Image-guided deployment and monitoring of a novel tungsten nanoparticleâ€"infused radiopaque absorbable inferior vena cava filter in pigs

The use of absorbable inferior vena cava filters (IVCFs) constructed with poly-p-dioxanone (PPDO) eliminates risks and complications associated with the use of retrievable metallic filters. Radiopacity of radiolucent PPDO IVCFs can be improved with the incorporation of nanoparticles (NPs) made of high-atomic number materials such as gold and bismuth. In this study, we focused on incorporating tungsten NPs (WNPs), along with polyhydroxybutyrate (PHB), polycaprolactone (PCL), and polyvinylpyrrolidone (PVP) polymers to increase the surface adsorption of the WNPs. We compared the imaging properties of WNPs with single-polymer PHB (W-P) and WNPs with polymer blends consisting of PHB, PCL, and PVP (W-PB). Our in vitro analyses using PPDO sutures showed enhanced radiopacity with either W-P or W-PB coating, without compromising the inherent physico-mechanical properties of the PPDO sutures. We observed a more sustained release of WNPs from W-PB-coated sutures than W-P-coated sutures. We successfully deployed W-P- and W-PB-coated IVCFs into the inferior vena cava of pig models, with monitoring by fluoroscopy. At the time of deployment, W-PB-coated IVCFs showed a 2-fold increase in radiopacity compared to W-P-coated IVCFs. Longitudinal monitoring of in vivo IVCFs over a 12-week period showed a drastic decrease in radiopacity at week 3 for both filters. Results of this study highlight the utility of NPs and polymers for enhancing radiopacity of medical devices; however, different methods of incorporating NPs and polymers can still be explored to improve the efficacy, safety, and quality of absorbable IVCFs.