Vascular Access Failure Research Articles

P0691LIPOPROTEIN(A) AS A POTENTIAL RISK FACTOR FOR CARDIOVASCULAR (CV) AND THROMBOTIC EVENTS IN CHRONIC KIDNEY DISEASE (CKD) AND TRANSPLANTED PATIENTS

Abstract Background and Aims Several studies suggested an independent association between elevated Lipoprotein (a) [Lp(a)] levels and the incidence of CV events in the normal population. Lp(a) levels start to rise with decreasing glomerular filtration rate. Whether high Lp(a) serum levels may contribute to the pathogenesis of atherosclerosis or thrombosis in CKD and, particularly, in transplanted (Tx) patients is largely unclear. Furthermore, it is still uncertain to which extent very high Lp(a) levels might influence CV events in this population. Aims: 1. To evaluate Lp(a) serum concentrations and lipid profile in CKD, dialysis and Tx patients. 2. To investigate the relationship between Lp(a) serum levels and atherosclerotic cardiovascular disease (ASCVD), including myocardial infarction, coronary revascularization, cerebrovascular accident, carotid endarterectomy, peripheral revascularization, gangrene, or limb amputation. 3. To assess whether Lp(a) may have a role in thrombotic events (failure of vascular access in HD or early renal allograft thrombosis after transplantation) in these patients. Method Serum Lp(a) levels and lipid profile were assessed in 295 patients (M 172, F 123; mean age 57.3, range 19-85 years): 23 with CKD stage I-III, 76 with CKD stage IV-V, 128 on dialysis (68 hemodialysis (HD), 60 peritoneal dialysis) and 68 were kidney Tx recipients (eGFR>30 ml/min). In the latter group, Lp(a) values were assayed before and after transplantation. Lp(a) levels were determined using the Macra® Lp(a) ELISA kit (Trinity Biotech, USA). Values are expressed as median and interquartile range. Logistic regression analysis was used to determine whether Lp(a) is a risk factor for CV and thrombosis disease. The cut-off value was identified according to maximum Youden index by receiver operating characteristic (ROC) curve. Results Increased mean serum levels of LDL-C (93.85 mg/d; normal values=<70 mg/dl) were observed in all groups of patients, while HDL-C and triglycerides serum levels were in the normal range. Serum Lp(a) levels (nv=14-31 mg/dl) were significantly (p<0.001) increased in advanced CKD group (stage IV-V) (45.5, 1.5-216.5 mg/dl) and, mostly, in patients on dialysis treatment (63.2, 2.0-216.6 mg/dl, p=0.001) compared to mild-moderate CKD group (stage I-III) (32, 1.3-149 mg/dl). Lp(a) serum levels correlated significantly with age (r=0.11, p<0.05) and, inversely, with eGFR only in advanced CKD group (r=-0.21 p<0.05). A significant (-56%; p<0.001) decrease of serum Lp(a) was observed after renal Tx, while staying in HD for another year resulted in an increase in serum Lp (a) levels of about 23.7% (p<0.003). No significant relationship was found between Lp(a) values and gender, inflammation (as assessed by serum C-reactive protein levels), or diabetes. By logistic regression analysis, Lp(a) values were found to be a risk factors for ASCVD in the whole population (No events 246 pts: Lp(a) 47.8 mg/dl; Yes events 49 pts: Lp(a) 53.8 mg/dl; p=0.049) and for thrombotic events in HD group (vascular access thrombosis: 4 events) and Tx patients (early acute renal vein thrombosis after Tx: 4 events) (p=0.028). The ROC curve (AUC 0.7829, 95% CI 0.5751-0.9907) allowed us to define the cut-off value for serum Lp(a) (82.45 mg/dl) (sensitivity of 87%; specificity of 73%) as a thrombotic risk factor in HD and Tx patients. Conclusion The study confirms the relevance of Lp(a) as non-traditional CV risk factor in CKD and Tx patients predicting both, the development of ASCVD and thrombosis. Serum Lp(a) levels higher than 82.45 mg/dl are potential thrombotic risk factors for vascular access failure in HD patients or early acute renal allograft thrombosis in Tx patients, suggesting more aggressive strategies to lower Lp(a) serum levels in this patient setting.

P1097INITIATING MAINTENANCE HAEMODIALYSIS USING INCREMENTAL HAEMODIALYSIS REGIME - A SINGLE CENTRE EXPERIENCE

Abstract Background and Aims Most patients with end stage renal disease (ESRD) initiate maintenance dialysis in three times per week regime irrespectively of residual kidney function (RKF). Incremental haemodialysis (IHD) showed benefits of starting and maintaining patients on less than three times per week regime, most importantly preserving urine volume output (UVO) and RKF. The aim of this study was to assess the main differences between a group of patients initiating dialysis once-weekly (1xHD) and twice-weekly (2xHD), to evaluate time to dialysis regime change, UVO and patients volume status at the end of study period. Method Patients with ESRD who started haemodialysis through the planned IHD (once-weekly and twice-weekly) and were undergoing IHD for at least 4 months (M) were enrolled (n=44) in the study. Study was conducted from January 2016 to December 2019 at dialysis department of our hospital. Patients were divided into two groups: 1xHD (20 pts) and 2xHD (24 pts). They were excluded from the study at the end of study period or earlier if they transitioned to thrice-weekly haemodialysis or died. Patients fluid status and body composition was assessed using results derived from bioimpedance measurements performed using Body Composition Monitor device. Results The 1xHD pts were younger (66,8±11,6 versus 67,4±10 years: P>0.05) and weighed less (74,4±14,7 versus 75,5±11,9 kg, p>0,05) with lower BMI. In both groups there were more males (60% versus 62,5%: P>0,05). The most common cause of ESRD in both groups was nephrosclerosis (45% in 1xHD versus 47,1% in 2xHD, p>0,05), followed by diabetic nephropathy (30% versus 20,8%, p>0,05), obstructive nephropathy (10% versus 8,3%, p>0,05), multiple myeloma (10% versus 8,3%, p>0,05), glomerulonephritis (5% versus 8,3%, p>0,05) and others in 2xHD group (12,5%; polycystic kidney disease and chronic interstitial nephritis). The estimated glomerular filtration rate of all patients at the time of HD initiation was 7,5±2,2 ml/min/1.73m2 (8,2±2,8 in 1xHD group versus 6,9±1,48 ml/ min/1.73m2 in 2xHD group, p>0,05). Baseline daily urine output was similar, 1826,6±344,6 ml/day in 1xHD and 1772,2±343,8 ml/day in 2xHD group (p>0,05). Patients in 1xHD concluded the study after mean period of 13,4 M (min 4 M, max 35 M). At the end of study period only three patients (15%) continued receiving dialysis once-weekly (mean 14,5 M, min 7 M, max 19 M), 12 pts (60%) transitioned to twice-weekly dialysis regime after 2 to 6 M (mean 3,1 M) and continued to receive this dialysis regime until the end of study period. Four pts (20%) transitioned to full-dose dialysis (mean 18,2 M, 11-24 M). Most of the patients in 2xHD group (17; 70,8%) concluded study in the same dialysis regime (mean 20,4 M, 4-24 M), 7 pts (29%) transitioned to full-dose dialysis (mean 12,6 M, 5-21 M) and one patient transitioned to once-weekly HD (8M). At the end of study daily urine output was 1463,1±317,5 in 1xHD versus 1321,1±309,1 ml/day in 2xHD group (p>0,05). Results of assessment of fluid status and body composition at the end of study are in Table 1. We evaluated nutritional status at the end of study: total protein 57,4±8,9 g/l in 1xHD versus 62,8±5,3 g/l in 2xHD, albumin 36,9±10,6 versus 37,6±4,4 g/l, total cholesterol 4,1±1,6 versus 4,4±1,3 mmol/l, triglycerides 1,3±0,8 versus 1,7±0,7 mmol/l (p>0,05 for all parameters). At the end of the study 70% of patients treated with IHD maintained renal function that was sufficient to continue IHD regime with overall survival rate 90% in 1xHD group and 87,5% in 2xHD group. Conclusion IHD, in carefully selected patients with good compliance, provides preservation of UVO and RKF, thus delaying transition to full-dose dialysis and avoiding complications of dialysis, such as intradialytic hypotension and vascular access failure. This type of dialysis is individualized treatment that obtains easier adaptation to dialysis and better quality of life.

P1361IS THE INFLAMMATORY STATE A DETERMINING FACTOR OF THE PRIMARY PERMEABILITY OF ARTERIOVENOUS FISTULES?

Abstract Background and Aims Clinical practice guidelines recommend an arteriovenous fistula (AVF) as the preferred vascular access for hemodialysis and are associated with a lower incidence of morbidity and mortality. However, primary vascular access (AV) failure is not uncommon. Low-grade inflammation is present in ERCT. We identify the inflammatory parameters that influence the primary permeability of vascular access for hemodialysis. Method Cross-sectional study; We include all the AVs performed in the HGUCR. We evaluate the initial operation after the creation of the AV. Demographic variables (age, sex), aetiology of CKD and associated comorbidity were collected. Statistical analysis with SPSS 25.0. Categorical variables are expressed as percentages and are compared using the Chi2 Test. Quantitative variables are expressed as mean ± standard deviation and the t-student was used to compare them. We performed a multivariate analysis to determine those factors involved in the primary failure of the VA. Statistical significance for a value of p <0.05. Results 600 VA performed on 466 patients were reviewed between October 2009 and December 2019. 492 autologous VA (86.8%) and 75 prosthetic VA (13.2%) were performed. The mean age of the patients was 65.3 ± 14.2 years and 66.2% were male. The most frequent etiology of CKD was diabetic nephropathy (29.9%), followed by non-affiliated (18%) and glomerulonephritis (16.5%). 90.8% of the patients had arterial hypertension (HT), diabetes mellitus (DM) 48%. 77.2% of AV presented primary permeability. In the univariate analysis using Chi2 and T student, statistical age (p = 0.017), HT (p = 0.002), statin treatment (p = 0.002), antiplatelet therapy (p = 0.001), low ferritin levels (p = 0.011) and PCR (p = 0.019). When performing a multivariate analysis, the high CRP figures (OR: 0.64 95% CI 0.42-0.98 p = 0.043) and ferritinemia (OR: 1.04 95% CI 1.01-1.06 p = 0.013) are predictive factors of primary AV failure. Conclusion In our study, high CRP decreases the probability of primary functioning of AVFs by 36% and elevated ferritin levels are predictors of primary failure after adjusting for age and sex in the multivariate model.

P1207ANALYSIS OF OUTCOME AND FACTORS ASSOCIATED WITH MAINTENANCE OF PERITONEAL DIALYSIS

Abstract Background and Aims Peritoneal dialysis (PD) is generally associated with a good survival rate and with great preservation of residual renal function (RRF). The various causes of technique failure are responsible for the relative short time staying in PD. Objectives: This study aimed to analyze the outcome and factors correlated with maintenance peritoneal dialysis (PD) to guide for improving prognosis. Method In a retrospective way we examined our PD-cohort concerning mortality, technique survival, peritonitis rate, and other complications. Results From 2005 to 2019 the number of PD patients who have been treated in PD program for more than 3 months was around 199 patient, 29.1% diabetics, mean age 53.3±15.03 years old and meantime in therapy 32.39± 27.34 months. The PD was seen as an alternative for younger patients in the transplant list and elderly patients with comorbidity. Around 7.5% of the PD patients were transplanted and 8.5 % of patients were transferred from HD due to vascular access failure. Around 88.9% of patients were on PD for more than 1 year, 37.7% from 3 up to 5 years and 19.8% percent of the patients have stayed on PD for more than 5 years. Cardiovascular mortality was the main cause of mortality with 53% of the cases. Higher comorbidity index, lower albumin levels, and lower residual renal function were the main risk factors for lower survival. The technical survival of patients was 92.3% during the first year, 79.5% and 69.6% in the second and the fifth year, respectively. There was not found a difference in technical survival between diabetics and nondiabetics patients. Ultrafiltration failure followed by peritonitis was the main reason for transfer patients with more than 24 months in therapy in hemodialysis probably linked with the no availability of icodextrin. Peritonitis rate was 1:41 patient months. Conclusion PD program in our center is organized based in the concept of integrated care in RRT. The outcome of our patients was at least comparable to those reported by larger registries Although we have done good progress in the prevention of infection the nonavailability of icodextrin is an important factor for a technical failure. RRF is an important factor and we need to be more focused to maintain it longer in the future.

Predicting arterio-venous fistula failure by urea-method derived access blood flow in chronic hemodialysis patients.

Dialysis access is an essential part of hemodialysis. Determining the access blood flow (Qa) can help predict arterio-venous fistula thrombosis. Qa determination by the urea method, which was previously described in the past is simple and is available in most of the dialysis units but was not be able to predict arterio-venous fistula thrombosis. To compare the efficacy of Qa determination by the urea method and by ultrasound dilution methods in predicting arterio-venous fistula failure. Qa was measured by urea method and by ultrasound dilution simultaneously, every 3 months for a period of 1 year, in stable chronic hemodialysis patients with arterio-venous fistula. Arterio-venous fistula failure determined by clinical parameters and confirmed by Doppler ultrasound before sending the patient for interventional angioplasty. This study enrolled a total of 16 patients, with 63% being male, 75% with lower-arm arterio-venous fistula and around 43% with previously done angioplasty. 59-Qa measurements were done, and 6 patients underwent angioplasty (one patient for severe upper limb edema, one for access thrombosis, and four for access dysfunction). Qa determination by the urea method had non-significantly lower Qa, (745 mL/min (interquartile range: 509-1143) and 779 mL/min (interquartile range: 530-1160), (p = 0.58)) and high correlation (r = 0.83, p < 0.001) to Qa by ultrasound dilution. The cut-off criteria with its sensitivity and specificity in predicting the access failure were 440 mL/min, 66.67%, and 96.15% for Qa determination by the urea and 400 mL/min, 66.67% and 90.38% for Qa by ultrasound dilution, respectively, with no difference in the area under the receiver operating characteristic curve. Measurement of Qa determination by the urea method is well correlated with Qa by ultrasound dilution and can be used to predict vascular access failure.

Stima della portata della fistola artero-venosa mediante termodiluizione nei pazienti in emodialisi cronica: esperienza monocentrica.

Purpose: Vascular access surveillance in hemodialysis is today an important challenge for nephrologist. Low blood flow is a risk factor for development of thrombosis of native fistula or graft.&#x0D; The aim of the study is to evaluate the correspondence between flow measurement by thermodilution and Color Doppler, and to identify flow rate values using the Blood temperature monitor (BTM) method in the case of stenosis.&#x0D; Methods: We evaluated 29 patients on chronic hemodialysis. The evaluation of blood flow with BTM were performed during the first hour of the hemodialysis session. All patients underwent a color doppler of vascular access within 10 days from the BTM measurements.&#x0D; Results: The mean vascular access flow calculated with BTM resulted 1142 ± 700 ml/min and there was a correlation with color doppler data 1199 ± 644 ml/min (p=0,0001 r=0,829). The flow of patients with hemodynamically significant stenosis was 332 ± 92 ml/min with a minimum value of 270 ml/min and a maximum value of 440 ml/min.&#x0D; Conclusion: the correspondence between thermodilution and color doppler support the implementation of intradialitic evaluation of the vascular access blood flow with the BTM method. Thermodilution allows to identify earlier patients with high risk of vascular access failure and the need for further diagnostic and therapeutic investigations.

Vascular Access Failure - Cause or Complication of Central Venous Catheterization: Case Report

Abstract The quality of life and patient survival rate in terminal chronic renal insufficiency depends on the duration of vascular approaches. Dialysis catheters are used to establish an adequate vascular approach when emergency hemodialysis is indicated and when all approaches are exhausted. Complications of CVC can be classified into three categories: mechanical (hematoma, arterial puncture, pneumothorax, hemothorax, catheter misplacement, and stenosis), infectious (insertion site infection, CVC colonization, and bloodstream infection) and thrombotic (deep vein thrombosis). Despite the increasing prevalence of haemodialysis patients with complex access issues, there remains no consensus on the definition of vascular access failure or end-stage vascular access. The dilema in these cases remains whether the generalized vascular insufficiency is the cause or a complication of exhausted vascular accesses. This case report is one of the examples of combined complications with generalized vascular access insufficiency. During the year and a half of the chronic dialysis program, the patient had several changes of vascular approaches, and each approach became dysfunctional in certain time due to various causes. After six months of successful hemodialysis, the patient was admitted with signs of infection and during hospitalization was again subjected to multiple changes of the vascular approach due to infection, thrombosis, and vascular access failure.

SAT-292 Success of Instant-Start Life-Saving Peritoneal Dialysis in Patients with End stage Vascular Access Failure

Hemodialysis is the most common dialysis modality worldwide. Good functioning Vascular Access (VA) is the Achilles heel for efficient and successful hemodialysis [1,2]. Up to 30% of admissions in hemodialysis population is related to vascular access dysfunction, leading to increase in morbidity and mortality [3]. Vascular access dysfunction constitutes quarter of total of End Stage Renal Disease (ESRD) expenditure in the United States [4]. About 80% of incident ESRD patients started urgent hemodialysis through Central Venous Catheter (CVC) [5]. The high morbidity and mortality rates in patients with CVC may be related to catheter infection, catheter related septicemia, frequent admissions, inadequate dialysis related to insufficient blood flow and frequent interruption of dialysis due to venous stenosis or thrombosis [6-8]. Almasri J, et al. conducted a recent systematic review and meta-analysis of 200 studies. Of 875,269 vascular accesses, the primary patency at two years was higher for fistulas than for graft and catheters (55%, 50% and 40% respectively). The risk factors for lower patency rates were old age, female gender, diabetes and coronary artery disease. This study aimed at evaluation of the feasibility of instant-start, life-saving peritoneal dialysis in dialysis patients with End Vascular Access Failure (ESVAF) in addition to complications and outcome of this dialysis modality. This is a prospective observational study from June 2015 throughout July 2018. Urgent two-cuff curled Tenckhoff PD catheters were inserted percutaneously within few hours by expert nephrology team. Twenty-three dialysis ESVAF patients who presented acutely to our hospital were included in the study. Dialysis was initiated within 2 hours (range: 1-3 h) from presentation in all patients. Adequate metabolic and volume control was achieved after 4 sessions of PD. Mechanical complications occurred in 25.1%. The main mechanical complications were minor peri-catheter leakage (13%) and catheter tip migration (8.7%). One patient had omental wrap which necessitated catheter replacement. ESI occurred in 13%, tunnel infection in 0% and peritonitis in 13% of patients. Peritonitis rate was 0.142 episode/patient-year. After 6 months, catheter and patient survival rates were 87.0% and 91.3% respectively. The instant-start PD modality was a life-saving, feasible and safe alternative to hemodialysis in patients with ESVAF.

An unusual complication of CAPD technique: Lesson to be learnt

Continuous Ambulatory Peritoneal Dialysis is a recommended mode of renal replacement therapy in those with vascular access failures. Complications of Surgical placement of catheter and Percutaneous technique by Nephrologist are well described. Complications may occur during the procedure or after the procedure. During the placement of the catheter, hollow viscus perforation is known to occur. Patients are given instructions of using laxative , emptying bladder before surgery in order to avoid bladder or bowel injury. Bladder perforation is one of the rare complication of CAPD technique.It is expected to occur commonly with rigid catheters than the soft catheters used in CAPD. Herein we report a case of bladder perforation during the procedure of placement of percutaneous CAPD catheterization.

Complications of permanent vascular access in hemodialysis patients

Background Vascular access (VA) complications are still considered a significant cause of morbidity and mortality in hemodialysis (HD) patients. The research aimed to study the complications of permanent VA in HD patients: single-center experience. Patients and methods This was a 1-year prospective, observational study conducted in a HD Unit, Department of Nephrology in 2018. 230 HD patients were recruited for the study, and they were subjected to clinical examination in each HD session. Culture and sensitivity of a swab sample of the VA was performed to confirm the diagnosis of infection. Also, Doppler ultrasound was used to evaluate the VA when there had been a suspicion of complications. Data were analyzed using the software Statistical Package for The Social Sciences. Results Arteriovenous fistula (AVF) was the predominant VA, and radiocephalic AVF was the most common type, followed by the brachiocephalic type. The most frequent complication was aneurysm (39.6%), followed by thrombosis (7%), stenosis (5.2%), infection (4.3%), and arterial steal syndrome (2.2%). Thrombosis was the leading cause of AVF failure, and antiplatelet therapy was a protective factor from thrombosis. Infection was the second cause of VA failure and Staphylococcus aureus infection was the most common type. Elbow AVF was considered as a predisposing risk factor of arterial steal syndrome. Conclusion VA complications are not rare, and they could cause VA failure. So, it is necessary to make more efforts and work as a multidisciplinary team.

Effect of sex differences in treatment response to angioplasty in a murine arteriovenous fistula model.

Failure to mature and venous neointimal hyperplasia formation are the two major causes of hemodialysis arteriovenous fistula (AVF) vascular access failure. Percutaneous transluminal angioplasty (PTA) is the firstline treatment for both of these conditions, but, clinically, women have decreased patency rates compared with men. The hypothesis to be tested in the present study was that female mice after PTA of venous areas of higher intimal thickening have increased gene expression of transforming growth factor-β1 (TGF-β1) and TGF-β receptor 1 (TGFβ-R1) accompanied with histological changes of fibrosis compared with male mice. Seventeen male and eighteen female C57BL/6J mice were used in this study. Chronic kidney disease was induced by partial nephrectomy, and, 28 days later, an AVF was created to connect the left carotid artery to the right jugular vein. Two weeks later, the higher intimal thickening area was treated with PTA, and mice were euthanized 3 days later for gene expression analysis or 14 days later for histopathological analysis. Doppler ultrasound was performed weekly after AVF creation. At day 3, female AVF had significantly higher average gene expression of TGF-β1 and TGFβ-R1 compared with male AVF. At day 14, female outflow veins had a smaller venous diameter, lumen vessel area, decreased wall shear stress, lower average peak systolic velocity, and an increased neointima area-to-media area ratio. Moreover, female outflow veins showed a significant increase in α-smooth muscle actin and fibroblast-specific protein-1. There was a decrease in M1/M2 with an increase in CD68.

Reduced patency in left-sided arteriovenous grafts in a porcine model

ObjectiveThe porcine arteriovenous graft model is commonly used to study hemodialysis vascular access failure, with most studies using a bilateral, paired-site approach in either the neck or femoral vessels. In humans, left- and right-sided central veins have different anatomy and diameters, and left-sided central vein catheters have worse outcomes. We assessed the effect of laterality on arteriovenous prosthetic graft patency and hypothesized that left-sided carotid-jugular arteriovenous prosthetic grafts have reduced patency in the porcine model. MethodsArteriovenous polytetrafluoroethylene grafts were placed ipsilaterally or bilaterally in 10 Yorkshire male pigs from the common carotid artery to the internal jugular vein. Ultrasound measurements of blood flow velocities and diameters were assessed before graft placement. Animals were sacrificed at 1 week, 2 weeks, or 3 weeks. Patency was determined clinically; grafts and perianastomotic vessels were excised and analyzed with histology and immunostaining. ResultsAt baseline, left- and right-sided veins and arteries had similar blood flow velocities. Although internal jugular veins had similar diameters at baseline, left-sided carotid arteries had 11% smaller outer diameters (P = .0354). There were 10 left-sided and 8 right-sided polytetrafluoroethylene grafts placed; only 4 of 10 (40%) grafts were patent on the left compared with 7 of 8 (88%) grafts patent on the right (P = .04). Left-sided grafts had increased macrophages at the arterial anastomosis (P = .0007). Left-sided perianastomotic arteries had thicker walls (0.74 vs 0.60 mm; P = .0211) with increased intima-media area (1.14 vs 0.77 mm2; P = .0169) as well as a trend toward 38% smaller luminal diameter (1.6 vs 2.5 mm; P = .0668) and 20% smaller outer diameter (3.0 vs 3.7 mm; P = .0861). Left- and right-sided perianastomotic veins were similar histologically, but left-sided veins had decreased expression of phosphorylated endothelial nitric oxide synthase (P = .0032) and increased numbers of α-actin-positive smooth muscle cells (P = .0022). ConclusionsLeft-sided arteriovenous grafts are associated with reduced short-term patency compared with right-sided grafts in the Yorkshire pig preclinical model of arteriovenous prosthetic grafts. Laterality must be considered in planning and interpreting surgical preclinical models.

Open and endovascular surgery for stenosis of the peripheral regions of arteriovenous fistula

Vascular access is the cornerstone of hemodialysis. With vascular access dysfunction, the results of treatment of patients with stage 5 chronic kidney disease significantly deteriorate. One of the most common causes of vascular access failure is peripheral venous stenosis. Despite the variety of initiating factors, the morphological substrate of stenotic damage to the arteriovenous fistula (or arteriovenous anastomosis) in most cases is neointimal hyperplasia. Stenotic lesions of the arterivenous fistula are strongly associated with an increased risk of thrombosis and loss of vascular access. There are 4 typical localizations of stenosis: arteriovenous or arteriograft anastomosis, stenosis of the juxta-anastomotic segment of the fistula, stenosis of the functional segment of the fistula, and stenosis of the cephalic arc.The most common indication for surgical treatment is vascular access failure; less common indications are clinical symptoms of venous insufficiency.There are various methods of open reconstruction of the stenotic segment of the fistula vein: resection, prosthetics with a synthetic vascular graft, prosthetics or plastic repair of the autologous vein wall, complete or partial drainage of the prestenotic segment of the vein, etc. Currently an alternative method of stenosis repair using endovascular interventions is gaining popularity. In contrast to central vein stenosis, where endovascular interventions are the gold standard, in peripheral vein stenosis it is only an adjuvant method. Complications of endovascular interventions are extremely rare.Despite the fact that endovascular interventions have almost absolute probability of technical success, the primary patency is not high and is about 50% in six months. The use of bare stents is not accompanied by an increase in primary patency. The use of stent-grafts can increase the primary patency, especially in the plastic repair of challenging stenoses of the graft-vein anastomosis or cephalic arch.Many issues related to endovascular interventions remain unresolved, which requires further research.

Higher Surgeon Procedure Volume is Associated with Improved Hemodialysis Vascular Access Outcomes

The objective of this study was to examine the association between surgeon characteristics, procedural volume, and short-term outcomes of hemodialysis vascular access. A retrospective cohort study was performed using Medicare Part A and B data from 2007 through 2014 merged with American Medical Association Physician Masterfile surgeon data. A total of 29,034 procedures met the inclusion criteria: 22,541 (78%) arteriovenous fistula (AVF) and 6,493 (22%) arteriovenous graft (AVG). Of these, 13,110 (45.2%) were performed by vascular surgeons, 9,398 (32.3%) by general surgeons, 2,313 (8%) by thoracic surgeons, 1,517 (5.2%) by other specialties, and 2,696 (9.3%) were unknown. Every 10-year increase in years in practice was associated with a 6.9 per cent decrease in the odds of creating AVF versus AVG (P = 0.02). Surgeon characteristics were not associated with the likelihood of vascular access failure. Every 10-procedure increase in cumulative procedure volume was associated with a 5 per cent decrease in the odds of vascular access failure (P = 0.007). There was no association of provider characteristics or procedure volume with survival free of repeat AVF/AVG or TC placement at 12 months. A significant portion of the variability in likelihood of creating AVF versus AVG is attributable to the provider-level variation. Increase in procedure volume is associated with decreased odds of vascular access failure.

Evaluation of hemodynamic impact of absorbable sutures in native arteriovenous fistulas: A retrospective study.

One of the major causes of arteriovenous fistula failure is the venous stenosis due to aggressive neointimal hyperplasia. The aim of the study was to assess the arteriovenous fistula maturation comparing absorbable sutures and non-absorbable ones in native vessels. Surgeries performed during a period of 24 months by a single team of expert surgeons were evaluated. Surgeries that met the inclusion criteria, namely, age ⩾ 18 years and radio-cephalic arteriovenous fistula, were considered. According to type of suture, patients were classified as Max group (absorbable suture) and Prol group (non-absorbable). Data pertaining to 70 patients were collected; 51% were men and the mean age was 73 ± 12 years. In Max group, an increasing blood flow was observed during the first 4 weeks without post-operative complications. In Prol group, six patients had thrombosis that resulted in vascular access failure. After the first week, the duplex Doppler ultrasound of both groups showed a regular arteriovenous fistula maturation, with an increase of blood flow rate. Although pre-operative post-tourniquet mean vein diameters of Max group were not adequate, the mean vein diameter and mean blood flow rate increased after 4 weeks, respectively. On the contrary, in Prol group, mean vein diameters and blood flow rate decreased. The maturation of arteriovenous fistula and its functional performance were not altered by the type of suture (absorbable/non-absorbable). Absorbable sutures were associated with good results considering arteriovenous fistula maturation.

The Role of MicroRNA-21 in Venous Neointimal Hyperplasia: Implications for Targeting miR-21 for VNH Treatment.

The molecular mechanism of hemodialysis access arteriovenous fistula (AVF) failure due to venous neointimal hyperplasia (VNH) is not known. The role of microRNA-21 (miR-21) in VNH associated with AVF failure was investigated by performing in vivo and in vitro experiments. In situ hybridization results revealed that miR-21 expression increased and was associated with fibroblasts in failed AVFs from patients. In a murine AVF model, qRT-PCR gene expression results showed a significant increase in miR-21 and a decrease in miR-21 target genes in graft veins (GVs) compared to contralateral veins in mouse AVF. miR-21 knockdown in GVs was performed using a lentivirus-mediated small hairpin RNA (shRNA), and this improved AVF patency with a decrease in neointima compared to control GVs. Moreover, loss of miR-21 in GVs significantly decreased the Tgfβ1, Col-Ia, and Col-Iva genes. Immunohistochemistry demonstrated a significant decrease in myofibroblasts and proliferation with an increase in terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining in miR-21-knockdown vessels, along with a decrease in hypoxia-inducible factor-1 alpha (HIF-1α) and phospho-SMAD2 (pSMAD-2) and phospho-SMAD3 (pSMAD-3) and an increase in phosphatase and tensin homolog (PTEN) staining. Hypoxic fibroblast knockdown for miR-21 showed a significant decrease in Tgfβ-1 expression and pSMAD-2 and -3 levels and a decrease in myofibroblasts. These results indicate that miR-21 upregulation causes VNH formation by fibroblast-to-myofibroblast differentiation.

FP671Zinc Deficiency may Implicate Vascular Access Failure after Vascular Access Intervention in Haemodialysis Patients

FP671Zinc Deficiency may Implicate Vascular Access Failure after Vascular Access Intervention in Haemodialysis Patients

Comparison of the efficacy of using paclitaxel-eluting balloon and plain balloon angioplasty for arteriovenous fistula in hemodialysis patients

Introduction: Arteriovanous (AV) access failure is one of the main problems in patients with end stage renal disease (ESRD), who receive hemodialysis. Balloon angioplasty is a favorable method for managing vascular access failure. The purpose of this study was to compare the six-month efficacy of paclitaxel-eluting balloon and plain balloon angioplasty in failed AV access cases among hemodialysis patients.&#x0D; Methods: In this quasi-experimental study (http://en.irct.ir/trial/35333), 50 hemodialysis patients with failure of AV access (stenosis &gt; 50%), who were candidates for angioplasty, were included. They were divided to receive either paclitaxel-eluting balloon (25 patients) or plain balloon (25 patients) angioplasty. Patients were followed up for six months with color Doppler ultrasonography and clinical examination for the hemodynamic success rate of angioplasty.&#x0D; Results: After six months, 19 patients (76%) in paclitaxel-eluting balloon angioplasty group achieved hemodynamic success, which was significantly higher than plain balloon angioplasty group (13 patients, 52%) (P = 0.012). Age, gender, diabetes mellitus, hypertension, and location of AVF (snuff box, forearm, and antecubital fossa) did not associate with hemodynamic success rate in any group.&#x0D; Conclusion: The use of angioplasty with paclitaxel-eluting balloon was superior to plain balloon angioplasty for failed AV access cases in hemodialysis patients. It is recommended to use paclitaxeleluting balloon angioplasty in patients with failure of AV access and requirement for balloon angioplasty.&#x0D;

Factors affecting arteriovenous fistula dysfunction: A narrative review.

Vascular access dysfunction is one of the most important causes of morbidity and mortality in haemodialysis patients, contributing to up to one third of hospitalisations and accounting for a significant amount of the health care costs of these patients. In the past decades, significant scientific advances in understanding mechanisms of arteriovenous fistula maturation and failure have contributed to an increase in the amount of research into techniques for creation and strategies for arteriovenous fistula dysfunction prevention and treatment, in order to improve patient care and outcomes. The aim of this review is to describe the pathogenesis of vascular access failure and provide a comprehensive analysis of the associated risk factors and causes of vascular access failure, in order to interpret possible future therapeutic approaches. Arteriovenous fistula failure is a multifactorial process resulting from the combination of upstream and downstream events with consequent venous neo-intimal hyperplasia and/or inadequate outward remodelling. Inflammation appears to be central in the biology of arteriovenous fistula dysfunction but important triggers still need to be revealed. Given the significant association of arteriovenous fistula failure and patient's prognosis, it is therefore imperative to further research in this area in order to improve prevention, surveillance and treatment, and ultimately patient care and outcomes.

The Effect of Aspirin on Preventing Vascular Access Dysfunction in Incident Hemodialysis Patients: A Prospective Cohort Study in Korean Clinical Research Centers for End-Stage Renal Disease (CRC for ESRD).

Background: Aspirin is often prescribed empirically to improve the patency of hemodialysis (HD) vascular access. Therefore, this study aimed to investigate the impact of aspirin on the survival of vascular access in incident HD patients with arteriovenous fistula (AVF) or arteriovenous graft (AVG). Methods: A prospective cohort of 881 incident HD patients was enrolled between 2009 and 2014. The primary outcome was defined as the first AVF/AVG intervention or salvage procedure, including percutaneous transluminal angioplasty or surgery for vascular access failure. Cox analyses were performed to determine the association between aspirin usage and the occurrence of the primary outcome. Results: The mean age of the patient group was 57.9 ± 13.4, and 63.8% of the patients were male. Aspirin was prescribed in 241 (27.4%) patients, and the median follow-up duration was 30 months. During follow-up, 180 (20.4%) patients experienced the primary outcome event. Univariate analysis showed that age, gender, presence of diabetes mellitus (DM), preexisting peripheral arterial disease, and the type of vascular access used (AVG versus AVF) were significantly associated with the development of the primary outcome. However, aspirin usage from the baseline was not significantly associated with primary outcome events (hazard ratio (HR): 1.16; 95% confidence interval (CI): 0.84–1.60; p = 0.378). Multivariate analysis showed that gender, the presence of DM, and the type of vascular access were still significantly associated with the occurrence of the primary outcome. Moreover, we did not observe the protective effect of taking aspirin on primary vascular access failure, even in subgroup analyses stratified according to gender, the presence of DM, and the type of vascular access. Conclusion: Physicians should carefully consider when they prescribe aspirin for the prevention of primary vascular access failure in Korean incident HD patients. In addition, larger prospective interventional studies are needed to elucidate the effect of aspirin on vascular access failure.