Autologous Arteriovenous Fistulae Research Articles

Evaluation of arteriovenous fistula maturation and early prediction of clinical eligibility, using ultrasound: The Fistula Maturation Evaluation (FAME) Study.

The study of time-related alterations of ultrasound-determined parameters during maturation, and the assessment of time to hemodynamic maturation, enabling early prediction of clinical eligibility, of hemodialysis autologous arteriovenous fistulae (AVF). This is an observational, prospective, study of only AVF-eligible patients referred for access creation, from 02/2019 to 02/2022 (ClinicalTrials.gov identifier: NCT0473687). Brachial artery diameter (dBA), access flow volume (FV), non-augmented efferent vein diameter (dEV), resistivity index (RI), and efferent vein total wall thickness (tEV), were assessed by ultrasound. Measurements were conducted daily in the first week and repeated on days 14, 21, 30, 60, and 90, postoperatively. The primary endpoint included the documentation of serial changes of flow and structural parameters related to AVF maturation in the first 90 days of the post-operative period and maturation early prediction. Secondary endpoints included the determination of factors affecting maturation. One hundred one participants (mean age, 67 ± 6 years; 76 males) were enrolled. Average dBA and FV reached maximum on day 60 (5.64 ± 0.85 mm) and 90 (1.172 ± 617 mL/min), respectively. Day 7 values of dBA (5.48 ± 0.73 mm) and FV (1.039 ± 531 mL/min) did not alter significantly during the follow-up period. Parameters indicative of clinical functionality, dEV (5.82 ± 0.90 mm) and tEV (0.493 ± 0.10 mm), reached approximately 90% of maximum (6.66 ± 1.42 mm and 0.526 ± 0.11 mm), by day 14. RI reached minimum on day 30 (0.46 ± 0.09), without significant changes after day 2 (0.48 ± 0.09, p = 0.284). A significant correlation was identified, between day 7 FV and day 60 dEV (r = 0.40, p = 0.0002). A FV cut-off value ⩾657.51 mL/min, on day 7, predicted successful fistula maturation with 85% sensitivity and 100% specificity. Multivariate analysis identified female gender, age >75, diabetes, and wrist access as independent predictors of decreased values of maturation parameters. Hemodynamic maturation is completed by the first postoperative week, while AVF is clinically functional, by the second. FV can be used for early prediction of maturation.

#1711 The impact of a multidisciplinary vascular access team on haemodialysis vascular access-related outcomes

Abstract Background and Aims Autologous arteriovenous fistulae (AVF) are considered the vascular access (VA) of choice for most haemodialysis (HD) patients. Timely AVF creation, adequate AVF maturation and assurance of long-term functional patency significantly benefit this population. International guidelines suggest the creation of multidisciplinary VA programs to improve access-related outcomes. This study aims to evaluate the results of the institution of a multidisciplinary VA team at our center. Method A retrospective case-control study was performed, comparing our center's incident HD patients from years 2019 and 2022. A multidisciplinary VA team was created in 2021. Patient data was collected from their electronic health record, namely demographic variables, comorbidities, prior nephrology (NA) and vascular access appointments (VAA), and access typology at the beginning of HD. The primary outcome was VA used for HD initiation. Secondary outcomes were time until multidisciplinary VAA, AVF creation and maturation, and the prevalence of AVF at six months for patients who initiated HD with a central venous catheter (CVC). Analysis of the results was performed using SPSS v28.0. A p-value < 0.05 was considered statistically significant. Results 184 and 169 incident HD patients were included from years 2019 and 2022, respectively. There were no significant differences regarding demographic variables, comorbidities and prior NA. 42.4% and 37.3% of patients had been observed in a VAA at least 6 months before HD initiation, in 2019 and 2022 respectively (p = 0.095). Significantly more patients started HD with an AVF in 2022 (37.5% vs 50.9%, p = 0.011), regardless of demographic variables, VAA and AVF creation prior to HD institution. For those who started HD with a CVC (62.5% in 2019 and 49.1% in 2022), the median time until VAA (33 vs 25.5 days, p = 0.045), AVF placement (87 vs 46 days, p < 0.001) and puncturable AVF (203 vs 132 days, p < 0.001) were significantly lower in 2022. At 180 days post-HD initiation with CVC, the number of puncturable AVFs was also significantly higher in 2022 (26.1% vs 38.6%, p = 0.002). Conclusion Multidisciplinary VA teams have a positive impact on the number of patients who start HD with AVF. For those who initiate HD using a CVC, these teams are also a major determinant in the number of functional AVFs.

#532 Association between blood flow measured within 30 days from AV access creation and the risk of thrombosis

Abstract Background and Aims The use of arteriovenous (AV) access for hemodialysis (HD) is hampered by the risk of dysfunction and thrombosis. Various factors affect the risk of AV access thrombosis, such as age, female sex, hematocrit, vessels’ diameter and anatomy, and patients’ comorbidities (e.g. diabetes mellitus, thrombophilia, chronic inflammatory disease). Previous studies have reported contradictory results on the prognostic value of intraoperative blood flow (Qa) measurements. Finally, only few studies have investigated the association between postoperative Qa measurements and thrombosis risk. Therefore, current guidelines report that there is not enough evidence to suggest routine assessment of AV access Qa for surveillance. This study aimed to analyze the association between Qa, measured at the first post-operative visit (within 30 days from creation), and thrombosis risk, in distal and proximal autologous AV fistulae (dAVF and pAVF), and AV grafts (AVG). Method This retrospective cohort study included all AV accesses created in San Paolo Hospital (Milan, IT) between January 1st 2013 and December 31st 2022, with a post-operative Qa measurement available within 30 days from the date of creation. AV accesses were classified as dAVF, pAVF and AVG. Qa was measured by ultrasound as the product of the cross-sectional area and the time-averaged mean velocity, in the feeding artery. The thrombosis-free survival of dAVF, pAVF and AVG was plotted using the Kaplan Meier method. The association between Qa and the risk of thrombosis was studied by Cox proportional hazard models, adjusted for patient's age and sex. Non-linearity was assessed using natural splines. Results A total of 218 AV accesses (92 dAVF, 76 pAVF, and 50 AVG) were created in 191 patients. At baseline, patients had a median age of 69 years, 70% were male, 42% were already on HD treatment, and overall, they had a high prevalence of hypertension, diabetes mellitus and cardiovascular comorbidities. At first post-operative visit, median Qa was 922 [698, 1278] ml/min, 1260 [917, 1825] ml/min, and 1665 [1195, 2508] ml/min, respectively for dAVF, pAVF, and AVG (p <0.001). During a median follow up time of 1.35 [0.55, 2.62] years, 66 AV access thrombosis occurred. The thrombosis-free survival rates for dAVF, pAVF and AVG were 84%, 97%, and 51% at 1 year, and 63%, 66%, and 19% at 5 years (Fig. 1). For dAVF we found a significant L-shaped association between Qa measured at the first post-operative visit and thrombosis risk, with the lowest risk found at Qa of 1289 ml/min and an exponential risk increase for dAVF with Qa <800 ml/min (Fig. 2). Particularly, for dAVF with Qa < 1289 ml/min, we found a 39% increased risk of thrombosis for every 100 ml/min decrease in Qa (aHR 1.39, 95% CI 1.10-1.75, p 0.006). In pAVF, Qa showed a trend of inverse linear association with the risk of thrombosis, although not reaching statistical significance (aHR 1.06, 95% CI 0.96-1.17, p 0.24, for every 100 ml/min decrease in Qa). In AVG, Qa was not associated with the risk of thrombosis (aHR 1.01, 95% CI 0.97-1.06, p 0.57, for every 100 ml/min decrease in Qa). Conclusion In our cohort we found that Qa, measured at the first post-operative visit, is associated with the risk of thrombosis in dAVF, but not in pAVF and AVG. In particular, in dAVF the association is non-linear with the lowest risk in our cohort found at Qa equal to 1289 ml/min, with an exponentially increasing risk for Qa <800 ml/min. Our findings suggest that post-operative flow assessment may be a useful tool to identify dAVF at higher risk of thrombosis and allow a closer monitoring or possible preventive interventions.

Management of depth to achieve timely arteriovenous fistula utilization

ObjectiveFailure to achieve timely arteriovenous fistulae (AVFs) utilization due to excessive depth (>6 mm) remains an ongoing concern for dialysis access. This study evaluates the outcomes of radiocephalic (RCF) and brachiocephalic (BCF) fistula elevation required for access utilization. MethodsA retrospective review of all patients undergoing first-time autologous access over 10 years was undertaken. RCF and BCF were analyzed, and cases of initial access failure due to depth alone were selected for study. Primary and staged brachio-basilic AVF were excluded. Outcomes of early thrombosis, line placement, maturation (successful progression to hemodialysis [HD), reintervention, and functional dialysis (continuous HD for 3 consecutive months) were examined. ResultsFrom January 2012 to December 2022, 1733 patients (67% female; mean age, 61 ± 14 years) underwent autologous AVF placement. Of these, 298 patients (17%) had depth-related AVF access issues (BCF, 71% and RCF, 29%). Nineteen percent of these AVFs underwent a primary balloon-assisted maturation (BAM), and 2% had side branch coil embolization before consideration for elevation. The average time to intervention for depth was 11 ± 4 weeks after primary creation. During elevation, side branch ligation occurred in 38% of cases, and 15% underwent intraoperative BAM, The pre-elevation depth was 8.2 ± 3.1 mm, and the mean post-elevation depth was 4.7 ± 2.9 mm (P = .002). Early thrombosis (<18 days) occurred in 4% of cases. There was no mortality, and the 30-day major adverse cardiac event rate was 2%, with a 30-day morbidity of 5%, which was driven by wound issues. Six percent of the AVFs underwent follow-up BAM within 3 months. Mean maturation of the AVFs was 74% ± 3% vs 72% ± 3% (P = .58) for the elevation vs no-elevation groups at 24 weeks, respectively. However, there was an increase in tunneled central line placement in pre-emptive fistula patients due to the delay in maturation (elevation, 17% vs no-elevation, 8%; P = .008). There was a mean successful access time of 6 ± 3 weeks after elevation (16 ± 4 weeks after access creation). There was a median of 2.4 secondary interventions per year after elevation compared with a median of 2.7 secondary interventions per year without elevation. Mean access functionality was 68% ± 8% vs 75% ± 8% at 3 years for the elevation vs no-elevation groups, respectively (P = .25). ConclusionsElevation of deep BCF and RCF occurs late after placement but can be successfully achieved with low morbidity and satisfactory long-term functionality. It results in an increase in tunneled central line placement in pre-emptive fistula patients. Elevation is a valuable adjunct to AVF maturation and enhances an autologous access policy.

Arteriovenous Fistula in Dialysis Patients Remains Patent with Strict Control of Blood Pressure

Patency rates of autologous arteriovenous fistulae in patients with end-stage renal failure constitute a serious problem. In the present study, we aimed to evaluate the effect of early stage blood pressure values on fistula patency in patients with autologous arteriovenous fistulae (AVF). Sixty-six patients with end-stage renal failure who were scheduled for autologous arteriovenous fistula were prospectively enrolled in the study. Systolic and diastolic blood pressure measurements were taken for a period of 24 h following the operation. At the end of the first month, patients were evaluated for fistula patency. Higher AVF thrombosis (p = 0.039) was found in patients with high postoperative systolic blood pressure (> 140 mmHg), while higher rates of fistula patency (p = 0.014) where observed in patients with diastolic blood pressure below 80 mmHg. Early-stage low diastolic and normal systolic (< 140 mmHg) blood pressure values were found to have a positive effect on AVF patency. This situation suggests that in patients with arteriovenous fistula formation, rates of fistula patency can be increased with close monitoring and strict control of blood pressure.

Ultrasound Guided Cannulation of Difficult Fistulae for Dialysis- A RCT

Introduction - Autologous arteriovenous fistulae (AVF) are the best method of vascular access for dialysis but require accurate two needle cannulation to facilitate dialysis (Feldman, Kobrin et al. 1996). A large body of evidence supports reduced complications in central venous access when performed using ultrasound (US) guidance (Hind, Calvert et al. 2003). This study aimed to determine the benefits of cannulation of AVF using US guidance.

Effective arteriovenous fistula alternative for hemodialysis access

BackgroundThe use of autologous arteriovenous fistulae (AVF) for hemodialysis (HD) is the gold standard; however, for many patients at tertiary referral centers, this is not an option. MethodsWe conducted a four year retrospective cohort study to evaluate HD access outcomes with AVF, bovine carotid artery (BCA), and polytetrafluoroethylene arteriovenous graft (PTFE). ResultsThe study contained 416 AVF, 175 BCA, and 58 PTFE, N = 649. There was statistical difference between rates of infection (AVF 3.4%, BCA 2.9%, PTFE 11.9%), P = 0.02. Maturation failed in 7.5% of AVF but in none of the BCA or PTFE (P = 0.001). Accesses were abandoned with AVF (1.9%), BCA (1.5%), and PTFE (9.5%), P = 0.01. ConclusionBovine carotid artery can be an effective alternative form of HD access with lower infection, abandonment, and failure to maturation rates when autologous arteriovenous fistula is not an option.

Autologous arteriovenous fistulae using microsurgery for hemodialysis in young children weighing 20 kg or less: Single center experience

Introduction Arteriovenous autologous fistula (AVF) is the best vascular access (VA) for hemodialysis but its feasibility in smaller children remains a surgical challenge. This study aims to describe a single-center experience regarding the efficiency, longevity and associated morbidities of AVF created in children weighting ≤ 20 kg. Material and methods We collected data of all AVF created using microsurgery techniques after preoperative ultrasound vascular mapping between 1988 and 2011. Primary patency (PP) was defined as the interval time from VA creation until any intervention designed to maintain or re-establish patency or until VA abandonment (failure or transplantation). Secondary patency (SP) was defined as the interval time from creation to VA abandonment. Results Fifty AVF (36 distal, 14 proximal) were created in 40 children with a median weight of 13 kg (range 6 to 22). A total of 22 children were already on extra-renal epuration: 18 on HD via central venous catheter and 4 on peritoneal dialysis. Early complications during the first month after AVF creation were observed in 8 AVF, 6 thrombosis, which were abandoned, and 2 non maturations (1 re-operated successfully). Median time to maturation (first utilization in HD) was 4 months. Secondary complications observed between the first month after AVF creation and transplantation or VA failure were the following: 18 thrombosis (39% of which occurred during transplantation surgery), 22 stenosis (15 corrected by angioplasty, 4 by surgery whether 3 ended to AVF failure) and 3 high blood flow rate (1600, 1850, 2100 mL/min/1,73 m2) without evidence of cardiac complications. Median duration of PP and SP were 7 and 17 months respectively. Conclusions In our experience, AVF is feasible in younger children with 86% of success. Time to maturation is longer than in older children but SP after creation is excellent. Attention should be paid during transplantation surgery, as thrombosis rate is considerably high.

Aspirex Thrombectomy in Occluded Dialysis Access: A Retrospective Study.

This study is the first to present the outcomes of the Straub Aspirex device for the salvage of occluded renal dialysis access fistulae. This is a retrospective study, using data from the Renal Unit and Radiology Department database. It included all the patients between 2010 and 2014 who underwent percutaneous mechanical thrombectomy (PMT) treated by JD. Aspirex is an over-the-wire, 6-10 French catheter within which is a rapidly rotating helix which draws thrombus into a window near the tip which it then macerates and removes. Access survival was assessed using the Kaplan-Meier method, and multi-variant analysis was performed using the Cox proportional hazards model. Significance was considered if p<0.05. A total of 27 procedures were performed for 19 patients. 13 had autologous arterio-venous fistulae, and 14 had synthetic (PTFE) arterio-venous grafts. 15 were males, 4 females. 100% of the patients successfully had a channel of thrombus removed. This resulted in an 81.5% initial clinical success, with primary patency rates of 53.6, 44.3 and 33% by days 30, 90 and 480, respectively, without significant difference of any analysed covariates. No major complication (pulmonary embolus, paradoxical cerebral infarction, limb ischaemia or significant haemorrhage) occurred. Aspirex has rates of patency and complication similar to other PMT devices. No covariant studied affected outcome.

Brachiobasilic fistulae: an upper limb autologous option for everyone?

Purpose Autologous arteriovenous fistulae (AVF) are the vascular access option of choice. However, Brachiobasilic fistula (BBF) are complex procedures with variable outcomes reported in the literature. Our aim was to evaluate outcomes and morbidity associated with BBF in our population. Methods Retrospective analysis of prospectively collected data was undertaken for all 51 BBF created in our institution between January 2010 and March 2013. These were compared to an age and sex-matched group of brachiocephalic fistula (BCF) created over a similar time period. Demographic, operative and outcome data was collected for all patients. The primary end points were primary functional patency, primary-assisted patency and secondary patency at 3, 6 and 12 months. Continuous data was compared using Student’s t-test and categorical data using chi-squared test (p < 0.05 is significant). Results Mean patient age was 57 years (range: 21–82). About 45% were male. About 73% of patients were already on hemodialysis (HD) at the time of BBF creation. BBF was the secondary or tertiary access procedure in 60.8% of patients (n = 31). BBF were associated with significant operative burden with 82% of patients requiring a general anaesthetic and median hospital admission of 2 days (range: 1–4). About 75% had a single-stage procedure. About 23.5% (n = 12) required operative revision (superficialization or anastomotic revision for stenosis). Patients with BBF spent an additional 3.45 days/year in hospital as a result of access related complications compared to 0.56 days/year in the BCF group. Primary-assisted patency at 3, 6 and 12 months was better in the BCF group than BBF group (86%, 72% and 48% vs. 71%, 59%, 33%, respectively; p < 0.01) Primary functional and secondary patency rates at 3, 6 and 12 months were 74%, 58% and 32% and 78%, 63% and 41%, respectively, with an average of 0.33 procedures per AVF to maintain patency (10 fistuloplasties, 4 IR thrombectomy and 3 surgical thrombectomy). About 32% (n = 17) of BBF were never used for HD (seven patients had a patent AVF but did not require HD >18 months following creation; nine failed to adequately mature and one patient refused second stage superficialization). Conclusions BBF are associated with a significant initial operative burden and higher complication and poorer patency rates than BCF. About one-third of BBF created in this series were never used. Given the morbidity associated with this procedure, careful consideration should be given to creation of BBF in pre-dialysis patients particularly those in whom the rate of decline in renal function is slow.

Assessment of the Effectiveness of Percutaneous Transluminal Balloon Angioplasty for Failing or Nonmaturing Arteriovenous Fistulae for Hemodialysis

Autologous arteriovenous (A-V) fistulae are the recommended arteriovenous access for long-term dialysis in chronic renal failure patients. However, the rate of nonmaturity and failure is still significant. The present study aimed at salvaging fistulas using percutaneous transluminal balloon angioplasty (PTA). Thirty-two patients with nonmaturing or failing fistulas were included, to which they were subjected to PTA with preintervention and postintervention fistulograms to assess the success rate in restoring the fistulae's patency and function. Salvage rate was 26 of 32 fistulas (81.3%) in which the fistulas regain their usability for hemodialysis at least for 3months of follow-up, 4 cases (12.5%) persist nonmature and 2 cases (6.3%) were not used for stenosis. PTA is a safe and effective method for treating nonmature and failing native A-V fistulas.

Effectiveness of Collateral Vein Embolization for Salvage of Immature Native Arteriovenous Fistulas

PurposeTo investigate the value of collateral vein embolization (CVE) as a salvage treatment for nonmaturing native arteriovenous fistulae (AVFs) in patients requiring hemodialysis. Materials and MethodsA total of 49 patients undergoing CVE (N = 65) for immature native AVFs at a single institution were reviewed. The study included 42 patients treated by 56 embolizations. Average fistula age at time of intervention was 18.2 weeks. Each patient underwent angiographic evaluation for fistula immaturity, with clinical success defined by initiation of single-session hemodialysis through the native fistula. ResultsFistula maturity was achieved in 32 of 42 patients (76.2%). No major complications occurred. Average time from CVE to fistula maturity was 38.4 days. Angioplasty done with CVE was found in a statistically higher percentage of patients with fistula success versus failure (31.3% vs 8.3%; P = .039). Radiocephalic fistulae were seen in a higher percentage of fistula failures compared with successes, but the results were not statistically significant (83.3% vs 59.4%; P = .054). Thirty-four patients underwent CVE without angioplasty, which resulted in successful fistula maturation in 22 cases (64.7%). Radiocephalic fistulae were again seen in a higher percentage of fistula failures compared with successes, but the findings did not meet statistical significance (81.8% vs 54.5%; P = .052). ConclusionsCoil embolization of competing collateral vessels as a salvage treatment for nonfunctioning autologous AVFs is a viable treatment option in the majority of patients. Patients with radiocephalic fistulae may be at higher risk for primary fistula failure, but the present data are inconclusive.

A novel classification system for autogenous arteriovenous fistula aneurysms in renal access patients.

Arteriovenous fistulae (AVFs) constructed for hemodialysis access are prone to aneurysmal degeneration. This can lead to life-threatening sequelae such as aneurysmal rupture. The literature includes various guidelines on the management of certain aspects of access-related aneurysm formation; however, no classification system exists to guide reporting or prognostication. We aimed to create a universally acceptable classification for these aneurysms and establish guidance about their management. We clinically examined, duplex scanned, and photographed all of the autologous arteriovenous fistulae in our local renal failure population in January 2010 in order to categorize morphology. We then followed up the cohort for 2 years prospectively to assess outcomes, primarily of rupture or surgical intervention for bleeding. A total of 344 patients were included (292 currently needling their fistula and 52 with low creatinine clearance awaiting dialysis). In all, 43.5% of dialyzed patients had aneurysmal fistulae. We propose a classification system as follows: type 1a: dilated along the length of the vein; type 1b: postanastomotic aneurysm; type 2a: classic "camel hump"; type 2b: combination of type 2a and 1b; type 3: complex; and type 4: pseudoaneurysm. Six fistulae needed emergency surgery for bleeding in the 2-year follow-up period and 5 of these were type 2 aneurysms. The remaining one was in the nonaneurysmal group, although it had become aneurysmal by the time it bled. Type 1 aneurysms are much commoner in patients who have not yet needled their fistula and have a relatively innocuous course although type 1a aneurysms should be monitored for high flow and physiological consequences thereof. Type 2 aneurysms are associated with needling of AVFs. They are at significant risk of rupture and need to be monitored carefully or treated prophylactically.

Lower limb access.

Lower limb vascular access is used as an access site in patients in whom all upper limb possibilities for arteriovenous access creation are exhausted or with bilateral upper limb central vein occlusions. Autologous arteriovenous fistulae (AVF) using the greater saphenous vein have disappointing results apart from the isolated success. Autologous AVF using the femoral vein transposition have good results both in terms of long-term patency and are associated with a 10-fold reduction in infection risk compared with arteriovenous grafts (AVGs). However, a femoral vein transposition is a major undertaking and is associated with an increased risk of ischaemic complications. It is not a good option for patients with established peripheral arterial disease, but may be a good alternative for the younger patient with a high infection risk. The type of lower-extremity vascular access should be carefully tailored to the individual patient.

High Brachial Artery Bifurcation is Associated with Failure of Brachio-Cephalic Autologous Arteriovenous Fistulae

Although European Best Practice Guidelines on vascular access recommend universal pre-operative duplex scan in patients receiving brachio-cephalic (BC) arteriovenous fistulae (AVF), this is not widespread practice. Furthermore, cadaveric and angiographic studies suggest that variation in upper limb arterial anatomy is common. Our aim was to investigate the prevalence of high brachial artery bifurcation (HB) and its impact on BC AVF patency. A retrospective analysis of consecutive autologous BC AVF created over an 18-month period (January 2008 to June 2009). Patients with high bifurcations identified at duplex scan were compared with a control group who had normal bifurcations. All patients were followed up at 1, 6 and 12 weeks post-operatively. The study endpoint was AVF patency. One hundred and five autologous BC AVF procedures were performed in our institution, of which 29 (27.6%) were identified as having a high brachial bifurcation on pre-operative duplex scan. The bifurcation was axillary in six patients and located at the proximal, middle and distal third of the humerus in nine, seven and seven patients, respectively. The actuarial functional patency rate was 53.2% (standard error = 9.6%) in the HB group and 76.2% (standard error = 4.9%) in the control group (log-rank test, p=0.027). These data show that aberrant brachial artery anatomy is both common (12%) and a predictor of autologous BC AVF failure. These data support the universal use of pre-AVF duplex scanning.

Technical Aspects of Duplex Ultrasound-Guided Angioplasty of Arteriovenous Fistulae

Introduction Up to one-third of autologous arteriovenous fistulae (AVF) created for hemodialysis access will require additional interventions to maintain patency or promote maturation. We describe the technical aspects of duplex ultrasound-guided AVF angioplasty as an alternative to traditional contrast fistulogram and angioplasty. Methods The procedure can be performed either in the operating room, interventional procedures suite, or in an outpatient office setting. It is done in a sterile fashion under local anesthesia and light intravenous sedation. With the use of a 12-MHz linear probe and color Doppler imaging, the AVF is surveyed in both the longitudinal and transverse planes, with velocity measurements for identification of areas of stenosis and measurement of AVF blood flow to examine for failure of maturation. Specific areas of stenosis are marked with a skin marker. Percutaneous access into the AVF, guidewire advancement, angioplasty balloon inflation, and deflation are all performed under direct ultrasound visualization. Successful angioplasty is achieved when the vessel diameter, flow, and velocity improve to acceptable ranges. Results We have found that duplex ultrasound provides accurate diagnosis of AVF stenosis and non-maturation. Ultrasound information assisted us in the selection of angioplasty balloon sizes and the process of balloon inflation-deflation. Available real-time hemodynamic assessment of lesions before and after interventions provided immediate feedback on the efficacy of treatment. Additional information such as vessel wall recoil, residual stenosis, or plaque dissection after angioplasty guided the upsizing of balloons or deployment of intravascular stents. Conclusions Duplex ultrasonography offers the potential for a less expensive and more informative treatment of stenotic or non-maturing arteriovenous fistulas in a variety of outpatient settings. One such future potential location includes the Vascular Laboratory. It offers additional benefits of the avoidance of ionizing radiation and nephrotoxic contrast.

La antiagregación plaquetaria incrementa los requerimientos de eritropoyetina en pacientes en hemodiálisis

BackgroundThe optimal use of human recombinant erythropoietin therapy is important to maximize the effectiveness of treatment of anemia and cost-effectiveness in hemodialysis (HD) patients. To achieve this, all the factors that can counteract the positive action of erythropoietin therapy should be identified. ObjectiveTo evaluate the possible influence of antiplatelet therapy on erythropoietin requirements in HD patients. Patients and methodA cross-sectional study was performed in 181 HD patients with autologous arteriovenous fistulae (55% males; mean age 65±14 years). Data were collected in 10 hemodialysis units in Aragon (Spain). Patients were divided into 2 groups according to whether they were receiving antiplatelet therapy or not. ResultsHemoglobin levels were similar in the 2 groups but erythropoietin requirements were higher in patients on antiplatelet therapy (129.8±59.8 versus 103.2±62.2 U/kg/week, p=0.0094). No differences between the 2 groups were found that could explain this finding. When diabetic patients were analyzed separately, erythropoietin doses were higher in the group of patients on antiplatelet therapy than in those not on antiplatelet drugs (130.9±58.2 versus 94.7±39.1 U/kg/week, p=0.0357). Multiple regression analysis revealed that antiplatelet therapy, low serum ferritin, low serum calcium, and high serum aluminium levels were independent predictors of erythropoietin hyporesponsiveness. In a subgroup of 95 patients in whom absolute lymphocyte count was available, patients on antiplatelet therapy showed lower lymphocyte count (1,127±394 versus 1,432±520 lymphocytes/μl, p=0.006) and higher erythropoietin requirements (138.6±63.1 versus 109.9±61.5 U/kg/week, p=0.0393) than individuals not on antiplatelet therapy. ConclusionsThe present study suggests that antiplatelet therapy may be an important factor in determining erythropoietin requirements in HD patients.

Thrombolytic Effects of Target-injected Urokinase on Hemodialysis Patients with Autologous Arteriovenous Fistulae

目的 观察尿激酶靶向溶栓治疗对血液透析患者动静脉内瘘血栓形成的疗效.方法 18例患者于瘘管血栓形成的近心端微泵注射尿激酶25～40万u/小时,平均30万u,观察治疗前后血管波动、血管杂音以及不良反应、血压和肝肾功能.结果 在总共进行的21例次溶栓治疗中,总成功率83.4%(18/21),一次成功率为94.4%(17/18).溶栓成功主要于血栓形成时间和血压关系密切.结论 微泵靶向性注射小剂量尿激酶治疗血液透析患者动静脉内瘘血栓形成的疗效确切,且操作简单,不良反应少,值得临床推广。

Vascular Access in Children: The Importance of Microsurgery for Creation of Autologous Arteriovenous Fistulae

Microsurgery gives much better immediate and long term results than classical surgery for the creation of direct arteriovenous fistulae, the best chronic access to blood in children.

Vascular access survival in children and young adults receiving long-term hemodialysis

The delivery of long-term hemodialysis therapy in children is complicated by smaller vascular caliber and the potential lifelong requirement for hemodialysis access. Various factors have resulted in the increased use of cuffed central venous catheters (CVLs) in preference to autologous arteriovenous fistulae (AVFs) and arteriovenous synthetic grafts (AVGs). The aim of this study is to compare CVL, AVF, and AVG survival and determine factors affecting their survival. A 20-year retrospective study was undertaken of pediatric patients receiving long-term hemodialysis therapy. Age, height, weight, body mass index, and sex were noted at each procedure, in addition to the presence of hypoalbuminemia, underlying diagnosis, type and site of vascular access, and effect of previous access surgery. The grade of operator also was noted. Three hundred four vascular access procedures were performed on 114 patients, with a median age at initial access formation of 12.0 years (range, 4 weeks to 21.9 years). The most common procedure was CVL insertion (182 procedures) and then AVF formation (107 procedures), with only 15 AVGs created. Median censored survival was 3.14 years (95% confidence interval, 1.22 to 5.06) for AVFs and 0.6 years (95% confidence interval, 0.20 to 1.00) for CVLs. Factors adversely affecting vascular access survival were younger age, trainee operator, presence of hypoalbuminemia, and type of access undertaken, with AVF better than CVL. This study shows increased survival of AVFs over CVLs and AVGs. Vascular access in children and adolescents may impact on future dialysis accessibility and should be undertaken by those most experienced in each technique.