Development of a Benchtop Model for Investigating Flow Characteristics in Chronic Venous Obstruction

Chronic venous obstruction (CVO) is a prevalent but often underdiagnosed condition affecting the deep veins of the lower extremities. CVO arises from venous stasis caused by compression, valve damage, proximal vein disease, or post-thrombotic changes. This leads to the formation of collagen-rich lesions that impair blood flow, thicken vessel walls, and elevate pressure. While arterial remodeling is well studied, the impact of altered flow in the venous system due to disease remains less understood. This study aims to address the gap in knowledge of venous flow conditions by developing clinically relevant benchtop models to investigate the effects of variable inflow conditions in CVO. Benchtop models were constructed using polydimethylsiloxane and a silicone rubber, with the iliofemoral vein as the target (diseased) segment, the popliteal, great saphenous, and deep femoral as the inflow veins, and the common iliac vein as the outflow segment. One healthy model and nine diseased models were developed with varying sizes of CVO lesions in the iliofemoral vein. Ultrasound studies were conducted in each of the models to assess the impact of different inflow conditions on velocities within and around the lesion. In one model, particle-tracking was used to visualize flow patterns around the lesion. Doppler ultrasound measurements showed that as the cross-sectional area and length of the lesion increased, average velocities were higher within and proximal to the lesion compared to distal regions. Lesions with greater cross-sectional area exhibited less proximal recovery, with velocity remaining elevated rather than returning to baseline levels, an effect that was more pronounced at higher inflow rates. Color Doppler studies revealed a flow eddy at the lesion inlets, consistent with clinical observations in patients with sudden stenosis. Particle-tracking further supported these findings. These results suggest that the degree of occlusion (i.e., cross-sectional area) influences flow dynamics more than the length of the lesion. Additionally, this study demonstrates the feasibility of replicating clinically observed venous flow patterns within a benchtop setting. The ultrasound-compatible models developed provide greater anatomical relevance with the inclusion of multiple source veins, making them more accurate for acquiring flow measurements and valuable for future venous disease research.