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Jos J M Westenberg - One of the best experts on this subject based on the ideXlab platform.
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high temporal Velocity encoded mri for the assessment of left ventricular inflow Propagation Velocity comparison with color m mode echocardiography
Journal of Magnetic Resonance Imaging, 2015Co-Authors: Emmeline E Calkoen, Nina Ajmone Marsan, Jeroen J Bax, Pieter J Van Den Boogaard, Arno A W Roest, Albert De Roos, Jos J M WestenbergAbstract:Purpose To develop an alternative method for Vp-assessment using high-temporal Velocity-encoded magnetic resonance imaging (VE-MRI). Left ventricular (LV) inflow Propagation Velocity (Vp) is considered a useful parameter in the complex assessment of LV diastolic function and is measured by Color M-mode echocardiography. Materials and Methods A total of 43 patients diagnosed with ischemic heart failure (61 ± 11 years) and 22 healthy volunteers (29 ± 13 years) underwent Color M-mode echocardiography and VE-MRI to assess the inflow Velocity through the mitral valve (mean interexamination time 14 days). Temporal resolution of VE-MRI was 10.8–11.8 msec. Local LV inflow Velocity was sampled along a 4-cm line starting from the tip of the mitral leaflets and for consecutive sample points the point-in-time was assessed when local Velocity exceeded 30 cm/s. From the position–time relation, Vp was calculated by both the difference quotient (Vp-MRI-DQ) as well as from linear regression (Vp-MRI-LR). Results Good correlation was found between Vp-echo and both Vp-MRI-DQ (r = 0.83, P < 0.001) and Vp-MRI-LR (r = 0.84, P < 0.001). Vp-MRI showed a significant but small underestimation as compared to Vp measured by echocardiography (Vp-MRI-DQ: 5.5 ± 16.2 cm/s, P = 0.008; Vp-MRI-LR: 9.9 ± 15.2 cm/s, P < 0.001). Applying age-related cutoff values for Vp to identify LV impaired relaxation, kappa-agreement with echocardiography was 0.72 (P < 0.001) for Vp-MRI-DQ and 0.69 (P < 0.001) for Vp-MRI-LR. Conclusion High temporal VE-MRI represents a novel approach to assess Vp, showing good correlation with Color M-mode echocardiography. In healthy subjects and patients with ischemic heart failure, this new method demonstrated good agreement with echocardiography to identify LV impaired relaxation. J. Magn. Reson. Imaging 2015.
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left ventricular inflow Propagation Velocity for diastolic function testing head to head comparison between Velocity encoded mri and color m mode doppler echocardiography
Journal of Cardiovascular Magnetic Resonance, 2013Co-Authors: Pieter J Van Den Boogaard, Nina Ajmone Marsan, Albert De Roos, Jos J M WestenbergAbstract:Background The inflow Propagation Velocity (Vprop) of the early filling wave has been proposed as an accurate marker of left ventricular (LV) diastolic function [1]. Traditionally, Color M-mode echo Doppler is used for Vprop-assessment. However, this method has not been validated against an alternative modality such as Velocity-encoded (VE) MRI for assessing Vprop. The purpose of this study was to compare Vprop assessed from high temporal VE MRI with Color M-mode echo Doppler in patients with ischemic cardiomyopathy. Methods
Mario J Garcia - One of the best experts on this subject based on the ideXlab platform.
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color m mode doppler flow Propagation Velocity is a preload insensitive index of left ventricular relaxation animal and human validation
Journal of the American College of Cardiology, 2000Co-Authors: Mario J Garcia, Nicholas G Smedira, Neil L Greenberg, Michael L Main, Michael S Firstenberg, Jill Odabashian, James D ThomasAbstract:OBJECTIVES: To determine the effect of preload in color M-mode Doppler flow Propagation Velocity (v(p)). BACKGROUND: The interpretation of Doppler filling patterns is limited by confounding effects of left ventricular (LV) relaxation and preload. Color M-mode v(p) has been proposed as a new index of LV relaxation. METHODS: We studied four dogs before and during inferior caval (IVC) occlusion at five different inotropic stages and 14 patients before and during partial cardiopulmonary bypass. Left ventricular (LV) end-diastolic volumes (LV-EDV), the time constant of isovolumic relaxation (tau), left atrial (LA) pre-A and LV end-diastolic pressures (LV-EDP) were measured. Peak Velocity during early filling (E) and v(p) were extracted by digital analysis of color M-mode Doppler images. RESULTS: In both animals and humans, LV-EDV and LV-EDP decreased significantly from baseline to IVC occlusion (both p < 0.001). Peak early filling (E) Velocity decreased in animals from 56 +/- 21 to 42 +/- 17 cm/s (p < 0.001) without change in v(p) (from 35 +/- 15 to 35 +/- 16, p = 0.99). Results were similar in humans (from 69 +/- 15 to 53 +/- 22 cm/s, p < 0.001, and 37 +/- 12 to 34 +/- 16, p = 0.30). In both species, there was a strong correlation between LV relaxation (tau) and v(p) (r = 0.78, p < 0.001, r = 0.86, p < 0.001). CONCLUSIONS: Our results indicate that color M-mode Doppler v(p) is not affected by preload alterations and confirms that LV relaxation is its main physiologic determinant in both animals during varying lusitropic conditions and in humans with heart disease.
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color m mode doppler flow Propagation Velocity is a preload insensitive index of left ventricular relaxation animal and human validation
Journal of the American College of Cardiology, 2000Co-Authors: Mario J Garcia, Nicholas G Smedira, Neil L Greenberg, Michael L Main, Michael S Firstenberg, Jill Odabashian, James D ThomasAbstract:Abstract OBJECTIVES To determine the effect of preload in color M-mode Doppler flow Propagation Velocity (vp). BACKGROUND The interpretation of Doppler filling patterns is limited by confounding effects of left ventricular (LV) relaxation and preload. Color M-mode vphas been proposed as a new index of LV relaxation. METHODS We studied four dogs before and during inferior caval (IVC) occlusion at five different inotropic stages and 14 patients before and during partial cardiopulmonary bypass. Left ventricular (LV) end-diastolic volumes (LV-EDV), the time constant of isovolumic relaxation (tau), left atrial (LA) pre-A and LV end-diastolic pressures (LV-EDP) were measured. Peak Velocity during early filling (E) and vpwere extracted by digital analysis of color M-mode Doppler images. RESULTS In both animals and humans, LV-EDV and LV-EDP decreased significantly from baseline to IVC occlusion (both p CONCLUSIONS Our results indicate that color M-mode Doppler vpis not affected by preload alterations and confirms that LV relaxation is its main physiologic determinant in both animals during varying lusitropic conditions and in humans with heart disease.
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color m mode doppler flow Propagation Velocity is a relatively preload independent index of left ventricular filling
Journal of The American Society of Echocardiography, 1999Co-Authors: Mario J Garcia, Robert T Palac, David J Malenka, Patricia Terrell, Jonathan F PlehnAbstract:Standard Doppler indexes of transmitral filling vary in response to alterations in left ventricular (LV) relaxation or preload. To determine whether color M-mode Doppler flow Propagation Velocity (vp), a new index of LV relaxation, is affected by preload, we obtained LV volumes, standard Doppler filling indexes, and vp in 20 patients at baseline, during Trendelenburg's position, inverse Trendelenburg's position, and after inhalation of amyl nitrite. LV end-diastolic volume decreased from 111 +/- 41 mL at baseline and 116 +/- 43 mL during Trendelenburg's position, to 104 +/- 40 during inverse Trendelenburg's maneuver and 92 +/- 33 mL after inhalation of amyl nitrite (P <.0001). Peak early filling Velocity decreased from 79 +/- 19 cm/s and 90 +/- 20 cm/s to 73 +/- 22 cm/s and 64 +/- 20 cm/s, respectively (P < 0.0001). In contrast, no significant changes were found in vp (48 +/- 24 and 50 +/- 26 cm/s vs 48 +/- 25 and 48 +/- 25 cm/s). We conclude that vp is not affected significantly by preload. Thus vp may provide a more reliable and independent assessment of LV relaxation.
James D Thomas - One of the best experts on this subject based on the ideXlab platform.
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color m mode doppler flow Propagation Velocity is a preload insensitive index of left ventricular relaxation animal and human validation
Journal of the American College of Cardiology, 2000Co-Authors: Mario J Garcia, Nicholas G Smedira, Neil L Greenberg, Michael L Main, Michael S Firstenberg, Jill Odabashian, James D ThomasAbstract:Abstract OBJECTIVES To determine the effect of preload in color M-mode Doppler flow Propagation Velocity (vp). BACKGROUND The interpretation of Doppler filling patterns is limited by confounding effects of left ventricular (LV) relaxation and preload. Color M-mode vphas been proposed as a new index of LV relaxation. METHODS We studied four dogs before and during inferior caval (IVC) occlusion at five different inotropic stages and 14 patients before and during partial cardiopulmonary bypass. Left ventricular (LV) end-diastolic volumes (LV-EDV), the time constant of isovolumic relaxation (tau), left atrial (LA) pre-A and LV end-diastolic pressures (LV-EDP) were measured. Peak Velocity during early filling (E) and vpwere extracted by digital analysis of color M-mode Doppler images. RESULTS In both animals and humans, LV-EDV and LV-EDP decreased significantly from baseline to IVC occlusion (both p CONCLUSIONS Our results indicate that color M-mode Doppler vpis not affected by preload alterations and confirms that LV relaxation is its main physiologic determinant in both animals during varying lusitropic conditions and in humans with heart disease.
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color m mode doppler flow Propagation Velocity is a preload insensitive index of left ventricular relaxation animal and human validation
Journal of the American College of Cardiology, 2000Co-Authors: Mario J Garcia, Nicholas G Smedira, Neil L Greenberg, Michael L Main, Michael S Firstenberg, Jill Odabashian, James D ThomasAbstract:OBJECTIVES: To determine the effect of preload in color M-mode Doppler flow Propagation Velocity (v(p)). BACKGROUND: The interpretation of Doppler filling patterns is limited by confounding effects of left ventricular (LV) relaxation and preload. Color M-mode v(p) has been proposed as a new index of LV relaxation. METHODS: We studied four dogs before and during inferior caval (IVC) occlusion at five different inotropic stages and 14 patients before and during partial cardiopulmonary bypass. Left ventricular (LV) end-diastolic volumes (LV-EDV), the time constant of isovolumic relaxation (tau), left atrial (LA) pre-A and LV end-diastolic pressures (LV-EDP) were measured. Peak Velocity during early filling (E) and v(p) were extracted by digital analysis of color M-mode Doppler images. RESULTS: In both animals and humans, LV-EDV and LV-EDP decreased significantly from baseline to IVC occlusion (both p < 0.001). Peak early filling (E) Velocity decreased in animals from 56 +/- 21 to 42 +/- 17 cm/s (p < 0.001) without change in v(p) (from 35 +/- 15 to 35 +/- 16, p = 0.99). Results were similar in humans (from 69 +/- 15 to 53 +/- 22 cm/s, p < 0.001, and 37 +/- 12 to 34 +/- 16, p = 0.30). In both species, there was a strong correlation between LV relaxation (tau) and v(p) (r = 0.78, p < 0.001, r = 0.86, p < 0.001). CONCLUSIONS: Our results indicate that color M-mode Doppler v(p) is not affected by preload alterations and confirms that LV relaxation is its main physiologic determinant in both animals during varying lusitropic conditions and in humans with heart disease.
Frederic Sirois - One of the best experts on this subject based on the ideXlab platform.
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high normal zone Propagation Velocity in second generation high temperature superconductor coated conductors with a current flow diverter architecture
Superconductor Science and Technology, 2014Co-Authors: Christian Lacroix, Yannick Lapierre, Jonathan Coulombe, Frederic SiroisAbstract:A high normal zone Propagation Velocity (NZPV) is a desirable feature in second generation (2G) high-temperature superconductor (HTS) coated conductors (CCs) in order to reduce the probability of developing destructive hot spots. In this work we investigated experimentally the impact of inserting a highly resistive layer that partially covers the HTS–stabilizer interface of 2G HTS CCs. This new layer was called a 'current flow diverter' (CFD). The purpose of the CFD is to concentrate the current at the edges of the tape when the current transfers from the HTS to the stabilizer upon a quench event. A series of commercial 2G HTS tapes were modified in order to integrate a CFD into them. Measurements realized on these modified tapes showed that the CFD architecture allowed the NZPV to be enhanced by at least two orders of magnitude in comparison with unmodified commercial tapes. Furthermore, it was shown that the NZPV can be significantly enhanced with a very small increase in the HTS–stabilizer interfacial resistance, which is of prime importance for the reliability of current contacts in real applications.
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concept of a current flow diverter for accelerating the normal zone Propagation Velocity in 2g hts coated conductors
Superconductor Science and Technology, 2014Co-Authors: Christian Lacroix, Frederic SiroisAbstract:In this paper, we propose a slight change in the architecture of second generation (2G) high temperature superconductor (HTS) coated conductors (CCs), in order to accelerate their normal zone Propagation Velocity (NZPV) and reduce the probability of developing hot spots. The concept described in this work is to insert a highly resistive layer (called a ‘current flow diverter’, CFD) at the superconductor–stabilizer interface of the 2G HTS CC. The CFD partially covers this interface, so when a normal zone appears the current that transfers from the superconducting layer to the metallic (stabilizer) layers is forced to circumvent the CFD in order to follow the path of least resistance. This results in a significant increase of the current transfer length and a better spatial distribution of heat generation, that help in increasing the NZPV. According to the numerical model developed in this paper, the CFD architecture allows us to obtain NZPV values of more than 20 m s−1, which is approximately two orders of magnitude faster than what has been measured so far on commercially available 2G HTS CCs. Furthermore, our calculations reveal that, for the same value of interfacial resistance, a tape with the CFD architecture can exhibit an NZPV more than 40 times higher than in the case of a similar tape with a uniform interfacial resistance.
Nina Ajmone Marsan - One of the best experts on this subject based on the ideXlab platform.
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high temporal Velocity encoded mri for the assessment of left ventricular inflow Propagation Velocity comparison with color m mode echocardiography
Journal of Magnetic Resonance Imaging, 2015Co-Authors: Emmeline E Calkoen, Nina Ajmone Marsan, Jeroen J Bax, Pieter J Van Den Boogaard, Arno A W Roest, Albert De Roos, Jos J M WestenbergAbstract:Purpose To develop an alternative method for Vp-assessment using high-temporal Velocity-encoded magnetic resonance imaging (VE-MRI). Left ventricular (LV) inflow Propagation Velocity (Vp) is considered a useful parameter in the complex assessment of LV diastolic function and is measured by Color M-mode echocardiography. Materials and Methods A total of 43 patients diagnosed with ischemic heart failure (61 ± 11 years) and 22 healthy volunteers (29 ± 13 years) underwent Color M-mode echocardiography and VE-MRI to assess the inflow Velocity through the mitral valve (mean interexamination time 14 days). Temporal resolution of VE-MRI was 10.8–11.8 msec. Local LV inflow Velocity was sampled along a 4-cm line starting from the tip of the mitral leaflets and for consecutive sample points the point-in-time was assessed when local Velocity exceeded 30 cm/s. From the position–time relation, Vp was calculated by both the difference quotient (Vp-MRI-DQ) as well as from linear regression (Vp-MRI-LR). Results Good correlation was found between Vp-echo and both Vp-MRI-DQ (r = 0.83, P < 0.001) and Vp-MRI-LR (r = 0.84, P < 0.001). Vp-MRI showed a significant but small underestimation as compared to Vp measured by echocardiography (Vp-MRI-DQ: 5.5 ± 16.2 cm/s, P = 0.008; Vp-MRI-LR: 9.9 ± 15.2 cm/s, P < 0.001). Applying age-related cutoff values for Vp to identify LV impaired relaxation, kappa-agreement with echocardiography was 0.72 (P < 0.001) for Vp-MRI-DQ and 0.69 (P < 0.001) for Vp-MRI-LR. Conclusion High temporal VE-MRI represents a novel approach to assess Vp, showing good correlation with Color M-mode echocardiography. In healthy subjects and patients with ischemic heart failure, this new method demonstrated good agreement with echocardiography to identify LV impaired relaxation. J. Magn. Reson. Imaging 2015.
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left ventricular inflow Propagation Velocity for diastolic function testing head to head comparison between Velocity encoded mri and color m mode doppler echocardiography
Journal of Cardiovascular Magnetic Resonance, 2013Co-Authors: Pieter J Van Den Boogaard, Nina Ajmone Marsan, Albert De Roos, Jos J M WestenbergAbstract:Background The inflow Propagation Velocity (Vprop) of the early filling wave has been proposed as an accurate marker of left ventricular (LV) diastolic function [1]. Traditionally, Color M-mode echo Doppler is used for Vprop-assessment. However, this method has not been validated against an alternative modality such as Velocity-encoded (VE) MRI for assessing Vprop. The purpose of this study was to compare Vprop assessed from high temporal VE MRI with Color M-mode echo Doppler in patients with ischemic cardiomyopathy. Methods
