43 research outputs found
Quantification of Thoracic Aorta Blood Flow by Magnetic Resonance Imaging During Supine Cycling Exercise of Increasing Intensity
Poster presentation from the 16th Annual SCMR Scientific Sessions San Francisco, CA, USA. 31 January - 3 February 2013
Theoretical open-loop model of respiratory mechanics in the extremely preterm infant
Non-invasive ventilation is increasingly used for respiratory support in
preterm infants, and is associated with a lower risk of chronic lung disease.
However, this mode is often not successful in the extremely preterm infant in
part due to their markedly increased chest wall compliance that does not
provide enough structure against which the forces of inhalation can generate
sufficient pressure. To address the continued challenge of studying treatments
in this fragile population, we developed a nonlinear lumped-parameter model of
respiratory system mechanics of the extremely preterm infant that incorporates
nonlinear lung and chest wall compliances and lung volume parameters tuned to
this population. In particular we developed a novel empirical representation of
progressive volume loss based on compensatory alveolar pressure increase
resulting from collapsed alveoli. The model demonstrates increased rate of
volume loss related to high chest wall compliance, and simulates laryngeal
braking for elevation of end-expiratory lung volume and constant positive
airway pressure (CPAP). The model predicts that low chest wall compliance
(chest stiffening) in addition to laryngeal braking and CPAP enhance breathing
and delay lung volume loss. These results motivate future data collection
strategies and investigation into treatments for chest wall stiffening.Comment: 22 pages, 5 figure
Image-based Quantification of 3D Morphology for Bifurcations in the Left Coronary Artery: Application to Stent Design
Background
Improved strategies for stentâbased treatment of coronary artery disease at bifurcations require a greater understanding of artery morphology. Objective
We developed a workflow to quantify morphology in the left main coronary (LMCA), left anterior descending (LAD), and left circumflex (LCX) artery bifurcations. Methods
Computational models of each bifurcation were created for 55 patients using computed tomography images in 3D segmentation software. Metrics including crossâsectional area, length, eccentricity, taper, curvature, planarity, branching law parameters, and bifurcation angles were assessed using openâsources software and custom applications. Geometric characterization was performed by comparison of means, correlation, and linear discriminant analysis (LDA). Results
Differences between metrics suggest dedicated or multistent approaches should be tailored for each bifurcation. For example, the side branch of the LCX (i.e., obtuse marginal; OM) was longer than that of the LMCA (i.e., LCXprox) and LAD (i.e., first diagonal; D1). Bifurcation metrics for some locations (e.g., LMCA Finet ratio) provide results and confidence intervals agreeing with prior findings, while revised metric values are presented for others (e.g., LAD and LCX). LDA revealed several metrics that differentiate between artery locations (e.g., LMCA vs. D1, LMCA vs. OM, LADprox vs. D1, and LCXprox vs. D1). Conclusions
These results provide a foundation for elucidating common parameters from healthy coronary arteries and could be leveraged in the future for treating diseased arteries. Collectively the current results may ultimately be used for design iterations that improve outcomes following implantation of future dedicated bifurcation stents