Experimental study of an asymmetric heart valve prototype

Vukicevic, Marija; Fortini, Stefania; Querzoli, Giorgio; Espa, Stefania; Pedrizzetti, Gianni

doi:10.1016/j.euromechflu.2012.01.014

Cited by 19 publications

(14 citation statements)

References 7 publications

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“…1(b)) of the LV, the negative-signed vortex of the pair interacts with the wall boundary, causing it to move slower than the positive-signed vortex, thereby leading to asymmetry about the centerline of the inflow jet. This phenomenon has also been observed previously by Pierrakos and Vlachos [4] and Vukićević et al [20]. The maximum velocity at peak E-wave for the D-and O-shaped annulus was measured to be 1.15 and 1.20 m/s, respectively.…”

Section: Intraventricular Flowsupporting

confidence: 88%

“…A considerable number of experimental studies using LV physical models [1,4,20,41] have commonly used MV prostheses with circular annulus geometries to study intraventricular filling patterns. This study represents the first one to address the effect of the mitral annulus change in geometry on the left ventricular filling process and efficiency.…”

Section: Discussionmentioning

confidence: 99%

“…Several types of PHVs for the mitral position are currently available [13][14][15], the most common of which include bileaflet ("three-jet" orifice) and bioprosthetic (circular orifice) designs. Previous studies on PHVs intended for the mitral position have investigated the LV filling fluid mechanics using bileaflet, tilting disk, and monoleaflet designs [11,16,17], as well as using PHVs with asymmetric leaflet lengths as observed in the native MV [18][19][20]. However, most of the studies of LV fluid mechanics employing physical and computational models (excluding in vivo studies) are limited to using a circular mitral annulus as a fundamental assumption.…”

Section: Introductionmentioning

confidence: 99%

“…Most annuloplasty rings used in present day clinical procedures are designed considering structural factors, such as leaflet stress distribution during annulus interaction with the time-varying motion of the left heart complex, and eventual surgical selection is made based on matching with patient-specific anatomy and ease of positioning. Though annuloplasty rings have historically been designed with primarily structural considerations, recent studies using different shapes of mitral prostheses have shown that the shape of the orifice can adversely impact the energetics of LV filling [4,20]. It is thus important to consider both the structural and fluid dynamic interactions of the MV complex with the LV while designing prosthetic devices.…”

Section: Introductionmentioning

confidence: 99%

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Role of Mitral Annulus Diastolic Geometry on Intraventricular Filling Dynamics

Okafor

Santhanakrishnan

Raghav

et al. 2015

Journal of Biomechanical Engineering

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The mitral valve (MV) is a bileaflet valve positioned between the left atrium and ventricle of the heart. The annulus of the MV has been observed to undergo geometric changes during the cardiac cycle, transforming from a saddle D-shape during systole to a flat (and less eccentric) D-shape during diastole. Prosthetic MV devices, including heart valves and annuloplasty rings, are designed based on these two configurations, with the circular design of some prosthetic heart valves (PHVs) being an approximation of the less eccentric, flat D-shape. Characterizing the effects of these geometrical variations on the filling efficiency of the left ventricle (LV) is required to understand why the flat D-shaped annulus is observed in the native MV during diastole in addition to optimizing the design of prosthetic devices. We hypothesize that the D-shaped annulus reduces energy loss during ventricular filling. An experimental left heart simulator (LHS) consisting of a flexible-walled LV physical model was used to characterize the filling efficiency of the two mitral annular geometries. The strength of the dominant vortical structure formed and the energy dissipation rate (EDR) of the measured fields, during the diastolic period of the cardiac cycle, were used as metrics to quantify the filling efficiency. Our results indicated that the O-shaped annulus generates a stronger (25% relative to the D-shaped annulus) vortical structure than that of the D-shaped annulus. It was also found that the O-shaped annulus resulted in higher EDR values throughout the diastolic period of the cardiac cycle. The results support the hypothesis that a D-shaped mitral annulus reduces dissipative energy losses in ventricular filling during diastole and in turn suggests that a symmetric stent design does not provide lower filling efficiency than an equivalent asymmetric design.

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Section: Intraventricular Flowsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Role of Mitral Annulus Diastolic Geometry on Intraventricular Filling Dynamics

Okafor

Santhanakrishnan

Raghav

et al. 2015

Journal of Biomechanical Engineering

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“…Moreover, McQueen & Peskin (2000) and Mihalef et al (2011) have studied the effect of combining realistic intra-ventricular flow with a physiological mitral valve using patient-specific models without fluid-structure interaction. Vukićević et al (2012) underlined the role of the asymmetrical structure of the native mitral valve and investigated the flow generated by a mechanical asymmetrical prosthesis. Recently, Seo et al (2014) have analysed how the morphology and kinematics of the mitral valve can affect the left ventricular flow using a physiological mitral valve.…”

mentioning

confidence: 99%

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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Biomechanics in AIMETA

Bisegna

Parenti‐Castelli²,

Pedrizzetti³

2022

50+ Years of AIMETA

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This chapter aims at presenting a concise picture of the research in Biomechanics developed by researchers of various disciplinary areas that refer to AIMETA. The research collectors are the international journal Meccanica, published by Springer, and the AIMETA congresses including publications of studies presented therein. This chapter is devoted to studies related to AIMETA activity and mainly refers to the topics from the above-mentioned sources. Final comments and future developments are outlined. Keywords Biomechanics • Biological tissues • Articular biomechanics • Medical devices • Biological fluid mechanics • Cardiovascular mechanics 1 Introduction, from Mechanics to Biomechanics Biomechanics is the science that studies the structure and function of biological systems using methods and knowledge of Mechanics. The birth of Biomechanics can be dated back to the first studies of Aristotle (384-322 BC) and later developed by Galen (129-210), Leonardo da Vinci (1452-1519), Galileo Galilei (1564-1642), and Giovanni Alfonso Borelli (1608-1679, up to a few further advancements through the nineteenth and twentieth centuries. It found in the last 50 years a rebirth of interests that became an exponential growth in the last 20 years. In the 50's of the past century, it was in fact considered a subject for

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Experimental study of an asymmetric heart valve prototype

Cited by 19 publications

References 7 publications

Role of Mitral Annulus Diastolic Geometry on Intraventricular Filling Dynamics

Role of Mitral Annulus Diastolic Geometry on Intraventricular Filling Dynamics

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

Biomechanics in AIMETA

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