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Role of Stents in Dialysis Vascular Access - Tweetorial 
Indications for Stent Use Recent Clinical Trials of Stents in Dialysis Vascular AccessComplications associated with Stent Use1/
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#VascularAccessPearls
Arterio-venous (AV) Access causes significant morbidity & mortality in patients on hemodialysis
Most AV access associated complications are due to vascular stenosis
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Vascular Access care has evolved over the past 60 years: -Scribner’s Shunt in 1960
-Brescia-Cimino AVF in 1966
-1st Balloon Angioplasty in 1981
-1st Bare Metal Stent in 1988
-1st Covered Stent in 1996
-DCB use in 2012
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Despite these innovations, AV access stenosis remains a big problem-Percutaneous Balloon Angioplasty (PTA) remains the 1st line therapy for stenosis but it is NOT very effective
-AVF patency after PTA is only 50% at 6-months & it is worse for AVGs
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Neointimal Hyperplasia (NIH) causes vascular stenosis & it is due to: -Hemodynamic stress
-Surgical trauma
-Cannulation needle trauma
-AVG
But balloon angioplasty, the treatment for stenosis, can itself induce NIH & cause restenosis5/
Therefore, Endovascular Stents have been used to treat the vascular stenosisWhat are Endovascular Stents?They are scaffolds that provide mechanical endoluminal support to the vessel wall to maintain patency
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Types of Stents:-1st generation stents were Bare-Metal Stents made of stainless steel
-Next generation of metal stents were Nitinol Stents made of nickel-titanium alloy
- Covered-Stents (Stent-Grafts) are Nitinol stents covered w/ ePTFE or Dacron
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Bare Metal Stents & Nitinol Stents have problems because the tissue in-growth through the bare metal causes restenosisCovered Stents (Stent-Grafts) theoretically form a barrier, & prevent tissue in-growth through the stent & cause less restenosis8/
Recent clinical trials have tested the efficacy of Stent-Grafts for AV access stenosis But before we get to the trials, let’s discuss the basic indications for Stent use:
Rupture of the vessel Recoil (Residual stenosis)Restenosis 9/
Rupture of the vessel can occur during angioplasty of a severely stenotic lesionIn most cases, extravasation can be controlled w/ manual compression or balloon tamponade but if bleeding persists then stents can be used to control the bleeding 10/
Another indication for Stent use is RecoilRecoil is defined as residual stenosis of > 30% following angioplasty & is thought to occur due to elastic recoil of the vessel wallRecoil is associated w/ poor AV access survival11/
Restenosis is the most common indication for stent useAVG patency post-angioplasty is very poorMost common site for AVG stenosis is at the graft-vein anastomosis, therefore recent clinical trials have tested the Stent-grafts at this site12/
Stent-Graft (SG)Trials in Dialysis Vascular AccessFlair PIVOTAL Trial: Flair SG vs. PTA for AVG REVISE Trial: Viabahn SG vs PTA for AVGBoth trials showed better 6-month patency with SG use compared to PTA for graft-vein anastomosis stenosis13/
Stent-Grafts (SG) have also been tested for In-stent restenosis RESCUE Trial: Fluency SG vs PTA for In-stent restenosis in both AVF & AVGRESCUE Trial showed better 6-month patency with SG compared to PTA14/
Summary of Stent Trials in Dialysis Vascular Access15/
Based on this data, KDOQI 2019 guidelines recommend Stent-Graft use for:Recurrent graft-vein anastomosis stenosis in AVG In-stent restenosis in AVF & AVG16/
Cost analysis of Stent-Grafts (SG) show that even though the initial cost of the SG is higher than the cost of balloon angioplasty, the overall cost was similar in the 2 groups at 24-months because the re-intervention rate was lower in the SG group17/
Complications associated with Stent use:Stent MigrationStent FractureStent Strut ProtrusionJailing of the veinsInfection 18/
Stent Migration can cause downstream vein occlusion/stenosis & can impact future AV access optionsStent fracture & protrusion can occur due to repeated cannulation thru the stentStent fracture can occur if stent is placed across a joint19/
Jailing of the Veins is a complication of stent placement & this can impact future AV access options Hence, the operator must be very careful during stent deployment in order to avoid this complication20/
Stent associated infection is a serious complication & may require AV access excision Stent associated AV access infections are more common when the stents are placed in the Pseudo-aneurysms 21/
Stent placement must be avoided in pseudo-aneurysms & in the cannulation zone due to high risk of infection & risk of stent fracture from needle traumaKDOQI Guidelines state that stent placement for pseudo-aneurysm only be used as a ‘last resort’ 22/
SummaryStent-Grafts are a viable therapeutic option for AV access stenosis but it’s use must be guided by scientific evidence Balloon angioplasty remains the 1st line therapy for the majority of the AV access stenotic lesionsEnd/
