Effect of intravenous amiodarone in patients with intraventricular conduction disorders

Using His bundle recordings and stimulation techniques, theelectrical effects of amiodarone (5 mg/kg intravenously) wereassessed in 12 patients aged 34–80 years (mean 65) exhibitingin sinus rhythm, intraventricular conduction disturbances. Bundlebranch block was present in 10 patients: left bundle branchblock in three patients, right bundle branch block in three,bilateral bundle branch block in four. All the patients hada long H-V interval (65–80 ms; mean 71). As has been previouslyreported, amiodarone slowed the sinus rate, prolonged the QTinterval, increased the atrial effective refractory period anddepressed A-V nodal conduction. Despite the presence of advancedconduction disturbances within the His-Purkinje system, amiodaronedid not alter the H-V interval in 11 patients and increasedit in one by only 5 ms. Thus, clinically, the use of amiodaronein patients with bundle branch block should be safe.