Empty vein ablation (EVA) technique: an in-vivo animal model to assess the effects of sclerosing agent concentration and wall contact time on intima and media tunicae structure

Background: Sclerotherapy is a cornerstone of the treatment of chronic venous disease, despite some technical aspects (e.g., sclerosant liquid agent concentration [SLAC] and contact time between sclerosant agent and vein wall [ctSA/VW]) to maximize outcomes remain an unsolved problem and a source of debate. An innovative three-balloon catheter has been developed to allow sclerotherapy in empty vein conditions (Empty Vein Ablation technique, EVA), revolutionizing the definition of SLAC and ctSA/VW. Aim of this experimental study is to analyze EVA effects on intima and media vessel tunicae using different SLAC and ctSA/VW in an in-vivo animal model. Methods: Two adult sheep were treated by EVA using jugular and common iliac vein axes (eight vein segments). Different SLAC (polidocanol 0.5% or 1%) and different ctSA/VW (3 or 5 minutes) were combined for testing residual circumferential intima percentage and media thickness after EVA. Results: Intact circumferential residual intima after the treatment was 21.3±4.9%, 18.2±7.4%, 15.7±2.4% and 8.9±2.0% using 0.5% (3 min), 0.5% (5 min), 1% (3 min) and 1% (5 min), respectively (R2=0.945; control sample: 97.6%). Media thickness after the treatment was 121.6±35.3 µm, 110.9±7.8 µm, 96.1±30.4 µm and 79.1±34.1 µm using 0.5% (3 min), 0.5% (5 min), 1% (3 min) and 1% (5 min), respectively (R2=0.990; control sample 125.7 µm). No significant modifications were detected analyzing the adventitia in all samples. Conclusions: EVA proved to be effective in venous wall destruction even with a very low SLAC and ctSA/VW (0.5% in 3 minutes), in quite large caliber veins. Direct comparisons with foam/liquid sclerotherapy should be done to confirm therapeutic effectiveness of these results, despite EVA has provided a maximized and controlled SA/VW contact time and ratio.