Atrio-ventricular block on Wolff Parkinson White's syndrome: a rare association

Complete atrioventricular block (AV block) associated with an accessory pathway is a rare phenomenon. We report the case of a third degree AV block paired with a Wolff Parkinson White (WPW) syndrome in a 91-year-old patient. The electrocardiogram (ECG) on admission showed a Mobitz type II AV block alternating with a third degree block on a wide-QRS ventricular rhythm beating at 35 cycles per minute. The patient urgently underwent the implantation of a single-lead pacemaker. The post-implantation ECG revealed a Kent accessory pathway on the left posteroseptal site. The existence of a complete AV block in the presence of an accessory pathway implies a more or less permanent blockage of atrial depolarization, both through the normal conduction tissue and the accessory pathway.