Patency of autogenous and polytetrafluoroethylene upper extremity arteriovenous hemodialysis accesses: a systematic review

Association of race and ethnicity with initial surgical hemodialysis access type in a safety net system

OBJECTIVES

Prior studies have found lower arteriovenous fistula (AVF) creation rates in Black and Hispanic patients. Whether this is due to health care disparities or other differences is unclear. Our objective was to evaluate the racial/ethnic differences in initial surgical access type within a high-volume, safety net system with predominantly Black and Hispanic populations.

METHODS

A retrospective review of initial hemodialysis (HD) access in consecutive cases between 2014 and 2019 was conducted from all five safety net hospitals in a health care system that primarily treats underserved patients. Patient data collected included race, ethnicity, sex, comorbidities, and initial arteriovenous (AV) access type (AV fistula [AVF] vs AV graft [AVG]). The rates of cephalic vein-based AVF (CAVF; radiocephalic, brachiocephalic) were compared with basilic and brachial vein AVF (BAVF), because the latter are performed as two stages. Bivariate and multivariate logistic regression models were adjusted for demographic and clinical variables to evaluate the relationship between race/ethnicity, surgical access type, and comorbid conditions.

RESULTS

We included 1334 patients (74% Hispanic, 9% Black, 7% Asian, 2% White, 8% other) who underwent first-time surgical HD access creation. The majority were male (818 [63%]). Medical comorbidities were equal among groups, except for chronic obstructive pulmonary disease and stroke, which were higher in Black patients (P < .005 and P = .005, respectively). Overall, 1303 patients (98%) underwent AVF creation and 31 AVG creation (2%), with no difference between race/ethnicity in AVF vs AVG creation. Of the AVF cohort, 991 (76%) had a CAVF and 312 (24%) had a BAVF. Males were more likely than females to get a CAVF (65% vs 35%; P = .002).

CONCLUSIONS

Within our safety net health system, where most patients are under-represented minorities, nearly all patients undergoing HD access had an AVF as their initial surgery with no difference in race/ethnicity. AVF type received differed by race, with Black patients twice as likely to undergo BAVF, which required two stages. Further studies are needed to identify the reasons for these differences.

Long-term outcomes following thrombolysis of arteriovenous grafts

BACKGROUND

Thrombolysis for arteriovenous grafts (AVG) yields high technical success rates, however, long-term outcomes are unclear. We conducted a multicenter retrospective cohort study to analyze 5-year patency rates following AVG thrombolysis.

METHODS

All patients who underwent AVG thrombolysis between 2005 and 2015 at three academic hospitals were included. Prospectively maintained institutional nephrology and radiology databases were used to record demographic, clinical, and AVG characteristics. The primary outcome was primary patency, defined as AVG access survival without re-intervention including angioplasty ± stent with/without re-thrombolysis. Secondary outcomes were assisted primary patency and cumulative patency, defined as AVG access survival until re-thrombosis requiring re-thrombolysis or abandonment, respectively. Technical success was defined as restoration of flow with <30% residual stenosis. Patients were followed until 2017. Patency rates were assessed using Kaplan-Meier survival analysis and Cox proportional hazards were calculated to determine associations between covariates and patency loss.

RESULTS

Seventy-four patients underwent AVG thrombolysis during the study period with a median follow-up period of 21.4 (IQR 8.3-42.8) months. The average age was 58.6 years with a high rate of comorbidities, including hypertension (82.4%) and diabetes (54.1%). Thrombolysis technical success was 96%. There were 147 re-interventions in 46 patients, of which 98 were re-thrombolysis (mean re-intervention rate of 1.27/patient/year). Primary patency at 1, 3, and 5 years were 43.2%, 20.2%, and 7.7%. Assisted primary patency at 1, 3, and 5 years were 47.5%, 20.2%, and 7.7%. Cumulative patency at 1, 3, and 5 years were 75.0%, 38.8%, and 22.6%. Cox proportional hazards analysis demonstrated no associations between demographic, clinical, and procedural characteristics and patency rates.

CONCLUSIONS

Despite a high technical success rate, thrombolysis for AVG dysfunction is associated with poor long-term patency. Future studies are needed to determine risk factors for re-thrombosis to identify patients who will benefit from AVG thrombolysis in the long-term.

Midterm outcomes of endoscopic-assisted brachial-basilic arteriovenous fistula creation

Endoscopic vein harvest remains underused in single-stage brachial-basilic arteriovenous fistula creation. We analyzed our results with the use of this technique in a cohort of predominantly obese (body mass index ≥30 kg/m2) patients. Demographics, intraoperative details, and outcomes for all consecutive patients who underwent single-stage endoscopic-assisted brachial-basilic arteriovenous fistula creation between 2020 and 2022 at a single institute were analyzed retrospectively. The primary outcomes were technical success, fistula maturation, and primary assisted and secondary patency rates. Of the 11 patients (7 men; mean age, 62 ± 11.6 years), 7 (64%) already required dialysis at referral. The mean body mass index was 34 ± 7 kg/m2, 64% were obese, and an additional 27% were overweight. The medical comorbidities included hypertension in 11 patients (100%), diabetes in 7 (64%), and smoking in 8 (73%). Technical success was 100%, with no intraoperative complications. The median procedural length was 231 minutes (range, 183-302 minutes). Early complications in two patients (18%) included bleeding of the venous side branch requiring ligation and the loss of thrill requiring division of a tethering bridge of a large tributary. The maturation rate was 100%, and the brachial-basilic arteriovenous fistula was successfully accessed in all patients who required dialysis. At 12 months, the primary assisted and secondary patency rates were 90% ± 10% and 100%, respectively. Reintervention in seven patients (64%) included successful angioplasty in four, thrombectomy in two, and aneurysm resection with an interposition graft in one patient. Endoscopic vein harvest can be used for single-stage brachial-basilic arteriovenous fistula creation with good technical success and favorable maturation and patency rates, even for obese patients.

Pull-through technique through antegrade radial artery puncture without sheath insertion in balloon-assisted radiocephalic arteriovenous fistulas maturation

PURPOSE

The aim of this study was to investigate the effectiveness and safety of the pull-through technique through antegrade radial artery puncture without sheath insertion in balloon-assisted radiocephalic AVF maturation.

METHODS

We retrospective studied a total of 62 patients with immature radiocephalic AVF, who received balloon-assisted maturation in our hospital. 15 patients received pull-through technique through radial artery without sheath insertion and 47 patients received treatment through a regular venous approach.

RESULTS

The success rate of pull-through technique group and control group was 86.7% (13 out of 15), 89.1% (41 out of 46) respectively. There was no significant difference between two groups (P > 0.05). In our study, there were 2 patients in the pull-through technique group and 3 patients in the control group, which had hematoma in the vein puncture site (P = 0.59). There were also no differences in the primary patency rate between two groups at 6 months and 12 months (76.9% vs 70.7%, 38.4% vs 41.5%, respectively, P > 0.05).

CONCLUSION

The pull-through technique through antegrade radial artery without sheath insertion in promoting radiocephalic AVF maturation is effective and safe.

Comparison between transposed arteriovenous fistulas and arteriovenous graft for the hemodialysis patients: A meta-analysis and systematic review

It is challenging for a surgeon to determine the appropriate vascular access for hemodialysis patients whose cephalic vein is usually inaccessible. The purpose of the study is to compare the complications and patency rates between transposed arteriovenous fistulas (tAVF) and arteriovenous graft (AVG) for the hemodialysis patients. Studies were recruited from PubMed, Cochrane library, EMBASE, the web of science databases, and reviewing reference lists of related studies from the inception dates to September 2, 2021. Statistical analyses were conducted using the statistical tool Review Manager version5.3 (Cochrane Collaboration, London, UK). I2 > 50% was defined as a high degree of heterogeneity, and then a random-effects model was used. Otherwise, the fixed-effects model was used. Odds ratio with its 95% confidence interval (95% CI) was used. Thirty-three trials (26 retrospective studies, four randomized controlled trials, two prospective trials, and one controlled-comparative study) with 6430 enrolled participants were identified in our analysis. The results showed that tAVF was accompanied with lower thrombosis rate (103/1184 (8.69%) vs 257/1367 (18.80%); I2 = 45%; 95% CI, 0.34 (0.26, 0.45)) and infection rate (43/2031 (2.12%) vs 180/2147 (8.38%); I2 = 0%; 95% CI, 0.20 (0.14, 0.30)) than arteriovenous graft. The significantly better primary patency rates, secondary patency rates, and primary assisted patency rates during follow-up were found in tAVF. However, the failure rate and the prevalence of hematoma were significantly lower in AVG group. No evidence showed the rate of overall mortality, steal syndrome, and aneurysm reduced in tAVF. Our results showed that tAVF is a promising vascular access technique for hemodialysis patients whose cephalic vein is inaccessible. Our data showed that tAVF has less thrombosis, infection risk, and better patency rates when compared with AVG. However, more attentions need to be paid to transposed arteriovenous fistulas maturation and hematoma.

End-to-end anastomosis as a superior repair type to prevent recurrence of arteriovenous fistula aneurysms and improve patency outcomes

BACKGROUND

Arteriovenous fistulae (AVF) complicated by aneurysms are repaired through several mechanisms. Little is known about risk factors for aneurysm recurrence or the efficacy of subsequent repair of recurring aneurysms.

METHODS

About 291 patients underwent AVF aneurysm repair between 2009 and 2019 at a large urban medical center. Patients who underwent staged repair, had a primary graft with pseudoaneurysm, were status-post kidney transplant, or using other dialysis access at the time of repair were excluded. One hundred sixty-two patients were included in the study, of which 52 developed a secondary aneurysm. Chi-square and t-test analyses were used to compare demographics. Multivariate logistic regression was used to examine independent risk factors for aneurysm recurrence. Of the 52 patients with recurrent aneurysms, 41 were repaired again. Patency was examined for each group 1 year postoperatively.

RESULTS

Patients without secondary aneurysms were more likely to have a Charlson Comorbidity Index score ⩾5 (p = 0.045). Males were 2.8 times more likely to develop a secondary aneurysm compared to females (p = 0.023). Patients who underwent elective compared to emergent or urgent surgery for primary aneurysms were significantly less likely to recur (OR = 0.222; p = 0.016). Primary aneurysms repaired by end-to-end anastomosis, compared to aneurysmorrhaphy or graft, were significantly less likely to recur (OR = 0.239; p = 0.041). Among patients with secondary aneurysms, those repaired via end-to-end anastomosis had a significantly higher primary patency rate 1 year postoperatively (p = 0.024). Secondary aneurysm repairs exhibited 1-year primary and secondary patency rates of 51.2% and 82.9%, respectively.

CONCLUSIONS

End-to-end anastomosis reduces risk of recurrence and demonstrates superior patency rates when repairing recurrent aneurysms. It remains unclear why some patients are prone to aneurysm recurrence, however continued attempts to repair existing vascular access are proven to be successful.

First-in-human feasibility study of the aXess graft (aXess-FIH): 6-Month results

OBJECTIVE

The creation of an arteriovenous fistula (AVF) is considered the most effective hemodialysis (HD) vascular access. For patients who are not suitable for AVF, arteriovenous grafts (AVGs) are the best access option for chronic HD. However, conventional AVGs are prone to intimal hyperplasia, stenosis, thrombosis, and infection. Xeltis has developed an AVG as a potential alternative to currently available AVGs based on the concept of endogenous tissue restoration. The results of the first 6-month follow-up are presented here.

METHODS

The aXess first-in-human (FIH) study [NCT04898153] is a prospective, single-arm, multicenter feasibility study that evaluates the early safety and performance of the aXess Hemodialysis Graft. A total of 20 patients with end-stage renal disease were enrolled across six European investigational sites.

RESULTS

At 6-months follow-up, all grafts were patent with primary and secondary patency rates were 80% and 100%, respectively. Three patients required a re-intervention to maintain graft patency, while one re-intervention was required to restore patency. One graft thrombosis and zero infections were reported.

CONCLUSION

The expected advantages of the novel aXess Hemodialysis Graft over conventional AVGs would be evaluated by the analysis on long-term safety and effectiveness during the 5-year follow-up of the currently ongoing trial.

Slowly moving the needle away from Fistula First

OBJECTIVE

In 2019, the management of end-stage kidney disease (ESKD) shifted away from "Fistula First" (FF) to "ESKD Life-Plan: Patient Life-Plan First then Access Needs." Indeed, some patients exhibit such excessive comorbidity that even relatively minor vascular surgery may be complicated. The purpose of this study was to retrospectively assess complications and mortality (and delineate operative futility) in patients undergoing arteriovenous fistula (AVF) creation in the FF era.

METHODS

Consecutive AVFs created in a single institution before 2021 were retrospectively reviewed. Operative futility was defined as never-accessed fistula, no initiation of dialysis, failure of access maturation (despite secondary intervention), hemodialysis access-induced distal ischemia requiring ligation, early loss of secondary patency, and/or patient mortality within the first 6 postoperative months.

RESULTS

A total of 401 AVFs were created including radial-cephalic (44%), brachial-cephalic (41%), and brachial-basilic (15%) constructions. Patients exhibited a mean age of 69 ± 15 years; 63% were male, and most (74%) were already being hemodialyzed at the time of fistula creation. Forty-five patients (11%) suffered a cardiac event, and five patients died (1%) within 90 days of their access surgery. Perioperative cardiac events were significantly more common after age 80 (19% vs 8%; P = .004); age >80 years was an independent predictor of major 90-day complications (odds ratio [OR], 1.88; 95% confidence interval [CI], 1.04-3.39; P = .036) and the sole independent predictor of major morbidity defined as cardiopulmonary complications, stroke, or death within the first year (OR, 2.01; 95% CI, 1.24-3.25; P = .004). Operative futility was encountered in 52% of the cohort (n = 208 patients): 40% (n = 160) of primary AVFs failed to mature despite assistance, 19% (n = 77) had lost secondary patency by 6 months, 13% of patients (n = 53) were never started on dialysis after access creation, 4% (n = 16) were dead by 6 months, 2% of AVFs (n = 10) matured but were never accessed, and 2% (n = 9) required ligation for hemodialysis access-induced distal ischemia. Not surprisingly, the sole independent protector against operative futility was that catheter-based dialysis had been established prior to AVF creation (OR, 0.36; 95% CI, 0.22-0.59; P < .01).

CONCLUSIONS

Approximately 50% of primary AVF operations performed in the aggressive FF era were deemed futile. Octogenarians were particularly prone to futility and complications during this era. A paradigm shift, from FF to an "ESKD Life-Plan" will, hopefully, more thoughtfully match vascular access strategies to individual patient needs.

Treatment of intragraft stenosis in hemodialysis grafts with Supera stents: A retrospective study

PURPOSE

To report the patency rates after implantation of an interwoven nitinol stent to salvage failing arteriovenous grafts (AVGs) caused by intragraft stenoses.

METHODS

Between May 2018 and May 2020, 21 Supera stents were placed in 20 patients (18 women; mean age: 79.9 years) who had a failing AVG due to repeat intragraft stenoses. Recurrent AVG dysfunction with same intragraft stenosis within 3 months after first time angioplasty was a criterion for stenting. Those with concurrent treatment for other lesions were excluded.

RESULTS

The technical success rate was 100%. Intragraft stenoses were treated at a median of 19.7 (interquartile range: 6-36) months after graft creation. Access circuit primary patency rates after stent placement were 84% and 35% at 6 and 12 months, respectively. Access circuit secondary patency rates were 100% at 6 and 12 months and 89% at 18 months. Only one patient presented with graft failure due to proximal drainage vein occlusion. The target lesion patency rates were 100% at 6 months and 75% at 12 months. The rate of reintervention for intragraft lesion was 0.15 procedures per year. Stent distortion did not occur under regular cannulation.

CONCLUSION

The interwoven nitinol stent is a promising treatment for failing AVGs with recurrent intragraft stenoses. The 1-year access circuit primary, secondary, and target lesion patency rates were acceptable, with a low reintervention rate. Stent fracture does not occur in areas of needle puncture.

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.

Robotic tomographic ultrasound and artificial intelligence for management of haemodialysis arteriovenous fistulae

BACKGROUND

Arteriovenous fistulae (AVF) and Arteriovenous Grafts (AVG) may present a problematic vascular access for renal replacement therapy (RRT), reliant on recurrent specialist nurse and medical evaluation. Dysfunctional accesses are frequently referred 'out of the dialysis clinic' for specialist sonographic examination, with associated delays potentiating loss of vascular access viability and/or need for emergency intervention. Definitive anatomical and functional diagnostics based in the dialysis unit may help to solve these delays and associated complications.

OBJECTIVES

This publication reports a novel vascular access monitoring concept, Robotic Tomographic Ultrasound (RTU).

RESEARCH DESIGN

Robotic Tomographic Ultrasound incorporates a semi-autonomous, robotic vascular ultrasound system and purpose designed analysis software that can be deployed at the point of care. Three-dimensional scan data, as well as conventional B-Mode and Doppler data are obtained by the system and transferred to a cloud based reporting and analysis software. Scans are remotely annotated and interpreted by a sonographer, with diagnostic data presented securely to clinicians on their preferred web based application/web connected device.

RESULTS

Software developed specifically for pre AVF mapping, maturation and monitoring protocols, analyse the data and then present interpreted results to all caring clinicians to assist with decision making. Vascular access planning can be determined with high confidence with data from the Map module. Maturation data can be presented in line with institutional requirements to the dialysis nurse, facilitating precocious needle access.

CONCLUSION

Robotic Tomographic Ultrasound is a novel approach to vascular access management that may reduce the risk of loss of functional access by regular monitoring with the system; automated alerts guiding clinicians to the need for pre-emptive intervention, and the potential to increase longevity of the vascular access.

Translational tissue-engineered vascular grafts: From bench to bedside

Cardiovascular disease is a primary cause of mortality worldwide, and patients often require bypass surgery that utilizes autologous vessels as conduits. However, the limited availability of suitable vessels and the risk of failure and complications have driven the need for alternative solutions. Tissue-engineered vascular grafts (TEVGs) offer a promising solution to these challenges. TEVGs are artificial vascular grafts made of biomaterials and/or vascular cells that can mimic the structure and function of natural blood vessels. The ideal TEVG should possess biocompatibility, biomechanical mechanical properties, and durability for long-term success in vivo. Achieving these characteristics requires a multi-disciplinary approach involving material science, engineering, biology, and clinical translation. Recent advancements in scaffold fabrication have led to the development of TEVGs with improved functional and biomechanical properties. Innovative techniques such as electrospinning, 3D bioprinting, and multi-part microfluidic channel systems have allowed the creation of intricate and customized tubular scaffolds. Nevertheless, multiple obstacles must be overcome to apply these innovations effectively in clinical practice, including the need for standardized preclinical models and cost-effective and scalable manufacturing methods. This review highlights the fundamental approaches required to successfully fabricate functional vascular grafts and the necessary translational methodologies to advance their use in clinical practice.

Hybrid Revision of Dysfunctional Aneurysmal Arteriovenous Fistulas

Endovascular therapy has become the first-line treatment for failing hemodialysis arteriovenous fistulas (AVFs). However, open revision remains an important modality for vascular access maintenance and the recommended approach for AVF aneurysms. This case series describes a hybrid approach for aneurysmal access revision. Three patients were referred for second opinion after failure of endovascular therapy to establish a functioning access. The medical history is briefly described to highlight the limitations of endovascular therapy and the technical advantages of the hybrid approach in these clinical scenarios.

Functional patency rates of arteriovenous fistula of a retrospective cohort study from one of the biggest centers in Canada

BACKGROUND

The main barriers to arterio-venous fistula (AVF) utilization are primary failure, long maturation duration, and low secondary patency rates.

METHODS

In this retrospective cohort study, primary, secondary, functional primary, and functional secondary patency rates were calculated and compared between two age groups (< 75 years and >  = 75 years) and between radiocephalic (RC-) and upper arm (UA-) AVFs, and factors determining the duration of functional secondary patency were evaluated.

RESULTS

Between 2016 and 2020, 206 predialysis patients whose AVFs had been created previously initiated renal replacement treatment. RC-AVFs comprised 23.3% and were created after favorable analysis of the forearm vasculature. Overall, the primary failure rate was 8.3, and 84.7% started hemodialysis with a functioning AVF. Functional secondary patency rates of primary AVFs were better with RC-AVFs [1,3 and 5 year rates of 95.8, 81.9 and 81.9% versus 83.4, 71.8 and 59.2% for UA-AVFs (log rank p: 0.041)]. There was no difference between the two age groups for any of the AVF outcomes assessed. Among patients whose AVF was abandoned, 40.3% had gone on to have a second fistula created. This was significantly less likely in the older group (p < 0.01).

IN CONCLUSION

(1) UA-AVFs were placed more commonly than RC-AVFs; (2) a selection bias existed whereby RC-AVFs were only created after favorable forearm vasculature was demonstrated or suspected; (3) superior functional secondary patency rates were observed with RC-AV's, perhaps stemming from this selection bias; (4) the elderly were more likely to have only one AVF creation attempt.

Imaging Patients with Kidney Failure

The approach to imaging a patient with kidney failure continues to evolve. Overstatement of the risk of iodinated contrast material-induced (ie, contrast-induced) acute kidney injury and new guidelines for administration of gadolinium-based contrast media affect screening and the choice of contrast material. Treatment of kidney failure requires dialysis or a kidney transplant. Pretransplant imaging includes assessment for the feasibility of performing a transplant and evaluation for underlying malignancy and peripheral vascular disease. Patients with kidney failure are at high risk for renal cell carcinoma. Subtypes that occur exclusively or more commonly in patients with kidney failure, such as acquired cystic kidney disease, renal cell carcinoma, and clear cell papillary renal cell carcinoma, have specific clinical-pathologic characteristics, with indolent behavior. Performing US for dialysis planning increases the success of placement of an arteriovenous fistula, while postoperative US evaluation is essential in assessment of access dysfunction. Systemic manifestations in patients with kidney failure are multifactorial and may relate to the underlying cause of renal failure or may be secondary to treatment effects. Disturbances in mineral and bone metabolism and soft-tissue and vascular calcifications are seen in patients with chronic kidney disease and mineral bone disorder. Neurologic and cardiothoracic complications are also common. The authors provide a comprehensive overview of imaging considerations for patients with kidney failure, including the appropriate use of CT, MRI, and US with their respective contrast agents; the use of imaging in transplant workup and dialysis assessment; and the common renal and extrarenal manifestations of kidney failure. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Arteriovenous fistula aneurysmorrhaphy is associated with improved patency and decreased vascular access abandonment

BACKGROUND

Upper extremity hemodialysis arteriovenous fistulas (AVFs) can become aneurysmal over time due to repeated cannulation and/or outflow steno-occlusive disease. The optimal surgical management of aneurysmal AVFs (aneurysmorrhaphy vs interposition graft) has remained unclear.

METHODS

We performed a retrospective review in which current procedural terminology codes were used to screen for patients who had undergone surgical treatment of aneurysmal AVFs between 2016 and 2021 at a single hospital system. The patients were included after a review of the operative reports. The cases were divided by surgical procedure (aneurysmorrhaphy vs interposition graft placement). The patients who had undergone primary AVF ligation or other types of repair were excluded. The primary outcomes were primary assisted and secondary patency, and the secondary outcome was dialysis access abandonment. Multivariable Cox proportional hazards regression was used to test the association between the type of AVF aneurysm repair and the primary and secondary outcomes.

RESULTS

From 2016 to 2021, 6951 patients had undergone 16,190 dialysis access procedures. Of these procedures, 381 (2.4%) were related to surgical treatment of an aneurysmal AVF. We excluded 58 primary AVF ligation cases and 20 cases involving other types of repair, leaving 303 cases for analysis. These were divided into two groups: aneurysmorrhaphy (n = 123; 41%) and interposition graft (n = 180; 59%). No differences were found between the groups in male gender (68% vs 63%), hypertension (98% vs 98%), or central stenosis (14% vs 22%). The patients who had undergone aneurysmorrhaphy were younger (median age, 54 years vs 59 years); had had a lower rate of diabetes (41% vs 59%), coronary artery disease (41% vs 58%), and congestive heart failure (41% vs 55%); and were less likely to have undergone upper arm access (72% vs 92%). The median follow-up was 11.1 months (interquartile range, 3.6-25.2 months). No differences were found in the incidence of 30-day wound complications (1% vs 3%) or surgical site infections (4% vs 6%). On multivariable Cox regression, interposition graft placement was associated with the loss of primary assisted patency (adjusted hazard ratio [aHR], 2.42; 95% confidence interval [CI], 1.18-4.95), loss of secondary patency (aHR, 3.10; 95% CI, 1.21-7.94), and abandonment of dialysis access (aHR, 3.07; 95% CI, 1.61-5.87; P < .05 for all) at 2 years.

CONCLUSIONS

AVF aneurysmorrhaphy was associated with improved primary assisted and secondary patency and decreased abandonment of dialysis access. We suggest using aneurysmorrhaphy when AVF aneurysms are indicated for repair. However, individual factors such as patient comorbidities, AVF anatomy, remaining dialysis access options, and patient preference should be considered when planning the surgical approach.

A Retrospective Review of Bovine Artery Graft Patency: A Single Site Study

BACKGROUND

The hemodialysis dependent population is increasing in the United States. Dialysis access complications are a significant source of morbidity and mortality for patients with end stage renal disease (ESRD). A surgically created autogenous arteriovenous fistula (AVF) has been the gold standard for dialysis access. However, for patients who are not candidates for AVF, arteriovenous grafts using various conduits have widely been utilized. In this study, we report the outcomes of bovine carotid artery (BCA) grafts for dialysis access at a single institution, and compare these results to those for polytetrafluoroethylene (PTFE) grafts.

METHODS

A single-institution, retrospective review of all patients undergoing surgical placement of a bovine carotid artery graft for dialysis access from 2017-2018 was performed under an IRB-approved protocol. The primary, primary-assisted, and secondary patency were calculated for the whole cohort and results determined based on gender, BMI and indication for use. Comparison was performed to PTFE grafts at same institution from 2013 to 2016.

RESULTS

One hundred and twenty two patients were included in this study. Seventy-four patients had a BCA graft placed while 48 had a PTFE graft placed. . The mean age was 59.7±13.5 years in the BCA group, 55.8±14.5 in the PTFE group and the mean BMI was 29.8 ± 9.2 kg/m² in the BCA group and 28.1±9.7 in the PTFE group. Comparison of the comorbidities present in BCA/PTFE groups included hypertension (92%/100%), diabetes (57%/54%), congestive heart failure (28%/10%), lupus (5%/7%), and chronic obstructive pulmonary disease (4%/8%). The various configurations were reviewed (BCA/PTFE): interposition/access salvage (40.5%/13%), axillary-axillary (18.9%/7%), brachial-basilic (5.4%,6%), brachial-brachial (4.1%,4%), brachial-cephalic (1.4%0%), axillary-brachial (1.4%/0%), brachial-axillary (23%, 62%), and femoral-femoral (5.4%,6%). Overall, twelve-month primary patency was 50% in the BCA group and 18% in the PTFE group (p=0.001). Twelve-month primary-assisted patency was 66% in the BCA group and 37% in the PTFE group (p=0.003). Twelve-month secondary patency was 81% in the BCA group and 36% in the PTFE group (p=0.07). When comparing BCA graft survival probability among male and female gender, males had better primary-assisted patency (p = 0.042). Secondary patency among the two genders was similar. There was no statistically significant difference in primary, primary-assisted and secondary patency of BCA grafts between different BMI groups or indication for use. The average patency of a bovine graft was 17.8 ±8 months. Sixty-one percent of the BCA grafts needed intervention with 24% needing multiple interventions. There was an average of 7 ±5 months to first intervention. The infection rate was 8.1% in the BCA group and 10.4% in the PTFE group with no statistical difference.

CONCLUSION

Primary and primary-assisted patency rates at 12 months in our study were higher than those for PTFE at our institution. There was higher primary assisted patency of BCA grafts among males at 12 months compared to PTFE. Obesity and indication for BCA graft use did not appear to affect patency in our population.

Staged autogenous to prosthetic hemodialysis access creation strategy to maximize forearm options

OBJECTIVE

When an adequate cephalic vein is not available for fistula construction, surgeons often turn to basilic vein or prosthetic constructions. Single-stage forearm prosthetic hemodialysis accesses are associated with poor durability, and upper arm non-autogenous access options are often limited by axillary outflow failure, which inevitably drives transition to the contralateral arm or lower extremity. We hypothesized that initial creation of a modest flow proximal forearm arterial-venous anastomosis to dilate ("develop") inflow and outflow vessels, followed by a planned second-stage procedure to create a cannulation zone with a prosthetic graft in the forearm, would result in reliable and durable hemodialysis access in patients with limited options.

METHODS

We performed an institutional cohort study from 2017 to 2021 using a prospectively maintained database supplemented with adjudicated chart review. Patients without traditional autogenous hemodialysis access options in the forearm underwent an initial non-wrist arterial-venous anastomosis creation in the forearm as a first stage, followed by a second-stage interposition graft sewn to the existing inflow and venous outflow segments to create a useable cannulation zone in the forearm while leveraging vascular development. Outcomes included time from second-stage access creation to loss of primary and secondary patency, frequency of subsequent interventions, and perioperative complications.

RESULTS

The cohort included 23 patients; first-stage radial artery-based (74%) configurations were more common than brachial artery-based (26%). Mean age was 63 years (standard deviation, 14 years), and 65% were female. Median follow-up was 340 days (interquartile range [IQR], 169-701 days). Median time to cannulation from second-stage procedure was 28 days (IQR, 18-53 days). Primary, primary assisted, and secondary patency at 1 year was 16.7% (95% confidence interval [CI], 5.3%-45.8%), 34.6% (95% CI, 15.2%-66.2%), and 95.7% (95% CI, 81.3%-99.7%), respectively. Subsequent interventions occurred at a rate of 3.02 (IQR, 1.0-4.97) per person-year, with endovascular thrombectomy with or without angioplasty/stenting (70.9%) being the most common. There were no cases of steal syndrome. Infection occurred in two cases and were managed with antibiotics alone.

CONCLUSIONS

For patients without adequate distal autogenous access options, staged prosthetic graft placement in the forearm offers few short-term complications and excellent durability with active surveillance while strategically preserving the upper arm for future constructions.

Development of an artificial portal vein using bioabsorbable polymers

PURPOSE

During surgical resection of malignant tumors in the hepatobiliary pancreatic region, portal vein resection and reconstruction may be needed. However, there is no alternative to the portal vein. We therefore developed an artificial portal vein that could be used in the abdominal cavity.

METHODS

In the experiments, hybrid pigs (n = 8) were included. An artificial portal vein was created using a bioabsorbable polymer sheet (BAPS). Subsequently, the portal vein's anterior wall was excised into an elliptical shape. A BAPS in the form of a patch was implanted at the same site. At 2 weeks (n = 3) and 3 months (n = 5) after the implantation, the BAPS implantation site was resected and evaluated macroscopically and histopathologically.

RESULTS

Immediately after the implantation, blood leakage was not detected. Two weeks after implantation, the BAPS remained, and endothelial cells were observed. Thrombus formation was not observed. Three months after implantation, the BAPS had been completely absorbed and was indistinguishable from the surrounding portal vein. Stenosis and aneurysms were not observed.

CONCLUSIONS

BAPS can replace a defective portal vein from the early stage of implantation to BAPS absorption. These results suggest that it can be an alternative material to the portal vein in surgical reconstruction.

Similar long-term outcomes between endovascular aneurysm repair and open surgical repair for abdominal aortic aneurysms in octogenarian patients: a single-center study

Purpose

Endovascular aneurysm repair (EVAR) has lower perioperative mortality and morbidity rates and shorter hospital stays when compared to open surgical repair (OSR) in octogenarian patients. However, its long-term results remain unclear. Hence, we aimed to analyze and compare the long-term outcomes of OSR and EVAR in this aging population.

Methods

This single-center, retrospective, observational study analyzed the data of patients older than 80 years who underwent primary repair of an abdominal aortic aneurysm (AAA) between 2011 and 2016 in our hospital. The primary outcomes were in-hospital complications and 30-day mortality, while the secondary outcomes included all-cause mortality and reintervention rate.

Results

Among the 48 patients with elective AAA repair, 13 underwent OSR and 35 underwent EVAR. In-hospital complications occurred in 10 patients (20.8%), 5 for OSR (38.5%) and 5 for EVAR (14.3%) with no significant difference between the groups (P = 0.067). In the OSR group, pulmonary complications were the most common events; in the EVAR group, 2 patients had ischemic colitis diagnosed with sigmoidoscopy and recovered by conservative treatment. The 1- and 5-year survival rates were 77.8% and 55.6% in the OSR group, and 66.0% and 54.9% in the EVAR group, respectively. The reintervention rate was 8.6% for the EVAR group; none of the OSR group were readmitted.

Conclusion

The difference in procedures did not affect patient survival. Therefore, OSR does not necessarily have a worse prognosis than EVAR. Individual risk stratification must be preceded before the selection of an appropriate treatment method.

The Effects of Vasodilation Induced by Brachial Plexus Block on the Development of Postoperative Thrombosis of the Arteriovenous Access in Patients with End-Stage Renal Disease: A Retrospective Study

Although brachial plexus block (BPB)-induced vasodilation reduces the incidence of arteriovenous access (AC) thrombosis, BPB cannot completely prevent its development. Therefore, we retrospectively investigated the factors affecting BPB-induced vasodilation and their effects on AC thrombosis development. Ninety-five patients undergoing AC surgery under BPB were analyzed. Vessel diameters were measured before and 20 min after BPB. The surgery abandoned before the BPB placement was performed when the BPB-induced increases in vessel diameters met its indications. Complete occlusive access thrombosis (COAT) was defined as loss of pulse, thrill, or bruit. Fourteen patients (14.7%) developed COAT. The outflow vein was more dilated by BPB than the inflow artery (0.6 versus 0.1 mm in median, p < 0.001). The original surgery plan was changed for seven patients (7.4%). Diabetes mellitus (DM) and ischemic heart disease (IHD) decreased the extent of increases in the inflow artery by -0.183 mm (95% confidence interval [CI] [-0.301, -0.065], p = 0.003) and outflow vein diameters by -0.402 mm (95% CI [-0.781, -0.024], p = 0.038), respectively. However, DM, IHD, and changes in the vessel diameters had insignificant effects on the development of COAT. In conclusion, although DM and IHD attenuate the vasodilating effects of BPB, they do not contribute to the development of COAT.

A Single-Center Experience with Forearm Arteriovenous Loop Grafts for Hemodialysis

BACKGROUND

Autogenous arteriovenous fistula (AVF) remains the standard of hemodialysis (HD) access; however, it cannot be reasonably obtained in all patients. For patients with contraindications to AVFs, prosthetic arteriovenous graft (AVG) remains an alternative. AVGs are plagued by high failure rates; however, there is a paucity of literature examining this. This study aims to examine a single-center review of outcomes of forearm loop AVGs in patients requiring HD access.

METHODS

A single institution, retrospective chart review was completed from 2012 to 2019, including demographics, end-stage renal disease etiology, brachial vessel diameters, and comorbidities. Logistic regression and Cox proportional hazard models were evaluated. Outcomes were defined as primary patency (time elapsed from graft creation until it was utilized as the patient's primary access), primary-assisted patency (time from primary access to intervention to maintain patency), and functional patency (time from graft placement until graft failure). Additionally, multinomial regression models were used to evaluate associations with categorical number of required interventions.

RESULTS

Ninety-eight patients [mean age 61.8 (13.9) years, 42.9% female] were identified as having brachial artery to brachial vein AVG creation during the study period, of which 75% achieved primary patency. Primary-assisted patency was 0.36 [standard error (SE) 0.07] at 6 months and 0.12 (SE 0.05) at 1 year. Functional patency was 0.75 (SE 0.07) at 6 months and 0.43 (SE 0.09) at 1 year. No association between preoperative vessel diameters and primary-assisted or functional patency was observed. Interestingly, there was a significant negative association between previous ipsilateral access and achievement of primary patency with a 60% decrease in odds of achieving primary patency in patients with previous ipsilateral access [odds ratio 0.4, 95% confidence interval (CI) 0.1-0.9, P = 0.03]. There was also noted to be a significant association between the presence of an ipsilateral catheter and increased risk of subsequent abandonment of the AVG (hazard ratio 2.6, 95% CI 1.1-5.8, P = 0.02).

CONCLUSIONS

Prosthetic forearm loop AVGs remain hindered in their utility as they show high rates of graft failure within a year of creation. A significant patient-specific factor leading to this was not clearly demonstrated. As guidelines change regarding the nature of dialysis access for patients on HD, these results draw into question the utility of prosthetic forearm loop grafts in patients requiring long-term HD access.

Results of endovascular treatment of venous anastomotic stenosis in prosthetic arteriovenous for hemodialysis PTFE grafts. Comparative analysis between patent and occluded grafts

OBJECTIVE

To analyze the results of endovascular treatment of venous anastomotic stenosis (VAS) in humero-axillary arteriovenous grafts (HAG), comparing outcomes between patent and thrombosed HAG.

MATERIAL AND METHODS

A retrospective cohort study was made of endovascular treated patients because of a VAS in a HAG between January 2009 and December 2019. Group A: Thrombosed HAG secondary to a VAS. Group B: Patent HAG with a VAS detected during follow-up. Technical success was defined as residual stenosis after treatment <30%, and clinical success as satisfactory immediate dialysis after surgery. After ET a biannual clinical and ultrasound follow-up was performed.

STATISTICAL ANALYSIS

Survival analysis was performed for time-to-event data to assess patency.

RESULTS

Group A: 55 patients. Group B: 22. There were no significative differences in demographic and anatomical factors between groups. Technical and clinical success were 100% in group B and 94.5% and 91% respectively in group A. Primary patency at 1, 6 and 12 months was: Group A: 81.8%, 22.4% y 15.7% respectively. Group B: 100%, 85.9%, 76,4% (p < 0.001). Secondary patency at 1, 6 and 12 months was: Group A: 85.2%, 45.8% y 31.3% respectively. Group B 100%, 95.3%, 95.2% (p < 0.001). Use of non-covered stents was associated with an increased risk of occlusion (HR 2.669 IC 95% 1.146-6.216, p = 0.010).

CONCLUSION

A higher patency of EV performed on a patent HAG is expected. It is therefore advisable to develop surveillance programs that are capable to detect VAS before its occlusion.

The clinical outcome of balloon-assisted maturation procedure between autogenous radiocephalic fistula and brachiocephalic fistula in a single center experience

OBJECTIVE

Balloon-assisted maturation by an endovascular method plays an important role in treating an immature arteriovenous fistula. However, the results between radiocephalic fistula and brachiocephalic fistula were rarely reported. This retrospective study aimed to investigate the effectiveness and outcome of balloon-assisted maturation in different sites of autogenous arteriovenous fistulas.

METHODS

This single-center retrospective study included patients who underwent balloon-assisted maturation procedures from January 2015 to December 2016. Of 148 patients, 117 and 31 patients had a radiocephalic fistula and a brachiocephalic fistula, respectively. The primary outcome was balloon-assisted maturation success. Data regarding fistula lesions, balloon types and size, frequency of procedures, and maturation time were collected for balloon-assisted maturations. The secondary outcome was the patency of a fistula in the follow-up period.

RESULTS

No difference was observed in procedure of balloon-assisted maturation frequency between the radiocephalic and brachiocephalic fistula groups. The total success rate was 77.7%, without significant difference between radiocephalic and brachiocephalic fistula groups (81.20% vs. 64.50%; P=0.055). Within the procedures, the culprit lesion of juxta-anastomosis segment (73.5% vs. 25.5%, P<0.001) and arterial inlet (21.2% vs. 7.8%, P=0.04) were more common in the radiocephalic fistula group, whereas the venous outlet was more common in the brachiocephalic fistula group (88.2% vs. 57.7%, P<0.001). Both groups had an equivalent patency rate after the balloon-assisted maturation within the follow-up period (P=0.272).

CONCLUSIONS

Balloon-assisted maturation was an effective procedure for immature fistulas, without significant difference between the radiocephalic and brachiocephalic fistulas. Through the procedure, the culprit lesions causing non-maturation were found to be different between the two groups. The patency rate between the two groups after surgery seems to be equivalent within the follow-up period.

Anticoagulation Therapy is Associated with Increased Access-related Wound Infections after Hemodialysis Access Creation

BACKGROUND

The effect of anticoagulation therapy (AC) on hemodialysis access patency and related complications is not well defined. Patients on long-term or chronic AC due to their underlying comorbid conditions may be particularly susceptible to access-related bleeding and complications from repetitive cannulation. Our goal is to assess the effect of anticoagulation therapy on outcomes after access creation.

METHODS

The Vascular Quality Initiative (VQI) database was queried for patients undergoing arteriovenous fistula (AVF) or graft (AVG) placement, from 2011 to 2019. Only patients with data on post-procedural AC status were included. Anticoagulation use was defined as patients on warfarin, dabigatran, or rivaroxaban after access creation at postoperative follow up. Demographic and procedural details were analyzed. Wound infection and patency rates at six months were assessed. Binomial logistic regression analysis was performed to assess the association of anticoagulation use with these outcomes.

RESULTS

A total of 27,757 patients underwent access creation, with the majority undergoing AVF creation (78.8%). The average age was 61.4 years and 55.3% were male. 12.9% of patients were on postoperative AC. The wound infection rate was 2.3- 3.8% in the no AC and AC cohorts, respectively (P < 0.001). At six months follow-up, patency was 85.7- 84.3% in the no AC and AC cohorts, respectively (P = 0.044). Expectedly, grafts had lower patency rates compared to AVF; those within the no AC cohort had a patency of 83.0% compared to 81.2 % in those on AC (P = 0.106). On multivariable analysis, anticoagulation use was associated with a higher risk of wound infections (odds ratio [OR] 1.513, 95% confidence interval [CI] 1.160-1.973, P = 0.002). AC use did not significantly affect access patency.

CONCLUSION

Anticoagulation therapy was associated with a higher rate of wound infections but did not affect short-term access patency within six-months. These patients warrant close surveillance of their access for signs of infection. Furthermore, long-term implications of anticoagulation needs further evaluation.

A national cohort study on hemodialysis arteriovenous fistulas after kidney transplantation - long-term patency, use and complications

OBJECTIVE

To describe the long-term hemodialysis arteriovenous fistula (AVF) patency, incidence of AVF use, incidence and nature of AVF complications and surgery in patients after kidney transplantation.

PATIENTS AND METHODS

We retrospectively analysed the AVF outcome and complications in all adult kidney allograft recipients transplanted between January 1st, 2000 and December 31, 2015 with a functional AVF at the time of transplantation. Follow-up was until December 31, 2019.

RESULTS

We included 626 patients. Median AVF follow-up was 4.9 years. One month after kidney transplantation estimated AVF patency rate was 90%, at 1 year it was 82%, at 3 years it was 70% and at 5 years it was 61%; median estimated AVF patency was 7.9 years. The main cause of AVF failure was spontaneous thrombosis occurring in 76% of AVF failure cases, whereas 24% of AVFs were ligated or extirpated. In a Cox multivariate model female sex and grafts were independently associated with more frequent AVF thrombosis. AVF was used in about one third of our patients. AVF-related complications occurred in 29% of patients and included: growing aneurysms, complicated thrombosis, high-flow AVF, signs of distal hypoperfusion, venous hypertension, trauma of the AVF arm, or pain in the AVF/arm.

CONCLUSIONS

AVFs remain functional after kidney transplantation in the majority of patients and are often re-used after graft failure. AVF-related complications are common and require proper care.

Arteriovenous Fistula Formation with Adjuvant Endovascular Maturation

INTRODUCTION

The clinical utility of the native arteriovenous fistula (AVF) is limited by a prolonged time to maturation, low overall maturation rate, and subsequent abandonment. Endovascular intervention is increasingly accepted as first line therapy to treat AVF stenosis. The objective of this study was to evaluate AVF formation outcomes when early endovascular intervention was selectively performed to bring about timely AVF maturation.

METHODS

A retrospective study (February 2014- February 2020) was performed on 82 AVF consecutive patients (mean age 62.5±13.5 (17-83); 58 male (70.7%)) with end-stage renal failure who had Vascular Access (VA) construction at a single institution. Four year AVF patency, vascular diameters, haemodialysis parameters, re-intervention rate, and mortality were analysed.

RESULTS

Radiocephalic AVF was the most common fistula constructed (71 patients; 88.6%). Post formation evaluation (46.2+/-56.0 days (5-343)) revealed 33 (40.2%) immature AVFs. Subsequently, 19 patients underwent endovascular procedures consisting of angioplasty/stenting of the juxta-anastomosis, cannulation and/or outflow segments to bring about timely maturation of the AVF. Hence 93.9% of AVFs had reached functional patency (maturation) by 6 months post formation, with a mean time to maturation of 67.8 +/- 65.9 (5-320) days. After reaching maturation, Primary Access Functional Patency was 82 +/- 4.3 % at 6 months, 58+/- 5.5% at 12 months and 34 +/- 6.8% at 48 months. Primary Assisted Access Functional Patency was 95 +/- 2.4% at 6 months, 90 +/-3.3 % at 12 months and 83 % +/- 4.7 % at 48 months. 121 endovascular interventions were performed to maintain patency, equating to an endovascular reintervention rate of .37 procedures/patient year. Mean arterial, venous and brachial flow rates did not change significantly after maturation with a mean fistula (primary assisted functional patency) survival time of 5.9 +/- 0.26 (5.33- 6.36) years from maturation. Only 12 thromboses occurred after the first post formation follow up review, which were all salvaged using endovascular techniques leading to 100% Total secondary functional patency at 4 years. 5 year estimated all-cause mortality was 45.6 +/-12.7%.

CONCLUSION

Arteriovenous fistula maturation rate and time to maturation can be improved when early endovascular intervention is selectively performed post formation. This allows for near universal maturation where, once matured, the use of ongoing endovascular re-intervention allows for a low re-intervention rate and long term patency providing for reliable long term renal vascular access.

Results of endovascular treatment of venous anastomotic stenosis in prosthetic arteriovenous for hemodialysis PTFE grafts. Comparative analysis between patent and occluded grafts

OBJECTIVE

To analyze the results of endovascular treatment of venous anastomotic stenosis (VAS) in humero-axillary arteriovenous grafts (HAG), comparing outcomes between patent and thrombosed HAG.

MATERIAL AND METHODS

A retrospective cohort study was made of endovascular treated patients because of a VAS in a HAG between January 2009 and December 2019. Group A: Thrombosed HAG secondary to a VAS. Group B: Patent HAG with a VAS detected during follow-up. Technical success was defined as residual stenosis after treatment <30%, and clinical success as satisfactory immediate dialysis after surgery. After ET a biannual clinical and ultrasound follow-up was performed.

STATISTICAL ANALYSIS

Survival analysis was performed for time-to-event data to assess patency.

RESULTS

Group A: 55 patients. Group B: 22. There were no significative differences in demographic and anatomical factors between groups. Technical and clinical success were 100% in Group B and 94.5% and 91% respectively in Group A. Primary patency at 1, 6 and 12 months was: Group A: 81.8%, 22.4% and 15.7% respectively. Group B: 100%, 85.9%, 76.4% (p<0.001). Secondary patency at 1, 6 and 12 months was: Group A: 85.2%, 45.8% and 31.3% respectively. Group B 100%, 95.3%, 95.2% (p<0.001). Use of non-covered stents was associated with an increased risk of occlusion (HR 2.669 95% CI 1.146-6.216, p=0.010).

CONCLUSION

A higher patency of EV performed on a patent HAG is expected. It is therefore advisable to develop surveillance programs that are capable to detect VAS before its occlusion.

Tailoring of arteriovenous graft-to-vein anastomosis angle to attenuate pathological flow fields

Arteriovenous grafts are routinely placed to facilitate hemodialysis in patients with end stage renal disease. These grafts are conduits between higher pressure arteries and lower pressure veins. The connection on the vein end of the graft, known as the graft-to-vein anastomosis, fails frequently and chronically due to high rates of stenosis and thrombosis. These failures are widely believed to be associated with pathologically high and low flow shear strain rates at the graft-to-vein anastomosis. We hypothesized that consistent with pipe flow dynamics and prior work exploring vein-to-artery anastomosis angles in arteriovenous fistulas, altering the graft-to-vein anastomosis angle can reduce the incidence of pathological shear rate fields. We tested this via computational fluid dynamic simulations of idealized arteriovenous grafts, using the Bird-Carreau constitutive law for blood. We observed that low graft-to-vein anastomosis angles ([Formula: see text]) led to increased incidence of pathologically low shear rates, and that high graft-to-vein anastomosis angles ([Formula: see text]) led to increased incidence of pathologically high shear rates. Optimizations predicted that an intermediate  ([Formula: see text]) graft-to-anastomosis angle was optimal. Our study demonstrates that graft-to-vein anastomosis angles can significantly impact pathological flow fields, and can be optimized to substantially improve arteriovenous graft patency rates.

Predialysis nephrology care amongst Palestinian hemodialysis patients and its impact on initial vascular access type

Referral time for end-stage renal disease (ESRD) patients to nephrologists and initial vascular access method are considered significant factors that impact health outcomes at the time of hemodialysis (HD) initiation. Native arteriovenous fistula (AVF) is strongly recommended as initial access. However, little is known about the referral rate among ESRD receiving HD in Palestine and its correlation with AVF creation. In Ramallah Hemodialysis Center, we investigated the pre-dialysis nephrology care and AVF usage in 156 patients. Type of access at HD initiation was temporary central venous catheter (CVC) in 114 (73%), tunneled hemodialysis catheter (TDC) in 21 (13%) and AVF in 21 (13%). Out of all participants, 120 (77%) were seen by nephrologist prior to dialysis. Of the participants who initiated dialysis with a CVC, 36 (31%) had not received prior nephrology care. All participants who initiated dialysis with functional AVF had received prior nephrology care. Patients who were not seen by a nephrologist prior to HD initiation had no chance at starting HD with AVF, whereas 17% of those who had nephrology care >12 months started with AVF. In conclusion, a relatively large percentage of Palestinian HD patients who were maintained on HD did not have any predialysis nephrology care. In addition, patients who received predialysis nephrology care were significantly more likely to start their HD through AVF whereas all those without predialysis nephrology care started through CVC. More in-depth national studies focusing on improving nephrology referral in ESRD patients are needed to increase AVF utilization.

Effect of pore size and spacing on neovascularization of a biodegradble shape memory polymer perivascular wrap

Neointimal hyperplasia (NH) is a main source of failures in arteriovenous fistulas and vascular grafts. Several studies have demonstrated the promise of perivascular wraps to reduce NH via promotion of adventitial neovascularization and providing mechanical support. Limited clinical success thus far may be due to inappropriate material selection (e.g., nondegradable, too stiff) and geometric design (e.g., pore size and spacing, diameter). The influence of pore size and spacing on implant neovascularization is investigated here for a new biodegradable, thermoresponsive shape memory polymer (SMP) perivascular wrap. Following an initial pilot, 21 mice were each implanted with six scaffolds: four candidate SMP macroporous designs (a-d), a nonporous SMP control (e), and microporous GORETEX (f). Mice were sacrificed after 4 (N = 5), 14 (N = 8), and 28 (N = 8) days. There was a statistically significant increase in neovascularization score between all macroporous groups compared to nonporous SMP (p < .023) and microporous GORETEX (p < .007) controls at Day 28. Wider-spaced, smaller-sized pore designs (223 μm-spaced, 640 μm-diameter Design c) induced the most robust angiogenic response, with greater microvessel number (p < .0114) and area (p < .0055) than nonporous SMPs and GORETEX at Day 28. This design also produced significantly greater microvessel density than nonporous SMPs (p = 0.0028) and a smaller-spaced, larger-sized pore (155 μm-spaced, 1,180 μm-sized Design b) design (p = .0013). Strong neovascularization is expected to reduce NH, motivating further investigation of this SMP wrap with controlled pore spacing and size in more advanced arteriovenous models.

Challenges and Possibilities of Cell-Based Tissue-Engineered Vascular Grafts

There is urgent demand for biologically compatible vascular grafts for both adult and pediatric patients. The utility of conventional nonbiodegradable materials is limited because of their thrombogenicity and inability to grow, while autologous vascular grafts involve considerable disadvantages, including the invasive procedures required to obtain these healthy vessels from patients and insufficient availability in patients with systemic atherosclerosis. All of these issues could be overcome by tissue-engineered vascular grafts (TEVGs). A large body of evidence has recently emerged in support of TEVG technologies, introducing diverse cell sources (e.g., somatic cells and stem cells) and novel fabrication methods (e.g., scaffold-guided and self-assembled approaches). Before TEVG can be applied in a clinical setting, however, several aspects of the technology must be improved, such as the feasibility of obtaining cells, their biocompatibility and mechanical properties, and the time needed for fabrication, while the safety of supplemented materials, the patency and nonthrombogenicity of TEVGs, their growth potential, and the long-term influence of implanted TEVGs in the body must be assessed. Although recent advances in TEVG fabrication have yielded promising results, more research is needed to achieve the most feasible methods for generating optimal TEVGs. This article reviews multiple aspects of TEVG fabrication, including mechanical requirements, extracellular matrix components, cell sources, and tissue engineering approaches. The potential of periodic hydrostatic pressurization in the production of scaffold-free TEVGs with optimal elasticity and stiffness is also discussed. In the future, the integration of multiple technologies is expected to enable improved TEVG performance.

Dialysis access intervention: Techniques for the interventional cardiologist

Interventional cardiologists who treat malfunctioning hemodialysis accesses play an important role in the life of patients with end-stage kidney disease (ESKD). By collaborating with interventional nephrologists who currently perform the bulk of routine access angiographic procedures, interventional cardiologists can fill an important gap in the care of ESKD patients by performing urgent or emergent procedures that fall outside the schedule of an outpatient interventional nephrology laboratory to ensure that hemodialysis patients will not miss a hemodialysis session or get a temporary catheter. This paper reviews the pathophysiology of dialysis access failure and illustrates the catheter-based approaches used by interventional cardiologists to treat malfunctioning dialysis accesses.

Midterm results of salvage surgery for autogenous dialysis access in aneurysmal arteriovenous fistulas

Autologous arteriovenous fistulas are commonly constructed in patients undergoing hemodialysis for end-stage renal disease. However, they are associated with a high rate of aneurysm formation, and aneurysmal arteriovenous fistulas that have become symptomatic require surgical intervention. This study was performed to evaluate the midterm results of salvage surgery for autogenous dialysis access in patients with aneurysmal arteriovenous fistulas. Of 1326 arteriovenous fistula operations, 81 involving surgery for aneurysmal arteriovenous fistulas between January 2008 and January 2012 were included in this study. The database was searched to identify all complicated arteriovenous fistula patients undergoing surgery for vascular access. The number of complicated arteriovenous fistula surgeries, for example for aneurysms, was greater than the number of patients undergoing surgery to create a new arteriovenous fistula. We performed three different surgical procedures to treat arteriovenous-related aneurysms in our clinic: primary repair, resection and saphenous vein interposition, and resection and polytetrafluoroethylene (PTFE) interposition. We compared the patency rates at the 12- and 24-month follow-ups among these three techniques. The study population consisted of 24 cases of primary repair, 29 cases of resection and saphenous vein interposition, and 30 cases of resection and PTFE graft interposition. True aneurysms occurring in patients undergoing hemodialysis did not require treatment unless they were symptomatic. Arteriovenous access salvage therapy is recommended after the aneurysm has become symptomatic. Symptomatic arteriovenous fistula aneurysms can be treated by maintaining arteriovenous fistula continuity. Moreover, patient safety is ensured by long-term patency.

Perceived barriers and attitudes toward arteriovenous fistula creation and use in hemodialysis patients in Palestine

In the dialysis center in Ramallah, we investigated the attitudes and perceived barriers to having arteriovenous fistula (AVF) in 156 patients. The current method of HD access was AVF in 52% and central venous catheter in 47%. Perceived causes of no or delayed AVF were: patient’s refusal of AVF in 54.5%, late referral to a surgical evaluation in 31.3% and too long to surgical appointments in 14.2%. Among those who refused AVF, reasons were: concern about the surgical procedure in 42.5%, poor understanding of disease/access in 23.3%, fear of needles in 15.1%, denial of disease or need for HD in 17.8%, and cosmetic reasons in 1.4%. Forty six percent of patients believed they received education about AVF prior to the creation of HD access, and 73.7% would recommend AVF as the method of access due to the lower risk of infection (96%), easier to care for (16%), easier showering (14%), and better-associated hygiene (3%). In conclusion, the majority would recommend an AVF as the mode of vascular access for HD. The most common barrier to having an AVF was patient’s refusal to undergo AVF creation because of their concern about the surgical procedure. A systematic evaluation of the process that precedes the creation of AVF may allow for better utilization.

Patency of ePTFE Arteriovenous Graft Placements in Hemodialysis Patients: Systematic Literature Review and Meta-Analysis

Arteriovenous grafts (AVGs) are an appropriate option for vascular access in certain hemodialysis patients. Expanded polytetrafluoroethylene (ePTFE) has become the dominant material for such grafts, due in part to innovations in graft design and surgical interventions to reduce complications and improve patency rates. Comprehensive evidence syntheses have not been conducted to update AVG performance in an era in which both access choice and ePTFE graft functioning may have changed. We conducted a systematic review and meta-analysis summarizing outcomes from recent studies of ePTFE AVGs in hemodialysis, following PRISMA standards. Literature searches were conducted in multiple databases to identify observational and interventional studies of AVG patency and infection risk. Primary, primary-assisted, and secondary patency rates were analyzed at 6, 12, 18, and 24 months postplacement. Kaplan-Meier graft survival plots were digitized to recreate individual patient-level data. Patency rates were pooled using a random effects model. We identified 32 studies meeting our selection criteria that were published from 2004 through 2019. A total of 38 study arms of ePTFE grafts were included, representing 3381 AVG accesses placed. The mean primary, primary-assisted, and secondary patency rates at 1 year were 41% (95% CI, 35% to 47%), 46% (95% CI, 41% to 51%), and 70% (95% CI, 64% to 75%), respectively. Mean 24-month patency rates were 28% (95% CI, 22% to 33%), 34% (95% CI, 27% to 41%), and 54% (95% CI, 47% to 61%), respectively. A high degree of heterogeneity across studies was observed. Overall risk of infection was not consistently reported, but among available studies the pooled estimate was 9% per patient-year (95% CI, 6% to 12%). This meta-analysis provides an up-to-date estimate of the performance of ePTFE AVGs, within the context of improved graft designs and improved interventional techniques.

Inferiority of arteriovenous grafts, in comparison to autogenous fistulas, is underestimated by standard survival measures alone

BACKGROUND

It has been argued that a prosthetic arteriovenous graft (AVG) is a reasonable alternative to an arteriovenous fistula (AVF) for dialysis. We aimed to compare the patency rates and requirements for the intervention of newly formed AVF and AVG.

METHODS

A retrospective analysis was undertaken of AVF and AVG formed between 1 January 2013 and 31 December 2015 at two tertiary referral centres and followed up until 31 December 2017. Outcome measures included successful use for dialysis, patency rates and the number of interventions required to maintain dialysis access per patient-year (PPY).

RESULTS

Four hundred and seventy AVF and 92 AVG were constructed. Of 470 AVF, 324 (68.9%) were used compared to 80 of 92 (87%) AVG. One year assisted primary patency of AVF was 75% (confidence interval 71-79%) compared to 47% (confidence interval 36-57%) for AVG. Secondary patency rates for AVF at 1, 2 and 3 years were 77%, 71% and 69%, respectively. At the same time points, secondary patency rates for AVG were 77%, 60% and 46%, respectively (log rank P = 0.034). AVG required 2.4 times the number of interventions PPY than AVF. Surgical thrombectomy of AVG was at a rate of 0.49 PPY compared with 0.042 PPY for AVF.

CONCLUSION

AVG have a substantially higher rate of thrombosis than AVF, evident from early in the life of the graft. AVF demonstrate superior patency rates to AVG throughout the life of the access, with far fewer interventions PPY than grafts.

Outcome of GORE® ACUSEAL graft for brachial-axillary vascular access in chronic haemodialysis patients: Cohort retrospective single-centre study

Background

The aim of this study was to evaluate the midterm results of a brachio-axillary arteriovenous graft (BA-AVG) for the provision of vascular access haemodialysis patients.

Materials and methods

A cohort retrospective consecutive single-centre study of 46 patients undergoing BA-AVG using the Gore Acuseal, from November 2015 to October 2019 was conducted. Data on patient demographics, comorbidities, medical therapy, and complications were collated for the initial endpoints of primary patency, primary assisted patency, and secondary patency. A subgroup analysis included outcomes in patients over 70 years old and events (complications) per AVG per year. Data were subjected to Kaplan-Meier survival estimator with log-rank analysis and test of probability.

Results

The mean age of the cohort was 63.5 years with male predominance (male, n = 27, 59%). A total of 37 (80%) patient procedures were conducted with elective settings as well as on an emergency basis with a 91.3% technical success rate. The most common complication was grade I steal syndrome (8.7%), followed by graft infections (4.3%), median nerve neuropraxia (4.3%), and postoperative bleeding (2%), demonstrating a 0.1 per AVG complication per 2 years. Median primary patency, primary assisted patency, and secondary patency over a mean follow-up period of 28 months was 5.5, 12.5, and 18 months, respectively, with no associated 30-day mortality.

Conclusion

BA-AVG with midterm longevity and low complications may serve as an alternative access type when a suitable site is not identified. The AVG patency rate in the elderly or patients with limited life expectancy is promising. However, more robust data are needed to confirm the benefit of AVG in this cohort.

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This series showed that Gore® Acuseal graft can be used as vascular access option in ESRD patients on chronic haemodialysis.

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It has reasonable technical success rate comparable to other synthetic access grafts and low complications rates in mid to long-term follow up.

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Sub-groups analysis included outcome in patients over 70 years old and events (complications) per AVG per year.

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AVG patency rate in elderly or patients with limited life expectancy is promising. However, more robust data needed.

Upper extremity reconstruction following open surgical repair of giant arteriovenous fistula aneurysm: clinical case and systematic review of the literature

Background:

Nearly 30% of arteriovenous fistulas (AVFs) located in the upper extremity for hemodialysis access result in short- and long-term adverse effects, such as rupture, necessitating emergent surgical management and extensive soft-tissue reconstruction. With this systematic review, we aimed to compile all reported open surgical techniques used for complicated AVF repair in the upper extremity, the respective soft-tissue reconstructive outcomes, and vascular patency rates at final follow-up.

Methods:

Using Ovid Medline/PubMed databases, we conducted a review of the English-language literature on AVF aneurysm surgical management in the upper extremity, filtered for relevance to open surgical technique and outcomes in vascular patency after aneurysmal repair at long-term follow-up (≥6 months postoperatively). We include a detailed case of surgical removal of a giant AVF aneurysm and subsequent flap elevation and reconstruction of the upper extremity.

Results:

Of 150 articles found in the initial search, 19 (from 2010-2017) met inclusion criteria. From the reviewed studies, 675 patients underwent open surgical repair of AVF aneurysm in the upper extremity. Surgical approaches included partial-to-full aneurysm excision, interposition graft, tubularized extracellular matrix, sutured and stapled aneurysmorrhaphy, and stent graft. Rates of vascular patency at repair site ranged from 47% to 100%, with a pooled average of 78% at 6 months or longer postoperatively.

Conclusions:

For plastic and hand surgeons, aneurysmal ligation and excision is feasible even in severe cases and is associated with overall good vascular and soft-tissue reconstructive outcomes in the upper extremity. (www.actabiomedica.it)

Reliability of preoperative venous mapping ultrasonography in predicting for autogenous arteriovenous fistula maturation

BACKGROUND

Autogenous arteriovenous fistula creation is the preferred route for vascular access for hemodialysis. Although preoperative venous mapping ultrasonography has been advocated as an operative planning adjunct and recently incorporated into the Society for Vascular Surgery clinical guidelines, controversy remains regarding its usefulness for predicting access success. The purpose of the present retrospective clinical study was to test the hypothesis that vein size measured on routine preoperative venous mapping is a poor predictor of primary fistula maturation.

METHODS

Consecutive upper extremity autogenous arteriovenous fistulas created by three dedicated vascular surgeons were retrospectively reviewed. The demographic characteristics, preoperative venous mapping, functional maturation, and patency were analyzed. The clinically relevant variables were tested for predictive significance using a logistic regression model.

RESULTS

A total of 199 upper extremity autogenous arteriovenous fistulas had been created during a 5-year period. Patients were aged 70 ± 16 years (range, 20-96 years), and 62% were men. Most had already been undergoing dialysis before fistula creation (83%), usually via a tunneled central venous catheter (62%). Radial-cephalic, brachial-cephalic, and brachial-basilic arteriovenous fistulas had been created in 82 patients (41%), 76 patients (38%), and 10 patients (5%), respectively. Fistula maturation, defined as a palpable thrill and/or successful cannulation of the fistula with the ability to deliver a flow rate of 400 mL/min, was achieved in 67% of the patients. A higher body mass index was associated with nonmaturation on both univariate and multivariate analyses (success, 28.6 ± 7.7 kg/m²; vs failed, 31.6 ± 9.4 kg/m²; P = .029; odds ratio [OR], 1.06; 95% confidence interval [CI], 1.02-1.10; P < .01). On univariate analysis, the maximum target vein diameter assessed by preoperative venous mapping was slightly larger in the group achieving successful maturation (2.9 ± 1.1 mm vs 2.6 ± 0.9 mm; P = .014). However, neither the maximum target vein diameter nor a target vein size >3 mm was significantly predictive of maturation on multivariate analysis (maximum vein diameter: OR, 0.65; 95% CI, 0.35-1.22; P = .176; vein size >3 mm: OR, 0.91; 95% CI, 0.32-2.60; P = .857). After a median follow-up of 15 months (interquartile range, 26 months), the primary functional patency, primary-assisted patency, and secondary patency rates were 39.1% ± 0.6%, 94.5% ± 0.6%, and 97.9% ± 0.5%. No association of vein diameter with long-term patency was found.

CONCLUSIONS

Despite the national fistula-first initiatives, most patients still undergo access via catheter at the initiation of hemodialysis. The use of routine preoperative venous mapping does not predict successful primary maturation. Also, no clinically useful predictor of fistula maturation was identified in the present study.

Flow Complexity Estimation in Dysfunctional Arteriovenous Dialysis Fistulas using Vector Flow Imaging

Non-invasive assessment is preferred for monitoring arteriovenous dialysis fistulas (AVFs). Vector concentration assesses flow complexity, which may correlate with stenosis severity. We determined whether vector concentration could assess stenosis severity in dysfunctional AVFs. Vector concentration was estimated in four stenotic phantoms at different pulse repetition frequencies. Spectral Doppler peak velocity and vector concentration were measured in 12 patients with dysfunctional AVFs. Additionally, 5 patients underwent digital subtraction angiography (DSA). In phantoms, vector concentration exhibited an inverse relationship with stenosis severity and was less affected by aliasing in severe stenoses. In nine stenoses of 5 patients undergoing DSA, vector concentration correlated strongly with stenosis severity (first stenosis: r = -0.73, p = 0.04; other stenoses; r = -0.69, p = 0.02) and mid-stenotic diameter (first stenosis: r = 0.87, p = 0.006; other stenoses: r = 0.70, p = 0.02) as opposed to peak velocities (p > 0.05). Vector concentration is less affected by aliasing in severe stenoses and correlates with DSA in patients with dysfunctional AVF.

Upper Arm Arteriovenous Grafts are Superior over Forearm Arteriovenous Grafts in Upper Extremity Dialysis Access

BACKGROUND

In this study, we compared the outcomes of forearm arteriovenous grafts (AVGs) and upper arm AVGs in a large, prospectively collected data set, which represents real-world experience with upper extremity prosthetic dialysis access, to determine if there are clinically significant differences in the upper arm and forearm positions.

METHODS

We identified 2,063 patients who received upper extremity AVGs within the Vascular Quality Initiative data set (2010-2018). Axillary to axillary upper arm AVGs were excluded (n = 394) from the analysis. The main outcome measures were primary and secondary patency rates at 12 months. Other outcomes were 6-month wound infection, steal syndrome, and arm swelling. The log-rank test was used to evaluate patency loss using a Kaplan-Meier analysis. Cox proportional hazards models were used to examine adjusted association between locations (forearm and upper arm) and outcomes.

RESULTS

There were 1,160 forearm AVGs and 509 upper arm brachial artery AVGs in the study cohort. Patients with forearm AVGs were more likely to have a body mass index > 30 (45% vs. 38%, P = 0.013), no history of previous access (73% vs. 63%, P < 0.001), and underwent local-regional anesthesia (56% vs. 43%, P < 0.001). The 12-month primary patency (51.5% vs. 62.9%, P < 0.001) and secondary patency (76.4% vs. 89.1%, P < 0.001) were significantly lower for forearm AVGs. Wound infection, steal syndrome, and arm swelling were similar between forearm AVGs and upper arm AVGs at the 6-month follow-up. In multivariable analysis, the primary patency loss (adjusted hazard ratio (aHR) 1.66, 95% confidence interval (CI) 1.33-2.01, P < 0.001) and 12-month secondary patency loss (aHR 2.71, 95% CI 1.84-3.98, P < 0.001) were significantly higher for forearm AVGs at 12 months.

CONCLUSIONS

From this observational study of the Vascular Quality Initiative data set, the primary and secondary patency rates were superior for upper arm brachial artery AVGs compared with forearm AVGs.

Systemic lupus erythematosus diagnosis impacts clinical outcomes of arteriovenous fistulas in comparison to other end-stage renal disease etiologies

OBJECTIVES

Arteriovenous fistulas primary patency at one-year occurs in 43-85% of the patients with end-stage renal disease. The diagnosis attributable to end-stage renal disease has been suggested to impact arteriovenous fistulas outcomes. The objective was to compare primary patency at one week, 1, 3, 6, and 12 months of follow-ups, among systemic lupus erythematosus patients and two control groups; additionally, we evaluated the impact of systemic lupus erythematosus to predict early patency loss.

METHODS

A retrospective review of charts from arteriovenous fistulas created between 2008 and 2017 was performed. One-hundred thirty-four patients were identified and classified according to end-stage renal disease attributable diagnosis as: systemic lupus erythematosus cases (N = 14), control-group-1 (91 patients with primarily diabetes and hypertension), and control-group-2 (29 patients with idiopathic end-stage renal disease). A case-control matched design (1:2:1) was proposed. Logistic regression analysis and Kaplan-Meier curves were used. Institutional Review Board approval was obtained.

RESULTS

More systemic lupus erythematosus patients lost primary patency at 3 (28.6%) and 12 months (71.4%) than patients from control-groups-1 (vs. 3.6% and 35.7%, respectively) and -2 (vs. 0% and 14.3%, respectively), (p ≤ 0.011 for both). Days of primary patency survival were shorter in systemic lupus erythematosus patients (p = 0.003). Systemic lupus erythematosus diagnosis was the only factor associated with early patency loss, HR: 3.141, 95%CI: 1.161-8.493 (systemic lupus erythematosus diagnosis vs. control-group-1) and HR: 12.582, 95%CI: 1.582-100.035 (systemic lupus erythematosus diagnosis vs. control-group-2).

CONCLUSIONS

Diagnosis attributable to end-stage renal disease has a major impact on arteriovenous fistula outcomes in patients. Systemic lupus erythematosus patients have an increased risk of arteriovenous fistulas patency loss within the first six months of follow-up. Patients with idiopathic end-stage renal disease had an excellent one year arteriovenous fistula patency survival.

Hybrid procedures in the dialysis fistula aneurysm treatment

OBJECTIVES

Dialysis fistula aneurysms are common complications which in selective cases require surgical revision. It is recommended to detect and treat outflow stenosis concurrent with a dialysis fistula aneurysm, but usually, the treatment is divided into two stages - the open and endovascular stages are performed separately. We describe the results of hybrid procedures composed of aneurysm resection and endovascular correction for outflow veins performed for a dialysis fistula aneurysm treatment.

METHODS

From March 2012, we performed hybrid procedures in 28 patients to correct dialysis fistula aneurysms. Patients, dialysis access, operative data, and the results obtained during a median follow-up of 28.5 months were analyzed.

RESULTS

For dialysis fistula aneurysm correction, we performed 27 bypasses and 1 aneurysmorraphy. For outflow vein stenosis correction, we performed standard balloon angioplasty, no stents or stentgraft were used. The average increase in minimal diameter after angioplasty was 135.5% (range 57-275%). The 12- and 24-month primary patency rates of corrected fistulas in the observed group were 92.3% and 80%, respectively. A significant difference in the one-year patency rates between the urgent and planned procedures was observed (81.2% vs. 100%, respectively). No early complications related to endovascular or open procedures were observed. Late complications were observed in seven patients (25%) - mainly thrombosis caused by the recurrence of outflow vein stenosis (six patients, 21.5%), infection, lymphocele, and hematoma (one case of each complication).

CONCLUSIONS

A hybrid procedure for the surgical correction of dialysis fistula aneurysms with the simultaneous correction of outflow pathologies enables effective long-term treatment. The obtained data showed the efficiency and good results of this procedure. Procedures performed for urgent indications significantly increase the risk for later complications, especially fistula thrombosis and loss of dialysis access.

Comparison between bovine carotid artery graft and polytetrafluoroethylene graft for haemodialysis vascular access: A systematic review and meta-analysis

BACKGROUND

There is a renewed interest in using bovine carotid artery grafts for haemodialysis vascular access after recent advances in conduit manufacturing and endovascular management of access-related complications. Our aim was to summarize the results of the recent studies comparing bovine carotid artery grafts with polytetrafluoroethylene grafts as vascular access for haemodialysis.

METHODS

A systematic review was conducted for original articles comparing bovine carotid artery with polytetrafluoroethylene grafts for haemodialysis vascular access published between January 2000 and December 2019 searching the databases of Medline, Scopus, Google Scholar, ClinicalTrials.gov and the Cochrane Central Register of Controlled Trials.

RESULTS

Four studies were included (one prospective randomized controlled trial and three retrospective studies) with 676 patients in total (bovine carotid artery: 395, polytetrafluoroethylene: 281). There was lower graft infection rate per patient-year in bovine carotid artery grafts (mean difference: -0.03, p < 0.0001). Bovine carotid artery grafts required fewer interventions per patient-year to maintain or restore patency (mean difference: -0.81, p = 0.002). No significant difference was detected regarding pseudoaneurysm formation (p = 0.24), steal syndrome (p = 0.11) or patency rates (primary: 1 year: p = 0.15, 2 years: p = 0.69; primary assisted: 1 year: p = 0.18, 2 years: p = 0.54; secondary: 1 year: p = 0.22, 2 years: p = 0.17).

CONCLUSION

Bovine carotid artery and polytetrafluoroethylene grafts have similar short-term and long-term outcomes, with a possible advantage of bovine carotid artery grafts concerning graft infections and number of required interventions. Thus, bovine carotid artery grafts can be a useful alternative modality for haemodialysis vascular access.

Clinical Value of Intraoperative Flow Measurements of Brachiocephalic Arteriovenous Fistulas for Hemodialysis

Background

The aim of this study was to analyze the clinical outcomes of autogenous brachiocephalic arteriovenous fistulas and to investigate the factors associated with 1-year patency after initiation of hemodialysis.

Methods

We retrospectively reviewed the medical records of 41 patients who underwent surgery to create an autogenous brachiocephalic arteriovenous fistula between January 2015 and December 2017, received hemodialysis at the same hospital for longer than 1 year, and were monitored for their vascular access status. Intraoperative flow was measured using transit-time ultrasonography.

Results

The 1-year primary and secondary patency rates were 61% (n=25) and 87.8% (n=36), respectively. The functional group (subjects who required no intervention to maintain patency within the first year after hemodialysis initiation) displayed a significantly higher median intraoperative flow rate (450 mL/min) than the non-functional group (subjects who required intervention at least once regardless of 1-year patency) (275 mL/min) (p=0.038). Based on a receiver operating characteristic curve analysis, all patients were additionally subdivided into a high-flow group (>240 mL/min) and a low-flow group (≤240 mL/min). The high-flow group included a significantly greater number of functional brachiocephalic arteriovenous fistulas than the low-flow group (74.2% vs. 20%, respectively; p=0.007).

Conclusion

Transit-time flow, as measured with intraoperative transit-time ultrasonography, was associated with patency without the need for intervention at 1 year after initiation of hemodialysis.