Capturing the His-Purkinje system is not possible from conventional right ventricular apical and nonapical pacing sites.

INTRODUCTION:Direct His bundle capture may negate ventricular electrical dyssynchrony induced by right ventricular (RV) apical pacing. We sought to evaluate if direct His bundle pacing is possible with conventional pacemaker lead implantation at various sites in the RV. METHODS:Consecutive patients underwent RV pacing using standard implantable active fixation pacing leads in a random order in the RV outflow tract, middle RV, and RV apex at stimulation threshold and at increasing voltages of 2.5, 5, 7.5, and 10 volts (V). At each location, QRS width and morphology on 12-lead electrocardiograph (ECG) were compared in sinus and paced rhythm at the different voltages. RESULTS:Twelve patients underwent a total of 2,160 paced QRS measurements. Progressive increases in stimulation voltage did not change QRS morphology or duration regardless of site of pacing (RV outflow tract, middle RV, and RV apex) in any of the 12 ECG leads. In addition, apart from the stimulation threshold between the RV outflow tract and RV apex, there was no statistically significant difference in QRS duration between the three pacing sites. CONCLUSION:In patients with a baseline normal QRS duration, none of the three conventional RV pacing sites were able to produce QRS narrowing and capture the His-Purkinje system. Furthermore, based on paced QRS duration as an indirect surrogate of electrical LV dyssynchrony, there was no clear advantage of one pacing site over another.