Hemodialysis Access Grafts Research Articles

LONG-TERM OUTCOMES OF VASCULAR GRAFTS IN HEMODIALYSIS ACCESS RETROSPECTIVE COHORT STUDY

Fistulas and grafts are essential for dialysis in patients diagnosed with end-stage renal disease (ESRD). The durability and efficiency of vascular grafts in hemodialysis access remain critical for patient outcomes. Objective: To evaluate the patency rate, complication rate, and efficiency of vascular graft surgery in hemodialysis access among 100 patients in the Department of Vascular Surgery at CMH Rawalpindi. Methods: This retrospective cohort study was conducted at the Department of Vascular Surgery, CMH Rawalpindi, from August 2022 to May 2024. The study analyzed the records of 100 patients treated with vascular grafts for hemodialysis access. Patient and graft characteristics, patency results, graft, and patient survival, as well as complications, were recorded. Long-term results were evaluated based on follow-up data up to five years. Statistical analyses were conducted using appropriate methods to assess patency rates and complication frequencies. Results: The study included 58 male and 42 female patients aged between 25 and 75 years. The primary patency rate was 85% at one year, 70% at three years, and 55% at five years. Complications included infection in 10% of cases, thrombosis in 15%, and stenosis in 20%. Patient satisfaction was high, with 80% reporting improved quality of life post-surgery. Conclusion: Vascular grafts provide effective long-term arteriovenous (AV) access for hemodialysis, offering reasonable primary and secondary patency rates and manageable complications. Close follow-up and timely intervention are essential to maintaining graft function and patient quality of life.

Long-term results of autologous scaffold-free tissue-engineered vascular graft for hemodialysis access.

The growing size of the end stage renal disease (ESRD) population highlights the need for effective dialysis access. Exhausted native vascular access options have led to increased use of catheters and prosthetic shunts, which are both associated with high risks of access failure and infection. Emerging alternatives include tissue-engineered vascular grafts (TEVG). Here we present the endpoint results for 10 ESRD patients with the scaffold-free tissue-engineered vascular access produced from sheets of extracellular matrix produced in vitro by human cells in culture. Grafts were implanted as arteriovenous shunts in 10 ESRD patients with a complex history of access failure. Follow-up included ultrasound control of graft morphology and function, dialysis efficiency, access failure, intervention rate, as well as immunohistochemical analysis of graft structure. One patient died of unrelated causes and three shunts failed to become useable access grafts during the 3-month maturation phase. The 12-month primary and secondary patency for the other six shunts was 86%. Survival of six shunts functioning as the vascular access was 22 ± 12 months with longest primary patency of 38.6 months. The dialysis event rate of 3.34 per patient-year decreased significantly with the use of this TEVG to 0.67. This living autologous tissue-engineered vascular graft seems to be an alternative to synthetic vascular access options, exhibiting advantages of native arteriovenous fistula.

Effect of Active Smoking on Outcomes of Arteriovenous Fistulas and Grafts for Hemodialysis Access

In the present study, we evaluated the effect of active smoking on the outcomes of arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs) for hemodialysis access in a large population-based cohort of patients.

Comparison of Bovine Artery and Polytetrafluoroethylene Grafts for Hemodialysis Access

A surgically created autogenous arteriovenous fistula (AVF) has been the reference standard for dialysis access. However, for patients who are not candidates for AVF, arteriovenous grafts using various conduits have widely been used. In the present study, we have reported the outcomes of bovine carotid artery (BCA) grafts for dialysis access at a single institution and compared these results to those for polytetrafluoroethylene (PTFE) grafts.

Prospective, Multicenter Clinical Study of the Covera Vascular Covered Stent in the Treatment of Stenosis at the Graft-Vein Anastomosis of Dysfunctional Hemodialysis Access Grafts

PurposeTo study the use of the self-expanding Covera covered stent for the treatment of stenotic lesions at the venous anastomosis of hemodialysis arteriovenous grafts (AVGs). Materials and MethodsA total of 110 patients with AVG venous anastomotic stenosis of ≥50% and access dysfunction were treated at 14 centers in the United States using percutaneous transluminal angioplasty followed by covered stent placement. The primary end points were 30-day safety and 6-month target lesion primary patency (TLPP). The secondary measures included access circuit primary patency, circuit cumulative patency, and the number of reinterventions through 24 months. ResultsFreedom from a primary safety event at 30 days was 96.4% while the 6-month TLPP rate was 70.3%. Seventy-five patients completed 24-month follow-up (68.2%). The TLPP rates were 54.2% at 365 days and 36.9% at 730 days while the access circuit primary patency rates were 16.7% at 365 days and 7.8% at 730 days (Kaplan-Meier analysis). The access circuit cumulative patency rates were 85.4% at 12 months and 73.6% at 24 months. The number of reinterventions to maintain the patency of the access circuit was 3.6 ± 3.1 at 24 months (1.6 ± 1.9 at the target lesion). ConclusionsUse of the Covera covered stent for hemodialysis graft-vein anastomotic stenosis provided a safe treatment option with a TLPP rate of 70.3% at 6 months and TLPP and cumulative access circuit patency rates of 36.9% and 73.6% at 2 years.

The impact of activated protein C resistance on the patency of arteriovenous grafts for hemodialysis access.

Vascular access is required for hemodialysis treatment. An effect of activated protein C resistance on access thrombosis rates has not yet been investigated. The aim of this study is to determine whether an activated protein C resistance is correlated with the patency of polytetrafluoroethylene arteriovenous grafts. The primary endpoint was the impact of activated protein C resistance; secondary endpoints were the influence of Factor V Leiden thrombophilia, homocysteine, ß2-glycoprotein antibodies, and other laboratory values on the assisted primary patency. Forty-three grafts in 43 patients were included. The overall mean assisted primary patency was 18.4months (±3.16 SE). Activated protein C resistance (p = 0.01) and ß2-glycoprotein antibodies (p = 0.018) had a significant influence on the assisted primary patency. The assisted primary patency for patients with low (<4) activated protein C resistance was 9.3months compared to 24.8 of those with a high (≥4) activated protein C resistance. Patients with low (≤2.6) ß2-glycoprotein antibodies presented an assisted primary patency of 31.8months whereas those with high (>2.6) ß2-glycoprotein antibodies showed 9.3months. In all patients with a pathologic activated protein C resistance, a heterozygous or homozygous Factor V Leiden thrombophilia was detected. This study identified low activated protein C resistance and high ß2-glycoprotein antibodies as risk factors for thrombosis in polytetrafluoroethylene arteriovenous grafts. A prospective study is needed to clarify if oral anticoagulation should be administered to all patients with a pathologic activated protein C resistance blood value and/or factor V Leiden mutation.

Abstract No. 68 Evaluation of the role of antiplatelet therapy in hemodialysis access graft patency following successful percutaneous thrombectomy

The purpose of this study was to understand the role of antiplatelet therapy in maintaining arteriovenous graft (AVG) patency after successful percutaneous thrombectomy. This was an IRB-approved, retrospective review of all dialysis access circuit evaluation orders placed over a 1-year period with a narrative keyword search of “declot.” A total of 152 encounters were found, 32 of which were excluded as the intervention performed was not a thrombectomy. The remaining 120 encounters were reviewed for patient demographics, details of procedure, and use of antiplatelet therapy prior to and after percutaneous thrombectomy. AVG failure was defined as re-thrombosis, graft abandonment, or surgical revision. The time to AVG failure was calculated from the date of declot to AVG failure. Technical success was defined as patency on angiography and palpable thrill at completion of the procedure. 65% (n = 78) of declots were performed on upper arm grafts, 3% forearm (n = 3), 8% leg (n = 9), 23% HeRO (n = 27), and 3% ax-ax/ax-fem (n = 3). Technical success was seen in 111 of 120 declots. Of the successful declots, 73 (65.8%) were already on antiplatelet therapy. 6 of 9 (67%) unsuccessful declots were not on antiplatelet therapy at the time of procedure. 24.3% of successful AVG declots (n = 27) were subsequently started on new or additional/increased antiplatelet therapy. Aspirin and clopidogrel were the most commonly used agents. Ticagrelor accounted for 18 of 61 cases of existing antiplatelet therapy and 5 of 27 cases of additional/increased therapy. The median time to AVG failure without prior or subsequent antiplatelet therapy was 49 days (range 1-412 days) compared to 90 days (range 1-427 days) for those previously on antiplatelets without a subsequent change in therapy. For those cases that were started on new/additional antiplatelet therapy, the median time to graft failure was 94 days (range 2-407 days). Antiplatelet therapy may provide additional patency gains for patients with AVG as evidenced by trends toward longer time to AVG failure and increased ability to successfully declot the AVG.

Patency Outcomes of Arteriovenous Fistulas and Grafts for Hemodialysis Access: A Trade-Off between Nonmaturation and Long-Term Complications.

Arteriovenous fistulas (AVFs) for hemodialysis (HD) are often associated with better outcomes than arteriovenous grafts (AVGs). We aimed to investigate vascular access (VA) outcomes and assessed if AVF nonmaturation outweighs long-term complications of AVGs. In this multicenter, retrospective cohort study in The Netherlands, 1- and 3-year primary, primary assisted, secondary, and functional patency rates were calculated, and the incidence of adverse events and procedures was assessed. Functional patency of RCAVFs, upper arm AVFs, and AVGs was compared using Cox analyses. In total, 1041 patients who received their first VA were included, of whom 863 had VAs that successfully matured. These patients were analyzed with a median follow-up of 25 months. The 1-year functional patency rates were 67%±2.0% for RCAVFs, 83%±2.0% for upper arm AVFs, and 85%±3.5% for AVGs. Three-year functional patency rates were 62%±2.0% for RCAVFs, 74%±2.0% for upper arm AVFs, and 69%±5% for AVGs. AVGs required more procedures per year (3.3 per year) of functional patency when compared with upper arm AVFs (1.8 per year). The functional patency of AVFs and AVGs is comparable, although AVGs required more interventions to maintain usability for HD. The choice of VA is a trade-off between short-term advantages, favoring AVGs, and long-term advantages, favoring AVFs. Which VA is most appropriate depends on the patient's prognosis and preferences.

Risk Factors and Outcomes of Revisions on Arteriovenous Hemodialysis Access

Arteriovenous access (AV) using either a fistula (AVF) or graft (AVG) for hemodialysis (HD) access is often complicated by poor function requiring revision. We investigated the risk factors and durability of revisions on AV access sites for patients on chronic HD. This retrospective cohort study identified all patients undergoing chronic HD for over 3 months in the Champlain NephroCare network between 2003 and 2018. Access creations, revisions, and functionality were documented. Cumulative access site durability was defined as the functional duration of AV access site despite revisions. Cox regression survival analysis was performed, with competing risks for transplants and with access sites clustered by subject. We identified 1962 eligible AV access creations in 1034 subjects, composed of 1725 (88%) AVF access. Of AV, 67% underwent at least one revision, and 13% received two or more revisions. Revisions were most commonly angioplasty (95.8%). There were 354 (26%) revisions performed to assist maturation before the access site was ever functional, of which 58 were repeated revisions. Conversely, 1011 (74%) of revisions were performed to maintain functionality after the access site had been exclusively used for dialysis, of which 473 procedures were repeated revisions. Of all AV access creation attempts, 35% were never functional without secondary procedures, and another 31% experienced primary failure within the first year. However, the 12-month secondary functional patency of AV access sites was 72%. Advanced age (odds ratio [OR], 1.14; P < .01), lower arm placement (OR, 1.43; P < .01), diabetes (OR, 1.45; P < .01) and prior ipsilateral central venous catheter (OR, 1.32; P = .02) were associated with need for secondary procedures. Revisions to assist maturation were less successful on AV grafts compared with fistulas (63% vs 77%; P = .04). Revisions to maintain functionality were less successful on AV grafts, occluded access sites, or access sites with previously low dialysis flow rates. The 12-month primary patencies after revisions to maintain functionality was 82%, 73%, and 61% after the first, second, and third revisions, respectively (P < .01). Secondary procedures on AV access sites are common and generally produce accepTable Results. Multiple factors are significantly associated with the outcomes of secondary procedures. Although repeated secondary procedures produce diminishing returns, the primary patency after a third revision remains superior to that of a new AV access site.Fig 2View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Outcomes of autogenous fistulas and prosthetic grafts for hemodialysis access in diabetic and nondiabetic patients

BackgroundThis study evaluated the effect of diabetes on outcomes of autogenous fistulas and prosthetic grafts for hemodialysis access in a large population-based cohort of patients. MethodsA retrospective cohort study was conducted of all patients who initiated hemodialysis in the United States Renal Database System (2007-2014). The χ2 test, Student t-test, Kaplan-Meier analysis, log-rank test, and multivariable logistic and Cox regression analyses were employed to evaluate maturation, interventions, patency, infection, and mortality. ResultsThe study of 381,622 patients comprised 303,307 (79.5%) autogenous fistulas and 78,315 (20.5%) prosthetic grafts placed in 231,134 (60.6%) diabetic patients and 150,488 (39.4%) nondiabetic patients. There was decrease in maturation for diabetics compared to nondiabetics who received autogenous fistulas (adjusted hazard ratio [aHR], 0.86; 95% confidence interval [CI], 0.83-0.88; P < .001) and prosthetic grafts (aHR, 0.88; 95% CI, 0.83-0.93; P < .001). Comparing diabetics vs nondiabetics, primary patency at 5 years was 19.4% vs 23.5% (P < .001) for autogenous fistulas and 9.1% vs 11.2% (P < .001) for prosthetic grafts. Primary assisted patency at 5 years was 35.2% vs 38.7% (P < .001) for autogenous fistulas and 17.2% vs 19.2% (P = .015) for prosthetic grafts. Secondary patency at 5 years was 44.8% vs 48.6% (P < .001) for autogenous fistulas and 34.1% vs 36.8% (P = .002) for prosthetic grafts. There was 5% decrease in primary patency (aHR, 0.95; 95% CI, 0.94-0.96; P < .001) for diabetics compared to nondiabetics who received autogenous fistulas. There was no difference in primary assisted and secondary patency for autogenous fistulas as well as primary, primary assisted, and secondary patency for prosthetic grafts in comparing diabetic to nondiabetic patients. There was also no significant difference in severe prosthetic graft infection between the groups (aHR, 0.99; 95% CI, 0.92-1.08; P = .90). There was a 19% increase in patient mortality for diabetic relative to nondiabetic autogenous fistula recipients (aHR, 1.19; 95% CI, 1.17-1.20; P < .001) and 12% increase for prosthetic graft recipients (aHR, 1.12; 95% CI, 1.10-1.15; P < .001). ConclusionsIn this population-based cohort of hemodialysis patients, diabetes mellitus was associated with a decrease in patient survival, access maturation, and primary fistula patency. In contrast, there was no association between diabetes and prosthetic graft patency and severe prosthetic graft infection warranting excision.

Age-related outcomes of arteriovenous grafts for hemodialysis access

BackgroundThe prevalence of end-stage renal disease spans the spectrum of age. Arteriovenous grafts are viable alternatives for hemodialysis access in patients whose anatomy precludes placement of an arteriovenous fistula. This report describes the age-related outcomes after arteriovenous graft placement in a population-based cohort. MethodsA retrospective cohort study was conducted of all patients who initiated hemodialysis in the U.S. Renal Data System (2007-2014). The χ2 test, t-test, Kaplan-Meier analysis, log-rank test, and multivariable logistic and Cox regression analyses were employed to evaluate access maturation, interventions, patency, and mortality. ResultsOf the 78,341 patients studied, 10,150 (13%) were younger than 50 years, 13,167 (16.8%) were 50 to 59 years, 19,975 (25.5%) were 60 to 69 years, 20,307 (25.9%) were 70 to 79 years, and 14,742 (18.8%) were 80+ years. There was no significant difference in access maturation time for patients in the older age categories compared to patients younger than 50 years. Primary patency at 5 years comparing <50 years vs 50 to 59 years vs 60 to 69 years vs 70 to 79 years vs 80+ years was 12% vs 12% vs 9% vs 9% vs 8% (P < .001). Primary assisted patency at 5 years was 20% vs 21% vs 18% vs 17% vs 14% (P < .001). Secondary patency at 5 years was 36% vs 39% vs 36% vs 30% vs 31% (P < .001). There was no significant difference in primary patency (adjusted hazard ratio [aHR], 1.00; 95% confidence interval [CI], 1.00-1.00; P < .001), primary assisted patency (aHR, 1.00; 95% CI, 1.00-1.00; P < .001), and secondary patency (aHR, 1.00; 95% CI, 1.00-1.00; P = .029) with increasing age. However, there was a decrease in severe prosthetic graft infection requiring graft excision (aHR, 0.99; 95% CI, 0.99-0.99; P < .001) and increase in mortality (aHR, 1.03; 95% CI, 1.03-1.03; P < .001) for the older age categories compared with the younger patients. ConclusionsIn this population-based cohort of hemodialysis patients, there was no significant association between older age and prosthetic graft maturation or patency. However, older age was associated with a decrease in severe graft infection and the expected increase in mortality.

A Long “Biotube” Vascular Graft for Hemodialysis Access: Evaluation in an Animal Model

Introduction - In patients receiving hemodialysis, autologous arteriovenous fistula (AVF) is first choice for vascular access. On the other hand, artificial vascular grafts are needed in an underlying disease or second surgery. However, they had any risk such as infectivity or low patency. In-body tissue architecture (iBTA) can prepare collagenous tubes, called Biotubes, by using a patient's body as a bioreactor. Previously, autologous Biotubes grown in patient’s subcutaneous pouches were successfully bypassed the venous stenosis region as the first-in-human study. In this study, long Biotubes were implanted as canine or goat AV hemodialysis access. Methods - Disk-like molds (1 in photos) having spiral cylinder were embedded in beagles or goats subcutaneously for 2 months. Biotubes with diameter of 4 or 5 mm and wall thickness of 1.5 mm were obtained after removing the mold harvested (2 in photos). The Biotubes were stored in an alcoholic solution at room temperature. Immediately before implantation Biotubes were immersed in a 0.6% glutaraldehyde solution for 2 min. AV shunts were prepared with allogenic Biotubes (straight shape, length 10 cm for beagles, U-shape, 50 cm for goats) between the carotid artery and jugular vein. Follow up was performed with Doppler echo and angiography. Results - Following placement of all Biotubes, continuous thrill was felt by palpation and Doppler echo showed turbulent blood flow. Angiography revealed that all three straight beagle Biotubes were patent for 6 months without any abnormal deformation in vascular shape (3 in photos). Percutaneous punctures and compression hemostasis within several minutes at every other day were possible after 1 month of implantation. All two U-shaped goat Biotubes were also patent up to 3 months until now even with the length of 50 cm (4 in photos). Conclusion - Long Biotubes successfully created an AV shunt that maintained steady blood flow, suggesting that Biotubes can have high potential clinical use as vascular access for hemodialysis.

Safety and Efficacy of Infraclavicular Arterio-arterial Chest Wall Prosthetic Loop Graft for Hemodialysis Access. A Review of 45 Patients

Introduction: Increase the need for hemodialysis (HD) due to concomitant increase incidence of nephropathic disease in association with increase in patients' life expectancy in the last three decades, makes it necessary to establish secondary or tertiary dialysis access to overcome exhausted peripheral veins and central venous occlusion.The increase of patients' life expectancy, with the limited durability of these angioaccesses, increases the demand to repeat fistula construction at different upper extremity levels (wrist, forearm, upper arm) and can ultimately result in exhaustion of autogenous AVF.(3) Methods: We conducted an analysis of prospectively collected data over a 3-year period in between December 2014 and December 2017 for 45 patients (32 men, 13 women) with ESRD who underwent infraclavicular arterio-arterial chest wall prosthetic graft procedures as a permanent vascular access for hemodialysis. After the local hospital’s ethical and scientific committee approved the study protocol, patients were enrolled at Vascular Surgery Unit, Benha University/Department of Surgery, Vascular Surgery Department, Nile Insurance Hospital & Vascular Surgery Department, Helwan University. An IAALG procedure was indicated only for patients who had no suitable superficial cephalic and basilic veins for an AVF and who belonged to one of the following indication:1.Cardiac insufficiency that was refractory to medical therapy confirmed by echocardiography based ejection fraction ≤ 40%.2.The unsuitability of large six deep veins (the subclavian, internal jugular and femoral veins). A vein was considered unsuitable when an occlusion or high-grade long stenosis (<70% in diameter, >4 cm long) of the venous outflow was detected and could not be treated by any interventions.3.Patients with at least one patent central vein that should be preserved as bailout access for an emergency central venous catheter (CVC). Results: The primary patency rates were 100%, 97.7%, 93%, 77.5% and 73.7% at 6, 9, 12, 18, and 24 months, respectively. The secondary patency was 100%, 88.7%, and 66.6% at 6, 9, and 12 months, respectively, after successful thrombectomy in nine patients. There were 20 (44.4%) secondary variable procedures performed during follow-up period Eighteen (40%) patients required 20 secondary procedures due to complications. The most common complication was graft thrombosis; it occurred in 11 patients (24.4%), surgical thrombectomy done in 9 (20%) patients, the other two thrombosed grafts were secondary to late graft infection that necessitate grafts removal. Puncture site aneurysm occurred in 7 cases (15.6%) with no procedure related mortality or limb threatened conditions were documented in our study. Conclusion: our case study reports reasonable mid-term patency and complications associated with this pattern of vascular access show that Infraclavicular arterio-arterial axillary loop grafts are a valid alternative option for complex patients. We advocate the use of this technique in patients with exhausted all vascular access possibilities in both upper extremities with central venous obstruction. We also indicate it in case of patients with cardiac insufficiency that could not tolerate long-term hemodynamic effect of arterio-venous fistula / graft.

Relationship between bovine carotid artery grafts for hemodialysis access and human leukocyte antigen sensitization.

Bovine carotid artery (BCA) Artegraft is a biologic graft that can be utilized as a conduit for permanent hemodialysis access and has been shown to outperform polytetrafluoroethylene grafts. However, concern regarding immunologic sensitization may limit the use of BCA in the transplant candidate. Panel reactive antibody (PRA) is an immunological test utilized in transplant recipient selection whereas increases in PRA limit access to transplantation. The purpose of our study was to determine whether BCA graft placement was adversely associated with increases in PRA. Of patients listed for kidney transplant at our institution, we identified 10 patients who underwent BCA placement for hemodialysis access and a matched cohort of 10 patients who underwent native arteriovenous fistula (AVF) creation between 2014 and 2017. The PRA value nearest to the surgery date was compared to postsurgery PRA value for the BCA and AVF patients using a paired t test. Presurgery PRAs were also compared to the maximum PRA at 0 to 6, 6 to 12, 12 to 18, and 18 to 24 months postsurgery. Prior to the dialysis access operation, the mean PRA was 14.1% ± 23.5% vs. 17.1% ± 29.0% (P = 0.76) and the median postsurgery follow-up time was 16 and 15 months for BCA and AVF cohorts, respectively. There were no statistically significant differences between presurgery and postsurgery PRA for BCA and AVF patients, regardless of time interval postsurgery. The difference in presurgery/postsurgery PRA change between cohorts was not statistically significant for PRAs closest to surgery (0.2% ± 40.6% vs. 1.0% ± 2.8%, P = 0.95, at a median 4 and 3 months postsurgery, respectively) or when using the maximum in any postsurgery interval. Prior to their dialysis access surgery, there were 16 sensitizing events in 5 patients in the BCA group compared to 10 events in 5 patients in the AVF group (P = 0.20). Only 1 of the 10 patients in the BCA group had a clinically relevant and sustained increase in PRA following their dialysis access operation vs. no patients in the AVF group (P > 0.99). However, this patient had a known sensitizing event (blood transfusion) between the BCA surgery and the postoperative PRA. Three of 10 patients in the BCA cohort vs. 5 of 10 patients in the AVF cohort went on to have successful kidney transplants (P = 0.65). The utilization of BCA for dialysis access was not associated with statistically significant changes in PRA. These data suggest that implantation of BCA will not affect access to organ transplantation.

A novel method for engineering autologous non-thrombogenic in situ tissue-engineered blood vessels for arteriovenous grafting

The durability of prosthetic arteriovenous (AV) grafts for hemodialysis access is low, predominantly due to stenotic lesions in the venous outflow tract and infectious complications. Tissue engineered blood vessels (TEBVs) might offer a tailor-made autologous alternative for prosthetic grafts. We have designed a method in which TEBVs are grown in vivo, by utilizing the foreign body response to subcutaneously implanted polymeric rods in goats, resulting in the formation of an autologous fibrocellular tissue capsule (TC). One month after implantation, the polymeric rod is extracted, whereupon TCs (length 6 cm, diameter 6.8 mm) were grafted as arteriovenous conduit between the carotid artery and jugular vein of the same goats. At time of grafting, the TCs were shown to have sufficient mechanical strength in terms of bursting pressure (2382 ± 129 mmHg), and suture retention strength (SRS: 1.97 ± 0.49 N). The AV grafts were harvested at 1 or 2 months after grafting. In an ex vivo whole blood perfusion system, the lumen of the vascular grafts was shown to be less thrombogenic compared to the initial TCs and ePTFE grafts. At 8 weeks after grafting, the entire graft was covered with an endothelial layer and abundant elastin expression was present throughout the graft. Patency at 1 and 2 months was comparable with ePTFE AV-grafts. In conclusion, we demonstrate the remodeling capacity of cellularized in vivo engineered TEBVs, and their potential as autologous alternative for prosthetic vascular grafts.

Gender-Based Utilization and Outcomes of Autogenous Fistulas and Prosthetic Grafts for Hemodialysis Access

To evaluate gender-based patterns of utilization and outcomes of arteriovenous fistulas (AVFs) and grafts (AVGs) in a population-based cohort of hemodialysis (HD) patients. A retrospective analysis of all patients in the United States Renal Data System who had an AVF or AVG placed for HD access (January 2007 to December 2014). Outcomes were access maturation, conduit patency, infection, and mortality. Chi-square, Student's t, Kaplan-Meier, and multivariable Cox regression analyses were employed accordingly. There were 456,693 (57%) males and 341,571 (43%) females who initiated HD via AVF (16%), AVG (4%) and HD catheter (80%). There was a 30% decrease in odds of initiating HD with AVF in females compared with males (adjusted odds ratio [aOR]: 0.70; 95% confidence interval [CI]: 0.69-0.71, P<0.001). The use of HD catheter as a bridge to AVF was 36% higher in females compared with males (aOR: 1.36; 95% CI: 1.33-1.39, P<0.001). Preemptive AVF maturation was 78% for males and 76% for females (P<0.001). The risk-adjusted analyses showed a 7% decrease in AVF maturation comparing females with males (adjusted hazard ratio [aHR]: 0.93; 95% CI: 0.92-0.95, P<0.001) but no difference in AVG maturation (aHR: 0.99; 95% CI: 0.97-1.01, P=0.46) After risk adjustment, primary (AVF: aHR-0.87; AVG: aHR-0.96), primary-assisted (AVF: aHR-0.84; AVG: aHR-0.97), and secondary (AVF: aHR-0.85; AVG: aHR-0.98) patency were lower for females compared with males (all P<0.05). Initiation of HD with a catheter and conversion to AVF was associated with lower patency in males (aHR: 0.29; 95% CI: 0.28-0.29; P<0.001) and females (aHR: 0.31; 95% CI: 0.30-0.31; P<0.001) compared with AVF initiates. Patient survival was higher for females compared with males who received AVF (aHR: 1.08; 95% CI: 1.07-1.09; P<0.001) and AVG (aHR: 1.13; 95% CI: 1.11-1.15; P<0.001). Initiation with HD catheter and subsequent conversion to AVF was associated with an increase in mortality for males (aHR: 1.45; 95% CI: 1.43-1.47; P<0.001) and females (aHR: 1.44; 95% CI: 1.44-1.52; P<0.001) compared with initiation via AVF. There was no significant difference in severe AVG infection comparing females with males (aHR: 1.05; 95% CI: 0.98-1.13; P=0.16). Female gender is associated with a lower prevalence of preemptive AVF's, higher utilization of catheters as a bridge to AVF, and lower patency compared with males. There was no difference in access maturation but patient survival was higher for females compared with males.

Efficacy of Primary Stent-Graft Placement in the Treatment of Vascular Access Graft Outflow Tract Stenosis.

The aim of this study is to present our personal experience using covered nitinol stent-graft in the treatment of outflow tract stenosis of arteriovenous grafts (AVGs) for hemodialysis access. Between May 2015 and October 2017, we retrospectively evaluated 36 (24 males, 12 females; mean age: 65.6 years) patients with AVGs on hemodialysis who underwent percutaneous angioplasty followed by endovascular stent-graft deployment for the treatment of stenosis of the venous outflow of the AVG. Indication for treatment included early restenosis (<3 months after previous percutaneous transluminal angioplasty [PTA]), long stenosis (stenoses >50% extending for a length >5 cm), and recoil of the stenosis after PTA performed with a noncompliant high-pressure balloon. Of 36 patients, 27 (75%) required surgical thrombectomy prior to endovascular procedure. Technical success, clinical success, primary and secondary patency, and safety were evaluated. Technical success was 100%, and clinical success was 94.4%. Primary patency was 94.4%, 72.2%, 63%, 45.9%, and 45.9% at 1, 3, 6, 12, and 18 months (average: 215 days, range: 9-653 days); secondary patency was 94.4% and 86.1% at 1 and 3 months; 80.4% at 6, 12, and 18 months; and 53.6% at 24 months (average: 276.8 days, range: 9-744 days). No deaths were registered. In selected cases, the use of stent-graft represents an effective and safe solution for the treatment of stenotic complications of the venous outflow of AVGs, even in the setting of access thrombosis.

Assessment of Use of Arteriovenous Graft vs Arteriovenous Fistula for First-time Permanent Hemodialysis Access

Initial hemodialysis access with arteriovenous fistula (AVF) is associated with superior clinical outcomes compared with arteriovenous graft (AVG) and should be the procedure of choice whenever possible. To address the national underuse of AVF in the United States, the Centers for Medicare & Medicaid has established an AVF goal of 66% or greater in 2009. To explore contemporary practice patterns and physician characteristics associated with high AVG use compared with AVF use. This review of 100% Medicare Carrier claims between January 1, 2016, and December 31, 2017, includes both inpatient and outpatient Medicare claims data. All patients undergoing initial permanent hemodialysis access placement with an AVF or AVG were included. All surgeons performing more than 10 hemodialysis access procedures during the study period were analyzed. Placement of an AVF or AVG for initial permanent hemodialysis access. A surgeon-level AVG (vs AVF) use rate was calculated for all included surgeons. Hierarchical logistic regression modeling was used to identify patient-level and surgeon-level factors associated with AVG use. A total of 85 320 patients (median age, 70 [range, 18-103] years; 47 370 men [55.5%]) underwent first-time hemodialysis access placement, of whom 66 489 (77.9%) had an AVF and 18 831 (22.1%) had an AVG. Among the 2397 surgeons who performed more than 10 procedures per year, the median surgeon level AVG use rate was 18.2% (range, 0.0%-96.4%). However, 498 surgeons (20.8%) had an AVG use rate greater than 34%. After accounting for patient characteristics, surgeon factors that were independently associated with AVG use included more than 30 years of clinical practice (vs 21-30 years; odds ratio, 0.85 [95% CI, 0.75-0.96]), metropolitan setting (odds ratio, 1.25 [95% CI, 1.02-1.54]), and vascular surgery specialty (vs general surgery; odds ratio, 0.77 [95% CI, 0.69-0.86]). Surgeons in the Northeast region had the lowest rate of AVG use (vs the South; odds ratio, 0.83 [95% CI, 0.73-0.96]). First-time hemodialysis access benchmarking reports for individual surgeons were created for potential distribution. In this study, one-fifth of surgeons had an AVG use rate above the recommended best practices guideline of 34%. Although some of these differences may be explained by patient referral practices, sharing benchmarked performance data with surgeons could be an actionable step in achieving more high-value care in hemodialysis access surgery.

Evaluation of Microscopic Structure-Function Relationships of PEGylated Small Intestinal Submucosa Vascular Grafts for Arteriovenous Connection.

Vascular grafts are used as vascular access for hemodialysis, the most common renal replacement therapy to artificially clean blood waste after kidney malfunction. Despite that they are widely used in clinical practice, upon implantation, synthetic vasculars show complications such as thrombogenesis, reduced patency rates, low blood pressure, or even complete collapse. In this study, a C-shaped vascular graft was manufactured with small intestinal submucosa (SIS) and modified on the surface and the bulk of the material via conjugation of polyethylene glycol (PEG) to obtain a biocompatible and less thrombogenic vascular graft than the commercially available polytetrafluoroethylene (ePTFE) vascular grafts. Molecular weight and concentration of PEG molecules were systematically varied to gain insights into the underlying structure-function relationships. We analyzed the chemical, thermal, and mechanical properties of vascular grafts modified with 6 equiv of SIS-PEG 400 as well as cytotoxicity and in vitro platelet deposition. Immune response, patency rates, and extent of regeneration were also tested in vivo with the aid of swine animal models. Results showed that the conjugation levels achieved were sufficient to improve graft compliance, therefore approaching that of native vessels, while platelet deposition was altered leading to a 95% reduction compared with pristine SIS and 92% with respect to ePTFE. H&E staining on explanted samples corroborated SIS-PEG 400 biocompatibility and the ability to promote regeneration. The obtained results set solid foundations for the rational design and manufacture of a regenerative, small diameter vascular graft model and introduce an alternative to ePTFE vascular grafts for hemodialysis access.

Clinical and Economic Benefits of Stent Grafts in Dysfunctional and Thrombosed Hemodialysis Access Graft Circuits in the REVISE Randomized Trial

PurposeTo compare reinterventions and associated costs to maintain arteriovenous graft hemodialysis access circuits after rescue with percutaneous transluminal angioplasty (PTA), with or without concurrent Viabahn stent grafts, over 24 months. Materials and MethodsThis multicenter (n = 30 sites) study evaluated reintervention number, type, and cost in 269 patients randomized to undergo placement of stent grafts or PTA alone. Outcomes were 24-month average cumulative number of reinterventions, associated costs, and total costs for all patients and in 4 groups based on index treatment and clinical presentation (thrombosed or dysfunctional). ResultsOver 24 months, the patients in the stent graft arm had a 27% significant reduction in the average number of reinterventions within the circuit compared to the PTA arm (3.7 stent graft vs 5.1 PTA; P = .005) and similar total costs ($27,483 vs $28,664; P = .49). In thrombosed grafts, stent grafts significantly reduced the number of reinterventions (3.7 stent graft vs 6.2 PTA; P = .022) and had significantly lower total costs compared to the PTA arm ($30,329 vs $37,206; P = .027). In dysfunctional grafts, no statistical difference was observed in the number of reinterventions or total costs (3.7 stent graft vs 4.4 PTA; P = .12, and $25,421 stent graft and $22,610 PTA; P = .14). ConclusionsOver 24 months, the use of stent grafts significantly reduced the number of reinterventions for all patients, driven by patients presenting with thrombosed grafts. Compared to PTA, stent grafts reduced overall treatment costs for patients presenting with thrombosed grafts and had similar costs for stenotic grafts.