When the helix unwinds: Lead entrapment during left bundle branch area pacing

Key Teaching Points.

• •Helix unwinding during left bundle branch area pacing may result from excessive torque in intraseptal entrapment.
• •Lead wrinkling and loss of torque are key warning signs.
• •Lead abandonment may be safer than aggressive extraction in selected cases.

Introduction

Left bundle branch area pacing (LBBAP) has emerged as a preferred conduction system pacing (CSP) technique since 2017, owing to its relative ease of implantation, favorable intraventricular synchrony, and low complication rates.^1,2 As with any evolving technique, unintentional complications—particularly rare ones—tend to become apparent only after widespread clinical adoption and increasing procedural volume.

To date, intraprocedural complications associated with conventional stylet-driven leads (SDLs) used in CSP, particularly those involving the helix, have been reported in approximately 0.43%–10.3% of cases.3, 4, 5 Understanding complications related to the use of SDLs in CSP is essential not only for improving procedural safety and lead performance but also for guiding clinical decision-making.

We present a case of a symptomatic patient with atrial fibrillation and slow ventricular response who underwent CSP with an SDL. During an attempt to reposition the lead, a helix unwinding phenomenon occurred. The patient was managed conservatively, with no adverse events observed over a follow-up period of 3 years.

Case report

An 83-year-old man with atrial fibrillation and a slow ventricular response, along with an atypical left bundle branch block and left axis deviation (Supplemental Figure 1), was referred for pacemaker implantation using the LBBAP technique due to dizziness and exertional dyspnea. A previous echocardiogram demonstrated normal left ventricular function, moderate left atrial enlargement, and mild tricuspid regurgitation. A 24-hour Holter monitor revealed 28 pauses lasting 3.4 seconds during waking hours.

A single-chamber system was planned. The patient was monitored using an EPTracer system (Cardiotek, Maastricht, the Netherlands) for surface electrocardiogram and intracardiac electrogram recordings, allowing precise interval measurements. Under conscious sedation and local anesthesia, a pocket was created in the left infraclavicular region. A single left axillary venous access was obtained, and a Selectra 3D 39-55 sheath (Biotronik, Berlin, Germany) was advanced into the right atrium through a 9F vascular sheath using a 0.035-inch J-shaped guidewire.

After positioning in the right atrium, the sheath was advanced approximately 2 cm beyond the tricuspid valve under right anterior oblique fluoroscopic guidance. A Solia S60 lead (Biotronik, Berlin, Germany) was introduced through the sheath, and the His bundle region was mapped and fluoroscopically marked. The sheath was then advanced approximately 1.5 cm inferiorly toward the apex. Pace mapping demonstrated a left bundle branch pattern in V1 with a “W” configuration and an inferior axis.

Fluoroscopy was then switched to the left anterior oblique (LAO) view, and the first attempt at ventricular lead deployment was performed. Clockwise rotation was applied under fluoroscopic guidance while monitoring lead impedance and fixation beats. Wrinkling of the lead insulation and cessation of lead advancement under fluoroscopy were observed, prompting discontinuation of further rotations.

A diagnosis of lead entanglement was made, and counterclockwise rotation was attempted. Despite repeated efforts, the lead remained firmly embedded and could not be disengaged from the septal tissue. The sheath was advanced over the lead in LAO view and anchored against the interventricular septum. A traction–countertraction maneuver was then performed, consisting of continuous counterclockwise rotation of the lead while advancing the sheath against the septum and applying traction in the opposite direction. A small amount of contrast was injected to delineate the septum and better understand the underlying mechanism of entrapment (Supplemental Video 2).

At this point, elongation of the lead helix was observed under fluoroscopy (Figures 1 and 2), and the procedure was interrupted. Given the patient’s advanced age and the plan for single-lead implantation, the risks associated with attempting further extraction—including helix detachment, tricuspid regurgitation, and cardiac perforation—were considered to outweigh the risks of implanting an additional lead. Therefore, the lead was abandoned (Figure 3), and a new venous access was obtained.

Figure 1.

Helix elongation under mechanical stress. Left anterior oblique fluoroscopic view showing elongation of the lead helix during traction with simultaneous sheath advancement against the interventricular septum.

Figure 2.

Distal helix entrapment. Magnified view of the lead helix elongation totally contained within the sheath abutting the interventricular septum.

Figure 3.

Elongated helix compared with functional lead. Right anterior oblique fluoroscopic view showing the abandoned lead with an elongated helix alongside a normally functioning lead in a stable position.

Repeat mapping was performed in the right anterior oblique view, and at a site 2–3 cm more apical, pace mapping demonstrated findings similar to those previously obtained. At this location, lead deployment was performed in the LAO view with clockwise rotation until fixation beats were observed. Further advancement was then halted, and measurements were obtained.

Unipolar pacing demonstrated correction of the left bundle branch block and normalization of the QRS axis, with a QR morphology in V1, transition in V3, RS morphology in lead II, positive morphology in augmented vector left, and negative morphology in augmented vector right (Figure 4). The stimulus-to-peak R-wave interval in V6 was 64 milliseconds, the interpeak R–R′ interval between V6 and V1 was 39 milliseconds, and the QRS duration was 110 milliseconds. The lead was left in this position (Supplemental Video 3).

Figure 4.

Left bundle branch capture during unipolar pacing. Final 25 mm/s electrocardiogram demonstrating left bundle branch block correction consistent with left bundle branch area pacing.

Echocardiography performed immediately after the procedure and before discharge showed no pericardial effusion. The patient has been followed for 3 years and 6 months without evidence of mechanical complications related to the abandoned lead, including tricuspid regurgitation.

Discussion

Damage to the lead helix associated with LBBAP procedures is heterogeneously described in the literature, with reported rates ranging from 0.43% to 10.3%.^4,5 Such complications are expected, as these leads were not originally designed for deep septal implantation. The “entanglement effect” is a relatively common phenomenon involving helix-related complications and occurs when endocardial tissue or chordal structures become wrapped around the helix. The operator typically recognized this phenomenon as proximal lead body wrinkling and spiraling, reflecting impaired torque transmission to the distal tip of the lead.⁶ In such situations, attempts at septal penetration should be promptly discontinued, and the lead should be gently withdrawn using counterclockwise rotation before a new implantation attempt is made.⁷

When an entrapped lead is encountered, it is necessary to weigh how far counterclockwise rotation combined with gentle traction on the lead—while applying counter-traction with the sheath anchored in the septum—should be pursued. More severe complications, such as disconnection of the helix from the lead body,⁸ may occur, and the decision to abandon the lead must be carefully weighed against the potential for successful extraction.⁹ In the present case, it was demonstrated that even with a disrupted helix, lead abandonment followed by implantation of a new lead was safe, with favorable outcomes over a follow-up period of 3 years and 6 months.

Another concern after lead abandonment is the possibility of inadequate conduction system capture. Although LBBAP can be achieved within a broad septal myocardial region, excessively close lead positioning may increase the risk of septal erosion, whereas a more apical position may fail to engage the conduction system and potentially increase the risk of pacing-induced cardiomyopathy.¹⁰ In our case, direct evidence of left bundle branch capture was not observed; however, indirect intraprocedural findings suggested at least deep left ventricular septal engagement consistent with LBBAP. Additionally, transthoracic echocardiography performed 3 years after implantation demonstrated preserved left ventricular ejection fraction, normal ventricular dimensions, and symptomatic improvement, further supporting effective physiological pacing.

Application of radiofrequency (RF) energy using a unipolar electrocautery pen connected to the proximal IS-1 pin (40 W for 3 seconds in cut mode) has been described as a potential strategy to disengage an entrapped helix.¹¹ In previously reported cases, RF application facilitated lead removal with subsequent counterclockwise rotation. However, the potential benefits of this technique must be balanced against the risk of injury to the conduction system and adjacent septal coronary vessels, particularly when the depth of lead entrapment is uncertain.

In a retrospective series of 36 patients with heart failure and reduced ejection fraction undergoing cardiac resynchronization therapy with LBBAP using lumenless leads, septal “electrosection” was performed by delivering unipolar RF energy through the proximal IS-1 pin (mean 27 W, range 20–40 W) for 2.6 ± 2.2 seconds to facilitate lead penetration through septal fibrosis. The technique was feasible, enabling successful lead deployment within the conduction system region. Non-sustained ventricular tachycardia occurred in 92% of patients and was limited to the period of RF delivery. However, fast ventricular tachycardia occurred in 8% of cases, including 1 episode requiring defibrillation. Importantly, pacing leads were not designed for RF current delivery, and the long-term effects on lead insulation, conductors, and the steroid-eluting helix remain unknown.¹²

Helix unwinding due to entanglement may represent an underreported complication of LBBAP. Increased awareness is important not only to guide safe extraction strategies but also to inform future improvements in lead design aimed at reducing the risk of entanglement. The discussion of this complication and the dissemination of validated management strategies may help guide the selection of the most appropriate approach for a given patient. In light of current knowledge, factors such as patient age, frailty, number of existing leads, and clinical reserve should be considered when determining the optimal management strategy in cases of helix unwinding due to entanglement.

Conclusion

In frail patients with few or no previously implanted leads, abandoning a lead exhibiting helix unwinding due to entanglement after an attempted gentle extraction appears to be a safe and reasonable strategy. This approach should be carefully weighed against the potential risks associated with more aggressive extraction maneuvers, including cardiac tamponade and structural disruption with separation of the helix from the lead body.

Declaration of Generative AI and AI-Assisted Technologies in the Writing Process

During the preparation of this work the authors used ChatGPT (OpenAI) exclusively for English language editing and grammatical refinement. After using this tool, the authors critically reviewed all content and take full responsibility for the accuracy and integrity of the manuscript.

Funding Sources

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Disclosures

The authors have no conflicts of interest to disclose.

Appendix. Supplementary Data

Supplementary Figure.