After Arteriovenous Fistula Research Articles

Trends in Venous Diameter and Brachial Artery Volume Flow of arteriovenous fistula in 12 Weeks Postoperatively

ObjectiveTo explore the trends of venous diameter and brachial artery volume flow (VF) in 12 weeks after arteriovenous fistula (AVF) and the influence of preoperative arterial diameter on this trend. Our goal was to clarify the maturation process within 12 weeks after AVF surgery. MethodsClinical data of 257 patients with end-stage renal disease who had their first radial-cephalic AVF established at our institution from February 1, 2023 to February 1, 2024 were included. The patients were divided into group A (radial artery diameter <1.5 mm), group B (radial artery diameter 1.5-2.0 mm), and group C (radial artery diameter >2.0 mm) according to the preoperative radial artery diameter. After AVF surgery, the artery and vein diameter, brachial artery VF were recorded at 1 day, 2 weeks, 4 weeks, 6 weeks, 8 weeks, 10 weeks and 12 weeks. Results1. The venous diameter and brachial artery VF of AVF showed an upward trend, and increased significantly in 1 day-6 weeks postoperatively (P < 0.05),especially between 1 day and 2 weeks, while no significant difference in the increases at 6-12 weeks. 2. Groups B and C were in line with the above trend, whereas the patients in group A showed best growth in 2-4 weeks postoperatively. 3. The natural maturation rates of AVF in groups B and C were significantly better than that of group A at all postoperative time (P＜0.05). ConclusionThe AVF was in a developmentally dominant stage at 6 weeks postoperatively, with 1 day-2 weeks being particularly prominent. The postoperative natural maturation rate of AVF with arteries diameter of<1.5 mm was low, the direct use of such arteries to establish AVFneed careful consideration.

#1434 A study of the factors related to the change in eGFR after arteriovenous fistula creation in CKD patients and its impact on kidney prognosis

Abstract Background and Aims Occasionally, we observe cases of transiently increased estimated glomerular filtration rate (eGFR) after arteriovenous fistula (AVF) creation in patients with chronic kidney disease (CKD). However, there is limited research on the factors influencing the change in eGFR after AVF creation and its impact on kidney prognosis. Method In this single-center retrospective cohort study conducted from April 1, 2021, to July 31, 2023, 141 patients with CKD were enrolled. The participants were categorized into two groups: the increased eGFR group and the non-increased eGFR group after AVF creation. Factors contributing to increased eGFR after AVF creation were identified using through univariate and multivariate logistic regression analysis. Predictive variables included demographic and clinical variables such as sex, age, presence of diabetes mellitus (DM), history of cardiovascular diseases, urinary protein level, systolic blood pressure (SBP) on admission, the use of RAAS inhibitors and diuretics, and smoking history. Additionally, the period from AVF creation to dialysis induction was compared between both groups by the Mann-Whitney U test. Results Mean age was 69.3 ± 12.4. 75.9% were male, and 48.2% had DM. Among the 141 patients, 44 (31.2%) experienced an increase in eGFR after AVF creation. There was no significant difference in eGFR at the time of AVF creation between the increased eGFR group and the non-increased eGFR group (6.4 ± 1.5 vs. 6.2 ± 1.7 ml/min/1.73 m2, P = 0.56). Multivariate adjustment revealed that DM (Odds ratio [OR] 2.55, 95% confidence interval [95% CI] 1.01-6.45), hypertension (OR 0.97, 95% CI 0.95-0.99), and smoking history (OR 0.40, 95% CI 0.16–0.98) were associated with the eGFR increase after AVF creation. The time from AVF creation to dialysis induction was significantly longer in the increased eGFR group than in the non-increased eGFR group (median, 76.5 days vs. 42.0 days, P = 0.02). Conclusion Factors associated with accelerated atherosclerosis, such as hypertension and smoking, were significantly negatively correlated with increased eGFR. Conversely, DM was significantly associated with increased eGFR after AVF creation. Increased eGFR after AVF creation significantly prolonged the time to dialysis induction compared to the non-increased eGFR group.

Mitochondrial targeted catalase improves muscle strength following arteriovenous fistula creation in mice with chronic kidney disease

Hand dysfunction is a common observation after arteriovenous fistula (AVF) creation for hemodialysis access and has a variable clinical phenotype; however, the underlying mechanism responsible is unclear. Grip strength changes are a common metric used to assess AVF-associated hand disability but has previously been found to poorly correlate with the hemodynamic perturbations post-AVF placement implicating other tissue-level factors as drivers of hand outcomes. In this study, we sought to test if expression of a mitochondrial targeted catalase (mCAT) in skeletal muscle could reduce AVF-related limb dysfunction in mice with chronic kidney disease (CKD). Male and female C57BL/6J mice were fed an adenine-supplemented diet to induce CKD prior to placement of an AVF in the iliac vascular bundle. Adeno-associated virus was used to drive expression of either a green fluorescent protein (control) or mCAT using the muscle-specific human skeletal actin (HSA) gene promoter prior to AVF creation. As expected, the muscle-specific AAV-HSA-mCAT treatment did not impact blood urea nitrogen levels (P = 0.72), body weight (P = 0.84), or central hemodynamics including infrarenal aorta and inferior vena cava diameters (P > 0.18) or velocities (P > 0.38). Hindlimb perfusion recovery and muscle capillary densities were also unaffected by AAV-HSA-mCAT treatment. In contrast to muscle mass and myofiber size which were not different between groups, both absolute and specific muscle contractile forces measured via a nerve-mediated in-situ preparation were significantly greater in AAV-HSA-mCAT treated mice (P = 0.0012 and P = 0.0002). Morphological analysis of the post-synaptic neuromuscular junction uncovered greater acetylcholine receptor cluster areas (P = 0.0094) and lower fragmentation (P = 0.0010) in AAV-HSA-mCAT treated mice. Muscle mitochondrial oxidative phosphorylation was not different between groups, but AAV-HSA-mCAT treated mice had lower succinate-fueled mitochondrial hydrogen peroxide emission compared to AAV-HSA-GFP mice (P < 0.001). In summary, muscle-specific scavenging of mitochondrial hydrogen peroxide significantly improves neuromotor function in mice with CKD following AVF creation.

Abstract 632: Cell Populations In Pre-access Veins And Arteriovenous Fistulas: A Single Cell Perspective

Objective: A comprehensive picture of the cellular events dictating the transformation of the vein after arteriovenous fistula (AVF) creation has remained elusive so far. This study generated the first granular cellular atlas of pre-access veins and AVF from patients with end-stage kidney disease (ESKD). Methods: Veins (n=5) and AVF (n=7) were obtained from a total of 12 ESKD patients undergoing fistula creation in two stages. 41,000 enzymatically dissociated cells were single cell sequenced using the 10x Chromium system. Monocle3 inferred the trajectory leading to neointimal cells and signaling interactome in the AVF. Results: Cells populated 16 clusters containing canonical and non-canonical vascular markers after integrating the single cell transcriptomic profiles in Seurat v4. The majority of cells in both veins and AVF were smooth muscle cells (6.6 vs. 9.4%), fibroblasts (12.4 vs. 26.7%), neointimal-like cells (11.5% vs, 17.0, endothelial cells (10.5 vs. 10.5%), macrophages (26.1 vs. 19.5%), lymphocytes (16.4 vs.10.3), and neutrophils (0.7vs. 3.8 %). CENPF+ dividing cells were abundant in the AVF (0.2 to 1.2%). For the first time, we have detected a potential transcriptomic neointimal signature defined by the expression of BGN and PRELP genes that was increased in AVFs, but not absent in the pre-access veins, confirming previous histological findings. Neutrophilic infiltration (S100A8/9+ and CSF3R+) was increased in the AVF. Interestingly, lymphocytes and macrophages were decreased in the AVF with respect to the vein. These changes in cell populations in the AVF wall correlated with up-regulation of GO terms such as ECM deposition, neutrophil activation, and blood vessel remodeling in the AVF. Finally, we established a pseudotime cellular trajectory from contractile SMCs to neointimal-like cells, defined by COL8A1, PRELP, and BGN by Cohen’s I. Conclusions: We present a comprehensive single-cell atlas of the AVF transformation and assign identity to the cellular sources and cell trajectories in this remarkable vascular transformation.

Implanted blood vessel external support device for the treatment of distal hypoperfusion ischemic syndrome in arteriovenous fistulas and high-frame-rate Vector Flow quality assessment.

Distal hypoperfusion ischemic syndrome (DHIS) is a complication occurring after arteriovenous fistula (AVF) creation. Different surgical alternatives haves been proposed in case of severe DHIS. Aim of the present paper is to present a new technique for DHIS treatment. Between the 1st of January 2021 and the 31st December 2021 all the patients referred to our center for DHIS grade 2-4 were treated with a new surgical technique. It consists of AVF remodeling using an external nitinol support (VasQ®) to reduce the risk of outflow vein enlargement and DHIS recurrence. To better appreciate the hemodynamic effects of the surgery, a new ultrasound technique called high-frame-rate Vector Flow (HiFR-VF) was used. Seven patients (M:F 1:3; mean age 43 ± 12 years, range 29-65) were included in this study. Central line was never necessary, and technical success was 100% at 12 months. The comparison with historical data demonstrated lower recurrence of symptoms in comparison to simple artery-to-vein redo (p 0.50). The HiFR-VF showed flow with limited turbulent characteristics at the anastomosis site. The new technique proposed demonstrated to be safe and effective for treatment of DHIS, preventing symptoms recurrence. Ultrasound examination and HiFR-VF can be considered a valuable method to evaluate complex flows at the levels of vascular anastomosis.

The Transcriptomics of the Human Vein Transformation After Arteriovenous Fistula Anastomosis Uncovers Layer-Specific Remodeling and Hallmarks of Maturation Failure

The molecular transformation of the human preaccess vein after arteriovenous fistula (AVF) creation is poorly understood. This limits our ability to design efficacious therapies to improve maturation outcomes. Bulk RNA sequencing (RNA-seq) followed by paired bioinformatic analyses and validation assays were performed in 76 longitudinal vascular biopsies (veins and AVFs) from 38 patients with stage 5 chronic kidney disease or end-stage kidney disease undergoing surgeries for 2-stage AVF creation (19 matured, 19 failed). A total of 3637 transcripts were differentially expressed between veins and AVFs independent of maturation outcomes, with 80% upregulated in fistulas. The postoperative transcriptome demonstrated transcriptional activation of basement membrane and interstitial extracellular matrix (ECM) components, including preexisting and novel collagens, proteoglycans, hemostasis factors, and angiogenesis regulators. A postoperative intramural cytokine storm involved >80 chemokines, interleukins, and growth factors. Postoperative changes in ECM expression were differentially distributed in the AVF wall, with proteoglycans and fibrillar collagens predominantly found in the intima and media, respectively. Interestingly, upregulated matrisome genes were enough to make a crude separation of AVFs that failed from those with successful maturation. We identified 102 differentially expressed genes (DEGs) in association with AVF maturation failure, including upregulation of network collagen VIII in medial smooth muscle cells (SMCs) and downregulation of endothelial-predominant transcripts and ECM regulators. This work delineates the molecular changes that characterize venous remodeling after AVF creation and those relevant to maturation failure. We provide an essential framework to streamline translational models and our search for antistenotic therapies.

Hydrogel-coated needles prevent puncture site bleeding in arteriovenous fistula and arteriovenous grafts in rats

IntroductionImperfect hemostasis after arteriovenous fistula (AVF) and arteriovenous graft (AVG) cannulation can cause a hematoma or pseudoaneurysm and leads to poor satisfaction. We hypothesized that a hydrogel-coated needle would effectively and rapidly stop bleeding after vascular cannulation in a rat AVF and AVG model. MethodA hydrogel comprised of sodium alginate (SA), hyaluronic acid (HA), and calcium carbonate was coated onto the surface of suture needles using a rotating system. The needles were observed using scanning electron microscopy (SEM) and immunofluorescence. Rat AVF with or without renal failure and AVG were punctured using bare and hydrogel-coated needles. The tissues were examined by histology. ResultThe hydrogel was successfully coated onto the surface of 30 G needles and confirmed by SEM. Hydrogel-coated needles rapidly stopped bleeding after AVF and AVG cannulation in rat. ConclusionIn this preliminary animal research, hydrogel-coated needles can stop AVF and AVG puncture-site bleeding; but additional clinical studies are needed to justify whether it is still effective in clinical.

Iliac Vein Stenosis and Venous Hypertension after Polytetrafluoroethylene Arteriovenous Loop Graft in the Thigh for Hemodialysis Access

Central venous stenosis occurs commonly as a complication of central venous catheterization. It is most often seen after arteriovenous (AV) graft or proximal AV fistula in the ipsilateral upper limb. Iliac vein stenosis after thigh AV graft has not been reported in the literature. Successful endovascular management of an iliac vein stenosis after AV loop graft in the thigh is presented here.

Development of a murine iliac arteriovenous fistula model for examination of hemodialysis access-related limb pathophysiology

ObjectiveHemodialysis access-related hand dysfunction is a common clinical feature of patients with chronic kidney disease (CKD) after arteriovenous fistula (AVF) placement. The heterogeneity in symptoms and the lack of a predictive association with changes in hemodynamic alterations precipitated by the AVF suggest that other factors are involved in the mechanisms responsible for causing hand and limb dysfunction postoperatively. To the best of our knowledge, no suitable animal models have provided a platform for performing preclinical experiments designed to elucidate the biologic drivers of access-related hand dysfunction. Therefore, our objective was to develop a novel murine AVF model that could be used to study dialysis access-related limb dysfunction. MethodsMale 8-week-old C57BL/6J mice (n = 15/group) were exposed to either an adenine-supplemented diet to induce CKD or casein-based chow (control). Four weeks after the diet intervention, the mice were randomly assigned to receive an iliac AVF (n = 10/group) or sham surgery (n = 5/group) on the left hindlimb. The mice were sacrificed 2 weeks after surgery, and AVF specimens and hindlimb skeletal muscles were collected for further analysis. ResultsBefore AVF or sham surgery, the glomerular filtration rates were significantly reduced and the blood urea nitrogen levels were significantly elevated in the CKD groups compared with the controls (P < .05). AVF surgery was associated with an ∼80% patency rate among the survivors (four control and three CKD mice died postoperatively). Patency was verified by changes in hemodynamics using Doppler ultrasound imaging and altered histologic morphology. Compared with sham surgery, AVF surgery reduced ipsilateral hindlimb perfusion to the tibialis anterior muscle (20%-40%) and paw (40%-50%), which remained stable until euthanasia. Analysis of gastrocnemius muscle mitochondrial respiratory function uncovered a significant decrease (40%-50%) in mitochondrial function in the AVF mice. No changes were found in the muscle mass, myofiber cross-sectional area, or centrally nucleated fiber proportion in the extensor digitorum longus and soleus muscles between the sham and AVF mice. ConclusionsThe results from the present study have demonstrated that iliac AVF formation is a practical animal model that facilitates examination of hemodialysis access-related limb dysfunction. AVF surgery produced the expected hemodynamic changes, and evaluation of the limb muscle revealed a substantial mitochondrial impairment that was present without changes in muscle size.

A single centre experience of arteriovenous fistula creation for hemodialysis access in Dar es Salaam, Tanzania

Chronic kidney disease (CKD) is increasingly diagnosed and thus more patients are in need of hemodialysis (HD) to sustain their life. The quality of vascular access for HD should be suitable for repeated puncture and allow a fast blood flow rate for high-efficiency dialysis with minimal complications. Our study aimed to document local experience and early outcomes after arteriovenous fistula (AVF) creation for hemodialysis access including complications related to AVF creation.This was a hospital based clinical audit in which case notes of patients who had undergone AVF creation between May, 2017 and March, 2018 at Muhimbili National Hospital (MNH) were reviewed using a structured data collection tool. Information regarding preoperative assessment for AVF creation, outcome of AVF, and age of the patients were collected. Descriptive statistics were prepared and summarized as tables. A total of 57 case notes of patients who underwent AVF creation for HD access with males contributing majority of patients (77.2%) were reviewed. The predominant age group was 41 to 60 years of age (56.2%) with mean age 47 years and age range of 18 -69 years. Three patients had procedure abandoned on the table due to sclerotic vein. The functional maturation rate was found to be 64.9% and post AVF complications in 15 patients (26.3%). Recorded post AVF creation complications were fistula stenosis/revision (27.8%), bleeding/haematoma (22.2%), limb oedema (22.2%), aneurysm (11.1%), surgical site infection [SSI] (11.1%) and thrombus formation (5.6%).AVF creation for HD access is common at MNH with a functional maturation rate of 64.9%, which is an acceptable rate. The preoperative vascular assessment in this survey was mainly found to be physical examination while preoperative vascular imaging was not commonly done to assess suitability of veins and arteries for AVF creation although post AVF complications are relatively few.

A systematic review with meta-analysis of the effects of arm exercise training programs on arteriovenous fistula maturation among people with chronic kidney disease.

This study systematically reviewed the evidence and quantified the effectiveness of arm exercise training programs, before and after arteriovenous fistula (AVF) operation on AVF maturation, among people with chronic kidney disease. Scopus, CINAHL, PubMed, Science Direct, Cochrane Library, and reference lists were searched. Experimental studies that investigated the effect of arm exercise before and post-operation on AVF maturations were included. Screened and extracted data were administered by two independent reviewers. Seven studies with preoperative exercise were included in a systematic review, while five studies were analyzed in a meta-analysis. Preoperative exercise significantly increased vessel diameters and grip strength after training. Postoperative exercise had higher clinical and ultrasonographic (US) maturation rates and arterial blood flow than controls (risk ratio [RR], 1.44; 95% confidence interval [CI], 1.23-1.69; RR, 1.27; 95% CI, 1.02-1.57; weight mean difference, 166.03; 95% CI, 27.58-304.49, respectively). Subgroup analysis showed that isometric exercise training promoted clinical and US maturations (RR, 2.40; 95% CI, 1.51-3.82; RR, 1.53; 95% CI, 1.02-2.30, respectively), whereas isotonic exercise promoted clinical maturation (RR, 1.18; 95% CI, 1.03-1.34). Grip strength had a greater trend in the intervention group than controls (standardized mean difference, 0.59; 95% CI, -0.06 to 1.25). In conclusion, arm exercise training improves vascular function, which is essential before surgery. The meta-analysis suggested that arm exercise training promotes AVF clinical and US maturations after surgery. Subgroup analysis suggested that isometric-arm exercise training may have a larger effect on AVF maturation. However, more studies are needed to draw a solid conclusion.

Natural Vascular Remodelling After Arteriovenous Fistula Creation in Dialysis Patients With and Without Previous Ipsilateral Vascular Access.

The aim of the study was to observe the natural haemodynamic changes after arteriovenous fistula (AVF) creation in haemodialysis patients with and without a previous ipsilateral vascular access. This was a retrospective, single centre cohort study. Patient demographics were registered and pre- and post-operative vessel ultrasound examinations were performed at regular follow up intervals. Arteriovenous fistula outcomes in terms of vessel diameter and access flow enhancement were determined for radiocephalic, brachiocephalic, and brachiobasilic AVFs. In total, 331 patients (median age 66 years, 60% male) with 366 new autologous AVFs were studied, of whom 112 patients had a previous ipsilateral vascular access (VA). Patients with a previous ipsilateral VA had a statistically significantly greater pre-operative brachial artery diameter (4.4mm) and flow (106mL/min), and basilic vein diameter (4.9mm), compared with patients without a previous ipsilateral VA (4.0mm, 54mL/min, and 4.3mm, respectively). For all AVF configurations these differences gradually disappeared over three months after AVF creation. The haemodynamic changes reached a plateau at three months, and were statistically significantly accelerated in patients with a previous ipsilateral VA. There were no differences in primary failure or high flow complications between both groups. Arteriovenous fistulae show haemodynamic and remodelling changes up to three months post-operatively. Previous ipsilateral VAs may initiate vessel preconditioning, and accelerate the observed haemodynamic changes after AVF creation. However, this preconditioning does not result in a beneficial or detrimental effect on VA function.

True brachial artery aneurysm after arteriovenous fistula closure following renal transplantation: a case report and literature review

BackgroundA brachial artery aneurysm (BAA) is a rare condition accounting for 5% of all peripheral arterial aneurysms. More cases of true BAAs after arteriovenous fistula (AVF) closure have been reported in the past two decades.Case presentationA 60-year-old man who underwent AVF closure after renal transplantation had a true BAA on his left elbow that had grown within the past 6 months. We successfully performed an open repair with end-to-end anastomosis. No complications occurred for 1 year.ConclusionsHigh flow due to AVF and some collateral factors such as the use of steroids and immunosuppressants after renal transplantation, arteriosclerosis, and chronic mechanical stimulation might contribute to BAA formation.

A new technique for measuring fistula flow using venous blood gas oxygen saturation in patients with a central venous catheter.

BackgroundDoppler ultrasound (DU) monitoring early after arteriovenous fistula (AVF) creation allows the identification of low blood flow (Qa) requiring prompt revision, but it is costly (needs skilled operators and technical instruments) and is not available in all dialysis units. Therefore alternative first-line methods to measure Qa would be welcomed. We reasoned that once an AVF is created, an increment in central venous oxygen saturation (ScvO2) is predictable and proportional to Qa.MethodsAccordingly, in patients receiving dialysis through a central venous catheter (CVC) in whom an AVF was created, we measured, by means of blood gas analysis, the ScvO2 increment before and after manual compression of the arteriovenous shunt and verified its correlation with DU-measured Qa.ResultsWe sampled blood gas in 18 patients with CVC and AVF before and after 30 s manual compression of the AVF. ScvO2 averaged 70.5 ± 3% before and 65.2 ± 3% after AVF closure, with an average drop of 5.1 ± 3% (range 1–12). AVF Qa, which was measured within 24 h by means of DU, averaged 635 ± 349 mL/min (range 50–1300) and was strictly and positively correlated with ΔScvO2 (r = 0.954, P < 0.0001).ConclusionsTherefore we suggest that in patients with CVC and a newly created AVF, it is possible to monitor AVF Qa without DU by simply measuring blood gas and ΔScvO2. This technique is simple, cheap, repeatable, non-invasive and operator independent and represents a new useful screening test to detect delayed AVF access maturation deserving prompt DU measurement and surgical revision. It helps to quickly identify patients in urgent need of DU verification and possible surgical revision. Regrettably, it is applicable only in patients with CVC.

Non-contrast MRI methods as a tool for the pre-operative assessment and surveillance of the arterio-venous fistula for haemodialysis

ObjectiveTo compare non-contrast enhanced MRI with ultrasound (US) for measurement of arm blood vessel geometries and flow velocities in volunteers and patients with end-stage renal disease.Materials and methodsSubjects were scanned using US (reference standard), and MRI 2D time-of-flight (ToF), 2D phase contrast (PC), and 3D multi-echo data image combination (MEDIC). Patients were also scanned after arteriovenous fistula (AVF) surgery.ResultsFor mean vessel diameters (radial and brachial arteries; cephalic vein) MEDIC measurements were similar to US (p > 0.05). However, ToF underestimated the mean diameter of the cephalic vein relative to US (p < 0.05). For arterial velocity measurements, the mean values derived by PC-MR and US were similar (p > 0.05). Post-operatively, the intra-luminal signal intensity was hypo-intense at the anastomosis site using ToF and MEDIC. At the same site the outer boundary of the vessel was consistently lost on ToF, but remained clearly delineated on the MEDIC images.DiscussionWith the exception of ToF, the MRI data demonstrated excellent agreement with US for measurements of vessel geometry and flow velocity. Further, the ability to clearly delineate the post-surgery vessel edges with MEDIC MRI suggests that the technique may be useful for surveillance after AVF creation or for patient-specific modelling studies.

Early experiences of intraoperative ultrasound guided angioplasty of the arterial stenosis during upper limb arteriovenous fistula creation.

In recent years the high prevalence of diabetes and atherosclerosis in elderly uremic patients starting hemodialysis (HD) has led to the increase in the risk of vascular access (VA) failure caused by pre-existing arterial diseases, including both VA slow maturation and early failure, and upper limb ischemic symptoms. Recently, in performing radial (R), brachial (B) and ulnar (U) artery (A) percutaneous transluminal angioplasty (PTA) in HD patients affected by access thrombosis, with insufficient blood flow and severe upper limb ischemia, good outcomes have been reported. Nevertheless, these procedures were performed after arteriovenous fistula (AVF) creation. About 2 years ago, we approached an intra-operative ultrasound-guided transluminal angioplasty (IUTA) performed during AVF creation, using the arterial incision, necessary because of the anastomosis, to introduce the necessary devices for the IUTA. The arterial stenosis having undergone IUTA was diagnosed by a preliminary ultrasound examination. Ultrasound guidance during the procedure is necessary for correct balloon location in the stenosis site. We treated seven patients (four diabetics), mean age 76 + 5 yrs. In all cases, the radial arteries because of hyposphygmia, were unfit for AVF creation. Four distal radio-cephalic AVFs at the wrist were created in patients 1, 3, 4 and 5; in the other three patients (2, 6 and 7), with failure or thrombosis of previous distal AVFs, an immediately upstream anastomosis was performed. In all cases, first, the area selected to perform the AV anastomosis was exposed, then the AR was incised, and the introductory metallic guide wire and the angioplasty catheter (with dimensions decided after PUS), were introduced. The balloon was inflated to 8-13 atm for 30-35 sec. In two patients a stent was also positioned. Later, a side-to-side AVF was created, closing the distal venous vessel. Patient follow-up ranged from 6-22 months. The ultrasound evaluation after IUTA showed the correction of all the stenosis treated. AVF maturation was good, except for the stented ones, which were inadequate. In conclusion, our early experience shows IUTA could be an adequate and effective procedure allowing the use of the stenotic arteries (otherwise unsuitable) for AVF creation. In our experience, stenting after IUTA does not add any other advantages.

Aneurysmal Degeneration of the Brachial Artery after Vascular Access Creation: Surgical Treatment Results

True peripheral artery aneurysms proximal to a longstanding arteriovenous fistula is a well-recognized complication. Late aneurysmal degeneration is rare. This study analyzed the characteristics, therapeutic options, and outcomes of true donor brachial artery aneurysms (DBAA) after arteriovenous fistula (AVF) for hemodialysis. We retrospectively collected the data of patients with DBAA after AVF creation, surgically repaired between January 2001 and September 2015. We excluded patients with pseudoaneurysms, anastomotic aneurysms, and infected aneurysms. We recorded patient's demographics, type of access, aneurysm characteristics, symptoms, treatment, and follow-up. Ten patients were treated for aneurysmal degeneration of the brachial artery. Average aneurysm diameter was 37.5 mm. All cases had, at least, one previous distal AVF, ligated or thrombosed, at the time of diagnosis. The first access was created in mean 137 months before the diagnosis of DBAA. Nine patients had previous medical history of renal transplant and were under immunosuppressive therapy. All patients were symptomatic at the time of diagnosis. In all cases, the treatment was aneurysmectomy followed by interposition bypass. One patient developed a postoperative hematoma with the need of surgical drainage. At 50 months of follow-up, one patient was submitted to percutaneous angioplasty due to an anastomotic stenosis. No other complications occurred during the entire follow-up period (mean: 69 months). The pathogenesis underlying DBAA remains unclear. Increased blood flow after AVF creation, immunosuppressive therapy, and ligation/thrombosis of the AVF may contribute to aneurysm formation. Surgical treatment by aneurysmectomy and bypass, with autogenous conducts, is a safe and effective option.

Upper limb DVT after hemodialysis AVF creation: Role of CT venography

ObjectiveThe aim of this study was to assess the role of CT venography (CTV) in diagnosis of upper limb deep venous thrombosis (DVT) after arterio-venous fistula (AVF) creation for patients with chronic renal failure (CRF) under regular hemodialysis. Patients and methodsDuring two years duration 22 patients with upper limb hemodialysis arterio-venous fistulas suspected to have deep venous thrombosis were prospectively evaluated. All patients underwent CTV examinations following a preset protocol. The images obtained were reconstructed using dedicated software and workstations. Results of CTV examinations were compared with those of Color Doppler (CD) examinations. ResultsOut of 22 examined cases, 20 cases (90.9%) had autogenous AVF and 2 cases (9.1%) had synthetic grafts.Diagnosis of proximal upper limb segment DVT including brachial, axillary and subclavian veins recorded 12 TP (54.5%), 8 TN (36.4%), 2 FP (9.1%) and no FN cases. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 100%, 80%, 85.7% and 100% respectively.Diagnosis of central venous segment DVT including innominate veins and SVC recorded 14 TP (63.6%), 8 TN (36.4%) and neither FP nor FN cases. Sensitivity, specificity, PPV and NPV were 100%, 100%, 100% and 100% respectively. ConclusionCTV has a major role in diagnosis of deep venous thrombosis particularly the central innominate veins/SVC segment after upper limb AVF creation for patients with CRF under hemodialysis.

Effect of a postoperative exercise program on arteriovenous fistula maturation: A randomized controlled trial.

Exercises after arteriovenous fistula (AVF) creation may help to improve maturation; however, their usefulness has only been examined in indirect, non-comparative studies or small trials. Between June 2013 and November 2014, we included all ambulatory patients with stages 5-5D chronic kidney disease who were candidates for the creation of a native AVF in our center. After surgery, all patients were randomized to an exercise group or a control group with single-blind control. At 1 month postoperatively, clinical maturation (expert nurse inspection) and ultrasonographic maturation (flow >500 mL/min, venous diameter >5 mm and depth <6 mm) were assessed in all patients. A total of 72 patients were randomized, 3 were lost to follow-up, and 69 were finally analyzed. The mean age was 66.8 years (standard deviation 13.8), 70.0% were men, and 65.2% were in pre-dialysis. After surgery (42.0% had distal AVF), the patients were randomized (31 controls, 38 exercise group). At 1 month after surgery, global clinical and ultrasonographic maturation was assessed in 88.4% and 78.3% of AVF, respectively (kappa = 0.539). Non-significant differences in clinical or ultrasonographic maturation were seen between exercise and control group (94.7% vs. 80.6%, P = 0.069; 81.6% vs. 74.2%, P = 0.459). A stepwise logistic regression was performed to control previously analyzed asymmetrically distributed confounding factors (AVF localization), revealing that the exercise group showed greater clinical, but not ultrasonographic, maturation (odds ratio [OR] 5.861, 95% confidence interval: 1.006-34.146 and OR 2.403, 0.66-8.754). A postoperative controlled exercise program after AVF creation seems to increase 1-month clinical AVF maturation in distal accesses. Furthermore, exercise programs should be taken into account, especially in distal accesses.

In Vitro Study of a Medical Device to Enhance Arteriovenous Fistula Eligibility and Maturation.

The arteriovenous fistula eligibility (AFE) system (Flow Forward Medical, Olathe, KS) is a small, temporary, wearable rotary blood pump system designed to rapidly dilate peripheral veins in hemodialysis patients and improve outcomes after arteriovenous fistula (AVF) creation. A benchtop pulsatile mock circulatory loop was developed to model forearm circulation and to compare the hemodynamics of the AFE system with those of a conventional radiocephalic AVF. The AFE system maintained a mean wall shear stress (mWSS) within the 2.5-7.5 Pa target range for cephalic outflow veins of 2-6 mm diameter, which when applied clinically will provide better control of mWSS during the outflow vein maturation process when compared with a conventional AVF. These results support further study to determine whether or not vein preconditioning with the AFE system under controlled levels of mWSS will promote improved AVF outcomes.