Canadian Journal of Cardiology



      His pacing (His-P) and left bundle branch pacing (LBB-P) are new modalities to obtain a more physiologic pacing (PP); they require however, new tools and new skills. We describe a simplified method to achieve LBB-P, using only a 12-lead EKG to guide lead deployment; mid septum (not too anterior close to His area or LV summit and not too posterior is sought).

      Methods and Results

      From our cohort of 211 physiologic pacing attempts (2019-2022), we extracted all patients (pts) with detailed available 12 lead EKG during implant. His-P and LOT/HOT-CRT pts were excluded. We reviewed the presence of two features: inferior lead discordance (at least one lead from II, III or aVF with different polarity compared to the others) or isodiphasic QRS at the beginning of 3830 Medtronic lead screwing, and the presence of typical LBB capture morphology after final position. Leads were screwed until LBB-P morphology was obtained or bipolar and unipolar pacing produced the same QRS pacing morphology. A total of 161 pts tracings were analyzed. Pts were 56% males; median age was 79 +/- 8.5 years. Indications were: SSS 25%, AV block 41% (including 8 post TAVR), Pacemaker induced cardiomyopathy (PIMC) 27% and AV node ablation in 7%. Success (defined as a QRS shorter than 140ms and a LVAT shorter than 90ms, or 20% reduction in QRS width) was achieved in 93.2% of pts. Procedural time (pts in-out) was 88min (+/- 37min). Perforation was confirmed when aVL has the same polarity of aVR and there was a monophasic R wave in V1 (mostly when anterior orientation or apical sites were tempted). Basal versus apical positions were easily differentiated looking at normal progression of R waves in precordial leads.


      Localizing the middle of the septum is easy, before start screwing, just looking at polarity of inferior leads, better outcomes are obtained starting at the middle of the septum (more LBB-P morphology achieved with acceptable failure rates). The anterior region seldom obtains a LBB-P morphology, but it is the second place to try as QRS are almost always the thinnest obtained.
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