title: A histological and mechanical analysis of the cardiac lead-tissue interface: implications for lead extraction.
abstract: The major risks of pacemaker and implantable cardioverter defibrillator extraction are attributable to the fibrotic tissue that encases them in situ, yet little is known about the cellular and functional properties of this response. In the present research, we performed a histological and mechanical analysis of human tissue collected from the lead-tissue interface to better understand this process and provide insights for the improvement of lead design and extraction. The lead-tissue interface consisted of a thin cellular layer underlying a smooth, acellular surface, followed by a circumferentially organized collagen-rich matrix. 51.8±4.9% of cells were myofibroblasts via immunohistochemistry, with these cells displaying a similar circumferential organization. Upon mechanical testing, samples exhibited a triphasic force-displacement response consisting of a toe region during initial tensioning, a linear elastic region and a yield and failure region. Mean fracture load was 5.6±2.1N, and mean circumferential stress at failure was 9.5±4.1MPa. While the low cellularity and fibrotic composition of tissue observed herein is consistent with a foreign body reaction to an implanted material, the significant myofibroblast response provides a mechanical explanation for the contractile forces complicating extractions. Moreover, the tensile properties of this tissue suggest the feasibility of circumferential mechanical tissue disruption, similar to balloon angioplasty devices, as a novel approach to assist with lead extraction.
authors.affiliation: Department of Surgery, Stanford University Medical Center, Stanford, CA, USA.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Rennert
authors.affiliation: Department of Surgery, Stanford University Medical Center, Stanford, CA, USA.
authors.forename: Kristine
authors.initials: K
authors.lastname: Rustad
authors.affiliation: Department of Surgery, Stanford University Medical Center, Stanford, CA, USA.
authors.forename: Kemal
authors.initials: K
authors.lastname: Levi
authors.affiliation: Division of Cardiovascular Medicine, Department of Internal Medicine, Stanford University Medical Center, Stanford, CA, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Harwood
authors.affiliation: Department of Surgery, Stanford University Medical Center, Stanford, CA, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Sorkin
authors.affiliation: Department of Surgery, Stanford University Medical Center, Stanford, CA, USA.
authors.forename: Victor W
authors.initials: VW
authors.lastname: Wong
authors.affiliation: Division of Cardiovascular Medicine, Department of Internal Medicine, Stanford University Medical Center, Stanford, CA, USA.
authors.forename: Amin
authors.initials: A
authors.lastname: Al-Ahmad
authors.affiliation: Division of Cardiovascular Medicine, Department of Internal Medicine, Stanford University Medical Center, Stanford, CA, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Zei
authors.affiliation: Division of Cardiology, Department of Internal Medicine, UCSF, San Francisco, CA, USA.
authors.forename: Henry
authors.initials: H
authors.lastname: Hsia
authors.affiliation: Department of Cardiothoracic Surgery, Stanford University Medical Center, Stanford, CA, USA.
authors.forename: Ramin E
authors.initials: RE
authors.lastname: Beygui
authors.affiliation: Division of Cardiovascular Medicine, Department of Internal Medicine, Stanford University Medical Center, Stanford, CA, USA.
authors.forename: Linda
authors.initials: L
authors.lastname: Norton
authors.affiliation: Division of Cardiovascular Medicine, Department of Internal Medicine, Stanford University Medical Center, Stanford, CA, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Wang
authors.affiliation: Department of Surgery, Stanford University Medical Center, Stanford, CA, USA. Electronic address: ggurtner@stanford.edu.
authors.forename: Geoffrey C
authors.initials: GC
authors.lastname: Gurtner
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002921:Cicatrix / Q000473:pathology; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D004566:Electrodes; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology* / Q000648:ultrastructure; D058628:Myofibroblasts / Q000473:pathology
keywords: Fibrosis; Pacemaker; Stress analysis; Tensile test