Percutaneous treatment of central venous stenosis in hemodialysis patients: long-term outcomes

Long-Term Outcome of a "Mother-Child" Coaxial Dual-Catheter Technique for Percutaneous Transluminal Angioplasty of Central Vein Stenosis or Occlusion in Hemodialysis Patients

PURPOSE

This study aims to evaluate the long-term outcome and prognostic factors of a "mother-child" coaxial dual-catheter technique for percutaneous transluminal angioplasty (PTA) in the treatment of central vein stenosis (CVS) or central vein occlusion (CVO).

MATERIALS AND METHODS

During September 2017 to August 2020, totally, 76 hemodialysis patients with symptomatic CVS or CVO were treated with PTA using the mother-child technique. The success rate, complications, and follow-up information were collected. Cox proportional hazard analysis was used to explore the predicting factors of primary patency. Primary patency rates of different subgroups were generated with the Kaplan-Meier analysis and compared using the log-rank (Mantel-Cox) test.

RESULTS

There were 31 CVS patients and 45 CVO patients who presented with 114 PTAs. The initial procedure success rate was 98.25%. By the end of the follow-up, 57 patients (75%) had maintained functioning fistula after initial or repeated PTAs. The primary patency rates were 88.75% at 3 months, 73.36% at 6 months, 55.83% at 12 months, and 50.75% at 18 months. The secondary patency rates were 97.14% at 6 months, 87.66% at 12 months, and 82.18% at 24 months. The predictors for primary patency were history diabetes mellitus (hazard ratio [HR] = 3.1, 95% confidence interval [CI]: 1.31-7.30, P = .010), abnormal white blood cell count (HR = 1.44, 95% CI: 1.18-1.75, P < .001), lesion at subclavian-innominate vein (HR=2.75, 95% CI: 1.34-5.63, P = .006), and occlusion (HR=0.33, 95% CI: 0.14-0.76, P = .010). The primary patency was significantly lower in the subclavian-innominate vein subgroup, with a median primary patency of 4.5 (3-12.75) months, than in the nonsubclavian-innominate vein subgroup (8.5 [5-13] months; P = .005). The median duration of each PTA was 8 months for the first PTA, 7.5 months for the second PTA, and 5 months for the third PTA. There was no significant difference in the patency duration of repeated PTAs and the primary PTA (P = .389).

CONCLUSIONS

The mother-child coaxial dual-catheter technique has a good success rate and acceptable primary patency in the treatment of hemodialysis patients with CVS or CVO. Repeated PTA is as effective as the primary PTA.

CLINICAL IMPACT

This is the follow up report on the "Mother-Child" coaxial dual-catheter technique for percutaneous transluminal angioplasty of central vein stenosis or occlusion in hemodialysis patients since we first presented it in 2019. In this paper, we can see that the long-term patency rate of this technique for central venous disease is satisfactory, and repeated use of this technique does not affect the patency time. Compared with other literature reports, the surgical success rate of this technique is significantly improved. Therefore, this technique is worth popularizing in the treatment of central venous disease.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Clinical outcome of percutaneous angioplasty and covered stent placement for treatment of left brachiocephalic vein obstruction in hemodialysis patients

BACKGROUND

Left brachiocephalic vein (LBV) obstruction is a common complication in patients undergoing hemodialysis. This study aimed to compare the clinical characteristics and outcomes of patients with LBV obstruction who underwent percutaneous angioplasty or stenting.

METHODS

We performed a retrospective study of 67 hemodialysis patients with LBV stenosis or occlusion who underwent percutaneous transluminal angioplasty (PTA; n = 25) or percutaneous transluminal stenting (PTS; n = 42). We compared the clinical characteristics, lesion features, and patency between the two groups of patients.

RESULTS

The average age, sex, smoking history, body mass index, obstruction period, comorbidities, and clinical manifestations were comparable between the PTA and PTS groups. Prior ipsilateral catheterization was less common in the PTS group than in the PTA group (14.3% vs 36.0%, p < 0.05). Smaller sized balloons were used in the PTS group than in the PTA group (p < 0.05). The overall primary patency rates were similar between the two groups, whereas the secondary patency rate in the PTS group was higher than that in the PTA group (p < 0.05). The average age, sex, smoking history, body mass index, obstruction period, prior ipsilateral catheterization, comorbidities, and types of lesions were comparable between patients with or without restenosis, while patients with restenosis had a higher percentage of high venous pressure than those without restenosis (87.5% vs 60.5%, p < 0.05).

CONCLUSION

The primary patency rates were similar in the angioplasty and the stenting groups. Stenting has a significantly higher secondary patency rate than angioplasty alone for treating LBV obstruction and is required more commonly in patients without prior ipsilateral catheterization.

Complex central venous catheter for dialysis: interventional radiology experience in insertion and management of their complications

BACKGROUND

CVCs are defined 'complex' when they are inserted through non-conventional accesses or positioned in non-usual sites or substituted by IR endovascular procedures. We report our experience in using diagnostic and interventional radiology techniques for complex CVC insertion and management; we recommend some precautions and techniques that could lead to long-term availability of central venous access and to avoid non-conventional sites CVC insertion.

METHODS

We retrospectively evaluated 617 patients, between January 2010 and December 2019, (mean age 71 ± 13; male 448/617), treated in our department for insertion of tunnelled CVC for haemodialysis.

RESULTS

Among 617 patients, 241 cases (39%) are considered 'complex' because they required either a PTA with or without stenting to restore/maintain venous access or had an unusual positioning site or required unconventional access. A direct correlation between CT angiography and PTA (r = 0.95; p-value <0.001) and an inverse correlation between CT angiography and unconventional 'rescue' access (r = -0.92; p-value <0.001) were found.

CONCLUSIONS

Precise pre-operative planning of treatment in a multidisciplinary setting and diagnostic and interventional radiology procedures knowledge allows reducing complex catheterisms in haemodialysis patient.

Efficacy and Safety of Sharp Recanalization with the Stiff End of a Microguidewire for Treatment of Refractory Central Venous Occlusions in Hemodialysis Patients

BACKGROUND

Sharp recanalization is a viable procedure for some refractory central venous occlusions that cannot be recanalized with the conventional technique. The sharp recanalization procedures reported in previous studies are often rely on costly devices and with a certain proportion of complications. This study aimed to present an inexpensive and risk-controllable coaxial centrifugally sharp recanalization technique that was independent of any additional costly devices.

METHODS

This retrospective study enrolled 8 patients who had received sharp recanalization of central venous occlusions, between August 2017 and May 2021. The sharp recanalization technique was performed centrifugally with the stiff end of a microguidewire after the lesions failed to be passed through with the conventional technique. Clinical data of patients on their lesions, technical success rate, procedure-related complications, and patency rates were collected and analyzed to assess the efficacy and safety of the technique.

RESULTS

Technical success was achieved in all patients, with no complications were observed. All symptoms were ameliorated within 48h postsurgery. The median follow-up period was 22 months. All patients maintained patency or assisted patency at 12 month follow-up.

CONCLUSIONS

Sharp recanalization performed centrifugally with the stiff end of the microguidewire could be a cost-effective and safe alternative procedure for the treatment of refractory central venous occlusion that cannot be recanalized with conventional technique.

Objective Performance Goals Based on a Systematic Review and Meta-Analysis of Clinical Outcomes for Bare-Metal Stents and Percutaneous Transluminal Angioplasty for Hemodialysis-Related Central Venous Obstruction

PURPOSE

To use safety and efficacy outcomes following treatment with percutaneous transluminal angioplasty (PTA) and/or stent placement for thoracic central venous obstruction in hemodialysis-dependent patients to establish objective performance goals (OPGs).

METHODS

A systematic literature review and meta-analysis were conducted for articles published between January 1, 2000, and August 31, 2021. Efficacy outcomes included primary patency rates at 6 and 12 months, and safety outcomes included adverse events (AEs) categorized as access loss, procedure-related AEs, and serious AEs (SAEs). OPGs were derived from the upper and lower bounds of the 95% confidence intervals for primary patency and SAE rates.

RESULTS

Of 66 articles reviewed, 17 met the inclusion criteria (PTA, n = 4; stent placement, n = 5; PTA/stent, n = 8). The 6- and 12-month primary patency rates for PTA were 50.9% and 36.7%, respectively. Based on these findings, the proposed 6- and 12-month primary patency OPGs identifying superiority against PTA were 66.5% and 52.6%, respectively, and those for noninferiority were 39.0% and 25.7%, respectively. For stent placement, the 6- and 12-month primary patency rates were 69.7% and 47.9%, respectively. The proposed 6- and 12-month primary patency OPGs identifying superiority were 82.1% and 64.1%, respectively, and those for noninferiority were 59.3% and 35.8%, respectively. SAE rates for PTA and stent placement were 3.8% and 8.1%, respectively. Proposed safety OPGs for noninferiority versus superiority for PTA and stent placement were 10.1% versus 1.4% and 13.6% versus 4.8%, respectively.

CONCLUSION

The OPGs derived from real-world studies of PTA and stent placement may serve as a benchmark for future interventions indicated for this patient population.

Unilateral jugular vein stenosis in five horses and experience with percutaneous transluminal angioplasty

BACKGROUND

Venous stenosis, a possible cause of jugular dilatation and congestion, is well known in human medicine but has poorly been described in horses.

OBJECTIVE

To report unilateral jugular vein stenosis as a cause of jugular vein dilatation in horses and describe treatment by percutaneous transluminal angioplasty (PTA).

STUDY DESIGN

Case report.

METHODS

Details of horses diagnosed with unilateral jugular stenosis were retrieved from medical records.

RESULTS

Five horses were presented with a non-painful, unilateral dilatation of the jugular vein of which two horses showed headshaking during exercise. In one horse an indwelling catheter had been used and jugular dilatation developed 4 weeks later. In the other horses, no intravenous injections had been administered in the months before jugular dilatation developed. Ultrasonographic examination revealed venous stenosis in all horses approximately 5-10 cm cranial to the thoracic inlet. The internal diameter at the level of this stenosis was only 1-3.1 mm. The length of the stenosis was about 15-19 mm with a markedly thickened intima and media on ultrasonography. After enoxaparin treatment, PTA was performed in three horses. During the procedure the stenotic vein was dilated three times with progressively increasing pressures up to 12 atm. The stenotic diameter increased to a maximum of 4.9 mm with improved jugular blood flow. Aftercare included anti-inflammatory and anti-thrombotic therapy.

CONCLUSION

Jugular vein stenosis occurs in horses and should be included in the differential diagnoses of unilateral jugular vein dilatation. It may present in the absence of previous intravenous treatment. PTA of the jugular vein is feasible to improve jugular blood flow.

A systematic review of venoplasty versus stenting for the treatment of central vein obstruction in ipsilateral hemodialysis access

OBJECTIVE

This review examines the evidence regarding treatment of central vein obstruction (CVO) in the setting of ipsilateral hemodialysis access. The aim of this work is to identify whether long-term venous patency after central vein stenting is superior compared with balloon venoplasty. To date, there are no evidence-based guidelines to direct the management of CVO in the setting of ipsilateral hemodialysis access.

METHODS

An extensive systematic database search was performed using Medline, Embase, and the Cochrane Databases to identify all articles published from January 2000 to November 2019 comparing the management of CVO with venoplasty and/or stenting in the setting of ipsilateral hemodialysis access fistulae/grafts.

RESULTS

There were 655 patients with 456 stenoses and 208 occlusions who were treated; 288 underwent venoplasty and 345 underwent stenting. Twenty-two patients failed intervention owing to an inability to traverse the occlusion. The most affected vein was the brachiocephalic vein. A superior primary patency (PP) is noted in those treated with stenting compared with venoplasty in the first 2 years. Overall, both treatments are suboptimal demonstrating a 12-month PP rate of less than 60%. Assisted PP and secondary patency rates were similar for both venoplasty and stenting with a 12-month secondary patency rate of 77.8% to 91.6% for venoplasty and 89.6% to 98.4% for stenting. Periprocedural and long-term complications were rare for both interventions, occurring in 2% of patients.

CONCLUSIONS

Although both treatments demonstrated poor patency rates, greater PP is noted for stenting in the first 2 years. Coupled with low complication rates, this finding highlights a potential benefit of stenting as a first-line treatment for CVO. Allowing for the overall poor quality of current studies, even this short-term improvement in PP may benefit patients undergoing hemodialysis. Further research with randomised control trials as well as assessment of adjuvant techniques such as drug-coated stents and balloons, anticoagulant therapy, and the role of intravascular ultrasound use is required.

The diagnostic value of multi-detector CT angiography for catheter-related central venous stenosis in hemodialysis patients

The objective is to compare Multi-detector CT angiography (MDCTA) and digital subtraction angiography (DSA) in diagnosing hemodialysis catheter related-central venous stenosis (CVS). During a period of 6 years, hemodialysis patients with suspected catheter related-CVS who received both MDCTA and DSA were retrospectively enrolled. We analyzed the sensitivity, specificity, accuracy, Cohen's kappa coefficient (κ) and other diagnostic parameters for MDCTA compared to DSA. A total of 1533 vascular segments in 219 patients were analyzed. Among the 280 lesions identified by DSA, 156 were correctly identified by MDCTA. There were 124 false negative and 41 false positive diagnoses. MDCTA had a high specificity (96.73%) but a low sensitivity (55.71%), with a moderate inter-test agreement (κ = 0.5930). In stratified analyses of vascular segments, the specificities of MDCTA were 89.93% (superior vena cava), 98.95% (left brachiocephalic vein), 95.33% (right brachiocephalic vein), 99.53% (left subclavian vein), 97.61% (right subclavian vein), 97.13% (left internal jugular vein), and 95.86% (right internal jugular vein), while the sensitivities were 90.00%, 65.52%, 66.67%, 87.50%, 40.00%, 20.00% and 8.11%, respectively. Good to excellent inter-test agreement was observed for the superior vena cava (κ = 0.7870), left brachiocephalic vein (κ = 0.7300), right brachiocephalic vein (κ = 0.6610), and left subclavian vein (κ = 0.8700) compared with poor to low agreement for the right subclavian vein (κ = 0.3950), left internal jugular vein (κ = 0.1890), and right internal jugular vein (κ = 0.0500). MDCTA had a high specificity in diagnosing hemodialysis catheter related-CVS. Its sensitivity varied by central venous segments, with better performance in superior vena cava and brachiocephalic veins.

Evaluating a Novel Telescoping Catheter Set for Treatment of Central Venous Occlusions

BACKGROUND

Central venous occlusive disease (CVOD) is a prevalent problem in patients with end-stage renal disease (ESRD) and can lead to access malfunction or ligation for symptomatic relief. The purpose of this study is to evaluate the efficacy of the TriForce® Peripheral Crossing Set (Cook Medical), a novel reinforced telescoping catheter set designed to provide additional support for crossing difficult central venous occlusions.

METHODS

This is a single-center retrospective study from a quaternary referral center. We identified 37 patients over a 17-month period who underwent 56 attempts at endovascular recanalization for the treatment of central venous occlusion. Technical success rates, procedural data, and outcomes were compared between those undergoing recanalization using traditional wire/catheter sets versus the TriForce catheter set.

RESULTS

Average age was 48 ± 2 years. Comorbidities were similar between the two cohorts and included ESRD (61%), deep venous thrombosis (30%), and May-Thurner syndrome (7%). Forty attempts were made with traditional wire/catheter sets and 16 attempts with the TriForce catheter set to treat 2.1 ± 0.2 and 1.9 ± 0.3 occluded venous segments, respectively (P = 0.74). Technical success rates were significantly higher for the group undergoing recanalization using the TriForce catheter (69% versus 38%, P = 0.04) and 4 patients were successfully recanalized using the TriForce catheter set after a failed attempt with traditional wire/catheter sets. Mean fluoroscopy time and radiation dose were 13 ± 3 min and 14,623 ± 2,775 μGy∗m² for traditional techniques versus 30 ± 6 min and 30,408 ± 10,433 μGy∗m² for the novel telescoping catheter set (P = 0.01 and 0.09, respectively). Freedom from reintervention at 1 year was 60% for the TriForce cohort versus 44% for the traditional wire/catheter cohort (P = 0.25).

CONCLUSIONS

The novel TriForce reinforced telescoping catheter set is a useful adjunct that may improve recanalization rates of CVOD compared with traditional wire/catheter sets.

[Thoracic Central Venous Occlusive Disease and Haemodialysis Access]

Benign central venous thoracic occlusion is a frequent issue in haemodialysis patients. Symptomatic stenosis affects quality of life and can cause dysfunction of arteriovenous access or make it impossible to implant a haemodialysis catheter. Common risk factors for the development of the occlusions are central venous catheters and cardiac rhythm devices. The gold standard for diagnosis is venous angiography. Treatment of asymptomatic lesions can lead to clinical deterioration and should be avoided. The primary method of treatment for symptomatic patients is endovascular therapy. Repeat balloon angioplasty is a standard therapy. In case of elastic recoiling or early recurrence, placement of bare metal stent or stent graft could be considered. Surgical options should be preserved only for refractory cases. Further randomised trials are needed to prove the efficacy of new devices, such as dedicated venous stents and drug coated balloons.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

Level 3a.

Efficacy and safety of a mother-child technique for recanalization of chronic central venous occlusive disease in hemodialysis patients

OBJECTIVE

There is no optimal treatment for central vein occlusive disease that remains a major contributor to vascular access impairment. This study aimed to review the outcomes of percutaneous treatment with a mother-child technique in the treatment of symptomatic central venous stenosis (CVS) and central venous occlusion (CVO) in patients on hemodialysis.

METHODS

Data were collected retrospectively and included all consecutive patients with CVS or CVO who were treated with percutaneous angioplasty and stenting. The occlusive lesions were crossed using the mother-child technique with an angiographic catheter-in-guiding catheter system.

RESULTS

A total of 36 patients with symptomatic CVS and 45 patients with total CVO were included. The average age and gender composition were similar between the two groups. Patients with CVO had higher prevalence of diabetic nephropathy than CVS (24.4% vs 5.6%; P < .05). Lesion success, device success, and procedural success were achieved in 36 (100%), 1 (100%), and 36 (100%) patients in the CVS group and in 43 (95.6%), 11 (100%), and 43 (95.6%) patients in the CVO group, respectively. There were no severe complications or procedure-related deaths in either group. During follow-up (median, 6 months), the primary patency rates were 89.7% (CVS) and 81.0% (CVO) at 6 months and were 54.2% (CVS) and 47.1% (CVO) at 12 months. The assisted primary patency rates were 100% (CVS) and 91.2% (CVO) at 6 and 12 months.

CONCLUSIONS

With extra backup support of the mother-child technique, percutaneous treatment provides an effective and safe method for recanalization of chronic venous occlusion in patients on hemodialysis.

Site of service influence on stent use for hemodialysis access interventions

OBJECTIVE

With rising health care spending in the United States, the Centers for Medicare and Medicaid Services (CMS) in recent years attempted to use reimbursement rates to influence use of less expensive care sites for covered patients, such as ambulatory surgery centers (ASCs) and office-based laboratories (OBLs), in lieu of hospital service sites. It has been suggested that cost savings have not been realized because of more procedures being performed by physicians with ownership interests in nonhospital facilities. CMS adopted massive reimbursement changes for 2019 OBL and ASC-based procedures, which reduced dialysis access angioplasty reimbursement in the ASC setting by 50%, whereas facility reimbursement for stenting increased by 33% above prior levels. The clinical utility of adjunctive stenting in treating dialysis access stenosis remains controversial and highly discretionary. As a vascular group performing such procedures in both a hospital and nonhospital facility in which we have equity interest, we reviewed our use of stents in dialysis access procedures both in the hospital and in the ASC/OBL to determine whether site of service affected stent use.

METHODS

A retrospective review of a prospectively maintained database was performed from 2014 to 2018. All patients undergoing dialysis access angiography with angioplasty and adjunctive stent placement at our OBL (later ASC) and our primary hospital were included in the study.

RESULTS

There were 961 angioplasty or stent procedures performed for dialysis accesses between the two sites, 564 (58.7%) in the hospital setting and 397 (41.3%) at the OBL/ASC. There was a significant difference in race and age between the two sites, with younger, minority patients more frequently being treated in the hospital and older, white patients more likely to be treated in the ambulatory setting; 153 (27.1%) underwent adjunctive stent placement in the hospital and 127 (32.0%) in the ambulatory setting (P = .09).

CONCLUSIONS

Whereas financial incentives have not yet had an appreciable influence on stent use for dialysis access within previous reimbursement paradigms, the dramatic changes recently adopted by CMS may well alter this dynamic and could lead to substantially higher overall costs without proven clinical advantage. Interventionalists may be incentivized to add stents when performing balloon angioplasty in ASCs. With high failure and reintervention rates and increasingly expensive adjuncts (drug-coated balloons and stents, covered stents), the cost implications of attempts to incentivize interventionalists toward a specific type of procedure or site of care are substantial, and unintended negative consequences are likely to occur.

Outcomes of Central Venoplasty in Haemodialysis Patients

Objective: To review the outcomes of central venoplasty in the treatment of symptomatic central vein stenosis in patients undergoing haemodialysis via an ipsilateral arteriovenous fistula (AVF).

Methods: Data were collected retrospectively, and included all the consecutive cases of central venoplasty between January 2008 and December 2015.

Results: A total of 132 central venoplasties in 76 patients were performed, with incidence of symptomatic central vein stenosis at 7.4%. Of the patients, 66% were male and the mean age was 61 years. The most frequent indication was decreased dialysis access flow rates (58%) and 52% of all the patients had symptoms of upper limb swelling. The patients who had previous ipsilateral tunneled internal jugular vein dialysis catheters made up 58% of the patients. The mean time from AVF creation to first central venoplasty was 24 months, and 74% of the cases required a second central venoplasty and the mean time to second venoplasty was 7 months. The overall post intervention assisted primary patency rate was 87%, 74%, 63%, and 42% at 6, 12, 18, and 24 months respectively. Statistically significant differences were found in primary assisted patency (p=0.025) and time to second procedure (p=0.039) comparing those with and without a history of ipsilateral tunneled dialysis catheter.

Conclusion: Central venoplasty is technically feasible with low procedural risk. The maintenance of the AVF patency usually requires multiple procedures at average interval of 7 months. Patients with a history of upper limb tunneled dialysis catheter ipsilateral to the side of central vein stenosis or AVF have a less favorable outcome compared to those without.

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.

An Economic Analysis of Stent Grafts for Treatment of Vascular Access Stenosis: Point-of-Care and Medicare Perspectives in the United States

PURPOSE

To conduct an economic analysis on the impact of increased stent graft (SG) use for treatment of arteriovenous graft (AVG) anastomotic stenosis or arteriovenous fistula (AVF)/AVG in-stent restenosis (ISR) from United States point-of-care (POC) and Medicare perspectives.

MATERIALS AND METHODS

The analyses compared initial device and reintervention costs over 2 years between current and projected treatment mixes, including percutaneous transluminal angioplasty (PTA), bare metal stents (BMSs), and SGs. In projected scenarios, the absolute increase in SG use was approximately 3%. Costs included procedure reimbursement rates (Medicare) and device list prices (POC) for index procedures and reinterventions. Reintervention rates and types were informed by the RENOVA and RESCUE randomized trials. Reinterventions were primarily PTA only; however, stent use occurred a proportion of the time. BMS reintervention rates were assumed to be identical to PTA based on observational data. A population size of 1,000 patients was assumed.

RESULTS

To the POC (n = 1,000), increased SG use was predicted to result in cost savings ranging from $4,106 to $34,420 for AVG anastomotic stenosis. For AVF/AVG ISR, increased SG use was predicted to result in either a cost increase of $17,187 or a cost savings of $13,159. To Medicare (n = 1,000), increased SG use was predicted to save costs for both populations, with savings ranging from $57,401 to $169,544.

CONCLUSIONS

The use of SG for treatment of AVG anastomotic stenosis and AVF/AVG ISR appears to be economically favorable for POC providers and Medicare. Further data on reintervention rates are required from other SG trials to validate findings.

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.

The efficacy of drug-eluting stent for recurrent central venous restenosis in a patient undergoing hemodialysis

Introduction:

Recurrent central venous restenosis is problematic in patients with ipsilateral arteriovenous fistula. We report our experience using a drug-eluting stent for the treatment of recurrent central vein restenosis.

Case report:

A 60-year-old man consulted our hospital because of recurrent swelling of his left upper limb with radial-cephalic arteriovenous fistula that originated in the distal forearm. More than 3 years prior, two bare-metal stents were placed for the obstructed lesions in the left subclavian and brachiocephalic venous lesions, and repeated balloon angioplasty for recurrent in-stent stenosis was performed approximately every 3 months. Angiography with iodinated contrast agents revealed an approximately 3-cm-long restenosis at the distal part of the bare-metal stents. One drug-eluting stent (Zilver PTX Drug-Eluting Peripheral Stent; Cook Medical, Bloomington, IN, USA) was deployed at the narrowing lesion, followed by balloon angioplasty. The stenotic lesion was successfully and safely dilated. The patient consulted our hospital 5.5 months after drug-eluting stent placement because of restenosis at the distal part of the drug-eluting stent, but only in a shorter segment than before. Freedom from clinically driven target-lesion revascularization (TLR) extended from 3.1 to 5.5 months after drug-eluting stent placement. Although additional implantation of the second drug-eluting stent was required 14.6 months after the first drug-eluting stent placement, freedom from TLR before/after the second drug-eluting stent placement extended from 4.4 months to more than 8.6 months.

Conclusion:

Drug-eluting stent placement is an effective strategy for recurrent central venous stenosis in patients with ipsilateral arteriovenous fistula. To our knowledge, this is the first report of drug-eluting stent placement for recurrent venous stenosis in a patient undergoing hemodialysis.

Percutaneous intervention for symptomatic central vein stenosis in patients with upper limb arteriovenous dialysis access

Central venous stenosis is an important hindrance to long-term maintenance of arteriovenous access in the upper extremities in dialysis patients.

Aim

The present study was done to determine feasibility and clinical success of endovascular approach for the treatment of symptomatic central venous stenosis associated with significant ipsilateral limb edema in dialysis patients with vascular access in the upper limb.

Methods

A database of hemodialysis patients who underwent endovascular treatment for central venous stenosis from January 2014 to January 2017 at our institute was retrospectively reviewed. Follow-up was variable.

Results

The study included ten patients (6 men and 4 women) with a mean age of 45.2 years, who underwent thirteen interventions during a period of 3 years. The technical success rate for endovascular treatment was 100%. One patient underwent primary PTA (percutaneous transluminal angioplasty). Seven patients underwent primary PTA and stenting. Three patients underwent secondary PTA. One among these patients underwent secondary PTA twice along with fistuloplasty. One patient underwent secondary PTA with stenting. No immediate complications were encountered during the procedure. Our study shows a primary patency rate of 67% and 33% at 6 months and 12 months for PTA with stenting. Our study also shows secondary or assisted primary patency of 75% at 6 months of follow-up.

Conclusions

Endovascular therapy (PTA) with or without stenting for central venous stenosis is safe, with low rates of technical failure. Multiple additional interventions are the rule and long-term patency rate is not very good.

Treatment of central venous in-stent restenosis with repeat stent deployment in hemodialysis patients

Purpose

To report patency rates for stent deployment for treatment of in-stent stenosis of the central veins of the chest in hemodialysis patients.

Materials and Methods

A retrospective analysis was performed on 29 patients who underwent 35 secondary percutaneous transluminal stent (PTS) deployments for in-stent stenosis within the central veins that were refractory to angioplasty and ipsilateral to a functioning hemodialysis access (in-stent PTS group). For comparison, patency data were acquired for 47 patients who underwent 78 successful percutaneous transluminal angioplasty (PTA) procedures for in-stent stenosis (in-stent PTA group) and 55 patients who underwent 55 stent deployments within native central vein stenosis refractory to angioplasty (native vein PTS group).

Results

The 3-, 6-, and 12-month primary lesion patency for the in-stent PTS group was 73%, 57%, and 32%, respectively. The 3-, 6-, and 12-month primary patency for the in-stent PTA group was 70%, 38%, and 17% and for the native vein PTS group was 78%, 57%, and 26%, which were similar to the in-stent PTS group (p = 0.20 and 0.41, respectively). The 3-, 6-, and 12-month secondary access patency was 91%, 73%, and 65% for the in-stent PTS group. Sub-analysis of the in-stent PTS group revealed no difference in primary (p = 0.93) or secondary patency rates (p = 0.27) of bare metal stents (n = 23) compared with stent grafts (n = 12).

Conclusions

Stent deployment for central vein in-stent stenosis refractory to angioplasty was associated with reasonable patency rates, which were similar to in-stent PTA and native vein PTS.

The feasibility and safety of a through-and-through wire technique for central venous occlusion in dialysis patients

Background

To retrospectively compare the operation time, success rate and efficacy between unidirectional and bidirectional procedures in the treatment of central venous occlusion diseases (CVOD), assess the advantages of the bidirectional approach, and determine the characteristics of CVOD appropriate for the bidirectional approach treatment.

Methods

A total of 49 patients who underwent endovascular interventions with all relevant data between January 2011 and December 2015 at the First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China, were included in this retrospective study, and were categorized into two groups: the 19 patients in group 1 had undergone percutaneous transluminal venoplasty (PTV) via a conventional technique (unidirectional procedure from the vein distal or proximal to the obstructive lesion), and the 30 in group 2 had undergone flossing wire technique (bidirectional procedure from femoral vein and the vein distal to obstructive lesion and using a flossing wire technique). The technical success rate, the fluoroscopy time in the procedure, perioperative complications, and patency were evaluated retrospectively.

Results

Compared with group 1, group 2 had a higher initial technical success rate (83.33% vs. 47.36%, p = 0.012) but a shorter fluoroscopy time (82.6 ± 26.1 vs. 116.1 ± 42.1, p = 0.048). Receiver operating characteristic (ROC) analysis indicated that a lesion with a length of 6.5 cm was the best predictor of technique success (p = 0.02) in group 1, but no cut-off value was identified for group 2. There were no significant differences in perioperative complications between these two groups. The complication rates were 31.58% (6/19) in group 1 and 6.67% (2/30) in group 2, (p = 0.043), respectively. No significant difference was observed between these two groups with respect to the stent patency rate.

Conclusion

Compared with the conventional technique, the flossing wire technique has a higher success rate, shorter fluoroscopy time, fewer complications and similar patency rate. It is a feasible treatment for CVOD, especially for long obstructive lesions.

Simultaneous Iliac Vein Bovine Pericardial Patch Venoplasty and Creation of PTFE Lower Limb Arteriovenous Fistula Graft for Rescue Vascular Access

BACKGROUND

We present a case of external iliac vein patch venoplasty to accommodate rescue vascular access via a polytetrafluoroethylene loop arteriovenous fistula graft (AVG) for a patient with multiple central venous stenoses.

METHODS

A 35-year-old female with anti-glomerular basement membrane antibody disease required rescue vascular access for hemodialysis. Repeated occlusion and/or thrombosis of long-term central venous access cannulae, to facilitate dialysis, had caused stenosis of brachiocephalic veins: right external iliac vein and occlusion of the left common iliac vein. A previous right brachiobasilic fistula had occluded within 1 year. No other upper limb options for arteriovenous fistula (AVF) were available. A right external iliac vein bovine patch angioplasty concurrently with a polytetrafluoroethylene AV graft between common femoral artery and common femoral vein was performed to restore venous patency and allow rescue dialysis access.

RESULTS

At 3-year follow-up, the fistula remains widely patent with 2 L/min flow rates and no recurrent stenosis to the treated iliac vein. She has not required any further surgical or interventional radiological procedures to maintain fistula or central venous patency. Central venous stenosis or occlusion is common for patients requiring dialysis, especially those with multiple previous long-term central venous cannulations. If restriction of outflow is present, AVF may fail. Venous patch angioplasty in these cases is a successful technique, allowing AVF formation and long-term patency.

CONCLUSION

Central venous stenosis can be treated successfully with patch venoplasty to accommodate AVF/AVG formation for rescue vascular access; this is a potentially lifesaving intervention for patients requiring dialysis.

Endovascular treatment of central venous obstruction as a complication of prolonged hemodialysis - Preliminary experience in a tertiary care center

Background:

Central venous disease is a serious complication in patients undergoing hemodialysis, often presenting with symptoms of venous hypertension. Treatment is aimed to provide symptomatic relief and to maintain hemodialysis access site patency.

Aim:

To describe our initial experience in the endovascular treatment of central venous stenosis or obstruction in patients undergoing hemodialysis.

Settings and Design:

This was a retrospective study carried out in a tertiary care center. Study duration was 24 months. Follow-up was variable.

Materials and Methods:

Eleven patients of chronic renal failure undergoing hemodialysis presented with central vein stenosis or obstruction having ipsilateral vascular access, between July 2012 and July 2014. All the patients underwent endovascular treatment and were analyzed retrospectively.

Results and Conclusion:

A total of 11 patients (4 male and 7 female) underwent 18 interventions for 13 stenotic segments during a time period of 2 years. Eight stenotic segments were in brachiocephalic vein, three in subclavian vein, and two in axillary veins. The technical success rate for endovascular treatment was 81.8%. Two patients underwent percutaneous transluminal angioplasty (PTA) alone and presented with restenosis later. Balloon angioplasty followed by stenting was done in seven patients, two of which required reintervention during follow-up. We found endovascular treatment safe and effective in treating central venous disease.

Comparison of two Endovascular Treatments of a Stenosed Arteriovenous Fistula: Balloon-Angioplasty with and without Stenting

Purpose

Arteriovenous fistulas (AVFs) are created in patients to enable a permanent vascular access for hemodialysis. The AVF causes changes in the hemodynamic conditions leading to possible complications, stenoses being the most common one. Our objective was to compare the effect of treating the stenosed AVF by balloon-angioplasty, whether followed or not with stenting.

Methods

We considered an AVF presenting an 60% arterial stenosis and simulated the two endovascular treatments using an implicit approach. We then simulated the fluid-structure interactions (FSI) within (i) the patient-specific stenosed AVF, (ii) the AVF after angioplasty, and (iii) the AVF after angioplasty plus stenting with ANSYS Workbench.

Results

We show that a self-expandable stent does not modify the curvature of the vessel after angioplasty; it only increases the local Young modulus of the stented wall by an order of magnitude. The results of the FSI simulations indicate that the two treatments induce the same hemodynamic conditions: they both reduce the pressure difference across the stenosis, while maintaining the flow distribution downstream of the stenosis. The venous flow rate that has to be guaranteed for hemodialysis is unaltered. Thanks to its large axial flexibility, the self-expandable stent causes at maximum a three-fold increase in the internal wall stresses at peak systole as compared to angioplasty alone.

Conclusions

By maintaining the vessel lumen shape over time, the stent is likely to reduce the risk of restenosis that can otherwise occur after balloon-angioplasty because of the viscoelastic recoil of the vessel.

Acesso vascular para hemodialise: o que ha de novo?

O aumento da expectativa de vida dos portadores de doenças crônicas, entre as quais a insuficiência renal crônica, faz com que métodos de tratamentos estejam em constante aperfeiçoamento. O uso em longo prazo da hemodiálise torna necessário confeccionar e manter acessos vasculares de utilização duradoura. Tanto as fístulas arteriovenosas - primeira opção de acesso para os pacientes hemodialíticos - como os cateteres vêm sendo objeto de estudos na literatura, na tentativa de prolongar sua vida útil. Esta revisão tem como objetivo relatar as alternativas e soluções atuais para os acessos vasculares para hemodiálise.

Stent grafts for central venous occlusive disease in patients with ipsilateral hemodialysis access

PURPOSE

To assess long-term outcomes of stent grafts in patients with symptomatic central venous stenoses and occlusions ipsilateral to hemodialysis grafts or fistulas.

MATERIALS AND METHODS

The study included 52 of 55 consecutive patients with symptomatic stenoses of the central veins draining upper limb dialysis access grafts or fistulas treated with stent grafts. Indications for stent grafts were poor angioplasty results, rapid recurrence, or total occlusion. Endpoints were lesion patency and access patency following intervention. Mean follow-up was 25 months with a median of 24 months and 1.25 additional procedures per patient year. Patency rates were calculated using Kaplan-Meier analysis.

RESULTS

All stent grafts were successfully deployed. The lesion patency rates at 6, 12, 24, and 36 months after intervention were 60%, 40%, 28%, and 28%. The access patency rates at 6, 12, 24, and 36 months after intervention were 96%, 94%, 85%, and 72%. There was one major complication and no minor complications. In 40 patients (77%), the internal jugular vein confluence was covered by the stent graft. In five patients, the dialysis circuits became occluded, with no clinical sequelae in four; one patient was lost to follow-up. The contralateral brachiocephalic vein was covered in three patients (6%), preventing contralateral access construction in one patient.

CONCLUSIONS

Central vein stent graft placement in patients with hemodialysis access is associated with prolonged access patency. Coverage of major vein confluences, which occurred in 83% of the patients in this series, can compromise future access and should be avoided whenever possible by careful technique.

Central vein stenosis

Central vein stenosis (CVS) is commonly seen in patients receiving hemodialysis through an arteriovenous access, threatening the usability of arteriovenous access for dialysis. Subclavian and internal jugular catheters are prime reasons for the development of CVS, especially in the setting of long-term use of multiple catheters. CVS related to cardiac rhythm devices also is seen frequently. Idiopathic CVS can be encountered, although it is less common. Clinical features ultimately become sufficiently prominent to prompt angiographic evaluation. CVS should be evaluated carefully because management must be individualized. The primary method for treatment of CVS is endovascular intervention, including angioplasty and stent placement, whereas surgical options should be pursued in only refractory cases due to the invasiveness of the intervention. Early referral of patients for chronic kidney disease care; timely discussion of kidney replacement modality choices, including nonhemodialysis options such as peritoneal dialysis and kidney transplantation; placement of arteriovenous access prior to the onset of dialysis; and avoidance of catheters and other central vein instrumentation will prevent the development of CVS in most patients with kidney disease.

Subclavian vein angioplasty during arteriovenous fistula surgery: case report and literature review

Patients with chronic kidney disease stage 5 are generally treated by hemodialysis, preferentially performed via an arteriovenous fistula (AVF). We report the case of a 58-year-old male patient with diabetes mellitus, hypertension and end-stage renal disease in whom hemodialysis was conducted via a long-term catheter. His medical record described numerous central venous cannulations and several AVF creations. The patient developed subclinical subclavian stenosis that required creation of a new vascular access route. The purpose of this case report is to describe treatment of subclavian vein stenosis during AVF creation.

Endovascular stenting for left subclavian venous stenosis for a hemodialysis patient with a persistent left superior vena cava

A persistent left superior vena cava (PLSVC) is the most common thoracic venous anomaly, and we should be aware of its existence. We encountered a case of significant left arm swelling due to recurrent left subclavian venous stenosis in a hemodialysis patient with a PLSVC. Endovascular stent placement was performed safely and effectively for the stenosis employing the pull-through technique, in which a guidewire was passed from the left internal jugular vein to the access vein. On the following day, left arm swelling had improved. 3 months after stent placement the left arm swelling has not recurred.

Vascular Access Flow Reduction for Arteriovenous Fistula Salvage in Symptomatic Patients with Central Venous Occlusion

Purpose

Vascular access patients with central vein (CV) stenosis or occlusion may have significant symptoms. Treatment is generally by balloon angioplasty, with or without stenting. However, CV lesions may not be correctable and when treated, tend to recur. Surgical bypass of CV obstruction is a major procedure and ligation of the access may leave the patient dependent on catheter dialysis. We review a precision inflow banding procedure to limit vascular access flow and pressure for symptomatic patients with CV obstruction while preserving access functionality.

Materials and Methods

All individuals with symptomatic CV occlusive disease who underwent an autogenous vascular access inflow restriction procedure by the two senior authors were identified. All had failed attempts to correct CV lesions by angioplasty and stent placement. A precision banding procedure was used for access inflow reduction with the addition of real-time intravascular flow monitoring.

Results

Twenty-two patients were identified. Ages were 22–72 years (mean=43 years). Nine patients (40.9%) were women, and 8 (36.4%) obese. Mean access flow was 1640 mL/minute before banding decreased to 820 mL/minute after banding (P<.01). All patients had access salvage. Swelling resolved promptly in 20 patients and was markedly improved in two individuals. Three patients underwent aneurysm repair with simultaneous inflow banding and decreased intra-access pressure after flow restriction. Two fistulas failed at eight and 13 months. Mean follow-up was 8 months.

Conclusions

The symptoms of hemodialysis vascular access patients associated with non-correctable central venous lesions resolved successfully and their access was maintained using a precision inflow banding procedure.

Endovascular Intervention for Central Venous Cannulation in Patients with Vascular Occlusion after Previous Catheterization

Objectives

This study was designed to assess endovascular intervention for central venous cannulation in patients with vascular occlusion after previous catheterization.

Methods

Patients referred for endovascular management of central venous occlusion during a 42-month period were identified from a regional endovascular database, providing prospective information on techniques and clinical outcome. Corresponding patient records, angiograms, and radiographic reports were analyzed retrospectively.

Results

Sixteen patients aged 48 years (range 0.5–76), including 11 females, were included. All patients but 1 had had multiple central venous catheters with a median total indwelling time of 37 months. Eleven patients cannulated for hemodialysis had had significantly fewer individual catheters inserted compared with 5 patients cannulated for nutritional support (mean 3.6 vs. 10.2, p<0.001) before endovascular intervention. Preoperative imaging by magnetic resonance tomography (MRT) in 8 patients, computed tomography (CT) venography in 3, conventional angiography in 6, and/or ultrasonography in 8, verified 15 brachiocephalic, 13 internal jugular, 3 superior caval, and/or 3 subclavian venous occlusions. Patients were subjected to recanalization (n=2), recanalization and percutaneous transluminal angioplasty (n=5), or stenting for vena cava superior syndrome (n=1) prior to catheter insertion. The remaining 8 patients were cannulated by avoiding the occluded route.

Conclusions

Central venous occlusion occurs particularly in patients under hemodialysis and with a history of multiple central venous catheterizations with large-diameter catheters and/or long total indwelling time periods. Patients with central venous occlusion verified by CT or MRT venography and need for central venous access should be referred for endovascular intervention.

Use of a rosch-uchida needle for recanalization of refractory dialysis-related central vein occlusion

OBJECTIVE

The purpose of this study was to evaluate our experience with the use of a Rösch-Uchida needle technique to recanalize central vein occlusion that cannot be traversed with a guidewire.

MATERIALS AND METHODS

We retrospectively evaluated 33 recanalization procedures performed with a Rösch-Uchida needle on 20 men and 13 women with central vein occlusion during the period January 1999-December 2008. The occlusions were in the subclavian vein (n = 29) and the brachiocephalic vein (n = 4). A 9- or 10-French Rösch-Uchida introducer sheath was advanced centrally to abut the occlusion. The Rösch-Uchida needle was directed and advanced toward a transfemoral angiographic catheter placed on the central side of the occlusion. After passage of a guidewire through the occlusion, balloon angioplasty and stent insertion were performed. The outcome measures evaluated were technical success rate, primary and secondary patency, and complication rate.

RESULTS

The mean occlusion length was 1.73 +/- 0.8 cm. The rate of technical success of recanalization was 93.9% (31 of 33 procedures). The 3-, 6-, and 12-month primary patency rates were 43.6%, 24%, and 8%, and the 3-, 6-, and 12-month secondary patency rates were 77.4%, 68.8% and 55.9%. One patient reported shoulder pain lasting 2 weeks, which resolved with conservative treatment.

CONCLUSION

Use of a Rösch-Uchida needle to recanalize central vein occlusion refractory to a traditional procedure is feasible and safe and can preserve the involved extremity for long-term hemodialysis.