The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Nobuyuki Ohte - One of the best experts on this subject based on the ideXlab platform.
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Noninvasive Evaluation of the Inertia Force of Late Systolic Aortic Flow
IFMBE Proceedings, 2020Co-Authors: Nobuyuki Ohte, Kiyomi Niki, Kazuaki Wakami, Motoaki Sugawara, Genjiro KimuraAbstract:The inertia force of late systolic Aortic Flow, which is generated by left ventricles with good contraction, may be a crucial parameter through which good left ventricular (LV) systolic function delivers its effect on LV early diastolic performance. We attempted to find noninvasive parameters of the inertia force using 2-dimensional ultrasound speckle tracking imaging of the left ventricle and wave intensity (WI) analysis at the right carotid artery. The LV strain along the long-axis at end-systole had significant correlations with both the LV ejection fraction (r=0.80, p
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abstract 18465 the kinetic energy of left ventricular ejection Flow during late systole produces inertia force of late systolic Aortic Flow and good left ventricular early diastolic function
Circulation, 2016Co-Authors: Junki Yamamoto, Syunsuke Murai, Tomonori Sugiura, Kazuaki Wakami, Shohei Kikuchi, Hiroshi Fujita, Toshihiko Goto, Nobuyuki OhteAbstract:Background: Inertia force of late systolic Aortic Flow (IF), which plays a substantial role for the coupling between left ventricular (LV) contraction and relaxation, may depend on the kinetic energy of ejecting Flow (KE) during late systole (KE-LS). Good LV contraction generated much greater KE during early systole (KE-ES) and the KE-ES should affect the KE-LS. We investigated whether the KE-ES and -LS obtained using Vector Flow Mapping (VFMTM, Hitachi-Aloka) had any relationships with both IF and LV relaxation parameters invasively obtained. Method: Study subjects were 30 patients who underwent diagnostic cardiac catheterization and echocardiography on the same day. Conventional color Doppler images were acquired in the apical 3-chamber view. KE was obtained using the commercially available software (Hitachi-Aloka) (Figure). We divided the LV ejection time into 3 equal phases, then the KE was computed as a sum of KE values frame by frame basis around ES and LS; The ES was defined as the first one-third ...
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abstract 12333 do the patients with inertia force of late systolic Aortic Flow have less incidence of heart failure
Circulation, 2013Co-Authors: Toshihiko Goto, Hachiya Kenta, Tomomitsu Tani, Kazuaki Wakami, Hiroshi Fujita, Takafumi Kato, Nobuyuki OhteAbstract:Inertia force of late systolic Aortic Flow (IF) is observed in the left ventricles (LV) with good systolic function. A lack of IF provokes isolated LV diastolic dysfunction and may be related to th...
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lack of inertia force of late systolic Aortic Flow is a cause of left ventricular isolated diastolic dysfunction in patients with coronary artery disease
Journal of the American College of Cardiology, 2006Co-Authors: Takayuki Yoshida, Hitomi Narita, Kaoru Asada, Hiromichi Miyabe, Tomoaki Saeki, Kazuaki Wakami, Nobuyuki Ohte, Seiichiro Sakata, Genjiro KimuraAbstract:Objectives We investigated whether a lack of inertia force of late systolic Aortic Flow and/or apical asynergy provoke early diastolic dysfunction in patients with coronary artery disease (CAD). Background Left ventricular (LV) isolated diastolic dysfunction is a well-recognized cause of heart failure. Methods We evaluated LV apical wall motion and obtained left ventricular ejection fraction (LVEF) by left ventriculography in 101 patients who underwent cardiac catheterization to assess CAD. We also computed the LV relaxation time constant (Tp) and the inertia force of late systolic Aortic Flow from the LV pressure (P)–first derivative of left ventricular pressure (dP/dt) relation. Using color Doppler echocardiography, we measured the propagation velocity of LV early diastolic filling Flow (Vp). Patients with LVEF ≥50% (preserved systolic function [PSF], n = 83) were divided into 2 subgroups: patients with inertia force (n = 53) and without inertia force (n = 30). No patient with systolic dysfunction (SDF) (LVEF Results The Tp was significantly longer in patients with SDF (85.7 ± 21.0 ms) and with PSF without inertia force (81.1 ± 23.6 ms) than in those with PSF with inertia force (66.3 ± 12.8 ms) (p Conclusions An absence of inertia force in patients with PSF is one of the causes of isolated diastolic dysfunction in patients with CAD. Normal LV apical wall motion is substantial enough to give inertia to late systolic Aortic Flow.
Chris S Malaisrie - One of the best experts on this subject based on the ideXlab platform.
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viscous energy loss in the presence of abnormal Aortic Flow
Magnetic Resonance in Medicine, 2014Co-Authors: Alex J. Barker, James C. Carr, Pim Van Ooij, Krishna C Bandi, Julio Garcia, Mazen Albaghdadi, Patrick M Mccarthy, Robert O Bonow, Jeremy D Collins, Chris S MalaisrieAbstract:Purpose To present a theoretical basis for noninvasively characterizing in vivo fluid-mechanical energy losses and to apply it in a pilot study of patients known to express abnormal Aortic Flow patterns. Methods Four-dimensional Flow MRI was used to characterize laminar viscous energy losses in the aorta of normal controls (n = 12, age = 37 ± 10 yr), patients with Aortic dilation (n = 16, age = 52 ± 8 yr), and patients with Aortic valve stenosis matched for age and Aortic size (n = 14, age = 46 ± 15 yr), using a relationship between the three-dimensional velocity field and viscous energy dissipation. Results Viscous energy loss was elevated significantly in the thoracic aorta in patients with dilated aorta (3.6 ± 1.3 mW, P = 0.024) and patients with Aortic stenosis (14.3 ± 8.2 mW, P < 0.001) compared with healthy volunteers (2.3 ± 0.9 mW). The same pattern of significant differences was seen in the ascending aorta, where viscous energy losses in patients with dilated aortas (2.2 ± 1.1 mW, P = 0.021) and patients with Aortic stenosis (10.9 ± 6.8 mW, P < 0.001) were elevated compared with healthy volunteers (1.2 ± 0.6 mW). Conclusion This technique provides a capability to quantify the contribution of abnormal laminar blood Flow to increased ventricular afterload. In this pilot study, viscous energy loss in patient cohorts was significantly elevated and indicates that cardiac afterload is increased due to abnormal Flow. Magn Reson Med 72:620–628, 2014. © 2013 Wiley Periodicals, Inc.
Alex J. Barker - One of the best experts on this subject based on the ideXlab platform.
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Increased systolic vorticity in the left ventricular outFlow tract is associated with abnormal Aortic Flow formations in Tetralogy of Fallot.
International Journal of Cardiovascular Imaging, 2020Co-Authors: Michal Schäfer, Alex J. Barker, James Jaggers, Gareth J. Morgan, Matthew L. Stone, Lorna P. Browne, Max B. MitchellAbstract:: Aortopathy is a recognized comorbidity of Tetralogy of Fallot (TOF). Aortic Flow in children with repaired TOF is abnormal despite normal Aortic valve anatomy and early surgical repair that results in Aortic size normalization. The purpose of this study was to investigate the Flow hemodynamics inside the left ventricle (LV) of children with repaired TOF using 4D-Flow MRI derived vorticity. Vorticity is the spatial derivative of Flow velocity and is sensitive to anatomic and geometric variations. Vorticity was calculated inside the LV of children with repaired TOF having normal Aortic size (n = 14) and normal controls (n = 10) during systolic ejection phase. All subjects underwent comprehensive biventricular analysis including the MRI based feature-tracking based LV strain analysis and mechanical dyssynchrony. Right ventricular (RV) volumetric indices along with LV mechanical indices were correlated with LV vorticity. All TOF patients had supraphysiologic helical Flow in the ascending aorta. The generated peak systolic vorticity integrated over the LV volume was elevated in TOF group compared to control (median: 1344 vs. 858 s-1, P
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Abnormal Aortic Flow conduction is associated with increased viscous energy loss in patients with repaired tetralogy of Fallot.
European Journal of Cardio-Thoracic Surgery, 2019Co-Authors: Michal Schäfer, Alex J. Barker, James Jaggers, Gareth J. Morgan, Matthew L. Stone, Uyen Truong, Lorna P. Browne, Ladonna Malone, Max B. MitchellAbstract:Objectives Aortopathy in tetralogy of Fallot (TOF) is characterized by increased Aortic stiffness, dilation and reduced left ventricular (LV) function. Repair in infancy normalizes Aortic dimensions in early childhood. Our prior work demonstrated that early TOF repair does not normalize Aortic compliance and that abnormal ascending Aortic Flow patterns are prevalent. The objectives of this study were to: (i) determine whether proximal Aortic Flow-mediated viscous energy loss (EL') is elevated in patients with early TOF repair compared with healthy controls, and (ii) determine whether the degree of EL' is associated with LV function. Methods Forty-one patients post TOF repair with normalized Aortic size and 15 healthy controls underwent 4-dimenisonal-Flow magnetic resonance imaging Flow analysis and EL' assessment. Correlations between EL', Aortic size, and LV function were assessed. Results The TOF group had increased peak systolic thoracic aorta EL' (3.8 vs 1.5 mW, P = 0.004) and increased averaged EL' throughout the cardiac cycle (1.2 vs 0.5 mW, P = 0.003). Peak and mean systolic EL' in the ascending aorta was increased 2-fold in the TOF group compared with control (peak: 2.0 vs 0.9 mW, P = 0.007). Peak EL' measured along the entire thoracic Aortic length correlated with LV ejection fraction (R = -0.45, P = 0.009), indexed LV end-systolic volume (R = -0.40, P = 0.010), and right ventricular end-systolic volume (R = -0.37, P = 0.034). Conclusions Patients with repaired TOF exhibit abnormal Aortic Flow associated with increased EL' in the thoracic aorta. The magnitude of EL' is associated with LV function and volumes. Increased Aortic EL' in TOF is likely due to inherently abnormal LV outFlow geometry and or right ventricular interaction. Reduced Aortic Flow efficiency in TOF increases cardiac work and may be an important factor in long-term cardiac performance.
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viscous energy loss in the presence of abnormal Aortic Flow
Magnetic Resonance in Medicine, 2014Co-Authors: Alex J. Barker, James C. Carr, Pim Van Ooij, Krishna C Bandi, Julio Garcia, Mazen Albaghdadi, Patrick M Mccarthy, Robert O Bonow, Jeremy D Collins, Chris S MalaisrieAbstract:Purpose To present a theoretical basis for noninvasively characterizing in vivo fluid-mechanical energy losses and to apply it in a pilot study of patients known to express abnormal Aortic Flow patterns. Methods Four-dimensional Flow MRI was used to characterize laminar viscous energy losses in the aorta of normal controls (n = 12, age = 37 ± 10 yr), patients with Aortic dilation (n = 16, age = 52 ± 8 yr), and patients with Aortic valve stenosis matched for age and Aortic size (n = 14, age = 46 ± 15 yr), using a relationship between the three-dimensional velocity field and viscous energy dissipation. Results Viscous energy loss was elevated significantly in the thoracic aorta in patients with dilated aorta (3.6 ± 1.3 mW, P = 0.024) and patients with Aortic stenosis (14.3 ± 8.2 mW, P < 0.001) compared with healthy volunteers (2.3 ± 0.9 mW). The same pattern of significant differences was seen in the ascending aorta, where viscous energy losses in patients with dilated aortas (2.2 ± 1.1 mW, P = 0.021) and patients with Aortic stenosis (10.9 ± 6.8 mW, P < 0.001) were elevated compared with healthy volunteers (1.2 ± 0.6 mW). Conclusion This technique provides a capability to quantify the contribution of abnormal laminar blood Flow to increased ventricular afterload. In this pilot study, viscous energy loss in patient cohorts was significantly elevated and indicates that cardiac afterload is increased due to abnormal Flow. Magn Reson Med 72:620–628, 2014. © 2013 Wiley Periodicals, Inc.
Ian R Drexler - One of the best experts on this subject based on the ideXlab platform.
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machine learning derived segmentation of phase velocity encoded cardiovascular magnetic resonance for fully automated Aortic Flow quantification
Journal of Cardiovascular Magnetic Resonance, 2019Co-Authors: Alex Bratt, Meridith P Pollie, Ashley Beecy, Nathan H Tehrani, Noel C F Codella, Rocio Perezjohnston, Maria Chiara Palumbo, Javid Alakbarli, Wayne Colizza, Ian R DrexlerAbstract:Background Phase contrast (PC) cardiovascular magnetic resonance (CMR) is widely employed for Flow quantification, but analysis typically requires time consuming manual segmentation which can require human correction. Advances in machine learning have markedly improved automated processing, but have yet to be applied to PC-CMR. This study tested a novel machine learning model for fully automated analysis of PC-CMR Aortic Flow.
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Machine learning derived segmentation of phase velocity encoded cardiovascular magnetic resonance for fully automated Aortic Flow quantification
Journal of Cardiovascular Magnetic Resonance, 2019Co-Authors: Alex Bratt, Meridith P Pollie, Ashley Beecy, Nathan H Tehrani, Noel C F Codella, Maria Chiara Palumbo, Javid Alakbarli, Wayne Colizza, Rocio Perez-johnston, Ian R DrexlerAbstract:Background Phase contrast (PC) cardiovascular magnetic resonance (CMR) is widely employed for Flow quantification, but analysis typically requires time consuming manual segmentation which can require human correction. Advances in machine learning have markedly improved automated processing, but have yet to be applied to PC-CMR. This study tested a novel machine learning model for fully automated analysis of PC-CMR Aortic Flow. Methods A machine learning model was designed to track Aortic valve borders based on neural network approaches. The model was trained in a derivation cohort encompassing 150 patients who underwent clinical PC-CMR then compared to manual and commercially-available automated segmentation in a prospective validation cohort. Further validation testing was performed in an external cohort acquired from a different site/CMR vendor. Results Among 190 coronary artery disease patients prospectively undergoing CMR on commercial scanners (84% 1.5T, 16% 3T), machine learning segmentation was uniformly successful, requiring no human intervention: Segmentation time was
Marco Francone - One of the best experts on this subject based on the ideXlab platform.
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Aortic Flow after valve sparing root replacement with or without neosinuses reconstruction
The Journal of Thoracic and Cardiovascular Surgery, 2019Co-Authors: Mario Gaudino, Filippo Piatti, Francesco Sturla, Jonathan W Weinsaft, Luca Weltert, Emiliano Votta, Nicola Galea, Ilaria Chirichilli, Antonino Di Franco, Marco FranconeAbstract:Abstract Objectives This study applied advanced 4-dimensional Flow magnetic resonance imaging processing to assess differences in Aortic Flow dynamics after valve sparing root replacement, with and without reconstruction of the Valsalva sinuses. Methods We enrolled patients after valve sparing root replacement with a straight tubular prosthesis (n = 10) or with a prosthesis with Valsalva neosinuses (n = 10); age-matched subjects without cardiovascular diseases served as controls (n = 10). 4-Dimensional Flow magnetic resonance imaging acquisitions were performed on a 3.0T magnetic resonance imaging unit. In-house processing was used to segment the Aortic lumen and extract the volumetric 4-dimensional Flow velocity field. Velocity Flow streamlines were computed to compare the amount of rotational Flow and wall shear stress. Occurrence of abnormal wall shear stress (WSS) was estimated within the descending aorta of each surgical group. Results Physiologic-like sinus vortices were visible in the Aortic root when using the prosthesis with neosinuses, whereas straight tubular graft revealed localized intrados malrotations (P = .003 for organized vortical structures vs neosinuses graft and P Conclusions Re-creation of the sinuses of Valsalva during valve-sparing root replacement is associated with more physiologic Flow and significantly lower WSS in the Aortic root. Lower WSSs in the distal thoracic aorta is a novel finding with potential implications on distal Aortic remodeling.
