Extendable / retractable helix pacing lead for LBBAP:
Compared to LL leads, SD pacing leads benefit from better support, stability and steerability during transseptal screwing for LBBAP and allow for a more customized implant approach in the setting of anatomic variations. However, careful pre-tensioning of the inner coil and locking of the connector pin is required before use (See Figure 3A and 3B). As transseptal screwing is associated with more distal grip and recoil of the outer lead body and helix, inadequate preparation of the lead may result in unwanted retraction of the helix during CW outer lead body rotations. For the same reason, full helix retraction is critical before attempting lead removal by CCW turning of the outer lead body. As illustrated by our second case, insufficient locking of the connector pin to the outer lead body during this maneuver may further extend the helix and eventually fracture the helix rotating mechanism. (Fig 3C) As illustrated by our first case, any premature traction on the lead with the helix incompletely retracted may result in helix misalignment or deformation. Although both implanters were experienced with tissue conduction pacing, they were relatively naïve to the use of an SD lead for LBBAP. In his recent paper, De Pooter et al. reported an average of 2 attempts per patient to reach the left side of the ventricular septum. No issues during lead repositioning were reported. With experience, the following suggestions can be made before unscrewing SD leads in LBBAP: 1) Verify full insertion of the stylet to the tip of the lead and obtain maximum support before retraction by maintaining the delivery sheath firmly against the RV septum 2) Much more than the minimum number of connector pin rotations to expose the helix are usually necessary to fully retract the helix 3) If the helix can not be retracted, avoid CCW rotation of the outer lead body without validated fixation of the connector pin by means of the stylet insertion tool (Fig 2D). 4) After removal and before repositioning, carefully inspect the screwing mechanism.