Recruitment of Complete Right Bundle Branch Block by Permanent Para-Hisian Pacing.

His-bundle pacing has recently emerged as a means to maintain a physiological ventricular activation and eliminate the risk of pacing-induced myopathy associated with traditional right ventricular pacing. With His-bundle pacing, the exact stimulated structure and resulting excitation wavefront may be highly dependent on the pacing output, dimensions of the stimulatory electrodes, and orientation of the cathode and anode relative to the approximated conduction tissue and surrounding myocardium, owing to the juxtaposition of tissues with very different conduction properties. We herein present an 89-year-old woman with an infra-Hisian conduction disease in whom lower output pacing resulted in pure His-bundle pacing, and higher output pacing resulted in para-Hisian pacing that recruited diseased portions of the conduction system, narrowing the QRS complex.