The antiarrhythmic efficacy and safety of intravenous
amiodarone were evaluated in 13 patients with recurrent sustained
ventricular tachycardia. All patients had been refractory to at least three prior antiarrhythmic agents (mean, 3.3 per patient), and 11 had multiple direct current
cardioversions. Intravenous
amiodarone suppressed sustained
tachycardia in seven patients; the concurrent use of
procainamide resulted in suppression in two additional patients.
Ventricular tachycardia recurred in three patients, two within 2 hours of initiation of
amiodarone. Adverse effects necessitated the discontinuation of
amiodarone in one patient because of significant hemodynamic deterioration. The use of intravenous
amiodarone was associated with a significant fall in heart rate and cardiac output. Plasma
amiodarone levels were high after initial bolus loading but declined to low or less than therapeutic levels within 60 minutes. Thus although we found intravenous
amiodarone to be effective in the short-term treatment of refractory
ventricular tachycardia, administration of
amiodarone can be associated with significant hemodynamic deterioration. The dosing protocol used should be modified to a lower initial bolus and a higher early maintenance infusion rate.