Outcome of selective patching following carotid endarterectomy

Objectives:Routine patch angioplasty has been advocated following carotid endarterectomy but patching can be associated with complications. This study assesses the effect of a selective patching policy based on distal internal carotid diameter on the rate of restenosis and outcome following carotid endarterectomy.Design, material and methods:A consecutive series of 213 patients underwent carotid endarterectomy performed by one surgeon. Preoperative carotid dimensions were measured intraoperatively using calipers. Following endarterectomy a 5mm Dacron patch was selectively employed if the distal internal carotid was 5mm or less (group 1, 95 patients) or 6mm or less (group 2, 118 patients). Patients underwent colour-coded Duplex scanning at 24 h, 1 week, 3, 6, 9, and 12 months, and yearly following this.Results:Overall 27 restenoses (5 residual) of 50% or greater and two occlusions developed. Patching was performed in 47% of group 1 and 61% of group 2 arteries. In group 1 14% of patched compared with 24% of non-patched arteries developed restenosis at 24 months (p = 0.4). In group 2 13% of patched compared to 11% of non-patched arteries developed restenosis at 12 months (p > 0.5). Stroke rate at 24 months were similar for patched and non-patched patients in groups 1 (p > 0.5) and 2 (p = 0.4).Conclusions:This study suggests that patch angioplasty of larger carotid arteries may be unnecessary. Randomisation of larger arteries between patch and primary closure would be required to confirm this

Antarctic climate and ice-sheet configuration during the early Pliocene interglacial at 4.23Ma

The geometry of Antarctic ice sheets during warm periods of the geological past is difficult to determine from geological evidence, but is important to know because such reconstructions enable a more complete understanding of how the ice-sheet system responds to changes in climate. Here we investigate how Antarctica evolved under orbital and greenhouse gas conditions representative of an interglacial in the early Pliocene at 4.23Ma, when Southern Hemisphere insolation reached a maximum. Using offline-coupled climate and ice-sheet models, together with a new synthesis of high-latitude palaeoenvironmental proxy data to define a likely climate envelope, we simulate a range of ice-sheet geometries and calculate their likely contribution to sea level. In addition, we use these simulations to investigate the processes by which the West and East Antarctic ice sheets respond to environmental forcings and the timescales over which these behaviours manifest. We conclude that the Antarctic ice sheet contributed 8.6±2.8m to global sea level at this time, under an atmospheric CO2 concentration identical to present (400ppm). Warmer-than-present ocean temperatures led to the collapse of West Antarctica over centuries, whereas higher air temperatures initiated surface melting in parts of East Antarctica that over one to two millennia led to lowering of the ice-sheet surface, flotation of grounded margins in some areas, and retreat of the ice sheet into the Wilkes Subglacial Basin. The results show that regional variations in climate, ice-sheet geometry, and topography produce long-term sea-level contributions that are non-linear with respect to the applied forcings, and which under certain conditions exhibit threshold behaviour associated with behavioural tipping points

Belfast Without Sight: Exploring Geographies of Blindness

In this paper (he transformed spaces of visually impaired and blind people is explored through a detailed analysis of interview transcripts with twenty seven visually impaired people living in or around Belfast. Data were collected using a structured open-ended interview and were analysed within NUD-IST, a qualitative data analysis package. Analysis revealed that visually impaired people become spatially confused (e.g. lost or disorientated) for two primary reasons. "Self-produced" confusion is spatial confusion caused by the misperception/miscognition of a route (e.g. miscounting intersections). "Situational" confusion is spatial confusion caused by a permanent or temporary localised occurrences such as road works, vehicles parked on pavements, and street furniture. Both types of spatial confusion were found to induce feelings of fear and anxiety, leading to a loss of selfconfidence, embarrassment and frustration, which in turn led to less independent travel and exploration, and constrained patterns of spatial behaviour. Respondents detailed a number of strategies for coping with spatial confusion. In addition, they assessed methods to make Belfast more navigable including environmental modifications and orientation and mobility aid

Belfast Without Sight: Exploring Geographies of Blindness

In this paper (he transformed spaces of visually impaired and blind people is explored through a detailed analysis of interview transcripts with twenty seven visually impaired people living in or around Belfast. Data were collected using a structured open-ended interview and were analysed within NUD-IST, a qualitative data analysis package. Analysis revealed that visually impaired people become spatially confused (e.g. lost or disorientated) for two primary reasons. "Self-produced" confusion is spatial confusion caused by the misperception/miscognition of a route (e.g. miscounting intersections). "Situational" confusion is spatial confusion caused by a permanent or temporary localised occurrences such as road works, vehicles parked on pavements, and street furniture. Both types of spatial confusion were found to induce feelings of fear and anxiety, leading to a loss of selfconfidence, embarrassment and frustration, which in turn led to less independent travel and exploration, and constrained patterns of spatial behaviour. Respondents detailed a number of strategies for coping with spatial confusion. In addition, they assessed methods to make Belfast more navigable including environmental modifications and orientation and mobility aid

Deglacial grounding-line retreat in the Ross Embayment, Antarctica, controlled by ocean and atmosphere forcing

Modern observations appear to link warming oceanic conditions with Antarctic ice sheet grounding-line retreat. Yet, interpretations of past ice sheet retreat over the last deglaciation in the Ross Embayment, Antarctica’s largest catchment, differ considerably and imply either extremely high or very low sensitivity to environmental forcing. To investigate this, we perform regional ice sheet simulations using a wide range of atmosphere and ocean forcings. Constrained by marine and terrestrial geological data, these models predict earliest retreat in the central embayment and rapid terrestrial ice sheet thinning during the Early Holocene. We find that atmospheric conditions early in the deglacial period can enhance or diminish ice sheet sensitivity to rising ocean temperatures, thereby controlling the initial timing and spatial pattern of grounding-line retreat. Through the Holocene, however, grounding-line position is much more sensitive to subshelf melt rates, implicating ocean thermal forcing as the key driver of past ice sheet retreat

Basal conditions of two Transantarctic Mountains outlet glaciers from observation-constrained diagnostic modelling

This is the published version. Copyright 2014 International Glaciological SocietyWe present a diagnostic glacier flowline model parameterized and constrained by new velocity data from ice-surface GPS installations and speckle tracking of TerraSAR-X satellite images, newly acquired airborne-radar data, and continental gridded datasets of topography and geothermal heat flux, in order to better understand two outlet glaciers of the East Antarctic ice sheet. Our observational data are employed as primary inputs to a modelling procedure that first calculates the basal thermal regime of each glacier, then iterates the basal sliding coefficient and deformation rate parameter until the fit of simulated to observed surface velocities is optimized. We find that the two glaciers have both frozen and thawed areas at their beds, facilitating partial sliding. Glacier flow arises from a balance between sliding and deformation that fluctuates along the length of each glacier, with the amount of sliding typically varying by up to two orders of magnitude but with deformation rates far more constant. Beardmore Glacier is warmer and faster-flowing than Skelton Glacier, but an up-glacier deepening bed at the grounding line, coupled with ice thicknesses close to flotation, lead us to infer a greater vulnerability of Skelton Glacier to grounding-line recession if affected by ocean-forced thinning and concomitant acceleration

The Effect of Spatial Tasks on Visually Impaired Peoples' Wayfinding Abilities

Thirty-eight people with visual impairments learned a 483-meter novel route through a university campus in four groups: verbalization, modeling, pointing, and control. The performance of all four groups improved with greater experience of the route, but the modeling group improved more than did the control group

Association of computed tomographic leg muscle characteristics with lower limb and cardiovascular events in patients with peripheral artery disease

Background Poor lower extremity physical performance is an independent predictor of unfavorable outcome in patients with peripheral artery disease (PAD); however, few studies have assessed muscle characteristics on imaging directly. Method and Results A novel 3‐dimensional semi‐automated protocol was developed to estimate leg muscle volume and density (mean attenuation) from computed tomography images. Patients with PAD who underwent a lower extremity computed tomography scan at a tertiary vascular surgery center were included, and were followed up using hospital records and linked data as part of a retrospective cohort study. The primary outcomes were lower limb events (major amputation or peripheral revascularization) and cardiovascular events (myocardial infarction, stroke, or cardiovascular death). Two hundred and twenty‐three patients with PAD were included (median age 69.0 years; 73% men) and followed for a median of 4.9 [2.6–7.0] years. During this time there were 99 index lower limb events and 97 cardiovascular events. Low leg muscle density was associated with increased risk of lower limb (rate ratio 1.41 [1.11–1.80] per SD reduction) and cardiovascular events (rate ratio 1.60 [1.29–1.99] per SD reduction). Low muscle density remained an independent predictor of cardiovascular (but not lower limb) events, after adjusting for age, sex, traditional cardiovascular risk factors, and angiographic PAD severity (rate ratio 1.39 [1.09–1.77] per lower SD). In contrast, leg muscle volume was not associated with outcomes after adjusting for risk factors and PAD severity. Conclusions Low leg muscle density, but not volume, is a strong, independent predictor of major cardiovascular events among people with PAD. Further research is needed to understand the mechanisms underlying these associations