Allogenous vein graft as vascular access for hemodialysis--lost battle?

Prospective Study of Recipient Human Leukocyte Antigen (HLA) Alloimmunization Following the Use of Cold-Stored Saphenous Vein Allografts in Vascular Surgery

Objectives: The aim of this study was to assess the HLA alloreactivity of cold-stored saphenous vein allografts (CSVAs) by identifying the production of HLA donor-specific antibodies (DSAs) in the recipient. The secondary objective was to evaluate CSVA rejection-related complications, such as CSVA thrombosis and/or aneurysmal degeneration in the recipient. Methods: This was a single-center, prospective, experimental before-and-after study which included participants undergoing CSVA placement, either to create a vascular access (VA) for hemodialysis or to create a lower limb arterial bypass. On Day 1, before CSVA placement, total blood samples were taken for HLA typing by sequence-specific primers (SSPs) and anti-HLA antibody detection using a Luminex assay. One month after CSVA placement, a second blood sample was taken to assess the appearance of donor-specific antibodies or an increase in the level of anti-HLA antibodies. Patency of the CSVA and potential aneurysmal degeneration were evaluated at 3 and 6 months with a Doppler ultrasound checkup. Results: From September 2022 to November 2023, 45 patients were included (30 men, 67%; mean age: 71 ± 12 years). One month after CSVA placement, no appearance of de novo anti-HLA antibody was detected in anti-HLA antibody-negative patients at inclusion (n = 28). Among the patients who already had anti-HLA antibodies at inclusion (n = 17), no increase in anti-HLA antibody levels or appearance of de novo anti-HLA antibodies was detected. Conclusions: This prospective study evaluating the immunogenicity of CSVAs through the appearance of anti-HLA antibodies one month after placement demonstrates that they do not seem to induce any HLA alloreactivity. Therefore, they may be used without the risk of HLA immunization in patients awaiting organ transplantation.

Prevalence of thrombosis in patients undergoing dialysis treatment: A systematic review and meta-analysis

AIM

to determine the prevalence of thrombosis in dialysis patients.

BACKGROUND

Thrombosis is the most common cause of vascular access dysfunction in dialysis patients. Various studies have reported different prevalence rates of thrombosis, and no systematic study provides a comprehensive result on this subject.

METHODS

In this systematic review and meta-analysis, a search of available texts was conducted until the end of December 2023, using keywords such as Thrombosis, end-stage renal disease, end-stage kidney disease, hemodialysis, and dialysis in databases including Web of Science, PubMed, Scopus, ProQuest, Ovid, Science Direct, Clinical Key, EMBASE, CINAHL, SID, and MagIran. The random-effects model was used, and the heterogeneity of the studies was assessed using the I2 index. The quality of the selected studies was evaluated using the STROBE checklist. Meta-analysis was performed using CMA version 2 and STATA version 14 software. The study adhered to the guidelines stated in the PRISMA statement.

RESULTS

Out of 12,604 articles found, after removing duplicates and conducting evaluations, the full text of 415 articles was examined, and ultimately, 141 articles were included in the study. The overall prevalence of thrombosis was 14.2% (95% CI: 11.5-17.2). The prevalence of thrombosis was higher in dialysis patients under 50 years of age (17.1%, 95% CI: 11.3-23.8) and patients with vascular access (16.2%, 95% CI: 13.1-19.5), especially arteriovenous grafts (22.8%, 95% CI: 14.5-32.4). Additionally, the prevalence of late thrombosis was higher than that of early thrombosis (15.0% vs. 5.3%) (95% CI: 7.7-24.2 vs. 95% CI: 2.7-8.5).

CONCLUSIONS

The results indicate a relatively high prevalence of thrombosis in dialysis patients. The prevalence of thrombosis in patients with arteriovenous grafts was notable. Considering the risks of thrombosis, the adoption of preventive measures in hemodialysis patients, such as the use of anticoagulant drugs, is recommended.

Editor's Choice - Outcomes of Cold Stored Saphenous Vein Allografts for Haemodialysis Vascular Access

OBJECTIVE

The aim of this study was to evaluate the outcomes of cold stored saphenous vein allografts (CSVAs) for haemodialysis vascular access.

METHODS

A retrospective, two centre study was conducted between January 2016 and December 2020 of all patients who had CSVA placement for haemodialysis vascular access. Primary, primary assisted, and secondary patency were analysed, as well as procedural complications and re-interventions.

RESULTS

One hundred and nine patients (n = 55 women) with a mean age of 67.2 ± 13.6 years, with no options for creating an autogenous arteriovenous fistula, were included in the study. At one year, primary, primary assisted, and secondary patency were 37.6%, 59.0%, and 73.3%, respectively; and at two years 19.9%, 42.5%, and 54.9%, respectively. During a mean follow up period of 26 ± 18 months, five patients (4.6%) had an access infection, with no related death. During the follow up period, 32 patients (29.4%) died and 13 patients (11.9%) underwent a kidney transplant. None of these patients showed immunoconversion before transplantation. The cumulative incidence of adverse events by the Fine-Gray method was calculated. Considering competing risks (death and renal transplantation), 9.2% of patients lost their vascular access at one year and 18% at two years. Moreover, 57.8% patients had stenosis, mainly on the outflow (45.9%), and 49.5% had thrombosis.

CONCLUSION

With a comparable patency rate associated with a low infection rate, CSVA offers a potential alternative to expanded polytetrafluoroethylene grafts. This creates haemodialysis vascular access when the venous capital is exhausted in patients with reported risk factors for vascular access infection, i.e., insertion in the thigh, advanced age, diabetes mellitus, immunocompromised state, obesity, or revision of an infected prosthetic graft.

Ultrasound-guided removal of organized thrombi using biopsy forceps in dialysis patients with arterio-venous access occlusion

INTRODUCTION

As a countermeasure against the organized thrombi frequently observed in vascular access occlusion, we devised a percutaneous excision method for organized thrombi under superficial ultrasound guidance using biopsy forceps. The Radial JawTM 3 (2 mm) biopsy forceps of Boston Scientific Corporation was used. The usefulness of this method was investigated.

METHOD

The following protocol, which is suitable for endovascular treatment, was prepared and used: (1) all procedures were performed under ultrasound guidance and (2) use of the forceps was assisted via a long sheath in cases involving a complicated bloodstream.

SUBJECTS

Among 564 cases of arterio-venous access occlusion that received treatment at this hospital between May 2014 and April 2017, the subjects of this study were 468 cases who could be followed up. Thrombectomy of an organized thrombus using the biopsy forceps was performed 194 times in 138 cases. Biopsy forceps were used in the initial treatment in a total of 115 cases, including 71 cases of acute occlusion of an autologous vein, 3 cases of chronic occlusion of an autologous vein, and 41 cases of acute occlusion of a prosthetic vessel.

RESULTS

The initial success rate for all cases of occlusion was 97.2%. The initial success rate for cases in which biopsy forceps were used was 98.2%. For cases using biopsy forceps, the primary patency rates were 47.1% at 3 months, and the secondary patency rates (until occlusion) were 89.1% at 3 months.

CONCLUSION

This method was considered to be a valuable choice as a countermeasure against organized thrombi.