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Himanshu Gupta - One of the best experts on this subject based on the ideXlab platform.
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Left Ventricular Torsion Shear Angle Volume Approach for Noninvasive Evaluation of Diastolic Dysfunction in Preserved Ejection Fraction
Journal of the American Heart Association, 2017Co-Authors: Oleg F. Sharifov, Louis J. Dell'italia, Thomas S. Denney, Chun S. Schiros, Inmaculada Aban, Gilbert J. Perry, Steven G. Lloyd, Himanshu GuptaAbstract:Background Accurate noninvasive diagnostic tools for evaluating left ventricular (LV) diastolic dysfunction (LVDD) are limited in preserved LV ejection fraction. We previously proposed the relationship of normalized rate of change in LV torsion Shear Angle (φ′) to corresponding rate of change in LV volume (V′) during early diastole (represented as −dφ′/dV′) as a measure of LV diastolic function. We prospectively evaluated diagnostic accuracy of −dφ′/dV′ in respect to invasive LV parameters. Methods and Results Participants (n=36, age 61±7 years) with LV ejection fraction ≥50% and no acute myocardial infarction undergoing coronary angiography for chest pain and/or dyspnea evaluation were studied. High‐fidelity invasive LV pressure measurements and cardiac magnetic resonance imaging with tissue tagging were performed. τ, the time constant of LV diastolic relaxation, was 58±10 milliseconds (mean±SD), and LV end‐diastolic pressure was 14.5±5.5 mm Hg. Cardiac magnetic resonance imaging‐derived −dφ′/dV′ was 5.6±3.7. The value of −dφ′/dV′ correlated with both τ and LV end‐diastolic pressure ( r =0.39 and 0.36, respectively, P 48 milliseconds and LV end‐diastolic pressure >12 mm Hg (LVDD1), or, alternatively, τ>48 milliseconds and LV end‐diastolic pressure >16 mm Hg (LVDD2). Area under the curve (AUC) of −dφ′/dV′ for identifying LVDD1 was 0.83 (0.67‐0.98, P =0.001), with sensitivity/specificity of 72%/100% for −dφ′/dV′ ≥6.2. AUC of −dφ′/dV′ for identifying LVDD_2 was 0.82 (0.64‐1.00, P =0.006), with sensitivity/specificity of 76%/85% for −dφ′/dV′ ≥6.9. There were good limits of agreement between pre‐ and post‐nitroglycerin −dφ′/dV′. Conclusions The −dφ′/dV′ obtained from the LV torsion volume loop is a promising parameter for assessing global LVDD with preserved LV ejection fraction and requires further evaluation.
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LEFT VENTRICULAR TORSION Shear Angle VOLUME APPROACH FOR NON-INVASIVE EVALUATION OF DIASTOLIC DYSFUNCTION IN PRESERVED EJECTION FRACTION
Journal of the American College of Cardiology, 2017Co-Authors: Himanshu Gupta, Louis J. Dell'italia, Oleg F. Sharifov, Chun S. Schiros, Inmaculada Aban, Gilbert J. Perry, Thomas S. DenneyAbstract:Background: Diagnostic accuracy of echocardiography for evaluating diastolic dysfunction is limited in preserved left ventricular ejection fraction (LVEF). We previously proposed the relationship of normalized rate of change in LV torsion Shear Angle ( φ’ ) to corresponding rate of change in LV
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Left ventricular torsion Shear Angle volume analysis in patients with hypertension: a global approach for LV diastolic function
Journal of Cardiovascular Magnetic Resonance, 2014Co-Authors: Chun S. Schiros, Louis J. Dell'italia, Thomas S. Denney, Ravi V Desai, Bharath Ambale Venkatesh, Krishna K. Gaddam, Shilpi Agarwal, Steven G. Lloyd, David A. Calhoun, Himanshu GuptaAbstract:Background: Torsion Shear Angle φ is an important measure of left ventricular (LV) systolic and diastolic functions. Here we provide a novel index utilizing LV normalized torsion Shear Angle ^ ðÞ volume ^ V loop to assess LV diastolic functional properties. We defined the area within ^ ^ V loop as torsion hysteresis area, and hypothesized that it may be an important global parameter of diastolic function. We evaluated the ^ φ changes to increased ^ during early diastoled^ φ=d ^ as a potential measure of LV suction. Methods: Sixty resistant hypertension patients (HTN), forty control volunteers were studied using cardiovascular magnetic resonance with tissue tagging. Volumetric and torsional parameters were evaluated. Results: HTN demonstrated concentric remodeling with preserved ejection fraction. HTN had significantly decreased normalized early filling rate, early diastolic mitral annulus velocity and E/A (1.33±1.13 vs. 2.19± 1.07, P 0.12 (Control mean torsion hysteresis area +1SD). Conclusions: Torsion hysteresis area and peak early diastolicd^=d ^ V were significantly increased in hypertensive concentric remodeling. The ^ ^ loop takes into account the active and passive recoil processes of LV diastolic and
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Left ventricular twist and Shear-Angle in patients with mitral regurgitation
Journal of Cardiovascular Magnetic Resonance, 2013Co-Authors: Meral Reyhan, Himanshu Gupta, Steven G Llyod, Louis J. Dell'italia, Hyun J. Kim, Thomas S. Denney, Daniel B. EnnisAbstract:Background Mitral regurgitation(MR) is a common valvular disorder that foments left ventricular(LV) dysfunction. The study of LV twist during the progression of MR is limited to studies performed with ultrasound/echo(1-3) in human subjects or animal studies(4), which suggest that LV twist decreases when MR is present. LV circumferential-longitudinal Shear Angle (CL-Shear Angle) has been proposed as a more reproducible measure of LV rotational mechanics, but has not been evaluated in patients with MR. We hypothesized that both LV twist and CL-Shear Angle would decrease with severity of MR. Methods Normal subjects(n=54), moderate MR patients(n=29), and severe MR patients(n=54) were studied after obtaining informed consent. MRI was performed on a 1.5T scanner (Signa, GE Healthcare, Milwaukee, WI) and grid tagged LV images were collect from the base to the apex(7). LV twist and CL-Shear Angle measurements were derived from Fourier Analysis of STimulated echoes(FAST)(8). LV twist is defined as the difference in rotation at the apex relative to the base of the heart. Shear-Angle is defined as the difference in rotation at the apex times the radius of the apex relative to the base times the radius of the base, divided by the distance between the apex and base(5, 6). Peak LV twist and peak CL-Shear Angle from the three groups were compared using a one-way ANOVA and Tukey’s least significant difference(LSD) procedure for multiple comparisons. Results Mean peak LV twist for normal subjects, moderate MR patients, and severe MR patients were: 11.5±3.2, 9.0±3.0, 8.8±2.6, respectively. Mean peak CL-Shear Angle for normal subjects, moderate MR patients, and severe MR patients were: 5.0±1.4, 4.7±1.6, 5.0±1.3 respectively. The one-way ANOVA of peak twist between the groups, showed differences among the groups(p
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left ventricular twist and Shear Angle in patients with mitral regurgitation
Journal of Cardiovascular Magnetic Resonance, 2013Co-Authors: Meral Reyhan, Himanshu Gupta, Steven G Llyod, Hyun J. Kim, Thomas S. Denney, Louis J Dellitalia, Daniel B. EnnisAbstract:Background Mitral regurgitation(MR) is a common valvular disorder that foments left ventricular(LV) dysfunction. The study of LV twist during the progression of MR is limited to studies performed with ultrasound/echo(1-3) in human subjects or animal studies(4), which suggest that LV twist decreases when MR is present. LV circumferential-longitudinal Shear Angle (CL-Shear Angle) has been proposed as a more reproducible measure of LV rotational mechanics, but has not been evaluated in patients with MR. We hypothesized that both LV twist and CL-Shear Angle would decrease with severity of MR. Methods Normal subjects(n=54), moderate MR patients(n=29), and severe MR patients(n=54) were studied after obtaining informed consent. MRI was performed on a 1.5T scanner (Signa, GE Healthcare, Milwaukee, WI) and grid tagged LV images were collect from the base to the apex(7). LV twist and CL-Shear Angle measurements were derived from Fourier Analysis of STimulated echoes(FAST)(8). LV twist is defined as the difference in rotation at the apex relative to the base of the heart. Shear-Angle is defined as the difference in rotation at the apex times the radius of the apex relative to the base times the radius of the base, divided by the distance between the apex and base(5, 6). Peak LV twist and peak CL-Shear Angle from the three groups were compared using a one-way ANOVA and Tukey’s least significant difference(LSD) procedure for multiple comparisons. Results Mean peak LV twist for normal subjects, moderate MR patients, and severe MR patients were: 11.5±3.2, 9.0±3.0, 8.8±2.6, respectively. Mean peak CL-Shear Angle for normal subjects, moderate MR patients, and severe MR patients were: 5.0±1.4, 4.7±1.6, 5.0±1.3 respectively. The one-way ANOVA of peak twist between the groups, showed differences among the groups(p<0.0001). Further investigation with LSD, showed a significant difference between the normal subjects and the moderate MR patients and between the normal subject group and the severe MR patients. However, the one-way ANOVA of peak Shear-Angle did not reveal any differences between the three groups(p=0.4).
Thomas S. Denney - One of the best experts on this subject based on the ideXlab platform.
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Left Ventricular Torsion Shear Angle Volume Approach for Noninvasive Evaluation of Diastolic Dysfunction in Preserved Ejection Fraction
Journal of the American Heart Association, 2017Co-Authors: Oleg F. Sharifov, Louis J. Dell'italia, Thomas S. Denney, Chun S. Schiros, Inmaculada Aban, Gilbert J. Perry, Steven G. Lloyd, Himanshu GuptaAbstract:Background Accurate noninvasive diagnostic tools for evaluating left ventricular (LV) diastolic dysfunction (LVDD) are limited in preserved LV ejection fraction. We previously proposed the relationship of normalized rate of change in LV torsion Shear Angle (φ′) to corresponding rate of change in LV volume (V′) during early diastole (represented as −dφ′/dV′) as a measure of LV diastolic function. We prospectively evaluated diagnostic accuracy of −dφ′/dV′ in respect to invasive LV parameters. Methods and Results Participants (n=36, age 61±7 years) with LV ejection fraction ≥50% and no acute myocardial infarction undergoing coronary angiography for chest pain and/or dyspnea evaluation were studied. High‐fidelity invasive LV pressure measurements and cardiac magnetic resonance imaging with tissue tagging were performed. τ, the time constant of LV diastolic relaxation, was 58±10 milliseconds (mean±SD), and LV end‐diastolic pressure was 14.5±5.5 mm Hg. Cardiac magnetic resonance imaging‐derived −dφ′/dV′ was 5.6±3.7. The value of −dφ′/dV′ correlated with both τ and LV end‐diastolic pressure ( r =0.39 and 0.36, respectively, P 48 milliseconds and LV end‐diastolic pressure >12 mm Hg (LVDD1), or, alternatively, τ>48 milliseconds and LV end‐diastolic pressure >16 mm Hg (LVDD2). Area under the curve (AUC) of −dφ′/dV′ for identifying LVDD1 was 0.83 (0.67‐0.98, P =0.001), with sensitivity/specificity of 72%/100% for −dφ′/dV′ ≥6.2. AUC of −dφ′/dV′ for identifying LVDD_2 was 0.82 (0.64‐1.00, P =0.006), with sensitivity/specificity of 76%/85% for −dφ′/dV′ ≥6.9. There were good limits of agreement between pre‐ and post‐nitroglycerin −dφ′/dV′. Conclusions The −dφ′/dV′ obtained from the LV torsion volume loop is a promising parameter for assessing global LVDD with preserved LV ejection fraction and requires further evaluation.
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LEFT VENTRICULAR TORSION Shear Angle VOLUME APPROACH FOR NON-INVASIVE EVALUATION OF DIASTOLIC DYSFUNCTION IN PRESERVED EJECTION FRACTION
Journal of the American College of Cardiology, 2017Co-Authors: Himanshu Gupta, Louis J. Dell'italia, Oleg F. Sharifov, Chun S. Schiros, Inmaculada Aban, Gilbert J. Perry, Thomas S. DenneyAbstract:Background: Diagnostic accuracy of echocardiography for evaluating diastolic dysfunction is limited in preserved left ventricular ejection fraction (LVEF). We previously proposed the relationship of normalized rate of change in LV torsion Shear Angle ( φ’ ) to corresponding rate of change in LV
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Left ventricular torsion Shear Angle volume analysis in patients with hypertension: a global approach for LV diastolic function
Journal of Cardiovascular Magnetic Resonance, 2014Co-Authors: Chun S. Schiros, Louis J. Dell'italia, Thomas S. Denney, Ravi V Desai, Bharath Ambale Venkatesh, Krishna K. Gaddam, Shilpi Agarwal, Steven G. Lloyd, David A. Calhoun, Himanshu GuptaAbstract:Background: Torsion Shear Angle φ is an important measure of left ventricular (LV) systolic and diastolic functions. Here we provide a novel index utilizing LV normalized torsion Shear Angle ^ ðÞ volume ^ V loop to assess LV diastolic functional properties. We defined the area within ^ ^ V loop as torsion hysteresis area, and hypothesized that it may be an important global parameter of diastolic function. We evaluated the ^ φ changes to increased ^ during early diastoled^ φ=d ^ as a potential measure of LV suction. Methods: Sixty resistant hypertension patients (HTN), forty control volunteers were studied using cardiovascular magnetic resonance with tissue tagging. Volumetric and torsional parameters were evaluated. Results: HTN demonstrated concentric remodeling with preserved ejection fraction. HTN had significantly decreased normalized early filling rate, early diastolic mitral annulus velocity and E/A (1.33±1.13 vs. 2.19± 1.07, P 0.12 (Control mean torsion hysteresis area +1SD). Conclusions: Torsion hysteresis area and peak early diastolicd^=d ^ V were significantly increased in hypertensive concentric remodeling. The ^ ^ loop takes into account the active and passive recoil processes of LV diastolic and
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Left ventricular twist and Shear-Angle in patients with mitral regurgitation
Journal of Cardiovascular Magnetic Resonance, 2013Co-Authors: Meral Reyhan, Himanshu Gupta, Steven G Llyod, Louis J. Dell'italia, Hyun J. Kim, Thomas S. Denney, Daniel B. EnnisAbstract:Background Mitral regurgitation(MR) is a common valvular disorder that foments left ventricular(LV) dysfunction. The study of LV twist during the progression of MR is limited to studies performed with ultrasound/echo(1-3) in human subjects or animal studies(4), which suggest that LV twist decreases when MR is present. LV circumferential-longitudinal Shear Angle (CL-Shear Angle) has been proposed as a more reproducible measure of LV rotational mechanics, but has not been evaluated in patients with MR. We hypothesized that both LV twist and CL-Shear Angle would decrease with severity of MR. Methods Normal subjects(n=54), moderate MR patients(n=29), and severe MR patients(n=54) were studied after obtaining informed consent. MRI was performed on a 1.5T scanner (Signa, GE Healthcare, Milwaukee, WI) and grid tagged LV images were collect from the base to the apex(7). LV twist and CL-Shear Angle measurements were derived from Fourier Analysis of STimulated echoes(FAST)(8). LV twist is defined as the difference in rotation at the apex relative to the base of the heart. Shear-Angle is defined as the difference in rotation at the apex times the radius of the apex relative to the base times the radius of the base, divided by the distance between the apex and base(5, 6). Peak LV twist and peak CL-Shear Angle from the three groups were compared using a one-way ANOVA and Tukey’s least significant difference(LSD) procedure for multiple comparisons. Results Mean peak LV twist for normal subjects, moderate MR patients, and severe MR patients were: 11.5±3.2, 9.0±3.0, 8.8±2.6, respectively. Mean peak CL-Shear Angle for normal subjects, moderate MR patients, and severe MR patients were: 5.0±1.4, 4.7±1.6, 5.0±1.3 respectively. The one-way ANOVA of peak twist between the groups, showed differences among the groups(p
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left ventricular twist and Shear Angle in patients with mitral regurgitation
Journal of Cardiovascular Magnetic Resonance, 2013Co-Authors: Meral Reyhan, Himanshu Gupta, Steven G Llyod, Hyun J. Kim, Thomas S. Denney, Louis J Dellitalia, Daniel B. EnnisAbstract:Background Mitral regurgitation(MR) is a common valvular disorder that foments left ventricular(LV) dysfunction. The study of LV twist during the progression of MR is limited to studies performed with ultrasound/echo(1-3) in human subjects or animal studies(4), which suggest that LV twist decreases when MR is present. LV circumferential-longitudinal Shear Angle (CL-Shear Angle) has been proposed as a more reproducible measure of LV rotational mechanics, but has not been evaluated in patients with MR. We hypothesized that both LV twist and CL-Shear Angle would decrease with severity of MR. Methods Normal subjects(n=54), moderate MR patients(n=29), and severe MR patients(n=54) were studied after obtaining informed consent. MRI was performed on a 1.5T scanner (Signa, GE Healthcare, Milwaukee, WI) and grid tagged LV images were collect from the base to the apex(7). LV twist and CL-Shear Angle measurements were derived from Fourier Analysis of STimulated echoes(FAST)(8). LV twist is defined as the difference in rotation at the apex relative to the base of the heart. Shear-Angle is defined as the difference in rotation at the apex times the radius of the apex relative to the base times the radius of the base, divided by the distance between the apex and base(5, 6). Peak LV twist and peak CL-Shear Angle from the three groups were compared using a one-way ANOVA and Tukey’s least significant difference(LSD) procedure for multiple comparisons. Results Mean peak LV twist for normal subjects, moderate MR patients, and severe MR patients were: 11.5±3.2, 9.0±3.0, 8.8±2.6, respectively. Mean peak CL-Shear Angle for normal subjects, moderate MR patients, and severe MR patients were: 5.0±1.4, 4.7±1.6, 5.0±1.3 respectively. The one-way ANOVA of peak twist between the groups, showed differences among the groups(p<0.0001). Further investigation with LSD, showed a significant difference between the normal subjects and the moderate MR patients and between the normal subject group and the severe MR patients. However, the one-way ANOVA of peak Shear-Angle did not reveal any differences between the three groups(p=0.4).
Xiaoliang Jin - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Shear Band Formation and Microstructure Evolution during Orthogonal Cutting of Ti-5553: Part I—Shear Angle, Strain and Strain Rate
Journal of Materials Engineering and Performance, 2020Co-Authors: David Yan, Xiaoliang JinAbstract:Ti-5553 (Ti-5Al-5Mo-5V-3Cr-0.5Fe) is a recently commercialized near-β titanium alloy employed in large-section forging of Boeing 787 landing gear. The machinability of Ti-5553 is low owing to its high strength at elevated temperature, low thermal conductivity and high chemical reactivity. Chip serration occurs during high-speed machining of Ti-5553, which is found to be attributed to the periodic formation of Shear bands caused by thermoplastic instability within the primary Shear zone. Microscopic observations indicate that the geometry and microstructure of Shear bands are significantly related to the Shear Angle, Shear strain and strain rate under the given cutting conditions. In this study, quick-stop turning tests were conducted to understand the chip formation mechanism in machining Ti-5553, and the machined chips were metallographically characterized to investigate their morphology and microstructure evolutions. In the Part I of this study, the Shear Angle, Shear strain and strain rate were quantitatively determined, and the Shear band microstructure was examined to reveal the effect of cutting conditions in dry turning of Ti-5553. This study advances the mechanism of Shear band formation in machining Ti-5553 and develops a novel experimental approach to directly obtain the actual Shear strain and strain rate based on the geometry of the machined chip.
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characterization of Shear band formation and microstructure evolution during orthogonal cutting of ti 5553 part i Shear Angle strain and strain rate
Journal of Materials Engineering and Performance, 2020Co-Authors: David Yan, Xiaoliang JinAbstract:Ti-5553 (Ti-5Al-5Mo-5V-3Cr-0.5Fe) is a recently commercialized near-β titanium alloy employed in large-section forging of Boeing 787 landing gear. The machinability of Ti-5553 is low owing to its high strength at elevated temperature, low thermal conductivity and high chemical reactivity. Chip serration occurs during high-speed machining of Ti-5553, which is found to be attributed to the periodic formation of Shear bands caused by thermoplastic instability within the primary Shear zone. Microscopic observations indicate that the geometry and microstructure of Shear bands are significantly related to the Shear Angle, Shear strain and strain rate under the given cutting conditions. In this study, quick-stop turning tests were conducted to understand the chip formation mechanism in machining Ti-5553, and the machined chips were metallographically characterized to investigate their morphology and microstructure evolutions. In the Part I of this study, the Shear Angle, Shear strain and strain rate were quantitatively determined, and the Shear band microstructure was examined to reveal the effect of cutting conditions in dry turning of Ti-5553. This study advances the mechanism of Shear band formation in machining Ti-5553 and develops a novel experimental approach to directly obtain the actual Shear strain and strain rate based on the geometry of the machined chip.
David Yan - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Shear Band Formation and Microstructure Evolution during Orthogonal Cutting of Ti-5553: Part I—Shear Angle, Strain and Strain Rate
Journal of Materials Engineering and Performance, 2020Co-Authors: David Yan, Xiaoliang JinAbstract:Ti-5553 (Ti-5Al-5Mo-5V-3Cr-0.5Fe) is a recently commercialized near-β titanium alloy employed in large-section forging of Boeing 787 landing gear. The machinability of Ti-5553 is low owing to its high strength at elevated temperature, low thermal conductivity and high chemical reactivity. Chip serration occurs during high-speed machining of Ti-5553, which is found to be attributed to the periodic formation of Shear bands caused by thermoplastic instability within the primary Shear zone. Microscopic observations indicate that the geometry and microstructure of Shear bands are significantly related to the Shear Angle, Shear strain and strain rate under the given cutting conditions. In this study, quick-stop turning tests were conducted to understand the chip formation mechanism in machining Ti-5553, and the machined chips were metallographically characterized to investigate their morphology and microstructure evolutions. In the Part I of this study, the Shear Angle, Shear strain and strain rate were quantitatively determined, and the Shear band microstructure was examined to reveal the effect of cutting conditions in dry turning of Ti-5553. This study advances the mechanism of Shear band formation in machining Ti-5553 and develops a novel experimental approach to directly obtain the actual Shear strain and strain rate based on the geometry of the machined chip.
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characterization of Shear band formation and microstructure evolution during orthogonal cutting of ti 5553 part i Shear Angle strain and strain rate
Journal of Materials Engineering and Performance, 2020Co-Authors: David Yan, Xiaoliang JinAbstract:Ti-5553 (Ti-5Al-5Mo-5V-3Cr-0.5Fe) is a recently commercialized near-β titanium alloy employed in large-section forging of Boeing 787 landing gear. The machinability of Ti-5553 is low owing to its high strength at elevated temperature, low thermal conductivity and high chemical reactivity. Chip serration occurs during high-speed machining of Ti-5553, which is found to be attributed to the periodic formation of Shear bands caused by thermoplastic instability within the primary Shear zone. Microscopic observations indicate that the geometry and microstructure of Shear bands are significantly related to the Shear Angle, Shear strain and strain rate under the given cutting conditions. In this study, quick-stop turning tests were conducted to understand the chip formation mechanism in machining Ti-5553, and the machined chips were metallographically characterized to investigate their morphology and microstructure evolutions. In the Part I of this study, the Shear Angle, Shear strain and strain rate were quantitatively determined, and the Shear band microstructure was examined to reveal the effect of cutting conditions in dry turning of Ti-5553. This study advances the mechanism of Shear band formation in machining Ti-5553 and develops a novel experimental approach to directly obtain the actual Shear strain and strain rate based on the geometry of the machined chip.
Louis J. Dell'italia - One of the best experts on this subject based on the ideXlab platform.
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Left Ventricular Torsion Shear Angle Volume Approach for Noninvasive Evaluation of Diastolic Dysfunction in Preserved Ejection Fraction
Journal of the American Heart Association, 2017Co-Authors: Oleg F. Sharifov, Louis J. Dell'italia, Thomas S. Denney, Chun S. Schiros, Inmaculada Aban, Gilbert J. Perry, Steven G. Lloyd, Himanshu GuptaAbstract:Background Accurate noninvasive diagnostic tools for evaluating left ventricular (LV) diastolic dysfunction (LVDD) are limited in preserved LV ejection fraction. We previously proposed the relationship of normalized rate of change in LV torsion Shear Angle (φ′) to corresponding rate of change in LV volume (V′) during early diastole (represented as −dφ′/dV′) as a measure of LV diastolic function. We prospectively evaluated diagnostic accuracy of −dφ′/dV′ in respect to invasive LV parameters. Methods and Results Participants (n=36, age 61±7 years) with LV ejection fraction ≥50% and no acute myocardial infarction undergoing coronary angiography for chest pain and/or dyspnea evaluation were studied. High‐fidelity invasive LV pressure measurements and cardiac magnetic resonance imaging with tissue tagging were performed. τ, the time constant of LV diastolic relaxation, was 58±10 milliseconds (mean±SD), and LV end‐diastolic pressure was 14.5±5.5 mm Hg. Cardiac magnetic resonance imaging‐derived −dφ′/dV′ was 5.6±3.7. The value of −dφ′/dV′ correlated with both τ and LV end‐diastolic pressure ( r =0.39 and 0.36, respectively, P 48 milliseconds and LV end‐diastolic pressure >12 mm Hg (LVDD1), or, alternatively, τ>48 milliseconds and LV end‐diastolic pressure >16 mm Hg (LVDD2). Area under the curve (AUC) of −dφ′/dV′ for identifying LVDD1 was 0.83 (0.67‐0.98, P =0.001), with sensitivity/specificity of 72%/100% for −dφ′/dV′ ≥6.2. AUC of −dφ′/dV′ for identifying LVDD_2 was 0.82 (0.64‐1.00, P =0.006), with sensitivity/specificity of 76%/85% for −dφ′/dV′ ≥6.9. There were good limits of agreement between pre‐ and post‐nitroglycerin −dφ′/dV′. Conclusions The −dφ′/dV′ obtained from the LV torsion volume loop is a promising parameter for assessing global LVDD with preserved LV ejection fraction and requires further evaluation.
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LEFT VENTRICULAR TORSION Shear Angle VOLUME APPROACH FOR NON-INVASIVE EVALUATION OF DIASTOLIC DYSFUNCTION IN PRESERVED EJECTION FRACTION
Journal of the American College of Cardiology, 2017Co-Authors: Himanshu Gupta, Louis J. Dell'italia, Oleg F. Sharifov, Chun S. Schiros, Inmaculada Aban, Gilbert J. Perry, Thomas S. DenneyAbstract:Background: Diagnostic accuracy of echocardiography for evaluating diastolic dysfunction is limited in preserved left ventricular ejection fraction (LVEF). We previously proposed the relationship of normalized rate of change in LV torsion Shear Angle ( φ’ ) to corresponding rate of change in LV
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Left ventricular torsion Shear Angle volume analysis in patients with hypertension: a global approach for LV diastolic function
Journal of Cardiovascular Magnetic Resonance, 2014Co-Authors: Chun S. Schiros, Louis J. Dell'italia, Thomas S. Denney, Ravi V Desai, Bharath Ambale Venkatesh, Krishna K. Gaddam, Shilpi Agarwal, Steven G. Lloyd, David A. Calhoun, Himanshu GuptaAbstract:Background: Torsion Shear Angle φ is an important measure of left ventricular (LV) systolic and diastolic functions. Here we provide a novel index utilizing LV normalized torsion Shear Angle ^ ðÞ volume ^ V loop to assess LV diastolic functional properties. We defined the area within ^ ^ V loop as torsion hysteresis area, and hypothesized that it may be an important global parameter of diastolic function. We evaluated the ^ φ changes to increased ^ during early diastoled^ φ=d ^ as a potential measure of LV suction. Methods: Sixty resistant hypertension patients (HTN), forty control volunteers were studied using cardiovascular magnetic resonance with tissue tagging. Volumetric and torsional parameters were evaluated. Results: HTN demonstrated concentric remodeling with preserved ejection fraction. HTN had significantly decreased normalized early filling rate, early diastolic mitral annulus velocity and E/A (1.33±1.13 vs. 2.19± 1.07, P 0.12 (Control mean torsion hysteresis area +1SD). Conclusions: Torsion hysteresis area and peak early diastolicd^=d ^ V were significantly increased in hypertensive concentric remodeling. The ^ ^ loop takes into account the active and passive recoil processes of LV diastolic and
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Left ventricular twist and Shear-Angle in patients with mitral regurgitation
Journal of Cardiovascular Magnetic Resonance, 2013Co-Authors: Meral Reyhan, Himanshu Gupta, Steven G Llyod, Louis J. Dell'italia, Hyun J. Kim, Thomas S. Denney, Daniel B. EnnisAbstract:Background Mitral regurgitation(MR) is a common valvular disorder that foments left ventricular(LV) dysfunction. The study of LV twist during the progression of MR is limited to studies performed with ultrasound/echo(1-3) in human subjects or animal studies(4), which suggest that LV twist decreases when MR is present. LV circumferential-longitudinal Shear Angle (CL-Shear Angle) has been proposed as a more reproducible measure of LV rotational mechanics, but has not been evaluated in patients with MR. We hypothesized that both LV twist and CL-Shear Angle would decrease with severity of MR. Methods Normal subjects(n=54), moderate MR patients(n=29), and severe MR patients(n=54) were studied after obtaining informed consent. MRI was performed on a 1.5T scanner (Signa, GE Healthcare, Milwaukee, WI) and grid tagged LV images were collect from the base to the apex(7). LV twist and CL-Shear Angle measurements were derived from Fourier Analysis of STimulated echoes(FAST)(8). LV twist is defined as the difference in rotation at the apex relative to the base of the heart. Shear-Angle is defined as the difference in rotation at the apex times the radius of the apex relative to the base times the radius of the base, divided by the distance between the apex and base(5, 6). Peak LV twist and peak CL-Shear Angle from the three groups were compared using a one-way ANOVA and Tukey’s least significant difference(LSD) procedure for multiple comparisons. Results Mean peak LV twist for normal subjects, moderate MR patients, and severe MR patients were: 11.5±3.2, 9.0±3.0, 8.8±2.6, respectively. Mean peak CL-Shear Angle for normal subjects, moderate MR patients, and severe MR patients were: 5.0±1.4, 4.7±1.6, 5.0±1.3 respectively. The one-way ANOVA of peak twist between the groups, showed differences among the groups(p
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Left ventricular twist, but not circumferential-longitudinal Shear Angle, increases with increasing age in normal subjects
Journal of Cardiovascular Magnetic Resonance, 2013Co-Authors: Meral Reyhan, Himanshu Gupta, Steven G Llyod, Louis J. Dell'italia, Hyun J. Kim, Thomas S. Denney, Daniel B. EnnisAbstract:Background Left Ventricular (LV) twist, defined as the difference in rotation between the apex and the base, has recently been suggested as a diagnostic imaging biomarker for LV dysfunction [1]. Increasing age is associated with an increase in apical rotation, which leads to an increase LV twist [2-4]. Recently, it has been suggested that LV circumferential-longitudinal Shear Angle (CL-Shear Angle) [5] may be a more robust imaging biomarker than LV twist, due to normalization within the formula for ventricular size and slice separation [6]. However, changes in CL-Shear Angle with respect to age have not been reported. CL-Shear Angle is defined as the difference between apical rotation times the epicardial radius of the apex and basal rotation times the epicardial radius of the base, divided by the distance between the apex and base. The purpose of this study was to evaluate age related changes in CL-Shear Angle.
