PURPOSE: The mechanisms of venous stenosis in vascular access include vascular constriction and neointimal hyperplasia. One purpose of this study was to examine the properties of stenotic lesions in arteriovenous graft outflow veins and the association with the results of treatment using stent placement. SUBJECTS AND METHODS: The study involved 46 patients who underwent stent placement to treat arteriovenous graft outflow vein stenosis. The properties of stenotic lesions before stent placement were observed by ultrasonography and were classified into three groups: vascular constriction types, neointimal proliferation types, and mixed types. Stent placement was performed when elastic recoil occurred or when restenosis occurred at the same site within three months. The primary patency results for each group were then compared. The primary endpoint included patency of the treatment area. RESULTS: The primary patency rate of the treatment area at 6, 12, 18 and 24 months post-stent placement for the vascular constriction type was 100.0%, 92.3%, 84.6% and 75.2%, respectively. Those rates were 66.7%, 33.3%, 33.3% and 25.0% for the neointimal proliferation type, and 90.5%, 52.4%, 38.1% and 27.2% with the mixed type. The vascular constriction type displayed excellent primary patency rates after stent placement. CONCLUSIONS: It is possible to define the types of stenotic lesions for which stent therapy is effective through morphological diagnosis of those lesions using ultrasound tomography.
PURPOSE: The mechanisms of venous stenosis in vascular access include vascular constriction and neointimal hyperplasia. One purpose of this study was to examine the properties of stenotic lesions in arteriovenous graft outflow veins and the association with the results of treatment using stent placement. SUBJECTS AND METHODS: The study involved 46 patients who underwent stent placement to treat arteriovenous graft outflow vein stenosis. The properties of stenotic lesions before stent placement were observed by ultrasonography and were classified into three groups: vascular constriction types, neointimal proliferation types, and mixed types. Stent placement was performed when elastic recoil occurred or when restenosis occurred at the same site within three months. The primary patency results for each group were then compared. The primary endpoint included patency of the treatment area. RESULTS: The primary patency rate of the treatment area at 6, 12, 18 and 24 months post-stent placement for the vascular constriction type was 100.0%, 92.3%, 84.6% and 75.2%, respectively. Those rates were 66.7%, 33.3%, 33.3% and 25.0% for the neointimal proliferation type, and 90.5%, 52.4%, 38.1% and 27.2% with the mixed type. The vascular constriction type displayed excellent primary patency rates after stent placement. CONCLUSIONS: It is possible to define the types of stenotic lesions for which stent therapy is effective through morphological diagnosis of those lesions using ultrasound tomography.