Location Of Arteriovenous Fistula Research Articles

Vascular access for hemodialysis in Italy: What a national survey reveals.

Since in Italy there are no official data on vascular access (VA) for hemodialysis the Vascular Access Project Group (VAPG) of the Italian Society of Nephrology (SIN) designed a national survey. A 35-question survey was designed and sent it to the Italian facilities through the SIN website. The basic questions were the prevalence, the location, and the surveillance of VA, the bedside use of ultrasound, the use of fluoroscopy for central venous catheter (CVC) placement, and of buttonhole technique, the role of nephrologist in the access creation. The questionnaire was completed in June 2022 by 161 facilities. The survey registered 15,499 patients, approximately one-third of the Italian dialysis population. The prevalence of arteriovenous fistula (AVF), arteriovenous Graft (AVG), and CVC were 61.8%, 3.7%, and 34.5% respectively. The AVF location was 50% in distal forearm, 20% in meanproximal forearm, 30% in upper arm. For AVF creation, nephrologists were involved in 72% of facilities while for CVC placement in 62%. As regards VA monitoring, 21% of the facilities did not have a surveillance protocol; 60% did not register AVF thrombosis and 53% did not register CVC infections. Most of facilities use the fluoroscope during CVC placement, 37% when needed, and 22% never. Ultrasound-guided puncture of complex AVFs was used by 80% of facilities. Buttonhole puncture was used in 5% of patients. Some considerations emerge from the survey data: (1) The increasing CVC prevalence compared to DOPPS 5 study. (2) The low rate of AVG prevalence. (3) The nephrologist is the operator in many VA procedures. (4) The fluoroscopy for CVC placement and the US-guide puncture of the complex AVF are widely used in most facilities. (5) The practice of the buttonhole is not widespread. (6) When the operator is the nephrologist more distal fistulas are performed.

#4923 ARTERIOVENOUS FISTULAS AS HEMODIALYSIS ACCESS IN A PEDIATRIC POPULATION – IS YOUNGER AGE A REASON TO MAINTAIN CENTRAL VENOUS CATHETER?

Abstract Background and Aims In the pediatric population, transplantation remains the first-line therapy in patients with end-stage renal disease (ESRD). However, it is not always possible, increasing the need for other kidney replacement therapy (KRT) modalities, and hemodialysis (HD) has been growing as a modality choice in recent years. To provide quality HD treatment, efficient vascular access is mandatory, and the arteriovenous fistula (AVF) is advocated as the best long-term access option. However, its creation is technically challenging, and its development and maintenance are some of the most difficult elements in the pediatric population. In this study, we describe our experience in the utilization of AVFs in children and adolescents on HD. Method We conducted a retrospective study including all the AVFs performed in our center on underage patients between January 2006 and December 2022. We reviewed the medical records, collected data on demographic variables, AVF characteristics, blood test results, and clinical outcomes. Statistical analysis was performed using SPSS software. Results Forty-three AVFs were performed in 32 pediatric patients. The median age at first AVF construction was 13.5 years (min 4.8; max 17.9). The most frequent etiology of ESRD was congenital anomalies of kidney and urinary tract (n = 20, 62.5%) and most patients (n = 24, 75.0%) were already receiving KRT. Median follow-up time was 16.4 months (min 1; max 98.4) and, at the end of the follow-up period, most patients (n = 22, 68.8%) were transplanted. The mortality rate was 6.3% (n = 2). In what concerns to the location of the AVF, radiocephalic was the first choice in 46.9% of the cases (n = 15), accounting for 34.9% of the total AVFs. Brachiocephalic location was used in 34.4% (n = 11) of first fistulas and 6 subsequent accesses, accounting for 39.5% of the total AVFs. The brachiobasilic location was chosen in 18.8% (n = 6) of the first AVFs and 25.6% of the total AVFs. Primary AVF failure occurred in 26.6% (n = 11) cases and, in 4 of these (36.4%), it was possible to successfully use the same location for a second AVF. We observed no statistical association between primary AVF failure dysfunction and gender, age at the construction of the first fistula, AVF location, or dialysis vintage. Platelet-lymphocyte (PLR) and neutrophil-lymphocyte (NLR) ratios also did not differ between groups. Primary and secondary patency rates at one year were, respectively, 62.5% and 93.8%. With respect to total AVF complications, we observed: thrombosis (27.9%), stenosis (18.6%), distal ischemia induced by vascular access (4.7%), and high flow/aneurismatic dilations (18.6%). The presence of complications was statistically related to age (p = 0.046), with more events in older patients at the time of AVF construction. There was no statistical difference between complications’ occurrence and AVF type, sex, gender, PLR, and NLR. Conclusion The utilization of AVF for HD has been growingly recognized as a safe and efficient alternative for the performance of KRT in pediatric patients. Although larger studies are needed, we demonstrate positive results in its usage in a pediatric population, with high primary and secondary patency rates. These outcomes were independent of the AVF location. We also advocate AVF usage in younger patients, as complications were associated with older age. PLR and NLR, which are emerging biomarkers for systemic inflammation, were not associated with AVF dysfunction, aligning with the results of other studies in pediatrics.

The impact of vascular access location on pulmonary arterial pressure in chronic kidney disease patients undergoing hemodialysis.

It is feared that among chronic kidney disease patients undergoing hemodialysis, arteriovenous fistula (AVF) itself could contribute to pulmonary hypertension (PH). The impact of AVF location on PH is yet to be assessed. We hypothesize that patients with proximal AVF have higher access blood flow and hence higher pulmonary arterial systolic pressure (PASP) than those with distal AVF. We aimed to compare the PASP between patients with proximal and distal AVF. In this cross-sectional study, PASP was estimated using Doppler echocardiography and blood flow in the AVF was assessed by Doppler ultrasound. PASP was modeled by multivariate linear regression. AVF location was the primary exposure of interest. Out of 89 patients undergoing hemodialysis, 72 (81%) had PH defined as PASP >35 mmHg. The mean blood flow in proximal and distal AVF was, respectively, 1240 and 783 mL/min (mean difference 457 mL/min, p < 0.001). Mean PASP in patients with proximal AVF was 16.6mmHg higher than those with distal AVF (p < 0.001, 95% CI 8.3-24.9). There was a positive correlation between access blood flow and PASP (r = 0.28, p = 0.007). If access blood flow was included as a covariate in the multivariate model, the association between AVF location and PASP ceased to exist. Patients with proximal AVF have a significantly higher PASP than those with distal AVF, and this could be attributed to the higher blood flow in proximal AVF compared to distal AVF.

Surgical planning of arteriovenous fistulae in routine clinical practice: A machine learning predictive tool.

Arteriovenous fistula (AVF) is the preferred vascular access (VA) for hemodialysis, but it is associated with high non-maturation and failure rates. Predicting patient-specific AVF maturation and postoperative changes in blood flow volumes (BFVs) and vessel diameters is of fundamental importance to support the choice of optimal AVF location and improve VA survival. The goal of this study was to employ machine learning (ML) in order to give physicians a fast and easy-to-use tool that provides accurate patient-specific predictions, useful to make AVF surgical planning decisions. We applied a set of ML approaches on a dataset of 156 patients. Both parametric and non-parametric ML approaches, taking preoperative data as input, were exploited to predict maturation, postoperative BFVs, and diameters. The best approach associated with lowest cross-validation errors between predictions and real measurements was then chosen to provide estimates and quantify prediction errors. The k-NN was the best approach to predict brachial BFV, AVF maturation, and other VA variables, and it was also associated with the least computational effort. With this approach, the confusion matrices proved the high accuracy of the prediction for AVF maturation (96.8%) and the low absolute error distribution for the continuous BFV and diameter variables. Our data-based approach provided accurate patient-specific predictions for different AVF configurations, requiring short computational time as compared to a physical model we previously developed. By supporting VA surgical planning, this fast computing approach could allow AVF surgical planning and help reducing the rate of non-maturation, which might ultimately have a broad impact on the management of hemodialysis patients.

The effect of the location of arteriovenous fistula on the right ventricle in end stage renal disease patients indicated for hemodialysis

Abstract Background End-stage renal disease (ESRD) has significantly increased in developing countries such as Egypt [1]. There are many sites for arteriovenous fistula (AVF) creation. The most common sites for AVF are radio-cephalic AVF (RC-AVF) followed by brachio-cephalic AVF (BC-AVF) [2]. To date, there are no significant studies discussing the possible correlation between the AVF location and abnormalities in the right ventricle (RV) in hemodialysis (HD) patients. Objective To determine the best location for AVF in order to ensure the least possible hazardous side effects of the AVF on the RV. Methods Our study, designed as an interventional study, included 50 ESRD patients referred for primary AVF construction to start HD for the first time. Patients were divided into two groups, 25 patients each. one group underwent a RC-AVF construction and the other had a BC-AVF. We assessed the RV by two dimensional transthoracic echocardiography (2D TTE) twice for each patient, firstly just before the AVF surgery and secondly three months after AVF construction. Results There was a statistically significant difference in between study groups regarding change in RV Tei index (p=0.001) with a decrease in the radial group (Mean ± SD = −0.19±0.2) and an increase in the brachial group (Mean ± SD = 0.02±0.12), and regarding the right ventricular outflow tract proximal diameter (p&amp;lt;0.001) with a decrease in the radial group (Mean ± SD = −2.32±5.49) and a larger increase in the brachial group (Mean ± SD = 2.94±3.14). Changes in the other RV dimensions and functional parameters did not show statistically significant difference. Conclusion After three months follow up, despite the fact that all the RV parameters remained within the normal range, the RV indices with the RC-AVF were associated with either improvement or less decline than with the BC-AVF. Funding Acknowledgement Type of funding sources: None.

SIroliMus coated angioPlasty versus plain balloon angioplasty in the tREatment of dialySis acceSs dysfunctION (IMPRESSION): study protocol for a randomized controlled trial

BackgroundPercutaneous transluminal angioplasty is the current standard treatment for arteriovenous fistula (AVF) stenosis. The mid- and long-term patency with plain balloon angioplasty (PBA) is however far from satisfactory. While paclitaxel-coated balloon angioplasty has been shown to be superior to PBA, concern over its safety profile has recently arisen after a reported possible increased mortality risk with a meta-analysis of large lower limb studies. An angioplasty balloon with a new type of drug coating, the sirolimus-coated balloon (SCB), has been proven to improve patency in the coronary arteries. However, its effect on AV access has yet to be studied.Methods/designThis is an investigator-initiated, prospective, multicenter, double-blinded, randomized controlled clinical trial to assess the effectiveness of SCB compared to PBA in improving the patency of AVF after angioplasty. A total of 170 patients with mature AVF that requires PTA due to AVF dysfunction will be randomly assigned to treatment with a SCB or PBA at a 1:1 ratio, stratified by location of AVF and followed up for up to 1 year. The inclusion criteria include [1] adult patient aged 21 to 85 years who requires balloon angioplasty for dysfunctional arteriovenous fistula [2]; matured AVF, defined as being in use for at least 1 month prior to the angioplasty; and [3] successful angioplasty of the underlying stenosis with PBA, defined as less than 30% residual stenosis on digital subtraction angiography (DSA) and restoration of thrill in the AVF on clinical examination. The exclusion criteria include thrombosed or partially thrombosed access circuit at the time of treatment, presence of symptomatic or angiographically significant central vein stenosis that requires treatment with more than 30% residual stenosis post angioplasty, and existing stent placement within the AVF circuit. The primary endpoint of the study is access circuit primary patency at 6 months. The secondary endpoints are target lesion primary patency; access circuit-assisted primary patency; access circuit secondary patency at 3, 6, and 12 months; target lesion restenosis rate at 6 months; total number of interventions; complication rate; and cost-effectiveness. The trial is supported by Concept Medical.DiscussionThis study will evaluate the clinical efficacy and safety of SCB compared to PBA in the treatment of AVF stenosis in hemodialysis patients.Trial registrationClinicalTrials.govNCT04409912. Registered on 1 June 2020

Efficacy and Safety of Plastic Cannulae Compared with Metal Needles in the Initial Use of an Arteriovenous Fistulae in Incident Hemodialysis Patients: A Randomized Controlled Study

Introduction: Successful cannulation of an arteriovenous fistula (AVF) is important in patients starting hemodialysis (HD). Metal needles have been used for decades, but the usefulness of plastic cannulae has recently been demonstrated as a new technique. Methods: This was a prospective, randomized, open-label study of incident HD patients. Eligible patients were randomized into 2 groups in a 1:1 ratio (n = 45/group). Maturation of the AVF was confirmed using Doppler ultrasound prior to first needling, and 2 well-trained nurses implemented the AVF cannulation. The primary endpoint was the initial cannulation failure rate, defined as the failure of successful completion of 3 consecutive dialysis sessions. The secondary endpoints were time for hemostasis at the end of HD, degree of patients’ pain, degree of cannulation difficulty felt by the nursing staffs, and achieving optimal HD adequacy. Results: The mean elapsed time from AVF creation to the first cannulation was 48.1 ± 16.7 days. A total of 17 cases of cannulation failure occurred, and the failure risk tended to be higher in the metal needle group than the plastic cannula group (hazard ratio 2.6, 95% confidence interval 0.95–7.41) after adjusting for age, gender, comorbidities, and AVF location. The overall incidence of vessel injury was higher and time for hemostasis was significantly longer in the metal group than the plastic group. The use of plastic cannula was associated with a better HD adequacy compared to a metal needle. However, the patients’ pain score (p = 0.004) and nursing staff’s cannulation difficulty score (p = 0.084) were higher in the plastic group, emphasizing the great importance of practice using plastic cannulae. Conclusion: The vascular outcomes of plastic cannulae were much favorable compared to metal needles in incident HD patients. The use of plastic cannulae could be a new and innovative way to improve the quality of dialysis.

International Comparisons of Native Arteriovenous Fistula Patency and Time to Becoming Catheter-Free: Findings From the Dialysis Outcomes and Practice Patterns Study (DOPPS)

Optimizing vascular access use is crucial for long-term hemodialysis patient care. Because vascular access use varies internationally, we examined international differences in arteriovenous fistula (AVF) patency and time to becoming catheter-free for patients receiving a new AVF. Prospective cohort study. 2,191 AVFs newly created in 2,040 hemodialysis patients in 2009 to 2015 at 466 randomly selected facilities in the Dialysis Outcomes and Practice Patterns Study (DOPPS) from the United States, Japan, and EUR/ANZ (Belgium, France, Germany, Italy, Spain, Sweden, United Kingdom, Australia, and New Zealand). Demographics, comorbid conditions, dialysis vintage, body mass index, AVF location, and country/region. Primary/cumulative AVF patency (from creation), primary/cumulative functional patency (from first use), catheter dependence duration, and mortality. Outcomes estimated using Cox regression. Across regions, mean patient age ranged from 61 to 66 years, with male preponderance ranging from 55% to 66%, median dialysis vintage of 0.3 to 3.2 years, with 84%, 54%, and 32% of AVFs created in the forearm in Japan, EUR/ANZ, and United States, respectively. Japan displayed superior primary and cumulative patencies due to higher successful AVF use, whereas cumulative functional patency was similar across regions. AVF patency associations with age and other patient characteristics were weak or varied considerably between regions. Catheter-dependence following AVF creation was much longer in EUR/ANZ and US patients, with nearly 70% remaining catheter dependent 8 months after AVF creation when AVFs were not successfully used. Not using an arteriovenous access within 6 months of AVF creation was related to 53% higher mortality in the subsequent 6 months. Residual confounding. Our findings highlight the need to reevaluate practices for optimizing long-term access planning and achievable AVF outcomes, especially AVF maturation. New AVFs that are not successfully used are associated with long-term catheter exposure and elevated mortality risk. These findings highlight the importance of selecting the best access type for each patient and developing effective clinical pathways for when AVFs fail to mature successfully.

Factors affecting patency of arteriovenous fistula following first percutaneous transluminal angioplasty.

Percutaneous transluminal angioplasty (PTA) has generally replaced surgical procedures to treat arteriovenous fistula (AVF) dysfunction, but the predictors of post-intervention patency are highly variable. This study aimed to determine predictors of primary patency following PTA of dysfunctional AVF. Retrospective analysis of first-time PTA of 307 AVF in 307 patients (171 males, mean age 64.3 ± 12.4years). Demographic, clinical, anatomical and medication variables were reviewed and subjected to univariate and multivariate Cox regression analysis. The post-intervention primary patency rates at 6, 12, 24, and 36months were 76.3%, 58.3%, 43.2%, and 38.2%, respectively. The higher aortic arch calcification (AAC) grade patients were older, had higher incidence of comorbidities and cardiomegaly, and younger AVF age, but their dialysis vintage term was shorter and diastolic blood pressure was lower, and the maximum diameter of balloon angioplasty was mostly ≤ 6mm, and had lower phosphorus level and less calcium-containing phosphate binder use. In multivariate Cox proportional hazard analysis, the presence of higher AAC grade [hazard ratio (95% confidence interval): (1.46 (1.02-2.09); p = 0.037)] and stenosis at upper arm [1.76 (1.16-2.67); p = 0.008] were associated with shorter post-intervention primary patency. In conclusion, higher AAC grade and anatomic factor related to the location of AVF (upper arm) were the important predictors of AVF dysfunction after PTA. These results could assist in tailoring surveillance programs and performing appropriate interventions for risky AVF.

Evaluation of Percutaneous Transluminal Angioplasty on the Success of Venoplasty in the Management of Hemodialysis Fistula Stenosis

Introduction: Patients with chronic kidney failure whose life depends on routine hemodialysis, need good hemodialysis access. Arteriovenous fistula (AVF) is the best access, but this access is prone to stenosis. The best treatment for the problem of AVF stenosis is by percutaneous transluminal angioplasty (venography /venoplasty). This action has developed in Cipto Mangunkusmo National Hospital since 2013, but there is no data and evaluation of its success. This study was conducted to evaluate the success of venoplasty in the treatment of AVF stenosis. Method: This study used a retrospective cohort study to assess the outcome of percutaneous transluminal angioplasty (venography and venoplasty) actions in AVF stenosis in patients with chronic kidney failure. The study was conducted in the Ward Division of Vascular and Endovascular Surgery, Integrated Heart Center, Cipto Mangunkusumo National Hospital’s medical records installation, and Hermina Depok Hospital from December 2016 to May 2017 by evaluating the demographic characteristics, underlying diseases, venoplasty, and venography assessment results, and ultrasound results. Results: Characteristics of people with chronic kidney disease with AVF stenosis were found mostly in the age group 50-60 years (40.9%). As many as 59% of patients were male, and underlying disease was mainly caused by hypertension (93.9%) and diabetes mellitus (42.4%). We found a significant relationship between age and sex with the size of AVF stenosis from demographic analysis. There was no significant relationship between the underlying disease, the location of AVF stenosis, and the venography’s outcome with the size of AVF stenosis from venography. There was a significant relationship between the location of AVF stenosis and the success of venoplasty. There was a significant increase in the results of the ultrasound examination, which were the draining vein diameter, volume flow, and peak systolic velocity to the results of venoplasty after the procedure or three months after the procedure. Conclusion: There was a significant relationship between age and sex with the size of AVF stenosis that occurred. There was no significant relationship between the underlying disease, the location of AVF stenosis with the size of AVF stenosis from venography. A significant relationship was found between the location of AVF stenosis and the success of venoplasty. There was a significant relationship between the results of the ultrasound examination (diameter draining vein, volume flow, and peak systolic velocity) to the results of venoplasty after the procedure or three months after the procedure. Keywords: arteriovenous fistula stenosis, percutaneous transluminal angioplasty, venoplasty, ultrasound

Early Predictors of Arteriovenous Fistula Maturation: A Novel Perspective on an Enduring Problem.

Preoperative ultrasound mapping is routinely used to select vessels meeting minimal threshold diameters for surgical arteriovenous fistula (AVF) creation but fails to improve AVF maturation rates. This suggests a need to reassess the preoperative ultrasound criteria used to optimize AVF maturation. We retrospectively identified 300 catheter-dependent patients on hemodialysis with a new AVF created between 2010 and 2016. We then evaluated the associations of preoperative vascular measurements and hemodynamic factors with unassisted AVF maturation (successful use for dialysis without prior intervention) and overall maturation (successful use with or without prior intervention). Multivariable logistic regression was used to identify preoperative factors associated with unassisted and overall AVF maturation. Unassisted AVF maturation associated with preoperative arterial diameter (adjusted odds ratio [aOR], 1.50 per 1-mm increase; 95% confidence interval [95% CI], 1.23 to 1.83), preoperative systolic BP (aOR, 1.16 per 10-mm Hg increase; 95% CI, 1.05 to 1.28), and left ventricular ejection fraction (aOR, 1.07 per 5% increase; 95% CI, 1.01 to 1.13). Overall AVF maturation associated with preoperative arterial diameter (aOR, 1.36 per 1-mm increase; 95% CI, 1.10 to 1.66) and preoperative systolic BP (aOR, 1.17; 95% CI, 1.06 to 1.30). Using receiver operating curves, the combination of preoperative arterial diameter, systolic BP, and left ventricular ejection fraction was fairly predictive of unassisted maturation (area under the curve, 0.69). Patient age, sex, race, diabetes, vascular disease, obesity, and AVF location were not associated with maturation. Preoperative arterial diameter may be an under-recognized predictor of AVF maturation. Further study evaluating the effect of preoperative arterial diameter and other hemodynamic factors on AVF maturation is needed.

Predictors of Arteriovenous Fistula Early Failure in End-Stage Renal Disease Patients: Real-World Data in Surabaya

Arteriovenous fistula (AVF) is the vascular access of choice in prevalent hemodialysis end-stage renal disease (ESRD) patients. However, there was a significant proportion of early AVF failure and its predictive factor was conflicting in several studies. We conducted a retrospective cohort study in 225 AVFs created in 159 patients. The purpose of this study was to identify the predictive factors of AVF early failure. The data variables included age at AVF creation, sex, history of diabetes, hypertension, cigarette smoking, AVF location and side, history of subclavian tunneled dialysis catheter and history of preoperative ultrasound mapping. This information was collected by interviewing the patient and by AVF scar inspection. AVF that was never coming into use was classified as an early failure. AVF creation in the wrist was significantly associated with a higher early failure rate (29.9%) compared with AVF creation at the elbow (4.4%) (p < 0.001). There was no significant association in terms of AVF early failure in terms of the other variables. We concluded that wrist AVF is significantly associated with early failure. However, this finding should not preclude the National Kidney Foundation’s recommendation of using wrist AVF for the first choice of vascular access to conserve more proximal access sites for future use.

Primary Failure of the Arteriovenous Fistula in Patients with Chronic Kidney Disease Stage 4/5.

BACKGROUND:An Arteriovenous fistula (AVF) is a creation of the natural blood vessels. It is a “gate of life” for the patients on hemodialysis.AIM:The study aimed to analyze the predictors for primary failure of AVF such as gender, age, number and location of AVF, and primary renal disease in patients with chronic kidney disease (CKD) stage 4/5.MATERIAL AND METHODS:The medical records of 178 created arteriovenous fistulae in patients with CKD stage 4/5, were retrospectively studied. Primary failure of AVF was defined as thrombosis or inability for cannulation of AVF within 3 months. Adequate maturation of AVF was defined as successful cannulation of AVF treatment and blood flow of > 600 ml/min.RESULTS:The mean age of the patients was 59.75 ± 14.65 years, and 65.16% (116/178) were men. Adequate maturation of AVF was achieved in 83.71% (149/178). Primary failure of AVF occurred in 16.29% (29/178) of the created fistulae, while 10.11% (18/178) had early thrombosis. The distal arteriovenous fistulae were significantly more frequently created in male patients (51 vs 18; p = 0.015). The female patients were significantly older than the male patients (63.27 vs 57.86 years; p = 0.018).CONCLUSION:Male gender was associated with better maturation of AVF. The age, number and location of AVF, and primary renal disease in patients with CKD stage 4/5 were not associated with primary failure of AVF.

Arteriovenous fistulae for access to hemodialysis in Chad: feasibility study of a medical civic action program by a French army surgical unit.

Use of chronic intermittent hemodialysis is recent in Chad, where it remains underdeveloped. Vascular access is most commonly by catheter. The objective of our study was to demonstrate the feasibility of arteriovenous fistula (AVF) surgery for hemodialysis during deployments as part of the medical civic action program (MEDCAP). We prospectively included all patients admitted for AVF creation at Camp Kossei forward surgical unit in N'Djamena (Chad) between December 2016 and February 2017. Surgery was performed by an experienced vascular surgeon. The data collected included age, sex, cause of kidney failure, type of anesthesia, AVF location, and the duration of the intervention and hospitalization. Patients were examined one month after the procedure to evaluate the functionality, morbidity, and mortality of the AVF. We performed 17AVF in 3months. Male to female ratio was 3. High blood pressure was the main cause of chronic kidney failure (55%). All interventions were conducted under locoregional anesthesia. Overall, 35% of fistulae were radiocephalic, 41% brachiocephalic, and 24% brachiobasilic. The mean duration of intervention was 58minutes and that of hospitalization one day. No deaths occurred. Global morbidity, including non-functioning AVF, was 25%. Our study showed that AVF surgery is feasible during deployment, especially in Chad, and meets the needs of the local healthcare facilities. It should be developed and taught to local surgeons.

Visual disorders caused by cranial arteriovenous fistula with venous drainage into the superior ophthalmic vein.

Although the abnormal venous drainage into the superior ophthalmic vein (SOV) is a well-known entity responsible for ocular symptoms, it remains unclear to what degree it affects the visual function. The purpose of this study was to evaluate the incidence, characteristics and outcomes of the visual disorders in patients with intracranial arteriovenous fistula (AVF) with venous drainage into the SOV. This retrospective study involved eight patients diagnosed with intracranial AVFs with abnormal venous drainage into the SOV between January 2014 and December 2016. The most common location of AVF was the cavernous sinus (CS) in five patients, followed by the intraorbit in two patients and superior sagittal sinus (SSS) in one patient. Visual disorders were detected in three patients (two intraorbit and one CS). The visual field contraction was observed in a patient with intraorbital AVF, and the reduction of visual acuity was confirmed in another patient with intraorbital AVF and a patient with CS dural AVF. All patients underwent an interventional treatment consisting of endovascular embolisation, stereotactic radiosurgery or both, which was selected based on their angioarchitecture. Although angiographic cure of AVF was confirmed in all patients, visual function did not fully recover in two patients with intraorbital AVF. In cases of intraorbital AVF, visual disorders are more frequent and can result in poorer outcomes compared with other dural AVFs with drainage into the SOV. Early diagnosis and treatment are crucial to preserve the visual function of patients with intraorbital AVF.

Prediction of Arteriovenous Fistula Clinical Maturation from Postoperative Ultrasound Measurements: Findings from the Hemodialysis Fistula Maturation Study.

The utility of early postoperative ultrasound measurements in predicting arteriovenous fistula (AVF) clinical maturation is uncertain. We investigated the relationships of ultrasound parameters with AVF clinical maturation in newly created AVF, measured at 1 day and 2 and 6 weeks, in 602 participants of a multicenter, observational cohort study. A backward elimination algorithm identified ultrasound measurements that independently predicted unassisted and overall AVF maturation. Candidate variables included AVF blood flow, diameter, and depth, upper arm arterial diameter, presence of stenosis, presence of accessory veins, seven case-mix factors (age, sex, black race, AVF location, diabetes, dialysis status, and body mass index), and clinical center. We evaluated the accuracy of the resulting models for clinical prediction. At each ultrasound measurement time, AVF blood flow, diameter, and depth each predicted in a statistically significant manner both unassisted and overall clinical maturation. Moreover, neither the remaining ultrasound parameters nor case-mix factors were associated with clinical AVF maturation after accounting for blood flow, diameter, and depth, although maturation probabilities differed among clinical centers before and after accounting for these parameters. The crossvalidated area under the receiver operating characteristic curve for models constructed using these three ultrasound parameters was 0.69, 0.74, and 0.79 at 1 day and 2 and 6 weeks, respectively, for unassisted AVF clinical maturation and 0.69, 0.71, and 0.76, respectively, for overall AVF maturation. AVF blood flow, diameter, and depth moderately predicted unassisted and overall AVF clinical maturation. The other factors considered did not further improve AVF maturation prediction.

Association of Genetic Polymorphisms of Renin-Angiotensin-Aldosterone System-Related Genes with Arterio-Venous Fistula Malfunction in Hemodialysis Patients.

Hemodialysis (HD) is the most commonly-used renal replacement therapy for patients with end-stage renal disease worldwide. Arterio-venous fistula (AVF) is the vascular access of choice for HD patients with lowest risk of infection and thrombosis. In addition to environmental factors, genetic factors may also contribute to malfunction of AVF. Previous studies have demonstrated the effect of genotype polymorphisms of angiotensin converting enzyme on vascular access malfunction. We conducted a multicenter, cross-sectional study to evaluate the association between genetic polymorphisms of renin-angiotensin-aldosterone system and AVF malfunction. Totally, 577 patients were enrolled. Their mean age was 60 years old and 53% were male. HD patients with AVF malfunction had longer duration of HD (92.5 ± 68.1 vs. 61.2 ± 51.9 months, p < 0.001), lower prevalence of hypertension (44.8% vs. 55.3%, p = 0.025), right-sided (31.8% vs. 18.4%, p = 0.002) and upper arm AVF (26.6% vs. 9.7%, p < 0.001), and higher mean dynamic venous pressure (DVP) (147.8 ± 28.3 vs. 139.8 ± 30.0, p = 0.021). In subgroup analysis of different genders, location of AVF and DVP remained significant clinical risk factors of AVF malfunction in univariate and multivariate binary logistic regression in female HD patients. Among male HD patients, univariate binary logistic regression analysis revealed that right-side AVF and upper arm location are two important clinical risk factors. In addition, two single nucleotide polymorphisms (SNPs), rs275653 (Odds ratio 1.90, p = 0.038) and rs1492099 (Odds ratio 2.29, p = 0.017) of angiotensin II receptor 1 (AGTR1), were associated with increased risk of AVF malfunction. After adjustment for age and other clinical factors, minor allele-containing genotype polymorphisms (AA and CA) of rs1492099 still remained to be a significant risk factor of AVF malfunction (Odds ratio 3.63, p = 0.005). In conclusion, we demonstrated that rs1492099, a SNP of AGTR1 gene, could be a potential genetic risk factor of AVF malfunction in male HD patients.

Association between Preoperative Vascular Function and Postoperative Arteriovenous Fistula Development.

Arteriovenous fistula (AVF) maturation failure is the primary cause of dialysis vascular access dysfunction. To evaluate whether preoperative vascular functional properties predict postoperative AVF measurements, patients enrolled in the Hemodialysis Fistula Maturation Study underwent up to five preoperative vascular function tests (VFTs): flow-mediated dilation (FMD), nitroglycerin-mediated dilation (NMD), carotid-femoral pulse wave velocity, carotid-radial pulse wave velocity, and venous occlusion plethysmography. We used mixed effects multiple regression analyses to relate each preoperative VFT to ultrasound measurements of AVF blood flow rate and venous diameter at 1 day, 2 weeks, and 6 weeks after AVF placement. After controlling for AVF location, preoperative ultrasound measurements, and demographic factors (age, sex, race, and dialysis status), greater NMD associated with greater 6-week AVF blood flow rate and AVF diameter (per absolute 10% difference in NMD: change in blood flow rate =14.0%; 95% confidence interval [95% CI], 3.7% to 25.3%; P<0.01; change in diameter =0.45 mm; 95% CI, 0.25 to 0.65 mm; P<0.001). Greater FMD also associated with greater increases in 6-week AVF blood flow rate and AVF diameter (per absolute 10% difference in FMD: change in blood flow rate =11.6%; 95% CI, 0.6% to 23.9%; P=0.04; change in diameter =0.31 mm; 95% CI, 0.05 to 0.57 mm; P=0.02). None of the remaining VFT parameters exhibited consistent statistically significant relationships with both postoperative AVF blood flow rate and diameter. In conclusion, preoperative NMD and FMD positively associated with changes in 6-week AVF blood flow rate and diameter, suggesting that native functional arterial properties affect AVF development.

Vascular access in diabetic patients. Are these patients "difficult"?

Diabetics with stage V chronic kidney disease (CKD) on hemodialysis (HD) are considered as "difficult patients", because of problems with creation of the vascular access. There is controversy regarding the results and recommendations for preparation of the vascular access in these patients. The aim of this retrospective study was to evaluate the results of creating different types of arteriovenous fistula (AVFs) in consecutive series of patients starting dialysis treatment. The analysis was performed in 741 patients (385 females and 356 males), average age 61.4±7 years, who started dialysis treatment in our department between January 2005 and December 2012. Native AVFs were created in all patients. No patients received an AVF requiring synthetic graft material. The number of patients with diabetic nephropathy was 166 (22.4%). Among them, 30 (18%) had type 1 diabetes and 136 (82%) type 2. In this group the occurrence of calcification in the forearm artery was estimated on the basis of physical examination, Allan's test, Doppler ultrasound and forearm X-ray. In a subgroup of patients with atherosclerotic changes in the arterial system the frequency of failed AVFs was analyzed. These results were compared with the group without diabetes. The number of procedures necessary for successfu AVF creation and type of access was counted in both groups. The assessment of the procedure frequency and AVF location in diabetic and in non-diabetic patients was made by χ² test with Yates correction. In the group of 166 patients with diabetes, in 100 cases (60%) atherosclerotic changes in forearm arteries were observed. In a subgroup of 30 patients with type 1 diabetes atherosclerosis was observed in 17 adults (57%). In this subgroup creation of a suitable forearm AVF in the first procedure in 9 patients was possible and in the other 8 cases the atherosclerotic changes necessitated repeated procedures and were an important obstacle to create the AVF. In the subgroup of 136 patients with type 2 diabetes, atherosclerosis in the forearm artery was observed in 83 cases (61%). In this subgroup the creation of a native AVF was possible in 40 patients during the first procedure and in 43 cases additional intervention was needed, but only in 8 cases was atherosclerosis the cause of fistula failure. Generally, among 166 patients only in 16 cases (10%) did atherosclerosis present an important obstacle for AVF creation, but the number of necessary procedures to create one functioning AVF was significantly greater in this population (2 v 2.7, p=0.0001). A functioning AVF in patients with diabetes was found significantly frequently in the arm localization in comparison to non-diabetic patients (4.3 v 2%, p=0.0478). Atherosclerotic changes in forearm arteries in diabetic patients appear in 60% of hemodialysis patients and make it difficult to create an AVF only in 10% of diabetic patients, but it is possible to create a native AVF in 90% of diabetic patients, although this requires more procedures. In patients with diabetes, AVF in the wrist region should be preferred.

Prediction of Arteriovenous Fistula Dysfunction: Can it be Taught?

Physical examination (PE) is an excellent means of predicting arteriovenous fistula (AVF) dysfunction. Although quick and inexpensive, PE is seldom used as a tool to assess stenosis by general nephrologists, dialysis nurses, and dialysis technicians. Previous studies have demonstrated that PE can be taught to interventional specialists, but the perception remains that it is too complex to be performed by other health care professionals. We hypothesized that the physical exam can be taught to a nonmedical professional, and that, with time, it would be comparable to the physical exam performed by a full-time interventional specialist. An undergraduate student and an interventional specialist (MD) examined AVF for dysfunction in a tertiary care hospital over a 6-month period. PE was performed on patients who were suspected of having dialysis access dysfunction and were referred for angiography and intervention (n=49). Physical exam findings were categorized blindly by each examiner into four categories of lesion location: inflow, outflow, both, or neither. Data were privately recorded and compared to the gold standard of angiographic results. Potential confounding variables, including age, gender, diabetic status, and location of AVF were recorded. Weighted Cohen's kappa value was used as a measurement of the level of agreement beyond chance between the diagnoses made by physical exam and angiography. The full-time interventional specialist demonstrated correct prediction of lesion location of 89.8% (kappa=0.850), while the undergraduate student had a correct prediction of 77.6% (kappa=0.625). The student's performance, however, differed significantly over time. The student correctly predicted the location of the lesion in 6 (42.9%) of the first 14 patients (kappa=0.082), compared to 32 (91.4%) of the last 35 patients (kappa=0.855). We suggest that physical exam of AVF can be taught to a nonmedical professional in a short duration of time and the predictive value of the exam can be similar to that of an interventional specialist.