Arteriovenous Fistula Blood Flow Research Articles

Risk Factors and Utility of Intraoperative Arteriovenous Fistula Blood Flow Level as a Surrogate Marker of Arteriovenous Fistula Failure in Patients with End-stage Renal Disease.

An arteriovenous fistula (AVF) can fail for different reasons at each stage after its creation. The study aimed to analyze the associations of the clinical and laboratory parameters, including the intraoperative AVF blood flow, with AVF failure at different periods (3 weeks and 3, 6, 9, 12, 24, and 36 months) after the AVF's creation and to evaluate the usefulness of the intraoperative AVF blood flow as a surrogate marker of AVF failure in patients with end-stage renal disease (ESRD). This was a single-center, retrospective cohort study that included 130 patients with ESRD who underwent the creation of new radiocephalic AVFs. The associations of the preoperative clinical and laboratory parameters and intraoperative flow with AVF failure in the different observation periods were investigated. Intraoperative AVF blood flow was significantly associated with AVF failure from 3 weeks to 24 months (P <0.05). Hemoglobin level and the size of the anastomosis were significantly associated with AVF failure at 6 months (P <0.05). In the analysis of the receiver operating characteristic curve, intraoperative AVF blood flow was significant from 3 weeks to 24 months (P <0.05). The intraoperative blood flow with the greatest sensitivity and specificity was 205-225 mL/min. Intraoperative blood flow was independently associated with AVF failure from 3 weeks to 24 months after the AVF's creation. An intraoperative AVF blood flow of >225 mL/min is crucial for long-term AVF patency. The intraoperative AVF blood flow level could be a surrogate marker of AVF failure in ESRD patients.

Analysis of Geometric and Hemodynamic Profiles in Rat Arteriovenous Fistula Following PDE5A Inhibition.

Arteriovenous fistula (AVF) is essential for chronic kidney disease (CKD) patients on hemodialysis, but treatment for AVF maturation failure remains an unmet clinical need. Successful AVF remodeling occurs through sufficient lumen expansion to increase AVF blood flow and lumen area. Aberrant blood flow is thought to impair AVF remodeling, but previous literature has largely focused on hemodynamics averaged over the entire AVF or at a single location. We hypothesized that hemodynamics is heterogeneous, and thus any treatment’s effect size is heterogeneous in the AVF. To test our hypothesis, we used the PDE5A inhibitor sildenafil to treat AVFs in a rat model and performed magnetic resonance imaging (MRI) based computational fluid dynamics (CFD) to generate a detailed spatial profile of hemodynamics in AVFs. 90 mg/kg of sildenafil was administered to rats in their drinking water for 14 days. On day 14 femoral AVFs were created in rats and sildenafil treatment continued for another 21 days. 21 days post-AVF creation, rats underwent non-contrast MRI for CFD and geometrical analysis. Lumen cross-sectional area (CSA) and flow rate were used to quantify AVF remodeling. Parameters used to describe aberrant blood flow include velocity magnitude, wall shear stress (WSS), oscillatory shear index (OSI), and vorticity. Geometrical parameters include arterial-venous (A-V) distance, anastomosis angle, tortuosity, and nonplanarity angle magnitude. When averaged across the entire AVF, sildenafil treated rats had significantly higher CSA, flow rate, velocity, WSS, OSI, and vorticity than control rats. To analyze heterogeneity, the vein was separated into zones: 0–5, 5–10, 10–15, and 15–20 mm from the anastomosis. In both groups: 1) CSA increased from the 0–5 to 15–20 zone; 2) velocity, WSS, and vorticity were highest in the 0–5 zone and dropped significantly thereafter; and 3) OSI increased at the 5–10 zone and then decreased gradually. Thus, the effect size of sildenafil on AVF remodeling and the relationship between hemodynamics and AVF remodeling depend on location. There was no significant difference between control and sildenafil groups for the other geometric parameters. Rats tolerated sildenafil treatment well, and our results suggest that sildenafil may be a safe and effective therapy for AVF maturation.

Plan, Do, Check, Act (PDCA) Cycle Nursing Model Reduces the Risk of Hemangioma in Hemodialysis Patients.

Background:We aimed to explore the effect of Plan, Do, Check, Act (PDCA) circulation nursing on the prevention of aneurysm after hemodialysis.Methods:A total of 139 hemodialysis patients from Oct 2018 to Jan 2020 in Nephrology Department of the First People’s Hospital of Lianyungang, China were enrolled. They were randomly divided into control group and PCDA group, including 58 patients in control group and 81 patients in PCDA group. Patients’ satisfaction, blood flow in arteriovenous internal fistula and the incidence of post-dialysis vascular-related complications were statistically investigated in the two groups.Results:The satisfaction of patients in PDCA group was significantly higher than that in control group (P<0.001). In addition, when there was no statistical difference in blood flow between the two groups, the probability of complications such as internal fistula obstruction, thrombosis, infection, secondary puncture and aneurysm was lower in patients in the PDCA group, none of which occurred aneurysm.Conclusion:PDCA circulation nursing can effectively improve the quality of care and medical effect of hemodialysis patients with internal arteriovenous fistula, improve patient satisfaction and reduce the incidence of complications.

Computational modeling of the cephalic arch predicts hemodynamic profiles in patients with brachiocephalic fistula access receiving hemodialysis

The most common configuration for arteriovenous fistula is brachiocephalic which often develop cephalic arch stenosis leading to the need for numerous procedures to maintain access patency. The hemodynamics that contributes to the development of cephalic arch stenosis is incompletely understood given the inability to accurately determine shear stress in the cephalic arch. In the current investigation our aim was to determine pressure, velocity and wall shear stress profiles in the cephalic arch in 3D using computational modeling as tools to understand stenosis. Five subjects with brachiocephalic fistula access had protocol labs, Doppler, venogram and intravascular ultrasound imaging performed at 3 and 12 months. 3D reconstructions of the cephalic arch were generated by combining intravascular ultrasounds and venograms. Standard finite element analysis software was used to simulate time dependent blood flow in the cephalic arch with velocity, pressure and wall shear stress profiles generated. Our models generated from imaging and flow measurements at 3 and 12 months offer snapshots of the patient's cephalic arch at a precise time point, although the remodeling of the vessel downstream of an arteriovenous fistula in patients undergoing regular dialysis is a dynamic process that persists over long periods of time (~ 5 years). The velocity and pressure increase at the cephalic bend cause abnormal hemodynamics most prominent along the inner wall of the terminal cephalic arch. The topology of the cephalic arch is highly variable between subjects and predictive of pathologic stenosis at later time points. Low flow velocity and wall pressure along the inner wall of the bend may provide possible nidus of endothelial activation that leads to stenosis and thrombosis. In addition, 3D modelling of the arch can indicate areas of stenosis that may be missed by venograms alone. Computational modeling reconstructed from 3D radiologic imaging and Doppler flow provides important insights into the hemodynamics of blood flow in arteriovenous fistula. This technique could be used in future studies to determine optimal flow to prevent endothelial damage for patients with arteriovenous fistula access.

MO746CARDIAC REMODELING AND PULMONARY HYPERTENSION IN HEMODIALYSIS PATIENTS

Abstract Background and Aims An important predictor of cardiovascular mortality and morbidity in hemodialysis patients is left ventricular hypertrophy. Also, pulmonary hypertension is a risk factor for mortality and cardiovascular events in hemodialysis patients. The aim of this study was to investigate cardiac remodeling and the dynamics of pulmonary arterial pressure during a year-long hemodialysis treatment and to evaluate relationship between pulmonary arterial pressure and blood flow in arteriovenous fistula. Method Hemodialysis patients (n=88; 42 males, 46 females, mean age was 51.7±13.0 years) were studied. Echocardiography and Doppler echocardiography were performed in the beginning of hemodialysis treatment and after a year. Echocardiographic evaluation was carried out on the day after dialysis. Left ventricular mass index (LVMI) was calculated. Left ventricular ejection fraction (LVEF) was measured by the echocardiographic Simpson method. Arteriovenous fistula flow was determined by Doppler echocardiography. Pulmonary hypertension was diagnosed according to criteria of Guidelines for the diagnosis and treatment of pulmonary hypertension of the European Society of Cardiology. Results Pulmonary hypertension was diagnosed in 47 (53.4%) patients. Left ventricular hypertrophy was revealed in 71 (80.7%) patients. Only 2 (2.3%) patients had LVEF&amp;lt;50%. At the beginning of hemodialysis correlation was detected between systolic pulmonary arterial pressure and LVMI (r=0.52; P&amp;lt;0.001). Systolic pulmonary arterial pressure negatively correlated with left ventricular ejection fraction (r=-0.20; P=0.04). After a year of hemodialysis treatment LVMI decreased from 140.49±42.95 to 123.25±39.27 g/m2 (р=0.006) mainly due to a decrease in left ventricular end-diastolic dimension (from 50.23±6.48 to 45.13±5.24 mm, p=0.04) and systolic pulmonary arterial pressure decreased from 44.83±14.53 to 39.14±10.29 mmHg (р=0.002). Correlation wasn’t found between systolic pulmonary arterial pressure and arteriovenous fistula flow (r=0.17; p=0.4). Conclusion Pulmonary hypertension was diagnosed in half of patients at the beginning of hemodialysis treatment. Pulmonary hypertension in hemodialysis patients was associated with left ventricular hypertrophy, systolic left ventricular dysfunction. After a year-long hemodialysis treatment, a regress in left ventricular hypertrophy and a partial decrease in pulmonary arterial pressure were observed. There wasn’t correlation between arteriovenous fistula flow and systolic pulmonary arterial pressure.

Reduction of arteriovenous access blood flow leads to biventricular unloading in haemodialysis patients

AimsPatients on chronic haemodialysis have a wide range of changes in cardiac function and structure, including left ventricular hypertrophy, dilation and diastolic dysfunction or pulmonary hypertension. All these changes were linked to increased mortality in previous studies. High-flow arteriovenous fistulas (AVF) are supposed to be a factor contributing to their development. This study investigated the early effect of surgical AVF blood flow (Qa) reduction on these changes in patients with or without heart failure changes. Methods and resultsForty-two patients in chronic haemodialysis programme with high-flow AVF (Qa over 1500 mL/min), indicated for surgery for ≥1 of the following indications: 1.manifest heart failure; 2.hand ischemia; 3.advanced structural heart changes detected by echocardiography. The patients underwent echocardiography on selection visit, before blood flow reducing surgery and six weeks thereafter. The Qa reduction led to decrease of left ventricular mass (p = 0.02), end-diastolic volume (p = 0.008), end-diastolic diameter (p = 0.003) and left atrial volume (p = 0.0006). Diastolic function improved. Similarly, right ventricular diameter and right atrial volume decreased (p = 0.000001 and 0.00009, respectively) together with the decrease of estimated pulmonary artery systolic pressure. 81% of patients suffered from pulmonary hypertension prior to surgery, only 36% thereafter. ConclusionThe surgical restriction of the hyperkinetic circulation leads to several improvements of heart structure and function, which was linked to higher mortality in other studies. The beneficial effect of Qa reduction is present even in patients without symptoms of heart failure. The contribution of AVF must be considered with structural or functional heart changes.

Inhibition of Lysyl Oxidase with β-aminopropionitrile Improves Venous Adaptation after Arteriovenous Fistula Creation.

The arteriovenous fistula (AVF) is the preferred hemodialysis access for end-stage renal disease (ESRD) patients. Yet, establishment of a functional AVF presents a challenge, even for the most experienced surgeons, since postoperative stenosis frequently occludes the AVF. Stenosis results from the loss of compliance in fibrotic areas of the fistula which turns intimal hyperplasia into an occlusive feature. Fibrotic remodeling depends on deposition and crosslinking of collagen by lysyl oxidase (LOX), an enzyme that catalyzes the deamination of lysine and hydroxylysine residues, facilitating intra/intermolecular covalent bonds. We postulate that pharmacological inhibition of lysyl oxidase (LOX) increases postoperative venous compliance and prevents stenosis in a rat AVF model. LOX gene expression and vascular localization were assayed in rat AVFs and human pre-access veins, respectively. Collagen crosslinking was measured in humans AVFs that matured or failed, and in rat AVFs treated with β-aminopropionitrile (BAPN), an irreversible LOX inhibitor. BAPN was either injected systemically or delivered locally around rat AVFs using nanofiber scaffolds. The major endpoints were AVF blood flow, wall fibrosis, collagen crosslinking, and vascular distensibility. Non-maturation of human AVFs was associated with higher LOX deposition in pre-access veins (N=20, P=0.029), and increased trivalent crosslinks (N=18, P=0.027) in human AVF tissues. Systemic and local inhibition of LOX increased AVF distensibility, while reducing wall fibrosis and collagen crosslinking in rat fistulas. Our results demonstrate that BAPN-mediated inhibition of LOX significantly improves vascular remodeling in experimental fistulas.

To ligate or not to ligate hemodialysis arteriovenous fistulas in kidney transplant patients.

There is significant disagreement about maintenance or ligation of arteriovenous fistulas (AVFs) in kidney transplant patients (KTPs). Potential harms from maintaining AVFs are their impact on cardiac function, cosmetic concerns and complications such as bleeding and rupture. High flow AVFs can place a strain on the heart and cause or exacerbate pre-existing cardiac dysfunction. There is an improvement in cardiac function after kidney transplantation independent of vascular access status. Studies comparing cardiac parameters in patients with and without AVFs after renal transplantation have shown conflicting results. Ligation of high flow AVFs in KTPs resulted in improvement in cardiac function and prevention of heart failure. In KTPs with deteriorating renal function and high flow AVFs, banding of the AVFs to reduce flow is an option. Patients who retain AVFs after renal transplant have the advantage of immediate, optimal access should the transplant fail and may have preserved kidney function. The patient's post-transplant kidney function, risk factors for transplant loss, AVF blood flow, and cardiac function play an important role when making the decision to ligate or preserve AVFs.

Impact of preoperative arterial and venous diameter on achievement of the adequate blood flow in arteriovenous fistula for hemodialysis.

An arteriovenous fistula (AVF) remains the best choice of vascular access (VA) for hemodialysis (HD). The aim of the study was to determine the factors associated with the achievement of adequate blood flow (BF) of AVFs at the 4th week after creation. Created AVFs in 63 patients with chronic kidney disease (CKD) stage 4/5 and CKD stage 5 on hemodialysis (CKD5D) were analyzed in a prospective study. Doppler ultrasound (DUS) was used for measuring the diameter of the radial artery, the brachial artery and the cephalic vein before AVF creation. The BF of AVF was calculated by DUS at the 4th week after creation and adequate BF was defined as ≥ 600 mL/min. The average age of patients was 61.31 ± 12.9 years. An adequate BF of AVF at the 4th week after creation was achieved in 43.54% of patients. The BF of AVF measured in male patients was significantly higher compared to the BF of AVF obtained in females (576.03 mL/min vs 375.12 mL/min, P = 0.004). The diameter of the blood vessels with achieved adequate BF was significantly larger compared to the diameter of the blood vessels without adequate BF (radial artery: 2.45 mm vs 2.03 mm, P = 0.000; brachial artery: 4.78 mm vs 4.06 mm, P = 0.001 and cephalic vein: 3.12 mm vs 2.83 mm P = 0.018). The gender and the diameter of the blood vessels before AVF creation were significantly associated with achievement of adequate BF of AVF at the 4th week of creation.

Role of early postoperative ultrasonography in prediction of AV fistula failure in hemodialysis patients

BackgroundDoppler ultrasonography (US) is the main imaging modality of hemodialysis AV fistula as it is safe non-invasive accurate modality. This study is to measure the arteriovenous (AV) fistula blood flow during early postoperative period (7–14 days) and assess its predictive role in AV fistula failure in hemodialysis patients. Color Doppler ultrasonography (CDU) was used to estimate the blood flow in the AV fistula of 100 patients at (7–14 days) after the fistula creation. The performance of fistula blood flow during early postoperative periods for predicting fistula failure was evaluated, and optimal cutoff value was determined.ResultsDuring the follow-up period (6 months), we classified the fistulas as 82 mature, and 18 failed. The blood flow was considerably lower in the failure group than that in the mature group at the early postoperative period (P value = 0.001). The areas under the curves (AUC) were 0.952, and the cutoff value was 200.5 ml/min. The sensitivity of CDU in prediction of fistula failure is 99% with negative predictive value 94% and accuracy 97%, and with specificity 89% and positive predictive value 98%.ConclusionMeasuring blood flow of the AV fistula at the early postoperative period probably has a predictive role in the AV fistula failure. There is risk of failure if the blood flow less than 200 ml/min at (day 7–14)

P1337ENDOVASCULAR REVISION OF ARTERIOVENOUS ANASTOMOSIS BY DOUBLE GUIDE TECHNIQUE

Abstract Background and Aims Juxta-anastomotic stenosis is the most frequent complication of arteriovenous fistula (AVF) for haemodialysis (HD). Treatment options are surgical bypass by creating a more proximal anastomosis or endovascular treatment by angioplasty. The available literature data show equal outcomes in term of secondary patency, but a significantly higher rate of recurrent stenosis for endovascular treatment (0.5 procedure/AVF/year). We describe the results of endovascular treatment by “double guide technique” (DGT) as to Turmel Rodrigues original description, in a series of patients referred to our centre. Method We describe all consecutive patients treated by DGT in the first semester of 2018 because of a de novo occurring juxta-anastomotic stenosis of the arteriovenous fistula for haemodialysis. The procedure was carried out as described by Turmell Rodrigues. In short: by means of a single retrograde access through the outflow vein by a 6 french valved introducer, two guide wire are navigated into both proximal and distal artery. Two consecutive dilatation of the anastomosis area are then performed including first the juxta-anastomotic vein at 6 to 7 mm (mean 6.7mm, ds 0.55), followed by the juxta-anastomotic artery at 4mm (mean 4.1mm, ds 0.33), as show in figures. Follow up was carried out at 1, 3, 6 12 month by clinical examination and ultrasound examination. Prospectively collected data was analyzed retrospectively. Results 25 patients were treated during the first 6 month of 2018 by a single operator. Patients data (mean): age 71years, HD vintage 31month, AVF vintage 31month. AVF distribution were: distal radio-cephalic 32%, proximal radio-cephalic 52%, distal ulnar-basilic 8%, humero-basilic 8%. Mean preoperative AVF blood flow - as measured by duplex ultrasound (US) - was 540ml/min. 32% of AVF have preoperative blood flow &amp;gt;600ml/min but a critical stenosis (&amp;lt;1.9mm of diameter). Mean juxta-anastomotic vein and juxta-anastomotic artery ballon diameter were 6.7mm (ds 0.55) and 4.1mm (ds 0.33) respectively. Overall mean blood flow at 12 month was 830ml/min. During follow up 3 patients required endovascular treatment of some new occurring stenosis, 3 patients were lost to follow up at 12 month, 1 patient died from unrelated reasons. In 52% of patients any other revision was required, while 32% required 1 further angioplasty, 4% 2 further angioplasty and 4% 4 further angioplasty of the target lesion during the following 12 month (recurrence rate: 0.28 procedure/patients/year). Assisted functional patency at 12month was 95%. Conclusion Endovascular treatment of juxta-anastomotic AVF stenosis by the DGT performed quite satisfactorily in our series and showed a low recurrence on the target lesion compared to data from literature. At 12 month the average AVF blood flow was below 1000ml/min. The technical advantage of the DGT consist in the single, small caliber percutaneous access, needed to complete the procedure. A larger series would confirm how this refinement of the technique compares with the improved results we preliminary observed.

P1319AMBIGUOUS RESULTS OF CENTRAL VEIN STENOSIS ENDOVASCULAR TREATMENT IN HEMODIALYSIS PATIENTS

Abstract Background and Aims Balloon angioplasty (BA) without the use of stents has unsatisfactory results, which may cast doubt on its expediency. At the same time, BA is a very expensive treatment method. We conducted a comprehensive comparative analysis of the native arteriovenous fistula (AVF) patency rates in hemodialysis patients with central venous stenosis (CVS) after endovascular BA and «open» palliative surgery. Method A retrospective study included 80 patients with confirmed central vein stenosis: subclavian, brachiocephalic veins, vena cava inferior, or multiple lesions. The main group included 39 patients who underwent percutaneous balloon angioplasty. The control group included 41 patients who did not have balloon angioplasty for various reasons. In this patients we performed only «open» palliative interventions: thrombectomy, proximalization of arteriovenous anastomosis, AVF blood flow reduction. Results Functional primary patency (the time interval between the start of AVF using and the first intervention) did not differ: groups were comparable in time of stenosis manifestation (fig. 1A). Primary patency (the time interval between the first and second interventions) after BA was statistically significantly better than in the main group (fig. 1B), but difference was minimal: median survival in the study group of 8 months [95% CI 6; 10] vs. - 6 months [95% CI 4.9; 7.1]. There was the strong negative correlation between the primary patency and functional primary patency in the main group (r = –0.627 [95%CI –0.787; –0.388], p &amp;lt;0.0001) but not in the control group (r = 0.049 [95%CI –0.262; –0.351], p = 0.7599). Thus, the later manifestation of CVS related with lower effectiveness of BA. The functional secondary patency (total duration of AVF use) in the main group was significantly better: median survival was 47 months [95% CI 40.9; 53.1] vs. 34 months [95% CI 29.8; 38.2] as well as secondary patency (the time interval between the first intervention and the complete cessation of AVF use): median survival was 16 months [95% CI 12.5; 19.5] vs. 7 months [95% CI 4.9; 9.1] (fig. 1 C and D). The occlusion-free period from the moment of starting the AVF use (functional primary assisted patency – fig. 1E) was higher in the main group, but difference was minimal: median survival was 39 months [95% CI 36.5; 41.5] vs. 32 months [95% CI 27.5; 36.5], as well as occlusion-free period from the moment of the first surgical intervention (primary assisted patency – fig. 1F) median survival was 9 months [95% CI 7; 11], in the control group - 7 months [95% CI 5.6; 8.4]. The need for open interventions was lower in the main group: 0.374 [95% CI 0.24; 0.556] and 2.451 [95% CI 1.1963; 3.023] per 10 patient-months, incidence rate ratio (IRR)= 0.153 [95% CI 0.095; 0.237], р&amp;lt;0.0001; as well as overall need for interventions: 1.511 [95% CI 1.225; 1.843] and 2.451 [95% CI 1.963; 3.023] per 10 patient-months, IRR 0.617 [95% CI 0.461; 0.825] p=0.0011. The value of AVF volume blood flow had a strong negative correlation with the primary patency in both groups (r = –0.529, p =0.0027; r = –0.419, p =0.0101). Conclusion 1. Central vein stenosis is inevitably leads to loss of vascular access on the ipsilateral side. 2. Balloon angioplasty allows to extend the period of AVF use but it is not a radical treatment method of CVS. 3. The results of balloon angioplasty are significantly affected by the length of the period from the start of AVF use to the CVS manifestation. 4. Multiple repeated BA are apparently justified in patients for whom the possibility of creating a new vascular access is doubtful. 4. The AVF volume blood flow is an important factor determining the severity of CVS clinical manifestations and the need for repeated surgical interventions.

Les peptides natriurétiques en dialyse : de la théorie à la pratique

Cardiologists and emergency-wards physicians are used to check natriuretic peptides serum level, mainly B-type natriuretic peptide and N-terminal pro-Brain natriuretic peptide for acute cardiac failure diagnosis. Due to their accumulation in chronic kidney disease and their elimination by dialysis, natriuretic peptides sampling remains debatable in chronic kidney disease patients. In dialysis patients, high natriuretic peptides values are associated with mortality, left ventricular hypertrophy and cardiac failure. However, a single value cannot provide a reliable diagnosis. Our clinical practice is as follows: First, we prefer B-type natriuretic peptide to N-terminal pro-Brain natriuretic peptide because of its shorter half-life, with less impact of renal function and dialysis, making its interpretation easier in case of advanced chronic kidney disease or in dialysis patients; second, we define a reference value of B-type natriuretic peptide at dry weight from serial measurements; third, the B-type natriuretic peptide changes are interpreted according to extracellular fluid and cardiac status, but also from the arteriovenous fistula blood flow. In stable dialysis patients, B-type natriuretic peptide is sampled monthly and weekly in unstable patients. We illustrate our experience using clinical cases of overhydration, new cardiac disease onset, hypovolemia and arteriovenous fistula with high blood flow. Longitudinal follow-up of B-type natriuretic peptide is an important advance in dialysis patients in order to detect and treat extracellular fluid variations and cardiac disease status early, both important factors associated with hard outcomes.

Effect of Natural Vascular Scaffolding Therapy on Rat Arteriovenous Fistula Development

BackgroundA mature arteriovenous fistula (AVF) has sufficient enlargement of vascular lumen (i.e. outward remodeling) and limited neointimal hyperplasia (i.e. inward remodeling) to allow increases in AVF blood flow for dialysis. The required vascular wall distention is likely affected by the integrity of vascular extracellular matrix (ECM). We hypothesized that preserving ECM integrity at the time of AVF creation surgery could improve AVF development. Collagen and elastin are the most abundant vascular ECM components and are key regulators of vascular remodeling. Natural Vascular Scaffolding (NVS) Therapy is known to interlink collagen and elastin by covalently linking these proteins via photoactivation. Thus, we investigated the effect of NVS treatment on AVF development.MethodsFemoral AVFs were created in young Wistar male rats by connecting the femoral artery (side) and femoral vein (end) in the same limb. Immediately after the blood flow was restored and dilatation of the femoral vein occurred, a 10 μl‐drop of the NVS compound (at 2 mg/ml diluted in phosphate buffered saline (PBS)) was placed at the anastomosis perivascularly and incubated for 5 minutes, giving the compound time to diffuse into the vascular wall. Next, the NVS compound was activated by a 1 minute illumination by 450nm light. The control group received a 10 μl‐drop of PBS and the same light activation. The skin was closed immediately after light activation. Rats were euthanized 1 week (early time point, 4 per group) and 4 weeks (later time point, 10 per group) post‐AVF creation for histology and morphometry. Verhoeff‐Van Gieson (VVG)‐stained thin cross‐sections were used to measure the area enclosed by internal elastic lamina (IEL), the area of open lumen, and the area of neointimal hyperplasia (NH) by Image J software. The percent open lumen area was calculated by “open lumen area/IEL‐enclosed area X 100%”. These analyses were done at three locations: the entire AVF, the AVF venous limb, and the AVF arterial limb.ResultsThe animals tolerated the treatment well in both experimental groups. At 1 week, the entire AVF’s lumen looked similar between treated and control groups. At 4 weeks, however, the entire AVF’s open lumen area and % open lumen area were trending larger in treated rats than in control rats, being 2.25 and 1.49‐folds larger, respectively (p=0.062, p=0.052). When the venous and arterial sides of the AVF were considered, the difference in open lumen area occurred in the venous side, where the AVF venous limb’s open lumen area and % open lumen area in treated rats were 4.18 and 1.98‐folds larger than in control rats, respectively (p=0.014, p=0.009). The AVF arterial limb’s open lumen area was similar in both groups. Importantly, the NH area was similar in both groups, regardless of the locations.ConclusionOur studies showed that rats tolerated NVS treatment well and the NVS treatment significantly increased the AVF open lumen area, without significantly affecting the NH area, suggesting that NVS treatment may have therapeutic potential by facilitating outward remodeling to enhance AVF maturation in patients.Support or Funding InformationAlucent Biomedical Inc.

Atorvastatin Reduces In Vivo Fibrin Deposition and Macrophage Accumulation, and Improves Primary Patency Duration and Maturation of Murine Arteriovenous Fistula.

Arteriovenous fistulas placed surgically for dialysis vascular access have a high primary failure rate resulting from excessive inward remodeling, medial fibrosis, and thrombosis. No clinically established pharmacologic or perisurgical therapies currently address this unmet need. Statins' induction of multiple anti-inflammatory and antithrombotic effects suggests that these drugs might reduce arteriovenous fistula failure. Yet, the in vivo physiologic and molecular effects of statins on fistula patency and maturation remain poorly understood. We randomized 108 C57Bl/6J mice to receive daily atorvastatin 1.14 mg/kg or PBS (control) starting 7 days before end-to-side carotid artery-jugular vein fistula creation and for up to 42 days after fistula creation. We then assessed longitudinally the effects of statin therapy on primary murine fistula patency and maturation. We concomitantly analyzed the in vivo arteriovenous fistula thrombogenic and inflammatory macrophage response to statin therapy, using the fibrin-targeted, near-infrared fluorescence molecular imaging agent FTP11-CyAm7 and dextranated, macrophage-avid nanoparticles CLIO-VT680. In vivo molecular-structural imaging demonstrated that atorvastatin significantly reduced fibrin deposition at day 7 and macrophage accumulation at days 7 and 14, findings supported by histopathologic and gene-expression analyses. Structurally, atorvastatin promoted favorable venous limb outward remodeling, preserved arteriovenous fistula blood flow, and prolonged primary arteriovenous fistula patency through day 42 (P<0.05 versus control for all measures). These findings provide new in vivo evidence that statins improve experimental arteriovenous fistula patency and maturation, indicating that additional clinical evaluation of statin therapy in patients on dialysis undergoing arteriovenous fistula placement is warranted.

The Relationship between the Blood Flow Volume of the Arteriovenous Fistula and its Early Effect on the Pulmonary Artery Pressure and the Left Ventricular Dimensions and Functions

Abstract Background Cardiovascular complications are leading cause of the death in hemodialysis patients. One of these complications is pulmonary hypertension which complicates chronic renal failure in 12–45% of cases and causes an increase in all-cause mortality of 2-3 folds in the dialysis population. Another complication is left ventricular hypertrophy which is a strong predictor of morbidity and mortality in patients with ESRD. Arteriovenous fistulas increase cardiac output and lead to significant increases in both the mass and the diameter of the left ventricular wall in the long-term duration. There is evidence that A-V fistula creation is a major risk factor for developing a new onset Congestive Heart Failure Aim of the Work Our study aimed to assess the relationship between blood flow volume of arteriovenous fistula (AVF) and its effect on the Pulmonary Artery Pressure (PAP) and the Left Ventricular (LV) dimensions and functions and to find out the cut off value of the AVF blood flow volume above which the cardiac dimensions and functions start to get affected. Methods and Results The study included 50 individuals selected from Internal Medicine and Nephrology outpatient clinics and inpatient wards at Ain Shams University Hospitals during the period from November 2016 until October 2018 who underwent full echocardiography studies once at the beginning of the study and once after 3 months and also underwent Duplex sonography on arteriovenous fistula to measure blood flow rate. The results showed that after 3 months the only significant changes were the ejection fraction (P-value of 0.029), the fractional shortening (P-value of 0.009), and the E/A ratio (p-value of 0.005). Also, the results showed a correlation between AVF blood flow volume and LV internal dimensions. Left ventricular end-diastolic diameter (LVEDD) and Left ventricular end-systolic diameter (LVESD) increased significantly in patients with AVF blood flow volume of 1010 ml/min or above and 1120 ml/min or above respectively. Surprisingly, PASP showed no statistically significant change in our study. Conclusion Our study concluded that high flow AVF affect cardiac dimensions and functions. We proved that a cut off value of AVF blood flow volume affecting LV dimensions and functions can be reached and in our study, a value of 1010 ml/min or above affected the LVEDD and a value of 1120 ml/min or above affected the LVESD. Surprisingly, in our study, the PASP did not show a positive correlation with AVF blood flow volume.

The effect of angioplasty of single arteriovenous fistula-associated stenosis on arteriovenous fistula blood flow rate.

Percutaneous balloon angioplasty of arteriovenous fistula-associated stenosis is performed for a variety of indications. Successful percutaneous transluminal angioplasty (PTA) is expected to increase in arteriovenous fistula blood flow rate (Qa). A validated approach to predicting changes in Qa based upon stenosis characteristics is not available. Three baseline parameters were determined in a group of patients with a single arteriovenous fistula-associated stenosis undergoing PTA. These were percent estimated stenosis, stenosis minimum luminal diameter, and baseline Qa. The relationship between these parameters and changes in Qa following PTA was analyzed using Spearman's rank correlation and linear regression. 113 patients (total group) were studied. Of these,106 had peripheral stenosis (total peripheral subgroup) and 7 had central stenosis. For the total group and total peripheral subgroup, a highly significant inverse correlation was seen between changes in Qa and baseline Qa. A weaker correlation was seen between changes in Qa and minimum luminal diameter, but no correlation was seen with percent estimated stenosis. A minimum luminal diameter ⩽2.0 mm was predictive of ⩾300-mL/min increases in Qa, whereas a minimum luminal diameter >4.5 mm was associated with <300-mL/min increases in Qa. PTA of Central vein stenosis was not associated with significant changes in Qa. Baseline Qa is the best predictor for change in Qa following PTA. Stenosis minimum luminal diameter cutoffs of ⩽2.0 and >4.5 mm are useful in predicting the magnitude of changes in Qa. Percent estimated stenosis is not predictive of change in Qa. PTA of central veins does not seem to change Qa.

P1359 Left ventricle hypertrophy and diastolic dysfunction in haemodialysis patients after surgical reduction of arteriovenous fistula blood flow

Abstract Funding Acknowledgements Grant of the Grant Agency of Charles University and grant of the Czech Health Research council Introduction Over 50% of patients treated by chronic haemodialysis programme die of cardiovascular diseases. Changes of heart structure and function can be detected by echocardiography. The most frequent changes are left ventricle hypertrophy (LVH) and its diastolic dysfunction. One of the considered contributing mechanisms is the hyperkinetic circulation. Purpose The aim of this study was to analyse the effect of high flow arteriovenous fistula (AVF) on eft ventricular hypertrophy and diastolic function. Materials and methods We included 30 patients with a high-flow arteriovenous fistula into the study, indicated for AVF blood flow reduction because of heart failure or hand ischemia. All the patients underwent echocardiographic examination and ultrasonographic measurement of AVF blood flow before and 6 weeks after the surgery. Results The AVF banding led to significant reduction of Qa (from 2977 ± 1408 to 1295 ± 610 mL/min; p ˂ 10-6, accompanied by significant decrease of cardiac index (from 4.34 ± 1.09 to 3.56 ± 0.90 L/min.m2). These findings were accompanied by significant reduction of left ventricle mass index (from 125 ± 31 to 116 ± 32 g/m2; p = 0.04) and by improvement of diastolic dysfunction grade (from 1.66 ± 0.67 to 1.14 ± 0.95; p = 0.03). The maximum velocity of tricuspid regurgitation decreased (from 3.1 ± 0.4 to 2.7 ± 0.5), and so did the left atrium volume index (from 47 ± 14 to 42 ± 15 mL/m2; p = 0.01). Conclusions LVH and diastolic dysfunction are frequent in haemodialysis patients; hyperkinetic circulation caused by high-flow arteriovenous fistula is one of the significant contributing mechanisms. Surgical reduction of AVF blood flow improved diastolic function of the left ventricle and reduced the hypertrophy in our patient population. AVF flow volume should be always considered during cardiological examination of haemodialysis patients.

The Role of Far Infrared Therapy in the Unassisted Maturation of Arterio-venous Fistula in Patients with Chronic Kidney Disease.

Introduction:The goal of arterio-venous fistula (AVF) creation is to achieve a well-functioning access that can be cannulated repetitively and can provide adequate flow for the dialysis. The objective of this study was to assess the role of far infrared (FIR) therapy in the unassisted maturation of newly created AVF in patients with chronic kidney disease (CKD).Materials and Methods:In this prospective open labeled randomised control trial, 107 patients were randomized. Participants in the control arm received oral clopidogrel 75 mg once daily for 30 days along with isometric hand exercise, whereas those in the test arm received FIR therapy twice weekly, 40 min session each, for 4 weeks. A biopsy from venous end was taken during fistula surgery. Doppler study of AVF was done at the end of the 4th and 12th week to assess AVF. Vascular access guidelines proposed by National Kidney Foundation –Kidney Disease Outcomes Quality Initiative (NKF- KDOQI) in 2006 were adapted to define the maturation of AVF.Results:Out of 107 patients, 51 were randomized to the test arm and 56 to the control arm. During follow-up, the blood flow rate through AVF (Qa) and the diameter of the cephalic vein draining (CVd) the AVF were measured. At the end of 3 months, Qa in Radio-Cephalic Fistula (RCF) was high in the test arm (p–0.003). The AVF failures were 5 (10.2%) and 14 (28%) in the test and control arms, respectively (p: 0.025). However, when adjusted for AVF failure within 6 h of surgery (may be related to surgical technique) this difference in AVF patency was statistically insignificant (p: 0.121). The mean Qa was high in patients with an arterial intimal medial thickness (AIMT) <0.5 mm. The IMT of the anastomosed artery had statistically significant correlation with the primary failure rate of AVF (P < 0.001).Conclusion:In patients with CKD, FIR therapy was effective in increasing the AVF blood flow rate at the end of 3 months, though the difference in primary failure rate was statistically insignificant.

Dynamic Banding (DYBAND) Technique for Symptomatic High-Flow Fistulae.

High flow rates may develop in arteriovenous fistula (AVF), resulting in clinical syndromes of steal, aneurysmal fistula, or high-output cardiac failure. Various techniques with varying success have been advocated to treat this difficult problem. We present a hemodynamically validated novel banding technique. We designed a computational fluid dynamic (CFD) model of the native high-flow AVF and tested various juxta-anastomotic venous diameters to determine the effect on AVF blood flow and pressure. We translated this principle in our banding technique, wherein adjustable banding was performed in conjunction with ultrasound-guided brachial artery flow measurement to determine the optimal band diameter. Polyurethane patch was used to fashion the adjustable band. Patient demographics, AVF flow parameters pre- and postintervention, operative intervention, and ultrasound follow-up data were collected prospectively. Our CFD testing demonstrated that the band diameter needed to achieve optimal distal blood pressure and preserve AVF flow depending on blood pressure, end capillary pressure, venous pressure, and vascular diameters. Five patients subsequently underwent dynamic banding of symptomatic high-flow AVF. Mean brachial artery blood flow rates pre- and postbanding were 2964 mL/min (confidence interval [CI]: 1487-4440 mL/min) and 1099 mL/min (CI: 571.7-1627 mL/min), respectively (P = .01). All patients had symptomatic improvement, and at a mean follow-up of 1 year, this benefit was sustained with no AVF thrombosis or loss. Adjustable dynamic band using ultrasound-guided brachial artery flow shows promising results in producing accurate AVF blood flow reduction with sustained efficacy in the short term for patients with symptomatic high-flow AVF.