Stent graft versus balloon angioplasty for failing dialysis-access grafts

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.

Pathological evaluation of a fluoropolymer-based drug-eluting stent in an arteriovenous graft outflow venous stenosis

A fluoropolymer-based drug-eluting stent was implanted in an arteriovenous graft outflow venous stenosis. Two and a half years later, due to a local infection, the stent was removed surgically, and a pathological evaluation was conducted. The stent struts exhibited partial endothelial cell coverage, with the remaining surface predominantly covered by fibrin. Notably, there was no evidence of restenosis or aneurysmal change.

Single-Cell Analyses Offer Insights into the Different Remodeling Programs of Arteries and Veins

Arteries and veins develop different types of occlusive diseases and respond differently to injury. The biological reasons for this discrepancy are not well understood, which is a limiting factor for the development of vein-targeted therapies. This study contrasts human peripheral arteries and veins at the single-cell level, with a focus on cell populations with remodeling potential. Upper arm arteries (brachial) and veins (basilic/cephalic) from 30 organ donors were compared using a combination of bulk and single-cell RNA sequencing, proteomics, flow cytometry, and histology. The cellular atlases of six arteries and veins demonstrated a 7.8× higher proportion of contractile smooth muscle cells (SMCs) in arteries and a trend toward more modulated SMCs. In contrast, veins showed a higher abundance of endothelial cells, pericytes, and macrophages, as well as an increasing trend in fibroblasts. Activated fibroblasts had similar proportions in both types of vessels but with significant differences in gene expression. Modulated SMCs and activated fibroblasts were characterized by the upregulation of MYH10, FN1, COL8A1, and ITGA10. Activated fibroblasts also expressed F2R, POSTN, and COMP and were confirmed by F2R/CD90 flow cytometry. Activated fibroblasts from veins were the top producers of collagens among all fibroblast populations from both types of vessels. Venous fibroblasts were also highly angiogenic, proinflammatory, and hyper-responders to reactive oxygen species. Differences in wall structure further explain the significant contribution of fibroblast populations to remodeling in veins. Fibroblasts are almost exclusively located outside the external elastic lamina in arteries, while widely distributed throughout the venous wall. In line with the above, ECM-targeted proteomics confirmed a higher abundance of fibrillar collagens in veins vs. more basement ECM components in arteries. The distinct cellular compositions and transcriptional programs of reparative populations in arteries and veins may explain differences in acute and chronic wall remodeling between vessels. This information may be relevant for the development of antistenotic therapies.

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.

Long-term outcomes following thrombolysis of arteriovenous grafts

BACKGROUND

Thrombolysis for arteriovenous grafts (AVG) yields high technical success rates, however, long-term outcomes are unclear. We conducted a multicenter retrospective cohort study to analyze 5-year patency rates following AVG thrombolysis.

METHODS

All patients who underwent AVG thrombolysis between 2005 and 2015 at three academic hospitals were included. Prospectively maintained institutional nephrology and radiology databases were used to record demographic, clinical, and AVG characteristics. The primary outcome was primary patency, defined as AVG access survival without re-intervention including angioplasty ± stent with/without re-thrombolysis. Secondary outcomes were assisted primary patency and cumulative patency, defined as AVG access survival until re-thrombosis requiring re-thrombolysis or abandonment, respectively. Technical success was defined as restoration of flow with <30% residual stenosis. Patients were followed until 2017. Patency rates were assessed using Kaplan-Meier survival analysis and Cox proportional hazards were calculated to determine associations between covariates and patency loss.

RESULTS

Seventy-four patients underwent AVG thrombolysis during the study period with a median follow-up period of 21.4 (IQR 8.3-42.8) months. The average age was 58.6 years with a high rate of comorbidities, including hypertension (82.4%) and diabetes (54.1%). Thrombolysis technical success was 96%. There were 147 re-interventions in 46 patients, of which 98 were re-thrombolysis (mean re-intervention rate of 1.27/patient/year). Primary patency at 1, 3, and 5 years were 43.2%, 20.2%, and 7.7%. Assisted primary patency at 1, 3, and 5 years were 47.5%, 20.2%, and 7.7%. Cumulative patency at 1, 3, and 5 years were 75.0%, 38.8%, and 22.6%. Cox proportional hazards analysis demonstrated no associations between demographic, clinical, and procedural characteristics and patency rates.

CONCLUSIONS

Despite a high technical success rate, thrombolysis for AVG dysfunction is associated with poor long-term patency. Future studies are needed to determine risk factors for re-thrombosis to identify patients who will benefit from AVG thrombolysis in the long-term.

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.

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.

Small Oversized Stent Graft Is Associated With Increased Patency for the Treatment of Central Venous Disease in Hemodialysis Patients

PURPOSE

The purpose of this study was to identify the independent predictors of higher patency rates and investigate the selection of specifications of stent graft in the treatment of central venous disease.

MATERIALS AND METHODS

This retrospective study included 54 patients who underwent stent-grafts' placement for the treatment of central venous disease between March 2017 and September 2022 at a tertiary hospital. The demographic data for the patients and the clinical data of the treated lesions were collected and analyzed. The patency rates of the treated lesions with different oversizing range were calculated via the Kaplan-Meier and log-rank analyses. The multivariate Cox proportional hazard models were constructed to identify the independent predictor of the target site primary patency.

RESULTS

The median follow-up period was 21.5 months. The primary patency rates of the target sites were 90.7%, 72.2%, and 55.1% at 6, 12, and 24 months, respectively. The assisted primary patency rates of the lesions were 96.3%, 92.5%, and 80.3% at 6, 12, and 24 months, respectively. The log-rank analysis showed that the stent-grafts' placement with small oversizing had significantly higher primary patency rates than those with large oversizing (p=0.022). The multivariate analysis revealed that concomitant stenosis and large oversizing stent graft were the independent predictors of target site primary patency.

CONCLUSIONS

Stent grafts showed reasonable primary patency for the treatment of central venous disease in hemodialysis patients. A stent graft with small oversizing is associated with better target site primary patency rates than those with large oversizing.

CLINICAL IMPACT

Stent grafts showed reasonable primary patency for the treatment of central venous disease in hemodialysis patients. Few studies, however, have explored the efficiency of stent grafts to treat CVD by considering different factors such as sizing considerations, the rate of oversizing percentage, etc. A stent graft with small oversizing is associated with better target site primary patency rates than those with large oversizing. Excessive oversizing should be avoided to prevent infolding or stent collapse.

Safety and efficacy of a new covered stent in hemodialysis vascular access outflow stenosis: A Brazilian multicenter retrospective study

BACKGROUND

Vascular stenosis commonly leads to dysfunction in hemodialysis vascular access. Although percutaneous transluminal angioplasty is an established treatment, stent utilization has increased in the last decade as an alternative solution to extend the access function. This study evaluated the safety and initial results of a new impermeable covered stent for treating vascular access outflow stenosis.

METHODS

Investigators retrospectively analyzed 114 hemodialysis patients treated with polytetrafluorethylene-covered stents from September 2018 to September 2022 across four centers. Lesions treated were de novo or restenotic and located in the venous graft anastomosis, outflow segment, cephalic arch, and basilic swing point. Patients were followed by in-person physical examination at 1, 3, and 6 months, and Duplex ultrasound was performed to evaluate the vascular access circuit and in-stent restenosis. The primary efficacy endpoint was target lesion primary patency at 1, 3, and 6 months. Secondary endpoints included access circuit primary patency and secondary patency at 1, 3, and 6 months. The primary safety endpoint was freedom from local or systemic serious adverse events through 30 days post-procedure.

RESULTS

Forty-four patients had thrombosed access at the initial presentation, and 41 patients presented with recurrent stenosis. The target lesion primary patency rates at 1, 3, and 6 months were 100%, 89.4%, and 74%, respectively. The access circuit primary patency rates were 100% at 1 month, 85% at 3 months, and 62.7% at 6 months. The secondary patency rates at 1, 3, and 6 months were 100%, 96.4%, and 94.6%, respectively. In the adjusted multivariate Cox regression analysis, only recurrent lesions and female gender were associated with reduced primary patency rates. No serious adverse event was observed through the first 30 days post-procedure.

CONCLUSION

In this retrospective analysis, a new covered stent was shown to be safe and effective for treating peripheral outflow stenosis in vascular access.

Use of Covered Stents in Cannulation Sites as a Last Option to Salvage Failing Vascular Access

PURPOSE

Controversy exists regarding the treatment of recurrent stenosis in vascular access at cannulation sites with a covered stent as repeated cannulation may damage the stent. The purpose of this study was to review covered stent placement at cannulation sites to salvage failing vascular access.

MATERIALS AND METHODS

A total of 11 patients were included for the purpose of this study. Eight patients (72.7%) received a covered stent due to recurrent stenosis, 2 (18.2%) due to an acute occlusion, and in 1 case (9.1%), the covered stent was used to repair a damaged polytetrafluoroethylene arteriovenous graft (PTFE AVG).

RESULTS

Primary patency after stent placement was 40.9% at 6 months, primary-assisted patency was 79.5% at 12 months, and secondary patency was 80% at 24 months. No significant problems were observed during the dialysis sessions after stent placement. The intervention rate per patient-year was not significantly different before or after covered stent placement, at 3.8 (IQR=9.5) interventions per year versus 2.5 (IQR=3.0) interventions per year (p=0.280).

CONCLUSION

In conclusion, treating failing vascular access with problems at cannulation sites with covered stents can be considered.

CLINICAL IMPACT

Treating vascular access stenosis at cannulation sites with covered stents can successfully prolong vascular access life.

A Prospective Multicenter Randomized Controlled Trial for Comparing Drug-Coated and Conventional Balloon Angioplasty in Venous Anastomotic Stenosis of Hemodialysis Arteriovenous Grafts

PURPOSE

To evaluate the efficacy and safety of drug-coated balloon angioplasty compared to conventional balloon angioplasty in the treatment of dysfunctional arteriovenous grafts.

MATERIALS AND METHODS

This prospective, multicenter, randomized clinical trial enrolled 190 patients with venous anastomotic stenosis in arteriovenous grafts at five participating hospitals. During pre-dilation, 4 patients dropped out due to ruptures requiring further treatment (n = 2) and residual stenosis of > 30% (n = 2). On successful pre-dilation with a 7 mm conventional balloon, patients were randomized to undergo either a 7 mm drug-coated balloon (n = 94) or conventional balloon angioplasty (n = 92). The primary out-come measure was target lesion primary patency at 3 and 6 months. The secondary out-come measures included target lesion primary patency at 12 months and access circuit primary patency at 6 and 12 months, clinical and technical success rates, and 12-month mortality differences between the groups.

RESULTS

The target lesion primary patency and access circuit patency rates at 3 and 6 months were significantly higher in drug-coated balloon angioplasty group as compared to conventional balloon angioplasty group. The technical and clinical success rates were 100% for both the groups. As a procedure-related complication, anastomotic site rupture occurred during pre-dilation in 4 cases. The number of deaths during the 12-month follow-up was one for each group. The number of early thrombotic events (at < 3 months) was significantly higher in the drug-coated balloon group (p = 0.002).

CONCLUSION

Drug-coated balloon angioplasty was more effective and safer for the treatment of dysfunctional arteriovenous grafts compared to conventional balloon angioplasty.

Sirolimus-coated balloon angioplasty in maintaining the patency of thrombosed arteriovenous graft: 1-year results of a prospective study

BACKGROUND

A prospective, pilot study was designed to test the feasibility of using sirolimus-coated balloon (SCB) to treat graft vein junction of thrombosed arteriovenous graft (AVG) following successful pharmacomechanical thrombectomy. The present report provides the 1-year results of this study.

METHODS

This is a 1-year follow-up of a single, prospective, single-arm study that was conducted from 2018 to 2019 in 20 patients who presented to a tertiary institution with thrombosed AVG. The recruited patients received SCB angioplasty at the graft-vein junction following successful endovascular thrombectomy of a thrombosed AVG. One year after recruitment, there were three deaths, one AVG revision, and one AVG explantation among the participants recruited. The outcomes of 15 subjects at 1-year following the index procedure obtained from electronic medical records were re-examined.

RESULTS

The 1-year access circuit primary patency rate was 40%, while assisted primary and secondary patency rates were 46.7% and 73.3%, respectively. A total of 16 interventions (4 angioplasties, 12 thrombectomies) were performed in 9 patients over the 12 months. Four AVGs were abandoned. The median number of interventions per patient was 1 (0-3) per year. Using Kaplan-Meier analysis, the mean estimated post-intervention access circuit primary patency was 230 (95% CI: 162-300) days, while access circuit assisted primary patency was 253 (95% CI: 187-320) days, and access circuit secondary patency was 292 (95% CI: 230-356) days. Sub-group analysis did not show a significant difference in the mean estimated primary patency between AVG with de novo and recurrent stenosis (245 days, 95% CI: 151-339 vs 210 days, 95% CI: 113-307; p = 0.29).

CONCLUSIONS

SCB may help sustain the patency of thrombosed AVG following successful thrombectomy.

Patency and Durability of Stent Grafts Placed in the Dialysis Circuit Cannulation Zone

PURPOSE

To investigate the safety, durability, and patency rates of stent grafts (SGs) placed in the cannulation zone of hemodialysis access circuits.

MATERIALS AND METHODS

From April 2020 to April 2023, all procedures with SGs placed in the cannulation zone were retrospectively analyzed. A total of 40 patients (25 men and 15 women) with SGs placed in the cannulation zone were included in the study. Mean age of the patients was 70 years. The Covera covered stent (BD, Franklin Lakes, New Jersey) was used in all cases. Of these, 26 were arteriovenous (AV) fistulae and 14 were AV grafts. SGs were placed for residual stenosis, perforation, aneurysm, and thrombosis. Follow-up outcomes were determined using follow-up angiographic images and included primary patency, primary-assisted patency, and secondary patency.

RESULTS

The primary patency of the target lesion was 89% (SD ± 5) and 74% (SD ± 8.4) at 6 and 12 months, respectively. The primary-assisted patency was 89% (SD ± 5.2) and 78% (SD ± 7.6) at 6 and 12 months, respectively. Secondary patency of the access circuit was 97% (SD ± 2.5) at both 6 and 12 months. Mean follow-up was 332 days (range, 28-661 days). All SGs were successfully cannulated for hemodialysis. No cases of stent fracture or stent infection were observed during follow-up.

CONCLUSIONS

SGs placed for cannulation zone pathologies can be safely cannulated for dialysis and have adequate short- and mid-term patency rates.

Advancements in Treatment Strategies for Chronic Mesenteric Ischemia: A Comprehensive Review

Chronic mesenteric ischemia (CMI) arises from the inability to achieve adequate intestinal blood flow after meals, leading to an imbalance between oxygen and metabolite supply and demand. The true incidence of CMI remains uncertain. However, the occurrence of mesenteric artery occlusive disease (MAOD) is relatively common among the elderly population. Delays in diagnosing CMI can often be attributed to several factors, including the variability in patient symptoms and the range of potential causes for chronic abdominal pain with weight loss. Mikkelson pioneered the introduction of a surgical treatment for occlusive lesions of the superior mesenteric artery (SMA) in 1957. The inaugural performance of endovascular revascularization (ER) for visceral vessels took place in 1980. The literature has documented two types of endovascular revascularization (ER) methods: percutaneous transluminal angioplasty (PTA) and primary stenting (PMAS). Despite the limited quality of available evidence, the consensus among experts is strongly in favor of PMAS over PTA alone for the treatment of atherosclerotic mesenteric artery stenosis. There are several key areas of focus for chronic mesenteric ischemia (CMI) treatment. Randomized controlled trials comparing different stent types, such as covered stents versus bare metal stents, are needed to evaluate efficacy, patency rates, and long-term outcomes in CMI patients.

Duplex ultrasound-guided angioplasty of hemodialysis vascular access

OBJECTIVE

Duplex ultrasound-guided angioplasty (DA) for hemodialysis vascular accesses remains questionable regarding its feasibility and safety. Minor complications (requiring no more treatment than nominal therapy) might be over-reported. Our hypothesis is that this procedure has no significant differences between observed rates and the recommended threshold of main outcomes of the procedure defined by the standards of arteriovenous fistulas (AVF) angioplasty.

METHODS

In a single-center retrospective study, 298 DA performed on 141 patients from 2015 to 2019 were analyzed. Occluded AVF or concomitant use of radiographic guidance were excluded. Duplex ultrasound parameters were collected up to 1 month before, at the end of angioplasty, and on day 30 after the procedure. Complications were registered, and patency rates were studied at 24 months of follow-up.

RESULTS

Anatomical success was achieved in 142 procedures (47.7%), clinical success in 284 (95.3%), and hemodynamic success in 283 (95.0%). Major complications-requiring at least a specific therapy-were reported in 8 procedures (2.7%) and minor complications-requiring no adjunctive therapy-in 157 (52.7%). At 24 months, overall postintervention primary patency was 34.0%, primary-assisted patency 87.4%, and secondary patency 92.5%. There were no significant differences of patency rates between groups with or without minor complications (P value for primary patency, 0.08; primary-assisted patency, 0.08; secondary patency, 0.23) or 30% residual stenosis (P value for primary patency, 0.82; primary-assisted patency, 0.46; secondary patency: 0.63). Duplex parameters further improved at postoperative day 30 after angioplasty.

CONCLUSIONS

DA of AVF is feasible, safe-despite over-reported minor complications having no impact on postintervention patency rates-and efficient. A minor complication can be seen as an event without bad or good consequences. Anatomical definition of success does not fit on DA for hemodialysis vascular access. Further studies are required to define the duplex parameter threshold for efficacy.

Longitudinal micro-incision creation prior to balloon angioplasty for treatment of arteriovenous access dysfunction in a real-world patient population: 6-month cohort analysis

INTRODUCTION

Routine hemodialysis depends on well-functioning vascular access. In the event of vascular access dysfunction, percutaneous transluminal balloon angioplasty (PTA) is conducted to restore patency. Although an angioplasty procedure can provide an excellent immediate result by opening the access to allow dialysis to continue, the long-term patency rates are less than satisfactory. The goal of this study was to assess the outcomes of patients who underwent a novel vessel preparation via longitudinal, controlled-depth micro-incisions prior to PTA.

METHODS

This multicenter, prospective, observational registry enrolled hemodialysis patients scheduled to undergo PTA of their arteriovenous fistula or graft due to clinical or hemodynamic abnormalities. A primary endpoint was anatomic success, defined as angiographic confirmation of <30% residual stenosis post-procedure without an adverse event. Additional assessments included device technical success, clinical success, freedom from target lesion revascularization, target lesion primary patency, and circuit primary patency at 6 months.

FINDINGS

A total of 148 lesions were treated with the FLEX Vessel Prep™ System (FLEX VP) prior to PTA in 114 subjects at eight clinical sites. Target lesions were 21 ± 25 mm in length with mean pre-procedure stenosis of 75.2% ± 4.7%. Five procedural complications were recorded without serious adverse events. Two subjects did not complete the follow-up evaluation. Target lesion primary patency across all subjects at 6-months was 62.2% with mean freedom from target lesion revascularization of 202.7 days. Target lesion primary patency and freedom from target lesion revascularization for AVF cases (n = 72) were 67.5% and 212.9 days, respectively. Target lesion primary patency and freedom from target lesion revascularization for AVGs (n = 42) were 52.4% and 183.3 days, respectively. In cases treating AVF cephalic arch stenosis (n = 25), 6-month target lesion primary patency was 70.6% and freedom from target lesion revascularization was 213.4 days.

DISCUSSION

This FLEX-AV registry demonstrates safety and effectiveness, notably in the cephalic arch and AVGs, when FLEX VP is used prior to PTA for treatment of vascular access dysfunction in a population of end-stage renal disease subjects.

Dialysis Access Maintenance: Plain Balloon Angioplasty

Plain balloon angioplasty remains the first-line treatment for dialysis access stenosis. This chapter reviews the outcomes of plain balloon angioplasty from cohort studies and comparative studies. Angioplasty outcomes are more favourable in arteriovenous fistulae (AVF) compared to arteriovenous grafts (AVG) with primary patency at 6 months ranging from 42-63% compared to 27-61%, respectively, and improved for forearm fistulae compared with upper arm fistulae. Higher pressures are required to treat stenoses in AVFs compared to AVGs. Outcomes are worse in more severe stenoses, increased patient age, previous interventions and fistulae that develop early stenoses. Major complication rates following angioplasty in dialysis access are between 3 and 5%. Repeat treatments and the use of adjuncts such as drug-coated balloons and stents can prolong the patency of dialysis access. Level of Evidence No level of evidence (Review paper).

Management of Central Venous Stenoses and Occlusions

Symptomatic central venous stenosis and occlusion remains the gordian knot of vascular access. Advances in techniques, like sharp recanalization, allowed for improved success rates in crossing these difficult lesions. There is also increasing evidence of new devices in treating central venous stenosis and, at the same time, improving the time needed between interventions. High-pressure balloons, paclitaxel-coated balloons, bare metal stents and covered stents have been tested with an aim to offer additional treatment options, although obstacles still exist. In the current review, authors describe relevant techniques and options, provide the evidence and evaluate the actual implementation of these devices in this demanding field.

Surgical Referral for Hemodialysis Access Maintenance

Hemodialysis access is the lifeline for end-stage renal disease patients. However, dialysis access is associated with a host of complications, including thrombosis, recurrent stenosis, infection, aneurysmal changes and bleeding. Although endovascular therapy remains the first-line treatment owing to its less invasive nature, there are certain situations where surgical referral is recommended or even necessary. Regardless, management of dialysis access complications requires a multidisciplinary approach. Interventional radiologists should be familiar with the appropriate timing for surgical referral to better serve the complex patient population.

A Randomised Trial Comparing Drug Coated Balloons and Conventional Balloons for the Treatment of Stent Graft Stenosis in Dialysis Vascular Access

OBJECTIVE

Previous studies on arteriovenous fistulas have demonstrated the potential benefit of drug coated balloons (DCBs) in maintaining the patency of dialysis access. However, stenoses involving stent grafts were excluded from these studies. Therefore, the aim was to evaluate the effectiveness of DCBs in treating stent graft stenosis.

METHODS

This was a prospective, single blinded, randomised controlled study. From March 2017 to April 2021, 40 patients with dysfunctional vascular access owing to stent graft stenosis were randomised to treatment with a DCB or conventional balloon. Clinical follow up was scheduled at one, three, and six months, and angiographic follow up was performed six months after the intervention. The primary outcome was angiographic late luminal loss at six months, and secondary outcomes included target lesion and access circuit primary patency at six months.

RESULTS

Thirty-six participants completed follow up angiography. The DCB group had a superior mean late luminal loss at six months compared with the control group (1.82 mm ± 1.83 mm vs. 3.63 mm ± 1.08 mm, respectively, p = .001). All 40 patients completed clinical follow up. The DCB group had a superior six month target lesion primary patency compared with the control group [hazard ratio (HR) 0.23, 95% confidence interval (CI) 0.07 - 0.71; p = .005). Additionally, the DCB group had a numerically higher six month access circuit primary patency rate than the control group, although the difference was not statistically significant (HR 0.54, 95% CI 0.26 - 1.11, p = .095).

CONCLUSION

Conventional balloon angioplasty is not durable in stent graft stenosis treatment. Treatment with DCBs provides less angiographic late luminal loss and potentially superior primary patency of the target lesion than treatment with conventional balloons. [ClinicalTrials ID: NCT03360279.].

Comparison of drug-coated balloon angioplasty versus common balloon angioplasty for arteriovenous fistula stenosis: A systematic review and meta-analysis

Drug-coated balloons (DCBs) have been used in dialysis patients with arteriovenous fistula (AVF) stenosis, but whether DCBs have advantages over ordinary balloons is still controversial. A meta-analysis was designed to investigate the safety and efficacy of DCBs and common balloons (CBs) in the treatment of AVF stenosis. We searched the PubMed, EMBASE, and China National Knowledge Internet (CNKI) databases for randomized controlled trials that evaluated the comparison of DCB angioplasty versus CB angioplasty for AVF stenosis in dialysis patients and reported at least one outcome of interest. The results showed that the DCB group had a higher first-stage patency rate of the target lesion 6 months [odds ratio, OR = 2.31, 95% confidence interval, CI: (1.69, 3.15), p < .01] and 12 months [OR = 2.09, 95% CI: (1.50, 2.91), p < .01] after surgery. There was no statistically significant difference in all-cause mortality between the two groups at 6 months [OR = 0.85, 95% CI: (0.47, 1.52), p = .58] and 12 months [OR = 0.99, 95% CI: (0.60, 1.64), p = .97]. Compared with CB, DCBs as a new endovascular treatment for AVF stenosis have a higher primary patency rate of target lesions and can delay the occurrence of restenosis. There is no evidence that DCB can increase the mortality of patients.

Prospective, randomized, multicenter clinical study comparing a self-expanding covered stent to percutaneous transluminal angioplasty for treatment of upper extremity hemodialysis arteriovenous fistula stenosis

Use of a covered stent after percutaneous transluminal angioplasty (PTA) was compared to PTA alone for treatment of upper extremity hemodialysis patients with arteriovenous fistula (AVF) stenoses. Patients with AVF stenosis of 50% or more and evidence of AVF dysfunction underwent treatment with PTA followed by randomization of 142 patients to include a covered stent or 138 patients with PTA alone. Primary outcomes were 30-day safety, powered for noninferiority, and six-month target lesion primary patency (TLPP), powered to test whether TLPP after covered-stent placement was superior to PTA alone. Twelve-month TLPP and six-month access circuit primary patency (ACPP) were also hypothesis tested while additional clinical outcomes were observed through two years. Safety was significantly non-inferior while six- and 12-month TLPP were each superior for the covered stent group compared to PTA alone (six months: 78.7% versus 55.8%; 12 months: 47.9% versus 21.2%, respectively). ACPP was not statistically different between groups at six-months. Observed differences at 24 months favored the covered-stent group: 28.4% better TLPP, fewer target-lesion reinterventions (1.6 ± 1.6 versus 2.8 ± 2.0), and a longer mean time between target-lesion reinterventions (380.4 ± 249.5 versus 217.6 ± 158.4 days). Thus, our multicenter, prospective, randomized study of a covered stent used to treat AVF stenosis demonstrated noninferior safety with better TLPP and fewer target-lesion reinterventions than PTA alone through 24 months.

Oscillometric pulse wave analysis for detecting low flow arteriovenous fistula

BACKGROUND

Pulse wave analysis may be useful to assess fistula function. We aimed to prospectively evaluate if convenient oscillometric devices are applicable to detect flow below 500 ml/min in a real life clinical setting.

METHODS

Pulse waves were recorded ambilaterally with the vicorder® device at the brachial artery in 53 patients on haemodialysis with native fistula. Primary variables consisted of the mean slope between the systolic maximum and the diacrotic notch (Slope2), the sum of the mean slopes in the four characteristic sections of pulse waves (Slope∑) and the amplitude of relative volumetric change in the measuring cuff at the upper arm (AMP). Fistula flow was measured with the use of duplex sonography using a standardized approach.

RESULTS

Parameter values above or below the median indicated measurement at the non-fistula side, with sensitivities/specificities of 0.79/0.79 (p < 0.001) for Slope 2, 0.64/0.64 (p = 0.003) for Slope∑ and 0.81/0.81 (p < 0.001) for AMP if measurements at the fistula and non-fistula arm were considered. ROC-analyses of parameter values measured at the fistula to detect low flow demonstrated AUCs (with CI) of 0.652 (0.437-0.866, p = 0.167) for Slope2, 0.732 (0.566-0.899, p = 0.006) for Slope∑ and 0.775 (0.56-0.991, p = 0.012) for AMP. The point with maximal youden's index was regarded as optimal cut-off, which corresponded to sensitivities and specificities of 0.8/0.56 for slope2, 0.86/ 0.56 for Slope∑ and 0.93/0.78 for AMP.

CONCLUSION

Functional surveillance with oscillometry is a promising clinical application to detect a low fistula flow. Among all investigated pulse wave parameters AMP revealed the highest diagnostic accuracy.

X-ray-guided and ultrasound-guided percutaneous transluminal angioplasty to treat arteriovenous fistula dysfunction in hemodialysis patients: A retrospective controlled study

PURPOSE

To compare the safety and efficacy of X-ray-guided and ultrasound-guided percutaneous transluminal angioplasty in treating arteriovenous fistula dysfunction.

MATERIALS AND METHODS

Data for 219 patients with arteriovenous fistula dysfunction between January 2016 and December 2018 were retrospectively analyzed. The primary endpoints were technical success, clinical success, and primary patency rates. The secondary endpoints were complications and secondary patency rates. Procedure outcomes and both endpoints were evaluated by propensity score analysis.

RESULTS

After the propensity score matching, 73 matched pairs of cases were created with 34 pairs of autogenous arteriovenous fistula cases and 39 pairs of prosthetic arteriovenous graft cases. There was no significant difference between the X-ray-guided and ultrasound-guided group, respectively, regarding the technical success rate (84.9% vs 87.7%, p = 0.630), clinical success rate (98.6% vs 97.3%, p = 0.999), and complications (10.9% vs 5.5%, p = 0.228). Although the 6- and 12-month secondary patency rates for the dialysis access between the two groups had significant difference (p < 0.05), there was no significant difference in primary and secondary patency curves between the two groups (p > 0.05).

CONCLUSION

The overall efficacy of ultrasound-guided versus X-ray-guided percutaneous transluminal angioplasty in treating arteriovenous fistula dysfunction might be comparable.

Dialysis Access Considerations in Kidney Palliative Care

In this review, we discuss common challenges at the interface between dialysis access planning, prognostication, and patient-centered decision making. Particularly for patients whose survival benefit from dialysis is attenuated by advanced age or other serious illness, knowing the potential complications and anticipated frequency of access procedures is essential for patients and families to be able to conceptualize what life on dialysis will look like. Although starting dialysis with a functioning graft or fistula is associated with reduced infection rates, mortality, hospitalizations, and cost compared with a central venous catheter, these benefits must be weighed against the chance that early access placement in an elderly or seriously ill patient is an unnecessary surgery because the chronic kidney disease never progresses, the patient dies before developing an indication to start dialysis, or, the patient prefers conservative kidney management over dialysis. Kidney palliative care is a growing subspecialty of nephrology focused on helping seriously ill patients navigate complex medical decisions, and may be useful for intensive goals-of-care discussions about treatment and access options for patients with limited anticipated survival because of age or other serious illness.

Bare-Metal Stent in Dysfunctional Hemodialysis Access: An Assessment of Circuit Patency according to Access Type and Stent Location

Purpose

To evaluate the circuit patency after nitinol bare-metal stent (BMS) placement according to the type of access and location of the stent in dysfunctional hemodialysis access.

Materials and Methods

Between January 2017 and December 2019, 159 patients (mean age, 64.1 ± 13.2 years) underwent nitinol BMS placement for dysfunctional access. The location of stents was as follows: 18 brachiocephalic vein, 51 cephalic arch, 40 upper arm vein, 10 juxta-anastomotic vein, 7 arteriovenous (AV) anastomosis, and 33 graft-vein (GV) anastomosis. Circuit patency was evaluated by the Kaplan-Meier method, and cox regression model.

Results

A total of 159 stents were successfully deployed in 103 AV fistula (AVF) and 56 AV graft (AVG). AVG showed lower primary and secondary patency at 12-months compared with AVF (primary patency; 25.0% vs. 44.7%; p = 0.005, secondary patency; 76.8% vs. 92.2%; p = 0.014). Cox regression model demonstrated poorer primary patency at 12 months after stenting in the cephalic arch and GV anastomosis compared with the other sites.

Conclusion

AVF showed better primary and secondary circuit patency at 12 months following the placement of BMS compared with AVG. Stents in the cephalic arch and GV anastomosis were associated with poorer primary patency at 12 months compared to those in other locations.

The role of stents in hemodialysis vascular access

Vascular access is the Achilles' heel of dialysis therapy among patient with end stage kidney disease. The development of neointimal hyperplasia and subsequent stenosis is common in vascular access and is associated with significant morbidity. Percutaneous transluminal angioplasty using balloon inflation was the standard therapy of these lesions. However, the balloon-based approaches were associated with poor vascular access patency rate necessitating new inventions. It is within this context that different types of stents were developed in order to improve the overall dialysis vascular access functionality. In this article, we review the available literature regarding the use of stents in treating dialysis vascular access stenotic lesions. Further, we review the major clinical trials of stent use in different anatomic locations and in different clinical scenarios.

Oxidative stress: An essential factor in the process of arteriovenous fistula failure

For more than half a century, arteriovenous fistula (AVFs) has been recognized as a lifeline for patients requiring hemodialysis (HD). With its higher long-term patency rate and lower probability of complications, AVF is strongly recommended by guidelines in different areas as the first choice for vascular access for HD patients, and its proportion of application is gradually increasing. Despite technological improvements and advances in the standards of postoperative care, many deficiencies are still encountered in the use of AVF related to its high incidence of failure due to unsuccessful maturation to adequately support HD and the development of neointimal hyperplasia (NIH), which narrows the AVF lumen. AVF failure is linked to the activation and migration of vascular cells and the remodeling of the extracellular matrix, where complex interactions between cytokines, adhesion molecules, and inflammatory mediators lead to poor adaptive remodeling. Oxidative stress also plays a vital role in AVF failure, and a growing amount of data suggest a link between AVF failure and oxidative stress. In this review, we summarize the present understanding of the pathophysiology of AVF failure. Furthermore, we focus on the relation between oxidative stress and AVF dysfunction. Finally, we discuss potential therapies for addressing AVF failure based on targeting oxidative stress.

Results of endovascular treatment of venous anastomotic stenosis in prosthetic arteriovenous for hemodialysis PTFE grafts. Comparative analysis between patent and occluded grafts

OBJECTIVE

To analyze the results of endovascular treatment of venous anastomotic stenosis (VAS) in humero-axillary arteriovenous grafts (HAG), comparing outcomes between patent and thrombosed HAG.

MATERIAL AND METHODS

A retrospective cohort study was made of endovascular treated patients because of a VAS in a HAG between January 2009 and December 2019. Group A: Thrombosed HAG secondary to a VAS. Group B: Patent HAG with a VAS detected during follow-up. Technical success was defined as residual stenosis after treatment <30%, and clinical success as satisfactory immediate dialysis after surgery. After ET a biannual clinical and ultrasound follow-up was performed.

STATISTICAL ANALYSIS

Survival analysis was performed for time-to-event data to assess patency.

RESULTS

Group A: 55 patients. Group B: 22. There were no significative differences in demographic and anatomical factors between groups. Technical and clinical success were 100% in group B and 94.5% and 91% respectively in group A. Primary patency at 1, 6 and 12 months was: Group A: 81.8%, 22.4% y 15.7% respectively. Group B: 100%, 85.9%, 76,4% (p < 0.001). Secondary patency at 1, 6 and 12 months was: Group A: 85.2%, 45.8% y 31.3% respectively. Group B 100%, 95.3%, 95.2% (p < 0.001). Use of non-covered stents was associated with an increased risk of occlusion (HR 2.669 IC 95% 1.146-6.216, p = 0.010).

CONCLUSION

A higher patency of EV performed on a patent HAG is expected. It is therefore advisable to develop surveillance programs that are capable to detect VAS before its occlusion.

Intimal Hyperplasia of Arteriovenous Fistula

Intimal hyperplasia (IH), a crucial histopathological injury, forms the basis of vascular stenosis and thrombogenesis. In addition, it is common in maladies such as stenosis at the anastomosis of arteriovenous fistula and restenosis after angioplasty. Various cellular and noncellular components play critical parts in the advancement of IH. This article reviews the distinctive components of IH, such as endothelial dysfunction, multiplication, and movement of vascular smooth muscle cells. Finally, in addition to synthesis of large amounts of extracellular matrix and inflammatory responses, which have frequently been studied in recent years, we offer a premise for clinical treatment with vascular smooth muscle cells.

Iatrogenic Fistula in Hemodialysis Patients: An Alternative Approach to Thrombectomy of Arteriovenous Graft (AVG) Thrombosis

Arterial venous (AV) fistula is the first choice of vascular access to perform hemodialysis in the vast majority of suitable patients followed by arteriovenous grafts (AVG). An iatrogenic fistula can occur when a second vein adjacent to the graft is punctured and the needle traverses the vein. In normal circumstances, this has no clinical repercussions and does not need correction, and in prior reports, it has helped to maintain the patency of partially occluded grafts but rarely can lead to thrombosis of the graft due to reduced flow and pressure in the graft lumen. We report here what we believe is a unique approach to perform thrombectomy of an occluded graft in a 71-year-old patient on hemodialysis to avoid placement of tunneled hemodialysis catheters and complications associated with catheters. When the outflow of basilic vein in this patient was thrombosed and could not be traversed, we successfully used an iatrogenic fistula as main outflow vein for the graft and created an alternative vein for drainage thus avoiding placement of a tunneled catheter for hemodialysis.

Cephalic arch restenosis rates in hemodialysis patients with brachiocephalic fistulae: a retrospective multicenter analysis of 3301 patients

Background

We evaluated restenosis rates at the cephalic arch after percutaneous angioplasty and stenting procedures in patients with brachial artery to cephalic vein arteriovenous fistula (BCAVF) hemodialysis access.

Methods

We used data from adult hemodialysis patients treated at a national network of 44 outpatient interventional facilities during Oct 2011–2015. We included data from patients with BCAVF who received an exclusive angioplasty, or stent with angioplasty, for treatment of cephalic arch stenosis and had ≥1 subsequent evaluation of the cephalic arch. Median percent restenosis per month at cephalic arch and days between encounters was calculated from the 1st index to 2nd procedure, and for up to 4 subsequent encounters. Analyses were stratified by intervention and device types.

Results

We identified a cohort of 3301 patients (mean age 62.2 ± 13.9 years, 58.5% male, 33.2% white race) with a BCAVF who had an angioplasty, or stent, at the cephalic arch for an index and ≥ 1 follow-up procedure. Between the 1st index to 2nd procedure, patients who received an angioplasty (n = 2663) or stent (n = 933) showed a median decrease of 18.9 and 16.5% in luminal diameter per month and a median time of 93 and 91 days between encounters, respectively. Restenosis and day rates were similar for standard versus high-pressure angioplasties. Bare metal stents showed 10.1 percentage point higher restenosis rate compared to stent grafts. Restenosis rates and time to restenosis were relatively consistent across subsequent encounters.

Conclusions

Findings suggest hemodialysis patients with a BCAVF who require an angioplasty or stent to treat a stenosis at the cephalic arch will have stenosis reformed at a rate of 18.9 and 16.5% per month after the first intervention, respectively. Findings suggest patients are at risk of having significant lesions at the cephalic arch within 3 months after the previous intervention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02728-4.

Drug-Coated Balloons for the Dysfunctional Vascular Access: An Evidence-Based Road Map to Treatment and the Existing Obstacles

An underlying stenosis within the venous limb of a hemodialysis access circuit is the main etiology for graft and fistula dysfunction as well as other symptoms such as arm, breast, and neck swelling. Treatment options for both peripheral and central venous stenoses include plain old balloon angioplasty, angioplasty with drug-coated balloons, and stenting. This article discusses the current evidence for the use of drug-coated balloon angioplasty in this patient population.

Endovascular Management of Thrombosed Dialysis Vascular Circuits

A functional hemodialysis vascular access is the lifeline for patients with end-stage kidney disease and is considered a major determinant of survival and quality of life in this patient population. Hemodialysis therapy can be performed via arteriovenous fistulas, arteriovenous grafts, and central venous catheters (CVCs). Following dialysis vascular access creation, the interplay between several pathologic mechanisms can lead to vascular luminal obstruction due to neointimal hyperplasia with subsequent stenosis, stasis, and eventually access thrombosis. Restoration of the blood flow in the vascular access circuit via thrombectomy is crucial to avoid the use of CVCs and to prolong the life span of the vascular access conduits. The fundamental principles of thrombectomy center around removing the thrombus from the thrombosed access and treating the underlying culprit vascular stenosis. Several endovascular devices have been utilized to perform mechanical thrombectomy and have shown comparable outcomes. Standard angioplasty balloons remain the cornerstone for the treatment of stenotic vascular lesions. The utility of drug-coated balloons in dialysis vascular access remains unsettled due to conflicting results from randomized clinical trials. Stent grafts are used to treat resistant and recurrent stenotic lesions and to control extravasation from a ruptured vessel that is not controlled by conservative measures. Overall, endovascular thrombectomy is the preferred modality of treatment for the thrombosed dialysis vascular conduits.

Stent Graft Outcomes in Dialysis Circuits: A Review of Clinical Trials and Literature

End-stage renal disease is a prevalent medical condition causing significant problems as the majority of patients are being treated with dialysis. While dialysis provides a means to compensate for the renal impairment, arteriovenous grafts and fistulas are often complicated by neointimal hyperplasia, loss of primary patency, and graft failure. Over the last decade, stent grafts have emerged as an alternative to balloon angioplasty and bare metal stents for revascularization in the event of arteriovenous graft occlusion or stenosis. Several randomized controlled trials have investigated the efficacy of stent grafts compared with balloon angioplasty for improving the function and durability of dialysis circuits. In this review, we present a comprehensive review of clinical trials. Stent grafts appear to offer increased primary patency over balloon angioplasty in the treatment of dialysis circuit stenosis. However, there is generally no significant difference between the two treatment modalities on other clinically relevant measures like complication rates and overall survival.

One-year outcomes and predictive factors for primary patency after stent placement for treatment of central venous occlusive disease in hemodialysis patients

Objective:

The study purpose was to determine the outcomes and factors predictive of primary stent patency for the treatment of central venous occlusive disease (CVOD) in hemodialysis patients.

Methods:

Data of 71 patients with CVOD treated with stent placement from January 2012 to December 2017 were analyzed. Univariate and multivariate analysis was performed to determine factors associated with stent patency. Adverse events related to stent placement were also examined.

Results:

The median primary patency duration of the 71 patients was 16 ± 2.2 months. The cumulative 3-, 6-, 9-, and 12- month primary patency rates were 93%, 72%, 55%, and 51%, respectively. Independent predictors of longer primary patency were vessel diameter > 12 mm, the use of a covered stent, and absence of vessel calcifications. Median primary patency of covered stents was 21 months as compared with only 10 months for bare stents (p < 0.001). Procedure-related adverse events occurred in 17 patients (21.8%), and four events (5.1%) required medical intervention. No life-threaten complications occurred.

Conclusions:

A vessel diameter > 12 mm, the use of a covered stent, and no vessel calcifications are independently associated with a higher primary patency rate after treatment of CVOD in hemodialysis patients.

Paclitaxel coated balloon versus conventional balloon angioplasty in dysfunctional dialysis arteriovenous fistula: a systematic review and meta-analysis of randomized controlled trials

Purpose

To compare the efficacy and safety between paclitaxel coated balloon (PCB) angioplasty and conventional balloon (CB) angioplasty in the treatment of dysfunctional arteriovenous fistula (AVF).

Methods

We searched four major electronic databases (PubMed, EMBASE, Web of Science and the Cochrane Library) for randomized controlled trials (RCTs) published from inception through November 28, 2021. Outcomes of interest included target lesion primary patency (TLPP), technical success and all-cause mortality. The STATA package version 15.1 was utilized to undertake meta-analyses.

Results

Fourteen RCTs totaling 1535 patients were analyzed. The available data showed that there were no significant differences of TLPP rates at 3, 6, 9 and 12 months between the PCB group and the CB group (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.93–1.07, p = 1.000, I² = 33.5%, Cochrane Q test p = 0.185, fixed-effect model; RR 1.17, 95% CI 0.99–1.39, p = 0.065, I² = 75.4%, Cochrane Q test p = 0.000, random-effect model; RR 0.81, 95% CI 0.35–1.89, p = 0.625, I² = 62.8%, Cochrane Q test p = 0.045, random-effect model; RR 1.19, 95% CI 0.97–1.47, p = 0.096, I² = 40.5%, Cochrane Q test p = 0.071, random-effect model). In addition, two groups had similar technical success rates (RR 1.00, 95% CI 0.97–1.03, p = 1.000, I² = 0.0%, Cochrane Q test p = 0.596, fixed-effect model) and all-cause mortality rates (RR 1.00, 95% CI 0.54–1.84, p = 1.000, I² = 0.0%, Cochrane Q test p = 0.599, fixed-effect model).

Conclusions

PCB angioplasty did not appear to convey any obvious advantage over CB angioplasty in the treatment of dysfunctional AVF. However, further multi-center, large-scale and well-designed RCTs are needed to prove outcomes.

An atypical case of hemodialysis access stent migration

Endovascular stent fractures are commonly seen in arteries but are rare events in the venous system. Stents deployed in hemodialysis vascular accesses can fracture and migrate to proximal locations. Complications associated with stent fracture include in-stent stenosis and central vein stenosis. In this report, we present a unique case of a hemodialysis access stent fracture that migrated to the left ventricle and manifested with chest pain.

Stent grafts improved patency of ruptured hemodialysis vascular accesses

This study aimed to compare stent graft with balloon tamponade for ruptured dialysis access during percutaneous transluminal angioplasty. Patients over an 8-year period (2010–2018) were identified from a database of 11,609 procedures. The primary endpoint was target lesion primary patency at 12 months. A total of 143 patients who had rupture dialysis access were enrolled, of whom 52 were salvaged by stent grafts and 91 were salvaged by balloon tamponade. The 6-month target lesion primary patency was greater in the stent graft group than in the balloon tamponade group (66.7% vs. 29.5%, P < 0.001). The benefit of stent grafts was sustained for 12 months (52.5% vs. 9.0%, P < 0.001). The stent grafts increased the median time from the index procedure to the next intervention in the ruptured area by 171 days (260 vs. 89 days) at 12 months. There was no significant difference in the access circuit patency rates at 6 months (25.5% vs. 19.8%, P = 0.203) and 12 months (12.0% vs. 5.8%, P = 0.052). The patency results of the stent grafts remained after the multivariable adjustment analysis. Compared to balloon tamponade alone, stent grafts provided superior target lesion primary patency at 6 and 12 months. The access circuit patency rates were similar.

SIroliMus coated angioPlasty versus plain balloon angioplasty in the tREatment of dialySis acceSs dysfunctION (IMPRESSION): study protocol for a randomized controlled trial

Background

Percutaneous transluminal angioplasty is the current standard treatment for arteriovenous fistula (AVF) stenosis. The mid- and long-term patency with plain balloon angioplasty (PBA) is however far from satisfactory. While paclitaxel-coated balloon angioplasty has been shown to be superior to PBA, concern over its safety profile has recently arisen after a reported possible increased mortality risk with a meta-analysis of large lower limb studies. An angioplasty balloon with a new type of drug coating, the sirolimus-coated balloon (SCB), has been proven to improve patency in the coronary arteries. However, its effect on AV access has yet to be studied.

Methods/design

This is an investigator-initiated, prospective, multicenter, double-blinded, randomized controlled clinical trial to assess the effectiveness of SCB compared to PBA in improving the patency of AVF after angioplasty. A total of 170 patients with mature AVF that requires PTA due to AVF dysfunction will be randomly assigned to treatment with a SCB or PBA at a 1:1 ratio, stratified by location of AVF and followed up for up to 1 year. The inclusion criteria include [1] adult patient aged 21 to 85 years who requires balloon angioplasty for dysfunctional arteriovenous fistula [2]; matured AVF, defined as being in use for at least 1 month prior to the angioplasty; and [3] successful angioplasty of the underlying stenosis with PBA, defined as less than 30% residual stenosis on digital subtraction angiography (DSA) and restoration of thrill in the AVF on clinical examination. The exclusion criteria include thrombosed or partially thrombosed access circuit at the time of treatment, presence of symptomatic or angiographically significant central vein stenosis that requires treatment with more than 30% residual stenosis post angioplasty, and existing stent placement within the AVF circuit. The primary endpoint of the study is access circuit primary patency at 6 months. The secondary endpoints are target lesion primary patency; access circuit-assisted primary patency; access circuit secondary patency at 3, 6, and 12 months; target lesion restenosis rate at 6 months; total number of interventions; complication rate; and cost-effectiveness. The trial is supported by Concept Medical.

Discussion

This study will evaluate the clinical efficacy and safety of SCB compared to PBA in the treatment of AVF stenosis in hemodialysis patients.

Trial registration

ClinicalTrials.govNCT04409912. Registered on 1 June 2020

First Clinical Results of the Merit WRAPSODY™ Cell-Impermeable Endoprosthesis for Treatment of Access Circuit Stenosis in Haemodialysis Patients

PURPOSE

This prospective, observational first in human study evaluated the safety and effectiveness of WRAPSODY^TM Cell-impermeable Endoprosthesis (Merit Medical Systems, Inc.) in the treatment of arteriovenous fistula and arteriovenous graft access circuit stenosis.

MATERIALS AND METHODS

Investigators conducted a prospective analysis of 46 patients with access circuit stenosis from three centres. Treatment sites included the peripheral outflow veins (e.g. cephalic arch, basilic vein swing point; 16 fistula and 10 graft patients); the graft-vein anastomosis (9 patients); and the central veins (up to, but not including the SVC; 11 patients). Primary outcome measures included 30-day freedom from access circuit-related safety events and 30-day target lesion primary patency. Secondary outcome measures included procedural success; device- and procedure-related adverse events; target lesion primary patency; access circuit primary patency; and secondary patency. In-person follow-up was scheduled at 1, 3, 6, and 12 months. An independent data monitoring/clinical event committee adjudicated all reinterventions and device/procedure-relatedness for adverse events.

RESULTS

All initial procedures were successful. All but one patient was free from safety events through the first 30 days (97.8% (45/46)). This event was not device-related. Over the remainder of the study, one adverse event was adjudicated as possibly device-related. Six- and 12-month target lesion primary patency rates were 97.7% (42/43) and 84.6.% (33/39), respectively. Six- and 12-month access circuit primary patency rates were 84.4% (38/45) and 65.9% (29/44), respectively.

CONCLUSION

Results suggest that the study device is safe and effective for treatment of stenoses in the peripheral and central veins of arteriovenous access circuits.

LEVEL OF EVIDENCE

Level 2b, cohort study.

Results of endovascular treatment of venous anastomotic stenosis in prosthetic arteriovenous for hemodialysis PTFE grafts. Comparative analysis between patent and occluded grafts

OBJECTIVE

To analyze the results of endovascular treatment of venous anastomotic stenosis (VAS) in humero-axillary arteriovenous grafts (HAG), comparing outcomes between patent and thrombosed HAG.

MATERIAL AND METHODS

A retrospective cohort study was made of endovascular treated patients because of a VAS in a HAG between January 2009 and December 2019. Group A: Thrombosed HAG secondary to a VAS. Group B: Patent HAG with a VAS detected during follow-up. Technical success was defined as residual stenosis after treatment <30%, and clinical success as satisfactory immediate dialysis after surgery. After ET a biannual clinical and ultrasound follow-up was performed.

STATISTICAL ANALYSIS

Survival analysis was performed for time-to-event data to assess patency.

RESULTS

Group A: 55 patients. Group B: 22. There were no significative differences in demographic and anatomical factors between groups. Technical and clinical success were 100% in Group B and 94.5% and 91% respectively in Group A. Primary patency at 1, 6 and 12 months was: Group A: 81.8%, 22.4% and 15.7% respectively. Group B: 100%, 85.9%, 76.4% (p<0.001). Secondary patency at 1, 6 and 12 months was: Group A: 85.2%, 45.8% and 31.3% respectively. Group B 100%, 95.3%, 95.2% (p<0.001). Use of non-covered stents was associated with an increased risk of occlusion (HR 2.669 95% CI 1.146-6.216, p=0.010).

CONCLUSION

A higher patency of EV performed on a patent HAG is expected. It is therefore advisable to develop surveillance programs that are capable to detect VAS before its occlusion.

Results of drug-eluting stent in significant restenosis of the hemodialysis access: An initial study

BACKGROUND

This study aimed to report the 12-month results of drug-eluting stent (DES) for the treatment of significant restenosis of the hemodialysis access.

MATERIALS AND METHODS

A total of 14 patients (seven men and seven women; median age 70 years; range of 50-83 years) with significant restenosis of hemodialysis accesses were enrolled from January 2017 to December 2018. A total of 10 arteriovenous graft (AVG) and four arteriovenous fistulae were treated with DES. Study outcomes included primary patency of the target lesion and circuit.

RESULTS

Venous anastomosis of the AVG was the most common target lesion for DES insertion (nine hemodialysis accesses). The range of follow-up time was 12-36 months. Primary patency rates of target lesion before DES (patency for last conventional balloon angioplasty [CBA]) versus target lesion after DES at 6 and 12 months were 29% versus 100% and 7% versus 86% (p < 0.001). Primary patency rates of pre-DES circuit (patency for last CBA) versus post-DES circuit at 6 and 12 months were 29% versus 64% and 7% versus 29%, respectively (p = 0.058).

CONCLUSION

DES might improve the patency rate of target lesion in patients with significant restenosis of the hemodialysis access.

Covered stents versus balloon angioplasty for failure of arteriovenous access: a systematic review and meta-analysis

INTRODUCTION

Patients with end-stage renal disease may require arteriovenous (AV) access in the form of arteriovenous fistulae (AVFs) or arteriovenous grafts (AVGs) for haemodialysis. AV access dysfunction requires intervention such as plain balloon angioplasty or covered stents to regain patency.

AIM

To systematically review and meta-analyse the patency outcomes of covered stents in failing haemodialysis AV access, compared with balloon angioplasty.

METHODS

The review was first registered on the International Prospective Register of Systematic Reviews (CRD42018069955) before data collection. We searched six electronic databases to identify relevant randomised controlled trials (RCTs) up until August 2020, without language restriction. Two reviewers assessed the suitability and quality of studies for inclusion using the Consolidated Standards of Reporting Trials guidelines. We meta-analysed data using a random-effects model.

RESULTS

We included seven studies including 1147 patients in the systematic review, of which 867 had AVGs and 280 had AVFs. One study was an ongoing RCT. In the meta-analyses, we assessed patients with failing AVGs only. Overall risk of bias was moderate. Covered stents were associated with lower loss of patency versus angioplasty alone at 6, 12 and 24 months (OR 4.48, 95% CI 1.98 to 10.14, p<0.001; OR 4.07, 95% CI 1.74 to 9.54, p=0.001; OR 2.24, 95% CI 1.17 to 4.29, p=0.01, respectively). Covered stents afforded superior access circuit primary patency compared with angioplasty alone at 6 and 12 months (OR 1.91, 95% CI 1.31 to 2.80, p<0.001; OR 1.97, 95% CI 1.14 to 3.41, p=0.02, respectively). This was not significant at 24 months. There was no significant difference in loss of secondary patency between groups at 12 or 24 months (OR 0.74, 95% CI 0.45 to 1.23, p=0.25; OR 0.67, 95% CI 0.29 to 0.154, p=0.34, respectively).

CONCLUSION

Our results support use of covered stents over angioplasty alone, at 6, 12 and 24 months in failing AVGs. Further clinical trials are warranted.

Arteriovenous fistulas for hemodialysis: Brief review and current problems

The number of people worldwide living with end-stage renal disease is increasing. Arteriovenous fistulas are the preferred method of vascular access in patients who will require hemodialysis. As the number of patients with arteriovenous fistulas grows, the role of physicians who intervene who maintain and salvage these fistulas will grow in importance. This review aims to familiarize practitioners with the rationale for arteriovenous fistula creation, the detection of fistula dysfunction, and the state of the art on fistula maintenance and preservation. Current controversies are briefly reviewed.

Dialysis access intervention: Techniques for the interventional cardiologist

Interventional cardiologists who treat malfunctioning hemodialysis accesses play an important role in the life of patients with end-stage kidney disease (ESKD). By collaborating with interventional nephrologists who currently perform the bulk of routine access angiographic procedures, interventional cardiologists can fill an important gap in the care of ESKD patients by performing urgent or emergent procedures that fall outside the schedule of an outpatient interventional nephrology laboratory to ensure that hemodialysis patients will not miss a hemodialysis session or get a temporary catheter. This paper reviews the pathophysiology of dialysis access failure and illustrates the catheter-based approaches used by interventional cardiologists to treat malfunctioning dialysis accesses.

Single-Center Prospective Pilot Study of Sirolimus Drug-Coated Balloon Angioplasty in Maintaining the Patency of Thrombosed Arteriovenous Graft

PURPOSE

To investigate the use of a sirolimus drug-coated balloon (DCB) in the management of a thrombosed arteriovenous graft (AVG).

MATERIALS AND METHODS

A single-center prospective pilot study was conducted between October 2018 and October 2019. Twenty patients (age = 67.0 years ± 10; male = 35%; mean time on dialysis = 31 months) with thrombosed upper limb AVG were enrolled. After successful pharmacomechanical thrombectomy and adequate treatment of the graft vein junction, sirolimus DCB angioplasty was performed at the graft vein junction. The patients were followed-up for 6 months, and all adverse events occurring during the study period were recorded.

RESULTS

The primary circuit patency rates at 3 and 6 months were 76% and 65%, respectively, while the assisted-primary circuit patency rates at 3 and 6 months were 82% and 65%, respectively. The 3- and 6-month secondary circuit patency rates were 88% and 76%, respectively. Using Kaplan-Meier analyses, the estimated mean primary, assisted-primary, and secondary patencies were 285 days (95% confidence interval (CI) = 194-376 days), 319 days (95% CI = 221-416 days), and 409 days (95% CI = 333-485 days). No adverse event directly related to sirolimus DCB use was observed.

CONCLUSIONS

The results of this pilot study suggest that the application of sirolimus DCB at the graft vein junction after the successful thrombectomy of AVG may be a feasible option to improve patency outcomes.