A novel computational model for the hemodynamics of bileaflet mechanical valves in the opening phase

Jahandardoost, Mehdi; Fradet, Guy; Mohammadi, Hadi

doi:10.1177/0954411915576944

Cited by 15 publications

(22 citation statements)

References 37 publications

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“…The reported results in this study are in good agreement with previous studies in the literature. For a normally functioning BMHV, numerical simulations mostly reported the velocity fields in the ascending aorta, TAWSS and OSI on valve leaflets and AVSS . Their findings are in a good agreement with our experimental results.…”

Section: Discussionsupporting

confidence: 88%

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Experimental investigation of the flow downstream of a dysfunctional bileaflet mechanical aortic valve

et al. 2019

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Mechanical heart valve replacement is the preferred alternative in younger patients with severe symptomatic aortic valve disease. However, thrombus and pannus formations are common complications associated with bileaflet mechanical heart valves.This leads to risks of valve leaflet dysfunction, a life-threatening event. In this experimental study, we investigate, using time-resolved planar particle image velocimetry, the flow characteristics in the ascending aorta in the presence of a dysfunctional bileaflet mechanical heart valve. Several configurations of leaflet dysfunction are investigated and the induced flow disturbances in terms of velocity fields, viscous energy dissipation, wall shear stress, and accumulation of viscous shear stresses are evaluated. We also explore the ability of a new set of parameters, solely based on the analysis of the normalized axial velocity profiles in the ascending aorta, to detect bileaflet mechanical heart valve dysfunction and differentiate between the different configurations tested in this study. Our results show that a bileaflet mechanical heart valve dysfunction leads to a complex spectrum of flow disturbances with each flow characteristic evaluated having its own worst case scenario in terms of dysfunction configuration. We also show that the suggested approach based on the analysis of the normalized axial velocity profiles in the ascending aorta has the potential to clearly discriminate not only between normal and dysfunctional bilealfet heart valves but also between the different leaflet dysfunction configurations. This approach could be easily implemented using phase-contrast MRI to follow up patients with bileaflet mechanical heart valves. K E Y W O R D Sbileaflet mechanical heart valve, flow dynamics, shear stress accumulation, valve dysfunction, viscous energy dissipation E250 | DARWISH et Al.

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Section: Discussionsupporting

confidence: 88%

“…From a fluid mechanics point‐of‐view, several studies have investigated the flow downstream of a BMHV under normal conditions . An excellent review can be found in .…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the flow downstream of a dysfunctional bileaflet mechanical aortic valve

et al. 2019

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“…7 We also developed a computational platform where the hemodynamic performance of the bileaflet MHVs in the opening phase can be evaluated. 8 In this study, we assessed the hemodynamics of the proposed design in more detail using the computational fluid dynamics (CFD) and compare it with the SJM valve in the opening phase. To report the detailed flow structure around the leaflets, we used the shear stress transport (SST) turbulence model.…”

Section: Introductionmentioning

confidence: 99%

Hemodynamic study of the elliptic St. Jude Medical valve: A computational study

Jahandardoost

Fradet

Mohammadi

2016

Proc Inst Mech Eng H

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Despite successful implantation of St. Jude Medical bileaflet mechanical heart valves, red blood cell lysis and thrombogenic complications associated with these types of valves are yet to be addressed. In our previous study, we proposed an elliptic housing where 10% ovality was applied to the housing of St. Jude Medical valves. Our preliminary results suggested that the overall hemodynamic performance of St. Jude Medical valves improved in both the closing and opening phases. In this study, we evaluated the hemodynamics around the leaflets in the opening phase using a more sophisticated computational platform, computational fluid dynamics. Results suggested both lower shear stress and wall shear stress values and an overall improved hemodynamic performance in the proposed design. This improvement is characterized by lower values of shear stress and wall shear stress in the regions downstream of the leaflets, lower pressure drop across the valve and smaller recirculation zones in the sinuses areas. The proposed design may open a new chapter in the concept of design and hemodynamic improvement of the next generation of mechanical heart valves.

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“…In our previous studies, we extensively assessed the hemodynamic performance of the SJM valve in the opening phase using computational fluid dynamics (CFD). Results suggested that SJM valves may be associated with thrombogenic complications around the hinges, on the leading edge of the leaflets and at the sinuses, possibly because of high blood shear stresses, turbulence, and the overall complexity of the hemodynamics in MHVs [6,7].…”

Section: Introductionmentioning

confidence: 99%

Elliptic st. jude bileaflet mechanical heart valves

Mohammadi¹,

Jahandardoost²,

Fradet³

2015

Cardio Vasc Syst

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St. Jude Medical (SJM) bileaflet mechanical valves were approved by the Food and Drug Administration in 1977. The SJM valve design consists of two semicircular leaflets which pivot on hinges. Compared to other mechanical heart valve prostheses such as ball and cage and tilting disk prosthetic valves, it provides good central flow, the leaflets open completely, and the pressure drop across the valve is trivial. However, non-physiological hemodynamics around these valves may lead to red blood cells lysis and therombigenic complications. Also, the regurgitation-flow inSJM valves is almost twice that of the native valves in the aortic position. In this study, we suggest a new design for the stent (housing) of SJM valves in which 15% ovality is applied to the stent whereas its perimeter remains constant. In a pilot study, the hemodynamic performance of the proposed design is analyzed in the closing phaseand compared to that of conventional SJM models. Results show that while the elliptic SJM model offers a shorter closing phase (9.7% shorter), the regurgitation flow remains almost unchanged. In other words, even though the dynamic response of the valve is improved, the regurgitation flow is not decreased. Thus, a more efficient effective orifice area (EOA) is shown to be provided by the proposed model. The preliminary calculations presented in this study justify an improved hemodynamics of elliptic SJM valves compared to conventional models; the proposed design shows promise and merits further development.

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A novel computational model for the hemodynamics of bileaflet mechanical valves in the opening phase

Cited by 15 publications

References 37 publications

Experimental investigation of the flow downstream of a dysfunctional bileaflet mechanical aortic valve

Experimental investigation of the flow downstream of a dysfunctional bileaflet mechanical aortic valve

Hemodynamic study of the elliptic St. Jude Medical valve: A computational study

Elliptic st. jude bileaflet mechanical heart valves

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