Shape-Setting of Self-Expanding Nickel-Titanium Laser-Cut and Wire-Braided Stents to Introduce a Helical Ridge.

PURPOSE: Altered hemodynamics caused by the presence of an endovascular device may undermine the success of peripheral stenting procedures. Flow-enhanced stent designs are under investigation to recover physiological blood flow patterns in the treated artery and reduce long-term complications. However, flow-enhanced designs require the development of customised manufacturing processes that consider the complex behaviour of Nickel-Titanium (Ni-Ti). While the manufacturing routes of traditional self-expanding Ni-Ti stents are well-established, the process to introduce alternative stent designs is rarely reported in the literature, with much of this information (especially related to shape-setting step) being commercially sensitive and not reaching the public domain, as yet. METHODS: A reliable manufacturing method was developed and improved to induce a helical ridge onto laser-cut and wire-braided Nickel-Titanium self-expanding stents. The process consisted of fastening the stent into a custom-built fixture that provided the helical shape, which was followed by a shape-setting in air furnace and rapid quenching in cold water. The parameters employed for the shape-setting in air furnace were thoroughly explored, and their effects assessed in terms of the mechanical performance of the device, material transformation temperatures and surface finishing. RESULTS: Both stents were successfully imparted with a helical ridge and the optimal heat treatment parameters combination was found. The settings of 500 °C/30 min provided mechanical properties comparable with the original design, and transformation temperatures suitable for stenting applications (Af = 23.5 °C). Microscopy analysis confirmed that the manufacturing process did not alter the surface finishing. Deliverability testing showed the helical device could be loaded onto a catheter delivery system and deployed with full recovery of the expanded helical configuration. CONCLUSION: This demonstrates the feasibility of an additional heat treatment regime to allow for helical shape-setting of laser-cut and wire-braided devices that may be applied to further designs.

Vitamin D levels in Irish children with fractures: A prospective case-control study with 5 year follow-up.

INTRODUCTION: Twenty-five-hydroxy-vitamin D3 (25-OH-vit D) is a prohormone that is essential for normal calcium homeostasis and bone metabolism. Understanding its role is an important component of the proper care of the pediatric orthopaedic patient. The aim of this study was to determine whether children in Ireland with fractures have increased prevalence of 25-OH-Vit D deficiency compared with age matched controls and to ascertain the relationship between a low 25-OH-vit D level and the incidence of fractures in Irish children. We hypothesised that children presenting to our centre following a fracture would have significantly lower 25-OH-vit D. METHODS: A prospective case-control study at a large urban tertiary referral academic hospital located in Dublin, Ireland was completed over a 14 month period from June 2014 to August 2015. A total of 116 subjects, distributed as cases (n = 58) and controls (n = 58) were included in this study. Whole blood (10 ml) was taken in two serum bottles from each patient. Serum 25-hydroxy-vitamin D3 levels were measured. An age matched control group was generated from other children attending the hospital, who also had vitamin D levels measured for different clinical reasons. We followed up both the fracture and control group for the next 5 years to assess the repeat fracture rate. RESULTS: Fifty-eight patients with a fracture requiring operative intervention, were included in the study. Statistical analysis was performed comparing to 58 age and sex-matched controls. The mean vitamin D level for the fracture group was 63.2 nmol/L (SD = 27.3), which was higher than the mean of the controls (62.5 nmol/L) (SD = 21.3) (p = 0.86), but this difference was found not to be statistically significant in unadjusted analysis. There was no statistically significant difference in the number of patients classified with low serum Vitamin D levels (<50 nmolL), with the fracture group consisting of 22 (37.9%) patients, and the control group of 17 patients (29.3%) (p = 0.33) with a level below 50 nmol/L. At five-year follow-up, 11 of the 58 patients (18.9%) in the fracture group went on to have a further fracture compared with eight patients (13.7%) from the control group. Out of these 11 from the fracture group five (45.45%) had been found to have a low serum 25-OH-Vit D level five years previously. Out of the eight controls that presented with a fracture within the five-year period, 3 (37.5%) had had a low vitamin D level at the origin of this study. CONCLUSION: The results of this study show that children presenting to our institution with low energy fractures have a prevalence of 38% 25-hydroxy-vitamin D deficiency. This study included children from age 1 to 16 primarily Caucasian encompassing all fracture types resulting from accidental trauma. Our findings suggest that in an Irish pediatric population vitamin D status may impact fracture risk with more than one-third being deficient in this review.

A randomised controlled trial of calcium channel blockade (CCB) with Amlodipine For the treatment oF subcortical ischaEmic vasCular demenTia (AFFECT): study protocol.

BACKGROUND: Vascular dementia is the second most common cause of dementia affecting over seven million people worldwide, yet there are no licensed treatments. There is an urgent need for a clinical trial in this patient group. Subcortical ischaemic vascular dementia is the most common variant of vascular dementia. This randomised trial will investigate whether use of calcium channel blockade with amlodipine, a commonly used agent, can provide the first evidence-based pharmacological treatment for subcortical ischaemic vascular dementia. METHODS/DESIGN: This is a randomised controlled trial of calcium channel blockade with Amlodipine For the treatment oF subcortical ischaEmic vasCular demenTia (AFFECT) to test the hypothesis that treatment with amlodipine can improve outcomes for these patients in a phase IIb, multi-centre, double-blind, placebo-controlled randomised trial. The primary outcome is the change from baseline to 12 months in the Vascular Dementia Assessment Scale cognitive subscale (VADAS-cog). Secondary outcomes include cognitive function, executive function, clinical global impression of change, change in blood pressure, quantitative evaluation of lesion accrual based on magnetic resonance imaging (MRI), health-related quality of life, activities of daily living, non-cognitive dementia symptoms, care-giver burden and care-giver health-related quality of life, cost-effectiveness and institutionalisation. A total of 588 patients will be randomised in a 1:1 ratio to either amlodipine or placebo, recruited from sites across the UK and enrolled in the trial for 104 weeks. DISCUSSION: There are no treatments licensed for vascular dementia. The most common subtype is subcortical ischaemic vascular dementia (SIVD). This study is designed to investigate whether amlodipine can produce benefits compared to placebo in established SIVD. It is estimated that the numbers of people with VaD and SIVD will increase globally in the future and the results of this study should inform important treatment decisions. TRIAL REGISTRATION: Current Controlled Trials ISRCTN31208535 . Registered on 7 March 2014.

Hippocampal volume is an independent predictor of cognitive performance in CADASIL.

Recent evidence suggests that hippocampal changes are present in vascular cognitive impairment but their importance and relationship with ischaemic mechanisms remain controversial. To investigate these issues we performed MRI and cognitive assessment in a large cohort (n=144) of patients with CADASIL, a hereditary small vessel disease and model of pure vascular cognitive impairment. Dementia status was ascribed according to DSM-IV and global cognitive function assessed with the Minimental State Examination (MMSE) and Mattis Dementia Rating Scale (MDRS). Hippocampal volume (HV) correlated with age (r=-0.33, p<0.001), brain volume (r=0.39, p<0.001) and lacunar lesion volume (r=-0.23, p=0.008), but not white matter lesions or microhaemorrhages. HV was reduced in dementia (2272+/-333 mm(3) versus 2642+/-349 mm(3), p<0.001) in the whole cohort and the subgroup progressing to dementia before age 60. HV correlated with MMSE (r=0.30, p<0.001), MDRS (r=0.40, p<0.001) and in a multivariate model predicted cognition independent of typical vascular lesions and whole brain atrophy. These findings strengthen the view that hippocampal atrophy is an important pathway of cognitive impairment in vascular as well as degenerative disease.

Measurement of brain atrophy in subcortical vascular disease: a comparison of different approaches and the impact of ischaemic lesions.

Measurement of brain atrophy has been proposed as a surrogate marker in MS and degenerative dementias. Although cerebral small vessel disease predominantly affects white and subcortical grey matter, recent data suggest that whole brain atrophy is also a good indicator of clinical and cognitive status in this disease. Automated methods to measure atrophy are available that are accurate and reproducible in disease-free brains. However, optimal methods in small vessel disease have not been established and the impact of ischaemic lesions on different techniques has not been explored systematically. In this study, three contrasting techniques -- Statistical Parametric Mapping 5 (SPM5), SIENAX and BrainVisa -- were applied to measure cross-sectional atrophy (brain parenchymal fraction or BPF) in a large (n=143) two-centre cohort of patients with CADASIL, a genetic model of small vessel disease. All three techniques showed similar sensitivity to trends in BPF associated with age and lesion load. No single technique was particularly vulnerable to error as a result of lesions. Provided major errors in registration were excluded by visual inspection, manual correction of segmentations had a negligible impact with mean errors of 0.41% for SIENAX and 0.46% for BrainVisa. BPF correlated strongly with global cognitive function and physical disability, independent of the technique used. Correlation coefficients with the Minimental State Examination score were: BrainVisa 0.58, SIENAX 0.58, SPM5 0.60 (for all, p<0.001). These results suggest that all three methods can be applied reliably in patients with ischaemic lesions. Choice of analysis approach for this kind of clinical question will be determined by factors other than their robustness and precision, such as a desire to explore subtle localised changes using extensions of these processing tools.

Cortical changes in cerebral small vessel diseases: a 3D MRI study of cortical morphology in CADASIL.

Brain atrophy represents a key marker of disease progression in cerebrovascular disorders. The 3D changes of cortex morphology occurring during the course of small vessel diseases of the brain (SVDB) remain poorly understood. The objective of this study was to assess the changes affecting depth and surface area of cortical sulci and their clinical and radiological correlates in a cohort of patients with cerebral autosomal dominant arteriolopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a genetic SVDB. Data were obtained from a series of 69 CADASIL patients. Validated methods were used to determine depth and surface area of four cortical sulci. The ratio of brain to intracranial cavity volumes (brain parenchymal fraction--BPF), volume of lacunar lesions (LL) and of white matter hyperintensities, number of cerebral microhaemorrhages, and mean apparent diffusion coefficient were also measured. Association between depth and surface area of the cortical sulci and BPF, clinical status and subcortical MRI lesions were tested. Depth and surface area of cortical sulci obtained in 54 patients were strongly correlated with both cognitive score and disability scales. Depth was related to the extent of subcortical lesions, surface area was related only to age. In additional analyses, the depth of the cingular sulcus was independently associated with the volume of LL (P = 0.001), and that of the superior frontal sulcus with the mean apparent diffusion coefficient (P = 0.003). In CADASIL, important morphological changes of cortical sulci occur in association with clinical worsening, extension of subcortical tissue damage and progression of global cerebral atrophy. These results suggest that the examination of cortical morphology may be of high clinical relevance in SVDB.

Leukoaraiosis.

Leukoaraiosis describes diffuse white matter abnormalities on CT or MR brain scans, often seen in the normal elderly and in association with vascular risk factors such as hypertension, or in the context of cognitive impairment. The term was introduced to avoid confusing an imaging appearance with a specific pathology. Neurologists often come across this appearance, but its significance is sometimes uncertain. The effects on cognitive function and gait are insidious and can be difficult to detect at the bedside, but are nevertheless important. However, gradually it is becoming clearer how leukoaraiosis relates to cerebrovascular disease, Alzheimer's and other diseases, and how this appearance should influence treatment decisions.

Brain atrophy is related to lacunar lesions and tissue microstructural changes in CADASIL.

BACKGROUND AND PURPOSE: Cerebral atrophy has been recently recognized as a key marker of disease progression in cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). The contribution of subcortical cerebral lesions in this process remains undetermined. The aim of this study was to investigate the relationships between cerebral volume and different types of subcortical MRI lesions in CADASIL. METHODS: Demographic, clinical, and laboratory data from 147 patients with CADASIL recruited from a prospective cohort study were analyzed. Validated methods were used to determine the ratio of brain volume to intracranial cavity volume (brain parenchymal fraction [BPF]), volume of white matter hyperintensities, volume of lacunar lesions, number of cerebral microhemorrhages, and mean apparent diffusion coefficient. Associations between BPF, clinical scales, and the different subcortical MRI markers were tested. RESULTS: BPF obtained in 129 patients was significantly associated with the Mattis dementia rating scale (P<0.0001), Mini-Mental State Examination (P=0.002), and modified Rankin scale (P<0.0001) after adjustment for age and sex. Multiple linear regression modeling showed that BPF was independently associated with mean apparent diffusion coefficient (P<0.0001), volume of lacunar lesions (P=0.004), and age (P<0.0001), accounting for 46% of the observed variance in BPF but not with volume of white matter hyperintensities or number of microhemorrhages. CONCLUSIONS: In association with age, mean apparent diffusion coefficient and volume of lacunar lesions are strong and independent MRI predictors of BPF, a key marker of cognitive and motor disability in CADASIL. These results suggest brain atrophy is related to remote and/or diffuse consequences of both lacunar lesions and widespread microstructural alterations within the brain outside lacunar lesions.