Transient complete atrioventricular block following radiofrequency ablation of left free wall accessory pathway

We report the case of a forty-six-year-old female with symptomatic WPW syndrome. The accessory pathway was located on the left free wall, for which ablation was attempted from the retrograde aortic approach. The ablation catheter was positioned at the appropriate site on the mitral anulus. A single radiofrequency energy application resulted in complete AV block with no escape rhythm, necessitating ventricular pacing. The AV conduction soon resumed with no evidence of pre-excitation. This phenomenon was thought to be related to trauma to the AV node during catheter entry in to the left ventricle.