Comparison of Cutting Balloon versus High-Pressure Balloon Angioplasty for Resistant Venous Stenoses of Native Hemodialysis Fistulas

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.

Do Balloon Catheters have a Different Radial Force Along Their Longitudinal Axis?

PURPOSE

This experimental study was designed to compare radial forces between the central portion and both ends of balloon catheters when dilating stenosis.

MATERIALS AND METHODS

Three balloon catheters of 6 and 8 mm in diameter and of variable length were tested: Mustang, Conquest, and Genoss PTA. Cylindrical modules to position balloon catheters and install the measuring tip during radial force measurements were made using a 3D printer. The measuring tip created 20% stenosis at the inner lumen. Both ends and center of the balloon catheter were located at the measuring tip. The radial force was measured after inflating the balloon catheter to the rated burst pressure.

RESULTS

For the different diameters and lengths of balloon catheters and cylinder sizes, the median inccenter, the radial rease in radial force at the distal end compared to the center was 16.5% (range: 9.8-35.2%) for Mustang, 12.4% (range: 10.3-25.5%) for Genoss, and 7.4% (range: -0.3-13.1%) for Conquest balloon catheters. Similarly, compared to that at the force at the proximal end was 10.8% greater (range: -2.9-18.3%) for Mustang, 9.9% greater (range: 3.9-22.3%) for Genoss, and 7.3% greater (range: -1.3-12.4%) for Conquest catheters.

CONCLUSION

The radial force is greater at both ends of the balloon than at the central portion, especially at the distal end. Dilation using the distal end of the balloon catheter is a practical method that can be applied in clinical practice without additional devices when encountering resistant stenosis, especially with semi-compliant balloons.

Efficacy of cutting balloon angioplasty versus high-pressure balloon angioplasty for the treatment of arteriovenous fistula stenoses in patients undergoing hemodialysis: Systematic review and meta-analysis

This systematic review and meta-analysis aimed to assess and compare the therapeutic outcomes of cutting balloon angioplasty and high-pressure balloon angioplasty for arteriovenous fistula stenosis in hemodialysis patients. All studies indexed in PubMed, Embase, and Cochrane Library Web of Science were retrieved. The retrieval deadline was July 15, 2023. Risk of bias 2.0 was used to evaluate the quality of the included studies. Revman 5.4 software was used for data analysis. This review included three studies and 180 patients, with 90 patients in the cutting balloon angioplasty group and 90 patients in the high-pressure balloon angioplasty group. The results of the meta-analysis suggested that compared with high-pressure balloon angioplasty, cutting balloon angioplasty can improve primary lesion patency rates of internal arteriovenous fistulas at 6 months (relative risk, 1.45; 95% confidence interval, 1.08-1.96; P = 0.01). However, there were no significant differences between the technical success rate (relative risk, 0.99; 95% confidence interval, 0.93-1.05; P = 0.72) and clinical success rate (relative risk, 1.01; 95% confidence interval, 0.95-1.07; P = 0.73). Therefore, cutting balloon angioplasty is likely to increase primary lesion patency rates at 6 months. However, more high-quality, large-sample, multicenter, randomized controlled trials are needed for further validation due to the limited number of included studies.

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.

Comparison of peripheral cutting balloon angioplasty with conventional balloon angioplasty for recurrent hemodialysis vascular access stenosis: A prospective randomized controlled trial

PURPOSE

This study aimed to compare the efficacy and safety of cutting balloon angioplasty (CBA) and conventional balloon angioplasty (control group) for recurrent vascular access stenosis in arteriovenous fistulas.

MATERIALS AND METHODS

This prospective, randomized single-center clinical trial included patients with hemodynamically significant recurrent vascular access stenosis of an arteriovenous fistula. The Kaplan-Meier method was used to assess primary patency, whereas the log-rank test was used to evaluate differences in patency between groups. Functional evaluations were performed using Doppler ultrasonography.

RESULTS

Patients (n = 122) were randomly assigned to undergo CBA or conventional balloon angioplasty between December 2012 and November 2017. The clinical success rate was 100% in both groups. The anatomical success rates were 65% and 56% in the CBA and control groups, respectively. The primary patency of the target lesion was significantly better in the CBA group (33.3%) than in the control group (16.1%) at 6 months (hazard ratio, 0.50; 95% confidence interval, 0.33-0.77; p = 0.00171). The stenosis percentage decreased significantly after angioplasty in the CBA group (Δ-50.7%) compared with the control group (Δ-41.9%) (p = 0.0008). Access flow, measured using duplex Doppler ultrasonography, improved after angioplasty in both groups (300-526 ml/min in the control group and, 268-546 ml/min in the CBA group). Change in access flow (Δ + 278 ± 162) in the CBA group tended to be greater than that in the control group (Δ + 226 ± 151) (p = 0.07). However, the difference was not statistically significant.

CONCLUSION

In patients with recurrent vascular access stenosis of the arteriovenous fistula CBA is effective and superior to conventional angioplasty.

Relationship Between Intimal Thickness on Ultrasonography and Long-Term Patency of Arteriovenous Fistula Restenosis After Cutting Balloon Versus High Pressure Balloon Angioplasty

BACKGROUND

To investigate the relationship between intimal thickness on ultrasonography and long-term patency of arteriovenous fistula restenosis after cutting balloon and high pressure balloon angioplasty.

METHODS

We retrospectively compared the outcomes between cutting balloon angioplasty and high pressure balloon angioplasty in 149 patients with hemodialysis access restenosis. The relationship of intimal thickness and primary assisted patency of hemodialysis access on ultrasonography was investigated as the primary outcome, using Kaplan-Meier survival analysis and Cox proportional hazards model. The second outcomes included residual diameter, blood flow, and venous pressure of hemodialysis access before and after angiography and balloon diameter and inflation pressure.

RESULTS

Primary assisted patency in cutting balloon angioplasty was 90.6%, which was significantly (P = 0.001) more than that of 37.9% in high pressure balloon angioplasty during the 20-month follow-up period. Cox proportional hazards model screened significant factors including procedure type (high pressure or cutting, P = 0.004), inflation pressure (P = 0.013), preoperative intimal thickness (P = 0.009), and difference of intimal thickness (P = 0.029). Finally, procedure type (P = 0.012) and preoperative intimal thickness (P = 0.033) were identified for predicting primary assisted patency by multivariate Cox proportional hazards model.

CONCLUSIONS

Compared to high pressure balloon angioplasty for treating patients with hemodialysis access restenosis, cutting balloon angioplasty had a better primary assisted patency. The increase of intimal thickness on ultrasonography after angiography was inversely correlated with primary assisted patency.

Balloon rupture with eversion during innominate vein angioplasty requiring surgical retrieval

Balloon rupture during angioplasty can with calcified or recalcitrant lesions. A 61-year-old woman presented with worsening arm and facial swelling. She had a history of left upper extremity thrombolysis and stenting of the innominate vein 6 years prior. Venography showed severe in-stent stenosis. After crossing the lesion, a 12-mm balloon was inflated, which ruptured at nominal pressure. The balloon became stuck and could not be moved over the wire even after retraction of the sheath. A limited surgical cutdown was performed, and the balloon and the wire were removed together. The ruptured balloon part was found to be everted and circumferentially wrapped around the wire, preventing the wire exchange. After cutting the everted portion of the balloon, the catheter was removed without losing wire access. A high-pressure balloon was subsequently used to treat the lesion successfully. Her symptoms had resolved on follow-up, and the stent remained patent after 6 months.

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.].

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.

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.

Sharp Needle Recanalization Technique for Peripheral Hemodialysis Arteriovenous Fistula Occlusion

PURPOSE

To determine the efficacy of a percutaneous sharp needle recanalization technique for the treatment of peripheral hemodialysis arteriovenous fistula (AVF) occlusion.

MATERIALS AND METHODS

This study included 13 patients (14 procedures) between May 2010 and February 2020 with non-thrombotic AVF occlusion wherein guidewire passage through the occluded segment had failed. We successfully passed the guidewire through the occluded segment using a sharp needle recanalization technique with Chiba or Colapinto needles, under ultrasound or fluoroscopic guidance. The type of AVF, site and length of occlusion, technical success, complications, and long-term patency were analyzed.

RESULTS

Technical success was achieved in 12 (85.7%) out of 14 procedures. The procedure failed in two patients due to the poor angle of approach in the axillary area and diffuse severe stenosis in the draining cephalic vein. In eight procedures, sharp needle recanalization was performed under ultrasound guidance, while the other six procedures were performed under fluoroscopic guidance. Chiba and Colapinto needles were used in five and nine procedures, respectively. The mean length of occlusion was 2.7 cm (range 1.8-4.2 cm). There was one case of mild complication, that is, mild contrast extravasation, which was treated by stent deployment. The post-intervention primary patency rates at 6 months, 1 year, and 2 years were 81.8%, 36.4%, and 18.2%, respectively.

CONCLUSION

The results of this limited series suggest that the sharp needle recanalization technique is a simple and effective method for the treatment of peripheral non-thrombotic AVF occlusion.

Efficacy and Safety of Paclitaxel-Coated Balloon Angioplasty for Dysfunctional Arteriovenous Fistulas: A Multicenter Randomized Controlled Trial

RATIONALE & OBJECTIVE

Previous studies have illustrated the potential superiority of drug-coated balloons (DCBs) in maintaining patency after initial angioplasty for arteriovenous fistula (AVF) dysfunction due to stenosis. Our trial evaluated the efficacy and safety of DCBs for preventing fistula restenosis in Chinese hemodialysis patients.

STUDY DESIGN

Multicenter, prospective, randomized, open-label, blinded end point, controlled trial.

SETTINGS & PARTICIPANTS

A total of 161 hemodialysis patients with fistula dysfunction from 10 centers in China.

INTERVENTION

Participants were randomized 1:1 to treatment with initial dilation followed by DCB angioplasty or conventional high-pressure balloon (HPB) angioplasty.

OUTCOMES

The primary end point was target lesion primary patency defined as the target lesion intervention-free survival in conjunction with an ultrasonography-measured peak systolic velocity ratio (PSVR) ≤2.0 at 6 months. The secondary end points included 1) device, technical, clinical, and procedural success; 2) major adverse events; 3) degree of target lesion stenosis at 6 months; and 4) clinically driven target lesion and target shunt revascularization within 12 months.

RESULTS

The percentage with target lesion primary patency as defined by a PSVR ≤2.0 was higher in the DCB group than in the control group (65% vs 37%, respectively; rate difference, 28% [95% CI, 13%-43%]; P <0.001) at 6 months. The target lesion and target shunt intervention-free survival of the DCB group were not superior to those of the control group at 6 months (P = 0.3 and P = 0.2, respectively) but were superior at 12 months (target lesion intervention-free survival: 73% for DCB vs 58% for control [P = 0.04]; target shunt intervention-free survival: 73% for DCB vs 57% for control [P = 0.04]). The average degree of target lesion stenoses at 6 months was not significantly different between the 2 groups (44% ± 16% for DCB vs 49% ± 18% for control; P = 0.09). There were no significant differences in major adverse events or in device, technical, clinical, or procedural success rates between the groups.

LIMITATIONS

Small sample size; short follow-up period; procedural differences between the 2 groups such as unequal inflation times and balloon lengths.

CONCLUSIONS

Compared to conventional HPB angioplasty, DCB treatment achieved superior primary patency defined using PSVR measured at 6 months and superior intervention-free survival of both the target lesion and the target shunt at 12 months without evidence of greater adverse events.

FUNDING

Funded by ZhuHai Cardionovum Medical Device Co., Ltd.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT02962141.

Network meta-analysis of trials comparing first line endovascular treatments for arteriovenous fistula stenosis

OBJECTIVE

We investigated the comparative effectiveness of different endovascular treatments for patients with failing autogenous arteriovenous fistulas (AVFs) with outflow vein stenosis.

METHODS

The Medline (via PubMed) and SCOPUS databases were searched. We performed a systematic review and network meta-analysis of randomized controlled trials that had investigated the effectiveness of plain balloon angioplasty (PBA), cutting balloon angioplasty, and drug-coated balloon angioplasty (DCBA) to treat vein stenoses in autogenous AVFs. Studies of central vein stenosis were excluded. The main outcome measures were the failure rates at 6 months and 1 year after treatment.

RESULTS

Eleven randomized controlled trials were included, with 814 patients, 395 of whom had undergone PBA. The network meta-analysis showed that DCBA at 6 months was significantly more effective than PBA (odds ratio, 0.39; 95% confidence interval, 0.18-0.81) and ranked as the best treatment option, although the difference was not statistically significant compared with cutting balloon angioplasty (odds ratio, 0.65; 95% confidence interval, 0.20-2.12). The differences among the three treatments at 1 year were not statistically significant. Additional conventional pairwise meta-analyses did not find significant differences at 1 year.

CONCLUSIONS

In failing AVFs with outflow stenosis, DCBA was significantly superior to PBA, with improved 6-month failure rates. However the effectiveness of DCBA in the long term deserves further investigation.

Use of the Viabahn covered stent for the treatment of venous rupture during interventions of dysfunctional or thrombosed hemodialysis vascular access

BACKGROUND

Angioplasty-related vessel rupture is a common complication of interventions. The effect of covered stents to treat venous rupture has been evaluated in smaller series, but should be further evaluated.

OBJECTIVE

To report the immediate outcomes and patency rates of a covered stent to rescue angioplasty-related venous rupture of hemodialysis vascular access.

METHODS

From January 2013 to December 2018, 113 procedures complicated with vessel ruptures were retrospectively analyzed from a prospectively collected database of 8146 hemodialysis access interventions. The strategies to salvage vessel ruptures were based on the discretion of the treating physicians. Follow-up outcomes were obtained via review of the angiographic images, procedural notes, and medical and dialysis records within 12 months after the index procedures.

RESULTS

A total of 52 vessel ruptures (21 fistulas, 31 grafts) salvaged by using Viabahn covered stents were enrolled. Vessel ruptures developed in 28 (53.8%) thrombectomy procedures. Device success was achieved in all procedures (100%) and clinical success was achieved in 50 (96.2%). The primary patency of the stent area was 66.0% at 6 months and 50.0% at 12 months. The primary patency of the entire access circuit was 27.4% at 6 months and 16.0% at 12 months. The most common cause of access circuit primary patency loss was thrombotic occlusion for graft accesses and restenosis at stent area for native accesses. Eleven vascular accesses were abandoned within 12 months after vessel ruptures, and the secondary patency rate of the entire access circuit was 78.0% at 12 months.

CONCLUSIONS

Treatment of angioplasty-induced vessel rupture of hemodialysis vascular accesses by using Viabahn covered stents has good immediate outcomes and patency results at the stent area. Nonetheless, the patency rate of entire access circuit was still below the threshold recommended by guidelines.

A randomized feasibility study of the effect of ascorbic acid on post-angioplasty restenosis of hemodialysis vascular access (NCT03524846)

Restenosis remains a significant problem after angioplasty of hemodialysis vascular access. Both experimental and clinical studies have shown a protective effect of antioxidants against post-angioplasty restenosis. A prospective, randomized, feasibility study was conducted to investigate the effect of ascorbic acid to prevent restenosis. Ninety-three hemodialysis patients were randomized into three groups after angioplasty: placebo (n = 31), 300 mg ascorbic acid (n = 31), and 600 mg ascorbic acid (n = 31), treated intravenously 3 times per week for 3 months. Eighty-nine completed the clinical follow-up, and 81 had angiographic follow-up. In the angiographic follow-up, the mean (stand deviation) late loss of luminal diameter for the placebo, 300 mg, and 600 mg groups were 3.15 (1.68) mm, 2.52 (1.70) mm (P = 0.39 vs. placebo group), and 1.59 (1.67) mm (P = 0.006, vs. placebo group), with corresponding angiographic binary restenosis of 79%, 67% (P = 0.38 vs. placebo group), and 54% (P = 0.08 vs. placebo group). The post-interventional primary patency rates at 3 months were 47%, 55% (P = 0.59 vs. placebo group), and 70% (P = 0.18 vs. placebo group) for placebo, 300 mg, and 600 mg groups. Our results demonstrated that intravenous 600 mg ascorbic acid was a feasible therapy and might attenuate restenosis after angioplasty; however, its effect on post-interventional primary patency was modest.

Temporal distribution and biological determinants of thrombotic events after interventions for dialysis vascular access

Endovascular therapy is the principal therapy for haemodialysis vascular access dysfunction. Nonetheless, the incidence and determinants of post-intervention thrombotic events are unclear. This prospective cohort study evaluated the incidence and timing of thrombotic events after endovascular therapy and analysed the clinical, angiographic, and biological determinants of thrombosis. Of the 236 patients enrolled, 91 experienced post-intervention thrombotic events within 1 year. The 1-year thrombosis-free patency was 28% for thrombosed accesses, 53% for non-thrombosed grafts, and 78% for non-thrombosed fistulas. Forty-one of the 91 thrombotic events (45%) occurred within 3 months post-intervention. In the univariate analysis, early thrombosis was associated with longer haemodialysis duration (hazard ratio [HR], 1.01; 95% confidence interval [CI], 1.01–1.02), graft access (HR, 7.69; 95% CI, 3.33–20.0), multiple stenoses (HR, 2.69; 95% CI, 1.36–5.37), and high indoxyl sulphate (IS) levels (HR, 1.55; 95% CI, 1.32–1.82). Late thrombosis was associated with diabetes (HR, 1.89; 95% CI, 1.01–3.57), cardiovascular disease (HR, 2.38; 95% CI, 1.27–4.54), and endothelial progenitor cell counts (HR, 0.97; 95% CI, 0.93–0.99). After multivariate adjustment, high IS was the major predisposing factor for early post-intervention thrombosis (HR, 1.41; 95% CI, 1.18–1.69). Our findings suggest that measures to decrease IS could target the most critical period of thrombosis.

Clinical Evaluation of the Cook Advance Enforcer 35 Focal-Force PTA Balloon Catheter for Treatment of Hemodialysis Fistula Stenoses: A Feasibility Study

PURPOSE

A prospective, single-center, single-arm feasibility study evaluated procedural and short-term performance of the Advance Enforcer 35 focal-force percutaneous transluminal angioplasty (PTA) balloon catheter in treating stenoses of mature native arteriovenous (AV) hemodialysis access circuits.

MATERIALS AND METHODS

Twenty-eight patients undergoing treatment for stenosis of a mature native AV hemodialysis access circuit were enrolled at a single institution. Angiographic assessments of the study lesion were required at baseline and after the procedure. Adjunctive procedures for significant residual stenosis were permitted, and patients had clinical and imaging follow-up for as long as 6 months.

RESULTS

Treatment with the study balloon was effective in reducing the average percent diameter stenosis of the treated lesion from 66.3% (range, 43.8%-93.3%) before the procedure to 23.7% (range, -6.7% to 51.4%) after the procedure. The average inflation pressure required was 12.3 atm. Only 1 patient required an adjunctive procedure, and all patients could resume normal dialysis following the study procedure. At 3 months, 62.0% of study lesions remained patent, and the 6-month patency rate was 25.1%. Two adverse events associated with the study procedure were reported: access-site hematoma and forearm pain (3.6% each).

CONCLUSIONS

The results demonstrate safety of the study balloon in treating AV access stenosis. Nominal-diameter angioplasty was achieved at relatively low pressure in most study patients without the use of adjunctive procedures, and resumption of normal dialysis was achieved for all patients.

Recent developments in endovascular interventions to sustain vascular access patency in haemodialysis patients

There is amassed evidence regarding the use of endovascular procedures for the treatment of vascular access stenosis and thrombosis. A review was conducted based on available randomized trials, cohort studies and retrospective analyses published after 2000 on endovascular treatment of dysfunctional and thrombosed vascular access, with an aim to illustrate the available device and procedural options. The use of paclitaxel-coated balloons, cutting balloons and covered stents is described in the field of vascular access stenosis. The broad spectrum of available devices and endovascular declotting procedures ranging from thrombolysis to thrombectomy is also discussed. Overall, in this review we demonstrate the increasing role of endovascular procedures in vascular access treatment and the improved patency outcomes provided by the implementation of novel endovascular devices. Moreover, the improvement of post-intervention primary patency rates after endovascular declotting procedures and the shift to more thrombectomy-dependent procedures over time is also highlighted. In conclusion, endovascular treatment of dialysis access stenosis and thrombosis has an established role, owing to the implementation of sophisticated devices, allowing, when needed, the simultaneous treatment of thrombosis and the underlying stenosis.

Spanish Clinical Guidelines on Vascular Access for Haemodialysis

Vascular access for haemodialysis is key in renal patients both due to its associated morbidity and mortality and due to its impact on quality of life. The process, from the creation and maintenance of vascular access to the treatment of its complications, represents a challenge when it comes to decision-making, due to the complexity of the existing disease and the diversity of the specialities involved. With a view to finding a common approach, the Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology [S.E.N.], vascular surgery [SEACV], vascular and interventional radiology [SERAM-SERVEI], infectious diseases [SEIMC] and nephrology nursing [SEDEN]), along with the methodological support of the Cochrane Center, has updated the Guidelines on Vascular Access for Haemodialysis, published in 2005. These guidelines maintain a similar structure, in that they review the evidence without compromising the educational aspects. However, on one hand, they provide an update to methodology development following the guidelines of the GRADE system in order to translate this systematic review of evidence into recommendations that facilitate decision-making in routine clinical practice, and, on the other hand, the guidelines establish quality indicators which make it possible to monitor the quality of healthcare.

Thrombophilia Associated with Early Post-angioplasty Thrombosis of Dialysis Vascular Access

AIM

Percutaneous transluminal angioplasty (PTA) is widely used as the primary treatment for dialysis vascular access dysfunction. Nonetheless, many patients develop early occlusion after angioplasty. Thus, we investigated the role of thrombophilia in access occlusion within 30 days of angioplasty.

MATERIALS AND METHODS

This case-control study included patients who underwent PTA for dialysis vascular access dysfunction. Patients who experienced occlusion within 30 days of angioplasty were included in the case group and those without occlusion for at least 30 days after angioplasty were included in the control group. All patients were tested for protein C, protein S, antithrombin III, lupus anticoagulant, and anticardiolipin antibodies.

RESULTS

From February to October 2015, 462 patients underwent PTA for dialysis vascular access dysfunction. Forty-one patients (8.9%) had early occlusion within 30 days of angioplasty. The case group had more graft accesses (73 vs. 31%, P < 0.001) and thrombotic occlusions (67 vs. 15%, P < 0.001). A higher incidence of protein C (10 vs. 2%), protein S (15 vs. 5%), and antithrombin III (10 vs. 2%) deficiency and elevated anticardiolipin antibody (22 vs. 10%) levels were observed in the case group. Overall, 26 patients (63%) in the case group had at least one thrombophilic factor, compared with 15 patients (37%) in the control group (unadjusted odds ratio [OR], 3.004; 95% confidence interval [CI], 1.223-7.380; P = 0.027). After adjustment for confounding factors, the association between thrombophilic factors and early occlusion remained (adjusted OR, 3.806; 95% CI, 1.018-14.220; P = 0.047).

CONCLUSION

Thrombophilia is associated with early occlusion after angioplasty for hemodialysis vascular access.

Definitions and End Points for Interventional Studies for Arteriovenous Dialysis Access

This paper is part of the Clinical Trial Endpoints for Dialysis Vascular Access Project of the American Society of Nephrology Kidney Health Initiative. The purpose of this project is to promote research in vascular access by clarifying trial end points which would be best suited to inform decisions in those situations in which supportive clinical data are required. The focus of a portion of the project is directed toward arteriovenous access. There is a potential for interventional studies to be directed toward any of the events that may be associated with an arteriovenous access' evolution throughout its life cycle, which has been divided into five distinct phases. Each one of these has the potential for relatively unique problems. The first three of these correspond to three distinct stages of arteriovenous access development, each one of which has been characterized by objective direct and/or indirect criteria. These are characterized as: stage 1-patent arteriovenous access, stage 2-physiologically mature arteriovenous access, and stage 3-clinically functional arteriovenous access. Once the requirements of a stage 3-clinically functional arteriovenous access have been met, the fourth phase of its life cycle begins. This is the phase of sustained clinical use from which the arteriovenous access may move back and forth between it and the fifth phase, dysfunction. From this phase of its life cycle, the arteriovenous access requires a maintenance procedure to preserve or restore sustained clinical use. Using these definitions, clinical trial end points appropriate to the various phases that characterize the evolution of the arteriovenous access life cycle have been identified. It is anticipated that by using these definitions and potential end points, clinical trials can be designed that more closely correlate with the goals of the intervention and provide appropriate supportive data for clinical, regulatory, and coverage decisions.

Timely thrombectomy can improve patency of hemodialysis arteriovenous fistulas

OBJECTIVE

The urgency with which salvage of thrombosed vascular accesses for dialysis should be attempted remains unknown. We examined the effect of a timely thrombectomy approach on vascular access outcomes for dialysis.

METHODS

A before-and-after study was conducted with patients on hemodialysis who had undergone endovascular thrombectomy. A timely thrombectomy initiative (ie, salvage within 24 hours of thrombosis diagnosis) was started in July 2015 at our institution. Data about thrombectomy procedures, performed within 1 year before and after the initiative was introduced, were abstracted from an electronic database. Immediate outcomes and patency outcomes were compared between the preinitiative (control) and postinitiative (intervention) groups.

RESULTS

During the study period, 329 patients were enrolled, including 165 cases before and 164 cases after the initiative. The intervention group had more thrombectomy procedures performed within 24 hours (93% vs 55%; P < .01) and within 48 hours (97% vs 79%; P < .01) than the control group. No between-group differences in procedural success or clinical success rates were found. At 3 months, the intervention group had a higher postintervention primary patency rate than the control group, although this did not reach statistical significance (58% vs 48%; P = .06). After stratification into native or graft accesses, the patency benefit was observed in the native access group (68% vs 50%; P = .03) but not in the graft access group (50% vs 46%; P = .65). After adjusting for potential confounders, timely thrombectomy remained an independent predictor of postintervention primary patency (hazard ratio, 0.449; 95% confidence interval, 0.224-0.900; P = .02) for native dialysis accesses.

CONCLUSIONS

Our results suggest that a timely thrombectomy approach, in which salvage is attempted within 24 hours of thrombosis diagnosis, improves postintervention primary patency of native but not graft accesses for dialysis.

Monocyte Chemoattractant Protein-1 Levels and Postangioplasty Restenosis of Arteriovenous Fistulas

BACKGROUND AND OBJECTIVES

Inflammation is relevant in restenosis of atherosclerotic vascular diseases, but its role in dialysis arteriovenous fistula remains unknown. In animal studies, upregulation of monocyte chemoattractant protein-1 has been shown in venous segments of arteriovenous fistula. We, therefore, aimed to investigate serial changes in circulating monocyte chemoattractant protein-1 after percutaneous transluminal angioplasty of dialysis arteriovenous fistulas and its relation to restenosis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Fifty-nine patients with dysfunctional arteriovenous fistulas that were referred for percutaneous transluminal angioplasty were enrolled prospectively between January of 2010 and July of 2012. Three of them were excluded due to percutaneous transluminal angioplasty failure or acute infection. Blood was sampled from arteriovenous fistulas at baseline, 2 days, 2 weeks, and 3 months after percutaneous transluminal angioplasty. Clinical follow-up was continued monthly for 3 months. Angiographic follow-up was arranged at the end of 3 months. Seventeen patients without significant stenosis were enrolled as the control group.

RESULTS

Fifty-six patients completed clinical follow-up. Significant increases in monocyte chemoattractant protein-1 were observed at 2 days and 2 weeks (both P<0.001) after percutaneous transluminal angioplasty. Twenty-three (41%) patients had symptomatic restenosis. The restenosis group had a higher percentage change in monocyte chemoattractant protein-1 levels at 2 days (median =47%; interquartile range, 27%-65% versus median =17%; interquartile range, 10%-25%; P<0.001) after percutaneous transluminal angioplasty compared with the patent group. Fifty-two patients completed angiographic follow-up. A positive correlation between relative luminal loss and monocyte chemoattractant protein-1 increase at 2 days after percutaneous transluminal angioplasty was found (r=0.53; P<0.001). In multivariate analysis, postangioplasty monocyte chemoattractant protein-1 increase at 2 days was an independent predictor of restenosis. Using receiver operator characteristic analysis, >25% postangioplasty increase of monocyte chemoattractant protein-1 was significantly associated with restenosis after percutaneous transluminal angioplasty (hazard ratio, 5.36; 95% confidence interval, 1.81 to 15.8).

CONCLUSIONS

Circulating monocyte chemoattractant protein-1 levels were elevated 2 days and 2 weeks after percutaneous transluminal angioplasty. Early postangioplasty increase of monocyte chemoattractant protein-1 level was associated with restenosis of arteriovenous fistulas.

Cutting balloons, covered stents and paclitaxel-coated balloons for the treatment of dysfunctional dialysis access

Percutaneous transcatheter balloon angioplasty has evolved to the current mainstay treatment for salvage of dysfunctional dialysis access. Nonetheless, it is frequently associated with recurrent vessel restenosis and the need for multiple repeat treatments in order to maintain hemodynamic patency. Cutting-balloons, covered stents or stent-grafts, and paclitaxel-coated balloons have been extensively tested and investigated with the aim to improve immediate anatomical and long-term clinical results. Areas covered: In the present overview, we discuss the background and appraise relevant medical literature on the aforementioned technologies and provide a more in-depth synthesis of the results of different clinical studies for each device category. We will also discuss the limitations in the mode of action of each group of devices and envision what the future holds for the challenging field of dialysis access interventions. Expert commentary: We propose a good practice algorithm for the treatment of thrombosed or dysfunctional dialysis access.

Future research directions to improve fistula maturation and reduce access failure

With the increasing prevalence of end-stage renal disease, there is a growing need for hemodialysis. Arteriovenous fistulae (AVF) are the preferred type of vascular access for hemodialysis, but maturation and failure continue to present significant barriers to successful fistula use. AVF maturation integrates outward remodeling with vessel wall thickening in response to drastic hemodynamic changes in the setting of uremia, systemic inflammation, oxidative stress, and pre-existent vascular pathology. AVF can fail due to both failure to mature adequately to support hemodialysis and development of neointimal hyperplasia that narrows the AVF lumen, typically near the fistula anastomosis. Failure due to neointimal hyperplasia involves vascular cell activation and migration and extracellular matrix remodeling with complex interactions of growth factors, adhesion molecules, inflammatory mediators, and chemokines, all of which result in maladaptive remodeling. Different strategies have been proposed to prevent and treat AVF failure based on current understanding of the modes and pathology of access failure; these approaches range from appropriate patient selection and use of alternative surgical strategies for fistula creation, to the use of novel interventional techniques or drugs to treat failing fistulae. Effective treatments to prevent or treat AVF failure require a multidisciplinary approach involving nephrologists, vascular surgeons, and interventional radiologists, careful patient selection, and the use of tailored systemic or localized interventions to improve patient-specific outcomes. This review provides contemporary information on the underlying mechanisms of AVF maturation and failure and discusses the broad spectrum of options that can be tailored for specific therapy.

Drug-coated balloon angioplasty for dialysis access fistula stenosis

Maintaining vascular access patency represents a tremendous challenge in hemodialysis patients. Although "native" arteriovenous fistula (AVF) is currently recommended as primary vascular access, neointimal hyperplasia stenoses frequently develop, with a risk for AVF thrombosis and vascular access loss. For years, first-line treatment of AVFs stenoses has been percutaneous transluminal angioplasty, generally with high-pressure or cutting uncoated balloons. However, restenosis and reintervention rates remain incredibly high and occur, according to recent studies, in up to 60% and 70% of patients at 6 and 12 months, respectively. Drug-coated balloons delivering paclitaxel at the angioplasty site have proved their superiority in the treatment of coronary and peripheral arterial stenoses. Paclitaxel reduces neointimal hyperplasia and drug-coated balloons, therefore, it represents an attractive option for AVF stenoses. Because data are scarce, the aim of this paper was to review the concepts and current results of drug-coated balloons in AVF stenosis management.

Serum Indoxyl Sulfate Associates with Postangioplasty Thrombosis of Dialysis Grafts

Hemodialysis vascular accesses are prone to recurrent stenosis and thrombosis after endovascular interventions.In vitro data suggest that indoxyl sulfate, a protein-bound uremic toxin, may induce vascular dysfunction and thrombosis. However, there is no clinical evidence regarding the role of indoxyl sulfate in hemodialysis vascular access. From January 2010 to June 2013, we prospectively enrolled patients undergoing angioplasty for dialysis access dysfunction. Patients were stratified into tertiles by baseline serum indoxyl sulfate levels. Study participants received clinical follow-up at 6-month intervals until June 2014. Primary end points were restenosis, thrombosis, and failure of vascular access. Median follow-up duration was 32 months. Of the 306 patients enrolled, 262 (86%) had symptomatic restenosis, 153 (50%) had access thrombosis, and 25 (8%) had access failure. In patients with graft access, free indoxyl sulfate tertiles showed a negative association with thrombosis-free patency (thrombosis-free patency rates of 54%, 38%, and 26% for low, middle, and high tertiles, respectively;P=0.001). Patients with graft thrombosis had higher free and total indoxyl sulfate levels. Using multivariate Cox regression analysis, graft thrombosis was independently predicted by absolute levels of free indoxyl sulfate (hazard ratio=1.14;P=0.01) and free indoxyl sulfate tertiles (high versus low, hazard ratio=2.41;P=0.001). Results of this study provide translational evidence that serum indoxyl sulfate is a novel risk factor for dialysis graft thrombosis after endovascular interventions.

The Eternal Tale of Dialysis Access Vessels and Restenosis: Are Drug-Eluting Balloons the Solution?

In dialysis access fistulas and grafts, percutaneous transluminal angioplasty (PTA) is frequently followed by restenosis development, which results in repeated periodical re-interventions. The technique of drug-eluting balloon (DEB) angioplasty has shown promising results in the treatment of femoropopliteal arteriosclerotic lesions. In contrast to arteriosclerotic arteries, dialysis access vessels host unfavorable hemodynamics due to the direct conduction of high-pressure fluid into a low-pressure system. Hence, the beneficial effect of DEB angioplasty may be limited in this system. However, a first prospective randomized trial on 40 patients with arteriovenous fistula or graft stenoses exhibited a significantly higher 6-month primary patency of the treated lesions after DEB angioplasty than after uncoated balloon angioplasty. Despite such a positive reference, general recommendations regarding the value of DEBs in dialysis access vessels cannot be considered as serious unless large randomized controlled trials have been performed.

Hybrid Simultaneous Treatment of Thrombosed Prosthetic Grafts for Hemodialysis

Purpose

The aim of the study was to evaluate our experience in the hybrid simultaneous treatment (open and endovascular) of acute thrombosis of prosthetic grafts for hemodialysis.

Methods

Between January 2011 and June 2013, 23 patients with acute thrombosis of a prosthetic graft for hemodialysis were urgently treated with a hybrid simultaneous treatment in order to obtain a prompt restoration of the flow. A new puncture of the graft was scheduled after 24 hours.

Results

Intraoperative technical success was 100% with a completion angiography showing the restored patency of the graft. As adjunctive procedures, in 6 patients (26.1%) locoregional thrombolysis was necessary and in all cases further endovascular manoeuvres (angioplasty/stenting) were immediately performed to solve a significant stenosis of the venous anastomosis/first tract of the vein. At 24 hours when the first puncture was done, three grafts were occluded resulting in a primary patency of 87%. During the follow-up (mean duration 5.6 months) four reocclusions occurred. In-stent restenosis occurred in all patients undergone stenting. At 1 year the rates of primary patency, primary assisted patency and secondary patency were 58.7%, 78.3% and 87%, respectively.

Conclusions

In our series the combined simultaneous hybrid approach in urgency maximizes the use of different available techniques, which appeared to improve overall success rate to save a thrombosed graft for hemodialysis. The great difference showed between primary and primary assisted patency demonstrates the necessity of a close follow-up.

Novel therapies for hemodialysis vascular access dysfunction: myth or reality?

Hemodialysis vascular access dysfunction is a major source of morbidity for patients with ESRD. Development of effective approaches to prevent and treat vascular access failure requires an understanding of the underlying mechanisms, suitable models for preclinical testing, systems for targeted delivery of interventions to maximize efficacy and minimize toxicity, and rigorous clinical trials that use appropriate outcome measures. This article reviews the substantial progress and ongoing challenges in developing novel treatments for arteriovenous vascular access failure and focuses on localized rather than systemic interventions.

Catheter Interventions for Pulmonary Artery Stenosis: Matching the Intervention with the Pathology

Pulmonary artery (PA) stenosis represents a heterogeneous defect with a wide morphology and etiology. Interventions to treat PA stenosis should be based on the location, severity, and cause of stenosis as well as the size of the patient at presentation. Specialized dilation balloons, stents, and delivery techniques have been developed to treat a variety of PA stenoses in small infants through adulthood. Early and intermediate results of angioplasty and stenting are superior to surgical results, while long-term data on angioplasty and stenting are becoming available for these proven safe and effective techniques.

Radial artery approach to salvage nonmaturing radiocephalic arteriovenous fistulas

PURPOSE

To evaluate the usefulness of an approach through the radial artery distal to the arteriovenous anastomosis for salvaging nonmaturing radiocephalic arteriovenous fistulas.

METHODS

Procedures that fulfilled the following criteria were retrospectively reviewed: (1) autogenous radiocephalic fistulas, (2) fistulas less than 3 months old, (3) distal radial artery approach for salvage. From 2005 to 2011, a total of 51 patients fulfilling the above criteria were enrolled. Outcome variables were obtained from angiographic, clinical and hemodialysis records, including the success, complication, and primary and secondary patency rates.

RESULTS

The overall anatomical and clinical success rates for the distal radial artery approach were 96 and 94%, respectively. The average procedure time was 36 ± 19 min. Six patients (12%) experienced minor complications as a result of extravasations. No arterial complication or puncture site complication was noted. The postinterventional 6-month primary patency rate was 51%, and the 6-month secondary patency rate was 90%. When the patients were divided into a stenosed group (20 patients) and an occluded group (31 patients), there were no differences in the success rate, complication rate, or primary and secondary patency rates.

CONCLUSION

An approach through the radial artery distal to the arteriovenous anastomosis is an effective and safe alternative for the salvage of nonmaturing radiocephalic arteriovenous fistulas, even for occluded fistulas.

Efficacy of a modified pharmacomechanical thrombolysis technique for endovascular treatment of thrombosed prosthetic arteriovenous grafts

Objective

We applied a modified pharmacomechanical thrombolysis (PMT) technique to endovascular treatment of thrombosed arteriovenous (AV) grafts without the use of any mechanical thrombectomy devices. The aim of this study was to evaluate the efficacy of the PMT technique in the treatment of thrombosed AV grafts by analyzing the long-term patency.

Materials and Methods

Eighty-two patients with thrombosed AV grafts were treated with the PMT technique. AV graft surveillance to detect failing/failed access was followed by endovascular treatment.

Results

The technical and clinical success rates were 95% and 95%, respectively. The total number of thrombolysis sessions was 279. A post-intervention primary patency rate was 45% and 22% at 12 and 24 months, respectively. The secondary patency rate was 96% and 91% at 12 and 24 months, respectively. No major complications were noticed.

Conclusion

The modified PMT technique is effective in endovascular treatment of thrombosed AV grafts.

Optimizing arteriovenous fistula maturation

Autogenous arteriovenous fistulas are the preferred vascular access in patients undergoing hemodialysis. Increasing fistula prevalence depends on increasing fistula placement, improving the maturation of fistula that fail to mature and enhancing the long-term patency of mature fistula. Percutaneous methods for optimizing arteriovenous fistula maturation will be reviewed.