297 - Non Thrombotic Venous Lesion (NVL) Due to Extrinsic Aortosternal Compression (ASC) Causing Central Vein Obstruction in Haemodialysis Access: Clinical Descriptors and Early Results of Elective Venous Stenting

Purpose: The bony thorax can cause central venous compression analogous to the better described May Thurner syndrome (MTS) in the iliac veins, related to the first rib, sternoclavicular junction or compression between the aorta and the sternum (ASC). These extrinsic compressive lesions, seen in patients with reduced aortosternal space, behave differently to the more common intrinsic or thrombotic/ fibrotic obstructions seen due to previous neck access. Contrary to our practise of plain balloon angioplasty (POBA) of the latter group, in this report, we test our hypothesis that an ASC will require a stent to prevent recoil and assess initial results.

Materials and Methods: ASC was characterised by the following: Appearance of rarefaction in LIV on frontal contrast digital subtraction angiogram, lesion always across the midline; relatively easy crossing; relatively fewer collaterals; easy balloon inflation with lower pressures and rapid recoil despite 14-16mm balloon angioplasty and pulsatile dynamic narrowing on intravascular ultrasound (IVUS). This was supplemented by CT venogram (n=6), IVUS (n=4) and cone beam CT (n=3). Between April 2021 and June 2025, First rib related indentation and obstruction was not included. 14 patients (M:F 5:9) with left upper limb swelling, mean age 59.6 years, underwent central vein stent placements for such symptomatic ASC. Additional thrombectomy devices were used in 2 cases. 5 patients had a history of previous plain angioplasty with recurrent symptoms. There were 4 radiocephalfc, 7 brachiocephalic, 1 brachiobasilic and 2 arteriovenous grafts. 16mm (n=13) and 18mm (n=1) diameter dedicated venous stents were placed mostly without jailing the right innominate vein. Four patients had collateral veins related to the obstruction. Antiplatelet (n=10) and Apixaban (n=4) were administered post procedure.

Results: After a mean follow up of 12.7 (range 1-29) months, all patients are asymptomatic. I patient needed angioplasty of instent stenosis. Additional procedures like fistuloplasty or cephalic arch stent was performed in 3 patients. 2 patients died during follow up unrelated to access and with no recurrent central vein symptoms. The mean aortosternal distance, in 12/14 patients, in this group, was 5.8 mm (range 3-9mm). Post procedure CT venogram confirmed stent patency in 5/5 patients where it was performed.

Conclusion: LIV obstruction due to extrinsic ASC may be a distinct clinical entity analogous to MTS in iliac veins. Recognition of this condition may be critical, as timely venous stent can prevent recurrent obstruction and prolong access survival.