Aims: Wall shear stress (WSS) may induce local remodeling of the vascular wall and the WSS pattern in turn depends on vascular geometry. We aimed to elucidate the impact of side-branches on local WSS.
Methods And Results: Steady numerical flow simulation studies were performed in three-dimensional reconstructed right coronary artery (RCA) trees. RCA from seven controls, five patients with coronary artery disease (CAD) and five patients with aneurysmatic CAD (AnCAD) classified by expert visual diagnosis were studied. Then three transient flow simulations were performed with cases representative for each group in order to evaluate the impact of pulsatile flow simulation. As vascular size and flow rates vary considerably between patients, non-dimensional approaches were applied for group comparison. A point-to-point comparison of the WSS in the same tree with and without side-branches revealed local differences in WSS of up to 12.0 Pa. This was caused by a reduction of volume flow of up to 78.7% in the trunk. Differences are not only limited to bifurcation sites but also affect local narrowings and strongly curved segments. The point-to-point comparison of steady and transient simulations found an average increase of WSS of below 7% in transient simulations. No significant differences were found between histograms of pulsatile and steady simulations, showing a high cross-correlation of >0.97.
Conclusion: Side-branches must not be neglected in numerical flow simulation (steady and transient) studies. Steady simulations are valid for an assessment of time-averaged WSS distributions.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1016/j.atherosclerosis.2010.09.007 | DOI Listing |
Cardiovasc Eng Technol
January 2025
Department of Cardiac Surgery, Heidelberg University Hospital, Heidelberg, Germany.
The flow convergence method includes calculation of the proximal isovelocity surface area (PISA) and is widely used to classify mitral regurgitation (MR) with echocardiography. It constitutes a primary decision factor for determination of treatment and should therefore be a robust quantification method. However, it is known for its tendency to underestimate MR and its dependence on user expertise.
View Article and Find Full Text PDFSci Rep
January 2025
College of Petroleum Engineering, Liaoning Petrochemical University, Fushun, China.
The laminae of varying lithologies are characteristic of shale oil reservoirs, with their pronounced heterogeneity and fluid-solid coupling significantly impacting oil productivity. To this end, this study initially quantified the permeability and mechanical heterogeneity in lamina-developed shale through permeability tests and quasi triaxial mechanical experiments on shale cores from different orientations in the Jiyang Depression. These tests revealed marked brittleness in horizontally oriented cores and elasticity in vertically oriented cores.
View Article and Find Full Text PDFCardiovasc Eng Technol
January 2025
School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut Street, Rm. 718, Philadelphia, PA, 19104, USA.
Purpose: Computational models of the cardiovascular system continue to increase in complexity. As more elements of the physiology are captured in multiscale models, there is a need to efficiently integrate subsystems. The objective of this study is to demonstrate the effectiveness of a coupling methodology, called functional mock-up interface (FMI), as applied to multiscale cardiovascular modeling.
View Article and Find Full Text PDFNeurogenetics
January 2025
Department of Biochemistry, College of Medicine, University of Lagos, Lagos State, Nigeria.
Schizophrenia (SZ) is a complex, chronic mental disorder characterized by positive symptoms (such as delusions and hallucinations), negative symptoms (including anhedonia, alogia, avolition, and social withdrawal), and cognitive deficits (affecting attention, processing speed, verbal and visuospatial learning, problem-solving, working memory, and mental flexibility). Extensive animal and clinical studies have emphasized the NMDAR hypofunction hypothesis of SZ. Glycine plays a crucial role as an agonist of NMDAR, enhancing the receptor's affinity for glutamate and supporting normal synaptic function and plasticity, that is, signal transmission between neurons.
View Article and Find Full Text PDFSci Rep
January 2025
Institute of Sustainable Energy, Universiti Tenaga Nasional, Jalan IKRAM-UNITEN, Kajang, 43000, Selangor, Malaysia.
The microgrid (MG) faces significant security issues due to the two-way power and information flow. Integrating an Energy Management System (EMS) to balance energy supply and demand in Malaysian microgrids, this study designs a Fuzzy Logic Controller (FLC) that considers intermittent renewable sources and fluctuating demand patterns. FLC offers a flexible solution to energy scheduling effectively assessed by MATLAB/Simulink simulations.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!