Correlation between preoperative vein and artery diameters and arteriovenous fistula outcome in patients with end-stage renal disease

Sex Differences in Inflammation During Venous Remodeling of Arteriovenous Fistulae

Vascular disorders frequently have differing clinical presentations among women and men. Sex differences exist in vascular access for hemodialysis; women have reduced rates of arteriovenous fistula (AVF) maturation as well as fistula utilization compared with men. Inflammation is increasingly implicated in both clinical studies and animal models as a potent mechanism driving AVF maturation, especially in vessel dilation and wall thickening, that allows venous remodeling to the fistula environment to support hemodialysis. Sex differences have long been recognized in arterial remodeling and diseases, with men having increased cardiovascular events compared with pre-menopausal women. Many of these arterial diseases are driven by inflammation that is similar to the inflammation during AVF maturation. Improved understanding of sex differences in inflammation during vascular remodeling may suggest sex-specific vascular therapies to improve AVF success.

Predictive Value of 1-Week Postoperative Ultrasonography Findings for the Patency Rate of Arteriovenous Fistula

Introduction

Most guidelines in different countries recommend waiting more than 2 weeks for the initial cannulation of an arteriovenous fistula (AVF) after its creation. Although an experienced examiner can subjectively determine if an AVF is ready for early cannulation, there is a lack of objective information to guide whether early cannulation is appropriate or how early cannulation may affect an AVF’s primary patency. The current study examined the relationship between the initial cannulation and the prognosis of AVF, considering ultrasonography (US) findings.

Methods

This retrospective observational study enrolled 103 patients with end-stage renal disease who had started hemodialysis therapy from 2013 to 2015 at the Juntendo University Hospital. All patients had been given a primary AVF before or after the initiation of dialysis, had undergone US examinations both before and 7 days after surgery, had initially cannulated the AVF at ≥7 days after surgery, and were observed for over 1 year.

Results

The factor associated with the loss of primary patency was a resistance index of brachial artery ≥0.65 on US examination at 7 days after surgery. There was no significant difference in patency rate between the early (within 14 days after surgery) and late initial cannulation groups (≥15 days after surgery).

Conclusion

Because a resistance index <0.65 on US findings at 7 days after surgery was a good indicator for predicting an excellent patency rate when we performed first cannulation of AVF located in the forearm within 2 weeks after its creation, 1-week postoperative US evaluation may provide crucial information.

Molecular Targets for Improving Arteriovenous Fistula Maturation and Patency

The increasing prevalence of chronic and end-stage renal disease creates an increased need for reliable vascular access, and although arteriovenous fistulae (AVF) are the preferred mode of hemodialysis access, 60% fail to mature and only 50% remain patent at one year. Fistulae mature by diameter expansion and wall thickening; this outward remodeling of the venous wall in the fistula environment relies on a delicate balance of extracellular matrix (ECM) remodeling, inflammation, growth factor secretion, and cell adhesion molecule upregulation in the venous wall. AVF failure occurs via two distinct mechanisms with early failure secondary to lack of outward remodeling, that is insufficient diameter expansion or wall thickening, whereas late failure occurs with excessive wall thickening due to neointimal hyperplasia (NIH) and insufficient diameter expansion in a previously functional fistula. In recent years, the molecular basis of AVF maturation and failure are becoming understood in order to develop potential therapeutic targets to aide maturation and prevent access loss. Erythropoietin-producing hepatocellular carcinoma (Eph) receptors, along with their ligands, ephrins, determine vascular identity and are critical for vascular remodeling in the embryo. Manipulation of Eph receptor signaling in adults, as well as downstream pathways, is a potential treatment strategy to improve the rates of AVF maturation and patency. This review examines our current understanding of molecular changes occurring following fistula creation, factors predictive of fistula success, and potential areas of intervention to decrease AVF failure.