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.