Effect of intravenous amiodarone in patients with intraventricular conduction disorders

Using His bundle recordings and stimulation techniques, the electrical effects of amiodarone (5 mg/kg intravenously) were assessed in 12 patients aged 34–80 years (mean 65) exhibiting in sinus rhythm, intraventricular conduction disturbances. Bundle branch block was present in 10 patients: left bundle branch block in three patients, right bundle branch block in three, bilateral bundle branch block in four. All the patients had a long H-V interval (65–80 ms; mean 71). As has been previously reported, amiodarone slowed the sinus rate, prolonged the QT interval, increased the atrial effective refractory period and depressed A-V nodal conduction. Despite the presence of advanced conduction disturbances within the His-Purkinje system, amiodarone did not alter the H-V interval in 11 patients and increased it in one by only 5 ms. Thus, clinically, the use of amiodarone in patients with bundle branch block should be safe.