An electrocardiogram from a patient implanted with a dual-chamber DDD pacemaker showed paced QRS complexes whose morphology and frontal-plane axis were consistent with biventricular stimulation with right ventricular lead located at the apex. However, some electrocardiographic findings were suggestive, rather, of univentricular right apical pacing and sustained ventricular fusion with competing native atrioventricular conduction in the presence of patient's spontaneous QRS showing right bundle branch block plus left anterior hemiblock. Shortening atrioventricular delay with magnet application advanced right ventricle stimulation and prevented the supraventricular impulse to contribute to ventricular depolarization, thereby making clear the mechanism of right v
Full-text is available in PDF file.
© 2017, International Journal of Cardiovascular Practice. This open-access article is available under the Creative Commons Attribution-NonCommercial 4.0 (CC BY-NC 4.0) International License (https://creativecommons.org/licenses/by-nc/4.0/), which allows for the copying and redistribution of the material only for noncommercial purposes, provided that the original work is properly cited.