scholarly journals Screening and surveillance of venous stenosis in AVG: Is it time to rethink our assumptions?

2021 ◽  
pp. 112972982110556
Author(s):  
David B Kingsmore ◽  
Peter Thomson ◽  
Karen Stevenson
Keyword(s):  
Observational Data ◽  
Randomised Trials ◽  
Stent Grafts ◽  
Venous Stenosis ◽  
Screening And Surveillance ◽  
Arteriovenous Grafts

Guidelines make no firm recommendations about surveillance of arteriovenous grafts as several randomised trials (RCT) have not shown a clear benefit in patency. However a more thorough review of these RCT based on epidemiological principles reveals significant limitations. In particular a key weakness of these older studies is the interventions performed for venous stenosis detected that was largely angioplasty. However, the observational data of modern stent-grafts shows a clear benefit over angioplasty, and thus seems to suggest that a modern well considered RCT is now mandated.

Pre-emptive or reactive treatment, angioplasty or stent-graft? The outcome for interventions for venous stenosis in early-cannulation arteriovenous grafts

2021 ◽  
pp. 112972982110294
Author(s):  
David B Kingsmore ◽  
Karen S Stevenson ◽  
Peter C Thomson ◽  
Ram Kasthuri ◽  
Stephen Knight ◽  
...  
Keyword(s):  
Case Mix ◽  
Stent Grafts ◽  
Stent Grafting ◽  
Venous Stenosis ◽  
Mode Of Presentation ◽  
Significant Difference ◽  
Elective Procedure ◽  
Arteriovenous Grafts ◽  
The Impact

Background: Early-cannulation arteriovenous grafts (ecAVG) have good initial patency, but frequent episodes of reintervention for venous stenosis (VS) and thrombosis limit their use. Stent grafts (SG) have shown promise in reducing re-interventions and improving functional patency for dysfunctional ecAVG and recurrent VS. There is little data on the impact of stent grafts as the first elective procedure for VS. The aim of this study was to determine firstly, if treating VS whilst asymptomatic has a better outcome than treating after presentation with thrombosis; and secondly, to determine the best initial treatment for asymptomatic VS: SG or angioplasty. Methods: A retrospective study was performed of 259 ecAVG with a sutured anastomosis. The case-mix and outcomes of 153 who presented with VS was analysed by presentation (elective at surveillance or emergency following thrombosis), and then for only elective patients, by treatment (SG vs angioplasty). Results: There was no significant difference in case-mix and time to presentation by mode of presentation (100 elective and 53 with thrombosis) other than a higher rate of pro-thrombotic disorders in thrombosed ecAVG. Thrombosed ecAVG had poorer outcomes with increased re-intervention rates and thrombosis in the following year, and reduced long-term functional patency. In patients presenting electively, primary SG rather than angioplasty led to significantly reduced thrombosis rates, a longer time to re-intervention in the following year, and superior long-term functional patency. The use of SG was the same in both groups. Both the mode of presentation and the type of intervention performed were independently predictive of a poorer subsequent functional patency. Conclusions: Primary elective stent-grafting may be the optimal strategy to reducing maintenance costs with ecAVG.

Endovascular stent-graft treatment for graft-vein anastomotic stenosis in haemodialysis patients with arteriovenous grafts

VASA ◽  
2015 ◽  
Vol 44 (6) ◽  
pp. 466-472 ◽  
Author(s):  
Chia-Hsun Lin ◽  
Yen-Yang Chen ◽  
Chai-Hock Chua ◽  
Ming-Jen Lu
Keyword(s):  
Risk Factors ◽  
Stent Graft ◽  
Target Lesion ◽  
Primary Patency ◽  
Anastomotic Stenosis ◽  
Secondary Patency ◽  
Endovascular Stent ◽  
Stent Grafts ◽  
Venous Anastomosis ◽  
Arteriovenous Grafts

Abstract. Background: In this study, we investigated the patency of endovascular stent grafts in haemodialysis patients with arteriovenous grafts, the modes of patency loss, and the risk factors for re-intervention. Patients and methods: Haemodialysis patients with graft-vein anastomotic stenosis of their arteriovenous grafts who were treated with endovascular stent-grafts between 2008 and 2013 were entered into this retrospective study. Primary and secondary patency, modes of patency loss, and risk factors for intervention were recorded. Results: Cumulative circuit primary patency rates decreased from 40.0 % at 6 months to 7.3 % at 24 months. Cumulative target lesion primary patency rates decreased from 72.1 % at 6 months to 22.0 % at 24 months. Cumulative secondary patency rates decreased from 81.3 % at 12 months to 31.6 % at 36 months. Patients with a history of cerebrovascular accident had a significantly higher risk of secondary patency loss, and graft puncture site stenosis jeopardised the results of stent-graft treatment. Conclusions: Our data can help to improve outcomes in haemodialysis patients treated with stent-grafts for venous anastomosis of an arteriovenous graft.

scholarly journals Preserving equipoise and performing randomised trials for COVID-19 social distancing interventions

2020 ◽  
Vol 29 ◽  
Author(s):  
Ioana Alina Cristea ◽  
Florian Naudet ◽  
John P. A. Ioannidis
Keyword(s):  
Observational Data ◽  
Study Design ◽  
Randomised Controlled Trials ◽  
Controlled Trials ◽  
Randomised Trials ◽  
Social Distancing ◽  
Design Choice ◽  
Travel Restrictions ◽  
Randomised Controlled ◽  
Selection Of

Abstract In the coronavirus disease 2019 (COVID-19) pandemic, a large number of non-pharmaceutical measures that pertain to the wider group of social distancing interventions (e.g. public gathering bans, closures of schools, workplaces and all but essential business, mandatory stay-at-home policies, travel restrictions, border closures and others) have been deployed. Their urgent deployment was defended with modelling and observational data of spurious credibility. There is major debate on whether these measures are effective and there is also uncertainty about the magnitude of the harms that these measures might induce. Given that there is equipoise for how, when and if specific social distancing interventions for COVID-19 should be applied and removed/modified during reopening, we argue that informative randomised-controlled trials are needed. Only a few such randomised trials have already been conducted, but the ones done to-date demonstrate that a randomised trials agenda is feasible. We discuss here issues of study design choice, selection of comparators (intervention and controls), choice of outcomes and additional considerations for the conduct of such trials. We also discuss and refute common counter-arguments against the conduct of such trials.

A critical review of surgical strategies to minimise venous stenosis in arteriovenous grafts

2021 ◽  
pp. 112972982110609
Author(s):  
David Kingsmore ◽  
Andrew Jackson ◽  
Karen Stevenson
Keyword(s):  
Clinical Trials ◽  
Surgical Technique ◽  
Computer Modelling ◽  
Practice Size ◽  
Approach Distance ◽  
Venous Stenosis ◽  
Wide Range ◽  
Observational Series ◽  
Surgical Options ◽  
Arteriovenous Grafts

It is inevitable that complications arising from surgical procedures are ascribed to surgical technique, and this applies to venous stenosis (VS) in arteriovenous grafts. However, despite a wide range of cellular studies, computer modelling, observational series and clinical trials, there remains uncertainty on whether surgical technique contributes to VS. This article reviews evidence from basic science, fluid dynamics and clinical data to try and rationalise the main surgical options to modify the occurrence of venous stenosis. There is sufficient data from diverse sources to make recommendations on clinical practice (size of target vein, shape of anastomosis, angle of approach, distance from venous needling, trauma to the target vein) whilst at the same time this emphasises the need to carefully report the practical aspects of surgical technique in future clinical trials.

Observational data: Understanding the real MS world

2016 ◽  
Vol 22 (13) ◽  
pp. 1642-1648 ◽  
Author(s):  
Tomas Kalincik ◽  
Helmut Butzkueven
Keyword(s):  
Observational Data ◽  
Observational Studies ◽  
Treatment Effectiveness ◽  
Primary Source ◽  
Mitigation Strategies ◽  
Randomised Trials ◽  
Disease Modifying Drugs ◽  
Trial Setting

Randomised clinical trials are the primary source of evidence, guiding the use of disease-modifying drugs in multiple sclerosis. However, the spectrum of questions that can be answered in the trial setting is relatively narrow. ‘Real-world’ observational data analysis has always been the major source of evidence for epidemiology, aetiology, outcomes and prognostics, but is now also increasingly used to study treatment effectiveness. While analyses of observational cohorts typically offer superior power, generalisability and duration of follow-up relative to prospective randomised trials, they are also subject to multiple biases. It is the role of researchers to mitigate bias and to ensure the results of observational studies are robust and valid. In this review of observational data research, we provide an overview of the inherent biases, the available mitigation strategies, and the state and direction of contemporary treatment outcomes research. The review will help clinicians critically appraise published results of observational studies.

Stent-grafts versus angioplasty and/or bare metal stents for failing arteriovenous grafts: a cross-over longitudinal study

2012 ◽  
Vol 26 (2) ◽  
pp. 389-395 ◽  
Author(s):  
Dimitris Karnabatidis ◽  
Panagiotis Kitrou ◽  
Stavros Spiliopoulos ◽  
Konstantinos Katsanos ◽  
Athanasios Diamantopoulos ◽  
...  
Keyword(s):  
Longitudinal Study ◽  
Bare Metal Stents ◽  
Metal Stents ◽  
Bare Metal ◽  
Stent Grafts ◽  
Arteriovenous Grafts

Stent Grafts Provided Superior Primary Patency for Central Venous Stenosis Treatment in Comparison with Angioplasty and Bare Metal Stent

2016 ◽  
Vol 50 (4) ◽  
pp. 221-230 ◽  
Author(s):  
Pietro Quaretti ◽  
Franco Galli ◽  
Lorenzo Paolo Moramarco ◽  
Riccardo Corti ◽  
Giovanni Leati ◽  
...  
Keyword(s):  
Bare Metal Stent ◽  
Primary Patency ◽  
Bare Metal ◽  
Metal Stent ◽  
Stent Grafts ◽  
Central Venous ◽  
Central Venous Stenosis ◽  
Venous Stenosis

scholarly journals Arteriovenous conduits for hemodialysis: how to better modulate the pathophysiological vascular response to optimize vascular access durability

2019 ◽  
Vol 316 (5) ◽  
pp. F794-F806 ◽  
Author(s):  
Yan-Ting Shiu ◽  
Joris I. Rotmans ◽  
Wouter Jan Geelhoed ◽  
Daniel B. Pike ◽  
Timmy Lee
Keyword(s):  
Vascular Access ◽  
Intimal Hyperplasia ◽  
Vascular Remodeling ◽  
Clinical Problem ◽  
Future Research ◽  
Vascular Response ◽  
Arteriovenous Fistulas ◽  
Venous Stenosis ◽  
Arteriovenous Grafts ◽  
Clinical Problems

Vascular access is the lifeline for patients on hemodialysis. Arteriovenous fistulas (AVFs) are the preferred vascular access, but AVF maturation failure remains a significant clinical problem. Currently, there are no effective therapies available to prevent or treat AVF maturation failure. AVF maturation failure frequently results from venous stenosis at the AVF anastomosis, which is secondary to poor outward vascular remodeling and excessive venous intimal hyperplasia that narrows the AVF lumen. Arteriovenous grafts (AVGs) are the next preferred vascular access when an AVF creation is not possible. AVG failure is primarily the result of venous stenosis at the vein-graft anastomosis, which originates from intimal hyperplasia development. Although there has been advancement in our knowledge of the pathophysiology of AVF maturation and AVG failure, this has not translated into effective therapies for these two important clinical problems. Further work will be required to dissect out the mechanisms of AVF maturation failure and AVG failure to develop more specific therapies. This review highlights the major recent advancements in AVF and AVG biology, reviews major clinical trials, and discusses new areas for future research.

Current status of special planetary and lunar theories and ephemerides

1966 ◽  
Vol 25 ◽  
pp. 266-267
Author(s):  
R. L. Duncombe
Keyword(s):  
Observational Data ◽  
Current Status ◽  
Numerical Errors

An examination of some specialized lunar and planetary ephemerides has revealed inconsistencies in the adopted planetary masses, the presence of non-gravitational terms, and some outright numerical errors. They should be considered of temporary usefulness only, subject to subsequent amendment as required for the interpretation of observational data.

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