The E-wave propagation index (EPI): A novel echocardiographic parameter for prediction of left ventricular thrombus. Derivation from computational fluid dynamic modeling and validation on human subjects

Harfi, Thura T.; Seo, Jong Hyun; Yasir, Hayder S.; Welsh, Nathaniel; Mayer, Susan A.; Abraham, Theodore P.; George, Richard Т. De; Mittal, Rajat

doi:10.1016/j.ijcard.2016.10.079

Cited by 23 publications

(29 citation statements)

References 14 publications

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“…It is evident that the large-scale recirculation is strongly determined by the specific valve model, and in the case of a mechanical valve, the large-scale vortex does not reach the ventricle apex. It is worth mentioning that for all of the three cases of figure 30, the E-wave propagation index (EPI) described in Harfi et al (2017) would be nearly identical since it is given by the ratio of the propagation length of the mitral jet, L MJ , and the vertical length of the ventricle at the maximum expansion, L LV . As shown by Harfi et al (2017), for all practical purposes, L MJ can be estimated in echocardiography through the velocity time integral VTI = T E 0 V M (t) dt, where T E is the duration of the early wave and V M is the jet velocity at the mitral leaflets.…”

Section: Discussionmentioning

confidence: 98%

“…It is worth mentioning that for all of the three cases of figure 30, the E-wave propagation index (EPI) described in Harfi et al (2017) would be nearly identical since it is given by the ratio of the propagation length of the mitral jet, L MJ , and the vertical length of the ventricle at the maximum expansion, L LV . As shown by Harfi et al (2017), for all practical purposes, L MJ can be estimated in echocardiography through the velocity time integral VTI = T E 0 V M (t) dt, where T E is the duration of the early wave and V M is the jet velocity at the mitral leaflets. Since all of the inflows are identical and L LV depends on the ejection fraction, in all cases, the E-wave propagation index is the same and indeed a direct calculation for Flow induced by natural and prosthetic mitral valves 299 EF = 40 % yields EPI = 1.24, 1.35 and 1.31 respectively for the natural, biological and mechanical valves.…”

Section: Discussionmentioning

confidence: 98%

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Flow structure in healthy and pathological left ventricles with natural and prosthetic mitral valves

Meschini

Tullio²,

Querzoli

et al. 2017

J. Fluid Mech.

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In this paper, the structure and the dynamics of the flow in the left heart ventricle are studied for different pumping efficiencies and mitral valve types (natural, biological and mechanical prosthetic). The problem is investigated by direct numerical simulation of the Navier-Stokes equations, two-way coupled with a structural solver for the ventricle and mitral valve dynamics. The whole solver is preliminarily validated by comparisons with ad hoc experiments. It is found that the system works in a highly synergistic way and the left ventricular flow is heavily affected by the specific type of mitral valve, with effects that are more pronounced for ventricles with reduced pumping efficiency. When the ventricle ejection fraction (ratio of the ejected fluid volume to maximum ventricle volume over the cycle) is within the physiological range (50 %-70 %), regardless of the mitral valve geometry, the mitral jet sweeps the inner ventricle surface up to the apex, thus preventing undesired flow stagnation. In contrast, for pathological ejection fractions ( 40 %), the flow disturbances introduced by the bileaflet mechanical valve reduce the penetration capability of the mitral jet and weaken the recirculation in the ventricular apex. Although in clinical practice the fatality rates in the five-year follow-ups for mechanical and biological mitral valve replacements are essentially the same, a breakdown of the deaths shows that the causes are very different for the two classes of prostheses and the present findings are consistent with the clinical data. This might have important clinical implications for the choice of prosthetic device in patients needing mitral valve replacement.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 98%

Flow structure in healthy and pathological left ventricles with natural and prosthetic mitral valves

Meschini

Tullio²,

Querzoli

et al. 2017

J. Fluid Mech.

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“…11). The values of Y v /Y LV , A v / A LV , EPI, and VFT are comparable to those of healthy LVs [2,26,50]. Hence, the flow analysis predicts that the LVT will likely resolve and the patient will be at low risk of LVT relapse if anticoagulation is discontinued.…”

Section: Patient-specific Discussionmentioning

confidence: 70%

“…6. Table 1 provides the LVT status, ejection fraction (EF), the Doppler-derived E-wave propagation index (EPI) [50], and the vortex formation time (VFT) [2]. EPI is the ratio between the time integral of velocity at the mitral annulus during the E-wave and the length of the LV.…”

Section: Resultsmentioning

confidence: 99%

“…EPI is the ratio between the time integral of velocity at the mitral annulus during the E-wave and the length of the LV. It has been shown [50] as an indicator of LVT formation. Cases with EPI > 1.5 are classified as normal, i.e., the flow has enough momentum to penetrate to the LV apex; EPI$1 represents borderline apical flow and EPI < 1 is considered high risk for LVT formation.…”

Section: Resultsmentioning

confidence: 99%

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Optimized Time-Resolved Echo Particle Image Velocimetry– Particle Tracking Velocimetry Measurements Elucidate Blood Flow in Patients With Left Ventricular Thrombus

Sampath¹,

Harfi

George

et al. 2018

Journal of Biomechanical Engineering

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Contrast ultrasound is a widely used clinical tool to obtain real-time qualitative blood flow assessments in the heart, liver, etc. Echocardiographic particle image velocimetry (echo-PIV) is a technique for obtaining quantitative velocity maps from contrast ultrasound images. However, unlike optical particle image velocimetry (PIV), routine echo images are prone to nonuniform spatiotemporal variations in tracer distribution, making analysis difficult for standard PIV algorithms. This study introduces optimized procedures that integrate image enhancement, PIV, and particle tracking velocimetry (PTV) to obtain reliable time-resolved two-dimensional (2D) velocity distributions. During initial PIV analysis, multiple results are obtained by varying processing parameters. Optimization involving outlier removal and smoothing is used to select the correct vector. These results are used in a multiparameter PTV procedure. To demonstrate their clinical value, the procedures are implemented to obtain velocity and vorticity distributions over multiple cardiac cycles using images acquired from four left ventricular thrombus (LVT) patients. Phase-averaged data elucidate flow structure evolution over the cycle and are used to calculate penetration depth and strength of left ventricular (LV) vortices, as well as apical velocity induced by them. The present data are consistent with previous time-averaged results for the minimum vortex penetration depth associated with LVT occurrence. However, due to decay and fragmentation of LV vortices, as they migrate away from the mitral annulus, in two cases with high penetration, there is still poor washing near the resolved clot throughout the cycle. Hence, direct examination of entire flow evolution may be useful for assessing risk of LVT relapse before prescribing anticoagulants.

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Turbulent blood dynamics in the left heart in the presence of mitral regurgitation: a computational study based on multi-series cine-MRI

Bennati

Giambruno

Renzi

et al. 2023

Biomech Model Mechanobiol

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In this work, we performed a computational image-based study of blood dynamics in the whole left heart, both in a healthy subject and in a patient with mitral valve regurgitation. We elaborated multi-series cine-MRI with the aim of reconstructing the geometry and the corresponding motion of left ventricle, left atrium, mitral and aortic valves, and aortic root of the subjects. This allowed us to prescribe such motion to computational blood dynamics simulations where, for the first time, the whole left heart motion of the subject is considered, allowing us to obtain reliable subject-specific information. The final aim is to investigate and compare between the subjects the occurrence of turbulence and the risk of hemolysis and of thrombi formation. In particular, we modeled blood with the Navier–Stokes equations in the arbitrary Lagrangian–Eulerian framework, with a large eddy simulation model to describe the transition to turbulence and a resistive method to manage the valve dynamics, and we used a finite element discretization implemented in an in-house code for the numerical solution.

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The E-wave propagation index (EPI): A novel echocardiographic parameter for prediction of left ventricular thrombus. Derivation from computational fluid dynamic modeling and validation on human subjects

Cited by 23 publications

References 14 publications

Flow structure in healthy and pathological left ventricles with natural and prosthetic mitral valves

Flow structure in healthy and pathological left ventricles with natural and prosthetic mitral valves

Optimized Time-Resolved Echo Particle Image Velocimetry– Particle Tracking Velocimetry Measurements Elucidate Blood Flow in Patients With Left Ventricular Thrombus

Turbulent blood dynamics in the left heart in the presence of mitral regurgitation: a computational study based on multi-series cine-MRI

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