Abstract
Conventional stylet-driven leads with extendable helix can be implanted
successfully for Left Bundle Branch Area Pacing (LBBAP) with a low acute
complication rate. We report 2 cases in which lead repositioning after a
first unsuccessful attempt to LBBAP was associated with fracture of the
helix rotating mechanism and failure to fully extract the pacing lead.
Case description Two patients referred for LBBAP were implanted
with a conventional stylet-driven (SD) lead with an extendable helix
(Biotronik Solia S60, SE & Co, Berlin, Germany) delivered through a
dedicated preshaped sheath (Selectra 3D, Biotronik, limited market
release). Before implantation, the lead was prepared by exposing the
helix. Using the stylet insertion tool, an additional 10 clockwise (CW)
rotations was applied. This pretensioning of the inner coil was
maintained by further pushing the stylet insertion tool onto the
proximal silicon sealing ring of the lead. This maneuver is essential to
maintain the pre-applied torque on the screw extension mechanism and
avoid unwinding of the extendable helix during transseptal screwing of
the lead.1,2 LBBAP was subsequently attempted
following the technique previously described by Huang et
al.3 In both cases, recording of His potential,
mapping of the right ventricular (RV) septal implant site, and screwing
the lead transseptally towards the left side of the interventricular
septum using outer lead body rotations was easy. In patient one, a
narrow paced QRS of 102 ms was obtained but no LBBB capture was clearly
demonstrated and pacing thresholds remained high (2.0 V with a pulse
duration of 1 ms). Therefore, an attempt to reposition the lead was
undertaken. With the stylet fully inserted to the tip of the pacing
lead, counterclockwise (CCW) rotations of the connector pin were first
applied to release tension on the inner coil and retract the exposed
helix. However, the helix failed to retract. An attempt to unscrew the
helix by CCW rotation of the entire lead also remained unsuccessful. The
implanter decided to test lead anchoring by gently pulling on the lead.
This maneuver immediately resulted in the misalignment of the helix.
With further efforts to extract the lead using lead rotations, traction
and counter-traction with the sheath, the helix elongated and finally
abruptly snapped (See Figure 1A). This patient was finally implanted
with a biventricular pacemaker without further complications. Computed
tomography confirmed the deep insertion of the residual helix fragment
into the interventricular septum (See Figure 1B).
LBBAP in patient two was attempted using a similar implantation
technique. As in patient one, no QRS changes indicative of LBBAP were
obtained, and pacing threshold was high (>2.5 V with a
pulse duration of 1 ms). Lead repositioning was attempted by CCW turning
of the outer lead body without fixation of the connector pin. This
maneuver resulted in rupture of the fixation mechanism and the
distortion of the helix (See Figure 2). Further attempts to extract the
lead by CCW turning of the connector pin or outer lead body were
ineffective. The lead was abandoned in the septum and a second lead was
implanted in the right ventricular apex.