BACKGROUND: Nonselective His-bundle pacing (nsHBp), nonselective left bundle branch pacing (nsLBBp), and left ventricular septal myocardial pacing (LVSP) are recognized as physiological pacing techniques. OBJECTIVE: The purpose of this study was to compare differences in ventricular depolarization between these techniques using ultra-high-frequency electrocardiography (UHF-ECG). METHODS: In patients with bradycardia, nsHBp, nsLBBp (confirmed concomitant left bundle branch [LBB] and myocardial capture), and LVSP (pacing in left ventricular [LV] septal position without proven LBB capture) were performed. Timings of ventricular activations in precordial leads were displayed using UHF-ECG, and electrical dyssynchrony (e-DYS) was calculated as the difference between the first and last activation. Duration of local depolarization (Vd) was determined as width of the UHF-QRS complex at 50% of its amplitude. RESULTS: In 68 patients, data were collected during nsLBBp (35), LVSP (96), and nsHBp (55). nsLBBp resulted in larger e-DYS than did LVSP and nsHBp [- 24 ms (-28;-19) vs -12 ms (-16;-9) vs 10 ms (7;14), respectively; P <.001]. nsLBBp produced similar values of Vd in leads V5-V8 (36-43 ms vs 38-43 ms; P = NS in all leads) but longer Vd in leads V1-V4 (47-59 ms vs 41-44 ms; P <.05) as nsHBp. LVSP caused prolonged Vd in leads V1-V8 compared to nsHBp and longer Vd in leads V5-V8 compared to nsLBBp (44-51 ms vs 36-43 ms; P <.05) regardless of R-wave peak time in lead V5 or QRS morphology in lead V1 present during LVSP. CONCLUSION: nslbbp preserves physiological LV depolarization but increases interventricular electrical dyssynchrony. LV lateral wall depolarization during LVSP is prolonged, but interventricular synchrony is preserved.

1st Department of Cardiology Interventional Electrocardiology and Hypertension Jagiellonian University Medical College Krakow Poland

Cardiocenter 3rd Faculty of Medicine Charles University and University Hospital Kralovske Vinohrady Prague Czech Republic

Department of Anesthesia and Intensive Care Charles University and University Hospital Kralovske Vinohrady Prague Czech Republic

Department of Cardiology Cardiovascular Research Institute Maastricht Maastricht University Medical Center Maastricht the Netherlands

Department of Physiology Cardiovascular Research Institute Maastricht Maastricht University Medical Center Maastricht the Netherlands

Institute of Scientific Instruments the Czech Academy of Sciences Brno Czech Republic

Institute of Scientific Instruments the Czech Academy of Sciences Brno Czech Republic; Brno University of Technology Faculty of Electrical Engineering and Communication Department of Biomedical Engineering Technická 12 Brno Czech Republic

International Clinical Research Center St Anne's University Hospital Brno Czech Republic

Comment In

Heart Rhythm. 2021 Aug;18(8):1290-1291. doi: 10.1016/j.hrthm.2021.05.013. PubMed

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