Novel Paradigms for Dialysis Vascular Access

Abstract

SummaryFailure of hemodialysis access is caused mostly by venous intimal hyperplasia, a fibro-muscular thickening of the vessel wall. The pathogenesis of venous neointimal hyperplasia in primary arteriovenous fistulae consists of processes that have been identified as upstream and downstream events. Upstream events are the initial events producing injury of the endothelial layer (surgical trauma, hemodynamic shear stress, vessel wall injury due to needle punctures, etc.). Downstream events are the responses of the vascular wall at the endothelial injury that consist of a cascade of processes including leukocyte adhesion, migration of smooth muscle cells from the media to the intimal layer, and proliferation. In arteriovenous fistulae, the stenoses occur in specific sites, consistently related to the local hemodynamics determined by the vessel geometry and blood flow pattern. Recent findings that the localization of these sites matches areas of disturbed flow may add new insights into the pathogenesis of neointimal hyperplasia in the venous side of vascular access after the creation of the anastomosis. The detailed study of fluid flow motion acting on the vascular wall in anastomosed vessels and in the arm vasculature at the patient-specific level may help to elucidate the role of hemodynamics in vascular remodeling and neointimal hyperplasia formation. These computational approaches may also help in surgical planning for the amelioration of clinical outcome. This review aims to discuss the role of the disturbed flow condition in acting as upstream event in the pathogenesis of venous intimal hyperplasia and in producing subsequent local vascular remodeling in autogenous arteriovenous fistulae used for hemodialysis access. The potential use of blood flow analysis in the management of vascular access is also discussed.

The care and keeping of vascular access for home hemodialysis patients

“…32,33 The effect of higher pump speeds has not been proven, but injury to the endothelial wall from altered flow mechanics of high pump speeds is likely to occur. 34 Expert opinion recommends that lower pump speeds should be used to promote vessel integrity and maintain fistula longevity. Regardless of the blood pump speeds utilized, most programs aim to maintain the arterial and venous pressures below −250 and 250 mmHg, respectively; however, these pressures are not strongly evidence based.…”

c-Kit signaling determines neointimal hyperplasia in arteriovenous fistulae

“…It achieves higher patency rates, has fewer complications than synthetic grafts (12,29,31), and has a lower risk of infections than central venous catheters (17,29). Despite its advantages, A-V fistulae frequently fail to mature or become dysfunctional after successful dialysis sessions, and this occurs primarily due to the development of neointimal hyperplasia (NIH) within the A-V fistula circuit (2,5,39). Stenosed A-V fistulae can sometimes be salvaged through angioplasty or surgical interventions, but these attempts often result in restenosis or additional complications (32).…”

“…These include vein configuration (22), hemodynamics stress (39), inflammation (20), and preexisting diseases like diabetes (40) and kidney failure (26). The above conditions induce de novo accumulation of growth factors such as VEGF (48), plateletderived growth factor (41), fibroblast growth factor (42), and transforming growth factor-␤ (18) and their receptor tyrosine kinases (RTKs) in the outflow vein, which ultimately increase the proliferation, migration, and survival of neointimal cells and the subsequent thickening of the vessel wall.…”

Comparison of Outcomes with Arteriovenous Fistula and Arteriovenous Graft for Vascular Access in Hemodialysis: A Prospective Cohort Study

“…Despite technological advances in HD VA creation since Cimino and Brescia first described radiocephalic fistulae, native AVF is still considered superior to AVG and CVC [22][23][24] . The prevalence of AVF has increased since the Fistula First initiative.…”