Arteriovenous Access Failure, Stenosis, and Thrombosis

Influence of balloon type and lesion location on outcomes following fistuloplasty

BACKGROUND

There is limited evidence supporting the optimal use of fistuloplasty to maintain vascular access at various lesion sites, despite its critical role in facilitating renal replacement therapy and the overall high failure rates of arteriovenous fistulas (AVFs). This study aims to identify covariates affecting primary and secondary patency following fistuloplasty of native upper limb vascular access AVFs.

METHODS

This retrospective study included all patients who underwent fistuloplasty at a tertiary vascular centre over 4 years. Baseline characteristics were recorded, and factors associated with primary and secondary patency rates were analysed.

RESULTS

A total of 206 patients (88 male, 118 female) with a mean age of 68 (±14) years underwent fistuloplasty during the study period. The prevalence of diabetes, ischaemic heart disease and antiplatelet usage were 33%, 21% and 70%, respectively. The median number of fistuloplasties per access during the follow-up period was 2 [1-3]. Fistulas were classified as radiocephalic (65), brachiocephalic (102) and brachiobasilic transposition (39). Recurrent stenosis (RS) was identified in 60 patients who had previous fistuloplasty before the study period, while 146 patients had de novo stenoses (DNS). Stenosis location significantly differed between RS and DNS (p = .03), with DNS primarily being anastomotic and RS predominantly in central and mixed locations. Younger fistulas were more likely to have anastomotic stenoses compared to those older than 1 year (p = .001). While no significant differences in primary patency (PP) were observed, secondary patency (SP) varied by stenosis location: Central 32 [13-42] months, Fistula vein 20 [12.5-35.5] months, Mixed 25 [13.5-37.5] months and Anastomotic 19 [7-29.5] months (p = .012).

CONCLUSION

Stenosis location in AVFs is associated with the age and type of the fistula. Younger fistulas often fail due to anastomotic stenoses, which have lower secondary patency compared to stenoses at other sites. Preliminary data suggest that central stenoses, primarily occurring in older fistulas, exhibit better secondary patency following fistuloplasty than stenoses at other locations.

Reliable Stenosis Detection Based on Thrill Waveform Analysis Using Non-Contact Arteriovenous Fistula Imaging

Hemodialysis therapy is an extracorporeal circulation treatment that serves as a substitute for renal function. In Japan, patients receive this efficient four-hour treatment, three times per week, allowing them to maintain a social life nearly equivalent to that of healthy individuals. Before the treatment, two punctures are performed to establish extracorporeal circulation, and a high blood flow rate is essential to ensure efficient therapy. Specialized blood vessels created through arteriovenous fistula (AVF) surgery are utilized to achieve high blood flow rates. Although the AVF allows safe and efficient dialysis treatment, AVF stenosis leads to a serious problem in dialysis. To early detect this abnormal blood flow, auscultation and palpation methods are widely used in hospitals. However, these methods can only provide qualitative judgment of the AVF condition, so the results cannot be shared among other doctors and staff. Additionally, since the conventional methods require contact with the skin, some issues require consideration regarding infection and low reproducibility. In our previous study, we proposed an alternative method for auscultation using non-contact optical imaging technology. This study aims to construct a reliable AVF stenosis detection method using Thrill waveform analysis based on the developed non-contact device to solve the problem with the contact palpation method. This paper demonstrates the performance validation of the non-contact imaging in the normal AVF group (206 total data, 75 patients, mean age: 69.1 years) and in the treatable stenosis group (107 total data, 17 patients, mean age: 70.1 years). The experimental results of the Mann-Whitney U test showed a significant difference (p=0.0002) between the normal and abnormal groups, which indicated the effectiveness of the proposed method as a new possible alternative to palpation.

Vascular Access Considerations in Home Hemodialysis

There is a global interest in expanding home dialysis utilization among patients with ESKD. Home hemodialysis (HHD) is an appealing KRT option for this population because of its multiple clinical and quality of life benefits. Central to successful HHD is the establishment and maintenance of a functioning vascular access that serves as a patient's lifeline while on therapy. While the selection of a vascular access type is influenced by individual patient circumstances, the arteriovenous fistula is generally the preferred access method. Training patients to use their dialysis access requires attention to safety, risk management, and monitoring for complications to minimize adverse events and technique failure. Policies incorporating systematic frameworks for quality improvement and assurance, in conjunction with the measurement of metrics relating to vascular access, are tools that should be used by HHD programs to enhance the value of care delivered. In this perspective, we aim to describe what is currently known about the various vascular access options in HHD and to elucidate what needs to be taken into consideration in the selection and care of this access.

A Miniaturized Dual-Band Circularly Polarized Implantable Antenna for Use in Hemodialysis

Hemodialysis is achieved by implanting a smart arteriovenous graft (AVG) to build a vascular pathway, but reliability and stability in data transmission cannot be guaranteed. To address this issue, a miniaturized dual-band circularly polarized implantable antenna operating at 1.4 GHz (for energy transmission) and 2.45 GHz (for wireless telemetry), implanted in a wireless arteriovenous graft monitoring device (WAGMD), has been designed. The antenna design incorporates a rectangular serpentine structure on the radiation surface to reduce its volume to 9.144 mm3. Furthermore, matching rectangular slots on the radiation surface and the ground plane enhance the antenna's circular polarization performance. The simulated effective 3 dB axial ratio (AR) bandwidths are 11.43% (1.4 GHz) and 12.65% (2.45 GHz). The simulated peak gains of the antenna are -19.55 dBi and -22.85 dBi at 1.4 GHz and 2.45 GHz, respectively. The designed antenna is implanted in a WAGMD both in the simulation and the experiment. The performance of the system is simulated in homogeneous human tissue models of skin, fat, and muscle layers, as well as a realistic adult male forearm model. The measurement results in a minced pork environment align closely with the simulation results.

Tunneled central venous catheters for hemodialysis-unfairly condemned? Catheter-related complications in a university hospital setting

BACKGROUND

Central venous catheters (CVCs) provide an immediate hemodialysis access but are considered to be of elevated risk for complications. It remains unclear, if CVCs per se have relevant impact on clinical outcome. We provide an assessment of CVC-associated complications and their impact on mortality.

METHODS

In a single center retrospective study, CVC patients between JAN2015-JUN2021 were included. Data on duration of CVC use, complications and comorbidities was collected. Estimated 6-month mortality was compared to actual death rate.

RESULTS

About 478 CVCs were analyzed. Initiation of dialysis was the main reason for CVC implantation. Death was predominant for termination of CVC use. Infections were rare (0.6/1000 catheter days), complications were associated with certain comorbidities. Actual 6-month mortality was lower than predicted (14.3% vs 19.6%).

CONCLUSION

(1) CVCs are predominantly implanted for initiation of hemodialysis; (2) serious complications are rare; (3) complications are associated with certain comorbidities; and (4) CVC patients survive longer than predicted.

Early access flow rate predicts vascular access patency-related intervention in the first year: A retrospective cohort study

INTRODUCTION

Arteriovenous fistulas and grafts are lifelines for most hemodialysis patients, and a low access flow rate often requires patency-related intervention, such as angioplasty or thrombectomy, to prevent access failure. We examined whether early access flow rate, measured after initial fistula/graft cannulation, predicts vascular access patency-related intervention within 1 year.

METHODS

This was a single-center retrospective cohort study. Among 172 patients undergoing surgical creation of a fistula/graft, 52 (30.2%) had documented access flow rates measurement by the Transonic™ ultrasound dilution technique, performed within an average of 48 days from initial access cannulation. The need for a patency-related intervention, defined as undergoing a fistulogram, angioplasty, thrombectomy, or surgical revision, was ascertained within 1 year. A receiver-operating characteristic curve (ROC) was generated to evaluate the diagnostic performance of first and average access flow rates for predicting patency-related intervention within 1 year.

FINDINGS

Twenty-eight (53.8%) of the 52 study subjects required a patency-related intervention within 1 year. Their characteristics were not significantly different from those who did not require patency-related interventions. However, first access flow rates were significantly lower in patients requiring patency-related intervention compared to those who did not (898 vs. 1471 mL/min; p = 0.003), as were average access flow rates (841 vs. 1506 mL/min; p < 0.001). The ROC analyses revealed that first access flow rates and average access flow rates predicted the need for patency-related intervention within 1 year, with an area under-the-ROC curve of 0.743 (95% confidence interval [CI] 0.608, 0.877) and 0.775 (95% CI 0.648, 0.903), respectively, demonstrating acceptable discrimination.

DISCUSSION

In adults undergoing hemodialysis, early access flow rate measurement can predict patency-related intervention within 1 year after initial vascular access cannulation. Additional studies are required to confirm these findings and identify optimal access flow rate cut-off values to predict vascular accesses at higher risk of stenosis.

Utility of a ML analytics on real time risk stratification and re-intervention risk prediction on AV access outcomes and cost

BACKGROUND

Vascular access is the lifeline for patients on hemodialysis. The average survival rates of dialysis dependent patients have been improving over the last 5 years and hence their dialysis access needs longevity for uninterrupted optimal dialysis. With the lack of genomic vascular access failure predictors, there is an unmet need for predicting an event and the appropriate approach to mitigate recurrence of the event that could have cost and outcome implications.

METHODS

We performed a single center experience that extracted relevant clinical (access flow, laboratory data and CKD details), access intervention (prior interventions, type & location of lesion, type of balloon used, use of stents etc.) and demographic (age, vintage on dialysis, sex, social determinants, other medical conditions) data in real time and feeds it into validated ML algorithms to predict risk of reintervention. (Plexus EMR LLC).

RESULTS

About 200 prevalent hemodialysis patients with a AV graft or AV fistula were included for this analysis. Need for re-intervention and use of stent/ flow reduction/new access creation were the outcomes analyzed. Plexus EMR is a licensed Azure based platform. R software was used to develop the ML algorithms. Regression factors were developed to assess and test the validity of individual attributes across all the data attributes. Each patient had a real time risk calculator available to the interventionalist on risk of reintervention/ year. Of the 200 patients, 148 had a AV fistula and the remaining 52 had a AV graft. Mean interventions in the year prior to analysis was 1.8 in patients with AV fistulas and 3.4 in AV grafts which decreased to 1.1 in AV fistulas and to 2.4 in AV grafts (p < 0.01) post tool deployment. There were 62 AV graft thrombectomies done in the observation year and 62% of those were repeat thrombectomies. Stent utilization increased to 37 (22 in AV grafts and 15 in AV fistulas) and 2 patients had AV access flow reduction surgery. The cumulative cost (predicted) preintervention was $712,609 and decreased to $512,172 post intervention. Stent utilization increased by 68% in the evaluation year and 89% of the stents used were PTFE coated stents.

CONCLUSION

Utilizing AI with ML based algorithms that includes clinical, demographic and patency maintenance variables could become new standards of care to optimally manage AV accesses and lower cost of care.

Direct Percutaneous Thrombolysis (DPT): A novel method of salvaging Thrombosed Native Arteriovenous Fistula

INTRODUCTION

Thrombosed arteriovenous fistulas (AVFs) are either treated by thrombectomy or pharmaco-mechanical thrombolysis with or without percutaneous balloon angioplasty. In this study, we have described an effective and economical technique of salvaging these fistulae using a 20-22-gauge spinal needle and urokinase and have named it direct percutaneous thrombolysis (DPT).

MATERIALS AND METHOD

This prospective study comprised of 148 patients out of which 120 patients presented with AVF thrombosis and were divided into two groups; those with no obvious stenosis on ultrasound (n = 38) and second with venous stenosis (n = 82). Remaining 28 patients developed thrombosis post angioplasty for venous stenosis. Percutaneous injection of urokinase into the thrombus was done under ultrasound guidance, followed by balloon angioplasty if there was associated stenosis.

RESULTS

In 38 patients who didn't have any stenosis, 32 AVFs were successfully thrombolysed by DPT, with technical success of 84.2%. Remaining six patients required angioplasty because of chronic nature of clot. In 82 patients who had venous stenosis, 80 cases were treated successfully by DPT followed by angioplasty with technical success of 97.5%. In third group (n = 28), who developed thrombosis post angioplasty, 100% success rate was noted. The mean length of thrombus was 31.4 ± 4.6 mm and mean diameter of thrombosed vein was 10.5 ± 1.2 mm. There were no major complications encountered during the procedure. Minor complications were seen in 19 patients which included prolonged oozing from puncture site and local hematoma formation.

CONCLUSION

Ultrasound guided DPT with urokinase is a safe and economical option for salvaging thrombosed AVF without vascular stenosis that does not need angioplasty.

Disturbed flow in the juxta-anastomotic area of an arteriovenous fistula correlates with endothelial loss, acute thrombus formation, and neointimal hyperplasia

Clinical failure of arteriovenous neointimal hyperplasia (NIH) fistulae (AVF) is frequently due to juxta-anastomotic NIH (JANIH). Although the mouse AVF model recapitulates human AVF maturation, previous studies focused on the outflow vein distal to the anastomosis. We hypothesized that the juxta-anastomotic area (JAA) has increased NIH compared with the outflow vein. AVF was created in C57BL/6 mice without or with chronic kidney disease (CKD). Temporal and spatial changes of the JAA were examined using histology and immunofluorescence. Computational techniques were used to model the AVF. RNA-seq and bioinformatic analyses were performed to compare the JAA with the outflow vein. The jugular vein to carotid artery AVF model was created in Wistar rats. The neointima in the JAA shows increased volume compared with the outflow vein. Computational modeling shows an increased volume of disturbed flow at the JAA compared with the outflow vein. Endothelial cells are immediately lost from the wall contralateral to the fistula exit, followed by thrombus formation and JANIH. Gene Ontology (GO) enrichment analysis of the 1,862 differentially expressed genes (DEG) between the JANIH and the outflow vein identified 525 overexpressed genes. The rat jugular vein to carotid artery AVF showed changes similar to the mouse AVF. Disturbed flow through the JAA correlates with rapid endothelial cell loss, thrombus formation, and JANIH; late endothelialization of the JAA channel correlates with late AVF patency. Early thrombus formation in the JAA may influence the later development of JANIH.NEW & NOTEWORTHY Disturbed flow and focal endothelial cell loss in the juxta-anastomotic area of the mouse AVF colocalizes with acute thrombus formation followed by late neointimal hyperplasia. Differential flow patterns between the juxta-anastomotic area and the outflow vein correlate with differential expression of genes regulating coagulation, proliferation, collagen metabolism, and the immune response. The rat jugular vein to carotid artery AVF model shows changes similar to the mouse AVF model.

A Cost-Effective Approach to Resistant AV Fistula Stenosis: Successful Treatment Using Coronary OPN NC® Balloon in a Low-Income Setting

Stenosis in the anastomotic site or venous limb of an arteriovenous fistula (AVF) is the most frequent cause of AVF failure. Percutaneous angioplasty with a standard or high-pressure balloon is the first-line treatment for AVF stenosis due to its higher technical success rate (90%) and lower complication rate (4%). Almost 20% of stenosis cases are resistant or undilatable by regular-pressure balloon angioplasty due to fibrosis, leading to technical failure or restenosis. Alternative therapies, such as atherectomy devices or cutting balloons, are expensive and difficult to obtain in low-income developing countries. We successfully treated resistant AVF stenosis with a coronary OPN-NC® ultra-high-pressure balloon and produced a good angiographic result with technical success. Coronary hardware is easily available and relatively cheaper compared to dedicated peripheral balloons or devices in our country due to reuse, which can be a boon in such type of cases. According to the standard hospital protocol, Cathlab hardware was reused.

Association between heart failure and arteriovenous access patency in patients with end-stage renal disease on hemodialysis

BACKGROUND

Heart disease and chronic kidney disease are often comorbid conditions owing to shared risk factors, including diabetes and hypertension. However, the effect of congestive heart failure (CHF) on arteriovenous fistula (AVF) and AV graft (AVG) patency rates is poorly understood. We hypothesize preexisting HF may diminish blood flow to the developing AVF and worsen patency.

METHODS

We conducted a single-institution retrospective review of 412 patients with end-stage renal disease who underwent hemodialysis access creation from 2015 to 2021. Patients were stratified based on presence of preexisting CHF, defined as clinical symptoms plus evidence of reduced left ventricular ejection fraction (EF) (<50%) or diastolic dysfunction on preoperative echocardiography. Baseline demographics, preoperative measures of cardiac function, and dialysis access-related surgical history were collected. Kaplan-Meier time-to-event analyses were performed for primary patency, primary-assisted patency, and secondary patency using standard definitions for patency from the literature. We assessed differences in patency for patients with CHF vs patients without CHF, patients with a reduced vs a normal EF, and AVG vs AVF in patients with CHF.

RESULTS

We included 204 patients (50%) with preexisting CHF with confirmatory echocardiography. Patients with CHF were more likely to be male and have comorbidities including, diabetes, chronic obstructive pulmonary disease, hypertension, and a history of cerebrovascular accident. The groups were not significantly different in terms of prior fistula history (P = .99), body mass index (P = .74), or type of hemodialysis access created (P = .54). There was no statistically significant difference in primary patency, primary-assisted patency, or secondary patency over time in the CHF vs non-CHF group (log-rank P > .05 for all three patency measures). When stratified by preoperative left ventricular EF, patients with an EF of <50% had lower primary (38% vs 51% at 1 year), primary-assisted (76% vs 82% at 1 year), and secondary patency (86% vs 93% at 1 year) rates than those with a normal EF. Difference reached significance for secondary patency only (log-rank P = .029). AVG patency was compared against AVF patency within the CHF subgroup, with significantly lower primary-assisted (39% vs 87% at 1 year) and secondary (62% vs 95%) patency rates for AVG (P < .0001 for both).

CONCLUSIONS

In this 7-year experience of hemodialysis access creation, reduced EF is associated with lower secondary patency. Preoperative CHF (including HF with reduced EF and HF with preserved EF together) is not associated with significant differences in overall hemodialysis access patency rates over time, but patients with CHF who receive AVG have markedly worse patency than those who receive AVF. For patients with end-stage renal disease and CHF, the risks and benefits must be carefully weighed, particularly for those with low EF or lack of a suitable vein for fistula creation.

Risk Factors for Thromboembolic Events in Patients With Dialysis-Dependent CKD: Pooled Analysis of Phase 3 Roxadustat Trials in Japan

INTRODUCTION

Thromboembolic events have occurred in clinical trials of roxadustat. This post hoc analysis explored potential factors related to thromboembolic events in dialysis-dependent patients treated with roxadustat in four phase 3 clinical trials in Japan.

METHODS

Thromboembolic events with onset before and after week 12 were evaluated. Baseline risk factors for thromboembolic events were investigated by Cox regression analyses. Nested case-control analyses using conditional logistic models with matched pairs of case-control data explored relationships between thromboembolic events and laboratory parameters.

RESULTS

Of the 444 patients, 56 thromboembolic events were observed in 44 patients during ≤ 52 weeks of treatment. The proportion of venous and arterial thromboembolic events gradually increased after week 12. Baseline risk factors included hemodialysis (vs peritoneal dialysis), advanced age (≥ 65 years), shorter dialysis vintage (< 4 months), and history of thromboembolism. The absence of concomitant intravenous or oral iron therapy (including ferric citrate) was associated with thromboembolic events before week 12 (hazard ratio 11.25; 95% confidence interval [CI] 3.36-37.71; vs presence). Case-control analysis revealed that low average transferrin saturation (< 10%; unadjusted odds ratio [OR] 6.25; 95% CI 1.52-25.62; vs ≥ 20%), high average transferrin level (≥ 2.5 g/L; unadjusted OR 4.36; 95% CI 1.23-15.39; vs < 2.0 g/L), and high average roxadustat dose (≥ 150 mg; unadjusted OR 5.95; 95% CI 1.07-33.16; vs < 50 mg) over the previous 8 weeks before the event onset were associated with thromboembolic events after week 12. However, adjustment for iron status extinguished the significant relationship between roxadustat dose and events. Multivariate case-control analysis showed that increased transferrin from baseline (≥ 1.0 g/L; adjusted OR 7.85; 95% CI 1.82-33.90; vs < 0.5 g/dL) and decreased mean corpuscular volume (< - 2 fL; adjusted OR 5.55; 95% CI 1.73-17.83; vs ≥ 0 fL) were associated with increased risk of thromboembolic events.

CONCLUSION

In addition to established risk factors, iron deficiency may be related to thromboembolic events. Graphical Abstract available for this article.

TRIAL REGISTRATION

NCT02780726, NCT02952092, NCT02780141, NCT02779764.

Impact of COVID-19 pandemic on hemodialysis access thrombosis

BACKGROUND

Delay in care of suspected stenosis or thrombosis can increase the chance of losing a functioning hemodialysis access. Access to care and resources were restricted during the COVID-19 pandemic. To evaluate the impact of the pandemic on arteriovenous fistula (AVF) and arteriovenous graft (AVG) procedures we have assessed the number and success of thrombectomies done before and during the COVID-19 pandemic.

METHODS

We examined all AVF and AVG angiograms with and without interventions, including thrombectomies, performed at a single center during April 2017-March 2021 (pre-COVID-19 era) and April 2020-March 2021 (COVID-19 era).

RESULTS

The proportion of procedures that were thrombectomies was higher during the COVID-19 era compared to the pre-COVID-19 era (13.3% vs 8.7%, p = 0.009). The proportion of thrombectomy procedures was higher during COVID-19 for AVF (8.2% vs 3.0%, p < 0.001) but there was no difference for AVG (26.5% vs 27%, p = 0.99). There was a trend toward a higher likelihood of unsuccessful thrombectomy during COVID-19 (33.3% vs 20.4%, p = 0.08).

CONCLUSIONS

More dialysis access thromboses and unsuccessful thrombectomies were noted during the COVID-19 pandemic. This difference could be due to a delay in patients getting procedures to maintain their dialysis accesses.

Ankle-brachial index associates with arteriovenous fistula stenosis

BACKGROUND

Arteriovenous fistula (AVF) stenosis is associated with pre-existing arterial atherosclerosis of AVF and results in significant morbidity and hospitalization for hemodialysis patients. The ankle brachial index (ABI) is a noninvasive method of assessing atherosclerosis. This study was to examine whether ABI is a significant predictor for AVF stenosis.

METHODS

This was a retrospective, longitudinal cohort study. Patients with hemodialysis between 1 January 2016 and 31 December 2022 were reviewed. ABI was assessed in January 2016. AVF stenosis was diagnosed by fistulography.

RESULTS

A total of 82 patients were included. Forty-two patients experienced AVF stenosis. The univariate logistic regression analysis showed that AVF stenosis was associated with age (OR: 1.045, p = 0.033), DM status (OR: 5.529, p = 0.013), 7-year averaged cholesterol level (OR: 1.018, p = 0.034), 7-year averaged triglyceride level (OR: 1.007, p = 0.017), and ABI (OR: 0.011, p < 0.001). In multivariate logistic regression analysis, ABI was a strong predictor for AVF stenosis (OR: 0.036, p = 0.023). Then, a cut-off point of ABI with optimal sensitivity and specificity for AVF stenosis was 1.01. An analysis of time to events with adjustment for other variables showed that patients with ABI < 1.01 were significantly associated with AVF stenosis (HR: 3.859, p < 0.001).

CONCLUSIONS

ABI below 1.01 was associated with AVF stenosis. This finding may be useful in tailoring surveillance programs for monitoring AVF function.

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.

Stent Grafts Across the Elbow Joint for Access Salvage

PURPOSE

Covered stent grafts (SGs) are currently being used in a wide variety of situations to maintain function and patency of hemodialysis access circuits. Stent grafts are rarely placed across the elbow joint (EJ), however, due to fear of stent fracture. This study reports on the experience and patency rates with SGs across the EJ.

MATERIALS AND METHODS

From April 2020 to August 2023, all procedures with SGs placed across the EJ were retrospectively analyzed. A total of 21 patients with SGs placed across the EJ were included in the study. The Covera Vascular Covered Stent (BD, Franklin Lakes, New Jersey, USA) was used in all cases. Of these, 18 were arteriovenous (AV) fistulae, and 3 were AV grafts. Stent grafts were placed for various pathologies, including residual stenosis, perforation, aneurysm, and thrombosis. Follow-up outcomes were obtained from angiographic images on follow-up angiography and included primary patency, primary assisted patency, and secondary patency.

RESULTS

The primary patency of the target lesion was 85% (CI=70%-100%) and 85% (CI=70%-100%) at 6 and 12 months, respectively. The primary assisted patency was 85% (CI=70%-100%) and 85% (CI=70%-100%) at 6 and 12 months, respectively. Secondary patency of the access circuit was 95% (CI=86%-100%) at 6 months and 89% (CI=75%-100%) at 12 months. The average follow-up duration was 393 days (range=27-768 days). There were no instances of stent fracture during follow-up.

CONCLUSIONS

Stent grafts should be placed across the EJ for good short-term and mid-term patency rates.

CLINICAL IMPACT

The placement of stent grafts across the elbow joint in hemodialysis patients for access salvage is controversial due to the fear of stent fracture or occlusion. This retrospective study evaluated the placement of stent grafts for access salvage in 21 patients for various etiologies. Good patency rates were seen out to 12 months and no stent fractures were observed. Although longer term data is needed, stent grafts should be considered an acceptable option for access salvage when treating lesions that cross the elbow joint.

Delamination and dissection of arteriovenous grafts: A multicenter report of four cases

Arteriovenous (AV) grafts are an alternative vascular access for chronic hemodialysis. AV graft failure is often due to stenosis of the feeding artery, graft, or draining vein. We report four cases of AV graft dysfunction and failure rarely caused by graft delamination and dissection. Two males and two females aged 47-67 years had been on chronic hemodialysis. Ultrasound examination detected graft delamination and dissection between 1 and 33 months after Acuseal AV graft implantation. Two cases were successfully treated with stenting and partial graft replacement, respectively. False lumen volume reduction by fluid withdrawal failed to salvage the delaminated graft in one of the patients. The delamination and dissection of another case spontaneously resolved 5 months later. Graft delamination and dissection should be considered as a possible cause for AV graft dysfunction and failure. Stenting and graft replacement may be recommended to treat AV graft dissection and delamination.

Small Caliber Distal Cephalic Veins Undergo Significant Dilation under Anesthesia and Can Successfully Be Used for Arteriovenous Fistula Creation

BACKGROUND

Successful arteriovenous fistula (AVF) maturation and use for dialysis is highly dependent on preoperative diameter. Small veins (<2 mm) exhibit high failure rates and are typically avoided. This study investigates the effects of anesthesia on the distal cephalic vein diameter as compared to preoperative outpatient vein mapping for the purpose of hemodialysis access creation.

METHODS

One hundred eight consecutive procedures for dialysis access placement met inclusion criteria and were reviewed. All patients received preoperative venous mapping and postanesthesia ultrasound mapping (PAUS). All patients received either regional and/or general anesthesia. A multiple regression was conducted to determine predictors of venous dilatation. The independent variables included both demographical and operative-specific variables such as the type of anesthesia. Outcomes of fistula maturation (successful cannulation and dialysis) were analyzed.

RESULTS

In this cohort, the mean preoperative vein diameter was 1.85 mm and the mean PAUS diameter was 3.45 mm, a 2.21× increase, with only 2 patient veins failing to increase in diameter. Smaller veins (<2 mm) exhibited significantly more dilation than larger veins after anesthesia (2.73 vs. 1.47×, P < 0.001). In the multiple regression analysis, smaller vein diameter was correlated with a significantly greater degree of dilation (P < 0.001). The degree of venous dilation was not affected by patient demographic-specific factors or by the type of anesthesia (regional block versus general) in the multiple regression analysis. 6 month follow-up data for fistula maturation was available for 75 of 108 patients. Small veins (<2 mm) on preoperative ultrasound matured at a similar rate as larger veins (90% vs. 91.4%, P = 0.833).

CONCLUSIONS

Small caliber distal cephalic veins experience a significant degree of dilation under regional and general anesthesia and can successfully be used for AVF creation. Consideration should be made to perform a postanesthesia vein mapping for all patients undergoing access placement despite preoperative venous mapping results.

Persistent median artery on computed tomographic arteriovenous fistulograms in patients on haemodialysis

INTRODUCTION

Cadaveric studies suggest an increasing prevalence of the persistent median artery (PMA) over a prolonged timeframe. The aim of this retrospective cross-sectional study was to evaluate the PMA prevalence in haemodialysis patients who had computed tomographic fistulograms (CTFs), and if present, their calibres and origins.

METHODS

All consecutive adult patients referred for an upper limb CTFs for assessment of arteriovenous fistula (AVF) dysfunction from 2006 to 2021 were included. Patients whose CTF did not include the forearm were excluded. PMA was identified as an artery running alongside the median nerve between flexor digitorum superficialis and flexor digitorum profundus. Patient demographics, presence of PMA including size and origin were recorded.

RESULTS

A PMA was found in 91/170 (53.5%) CTFs (7:3 male-to-female ratio, mean age 71-years). When stratified by age, prevalence increased with decreasing age; 51% in >70-year-olds, 54% in 50-70-year-olds and 67% in <50-year-olds. The average PMA diameter was 2.2 mm proximally and 1.8 mm distally. No stenosis was observed in the PMAs.

CONCLUSION

The PMA prevalence appears to increase with decreasing age and is a frequently encountered anatomical variant. Radiologists assessing forearm vasculature need to be aware of this anatomical variant and potentially include it in their future reports. Further research into the PMA may make its potential use as arterial conduits for AVF, potential donor grafts for coronary artery bypass surgery or additional vascular access options possible. Whether the reducing prevalence with age reflects an overall increasing prevalence is yet to be determined.

Maintenance and Salvage of Hemodialysis Access

Many end-stage kidney failure patients require hemodialysis as a life-sustaining treatment. Hemodialysis access via arteriovenous fistula or graft creation is preferred over long-term dialysis catheters, but intervention to maintain patency and prevent access failure is common. Endovascular and open surgical techniques are both utilized to address the underlying etiology of failure. Endovascular options include balloon angioplasty, angioplasty with stenting, and drug-eluting stents. Open revision is commonly needed for recurrent stenosis, aneurysmal or pseudoaneurysmal change, hemodialysis access-induced distal ischemia, and infection. Treatment plans should be guided by patient's individualized goals of care and require a multidisciplinary approach to the management of this complex disease.

Acute hemodynamic changes during far infrared treatment of the arteriovenous fistula in hemodialysis patients

BACKGROUND

The arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis (HD) treatment and preservation of a stable vascular access is crucial. Long term Far Infrared Radiation (FIR) has been found to increase access flow together with an enhanced maturation and patency of the AVF. The acute effects of FIR on access flow have been sparsely described and the results are contradictory, perhaps due to differences in measurement conditions and other factors of importance for access flow.

METHODS

Twenty patients in HD with an AVF were included. Each patient was randomized to receive either FIR (FIR group) or no FIR (control group). The acute changes in access flow were investigated in both groups on the second dialysis day of the week and during the first 1.5 h of the dialysis session. Concomitant changes in hemodynamic parameters of importance for access flow were also explored.

RESULTS

There was no significant change in access flow in the FIR group compared with the control group (median (Interquartile Range)) (-10 (-413.8; 21.3) ml/min vs -17.5 (-83.8; 76.3) ml/min, p = 0.58). There was no significant difference in any of the hemodynamic parameters between the FIR and the control group; cardiac output (-0.7 (-1.2; -0.2) l/min vs -0.4 (-0.9; 0.1) l/min, p = 0.58), cardiac index (-0.3 (-0.5; -0.1)) l/min/m2 vs -0.3 (-0.4; 0) l/min/m2, p = 0.68), mean arterial pressure (5.5 (-1.8; 8.4) mmHg vs 1.5 (-3; 6.3) mmHg, p = 0.35) and total peripheral resistance (2 (1.8; 3.4) mmHg × min/l vs 1 (-0.3; 3.1) mmHg × min/l, p = 0.12).

CONCLUSION

In this trial, with a highly standardized set-up, one session of FIR did not result in any acute changes in access flow. This was not due to differences in the hemodynamic parameters between the groups.

Clinical implications of inflammation in atheroma formation and novel therapies in cardiovascular diseases

Cardiovascular diseases (CVD) are the leading causes of death and disability in the world. Among all CVD, the most common is coronary artery disease (CAD). CAD results from the complications promoted by atherosclerosis, which is characterized by the accumulation of atherosclerotic plaques that limit and block the blood flow of the arteries involved in heart oxygenation. Atherosclerotic disease is usually treated by stents implantation and angioplasty, but these surgical interventions also favour thrombosis and restenosis which often lead to device failure. Hence, efficient and long-lasting therapeutic options that are easily accessible to patients are in high demand. Advanced technologies including nanotechnology or vascular tissue engineering may provide promising solutions for CVD. Moreover, advances in the understanding of the biological processes underlying atherosclerosis can lead to a significant improvement in the management of CVD and even to the development of novel efficient drugs. To note, over the last years, the observation that inflammation leads to atherosclerosis has gained interest providing a link between atheroma formation and oncogenesis. Here, we have focused on the description of the available therapy for atherosclerosis, including surgical treatment and experimental treatment, the mechanisms of atheroma formation, and possible novel therapeutic candidates such as the use of anti-inflammatory treatments to reduce CVD.

Thrombectomy approach for access maintenance in the end stage renal disease population: a narrative review

Objective

This article reviews current practices and outcomes in endovascular thrombectomy techniques for the treatment of thrombosed arteriovenous grafts (AVGs) and fistulas (AVFs).

Background

Arteriovenous (AV) access allows patients with end-stage renal disease (ESRD) to receive hemodialysis. Thrombosis of AV access can lead to delay in hemodialysis or abandonment of access requiring dialysis catheter placement. Endovascular approach has become the preferred treatment option for thrombosed access over surgery. Interventions include removal of thrombus from the AV circuit and treatment of the underlying anatomical abnormality, such as an anastomotic stenosis. Thrombolysis, or the act of dissolving thrombus, is performed by using infusion catheters or pulse injector devices for the administration of fibrinolytic agents. Thrombectomy, or the mechanical removal of thrombus, is performed by using embolectomy balloon catheters, rotating baskets or wires, rheolytic and aspiration mechanisms. Adjunctive methods such as cutting balloon angioplasty, drug-coated balloon (DCB) angioplasty, and stent placement are also used to treat stenoses in the AV circuit. Complications of these procedures include vessel rupture, arterial embolism, pulmonary embolism (PE), and paradoxical embolism to the brain.

Methods

This narrative review article was written based on literature search from electronic databases, including PubMed and Google Scholar.

Conclusions

The understanding of thrombectomy techniques and their potential complications is essential in the management of patients with thrombosed AV access.

Angioplasty of Dysfunctional Dialysis Fistula or Graft with Resveratrol-Excipient and Paclitaxel-Coated Balloon Improves Primary Patency Rates Compared to Plain Angioplasty Alone

In this prospective randomized single-blinded study (reg. ISRCTN11414306), 76 patients with a dysfunctional dialysis fistula or graft due to a single de novo or recurrent stenosis in the access circuit were randomized to receive either conventional PTA (POBA) as a standard of care (n = 38) or PTA + adjunctive PTA with a drug-coated (paclitaxel-resveratrol matrix) SeQuent^® Please OTW balloon (n = 38, DCB). Patients were scheduled for follow-up PTA at 3, 6, 9, and 12 months. The time of clinically driven target-lesion reintervention rate (primary patency rate) after the index procedure was analyzed using the log-rank test. The primary patency rates at 12 months after the index procedure were 17% (DCB) vs. 11% (POBA). At 3 months, they were 87% vs. 74%, at 6 months they were 53% vs. 26%, and at 9 months they were 22% vs. 11%. The hazard ratio for DCB was 0.55 (95%CI 0.32 to 0.95). The median time needed for target-lesion reintervention was longer in the DCB group (181 days) than in the conventional PTA group (98 days, p = 0.019). We conclude that PTA with the paclitaxel-resveratrol drug-coated SeQuent^® Please OTW balloon in patients with de novo or recurrent stenosis in dialysis arteriovenous fistulas or grafts prolongs the time needed for target lesion reintervention and improves primary patency rates in the first year after the index procedure.

Difficult cannulation of hemodialysis arteriovenous fistula - Role of imaging in access management (DICAF STUDY)

BACKGROUND

Difficulty in cannulation of arteriovenous fistula (AVF) can lead to inadequate dialysis, transient to permanent loss of access and increases dependency on bridging catheters. This study aimed to analyze the causes for difficult fistula cannulation, using various imaging modalities.

METHODOLOGY

This was a retrospective single-center observational study conducted between October 2017 and June 2018. Patients whose fistulae were difficult to cannulate were initially evaluated by physical examination followed by doppler ultrasonography or/and fistulogram as necessary. The patients were divided into two groups that is, primary difficult cannulation (within first three months of creation of fistula) or secondary difficult cannulation (after three months).

RESULTS

We encountered difficult cannulation in 43 patients. About 60% were primary difficult cannulations. Most common causes for difficulty in cannulation were cannulation zone (CZ) stenosis (23.3%), immature fistula (20.9%), outflow stenosis (18.6%), inflow stenosis (11.6%), anatomical abnormalities (11.6%), outflow plus CZ stenosis (9.3%) and inflow plus CZ stenosis (4.7%). Among patients with primary difficult cannulation, immature fistula (34.6%) was the most common cause, whereas CZ stenosis (47.1%) was the most common etiology for secondary difficult cannulation. Edema leading to difficult cannulation was found in 12 patients (27.9%), all of which was due to central vein stenosis. Cannulation resulted in hematoma, fistula thrombosis, failure of fistula and pseudoaneurysm in 83.7%, 27.9%, 16.3%, and 2.3% of cases respectively. Bridging temporary dialysis catheter placement was required in 67.4% patients. Ultrasound doppler had lower diagnostic value when compared to fistulogram (71.4% vs 93.9%, p = 0.014).

CONCLUSION

Difficulty in cannulating the arteriovenous fistula is a common problem in hemodialysis patients. We suggest that patients whose fistulae are difficult to cannulate should undergo early radiological evaluation to decrease catheter dependency and access failure.

Early Failure of Arteriovenous Fistula (AVF): The Effect of Diabetes and Hypertension in a Cross-Sectional Study

Background: Identification and control of clinical predictors of arteriovenous (AVF) failure can improve the long-term outcome of hemodialysis patients. The effects of these factors on the outcome of AVF are not still clear. So, we aimed this study to compare the effect of hypertension and diabetes on early failure of AVF. Methods: In this retrospective study, we evaluated 400 patients with ESRD referred to our clinic for the creation of the first AVF from July 14, 2001, through August 7, 2018. One month after AVF creation, the patients were referred to the clinic for patency control. Demographic characteristics, previous history of diabetes and hypertension, and laboratory data of all patients were recorded preoperatively. Data were entered to SPSS v.24 and Study data were analyzed with chi-square and independent student t-test. Then, early failure of AVF and its relationship with a history of diabetes and hypertension were assessed. Results: There was no statistically significant relationship between the history of diabetes and early AVF failure risk in ESRD patients (OR, 0.78; 95% CI, 0.25 to 2.43). Furthermore, the history of hypertension was significantly lower in the early failure of AVF group (OR, -2.82; 95% CI, -1.42 to -5.59). Although, this effect faded when using regression analysis (OR, -2.67; 95% CI, -0.97 to -7.36). There was a higher Body mass index in the non-early failure group (p = 0.041). There was no significant difference in age (p = 0.512), gender (p = 0.091), history of smoking (p = 0.605), treatment with insulin (p = 0.683), oral antidiabetic agents (p = 0.734), duration of diabetes (p = 0.384), and duration of hypertension (p = 0.093). Conclusion: We reported that the history of diabetes was not higher in the early failure group, while there was a lower risk of AVF failure in patients with a previous history of hypertension.

Uncommon Surgical Management by AVF between the Great Saphenous Vein and Anterior Tibial Artery for Old Radiocephalic AVF Failure

Introduction: Autologous native arteriovenous fistula (AVF) created in the non-dominant arm is the gold standard vascular access for dialysis in end-stage renal disease, but the post-surgical vascular access dysfunction causes a reduction in the patient’s quality of life. Creating a functional upper extremity permanent arteriovenous access is limited by the upper limb’s vascular resources, so good management of a complicated arteriovenous fistula may improve patient outcomes. This article highlights the importance of new surgical options in treating complicated AVFs. Case report: We present the case of a patient with a 17-year-old complex radio-cephalic arterio-venous fistula and a series of surgical interventions performed for life salvage in the first place and functional vascular access in the second place. Furthermore, we describe a successfully created uncommon type of fistula in the lower extremity between the great saphenous vein and the anterior tibial artery as the last possible access for hemodialysis in this patient. Results: The patient underwent the first successful dialysis using the newly created lower limb fistula 1 month after the surgery. Conclusion: Applying new surgical techniques to manage AVFs gives a unique chance to improve the quality of life and reduce morbidity and mortality in these patients.

Transcriptomic Analysis Identifies Differentially Expressed Genes Associated with Vascular Cuffing and Chronic Inflammation Mediating Early Thrombosis in Arteriovenous Fistula

Arteriovenous fistula (AVF) is vascular access created for hemodialysis in end-stage renal disease patients. AVF creation causes increased blood flow in the outflow vein with increased pressure. Increased blood flow, blood volume, and shear stress causes outward remodeling so that the outflow vein can withstand the increased pressure. Outward remodeling of the vein involved in AVF is necessary for AVF maturation, however, inward remodeling due to excessive neointimal hyperplasia (NIH) and chronic inflammation may end up with vessel thrombosis and AVF maturation failure. Early thrombosis of the vessel may be due to the luminal factors including NIH and chronic inflammation or due to chronic inflammation of the adventitial due to perivascular cuffing. Inflammation may either be due to an immune response to the vascular injury during AVF creation or injury to the surrounding muscles and fascia. Several studies have discussed the role of inflammation in vascular thrombosis due to intimal injury during AVF creation, but there is limited information on the role of inflammation due to surrounding factors like a muscle injury. The concept of perivascular cuffing has been reported in the nervous system, but there is no study of perivascular cuffing in AVF early thrombosis. We performed the bulk RNA sequencing of the femoral arterial tissue and contralateral arteries as we found thrombosed arteries after AVF creation. RNA sequencing revealed several significantly differentially expressed genes (DEGs) related to chronic inflammation and perivascular cuffing, including tripartite motif-containing protein 55 (TRIM55). Additionally, DEGs like myoblast determination protein 1 (MYOD1) increased after muscle injury and relates to skeletal muscle differentiation, and network analysis revealed regulation of various genes regulating inflammation via MYOD1. The findings of this study revealed multiple genes with increased expression in the AVF femoral artery and may provide potential therapeutic targets or biomarkers of early thrombosis in AVF maturation failure. Thus, not only the luminal factors but also the surrounding factors mediating vascular cuffing contribute to vessel thrombosis and AVF failure via early thrombosis, and targeting the key regulatory factors may have therapeutic potential.

Development and validation of a risk score to prioritize patients for evaluation of access stenosis

Background

Access flow dysfunction, often associated with stenosis, is a common problem in hemodialysis access and may result in progression to thrombosis. Timely identification of accesses in need of evaluation is critical to preserving a functioning access. We hypothesized that a risk score using measurements obtained from the Vasc‐Alert surveillance device could be used to predict subsequent interventions.

Methods

Measurement of five factors over the preceding 28 days from 1.46 million hemodialysis treatments (6163 patients) were used to develop a score associated with interventions over the subsequent 60 days. The score was validated in a separate dataset of 298,620 treatments (2641 patients).

Results

Interventions in arteriovenous fistulae (AVF; n = 4125) were much more common in those with the highest score (36.2%) than in those with the lowest score (11.0). The score also was strongly associated with interventions in patients with an arteriovenous graft (AVG; n = 2,038; 43.2% vs. 21.1%). There was excellent agreement in the Validation datasets for AVF (OR = 2.67 comparing the highest to lowest score) and good agreement for AVG (OR = 1.92).

Conclusions

This simple risk score based on surveillance data may be useful for prioritizing patients for physical examination and potentially early referral for intervention.

Mathematical Models for Blood Flow Quantification in Dialysis Access Using Angiography: A Comparative Study

Blood flow rate in dialysis (vascular) access is the key parameter to examine patency and to evaluate the outcomes of various endovascular interve7ntions. While angiography is extensively used for dialysis access–salvage procedures, to date, there is no image-based blood flow measurement application commercially available in the angiography suite. We aim to calculate the blood flow rate in the dialysis access based on cine-angiographic and fluoroscopic image sequences. In this study, we discuss image-based methods to quantify access blood flow in a flow phantom model. Digital subtraction angiography (DSA) and fluoroscopy were used to acquire images at various sampling rates (DSA—3 and 6 frames/s, fluoroscopy—4 and 10 pulses/s). Flow rates were computed based on two bolus tracking algorithms, peak-to-peak and cross-correlation, and modeled with three curve-fitting functions, gamma variate, lagged normal, and polynomial, to correct errors with transit time measurement. Dye propagation distance and the cross-sectional area were calculated by analyzing the contrast enhancement in the vessel. The calculated flow rates were correlated versus an in-line flow sensor measurement. The cross-correlation algorithm with gamma-variate curve fitting had the best accuracy and least variability in both imaging modes. The absolute percent error (mean ± SEM) of flow quantification in the DSA mode at 6 frames/s was 21.4 ± 1.9%, and in the fluoroscopic mode at 10 pulses/s was 37.4 ± 3.6%. The radiation dose varied linearly with the sampling rate in both imaging modes and was substantially low to invoke any tissue reactions or stochastic effects. The cross-correlation algorithm and gamma-variate curve fitting for DSA acquisition at 6 frames/s had the best correlation with the flow sensor measurements. These findings will be helpful to develop a software-based vascular access flow measurement tool for the angiography suite and to optimize the imaging protocol amenable for computational flow applications.

Intimal Hyperplasia and Arteriovenous Fistula Failure: Looking Beyond Size Differences

The development of venous intimal hyperplasia (IH) has been historically associated with failure of arteriovenous fistulas (AVF) used for hemodialysis. This long-standing assumption, based on histological observations, has been recently challenged by clinical studies indicating that the size of the intima by itself is not enough to explain stenosis or AVF maturation failure. Irrespective of this lack of association, IH is present in most native veins and fistulas, is prominent in many cases, and suggests a role in the vein that may not be reflected by its dimensions. Therefore, the contribution of IH to AVF dysfunction remains controversial. Using only clinical data and avoiding extrapolations from animal models, we critically discuss the biological significance of IH in vein remodeling, vascular access function, and the response of the venous wall to repeated trauma in hemodialysis patients. We address questions and pose new ones such as: What are the factors that contribute to IH in pre-access veins and AVFs? Do cellular phenotypes and composition of the intima influence AVF function? Are there protective roles of the venous intima? This review explores these possibilities, with hopes of rekindling a critical discussion about venous IH that goes beyond thickness and AVF outcomes.

Factors influencing arteriovenous fistulas: A multicenter study

In this cross-sectional, descriptive study, the arteriovenous fistulas (AVF) of HD patients were evaluated by physical examination and factors associated with AVF function and longevity were investigated. Data were collected using a patient information form and the Arteriovenous Fistula Assessment Scale (AVF-AS). The study population included 279 patients under chronic HD treatment. Their mean age was 61.14 ± 14.00 years and 58.6% were men. Age, AVF location, and number of AVFs created were identified as factors associated with AVF needle entry site and flow problems, stenosis, and risk of developing ischemic complications (p = 0.005, p = 0.000, p = 0.006, respectively). AVF dysfunction adversely affected HD pump speed (p = 0.000) and HD adequacy (p = 0.000). It was determined that gender, AVF location, last AVF duration, and total number of previous AVF were identified as the risk of AVF complications. The results of this study revealed that regular follow-up and evaluation are needed to minimize the risk of dysfunction and failure due to AVF complications.

Tailoring of arteriovenous graft-to-vein anastomosis angle to attenuate pathological flow fields

Arteriovenous grafts are routinely placed to facilitate hemodialysis in patients with end stage renal disease. These grafts are conduits between higher pressure arteries and lower pressure veins. The connection on the vein end of the graft, known as the graft-to-vein anastomosis, fails frequently and chronically due to high rates of stenosis and thrombosis. These failures are widely believed to be associated with pathologically high and low flow shear strain rates at the graft-to-vein anastomosis. We hypothesized that consistent with pipe flow dynamics and prior work exploring vein-to-artery anastomosis angles in arteriovenous fistulas, altering the graft-to-vein anastomosis angle can reduce the incidence of pathological shear rate fields. We tested this via computational fluid dynamic simulations of idealized arteriovenous grafts, using the Bird-Carreau constitutive law for blood. We observed that low graft-to-vein anastomosis angles ([Formula: see text]) led to increased incidence of pathologically low shear rates, and that high graft-to-vein anastomosis angles ([Formula: see text]) led to increased incidence of pathologically high shear rates. Optimizations predicted that an intermediate  ([Formula: see text]) graft-to-anastomosis angle was optimal. Our study demonstrates that graft-to-vein anastomosis angles can significantly impact pathological flow fields, and can be optimized to substantially improve arteriovenous graft patency rates.

Effectiveness and safety of repeated percutaneous intervention in an office-based endovascular center in maintaining hemodialysis access

OBJECTIVES

Percutaneous dialysis access interventions are routinely used to maintain the patency of dialysis access despite the lack of data regarding their long-term effectiveness. This retrospective study was undertaken to study the effectiveness and safety of percutaneous dialysis access interventions in arm fistulas and bridge grafts in an office-based endovascular center.

METHODS

Patients who had a percutaneous dialysis access intervention in their upper extremity access site, performed at a single office-based endovascular center over a nine-year period (2007-2016) were included in this study. The patients' demographic factors, patency, and complications were analyzed. Patients were entered in the study after first percutaneous dialysis access intervention.

RESULTS

A total of 298 limbs in 259 patients had 913 procedures carried out over a nine-year period. There were 190 access arteriovenous fistulas and 108 arteriovenous grafts. The two most common arteriovenous fistulas were the brachiocephalic fistula (n = 74, 39%) and radio cephalic fistula (n = 69, 36%). Arteriovenous grafts were most commonly placed in the upper arm (n = 66, 61%) followed by the forearm (n = 42, 39%). The mean overall patency for all limbs was 50.86 months. Arteriovenous fistulas had a significantly longer patency than arteriovenous grafts (51.65 vs. 42.09 months; P = 0.01). In addition, patients with two or more percutaneous dialysis access intervention in their arteriovenous fistula had significantly greater patency than those with only one percutaneous dialysis access intervention (58.5 vs. 7.6 months; hazard ratio 0.41; P = 0.0008). This was not true for the arteriovenous graft group. Women represented 49% of the patient group. Their accesses had shorter patency than men (39.8 vs. 60 months; P = 0.0007).

CONCLUSIONS

This data support the use of repeated percutaneous dialysis access intervention to maintain long-term patency of dialysis access sites in an office-based endovascular center. Overall, fistulas have longer patency than grafts and women have poorer outcomes as compared to men.

Vascular access cannulation and haemostasis: a national observational study of French practices

BACKGROUND

We report the results of an observational study of arteriovenous fistula (AVF) cannulation and haemostasis practices in France.

METHODS

The study (sponsored by Brothier Pharmaceutical Inc.) was conducted in 150 dialysis units. Data obtained from 150 supervisory nurses, 1538 nurses and 3588 patients with an AVF were analysed.

RESULTS

The nurses reported using rope-ladder, area or buttonhole cannulation techniques in 68, 26 and 6% of cases, respectively. Metal needles were used most frequently (64%), with mainly a diameter of 15 G or 16 G. The needle was introduced with the bevel up in 56% of cases. Compression applied using dressings (in particular, pure calcium alginate dressings) was the method of choice for haemostasis of the puncture sites and was assessed as being strong by most of the nurses and very strong in cases of prolonged bleeding. Most (82%) of the patients reported the use of local anaesthetic before cannulation and 23% reported an allergic skin reaction to the anaesthetic. Bleeding of the puncture sites lasted for >10 min for 48% of the patients and it reappeared between two sessions for 29% of the patients. Whereas the nurses appeared to have a good understanding of AVF, more than half of the patients did not know how to care for it, with 55% requiring more information.

CONCLUSIONS

This study underlines the lack of national consensus concerning AVF cannulation practices. It suggests that haemostasis methods of the puncture sites can be improved and it highlights the need to improve patient knowledge.

Effect of pore size and spacing on neovascularization of a biodegradble shape memory polymer perivascular wrap

Neointimal hyperplasia (NH) is a main source of failures in arteriovenous fistulas and vascular grafts. Several studies have demonstrated the promise of perivascular wraps to reduce NH via promotion of adventitial neovascularization and providing mechanical support. Limited clinical success thus far may be due to inappropriate material selection (e.g., nondegradable, too stiff) and geometric design (e.g., pore size and spacing, diameter). The influence of pore size and spacing on implant neovascularization is investigated here for a new biodegradable, thermoresponsive shape memory polymer (SMP) perivascular wrap. Following an initial pilot, 21 mice were each implanted with six scaffolds: four candidate SMP macroporous designs (a-d), a nonporous SMP control (e), and microporous GORETEX (f). Mice were sacrificed after 4 (N = 5), 14 (N = 8), and 28 (N = 8) days. There was a statistically significant increase in neovascularization score between all macroporous groups compared to nonporous SMP (p < .023) and microporous GORETEX (p < .007) controls at Day 28. Wider-spaced, smaller-sized pore designs (223 μm-spaced, 640 μm-diameter Design c) induced the most robust angiogenic response, with greater microvessel number (p < .0114) and area (p < .0055) than nonporous SMPs and GORETEX at Day 28. This design also produced significantly greater microvessel density than nonporous SMPs (p = 0.0028) and a smaller-spaced, larger-sized pore (155 μm-spaced, 1,180 μm-sized Design b) design (p = .0013). Strong neovascularization is expected to reduce NH, motivating further investigation of this SMP wrap with controlled pore spacing and size in more advanced arteriovenous models.

Abnormal preoperative digital brachial index is associated with lower 2-year arteriovenous fistula access patency

OBJECTIVE

The aim of the present study was to assess whether a single measurement of the digital brachial index (DBI; systolic finger pressure/systemic pressure ratio), reflecting the arm's circulation, was associated with access patency in patients with severe chronic kidney disease scheduled for arteriovenous fistula (AVF) creation.

METHODS

A bilateral DBI was obtained using digital plethysmography just before construction of the patient's first AVF from January 2009 to December 2017 at one center. A DBI of 80% to 99% was considered normal, and a DBI of <80% (low) or DBI of ≥100% (high) were considered abnormal. DBI values ipsilateral to the AVF were used for analysis. The primary and secondary access patency rates were calculated using reported standards and compared using standard statistical techniques.

RESULTS

Data sets of 163 patients were obtained (69 women; age, 71 ± 12 years). The median follow-up was 40 weeks (range, 0-104 weeks; follow-up index, 99% ± 1%). Patients with abnormal preoperative DBI values had lower 2-year primary patency rates (low DBI, 25% ± 11%; high DBI, 28% ± 6%; normal DBI, 49% ± 8%; P = .018). After correction for age, sex, hypertension, diabetes mellitus, cardiovascular disease, smoking status, and a history of ipsilateral central venous catheter use, an adjusted model demonstrated that abnormal DBI values conferred an increased risk of primary patency failure (low DBI [<80%]: hazard ratio [HR], 2.25; 95% confidence interval [CI], 1.13-4.48; high DBI [≥100%]: HR, 1.74; 95% CI, 1.06-2.85; P < .030 for both). Patients with a low preoperative DBI had also had diminished secondary patency (HR, 2.86; 95% CI, 1.08-7.59; P = .035). In contrast, the diameters of the outflow veins did not determine access patency.

CONCLUSIONS

Patients with abnormal DBI values before AVF construction for hemodialysis had lower 2-year access patency rates compared with patients with a normal DBI. Plethysmographic finger measurements might have a role in the preoperative counseling of patients with severe chronic kidney disease requiring an AVF.

Inferiority of arteriovenous grafts, in comparison to autogenous fistulas, is underestimated by standard survival measures alone

BACKGROUND

It has been argued that a prosthetic arteriovenous graft (AVG) is a reasonable alternative to an arteriovenous fistula (AVF) for dialysis. We aimed to compare the patency rates and requirements for the intervention of newly formed AVF and AVG.

METHODS

A retrospective analysis was undertaken of AVF and AVG formed between 1 January 2013 and 31 December 2015 at two tertiary referral centres and followed up until 31 December 2017. Outcome measures included successful use for dialysis, patency rates and the number of interventions required to maintain dialysis access per patient-year (PPY).

RESULTS

Four hundred and seventy AVF and 92 AVG were constructed. Of 470 AVF, 324 (68.9%) were used compared to 80 of 92 (87%) AVG. One year assisted primary patency of AVF was 75% (confidence interval 71-79%) compared to 47% (confidence interval 36-57%) for AVG. Secondary patency rates for AVF at 1, 2 and 3 years were 77%, 71% and 69%, respectively. At the same time points, secondary patency rates for AVG were 77%, 60% and 46%, respectively (log rank P = 0.034). AVG required 2.4 times the number of interventions PPY than AVF. Surgical thrombectomy of AVG was at a rate of 0.49 PPY compared with 0.042 PPY for AVF.

CONCLUSION

AVG have a substantially higher rate of thrombosis than AVF, evident from early in the life of the graft. AVF demonstrate superior patency rates to AVG throughout the life of the access, with far fewer interventions PPY than grafts.

Comparison of Percutaneous Transluminal Angioplasty with Stenting for Treatment of Central Venous Stenosis or Occlusion in Hemodialysis Patients: A Systematic Review and Meta-analysis

OBJECTIVES

A common cause of hemodialysis vascular access dysfunction, a primary cause of morbidity and mortality in patients undergoing hemodialysis, is central venous stenosis or occlusion. The present study compared percutaneous transluminal angioplasty (PTA) with percutaneous transluminal angioplasty and stent placement (PTS) for treatment of central venous stenosis or central vein occlusion in hemodialysis patients.

METHODS

A systematic literature review was conducted using database searches of PubMed, Cochrane, and Embase. Articles were selected using the Population/Intervention/Comparator/Outcomes (PICO) process. Outcomes included the rate of procedural success, primary patency, assisted primary patency, re-intervention subjects, re-intervention rate, and adverse events.

RESULTS

A total of eight studies were included in the meta-analysis with subjects in the PTA group (n = 281) or PTS group (n = 192). Primary patency rate between PTA and PTS groups at 3-, 6-, 12-, or 24-month follow-up was not different (all p > 0.05). Patients treated with PTA had greater assisted primary patency rates than the PTS group (OR = 1.03, 1.73, 1.03, and 2.00 at 3, 6, 12, and 24 months, respectively). However, the statistical assessment only showed significantly at 24-month follow-up (p = 0.01).

CONCLUSIONS

The present meta-analysis revealed that, compared to PTS, PTA may provide increased assisted primary patency for endovascular treatment of central vein stenosis or occlusion in patients undergoing hemodialysis.

LEVEL OF EVIDENCE

Level 3a.

Treatment of failing arterio-venous dialysis graft by angioplasty, stent, and stent graft: Two-years analysis of patency rates and cost-effectiveness

The objective of this prospective randomized single-center study was to compare primary and secondary patency rates, number of percutaneous transluminal angioplasty (PTA) interventions and cost-effectiveness among PTA, deployment of a stent, or a stent graft in the treatment of failing arteriovenous dialysis grafts (AVG) due to restenosis in the venous anastomosis or the outflow vein. Altogether 60 patients with failing AVG and restenosis in the venous anastomosis or the outflow vein were randomly assigned to either PTA, placement of a stent (E-Luminexx^®) or stent graft (Fluency Plus^®). After the procedure, patients with stent or stent graft received dual antiplatelet therapy for the next three months. Follow-up angiography was scheduled at 3, 6, and 12 months unless requested earlier due to suspected stenosis or malfunction of the access. Subsequently, angiography was performed only if requested by the clinician. During a median follow-up of 22.4 (IQR=5.7) months patients with PTA, stent, or stent graft required 3.1±1.7, 2.5±1.7, or 1.7±2.1 (P=0.031) secondary PTA interventions. The primary patency rates were 0, 18 and 65% at 12 months and 0, 18 and 37% at 24 months in the PTA, stent, and stent graft group respectively (P<0.0001). The cost of the procedures in the first two years was €7,900±€3,300 in the PTA group, €8,500±€4,500 in the stent group, and €7,500±€6,200 in the stent graft group (P=0.45). We conclude that the treatment of failing dialysis vascular access by the deployment of a stent graft significantly improves its primary patency rates and decreases the number of secondary PTA interventions; however, the reduction in costs for maintaining AVG patency is not significant.

Efficacy of Primary Stent-Graft Placement in the Treatment of Vascular Access Graft Outflow Tract Stenosis

PURPOSE

The aim of this study is to present our personal experience using covered nitinol stent-graft in the treatment of outflow tract stenosis of arteriovenous grafts (AVGs) for hemodialysis access.

MATERIALS AND METHODS

Between May 2015 and October 2017, we retrospectively evaluated 36 (24 males, 12 females; mean age: 65.6 years) patients with AVGs on hemodialysis who underwent percutaneous angioplasty followed by endovascular stent-graft deployment for the treatment of stenosis of the venous outflow of the AVG. Indication for treatment included early restenosis (<3 months after previous percutaneous transluminal angioplasty [PTA]), long stenosis (stenoses >50% extending for a length >5 cm), and recoil of the stenosis after PTA performed with a noncompliant high-pressure balloon. Of 36 patients, 27 (75%) required surgical thrombectomy prior to endovascular procedure. Technical success, clinical success, primary and secondary patency, and safety were evaluated.

RESULTS

Technical success was 100%, and clinical success was 94.4%. Primary patency was 94.4%, 72.2%, 63%, 45.9%, and 45.9% at 1, 3, 6, 12, and 18 months (average: 215 days, range: 9-653 days); secondary patency was 94.4% and 86.1% at 1 and 3 months; 80.4% at 6, 12, and 18 months; and 53.6% at 24 months (average: 276.8 days, range: 9-744 days). No deaths were registered.

CONCLUSIONS

In selected cases, the use of stent-graft represents an effective and safe solution for the treatment of stenotic complications of the venous outflow of AVGs, even in the setting of access thrombosis.

Comparative efficacy and safety of local and peripheral venous thrombolytic therapy with urokinase for thrombosed hemodialysis arteriovenous fistulas

Arteriovenous fistula (AVF) thrombosis is a common complication in patients undergoing hemodialysis, and early intervention is required. Urokinase has been used as a thrombolytic agent for declotting the thrombosed access. However, the optimal route for infusing urokinase remains to be determined. In the present retrospective observational study, 49 patients who underwent local venous infusion and 57 patients with peripheral venous infusion of urokinase were included. A urokinase dosage of 300,000 U was administered until successful thrombolysis, which was a maximum of three times. Age, sex, period of dialysis, time of AVF placement, systolic and diastolic blood pressure and thrombus age were similar between the two groups. The efficacy of urokinase infusion via the two routes in resolving thrombosed AVFs, defined as successful fibrinolysis, and the safety, defined as the number of bleeding events, was compared. The cumulative thrombolysis success rate following three sessions of thrombolytic therapy in the local venous thrombolysis group was higher compared with that in the peripheral venous thrombolysis group (85.7 vs. 68.4%; P=0.04). The local thrombolysis group exhibited less ecchymosis (4.1 vs. 14.0%; P=0.07), epistaxis (2.0 vs. 10.5%; P=0.08) and gingival bleeding (4.1 vs. 19.3%; P=0.02) events compared with the peripheral thrombolysis group. Further analyses demonstrated that systolic [odds ratio (OR)=1.10; 95% confidence interval (CI), 1.03-1.17; P<0.01] and diastolic (OR=1.08; 95% CI, 1.02-1.14; P<0.05) blood pressure were protective factors, whereas thrombus age (OR=0.91; 95% CI, 0.84-0.99; P<0.05) was a risk factor for thrombolysis success among patients who underwent local thrombolytic therapy. Overall, the results suggest that local venous infusion of urokinase is superior to peripheral venous infusion for the treatment of patients with thrombosed fistulas.

Partial aneurysmectomy for treatment of autologous hemodialysis fistula aneurysm is safe and effective

OBJECTIVE

The purpose of this study was to evaluate the outcome and the factors associated with stenosis after treatment using partial aneurysmectomy for aneurysm in autologous arteriovenous fistulas.

METHODS

This retrospective cohort study was conducted from July 2007 to June 2016 and included patients with complicated aneurysms in upper extremity autologous arteriovenous fistulas were treated by partial aneurysmectomy. Vascular ultrasound examination was performed every 6 months after the surgery.

RESULTS

Forty-one patients (median age, 37 years; 70.7% males) were included. Of the patients, 95.1% had a radial-cephalic fistula in the forearm and nearly 88% had 1 or 2 aneurysms in arteriovenous fistulas that had been created for 10 to 84 months. Technical success of partial aneurysmectomy was achieved in all patients. The access diameter (44.0 ± 5.1 mm vs 10.4 ± 1.8 mm; P < .01) and brachial artery blood flow (1618.2 ± 277.0 mL/min vs 772.1 ± 127.4 mL/min; P < .01) were significantly decreased after the surgery. The median follow-up time was 27 months (range, 12-43 months). The primary patency rates at 6 and 12 months were 100% and 95%, respectively. Loss of patency was due to stenosis of the remodeled fistulas, which occurred in seven patients (17%). Multivariate COX regression analysis revealed that diabetes (hazard ratio, 114.28; 95% confidence interval, 2.85-4583.94; P = .01) was a risk factor for the impaired primary patency rates. A larger postprocedure residual diameter trended to favor fistula patency (hazard ratio, 0.46; P = .07). Stenosis was successfully treated with percutaneous transluminal angioplasty.

CONCLUSIONS

Partial aneurysmectomy is an effective and safe method for treating aneurysm of upper extremity autologous arteriovenous fistulas, leading to good 12-month primary patency and no aneurysm recurrence. Using a larger catheter to size the revised fistula during aneurysmectomy may increase access patency.

Role of neutrophil-to-lymphocyte ratio as a prognostic indicator for hemodialysis arteriovenous fistula failure

OBJECTIVE

To evaluate the role of preoperative peripheral blood neutrophil-to-lymphocyte ratio in predicting early arteriovenous fistula failure. The impact of postoperative neutrophil-to-lymphocyte ratio on arteriovenous fistula failure was also investigated.

METHODS

Medical records from 470 patients who underwent first-time arteriovenous fistula creation were studied. Demographic, clinical, and laboratory data were obtained. Receiver operating characteristic curves were constructed to determine the optimal cutoff values of preoperative and postoperative neutrophil-to-lymphocyte ratios for predicting early arteriovenous fistula failure. Univariate and multivariate analyses were performed to evaluate whether the neutrophil-to-lymphocyte ratio parameters were prognostic indicators for arteriovenous fistula failure.

RESULTS

Complete data from 396 patients were studied. The prevalence of early arteriovenous fistula failure was 30.6%. The optimal cutoff values of preoperative and postoperative neutrophil-to-lymphocyte ratios for predicting early arteriovenous fistula failure were 2.7 (82.6% sensitivity and 52.0% specificity) and 2.9 (78.5% sensitivity and 73.1% specificity), respectively. By univariate and multivariate analyses, high preoperative and postoperative neutrophil-to-lymphocyte ratios were significantly associated with early arteriovenous fistula failure. The adjusted odds ratios were 5.46 (95% confidence interval: 3.15-9.48) and 7.19 (95% confidence interval: 4.12-12.55), respectively.

CONCLUSIONS

High preoperative and postoperative neutrophil-to-lymphocyte ratios significantly predict early arteriovenous fistula failure.

A novel hybrid silk-fibroin/polyurethane three-layered vascular graft: towards in situ tissue-engineered vascular accesses for haemodialysis

Clinically available alternatives of vascular access for long-term haemodialysis-currently limited to native arteriovenous fistulae and synthetic grafts-suffer from several drawbacks and are associated to high failure rates. Bioprosthetic grafts and tissue-engineered blood vessels are costly alternatives without clearly demonstrated increased performance. In situ tissue engineering could be the ideal approach to provide a vascular access that profits from the advantages of vascular grafts in the short-term (e.g. early cannulation) and of fistulae in the long-term (e.g. high success rates driven by biointegration). Hence, in this study a three-layered silk fibroin/polyurethane vascular graft was developed by electrospinning to be applied as long-term haemodialysis vascular access pursuing a 'hybrid' in situ engineering approach (i.e. based on a semi-degradable scaffold). This Silkothane^® graft was characterized concerning morphology, mechanics, physical properties, blood contact and vascular cell adhesion/viability. The full three-layered graft structure, influenced by the polyurethane presence, ensured mechanical properties that are a determinant factor for the success of a vascular access (e.g. vein-graft compliance matching). The Silkothane^® graft demonstrated early cannulation potential in line with self-sealing commercial synthetic arteriovenous grafts, and a degradability driven by enzymatic activity. Moreover, the fibroin-only layers and extracellular matrix-like morphology, presented by the graft, revealed to be crucial in providing a non-haemolytic character, long clotting time, and favourable adhesion of human umbilical vein endothelial cells with increasing viability after 3 and 7 d. Accordingly, the proposed approach may represent a step forward towards an in situ engineered hybrid vascular access with potentialities for vein-graft anastomosis stability, early cannulation, and biointegration.

Omega-3 fatty acids for dialysis vascular access outcomes in patients with chronic kidney disease

BACKGROUND

Maintaining long-term vascular access patency is necessary for high quality haemodialysis (HD) treatment of patients with the terminal and most serious stage of chronic kidney disease (CKD) - end-stage kidney disease (ESKD). Oral supplementation with omega-3 fatty acids (ω-3FA) may help to prevent blockage of the vascular access by reducing the risk of thrombosis and stenosis.

OBJECTIVES

To evaluate the efficacy and safety of ω-3FA supplementation versus placebo or no treatment for maintaining vascular access patency in ESKD patients undergoing HD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 23 July 2018 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of omega-3 fatty acids versus placebo that assessed the patency of arteriovenous fistula (AVF) or arteriovenous graft (AVG) types of vascular access in ESKD patients.

DATA COLLECTION AND ANALYSIS

We assessed the risk of bias of each eligible study using the Cochrane Risk of Bias tool and made separate overall risk of bias judgments for the efficacy and safety outcomes. The certainty of evidence was assessed using the GRADE approach. The primary efficacy outcome was loss of vascular patency and the primary safety outcomes were occurrences of serious adverse events (e.g. death, hospitalisation, cardiovascular events, major bleeding). Secondary outcomes were the occurrence of non-serious adverse events (e.g. minor bleeding, gastrointestinal events and other adverse events). Efficacy effects were reported as risk ratios (RR) and safety effects as risk differences (RD) with 95% confidence intervals (CI). Studies were pooled separately by type of vascular access using a random-effects model.

MAIN RESULTS

Five studies (833 participants) were included; one was a very small pilot study of 7 participants. All studies compared oral ω-3FA supplements against placebo. Four studies enrolled participants with arteriovenous grafts (AVGs), and the other had participants with arteriovenous fistulas (AVFs). The risk of bias for both efficacy and safety outcomes was unclear for all studies, due mainly to incomplete reporting for allocation concealment and incompleteness of study follow-up.In AVF patients, ω-3FA supplementation probably makes little or no difference to the 12-month risk of patency loss (1 study, 536 participants: RR 1.01, 95% CI 0.84 to 1.21; moderate certainty evidence), risk of death (1 study, 567 participants: RD 0.00, 95% CI -0.03 to 0.02; moderate certainty evidence) and risk of hospitalisation (1 study, 567 participants: RD 0.00, 95% CI -0.08 to 0.08; low certainty evidence). There was no information on cardiovascular events and major bleeding.In AVG patients, it is very uncertain whether ω-3FA supplementation reduces the risk of patency loss within 6 months (2 studies, 41 participants: RR 0.91, 95% CI 0.36 to 2.28; very low certainty evidence) or 12 months (2 studies, 220 participants: RR 0.59, 95% CI 0.27 to 1.31; very low certainty evidence). ω-3FA supplementation may make little or no difference to the risk of death within 6 to 12 months in AVG patients (4 studies, 261 participants: RD 0.01, 95% CI -0.05 to 0.07; low certainty evidence). It is very uncertain if ω-3FA supplementation increases the risk of hospitalisation (3 studies, 65 participants: RD 0.08, 95% CI -0.11 to 0.28; very low certainty evidence), changes the risk of cardiovascular events (4 studies, 261 participants: RD -0.02, 95% CI -0.11 to 0.07; very low certainty evidence), or increases the risk of major bleeding (3 studies, 65 participants: RD 0.08, 95% CI -0.11 to 0.28; very low certainty evidence) within 6 to 12 months in AVG patients. There may be an increase in the risk of mild gastrointestinal adverse reactions (3 studies, 65 participants: RD 0.25, 95% CI 0.07 to 0.43; low certainty evidence) such as a sensation of bloatedness, gas or a fishy aftertaste.

AUTHORS' CONCLUSIONS

In CKD patients with an AVF, there is moderate certainty that ω-3FA supplementation makes little or no difference to preventing patency loss; and in patients with an AVG, it is very uncertain that ω-3FA supplementation prevents patency loss within 12 months.