the Valsalva maneuver could ceainly be tried first. If these are unsuccessful, adenosine, with its excellent safety profile and extremely sho half-life, is the drug of choice for supraventricular tachycardia at an initial dose of 6 mg. Dosage can be repeated if necessary a few minutes later at 12 mg. Verapamil is the next alternative; if the initial dose of 2.5 to 5 mg does not yield conversion, one or two additional boluses 10 min apa can be used. Diltiazem and digoxin may be useful in rate control and conversion, but have a much slower onset of action.