Libin Cardiovascular Institute of Alberta

About: Libin Cardiovascular Institute of Alberta is a facility organization based out in Calgary, Alberta, Canada. It is known for research contribution in the topics: Population & Atrial fibrillation. The organization has 758 authors who have published 1459 publications receiving 44418 citations.

Convolutional neural network-based approach for segmentation of left ventricle myocardial scar from 3D late gadolinium enhancement MR images

Abstract: Purpose Accurate three-dimensional (3D) segmentation of myocardial replacement fibrosis (i.e., scar) is emerging as a potentially valuable tool for risk stratification and procedural planning in patients with ischemic cardiomyopathy. The main purpose of this study was to develop a semiautomated method using a 3D convolutional neural network (CNN)-based for the segmentation of left ventricle (LV) myocardial scar from 3D late gadolinium enhancement magnetic resonance (LGE-MR) images. Methods Our proposed CNN is built upon several convolutional and pooling layers aimed at choosing appropriate features from LGE-MR images to distinguish between myocardial scar and healthy tissues of the left ventricle. In contrast to previous methods that consider image intensity as the sole feature, CNN-based algorithms have the potential to improve the accuracy of scar segmentation through the creation of unconventional features that separate scar from normal myocardium in the feature space. The first step of our pipeline was to manually delineate the left ventricular myocardium, which was used as the region of interest for scar segmentation. Our developed algorithm was trained using 265,220 volume patches extracted from ten 3D LGE-MR images, then was validated on 450,454 patches from a testing dataset of 24 3D LGE-MR images, all obtained from patients with chronic myocardial infarction. We evaluated our method in the context of several alternative methods by comparing algorithm-generated segmentations to manual delineations performed by experts. Results Our CNN-based method reported an average Dice similarity coefficient (DSC) and Jaccard Index (JI) of 93.63% ± 2.6% and 88.13% ± 4.70%. In comparison to several previous methods, including K-nearest neighbor (KNN), hierarchical max flow (HMF), full width at half maximum (FWHM), and signal threshold to reference mean (STRM), the developed algorithm reported significantly higher accuracy for DSC with a P-value less than 0.0001. Conclusions Our experimental results demonstrated that our CNN-based proposed method yielded the highest accuracy of all contemporary LV myocardial scar segmentation methodologies, inclusive of the most widely used signal intensity-based methods, such as FWHM and STRM. To our knowledge, this is the first description of LV myocardial scar tissue segmentation from 3D LGE-MR images using a CNN-based method.

Losartan abolishes oxidative stress induced by intermittent hypoxia in humans

Abstract: The aim of this study was to assess the role of the type 1 angiotensin II (AT(1)) receptor in the increase of oxidative stress and NO metabolism during a single 6 h exposure to intermittent hypoxia (IH). Nine healthy young men were exposed, while awake, to sham IH, IH with placebo medication, and IH with the AT(1) receptor antagonist, losartan, using a double-blind, placebo-controlled, randomized, crossover study design. In addition to blood pressure, oxidative stress, peroxynitrite activity, uric acid, global antioxidant status and the end-products of NO (NOx) metabolism were measured in plasma before and after 6 h of IH. Oxidative stress and peroxynitrite activity increased and NOx decreased during IH with placebo. In contrast, neither sham IH nor IH with losartan affected these parameters. With respect to each condition, blood pressure had the same profile as oxidative stress. These results demonstrate that blockade of AT(1) receptors prevented the increase in oxidative stress and peroxynitrite activity and the decrease in NO metabolism induced by IH. Finally, this study suggests that the renin-angiotensin system may participate in the overproduction of reactive oxygen species associated with IH by upregulation of the actions of angiotensin II.

Fixed-dose combination pharmacologic therapy to improve hypertension control worldwide: Clinical perspective and policy implications

Abstract: 1University of South Carolina School of Medicine, University of South Carolina, Columbia, South Carolina 2Palmetto Health, Columbia, South Carolina 3Department of Medicine, Physiology and Pharmacology and Community Health Sciences, O’Brien Institute for Public Health and Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada 4FOSCAL, UDES, Bucaramanga, Colombia 5Eugenio Espejo Medical Sciences Faculty, UTE, Quito, Ecuador 6Arnhold Institute for Global Health, Icahn School of Medicine at Mount Sinai, New York, New York 7Young Professionals Chronic Disease Network, New York, New York 8Resolve to Save Lives, New York, New York 9Kaiser Permanente South, San Francisco Medical Center South, San Francisco, California 10University of Barcelona, Barcelona, Spain 11Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 12Department of Non‐Communicable Diseases and Mental Health, The Pan‐American Health Organization, Washington, District of Columbia