298 - Intravascular Ultrasound for Complex Central Venous Obstruction in Hemodialysis Access: Morphological Insights and Therapeutic Implications

Purpose: Digital subtraction angiography (DSA) is the current standard in assessing central venous obstruction (CVO) {1}. As in pelvic veins, intravascular ultrasound (IVUS) may overcome the limitations of two-dimensional projectional imaging in accurately assessing complex central venous pathology {2}. We set out to compare the diagnostic accuracy of intravascular ultrasound (IVUS) versus DSA in detecting and characterizing CVO in hemodialysis patients, and assess the impact of IVUS guidance on treatment decision-making {3-7}.

Materials and Methods: This prospective, single-center, observational, comparison study enrolled 25 consecutive maintenance hemodialysis patients with symptomatic central venous obstruction over 12 months (December 2023-December 2024). All patients underwent sequential imaging with both DSA and IVUS during the same procedure. Endpoints included diagnostic accuracy comparison, quantitative measurement differences, and treatment modification rates. Statistical analysis employed paired t-tests, McNemar's test, Fisher's exact test, intraclass correlation coefficients (ICC), and Bland-Altman plots.

Results: A total of 31 lesions were identified across 25 patients using IVUS, demonstrating superior diagnostic performance compared to DSA, which detected 27 lesions (87.1%, p = 0.125). IVUS consistently measured higher stenosis severity (80.6 ± 14.1% vs 58.9 ± 28.2%, p < 0.001), larger reference vessel diameters (15.1 ± 1.5 mm vs 11.6 ± 4.2 mm, p < 0.001), and longer lesion lengths (37.0 ± 15.1 mm vs 26.1 ± 17.8 mm, p < 0.001). IVUS detected significantly more external compression (41.9% vs 12.9%, p < 0.001), distinguishing it from intrinsic stenosis and provided superior morphological characterization such as vessel wall/lumen irregularities (45.2%), fibrin sheaths (41.9%), chronic thrombus (32.3%), acute thrombus (3.2%) and eccentric stenosis (38.7%). Following initial balloon angioplasty, IVUS detected 3.8 times more residual stenosis (61.3% vs 16.1%, p< 0.001) leading to treatment modifications in 54.8% of lesions. There was 100% technical and clinical success with no IVUS-related complications and addition of only 7.8 ± 1.0 minutes to procedural time.

Conclusion: IVUS provides superior diagnostic efficacy compared to DSA in CVO, enabling enhanced lesion detection, accurate vessel measurements, differentiation between intrinsic stenosis and external compression, and comprehensive morphological characterisation, thereby facilitating optimised treatment decisions while maintaining excellent safety and efficiency profiles.