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Pingsha Dong - One of the best experts on this subject based on the ideXlab platform.
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evaluation of magnesium weldment fatigue data using traction and notch Stress methods
International Journal of Fatigue, 2020Co-Authors: Wenqing Zhou, Pingsha Dong, Xianjun Pei, Ozler KarakasAbstract:Abstract Recent magnesium weldment fatigue test data (Karakas et al., 2008), which involve partial- and full-penetration butt welds, as well as non-load carrying fillet welds, have been analyzed using both traction Structural Stress and equivalent notch Stress methods. Both methods were compared for their effectiveness in correlating the test data by incorporating fracture mechanics-based load ratio parameters and was successfully used in conjunction with the load ratio parameter. Furthermore, the equivalent traction Stress parameter, once converted into an equivalent Structural strain parameter, enables comparison between magnesium weldment test data with the master S-N curve scatter band adopted in ASME Div. 2.
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a spectral fatigue method incorporating non proportional multiaxial loading
International Journal of Fatigue, 2020Co-Authors: Sandipp Krishnan Ravi, Pingsha DongAbstract:Abstract A frequency domain method incorporating multiaxial non-proportional loading conditions is presented in this paper. The non-proportionality is modelled by implementing a multiaxial cycle counting procedure of path dependent maximum range\moment of load path proposed recently by Mei and Dong (2016) in frequency domain through a formulation of an effective equivalent Structural Stress (EESS) transfer function. Additionally, the formulation through transfer functions and the treatment of phase differences between normal and shear Stresses represents a unique approach to multiaxial fatigue analysis in frequency domain. The numerous test studies performed on a representative Structural detail in marine structure showed rather promising results. Reasonable multiaxial fatigue damage estimations have been obtained through the developed method by comparing the fatigue damages computed with time domain methods.
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analysis of fatigue behavior of welded joints in orthotropic bridge deck using traction Structural Stress
Advances in Mechanical Engineering, 2019Co-Authors: Haibo Yang, Hongliang Qian, Ping Wang, Pingsha DongAbstract:In this study, the fatigue behavior of welded joints in an orthotropic steel bridge is simulated and analyzed. The traction Structural Stress method is proven to be more accurate and effective, and...
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traction Structural Stress analysis of fatigue behaviors of rib to deck joints in orthotropic bridge deck
International Journal of Fatigue, 2019Co-Authors: Pingsha Dong, Ping Wang, Shaopin SongAbstract:Abstract In this study, a traction Stress method is adopted for analyzing some of the unique fatigue behaviors observed in a series of recent experimental studies on rib-to-deck joints in orthotropic steel bridge decks. It is found that the traction-based Structural Stress definition is not only effective for describing the relevant Stress state responsible for each of the four fatigue failure modes, but also mesh-insensitive in finite element computation. The latter attribute is essential for achieving a reliable evaluation of the most likely failure mode possible out of four typical failure modes for a given joint design (including exact weld dimensions) under specified loading conditions. As such, effective means of avoiding undesirable failure mode, e.g., Type 4 (i.e., weld root cracking), can be examined, e.g., by increasing either weld fillet size and/or weld penetration. Furthermore, the rib-to-deck joint fatigue test data investigated in this study are shown falling within the scatter band of the traction Stress based master S-N curve adopted by ASME Div Code since 2007, implying that data transferability exists among these three sets of test data obtained independently by different laboratories.
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analysis methods of the dynamic Structural Stress in a full scale welded carbody for high speed trains
Advances in Mechanical Engineering, 2018Co-Authors: Heyan Zheng, Tianli Chen, Jing Zeng, Pingsha DongAbstract:The calculation of the dynamic Stress of a large and complex welded carbody is the key to the fatigue design and the durability evaluation of the carbody. Adopting the advanced Structural Stress ba...
Zhongzhao Teng - One of the best experts on this subject based on the ideXlab platform.
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impact of combined plaque Structural Stress and wall shear Stress on coronary plaque progression regression and changes in composition
European Heart Journal, 2019Co-Authors: Charis Costopoulos, Lucas H Timmins, Yuan Huang, Olivia Y Hung, David Molony, Adam J Brown, Emily L Davis, Zhongzhao TengAbstract:AIMS The focal distribution of atherosclerotic plaques suggests that local biomechanical factors may influence plaque development. METHODS AND RESULTS We studied 40 patients at baseline and over 12 months by virtual-histology intravascular ultrasound and bi-plane coronary angiography. We calculated plaque Structural Stress (PSS), defined as the mean of the maximum principal Stress at the peri-luminal region, and wall shear Stress (WSS), defined as the parallel frictional force exerted by blood flow on the endothelial surface, in areas undergoing progression or regression. Changes in plaque area, plaque burden (PB), necrotic core (NC), fibrous tissue (FT), fibrofatty tissue, and dense calcium were calculated for each co-registered frame. A total of 4029 co-registered frames were generated. In areas with progression, high PSS was associated with larger increases in NC and small increases in FT vs. low PSS (difference in ΔNC: 0.24 ± 0.06 mm2; P < 0.0001, difference in ΔFT: -0.15 ± 0.08 mm2; P = 0.049). In areas with regression, high PSS was associated with increased NC and decreased FT (difference in ΔNC: 0.15 ± 0.04; P = 0.0005, difference in ΔFT: -0.31 ± 0.06 mm2; P < 0.0001). Low WSS was associated with increased PB vs. high WSS in areas with progression (difference in ΔPB: 3.3 ± 0.4%; P < 0.001) with a similar pattern observed in areas with regression (difference in ΔPB: 1.2 ± 0.4%; P = 0.004). Plaque Structural Stress and WSS were largely independent of each other (R2 = 0.002; P = 0.001). CONCLUSION Areas with high PSS are associated with compositional changes consistent with increased plaque vulnerability. Areas with low WSS are associated with more plaque growth in areas that progress and less plaque loss in areas that regress. The interplay of PSS and WSS may govern important changes in plaque size and composition.
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impact of combined plaque Structural Stress and wall shear Stress on coronary plaque progression regression and changes in composition
European Heart Journal, 2019Co-Authors: Charis Costopoulos, Lucas H Timmins, Yuan Huang, Olivia Y Hung, David Molony, Adam J Brown, Emily L Davis, Zhongzhao TengAbstract:Open in a separate window Aims The focal distribution of atherosclerotic plaques suggests that local biomechanical factors may influence plaque development.
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plaque rupture in coronary atherosclerosis is associated with increased plaque Structural Stress
Jacc-cardiovascular Imaging, 2017Co-Authors: Charis Costopoulos, Zhongzhao Teng, Yuan Huang, Adam J Brown, Patrick A Calvert, Stephen P Hoole, Nick E J West, Jonathan H Gillard, Martin R BennettAbstract:Abstract Objectives The aim of this study was to identify the determinants of plaque Structural Stress (PSS) and the relationship between PSS and plaques with rupture. Background Plaque rupture is the most common cause of myocardial infarction, occurring particularly in higher risk lesions such as fibroatheromas. However, prospective intravascular ultrasound–virtual histology studies indicate that Methods We analyzed plaque structure and composition in 4,053 virtual histology intravascular ultrasound frames from 32 fibroatheromas with rupture from the intravascular ultrasound–virtual histology in Vulnerable Atherosclerosis study and 32 fibroatheromas without rupture on optical coherence tomography from a stable angina cohort. Mechanical loading in the periluminal region was estimated by calculating maximum principal PSS by finite element analysis. Results PSS increased with increasing lumen area (r = 0.46; p = 0.001), lumen eccentricity (r = 0.32; p = 0.001), and necrotic core ≥10% (r = 0.12; p = 0.001), but reduced when dense calcium was ≥10% (r = −0.12; p = 0.001). Ruptured fibroatheromas showed higher PSS (133 kPa [quartiles 1 to 3: 90 to 191 kPa] vs. 104 kPa [quartiles 1 to 3: 75 to 142 kPa]; p = 0.002) and variation in PSS (55 kPa [quartiles 1 to 3: 37 to 75 kPa] vs. 43 kPa [quartiles 1 to 3: 34 to 59 kPa]; p = 0.002) than nonruptured fibroatheromas, with rupture primarily occurring either proximal or immediately adjacent to the minimal luminal area (87.5% vs. 12.5%; p = 0.001). PSS was higher in segments proximal to the rupture site (143 kPa [quartiles 1 to 3: 101 to 200 kPa] vs. 120 kPa [quartiles 1 to 3: 78 to 180 kPa]; p = 0.001) versus distal segments, associated with increased necrotic core (19.1% [quartiles 1 to 3: 11% to 29%] vs. 14.3% [quartiles 1 to 3: 8% to 23%]; p = 0.001) but reduced fibrous/fibrofatty tissue (63.6% [quartiles 1 to 3: 46% to 78%] vs. 72.7% [quartiles 1 to 3: 54% to 86%]; p = 0.001). PSS >135 kPa was a good predictor of rupture in higher risk regions. Conclusions PSS is determined by plaque composition, plaque architecture, and lumen geometry. PSS and PSS variability are increased in plaques with rupture, particularly at proximal segments. Incorporating PSS into plaque assessment may improve identification of rupture-prone plaques.
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tct 598 plaque rupture in coronary atherosclerosis is associated with increased plaque Structural Stress
Journal of the American College of Cardiology, 2016Co-Authors: Charis Costopoulos, Zhongzhao Teng, Yuan Huang, Adam J Brown, Patrick A Calvert, Stephen P Hoole, Nick E J West, Jonathan H Gillard, Martin R BennettAbstract:Plaque rupture is the commonest cause of myocardial infarction, occurring particularly in higher-risk lesions such as fibroatheromas. However, prospective virtual-histology intravascular ultrasound (VH-IVUS) studies indicate that <10% higher-risk plaques cause clinical events over 3-years,
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coronary plaque Structural Stress is associated with plaque composition and subtype and higher in acute coronary syndrome the beacon i biomechanical evaluation of atheromatous coronary arteries study
Circulation-cardiovascular Imaging, 2014Co-Authors: Zhongzhao Teng, Yuan Huang, Adam J Brown, Patrick A Calvert, Richard A Parker, Daniel R Obaid, Stephen P Hoole, Nick E J West, Jonathan H Gillard, Martin R BennettAbstract:Background— Atherosclerotic plaques underlying most myocardial infarctions have thin fibrous caps and large necrotic cores; however, these features alone do not reliably identify plaques that rupture. Rupture occurs when plaque Structural Stress (PSS) exceeds mechanical strength. We examined whether PSS could be calculated in vivo based on virtual histology (VH) intravascular ultrasound and whether PSS varied according to plaque composition, subtype, or clinical presentation. Methods and Results— A total of 4429 VH intravascular ultrasound frames from 53 patients were analyzed, identifying 99 584 individual plaque components. PSS was calculated by finite element analysis in whole vessels, in individual plaques, and in higher-risk regions (plaque burden ≥70%, mean luminal area ≤4 mm 2 , noncalcified VH-defined thin-cap fibroatheroma). Plaque components including total area/arc of calcification ( R 2 =0.33; P R 2 =0.28; P R 2 =0.18; P R 2 =0.15; P P =0.002). PSS was also higher in patients with an acute coronary syndrome, where mean luminal area ≤4 mm 2 (8.24 [7.06–9.93] versus 7.72 [6.33–9.34]; P =0.03), plaque burden ≥70% (9.18 [7.44–10.88] versus 7.93 [6.16–9.46]; P =0.02), and in noncalcified VH-defined thin-cap fibroatheroma (9.23 [7.33–11.44] versus 7.65 [6.45–8.62]; P =0.02). Finally, PSS increased the positive predictive value for VH intravascular ultrasound to identify clinical presentation. Conclusions— Finite element analysis modeling demonstrates that Structural Stress is highly variable within plaques, with increased PSS associated with plaque composition, subtype, and higher-risk regions in patients with acute coronary syndrome. PSS may represent a novel tool to analyze the dynamic behavior of coronary plaques with the potential to improve prediction of plaque rupture.
Hong Tae Kang - One of the best experts on this subject based on the ideXlab platform.
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Fatigue life prediction of spot-welded joints with a notch Stress approach
Theoretical and Applied Fracture Mechanics, 2020Co-Authors: Changjian Wei, Hong Tae KangAbstract:Abstract Spot-welded joints are widely used in the construction of vehicle structures and frequently become critical locations for fatigue failure. Hence, it is essential to have reliable fatigue life prediction method for the spot-welded joints during vehicle structure design. In this paper, a new notch Stress approach is developed for fatigue life prediction of the spot-welded joints. Currently, Structural Stress methods are widely used in automotive industry for fatigue life prediction of spot-welded joints. However, these methods are not well considering local geometry information. This paper introduces a notch Stress based method to overcome the limitation of the Structural Stress methods. In the notch Stress method, Stress concentration factors for spot-welded joints are calculated from Stress intensity factor equations. Then, the notch Stress method is validated with fatigue test results of lap-shear and coach peel specimens.
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fatigue analysis of spot welds using a mesh insensitive Structural Stress approach
International Journal of Fatigue, 2007Co-Authors: Hong Tae Kang, Pingsha Dong, J K HongAbstract:Abstract This paper describes the application procedures of a nodal force based mesh-insensitive Structural Stress parameter for analysis of a comprehensive set of spot weld fatigue test data collected from a series of advanced high strength sheet steels. The Structural Stress parameter is calculated in an equilibrium sense in terms of bending and membrane components from nodal forces and moments at each grid point along the periphery of a weld nugget. Based on fracture mechanics considerations, an equivalent Structural Stress parameter is then used to take into account the effects of loading mode and sheet thickness on the fatigue of spot welded joints. The equivalent Structural Stress is proven effective in consolidating the large amount of fatigue data of spot welds for transformation induced plasticity (TRIP), dual-phase (DP), and high strength low alloy (HSLA) steels subjected to both tensile shear and coach peel loadings. As a result, a single master S–N can be established for fatigue design and life prediction of spot-welded structures.
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Fatigue prediction of spot welded joints using equivalent Structural Stress
Materials & Design, 2007Co-Authors: Hong Tae KangAbstract:The author proposes a fatigue prediction method for spot welded joints in automotive body structures using an equivalent Structural Stress at the edge of spot welds. The proposed fatigue prediction method is developed by substituting the Stress components in von Mises equation to the local Structural Stresses at the vicinity of spot weld. The Structural Stresses at the edges of the weld nugget in each sheet are calculated using the forces and moments that are determined by finite element analysis. The equivalent Structural Stresses are correlated to experimental fatigue data to predict fatigue life of the spot welded joints. The proposed method is evaluated with two different experimental fatigue data of spot welds and shown good correlation with fatigue test results.
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fatigue damage parameter of spot welded joints under proportional loading
International Journal of Automotive Technology, 2005Co-Authors: Hong Tae KangAbstract:In this paper, the author proposes a fatigue damage parameter of spot welded joints under proportional loading. The proposed fatigue damage parameter is developed based on von Mises’ equivalent Stress and local Structural Stress at the edge of spot weld nugget. The Structural Stress at the edges of the weld nugget in each sheet is calculated using the forces and moments that are determined by finite element analysis. A Structural equivalent Stress is then calculated by von Mises’ equivalent Stress equation. The Structural equivalent Stresses are correlated to experimental fatigue life of the spot welded joints. The proposed parameter is evaluated with fatigue test data of spot welds subjected to multiaxial and tensile-shear loads. Sheppard’s parameter and Rupp and co-workers’ parameter are also evaluated with the same test data to compare with the author’s parameter. This proposed parameter presents a better correlation with experimental fatigue data than those of Sheppard’s and Rupp and co-workers’ parameter. The proposed parameter should be very effective for durability calculations during the early design phase since coarsely meshed finite element models can be employed.
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evaluation of multiaxial spot weld fatigue parameters for proportional loading
International Journal of Fatigue, 2000Co-Authors: Hong Tae Kang, Mark E Barkey, Yung-li LeeAbstract:Abstract The authors have conducted set of experiments to study the effects of combined tension and shear loads on the fatigue life of spot welded joints. The fatigue life of the specimens depended on the applied load amplitude, the ratio of shear to normal loading, and spot weld nugget diameter. The lower load amplitudes had longer fatigue lives, as did the cases which contained a higher amount of shear loading and specimens with a larger nugget diameter. Based on the test results, Swellam and co-workers' model, Sheppard's model, Rupp and co-workers' model, and an interpolation/extrapolation model are evaluated. The four approaches were correlated with the experimental fatigue life for the multiaxial test results with reasonable accuracy. The success of Swellam and co-workers' method relies heavily on determining the appropriate parameters β and b 0 . Sheppard's Structural Stress method agreed reasonably well for mutiaxial test results, although the maximum Structural Stress range is sensitive to the variation of the sheet thickness, and the determination of Δ M * is a complex procedure. Rupp and co-workers' method is suitable for application to large Structural models because mesh refinement is not necessary for modeling the spot weld connection.
Martin R Bennett - One of the best experts on this subject based on the ideXlab platform.
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plaque rupture in coronary atherosclerosis is associated with increased plaque Structural Stress
Jacc-cardiovascular Imaging, 2017Co-Authors: Charis Costopoulos, Zhongzhao Teng, Yuan Huang, Adam J Brown, Patrick A Calvert, Stephen P Hoole, Nick E J West, Jonathan H Gillard, Martin R BennettAbstract:Abstract Objectives The aim of this study was to identify the determinants of plaque Structural Stress (PSS) and the relationship between PSS and plaques with rupture. Background Plaque rupture is the most common cause of myocardial infarction, occurring particularly in higher risk lesions such as fibroatheromas. However, prospective intravascular ultrasound–virtual histology studies indicate that Methods We analyzed plaque structure and composition in 4,053 virtual histology intravascular ultrasound frames from 32 fibroatheromas with rupture from the intravascular ultrasound–virtual histology in Vulnerable Atherosclerosis study and 32 fibroatheromas without rupture on optical coherence tomography from a stable angina cohort. Mechanical loading in the periluminal region was estimated by calculating maximum principal PSS by finite element analysis. Results PSS increased with increasing lumen area (r = 0.46; p = 0.001), lumen eccentricity (r = 0.32; p = 0.001), and necrotic core ≥10% (r = 0.12; p = 0.001), but reduced when dense calcium was ≥10% (r = −0.12; p = 0.001). Ruptured fibroatheromas showed higher PSS (133 kPa [quartiles 1 to 3: 90 to 191 kPa] vs. 104 kPa [quartiles 1 to 3: 75 to 142 kPa]; p = 0.002) and variation in PSS (55 kPa [quartiles 1 to 3: 37 to 75 kPa] vs. 43 kPa [quartiles 1 to 3: 34 to 59 kPa]; p = 0.002) than nonruptured fibroatheromas, with rupture primarily occurring either proximal or immediately adjacent to the minimal luminal area (87.5% vs. 12.5%; p = 0.001). PSS was higher in segments proximal to the rupture site (143 kPa [quartiles 1 to 3: 101 to 200 kPa] vs. 120 kPa [quartiles 1 to 3: 78 to 180 kPa]; p = 0.001) versus distal segments, associated with increased necrotic core (19.1% [quartiles 1 to 3: 11% to 29%] vs. 14.3% [quartiles 1 to 3: 8% to 23%]; p = 0.001) but reduced fibrous/fibrofatty tissue (63.6% [quartiles 1 to 3: 46% to 78%] vs. 72.7% [quartiles 1 to 3: 54% to 86%]; p = 0.001). PSS >135 kPa was a good predictor of rupture in higher risk regions. Conclusions PSS is determined by plaque composition, plaque architecture, and lumen geometry. PSS and PSS variability are increased in plaques with rupture, particularly at proximal segments. Incorporating PSS into plaque assessment may improve identification of rupture-prone plaques.
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tct 598 plaque rupture in coronary atherosclerosis is associated with increased plaque Structural Stress
Journal of the American College of Cardiology, 2016Co-Authors: Charis Costopoulos, Zhongzhao Teng, Yuan Huang, Adam J Brown, Patrick A Calvert, Stephen P Hoole, Nick E J West, Jonathan H Gillard, Martin R BennettAbstract:Plaque rupture is the commonest cause of myocardial infarction, occurring particularly in higher-risk lesions such as fibroatheromas. However, prospective virtual-histology intravascular ultrasound (VH-IVUS) studies indicate that <10% higher-risk plaques cause clinical events over 3-years,
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coronary plaque Structural Stress is associated with plaque composition and subtype and higher in acute coronary syndrome the beacon i biomechanical evaluation of atheromatous coronary arteries study
Circulation-cardiovascular Imaging, 2014Co-Authors: Zhongzhao Teng, Yuan Huang, Adam J Brown, Patrick A Calvert, Richard A Parker, Daniel R Obaid, Stephen P Hoole, Nick E J West, Jonathan H Gillard, Martin R BennettAbstract:Background— Atherosclerotic plaques underlying most myocardial infarctions have thin fibrous caps and large necrotic cores; however, these features alone do not reliably identify plaques that rupture. Rupture occurs when plaque Structural Stress (PSS) exceeds mechanical strength. We examined whether PSS could be calculated in vivo based on virtual histology (VH) intravascular ultrasound and whether PSS varied according to plaque composition, subtype, or clinical presentation. Methods and Results— A total of 4429 VH intravascular ultrasound frames from 53 patients were analyzed, identifying 99 584 individual plaque components. PSS was calculated by finite element analysis in whole vessels, in individual plaques, and in higher-risk regions (plaque burden ≥70%, mean luminal area ≤4 mm 2 , noncalcified VH-defined thin-cap fibroatheroma). Plaque components including total area/arc of calcification ( R 2 =0.33; P R 2 =0.28; P R 2 =0.18; P R 2 =0.15; P P =0.002). PSS was also higher in patients with an acute coronary syndrome, where mean luminal area ≤4 mm 2 (8.24 [7.06–9.93] versus 7.72 [6.33–9.34]; P =0.03), plaque burden ≥70% (9.18 [7.44–10.88] versus 7.93 [6.16–9.46]; P =0.02), and in noncalcified VH-defined thin-cap fibroatheroma (9.23 [7.33–11.44] versus 7.65 [6.45–8.62]; P =0.02). Finally, PSS increased the positive predictive value for VH intravascular ultrasound to identify clinical presentation. Conclusions— Finite element analysis modeling demonstrates that Structural Stress is highly variable within plaques, with increased PSS associated with plaque composition, subtype, and higher-risk regions in patients with acute coronary syndrome. PSS may represent a novel tool to analyze the dynamic behavior of coronary plaques with the potential to improve prediction of plaque rupture.
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coronary plaque Structural Stress is associated with plaque composition and subtype and higher in acute coronary syndrome
Circulation-cardiovascular Imaging, 2014Co-Authors: Zhongzhao Teng, Yuan Huang, Adam J Brown, Patrick A Calvert, Richard A Parker, Daniel R Obaid, Stephen P Hoole, Nick E J West, Jonathan H Gillard, Martin R BennettAbstract:Background—Atherosclerotic plaques underlying most myocardial infarctions have thin fibrous caps and large necrotic cores; however, these features alone do not reliably identify plaques that ruptur...
Yuan Huang - One of the best experts on this subject based on the ideXlab platform.
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impact of combined plaque Structural Stress and wall shear Stress on coronary plaque progression regression and changes in composition
European Heart Journal, 2019Co-Authors: Charis Costopoulos, Lucas H Timmins, Yuan Huang, Olivia Y Hung, David Molony, Adam J Brown, Emily L Davis, Zhongzhao TengAbstract:AIMS The focal distribution of atherosclerotic plaques suggests that local biomechanical factors may influence plaque development. METHODS AND RESULTS We studied 40 patients at baseline and over 12 months by virtual-histology intravascular ultrasound and bi-plane coronary angiography. We calculated plaque Structural Stress (PSS), defined as the mean of the maximum principal Stress at the peri-luminal region, and wall shear Stress (WSS), defined as the parallel frictional force exerted by blood flow on the endothelial surface, in areas undergoing progression or regression. Changes in plaque area, plaque burden (PB), necrotic core (NC), fibrous tissue (FT), fibrofatty tissue, and dense calcium were calculated for each co-registered frame. A total of 4029 co-registered frames were generated. In areas with progression, high PSS was associated with larger increases in NC and small increases in FT vs. low PSS (difference in ΔNC: 0.24 ± 0.06 mm2; P < 0.0001, difference in ΔFT: -0.15 ± 0.08 mm2; P = 0.049). In areas with regression, high PSS was associated with increased NC and decreased FT (difference in ΔNC: 0.15 ± 0.04; P = 0.0005, difference in ΔFT: -0.31 ± 0.06 mm2; P < 0.0001). Low WSS was associated with increased PB vs. high WSS in areas with progression (difference in ΔPB: 3.3 ± 0.4%; P < 0.001) with a similar pattern observed in areas with regression (difference in ΔPB: 1.2 ± 0.4%; P = 0.004). Plaque Structural Stress and WSS were largely independent of each other (R2 = 0.002; P = 0.001). CONCLUSION Areas with high PSS are associated with compositional changes consistent with increased plaque vulnerability. Areas with low WSS are associated with more plaque growth in areas that progress and less plaque loss in areas that regress. The interplay of PSS and WSS may govern important changes in plaque size and composition.
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impact of combined plaque Structural Stress and wall shear Stress on coronary plaque progression regression and changes in composition
European Heart Journal, 2019Co-Authors: Charis Costopoulos, Lucas H Timmins, Yuan Huang, Olivia Y Hung, David Molony, Adam J Brown, Emily L Davis, Zhongzhao TengAbstract:Open in a separate window Aims The focal distribution of atherosclerotic plaques suggests that local biomechanical factors may influence plaque development.
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plaque rupture in coronary atherosclerosis is associated with increased plaque Structural Stress
Jacc-cardiovascular Imaging, 2017Co-Authors: Charis Costopoulos, Zhongzhao Teng, Yuan Huang, Adam J Brown, Patrick A Calvert, Stephen P Hoole, Nick E J West, Jonathan H Gillard, Martin R BennettAbstract:Abstract Objectives The aim of this study was to identify the determinants of plaque Structural Stress (PSS) and the relationship between PSS and plaques with rupture. Background Plaque rupture is the most common cause of myocardial infarction, occurring particularly in higher risk lesions such as fibroatheromas. However, prospective intravascular ultrasound–virtual histology studies indicate that Methods We analyzed plaque structure and composition in 4,053 virtual histology intravascular ultrasound frames from 32 fibroatheromas with rupture from the intravascular ultrasound–virtual histology in Vulnerable Atherosclerosis study and 32 fibroatheromas without rupture on optical coherence tomography from a stable angina cohort. Mechanical loading in the periluminal region was estimated by calculating maximum principal PSS by finite element analysis. Results PSS increased with increasing lumen area (r = 0.46; p = 0.001), lumen eccentricity (r = 0.32; p = 0.001), and necrotic core ≥10% (r = 0.12; p = 0.001), but reduced when dense calcium was ≥10% (r = −0.12; p = 0.001). Ruptured fibroatheromas showed higher PSS (133 kPa [quartiles 1 to 3: 90 to 191 kPa] vs. 104 kPa [quartiles 1 to 3: 75 to 142 kPa]; p = 0.002) and variation in PSS (55 kPa [quartiles 1 to 3: 37 to 75 kPa] vs. 43 kPa [quartiles 1 to 3: 34 to 59 kPa]; p = 0.002) than nonruptured fibroatheromas, with rupture primarily occurring either proximal or immediately adjacent to the minimal luminal area (87.5% vs. 12.5%; p = 0.001). PSS was higher in segments proximal to the rupture site (143 kPa [quartiles 1 to 3: 101 to 200 kPa] vs. 120 kPa [quartiles 1 to 3: 78 to 180 kPa]; p = 0.001) versus distal segments, associated with increased necrotic core (19.1% [quartiles 1 to 3: 11% to 29%] vs. 14.3% [quartiles 1 to 3: 8% to 23%]; p = 0.001) but reduced fibrous/fibrofatty tissue (63.6% [quartiles 1 to 3: 46% to 78%] vs. 72.7% [quartiles 1 to 3: 54% to 86%]; p = 0.001). PSS >135 kPa was a good predictor of rupture in higher risk regions. Conclusions PSS is determined by plaque composition, plaque architecture, and lumen geometry. PSS and PSS variability are increased in plaques with rupture, particularly at proximal segments. Incorporating PSS into plaque assessment may improve identification of rupture-prone plaques.
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tct 598 plaque rupture in coronary atherosclerosis is associated with increased plaque Structural Stress
Journal of the American College of Cardiology, 2016Co-Authors: Charis Costopoulos, Zhongzhao Teng, Yuan Huang, Adam J Brown, Patrick A Calvert, Stephen P Hoole, Nick E J West, Jonathan H Gillard, Martin R BennettAbstract:Plaque rupture is the commonest cause of myocardial infarction, occurring particularly in higher-risk lesions such as fibroatheromas. However, prospective virtual-histology intravascular ultrasound (VH-IVUS) studies indicate that <10% higher-risk plaques cause clinical events over 3-years,
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coronary plaque Structural Stress is associated with plaque composition and subtype and higher in acute coronary syndrome the beacon i biomechanical evaluation of atheromatous coronary arteries study
Circulation-cardiovascular Imaging, 2014Co-Authors: Zhongzhao Teng, Yuan Huang, Adam J Brown, Patrick A Calvert, Richard A Parker, Daniel R Obaid, Stephen P Hoole, Nick E J West, Jonathan H Gillard, Martin R BennettAbstract:Background— Atherosclerotic plaques underlying most myocardial infarctions have thin fibrous caps and large necrotic cores; however, these features alone do not reliably identify plaques that rupture. Rupture occurs when plaque Structural Stress (PSS) exceeds mechanical strength. We examined whether PSS could be calculated in vivo based on virtual histology (VH) intravascular ultrasound and whether PSS varied according to plaque composition, subtype, or clinical presentation. Methods and Results— A total of 4429 VH intravascular ultrasound frames from 53 patients were analyzed, identifying 99 584 individual plaque components. PSS was calculated by finite element analysis in whole vessels, in individual plaques, and in higher-risk regions (plaque burden ≥70%, mean luminal area ≤4 mm 2 , noncalcified VH-defined thin-cap fibroatheroma). Plaque components including total area/arc of calcification ( R 2 =0.33; P R 2 =0.28; P R 2 =0.18; P R 2 =0.15; P P =0.002). PSS was also higher in patients with an acute coronary syndrome, where mean luminal area ≤4 mm 2 (8.24 [7.06–9.93] versus 7.72 [6.33–9.34]; P =0.03), plaque burden ≥70% (9.18 [7.44–10.88] versus 7.93 [6.16–9.46]; P =0.02), and in noncalcified VH-defined thin-cap fibroatheroma (9.23 [7.33–11.44] versus 7.65 [6.45–8.62]; P =0.02). Finally, PSS increased the positive predictive value for VH intravascular ultrasound to identify clinical presentation. Conclusions— Finite element analysis modeling demonstrates that Structural Stress is highly variable within plaques, with increased PSS associated with plaque composition, subtype, and higher-risk regions in patients with acute coronary syndrome. PSS may represent a novel tool to analyze the dynamic behavior of coronary plaques with the potential to improve prediction of plaque rupture.
