Peri-left bundle branch pacing in a patient with right ventricular pacing-induced cardiomyopathy and atrioventricular infra-Hisian block

A 74-years-old man who received a dual-chamber pacemaker with right ventricular (RV) septal pacing due to advanced atrioventricular (AV) block 6 years ago developed a RV pacing-induced cardiomyopathy with left ventricular ejection fraction (LVEF) of 34% and a left ventricular end-diastolic diameter (LVEDd) of 62 mm. We decided to up-grade the RV pacing to a conduction system pacing. Electrograms obtained from the pacing lead at the His-bundle revealed AV nodal and infra-Hisian AV block (Panel A). Pacing at this site resulted in His capture with a high threshold of 3.0 V/0.5 ms and was considered to be unacceptable. Then a second lead (Model 3830; Medtronic) was added and moved towards the ventricular side using the proximal His bundle pacing (HBP) lead as a marker to achieve peri-left bundle branch pacing (LBBP). Left bundle branch (LBB) potential was recorded regularly before each ventricular electrograms (Panel A). Unipolar tip pacing resulted in a paced QRS of right bundle branch block (RBBB) morphology. Output independent selective and non-selective LBBP was observed with similar stimulus to peak LV activation times (Panel B). There was 1:1 LBB-ventricular conduction at pacing rates of 150 b.p.m. The R-wave amplitude was 19.7 mv. After 6 months of LBBP, LVEF increased to 63%, LVEDd decreased to 46 mm, and New York Heart Association class improved from III to I. The LBB capture threshold was 0.5 V/0.5 ms and R-wave amplitude was 20 mV. The full-length version of this report can be viewed at: https://www.escardio.org/Education/E-Learning/Clinical-cases/Electrophysiology.