Ultrasound-Guided Angioplasty of Autogenous Arteriovenous Fistulas in the Office Setting

Abstract

increased when siRNA was complexed with PEI. The amount of siRNA adsorbed generally appeared greater in ePET than in PTFE fabrics. Repeated dipping of ePET in siGLO Red/PEI solution significantly increased siRNA adsorption vs single dipping.Conclusions: siRNA adsorption to ePET and PTFE surfaces is significantly increased if the siRNA is complexed with PEI. Preliminary data in this study suggest that siRNA adsorbs better to ePET than PTFE. Further, repeated dipping of ePET additionally increased adsorption of siRNA to fabric. Thus, coating of ePET with siRNA/PEI may be a method to improve graft patency.Introduction and objectives: Eph-B4, the receptor tyrosine kinase that serves as the embryonic venous fate determinant, is decreased in association with the successful adaptation of surgical vein grafts to the arterial environment. Stimulation of Eph-B4 recovers the native phenotype. However, the Ephrin-B2 protein, the juxtacrine ligand for Eph-B4, is not expressed in veins; as such, the adult physiologic controller of Eph-B4 is unknown. We explored whether the mechanosensitive integrin-␤-1 molecule is an upstream regulator of Eph-B4 signaling.Methods: Eph-B4 -positive endothelial cells and Eph-B4 -negative Cos cells transfected with wild-type or mutant W804A Eph-B4 were stimulated with type I collagen and anti-integrin-␤-1 activating antibody (P4G11) and analyzed with Western blotting. Colocalization was determined using immunofluorescence. Unilateral external carotid artery ligation was performed on heterozygous integrin-␤-1 knockout (Het-B1-KO) mice. Carotid arteries were examined on day 14 and jugular veins on days 1 and 7. Veins from Het-B1-KO mice were placed as aortic interposition grafts into wild-type mice and examined at day 21.Results: Endothelial cells stimulated with collagen or P4G11 increased Eph-B4 phosphorylation. Eph-B4 and integrin-␤-1 colocalized on both endothelial cells and wild-type Eph-B4 transfected Cos cells after stimulation with collagen; mutant W804A Eph-B4 transfected cells were unable to phosphorylate Eph-B4. Het-B1-KO mice that underwent unilateral ligation of the external carotid showed aberrant vascular remodeling. Het-B1-KO vein grafts showed approximately threefold increased neointimal thickening compared with wild-type controls.Conclusions: Integrin-␤-1 is present on endothelial cells, responds to hemodynamic forces, induces Eph-B4 signaling, and modifies vessel and vein graft remodeling. These results connect hemodynamic forces to vein graft adaptation through extracellular matrix interactions. Integrin-␤-1 is an upstream regulator of Eph-B4 signaling during vein graft adaptation and may represent a novel therapeutic target with the potential to limit neointimal hyperplasia in vein grafts.

Editor's Choice – Vascular Access: 2018 Clinical Practice Guidelines of the European Society for Vascular Surgery (ESVS)

“…134 Only a few studies are available on DUS as a tool for ultrasound guided percutaneous transluminal angioplasty (PTA) of failing or non-maturing VA, which may be particularly indicated in patients with iodine contrast allergy or with residual kidney function. 135,136 Although VA infection is primarily diagnosed clinically 137 DUS can supplement information on the extent of infected perivascular tissue and associated thrombosis.…”

Sonographic detection of a radiolucent object in dialysis vascular access

“…The equipment required for percutaneous endovascular angioplasty, such as balloon catheters and vascular sheaths, needs to be prepared based on vascular imaging measurements . As long as the equipment is properly chosen and prepared, the protective tubes of balloon catheters are designed to be impossible to insert into correctly sized vascular sheaths, so that they cannot be placed into the vessels.…”

“…Ultrasonography can detect many solid objects in vessels, and sonographic‐guided angioplasty is a valuable tool to salvage vascular access failure, tending to replace X‐ray angiography, since avoiding radiation exposure and the use of nephrotoxic contrast agent. However, to avoid human errors, angioplasty needs to be performed under prerequisite conditions, including a sonographer skilled in vascular imaging and an interventionist with sufficient knowledge of angioplasty procedures …”

Ultrasound in dialysis access: Opportunities and challenges

“…Late AVF failure as a result of outflow stenosis is identified by a visual narrowing at the stenotic site, a reduction in luminal diameter of >50%, post-stenotic dilatation of the draining vein, elevated peak systolic flow velocity (PSV), and/or ratio across the stenosis >2.0 34 ( Figure 5). Sonography is used to ligate significant accessory veins percutaneously 35 and US-guided angioplasties have been successfully used intra-operatively for arterial stenosis 36 or in office-based practices for the management of dysfunctional and failing fistulae 37,38 and grafts. 39 The use of intra-vascular ultrasound (IVUS) in addition to conventional angiography for dysfunctional grafts in a recently published pilot study altered management plans in a majority of the patients and doubled the median time to reintervention or graft abandonment.…”