An initial dose of 6 mg is administered through a freely running intravenous catheter as a rapid bolus and flushed in as quickly as possible with intravenous fluids. Administration of adenosine via a peripheral vein results in a delay of five to 10 seconds before any ECG effects can be detected. If the initial 6 mg dose of adenosine is not effective, two subsequent doses of 12 mg each may be given approximately two minutes apart. A dose of 12 mg or less will result in at least transient termination of the tachycardia in more than 90 percent of patients. Pharmacotherapy and vagal maneuvers generally interrupt the tachycardia by causing block in the slow pathway.
Digoxin is sometimes effective.
Beta blockers may be useful when arrhythmia initiation appears to be catecholamine dependent. Although verapamil is effective and may be administered as a single daily dose of 240 mg, its use may be limited by constipation, fatigue, flushing, and edema. Diltiazem may also be effective and is generally better tolerated. Amiodarone is effective but has too many side effects to warrant its use for this curable arrhythmia. Both direct and cryoablative surgical approaches have been employed with high success rates and relatively low morbidity.