Transseptal Transition Patterns During Left Bundle Branch Area Lead Implantation.

BACKGROUND

Continuous deep septal pacing and signal recording during implantation of left bundle branch pacing (LBBP) lead enables to monitor beat-to-beat changes of electrocardiogram (ECG) and myocardial current of injury (COI) as the lead crosses the septum.

OBJECTIVES

This study aimed to characterize patterns of continuous QRS, ST-T, and COI change for monitoring of the lead depth and instantaneous determination of the obtained capture type (LBBP vs left ventricular septal pacing [LVSP]).

METHODS

The ECG and COI during lead implantation were scrutinized for sudden changes of V6 R-wave peak time, V1 initial and terminal R-wave amplitude, V3-V6 R-wave amplitude, repolarization pattern and S-wave amplitude in I, V5-V6, and COI drop. The sudden and gradual transition patterns were diagnosed depending on the presence or absence of the above beat-to-beat ECG phenomena, respectively.

RESULTS

A total of 212 pacemaker recipients were analyzed; LBBP and LVSP were obtained in 77.4% and 22.6%, respectively. There were 4.7 ± 2.1 and 0.2 ± 0.6 beat-to-beat phenomena in LBBP and LVSP patients, respectively. The sudden transition pattern, recognized in 80.7%, had sensitivity and specificity for LBBP diagnosis of 98.8% and 81.2%, respectively. A sudden drop of COI (29.4 ± 8.5 mV to 12.8 ± 4.9 mV) was observed in 53.9% patients (LBBP was simultaneously obtained in 92.7%).

CONCLUSIONS

Capture of left bundle branch during lead penetration is a beat-to-beat phenomenon. Two transseptal transition patterns were identified: 1) sudden, which is typical for obtaining LBBP; and 2) gradual, which is typical for obtaining LVSP. A sudden COI drop, a very observable phenomenon, also identified reaching the left subendocardial area.