MO775: Vacuum-Assisted Thromboaspiration with Indigo System After Acute Arteriovenous Fistula Thrombosis: Monocentric Experience of an Innovative Interventional Approach
Authors: Cingolani Alessandra , Scrivo Anna , Mattiotti Maria , Zappulo Fulvia , Laura Croci Chiocchini Anna , Gasperoni Lorenzo , Hu Lilio , Abenavoli Chiara , DI Nunzio Miriam , Marchegiani Beatrice , Tringali Edoardo , Cristina Galaverni Maria , Cappelli Alberta , Mosconi Cristina , Renzulli Matteo , Golfieri Rita , Donati Gabriele , LA Manna Gaetano 
Published: May 2022

Abstract

BACKGROUND AND AIMS
Arteriovenous fistula (AVF) must be the first choice where eligible and a prompt approach within 48–72 h should be performed in case of acute AVF failure in order to maintain the patency of the vascular access. Evaluation of the most appropriate de-clotting technique must be made considering the patient's comorbidity, AVF characteristics and absolute, relative and temporary contraindications to each kind of corrective intervention. The outcome is different between the multiple methods and nowadays mechanical thromboaspiration (MT) seems to be an innovative and promising approach.

METHOD
A total of 9 AVF of 9 chronic haemodialysis patients with acute AVF failure were treated with MT between January 2019 and January 2022 and were retrospectively evaluated. MT was carried out via Indigo catheter (Penumbra Inc.), an aspiration system intended for the removal of emboli and thrombi from vessels through venipuncture of AVF/AVG: the continuous aspiration helps distinguish clots from normal blood flow; in case of resistant clots, separators of many sizes can be used at the tip of the catheter to facilitate their fragmentation and aspiration. Adjunctive procedures such as balloon angioplasty (used at all sites), local fibrinolysis, heparin infusion, or stents placement were considered. Technical success was defined by clot removal from AVF or AVG. Clinical success was defined by the restoration of thrill and bruit together with AVF usability after the procedure. Vascular access survival defined as AVF/AVG usability at 3 and 6 months was assessed.

RESULTS
Average age was 71.2 years; dialysis vintage was 93.4 months. Medium follow-up was 13.1 months. All patients needed placement of a temporary central venous catheter (CVC) and dialysis before the MT. Technical success was achieved in 100% of the procedures, clinical success was achieved in 88.9% of the MT (despite the technical success, in 1/9 patients AVF could not be used due to a severe residual venous stenosis). None reported peri-/intraprocedural complications. In 2/9 MT there was no use of anticoagulation; in 5/9 patients, a single unfractionated heparin bolus was used (2500 UI) during the manoeuvre; in 2/9 patients, a single 2500 UI bolus plus continuous intravenous infusion of unfractionated heparin was administered combined with local thrombolysis with urokinase: both patients needed blood transfusions after the manoeuvre, one of them reporting severe haemorrhage from AVF. As adjunctive procedures, 9/9 patients underwent balloon angioplasty; one of them needed stent placement over the venous stenosis. CVC was removed less than 48 h from the procedure in 5/9 patients (55.6%), in 3/9 patients it was removed after 48 h, while 1/9 patients maintained the temporary vascular access due to the lack of clinical success after MT. Double-needle puncture occurred after a medium time of 3.5 days. AVF survival at 3 months and 6 months was 66.6% (6/9 patients), while 3/9 patients faced AVF failure (1/3 patients deceased 2 months after the procedure with a functioning AVF, in 1/3 patients a relapse of AVG thrombosis occurred 2 months after the procedure, 1/3 never reached clinical success due to severe residual venous stenosis). At the time of study design, 3/9 patients resulted to be deceased due to causes unrelated to the procedure. (1/3 due to complications of abdominal surgery, 1/3 due to sepsis, 1/3 due to subarachnoid haemorrhage).

CONCLUSION
MT is an innovative yet functional and safe procedure that allows declotting of the thrombosed AVF while reducing or avoiding anticoagulation and/or surgery.