Shear-scaling-based approach for irreversible energy loss estimation in stenotic aortic flow – An in vitro study

Gülan, Utku; Binter, Christian; Kozerke, Sebastian; Holzner, Markus

doi:10.1016/j.jbiomech.2017.03.006

Cited by 22 publications

(25 citation statements)

References 23 publications

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“…Although previous work suggests that c S = 0.1 can be used for turbulent aortic flow, this resulted in a large underestimation of the true pressure drop in this study. 10 According to the regression between the turbulence production method and the shear-scaling method, the shear-scaling parameter of c S = 0.243 was found to be more accurate and reduce the underestimation of the pressure drop ( Figure 6). Considering that previous studies have demonstrated that c S in the turbulent flow is ~0.1 regardless of flow rate or valve shape, 10,34,35 we suspect that we obtained a different result because the l 2 norm of the strain rate tensor of the mean velocity field in 4D flow MRI data was overestimated.…”

Section: F I G U R E 5 Comparison Of 4d Flow Mri Pressure Drop Estimamentioning

confidence: 96%

“…Some new methods for the assessment of pressure drop across a stenosis have recently been proposed based on turbulence quantification of the flow. [10][11][12] Because most of the energy loss of the stenotic flow is associated with turbulence in the flow, previous studies have shown that the pressure drop through a constriction can be assessed by quantifying total turbulent kinetic energy (TKE). 12,13 TKE reflects the amount of turbulence in the flow, but as the dissipation is unknown, it is not sufficient to compute the irreversible pressure drop.…”

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confidence: 99%

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Validation of pressure drop assessment using 4D flow MRI‐based turbulence production in various shapes of aortic stenoses

Kvitting

Dyverfeldt

et al. 2018

Magnetic Resonance in Med

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Purpose To validate pressure drop measurements using 4D flow MRI‐based turbulence production in various shapes of stenotic stenoses. Methods In vitro flow phantoms with seven different 3D‐printed aortic valve geometries were constructed and scanned with 4D flow MRI with six‐directional flow encoding (ICOSA6). The pressure drop through the valve was non‐invasively predicted based on the simplified Bernoulli, the extended Bernoulli, the turbulence production, and the shear‐scaling methods. Linear regression and agreement of the predictions with invasively measured pressure drop were analyzed. Results All pressure drop predictions using 4D Flow MRI were linearly correlated to the true pressure drop but resulted in different regression slopes. The regression slope and 95% limits of agreement for the simplified Bernoulli method were 1.35 and 11.99 ± 21.72 mm Hg. The regression slope and 95% limits of agreement for the extended Bernoulli method were 1.02 and 0.74 ± 8.48 mm Hg. The regression slope and 95% limits of agreement for the turbulence production method were 0.89 and 0.96 ± 8.01 mm Hg. The shear‐scaling method presented good correlation with an invasively measured pressure drop, but the regression slope varied between 0.36 and 1.00 depending on the shear‐scaling coefficient. Conclusion The pressure drop assessment based on the turbulence production method agrees well with the extended Bernoulli method and invasively measured pressure drop in various shapes of the aortic valve. Turbulence‐based pressure drop estimation can, as a complement to the conventional Bernoulli method, play a role in the assessment of valve diseases.

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Section: F I G U R E 5 Comparison Of 4d Flow Mri Pressure Drop Estimamentioning

confidence: 96%

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confidence: 99%

Validation of pressure drop assessment using 4D flow MRI‐based turbulence production in various shapes of aortic stenoses

Kvitting

Dyverfeldt

et al. 2018

Magnetic Resonance in Med

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“…It has been shown that turbulence increases the probability of thrombus formation in the cardiovascular system 11 . Since the presence of turbulence is an indicator in assessing the abnormalities in the circulatory system 12 , 13 , studies on assessing blood flow need to consider the influence of vortex formation, disturbed flow and turbulence. To the best of our knowledge, such a study has not yet been conducted in the right atrium.Therefore, the aim of this study was to both qualitatively and quantitatively characterize vortex formation, and to assess the temporal and spatial evolution of vortical structures and their association with wall shear stresses within the healthy human right atrium.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Atrial Vortices Using a Novel Right Heart Model and Possible Implications for Atrial Thrombus Formation

Gülan

Saguner

Akdiş

et al. 2017

Sci Rep

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The main aim of this paper is to characterize vortical flow structures in the healthy human right atrium, their impact on wall shear stresses and possible implications for atrial thrombus formation. 3D Particle Tracking Velocimetry is applied to a novel anatomically accurate compliant silicone right heart model to study the phase averaged and fluctuating flow velocity within the right atrium, inferior vena cava and superior vena cava under physiological conditions. We identify the development of two vortex rings in the bulk of the right atrium during the atrial filling phase leading to a rinsing effect at the atrial wall which break down during ventricular filling. We show that the vortex ring formation affects the hemodynamics of the atrial flow by a strong correlation (ρ = 0.7) between the vortical structures and local wall shear stresses. Low wall shear stress regions are associated with absence of the coherent vortical structures which might be potential risk regions for atrial thrombus formation. We discuss possible implications for atrial thrombus formation in different regions of the right atrium.

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“…The flow rates ranged from around 6.46 to 20.95 L/min, which corresponds to the Reynolds number of 5,262 to 17,065. Although the use of water resulted in a higher Reynolds number, this range still covers the Reynolds number of aortic blood flow of around 5,000 to 10,000 [63][64][65]. In addition, the aortic flow belongs to the highly turbulent flow regime [66], where the viscosity effect is negligible.…”

Section: Discussionmentioning

confidence: 99%

4D Flow MRI quantification of blood flow patterns, turbulence and pressure drop in normal and stenotic prosthetic heart valves

Kvitting

Dyverfeldt

et al. 2019

Magnetic Resonance Imaging

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The self-archived postprint version of this journal article is available at Linköping University Institutional Repository (DiVA): http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-153497 N.B.: When citing this work, cite the original publication.Ha, H., Escobar Kvitting, J., Dyverfeldt, P., Ebbers, T., (2019), 4D Flow MRI quantification of blood flow patterns, turbulence and pressure drop in normal and stenotic prosthetic heart valves, Magnetic Resonance Imaging, 55, 118-127. https://doi. AbstractPurpose -To assess valvular flow characteristics and pressure drop in a variety of normal and stenotic prosthetic heart valves (PHVs) using 4D Flow MRI. Materials and methods-In-vitro flow phantoms with four different PHVs were studied: Medtronic-Hall tilting disc, St. Jude Medical standard bileaflet (STJM), Medtronic CoreValve Evolut R and Edwards SAPIEN 3. The valvular flow characteristics were investigated in normal and stenotic PHVs by using 4D Flow MRI.Results -The results showed that each valve provided a different amount of signal loss in the 4D Flow MRI. The defect size of the signal loss from each valve was 37.5 mm, 39.0 mm, 37.5 mm and 51.0 mm for the Tilting disk, STJM, SAPIEN 3 and CoreValve, respectively.The 4D Flow MRI-based estimation of the elevation of the pressure drop through the stenotic PHV using both Bernoulli-based and turbulence-based methods correlated well with the true values for the Tilting disc, STJM and SAPIEN 3 valve. However, the obstructive hemodynamics in the stenotic CoreValve was not clearly identified due to the large signal void from the long struts, resulting in a severe underestimation of the pressure drop using 4D Flow MRI.Conclusion -The Tilting disc, STJM and SAPIEN 3 valves provided reasonable estimates of peak velocity, turbulence production and the corresponding pressure drop. In contrast, the large strut of the CoreValve and corresponding signal void prevented accurate measurements of the velocity and turbulence production; therefore, 4D Flow MRI prediction of the pressure drop through the CoreValve was not feasible.

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Shear-scaling-based approach for irreversible energy loss estimation in stenotic aortic flow – An in vitro study

Cited by 22 publications

References 23 publications

Validation of pressure drop assessment using 4D flow MRI‐based turbulence production in various shapes of aortic stenoses

Validation of pressure drop assessment using 4D flow MRI‐based turbulence production in various shapes of aortic stenoses

Investigation of Atrial Vortices Using a Novel Right Heart Model and Possible Implications for Atrial Thrombus Formation

4D Flow MRI quantification of blood flow patterns, turbulence and pressure drop in normal and stenotic prosthetic heart valves

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