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Objective: The aim of this study is to evaluate the deformations of the femoropopliteal (FP) arterial segment due to knee flexion in patients suffering from popliteal aneurysm before and after endovascular treatment (ET).Design and methods: Nine patients were prospectively evaluated. Pre-operative and post-operative computed tomography angiography (CTA) scans were performed on the leg of each patient in both a flexed and extended knee position. The images were employed to reconstruct the FP segment through segmentation and the resulting models were subsequently used to calculate the average diameter, length, and tortuosity of both the superficial femoral artery (SFA) and popliteal artery (PA). Furthermore, the overall PA tortuosity was decomposed into 2 components, ie, antero-posterior and lateral direction.Results: Following knee flexion, both arterial segments experienced shortening in the pre-operative and post-operative phases. Specifically, the SFA was shortened by 3.5% in pre (p<0.001) and 1.21% in post-stenting (p<0.001), while the PA was shortened by 4.8% (p<0.001) and 5.63% (p<0.001), respectively. Tortuosity significantly increased in all considered segments; in particular, in SFA there was a pre-intervention increase of 85.2% (p=0.002) and an increase of 100% post-intervention (p=0.004), whereas in the PA, there was an increase of 128.9% (p<0.001) and 254.8% (p<0.001), respectively. The only diameter variation occurred in the SFA pre-operatively with an increase of 11.9% (p=0.007). Tortuosity decomposition revealed significant differences between the 2 planes during the pre-operative and post-operative phases in both extended and flexed configurations, confirming a change in artery position and geometry due to treatment.Conclusions: Knee flexion induces arterial shortening and increased tortuosity in both the pre- and post-operative configuration. Stent placement does not induce significant geometric differences between pre-treatment and post-treatment. These results seem to indicate that the geometry of the covered stent is not affected by the flexion of the knee joint. Despite this, a more detailed analysis of arterial tortuosity showed a change in artery deformation following treatment.Clinical Impact This study aimed to evaluate femoropopliteal arterial deformations in nine patients with popliteal aneurysm before and after endovascular treatment (ET) during knee flexion, using a standardized protocol for CTA acquisition and analysis. The result can be useful in procedure planning and have shown that the Viabahn stent used can adapt to the morphological variations induced by limb flexion. Consequently, device failure does not be attributed to stent compression but rather to other factors, such as alterations in hemodynamic and biomechanical forces on the implant due to the significant changes in tortuosity observed, or biological causes.

Purpose:To evaluate morphological changes of the femoropopliteal (FP) arteries due to limb flexion in patients undergoing endovascular treatment of popliteal artery aneurysms (PAAs). Materials and Methods:Seven male patients (mean age 68 years) underwent endovascular treatment of PAA with a Viabahn stent-graft between January 2013 and December 2017. During follow-up, one contrast-enhanced computed tomography angiography (CTA) scan of the lower limbs was acquired for each recruited patient. A standardized CTA protocol for acquisitions in both straight-leg and bent-leg positions was used to visualize changes in artery shape due to limb flexion. Three-dimensional reconstruction of the FP segment was performed to compute mean diameter and eccentricity of the vascular lumen and to measure length, tortuosity, and curvature of the vessel centerline in 3 arterial zones: (A) between the origin of the superficial femoral artery and the proximal end of the stent-graft, (B) within the stent-graft, and (C) from the distal end of the stent-graft to the origin of the anterior tibial artery. Results:After limb flexion, all zones of the FP segment foreshortened: 6% in zone A (p=0.001), 4% in zone B (p=0.001), and 8% in zone C (p=0.07), which was the shortest (mean 4.5±3.6 cm compared with 23.8±5.7 cm in zone A and 23.6±7.4 cm in zone B). Tortuosity increased in zone A (mean 0.03 to 0.05, p=0.03), in zone B (0.06 to 0.15, p=0.005), and in zone C (0.027 to 0.031, p=0.1). Mean curvature increased 15% (p=0.05) in zone A, 27% (p=0.005) in zone B, and 95% (p=0.06) in zone C. In all zones, the mean artery diameter and eccentricity were not significantly affected by limb flexion. Conclusion:Limb flexion induces vessel foreshortening and increases mean curvature and tortuosity of the FP segment both within and outside the area of the stent-graft.

Introduction: The study evaluated the Heparin Bioactive Surface (HBS) Viabahn Stent (W.L. Gore & Associates, Flagstaff, Arizona) efficacy in the maintenance or re-establishment of hemodialysis.Materials and methods: Fifty HBS Viabahn stents deployed in 37 consecutive patients with hemodialysis dysfunction from January 2008 to May 2016 were evaluated in a single-institution retrospective review. Outcomes were stent patency intended as primary circuit patency (PP), assisted primary patency (APP), target lesion primary patency (TLPP) and secondary patency (SP). Moreover, the risk factor analysis for hemodialysis dysfunction that required reintervention was performed. A subgroup analysis was conducted to assess patency of Viabahn stent to treat peripheral venous long segment obstruction (LSO).Results: Overall Kaplan-Meyer PPs were 60% at 12 months and 42% at 24 months. Overall TLPP estimated rates were 68% and 49% at 12 and 24 months, respectively. The corresponding SP rates were 85% and 78% at the same period. Estimated PP rates at 12 and 24 months for stent placement after peripheral venous long segment recanalization procedure were 53% and 31%, respectively. Corresponding SP rates were 82% and 68%, respectively. The APP rates were 79% at 12 months and 61% at 24 months. Female sex, access age and thrombosis were associated with reduced primary patency.Conclusions: Considering the high rates of PP, TLPP, APP and SP, Viabahn stents have been proven effective in maintaining or re-establishing the hemodialysis access. Moreover, stent placement after recanalization of LSO of venous out-flow represented a valid approach to rescue a dysfunctional fistula that would otherwise be abandoned.