3.3 Continuous lead stylet pacing to guide LBBAP
In the feasibility-group, all patients demonstrated selective (14/20
patients, 70%) or non-selective (6/20 patients, 30%) LBB capture at
the end of the continuous transseptal-screwing maneuver. This was
associated with a short and stable mean pLVAT of 73ms [IQR 68-80.5]
and short median paced QRS duration of 120ms [IQR 112-152ms]. The
screwing maneuver duration was highly variable and ranged from 7.8
seconds to 27 seconds. During lead deployment the impedance evolution
was recorded for off-line analysis. However, in 5 patients the recording
quality was insufficient, and those impedance data were discarded.
As the lead progressed from the RV septum to the LV sub-endocardial
region, a small increase followed by progressive decrease of the
unipolar pacing impedance was noted in most patients (with a mean
impedance difference 143 ± 87 Ohm) ending with a discrete increase just
before reaching final position (Figure 4). The impedance at final
position ranged from 340 to 728 Ohm. Two patients showed an unexpected
progressive increase in impedance from 590 to 715 Ohm and from 405 to
674 Ohm. This was associated with a suboptimal paced QRS morphology
without qR pattern in precordial ECG lead V1 in both patients, but with
narrow QRS (120ms) and pLVAT (74ms) in the first patient and with clear
LBB potential on local EGM and narrow QRS and PLVAT (126ms and 71ms
respectively) in the second patient. No helix retraction was observed in
these 2 patients.