Postmortem analysis of encapsulation around long-term ventricular endocardial pacing leads

Objective: To analyze the site and thickness of encapsulation around ventri cular endocardial pacing leads and the extent of tricuspid val re adhesion, from today's perspective, with implications for lead removal and sensor lo cation. Material and Methods: Gross cardiac postmortem analysis was performed in II cases (8 female and 3 male patients; mean age, 78 +/- 7 years). None of th e patients had died because of pacemaker malfunction. The mean implant time was 61 +/- 60 months (range, 4 to 184). Results: The observations ranged from encapsulation only at the tip of the pacing lead to complete encapsulation along the entire length of the pacing lead within the right ventricle, Substantial areas of adhesion at the tric uspid valve apparatus were noted in 7 of the 11 cases (64%). The firmly att ached leads could be removed only by dissection, and in some cases, removal was possible only by damaging the associated structures. No specific optim al site for sensor placement could be identified along the ventricular port ion of the pacing leads; however, the fibrotic response was relatively less prominent in the atrial chamber. Conclusion: Extensive encapsulation is present in most long-term pacemaker leads, which may complicate tend removal, The site and thickness of encapsu lation seem to be highly variable, Tricuspid valve adhesion, which is usual ly underestimated, may be severe. In contrast to earlier reports, our study demonstrates that the extent of fibrotic encapsulation may not be related to the duration since lead implantation. Moreover, we noted no ideal encaps ulation-free site for sensors on the ventricular portion of long-term pacin g leads.