Assessment of Biocompatibility of the Multilayer Flow Modulator with Differing Thread Designs

Background: The Multilayer Flow Modulator (MFM) (Cardiatis, Isnes, Belgium) is a self-expandable mesh of cobalt alloy wires used for the treatment of aortic aneurysms.The impact of design thread count and duration of implantation on the biocompatibility of the MFM in porcine animal models was assessed in this study.Methods: Eight mini-piglets received 26 MFM devices (12 with 56 threads, 14 with 80-96 threads) in the iliac, carotid, and renal arteries.Animals were sacrificed and specimens explanted at 1, 3, and 6 months, at which time histological and ultrastructural analyses were carried out.Results: The MFM was successfully deployed in 25 of the 26 implanted cases.The 56 thread devices were well tolerated locally and yielded fewer signs of inflammation and neo intimal hyperplasia.Percentage stenosis was 16.9% ± 5.1% for the 56 thread devices versus 33.4% ± 10.2% for the 80-96 thread devices (p=0.001) at 3 months, and 21.7% ± 9.9% for the 56 thread devices versus 33.6% ± 12.4% for the 80-96 thread devices (p=0.004) at 6 months.The 5 devices selected for SEM examination were well deployed, integrated into the vessel wall and endothelialized, and had patent side branches.Conclusions: No significant stenosis formation or inflammatory response was recorded in any of the implanted animals.The 80-96 thread devices elicited a greater intra-arterial response than the 56 thread devices, although the values for both groups remained within the normal range for stented carotid, renal, or iliac arteries.Further preclinical and clinical studies will extend assessment of the long-term safety and effectiveness of the MFM.