Factors Influencing The Coverage Of The Contralateral Iliac Vein Opening By Iliac Vein Stents

Purpose: To evaluate the factors affecting the covered area of the contralateral iliac vein opening by stents that protruded into the inferior vena cava in patients with iliac vein compression syndrome(IVCS).Materials and methods : We retrospectively analyzed the data of patients with IVCS who underwent iliac vein stent placement in our hospital from September 1,2018 to October 1,2020.The age,sex,type of stent implanted,and diameter of the stent were recorded.Three-dimensional rotational angiography and 3D image reconstruction of the iliac vein were used to measure the length of the stent in the inferior vena cava and measure the angles between the affected iliac vein and the inferior vena cava in the anteroposterior and lateral views.Image J was used to measure the area of the contralateral iliac vein opening and its covered area on the 3D images and calculate the percentage of the area that was covered.Univariate and multivariate linear regression were used to analyze the factors that influenced the area of the contralateral iliac vein opening covered by the iliac vein stent.Results:A total of 64 patients with iliac vein compression syndrome were included.Univariate analysis indicated that the length of the stent tip in the inferior vena cava,the angle between the affected iliac vein and the inferior vena cava in the lateral view,and the type of stent were all statistically significant factors of opening coverage(F1=72.109,F2=26.498,F3=9.537,all P<0.05).Sex,stent diameter,and the angle between the affected iliac vein and the inferior vena cava in the anteroposterior view were not statistically significant.Multiple regression analysis indicated that the strongest impact factor on the covered area of the iliac vein opening was the length of the stent in the inferior vena cava,followed by the type of stent and the angle between the affected iliac vein and the inferior vena cava in the lateral view.The standardized coefficients were B1=0.595,B2=0.249,and B3=-0.242,respectively.Greater length of the stent in the inferior vena cava was associated with greater coverage.Compared with braided stents,laser-cut stents covered a larger area of the contralateral iliac vein opening if other conditions were same(t2=3.748,P<0.05).A larger angle between the affected iliac vein and the inferior vena cava in the lateral view was associated with a smaller covered area of the contralateral iliac vein opening(t3=-3.296,P<0.05).Conclusion:During stent placement in a patient,the length of the stent that extends into the inferior vena cava,the angle between the affected iliac vein and the inferior vena cava in the lateral view,and the type of stent should be fully considered.The length of the stent in the inferior vena cava should be minimized while ensuring complete coverage of the lesion.For patients who have a large angle between the affected iliac vein and the inferior vena cava in the lateral view and undergo Wallstent implantation,appropriately increasing the length of the stent in the inferior vena cava will not cause excessive coverage of the contralateral iliac vein opening.