scholarly journals Physics-constrained intraventricular vector flow mapping by color Doppler

2021 ◽  
Author(s):  
Florian Vixege ◽  
Alain Berod ◽  
Yunyun Sun ◽  
Simon Mendez ◽  
Olivier Bernard ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Optimization Problem ◽  
Regularization Parameter ◽  
Color Doppler ◽  
Scalar Fields ◽  
Patient Specific ◽  
Polar Coordinate System ◽  
Flow Mapping ◽  
Vector Flow Mapping

Abstract Color Doppler by transthoracic echocardiography creates two-dimensional fan-shaped maps of blood velocities in the cardiac cavities. It is a one-component velocimetric technique since it only returns the velocity components parallel to the ultrasound beams. Intraventricular vector flow mapping (iVFM) is a method to recover the blood velocity vectors from the Doppler scalar fields in an echocardiographic three-chamber view. We improved our iVFM numerical scheme by imposing physical constraints. The iVFM consisted in minimizing regularized Doppler residuals subject to the condition that two fluid-dynamics constraints were satisfied, namely planar mass conservation, and free-slip boundary conditions. The optimization problem was solved by using the Lagrange multiplier method. A finite-difference discretization of the optimization problem, written in the polar coordinate system centered on the cardiac ultrasound probe, led to a sparse linear system. The single regularization parameter was determined automatically for non-supervision considerations. The physics-constrained method was validated using realistic intracardiac flow data from a patient-specific CFD (computational fluid dynamics) model. The numerical evaluations showed that the iVFM-derived velocity vectors were in very good agreement with the CFD-based original velocities, with relative errors ranged between 0.3 and 12%. We calculated two macroscopic measures of flow in the cardiac region of interest, the mean vorticity and mean stream function, and observed an excellent concordance between physics-constrained iVFM and CFD. The capability of physics-constrained iVFM was finally tested with in vivo color Doppler data acquired in patients routinely examined in the echocardiographic laboratory. The vortex that forms during the rapid filling was deciphered. The physics-constrained iVFM algorithm is ready for pilot clinical studies and is expected to have a significant clinical impact on the assessment of diastolic function.

Abstract 15137: Vector Flow Mapping is a Novel Useful Technique in Assessing Inertia Force of Late Systolic Aortic Flow and Left Ventricular Early Diastolic Function

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Kazuaki Wakami ◽  
Kenta Hachiya ◽  
Syunsuke Murai ◽  
Tsuyoshi Ito ◽  
Hiroshi Fujita ◽  
...  
Keyword(s):  
Blood Flow ◽  
Time Constant ◽  
Color Doppler ◽  
Left Ventricular ◽  
Doppler Imaging ◽  
Inertia Force ◽  
Lv Function ◽  
Flow Mapping ◽  
Vector Flow Mapping ◽  
Late Systole

Background: We previously reported that the inertia force (IF) of blood flowing out of left ventricle (LV) during late-systole produces greater LV elastic recoil force and brings faster LV relaxation. Vector flow mapping (VFM TM , Hitachi-Aloka) enables us to see blood flow velocity vectors that are generated from conventional color Doppler imaging data at any phase of cardiac cycle without angle dependency. Using VFM, kinetic energy (KE) of ejecting blood flow during systole at the LV outflow tract (LVOT) can be obtained. Thus, we investigated whether the KE obtained at the LVOT during late systole (KE-ls) had any relations with the IF and invasively obtained LV function parameters. Method: Study subjects were 33 patients who underwent diagnostic cardiac catheterization and echocardiographic examination on the same day. Color Doppler images were acquired in the apical 3-chamber view. The frame rate ranged was from 40 to 51 frames per minute. Data analyses were performed offline using the commercially available software (DAS-RS1 TM, Hitachi-Aloka). A data sampling area was set at the level just below the aortic valve in the LVOT. The KE-ls was computed as the sum of KE values computed in frame by frame basis during late-systole; late-systole was defined as the latter one-third of ejecting time. LV pressure wave was obtained using a catheter-tipped micromanometer, and then, the first derivative of LV pressure (dP/dt) and a time constant τ of LV pressure decay during isovolumic relaxation were calculated. From LV pressure-dP/dt relationships (phase loop), the IF was determined. Results: A significant positive correlation was observed between the KE-ls and the IF (r=0.79, p<0.0001). The log transformed KE-ls had significant correlations with both peak negative dP/dt (r=0.53, p<0.01) and the time constant τ (r=-0.67, p<0.0001). Conclusion: VFM is a new useful technique to see blood flow in the LV chamber. Noninvasively obtained KE-ls using VFM, which may be a noninvasive surrogate for the IF, has significant correlations with the parameters of LV relaxation.

Comparison Among Different High Porosity Stent Configurations: Hemodynamic Effects of Treatment in a Large Cerebral Aneurysm

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Breigh N. Roszelle ◽  
Priya Nair ◽  
L. Fernando Gonzalez ◽  
M. Haithem Babiker ◽  
Justin Ryan ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Simulation ◽  
Cerebral Aneurysms ◽  
Post Treatment ◽  
Patient Specific ◽  
High Porosity ◽  
Velocity Magnitude ◽  
Large Patient ◽  
Aneurysm Model

Whether treated surgically or with endovascular techniques, large and giant cerebral aneurysms are particularly difficult to treat. Nevertheless, high porosity stents can be used to accomplish stent-assisted coiling and even standalone stent-based treatments that have been shown to improve the occlusion of such aneurysms. Further, stent assisted coiling can reduce the incidence of complications that sometimes result from embolic coiling (e.g., neck remnants and thromboembolism). However, in treating cerebral aneurysms at bifurcation termini, it remains unclear which configuration of high porosity stents will result in the most advantageous hemodynamic environment. The goal of this study was to compare how three different stent configurations affected fluid dynamics in a large patient-specific aneurysm model. Three common stent configurations were deployed into the model: a half-Y, a full-Y, and a crossbar configuration. Particle image velocimetry was used to examine post-treatment flow patterns and quantify root-mean-squared velocity magnitude (VRMS) within the aneurysmal sac. While each configuration did reduce VRMS within the aneurysm, the full-Y configuration resulted in the greatest reduction across all flow conditions (an average of 56% with respect to the untreated case). The experimental results agreed well with clinical follow up after treatment with the full-Y configuration; there was evidence of thrombosis within the sac from the stents alone before coil embolization was performed. A computational simulation of the full-Y configuration aligned well with the experimental and in vivo findings, indicating potential for clinically useful prediction of post-treatment hemodynamics. This study found that applying different stent configurations resulted in considerably different fluid dynamics in an anatomically accurate aneurysm model and that the full-Y configuration performed best. The study indicates that knowledge of how stent configurations will affect post-treatment hemodynamics could be important in interventional planning and demonstrates the capability for such planning based on novel computational tools.

P2477Assessment of intraventricular flow dynamics in acute heart failure studied by Vector Flow Mapping

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
K Masuda ◽  
S Minami ◽  
M Stugaard ◽  
A Kozuma ◽  
S Takeda ◽  
...  
Keyword(s):  
Heart Failure ◽  
Diastolic Pressure ◽  
Color Doppler ◽  
Propagation Distance ◽  
Left Ventricular ◽  
Flow Dynamics ◽  
Significant Part ◽  
Flow Mapping ◽  
Vector Flow Mapping ◽  
Ejection Rate

Abstract Background Although left ventricular (LV) flow dynamics should be closely related to LV morphology and function, little is known about how heart failure (HF) changes it. Pathline Analysis (PA), a recently developed software based on Vector Flow Mapping (VFM, Hitachi), enables us to trace the virtual blood particles entering to the LV in diastole and being ejected in systole. We investigated the change of flow dynamics in HF induced in dogs using PA. Methods In 15 open-chest dogs, HF was induced by intracoronary injection of microspheres. Color Doppler images of apical long-axis view were acquired using Prosound F75 (Hitachi) before and after HF and were analyzed by PA. We calculated the ratio of the numbers of entering particles in diastole and ejected particles in systole (ejection rate) and the distance reached by the particles in diastole corrected by the LV long-axis diameter (propagation distance). Apical and basal short axis images were acquired using GE Vivid E9 and were analyzed for peak rotation and peak twist. Results After inducing HF, LV end-diastolic pressure increased from 6±2 to 15±5 mmHg (p<0.001) and ejection fraction (EF), apical peak rotation and peak twist decreased significantly (EF; 58±5 to 36±8%, apical peak rotation; 14±5 to 3±2 degree, peak twist; 19±5 to 6±3 degree, p<0.05, respectively). PA showed most of the entering particles to the LV were ejected in the following systole at the control stage, but in HF, a significant part of the entering particles were not ejected and remained in the LV (Figure). Ejection rate decreased from 50±11 to 26±11% (p<0.001) and the propagation distance decreased from 85±9 to 66±13% (p<0.001) after inducing HF. There were significant relationships between indices obtained by PA and EF and peak twist (Table). Conclusion A significant part of inflow is not ejected directly to the outflow in the next systole and remains in the LV in HF, suggesting inefficient flow dynamics.

Patient-Specific Stented Coronary Bifurcations: Numerical Analysis of Near-Wall Quantities and the Bulk Flow

2013 ◽  
Author(s):  
Claudio Chiastra ◽  
Stefano Morlacchi ◽  
Diego Gallo ◽  
Umberto Morbiducci ◽  
Rubén Cárdenes ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Shear Stress ◽  
Coronary Arteries ◽  
Fluid Dynamic ◽  
Patient Specific ◽  
Wall Region ◽  
Stent Restenosis ◽  
Local Measurements ◽  
In Stent Restenosis

The mechanisms and the causes of the in-stent restenosis process in coronary arteries are not fully understood. One of the most relevant phenomena, which seems to be associated to this process, is an altered hemodynamics in the stented wall region [1]. In vivo local measurements of velocities and their gradients in human coronary arteries are very difficult and can hardly be applied to successfully investigate the fluid dynamic field [1]. Alternatively, virtual models of blood flow in patient-specific coronary arteries allow the study of local fluid dynamics and the computation of the wall shear stress (WSS) and other quantities which can be related to the risk of restenosis.

P3365Relationship between early diastolic intra-ventricular pressure gradient shortly after aortic valve closure estimated by vector flow mapping and left ventricular diastolic untwisting rate in humans

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
T Hozumi ◽  
Y Nozawa ◽  
K Takemoto ◽  
T Nishi ◽  
T Wada ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Speckle Tracking ◽  
Speckle Tracking Echocardiography ◽  
Color Doppler ◽  
Left Ventricular ◽  
Valve Closure ◽  
Flow Mapping ◽  
Vector Flow Mapping ◽  
Diastolic Velocity ◽  
Aortic Valve Closure

Abstract Background Early diastolic suction is an important determinant of early diastolic function. Previous studies using color Doppler M-mode and speckle-tracking echocardiography have shown left ventricular (LV) early diastolic LV untwisting rate is directly related to LV intra-ventricular pressure gradient (IVPG) between LV base and apex during early diastole. Recent introduction of vector flow mapping (VFM) using combination of color Doppler and speckle-tracking echocardiography provides noninvasive and feasible assessment of early diastolic IVPG shortly after aortic valve closure including isovolmic relaxation period (ED-IVPG) in humans. However, relationship between VFM–derived ED-IVPG and early diastolic LV untwisting rate has not been well investigated. Purpose The purpose of this study was to examine relationship between ED-IVPG estimated by VFM and LV untwisting rate by speckle-tracking echocardiography. Methods The study population consists of 66 patients without segmental wall motion abnormality, significant valvular diseases, and atrial fibrillation who underwent echocardiography for evaluation of LV function (age: 60±15 years, LVEF: 49±16%). From the apical long-axis views by color Doppler echocardiography, we analyzed peak ED-IVPG between LV base and apex just after aortic valve closure (figure) using commercially available VFM analysis software (DAS-RS1, Hitachi). We assessed peak early diastolic LV untwisting rate and LV torsion from LV basal and apical short-axis view by speckle-tracking echocardiography. We evaluated correlation between ED-IVPG and LV untwisting rate. We also evaluated correlation between ED-IVPG and peak systolic LV torsion, LV end-diastolic (EDV) and end-systolic volumes (ESV), ejection fraction (EF), early diastolic velocity (E) of LV inflow, average early diastolic velocity (e') of mitral annulus, and average E/e'. Results In all the study patients, ED-IVPG was successfully and quickly evaluated. 1) ED-IVPG correlated well with peak LV untwisting rate (r=0.64, p<0.0001). 2) ED-IVPG significantly correlated with LV torsion, LVEDV, LVESV, and LVEF (r=0.47, r=−0.48, r=−0.46, and r=0.48, respectively, p<0.001). 3) There were no significant correlations between ED-IVPG and other indexes including E, average e', and average E/e'. According to receiver operating characteristic analysis, the best cut-off value of ED-IVPG for determining impaired LV untwisting rate (<80 degrees/s) was found at 0.42 mmHg (sensitivity 81%, specificity 76%, and area under the curve 0.86) ED-IVPG measurement by VFM Conclusions The present results showed that noninvasive VFM-derived peak ED-IVPG shortly after aortic valve closure is related to early diastolic peak LV untwisting rate. ED-IVPG easily and quickly estimated by VFM may be used as an additional index for LV diastolic function.

Intracardiac Vortex Dynamics by High-Frame-Rate Doppler Vortography—In Vivo Comparison With Vector Flow Mapping and 4-D Flow MRI

2017 ◽  
Vol 64 (2) ◽  
pp. 424-432 ◽  
Author(s):  
Julia Faurie ◽  
Mathilde Baudet ◽  
Kondo Claude Assi ◽  
Dominique Auger ◽  
Guillaume Gilbert ◽  
...  
Keyword(s):  
Vortex Dynamics ◽  
Frame Rate ◽  
Flow Mapping ◽  
High Frame Rate ◽  
Vector Flow Mapping ◽  
Flow Mri

scholarly journals Relationship between left ventricular isovolumic relaxation flow patterns and mitral inflow patterns studied by using vector flow mapping

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yu Han ◽  
Liang Huang ◽  
Zhiguo Li ◽  
Na Ma ◽  
Qiaozhen Li ◽  
...  
Keyword(s):  
Color Doppler ◽  
Left Ventricular ◽  
Flow Mapping ◽  
Mitral Inflow ◽  
Vector Flow Mapping ◽  
Significant Relationships ◽  
Large Vortex ◽  
Artery Disease ◽  
Bidirectional Flow ◽  
Isovolumic Relaxation

Abstract The purpose of this study was to investigate the relationship between isovolumic relaxation flow (IRF) patterns in left ventricle (LV) and mitral inflow patterns. Color Doppler loops were acquired for vector flow mapping in apical long-axis view in 57 patients with coronary artery disease, 31 patients with dilated cardiomyopathy, and 58 healthy controls. IRF patterns were classified into three categories: pattern A, apically directed flow; pattern B, bidirectional flow with small scattered vortices; and pattern C, a large vortex. All normals and patients with normal LV filling (n = 10) showed pattern A. Patients with impaired relaxation consisted of 31 (66%) patients having pattern A, 11 (23%) having pattern B, and 5 (11%) having pattern C. Patients with pseudonormal filling included 4 (31%) patients having pattern A, 7 (54%) having pattern B, and 2 (15%) having pattern C. In patients with restrictive filling, 14 (78%) showed pattern C, 4 (22%) showed pattern B, and no patient showed pattern A. IRF patterns were associated with LV filling patterns (χ2 = 52.026, p < 0.001). There are significant relationships between LV filling and IRF patterns. IRF patterns may provide an index for evaluation of LV diastolic function.

scholarly journals A proof-of-concept study of the in-vivo validation of a computational fluid dynamics model of personalized radioembolization

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Raúl Antón ◽  
Javier Antoñana ◽  
Jorge Aramburu ◽  
Ana Ezponda ◽  
Elena Prieto ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Patient Specific ◽  
Percentage Points ◽  
Pet Ct ◽  
Voxel Dosimetry ◽  
Computational Fluid Dynamics Cfd ◽  
Intraarterial Therapy

AbstractRadioembolization (RE) with yttrium-90 (90Y) microspheres, a transcatheter intraarterial therapy for patients with liver cancer, can be modeled computationally. The purpose of this work was to correlate the results obtained with this methodology using in vivo data, so that this computational tool could be used for the optimization of the RE procedure. The hepatic artery three-dimensional (3D) hemodynamics and microsphere distribution during RE were modeled for six 90Y-loaded microsphere infusions in three patients with hepatocellular carcinoma using a commercially available computational fluid dynamics (CFD) software package. The model was built based on in vivo data acquired during the pretreatment stage. The results of the simulations were compared with the in vivo distribution assessed by 90Y PET/CT. Specifically, the microsphere distribution predicted was compared with the actual 90Y activity per liver segment with a commercially available 3D-voxel dosimetry software (PLANET Dose, DOSIsoft). The average difference between the CFD-based and the PET/CT-based activity distribution was 2.36 percentage points for Patient 1, 3.51 percentage points for Patient 2 and 2.02 percentage points for Patient 3. These results suggest that CFD simulations may help to predict 90Y-microsphere distribution after RE and could be used to optimize the RE procedure on a patient-specific basis.

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