Computational Fluid Dynamics (CFD) in Arteriovenous (AV) Graft Implantation Through End-to-Side Anastomosis with Varying Tube Diameters Across Different Vascular Access Locations for Dialysis Treatment.

Background/Objectives: Arteriovenous (AV) graft is a procedure for hemodialysis performed in the arm. Optimizing AV graft design is vital to enhance haemodialytic efficiency in patients with kidney disease. Despite being a standard procedure, making it work optimally is still difficult due to various graft diameters and anastomosis configurations, which have limited studies. This research aims to find the ideal AV graft tube diameter on blood flow and pressure gradients and the ideal body site for AV graft implantation and to study their angles for dialysate flow. Methods: Nine models were designed in Autodesk Fusion 360 with 40°, 50°, and 60° angles each having 2 mm, 5.1 mm, and 14.5 mm diameters, all following specific equations on continuity, momentum (Navier-Stokes Equation)), and the Reynolds Stress Model (RSM). The CFD simulation of these models was performed in ANSYS Fluent with an established parameter of 0.3 m/s inlet velocity and stiff/no-slip graft and artery wall boundary condition. Results: As a result, the design with a diameter of 14.5 mm and a 40° angle was overall the most ideal in terms of minimal wall shear stress and turbulence. Conclusions: Thus the brachiocephalic area or the forearm is calculated to be the most optimal implantation site. Additionally, varying angles do affect dialysate flow, as smaller values cause less stress.

What is the MAUDE Database Telling us about 510(k) Authorization? Evaluation of Two Generations of Endovascular Arteriovenous Fistula Devices.

BACKGROUND: In 2019, Bard Peripheral Vascular Inc (BV; now Becton, Dickinson and Company; Sparks, Maryland) received Food and Drug Administration (FDA) approval to begin marketing the WavelinQ EndoAVF System through a process known as 510(k) authorization. Such authorization relies on BV proving that the new WavelinQ EndoAVF System was of "substantial equivalence" to the WavelinQ 4F EndoAVF System. We set forth to analyze patient problems and device issues reported for the new device and determine if they were significantly different from the predicate device its 510(k) approval was based on. METHODS: FDA database Manufacturer and User Facility Device Experience was queried for all adverse report events for the WavelinQ EndoAVF System and WavelinQ 4F EndoAVF System. Data were collected on patient issues and device issues. Fisher's exact test was used. RESULTS: There were a total of 125 reports for the WavelinQ 4F EndoAVF System and 78 for the WavelinQ EndoAVF System. There was a significant increase in patient problem "hypertension" (0% vs. 5.1%; P = 0.02) for the WavelinQ EndoAVF System but a statistically significant decrease in device issue "failure to align" for the WavelinQ EndoAVF System (24.8% vs. 10.3%; P ≤ 0.01). CONCLUSIONS: There were changes in device and patient outcomes between the WavelinQ EndoAVF System and WavelinQ 4F EndoAVF System. While we noted a decrease in device problem "failure to align", there was an overall increase in patients' "hypertension" rates. This highlights the importance of the FDA Manufacturer and User Facility Device Experience reporting in ensuring that device safety is maintained when devices are approved for marketing through the 510(k) process.

Distal Adjuncts for High-Risk Lower Extremity Bypasses.

BACKGROUND: This review will discuss the use of distal adjuncts for improving graft patency in high-risk lower extremity bypasses. METHODS: Factors that contribute to the increased risk of failure in high-risk lower extremity bypasses, such as the use of nonautogenous conduits, the creation of bypasses to very distal arterial targets, and bypasses in patients with significant tibial arterial disease, will be discussed. RESULTS: The use of surgical techniques such as creating venous cuffs, venous patches, and arteriovenous fistulas have been shown to improve the patency of high-risk bypasses. CONCLUSIONS: Despite the increased risk of failure, the use of surgical adjuncts such as cuffs, patches, and arteriovenous fistulas can improve the patency rates of high-risk lower extremity bypasses.

An Implantable Magnetic Drive Mechanism for Non-Invasive Arteriovenous Conduit Blood Flow Control.

OBJECTIVE: Hemodialysis patients usually receive an arteriovenous fistula (AVF) in the arm as vascular access conduit to allow dialysis 2-3 times a week. This AVF introduces the high flow necessary for dialysis, but over time the ever-present supraphysiological flow is the leading cause of complications. This study aims to develop an implantable device able to non-invasively remove the high flow outside dialysis sessions. METHODS: The developed prototype features a magnetic ring allowing external coupling and torque transmission to non-invasively control an AVF valve. Mock-up devices were implanted into arm and sheep cadavers to test sizes and locations. The transmission torque, output force, and valve closure are measured for different representative skin thicknesses. RESULTS: The prototype was placed successfully into arm and sheep cadavers. In the prototype, a maximum output force of 78.9 ± 4.2 N, 46.7 ± 1.9 N, 25.6 ± 0.7 N, 13.5 ± 0.6 N and 6.3 ± 0.4 N could be achieved non-invasively through skin thicknesses of 1-5 mm respectively. The fistula was fully collapsible in every measurement through skin thickness up to the required 4 mm. CONCLUSION: The prototype satisfies the design requirements. It is fully implantable and allows closure and control of an AVF through non-invasive torque transmission. In vivo studies are pivotal in assessing functionality and understanding systemic effects. SIGNIFICANCE: A method is introduced to transfer large amounts of energy to a medical implant for actuation of a mechanical valve trough a closed surface. This system allows non-invasive control of an AVF to reduce complications related to the permanent high flow in conventional AVFs.

Using two-holed needles for both arterial and venous accesses to the arteriovenous fistula to improve flow during hemodialysis.

This prospective study compared methods using both arterial and venous needles with back eyes with those using only arterial needle with back eye for arteriovenous fistula cannulation. Sixty-one patients receiving hemodialysis (HD) via an arteriovenous fistula were evaluated. All patients underwent arteriovenous fistula puncture using only arterial needle with back eye in first 3 months and both arterial and venous needles with back eyes in following 3 months. Arterial and venous pressures, blood flow velocities, total blood volume cleared, and Kt/V values were compared. Mean blood flow velocity, arterial pressure, Kt/V, and cleared total blood volume values were higher and venous pressure was lower in patients who underwent cannulation using both needles with back eyes than in those with only the arterial needle with back eye. For arteriovenous fistula cannulation, using both arterial and venous needles with back eyes provides adequate HD more successfully.

A randomized controlled study of early versus standard cannulation of arteriovenous grafts in hemodialysis patients.

OBJECTIVE: Arteriovenous grafts (AVGs) are frequently needed in hemodialysis (HD) patients with unsuitable superficial veins. First cannulation of standard arteriovenous grafts (sAVGs) still require about 2 weeks after implantation. Early cannulation arteriovenous grafts (eAVGs) were suggested to overcome this shortcoming. The present randomized study proposed to compare the clinical outcomes of sAVGs and eAVGs in HD patients. METHODS: The present single-center randomized clinical study recruited 477 HD patients indicated for AVG creation. They included 236 in the sAVG group and 241 in the eAVG group. Eligible patients were simply randomized and allocated to the studied groups using 1:1 allocation ratio. Blinding was secured using the sealed envelope technique. Enrolled patients were followed up for 12 months. The primary outcome in the present study was primary, primary assisted, and secondary patency rates at 12 months. Other outcome parameters included time to first cannulation, graft complications, and mortality. RESULTS: Comparison between the studied groups regarding the primary outcomes revealed no statistically significant differences. Primary patency rate was 65.7% and 68.0% (P = .58) at 6 months and 53.8% and 56.4% (P = .57) at 12 months in the sAVG and eAVG groups, respectively. Primary assisted patency rate was 70.8% and 69.7% (P = .8) in patients with sAVG and eAVG, whereas the reported rates at 12 months were 59.3% and 61.0% (P = .71), respectively. Secondary patency rate was 78.4% and 73.9% (P = .25) at 6 months and 67.8% and 69.7% (P = .65) at 12 months in the sAVG and eAVG groups, respectively. As expected, patients in the eAVG group experienced significantly earlier cannulation when compared with patients in the sAVG group (median, 3.0 days; range, 1.0-9.0 days vs 19.0 days; range, 15.0-22.0 days; P < .001). CONCLUSIONS: Patients in the eAVG group have comparable outcomes to those in the sAVG group at 12 months with the added advantage of earlier time to first cannulation.

Percutaneous arteriovenous fistula creation with the 4F WavelinQ EndoAVF System.

BACKGROUND: Percutaneous devices for creation of native arteriovenous fistulae offer an alternative to traditional open surgical techniques. The 4F WavelinQ EndoAVF System was developed as a lower profile alternative to facilitate access through smaller vessels and minimize access site complications; The current report is the original first experience of this device, assessing outcome in 120 patients followed for 6 months. METHODS: The use of the 4F WavelinQ system in three studies, EASE (32 patients), EASE-2 (24 patients), and the EU postmarket clinical follow-up study (64 patients) was aggregated and analyzed. Patients were followed with duplex ultrasound at discharge and follow-up visits at 1, 3, and 6 months. Primary, assisted primary, and secondary patency rates were evaluated as Kaplan-Meier estimates and standard errors. Time to maturity and time to successful cannulation were defined as the mean ± standard deviation days from the procedure in patients enrolled on dialysis. RESULTS: Procedural success was achieved in 116 patients (96.7%). Primary, assisted-primary, and secondary 6-month patency rates were 71.9% ± 4.5%, 80.7% ± 4.1%, and 87.8% ± 3.3%, respectively. Time to maturity averaged 41 ± 17 days. Time to successful cannulation averaged 68 ± 51 days. Device-related serious adverse events were reported in 3 of 120 patients (2.5%) and procedure-related serious adverse events occurred in 7 of 120 patients (5.8%). Arterial or venous access complications were not reported in any of the patients. Access circuit reinterventions were performed in 23 patients (19.2%), split between those performed for EndoAVF maturation (13/120 [10.8%]) and maintenance (11/120 [9.2%]). CONCLUSIONS: Percutaneous creation of native dialysis fistulae with the 4F WavelinQ EndoAVF System is safe and effective, with favorable durability and a low rate of serious complications and reinterventions through 6-month follow-up. Use of the 4F device allows for percutaneous fistula creation between the radial artery and radial vein or the ulnar artery and ulnar vein. These findings suggest that the 4F device is a useful percutaneous alternative to open surgical AVF or endovascular AVF with larger bore devices.

Tapered and non-tapered prosthetic grafts in upper extremity dialysis access: A systematic review and meta-analysis.

OBJECTIVE: It is unclear whether tapered arteriovenous grafts (AVGs) are superior to non-tapered AVGs when it comes to preventing upper extremity ischemic steal syndrome. We aimed to evaluate the outcomes of tapered and non-tapered AVGs using systematic review and meta-analysis. METHODS: A literature search was systemically performed to identify all English publications from 1999 to 2019 that directly compared the outcomes of upper extremity tapered and non-tapered AVGs. Outcomes evaluated were the primary patency at 1-year (number of studies (n) = 4), secondary patency at 1-year (n = 3), and risk of ischemic steal (n = 5) and infection (n = 4). Effect sizes of individual studies were pooled using random-effects model, and between-study variability was assessed using the I2 statistic. RESULTS: Of 5808 studies screened, five studies involving 4397 patients have met the inclusion criteria and included in the analysis. Meta-analyses revealed no significant difference for the risk of ischemic steal syndrome (pooled odds ratio (OR) 0.92, 95% Confidence Incidence (CI) 0.29-2.91, p = 0.89, I2 = 48%) between the tapered and non-tapered upper extremity AVG. The primary patency (OR 1.33, 95% CI 0.93-1.90, p = 0.12, I2 = 10%) and secondary patency at 1-year (OR 1.49, 95% CI 0.84-2.63, p = 0.17, I2 = 13%), and rate of infection (OR 0.62, 95% CI 0.30-1.27, p = 0.19, I2 = 29%) were also similar between the tapered and non-tapered AVG. CONCLUSIONS: The risk of ischemic steal syndrome and patency rate are comparable for upper extremity tapered and non-tapered AVGs. This meta-analysis does not support the routine use of tapered graft over non-tapered graft to prevent ischemic steal syndrome in upper extremity dialysis access. However, due to small number of studies and sample sizes as well as limited stratification of outcomes based on risk factors, future studies should take such limitations into account while designing more robust protocols to elucidate this issue.

Short- to midterm results of early cannulation arteriovenous grafts (Gore® ACUSEAL) for hemodialysis: Experience with the ACUSEAL in a Japanese cohort.

BACKGROUND: In patients without suitable vasculature for autologous arteriovenous fistula, vascular access using a prosthetic graft is an option for hemodialysis. Gore® ACUSEAL Vascular graft is an early cannulation arteriovenous graft (AVG) that allows early puncture within 24 h after surgery. We aimed to report the outcomes of using this graft in patients from a single center. METHODS: This study included 113 patients who underwent surgery for a new AVG using ACUSEAL, between December 2015 and December 2017, and were followed up. The primary outcomes were primary patency, assisted-primary patency, and secondary patency. Secondary outcomes were postoperative complications such as graft infection and steal syndrome. RESULTS: Of the 113 patients, 60 were male and 53 were female. The average age was 74.4 ± 10.7 years. We could cannulate 69.1% of patients within 24 h. The average follow-up period was 20.1 ± 10.8 months. The primary patency rates after 3 months, 6 months, and 1 year were 76.2%, 60.4%, and 33.8%, respectively. The assisted-primary patency rates after 3 months, 6 months, and 1 year were 88.8%, 73.2%, and 58.9%, respectively. The secondary patency rates after 3 months, 6 months, and 1 year were 100%, 100%, and 98.8%, respectively. Fourteen patients (12.4%) developed graft infection and two patients (1.8%) developed steal syndrome. CONCLUSION: In our study, ACUSEAL showed satisfactory patency and acceptable complication rates in the short to medium term, similar to previous studies. ACUSEAL is beneficial for surgeons who are familiar with using AVG and for medical staff who control bleeding after dialysis. However, due to the large outer diameter of the graft, surgical wounds might become dehiscent, and careful designing of the subcutaneous graft route is necessary. It might be possible to reduce the rate of graft infection by planning the site and skin incision.

Multicenter European real-world utilization of VasQ anastomotic external support device for arteriovenous fistulae.

OBJECTIVE: To evaluate the outcomes of arteriovenous fistulae (AVF), created with VasQ external support device under standard clinical practice across three vascular access clinics. METHODS: This multinational, retrospective study evaluated prospectively collected clinical outcomes of both forearm and upper arm brachiocephalic AVF (BCAVF) created using the VasQ device. Fifty-one AVF patients were pooled from three different vascular access centers in Germany, Italy, and Spain. Postprocedure outcomes were assessed by flow measurement with ultrasound examination in all centers. Primary failure, usability, patency, and intervention rates during the study period were evaluated. RESULTS: Fifty-one VasQ devices were implanted during 37 forearm (36 radiocephalic and 1 ulnar-basilic AVF) and 14 BCAVF procedures. The study population comprised mostly males (73%) and Caucasians (82%), with a mean age of 62.5 years (range, 38-84 years) and mean body mass index of 29.2. One patient died owing to access-unrelated reasons, and one patient was lost to follow-up without AVF assessment after its creation. From the remaining 49, 3 patients had a follow-up of less than 4 weeks and were excluded from maturation, primary failure, and dialysis initiation analysis (because those factors could not be evaluated yet), leaving 46 patients in this evaluation. Maturation was achieved in 91% of patients. The primary failure rate was 9%. A primary patency rate of 77% was observed at 6, 12, and 18 months. The secondary patency rate was 91% at 6 months, and 85% at 12 months and 18 months. Both primary patency and secondary patency did not differ statistically when comparing forearm AVF with BCAVF (P > .25). Successful cannulation was achieved in 86% of patients (32/37) requiring dialysis with a median time from creation to cannulation of 46 days. Of those patients, the functional patency rate was 94%. Five patients underwent seven interventions to maintain or restore patency or functionality, with an overall rate of 0.248 interventions per patient-year. CONCLUSIONS: AVFs created with VasQ external support device demonstrated promising patency and functionality outcomes in multicentric real-world setting across the two most commonly used anatomic locations.

Comparison of Ellipsys Percutaneous and Proximal Forearm Gracz-Type Surgical Arteriovenous Fistulas.

RATIONALE & OBJECTIVE: Percutaneous arteriovenous fistulas (AVF) are created by establishing a proximal forearm anastomosis and offer a safe and reliable vascular access. This study compares the Ellipsys percutaneous AVF with a proximal forearm Gracz-type surgical AVF, chosen for comparison as it is constructed at the same anatomical site. STUDY DESIGN: Retrospective study of prospectively collected clinical data. SETTING & PARTICIPANTS: All vascular access procedures conducted during a 34-month period were reviewed. The study groups comprised 89 percutaneous AVFs and 69 surgical AVFs. EXPOSURE: Percutaneous or surgical AVF placement. OUTCOME: AVF patency, function, and complications. ANALYTICAL APPROACH: Patency rates for each AVF group were evaluated by competing risk survival analysis using a cumulative incidence function. Association of primary, primary assisted, and secondary patency with the AVF groups was examined by Cox proportional hazard models. RESULTS: Technical success was 100% for both groups. Average procedure times were 14 minutes for percutaneous AVFs and 74 minutes for surgical AVFs (P < 0.001). Proximal radial artery (PRA) was used in all percutaneous AVF cases. Inflow for surgical AVFs included radial (30%), ulnar (12%), and brachial (58%) arteries. Outflow veins for both groups were the cephalic and/or basilic veins. Access flow volumes, times to maturation, and overall numbers of interventions per patient-year were not significantly different. Cumulative incidence of primary patency failure at 12 months was lower for surgical AVF (47% vs 64%, P = 0.1), but secondary patency failure was not different between groups (20% vs 12%, P = 0.3). PRA surgical AVFs had similar primary patency (65% vs 64%, P = 0.8) but higher secondary patency failure rates than percutaneous AVFs at 12 months (34% vs 12%, P = 0.04). LIMITATIONS: Retrospective study with a relatively short follow-up period, and not all patients required hemodialysis at the end of study. CONCLUSIONS: Both percutaneous and surgical AVFs demonstrated high rates of technical success and secondary patency. Percutaneous AVFs required shorter procedure times. The rate of intervention was similar. When a distal radial artery AVF is not feasible, percutaneous AVF might offer an appropriate procedure for creating a safe and functional access, maintaining further proximal forearm surgical AVF creation options.

A systematic review of brachial artery ligation as a safe and feasible option in the management of arteriovenous dialysis access infection.

OBJECTIVE: Creation of good long-term arteriovenous access is essential in patients requiring hemodialysis for end-stage renal failure. However, arteriovenous grafts or fistulae can be complicated by infection that may require emergency surgery. For infections that involve the brachial artery anastomosis, or if total graft explantation is indicated, brachial artery repair or reconstruction is often required. An alternative management strategy would be brachial artery ligation (BAL). We performed a systematic review to evaluate the outcomes of BAL that has been performed for infected arteriovenous grafts or fistulae. METHODS: A thorough literature search was conducted using various electronic databases. We included articles that reported outcomes of BAL performed for infected arteriovenous grafts or fistulae. The primary outcome was the incidence of upper limb ischemia after BAL. Secondary outcomes were the need for urgent revascularization, need for upper limb amputation, and incidence of postoperative neurological deficit after BAL. RESULTS: A total of five studies with a total of 125 patients were included in our systematic review. BAL was performed for infected arteriovenous grafts or fistulae for all studies. Follow-up period ranged from 1 to 27 months. The incidence of upper limb ischemia after BAL was low. Only a single study reported three patients who developed upper limb ischemia. Two patients required urgent revascularization, and one patient required forearm amputation after proximal ligation. All studies reported clearance of infection with no recurrence. CONCLUSIONS: Distal BAL may be performed safely for patients with infected arteriovenous fistulae or grafts with low risk of upper limb ischemia, postoperative neurological deficit, and recurrent infection.

Comparison of surgical versus percutaneously created arteriovenous hemodialysis fistulas.

OBJECTIVE: The aim of the present study was to compare the results between percutaneous arteriovenous fistulas (p-AVFs) created with the Ellipsys device (Ellipsys Vascular Access System; Avenu Medical, San Juan Capistrano, Calif) and surgical arteriovenous fistulas (s-AVFs). METHODS: A single-center retrospective comparative study of the first 107 patients who had undergone p-AVF creation with the Ellipsys system from May 2017 to May 2018 with an equal number of consecutive patients who had undergone s-AVF creation in our center during the same period. The primary endpoints included the maturation and patency rates. The secondary endpoints were reintervention, risk of infection, and the incidence of steal syndrome and aneurysm formation. RESULTS: The demographic, hypertension, and diabetes data were similar for both groups. The only difference between the two groups was that more p-AVF patients had already been receiving hemodialysis (61% vs 47%; P < .05). The p-AVFs showed superior maturation rates at 6 weeks (65% vs 50%; P = .01). The primary patency rates were greater for the s-AVFs at 12 months (86% vs 61%; P < .01). However, primary patency was comparable between the two groups at 24 months (52% vs 55%; P = .48). No significant difference was found in the secondary patency rates at 12 (90% vs 91%) and 24 (88% vs 91%) months. At the 2-year follow-up point, the rate of percutaneous reintervention was similar; however, the s-AVFs had required more frequent surgical revision (36% vs 17%; P = .01). Issues with wound healing and infection were also more frequent with s-AVFs (9% vs 0.9%; P < .01). CONCLUSIONS: Fistulas created percutaneously with the Ellipsys system showed superior maturation rates and similar patency with s-AVFs created in an experienced high-volume vascular surgery practice. p-AVFs had a lower risk of wound healing issues, infection, and surgical revision. Larger, prospective, randomized multicenter studies are needed to confirm these findings.

Initial Outcomes Following Introduction of Percutaneous Arteriovenous Fistula Program with Comparison to Historical Surgically Created Fistulas.

BACKGROUND: Recently, there has been an abundance of encouraging data regarding the creation of percutaneous arteriovenous fistulas. Despite promising data regarding their clinical maturation, a paucity of data exists which provides direct comparison between percutaneously created AVFs (pAVF) and open surgically created AVFs (sAVF). This study has 2 primary objectives: First, to compare clinical outcomes of pAVFs to sAVFs, with emphasis on clinical maturation and frequency of postoperative interventions to facilitate maturation. Second, to contribute toward the evidence-based incorporation of the pAVF procedure into the hemodialysis access algorithm. METHODS: A single-center retrospective review was performed on all consecutive patients undergoing surgically created brachiocephalic arteriovenous fistula (BC-AVF, sAVF group) from January 1, 2018 to December 31, 2018 and Ellipsys-created percutaneous arteriovenous fistula (pAVF group) from January 1, 2019 to December 31, 2019. Comparative analysis between groups was performed. RESULTS: A total of 24 patients underwent Ellipsys-created pAVF with mean age of 56.7 ± 22.6 years (12 males [50%], 12 females [50%]) and 62 patients underwent surgically created BC-AVF with mean age of 62.5 ± 13.2 years (32 males [52%], 30 females [48%]). Both the pAVF and sAVF groups had comparable mean operating times (60 ± 40 vs. 56 ± 25 min, P = 0.67) and frequency of procedural technical success (23 [96%] vs. 62 [100%], P = 0.28), respectively. The pAVF group had a lower clinical maturation rate (12 [52%] vs. 54 [87%], P = 0.003) and a higher primary failure rate (9 [39%] vs. 6 [10%], P = 0.003) when compared to the sAVF group. The pAVF group had an increased overall rate of undergoing a postoperative intervention (18 [78%] vs. 13 [21%], P< 0.001), as well as an increased number of total postoperative interventions (1.1 ± 0.9 vs. 0.3 ± 0.6 interventions, P< 0.001) compared to the sAVF group. Percutaneous transluminal angioplasty of the juxta anastomotic segment was the most prevalent postoperative intervention performed in the pAVF group and occurred at a significantly increased frequency when compared to the sAVF group rate (13 [57%] vs. 5 [8%], P< 0.001). CONCLUSIONS: In our single-center retrospective review, patients undergoing Ellipsys-created pAVF in the first year following introduction of percutaneous endovascular had inferior rates of clinical maturation and underwent more postoperative interventions when compared to historical patients undergoing surgically created BC-AVF. Outcome discrepancies compared to previously reported Ellipsys data demonstrate a need for further studies examining the practical translatability of the pAVF.

Single Asian Center Experience Using the Flixene™ Early Cannulation Graft for Hemodialysis Access Creation.

BACKGROUND: The aim of this study was to review the efficacy of the Flixene™ (Atrium™, Hudson, NH, USA) hemodialysis arterio-venous graft (AVG) in a multiethnic Asian cohort of patients with end-stage renal failure (ESRF). Primary outcome was graft primary patency rate and secondary end points included graft usability, time to cannulation, reinterventions required for access salvage, complications, and patient mortality. METHODS: Single-center, single-arm, multi-investigator nonrandomized retrospective study. Patients with ESRF who underwent Flixene™ graft implantation over a two-year period (January 2017 - December 2018) were included to allow at least one-year follow-up. Demographics, procedural and follow-up data were collected from the hospital electronic medical records. RESULTS: About 48 patients (49 AVG) were included. There were 24 (50%) men; mean age 63.7 (IQR 58.2-71.3) years. Technical success rate was 45/49 (91.8%); 4/49 (8.2%) AVG created did not reach cannulation. 11/49 (22.4%) and 28/49 (57.1%) achieved cannulation within 1 and 2 weeks, respectively. 6- and 12- month primary patencies were 33.5% and 19.6%, respectively. Primary-assisted patency rates were 46.6% and 29.6% at the same time intervals. Secondary patency rate was 77.6% and 63.9% at 6 and 12 months, respectively. There were 6 (12.2%) graft infections requiring explant and one-year mortality was 14%. CONCLUSIONS: Our experience with the Flixene™ early cannulation graft is comparable with other AVGs in terms of patency and infection rates. However, early cannulation rates are lower than in other case series.

Use of a novel immediate access dialysis graft designed to prevent needle-related complications: A first-in-man case report.

Currently, there is no vascular access that possesses all ideal qualities for hemodialysis access, but attributes particularly lacking include: ease of identification (cannulation zone), ease of access, resistance to stenosis, durable to repetitive cannulation, resistance to infection, resistance to acute needle-related injuries, and instant hemostasis. The overall value of these attributes could be appreciated in the reduction of complications (patient burden and suffering, which can also result in increased healthcare costs), and improved safety and durability. In this case report, we present a novel hemodialysis access graft that has the potential to provide the following benefits: it is designed to be self-sealing and immediately usable post implant, easy to identify, easy to access, has more durable cannulation zones, and protects from needle-related injuries. This case report describes the first-in-man use of this novel graft technology to replace a giant, thrombotic, and difficult-to-access arteriovenous fistula to provide the patient with a potentially safer and more durable access that does not require placement of a bridging dialysis catheter. This single-patient experience suggests that implantation and function of this novel graft as a hemodialysis access is feasible in a human subject with end-stage renal disease, and it suggests that the novel properties (i.e. immediate use, easy identification, easy use, cannulation zone durability, and protection from needle-related injuries) of this graft seem to function as intended.

Creating percutaneous radiocephalic arteriovenous fistulas at the wrist.

BACKGROUND: The first arteriovenous fistulas were created at the wrist more than 60 years ago. Basic surgical construction techniques remain unchanged with mobilization and repositioning of the vessels followed by a sutured anastomosis. We used the Ellipsys device to construct percutaneous radiocephalic-arteriovenous fistulas at the wrist and report the results. METHODS: Data were reviewed retrospectively for all patients who had a percutaneous radiocephalic-arteriovenous fistula created during a 6-month period. Each individual underwent ultrasound vessel mapping in addition to physical examination. When a radiocephalic-arteriovenous fistula was feasible and a communicating vein ⩾ 2 mm in diameter was noted in the distal forearm along with a radial artery ⩾ 2 mm, a percutaneous radiocephalic-arteriovenous fistula was considered and reviewed with the patient. RESULTS: Four individuals met the criteria to consider a percutaneous radiocephalic-arteriovenous fistula and all elected to have the procedure performed. Ages were 54-85 years. Three were diabetic and one was female. All percutaneous radiocephalic-arteriovenous fistulas were technically successful. Two individuals had not yet started dialysis therapy. Successful and repetitive cannulation for the two individuals with catheters was initiated at 4 and 8 weeks post procedure. The two pre-dialysis patients had physiologic arteriovenous fistula maturation (6 mm vein diameter and >500 mL/min flow) at 4 and 12 weeks. There were no procedural or late complications and none required intervention. Follow-up was 8-23 months (mean 16 months). CONCLUSION: The success of these percutaneous radiocephalic-arteriovenous fistulas suggests that use of the Ellipsys device will be applicable at the wrist in selected patients where appropriate vessel sizes and configurations are found.

Percutaneous creation of proximal radio-radial arteriovenous hemodialysis fistula before secondary brachial vein elevation.

OBJECTIVE: We evaluate the creation of a percutaneous proximal radial artery-radial vein arteriovenous fistula with Ellipsys® instead of the usual first-stage brachial artery fistula prior to a second-stage brachial vein elevation, in patients with inadequate cephalic and basilic veins. METHODS: Single center study of eight patients (six males, mean = 54 years) who underwent a two-stage brachial vein elevation procedure between May 2017 and October 2019. Inclusion criteria were life expectancy > 6 months, patent brachial and proximal radial artery (>2 mm in diameter) absent/inadequate cephalic and basilic veins, existence of a brachial vein >3 mm in diameter, and in continuity with a proximal radial vein > 2 mm in diameter. RESULTS: Technical success was 100%. Four patients required angioplasty of a juxta-anastomotic stenosis, accounting for a 6-month primary and secondary patency rates were 68% and 100%, respectively. Access flow averaged 982 mL/min (range 768-1586) at final follow-up evaluation. There were no significant adverse events related to the procedures. All fistulae were elevated at 4-12 (mean: 8) weeks post creation and were successfully cannulated with two needles after healing was completed (2-4 weeks after elevation). No patients developed hand ischemia or arm edema. CONCLUSIONS: Percutaneous creation of a proximal radial artery-radial vein fistula followed by brachial vein elevation is a safe and reliable option for autogenous access creation in patients with inadequate cephalic or basilic veins. Minimally invasive radial artery inflow and longer available length of the targeted brachial vein available for elevation are the main advantages in skilled hands.

Patency and functionality of radiocephalic arteriovenous fistulas with an external support device (VasQ™): Real-world single-center experience.

BACKGROUND: The VasQTM device was designed to improve the outcome of arteriovenous fistulae by optimizing the hemodynamics of the flow in the juxta-anastomotic region of the arteriovenous fistulae through tailored external support. The aim of the study was to evaluate the impact of the VasQ on outcome of radiocephalic arteriovenous fistulae in a real-world setting. METHODS: This was a single-center, retrospective analysis of patients with either fistula creation before or after dialysis initiation with implantation of the VasQ device during creation of end-to-side radiocephalic arteriovenous fistulae between June 2018 and May 2019. The flow rate and vein diameter were evaluated intraoperatively, at discharge within 48 h postprocedure and at a follow-up of 1, 3, 6, 9, and 12 months. RESULTS: Thirty-three VasQ devices were implanted during 33 radiocephalic arteriovenous fistula procedures. The study population comprised mostly of men, with an average age of 66 years. Mean intraoperative flow was 428 mL/min (range: 130-945). All patients were discharged with patent arteriovenous fistulae and mean fistula flow of 740 mL/min (range: 230-1300 mL/min). The primary patency was 100% and 79% at 3 and 6 months, respectively. Cumulative/secondary patency was 100% and 90% at 3 and 6 months, respectively. CONCLUSION: Data presented here suggest that the VasQ device has the potential to provide benefit to the functionality of radiocephalic arteriovenous fistulae.