Background

Leadless pacemakers (LPs) have proven safe and effective, but device revisions remain necessary. Either replacing the LP or implanting a new adjacent LP is feasible. Replacement seems more appealing, but encapsulation and tissue adhesions may hamper the safety and efficacy of LP retrieval.

Objective

We determined the incidence and cellular characteristics of tissue adherent to retrieved LPs and the potential implications for end-of-life strategy.

Methods

All 15 consecutive successful Nanostim LP retrievals in a tertiary center were included. We assessed the histopathology of adherent tissue and obtained clinical characteristics.

Results

Adherent tissue was present in 14 of 15 retrievals (93%; median implantation duration 36 months; range 0–96 months). The tissue consisted of fibrosis (n = 2), fibrosis and thrombus (n = 9), or thrombus only (n = 3). In short-term retrievals (<1 year), mostly fresh thrombi without fibrosis were seen. In later retrievals, the tissue consisted of fibrosis often with organizing or lytic thrombi. Fibrosis showed different stages of organization, notably early fibrocellular and later fibrosclerotic tissue. Inflammatory cells were seen (n = 4) without signs of infection. Tricuspid valve material was retrieved in 1 patient after 36 months, resulting in increased tricuspid regurgitation.

Conclusion

Our results suggest that fibrosis and thrombus adherent to LPs are common and encapsulate the LP as seen in transvenous pacemakers. LPs may adhere to the tricuspid valve or subvalvular apparatus affecting retrieval safety. The end-of-life strategy should be optimized by incorporating risk stratification for excessive fibrotic encapsulation and adhesions.

中文翻译：

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与回收的无引线起搏器相连的组织：与植入时间和并发症相关的组织成分的组织病理学评估

背景

无引线起搏器 (LP) 已被证明是安全有效的，但仍需要对设备进行修改。更换 LP 或植入新的相邻 LP 都是可行的。替换似乎更有吸引力，但封装和组织粘连可能会妨碍 LP 检索的安全性和有效性。

客观的

我们确定了与回收的 LP 粘附的组织的发生率和细胞特征，以及对生命终结策略的潜在影响。

方法

包括在三级中心的所有 15 次连续成功的 Nanostim LP 检索。我们评估了粘附组织的组织病理学并获得了临床特征。

结果

15 次取回中有 14 次存在粘附组织（93%；中位植入持续时间 36 个月；范围 0-96 个月）。组织由纤维化（n = 2）、纤维化和血栓（n = 9）或仅血栓（n = 3）组成。在短期取回（<1 年）中，大多数是没有纤维化的新鲜血栓。在后来的取回中，组织由纤维化组成，通常伴有组织性或溶解性血栓。纤维化表现出不同的组织阶段，特别是早期的纤维细胞组织和晚期的纤维硬化组织。看到炎症细胞（n = 4），没有感染迹象。1 名患者在 36 个月后取出三尖瓣材料，导致三尖瓣反流增加。

结论

我们的研究结果表明，纤维化和血栓附着在 LP 上很常见，并且包裹着 LP，如经静脉起搏器中所见。LP 可能粘附在三尖瓣或瓣下装置上，影响取出安全。应通过对过度纤维化包裹和粘连进行风险分层来优化临终策略。