Radial Support Force: A Key Player in Vena Cava Neointimal Hyperplasia

Area of Science:

• Biomaterials science
• Vascular biology
• Medical device engineering

Background:

• Neointimal hyperplasia (NIH) complicates inferior vena cava filter (IVCF) retrieval and can damage the vena cava.
• Mechanical properties of IVCFs, crucial for understanding NIH, are not well-documented by manufacturers.
• This study investigates the link between IVCF radial support force (RSF) and NIH, including inflammatory responses.

Purpose of the Study:

• To evaluate the correlation between radial support force (RSF) exerted by IVCFs and the development of neointimal hyperplasia (NIH).
• To assess the relationship between RSF and the release of tumor necrosis factor-alpha (TNF-α) in the context of IVCF implantation.
• To provide mechanical property data for IVCFs to better predict and manage post-retrieval complications.

Main Methods:

• In vitro analysis of RSF from IVCF struts across varying inferior vena cava (IVC) diameters.
• In vivo implantation of IVCFs in Bama swine for three weeks to assess NIH thickness and TNF-α content.
• Statistical analysis including Student's t-test, chi-square test, and regression analyses to determine correlations.

Main Results:

• A linear relationship was observed between oversizing ratio (OR) and RSF (R² = 0.718, p < 0.001).
• NIH thickness showed a U-shaped dose-response relationship with increased RSF (R² = 0.630, p < 0.001).
• Elevated TNF-α levels correlated significantly with increased RSF (R² = 0.777, p < 0.001), particularly at smaller caval diameters.

Conclusions:

• IVCF oversizing directly influences RSF, with larger oversizing ratios leading to higher forces.
• Increased RSF is a significant factor contributing to greater NIH thickness and inflammatory responses.
• Understanding the mechanical forces of IVCFs is critical for mitigating complications like NIH and improving retrieval outcomes.