[Effect of the anti-arrhythmia agent ethmozin on the refractory period of the accessory pathway in Wolff-Parkinson-White syndrome].

Sudden onset of atrial fibrillation can be very dangerous in patients with WPW syndrome, because it may result in high ventricular rate. The ventricular rate depends upon the length of the effective refractory period (ERP) of the accessory pathway. It is appropriate, therefore, to test newer antiarrhythmic agents on their effect on the ERP of the accessory bundle. 13 patients underwent the studies. Ethmozin was given intravenously 1 mg/kg body weight. The ERP increased significantly after Ethmozin (p less than 0.05). The increase was more prominent in those patients who had longer basal values of ERP (greater than 300 ms), as compared with the patients with shorter values (less than 300 ms); the latter revealed at most a slight lengthening of the ERP. Ethmozin exerts a favourable effect on the accessory pathway, however, the effectiveness of this substance is insufficient in patients, who are at risk because of a very short ERP.