The role of shear stress in arteriovenous fistula maturation and failure: a systematic review

Non-maturation and post-maturation venous stenosis are the primary causes of failure within arteriovenous fistulae (AVFs). Although the exact mechanisms triggering failure remain unclear, abnormal hemodynamic profiles are thought to mediate vascular remodelling and can adversely impact on fistula patency

Should patients with infrainguinal arterial bypasses using autologous vein conduit undergo follow-up surveillance with duplex ultrasound?

This best evidence topic was investigated according to a structured format. The question asked was: should duplex ultrasound (DUS) scanning be a routine component of surveillance following infrainguinal arterial bypass using vein conduit? We performed a systematic literature search and identified 4 studies (3 randomised controlled trials and 1 meta-analysis) that provided the best evidence.The highest quality study was a multi-centre randomised controlled trial (n = 594). At 18 months following surgery, it found no difference in patency rates, amputations, vascular mortality or mortality. However it achieved just over half of anticipated recruitment and thus was underpowered. The remaining two randomised controlled trials had smaller sample sizes and methodological weaknesses and found conflicting results. Lundell et al. (n = 106) found improved primary assisted and secondary patency rates and fewer graft occlusions with a routine DUS policy. Ihlberg et al. (n = 152) found no difference in primary assisted patency or amputations although secondary patency was improved. A meta-analysis of mostly observational data (n = 6649) found fewer occlusions with routine DUS surveillance and no effect on amputations or mortality.Results are conflicting. The strongest evidence comes from the single high quality multi-centre trial. It appears as though routine DUS surveillance does not yield benefits in patient important outcomes. Further studies are needed. (C) 2014 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved

The mesocolon a histological and electron microscopic characterization of the mesenteric attachment of the colon prior to and after surgical mobilization

Background: Colonic mobilization requires separation of mesocolon from underlying fascia. Despite the surgical importance of planes formed by these structures, no study has formally characterized their microscopic features. The aim of this study was to determine the histological and electron microscopic appearance of mesocolon, fascia, and retroperitoneum, prior to and after colonic mobilization.Methods: In 24 cadavers, samples were taken from right, transverse, descending, and sigmoid mesocolon. In 12 cadavers, specimens were stained with hematoxylin and eosin (3 sections) or Masson trichrome (3 sections). In the second 12 cadavers, lymphatic channels were identified by staining immunohistochemically for podoplanin. The ascending mesocolon was assessed with scanning electron microscopy. The above process was first conducted with the mesocolon in situ. The mesocolon was then surgically mobilized, and the process was repeated on remaining structures.Results: The microscopic structure of mesocolon and associated fascia was consistent from ileocecal to mesorectal level. A surface mesothelium and underlying connective tissue were evident throughout. Fibrous septae separated adipocyte lobules. Where apposed to retroperitoneum, 2 mesothelial layers separated mesocolon and underlying retroperitoneum. A connective tissue layer occurred between these (ie, Toldt's fascia). Lymphatic channels were evident both in mesocolic connective tissue and Toldt's fascia. After surgical separation of mesocolon and fascia both remained contiguous, the fascia remained in situ and the retroperitoneum undisturbed.Conclusions: The findings demonstrate that the contiguous mesocolon and retroperitoneum are separated by mesothelial and connective tissue layers. These properties generate the surgical planes (ie, meso-and retrofascial planes) exploited in colonic and mesocolic mobilization

Comparing the endothelialisation of extracellular matrix bioscaffolds with coated synthetic vascular graft materials

Introduction Existing synthetic vascular grafts have unacceptably high failure rates when replacing small diameter infrapopliteal vessels [1]. The lack of a confluent endothelial lining is repeatedly cited as the most common cause of conduit failure [2, 3]

One-stage vs.two-stage brachio-basilic arteriovenous fistula for dialysis access: a systematic review and a meta-analysis

A brachiobasilic arteriovenous fistula (BB-AVF) can provide access for haemodialysis in patients who are not eligible for a more superficial fistula. However, it is unclear whether one or two-stage BB-AVF is the best option for patients

Validation of ERICVA risk score as a predictor of one year amputation-free survival of patients with critical limb ischemia

Background: The ERICVA score was derived to predict amputation-free survival in patients with critical limb ischemia (CLI). It may be a useful tool to stratify patients in trials of novel interventions to treat CLI but, as yet, it has not been externally validated. Methods: A prospective database of CLI patients was developed during prescreening of patients for a phase 1 stem cell therapy clinical trial. The primary outcome was amputation free survival (AFS) at 1 year. Both the full ERICVA scale (11 parameters) and simplified ERICVA scale (5 parameters) were validated. Data analysis was performed by calculation of the area under the receiver operating characteristic (ROC) curve examining the predictive value of the scores. The Chi-square test was used to examine the association between risk group and one-year AFS and the cumulative survival of the three risk groups was compared using Kaplan Meier survival curves. Results: A series of 179 CLI patients were included in the analysis. The Chi-square test of independence showed a significant association between the risk group (high, medium and low) and one-year AFS outcome (P = 0.0007). Kaplan-Meier survival curve showed significant difference in one-year AFS between the three risk groups (log-rank P < 0.001). The area under the curve (AUC) was found to be 0.63 and 0.61 for the full and simplified score, respectively. The sensitivity of the full score was 0.44 with specificity of 0.84. The simplified score had a sensitivity of 0.28 and specificity of 0.92. Conclusion: The ERICVA risk score system was found to have a fair validity but cannot be considered reliable as a single predictor of one year AFS of CLI patients. The simplified score had an AUC almost identical to the full score and can accordingly replace the full score

Introducing a novel and robust technique for determining lymph node status in colorectal cancer

Objective: This study aims to harness the potential of public gene expression repositories, to develop gene expression profiles that could accurately determine nodal status in colorectal cancer. Background: Currently, techniques that determine lymph node positivity (before resection) have poor sensitivity and specificity. The ability to determine lymph node status, based on preoperative biopsies, would greatly assist in planning treatment in colorectal cancer. This is particularly relevant in polypdetected cancers. Methods: Public gene expression repositories were screened for experiments comparing metastatic and nonmetastatic colorectal cancer. A customized graphic user interface was developed to extract genes dysregulated across most identified studies (ie, consensus profiles). The utility of consensus profiles was tested by determining whether classifiers could be derived that determined nodal positivity or negativity. Consensus profiles-derived classifiers were tested on separate Affymetrix- and Illumina-based experiments, and collated outputs were compiled in summary receiver operator curve characteristic format, with area under the curve (AUC) reflecting accuracy. The association between classification and oncologic outcome was determined using an additional, independent data set. Final validation was conducted using the Ingenuity network-linkage environment. Results: Four consensus profiles were generated from which classifiers were derived that accurately determined node positive and negative status (pooled AUC were 0.79 ± 0.04 and 0.8 ± 0.03 for nodal positivity and negativity, respectively). Overall AUC ranged from 0.73 to 0.86, demonstrating high accuracy across consensus profile type, classification technique, and array platform used. As consensus profile enabled classification of nodal status, survival outcomes could be compared for those predicted node negative or positive. Patterns of disease-free and overall survival were identical to those observed for standard histopathologic nodal status. Genes contained within consensus profiles were strongly linked to the metastatic process and included (among others) FYN,WNT5A, COL8A1, BMP, and SMAD family members. Conclusions: Microarray expression data available in public gene expression repositories can be harnessed to generate consensus profiles. The latter are a source of classifiers that have prognostic and predictive properties

Differential impact of smoking on mortality and kidney transplantation among adult Men and Women undergoing dialysis

Background: The extent to which smoking contributes to adverse outcomes among men and women of all ages undergoing dialysis is uncertain. The objective of this study was to determine the differential impact of smoking on risks of mortality and kidney transplantation by age and by sex at dialysis initiation.Methods: We conducted a population-based cohort of incident U.S dialysis patients (n = 1, 220, 000) from 1995-2010. Age- and sex-specific mortality and kidney transplantation rates were determined for patients with and without a history of cardiovascular disease. Multivariable Cox regression evaluated relative hazard ratios (HR) for death and kidney transplantation at 2 years stratified by atherosclerotic condition, smoking status and age. Analyses were adjusted for demographic characteristics, non-cardiovascular conditions, laboratory variables, socioeconomic and lifestyle factors.Results: The average age was 62.8 (+/- 15) years old, 54 % were male, and the majority was white. During 2-year follow-up, 40.5 % died and 5.7 % were transplanted. Age-and sex-specific mortality rates were significantly higher while transplantation rates were significantly lower for smokers with atherosclerotic conditions than non-smokers (

Preconditioning shields against vascular events in surgery (SAVES), a multicentre feasibility trial of preconditioning against adverse events in major vascular surgery: study protocol for a randomised control trial

Background: Patients undergoing vascular surgery procedures constitute a 'high-risk' group. Fatal and disabling perioperative complications are common. Complications arise via multiple aetiological pathways. This mechanistic redundancy limits techniques to reduce complications that target individual mechanisms, for example, anti-platelet agents. Remote ischaemic preconditioning (RIPC) induces a protective phenotype in at-risk tissue, conferring protection against ischaemia-reperfusion injury regardless of the trigger. RIPC is induced by repeated periods of upper limb ischaemia-reperfusion produced using a blood pressure cuff. RIPC confers some protection against cardiac and renal injury during major vascular surgery in proof-of-concept trials. Similar trials suggest benefit during cardiac surgery. Several uncertainties remain in advance of a full-scale trial to evaluate clinical efficacy. We propose a feasibility trial to fully evaluate arm-induced RIPC's ability to confer protection in major vascular surgery, assess the incidence of a proposed composite primary efficacy endpoint and evaluate the intervention's acceptability to patients and staff.Methods/Design: Four hundred major vascular surgery patients in five Irish vascular centres will be randomised (stratified for centre and procedure) to undergo RIPC or not immediately before surgery. RIPC will be induced using a blood pressure cuff with four cycles of 5 minutes of ischaemia followed by 5 minutes of reperfusion immediately before the start of operations. There is no sham intervention. Participants will undergo serum troponin measurements preoperatively and 1, 2, and 3 days post-operatively. Participants will undergo 12-lead electrocardiograms pre-operatively and on the second post-operative day. Predefined complications within one year of surgery will be recorded. Patient and staff experiences will be explored using qualitative techniques. The primary outcome measure is the proportion of patients who develop elevated serum troponin levels in the first 3 days post-operatively. Secondary outcome measures include length of hospital and critical care stay, unplanned critical care admissions, death, myocardial infarction, stroke, mesenteric ischaemia and need for renal replacement therapy (within 30 days of surgery).Discussion: RIPC is novel intervention with the potential to significantly improve perioperative outcomes. This trial will provide the first evaluation of RIPC's ability to reduce adverse clinical events following major vascular surgery