Unusual QRS Wave Forms Associated with Permanent Pacemakers

Abstract

Electrocardiograms from 86 patients with permanent pacemakers were reviewed to assess the frequency of unusual QRS configurations associated with properly placed pacemaker catheters. All nine patients with epicardial pacemaker wires had the expected QRS configuration, suggesting that the contralateral ventricle was depolarized last. Electrocardiograms from 71 of 77 patients with transvenous pacemakers showed the expected left bundle branch block type configuration. Six patients had unexpected QRS morphology, manifested either as typical right-bundle branch block morphology or as a prominent R wave or RsR’ pattern in lead V 1 . Clinical evaluation including lateral chest x-ray film findings revealed no evidence of catheter malposition in these six patients, and two with appropriate catheter position confirmed by direct visualization. These results suggest that unusual QRS configurations as described are not uncommonly associated with permanent transvenous pacemakers, and need not always imply inappropriate catheter position. Possible mechanisms of the unusual QRS configurations are discussed.