Generator Pocket Adhesions of Cardiac Leads: Classification and Correlation with Transvenous Lead Extraction Results

Computed tomography predictors of increased transvenous lead extraction difficulty

BACKGROUND

The ability of computed tomography (CT) characteristics to predict the difficulty of transvenous lead extraction (TLE) is an evolving subject.

OBJECTIVE

To identify CT characteristics associated with increased TLE difficulty.

METHODS

All consecutive patients undergoing TLE at the University of California San Diego from January 2018 to February 2022 were analyzed, utilizing the UC San Diego Lead Extraction Registry. Patients underwent cardiac-gated chest CT scans with intravenous contrast; all scans were reviewed by a single radiologist. Lead extraction was performed per standard institutional protocol with the initial use of a laser sheath and crossover to a mechanical sheath as needed. Multivariable linear and logistic regression analyses were performed to identify predictors of individual lead-removal fluoroscopy time and mechanical sheath use, as markers of extraction difficulty.

RESULTS

A total of 343 patients were analyzed. The mean age of the study population was 63.8 ± 15.4 years; 71% were male. The mean lead dwell-in duration was 8.6 ± 5.7 years. In multivariable linear regression analysis, venous occlusion detected on CT was independently associated with higher individual lead-removal fluoroscopy time (p = 0.004), when adjusting for clinical characteristics such as lead dwell time. In multivariable logistic regression analysis, calcification and venous occlusion were independently associated with a higher need for mechanical sheath use during TLE (odds ratio:5.08, p < 0.001, 95% CI: 2.54-10.46) and (odds ratio:3.72, p < 0.001, 95% CI: 1.89-7.35), respectively.

CONCLUSION

In patients undergoing TLE, venous occlusion identified by chest CT is associated with increased fluoroscopy time. Patients with lead-associated calcification or venous occlusion detected by chest CT are each five and three times more likely to require crossover from laser to a mechanical sheath.

Effects of envelopes on cardiac implantable electronic device pocket healing: A head-to-head preclinical evaluation

BACKGROUND

The healing response to cardiac implantable electronic device (CIED) implantation results in inflammation that can lead to fibrous pocket formation, which may disrupt pocket healing or complicate future interventions.

OBJECTIVE

The purpose of this study was to assess CIED pocket healing with use of the second-generation TYRX absorbable antibacterial envelope (T2), the next-generation (NG) TYRX absorbable antibacterial envelope under development, and the CanGaroo® extracellular matrix envelope (ECM) compared to no envelope.

METHODS

A total of 110 CIEDs were implanted in an ovine model, either with (T2, NG, or ECM) or without envelopes. Histopathologic and morphometric analyses were completed at several timepoints after implant (3 days, 7 days, 4 weeks, 12 weeks, 24 weeks). An independent pathologist completed a blinded histopathology assessment of the pockets.

RESULTS

TYRX (T2/NG) pockets showed similar inflammatory and healing profiles to controls with more rapid provisional matrix formation compared to controls and ECM. ECM pockets exhibited increased acute (3 and 7 days) and chronic (24 weeks) inflammation. T2/NG had almost complete (T2) or complete (NG) absorption by week 12. ECM remained present at week 24 and was associated with significantly thicker capsules (ECM 0.80 ± 0.14 mm; NG 0.37 ± 0.10 mm; control 0.56 ± 0.17 mm).

CONCLUSION

Compared to ECM, pockets with TYRX showed less inflammation, more rapid provisional matrix formation, faster absorption, and thinner capsules. TYRX pockets had low inflammation comparable to controls with accelerated provisional matrix deposition and tissue adhesion. The healing response to CIEDs used with TYRX fosters the formation of a well-healed pocket, which may bring patient benefit beyond its proven infection reduction.

Radiographic predictors of failure of simple manual traction of transvenous implantable cardioverter-defibrillator leads: a single-center experience

BACKGROUND

Extraction of the implantable cardioverter-defibrillator (ICD) leads could be a difficult procedure due to fibrous tissue around the lead and anatomical variations. In this report, we present our experience in the radiographic predictors of failure of simple manual traction (SMT) in patients with dual-coil ICD requiring lead extraction (LE).

METHODS

Between January 2017 and February 2021, 103 leads were removed in 65 consecutive patients; 65 (63.1%) were dual-coil ICD leads, 22 (21.4%) were atrial, and 16 (15.5%) were coronary sinus leads. Patient-based and procedural data were collected and analyzed retrospectively. Clinical and procedural characteristics were compared and radiographic predictors of failure of SMT of ICD leads were assessed. Projected anteroposterior (AP) lead tortuosity was measured and lead slack score was estimated on chest X-ray (CXR).

RESULTS

Simple manual traction failed in 27 (42%) of the ICD leads. Ottawa slack score (odds ratio [OR] 2.368, 95% CI [1.261-4.447]; P = 0.007), AP lead tortuosity > 1.10 (OR 7.477, 95% CI [1.718-35.542]; P = 0.007), and number of previous interventions (OR 6.016, 95% CI [1.184-30.557]; P < 0.030) were found to be independently related to the failure of SMT. Receiver-operator characteristic curve analysis yielded an AP lead tortuosity cutoff value of > 1.10 for predicting the failure of SMT. The area under the curve was 0.744; the 95% confidence interval (CI) was 0.617 to 0.871 (P = 0.001), with a sensitivity of 63% and a specificity of 73%.

CONCLUSION

Simple manual traction success in our study varied based on radiographic lead-related parameters. Before planning the procedure, increased AP lead tortuosity in vasculature and higher lead slack score can be easily determined on CXR and may be associated with more fibrous adherences, the complexity of the LE, and failure of SMT.

Pocket histology at cardiac implantable electronic device replacement: What's new?

BACKGROUND

Repeated procedures involving the cardiac implantable electronic device (CIED) pocket increase the infection risk, and the extent of pocket adhesions may prolong the procedure time. Few data on pocket histology at the time of CIED replacement are available.

OBJECTIVE

The purpose of this study was to describe CIED pocket histology in a cohort of patients undergoing CIED replacement or upgrade.

METHODS

All consecutive patients undergoing CIED replacement or upgrade at our center between November 2019 and May 2020 were enrolled. Subclinical pocket infection was ruled out by physical inspection and laboratory parameters before the procedure. Pocket tissue specimens from the anterior and posterior pockets were obtained intraoperatively. A systematic histological analysis of capsular thickness, fibrous connective tissue, neovascularization, inflammation, and calcifications was performed.

RESULTS

Thirty patients (6 women, 20%) were enrolled. The mean capsular thickness was 0.8 ± 0.3 mm in the anterior wall and 1.1 ± 0.4 mm in the posterior wall. Subcapsular fibrosis was mild and multifocal in the anterior wall and moderate and focal in the posterior wall. Neovascularization was focal in most cases, and vessel remodeling mainly involved the tunica media. Chronic inflammation was usually mild and nongranulomatous, and in a quarter of cases, subacute exudative fibrous inflammation was detected in the posterior pocket wall.

CONCLUSION

The CIED pocket is a histopathologically dynamic environment, given the coexistence of both a subacute foreign body response and fibrous tissue growth, implying continuous remodeling due to an injury-repair mechanism. Strategies to interact with foreign body response might minimize inflammatory pocket activity, especially device encapsulation by tight fibrous tissue, and possibly complications related to repeated CIED procedures.

Preclinical evaluation of a third-generation absorbable antibacterial envelope

BACKGROUND

The TYRX (Medtronic) absorbable antibacterial envelope has been shown to stabilize implantable cardiac devices and reduce infection. A third-generation envelope was developed to reduce surface roughness with a redesigned multifilament mesh and enhanced form factor but identical polymer coating and antibiotic concentrations as the currently available second-generation envelope.

OBJECTIVE

The purpose of this study was to compare drug elution, bacterial challenge efficacy, stabilization, and absorption of second- vs third-generation envelopes.

METHODS

Antibiotic elution was assessed in vitro and in vivo. For efficacy against gram-positive/gram-negative bacteria, 40 rabbits underwent device insertions with or without third-generation envelopes. For stabilization (migration, rotation), 5 sheep were implanted with 6 devices each in second- or third-generation envelopes. Prespecified acceptance criteria were <83-mm migration and <90° rotation. Absorption was assessed via gross pathology.

RESULTS

Elution curves were equivalent (similarity factors ≥50 per Food and Drug Administration guidance). Third-generation envelopes eluted antibiotics above minimal inhibitory concentration (MIC) in vivo at 2 hours postimplant through 7 days, consistent with second-generation envelopes. Bacterial challenge showed reductions (P <.05) in infection with second- and third-generation envelopes. Device migration was 5.5 ± 3.5 mm (third-generation) vs 9. 9 ±7.9 mm (second-generation) (P <.05). Device rotation was 18.9° ± 11.4° (third-generation) vs 17.6° ± 15.1° (second-generation) and did not differ (P = .79). Gross pathology confirmed the absence of luminal mesh remainders and no differences in peridevice fibrosis at 9 or 12 weeks.

CONCLUSION

The third-generation TYRX absorbable antibacterial envelope demonstrated equivalent preclinical performance to the second-generation envelope. Antibiotic elution curves were similar, elution was above MIC for 7 days, infections were reduced compared to no envelope, and acceptance criteria for migration, rotation, and absorption were met.

Reduced fibrous capsule elastic fibers from biologic ECM-enveloped CIEDs in minipigs, supported with a novel compression mechanics model

BACKGROUND

Fibrous capsules (Fb) in response to cardiovascular implantable electronic devices (CIEDs), including a pacemaker (P) system, can produce patient discomfort and difficulties in revision surgery due partially to their increased compressive strength, previously linked to elevated tissue fibers.

OBJECTIVE

A preliminary study to quantify structural proteins, determine if biologic extracellular matrix-enveloped CIEDs (PECM) caused differential Fb properties, and to implement a realistic mechanical model.

METHODS

Retrieved Fb (-P and -PECM) from minipigs were subjected to biomechanical (shear oscillation and uniaxial compression) and histological (collagen I and elastin) analyses.

RESULTS

Fb-PECM showed significant decreases compared to Fb-P in: low strain-loss modulus (390 vs. 541 Pa) across angular frequencies, high strain-compressive elastic modulus (1043 vs. 2042 kPa), and elastic fiber content (1.92 vs. 3.15 μg/mg tissue). Decreases in elastin were particularly noted closer to the implant's surface (Fb-PECM = 71% vs. Fb-P = 143% relative to dermal elastin at mid-tangential sections) and verified with a solid mechanics hyperelasticity with direction-dependent fiber viscoelasticity compression simulation (r2 ≥ 98.9%).

CONCLUSIONS

The biologic envelope composed of decellularized porcine small intestine submucosa ECM for CIEDs promoted fibrous tissues with less elastic fibers. Novel compression modeling analyses directly correlated this singular reduction to more desirable subcutaneous tissue mechanics.

Risk Profiles and Outcomes of Patients Receiving Cardiovascular Implantable Electronic Devices With and Without Antibacterial Envelopes

Background

The increasing use of cardiac implantable electronic devices (CIEDs) in a growing patient population has led to an even greater increase in CIED infection rates. Antibacterial CIED envelopes are often used as part of an infection risk-reduction strategy. However, best practices for when to use an envelope and which envelope to choose remain to be elucidated.

Methods

In this retrospective study, the records of 455 patients undergoing CIED implantation by a single surgeon were reviewed to identify trends in envelope use and outcomes after implantation through 12 months of follow-up. Of these patients, 165 were managed with a biologic antibacterial CIED envelope (CanGaroo®, Aziyo Biologics, Inc., Silver Spring, MD), 219 with a non-biologic envelope (Tyrx®, Medtronic Inc., Monmouth Junction, NJ), and 71 with no envelope.

Results

Most patients had two or more infection risk factors (77.9% with any envelope vs. 52.1% with no envelope; P < 0.001). Factors significantly associated with the use of an envelope included the history of heart failure, systemic anticoagulant use, the use of high-power or more complex devices, and reoperations. The overall rate of adverse events was 9.2% (n = 42). Rates of infection and hematoma were 1.8% and 2.6%, respectively. A decision tree is proposed that may aid clinical decision-making when considering CIED envelope usage.

Conclusions

There were no significant differences between groups in overall or individual adverse event rates. These data provide insight into real-world clinical decisions regarding the use of CIED envelopes and support the use of antibiotic-eluting CIED envelopes to limit infection risk in high-risk patients.

Looking for Lead Adhesions While Planning for Transvenous Lead Extraction

The first implantable pacemaker was placed in the 1958, ushering in a new frontier of cardiovascular medicine. This article is protected by copyright. All rights reserved.

Characterization of Lead Adherence Using Intravascular Ultrasound to Assess Difficulty of Transvenous Lead Extraction

Background:

Clinical factors associated with development of intravascular lead adherence (ILA) are unreliable predictors. Because vascular injury in the superior vena cava-right atrium during transvenous lead extraction is more likely to occur in segments with higher degrees of ILA, reliable and accurate assessment of ILA is warranted. We hypothesized that intravascular ultrasound (IVUS) could accurately visualize and quantify ILA and degree of ILA correlates with transvenous lead extraction difficulty.

Methods:

Serial imaging of leads occurred before transvenous lead extraction using IVUS. ILA areas were classified as high or low grade. Degree of extraction difficulty was assessed using 2 metrics and correlated with ILA grade. Lead extraction difficulty was calculated for each patient and compared with IVUS findings.

Results:

One hundred fifty-eight vascular segments in 60 patients were analyzed: 141 (89%) low grade versus 17 (11%) high grade. Median extraction time (low=0 versus high grade=97 seconds, P <0.001) and median laser pulsations delivered (low=0 versus high grade=5852, P <0.001) were significantly higher in high-grade segments. Most patients with low lead extraction difficulty score had low ILA grades. Eighty-six percentage of patients with high lead extraction difficulty score had low IVUS grade, and the degree of transvenous lead extraction difficulty was similar to patients with low IVUS grades and lead extraction difficulty scores.

Conclusions:

IVUS is a feasible imaging modality that may be useful in characterizing ILA in the superior vena cava-right atrium region. An ILA grading system using imaging correlates with extraction difficulty. Most patients with clinical factors associated with higher extraction difficulty may exhibit lower ILA and extraction difficulty based on IVUS imaging.

Graphic Abstract:

A graphic abstract is available for this article.

Microengineered biosynthesized cellulose as anti-fibrotic in vivo protection for cardiac implantable electronic devices

Upon cardiac implantable electronic device (CIED) exchange, upgrade, or revision surgery patients are exposed to a considerable risk of adverse events. The presence of firm fibrotic tissue endangers these procedures. Leads can be damaged in the attempt of freeing them from fibrotic tissue. Hematoma can form as result of capsulectomy, pocket debridement and leads dissection. Due to the increasing number of CIED exchange, upgrade and revision surgeries, the incidence of related complications is expected to rise in the near future.The aim of the study was to evaluate the feasibility, safety, and performance of a rationally micro-engineered non-resorbable biosynthesized cellulose (BC) membrane as conformal wrapping protection around CIED implants. Protective membranes were generated by means of a recently established method to transfer on-demand microscale geometries onto the surface of BC. A chronic minipig animal model was selected to investigate the performance of the BC anti-fibrotic protection, directly measured as reduction of fibrotic tissue formation. Sixteen (n = 16) animals received each one BC coated pacemaker (PMC) and one native pacemaker (BI) at equivalent anatomical sites. BC protective layers were juxtaposed around pacemakers through a fast and well-repeatable procedure. Explants were performed at 3 and 12 months after implantation. Endpoint analysis showed that the BC protective layers were 100% integer, with no sign of chemical or mechanical degradation and appeared as a thin layer of white-tan material, adherent to the surrounding thin fibrous capsule, from which it could be peeled off by gently pulling with forceps. The protective effect of micro-engineered BC yielded an average thickness reduction of 66% of the fibrotic tissue thickness generated around PMC, as compared to that measured around the naked counterpart (i.e. the BI). When protected by in BC, both the generator and the proximal parts of the leads were completely free from fibrotic tissue. The insertion of an anti-adhesive, non-resorbable and well-tolerated BC interface between the implant and the surrounding tissue in the surgical pocket significantly reduced the formation of fibrotic tissue, ensuring an easy access to the device pocket, and thus creating the conditions for simplified CIED revision surgeries.

A micron-scale surface topography design reducing cell adhesion to implanted materials

The micron-scale surface topography of implanted materials represents a complementary pathway, independent of the material biochemical properties, regulating the process of biological recognition by cells which mediate the inflammatory response to foreign bodies. Here we explore a rational design of surface modifications in micron range to optimize a topography comprised of a symmetrical array of hexagonal pits interfering with focal adhesion establishment and maturation. When implemented on silicones and hydrogels in vitro, the anti-adhesive topography significantly reduces the adhesion of macrophages and fibroblasts and their activation toward effectors of fibrosis. In addition, long-term interaction of the cells with anti-adhesive topographies markedly hampers cell proliferation, correlating the physical inhibition of adhesion and complete spreading with the natural progress of the cell cycle. This solution for reduction in cell adhesion can be directly integrated on the outer surface of silicone implants, as well as an additive protective conformal microstructured biocellulose layer for materials that cannot be directly microstructured. Moreover, the original geometry imposed during manufacturing of the microstructured biocellulose membranes are fully retained upon in vivo exposure, suggesting a long lasting performance of these topographical features after implantation.

Neointimal fibrotic lead encapsulation - Clinical challenges and demands for implantable cardiac electronic devices

Every tenth patient with a cardiac pacemaker or implantable cardioverter-defibrillator implanted is expected to have at least one lead problem in his lifetime. However, transvenous leads are often difficult to remove due to thrombotic obstruction or extensive neointimal fibrotic ingrowth. Despite its clinical significance, knowledge on lead-induced vascular fibrosis and neointimal lead encapsulation is sparse. Although leadless pacemakers are already available, their clinical operating range is limited. Therefore, lead/tissue interactions must be further improved in order to improve lead removals in particular. The published data on the coherences and issues related to lead associated vascular fibrosis and neointimal lead encapsulation are reviewed and discussed in this paper.

[Practical aspects of pacemaker and ICD-lead extractions]

Special tools for lead removal enables transvenous lead extractions without cardiac exposure. The risk of fatal complications during extraction of long-term implanted leads requires detailed knowledge and trained physicians. In addition to patients’ age and gender, individual extraction risk factors are access and time since implantation, lead position, kind and number of leads. Locking stylets to anchor the lead within the lumen are necessary in all extraction procedures while the use of external sheaths is optional. Higher risk of cardiac or central vein perforation during lead mobilisation with external laser sheaths has to be respected, and these tools should be used with strong indication only. In cases of high risk, lead explantation with an open heart procedure should be considered as an alternative.