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

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

The Effect of Geometric Graft Modification on Arteriovenous Graft Patency in Haemodialysis Patients: A Systematic Review and Meta-Analysis.

OBJECTIVE: Arteriovenous grafts (AVGs) are the second best option for haemodialysis access when native arteriovenous fistulae placement is not possible, because they have a lower patency owing to neointimal hyperplasia at the venous anastomosis. This review aimed to evaluate the effect of geometric graft modification to the graft-vein interface on AVG patency. DATA SOURCES: The MEDLINE and Embase (OvidSP) databases were systematically searched for relevant studies analysing the effect of geometrically modified AVGs on graft patency and stenosis formation (last search July 2019). REVIEW METHODS: Data regarding AVG type, patency, and graft outlet stenosis was extracted for further evaluation. Data were pooled in a random effects model to estimate the relative risk of graft occlusion within one year. Follow up, number of patients, and relevant patient characteristics were extracted for the quality assessment of the included studies using Newcastle-Ottawa Scale and Cochrane Risk of Bias Tool. The quality of the evidence was determined according to the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system. RESULTS: Search strategies produced 2772 hits, of which eight articles met predetermined inclusion criteria. Overall, the included articles had low to moderate risk of bias. In total, 414 expanded polytetrafluoroethylene AVGs (232 geometrically modified and 182 standard) were analysed, comprising two modified AVG types: a prosthetic cuff design (Venaflo®) and grafts with a Tyrell vein patch. Overall, modified grafts did not show a statistically significantly higher one year primary (relative risk [RR] 0.86, 95% confidence interval [CI] 95% 0.64-1.16; GRADE: "low to very low") or secondary patency (RR 0.57, 95% CI 0.32-1.02; GRADE: "low to very low") when compared with standard AVGs. Analysis of prosthetic cuffed grafts (112 patients) separately demonstrated a statistically significantly higher one year primary (RR 0.75, 95% CI 0.61-0.91) and one year secondary patency (RR 0.47, 95% CI 0.30-0.75) compared with standard grafts (92 patients). The results on stenosis formation were inconclusive and inadmissible to quantitative analyses. CONCLUSION: The meta-analysis showed that a prosthetic cuff design significantly improves AVG patency, while a venous cuff does not. Although the heterogeneity and low number of available studies limit the strength of the results, this review shows the potential of grafts with geometric modification to the graft-vein anastomosis and should stimulate further clinical and fundamental research on improving graft geometry to improve graft patency.

Pre-operative Patient Specific Flow Predictions to Improve Haemodialysis Arteriovenous Fistula Maturation (Shunt Simulation Study): A Randomised Controlled Trial.

OBJECTIVE: An arteriovenous fistula (AVF) needs to mature before it becomes suitable to cannulate for haemodialysis treatment. Maturation importantly depends on the post-operative flow increase. Unfortunately, 20-40% of AVFs fail to mature (FTM). A patient specific computational model that predicts immediate post-operative flow was developed, and it was hypothesised that providing information from this model for planning of fistula creation might reduce FTM rates. METHODS: A multicentre, randomised controlled trial in nine Dutch hospitals was conducted in which patients with renal failure who were referred for AVF creation, were recruited. Patients were randomly assigned (1:1) to the control or computer simulation group. Both groups underwent a work up, with physical and duplex ultrasonography (DUS) examination. In the simulation group the data from the DUS examination were used for model simulations, and based on the immediate post-operative flow prediction, the ideal AVF configuration was recommended. The primary endpoint was AVF maturation defined as an AVF flow ≥500 mL/min and a vein inner diameter of ≥4 mm six weeks post-operatively. The secondary endpoint was model performance (i.e. comparisons between measured and predicted flows, and (multivariable) regression analysis for maturation probability with accompanying area under the receiver operator characteristic curve [AUC]). RESULTS: A total of 236 patients were randomly assigned (116 in the control and 120 in the simulation group), of whom 205 (100 and 105 respectively) were analysed for the primary endpoint. There was no difference in FTM rates between the groups (29% and 32% respectively). Immediate post-operative flow prediction had an OR of 1.15 (1.06-1.26; p < .001) per 100 mL/min for maturation, and the accompanying AUC was 0.67 (0.59-0.75). CONCLUSION: Providing pre-operative patient specific flow simulations during surgical planning does not result in improved maturation rates. Further study is needed to improve the predictive power of these simulations in order to render the computational model an adjunct to surgical planning.

Surgical and Endovascular Intervention for Dialysis Access Maturation Failure During and After Arteriovenous Fistula Surgery: Review of the Evidence.

BACKGROUND: Maturation failure is the major obstacle to establishing functional arteriovenous fistulae (AVF) for haemodialysis treatment. Various endovascular and surgical techniques have been advocated to enhance fistula maturation and to increase the number of functional AVFs. This narrative review considers the available evidence of interventional techniques for treatment of AVF non-maturation. RESULTS: Intra-operative vein dilation and anastomosis modification results in a clinical maturation rate of 74-92% and a 6 month cumulative AVF patency of 79-93%. Percutaneous transluminal angioplasty (PTA) with or without accessory vein obliteration is successful in 43-97% of patients. The long-term primary patency of PTA is rather low and multiple re-interventions are needed to achieve an acceptable cumulative fistula patency. The results of surgical revision exceed the results of endovascular intervention, with a mean primary one year patency of 73% (range 68-78%) compared with 49% (range 28-72%), respectively. The role of accessory vein obliteration remains unclear. CONCLUSION: Intervention for autologous arteriovenous fistula non-maturation is worthwhile and results in an increased number of functional fistulae. The outcome of surgical revision is better than endovascular and might be preferable in certain patient populations.

Three Year Patency and Recurrence Rates of Revision Using Distal Inflow with a Venous Interposition Graft for High Flow Brachial Artery Based Arteriovenous Fistula.

OBJECTIVES: Upper arm arteriovenous fistulas (AVF) occasionally develop high flow. Revision using distal inflow (RUDI) effectively reduces flow of high flow accesses (HFA) in the short-term and is also popularised for treatment of haemodialysis access induced distal ischaemia (HAIDI). The long-term efficacy is unknown. The study's aim was to report on 3 year RUDI patency and recurrence rates for HFA with and without HAIDI. MATERIAL AND METHODS: This was a retrospective cohort study of patients with a HFA with or without HAIDI undergoing RUDI using greater saphenous vein (GSV) interposition between March 2011 and October 2017 at three facilities. AVFs were termed HFA if flow volumes exceeded 2 L/min on two consecutive measurements using dilution techniques. HAIDI was diagnosed as recommended. Following RUDI, follow up was not different from standard care in AVF patients. Data on post-operative flows and re-interventions were extracted from electronic patient files. Loss to follow up was avoided. Rates of patency and HFA recurrence were analysed. RESULTS: During the observation period, 21 patients were studied (7 females, 54 years ± 3). Fourteen had uncomplicated HFA whereas seven had additional HAIDI. Immediately post-operatively, flows decreased threefold (3120 mL/min ± 171 vs. 1170 mL/min ± 87, p < .001). Overall 3 year primary patency was 48% ± 12 (HFA, 55% ± 15 vs. HAIDI/HFA, 29% ± 17, p = .042). Secondary patency was identical in both groups (overall, 84% ± 9). Interventions were percutaneous transluminal angioplasty (n = 12, 9 patients), thrombectomy (n = 7, 3 patients), and revision with new interposition grafts (n = 3). After 3 years, 51% ± 12 were free of high flow (HFA, 32% ± 13 vs. HAIDI/HFA, 100%, p = .018). High immediate post-operative access flow predicted recurrence (OR 1.004 [1.000-1.007], p = .044). Patients with recurrence were 12 years younger than those without (p = .055). CONCLUSION: RUDI with GSV interposition for HFA offers acceptable patency rates after 3 years although re-interventions are often required. High immediate post-operative flows and young age are associated with recurrent high flow.

Pre-operative Duplex Ultrasonography in Arteriovenous Fistula Creation: Intra- and Inter-observer Agreement.

OBJECTIVE: Although clinical guidelines on arteriovenous fistula (AVF) creation advocate minimum luminal arterial and venous diameters, assessed by duplex ultrasonography (DUS), the clinical value of routine DUS examination is under debate. DUS might be an insufficiently repeatable and/or reproducible imaging modality because of its operator dependency. The present study aimed to assess intra- and inter-observer agreement of DUS examination in support of AVF surgery planning. METHODS: Ten end stage renal disease patients were included, to assess intra- and inter-observer agreement of pre-operative DUS measurements. All measurements were performed by two trained and experienced vascular technicians, blinded to measurement readings. From the routine DUS protocol, representative measurements (venous diameters, and arterial diameters and volume flow in the upper arm and forearm) were selected. For intra-observer agreement the measurements were performed in triplicate, with the probe released from the skin between each. Intraclass correlation coefficients were calculated for intra- and inter-observer agreement, and Bland-Altman plots used to graphically display mean measurement differences and limits of agreement. RESULTS: Ten patients (6 male, 59.4±19.7 years) consented to participate, and all predefined measurements were obtained. Intraclass correlation coefficients for intra-observer agreement of diameter measurements were at least 0.90 (95% CI 0.74-0.97; radial artery). Inter-observer agreement was at least 0.83 (0.46-0.96; lateral diameter upper arm cephalic vein). The Bland-Altman plots showed acceptable mean measurement differences and limits of agreement. CONCLUSION: In experienced hands, excellent intra- and inter-observer agreement can be reached for the discrete pre-operative DUS measurements advocated in clinical guidelines. DUS is therefore a reliable imaging modality to support AVF surgery planning. The content of DUS protocols, however, needs further standardisation.

Determination of brachial artery stiffness prior to vascular access creation: reproducibility of pulse wave velocity assessment.

BACKGROUND: Despite routine ultrasound mapping of upper extremity arteries and veins, early thrombosis and nonmaturation remain frequent complications following vascular access (VA) surgery. Besides vascular diameters, brachial artery stiffness is assumed to play an important role; however, reproducibility of measurements has never been established. The purpose of this study was to determine within-session and between-session variabilities of pulse wave velocity (PWV) assessment by using ultrasonography and blood pressure registration. METHODS: Beat-to-beat changes in brachial artery diameter and pressure were obtained in 21 subjects in measurement sessions on Day 1 and Day 3. Each session consisted of three acquisitions. For each acquisition, systolic and diastolic diameter and pressure were determined and used for calculation of brachial artery PWV. Within-session variability of diameter and pressure, as well as the estimated PWV, was expressed using the intraclass correlation coefficient with corresponding coefficient of variation (CoV). Between-session variability was reported using Bland-Altman analysis in combination with CoV analysis. RESULTS: Significant agreement (P < 0.001) was obtained for all diameter and pressure measurements obtained on Day 1 and Day 3. Within-session CoV of pulse pressure, diastolic diameter and distension were 7.0, 1.6 and 18.3%, respectively. Subsequent estimation of local PWV resulted in a CoV of 10.6%. Between-session CoV was 15.1, 3.8 and 18.9% for pulse pressure, diastolic diameter and distension, respectively. For PWV estimation, this resulted in a CoV of 13.5%. CONCLUSIONS: Diameter and pressure can be recorded accurately over the cardiac cycle, and calculations of distensibility, pulse pressure and PWV show a slight to moderate degree of variation. Larger studies elaborating on interindividual differences need to determine the clinical efficacy of PWV measurements prior to VA creation.

Optimising Access Surgery in Senior Haemodialysis Patients (OASIS): study protocol for a multicentre randomised controlled trial.

INTRODUCTION: Current evidence on vascular access strategies for haemodialysis patients is based on observational studies that are at high risk of selection bias. For elderly patients, autologous arteriovenous fistulas that are typically created in usual care may not be the best option because a significant proportion of fistulas either fail to mature or remain unused. In addition, long-term complications associated with arteriovenous grafts and central venous catheters may be less relevant when considering the limited life expectancy of these patients. Therefore, we designed the Optimising Access Surgery in Senior Haemodialysis Patients (OASIS) trial to determine the best strategy for vascular access creation in elderly haemodialysis patients. METHODS AND ANALYSIS: OASIS is a multicentre randomised controlled trial with an equal participant allocation in three treatment arms. Patients aged 70 years or older who are expected to initiate haemodialysis treatment in the next 6 months or who have started haemodialysis urgently with a catheter will be enrolled. To detect and exclude patients with an unusually long life expectancy, we will use a previously published mortality prediction model after external validation. Participants allocated to the usual care arm will be treated according to current guidelines on vascular access creation and will undergo fistula creation. Participants allocated to one of the two intervention arms will undergo graft placement or catheter insertion. The primary outcome is the number of access-related interventions required for each patient-year of haemodialysis treatment. We will enrol 195 patients to have sufficient statistical power to detect an absolute decrease of 0.80 interventions per year. ETHICS AND DISSEMINATION: Because of clinical equipoise, we believe it is justified to randomly allocate elderly patients to the different vascular access strategies. The study was approved by an accredited medical ethics review committee. The results will be disseminated through peer-reviewed publications and will be implemented in clinical practice guidelines. TRIAL REGISTRATION NUMBER: NL7933. PROTOCOL VERSION AND DATE: V.5, 25 February 2021.

Buttonhole needling of haemodialysis arteriovenous fistulae results in less complications and interventions compared to the rope-ladder technique.

BACKGROUND: The rope-ladder puncture technique, with cannulation along the whole length of the vessel traject, has been very common in haemodialysis patients with autogenous arterio-venous fistula (AVF). Today's dialysis population with AVF may exhibit difficult cannulation, because of a short vein length or a complicated cannulation route. An alternative needling possibility is the buttonhole (BH) technique, which inserts needles at exactly the same location during every dialysis session. The present study was conducted to investigate the effect of both cannulation techniques on the incidence of vascular access (VA) complications. METHODS: A total of 75 prevalent haemodialysis patients with autogenous AVF using the BH technique were compared with 70 patients using the rope-ladder technique. The following parameters were registered: haematoma occurrence, redness, swelling, aneurysm formation, the use of sharp or dull needles, miscannulations, and interventions. Needling pain and fear of puncture were assessed using a verbal rating scale (VRS). The duration of the follow-up was 9 months. RESULTS: Patients in the BH group had more unsuccessful cannulations, compared with the rope-ladder method (P < 0.0001), but the frequency of haematoma (P < 0.0001) and aneurysm formation (P < 0.0001) was less. In addition, intervention such as angioplasty (P < 0.0001) was higher in patients using the rope-ladder technique. A negative outcome of the BH technique was the higher incidence of access infections compared to the rope-ladder method. CONCLUSION: This study showed that the BH method is a valuable technique with few complications like haematoma, aneurysm formation and the need for interventions. However, the infections induced by the BH method should not be underestimated. This underlines the importance of an aseptic and correct technique of the buttonhole procedure.

Surgical or endovascular repair of thrombosed dialysis vascular access: is there any evidence?

INTRODUCTION: Endovascular and surgical strategies have been used to manage patients with thrombosed vascular access for hemodialysis. We analyzed the evidence to see whether endovascular or surgical treatment has the best outcome in terms of primary success rate and long-term patency. METHODS: We performed a systematic literature search of endovascular and surgical repair of thrombosed hemodialysis vascular access. The analysis included meta-analysis, randomized, and population-based studies of thrombosed arteriovenous fistulae and grafts. RESULTS: One meta-analysis and eight randomized studies on the treatment of arteriovenous graft thrombosis were identified. Studies conducted before 2002 demonstrated a significantly better primary success rate and primary and secondary patencies of surgical thrombectomy vs endovascular intervention. After 2002, similar results of both techniques have been reported. Only population-based studies on the treatment of thrombosed autogenous arteriovenous fistulae have been published, showing similar outcome of surgical and endovascular intervention in terms of primary success. The long-term primary and secondary patencies are slightly better for surgical treatment, but this concerns only forearm fistulae. CONCLUSIONS: The outcome of endovascular and surgical intervention for thrombosed vascular access is comparable, in particular for thrombosed prosthetic grafts. Surgical treatment of autogenous arteriovenous fistulae is likely to have benefit compared with endovascular means. Definitive randomized trials are needed to provide the level 1 evidence to resolve this latter issue.

Retrograde catheterization of haemodialysis fistulae and grafts: angiographic depiction of the entire vascular access tree and stenosis treatment.

BACKGROUND: The European Best Practice Guidelines on Vascular Access propose magnetic resonance angiography (MRA) of dysfunctional dialysis fistulae and grafts if visualization of the complete arterial inflow and outflow vessels is needed. In a prospective multi-centre study we determined the technical success rate of complete vascular access tree depiction by digital subtraction angiography (DSA) as an alternative to MRA. Instead of a more invasive brachial artery of femoral artery approach, we performed a retrograde catheterization of the venous outflow or graft, and stenoses were treated in connection with DSA. METHODS: A catheter was advanced into the central arterial inflow after retrograde puncture of the venous outflow or graft for depiction of the complete inflow, access region and complete outflow. Access DSA through femoral artery puncture was done if the retrograde approach failed to depict the complete vascular access tree. Stenoses with a luminal diameter reduction >or=50% were treated, if possible, in connection with DSA. RESULTS: A total of 116 dysfunctional haemodialysis fistulae and 50 grafts were included. Retrograde DSA depicted the complete vascular tree in 162 patients (97.6%). The arteriovenous anastomosis of four fistulae could not be negotiated by a catheter. DSA demonstrated 247 significant stenoses: 30, 128 and 89 were located in the arterial inflow (12.1%), AV anastomosis and graft region (51.8%) and venous outflow (36.0%), respectively. Ten patients (6.0%) had no stenosis. Eight (4.8%), 55 (33.1%) and 33 (19.9%) patients demonstrated stenoses in only inflow, access region or outflow, respectively. Stenoses in two or three vascular territories were present in 53 (31.9%) and 7 (4.2%) patients, respectively. A technically successful endovascular intervention was obtained in 135 of the 139 patients (97.1%) who underwent angioplasty and/or stent placement. Additional sheath insertion by antegrade outflow puncture was needed in 46 patients (33.1%) for the treatment of coexisting venous outflow stenoses, located downstream from the retrograde positioned sheath. Two minor complications were observed at DSA/angioplasty. CONCLUSION: As an alternative to MRA, full retrograde DSA is safe and effective for stenosis detection and stenosis treatment. However, access evaluation by a non-invasive imaging modality such as colour duplex ultrasound will be sufficient in most cases as proximal inflow stenoses are encountered in a minority of patients. Full retrograde DSA, including complete arterial inflow depiction, may then be reserved for cases with an unsuccessful outcome following endovascular intervention of stenoses depicted at ultrasound.

Dialysis needle hemodynamics in arterio-venous fistulae: a technical report.

BACKGROUND: Vascular access is the lifeline for end-stage renal disease patients needing hemodialysis treatment. For dialysis treatment two needles are placed into the vascular access. Few studies on needle hemodynamics have been published. METHODS: We investigated needle hemodynamics by means of Doppler ultrasonography, both in B-mode and in pulsed Doppler mode. RESULTS: Direct visualization of the needles, turbulence around the arterial needle and blood flow jet from the venous needle are presented. CONCLUSIONS: Ultrasound investigation of the hemodynamics of the dialysis needles is feasible. The extreme blood flow jet through the arterial needle was directed in all patients to the anterior vessel wall.

Rheos Baroreflex Hypertension Therapy System to treat resistant hypertension.

Resistant hypertension has a high prevalence and is associated with high morbidity and mortality. The Rheos Baroreflex Hypertension Therapy System is an implantable device that offers a completely new approach to treating patients with resistant hypertension by electrically activating the carotid baroreflex. Preliminary results from current feasibility clinical trials have shown sustained decreases in blood pressure after 1 year. The pivotal trial for US FDA approval and market release is currently ongoing. This article profiles the Rheos System and evaluates the treatment of resistant hypertension in general.

Randomized Controlled Trial Comparing Open Versus Laparoscopic Placement of a Peritoneal Dialysis Catheter and Outcomes: The CAPD I Trial.

OBJECTIVE: To determine the best operation technique, open versus laparoscopic, for insertion of a peritoneal dialysis (PD) catheter with regard to clinical success. Clinical success was defined as an adequate function of the catheter 2 - 4 weeks after insertion. METHODS: All patients with end-stage renal disease who were suitable for PD and gave informed consent were randomized for either open surgery or laparoscopic surgery. A previous laparotomy was not considered an exclusion criterion. Laparoscopic placement had the advantage of pre-peritoneal tunneling, the possibility for adhesiolysis, and placement of the catheter under direct vision. Catheter fixation techniques, omentopexy, or other adjunct procedures were not performed. Other measured parameters were in-hospital morbidity and mortality and post-operative infections. RESULTS: Between 2010 and 2016, 95 patients were randomized to this study protocol. After exclusion of 5 patients for various reasons, 44 patients received an open procedure and 46 patients a laparoscopic procedure. Gender, age, body mass index (BMI), hypertension, current hemodialysis, severe heart failure, and previous an abdominal operation were not significantly different between the groups. However, in the open surgery group, fewer patients had a previous median laparotomy compared with the laparoscopic group (6 vs 16 patients; p = 0.027). There was no statistically significant difference in mean operation time (36 ± 24 vs 38 ± 15 minutes) and hospital stay (2.1 ± 2.7 vs 3.1 ± 7.3 days) between the groups. In the open surgery group 77% of the patients had an adequate functioning catheter 2 - 4 weeks after insertion compared with 70% of patients in the laparoscopic group (p = not significant [NS]). In the open surgery group there was 1 post-operative death (2%) compared with none in the laparoscopic group (p = NS). The morbidity in both groups was low and not significantly different. In the open surgery group, 2 patients had an exit-site infection and 1 patient had a paramedian wound infection. In the laparoscopic group, 1 patient had a transient cardiac event, 1 patient had intraabdominal bleeding requiring reoperation, and 1 patient had fluid leakage that could be managed conservatively. The survival curve demonstrated a good long-term function of PD. CONCLUSION: This randomized controlled trial (RCT) comparing open vs laparoscopic placement of PD catheters demonstrates equal clinical success rates between the 2 techniques. Advanced laparoscopic techniques such as catheter fixation techniques and omentopexy might further improve clinical outcome.

Preoperative computer simulation for planning of vascular access surgery in hemodialysis patients.

INTRODUCTION: The arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis patients. Unfortunately, 20-40% of all constructed AVFs fail to mature (FTM), and are therefore not usable for hemodialysis. AVF maturation importantly depends on postoperative blood volume flow. Predicting patient-specific immediate postoperative flow could therefore support surgical planning. A computational model predicting blood volume flow is available, but the effect of blood flow predictions on the clinical endpoint of maturation (at least 500 mL/min blood volume flow, diameter of the venous cannulation segment ≥4 mm) remains undetermined. METHODS: A multicenter randomized clinical trial will be conducted in which 372 patients will be randomized (1:1 allocation ratio) between conventional healthcare and computational model-aided decision making. All patients are extensively examined using duplex ultrasonography (DUS) during preoperative assessment (12 venous and 11 arterial diameter measurements; 3 arterial volume flow measurements). The computational model will predict patient-specific immediate postoperative blood volume flows based on this DUS examination. Using these predictions, the preferred AVF configuration is recommended for the individual patient (radiocephalic, brachiocephalic, or brachiobasilic). The primary endpoint is FTM rate at six weeks in both groups, secondary endpoints include AVF functionality and patency rates at 6 and 12 months postoperatively. TRIAL REGISTRATION: ClinicalTrials.gov (NCT02453412), and ToetsingOnline.nl (NL51610.068.14).

The effect of flow changes on the arterial system proximal to an arteriovenous fistula for hemodialysis.

Arterial remodeling in response to flow changes is controlled by the endothelium, sensing wall shear stress (SS) changes. The present study focuses on the remodeling capacities of the brachial (BA) and radial artery (RA) of 16 renal failure patients after arteriovenous fistula creation. Pre- and postoperatively at predetermined time-points, diameter, wall thickness and peak and mean SS were assessed. After arteriovenous fistula creation, acute increases in BA SS (p = 0.018) and lumen diameter (p = 0.028) were observed. The diameter further increased in the next year (p = 0.023), whereas BA SS remained unchanged. RA SS and diameter increased acutely (p = 0.005) and remained unaltered after 1 y. RA wall thickness tended to decrease acutely (p = 0.059) and increased steadily during 1 y (p = 0.008). BA and RA diameter acutely increased after an acute SS rise and remained augmented after 1 y. Also, the RA vessel wall thickness enlarged, indicating structural remodeling. After 1 y, however, these changes did not result in SS restoration.

Patient safety in dialysis access: education and research.

Today, a growing activity to improve patient safety in all domains of medicine is reality. This chapter deals with patient safety research in general, but is also about strategies to implement this evidence in the daily clinical work treating patients on dialysis. Good clinical research practice has been well established for some years. In the domain of dialysis access, further basic, clinical, epidemiological and health service research will be important to further improve patient safety as a whole.

Hemodialysis vascular access management in the Netherlands.

PURPOSE: In the Netherlands, 86% of patients start renal replacement therapy with chronic intermittent hemodialysis (HD). Guidelines do indicate predialysis care and maintenance of a well-functioning vascular access (VA) as critical issues in the management of the renal failure patient. Referral to the surgeon and time to VA creation are important determinants of the type and success of the VA and HD treatment. METHODS AND RESULTS: Data from a national questionnaire showed that time from referral to the surgeon and actual access creation is <4 weeks in 43%, 4 to 8 weeks in 30% and >8 weeks in 27% of the centers. Preoperative ultrasonography and postoperative access flowmetry are the diagnostic methods in the majority of centers (98%). Most facilities perform rope-ladder cannulation with occasionally the buttonhole technique for selected patients in 87% of the dialysis units. Endovascular intervention for thrombosis is practiced by 13%, surgical thrombectomy by 21% and either endovascular or surgery by 66% of the centers. Weekly multidisciplinary meetings are organized in 57% of the units. Central vein catheters are inserted by radiologists (36%), nephrologists and surgeons (32%). CONCLUSIONS: We conclude that guidelines implementation has been successful in particular regarding issues as preoperative patient assessment for VA creation and postoperative surveillance in combination with (preemptive) endovascular intervention, leading to very acceptable VA thrombosis rates.

Chlamydia pneumoniae serology is associated with thrombosis-related but not with plaque-related microembolization during carotid endarterectomy.

BACKGROUND AND PURPOSE: Chlamydia pneumoniae has repeatedly been associated with atherosclerotic disease. Our study was designed to clarify whether this association is based on C pneumoniae-induced transformation of a stable into an unstable atherosclerotic plaque or on stimulation of hypercoagulability leading to increased thrombotic arterial occlusions by C pneumoniae infection. Transcranial Doppler ultrasonographic monitoring of the middle cerebral artery during carotid endarterectomy offers the opportunity to study, before removal of the plaque, atherothrombotic emboli dislodging from an unstable carotid plaque (plaque-related emboli) and emboli related to (excessive) thrombus formation at the endarterectomy site after removal of the plaque and restoration of flow (thrombosis-related emboli). METHODS: C pneumoniae IgA (> or =1/16) and IgG (> or =1/64) seropositivity was assessed in 53 patients with symptomatic carotid artery disease undergoing carotid endarterectomy. The removed carotid plaques were studied histologically to assess plaque instability. RESULTS: Plaque- and thrombosis-related emboli were registered in 43 patients with an adequate transtemporal window. IgA seropositivity (58%) was associated significantly with thrombosis-related embolization (P=0.030) but not with plaque-related embolization or with histological plaque instability. CONCLUSIONS: C pneumoniae serology is associated with microembolization after endarterectomy and restoration of flow. Since these microemboli represent platelet aggregations and are related to cerebrovascular complications, our data suggest that C pneumoniae infection contributes to cerebrovascular events in patients with carotid artery disease through stimulation of thrombosis.