Cephalic Arch Stenosis in Dialysis Patients: Review of Clinical Relevance, Anatomy, Current Theories on Etiology and Management

The Alpha to Omega of Dialysis Access: Arteriovenous Fistula and Graft (Part 1)

Background: Vascular access is a critical determinant of hemodialysis efficacy in patients with end-stage kidney disease (ESKD). The choice between arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs) influences long-term dialysis outcomes, with AVFs offering superior patency but higher maturation failure rates and AVGs providing immediate usability at the expense of increased complications. Recent advancements in endovascular techniques and biomaterials have introduced novel approaches to optimizing vascular access. Purpose: This review examines the latest evidence on AVF and AVG creation, focusing on factors affecting maturation, long-term patency, and emerging minimally invasive techniques, such as percutaneous AVF creation, to enhance hemodialysis access outcomes. Research Design: A systematic review of current literature, clinical guidelines, and innovations in vascular access for dialysis patients was conducted. Emphasis was placed on comparative effectiveness studies, patency and complication rates, and new endovascular approaches. Study Sample: Data were sourced from clinical trials, registry reports, and systematic reviews evaluating AVF and AVG outcomes, as well as emerging endovascular fistula technologies. Data Collection and/or Analysis: Key parameters such as patency rates, infection rates, thrombosis incidence, and maturation success were analyzed. Particular attention was given to procedural innovations, including bioengineered grafts and percutaneous fistula creation, assessing their impact on long-term dialysis access viability. Results: AVFs maintain superior long-term patency but are hindered by primary failure rates, necessitating interventions for maturation. AVGs, while more prone to infection and thrombosis, offer a viable alternative when native vessels are unsuitable. Endovascular AVF creation has demonstrated high technical success and promising long-term outcomes, reducing the need for traditional surgical approaches. Advances in biomaterials and adjunctive pharmacologic therapies may further improve vascular access durability. Conclusions: Individualized vascular access planning remains essential to optimizing hemodialysis outcomes. The evolution of minimally invasive techniques, coupled with improved patient selection criteria and emerging biomaterials, offers new opportunities for enhancing dialysis access longevity. Future research should focus on refining endovascular approaches and integrating novel technologies to minimize complications and improve access patency.

Factors associated with early and late losses of primary patency following drug-coated balloon for dysfunctional arteriovenous fistula

OBJECTIVE

This study aimed to evaluate the effectiveness of a drug-coated balloon (DCB) for the treatment of dysfunctional arteriovenous fistulas (AVFs) and to identify the risk factors associated with early and late losses of primary patency following DCB in real-world practice.

METHODS

This multicenter, retrospective study included 407 patients (72 ± 11 years, 64.1% males) with dysfunctional AVFs (juxta-anastomotic lesion location in 58.7% of cases, mean size 1.2 mm, mean length 54 mm) who underwent DCB for the first time for the treatment of dysfunctional AVF. The primary outcome measure was the loss of primary patency after DCB. The secondary outcome measures were the factors associated with early (<90 days) and late (⩾90 days) losses of primary patency after DCB.

RESULTS

The primary patency rates 6 and 12 months after DCB were 72.5% ± 2.3% and 40.1% ± 2.7%, respectively. The factors associated with the early loss of primary patency were de novo lesions (adjusted hazard ratio [HR], 7.91; [95% confidence interval (CI), 1.90-32.97]; p = 0.005), endovascular treatment (EVT) history within the previous 90 days (adjusted HR, 9.29; [95% CI, 3.09-27.92]; p < 0.001) and juxta-anastomotic stenosis (adjusted HR, 0.30; [95% CI, 0.13-0.70]; p = 0.005). The factors associated with a late loss of primary patency included EVT history within the previous 90 days (adjusted HR, 2.52; [95% CI, 1.89-3.38]; p < 0.001) and pre-dilation balloon size (adjusted HR, 1.99; [95% CI, 1.50-2.64]; p < 0.001).

CONCLUSIONS

DCB is an effective device to prolong the patency of dysfunctional AVFs in most cases. De novo lesions and their locations were associated with an early loss of primary patency, whereas the vessel preparation balloon size was associated with a late loss of primary patency. EVT history within the previous 90 days was associated with early and late losses of primary patency.

Challenges in Managing Cephalic Arch Stenosis: A Case of Stent Fracture and Lessons Learned

Cephalic arch stenosis (CAS) is a common cause of vascular access dysfunction in patients undergoing hemodialysis. This report describes a case of recurrent stent fractures and restenosis following endovascular treatment for CAS. A 34-year-old man with diabetic nephropathy and chronic hemodialysis underwent multiple stent placements for CAS. Complications, including stent entanglement during balloon angioplasty and stent fracture due to the cephalic arch's anatomical characteristics, necessitated surgical intervention. This case highlights two critical considerations: the unsuitability of balloon-expandable stents for CAS, as they lack resilience to deformation caused by shoulder movements, and the importance of selecting appropriate balloons to minimize stent damage. The unique anatomical characteristics of the cephalic arch increase the risk of stent bending and fracture, emphasizing the need for careful device selection. This case increases the awareness of stent placement for CAS.

Collapse of a cephalic arch stent: An atypical complication of hemodialysis vascular access

Access dysfunction is a significant contributor to morbidity in hemodialysis patients. The cephalic arch is a common location of vascular stenosis, with a considerable risk of relapse. While covered stents demonstrated a higher patency rate when compared to percutaneous transluminal angioplasty, their placement has some issues. Stent collapse and guttering are well-documented in arteries but not in arteriovenous fistulas. This report describes an unusual case of a cephalic arch stent collapsing 1 month after its positioning, as evidenced by access dysfunction.

Management of cephalic arch stenosis in hemodialysis access: Updated systematic review and meta-analysis

INTRODUCTION

Cephalic arch stenosis (CAS) is often recurrent, resistant to treatment and the intervention outcome is not well validated so far. We purposed to assess the clinical outcomes of CAS treatment in patients with hemodialysis access.

METHODS

Electronic bibliographic sources were searched up to December 4 2023 to identify studies reported outcome after treating CAS. Direct and indirect evidence was combined to compare odds ratios (OR) and surfaces under the cumulative ranking curves across the different treatment modalities through meta-analysis and network meta-analyses (NMA). This systematic review was conducted in accordance with the PRISMA-P. The review is registered in PROSPERO (CRD42022296513).

RESULTS

Four randomized controlled trials (RCTs) and 15 non-RCTs were included in the analysis. The study population differed in fistula type, restenosis or thrombosis, and significant heterogeneity was observed among the publications. The risk of bias was low to serious. Meta-analysis found no significant difference between DCB and PTA in primary patency at 6 and 12 months (OR 1.16 and 0.60, respectively; low certainty of evidence). Favorable result with STG compared to stent or PTA at 3, 6, and 12 month was observed (OR 4.28, 5.13, and 13.12, and 4.28, 5.13, 13.12, respectively; low certainty of evidence). Regarding primary patency, the treatment rankings, from highest to lowest, were STG (92.7%), transposition (76.0%), stent (67.5%), DCB (46.3%), and PTA (64.5%) at 12 months.

CONCLUSION

Despite data limitations, the low-quality evidence suggests that STG may merit consideration as a primary treatment option when all alternatives are applicable, given their potential for better primary patency and higher treatment ranking.

Health-care Professionals' Perspectives on Ultrasound Evaluation of Arteriovenous Hemodialysis Fistula: A Narrative Review

Arteriovenous hemodialysis fistulas play a critical role in maintaining life on hemodialysis. With the growing use of Doppler ultrasound in nephrology, its utility has expanded to improve the prognosis and quality of life of patients receiving hemodialysis. On a fistula care team, different health-care professionals, including nephrologists, dialysis technicians, and surgeons or vascular interventionalists, require different information. This review article comprehensively explains how Doppler ultrasound evaluation can be beneficial in the management of arteriovenous fistulas from different perspectives of health-care professionals. The article also introduces the pathophysiology of arteriovenous fistula disease and provides a thorough introduction to the use of Doppler ultrasound for the evaluation of arteriovenous fistulas and their associated diseases, addressing the need for a comprehensive understanding among ultrasound practitioners.

Long-Term Efficacy of Ultrasound-Guided Percutaneous Transluminal Angioplasty for Arteriovenous Fistula Outflow Stenosis Caused by Venous Valve

Introduction

Venous valve-related stenosis (VVRS) is an uncommon type of failure of arteriovenous fistula among patients with end-stage renal disease (ESRD). There is a paucity of data on the long-term efficacy of ultrasound-guided percutaneous transluminal angioplasty (PTA) for VVRS.

Methods

ESRD patients who underwent PTA because of VVRS between January 2017 and December 2021 at the First Affiliated Hospital of Chongqing Medical University were enrolled. Patients were classified into three cohorts (cohort1, VVRS located within 3 cm of the vein adjacent to the anastomosis; cohort2, VVRS located over 3 cm away from the anastomosis; cohort3, multiple stenoses). The patency rates were assessed by the Kaplan-Meier method and compared using the log-rank test. Univariate and multivariate Cox analyses were performed to identify the risk factors.

Results

A total of 292 patients were enrolled, including 125 (42.8%), 111 (38.0%), and 56 (19.2%) patients in cohort1, cohort2, and cohort3, respectively. The median follow-up was 34.8 months. The 6-month, 1-year, 2-year, and 3-year primary patency rates were 86.0%, 69.4%, 47.5%, and 35.3%, respectively. The secondary patency rates were 94.5%, 89.4%, 75.5%, and 65.3%, respectively. Cohort1 showed a relatively better primary patency compared to cohort2 and cohort3. The secondary patency rates were comparable in the three cohorts. Duration of dialysis and VVRS type were potential factors associated with primary patency.

Conclusions

This study showed acceptable long-term primary and secondary patency rates after PTA for VVRS in ESRD patients, especially for those with VVRS located within 3 cm of the vein adjacent to the anastomosis.

Study protocol for a Prospective, Randomized controlled trial of stEnt graft and Drug-coated bAlloon Treatment for cephalic arch stenOsis in dysfunctional arteRio-venous fistulas (PREDATOR)

BACKGROUND

Treatment of cephalic arch stenosis (CAS) is associated with high risk of failure and complications. Although stent-graft (SG) placement has improved patency rates, stent edge restenosis has been raised as a potential limiting factor for SG usage in CAS. This study aims to evaluate the safety and efficacy of combining stent graft placement with paclitaxel-coated balloon (PCB) angioplasty versus PCB alone in the treatment of CAS.

METHODS

This is an investigator-initiated, prospective, international, multicenter, open-label, randomized control clinical trial that plans to recruit 80 patients, who require fistuloplasty from dysfunctional arteriovenous fistula (AVF) from CAS. Eligible participants are randomly assigned to receive treatment with SG and PCB or PCB alone in a 1:1 ratio post-angioplasty (n = 40 in each arm). Randomization is stratified by de novo or recurrent lesion, and the participants are followed up for 1 year. The primary endpoints of the study are target lesion primary patency (TLPP) and access circuit primary patency (ACPP) rates at 6-months. The secondary endpoints are TLPP and ACPP at 3- and 12-month; target lesion and access circuit assisted primary and secondary patency rates at 3, 6, and 12-months and the total number of interventions; complication rate; and cost-effectiveness.

DISCUSSION

This study will evaluate the clinical efficacy and safety of combination SG and PCB implantation compared to PCB alone in the treatment of CAS for hemodialysis patients.

Hemodialysis Access: US for Preprocedural Mapping and Evaluation of Maturity and Access Dysfunction

Patients with kidney failure require kidney replacement therapy. While renal transplantation remains the treatment of choice for kidney failure, renal replacement therapy with hemodialysis may be required owing to the limited availability and length of time patients may wait for allografts or for patients ineligible for transplant owing to advanced age or comorbidities. The ideal hemodialysis access should provide complication-free dialysis by creating a direct connection between an artery and vein with adequate blood flow that can be reliably and easily accessed percutaneously several times a week. Surgical arteriovenous fistulas and grafts are commonly created for hemodialysis access, with newer techniques that involve the use of minimally invasive endovascular approaches. The emphasis on proactive planning for the placement, protection, and preservation of the next vascular access before the current one fails has increased the use of US for preoperative mapping and monitoring of complications for potential interventions. Preoperative US of the extremity vasculature helps assess anatomic suitability before vascular access creation, increasing the rates of successful maturation. A US mapping protocol ensures reliable measurements and clear communication of anatomic variants that may alter surgical planning. Postoperative imaging helps assess fistula maturation before cannulation for dialysis and evaluates for early and late complications associated with arteriovenous access. Clinical and US findings can suggest developing stenosis that may progress to thrombosis and loss of access function, which can be treated with percutaneous vascular interventions to preserve access patency. Vascular access steal, aneurysms and pseudoaneurysms, and fluid collections are other complications amenable to US evaluation. ©RSNA, 2023 Supplemental material is available for this article. Test Your Knowledge questions for this article are available through the Online Learning Center.

Contemporary review of management techniques for cephalic arch stenosis in hemodialysis

The type of hemodialysis access and its preservation impact the quality of life and survival of patients undergoing hemodialysis. Vascular access complications are among the top causes of morbidity, hospitalization, and catheter use, with significant economic burden. Poor maturation and stenosis continue to be key impediments to upper arm arteriovenous fistula feasibility. Cephalic arch is a common location for vascular access dysfunction due to its distinctive anatomy, complex valves, and biochemical alterations attributable to renal failure. Understanding cephalic arch stenosis is critical due to its high prevalence and treatment failure. The appropriate management option is highly debatable and mostly dependent on patient characteristics and interventionist's preference. Current options include, percutaneous transluminal balloon angioplasty, stent grafts, bare metal stents, cutting balloon angioplasty, endovascular banding, and surgical procedures. This article discusses the etiologies of cephalic arch stenosis as well as currents trends in management including endovascular and surgical options.

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

INTRODUCTION

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

METHODS

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

FINDINGS

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

DISCUSSION

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

Cephalic arch stenosis in the arteriovenous fistula: A retrospective analysis of predisposing factors

BACKGROUND

Cephalic Arch Stenosis (CAS) is a frequently observed complication in brachiocephalic and radiocephalic arteriovenous fistulae (AVF) associated with high morbidity and healthcare expenditure. The predisposing factors and preventative strategies for CAS remain unclear. Our aim was to examine predisposing factors for CAS development in the AVF.

METHODS

A retrospective case-control study was performed at Gold University Coast Hospital on patients with AVFs created from 2009 to 2018 with ⩾18 months follow-up. CAS was defined as a >50% narrowing on angiographic assessment with clinically significant symptoms (dialysis dysfunction, arm swelling, prolonged bleeding after access).

RESULTS

About 187 patients with AVF were included in the analysis (36 brachiocephalic, 151 radiocephalic). CAS developed in 22 of 36 (61%) of brachiocephalic AVF and 9 of 151 (6%) of radiocephalic AVFs. Brachiocephalic AVF were ⩾12 times more likely to develop CAS than radiocephalic AVF (Hazard Ratio (HR) 12.7, 95% CI [5.6-28.3], p < 0.001). Each 1 mL/min increase in flow rate through the AVF, correlated with a 0.07% increase in the probability of development of CAS (HR 1.0007, 95% CI [1.0001-1.0012], p = 0.011). Brachiocephalic AVFs with CAS were associated with a higher number of interventional procedures per access-year compared with their non-CAS counterparts (Median [Interquartile range]: 1.76 [0.74, 3.97] vs 0.41 [0.27, 0.67], p = 0.003).

CONCLUSION

Brachiocephalic AVF with higher access flow rates are more likely to develop CAS and earlier than radiocephalic AVF, and in a dose dependent fashion. AVF flow rate is a major factor in CAS development within brachiocephalic AVF and has potential utility in surveillance thresholds for prophylactic blood flow reduction procedures. AVFs with CAS are associated with a greater number of interventional procedures per access-year, heralding higher patient morbidity and healthcare expenditure. Further prospective studies will help define an AVF access flow rate threshold in the implementation of prophylactic strategies for CAS.

Surgical Referral for Hemodialysis Access Maintenance

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

Arteriovenous Hemodialysis Access Stenosis Diagnosed by Duplex Doppler Ultrasonography: A Review

Arteriovenous fistula (AVF) is currently the hemodialysis access with the longest life expectations for the patients. However, even the AVF is at risk for many complications, especially the development of stenosis. The latter can not only lead to inadequate hemodialysis but also lead to AVF thrombosis. Duplex Doppler ultrasonography is a very precise method, in the hands of experienced professionals, for the diagnosis of AVF complications. In this review, we summarize the ultrasound diagnostic criteria of significant stenoses and their indication for procedural therapy.

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

Background

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

Methods

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

Results

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

Conclusions

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

Supplementary Information

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

Outcomes of endovascular treatment for stenosis occurring after cephalic vein transposition and graft interposition

OBJECTIVE

To evaluate the outcome of endovascular treatment after surgical treatment for cephalic arch stenosis in brachiocephalic fistula and to analyze the factors influencing patency.

METHODS

We conducted a retrospective review of patients undergoing cephalic transposition (CVT) or graft interposition (GIP) for cephalic arch stenosis (CAS) from January 1, 2017, to December 31, 2019. A total of 73 patients with restenosis were included in this study. Patients were classified into cephalic transposition (BCF-CVT) (n=49) and graft interposition (BCF-GIP) (n=24) groups. We calculated the postintervention primary and secondary patency of endovascular treatment by using the Kaplan-Meier analysis and analyzed variables associated with loss of postintervention patency.

RESULTS

Six-month and 12 month postintervention primary patency rates of endovascular treatment for restenosis were 56.7% and 15.6% and secondary patency rates were 89.7% and 72.1%, respectively. In BCF-CVT group, six month, and 12 month postintervention primary patency was 56.8% and 17.6% and secondary patency was 93.3% and 79.4%, respectively. In BCF-GIP group, six-month, and 12 month postintervention primary patency was 56.5% and 8.7% and secondary patency was 85.7% and 56.3%, respectively. There was no significant difference in postintervention primary patency between the two groups (p=0.79). However, BCF-CVT group demonstrated higher postintervention secondary patency (p=0.034). BCF-GIP group had a higher number of stenosis sites (p<0.01). There was no significant predictor of reduced postintervention primary patency. The only adverse variable of postintervention secondary patency was BCF-GIP (Hazard ratio 3.14; 95% CI 1.06 to 9.34, p <0.05).

CONCLUSION

Endovascular treatment is still the acceptable option for stenosis occurring after surgical treatment for CAS. CVT provides higher postintervention secondary patency than GIP.

Treatment of cephalic arch stenosis in dysfunctional arteriovenous fistulas with paclitaxel-coated versus conventional balloon angioplasty

Background

Treatment of cephalic arch stenosis (CAS) with standard plain old balloon angioplasty (POBA) in dysfunctional arteriovenous fistulas (AVF), is associated with early re-stenosis and higher failure rates compared to other lesions. Paclitaxel-coated balloons (PCB) may improve patency rates. This is a retrospective cohort study. Patients who underwent POBA or PCB for CAS over a 3-year period were included. Outcomes compared were circuit primary patency rates (patency from index procedure to next intervention), circuit primary assisted-patency rates (patency from index procedure to thrombosis), and target lesion (CAS) patency rates (stenosis > 50%) at 3, 6 and 12 months.

Results

Ninety-one patients were included. Sixty-five (71.4%) had POBA, while 26 (28.6%) had PCB angioplasty. There were 62 (68.1%) de-novo lesions. CAS was the only lesion that needed treatment in 24 (26.4%) patients. Circuit primary patency rates for POBA versus PCB groups were 76.2% vs. 60% (p = 0.21), 43.5% vs. 36% (p = 0.69) and 22% vs. 9.1% (p = 0.22) at 3, 6 and 12-months respectively. Circuit assisted-primary patency rates were 93.7% vs. 92% (p = 1.00), 87.1% vs. 80% (p = 0.51) and 76.3% vs. 81.8% (p = 0.77), whilst CAS target lesion intervention-free patency rates were 79.4% vs. 68% (p = 0.40), 51.6% vs. 52% (p = 1.00) and 33.9% vs. 22.7% (p = 0.49) at 3, 6 and 12-months respectively. Estimated mean time to target lesion intervention was 215 ± 183.2 days for POBA and 225 ± 186.6 days for PCB (p = 0.20).

Conclusion

Treatment of CAS with PCB did not improve target lesion or circuit patency rates compared to POBA.

ASDIN white paper: Management of cephalic arch stenosis endorsed by the American Society of Diagnostic and Interventional Nephrology

Brachiocephalic arteriovenous fistulas (AVF) makeup approximately one third of prevalent dialysis vascular accesses. The most common cause of malfunction with this access is cephalic arch stenosis (CAS). The accepted requirement for treatment of a venous stenosis lesion is ⩾50% stenosis associated with hemodynamically abnormalities. However, the correlation between percentage stenosis and a clinically significant decrease in access blood flow (Qa) is low. The critical parameter is the absolute minimal luminal diameter (MLD) of the lesion. This is the parameter that exerts the key restrictive effect on Qa and results in hemodynamic and functional implications for the access. CAS is the result of low wall shear stress (WSS) resulting from the effects of increased blood flow and the unique anatomical configuration of the CAS. Decrease in WSS has a linear relationship to increased blood flow velocity and neointimal hyperplasia exhibits an inverse relationship with WSS. The result is a stenotic lesion. The presence of downstream venous stenosis causes an inflow-outflow mismatch resulting in increased pressure within the access. Qa in this situation may be decreased, increased, or within a normal range. Over time, the increased intraluminal pressure can result in marked aneurysmal changes within the AVF, difficulties with cannulation and the dialysis treatment, and ultimately, increasing risk of access thrombosis. Complete characterization of the lesion both hemodynamically and anatomically should be the first step in developing a strategy for management. This requires both access flow measurement and angiographic imaging. Patients with CAS present a relatively broad spectrum as relates to both of these parameters. These data should be used to determine whether primary treatment of CAS should be directed toward the anatomical lesion (small MLD and low Qa) or the pathophysiology (large MLD and high Qa).

Ultrasound evaluation of access complications: Thrombosis, aneurysms, pseudoaneurysms and infections

Arteriovenous fistula (AVF) complications are classified based on fistula outcomes. This review aims to update colour Doppler (CD) and pulse wave Doppler (PWD) roles in managing early and late complications of the native and prosthetic AVF. Vascular access (VA) failure occurs because inflow or outflow stenosis activates Wirchow's triad inducing thrombosis. Therefore, the diagnosis of the tributary artery and outgoing vein stenosis will be the first topic considered. Post-implantation complications occur from the inability to achieve AVF maturation and dialysis suitability due to inflow/outflow stenosis. Late stenosis is usually a sequence of early defects repaired to maintain patency. Less frequently, in the mature AVF or graft, complications are acquired 'de novo'. They derive either from incorrect management of vascular access (haematoma, pseudoaneurysm, prosthesis infection) or wall pathologies (aneurysm, myxoid valve degeneration, kinking, coiling, abnormal dilation from defects of elastic structures). High-resolution transducers (10-20 MHz) allow the characterization of the wall damage, haemodynamic dysfunctions, early and late complications even if phlebography remains the gold standard for the diagnosis for its sensitivity and specificity.

Surgical repair of a special category of arteriovenous fistula outflow stenosis caused by venous valve hyperplasia

OBJECTIVE

This study evaluated a special category of arteriovenous fistula outflow stenosis caused by venous valve hyperplasia and explored the effectiveness of surgical repair in dealing with this kind of stenosis.

STUDY DESIGN

This retrospective cohort study was conducted from February 2016 to January 2020 in our center. Patients with arteriovenous fistula dysfunction, including flow rate insufficiency, venous hypertension, thrombosis, and aneurysm dilation enlargement, were selected. Stenosis lesions presenting with venous valve hyperplasia were selected after ultrasound screening. All patients underwent surgical repair and were followed up every 6 months after surgery.

RESULTS

Forty-three patients (median age, 54.5 ± 11.2 years; 65.1% men) were included. All procedures were technically successful. Based on intraoperative exploration, 56.5% were reconstructed via autologous vein patch, 17.4% of patients were reconstructed with end-to-end reconstruction after cutting the stenotic segment, 13.0% of cases simply had the valve resected, and 13.0% of cases involved a longitudinal incision and transverse suture. All patients returned to routine dialysis the following day and avoided catheter insertion. The mean follow-up time was 22.5 ± 14.0 (range, 1.3-49.8) months. The patency rates at 2 and 4 years were 92.2% and 79.0%, respectively. Valves harvested from patients were analyzed via Masson staining and immunohistochemical staining, indicating collagen fiber and myofibroblast hyperplasia in outflow venous valve hyperplasia (OVVH).

CONCLUSIONS

Outflow venous valve hyperplasia can lead to fistula dysfunction. Ultrasound is the main method to diagnosis OVVH. Special surgical repair can preserve valuable vascular resources and relieve stenosis, is safe and effective, and has a high patency rate.

Intracranial hemorrhage due to central venous occlusion from hemodialysis access: A case report

Central venous stenosis in hemodialysis patients rarely causes venous hypertension and intracranial hemorrhage. A 54 year-old male with right arm arteriovenous fistula was transferred to our institution in a comatose state following right parietal venous infarction. Fistulography showed right brachiocephalic vein (BCV) occlusion with reflux into the right transverse sinus and obstruction of left internal jugular vein outflow due to the styloid process. Balloon venoplasty of the right BCV occlusion failed to improve the patient's status because of the delayed diagnosis. Headaches and neurologic symptoms in hemodialysis patients can herald intracranial hypertension due to central venous occlusion and needs prompt assessment with fistulography.

Double Mesh Nitinol Stent Versus Self-expanding Stent-graft in Recurrent/Resistant Cephalic Vein Arch Stenoses in Dialysis Fistulae: A Comparative Study

PURPOSE

To compare the double mesh nitinol stent (DNS) versus the self-expanding stent-graft (SES) in recurrent/resistant cephalic vein arch stenosis in dialysis fistulae.

MATERIALS AND METHODS

17 cases with recurrent/resistant stenosis of the cephalic vein arch treated with a DNS were compared retrospectively with 18 cases treated with an SES. Stenting was performed either for significant recoil post-angioplasty with high-pressure balloons or in recurrent stenoses. Patients were followed up with Doppler ultrasound in our vascular access surveillance programme. Primary and assisted primary patency rates at 3, 6 and 12 months were estimated by Kaplan-Meier analysis.

RESULTS

Both stents showed 100% technical success immediately post-stenting, defined as residual stenosis < 30%. 3, 6 and 12 month primary patency of the DNS was 82.4%, 69.7% and 28.1% versus 88.9%, 77.8% and 72.2% for the SES. The DNS had a mean primary patency of 242.4 days compared to 896.3 days for the SES (p = 0.021). 12 month assisted primary patency was 88.2% (DNS) and 100% (SES). The DNS had a mean assisted primary patency of 812 days compared to 1390.3 days for the SES, though this did not reach statistical significance. No stent fractures were identified at 2 years in either group.

CONCLUSION

Both stents had 100% technical success with no stent fractures. SES showed statistically significant higher primary patency. Assisted primary patency was also higher, though this did not reach statistical significance.

Peripherally Inserted Central Venous Catheter for Pediatric and Young Adult Patients With Hematologic and Malignant Diseases

BACKGROUND

Long-term venous access is essential when treating malignant diseases. As an alternative to conventional central venous catheters, peripherally inserted central venous catheter (PICC) are now widely used. The aim of this study is to evaluate the safety, efficacy, and reliability of PICCs in comparison with previous reports, and to describe significant complications associated with their use.

PATIENTS AND METHODS

From June 2009 to November 2017, PICCs were inserted 258 times in a total of 160 pediatric and young adult patients at our institution. We retrospectively evaluated our data regarding catheter life, a note of caution during insertion, reasons for removal, infection, and other notable complications.

RESULTS

The 258 PICCs were placed for a total of 30,901 catheter-days with a median catheter life of 102 days ranging from 2 to 471 days. The most suitable vein for the insertion was a basilic vein. The insertion depth from the cubital fossa to the point of the lower third superior vena cava was found to have a strong correlation with body surface area. Suspected catheter infection requiring catheter removal was observed 30 times (0.97/1000 catheter-days) and catheter-related bloodstream infection was observed 2 times (0.06/1000 catheter-days). All the responsible pathogens were Staphylococcus epidermidis. As notable complications, fibrin sheath formation were seen in 4 patients and catheter tip migration to the thorax in 1 patient.

CONCLUSIONS

Our data suggest that PICC is safe and effective in pediatric and young adult patients receiving long-term treatment. However, clinicians should be aware of the possible complications during PICC use.

Undersized stent graft for treatment of cephalic arch stenosis in arteriovenous hemodialysis access

Cephalic arch stenosis (CAS) is a common cause of AV dialysis access failure and is notoriously difficult to treat with conventional venoplasty. Although stent graft (SG) placement has improved patency rate, they are prone to stent failure caused by edge stenosis. We investigate the effect of SG diameter relative to cephalic vein on patency rate among hemodialysis patients with dysfunctional arteriovenous access caused by CAS. We identified 22 patients with recalcitrant cephalic arch stenosis or post-venoplasty vessel rupture and received SG placement. Patients were divided into two groups based on the stent-to-vessel diameter (S/V) ratio: undersized group, < 1; and apposed group, 1–1.2. Outcomes were assessed through follow-up angiography. S/V ratio was significant smaller in the undersized patient group (p < 0.001). Placement of undersized SG demonstrated higher primary stent (p = 0.001) and access patency rates (p = 0.021) and a reduced number of post-treatment reinterventions per access year (p = 0.021). A decreased number of lateral edge stenosis was noted in undersized SG (p = 0.005). Increased S/V ratio was significantly associated with lateral edge stenosis (OR = 5.19; p = 0.027). Undersized SG is associated with higher primary stent and access patency rate, and decreased number of post-SG interventions, and are suggested in the treatment of cephalic arch stenosis.

Safety and Efficacy of the Percutaneous Manual Aspiration Thrombectomy Technique to Treat Thrombotic Occlusion of Native Arteriovenous Fistulas for Hemodialysis

목적

대상과 방법

결과

결론

Cubital vein transposition for a distal radiocephalic fistula complicated by outflow obstruction

Introduction:

Outflow stenosis is a frequent complication of vascular access for hemodialysis. It may cause increased pressure within the angioaccess along with reduced blood flow. Elective treatment is percutaneous transluminal angioplasty; however, when a long occlusion (>2 cm) occurs, success and mid-term patency of endovascular treatment are uncertain. We describe a case series of patients with long occlusion of elbow outflow complicating an otherwise excellent forearm arteriovenous fistula, treated by a bypass across the elbow through cubital vein transposition.

Patients and methods:

Six consecutive patients have been treated between 2015 and 2017; all were referred because of either low flow, increased venous pressure, excessive bleeding time, or recirculation and were examined by duplex ultrasound. A total of 83% of patients showed associated thrombosis within the access. All procedures were performed under loco-regional anesthesia and preventive hemostasis. Surgical thrombectomy was also performed when needed.

Results:

Immediate success was obtained in all but two patients converted in veno-venous polytetrafluoroethylene bypass. Post-operative blood flow increased from 316 to 878 mL/min. All patients were dialyzed through the forearm access immediately the day after surgery, without the need for central vein catheter. Overall, 75% of patients needed a percutaneous transluminal angioplasty of the veno-venous anastomosis within 6 months. Primary and secondary patency at 12 and 24 months were 25%–0% and 100%–100%, respectively.

Conclusion:

Outflow reconstruction through the elbow bypass by cubital vein transposition is a valuable resource to rescue radiocephalic arteriovenous fistula complicated by outflow obstruction, avoiding the use of an interim central vein catheter. Endovascular treatment is vital to maintain functional patency in the mid- and long term.

Helical stent (SUPERA™) and drug-coated balloon (Passeo-18 Lux™) for recurrent cephalic arch stenosis: Rationale and design of arch V SUPERA-LUX Study

BACKGROUND

The treatment options for cephalic arch stenosis are limited and standard of care remains at crossroads - none are ideal and there is currently no gold standard. Endovascular techniques are now the preferred primary therapeutic option because they are minimally invasive and better tolerated by haemodialysis patients who have multiple comorbidities. However, conventional plain old balloon angioplasty, bare metal stenting and stent grafts all have their limitations. The aim of this trial is to evaluate whether the helical SUPERA™ stent (Abbott Vascular, Santa Clara, CA, USA), which has a higher degree of flexibility and resistance to compressive forces compared to traditionally laser-cut nitinol stents, combined with a drug-coated balloon (Biotronik Passeo-18 Lux™) to minimize the neointimal hyperplasia effect, can improve patency and reduce reintervention rates.

METHODS AND RESULTS

Arch V SUPERA-LUX is a pilot investigator-initiated single-centre, single-arm prospective study. Twenty patients with a brachiocephalic fistula within 6 months of initial plain old balloon angioplasty for significant cephalic arch stenosis will be recruited for treatment with SUPERA and drug-coated balloon. The primary objectives are immediate angiographic and procedural success, primary patency and functional fistula at 1 week, 8 weeks, 6 and 12 months. The results from eight patients treated prospectively as proof of concept have shown primary patency of 83.3% at 1 year with 100% technical and procedural success rates. Enrolment for the Arch V SUPERA-LUX study is expected to be completed at the end of 2019.

CONCLUSION

The Arch V SUPERA-LUX study is the first trial to evaluate whether SUPERA stent implantation and drug-coated balloon use can provide superior protection against restenosis compared to traditional angioplasty, bare metal stents and stent grafts in recurrent cephalic arch stenosis. Initial pilot results are encouraging but longer follow-up is required to truly test this technique.

TRIAL REGISTRATION

This study is registered on ClinicalTrials.gov NCT03891693.

Restoration of wall shear stress in the cephalic vein during extreme hemodynamics

The surgical creation of an artery-vein connection via a Brachicephalic fistula (BCF) in patients with end stage renal disease (ESRD) provides a unique opportunity to study blood vessel response mechanisms to extreme hemodynamic conditions in relatively short timeframes. After BCF creation, the flow rate in the vein increases by an order of magnitude leading to separated flows and corresponding abnormally low, or negative, wall shear stress (WSS) in the curved arch segment of the cephalic vein. Locations of abnormally low WSS are shown to correlate with development of neointimal hyperplasia (NH) and subsequent stenosis. It is found that the stenosis, prior to a surgical intervention, restores the normal physiological WSS in the vein. As a result, this investigation provides evidence that the adaptation principle, known to apply in the arterial system, is also valid in the venous system. A novel graphical method is developed that combines clinical and computational data to assist in interpreting these physiological mechanisms including adaptation that lead to changes in vein geometry over time.

Cephalic Arch Stenosis: Location of Stenosis in Indian Hemodialysis Patients

The cephalic vein is formed over the "anatomical snuff box" and joins the axillary vein just below the clavicular level. The definition of cephalic arch is varied. In the radiology literature, it is defined as the central perpendicular portion of the cephalic vein as it traverses the deltopectoral groove and joins the axillary vein. The possible etiologies of cephalic arch stenosis are numerous. This study aimed to identify patients with cephalic arch stenosis and to discern the domain site of stenosis. This is a retrospective case series of patients who had an arteriovenous fistula with dysfunction of access and ipsilateral upper-limb edema. The clinical features of the access dysfunction were strong pulse due to increased pressure, weak thrill due to poor proximal flow, high static pressure, or decreased dialysis efficiency. All these 25 patients underwent computed tomography (CT) angiogram. The CT angiographic findings revealed cephalic arch stenosis and stenosis in 13 patients (52%). domain IV was slightly more affected than other domains of cephalic arch.

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.

Prevalence of Central Vein Stenosis in Patients Referred for Vein Mapping

BACKGROUND AND OBJECTIVES

Central vein stenosis is considered to be common in patients on hemodialysis but its exact prevalence is not known. In this study, we report the prevalence of central vein stenosis in patients with CKD referred for vein mapping.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a retrospective study of adult patients who had bilateral upper extremity venographic vein mapping from September 1, 2011 to December 31, 2015. Patients with and without stenosis were compared for differences in clinical or demographic characteristics. Multiple logistic regression was used to identify independent associations between patient characteristics and central vein stenosis.

RESULTS

There were 525 patients who underwent venographic vein mapping during the study period, 27% of whom were referred before initiation of hemodialysis. The mean age (±SD) and body mass index were 59 (±15) years and 28 (±7), respectively. Women accounted for 45% of patients; 82% were black. The prevalence of central vein stenosis was 10% (95% confidence interval [95% CI], 8% to 13%) for the whole group, and 13% (95% CI, 10% to 17%) among patients with tunneled central venous dialysis catheters. Current use of tunneled hemodialysis catheters (odds ratio [OR], 14.5; 95% CI, 3.25 to 65.1), presence of cardiac rhythm devices (OR, 5.07; 95% CI, 1.82 to 14.11), previous history of fistula or graft (OR, 3.28; 95% CI, 1.58 to 6.7), and history of previous kidney transplant (OR, 18; 95% CI, 4.7 to 68.8) were independently associated with central vein stenosis.

CONCLUSIONS

In this population, the prevalence of central vein stenosis was 10% and was clustered among those with tunneled hemodialysis catheters, cardiac rhythm device, and previous history of dialysis access or transplant.

Surgical Treatment of Cephalic Arch Problems in Arteriovenous Fistulas: A Center Experience

BACKGROUND

Cephalic arch problems, mainly stenosis, are a common cause of arteriovenous fistulas (AVFs) failure, and the most effective treatment is yet to be clearly defined. Restenosis usually occurs soon, and multiple interventions become necessary to maintain patency and functionality. The authors present the experience of their center with cephalic vein transposition in a group of patients with different problems involving the cephalic arch.

METHODS

After consultation of the medical records, an observational retrospective analysis was performed to evaluate the outcomes of surgical treatment in cephalic arch problems of AVFs treated at the author's center between January 2013 and December 2015. The considered outcomes were endovascular intervention rate, thrombosis rate, and primary and secondary patencies.

RESULTS

Seven patients were treated by venovenostomy with transposition of the cephalic arch and anastomosis to the axillary vein. The average patient age was 72 years (59-81), and most patients were female (71%) and diabetic (71%). All accesses were brachiocephalic AVFs with a mean duration of 4 years (1-7). The underlying problems were intrinsic cephalic arch stenosis (n = 5), entrapment of the cephalic vein (n = 1), and clinically significant vein tortuosity at the cephalic arch (n = 1). These last 2 problems conducted to a surgical approach as first-line therapy instead of endovascular intervention, the initial treatment in the other 5 cases (all with high-pressure balloons, with cutting balloon in one case). Previous thrombotic episodes were reported in 57% of the patients. The mean access flow before surgical intervention was 425 mL/min (350-1,500). No complications related with the surgical procedure were reported. One patient underwent surgical thrombectomy after AVF thrombosis, followed by transposition of the vein. In another case, a simultaneous flow reduction was performed. Most of the patients on dialysis (5/6) used the AVF after surgery. After a mean follow-up period of 9 months (1-22), surgical treatment was associated with a reduction in endovascular intervention rate (1.9 interventions per patient-year presurgery versus 0.4 postsurgery; P < 0.05) and thrombosis rate (0.93 thrombotic episodes per patient-year presurgery versus 0.17 postsurgery; P < 0.05). The problems leading to endovascular reintervention were as follows: new venous anastomosis stenosis (57%), axillary vein stenosis (29%), and swing-point stenosis (14%). Primary and secondary patencies at 6 months were 57% and 71%, respectively.

CONCLUSIONS

In this group of patients with cephalic arch problems and multiple previous procedures, surgical treatment was associated with a reduction in endovascular intervention and thrombosis rate but did not avoid reintervention. Facing the complexity and multiplicity of the cephalic arch complications, treatment should be individually decided.

Cephalic vein transposition is a durable approach to managing cephalic arch stenosis

INTRODUCTION

The proximal cephalic vein that enters the axillary vein (cephalic arch) is a common site of stenosis in patients with upper extremity arteriovenous fistulas for hemodialysis (HD). In this study, we present the outcomes of a series of cephalic vein transposition, to determine its utility in the setting of refractory arch stenosis.

METHODS

We conducted a retrospective review of patients undergoing cephalic vein transposition to manage refractory cephalic arch stenosis from January 1, 2008 to August 31, 2015. Demographics, past medical history, access history of the patients as well as procedural details of the surgery to the stenotic segment, patency of the access, and the need for subsequent interventions were recorded.

RESULTS

Twenty-three patients underwent a cephalic vein transposition during the study period. The patients undergoing cephalic transposition had their current access for an average of 3.0 ± 2.6 years and had an average of 2.3 ± 0.9 interventions on the access prior to the surgery. Complications from the surgery were uncommon (8.7%) and no patient required a temporary tunneled dialysis catheter. The re-intervention rate was 0.2 ± 0.2 interventions per patient per year. At two years, primary patency was 70.9% and cumulative patency was 94.7% for the patients with cephalic transposition.

CONCLUSIONS

Cephalic vein transposition is safe and effective treatment for cephalic arch stenosis without interrupting utilization of the access. The surgical approach to stenosis of the proximal cephalic vein is effective, requires minimal re-interventions, and should be considered for isolated, refractory cephalic arch stenosis in mature arteriovenous fistulas.

Use of the Viabahn stent graft for the treatment of recurrent cephalic arch stenosis in hemodialysis accesses

OBJECTIVE

Cephalic arch stenosis (CAS) is a frequent and challenging failure mode of brachiocephalic fistulas. Natural tortuosity of the cephalic arch requires special consideration in selecting a treatment modality. Typical percutaneous angioplasty and bare-metal stent (BMS) treatments provide a short-term treatment solution for CAS without a durable effect. This study assessed Viabahn (W. L. Gore & Associates, Flagstaff, Ariz) stent grafts (SGs) as a first-line percutaneous option to provide a durable treatment for CAS.

METHODS

SG data were collected at a free-standing physician office between July 10, 2009, and January 26, 2011. A single-arm, prospective, observational study was conducted of 50 consecutive CAS patients treated with angioplasty followed by deployment of Viabahn SGs. Outcomes included target lesion primary patency and reintervention rates as well as secondary access patency. Results were compared with historic cohorts of percutaneous balloon angioplasty (N = 50) and angioplasty followed by BMS deployment (N = 50). The cohorts were treated between May 5, 2005, and May 20, 2010, and assessed in chronologic order.

RESULTS

The SG cohort target lesion primary patency reported at 3, 6, and 12 months was 90% ± 7%, 74% ± 12%, and 60% ± 14% (±95% confidence interval), respectively. Compared with historic cohorts, the SG cohort demonstrated statistically superior target lesion primary patency (P < .001), with a reduced reintervention rate per access-year (P < .001). Secondary access patency was statistically superior compared with the percutaneous balloon angioplasty cohort (P = .034) but not statistically different from the BMS cohort when assessed during a 2.5-year period. The secondary access patency for the SG cohort at 5 years was 80% ± 15%.

CONCLUSIONS

In treatment of a CAS, the Viabahn SG study group demonstrated superior target lesion primary patency and required fewer subsequent interventions compared with historic cohorts treated with angioplasty or angioplasty followed by BMS placement. Given the significant improvement in target lesion primary patency, future studies should challenge Viabahn SGs as a primary percutaneous treatment modality vs durable surgical alternatives.

A rare anatomic variant of a single-conduit supraclavicular cephalic arch draining into the external jugular vein presenting with recurrent arteriovenous fistula stenosis in a hemodialysis patient

The cephalic arch is a common location of stenosis, especially in brachiocephalic fistulas. The cephalic arch has a number of anatomic variations. Cephalic arch stenoses are often resistant and have poor primary patency. Here we describe an unusual case of a hemodialysis patient with a single-conduit supraclavicular cephalic arch draining into the external jugular vein presenting with recurrent cephalic arch stenoses and external jugular vein stenosis. In our view, extrinsic compression by the clavicle may contribute to the high rate of recurrence, the lack of complete dilation of even high-pressure balloons, and a theoretically heightened risk of rupture when cutting balloons are used.

Increased Inlet Blood Flow Velocity Predicts Low Wall Shear Stress in the Cephalic Arch of Patients with Brachiocephalic Fistula Access

Background

An autogenous arteriovenous fistula is the optimal vascular access for hemodialysis. In the case of brachiocephalic fistula, cephalic arch stenosis commonly develops leading to access failure. We have hypothesized that a contribution to fistula failure is low wall shear stress resulting from post-fistula creation hemodynamic changes that occur in the cephalic arch.

Methods

Twenty-two subjects with advanced renal failure had brachiocephalic fistulae placed. The following procedures were performed at mapping (pre-operative) and at fistula maturation (8–32 weeks post-operative): venogram, Doppler to measure venous blood flow velocity, and whole blood viscosity. Geometric and computational modeling was performed to determine wall shear stress and other geometric parameters. The relationship between hemodynamic parameters and clinical findings was examined using univariate analysis and linear regression.

Results

The percent low wall shear stress was linearly related to the increase in blood flow velocity (p < 0.01). This relationship was more significant in non-diabetic patients (p < 0.01) than diabetic patients. The change in global measures of arch curvature and asymmetry also evolve with time to maturation (p < 0.05).

Conclusions

The curvature and hemodynamic changes during fistula maturation increase the percentage of low wall shear stress regions within the cephalic arch. Low wall shear stress may contribute to subsequent neointimal hyperplasia and resultant cephalic arch stenosis. If this hypothesis remains tenable with further studies, ways of protecting the arch through control of blood flow velocity may need to be developed.

Characterization of the cephalic arch and location of stenosis

PURPOSE

The purpose of this study is to accurately characterize the cephalic arch segments into four domains and to enable more specific evaluation of cephalic arch stenosis (CAS) and determine the frequency of stenosis in each domain.

METHODS

After Institutional Review Board (IRB) approval, a retrospective chart review was done to define a population of patients receiving hemodialysis who developed CAS as apparent on clinically indicated radiologic imaging. A standardized approach was devised to categorize four domains of the cephalic arch. Domain I was defined as the peripheral portion of the arch and Domain IV was the distal portion of the cephalic vein near termination with the axillary vein. The magnitude of stenosis as measured by percentage was determined and compared in the four domains.

RESULTS

The most frequent location for stenosis was found in domain IV when compared with domains II or I (p<0.01). The magnitude of stenosis differed across all domains (p<0.001) with the least common place for CAS in domain I. Treatment of CAS included angioplasty in all, thrombectomy in eight, and stent placement in five.

CONCLUSIONS

CAS occurs most commonly in the terminal portion of the arch. Four standardized domains have been defined; future work will validate these findings and determine the best intervention for each domain.

Anatomical vascular variations and practical implications for access creation on the upper limb

BACKGROUND

A profound knowledge of vascular anatomy and an understanding of vascular access functionality with respect to possible complications are critical in selecting the site for arteriovenous anastomosis.

METHODS

Outline of vasculature variations of the upper limb with prevalence reported in literature of at least 1%, which may affect access creation, is depicted in this review.

RESULTS

Over a dozen arterial anatomical anomalies of the upper limb, the most common is "high origin" of the radial artery (12-20%). Superficial positions of brachial, ulnar and radial artery as well as accessory brachial are another possible anatomic variants (0.5-7%). The most variable venous layout on the upper arm is seen in the anatomy of the brachial vein and the basilic vein forming the axillary vein. Three types of basilic vein course on upper arm have been described.

CONCLUSIONS

The mapping technique to assess vascular variants facilitate site selection for AVF creation even in cases with previously attempted failed access (misdiagnosed vascular variant could force to secondary options). Thus, a thorough understanding and evaluation of anatomy, taking into consideration the possible vascular variations of the forearm and upper arm, are necessary in the planning of AVF creation and increase the success of AVF procedures.