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Abstract
Background Flow diverters (FDs) have become a standard treatment option for intracranial aneurysms. However, major drawbacks include the need for dual-antiplatelet therapy after implant and delayed complete occlusion of the aneurysm, which occurs when new tissue growth excludes the aneurysm from the parent artery. Biomimetic surface modifications such as the phosphorylcholine polymer (Shield surface modification) represent major advances in reducing thrombogenicity of these devices. However, there are concerns that this modification may delay endothelial growth over devices as they heal. We sought to investigate the longitudinal healing of Pipeline Shield, Vantage Shield, and bare metal Pipeline Flex devices in vivo hypothesizing that there would be no differences between the modified and bare devices.
Methods Bare metal Pipeline, Pipeline Shield, and Vantage with Shield devices were implanted in the common carotid arteries of 10 rabbits (2 in the left, 1 in the right). Following implant, and at 5, 10, 15, and 30 days, the devices were imaged with high-frequency optical coherence tomography (HF-OCT) and catheter angiography to evaluate placement and tissue growth. At 30 days the devices were explanted, and their endothelial growth was assessed with scanning electron microscopy (SEM) at 5 locations along their length using a semi-quantitative score from 0 (no endothelial tissue growth) to 5 (completely matured tissue coverage). An automated method was used to measure the average tissue growth thickness (ATGT) along the device based on the HF-OCT images (figure 1).
Results Endothelialization was first apparent after 5 days. Although the Vantage devices were noted to have relatively greater ATGT compared to the other devices at the 5-day time point, no statistical difference was found (p=0.055). At the remaining timepoints, there was no difference, or even trend of a difference in ATGT between device types. On SEM, all devices scored at least a 4 or 5 at every location, and no differences were found between median or mean scores for each of the three devices.
Conclusion The lack of significant difference in ATGT between the devices indicates that the Shield modification does not delay or alter the rate or thickness of tissue growth on FDs in vivo (figure 1). SEM evaluation of FDs shows near complete endothelial coverage at 30 days, that does not differ for device type or surface modification. These findings suggest that in vivo, neither the Shield surface modification nor the Vantage device design altered the longitudinal healing of the flow diverter.
Disclosures C. Zoppo: None. M. Epshtein: None. R. King: None. M. Gounis: 1; C; NIH, the United States – Israel Binational Science Foundation, Anaconda, ApicBio, Arsenal Medical, Axovant, Balt, Cerenovus, Ceretrieve, CereVasc LLC, Cook Medical, Galaxy Therapeutics, Gentuity, Gilb. 2; C; Alembic LLC, Astrocyte Pharmaceuticals, BendIt Technologies, Cerenovus, Imperative Care, Jacob’s Institute, Medtronic Neurovascular, Mivi Neurosciences, phenox GMbH, Q’Apel, Route 92 Medical, Scientia. 4; C; Imperative Care, InNeuroCo, Galaxy Therapeutics, Neurogami and Synchron. V. Anagnostakou: None.