Arteriovenous Graft Research Articles

Patency of tertiary vascular access in hemodialysis patients: case series

Background: Transposed brachio-basilic arteriovenous fistula (TBB-AVF) or arteriovenous graft (AVG) can be considered when primary and secondary vascular access options have been exhausted. Evidence that compared both procedures remains scarce. We aimed to report and describe the effectiveness of TBB-AVF and AVG as tertiary vascular access, reviewing literature about the advantages of each procedure. Case Presentation: We presented a series of end-stage renal disease (ESRD) patients needing tertiary vascular access to compare each procedure's effectiveness. Our study included 17 patients with ESRD and multiple vascular access failures who needed tertiary vascular access for hemodialysis between January 2019 and August 2022. Patency in 6 months and 1 year were compared between TBB-AVF and AVG using the Kaplan-Meier curve. The early failure rate was 14.4% for TBB-AVF and 87.5% for AVG. TBB-AVF had a better patency rate than AVG (p=0.005; log-rank). Cumulative patency rates in six months and one year were 91.7% and 85.7% for TBB-AVF compared to 87.5% and 16.7% for AVG, respectively. Conclusion: The creation of TBB-AVF should only be suggested if primary and secondary vascular access options have been exhausted. The TBB-AVF was more effective in functional patency than AVG as tertiary vascular access.

Evaluation of outcomes with permanent vascular access in an elderly Korean population based on the National Health Insurance Service database.

As nearly half of patients with end-stage kidney disease (ESKD) who initiate hemodialysis (HD) are over 65 years old (commonly defined as elderly), the fistula first strategy is controversial even in HD patients ≥65 years. In Korea's National Health Insurance Service database from 2008 to 2019, 41,989 elderly (≥ 65 years) HD patients were retrospectively reviewed to identify their clinical characteristics and outcomes. Vascular access (VA) patencies, risk factors associated with patencies and patient survival between arteriovenous fistula (AVF) and arteriovenous graft (AVG) were compared. Elderly AVF group (n=28,467) had superior primary, primary assisted, and secondary patencies than elderly AVG group (n=13,522) (all p values are <0.001). Patient survival was also better in the elderly AVF group than in the elderly AVG (p < 0.001). In multivariate Cox regression analyses for diverse outcomes, AVG (vs. AVF) was identified as a risk factor for all-cause mortality (adjusted hazard ratio [HR]: 1.307; 95% confidence interval [CI]: 1.272-1.343; p < 0.001), primary patency (adjusted HR: 1.745; 95% CI: 1.701-1.790; p < 0.001), primary-assisted patency (adjusted HR: 2.163; 95% CI: 2.095-2.233; p < 0.001), and secondary patency (adjusted HR: 3.718; 95% CI: 3.533-3.913; p < 0.001). Our study demonstrated that as a permanent VA for HD, AVF should be strongly considered in elderly (≥ 65 years) ESKD Korean patients. The age limit for AVF creation in ESKD patients should be adjusted more upward.

Management of infected arteriovenous grafts for haemodialysis: Outcomes and strategies using a novel objective scoring system.

In haemodialysis patients with exhausted autogenous options, prosthetic arteriovenous grafts (AVGs) are frequently utilised as tertiary vascular access. However, the prosthetic nature of AVGs precipitates an increased risk of infection which may translate to excess morbidity and life-threatening complications. The current evidence remains divided on the optimal treatment strategy for arteriovenous graft infections (AVGi) with arguments for conservative management by antibiotics, salvaging with graft revision or total/subtotal excision. To address this gap, we assessed the outcomes of AVGi patients treated in our institution, developing an AVGi severity classification model and a proposed treatment algorithm to guide AVGi management. We conducted a single centre retrospective review of outcomes of patients with AVGi managed either by sole antibiotics therapy, graft revision or surgical excision between June 2016 and May 2021. Outcomes of AVGi patients across differing treatment groups were compared, including 1-year mortality, 6-month and 1-year functional vascular access. We also analysed the outcomes of tunnelled haemodialysis lines (THL), which were used as a temporary vascular access in several AVGi patients in our study. A total of 34 AVGi patients were managed within that time frame and included in the study (5 conservatively management by antibiotics, 5 graft revisions and 24 surgical excision) with a mean age of 60.4 ± 14.4 years (67.6% males). Overall 1-year mortality was 14.7%. A 6-month functional vascular access status across the three groups stood at 60%, 60% and 10% while 1-year functional vascular access status was 60%, 75% and 42% respectively. When clinically appropriate, conservative management by antibiotics or salvage/graft revision can present as prudent AVGi treatment options. The adoption of our proposed severity classification system and treatment algorithm provides a more thorough objective assessment of the infection and helps guide the clinical decision-making process.

SUPERA stent placement for salvaging early recurrent arteriovenous graft thrombosis after percutaneous transluminal angioplasty: A single-center study.

The aim of this study was to evaluate the patency of the helical interwoven SUPERA stent for salvaging prosthetic arteriovenous (AV) grafts with rapidly recurrent thrombotic occlusion developed within a short time period after successful percutaneous transluminal angioplasty. From December 2019 to September 2021, the data of 20 patients with AV graft who had the SUPERA stent inserted satisfying the following conditions were consecutively collected. (1) More than 1 year has passed since the AV access operation; (2) Thrombotic re-occlusion of AV graft occurred within 3 months after previous successful endovascular treatment; (3) Residual stenosis is greater than 30% after full effacement of balloon angioplasty in the primary lesion. Post-interventional target lesion primary patency (TLPP), access circuit primary patency (ACPP), and secondary patency (SP) were calculated. Primary lesions of early recurrent arteriovenous graft thrombosis were found in 13 patients with graft-vein anastomosis, six patients with intra-graft stenosis, and one patient with outflow vein complications. The lesions showed residual stenosis in 47.4% (interquartile range: 44.1%-55.3%) of patients despite full-effacement balloon angioplasty. Clinical success was achieved in all patients with full-expansion of the stents at the 1-month follow-up. The TLPP was 70.7% and 32% at 6 and 12 months, respectively, and ACPP was 47.5% and 6.8% at 6 and 12 months, respectively. The SP was 76.1% and 57.1% at 6 and 12 months, respectively. No cannulation complications occurred in the six patients with installation inside the graft. No hemodialysis or stent fracture occurred in any patient during the follow-up period. The SUPERA stent may have a role in salvaging AV grafts with early recurrent thrombosis due to its greater radial force and its conformability and can be useful in treating stenosis involving the elbow or axilla, with fair patency and low complication rates.

Association of Four Types of Vascular Access Including Arterial Superficialization with Mortality in Maintenance Hemodialysis Patients: A Nationwide Cohort Study in Japan

Introduction: Vascular access usage varies widely across countries. Previous studies have evaluated the association of clinical outcomes with the three types of vascular access, namely, arteriovenous fistula (AVF), arteriovenous graft (AVG), and tunneled and cuffed central venous catheter (TC-CVC). However, little is known regarding the association between arterial superficialization (AS) and the mortality of patients. Methods: A nationwide cohort study was conducted using data from the Japanese Society for Dialysis Therapy Renal Data Registry (2006–2007). We included patients aged ≥20 years undergoing hemodialysis with a dialysis vintage ≥6 months. The exposures of interest were the four types of vascular access: AVF, AVG, AS, and TC-CVC. Cox proportional hazard models were used to evaluate the associations of vascular access types with 1-year all-cause and cause-specific mortality. Results: A total of 183,490 maintenance hemodialysis patients were included: 90.7% with AVF, 6.9% with AVG, 2.0% with AS, and 0.4% with TC-CVC. During the 1-year follow-up period, 13,798 patients died. Compared to patients with AVF, those with AVG, AS, and TC-CVC had a significantly higher risk of all-cause mortality after adjustment for confounding factors: adjusted hazard ratios (95% confidence intervals) – 1.30 (1.20–1.41), 1.56 (1.39–1.76), and 2.15 (1.77–2.61), respectively. Similar results were obtained for infection-related and cardiovascular mortality. Conclusion: This nationwide cohort study conducted in Japan suggested that AVF usage may have the lowest risk of all-cause mortality. The study also suggested that the usage of AS may be associated with better survival rates compared to those of TC-CVC in patients who are not suitable for AVF or AVG.

Prospective multicenter study of a novel endovascular venous anastomotic procedure and device for implantation of an arteriovenous graft for hemodialysis.

The traditional sutured venous anastomosis used during arteriovenous graft implantation is associated with a high incidence of subsequent stenosis that is attributed to neointimal hyperplasia. Hyperplasia results from multiple factors, including hemodynamic abnormalities and vessel trauma during implantation. A novel anastomotic connector device was designed to provide an alternative, less traumatic, endovascular venous anastomosis that may ameliorate the clinical challenges associated with a sutured anastomosis. A prospective single-arm multicenter study was performed to evaluate safety and effectiveness of graft implantation using the study device. Patients requiring graft creation and who met the study criteria were enrolled between February 2018 and July 2021 and observed for 6 months. Collected data included baseline characteristics, graft patency and use for hemodialysis, graft interventions, and adverse events. The primary study endpoint was cumulative graft patency, compared to a pre-specified Performance Goal of 75%. Secondary endpoints included primary unassisted patency and serious adverse events, defined as the occurrence of death, graft infection, emergent surgery, significant bleeding, and pseudoaneurysm. A total of 158 patients were enrolled from 10 study sites, among which 144 subjects were evaluable at 6 months and 14 were censored with partial follow-up observation. Three patients died and the graft was abandoned in 12. The primary endpoint was met (p-value < 0.001). By Kaplan Meier survival analysis, cumulative patency was 92.08% with a lower 95% Confidence Bound of 86.98%. Primary unassisted patency was 60.21% with a lower 95% Confidence Bound of 50.84%. Graft infections occurred in six patients, all unrelated to the study device. There were no reports of emergent surgery, significant bleeding or pseudoaneurysm. These results demonstrate that the study device can be used for successful endovascular anastomosis of a vein to a graft for hemodialysis, with acceptable cumulative patency and safety profile at 6 months. ClinicalTrials.gov Identifier: NCT02532621.

Comprehensive Approach to Improve Quality of Life in Hemodialysis Patients by Early Creation of Arteriovenous Access

An arteriovenous fistula (AVF) is the closest to the ideal model of vascular access. Evidence suggests that people who approach end-stage kidney disease may have an arteriovenous fistula surgically created proactively, enabling the elimination of Permcath insertion for dialysis. Consequently, this proactive action will reduce the risk of bacteremia and admissions to inpatient services for this vulnerable population. The current mean waiting time for AVF creation in King Fahd Armed Forces Hospital, Jeddah (KFAFH), was 172 days. The aim of the project was to decrease the adult Chronic Kidney Disease patient mean waiting time for arteriovenous (AV) access creation from a mean of 172 days to less than 10 days within 12 months. The project was carried out in the Chronic Kidney Disease patient population of King Fahd Armed Forces Hospital, Jeddah. The Plan Do Study Act rapid cycles Quality improvement method was used to implement changes. The interventions include a multidisciplinary approach as the base for the new AVF strategy. Identification of CKD Stage IV patients with impending dialysis was booked for early AVF, thereby reducing the need for Permcath. An additional renal clinic was established to update the patients waiting time for AVF creation and to book patients as Day-surgery through fast track. Daily rounds in the dialysis unit were introduced to address issues of new patients on hemodialysis, and the waiting time for each patient was revised and booked to the new renal clinic for AVF creation. This reduced the referral time to the vascular clinic. Centralized approach by requesting early venogram &amp; venous mappings. The addition of a dedicated inpatient bed for advanced access surgery like AV graft, superficialization, and bridging for patients on anti-coagulation was allotted. Addition of a dedicated operating room for at least daily AVF creation apart from the regular operating list. Addition of 1 more day to existing 1 day per week schedule for Day case procedures with 2 day surgery beds for vascular access. During the 1st PDCA cycle, the mean waiting time for AVF Access decreased to 127.75 days; during the 2nd PDCA cycle, the mean time decreased to 34.25 days, and during the 3rd PDCA cycle the project achieved proactive AVF access with the mean waiting time at -7.2 days. None of the patients with newly created AVF access developed steal syndrome during the project period. AV fistulae have a longer median survival, require less costly and invasive intervention to maintain patency and are less likely to become infected than AV graft or Permcath. A multidisciplinary team approach proved to be successful in reducing the mean AVF waiting time for hemodialysis patients. The interventions enable the team to perform proactive AVF creation in a timely manner eliminating the use of Permcaths for newly admitted Hemodialysis patients. Thus, reducing the CLABSI rate.

Two patients had iliac vein occlusion after treatment of artificial vascular arteriovenous fistula with Viabahn film mulching stent

ObjectiveWith the aging of the population, diabetes mellitus, peripheral vascular diseases, and the increased dialysis age of hemodialysis patients, the depletion of upper limb blood vessels and superior vena cava resources is becoming more visible. MethodsThe lower limb arteriovenous diameter is relatively large, and the first patency rate after artificial arterioplasty is high, with fewer thrombotic events. ResultsAs a result, arteriovenous grafts (AVG) are an important supplement to the hemodialysis pathway after the upper limb hemodialysis pathway has been depleted. The presence of iliac vein stenosis/occlusion following AVG of the lower limbs is uncommon and rarely reported in the literature. ConclusionsRecently, two cases of iliac vein occlusion and treated with Viabahn film mulching stent have achieved good clinical results, which are reported as follows.

WCN23-0076 Clotted arteriovenous fistulae and grafts - does the time taken to intervene in interventional radiology make a difference?

WCN23-0076 Clotted arteriovenous fistulae and grafts - does the time taken to intervene in interventional radiology make a difference?

Comparative efficacy and safety of four common balloon angioplasty techniques for an arteriovenous fistula or graft stenosis: a systematic review and network meta-analysis of randomized controlled trials.

Balloon angioplasty could decrease restenosis of hemodialysis vascular access. The present study investigated the comparative effects and safety of commonly available balloon angioplasty techniques for treating patients with failing autogenous arteriovenous fistulas (AVFs) and grafts (AVGs) stenosis. A comprehensive literature search, including an updated search of PubMed and Embase (via Ovid) and screening of published meta-analyses, was conducted. Primary patency at 6 and 12 months was the primary outcome, and the incidence of complications was the secondary outcome. The random-effects model was used to conduct all statistical analyses, which were performed using RevMan 5.3 and ADDIS 1.16.8. A total of 20 eligible studies involving four balloon angioplasty techniques were entered into the final analysis. Although the direct meta-analysis indicated that cutting balloon angioplasty (CtBA) significantly improved primary patency at 6 [odds ratio (OR), 1.91; 95% confidence interval (CI): 1.27 to 2.86] and 12 (OR, 1.56; 95% CI: 1.13 to 2.15) months compared with conventional balloon angioplasty (CBA), this was not supported by network meta-analysis, which suggested that CtBA was associated with a higher risk of complications compared with drug-coated balloon angioplasty (DcBA) [OR, 0.05; 95% credible interval (CrI): 0.00 to 0.83], high-pressure balloon angioplasty (HBA) (OR, 0.04; 95% CrI: 0.00 to 0.69), and CBA (OR, 0.11; 95% CrI: 0.02 to 0.59). Subgroup analysis of AVFs did not detect any significant differences. In failing AVF and AVG stenosis, HBA might be a preferential option as it is related to a lower risk of complications and has numerically higher primary patency than DcBA and CBA. Further studies are needed to confirm these findings.

Comparing post-maturation outcomes of arteriovenous grafts and fistulae.

Though arteriovenous grafts (AVG) mature more reliably than arteriovenous fistulae (AVF) and require fewer maturation procedures (MP) to obtain functional patency, AVG are thought to have worse function after maturation. We explored differences in post-maturation outcomes between the following groups: AVF patients who did (AS-AVF) and did not (unAS-AVF) require assisted maturation and AVG patients who did (AS-AVG) and did not (unAS-AVG) require assisted maturation. Using the US Renal Data System (2012-2017), we retrospectively identified patients who initiated dialysis with a central venous catheter, underwent AVF or AVG placement and achieved successful two-needle cannulation. Primary patency and access abandonment after maturation were compared across groups using competing risks regression methods, generating sub-hazards ratios (sHR). We identified 42,664 AVF and 12,335 AVG that met inclusion criteria. A larger proportion of AVFs required interventions: 18,408 AVF (43.2%) versus 2594 AVG (21.0%; p < 0.01). Both AS-AVG and AS-AVF patients experienced patency loss at 1 year more frequently compared with unAS-AVG (67.5% & 57.5% vs 55.2% respectively). Patency loss was lowest in unAS-AVF (38.9%). These trends were robust on adjusted analysis (unAS-AVG reference, AS-AVG sHR = 1.44, p < 0.01; AS-AVF sHR = 1.08, p < 0.01, unAS-AVF sHR = 0.67, p < 0.01). AS-AVGs were more likely to be abandoned than unAS-AVGs (11.7% unAS-AVG vs 17.2% AS-AVG). Fistulae, assisted or not, had lower unadjusted rates of 1-year abandonment than grafts (8.9% AS-AVF vs 7.3% unAS-AVF). On adjusted analysis, AVF usage was protective against abandonment (unAS-AVG, reference; AS-AVF sHR = 0.67, p < 0.01; unAS-AVF sHR = 0.59, p < 0.01) while AS-AVG was not (AS-AVG sHR = 1.32, p < 0.01). unAS-AVF have the best long-term outcomes. AS-AVF lose primary patency at a higher rate than unAS-AVG. AVGs may be a better choice than AVFs if veins are marginal and likely to require assisted maturation. Further research is needed to identify anatomic and physiologic factors that affect long-term performance and influence conduit choice.

Utility of a ML analytics on real time risk stratification and re-intervention risk prediction on AV access outcomes and cost.

Vascular access is the lifeline for patients on hemodialysis. The average survival rates of dialysis dependent patients have been improving over the last 5 years and hence their dialysis access needs longevity for uninterrupted optimal dialysis. With the lack of genomic vascular access failure predictors, there is an unmet need for predicting an event and the appropriate approach to mitigate recurrence of the event that could have cost and outcome implications. We performed a single center experience that extracted relevant clinical (access flow, laboratory data and CKD details), access intervention (prior interventions, type & location of lesion, type of balloon used, use of stents etc.) and demographic (age, vintage on dialysis, sex, social determinants, other medical conditions) data in real time and feeds it into validated ML algorithms to predict risk of reintervention. (Plexus EMR LLC). About 200 prevalent hemodialysis patients with a AV graft or AV fistula were included for this analysis. Need for re-intervention and use of stent/ flow reduction/new access creation were the outcomes analyzed. Plexus EMR is a licensed Azure based platform. R software was used to develop the ML algorithms. Regression factors were developed to assess and test the validity of individual attributes across all the data attributes. Each patient had a real time risk calculator available to the interventionalist on risk of reintervention/ year. Of the 200 patients, 148 had a AV fistula and the remaining 52 had a AV graft. Mean interventions in the year prior to analysis was 1.8 in patients with AV fistulas and 3.4 in AV grafts which decreased to 1.1 in AV fistulas and to 2.4 in AV grafts (p < 0.01) post tool deployment. There were 62 AV graft thrombectomies done in the observation year and 62% of those were repeat thrombectomies. Stent utilization increased to 37 (22 in AV grafts and 15 in AV fistulas) and 2 patients had AV access flow reduction surgery. The cumulative cost (predicted) preintervention was $712,609 and decreased to $512,172 post intervention. Stent utilization increased by 68% in the evaluation year and 89% of the stents used were PTFE coated stents. Utilizing AI with ML based algorithms that includes clinical, demographic and patency maintenance variables could become new standards of care to optimally manage AV accesses and lower cost of care.

Arteriovenous Graft Failure in the Veterans Health Administration: Outcome Disparities Associated with Race.

Background Vascular access for ongoing hemodialysis often fails, frequently requiring repeated procedures to maintain vascular patency. While research has shown racial discrepancies in multiple aspects of renal failure treatment, there is poor understanding of how these factors might relate to vascular access maintenance procedures after arteriovenous graft (AVG) placement. Purpose To evaluate racial disparities associated with premature vascular access failure after percutaneous access maintenance procedures following AVG placement using a retrospective national cohort from the Veterans Health Administration (VHA). Materials and Methods All hemodialysis vascular maintenance procedures performed at VHA hospitals between October 2016 and March 2020 were identified. To ensure the sample represented patients who consistently used the VHA, patients without AVG placement within 5 years of their first maintenance procedure were excluded. Access failure was defined as a repeat access maintenance procedure or as hemodialysis catheter placement occurring 1-30 days after the index procedure. Multivariable logistic regression analyses were performed to calculate prevalence ratios (PRs) measuring the association between hemodialysis maintenance failure and African American race compared with all other races. Models controlled for vascular access history, patient socioeconomic status, and procedure and facility characteristics. Results In total, 1950 access maintenance procedures in 995 patients (mean age, 69 years ± 9 [SD], 1870 men) with an AVG created in one of 61 VHA facilities were identified. Most procedures involved African American patients (1169 of 1950, 60%) and patients residing in the South (1002 of 1950, 51%). Premature access failure occurred in 215 of 1950 (11%) procedures. When compared with all other races, African American race was associated with premature access site failure (PR, 1.4; 95% CI: 1.07, 1.43; P = .02). Among the 1057 procedures in 30 facilities with interventional radiology resident training programs, there was no evidence of racial disparity in the outcome (PR, 1.1; P = .63). Conclusion African American race was associated with higher risk-adjusted rates of premature arteriovenous graft failure after dialysis maintenance. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Forman and Davis in this issue.

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

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. A surgically created autogenous arteriovenous fistula has been the gold standard for dialysis access. However, for patients who are not candidates for arteriovenous fistula, arteriovenous grafts using various conduits have widely been used. 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. 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 institutional review board-approved protocol. The primary, primary-assisted, and secondary patency were calculated for the whole cohort and results determined based on gender, body mass index (BMI), and indication for use. Comparison was performed to PTFE grafts at same institution from 2013 to2016. 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±13.5years in the BCA group, 55.8±14.5 in the PTFE group, and the mean BMI was 29.8±9.2kg/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, 12-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 2 genders was similar. There was no statistically significant difference in primary, primary-assisted, and secondary patency of BCA grafts between different BMI groups and indication for use. The average patency of a bovine graft was 17.8±8months. Sixty one percent of the BCA grafts needed intervention with 24% needing multiple interventions. There was an average of 7±5months to first intervention. The infection rate was 8.1% in the BCA group and 10.4% in the PTFE group with no statistical difference. Primary and primary-assisted patency rates at 12months in our study were higher than those for PTFE at our institution. There was higher primary-assisted patency of BCA grafts among males at 12months compared to PTFE. Obesity and indication for BCA graft use did not appear to affect patency in our population.

Arteriovenous shunt status post-coronary artery bypass graft surgery treated with microcoil placement: A case report

Accidental cardiac arteriovenous (AV) anastomoses is a rare but severe complication of coronary artery bypass grafting. This can result in high output heart failure if left untreated. Little research has been done on the mainstays of treatment for this condition. Our patient is an 82-year-old male with a history of known coronary artery disease, status post-coronary bypass grafting surgery, presented with increasing shortness of breath, which was initially determined clinically to be due to high output heart failure, which was later confirmed during cardiac catheterization procedure. Coronary cardiac catheterization was carried out 2 weeks prior at an outside hospital for which the graft, which is supposed to be anastomosed of the circumflex, inadvertently anastomosed to the coronary sinus. The patient returned to the cardiac catheter lab and repeat angiography was performed. The left to right shunt was subsequently embolized using microcoils. He tolerated the procedure well. No recurrent anginal and/or heart failure symptoms were present. Interventional cardiology began the procedure by gaining right common femoral access. Next the saphenous vein graft to the coronary sinus was engaged with a 6 French JRy (Medtronic Inc., Minneapolis, MN) guide catheter and a 0.014” coronary wire was placed into the graft. Then interventional radiology advanced a 2.4 French microcatheter (Terumo, Ann Arbor, MI USA) over the 0.014” wire (Abbott Vascular Devices, Plymouth MN) into the mid to distal aspect of the bypass graft. Four detachable 0.018” microcoils (Terumo, Ann Arbor, MI USA) were carefully placed within the bypass graft. Subsequent angiogram demonstrated complete occlusion of the bypass graft with resolution of the AV shunt. Due to the acuity of the patient’s symptoms and the long timeframe from originally attempting stenting, no additional attempts to stent the circumflex were performed. Follow-up angiogram through the base catheter demonstrates complete occlusion of the bypass graft with resolution of the AV shunt. No contrast was seen entering the coronary sinus. The patient tolerated the procedure well with no immediate complications. Estimated blood loss was &lt;10 mL. The patient was admitted overnight for further evaluation. No shortness of breath noted. He was discharged in good condition the following day. Accidental cardiac AV anastomosis is a rare complication of coronary artery bypass grafting that could lead to high output heart failure. In such cases, catheter directed embolization with microcoils can be done to occlude the AV shunt created by the previously placed cardiac catheter with resolution of heart failure symptoms.

Intimal growth on the luminal surface of arteriovenous grafts in rats.

Endothelial cells are known to grow on the luminal surface of arteriovenous grafts (AVGs) used in hemodialysis. Although endothelial cells are important for preventing infection, a detailed growth of endothelial cells in AVGs is unknown. This study sought to create a simpler animal model of AVGs and to investigate how endothelial cells form on the luminal surface. Polyethylene grafts were placed between the cervical artery and vein of Wistar rats. The grafts were removed at 6h, 24h, 3days, or 7days after placement. The luminal surface was observed under optical and polarizing microscopy and stained with endothelial cell markers (LEL, CD31), the progenitor cell marker CD34, and the macrophage marker ED-1. Microscopy demonstrated many diffuse vascular endothelial cells on the luminal surface of AVGs after placement. While there was no difference in the number of LEL-positive cells between the arterial side (AS) and venous side (VS) at 6h or 7days, there were significantly more of these cells on the VS at both 24h and 3days (p < 0.05). Analysis at 24h showed some CD31-positive cells and few CD34-positive cells. This was the first study to use a simple rat model of AVG placement. Endothelial cell formation was initially more active on the VS than on the AS, but these cells subsequently increased in number across the luminal surface. Future clinical studies might contribute clinically by confirming whether AS versus VS puncture results in different infection rates.

Outcomes of operative intervention for ulcers over hemodialysis arteriovenous access.

The native arteriovenous fistula (AVF) is the gold standard for long-term hemodialysis access. When native vein options are exhausted, arteriovenous graft (AVG) becomes the next choice. An ulcer over an AVF or AVG is a serious condition with the potential for life-threatening hemorrhage. This study aims to present our experience with surgical management of ulcers over AVFs or AVGs. Electronic records of 26 patients who underwent 27 consecutive surgical procedures for ulcers over AVFs or AVGs from December 31, 2016 to December 31, 2021 at the Royal Liverpool University Hospital were retrospectively analyzed. The majority were males (14/26, 53.8%) and the median age was 64.5 years. Operative repair was required for 25 ulcers over 24 AVFs and 2 ulcers over 2 AVGs. Ten patients (37%) presented with bleeding. Seventeen (63%) had impending bleeding suggested by a thin soft tissue covering or a false aneurysm at the site of the ulcer. Previous endovascular intervention for fistula outflow stenosis was a significant predictor for presenting with bleeding (p=0.031). All ulcers (27/27, 100%) underwent excision and primary skin closure. Fistula wall defects were directly repaired in 18/27 (66.7%). Four/26 (14.8%) fistulas had to be ligated and 2 (7.4%) had end-to-end re-anastomosis after excision of damaged segments. Three/26 (11.53%) fistulas thrombosed immediately after the intervention. The overall fistula salvage rate was 73.08% (19/26). There was 1 (3.7%) patient mortality due to bleeding from wound breakdown after surgery. An acceptable fistula salvage rate can be expected following surgical repair of ulcers over AVFs and AVGs. A history of previous endovascular interventions for fistula outflow stenosis was a predictor of bleeding from these ulcers.

Computational assessment of venous anastomosis angles and graft configurations in arteriovenous graft

Arterio-venous grafts are a viable option for hemodialysis as long-term vascular access. The leading cause of Arterio-venous Grafts (AVG) failure is the development of intimal hyperplasia (IH), primarily found in vessel areas with unfavorable hemodynamic conditions. Computational Fluid Dynamics (CFD) is utilized in this study to assess the effect of some geometrical designs at venous anastomosis on these conditions.At first, models with various anastomosis angles are designed. Results represent that the maximum Wall Shear Stress (WSS) in the model with the anastomosis angle of 15° has decreased from 34.07 Pa to 17.48 Pa (48.69%) compared to the conventional model. Moreover, vortices and regions with high WSS at vein anastomosis reduce remarkably.In the second part, to lessen the unfavorable hemodynamic conditions inspired by the rotational blood flow in the aorta, the graft is designed with several cross-sectional ridges to induce a swirl flow. Three essential hemodynamic parameters, including Oscillatory Shear Index (OSI), Time Averaged Wall Shear Stress (TAWSS), and Relative Residence Time (RRT) in pulsating blood flow models, are extracted, and the outcomes are compared to conventional AVG.Finally, according to the results of the previous sections, an optimized model is proposed. Comparing this model with the conventional one illustrates more than 90% decrement in regions related to high OSI values and a 22.84% reduction in RRT values as the main hemodynamic parameters to assess the areas with a high risk of IH development.

Surgical creation of lower extremity fistula and grafts.

Lower limb vascular access (LLVA) should be considered for patients in whom upper extremity access has been exhausted. The decisional process around vascular access (VA) site selection should incorporate a patient centered approach that aligns with End Stage Kidney Disease life-plan as recently described in proffered in 2019 Vascular Access Guidelines. The current surgical approaches to LLVA can be divided into two main groups: (A) autologous arteriovenous fistulas (AVFs); (B) synthetic arteriovenous grafts (AVGs). The autologous AVFs include both the femoral vein (FV) and great saphenous vein (GSV) transpositions, while prosthetic AVGs in the thigh position are appropriate for certain patient subtypes. Good durability has been described for autogenous FV transposition as well as AVGs with both demonstrating acceptable primary and secondary patency rates. Major complications such as steal syndrome, limb edema, and bleeding and minor complications such as wound-related infection, hematoma and delayed wound healing have been noted. LLVA is commonly reserved for the patient in whom the only alternative VA may be a tunneled catheter with its attendant morbidity. In this clinical circumstance, successful LLVA has the opportunity to be a life-saving surgical therapy when successfully performed. We describe a thoughtful approach that focuses on patient selection to optimize success and mitigate complications associated with LLVA.

Surgical creation of upper extremity arteriovenous fistula and grafts: a narrative review.

Surgical creation of arteriovenous fistulas (AVF) and grafts (AVG) continues to be the mainstay access for hemodialysis (HD). Avoidance of dependence on dialysis catheters continues to be a worldwide mission in dialysis access. Importantly, there is no one-size-fits-all approach to hemodialysis access and each patient should undergo access creation that is patient-centered. The aim of this paper is to review the literature, current guidelines, and discuss the common types of upper extremity hemodialysis access and their reported outcomes. We will also share our institutional experience regarding the surgical creation of upper extremity hemodialysis access. The literature review incorporates twenty-seven relevant articles from 1997 to present and one case report series from 1966. Sources were gathered from electronic databases including PubMed, EMBASE, Medline, and Google Scholar. Only articles written in the English language were considered and study designs varied from current clinical guidelines, systematic and meta-analyses, randomized controlled trials, observational studies, and two main vascular surgery textbooks. This review exclusively focuses on the surgical creation of upper extremity hemodialysis accesses. Creating a graft versus fistula ultimately is decided by the existing anatomy, and is centered around the need of the patient. Preoperatively, the patient should undergo a thorough history and physical exam, with special attention to any previous central venous access, as well as, delineating the vascular anatomy with ultrasound imaging. The major tenets of access creation are choosing the most distal site of the non-dominant upper extremity whenever possible; and ideally creation of an autogenous access is preferred over a prosthetic graft. Described in this review are multiple surgical approaches for upper extremity hemodialysis access creation and associated institutional practices performed by the surgeon author. In the postoperative period, follow up care and surveillance are imperative to preserve a functioning access. The most recent guidelines regarding hemodialysis access still favor arteriovenous fistula as the primary goal for patients with suitable anatomy. Preoperative evaluation including patient education, intraoperative ultrasound assessment, meticulous technique, and careful postoperative management are all paramount for successful access surgery. Dialysis access remains quite challenging, but with diligence the great majority of patients can be dialyzed without catheter dependence.