Historical Perspective on More Than 60 Years of Hemodialysis Access

Comparison of end-to-side versus side-to-side anastomosis in upper limb arteriovenous fistula in hemodialysis patients: A systematic review and meta-analysis

Objective

It is currently unclear if the anastomosis technique impacts the patency of upper arm arteriovenous fistula (AVF) in hemodialysis patients. This review compared outcomes of end-to-side and side-to-side anastomosis for AVF fistula in hemodialysis patients.

Methods

PubMed, CENTRAL, Web of Science, and Embase were searched for all types of studies published between 1st January 2000 to 3rd September 2022. Patency rates at 6, 12 months, maturation time, and complications were compared between ETS and STS groups.

Results

Sixteen studies including six randomized controlled trials (RCTs) were included. Meta-analysis showed no difference in patency rates between ETS and STS group at 6 months (OR: 1.15 95% CI: 0.72, 1.83 I ² = 52% p = 0.56) but better patency with STS at 12 months (OR: 0.63 95% CI: 0.41, 0.95 I ² = 21% p = 0.03). The difference was non-significant in a subgroup analysis of RCTs and non-RCTs. In the absence of distal vein ligation in the STS group, the ETS group had significantly better patency at 6 months but with distal vein ligation, STS had higher patency at 12 months. Meta-analysis demonstrated no difference in maturation time between the two groups (MD: 0.10 95% CI: 0.29, 0.49 I ² = 89% p = 0.61). Only a descriptive analysis of complications could be carried out with no major difference.

Conclusion

Our review demonstrates that the STS anastomosis technique with distal vein ligation may result in significantly better patency rates as compared to the standard ETS technique. Data for complication rates are scarce and varied but without any significant differences between the two techniques.

Hemodynamic Impact of Anastomosis Size and Angle in Side-to-End Arteriovenous Fistulae: A Computer Analysis

Purpose

An arteriovenous fistula (AVF) is the first choice vascular access for hemodialysis. The AVF pathway can be seen as consisting of seven segments: proximal artery, distal artery, arterial collaterals, proximal vein, distal vein, venous collaterals, and the anastomosis. While most studies describe access complications without considering the impact of the anastomosis (7th segment), the present mathematical study investigated the hemodynamic impact of anastomosis size and angle on pressure drop and flow distribution.

Methods

A side-to-end AVF model was developed, consisting of an anastomosis with a given cross-sectional area (substudy 1) and angle (substudy 2). Starting from two reference cases (one for each substudy) with fixed flow distribution, pressure drop over the anastomosis was calculated for an arterial inflow in the range 600 to 1200 ml/min. The same reference cases, subsequently with fixed pressure boundary conditions, were further used to assess flow distribution over the proximal vein and distal artery.

Results

Pressure drop decreased with a larger anastomosis cross-sectional area and an angle wider than 43°, while it was almost stable for smaller angles. Although proximal arterial inflow increased for larger anastomosis areas, the overall flow distribution shifted almost totally to the proximal vein. When the anastomosis angle exceeded 58°, the proximal arterial inflow was not sufficient to deliver enough flow, leading to distal arterial flow reversal.

Conclusion

Despite the underestimation of the hemodynamic impact of the anastomosis size and angle in the literature, this study showed major influences on the pressure drop over the anastomosis and, with it, on flow distribution towards the arterial and venous outflow.

Radiocephalic fistulas for hemodialysis: a comparison of techniques

The radiocephalic fistula dates back to the 1960s with good long-term survival and a low incidence of complications. The standard practice of creating an end cephalic vein to side radial artery fistula (ETS) has a high incidence of early thrombosis and failure to mature, which limits its efficacy. The hypothesis is that a 1.3- to 1.5-cm side-to-side with distal vein ligation anastomosis (STS) is associated with a lower early thrombosis rate and higher primary patency rate. We retrospectively evaluated all radiocephalic fistulas created at our hospital from January 1, 2012, to December 31, 2012, comparing a 1.3- to 1.5-cm STS anastomosis to the ETS anastomosis. Primary endpoints were patency at three and six months and the secondary outcome was suitability for cannulation. An ETS anastomosis resulted in an early thrombosis rate, 3-month cannulation rate, and 6-month primary patency rate of 14, 30, and 48 per cent, respectively. Outcomes from the STS technique were significantly improved with no early thrombosis (P < 0.05), 3-month cannulation rate of 67 per cent (P < 0.03), and a primary patency of 75 per cent (P = 0.03). A STS radiocephalic fistula with distal vein ligation is superior to the ETS radiocephalic fistula. Early thrombosis, 6-month primary patency, and cannulation rates were significantly improved.

Tunneled dialysis catheters: recent trends and future directions

Despite aggressive efforts to increase autogenous fistula prevalence primarily from recommendations by the NKF and the Fistula First National Vascular Access Improvement Initiative, catheters remain an essential access modality for a large percentage of the hemodialysis population. Tunneled dialysis catheters or chronic catheters are associated with a multitude of complications including infections, stenosis, thrombosis, and increased morbidity and mortality even after adjustment for potential confounding variables. Also, given the blood flow rates of catheters, dialysis adequacy is compromised as compared with arteriovenous fistulae and arteriovenous grafts. This review endeavors to provide an update on catheter outcomes in the Fistula First and Kidney Disease Outcomes Quality Initiative era in relation to the increasing fistula prevalence and decline in graft placements. The conflicting view of whether catheters are increasing concurrently with the increase in fistula prevalence is discussed. The management of tunneled dialysis catheter-related complications is considered with a review of the most recent data. Future research strategies and innovations in catheter design are also addressed. This review provides a comprehensive update of tunneled hemodialysis catheters, their necessity and pitfalls, and novel directions for future investigation.