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

HeRO graft-The results of the cologne single center study

OBJECTIVE

The HeRO graft is a technique for vascular access in patients with limited treatment options; however, the published results with the HeRO graft are diverging. We therefore conducted a single-center study.

METHODS

Patient records between July 2014 and February 2020 from Vascular Access Unit of the Department of Vascular and Endovascular Surgery of University Clinic of Cologne (Germany) were reviewed. Retrospective data was analysed from patients with a HeRo graft (n = 18).

RESULTS

Eighteen patients were enrolled in the study. The mean age of the patients was 62.8 ± 17.24 years. During the follow-up period, no patients died from complications related to the HeRO graft. Each patient had a mean of 1.94 concomitant diseases. The primary patency rates of the HeRO graft at 3, 6, 12, 18, and 24 months were 61.1%, 50%, 16.7%, 11.1%, and 5.6%, respectively. The secondary patency rates at the same time intervals were 77.8%, 72.8%, 55.6% 55.6%, and 55.6%, respectively. There were 44 re-operations per year, or 2.4 operations per patient. The main cause of acute complications was acute graft occlusions after HERO graft implantation. An infection after the graft implantation occurred in five (27.7%) patients, leading to graft explanation in 2 cases.

CONCLUSION

The use of the HERO graft is a valuable alternative method for providing a durable dialysis access in patients with limited access options. The secondary patency and survival are good with a low infection rate.

Application of modified no-touch technique in rabbit arteriovenous fistula model and its effect on venous neointimal hyperplasia

BACKGROUND

To investigate the technical advantages of a modified no-touch technique (MNTT) in constructing arteriovenous fistulas (AVF) compared to the conventional technique (CT) and assess its potential to reduce neointimal hyperplasia in the outflow vein.

METHODS

Forty-seven New Zealand rabbits were randomly divided into three groups: control, CT, and MNTT. Rabbits in control group were observed using ultrasound and then euthanized to obtain external jugular vein (EJV) for Hematoxylin-eosin (H-E). We established common carotid artery (CCA)-EJV AVF using MNTT in the MNTT group and the CT in the CT group. AVF patency and complications were compared between the CT and MNTT groups. Rabbits with patent AVF in both groups were observed using ultrasound 2 weeks after surgery to evaluate changes in the vessel diameter and blood flow spectrum of the AVFs. H-E staining measured the intima thickness of EJV adjacent to the anastomosis and histologic characteristics of the AVF at 2 and 4 weeks after surgery.

RESULTS

Five rabbits died after surgery with common symptoms of sneezing, coughing, runny nose, anorexia, and diarrhea; two in the MNTT group and three in the CT group. There were significant differences in the diameter (p = 0.010) and peak systolic velocities (PSV) (p = 0.001) of EJV between the CT and MNTT groups 2 weeks after surgery. Spiral laminar flow (SLF) was observed in CCA and EJV adjacent to anastomosis in the MNTT group. Additionally, histological observations showed less venous neointimal hyperplasia in the MNTT group than in the CT group 4 weeks after surgery.

CONCLUSION

The rabbit model of CCA-EJV AVF established using MNTT demonstrated fewer complications, larger vein diameters, and reduced venous neointimal hyperplasia, indicating that this maybe an ideal animal model to further investigate the application of MNTT in AVF surgery.

Clinical outcomes and predictive factors of stent grafts treatment for symptomatic central venous obstruction in end stage kidney disease patients with arteriovenous access

To assess the efficacy of stent grafts (SGs) in managing central venous obstruction disease (CVOD) in hemodialysis (HD) patients with arteriovenous (AV) access, and to identify predictive factors influencing the SG treatment outcomes. HD subjects with CVOD who underwent SGs placement at our center between August 2018 and June 2022 were enrolled. Survival curve analysis using the Kaplan-Meier method and log-rank test was performed. Cox proportional hazards regression analysis was employed to identify predictive factors associated with outcomes. A total of 59 SG implantation procedures for CVOD were analyzed, comprising 30 cases of stenosis and 29 cases of occlusion. The access circuit primary patency (ACPP) at 6, 12, and 24 months post-SG placement were 80.9%, 53.8%, and 31.4%, respectively, while, the target lesion primary patency (TLPP) were 91.3%, 67.6%, and 44.5%, respectively. Subgroup analysis revealed higher TLPP in the stenosis group compared to the occlusion group, although the difference was not statistically significant (P = 0.165). The TLPP was significantly improved by SG placement in those who had antecedent balloon dilations (P < 0.001). Cox proportional hazards regression identified target lesion length ≥ 30 mm and procedure defects as independent predictors of lower TLPP after SG treatment for CVOD in HD patients. SG placement demonstrates safety and efficacy in managing CVOD among HD patients, leading to improved TLPP of endovascular therapy (EVT) for CVOD. Notably, long target lesions (≥ 30 mm) and procedure defects emerged as predictive factors influencing TLPP.

Temporal trends in hemodialysis access creation during the fistula first era

OBJECTIVE

Although forearm arteriovenous fistulas (AVFs) are the preferred initial vascular access for hemodialysis based on national guidelines, there are no population-level studies evaluating trends in creation of forearm vs upper arm AVFs and arteriovenous grafts (AVGs). The purpose of this study was to report temporal trends in first-time permanent hemodialysis access type, and to assess the effect of national initiatives on rates of AVF placement.

METHODS

Retrospective cross-sectional study (2012-2022) utilizing the Vascular Quality Initiative database. All patients older than 18 years with creation of first-time upper extremity surgical hemodialysis access were included. Anatomic location of the AVF or AVG (forearm vs upper arm) was defined based on inflow artery, outflow vein, and presumed cannulation zone. Primary analysis examined temporal trends in rates of forearm vs upper arm AVFs and AVGs using time series analyses (modified Mann-Kendall test). Subgroup analyses examined rates of access configuration stratified by age, sex, race, dialysis, and socioeconomic status. Interrupted time series analysis was performed to assess the effect of the 2015 Fistula First Catheter Last initiative on rates of AVFs.

RESULTS

Of the 52,170 accesses, 57.9% were upper arm AVFs, 25.2% were forearm AVFs, 15.4% were upper arm AVGs, and 1.5% were forearm AVGs. From 2012 to 2022, there was no significant change in overall rates of forearm or upper arm AVFs. There was a numerical increase in upper arm AVGs (13.9 to 18.2 per 100; P = .09), whereas forearm AVGs significantly declined (1.8 to 0.7 per 100; P = .02). In subgroup analyses, we observed a decrease in forearm AVFs among men (33.1 to 28.7 per 100; P = .04) and disadvantaged (Area Deprivation Index percentile ≥50) patients (29.0 to 20.7 per 100; P = .04), whereas female (17.2 to 23.1 per 100; P = .03), Black (15.6 to 24.5 per 100; P < .01), elderly (age ≥80 years) (18.7 to 32.5 per 100; P < .01), and disadvantaged (13.6 to 20.5 per 100; P < .01) patients had a significant increase in upper arm AVGs. The Fistula First Catheter Last initiative had no effect on the rate of AVF placement (83.2 to 83.7 per 100; P=.37).

CONCLUSIONS

Despite national initiatives to promote autogenous vascular access, the rates of first-time AVFs have remained relatively constant, with forearm AVFs only representing one-quarter of all permanent surgical accesses. Furthermore, elderly, Black, female, and disadvantaged patients saw an increase in upper arm AVGs. Further efforts to elucidate factors associated with forearm AVF placement, as well as potential physician, center, and regional variation is warranted.

Arteriovenous access creation and hazards of hospitalization and death in patients starting hemodialysis

BACKGROUND

Recent evidence suggests an overestimation of the benefits associated with arteriovenous (AV) fistula versus graft in certain populations. We assessed hazards of all-cause and cause-specific hospitalization and death associated with AV access type in patients who started hemodialysis with a catheter in France, overall and by subgroups of age, sex and comorbidities.

METHODS

We performed a target trial emulation including patients who initiated hemodialysis with a catheter from 2010 through 2018 and were followed by the REIN Registry. We identified first-created fistula or graft through the French national health-administrative database. We used joint frailty models to deal with recurrent hospitalizations and potential informative censoring by death, and inverse probability weighting to account for confounding.

RESULTS

From the 18 800 patients included (mean age 68 ± 15 years, 35% women), 5% underwent AV graft creation first. The weighted hazard ratio (wHR) of all-cause hospitalization associated with graft was 1.08 [95% confidence interval (CI) 1.02 to 1.15], that of vascular access-related hospitalization was 1.43 (95% CI 1.32 to 1.55), and those of cardiovascular- and infection-related hospitalizations were 1.14 (95% CI 1.03 to 1.26) and 1.11 (95% CI 0.97 to 1.28), respectively. Results were consistent for most subgroups, except that the highest hazard of all-cause, cardiovascular- and infection-related hospitalizations with graft was blunted in patients with comorbidities (i.e. diabetes, wHR 1.01, 95% CI 0.93 to 1.10; 1.10, 95% CI 0.96 to 1.26; and 0.94, 95% CI 0.78 to 1.12, respectively).

CONCLUSIONS

In patients starting hemodialysis with a catheter, AV graft creation is associated with increased hazard of vascular access-related hospitalizations compared with fistula. This may not be the case for death or other causes of hospitalization.

Out-Patient versus In-Patient Arteriovenous Fistula Creation for Dialysis: Assessing Cost-Effectiveness Alongside Clinical Implications

(1) Background: The surgical procedure to create an arteriovenous fistula (AVF) can be performed in either an ambulatory or in-patient hospital setting, depending on the case's complexity, the anesthesia type used, and the patient's comorbidities. The main scope of this study is to assess the cost-effectiveness and clinical implications of surgically creating an AVF in both ambulatory and in-hospital settings. (2) Methods: We conducted a retrospective observational study, in which we initially enrolled all patients with end-stage kidney disease (ESKD) admitted to the Vascular Surgery Department, Emergency County Hospital of Targu Mures, Romania, to surgically create an AVF for dialysis, between January 2020 and December 2022. The primary endpoint of this study is to assess the cost-effectiveness of surgically creating an AVF in an ambulatory vs. in-hospital setting by comparing the costs required for the two types of admissions. Further, the 116 patients enrolled in this study were divided into two groups based on their preference for hospitalization: out-patients and in-patients. (3) Results: Regarding in-patient comorbidities, there was a higher prevalence of peripheral artery disease (PAD) (p = 0.006), malignancy (p = 0.020), and previous myocardial infarction (p = 0.012). In addition, active smoking (p = 0.006) and obesity (p = 0.018) were more frequent among these patients. Regarding the laboratory data, the in-patients had lower levels of white blood cells (WBC) (p = 0.004), neutrophils count (p = 0.025), lymphocytes (p = 0.034), and monocytes (p = 0.032), but there were no differences between the two groups regarding the systemic inflammatory biomarkers or the AVF type. Additionally, we did not register any difference regarding the outcomes: local complications (p = 0.588), maturation failure (p = 0.267), and primary patency (p = 0.834). In our subsequent analysis, we discovered no significant difference between the hospitalization type chosen by patients regarding AVF primary patency failure (p = 0.195). We found no significant association between the hospitalization type and the recorded outcomes (all ps > 0.05) in both multivariate linear regression and Cox proportional hazard analysis. (4) Conclusions: In conclusion, there are no significant differences in the clinical implications, short-term and long-term complications of AVF for out-patient and in-patient admissions. Additionally, we found no variation in the costs associated with laboratory tests and surgical supplies for an AVF creation. Therefore, it is safe to perform ambulatory AVFs, which can reduce the risk of hospital-acquired infections and provide greater comfort to the patient.

Evaluation of arteriovenous fistula maturation and early prediction of clinical eligibility, using ultrasound: The Fistula Maturation Evaluation (FAME) Study

INTRODUCTION

The study of time-related alterations of ultrasound-determined parameters during maturation, and the assessment of time to hemodynamic maturation, enabling early prediction of clinical eligibility, of hemodialysis autologous arteriovenous fistulae (AVF).

METHODS

This is an observational, prospective, study of only AVF-eligible patients referred for access creation, from 02/2019 to 02/2022 (ClinicalTrials.gov identifier: NCT0473687). Brachial artery diameter (dBA), access flow volume (FV), non-augmented efferent vein diameter (dEV), resistivity index (RI), and efferent vein total wall thickness (tEV), were assessed by ultrasound. Measurements were conducted daily in the first week and repeated on days 14, 21, 30, 60, and 90, postoperatively. The primary endpoint included the documentation of serial changes of flow and structural parameters related to AVF maturation in the first 90 days of the post-operative period and maturation early prediction. Secondary endpoints included the determination of factors affecting maturation.

RESULTS

One hundred one participants (mean age, 67 ± 6 years; 76 males) were enrolled. Average dBA and FV reached maximum on day 60 (5.64 ± 0.85 mm) and 90 (1.172 ± 617 mL/min), respectively. Day 7 values of dBA (5.48 ± 0.73 mm) and FV (1.039 ± 531 mL/min) did not alter significantly during the follow-up period. Parameters indicative of clinical functionality, dEV (5.82 ± 0.90 mm) and tEV (0.493 ± 0.10 mm), reached approximately 90% of maximum (6.66 ± 1.42 mm and 0.526 ± 0.11 mm), by day 14. RI reached minimum on day 30 (0.46 ± 0.09), without significant changes after day 2 (0.48 ± 0.09, p = 0.284). A significant correlation was identified, between day 7 FV and day 60 dEV (r = 0.40, p = 0.0002). A FV cut-off value ⩾657.51 mL/min, on day 7, predicted successful fistula maturation with 85% sensitivity and 100% specificity. Multivariate analysis identified female gender, age >75, diabetes, and wrist access as independent predictors of decreased values of maturation parameters.

CONCLUSION

Hemodynamic maturation is completed by the first postoperative week, while AVF is clinically functional, by the second. FV can be used for early prediction of maturation.

Proximalization of Arterial Inflow for the Treatment of Limb Ischemia in a Transposed Femoral Arteriovenous Fistula-A Case Report

INTRODUCTION

Femoral vein transposition is one of the final resorts for vascular access in patients with exhaustion of upper limb venous patrimony and central venous occlusive disease. Its major pitfalls include hemodialysis access-induced distal ischemia and infection. Surgical procedures may be warranted to preserve vascular access if ischemia develops. Several techniques are reported in the literature for femoral vein transposition.

CASE REPORT

We expose an endoscopic femoral vein harvesting as an alternative to the single thigh incision in order to avoid its associated complications. In the setting of ischemia, proximalization of arterial inflow was used to manage femoral vein transposition associated limb ischemia.

CONCLUSION

This case report aims to expose the aforementioned unreported surgical techniques for lower limb arteriovenous fistula, its advantages, and pitfalls, as well as considerations on its future use.

Application of a supporting catheter in surgery for forearm arteriovenous fistula construction

INTRODUCTION

This study explored the feasibility of a supporting catheter combined with modified end-to-side anastomosis in the operation of radio-cephalic arteriovenous fistula (RC-AVF) and evaluated the clinical application value of this technique.

METHODS

Sixty patients underwent RC-AVF operations in our hospital from January 2022 to June 2022. All the patients were treated with modified end-to-side AVF anastomosis and divided into the control group or the test group depending on whether a supporting catheter was applied. The clinical data of 60 cases were analysed retrospectively. Intraoperative related indices, the first time the fistula was used, the success rate of first puncture, the blood flow of first dialysis, the maturity condition of fistula, the size of anastomosis, the diameter of radial artery and drainage vein, the blood flow of brachial artery 8 weeks after operation and the incidence of complications within 6 months after operation were compared between the two groups.

RESULTS

Compared with that in the control group, the time spent on the vascular anastomosis in the test group was significantly shortened (p<0.05). The blood flow of the first dialysis, the size of the anastomosis, the diameter of the drainage vein, the blood flow of the brachial artery 8 weeks after the operation and the incidence of complications within 6 months after operation were significantly different between the two groups (p<0.05).

CONCLUSION

In the RC-AVF operation, using a supporting catheter can not only increase operation efficiency by reducing surgical injury and difficulty of vascular anastomosis, but also improve postoperative prognosis. RC-AVF is worth promoting in clinical practice.

Impact of stage-specific limb function exercises guided by a self-management education model on arteriovenous fistula maturation status

BACKGROUND

The exercise of limb function is the most economical and safe method to promote the maturation of arteriovenous fistula (AVF). However, due to the lack of a unified exercise standard in China, many patients have insufficient awareness of the importance of AVF, leading to poor effectiveness of limb function exercise. The self-management education model can effectively promote patients to take proactive health-related actions. This study focuses on the characteristics of patients during the peri-AVF period and conducts a phased limb function exercise under the guidance of the self-management education model to observe changes in factors such as the maturity of AVF.

AIM

To assess the impact of stage-specific limb function exercises, directed by a self-management education model, on the maturation status of AVFs.

METHODS

This study is a randomized controlled trial involving 74 patients with forearm AVFs from the Nephrology Department of a tertiary hospital in Sichuan Province, China. Patients were randomly divided into an observation group and a control group using a random number table method. The observation group underwent tailored stage-specific limb function exercises, informed by a self-management education model which took into account the unique features of AVF at various stages, in conjunction with routine care. Conversely, the control group was given standard limb function exercises along with routine care. The assessment involves the maturity of AVFs post-intervention, postoperative complications, and the self-management level of the fistula in both groups patients. Analyses were conducted using SPSS version 23.0. Count data were represented by frequency and percentage and subjected to chi-square test comparisons. Measurement data adhering to a normal distribution were presented as mean ± SD. The independent samples t-test was utilized for inter-group comparisons, while the paired t-test was used for intra-group comparisons. For measurement data not fitting a normal distribution, the median and interquartile range were presented and analyzed using the Wilcoxon rank sum test.

RESULTS

At the 8-wk postoperative mark, the observation group demonstrated significantly higher scores in AVF symptom recognition, symptom prevention, and self-management compared to the control group (P < 0.05). However, the variance in symptom management scores between the observation and control groups lacked statistical significance (P > 0.05). At 4 wk after the operation, the observation group displayed a superior vessel diameter and depth from the skin of the drainage vessels in comparison to the control group (P < 0.05). While the observation group did manifest elevated blood flow rates in the drainage vessels relative to the control group, this distinction was not statistically significant (P > 0.05). By the 8-wk postoperative interval, the observation group outperformed the control group with notable enhancements in blood flow rates, vessel diameter, and depth from the skin of drainage vessels (P < 0.01). Seven days following the procedure, the observation group manifested significantly diminished limb swelling and an overall reduced complication rate in contrast to the control group (P < 0.05). The evaluation of infection, thrombosis, embolism, arterial aneurysm stenosis, and incision bleeding showed no notable differences between the two groups (P > 0.05). By the 4-wk postoperative juncture, complications between the observation and control groups were statistically indistinguishable (P > 0.05).

CONCLUSION

Stage-specific limb function exercises, under the guidance of a self-management education model, amplify the capacity of AVF patients to discern and prevent symptoms. Additionally, they expedite AVF maturation and mitigate postoperative limb edema, underscoring their efficacy as a valuable method for the care and upkeep of AVF in hemodialysis patients.

Outcomes of brachial artery transposition in hemodialysis patients

OBJECTIVE

In hemodialysis patients with a difficult access extremity who are not suitable for an arteriovenous fistula or arteriovenous graft creation, the concept of cannulating a superficialized artery for arterial outflow in dialysis sessions has been adopted as a tertiary alternative. However, its long-term patency and complications have not been recognized widely. We report our 16-year experience with hemodialysis access creation using the brachial artery transposition (BAT) technique.

METHODS

This single-center retrospective study included consecutive patients who underwent BAT for hemodialysis vascular access between June 1, 2006, and December 31, 2022. The patency of the whole access circuit and the transposed brachial artery itself was evaluated independently.

RESULTS

In total, 193 surgical procedures were included. The success rate was 93.2%. The mean operative time was 128 minutes. The median interval from access placement to first cannulation was 21 days. The primary patency rates for BAT were 92.3%, 91.3%, 90.3%, 86.1%, and 71.9% at 1, 2, 3, 5, and 10 years, respectively. The secondary patency rates for BAT were 96.3%, 96.3%, 95.0%, 90.1%, and 74.9% at 1, 2, 3, 5, and 10 years, respectively. The primary patency rates for the whole access circuit were 61.4%, 49.2%, 45.8%, and 26.9% at 1, 2, 3, and 5 years, respectively. The secondary patency rates for the whole access circuit were 85.1%, 83.3%, 82.0%, and 68.6% at 1, 2, 3, and 5 years, respectively. The overall patient survival rates were 79.6%, 69.6%, 54.6%, 36.5%, and 13.4% at 1, 2, 3, 5 and 10 years, respectively. The abandonments of BAT were brachial artery thrombosis (n = 6), pseudoaneurysm (n = 2), aneurysmal change (n = 1), and other reasons (n = 1). The abandonments of the whole access circuit were exhaustion of venous return (n = 26), abandonment of BAT (n = 7), and other reasons (n = 2). Complications were exhaustion of venous return (n = 26), aneurysmal change (n = 12), pseudoaneurysm (n = 6), brachial artery thrombosis (n = 7), impaired wound healing (n = 19), lymphorrhea (n = 9), skin infection (n = 5), hematoma on cannulation (n = 3), and reduced peripheral blood flow (n = 2).

CONCLUSIONS

The patency of BAT was excellent, and that of the whole access circuit was adequate, with a few complications. BAT is an effective alternative from a long-term perspective for patients who are unsuitable for conventional hemodialysis access creation.

The influence of near-infrared therapy on arteriovenous fistula patency in haemodialysis patients: A multicentre, randomised, controlled clinical trial

BACKGROUND

Arteriovenous fistula (AVF) is the preferred vascular access for patients undergoing haemodialysis (HD). AVF malfunction remains a major clinical problem and is a significant independent risk factor for death. Although far-infrared (FIR) therapy has been shown to reduce complications and improve the patency rate of AVFs in various studies, it has been cautiously recommended by the Kidney Disease Outcome Quality Initiative (KDOQI) guidelines for AVF care due to insufficient evidence. Therefore, it is necessary to identify more effective methods for preventing AVF dysfunction. Many in vitro studies and few clinical studies have examined the effects of near-infrared (NIR) therapy on the vasculature. This study will examine the effects of NIR therapy on AVF.

METHODS

A randomised, controlled, open-label, multicentre trial will compare the effect of NIR on AVF patency after 1 year of therapy with that of a control group of patients with existing AVF. One group of patients received NIR treatment above their AVFs, whereas the control group received regular care. The primary outcome is the primary fistula patency rate within 12 months. In addition, acute changes in inflammatory, vasodilatory and haemodynamic parameters after a single treatment in the first 40 participants will be examined. This study was registered in the Clinical Trials Registry (ChiCTR2300071305) at https://register.clinicaltrials.gov/.

DISCUSSIONS

This study will explore the long-term and acute effects of NIR on AVFs. The study findings will provide information that can be used to develop new technical support for the prevention of AVF dysfunction in patients undergoing haemodialysis.

Assessment of volume flow rate in arteriovenous fistulas with a novel ultrasound Doppler device (earlybird): Trend analysis, comparison of methods, and inter- and intra-rater reliability

BACKGROUND

An accessible tool is required to analyze volume flow trends in arteriovenous fistulas for hemodialysis. Earlybird, an easy-to-place ultrasound Doppler device, has shown comparable accuracy to duplex ultrasound. In this study, we compared volume flow measurements obtained with duplex ultrasound and the dilution technique to an enhanced earlybird device, featuring a dual Doppler probe system, eliminating the requirement for a known insonation angle.

METHODS

Nine patients with a distal radiocephalic arteriovenous fistula were monitored for 12 months with regular volume flow measurements. Correlation and inter- and intra-class reliability analyses were conducted.

RESULTS

An overall moderate correlation was observed between earlybird and duplex ultrasound or dilution technique (intraclass correlation coefficient = 0.606 (95% confidence interval 0.064, 0.721) and 0.581 (0.039, 0.739), respectively). Duplex ultrasound compared to dilution measurements, demonstrated an overall moderate correlation (0.725 (0.219, 0.843)). Correlation between earlybird and duplex ultrasound was stronger for the arteriovenous fistula (0.778 (0.016, 0.901)) than the brachial artery (0.381 (-0.062, 0.461)). For earlybird, inter-rater reliability was excellent for the arteriovenous fistula (0.907 (0.423, 0.930)) and poor for the brachial artery (0.430 (0.241, 0.716)). Duplex ultrasound showed a good inter-rater reliability (arteriovenous fistula: 0.843 (0.610, 0.871), brachial artery: 0.819 (0.477, 0.864)). The overall intra-rater reliability was good for duplex ultrasound (rater A: 0.893 (0.727, 0.911); rater B: 0.853 (0.710, 0.891)), while excellent for earlybird (rater A: 0.905 (0.819, 0.928); rater B: 0.921 (0.632, 0.969)).

CONCLUSION

We observed a weaker correlation in the measurements of volume flow rates in arteriovenous fistulas when obtained using earlybird compared to dilution technique, unlike the comparison between duplex ultrasound and the dilution technique. However, inter-rater reliability for the arteriovenous fistula was excellent with earlybird and good with duplex ultrasound, indicating the potential of earlybird as a tool for frequent measurements, enabling trend surveillance and predicting adverse outcomes.

Novel classification of proximal forearm perforator vein in the planning and creation of percutaneous and surgical Gracz-type arteriovenous fistulae

BACKGROUND

The perforator vein determines whether it is feasible to create a percutaneous (pAVF) or surgical "Gracz-type" arteriovenous fistula (sAVF). Creating a standard anatomic classification of the antecubital region is beneficial to both the selection of the appropriate device and/or procedure and technical outcomes. Accordingly, an analysis of a large cohort of patients undergoing pAVF/sAVF was performed, focusing on perforator vein anatomical suitability, and a novel anatomical classification of the antecubital region was developed and proposed.

METHODS

Between August 2018 and July 2022, chronic or end-stage kidney disease patients as well as patients anticipated an initiation of apheresis, who were referred for vascular access planning, underwent a standardized evaluation of upper extremities. A vessel mapping summary detailing the vasculature and the access creation plan was completed, indicating the anatomical suitability for sAVF and pAVF (Ellipsys and WavelinQ) techniques.

RESULTS

Of 524 patients, 36.5% were female (average age 65 years). 53.2% were on dialysis, 41.6% had diabetes, and 13.2% had a previously failed permanent dialysis access. The anatomy for successful pAVF creation was judged to be suitable in 54% of patients for an Ellipsys-pAVF, and 29.8% for WavelinQ-pAVF. Of the WavelinQ group, 54.4% had suitable anatomy for ulnar, 26.9% for radial, and 18.6% for both ulnar/radial anastomoses. Additionally, 60.7% had suitable anatomy for pAVF creation with at least one of the systems, while 22.5% were suited for both types of pAVF-systems. 80.3% were candidates for creation of a Gracz-AVF.

CONCLUSION

Overall, we found that about 60% of patients are likely candidates for a pAVF, with 80% being candidates for creation of a Gracz-AVF. Male patients have significantly higher suitability for most types of AVF creation, and younger patients are more suitable for Ellipsys-pAVF and RCAVFs. Most importantly, a universal classification of perforator vein was developed, which is indispensable in modern vascular access planning.

A rare hemodialysis vascular access complication-Internal jugular vein reflux

Hemodialysis (HD) arteriovenous fistulas commonly present with late vascular access complications, but are rarely in association with internal jugular vein (IJV) reflux. We reported two patients who had severe and mild IJV reflux, respectively. Case 1 was a 48-year-old male with end-stage renal disease (ESRD) who had been treated with HD for 5 years. He presented with persistent headaches, nausea, and vomiting. Combined with all the examinations, it was revealed severe IJV reflux, brachiocephalic vein stenosis, high-flow vascular access, and IJV valve dysfunction. Case 2 was a 59-year-old female with ESRD who had constructed an AVF for 4 months and had been on HD for only 1 day. She presented with dizziness and nausea after the first hemodialysis and duplex ultrasonography showed slightly continuous IJV reflux, high-flow vascular access, and IJV valve dysfunction. Furthermore, we reviewed 16 case reports to identify the characteristics of IJV reflux in HD patients. IJV reflux in HD patients may be caused by high-flow access, central venous stenosis or occlusion, and valve dysfunction. Severe IJV reflux can develop neurological symptoms secondary to intracranial venous reflux in this article. Etiological treatment is helpful for these patients, but there is a risk of recurrence.

Influence of renin-angiotensin system blockades on vascular access survival in patients on maintenance hemodialysis

INTRODUCTION

Results on the association between the use of renin-angiotensin system blockades (RASBs) and vascular access-related outcomes are inconsistent. We aimed to compare vascular access-related outcomes according to the use of RASBs in hemodialysis patients.

METHODS

This study used data from a national hemodialysis quality assessment program of the Republic of Korea (n = 54,903). Group 1 was not prescribed any blood pressure-lowering drugs (n = 28,521). Group 2 was prescribed other blood pressure-lowering agents except for RASBs (n = 9571). Group 3 was prescribed RASBs (n = 16,811). Vascular access-related outcomes were classified into intervention-free survival (IFS), thrombosis-free survival (TFS), and vascular access survival (VAS).

RESULTS

No significant difference in the three access survival rates was identified among the three groups. The multivariate Cox regression analyses indicated that Group 3 had better outcomes in IFS and TFS than Group 1. The numbers of angioplasties performed were significantly greater in Group 1 than in the other two groups. The numbers of thrombectomies performed were significantly the lowest in Group 3 among all the groups.

CONCLUSIONS

Our study revealed different results according to types of access survival in univariate or multivariate analyses. The association of RASBs with favorable outcomes in vascular access remains unclear.

Risk factors for in-stent restenosis in maintenance hemodialysis patients with central venous occlusive disease and biomechanical assessment of stents

OBJECTIVES

To investigate the risk factors and biomechanical mechanisms of in-stent restenosis (ISR) in central venous occlusive disease (CVOD).

PATIENTS AND METHODS

This retrospective study consecutively included 77 maintenance hemodialysis (MHD) patients with CVOD who received the first percutaneous transluminal angioplasty with stenting (PTS) due to symptomatic CVOD in a tertiary hospital. The mean age was 59.7 ± 14.0 years, and 51.9% of patients were male. The clinical characteristics, occurrence of ISR and patency rates were recorded. Finite element method was applied to assess the biomechanical properties of stents.

RESULTS

Among 77 patients with a mean CVS score of 8.0 ± 2.8, 20.8%, 62.3%, and 16.9% of patients had the main vein of CVOD in the subclavian vein, brachiocephalic vein, and superior vena cava, respectively. A total of 72 (93.5%) patients received successful PTS treatment, for which the stents implanted were mainly Fluency covered stent (48.6%) and SMART bare stent (31.9%). During 15 (10-24)-months of follow-up, ISR occurred in 36.1% of the 72 patients. The primary and assisted primary patency rates at 6, 12, and 18 months were 78%, 56%, 42% and 95%, 90%, 87%, respectively. A prolonged dialysis vintage was an independent risk factor for ISR, yet the stent type or the main vein location was not correlated with ISR. Among three laser-engraving stents, the SMART stent was the best in terms of flexibility, stress, and strain on stents but worst in stress or strain on vessels. The Luminexx stent was the best in radial force and worst in stress or strain on stents. The Vici stent was the best in stress and strain on vessels and worst in radial force and flexibility.

CONCLUSIONS

An unsatisfactory comprehensive biomechanical performance from configurations rooted in existing stents may account for the high incidence of ISR in CVOD.

The difference in diameter between radial artery and cephalic vein correlates with primary patency of radio-cephalic arteriovenous fistula

INTRODUCTION

Autogenous radio-cephalic arteriovenous fistula (RCAVF) is preferred for chronic hemodialysis access. However, RCAVF still suffers from disappointing survival due to fistula dysfunction, with intimal hyperplasia (IH) as an underlying cause of this condition. The inconsistency of radial artery diameter (DRA) and cephalic vein diameter (DCV) is one of the factors affecting the shear disturbance, which is believed to trigger the onset of IH. However, there are no reports correlating the difference in DRA and DCV with RCAVF outcomes.

METHODS

This was a retrospective cohort study. Consecutive patients (n = 233) with a new RCAVF created were included if they underwent duplex ultrasound examination to evaluate preoperatively the radial artery diameter (DRA) and cephalic venous diameter (DCV). We then calculated radial artery-cephalic vein diameter difference (DCV minus DRA, termed DCV-DRA hereafter) and evaluated the association of the preoperative DCV-DRA with primary patency of RCAVF at 12 months. Subgroup analysis was also performed to explore effect modification by age, gender, radial artery diameter, and cephalic vein diameter with DCV-DRA.

RESULTS

After adjusting for age, gender, weight, and mean arterial pressure, the preoperative DCV-DRA was associated with primary patency of RCAVF at 12 months (adjusted Odds ratio [aOR], 1.524 per 1-mm increase; 95% confidence interval [95% CI], 1.048-2.218). The primary patency of RCAVF at 12 months was achieved in 69.4%, 71.8%,and 87.3% of patients with a preoperative DCV-DRA of ⩽-0.6 mm, (-0.5)-0.5 mm, and ⩾0.6 mm, respectively. P for trend was 0.029. Patients with DCV-DRA of ⩾0.6 mm had a much higher chance of 12-month patency than patients with DCV-DRA of ⩽-0.6 mm (aOR, 3.574; 95% CI, 1.276-10.010). Age, gender, radial artery diameter, and cephalic vein diameter did not modify the association of DCV-DRA with primary patency of RCAVF at 12 months.

CONCLUSIONS

Preoperative DCV-DRA may be an under-recognized predictor of RCAVF patency.

Y-shaped stenting of brachiocephalic vein in a symptomatic hemodialysis patient

Stenosis or obstruction of neck great veins represent a frequent and severe complication in hemodialysis patients. Endovascular treatment with percutaneous transluminal angioplasty and/or stenting of these veins is the gold standard to restore patency. However, the jugular vein is frequently overstented in these cases and this might lead to persistent symptomatology of those patients also losing an access for future catheter placement. Herein, we present the 6-months performance of a Y-shaped stenting of the brachiocephalic and internal jugular vein leading to complete resolution of the symptoms, and maintenance of the jugular vein access.

A meta-analysis of vascular access outcomes in hemodialysis patients aged 75 years or older

BACKGROUND

Several existing guidelines advocate the access creation without any specific recommendations for those patients over 75 years of age. The aim of this meta-analysis is to compare the outcomes of different vascular access procedures in the sub-group of elderly ESRD patients ⩾75 years of age.

METHODS

A literature search was performed using the MEDLINE and SCOPUS electronic databases. The analysis focused on studies with subgroups of elderly patients ⩾75 years of age with different vascular access procedures, and compared the failure rates of autologous versus prosthetic vascular access. Articles comparing patency rates of distal (forearm) versus proximal upper arm AVFs were also investigated.

RESULTS

Twelve relevant studies were identified and included in the meta-analysis. The pooled results revealed a statistically significant unassisted (primary) failure rate at 24 months in favor of autologous AVFs [odds ratio (OR): 0.56, 95% CI: 0.38-0.83, p = 0.003]. A secondary analysis revealed significantly higher 12 months unassisted (primary) and secondary failure rates of forearm AVFs compared with proximal upper arm AVFs (OR: 2.14, 95% CI: 1.53-2.97, p < 0.00001 and OR: 1.76, 95% CI: 1.12-2.78, p < 0.01 respectively).

CONCLUSION

An increased risk of failure of prosthetic vascular access procedures was found compared with autologous AVFs in patients ⩾75 years of age. Elderly patients ⩾75 years should not be excluded from creation of an autologous access, with proximal upper arm AVFs having better patency rates.

Comparing post-maturation outcomes of arteriovenous grafts and fistulae

BACKGROUND

Though arteriovenous grafts (AVG) mature more reliably than arteriovenous fistulae (AVF) and require fewer maturation procedures (MP) to obtain functional patency, AVG are thought to have worse function after maturation. We explored differences in post-maturation outcomes between the following groups: AVF patients who did (AS-AVF) and did not (unAS-AVF) require assisted maturation and AVG patients who did (AS-AVG) and did not (unAS-AVG) require assisted maturation.

METHODS

Using the US Renal Data System (2012-2017), we retrospectively identified patients who initiated dialysis with a central venous catheter, underwent AVF or AVG placement and achieved successful two-needle cannulation. Primary patency and access abandonment after maturation were compared across groups using competing risks regression methods, generating sub-hazards ratios (sHR).

RESULTS

We identified 42,664 AVF and 12,335 AVG that met inclusion criteria. A larger proportion of AVFs required interventions: 18,408 AVF (43.2%) versus 2594 AVG (21.0%; p < 0.01). Both AS-AVG and AS-AVF patients experienced patency loss at 1 year more frequently compared with unAS-AVG (67.5% & 57.5% vs 55.2% respectively). Patency loss was lowest in unAS-AVF (38.9%). These trends were robust on adjusted analysis (unAS-AVG reference, AS-AVG sHR = 1.44, p < 0.01; AS-AVF sHR = 1.08, p < 0.01, unAS-AVF sHR = 0.67, p < 0.01). AS-AVGs were more likely to be abandoned than unAS-AVGs (11.7% unAS-AVG vs 17.2% AS-AVG). Fistulae, assisted or not, had lower unadjusted rates of 1-year abandonment than grafts (8.9% AS-AVF vs 7.3% unAS-AVF). On adjusted analysis, AVF usage was protective against abandonment (unAS-AVG, reference; AS-AVF sHR = 0.67, p < 0.01; unAS-AVF sHR = 0.59, p < 0.01) while AS-AVG was not (AS-AVG sHR = 1.32, p < 0.01).

CONCLUSIONS

unAS-AVF have the best long-term outcomes. AS-AVF lose primary patency at a higher rate than unAS-AVG. AVGs may be a better choice than AVFs if veins are marginal and likely to require assisted maturation. Further research is needed to identify anatomic and physiologic factors that affect long-term performance and influence conduit choice.

The impact of stent-graft sizing on venous stenosis re-intervention and arteriovenous graft patency: Free-floating stent outflow is associated with improved outcomes

BACKGROUND

Early cannulation arteriovenous grafts (ecAVG) for dialysis access are limited by reintervention for venous stenosis (VS) despite their good initial patency. Whilst stent-grafts (SG) have shown promise, the optimal sizing is unclear. Therefore, this study aims to determine if outflow vein diameter, SG diameter or these relative to each other (V:Sr) alters outcomes, and if so, which is more important.

METHODS

Retrospective analysis was performed of Gore® Acuseal® ecAVGs with VS treated with Gore® Viabahn® SG over a 7-year period. Primary patency (PP), time to thrombosis and functional patency were analysed by SG length/diameter, vein diameter and V:Sr.

RESULTS

We identified 114 ecAVGs with median follow-up 492 days (IQR 189-770). SG length and diameter did not correlate with PP, however, there was a significant relationship between vein diameter and PP (RR = 0.901 (0.832-0.975), p = 0.01) and between V:Sr and PP (RR = 0.462 (0.255-0.838), x2 = 5.866, p = 0.0015). The optimal V:Sr was ⩾1.4 (i.e. vein diameter at least 40% greater than the stent-graft; or 'free-floating' stent outflow) (RR = 2.759 (1.670-4.558), p < 0.001), translating to a difference in median PP of 252 versus 496 days (IQR: 188-316; 322-670). On multivariate analysis, absolute vein diameter lost significance, whilst V:Sr remained an independently significant predictor of PP (RR = 3.247 (1.560-6.759), p = 0.02).

CONCLUSIONS

Placement of the SG outflow into a relatively larger segment of vein was associated with a significant increase in PP independent of the absolute vein diameter. This suggests that larger calibre SG which are apposed to the vein wall are not required for optimal primary patency, and indeed should be actively avoided. Instead, a 'free-floating' stent outflow which is undersized relative to the recipient vein (whilst maintaining a minimum anchoring calibre) is recommended where possible. This should be considered during intervention and may require selection of longer devices, where practical, to bring the stent outflow into a larger vein segment.

LEVEL OF EVIDENCE

Level 3a, Non-randomised controlled cohort/follow-up study.

A scoping review on surgical reduction of high flow arteriovenous haemodialysis access

Volume flow (Qa) > 1.5-2 l /minQa in arteriovenous accesses may be associated with high flow related systemic or locoregional complications. A variety of surgical techniques are advocated for Qa reduction. Aim of this scoping review is to provide an overview of available evidence regarding the efficacy of this broad spectrum of interventions for Qa reduction in patients with a high flow haemodialysis access. PubMed and Embase were searched according to PRISMA-guidelines. Studies on invasive management of HFA were selected. Inclusion required an English description of surgical techniques in human HFAs including pre- and postoperative access flow-values. Sixty-six studies on 940 patients (mean age 56 years (3-90 years), male 62%, diabetes mellitus 26%, brachial artery-based arteriovenous access 65%) fulfilled inclusion criteria. Performed techniques were banding (58%), revision using distal inflow (12%), plication/anastomoplasty (10%), graft interposition (5%), proximal radial artery ligation (3%), aneurysm repair (4%), or miscellaneous other techniques (8%). Definition of HFA, work-up, indication for surgery and intraoperative monitoring were diverse. All techniques reduced Qa on the short term (mean drop 0.9-1.7 l/min). Secondary access patency rates varied between 70% and 93% (mean follow-up 15 (0-189) months). Definitions of success and recurrence varied widely precluding a comparison of efficacy of techniques. Patient specific factors legitimizing invasive treatment for HFA are discussed. Recommendations on reporting standards when dealing with HFA surgery are provided. In conclusion, the present report on the current management of high flow access does not allow for drawing any definite conclusions due to a lack of standardization in definition, indications for surgical intervention and techniques. Randomized trials comparing different Qa reducing techniques in symptomatic patients are warranted, as are trials comparing a wait-and-see approach versus Qa reduction in asymptomatic patients. As an overview of the variety of techniques was lacking, this scoping review might serve as a map for future researchers.

Outcomes of stent grafts for treatment of central venous disease in hemodialysis patients

BACKGROUND

To evaluate the effectiveness of stent graft (SG) for the treatment of central venous disease (CVD) in hemodialysis patients.

METHODS

Between January 2014 and April 2022, 122 patients on hemodialysis with symptomatic CVD were treated with percutaneous transluminal angioplasty (PTA) and bare-metal stent (BMS) or SG placement. The mean follow-up was 14.5 months (IQR: 8.0, 24.2). Patency rates of the target sites were calculated using Kaplan-Meier and log-rank studies. Multivariate Cox proportional hazard models were used to evaluate the association between various characteristics and target site primary patency.

RESULTS

Technical success rate was 100%. At 3, 6, 12, and 24 months, the target sites primary patency rates were 86.4%, 74.2%, 45.1%, and 30.4% for PTA; 94.7%, 78.6%, 60.8%, and 45.6% for BMS; and 94.0%, 92.0%, 82.4%, and 66.8% for SG, respectively, and the assisted primary patency rates were 86.5%, 80.4%, 63.8%, and 46.0% for PTA; 94.7%, 89.5%, 77.5%, and 71.1% for BMS; 100%, 100%, 97.8%, and 83.4% for SG, respectively. The Kaplan-Meier analysis indicated that SGs achieved better primary and assisted primary patency than PTA or BMS (p<0.05). SG use and concomitant stenosis were the independent predictors of target site primary patency dysfunction in the multivariate analysis.

CONCLUSIONS

This study confirmed the better long-term patency of SG in comparison with PTA and BMS for the treatment of CVD in hemodialysis patients.

Doppler ultrasound assessment of calcified radial arteries prior to radio-cephalic arterio-venous fistula placement: an observational study

BACKGROUND

In elderly and diabetic patients, arterial calcifications are prevalent and result in worse outcomes of arterio-venous fistulas (AVFs). Optimal ultrasound criteria for assessment of calcified arteries are unknown. We report our experience with ultrasound assessment of calcified arteries prior to placement of radio-cephalic (RC) AVFs.

MATERIAL AND METHODS

We included 85 patients in whom a RC-AVF placement was planned. Patients were divided according to the presence of radial artery calcifications into a calcified group (moderate/severe calcifications, N = 18) and control group (no changes/mild atherosclerosis, N = 67). Doppler ultrasound parameters were analyzed in the calcified group with focus on assessment of the artery, including grading of calcifications and Doppler measurements at rest and during reactive hyperemia (RH).

RESULTS

In the calcified group mean patients' age was 72 ± 11 years, 72% were diabetics, mean resistance index (RI) during RH was 0.78 ± 0.09 (range 0.63-0.90). In 14 (78%) patients an AVF was successfully placed and in 12 it matured (67% maturation rate). A lower RI at rest was observed in the primary failure sub-group with high area under the ROC curve (0.89) and a cut-off value of 0.90 for RI. There was no difference in RI at RH between failed and matured AVFs. 1-year secondary patency was 66% and in eight patients with follow-up ultrasound available, blood flow was 350-1300 ml/min. For comparison, in the control group a radio-cephalic AVF was placed in all patients, primary failure rate was 6%, maturation rate 85% and 1-year secondary patency was 77%.

CONCLUSIONS

Our very limited experience suggests that successful RC-AVF placement and maturation with good 1-year patency rates is possible in patients with moderately/severely calcified arteries and RI during RH of up to 0.90.

Axillary necklace graft salvage of a locally infected Haemodialysis with Reliable Outflow (HeRO®) graft

BACKGROUND

A 48-year-old patient presented 4 months after insertion of a right sided Haemodialysis with Reliable Outflow (HeRO®, Merit Medical) graft with a discharging abscess at the site of the brachial artery anastomosis. There was localised involvement of the arterial Gore® Acuseal inflow graft that necessitated its removal. The venous outflow component was thought salvageable as infection was well localised to the region of the antecubital fossa.

OBJECTIVES

Alternative access options were limited so we sought to preserve the venous outflow portion of the patient's original graft - minimising tissue damage and avoiding the need for a dialysis line.

METHODS

The infected arterial graft was excised, leaving behind the original SuperHero® connector and venous graft. A left sided tunnelled axillary necklace technique was utilised to restore arterial inflow.

RESULTS

After a four-day recovery, the patient went on to successfully resume their usual haemodialysis regimen without any complications. Convalescent imaging, repeat blood cultures, and monitoring of inflammatory markers showed no signs of residual infection at 6 weeks.

CONCLUSIONS

The originality of this case was the way in which an axillary necklace inflow graft was connected to the pre-existing venous outflow portion of the HeRO® haemodialysis graft system, allowing the excision of the infected inflow graft at the brachial anastomosis. This technique could be viewed as an effective salvage procedure as it allowed the venous outflow portion of the original graft to remain in situ, minimised tissue damage and enabled the patient to swiftly resume haemodialysis without the need for a line.

Zero upper arm hemodialysis fistulas: utopian or realistic goal?

BACKGROUND

Although distal native fistula is the best first-line vascular access (VA), upper arm fistula (UAF) prevalence is increasing worldwide, except in Japan. Our previous survey on 50% of hemodialysis patients (HP) revealed a prevalence of UAF of less than 5%, which is lower than the findings published by the DOPPS 5 study in our country. We analyzed the VA prevalence on 100% of HPs from our department.

METHODS

In December 2021, we investigated the prevalence of vascular access of 1295 hemodialysis patients from 17 dialysis factories. VAs were classified according to location into distal forearm fistula (DFF), middle-proximal forearm fistula (MPFF), and UAF. The department manages VA using a Hub and Spoke model. The hub performs simple and complex VA including Graft placement, the Percutaneous Transluminal Angioplasty (PTA) of fistulas and central stenosis, and the surgical and endovascular rescue of thrombosed or stenotic fistulas. The spokes perform mainly simple DFFs.

RESULTS

The mean age of 1295 HP (35% females and 21% diabetics) was 69 ± 12.4 years; 506 (39%) were over 75 years old. The prevalence of DFF, MPFF, UAF, GRAFT, and CVC was 63.5%, 10.1%, 3%, 0.7%, and 22.5%, respectively. Data comparison between our two surveys revealed a lower MPFF, UAF, and GRAFT prevalence and increased CVC prevalence. Patients aged 75 years or older, women, and diabetics showed a higher frequency of CVC and a lower prevalence of DFF.

CONCLUSIONS

The findings confirm the low prevalence of UAF found in our prior survey, demonstrating that UAFs can be reduced to 5% or less, as seen in Japanese experience.

Association of anesthetic modality and other variables on 1-year functional patency of cephalic-based arteriovenous fistulae

OBJECTIVE

Some studies suggest that regional anesthesia provides better patency for arteriovenous fistula (AVF) for hemodialysis access as compared to local and general anesthesia. This study evaluates the impact of anesthetic modality on long term fistula function at 12 months.

METHODS

A retrospective review of patients undergoing cephalic vein-based hemodialysis access in consecutive cases between 2014 and 2019 was conducted from five safety net hospitals. The primary endpoint was functional patency at 12 months. Subset analysis individually evaluated cephalic-based lower forearm and wrist vs upper arm AVFs. Bivariate and multivariate logistic regression models evaluated the relationship between anesthetic modality and fistula function at 12 months.

RESULTS

There were 818 cephalic-based fistulas created during the study period. The overall 12-month functional patency rate was 78.7%, including an 81.3% patency for upper arm AVF and 73.3% for wrist AVF (P = .009). There was no statistically significant difference among patients with functional and nonfunctional AVFs at 12 months with respect to anesthetic modality when comparing regional, local, and general anesthesia (P = .343). Multivariate regression analysis identified that history of AVF/arteriovenous graft (odds ratio [OR], 0.24; P = .007), receiving intraoperative systemic anticoagulation (OR, 2.49; P < .001), and vein diameter (OR, 1.85; P = .039) as independently associated with AVF functional patency at 12 months.

CONCLUSIONS

There was no association between anesthetic modality and functional patency of cephalic-based AVFs at 12 months. Further studies are needed to better define which patients may benefit from regional anesthesia.

Arteriovenous Fistula Closure Using a Simple Ligation Technique After Kidney Transplantation

BACKGROUNDS

There are advantages and disadvantages with closure of an arteriovenous fistula (AVF) after kidney transplantation, but some cases require closure. The general procedure for closure is angioplasty with exposure of the anastomotic site, but this is often time-consuming and complicated. We have developed a simpler, less invasive, and shorter procedure for AVF closure, in which the anastomotic site itself is not peeled off and the outflow vein close to this site is ligated using 1-0 silk. In this study, we examined the utility of this procedure.

METHODS

A retrospective case series study was conducted by review of electronic medical records of patients and surgeries. All patients (n = 52) who underwent AVF closure after kidney transplantation at our hospital between January 2008 and April 2021 were reviewed. Perioperative and long-term postoperative results were examined. This study was carried out following the ethical standards of the Declaration of Helsinki and Istanbul. Donors were not from prisoners, or from those individuals who are coerced of paid.

RESULTS

Simple ligation was performed for 46 patients (88.5%). The median time after renal transplantation was 40 (24.5-66.5) months. Median operative time and blood loss were 20 (12.2-30) minutes and 10 (5-15) mL, respectively. Two patients (4.3%) developed the aneurysm after the AVF closure using the simple ligation.

CONCLUSION

The simple ligation technique had a relatively shorter operative time and only 2 cases had aneurysm formation. These results suggest that this technique is an option for closure of an AVF after kidney transplantation.

Improving accuracy of vascular access quality classification in hemodialysis patients using deep learning with K highest score feature selection

OBJECTIVE

To develop and evaluate a novel feature selection technique, using photoplethysmography (PPG) sensors, for enhancing the performance of deep learning models in classifying vascular access quality in hemodialysis patients.

METHODS

This cross-sectional study involved creating a novel feature selection method based on SelectKBest principles, specifically designed to optimize deep learning models for PPG sensor data, in hemodialysis patients. The method effectiveness was assessed by comparing the performance of multiple deep learning models using the feature selection approach versus complete feature set. The model with the highest accuracy was then trained and tested using a 70:30 approach, respectively, with the full dataset and the SelectKBest dataset. Performance results were compared using Student's paired t-test.

RESULTS

Data from 398 hemodialysis patients were included. The 1-dimensional convolutional neural network (CNN1D) displayed the highest accuracy among different models. Implementation of the SelectKBest-based feature selection technique resulted in a statistically significant improvement in the CNN1D model's performance, achieving an accuracy of 92.05% (with feature selection) versus 90.79% (with full feature set).

CONCLUSION

These findings suggest that the newly developed feature selection approach might aid in accurately predicting vascular access quality in hemodialysis patients. This advancement may contribute to the development of reliable diagnostic tools for identifying vascular complications, such as stenosis, potentially improving patient outcomes and their quality of life.

Elevated Leukocyte Glucose Index Is Associated with Long-Term Arteriovenous Fistula Failure in Dialysis Patients

(1) Background: Arteriovenous fistula (AVF) is the preferred type of vascular access for dialysis in patients with end-stage kidney disease (ESKD). However, the primary patency of AVF at one year is under 70% due to several risk factors and comorbidities. Leukocyte glucose index (LGI), a new biomarker based on blood leukocytes and glucose values, has been found to be associated with poor outcomes in cardiovascular disease. The aim of this study is to analyze the impact of LGI on the long-term primary patency of AVF following dialysis initiation. (2) Methods: We conducted a retrospective observational study in which we initially enrolled 158 patients with ESKD admitted to the Vascular Surgery Department of the Emergency County Hospital of Targu Mures, Romania, to surgically create an AVF for dialysis between January 2020 and July 2023. The primary endpoint was AVF failure, defined as the impossibility of performing a chronic dialysis session due to severe restenosis or AVF thrombosis. After follow-up, we categorized patients into two groups based on their AVF status: "functional AVF" for those with a permeable AVF and "AVF failure" for those with vascular access dysfunction. (3) Results: Patients with AVF failure had a higher prevalence of atrial fibrillation (p = 0.013) and diabetes (p = 0.028), as well as a higher LGI value (1.12 vs. 0.79, p < 0.001). At ROC analysis, LGI had the strongest association with the outcome, with an AUC of 0.729, and an optimal cut-off value of 0.95 (72.4% sensitivity and 68% specificity). In Kaplan-Meier survival analyses, patients in the highest tertile (T3) of LGI had a significantly higher incidence of AVF failure compared to those in tertile 1 (p = 0.019). Moreover, we found that patients with higher baseline LGI values had a significantly higher risk of AVF failure during follow-up (HR: 1.48, p = 0.003). The association is independent of age and sex (HR: 1.65, p = 0.001), cardiovascular risk factors (HR: 1.63, p = 0.012), and pre-operative vascular mapping determinations (HR: 3.49, p = 0.037). (4) Conclusions: In conclusion, high preoperative values of LGI are positively associated with long-term AVF failure. The prognostic role of the biomarker was independent of age, sex, cardiovascular risk factors, and pre-operative vascular mapping determinations.

Lipectomy as an alternative for superficialization of autologous AVF in obese patients: experience of a referral center in Amazon

Background

The preferred vascular access for hemodialysis is a native arteriovenous fistula (AVF) because it offers the best results in the short and long terms, lower morbidity and mortality, and has additional advantages in relation to central venous catheters or arteriovenous grafts. However, obesity can present an additional challenge because of the barrier of subcutaneous cellular tissue covering the surface of the vein to be punctured.

Objectives

The authors review their experience with excision of subcutaneous tissue (lipectomy) overlying upper arm cephalic vein arteriovenous fistulas in obese patients.

Methods

Consecutive vascular access patients undergoing lipectomy for cannulation with difficult access because of vein depth were reviewed. Cephalic vein depth was measured by ultrasound in all cases.

Results

Twenty-two patients were reviewed (15 men and 7 women), with a mean body mass index of 34.0 kg/m2 (range: 28-40 kg/m2). Mean age was 58.4 years. The mean preoperative vein depth of 7.9 mm (range: 7.0-10.0 mm) was reduced to 4.7 mm (range: 3.0-6.0 mm) (P 0.01). The mean follow-up period for patients was 13.2 months. Four patients were lost to follow-up and four died during the period due to causes unrelated to vascular access.

Conclusions

Obesity should not be a limiting factor to creation of a native AVF, since lipectomy is a relatively simple option for superficialization, enabling functioning native and deep arteriovenous fistulas in obese patients.

The Tunnelled Atrial Catheter: A Promising Solution for Vascular Capital Depletion in Dialysis despite Associated Thrombi

Introduction

Longer survival in dialysis led to a higher incidence of vascular access complications and failure. With the limited access to kidney transplantation programs and peritoneal dialysis, exhaustion of vascular access for hemodialysis is an increasingly common situation. Among the available options, atrial tunneled dialysis catheter (ATDC) has been reported as an effective vascular access in this population. Methodology. We report the experiences of two nephrology centers in Tunis with ATDC as an ultimate vascular access for dialysis. Case Reports. Two patients with exhausted vasculature underwent ATDC insertion in 2020 and 2022, respectively, as a vascular access of last resort. Both patients underwent CRBI, which resolved with favorable outcomes. One case was complicated by post-operative thrombosis and was successfully treated with thrombolysis. Both patients are currently on dialysis via their ATDC with a catheter patency of 29 months.

Conclusion

ATDC is a life-saving and safe vascular access in cases of depleted vasculature. Little more than 50 cases have been reported in the literature during the last 30 years. As the frequency of vasculature exhaustion is expected to increase, preservation of veinous access in patients at risk of chronic kidney disease have never been more crucial.

Off-the-Shelf Synthetic Biodegradable Grafts Transform In Situ into a Living Arteriovenous Fistula in a Large Animal Model

Current vascular access options require frequent interventions. In situ tissue engineering (TE) may overcome these limitations by combining the initial success of synthetic grafts with long-term advantages of autologous vessels by using biodegradable grafts that transform into autologous vascular tissue at the site of implantation. Scaffolds (6 mm-Ø) made of supramolecular polycarbonate-bisurea (PC-BU), with a polycaprolactone (PCL) anti-kinking-coil, are implanted between the carotid artery and jugular vein in goats. A subset is bio-functionalized using bisurea-modified-Stromal cell-derived factor-1α (SDF1α) derived peptides and ePTFE grafts as controls. Grafts are explanted after 1 and 3 months, and evaluated for material degradation, tissue formation, compliance, and patency. At 3 months, the scaffold is resorbed and replaced by vascular neo-tissue, including elastin, contractile markers, and endothelial lining. No dilations, ruptures, or aneurysms are observed and grafts are successfully cannulated at termination. SDF-1α-peptide-biofunctionalization does not influence outcomes. Patency is lower in TE grafts (50%) compared to controls (100% patency), predominantly caused by intimal hyperplasia. Rapid remodeling of a synthetic, biodegradable vascular scaffold into a living, compliant arteriovenous fistula is demonstrated in a large animal model. Despite lower patency compared to ePTFE, transformation into autologous and compliant living tissue with self-healing capacity may have long-term advantages.

A practical review of barriers and challenges to a definitive randomised trial of grafts versus fistula

A definitive randomised controlled trial of arteriovenous fistula (AVF) versus arteriovenous grafts (AVG) has been advocated for more than a decade, but as yet, none has been completed. The aim of this article is to summarise the theoretical barriers, review the difficulties in trial design and practicalities that have thus far prevented this from occurring.

Does central venous stenosis affects the brachial artery flow volume and peripheral vascular resistive index in patients on maintenance hemodialysis? A retrospective study

BACKGROUND

A well-functioning vascular access (VA) is crucial for the patients on maintenance hemodialysis (HD). Central venous stenosis (CVS) is a common, yet, overlooked complication of VA as its diagnosis is challenging. Moreover, its effect on the flow volume (FV) and the peripheral resistive index (RI) was not well discussed before. Despite the availability of doppler ultrasound (DUS) in most centers, direct visualization of central veins using DUS is quite difficult.

METHODS

This is a retrospective single-center self-controlled cohort study that was conducted in a specialized vascular access management tertiary center in Japan and included all patients with CVS who underwent percutaneous transluminal angiography (PTA) with or without vascular stenting in the period from January 2014 to September 2022. The patients were divided according to their VA type into arteriovenous fistula (AVF), and arteriovenous graft (AVG) groups, then subdivided, according to the type of stenosis, into two subgroups: CVS, and mixed central and peripheral venous stenosis (MVS) groups. The FV and RI of the feeding artery were compared in the same procedure before and after PTA to assess the impact of the procedure itself.

RESULTS

Data of 485 percutaneous transluminal angiography procedures (PTA), performed in 95 patients during the period from January 2014 to September 2022, were collected. FV and RI were significantly affected in the patients with MVS than patients with CVS. After PTA, both FV and RI were significantly improved. The improvement rate of FV and RI after PTA were significantly higher in patients with MVS than patients with CVS. However, it was difficult to determine the cut-off value to diagnose or to assess the improvement of CVS.

CONCLUSION

Our findings suggest that FV and RI measurement by DUS are good tools, along with the clinical findings for assessment of CVS in certain situations.

The ımpact of radiofrequency ablation on quality of life/symptoms (VEINES-QOL/Sym questionnaire score) in patients with chronic venous ınsufficiency

Purpose

Chronic venous insufficiency is defined as a progressive disease that impairs the quality of life. Symptomatic patients can be treated with a 97% success rate through endovenous radiofrequency ablation (RFA) procedures. The aim of this study is to evaluate the effect and impact of RFA therapy on both the Venous Insufficiency Epidemiological and Economic Study Quality of Life/Symptom Questionnaire (VEINES-QOL/Sym) scale and the VEINES-QOL/Sym severity score in patients with isolated vena saphena magna insufficiency.

Methods

Between March and June 2018, a retrospective analysis was conducted on 45 patients with a healthy vena saphena parva. They were divided into two groups based on the diameter of the great saphenous vein (GSV). Patients with GSV < 6 mm were assigned to group I (n = 22, 15 males, 7 females, mean age 52.45 ± 13.98 years), while patients with GSV ≥ 6 mm were assigned to group II (n = 23, 14 males, 9 females, mean age 55.04 ± 10.18 years). The pre-procedural Clinical-Etiology-Anatomy-Pathophysiology (CEAP) classification and post-procedural quality of life and symptom assessment at 12-24 months were evaluated using the VEINES-QOL/Sym questionnaire scale.

Results

When all patients were assessed in terms of the VEINES-QOL/Sym questionnaire scale, compared to the previous year, it was found that 57.8% of patients (n = 26) still experienced complaints, and 24.4% of patients (n = 14) reported slightly worse symptoms than the previous year. In group II, 56.5% of patients (n = 13) reported experiencing similar complaints as the previous year, while 30.4% (n = 7) noted slightly worse symptoms.

Conclusions

Our study findings revealed that the increase in vessel diameter does not significantly impact the severity of symptoms and quality of life outcomes after RFA therapy; however, it does have a notable impact on the improvement of symptom characteristics. As a result, early intervention for symptomatic patients is crucial in order to address their symptoms and improve their quality of life.

Pre-operative ultrasound mapping before arteriovenous fistula formation: an updated systematic review and meta-analysis

BACKGROUND

Arteriovenous fistula represents the preferred vascular access for patients with kidney failure requiring hemodialysis. Surgeons have traditionally used physical examination to identify the most suitable vessels. This meta-analysis aims to evaluate whether ultrasound mapping should be routinely performed before arteriovenous fistula creation.

METHODS

Medline, Scopus, Web of Science and CENTRAL were systematically searched from inception to November 1, 2022. Randomized controlled trials and cohort studies comparing routine ultrasound mapping to physical examination in terms of arteriovenous fistula patency were included. Meta-analysis was performed by fitting random-effects models. The study protocol has been prospectively registered in PROSPERO (CRD42023402390).

RESULTS

Overall, 18 studies were included, comprising 3655 participants. Routine pre-operative ultrasound mapping was associated with significantly lower rates of primary arteriovenous fistula failure (Risk Ratio-RR: 0.56, 95% confidence intervals-CI: 0.37-0.84, low certainty). A significant outcome was observed by separately pooling randomized controlled trials (RR: 0.37, 95% CI: 0.25-0.54). Routine ultrasound mapping was also associated with significantly higher rates of 1-year primary arteriovenous fistula patency (RR: 1.33, 95% CI: 1.19-1.47, moderate certainty). This effect remained significant in the analysis of randomized controlled trials (RR: 1.26, 95% CI: 1.02-1.56).

CONCLUSIONS

Implementing routine pre-operative ultrasound mapping of vessels is associated with significantly better outcomes in terms of early arteriovenous fistula failure and primary patency rates at 12 months. Further research should confirm the long-term benefits of routine ultrasound examination and evaluate its cost-effectiveness in different populations.

Assessment of the performance of vascular access for hemodialysis

BACKGROUND

Life and quality of life on hemodialysis depends on adequate vascular access. An autogenous arteriovenous fistula (AVF) has the best performance, while the use of a central venous catheter (CVC) may have a negative impact on fistula performance and may be associated with increased systemic inflammation. Our objective is to evaluate the performance of vascular accesses in patients undergoing a chronic hemodialysis program.

METHODS

This is an observational, cross-sectional, and descriptive study that included patients on chronic hemodialysis for more than 90 days. Patients with an acute systemic inflammatory disease and those with acute cardiovascular illness were excluded. Clinical data, dialysis session parameters, and serum levels of inflammatory markers were evaluated.

RESULTS

A total of 91 patients were evaluated, 59 (65%) had an AVF and 32 patients (35%) had a CVC. The adequacy rate was 67%; being 67.8% with AVF and 65.6% with CVC. Among the causes of AVF inadequacy, the ones that presented the highest prevalence ratio (PR) were non-mature AVF (PR: 4.055; 95% CI: 2.017-8.151), pseudoaneurysm (PR: 6.580; 95% CI: 3.723-11.629) and presence of hematoma (PR: 4.360; 95% CI: 2.125-8.946), p < 0.001. Among the catheter group, the causes of inadequacy with the highest PR were the presence of access thrombosis, indicating the use of thrombolytics (PR: 11.103; 95% CI: 4.746-25.977; p < 0.001) and infection (PR: 2.984; 95% CI: 1.293-6.889; p = 0.010). Median primary AVF patency was 72 months compared to 7 months of catheters (p < 0.001). There was no significant difference in serum inflammatory markers between the two groups.

CONCLUSIONS

Adequacy rates of vascular accesses did not differ between the groups, but the primary and functional patency of AVF is 10 times higher than that of catheters. Infection in dialysis catheters is associated with worse access performance. There was no association between systemic inflammation and vascular access.

Use of a Paclitaxel Drug-Eluting Stent for the Treatment of Hemodialysis Access Outflow Stenosis

PURPOSE

To evaluate the outcomes and durability of drug-eluting stents (DESs) for the treatment of hemodialysis access outflow stenosis.

MATERIAL AND METHODS

A single-center retrospective analysis was conducted of all patients with hemodialysis vascular access outflow stenosis treated with a paclitaxel-coated DES (Eluvia; Boston Scientific, Marlborough, Massachusetts) between January 2020 and July 2022. A total of 34 DESs were implanted to treat outflow stenosis in 32 patients. Primary target lesion patency after stent deployment was the main outcome. Comparison between the time interval free from target lesion reintervention (TLR) after previous plain balloon angioplasty (PBA) and that after stent deployment for the same target lesion was considered a secondary outcome.

RESULTS

The primary patency at 6, 12, and 18 months was 63.1%, 47.6%, and 41.7%, respectively. The secondary patency rate was 100% at 18 months. The median time interval free from TLR increased from 4.1 to 11.9 months (P < .001). No adverse events were observed during the median follow-up period of 387 days.

CONCLUSIONS

The patency rates after use of DES for hemodialysis access outflow stenosis were comparable with results for drug-coated balloons and stent grafts, addressing recoil and minimizing the risk of jailing by a covered stent.

Intraoperative Transit Time Flow Measurement Predicts Maturation of Radiocephalic Arteriovenous Fistulas

OBJECTIVE

The arteriovenous fistula (AVF) is the first choice for gaining vascular access for hemodialysis. However, 20-50% of AVFs fail within 4 months after creation. Although demographic risk factors have been described, there is little evidence on the intraoperative predictors of AVF maturation failure. The aim of this study was to assess the predictive value of intraoperative transit time flow measurements (TTFM) on AVF maturation failure.

METHODS

In this retrospective cohort study, the intraoperative blood flow, measured using TTFM, was compared to AVF maturation after 6 weeks in 55 patients. Due to its significantly higher prevalence and risk of non-maturation, the radiocephalic AVF (RCAVF) was the main focus of this study. A recommended cut-off point for high versus low intraoperative blood flow was determined for RCAVFs, using an ROC curve.

RESULTS

The average intraoperative blood flow in RCAVFs was 156 mL/min. Patients with an intraoperative blood flow equal or lower than the determined cut-off point of 160 mL/min, showed a 3.03 times increased risk of AVF maturation failure after 6 weeks, compared to patients with a higher intraoperative blood flow (P < .001).

CONCLUSION

The intraoperative blood flow in RCAVFs measured by TTFM provides an adequate means of predicting AVF non-maturation 6 weeks after surgery. For RCAVFs, a cut-off point for intraoperative blood flow of 160 mL/min is recommended for maximum sensitivity and specificity to predict AVF maturation failure after 6 weeks.

Midterm outcomes of arteriovenous fistula aneurysm repair with simultaneous inflow revision or outflow tract revascularization

OBJECTIVE

The aim of this study was to investigate the 2-year outcomes of extensive revisions aimed at simultaneously addressing arteriovenous fistula (AVF) aneurysms, outflow stenosis, and/or high flow volumes.

METHODS

This was a retrospective cohort study in a tertiary referral center. The study population comprised hemodialysis patients with aneurysmal AVFs requiring revision. Subjects were eligible if they were ≥18 years of age and had aneurysm repair associated with inflow revision or treatment of outflow lesions. Patients were followed-up for a minimum of 2 years, and the primary outcome measure was cumulative patency.

RESULTS

Our cohort comprised 93 patients with a mean age of 56 ± 12 years. The most frequent access type was brachiocephalic fistula (61%), and the median access age at the time of revision was 66 months (interquartile range, 46-93 months). The median access flow volume was 2300 ml/min (interquartile range, 1281-2900), and 31 subjects (33%) presented aneurysms associated with both high flow and venous obstruction. Aneurysm repair consisted of aneurysmorraphy in the overwhelming majority (95%). Inflow revision was performed in a total of 49 cases (53%), and outflow tract obstruction was treated in 71 patients (72%), with 27 patients (29%) receiving a simultaneous 3-component revision. At 2 years, the primary, primary assisted, and cumulative patencies were 60% ± 1%, 91% ± 3%, and 94% ± 3%, respectively. The most frequent indication for first-time reinterventions was outflow tract stenosis (24%). Aneurysm recurrence was observed in 13 subjects (14%) during the entire follow-up and was responsible for reinterventions in seven of them (8%), with a 2-year freedom from aneurysm-related reintervention rate of 95% ± 3%.

CONCLUSIONS

Extensive AVF revision with simultaneous aneurysm repair, inflow revision, and outflow tract revascularization is feasible, safe, and associated with favorable 2-year patency rates.

The Use of a High Flow PICC Catheter for Stem Cell and Lymphocyte Apheresis: The Initial Experience of a Pediatric Oncology Center in Brazil

BACKGROUND

Autologous hematopoietic stem cell transplant (HSCT), characterized by high intensity chemotherapy followed by the infusion of HSC previously collected from the peripheral blood, is a procedure used in the treatment of several malignancies. In pediatrics, the apheresis procedure represents a challenge, due to the need for insertion of a rigid central venous catheter (CVC) in small children. The CVC is usually used for stem cell collection and then removed. Later, the patient will need a new device for cell infusion.

AIM

We propose the use of one single catheter for both apheresis and infusion.

METHODS

We present five children between 1 and 13 years of age who underwent apheresis using a high flow PICC catheter surgically inserted.

RESULTS

All patients utilized a PICC line double lumen 5Fr (PowerPICC™ 5Fr DL BARD/USA) placed in the brachiocephalic vein tunneled on the chest, inserted under 24 h prior to apheresis to assure the devices were pervious. Three of the patients were diagnosed with solid tumor and one with acute lymphoblastic leukemia (ALL) awaiting Car-T Cell therapy. The four children who underwent autologous HSCT used the same catheter for cell infusion and remained with the catheter following discharge. The child who was submitted for Car-T Cell still awaits infusion and the catheter was removed.

CONCLUSIONS

High flow PICC is a viable alternative for apheresis to maintain an adequate flow of 5 ml/s and can be used as a single catheter throughout the HSCT process, reducing the risks from anesthesia and the catheter insertion procedure.

TYPE OF STUDY

Clinical Research.

Endovascular tools for vascular access stenosis: Flow-chart proposal

Stenosis represents the most relevant arteriovenous fistula (AVF) pathology and can affects the entire conduit forming the fistula, from afferent artery to central venous vessels. Correction of vascular access stenosis significantly affects the survival and quality of life for end stage renal disease patients (ESRD) dependent on hemodialysis. Guidelines consider the procedure of percutaneous transluminal angioplasty (PTA) relevant for the primary treatment of these lesions with excellent results in restoring AVF immediately at the end of the procedure. From first AVF angioplasty in 1981 to now, wide scientific innovation has led to development of new devices, composed by different materials and technologies, specific for the site and the type of stenosis to be treated, able to manage resistant stenotic lesion and to reduce stenosis recurrences. International guidelines do not clearly specify all treatment possibilities in the individual case. In this review the authors want to provide specific information on most used devices for stenosis treatment based on literature evidence, showing when and where to use the various tools available with flow-chart treatment proposal.

Realtime monitoring of thrombus formation in vivo using a self-reporting vascular access graft

BACKGROUND

Chronic kidney disease (CKD) affects 10% of the global population costing over a hundred billion dollars per annum and leading to increased risk of cardiovascular disease. Many patients with CKD require regular haemodialyses. Synthetic arteriovenous grafts (AVG) are increasingly used to provide rapid vascular connection for dialysis. Initially, they have excellent patency rates but are critically limited by neointimal hyperplasia at the venous anastomosis, which drives subsequent thrombosis, graft failure and death.

METHODS

Here, we describe a system in which electrical impedance spectroscopy sensors are incorporated circumferentially into the wall of a synthetic arteriovenous graft. This is combined with an implantable radiotelemetry system for data transmission outside the patient. The system was tested using monolayers of endothelial and smooth muscle cells as well as swine blood and clots with explanted human carotid artery plaques. Sensor testing was then performed in vitro and the device was implanted in vivo in female swine.

RESULTS

The device can wirelessly report the accumulation of biological material, both cells and blood. Differences are also detected when comparing controls with pathological atheroma. In swine differences between blockage formation in a graft were remotely obtained and wireless reported.

CONCLUSIONS

Combining electrical impedance spectroscopy and an implantable radiotelemetry system enables graft surveillance. This has the potential to be used for early detection of venous stenosis and blood clot formation in real-time in vivo. In principle, the concept could apply to other cardiovascular diseases and vascular implantable devices.

Therapeutic strategies based on non-ionizing radiation to prevent venous neointimal hyperplasia: the relevance for stenosed arteriovenous fistula, and the role of vascular compliance

We have reviewed the development and current status of therapies based on exposure to non-ionizing radiation (with a photon energy less than 10 eV) aimed at suppressing the venous neointimal hyperplasia, and consequentially at avoiding stenosis in arteriovenous grafts. Due to the drawbacks associated with the medical use of ionizing radiation, prominently the radiation-induced cardiovascular disease, the availability of procedures using non-ionizing radiation is becoming a noteworthy objective for the current research. Further, the focus of the review was the use of such procedures for improving the vascular access function and assuring the clinical success of arteriovenous fistulae in hemodialysis patients. Following a brief discussion of the physical principles underlying radiotherapy, the current methods based on non-ionizing radiation, either in use or under development, were described in detail. There are currently five such techniques, including photodynamic therapy (PDT), far-infrared therapy, photochemical tissue passivation (PTP), Alucent vascular scaffolding, and adventitial photocrosslinking. The last three are contingent on the mechanical stiffening achievable by the exogenous photochemical crosslinking of tissular collagen, a process that leads to the decrease of venous compliance. As there are conflicting opinions on the role of compliance mismatch between arterial and venous conduits in a graft, this aspect was also considered in our review.

First-in-human feasibility study of the aXess graft (aXess-FIH): 6-Month results

OBJECTIVE

The creation of an arteriovenous fistula (AVF) is considered the most effective hemodialysis (HD) vascular access. For patients who are not suitable for AVF, arteriovenous grafts (AVGs) are the best access option for chronic HD. However, conventional AVGs are prone to intimal hyperplasia, stenosis, thrombosis, and infection. Xeltis has developed an AVG as a potential alternative to currently available AVGs based on the concept of endogenous tissue restoration. The results of the first 6-month follow-up are presented here.

METHODS

The aXess first-in-human (FIH) study [NCT04898153] is a prospective, single-arm, multicenter feasibility study that evaluates the early safety and performance of the aXess Hemodialysis Graft. A total of 20 patients with end-stage renal disease were enrolled across six European investigational sites.

RESULTS

At 6-months follow-up, all grafts were patent with primary and secondary patency rates were 80% and 100%, respectively. Three patients required a re-intervention to maintain graft patency, while one re-intervention was required to restore patency. One graft thrombosis and zero infections were reported.

CONCLUSION

The expected advantages of the novel aXess Hemodialysis Graft over conventional AVGs would be evaluated by the analysis on long-term safety and effectiveness during the 5-year follow-up of the currently ongoing trial.

Vascular access challenges in hemodialysis patients with superior vena cava syndrome

BACKGROUND

Superior vena cava syndrome in hemodialysis patients resulting from previous or current use of a tunneled central vein catheter is a rare but potentially severe condition. Two aspects have to be addressed during management and treatment: the restoration of central venous flow and the creation of an alternative vascular access to guarantee hemodialysis.

RESEARCH DESIGN

Conforming to the current guidelines and literature, we present a stepwise approach and discuss therapeutic options. The removal of the tunneled central vein catheter should be attempted and a native vascular access created whenever feasible.

RESULTS

First, an upper extremity AVF should be preserved or, as in our case, made functional. Endovascular treatment of CVSO should primarily consist of balloon dilatation. Placement of a stent or stent graft should be considered as a secondary option. HeRO graft placement may be considered in recurrent CVSO and recanalization with a Surfacer. LL-AVF or AVG need to be discussed and may be an alternative for certain HD patients when the risk of lower limb ischemia and infection is considered.

CONCLUSION

Several therapeutic options are available and the basic principles are well established in the literature, although the level of evidence is not high. Therefore, we propose a stepwise and interdisciplinary approach to guide the challenging decision-making process in SVC.

Point-of-Care Arterio-Venous Fistula Ultrasound in the Outpatient Hemodialysis Unit-A Survey on the Nurses' Perspective

The preservation of complication-free arterio-venous fistulas (AVF) for long-term hemodialysis (HD) use is associated with better overall patient outcomes, which is why this is a current goal in any HD center. Point-of-care ultrasound (POCUS) for in-center AVF assessment has proven its benefits in the identification of vascular access (VA) complications and as an additional tool to avoid blind cannulation. The current study aims to assess the change in the HD nurses' perceptions regarding AVF POCUS use in the HD center. The nursing staff anonymously answered a Likert scale questionnaire with five questions related to various aspects of AVF POCUS utility shortly after the technique had been implemented and at a 5-year follow-up. The results showed an overall positive attitude toward this method, both at implementation and at follow-up, with no statistically significant score changes for four out of the five items assessed. However, we found a statistically significant reduction in the nurses' cannulation confidence scores at the 5-year follow-up (p < 0.01). Overall, AVF POCUS implementation is regarded as a useful tool, with major benefits both for the patient and for the medical team. The current study results aim to support the introduction of AVF POCUS assessment as a standard practice from the nursing staff's viewpoint. This study was not registered.