This study was performed to ascertain whether intravenous
amiodarone would revert
supraventricular tachycardias to sinus rhythm, and if so, whether this effect depended upon the underlying mechanism of the
arrhythmia. Fourteen patients were studied. Seven had Wolff-Parkinson-White (
WPW) syndrome, 1 had dual atrioventricular nodal pathways and 1 an
ectopic atrial tachycardia. Five patients had
atrial fibrillation without accessory pathways. An atrial
electrode was inserted to initiate
tachycardias and record the electrogram. If
tachycardias were stable for more than 5 min,
amiodarone (5 mg/kg) diluted with
dextrose saline was infused intravenously over 5 min. Two electrocardiographic leads and the right atrial electrogram were monitored. In 7 patients with
atrial fibrillation (2 with accessory pathways), 6 did not revert to sinus rhythm, 1 reverted only after 1 hr. In 5 cases without accessory pathways the ventricular rate fell 5-10 min after commencing
amiodarone. Four of the 5 patients with
WPW syndrome and re-entrant
tachycardias returned to sinus rhythm within 6 min of commencing the infusion (atrioventricular and ventriculoatrial times increased by 0-38% and 0-14% respectively). (
Tachycardias terminated in the anterograde limb.) Three patients underwent intermittent right atrial stimulation for 1 hr. No
tachycardias could be initiated for 30 min post
amiodarone. The
ectopic atrial tachycardia and that due to dual atrioventricular nodal pathways terminated within 7 and 2 min, respectively, of commencing intravenous
amiodarone. Thus the use of intravenous
amiodarone would be appropriate in the acute management of sustained
supraventricular tachycardias.