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

The efficacy of percutaneous transluminal angioplasty and arteriovenous fistula reconstruction for immature arteriovenous fistula

BACKGROUND

To access the efficacy of percutaneous transluminal angioplasty and arteriovenous fistula reconstruction for immature arteriovenous fistula, compare the long-term patency and post-operative complications between them.

MATERIALS AND METHODS

The medical records and Hemodialysis record sheets from 44 patients between May 2020 and January 2022 who underwent percutaneous transluminal angioplasty or arteriovenous fistula reconstruction treatment for immature autogenous arteriovenous fistula (AVF) were retrospectively reviewed. The patients were divided into two groups according to the type of surgery they received, including 25 patients in the PTA group and 19 patients in the AVF reconstruction group. Clinical outcomes were included, such as the primary and secondary patency rates following the procedure, maturation time, peak systolic velocity (PSV) of brachial artery, maximum pump-controlled blood flow at initial dialysis, and post-operative complications rates in the two groups.

RESULTS

Technical and clinical success was achieved in 100% of the 44 cases. For patients who underwent percutaneous transluminal angioplasty, the primary patency rate at 3, 6, and 9 months was 84.0%, 68.0%, 60.0%, and the secondary patency rate was 92.0%, 84.0%, 80.0%, respectively. And for patients who underwent arteriovenous fistula reconstruction, the primary patency rate at 3, 6, and 9 months was 89.5%, 73.7%, 68.4%, and the secondary patency rate was 100.0%, 94.7%, 94.7%, respectively. There were no significant differences between the two groups in terms of patency rates (p > .050). In patients whose maturation was successful, the average maturation time of fistula after the PTA procedure was 19.36 ± 13.94 days, and 58.63 ± 18.95 days for the reconstruction procedure (p < .010). The PSV of brachial artery before and after the procedure was 87.64 ± 23.87 cm/s and 153.20 ± 21.69 cm/s in PTA group, for reconstruction group, the number was 86.26 ± 20.59 cm/s and 151.26 ± 29.94 cm/s, respectively. No statistically significant differences (p > .050). The maximum pump-controlled blood flow at initial dialysis was 232.60 ± 16.72 ml/min in PTA group, which was significantly higher than 197.11 ± 10.45 ml/min in reconstruction group (p < .010). Subcutaneous hematoma, restenosis, thrombus formation, and pseudoaneurysm were major complications in PTA group. Restenosis, thrombus formation, and pseudoaneurysm were major complications in reconstruction group, with no statistically significant differences between the two groups (p > .050).

CONCLUSION

When immature AVFs require reconstruction surgery, the patency outcomes are comparable to AVFs that undergo successful management by PTA. While, when AVFs are successfully managed by PTA, they have significantly less maturation times and higher maximum pump-controlled blood flow rates at initial dialysis AVF use.

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.

Procedure and Clinical Success of Drug-Coated Balloon Fistuloplasty of the Drainage Vein in Dysfunctional Native Arteriovenous Fistulas

Purpose

Native arteriovenous fistulas (AVFs) are the most effective vascular access (VA) for haemodialysis. We aimed to evaluate the results of balloon angioplasty (fistuloplasty) from drainage vein performed for the treatment of AVF dysfunction in haemodialysis patients and examine potential patient and AVF-associated factors that might affect such results.

Methods

This is a nonrandomized, retrospective, and single-centred study. A total of 105 balloon fistuloplasties were performed for dysfunctional AVFs of 82 haemodialysis patients. Patients were treated with a drug-coated balloon according to standard procedures. Evaluations were performed by physical examinations and if needed by color Doppler imaging in every 6 months. The primary endpoint was patency by balloon fistuloplasty. Patency was evaluated clinically by detecting the thrill in AVF and by the adequacy of the dialysis. Multidimensional scaling (MDS) technique was used as a method for the statistical analysis.

Results

The success of the procedure after the first attempt was 85.3% with 70 patients. Patency in the 6th, 12th, 18th, and 24th months were 63 (76.8%), 60 (73.1%), 53 (64.6%), and 44 (54%), respectively. The procedure was considered successful when the thrill was detected in AVF and when dialysis was adequate. The statistical analysis by MDS revealed that patients' age was the most effective factor acting on the procedure success followed by the age of AVF. Other patient-associated and AVF-associated factors were not found as effective statistical evaluation.

Conclusions

Haemodialysis through native AVFs with restored functionality contributes positively to the life span and the quality of life of the patient. Probably, advanced age and high fistula age are unfavourable factors leading to the development of neointimal hyperplasia and venous stenosis. Balloon fistuloplasty of the draining vein is an effective and safe method regardless of patient age and the age of AVF.

Vasodilator agents improve hemodialysis vascular access patency: A population-based study from Korea

Vascular access (VA) failure is an important problem for patients undergoing hemodialysis, and maintaining VA patency is challenging. In this study, we used a nationwide database to investigate the effects of nitrate, as a vasodilator, on VA failure in hemodialysis patients.We investigated the Korean insurance claims data of hemodialysis patients who underwent angioplasty for VA failure between January 2012 and December 2017. The patients were divided into 2 groups: those not receiving vasodilator therapy (controls) and those receiving any vasodilator administration (vasodilator treatment, VDT). The primary endpoint was VA primary patency, defined as the time between arteriovenous dialysis access creation and the first percutaneous transluminal angioplasty (PTA).During the study period, a total of 6350 patients were recruited, 409 (6.4%) patients assigned to the VDT group and 5941 (93.6%) controls. PTA was performed in 998 patients (15.7%), including 8 in the VDT group and 990 controls. The VA site PTA rate was significantly lower in the VDT group (2.0%) than in the control group (16.7%, P < .001). In the subgroup analysis, the patency rates associated with the different vasodilators were similar (P = .736). All vasodilators, except molsidomine, improved the patency rate by approximately 20%.In this large national database study, vasodilator administration was associated with higher VA primary patency, compared with controls, in hemodialysis patients. VDT may have a beneficial effect on maintaining VA patency in patients undergoing hemodialysis.

Predictive value of neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio for primary patency of percutaneous transluminal angioplasty in hemodialysis arteriovenous fistula stenosis

OBJECTIVE

The aim of this study is to investigate the potential association of the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) with the primary patency of percutaneous transluminal angioplasty (PTA) in hemodialysis arteriovenous fistula (AVF) stenosis.

METHODS

This study conducted a retrospective review of patients with end-stage renal disease referred for hemodialysis AVF stenosis in one center. The study consisted of 114 patients with significant (significant stenosis was defined as a reduction in the caliber of the fistula vein of > 50% with respect to the non-aneurysmal venous segment). AVF stenosis patients were treated with PTA, with conventional balloon angioplasty. The NLR and PLR were calculated from the pre-interventional blood samples. The patients were classified into two groups: group A, primary patency < 12 months (n = 35) and group B, and primary patency ≥ 12 months (n = 79). Comparisons between the groups were performed using the Mann-Whitney U test. Kaplan-Meier analysis was performed to compare the factors, NLR and PLR, for association with primary patency AVFs. A receiver-operating characteristic curve analysis was performed to identify the sensitivity and specificity of the NLR and PLR cut-off values in the prediction of primary patency time.

RESULTS

There was no difference in gender; age; side of AVF; AVF type; comorbid diseases such as diabetes mellitus and hypertension; or blood parameters such as white cell count, erythrocytes, hemoglobin, neutrophils, lymphocytes, monocytes, eosinophils, basophils, C-reactive protein, NLR, or PLR between the two groups (p > 0.05). There was also no significant difference in the patency rate between the NLR < 4.13 and NLR ≥ 4.13 groups at 12 months (NLR cut-off point = 4.13, p = 0.273). There were statistically significant differences between the primary patency rates of the PLR < 187.86 and PLR ≥ 187.86 groups at 12 months (PLR cut-off point = 187.86, p = 0.023). The cut-off value for PLR for the determination of primary patency was 187.86, with a sensitivity of 57.0% and specificity of 34.4%.

CONCLUSION

An increased level of PLR may be a risk factor for the development of early AVF restenosis after successful PTA. However, more studies are needed to validate this finding.

Current role of ultrasound in hemodialysis access evaluation

Physical examination (PE) is considered the backbone before vascular access (VA) placement, during maturation period and for follow-up. However, it may be inadequate in identifying suitable vasculature, mainly in comorbid patients, or in detecting complications. This review highlights the advantages of ultrasound imaging to manage VA before placement, during maturation and follow-up. Furthermore, it analyses the future perspectives in evaluating early and late VA complications thank to the availability of multiparametric platforms, point of care of ultrasound, and portable/wireless systems. Technical improvements and low-cost systems should favor the widespread ultrasound-based VA surveillance programs. This significant turning point needs an adequate training of nephrologists and dialysis nurses and the standardization of exams, parameters, and procedures.

Efficacy and safety of secondary procedures for maintaining arteriovenous hemodialysis access patency: protocol for a systematic review and network meta-analysis

BACKGROUND

Arteriovenous (AV) hemodialysis access creation is recommended by international guidelines as the preferred method of hemodialysis access. However, most AV access sites will require revision to maintain patency. Although several treatment options exist, many have not been directly compared. We intend to compare the relative effectiveness of methods to maintain post-intervention primary patency of failing AV access.

METHODS

We will search EMBASE, MEDLINE, CENTRAL, trial registries, the grey literature, and ancestry and citation search from January 1977 to present, for randomized controlled trials comparing interventions to maintain primary patency of AV access. Two investigators will independently and blindly review all identified citations and extract data from included studies. The primary outcome is the primary patency 6 months after intervention. Secondary outcomes include immediate technical and functional success, reinterventions, patency, and mortality. Risk of bias, subgroup analyses, and sensitivity analyses are planned.

DISCUSSION

There are a number of treatment modalities for the management of failing AV access. However, most modalities have only been directly compared with plain old balloon angioplasty, and currently synthesized evidence focuses on individual pairwise comparisons. In light of the lack of comprehensively synthesized evidence and clinical equipoise, our study intends to synthesize currently available evidence though it is unclear which treatment modality is most effective.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO ID CRD42020148224.

Platelet to lymphocyte ratio predicting 6-month primary patency of drug-coated balloon for femoropopliteal disease

Background

Inflammatory reaction is an essential factor in the occurrence, development and prognosis of femoropopliteal disease (FPD). The ratio of platelets to lymphocytes (PLR) is a new indicator reflecting platelet aggregation and burden of systemic inflammation. Our study is to explore the association between preoperative platelet-to-lymphocyte ratio (pre-PLR) and 6-month primary patency (PP) after drug-coated balloon (DCB) in FPD.

Methods

There were 70 patients who underwent DCB for FPD contained in the study. According to 6-month PP, patients were divided into group A (PP ≥6 months, n = 54) and group B (PP < 6 months, n = 16). Logistic regression analysis was used to identify potential predictors for 6-month PP after DCB in FPD. A receiver operating characteristic (ROC) curve analysis was used to identify the cut-off value of pre-PLR to predict 6-month PP.

Results

Logistic regression analysis showed that pre-PLR (OR: 1.008, 95% CI: 1.001–1.016, P = 0.031) and lesion length > 10 cm (OR: 4.305, 95% CI: 1.061–17.465, P = 0.041) were independently predictive for 6-month PP. The cutoff value of pre-PLR obtained from the ROC analysis was 127.35 to determine 6-month PP with the area of 0.839. Subgroup analysis was conducted based on the cutoff value of pre-PLR. The 6-month PP in the group of pre-PLR < 127.35 was higher than that of pre-PLR ≥ 127.35 group (p < 0.001).

Conclusions

The present study indicated that an elevated pre-PLR was an effective additional indicator for predicting early PP in FPD after DCB.

Relationship of arteriovenous fistula stenosis and thrombosis with the platelet-lymphocyte ratio in hemodialysis patients

BACKGROUND

The platelet-lymphocyte ratio, which was reported to have a strong relationship with chronic inflammation and thrombosis, is a useful biomarker. The purpose of this study was to evaluate the relationship between the platelet-lymphocyte ratio, arteriovenous stenosis, and thrombosis in patients with chronic renal failure.

METHODS

Patients who were referred to our interventional radiology department due to arteriovenous fistula dysfunction from dialysis units between August 2015 and December 2018 were retrospectively reviewed. In the study, 95 patients with arteriovenous fistula access problems were included. Patients were divided into two groups: stenosis (n = 52) and thrombosis (n = 43). Thirty-six subjects with a patent left radiocephalic arteriovenous fistula proven by both color Doppler ultrasonography and clinically were added to the control group. Blood samples were obtained on the same day before the fistulography.

RESULTS

Platelet counts, lymphocyte counts, and platelet-lymphocyte ratio were found to be significantly different between the three groups. After the Bonferroni post hoc analysis, there was a significant difference between the stenosis and control group (p = 0.017), and the thrombosis and control group (p < 0.001) in terms of the platelet-lymphocyte ratio. No significant difference for any parameter was found between stenosis and thrombosis group.

CONCLUSION

High levels of the platelet-lymphocyte ratio may be a supportive finding of arteriovenous fistula stenosis and thrombosis and can be taken into consideration during hemodialysis-dependent patients' follow-up.

Drug-coated balloon angioplasty in failing haemodialysis arteriovenous shunts: 12-month outcomes in 200 patients from the Aperto Italian registry

Background:

We evaluated the safety and technical and clinical outcomes of angioplasty with a drug-coated balloon for the management of venous stenosis in arteriovenous grafts and arteriovenous fistulas in patients undergoing haemodialysis.

Methods:

Data were obtained from an ongoing prospective, non-randomised registry conducted at three Italian centres. Patients were treated with a drug-coated balloon according to standard procedures in each participating centre. Evaluation was by colour Doppler imaging every 3 months. The primary end-point was primary assisted patency. The secondary end-point was the rate of assisted patency of the vascular access.

Results:

A total of 311 angioplasty procedures in 200 patients, (60.4% male), were analysed. The procedural success rate was 100%. A total of 192 treatments of restenosis were necessary in 81 patients during average 21 ± 8 months follow-up. Kaplan–Meier estimates indicated that 88.0%, 64.2% and 40.6% of treated lesions were free from restenosis at 6, 12 and 24 months, respectively. Including multiple angioplasty, circuit patency rates were 99.2%, 92.5% and 84.8% at 6, 12 and 24 months, respectively. Primary patency rates were highest in shunts treated de novo with drug-coated balloons. Risk of restenosis was associated with circuit age (p = 0.017), history of treatment with conventional angioplasty (p < 0.001) and the kind of balloon used during pre-dilation (p = 0.001).

Conclusion:

The results suggest that favourable long-term patency rates can be achieved with the drug-coated balloon in a varied population of patients with failing haemodialysis arteriovenous shunts treated under conditions of actual care.

Maintaining lower limb access with the HeRO device

Central venous catheters (CVC) remain a mainstay of vascular access particularly for incident patients,
but lead to central vein stenosis (CVS) in up to 1 in 6 patents. This often leads to establishing dialysis access in the groin which in turn may result in development of CVS in the lower body, although this is poorly reported. The HeRO device was designed to address CVS by bypassing the stenosed veins with a nitinol-reinforced silicone tube into the right atrium, which acts as an outflow conduit attached to an arterial inflow. The efficacy and safety of the HeRO device in the upper limb is well established, but there is no data on its use in the lower limb. We describe 2 cases of HeRO in the lower limb, one primary and one secondary, which remain in use. Lower limb HeRO is feasible in the lower limb and can work well either as de novo (to achieve vascular access) or as a salvage procedure (to maintain vascular access).

Relationship Between Postoperative Neutrophil-Lymphocyte Ratio and 6-Month Primary Patency of Percutaneous Transluminal Angioplasty in Femoropopliteal disease With Drug-Coated and Uncoated Balloons

We investigated the relationship of postoperative neutrophil-lymphocyte ratio (NLR) with 6-month primary patency of percutaneous transluminal angioplasty (PTA) in femoropopliteal disease using drug-coated balloon (DCB) or uncoated balloon (UCB). This retrospective study included 106 patients who received DCB (n = 44) or UCB (n = 62). The postoperative NLR was lower in the DCB group than that in the UCB group (2.60 vs 3.23; P = .004), and 6-month primary patency rate was significantly higher in DCB group than that in the UCB group (77.3% vs 53.2%; P = .011). Multivariate logistic analysis showed that the postoperative NLR was an independent predictor of 6-month primary patency after PTA in patients with femoropopliteal disease (odds ratio: 1.589, 95% confidence interval: 1.078-2.343; P = .019). The cutoff value of postoperative NLR was 3.05 for prediction of 6-month primary patency, with a sensitivity of 64.1% and specificity of 65.7%. The 6-month primary patency rate in the NLR ≤3.05 group was higher than that in the NLR >3.05 group (75.9% vs 47.9%; P = .003). In conclusion, DCB may improve early primary patency by inhibiting inflammation. A higher postoperative NLR was associated with early restenosis.

Treatment of juxta-anastomotic stenoses for failing distal radiocephalic arteriovenous fistulas: Drug-coated balloons versus angioplasty

The aim of our study is to report the results of two types (type A, type B) paclitaxel drug-coated balloon compared with standard percutaneous transluminal angioplasty in the treatment of juxta-anastomotic stenoses of mature but failing distal radiocephalic hemodialysis arteriovenous fistulas. Two groups of 26 and 44 patients treated with two different drug-coated balloon are compared with a control group of 86 treated with standard percutaneous transluminal angioplasty. A color Doppler ultrasound was performed to evaluate stenosis and for treatment planning. We assess primary patency, defined as the absence of dysfunction of the arteriovenous fistulas, patent lesion or residual stenosis < 30% and no need for further reintervention of target lesion. Primary patency and secondary patency are evaluated after 12 months with color Doppler ultrasound for the whole arteriovenous fistulas, defined as absolute (absolute primary patency, absolute secondary patency) and target lesion. Postprocedural technical and clinical success was 100%. After 12 months, absolute primary patency is 81.8% for type A, 84.1% type B, and 54.7% for standard percutaneous transluminal angioplasty; target lesion primary patency is 92% type A, 86.4% type B, and 62.8% standard percutaneous transluminal angioplasty; absolute secondary patency is 95.4% type A, 95.5% type B, and 80.7% standard percutaneous transluminal angioplasty; target lesion secondary patency is 100% type A, 97.7% type B, and 80.7% standard percutaneous transluminal angioplasty. All the patients treated with drug-coated balloon (type A + type B) have an absolute primary patency of 83.3%, a target lesion primary patency of 87.9%, an absolute secondary patency of 95.5%, and a target lesion secondary patency of 98.4%. Our study confirms that the use of drug-coated balloon, indiscriminately among different brands, improves primary patency with statistically significant difference in comparison with standard percutaneous transluminal angioplasty and decreases reintervention of target lesion in juxta-anastomotic stenoses of failing distal arteriovenous fistulas maintaining the radiocephalic fistula as long as possible.

Paclitaxel-Coated Balloon Angioplasty for Early Restenosis of Central Veins in Hemodialysis Patients: A Single Center Initial Experience

Objective

To report the results of angioplasty with paclitaxel-coated balloons for the treatment of early restenosis of central veins in hemodialysis patients.

Materials and Methods

Sixteen patients (9 men and 7 women; mean age 65.8 ± 14.4 years; range, 40-82 years) with 16 episodes of early restenoses of central veins within 3 months (median patency duration 2.5 months) were enrolled from January 2014 to June 2015. Ten native central veins and 6 intra-stent central veins were treated with double paclitaxel-coated balloons (diameter 6-7 mm) plus a high pressure balloon (diameter 12-14 mm). The study outcomes included procedural success (< 30% residual stenosis) and primary patency of the treated lesion (< 50% angiographic stenosis without re-intervention).

Results

Procedural success was achieved in all 16 cases of central vein stenoses. The mean diameter of the central vein was 3.7 ± 2.4 mm before the procedure vs. 11.4 ± 1.8 mm after the initial procedure. There were no procedure-related complications. The mean diameters of the central veins at 6 months and 12 months were 7.8 ± 1.3 mm and 6.9 ± 2.7 mm, respectively. The primary patency rates at 6 months and 12 months were 93.8% and 31.2%, respectively. One patient had significant restenosis of the central vein at 3 months. The median primary patency period was 9 months for paclitaxel-coated balloons and 2.5 months for the last previous procedure with conventional balloons (p < 0.001).

Conclusion

In our limited study, paclitaxel-coated balloons seem to improve the patency rate in cases of early restenosis of central veins. However, a further randomized control trial is necessary.

A Review of Percutaneous Transluminal Angioplasty in Hemodialysis Fistula

The number of patients in dialysis increases every year. In this review, we will evaluate the role of percutaneous transluminal angioplasty (PTA) according to patency of arteriovenous fistula and grafts. The main indication of PΤΑ is stenosis > 50% or obstruction of the vascular lumen of an arteriovenous fistula and graft. It is usually performed under local anesthesia. The infection rate is as low as the number of complications. Fistula can be used in dialysis in the same day without the need for a central venous catheter. Primary patency is >50% in the first year while primary assisted patency is 80-90% in the same time period. Repeated PTA is as durable as the primary PTA. An early PTA carries a risk of new interventions. Cutting balloon can be used as a second-line method. Stents and covered stents are kept for the management of complications and central outflow venous stenosis. PTA is the treatment of choice for stenosis or obstruction of dialysis fistulas. Repeated PTA may be needed for better patency. Drug eluting balloon may become the future in PTA of dialysis fistula, but more trials are needed.

Stent graft placement versus angioplasty for hemodialysis access failure: a meta-analysis

BACKGROUND

Hemodialysis is a common treatment for end-stage renal disease, and maintenance of access patency remains a key issue. Angioplasty is recommended as the first choice for access stenosis, but it poses a risk of a high rate of restenosis. Stent graft placement can generate a high patency rate of dialysis access. This study aimed to compare the primary patency of the treatment area and access circuit between stent grafts and angioplasty in dialysis access failure.

MATERIALS AND METHODS

Three electronic databases, namely, PubMed, Cochrane Library of Systematic Reviews, and EMBASE, were searched from the database inception to September 2017 without language restriction. Randomized controlled trials comparing the primary patency of the treatment area and access circuit between stent graft and angioplasty were included. Two independent reviewers assessed the quality of the trials and extracted relevant data.

RESULTS

Four trials satisfied our inclusion criteria. Our pooled results suggested that stent graft placement was associated with significantly higher primary patency of treatment area (hazard ratio: 0.65, 95% confidence interval: 0.55-0.77, P < 0.0001, I² = 0) and access circuit (hazard ratio: 0.76, 95% confidence interval: 0.65-0.88, P = 0.0004, I² = 0) in hemodialysis access compared with those of standard angioplasty.

CONCLUSIONS

The patency of hemodialysis access may be higher after stent graft placement combined with standard angioplasty than after angioplasty alone.

A Single-Center Retrospective Analysis of the Efficacy of a New Balloon Catheter in Autogenous Arteriovenous Fistula Dysfunction Resistant to Conventional Balloon Angioplasty

PURPOSE

The purpose of the study was to present a new alternative balloon catheter option for autogenous arteriovenous fistula (AVF) dysfunction with a stiff constriction resistant to conventional balloon angioplasty.

METHODS

Our first series of 51 patients with autogenous AVF dysfunction who were simultaneously treated with VascuTrak™ balloon catheter, following failed conventional balloon therapy (failure was defined as residual stenosis of >30%), were retrospectively observed and analyzed. The indices that were used to evaluate the clinical efficacy of VascuTrak balloon catheter included the immediate technical success rate, residual stenosis, successful dilation times, degree of pain assessed using the Visual Analog Scale, complications, and follow-up patency rate.

RESULTS

The stenotic or occlusive lesions of all 51 cases resistant to conventional balloon angioplasty were promptly eliminated or alleviated (residual stenosis rate ≤ 30%), with a 100% immediate technical success rate. VascuTrak balloon catheters were successful in achieving full dilation under working pressure, of which 44 cases required a 1-time dilation (86.3%) and 7 cases required 2 dilations, which differed significantly from the average of 2.4 dilations required by the preceding conventional balloon therapy (P < 0.0001). A statistically significant improvement in the degree of pain experienced by patients who received VascuTrak balloon dilation was observed compared to that of the preceding conventional balloon dilation (P < 0.0001). One case of a brachial artery pseudoaneurysm complication occurred in the perioperative period. The primary patency rate was 88.2% at 6 months and 74.5% at 12 months.

CONCLUSION

The use of VascuTrak balloon catheter to treat autogenous AVF dysfunction resistant to conventional balloon angioplasty appears to be safe and effective, although further, large randomized controlled trials are necessary.

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.

Photochemical Tissue Passivation Reduces Vein Graft Intimal Hyperplasia in a Swine Model of Arteriovenous Bypass Grafting

BACKGROUND

Bypass grafting remains the standard of care for coronary artery disease and severe lower extremity ischemia. Efficacy is limited by poor long-term venous graft patency secondary to intimal hyperplasia (IH) caused by venous injury upon exposure to arterial pressure. We investigate whether photochemical tissue passivation (PTP) treatment of vein grafts modulates smooth muscle cell (SMC) proliferation and migration, and inhibits development of IH.

METHODS AND RESULTS

PTP was performed at increasing fluences up to 120 J/cm(2) on porcine veins. Tensiometry performed to assess vessel elasticity/stiffness showed increased stiffness with increasing fluence until plateauing at 90 J/cm(2) (median, interquartile range [IQR]). At 90 J/cm(2), PTP-treated vessels had a 10-fold greater Young's modulus than untreated controls (954 [IQR, 2217] vs 99 kPa [IQR, 63]; P=0.03). Each pig received a PTP-treated and untreated carotid artery venous interposition graft. At 4-weeks, intimal/medial areas were assessed. PTP reduced the degree of IH by 66% and medial hypertrophy by 49%. Intimal area was 3.91 (IQR, 1.2) and 1.3 mm(2) (IQR, 0.97; P≤0.001) in untreated and PTP-treated grafts, respectively. Medial area was 9.2 (IQR, 3.2) and 4.7 mm(2) (IQR, 2.0; P≤0.001) in untreated and PTP-treated grafts, respectively. Immunohistochemistry was performed to assess alpha-smooth muscle actin (SMA) and proliferating cell nuclear antigen (PCNA). Objectively, there were less SMA-positive cells within the intima/media of PTP-treated vessels than controls. There was an increase in PCNA-positive cells within control vein grafts (18% [IQR, 5.3]) versus PTP-treated vein grafts (5% [IQR, 0.9]; P=0.02).

CONCLUSIONS

By strengthening vein grafts, PTP decreases SMC proliferation and migration, thereby reducing IH.

Trans-collateral angioplasty in vascular access intervention therapy for subacute occluded vessel

We describe the first reported case of successful trans-collateral angioplasty (TCA) in vascular access intervention therapy (VAIVT) for a subacute occluded lesion in the vascular access route. TCA is a technique which has been developed in the field of endovascular therapy for peripheral arterial disease and is usually applied for a long chronic total occluded lesion with no available distal puncture site. Because such lesion characteristics suitable for being applied with TCA are not usually seen in the patients who receive VAIVT, there is little opportunity when TCA is performed in VAIVT. The present patient showed subacute occlusion in the vascular access route with well-developed collateral blood vessels. Because antegrade wiring resulted in subintimal tracking, we failed to antegradely introduce the guidewire to the vascular true lumen. Moreover, no puncture site in the venous side was anatomically available. Therefore, we adopted the strategy of TCA and successfully completed the procedure. Although we rarely encounter the situation in which TCA is necessary for VAIVT, the strategy of TCA is a promising procedure if the condition permits.

Systematic Review of Drug Eluting Balloon Angioplasty for Arteriovenous Haemodialysis access Stenosis

Background

Native or prosthetic arteriovenous (AV) fistulas are preferred for permanent haemodialysis (HD) access. These are marked with circuit steno-occlusive disease leading to dysfunction or even failure. Late failure rates have been reported as high as 50%. Standard angioplasty balloons are an established percutaneous intervention for HD access stenosis. Reported restenosis rates remain high and practice guidelines recommend a wide 6-month primary patency (PP) of at least 50% for any intervention. Neointimal hyperplasia is one of the main causes for access circuit stenosis. Drug eluting balloon (DeB) angioplasty has been proposed as an alternative intervention to reduce restenosis by local drug delivery and possible inhibition of this process.

Purpose

To systematically assess the reported efficacy and safety of DeB angioplasty in percutaneous management of prosthetic and autologous HD access stenosis.

Methods

Protocol for the review was developed following the PRISMA-P 2015 statement. An electronic database (Medline, EMBASE, Clinical Trials.gov and Cochrane CENTRAL) search was conducted to identify articles reporting on the use of DeB intervention in HD AV access. Backward and forward citation search as well as grey literature search was performed. The MOOSE statement and PRISMA 2009 statement were followed for the reporting of results. Data from the included studies comparing DeBs with non-DeBs were pooled using a random effects metaanalysis model and reported separately on randomised and non-randomised studies.

Results

Six studies reported on 254 interventions in 162 participants (mean 27 ± 10 SD). The pooled mean and median duration of follow-up was 12 and 13 months (range 6-24 months). These comprised two randomised control trials (RCTs) and four cohort studies. Participant's mean age was 64 ± 5 years and 61% were male. Target lesions (TLs) ranged from under 2 mm to 5.9 mm and 51 were reported as de novo stenosis. Device failure described as wasting of the DeB was reported in two studies (55% and 92.8%). At 6 months TL PP was reported between 70% to 97% for DeBs in the RCTs and cohort studies, and 0% to 26% for non-DeBs. TLs treated with DeBs were associated with a higher primary patency at 6 months as compared to non-DeB balloons (RCTs: odds ratio [OR] 0.25, 95% CI 0.08 to 0.77 and I2 = 19%, cohort studies: OR 0.10, 95% CI 0.03 to 0.31 and an I2 = 20%). No procedure-related major or minor complications were reported.

Conclusions

Current literature reports DeBs as being safe and may convey some benefit in terms of improved rate of restenosis when used to treat AV access disease. However, this body of evidence is small and clinically heterogeneous. A large multicentre RCT may help to clarify the role of DeBs in the percutaneous treatment of AV HD access stenosis.

An efficacy of intensive vitamin D delivery to neointimal hyperplasia in recurrent vascular access stenosis

PURPOSE

Neointimal hyperplasia (NH) causes vascular access (VA) stenosis, which results in serious under-dialytic morbidity in hemodialysis patients. We sought to assess whether a vitamin D intervention to NH lesions leads to better VA patency and examined clinical and in vitro studies.

METHODS

A pilot clinical study of six hemodialysis patients was conducted to elucidate whether 0.5 μg calcitriol injection to stenotic lesion after balloon angioplasty (PTA) maintains better vessel patency until the next follow-up angiography. Localized vitamin D exposure was utilized by delivering and fixing calcitriol intensively at the stenotic lesion through a side-hole catheter with balloon clamping. We also performed vascular smooth muscle cell (VSMC) culture to detect both apoptosis (cell death detection assay) and cell viability (5-Bromo-2'-deoxy-uridine incorporation), and explored the efficacy of vitamin D to inhibit VSMC proliferation. Additionally, immunohistochemistry (IHC) was conducted to examine vitamin D receptor (VDR) expression at NH lesion, obtained from VA surgery.

RESULTS

Percent patency, the proportion between stenotic and non-stenotic vessel diameters, increased significantly (p = 0.03) after directly catheter-delivered 0.5 μg calcitriol administration. In vitro VSMC studies, 0.1 nM calcitriol significantly (p<0.05) enhanced apoptosis and cell-cycle inhibition for two different calcitriol exposure times (15 minutes and 24 hours). IHC staining revealed that VDR-positive hyperplastic cells were observed at NH lesion.

CONCLUSIONS

Intensive vitamin D exposure at NH lesion has an ability to inhibit further VSMC proliferation, and presumably leads to greater patency rate for recurrent VA stenosis. Further studies are needed to clarify whether its unique property is exhibited through VDR-mediated mechanism.