[Myocardial refractory changes after single intravenous administration of cordarone (electrophysiologic study of the...

In 29 patients with cardiac arrhythmias, refractory periods (RP) of the atrium, atrioventricular node and ventricle were defined before and after intravenous administration of cordarone in a dose of 5 mg/kg body weight. The effective RP (ERP) of the atrio-ventricular node showed the most profound changes: in 73% of the patients, the increase was 22.8% as compared to the pretreatment value. The most response of atrial RP to cordarone was also an increase of right atrial ERP by an average of 16.5%, FRP, by 13.1% versus the baseline values. The least effect was produced by cordarone on ventricular RP, namely the maximal increase in right ventricular FRP and ERP did not exceed 10%, but these parameters remained unchanged in a third of the patients.