Unintentional Septal Arterial Entry During Left Bundle Branch Area Pacing

Abstract

Background

Left bundle branch area pacing (LBBAP) is increasingly adopted as a physiological pacing strategy. Deep septal lead deployment, however, may occasionally result in unexpected vascular staining.

Case Summary

A 70-year-old woman with advanced atrioventricular block and preserved ejection fraction underwent LBBAP. During contrast injection to assess septal lead depth, unexpected opacification of the left anterior descending artery and a septal perforator branch occurred, suggesting inadvertent vascular entry. The lead was promptly repositioned more proximally, achieving optimal electrical parameters. The patient remained asymptomatic, and follow-up echocardiography confirmed preserved ventricular function without pericardial effusion or hematoma.

Discussion

To our knowledge, this is the first report providing direct angiographic visualization of coronary opacification during LBBAP, highlighting the importance of septal vascular anatomy and imaging guidance.

Take-Home Messages

Inadvertent vascular staining during LBBAP is rare and usually benign when promptly recognized. Angiographic contrast injection is useful to confirm lead position and detect unintended vascular entry.

Visual Summary

Visual Summary.

Unexpected Arterial Opacification During LBBAP

Left bundle branch area pacing (LBBAP) is a novel pacing technique that preserves ventricular synchrony and reduces the risk of pacing-induced cardiomyopathy, particularly in patients with high expected ventricular pacing burden.¹ However, deep lead placement within the interventricular septum may occasionally lead to unexpected findings. Previous reports have described septal hematoma or staining as potential consequences of deep septal lead placement (Table 1). However, to date, no direct angiographic documentation of inadvertent vascular entry during LBBAP has been provided.

Take-Home Messages

• •Inadvertent vascular staining during LBBAP may occur due to entry into small septal perforators, but it is usually benign and self-limiting when promptly recognized.
• •Angiographic contrast injection can be a valuable tool to confirm septal lead position and identify unintended vascular entry, reinforcing the importance of careful fluoroscopic monitoring during the procedure.

Table 1.

Reported Vascular Complications of Left Bundle Branch Area Pacing

First Author	Complication	Site/Mechanism	Useful Projection/Imaging	Management
Trivedi et al2 Zheng et al3 Del Castillo et al4	Interventricular septal hematoma	Septal vessel injury during deep lead penetration	Angiography, transthoracic echocardiogram, TC	Conservative, monitoring. Treatment by covered stent.
De Pooter et al5 Baszko et al6	Septal coronary artery fistula	Septal perforator → LAD entry/communication	Angiography, transthoracic echocardiogram	Conservative, monitoring. Closing abnormal vascular connections with coils.
Ferrari et al7	Extrinsic compression of LAD	Extrinsic compression by the helix of the ventricular lead causing a significant decrease in flow	Angiography, transthoracic echocardiogram	Lead repositioning.
Ponnusamy et al8	Coronary artery spasm	Trauma to septal artery	Angiography, ECG	Lead repositioning.

Exemplary published cases of vascular complications during left bundle branch area pacing, with mechanisms, imaging modalities, and management strategies.

ECG = electrocardiogram; LAD = left anterior descending artery; TC = computed tomography.

Case Description

A 70-year-old woman with a history of hypertension presented with advanced atrioventricular block. She had no other significant cardiac history. Baseline echocardiography revealed a left ventricular ejection fraction of 52%. Given an anticipated pacing burden >20%, LBBAP was selected.

Venous access was obtained via fluoroscopically guided puncture of the left axillary vein, and a Medtronic SelectSecure 3,830 lead was delivered using a C315HIS (Medtronic) sheath. Septal mapping was performed by pacing the right ventricular septum and observing a W pattern in lead V₁ with a discordant pattern in leads II and III. The lead was advanced with approximately 5 clockwise rotations penetrating about 8 mm into the interventricular septum until the notch from the nadir of the QRS interval in V₁ ascended and evolved into a terminal R-wave.

To assess septal penetration depth, contrast injection was performed in the right anterior oblique projection. Unexpectedly, this revealed opacification of the left anterior descending artery and a septal perforator branch, indicating inadvertent vascular entry of the pacing lead (Video 1, Figure 1).

Figure 1.

Contrast Injection During Left Bundle Branch Area Pacing

The arrows indicate inadvertent opacification of a septal perforator branch of the left anterior descending artery.

The lead was promptly unscrewed and repositioned in a more proximal septal location. Final electrical parameters were satisfactory: paced right bundle branch block morphology, paced V₆ R-wave peak time 70 milliseconds, sensing 10 mV, threshold 1.2 V at 0.4 milliseconds, and impedance 900 Ω.

The patient remained asymptomatic. Transthoracic echocardiography performed postprocedure showed no pericardial effusion or septal hematoma (Figure 2). Follow-up echocardiography at 1 and 3 months confirmed preserved left ventricular function and stable lead performance.

Figure 2.

Septal Lead Visualization With No Effusion or Hematoma

(A) Subcostal 4-chamber view and (B) apical 4-chamber view are shown. The arrows indicate the pacing lead within the interventricular septum. No pericardial effusion or septal hematoma is observed.

Discussion

The well-recognized adverse consequences of chronic right ventricular pacing in patients with bradycardia have stimulated the development of more physiological pacing strategies.¹ LBBAP has recently emerged as a promising alternative; however, this novel modality may occasionally be associated with unusual complications, which, although rare, are generally benign and without long-term sequelae.⁹

The interventricular septum is perfused by small perforating branches of the left anterior descending artery, whose number, caliber, and distribution are highly variable across individuals.¹⁰ During deep septal lead deployment, unintentional contact with these vessels may occur, particularly when the lead trajectory is directed too anteriorly. This anatomic variability underscores the importance of careful sheath orientation and avoidance of an excessively anterior trajectory to reduce the risk of vascular entry.

Electrocardiographic cues can assist in achieving optimal lead positioning. In particular, the paced QRS morphology in the inferior leads provides valuable feedback. After confirming that lead II is overall more positive than lead III, the QRS complex in lead II should retain a small positive or negative component, rather than being completely positive or completely negative. Complete negativity of the inferior leads suggests an origin from the inferior septum, whereas complete positivity indicates an anterior septal origin. By contrast, a biphasic positive/negative morphology is consistent with pacing from the mid-septum. Careful interpretation of these patterns can guide operators in avoiding excessively anterior or posterior positioning and, consequently, minimize the risk of interfering with major septal perforating arteries.

When vascular staining is suspected, contrast injection in right anterior oblique and left anterior oblique projections can promptly confirm the diagnosis. Immediate unscrewing and proximal repositioning of the lead is often sufficient to achieve resolution without sequelae, as in the present case. Progression to hemodynamic compromise or the need for invasive management is rare.⁹ Nonetheless, pericardial effusion and septal hematoma, although uncommon, should always be excluded by echocardiography. In most cases, a conservative approach is sufficient because both vascular staining and septal hematomas usually resolve spontaneously over time (Table 1).

Conclusions

To our knowledge, this is the first published case to provide direct angiographic documentation of opacification of the left anterior descending artery and its septal perforator branch during LBBAP. This case illustrates the potential for inadvertent vascular entry during LBBAP and emphasizes the importance of awareness of septal vascular anatomy. Angiographic contrast injection can provide immediate confirmation of such events and guide safe lead repositioning. Although vascular staining or hematoma typically resolve without sequelae, careful procedural technique and prompt recognition are essential to avoid complications.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Appendix

Video 1

Right Anterior Oblique Angiographic Projection During Contrast Injection Through the Delivery Sheath

The video demonstrates inadvertent opacification of the left anterior descending artery and one of its septal perforator branches, illustrating vascular entry during deep septal lead placement in left bundle branch area pacing.