Pocket healing and bioabsorption dynamics of a novel absorbable antibiotic CIED envelope: preclinical evidence beyond antimicrobial efficacy
M Ziacchi, M Biffi, R D Schaller, A BreitensteinAbstract
Background
Beyond infection prevention, the long-term success of cardiac implantable electronic devices (CIEDs) depends on healthy pocket healing and device stability. The novel absorbable antibiotic envelope is designed to provide both antimicrobial protection and enhanced tissue compatibility through optimal engineering of implant materials.
Objective
To perform a preclinical evaluation of pocket healing, capsule formation, antibiotic elution, and antibacterial efficacy of the novel envelope (test) compared with the standard absorbable envelope (control) in combination with CIED implantation.
Methods
In vivo, 18 non-functional CIEDs were implanted in an ovine model and analyzed at 2, 9, and 13 weeks for pocket healing, device migration, and histopathology according to ISO 10993-6. Capsule thickness, inflammation, and envelope absorption were quantified. Envelope drapability was assessed per ISO 9073-7. In vitro, bacterial challenge tests were performed against Methicillin resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Enterococcus faecium, Escherichia coli, Pseudomonas aeruginosa, and Acetobacter baumannii. Antibiotic elution was evaluated in a rabbit model by measuring residual drug content and serum concentrations of rifampin and minocycline over the course of 7 days.
Results
Pocket capsules matured normally in both groups: the test thickened from 0.5 ± 0.1 mm at 2 weeks to 1.3 ± 0.3 mm at 9 weeks, then remodeled to 1.1 ± 0.4 mm at 13 weeks; the control reached 1.5 ± 0.5 mm. Inflammation remained mild and both envelopes were fully absorbed by week 13. Device migration stayed < 2 cm without complications. The test envelope demonstrated superior form-fitting properties, conforming up to 60° of curvature versus 15° for the control. The test envelope showed complete bacterial eradication (6–7 log reduction, p<0.05) for all tested strains. Antibiotic elution was sustained for at least 7 days with low systemic exposure (peak 129–151 ng/mL), whereas the control showed a rapid burst release completed by day 7.
Conclusion
The novel envelope promotes a mature, stable pocket with favorable bio absorption comparable to the current standard. In addition, it ensures complete antibacterial activity and sustained antibiotic release. These findings highlight potential procedural and long-term benefits extending beyond infection prevention.