High fidelity blood flow in a patient-specific arteriovenous fistula.

An arteriovenous fistula, created by artificially connecting segments of a patient's vasculature, is the preferred way to gain access to the bloodstream for kidney dialysis. The increasing power and availability of supercomputing infrastructure means that it is becoming more realistic to use simulations to help identify the best type and location of a fistula for a specific patient. We describe a 3D fistula model that uses the lattice Boltzmann method to simultaneously resolve blood flow in patient-specific arteries and veins. The simulations conducted here, comprising vasculatures of the whole forearm, demonstrate qualified validation against clinical data. Ongoing research to further encompass complex biophysics on realistic time scales will permit the use of human-scale physiological models for basic and clinical medicine.

Association of Retinol-Binding Protein 4 with Arteriovenous Fistula Dysfunction in Hemodialysis Patients.

BACKGROUND: Arteriovenous fistula (AVF) is the most common vascular access for patients undergoing hemodialysis (HD). Neointimal hyperplasia (NIH) might be a potential mechanism of AVF dysfunction. Retinol-binding protein 4 (RBP4) may play an important role in the pathogenesis of NIH. The aim of this study was to investigate whether AVF dysfunction is associated with serum concentrations of RBP4 in HD subjects. METHODS: A cohort of 65 Chinese patients undergoing maintenance HD was recruited between November 2017 and June 2019. The serum concentrations of RBP4 of each patient were measured with the ELISA method. Multivariate logistic regression was used to analyze data on demographics, biochemical parameters, and serum RBP4 level to predict AVF dysfunction events. The cutoff for serum RBP4 level was derived from the highest score obtained on the Youden index. Survival data were analyzed with the Cox proportional hazards regression analysis and Kaplan-Meier method. RESULTS: Higher serum RBP4 level was observed in patients with AVF dysfunction compared to those without AVF dysfunction events (174.3 vs. 168.4 mg/L, p = 0.001). The prevalence of AVF dysfunction events was greatly higher among the high RBP4 group (37.5 vs. 4.88%, p = 0.001). In univariate analysis, serum RBP4 level was statistically significantly associated with the risk of AVF dysfunction (OR = 1.015, 95% CI 1.002-1.030, p = 0.030). In multivariate analysis, each 1.0 mg/L increase in RBP4 level was associated with a 1.023-fold-increased risk of AVF dysfunction (95% CI for OR: 1.002-1.045; p = 0.032). The Kaplan-Meier survival analysis indicated that the incidence of AVF dysfunction events in the high RBP4 group was significantly higher than that in the low-RBP4 group (p = 0.0007). Multivariate Cox regressions demonstrated that RBP4 was an independent risk factor for AVF dysfunction events in HD patients (HR = 1.015, 95% CI 1.001-1.028, p = 0.033). CONCLUSIONS: HD patients with higher serum RBP4 concentrations had a relevant higher incidence of arteriovenous dysfunction events. Serum RBP4 level was an independent risk factor for AVF dysfunction events in HD patients.

Secondary S100B Protein Increase Following Brain Arteriovenous Malformation Rupture is Associated with Cerebral Infarction.

Early S100B protein serum elevation is associated with poor prognosis in patients with ruptured brain arteriovenous malformations (BAVM). The purpose of this study is to determine whether a secondary elevation of S100B is associated with early complications or poor outcome in this population. This is a retrospective study of patients admitted for BAVM rupture. A secondary increase of S100B was defined as an absolute increase by 0.1 µg/L within 30 days of admission. Fisher's and unpaired t tests followed by multivariate analysis were performed to identify markers associated with this increase. Two hundred and twenty-one ruptures met inclusion criteria. Secondary S100B protein serum elevation was found in 17.1% of ruptures and was associated with secondary infarction (p < 0.001), vasospasm-related infarction (p < 0.001), intensive care (p = 0.009), and hospital length of stay (p = 0.005), but not with early rebleeding (p = 0.07) or in-hospital mortality (p = 0.99). Secondary infarction was the only independent predictor of secondary increase of S100B (OR 9.9; 95% CI (3-35); p < 0.001). Secondary elevation of S100B protein serum levels is associated with secondary infarction in ruptured brain arteriovenous malformations.

Angiopoietin-2 predicts morbidity in adults with Fontan physiology.

Morbidity in patients with single-ventricle Fontan circulation is common and includes arrhythmias, edema, and pulmonary arteriovenous malformations (PAVM) among others. We sought to identify biomarkers that may predict such complications. Twenty-five patients with Fontan physiology and 12 control patients with atrial septal defects (ASD) that underwent cardiac catheterization were included. Plasma was collected from the hepatic vein and superior vena cava and underwent protein profiling for a panel of 20 analytes involved in angiogenesis and endothelial dysfunction. Ten (40%) of Fontan patients had evidence of PAVM, eighteen (72%) had a history of arrhythmia, and five (20%) were actively in arrhythmia or had a recent arrhythmia. Angiopoietin-2 (Ang-2) was higher in Fontan patients (8,875.4 ± 3,336.9 pg/mL) versus the ASD group (1,663.6 ± 587.3 pg/mL, p < 0.0001). Ang-2 was higher in Fontan patients with active or recent arrhythmia (11,396.0 ± 3,457.7 vs 8,118.2 ± 2,795.1 pg/mL, p < 0.05). A threshold of 8,500 pg/mL gives Ang-2 a negative predictive value of 100% and positive predictive value of 42% in diagnosing recent arrhythmia. Ang-2 is elevated among adults with Fontan physiology. Ang-2 level is associated with active or recent arrhythmia, but was not found to be associated with PAVM.

S100B Serum Elevation Predicts In-Hospital Mortality After Brain Arteriovenous Malformation Rupture.

Background and Purpose- S100B protein serum elevation has been associated with poor prognosis in neurologically ill patients. The purpose of this study is to determine whether elevation of S100B is associated with increased in-hospital mortality after brain arteriovenous malformation rupture. Methods- This is a retrospective study of patients admitted for brain arteriovenous malformation rupture. The study population was divided into derivation and validation cohorts. Univariate followed by multivariate logistic regression was used to determine whether elevation of S100B serum levels above 0.5 µg/L during the first 48 hours after admission (S100Bmax48) was associated with in-hospital mortality. Results- Two hundred and three ruptures met inclusion criteria. Twenty-three led to in-hospital mortality (11%). Mean S100Bmax48 was 0.49±0.62 µg/L. In the derivation cohort (n=101 ruptures), multivariate analysis found Glasgow coma scale score ≤8 (odds ratio, 21; 95% CI, 2-216; 0.001) and an S100Bmax48>0.5 µg/L (odds ratio, 19; 95% CI, 2-188; P=0.001) to be associated with in-hospital mortality. When applied to the validation cohort (n=102 ruptures), the same model found only S100Bmax48>0.5 µg/L (odds ratio, 8; 95% CI, 1.5-44; P=0.01) to be associated with in-hospital mortality. Conclusions- Elevated S100B protein serum level is strongly associated with in-hospital mortality after brain arteriovenous malformation rupture.

Modulation of micro-rheological and hematological parameters in the presence of artificial carotid-jugular fistula in rats.

BACKGROUND: Arteriovenous fistula (AVF) may affect erythrocytes through many pathways (e.g., mechanical, inflammatory). However, these effects haven't been elucidated completely yet. OBJECTIVE: To follow-up the hemorheological and the hematological changes in the presence of artificial carotid-jugular fistula in rats. METHODS: Female Wistar rats were subjected to sham-operated group (SG, n = 6) and to fistula group (FG, n = 10). Under general anesthesia, the right carotid artery and jugular vein were isolated via a neck incision, and in the FG carotid-jugular fistula was performed by microsurgical techniques. Hematological variables, red blood cell (RBC) deformability and membrane (mechanical) stability parameters were determined before operation and on the 1st and 6th postoperative weeks. Density separated samples ('young' and 'old' RBCs) were also tested. RESULTS: In FG group hematocrit, RBC and platelet counts increased gradually to reach highly significant level of increment on the 6th postoperative week. RBC deformability significantly was impaired. The membrane stability test showed lower deformability values after applying mechanical shearing. No significant differences were observed between density separated RBC subpopulations. CONCLUSIONS: The presence of arteriovenous fistula may lead to an increment of RBC mass and impairment of RBC deformability. These changes could be one of the pathways through which the fistula influences the microcirculation.

Assessing changes in tissue oxygenation by near-infrared spectroscopy following brachial plexus block for arteriovenous fistula surgery: A prospective observational pilot study.

BACKGROUND: Near-infrared spectroscopy (NIRS) can be used to measure tissue oxygen saturation (StO2) in different sites and in a wide range of clinical scenarios. Peripheral regional anaesthesia induces vascular changes causing increased arterial blood flow and venodilatation, but its effect on StO2 is still under debate. This is especially so for patients undergoing arteriovenous fistula surgery, wherein latest data suggest an improved outcome under brachial plexus block (BPB) compared with local anaesthesia, but no data are available. OBJECTIVE: The aim of this study was to investigate changes in StO2 following BPB prior to arteriovenous fistula surgery using NIRS. DESIGN: A prospective observational study. SETTING: A secondary teaching hospital from August 2016 to March 2017. PATIENTS: Fifteen patients undergoing arteriovenous fistula surgery. INTERVENTION: Ultrasound-guided BPB in 15 patients undergoing arteriovenous fistula surgery. OUTCOME MEASURES: StO2 at baseline and compared with baseline and the contralateral arm following BPB measured using NIRS of the thenar eminence (NIRSth). RESULTS: Baseline values of StO2 assessed by NIRSth were 42.6 ±â€Š7.7% in the arteriovenous fistula arm and 42.7 ±â€Š9.7% in the contralateral arm. There was no significant difference between the two. Five minutes after BPB, there was a significant increase in StO2 of the blocked arm, compared with the control arm expressed as difference of absolute values (7.1 ±â€Š9.7%). At 60 min, an absolute difference of 21.0 ±â€Š13.5% was reached. The absolute increase in StO2 of the blocked arm compared with baseline reached significance after 5 min (8.8 ±â€Š4.6%) and increased up to 23.2 ±â€Š8.2% after 60 min. CONCLUSION: NIRSth indicates that BPB significantly increases StO2 of the arteriovenous fistula arm in patients undergoing haemodialysis. TRIAL REGISTRATION: Clinicaltrials.gov: NCT03044496.

Deep Sequencing of Small RNAs in Blood of Patients with Brain Arteriovenous Malformations.

BACKGROUND: Deregulation of circulating microRNAs (miRNAs) is always associated with development and progression of human diseases. We aimed to assess whether patients with brain arteriovenous malformations (BAVMs) possess a distinct miRNA signature compared with healthy subjects. METHODS: Three patients with unruptured BAVMs and 3 normal control subjects were recruited as case and control groups. Peripheral blood was collected, and miRNA signature was obtained by next-generation sequencing, followed by comparative, functional, and network analyses. Quantitative reverse transcription polymerase chain reaction was performed to validate expression of specific miRNAs. RESULTS: Deep sequencing detected 246 differentially expressed miRNAs in blood samples of patients with BAVMs compared with normal control subjects. For the top 5 miRNAs, 946 target genes were predicted, and a BAVM-specific miRNA-target gene regulatory network was constructed. Functional annotation suggested that 15 of the predicted miRNA-targeted genes were involved in vascular endothelial growth factor signaling, in which 3 critical miRNAs were involved: miR-7-5p, miR-199a-5p, and miR-200b-3p. CONCLUSIONS: We explored the miRNA expression signature of BAVMs, which will provide an important foundation for future studies on the regulation of miRNAs involved in BAVMs.

Circulating Fibroblast Growth Factor-23 Level and Paraoxonase-1 Lactonase Activity in Chronic Hemodialysis Patients: Their Impact on the Incidence of Native AV Fistula Thrombosis.

PURPOSE: Thrombosis of native arteriovenous (AV) fistula is an important cause of complications in hemodialysis (HD) patients. The purpose of this study was to investigate the usefulness of measuring circulating fibroblast growth factor-23 (FGF-23) level and paraoxonase-1 (PON1) lactonase activity as potential predictors of native AV fistula thrombosis in chronic HD patients. METHODS: This study included 83 HD patients (48 with thrombosed and 35 with non-thrombosed native AV fistulas) and 38 healthy volunteers. Serum FGF-23 level was measured using the ELISA technique, while serum PON1 lactonase activity was measured spectrophotometrically using gamma-thiobutyrolactone as a substrate. RESULTS: FGF-23 was significantly increased while PON1 lactonase was markedly decreased in both thrombosed and non-thrombosed HD patients compared with controls (P < 0.001). FGF-23 was elevated whereas PON1 lactonase was decreased in HD patients with thrombosed native AV fistulas compared with HD patients with non-thrombosed native AV fistulas (P = 0.001 and 0.002, respectively). A significant negative correlation was found between FGF-23 and PON1 lactonase in HD patients with thrombosed native AV fistulas (r = -0.342, P = 0.017). CONCLUSIONS: This study shows a potential value of FGF-23 and PON1 lactonase as predictors of native AV fistula thrombosis in HD patients.

Coagulation, thrombophilia and patency of arteriovenous fistula in children undergoing haemodialysis compared with healthy volunteers: a prospective analysis.

UNLABELLED: This study aimed to assess whether markers of coagulation, fibrinolysis or thrombophilia are increased in children on haemodialysis compared with controls and whether measurement of any of these factors could help to identify patients at an increased risk of arteriovenous fistula (AVF) occlusion. Blood samples were taken from 55 children immediately before a session of haemodialysis and from 20 healthy volunteers. Thrombin-antithrombin (TAT), D-dimer, plasmin-antiplasmin (PAP) and anticardiolipin immunoglobulin G (ACA-Ig G) were measured by ELISA. Factor V Leiden mutation (G1691A) was determined by gene polymorphism [restriction fragment length polymorphism (RFLP)]. Determination of the patency of the AVF was prospectively followed up for a minimum of 4 years or until the AVF was nonfunctioning. Fifty-five patients were studied with a median follow-up of 659 days (range 30-1670 days). A significant increase was found in the levels of D-dimer, PAP and ACA-Ig G in haemodialysis patients with thrombosed and nonthrombosed native AVFs vs. CONTROLS: There was a significant difference between both chronic haemodialysis patients with thrombosed and nonthrombosed native AVF with regard to ACA-IgG levels. At 1 year follow-up, primary patency was 61.4% (27 patients). In multivariate analysis, D-dimer was inversely associated with secondary patency.Thrombophilia may predispose children with end stage renal disease to access failure. The promising finding is that in children on haemodialysis, D-dimer levels were increased and inversely correlated with secondary patency. Further evaluation is required into the possible role of D-dimer as a biomarker of AVF occlusion.

Endovascular management of iatrogenic renal arterial lesions and clinical outcomes.

PURPOSE: We aimed to evaluate iatrogenic renal arterial lesions, including pseudoaneurysm, arteriovenous fistula, and arteriocaliceal fistula, their management by endovascular embolization, and the clinical results. METHODS: Fifty-five patients (forty males, fifteen females) with a median age of 40 years (range, 8-85 years), who underwent endovascular embolization of iatrogenic renal arterial lesions between March 2003 and December 2013 were included in this retrospective study. Types of iatrogenic lesions and details of embolization procedures were reported. Estimated glomerular filtration rate (eGFR), renal function tests, hemoglobin, and hematocrit levels before and after embolization were recorded and compared. RESULTS: Median follow-up was 24 months. We identified 53 pseudoaneurysms, 30 arteriovenous fistulas, and 11 arteriocaliceal fistulas in 55 patients, after percutaneous nephrolithotomy (n=26), renal biopsy (n=21), nephrostomy (n=3), renal surgery (n=3), and extracorporeal shock wave lithotripsy (n=2). Median number of pseudoaneurysms was 1 (range, 1-4) with a median size of 7 mm (range, 1.5-35 mm). Fifty-one patients underwent coil embolization. Median number of coils was 5 (range, 2-21) and median renal parenchymal loss was 5% (range, 1%-50%). There were no significant differences between pre- and postoperative eGFR and serum parameters. CONCLUSION: Iatrogenic renal arterial lesion can be a life threatening condition. Superselective coil embolization is a safe, minimally invasive treatment option with minimal renal parenchymal loss and without significant change in renal function.

Soluble adhesion molecules as markers of native arteriovenous fistula thrombosis in children on uremia.

Vascular access represents a lifeline for children undergoing hemodialysis. A failure of vascular access among patients receiving regular hemodialysis is associated with increased morbidity, mortality and costs. We assessed the possibility of using soluble adhesion molecules as reliable predictors of vascular access failure in children on hemodialysis. Moreover, we evaluated whether there is an association among the different studied adhesion molecules in hemodialysis patients with thrombosed and non-thrombosed arteriovenous fistula fistulas (AVFs). This study included 55 hemodialysis children, 36 with good access and 19 with access failure, and 20 healthy volunteers. Forty-four patients had native AVFs and 11 patients had tunneled permanent catheter (11with thrombosed and 33 with non-thrombosed AVFs). Serum-soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1), soluble E-selectin (sE-selectin) and soluble P-selectin (sP-selectin) were measured using ELISA technique. A significant increase was found in the levels of sVCAM-1, sICAM-1, sE-selectin and sP-selectin versus controls and all hemodialysis patients, hemodialysis patients with good access and hemodialysis patients with access failure (P=0.001 for sVCAM-1 and sICAM-1 and P=0.0001 for sE-selectin and sP-selectin). A significant increase was found in the levels of sVCAM-1, sE-selectin and sP-selectin in both chronic hemodialysis patients with thrombosed and non-thrombosed native AVFs versus controls (P=0.0001 for all parameters). There was significant difference between both chronic hemodialysis patients with thrombosed and non-thrombosed native AVFs as regard to sVCAM-1 (54.64±30.82 versus 25.69±27.96ng/ml, P=0.04). Both sICAM-1 and sP-selectin were positively correlated with the erythropoietin (EPO) dose in hemodialysis children (r=0.31, P=0.04 and r=0.32, P=0.04, respectively). A significant positive association was found between E-selectin and sP-selectin in hemodialysis patients with thrombosed AVFs (r=0.83, P=0.04). There was a significant correlation between sVCAM-1 and EPO dose in thrombosed AVF group (r=0.84, P=0.01). The assessment of serum sVCAM-1 might be useful for the identification of the chronic hemodialysis patients at an increased risk for native AVFs thrombosis. The role of EPO in vascular access failure should be taken into consideration. The clinical relevance of these observations warrants further investigations.

Predictive value of serum myeloperoxidase activity for thrombosis of arteriovenous fistulas.

Myeloperoxidase is a proinflammatory protein that appears as a result of increased oxidative stress. It plays an important role in the promotion and progression of atherosclerosis. The aim of this study was to determine the importance of MPO as a predictive parameter for thrombosis of arteriovenous fistula (AVF). The study involved monitoring patients with AVFs for hemodialysis over a period of 2 years. There were 41 patients, 19 (46%) men and 22 (54%) women, with mean age of 65 ± 12.7 years. Routine laboratory analyses were carried out in all respondents, including determination of MPO concentration. Gender, demographic and anthropometrical characteristics, smoking, alcohol consumption, as well as the presence of diabetic nephropathy, as an etiological factor of kidney disease, were recorded. The group of patients who developed initial thrombosis of the AVFs had significantly different values for leukocytes (8.5 ± 3.8 vs. 7.3 ± 2.1, P = 0.024), erythrocytes (2.8 ± 0.27 vs. 3.2 ± 0.65; P = 0.019), hemoglobin (88.5 ± 81 vs. 99.1 ± 6.02; P = 0.041), and myeloperoxidase (19.3 ± 4.67 vs. 11.1 ± 4.43; P = 0.007) when compared with the group without fistula thrombosis. Diabetic nephropathy (P = 0.02) characterized the group of patients with thrombosis of the fistula. Diabetic nephropathy (B = 2.53, P = 0.049) and MPO (B = 0.03, P = 0.029) were statistically significant predictors of fistula thrombosis. In our study, MPO and diabetic nephropathy were predictors of thrombosis of the AVF.

The level of C-reactive protein in chronic hemodialysis patients: a comparative study between patients with noninfected catheters and arteriovenous fistula in two large Gulf hemodialysis centers.

Hemodialysis (HD) patients have greater morbidity and mortality when they have a central venous catheter (CVC) rather than an arteriovenous fistula (AVF) access. Inflammation associated with dialysis catheter use and resultant higher C-reactive protein (CRP) levels could have an independent adverse effect on patient outcomes. In this prospective study, we investigated whether HD catheters induce inflammation independent of infection. We compared the mean levels of the inflammatory marker (CRP) in 67 patients on maintenance HD using noninfected catheters with 86 HD patients using AVFs at Prince Salman Center for Kidney Diseases, Saudi Arabia (KSA), and Jahra Hospital, Kuwait, who met our inclusion criteria. C-reactive protein levels were measured every 2 months over a period of 6 months using immunoturbidimetric assay. One hundred fifty-three patients on maintenance HD for more than 6 months were included in the study, with mean age of 52.19 ± 16.06 years; 66% were males and 34% were females. Serial levels of mean CRP were statistically and significantly higher in group with noninfected catheters (1.33, 1.24, and 1.10 mg/dL) compared to those with AVFs (0.65, 0.59, and 0.68 mg/dL) with P value of 0.000. In our study, we found no relation between CRP level and age, sex, hemoglobin, albumin, calcium, phosphorus, and iPTH level in both groups. Hemodialysis patients with a catheter have a heightened state of inflammation independent of infection, and thus our study supports the avoidance of catheters and a timely conversion to AVFs with catheter removal.

Management of postbiopsy arteriovenous fistulas in transplanted kidneys and effectiveness of endovascular treatment: a single-center experience.

BACKGROUND: We sought to evaluate the best therapeutic management of postbiopsy arteriovenous fistulas (AVFs) in transplanted kidneys. METHODS: Between January 2005 and December 2011, we observed 17 cases of postbiopsy AVF in transplanted kidneys (9 asymptomatic; 8 symptomatic). Asymptomatic cases were managed conservatively, while patients with symptomatic AVF underwent endovascular treatment. We used a technique that consisted in a superselective transcatheter embolization of the afferent branch. We evaluated the technical success (postoperative closure of AVF), the immediate clinical efficacy (cessation of symptoms), and clinical efficacy at follow-up (measurement of serum creatinine at 7 days and 6 and 12 months compared with preoperative levels using t-tests). RESULTS: Asymptomatic AVFs resolved spontaneously, while the endovascular treatment in symptomatic AVFs showed a complete technical and clinical success with prompt remission of the presented symptoms. We observed a statistically significant reduction in serum creatinine at 7 days and 6 and 12 months postoperatively (mean creatinine--preoperative: 3.23 ± 1.4 mg/dL; 7 days: 2.25 ± 0.8 mg/dL; 6 months: 1.65 ± 0.28 mg/dL; 12 months: 1.4 ± 0.26 mg/dL; in all cases P < 0.05). CONCLUSIONS: In our experience, asymptomatic AVFs could be managed conservatively with close follow-up while the endovascular treatment for symptomatic AVFs is both safe and effective in the short- and long-term.

Acesso vascular para hemodiálise: o que há de novo? / Vascular access for hemodialisys: what's new?

O aumento da expectativa de vida dos portadores de doenças crônicas, entre as quais a insuficiência renal crônica, faz com que métodos de tratamentos estejam em constante aperfeiçoamento. O uso em longo prazo da hemodiálise torna necessário confeccionar e manter acessos vasculares de utilização duradoura. Tanto as fístulas arteriovenosas - primeira opção de acesso para os pacientes hemodialíticos - como os cateteres vêm sendo objeto de estudos na literatura, na tentativa de prolongar sua vida útil. Esta revisão tem como objetivo relatar as alternativas e soluções atuais para os acessos vasculares para hemodiálise.

The increasing life expectancy of patients with chronic diseases, including chronic renal failure, means that treatment methods are constantly being updated and improved. Long term hemodialysis has created the need to provide and maintain long lasting vascular access. Arteriovenous fistula is the first-choice option for hemodialysis and research has been conducted to attempt to increase the useful life of both fistula and catheter access methods. This article reviews the vascular access options and solutions currently available for hemodialysis.

Thrombin-anti-thrombin levels and patency of arterio-venous fistula in patients undergoing haemodialysis compared to healthy volunteers: a prospective analysis.

BACKGROUND: Patients on haemodialysis (HD) are at an increased risk of sustaining thrombotic events especially to their vascular access which is essential for maintenance of HD. OBJECTIVES: To assess whether 1) markers of coagulation, fibrinolysis or endothelial activation are increased in patients on HD compared to controls and 2) if measurement of any of these factors could help to identify patients at increased risk of arteriovenous (AVF) access occlusion. PATIENTS/METHODS: Venous blood samples were taken from 70 patients immediately before a session of HD and from 78 resting healthy volunteers. Thrombin-antithrombin (TAT), D-dimer, von Willebrand factor (vWF), plasminogen activator inhibitor-1 antigen (PAI-1) and soluble p-selectin were measured by ELISA. C-reactive protein (hsCRP) was measured by an immunonephelometric kinetic assay. Determination of the patency of the AVF was based upon international standards and was prospectively followed up for a minimum of four years or until the AVF was non-functioning. RESULTS: A total of 70 patients were studied with a median follow-up of 740 days (range 72-1788 days). TAT, D-dimer, vWF, p-selectin and hsCRP were elevated in patients on HD compared with controls. At one year follow-up, primary patency was 66% (46 patients). In multivariate analysis TAT was inversely associated with primary assisted patency (r = -0.250, p = 0.044) and secondary patency (r = -0.267, p= 0.031). CONCLUSIONS: The novel finding of this study is that in patients on haemodialysis, TAT levels were increased and inversely correlated with primary assisted patency and secondary patency. Further evaluation is required into the possible role of TAT as a biomarker of AVF occlusion.

Hemodialysis duration, human platelet antigen HPA-3 and IgA isotype of anti-ß2glycoprotein I antibodies are associated with native arteriovenous fistula failure in Tunisian hemodialysis patients.

INTRODUCTION: Arteriovenous fistula (AVF) failure is a major cause of morbidity and mortality in hemodialysis patients. We assessed the role of a large panel of acquired and inherited thrombophilic markers in cases of AVF thrombosis among 101 Tunisians on chronic hemodialysis, all with native AVF. MATERIALS AND METHODS: In this case-control study, we considered the levels of fibrinogen, factor II, factor VII, factor VIII, factor IX, factor X, factor XI, factor XII, von Willebrand factor, natural coagulation inhibitors, D-Dimer, homocysteine, IgG, IgM and IgA anticardiolipin and anti-ß2glycoprotein I (anti-ß2GPI), and anti-H/PF4 antibodies; the presence of Lupus Anticoagulant; and genetic markers (Factor V Leiden, prothrombin 20210G>A, MTHFR 677C>T and 1298A>C). RESULTS: Multivariate analysis indicated that dialysis for >69 months (OR=10.12; 95% CI, 2.53 to 40.52; p=0.001), HPA-3aa genotype (OR=3.58; 95% CI, 1.36 to 9.4; p=0.01) and anti-ß2GPI IgA isotype (OR=3.4; 95% CI, 1.21 to 9.55; p=0.02) were independent risk factors for AVF thrombosis in Tunisian hemodialysis patients. Kaplan-Meier analysis showed that AVF survival was significantly lower for patients with anti-ß2GPI IgA than for patients without this isotype (log-rank test, p=0.014). CONCLUSIONS: IgA anti-ß2GPI may be of clinical relevance among Tunisians. Further studies on the polymorphism of ß2GPI and HPA systems would be helpful for identifying patient groups at high risk of AVF failure.

Endostatin, an inhibitor of angiogenesis, decreases after bidirectional superior cavopulmonary anastamosis.

Pulmonary arteriovenous malformations (PAVMs) are a common source of morbidity after bidirectional superior cavopulmonary anastomosis (Glenn). The diversion of hepatic venous effluent away from the pulmonary circulation after Glenn appears to play a significant role in the pathogenesis of PAVMs. Although the liver is known to produce factors that regulate vascular development, specific hepatic inhibitors of angiogenesis have not been described in the post-Glenn population. Endostatin, produced from its precursor collagen XVIII, is a potent inhibitor of angiogenesis produced by the liver. This study aimed to investigate the hypothesis that endostatin levels decrease in patients after Glenn. Levels of endostatin and its precursor, long-type collagen XVIII, were determined by enzyme-linked immunoassay and immunoprecipitation, respectively, for serum samples from 38 patients undergoing Glenn, total cavopulmonary anastomosis (Fontan), or biventricular repair of cardiac defects. Samples were obtained before surgery and 24 h afterward. In patients undergoing a bidirectional Glenn procedure, endostatin levels decreased after surgery (n = 17; 4.42 vs 3.34 ng/ml; p < 0.001), and long type-collagen XVIII levels increased by 200 % (n = 10; p = 0.0001). However, endostatin levels did not change after surgery in patients undergoing Fontan (n = 13) or biventricular repair (n = 8). In patients undergoing Fontan, long-type collagen XVIII increased by 18 % (p < 0.01), whereas in control subjects, the levels were unchanged. These data suggest that the diversion of hepatic blood flow away from the pulmonary circulation in patients after the Glenn procedure inhibits endostatin production from collagen XVIII, resulting in decreased circulating serum endostatin levels. A decrease in endostatin may promote angiogenesis. The mechanism whereby the pulmonary circulation processes endostatin and its potential role in the pathogenesis of PAVMs warrant further study.