Velocity and pressure distributions in the aortic valve

1969 ◽  
Vol 37 (3) ◽  
pp. 587-600 ◽  
Author(s):  
B. J. Bellhouse
Keyword(s):  
Aortic Valve ◽  
Pressure Difference ◽  
Inviscid Flow ◽  
Jet Formation ◽  
Aortic Valves ◽  
Dimensional Solution ◽  
One Dimensional ◽  
Flow Equations ◽  
Pressure Distributions ◽  
Generation Of Vortices

The distribution of pressure in normal and stenosed aortic valves is investigated experimentally with a rigid-walled model placed in a pulsatile water-tunnel, and the experiments are complemented by a one-dimensional solution of the unsteady inviscid-flow equations. In the normal valve, convectively fed vortices are formed in the aortic sinuses; the vortices aid cusp positioning and the prevention of jet formation during valve closure. Aortic valve stenosis is shown to prevent the generation of vortices, causing the formation of a turbulent jet, with reduction of the pressure difference between the inlets (ostia) of the coronary arteries and the ventricle. This pressure difference is calculated for man resting and exercising, and for various degrees of stenosis.

The fluid mechanics of the aortic valve

1969 ◽  
Vol 35 (4) ◽  
pp. 721-735 ◽  
Author(s):  
B. J. Bellhouse ◽  
L. Talbot
Keyword(s):  
Aortic Valve ◽  
Inviscid Flow ◽  
Reversed Flow ◽  
Forward Flow ◽  
Flow Equations ◽  
Vortex Model ◽  
Closure Mechanism ◽  
Spherical Vortex ◽  
Human Aortic Valve ◽  
Trapped Vortex

The closure mechanism of the human aortic valve is investigated experimentally with a rigid-walled model placed in a pulsatile water-tunnel. It is shown that the valve is controlled by a fluid feed-back system incorporating a stagnation point at the downstream end of each sinus and a trapped vortex within it, and that threequarters of the valve's closure is accomplished during forward flow, requiring only very little reversed flow to seal it. The experiments are complemented by solutions of the inviscid-flow equations, based on a Hill spherical vortex model.

An Assessment of Ca-Naphthenate-Epon Mixtures as Standards for Calcium Quantification in Aortic Valve Leaflets

1982 ◽  
Vol 40 ◽  
pp. 390-391
Author(s):  
Kathryn N. Colonna ◽  
Sydney S. Breese ◽  
Susan C. Sellers ◽  
J. David Deck
Keyword(s):  
Aortic Valve ◽  
Aortic Valves ◽  
X Ray ◽  
Aortic Valve Leaflets

Qualitative x-ray microanalytical studies used to demonstrate calcium in bioprosthetic aortic valves have shown that it occurs in a range of morphological forms. A consistent and reproducible standard for measuring calcium was necessary to investigate whether these forms represented varying concentrations of calcium. To provide such a standard, we tested a series of calcium naphthenate-epon mixtures.

Platelet membrane-coated nanoparticles target sclerotic aortic valves in ApoE−/− mice by multiple binding mechanisms under pathological shear stress

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
H Yang ◽  
Y Song ◽  
Z Huang ◽  
J Qian ◽  
Z Pang ◽  
...  
Keyword(s):  
Shear Stress ◽  
Aortic Valve ◽  
Aortic Valve Disease ◽  
Binding Capacity ◽  
Platelet Membrane ◽  
Valve Disease ◽  
Funding Source ◽  
Aortic Valves ◽  
Coated Nanoparticles

Abstract Background Aortic valve disease is the most common valvular heart disease leading to valve replacement. The efficacy of pharmacological therapy for aortic valve disease is limited by the high mechanical stress at the aortic valves impairing the binding rate. We aimed to identify nanoparticle coating with entire platelet membranes to fully mimic their inherent multiple adhesion mechanisms and target the sclerotic aortic valve of apolipoprotein E-deficient (ApoE−/−) mice based on their multiple sites binding capacity under high shear stress. Methods Considering the potent interaction of platelet membrane glycoproteins with components present in sclerotic aortic valves, platelet membrane-coated nanoparticles (PNPs) were synthetized and the binding capacity under high shear stress was evaluated in vitro and in vivo. Results Compared with PNPs bound intensity in the static station, 161%, 59%, and 39% of attached PNPs remained adherent on VWF-, collagen-, and fibrin-coated surfaces under shear stress of 25dyn/cm2 respectively. PNPs demonstrated effectively adhering to von Willebrand factor, collagen and fibrin under shear stresses in vitro. In an aortic valve disease model established in ApoE−/− mice, PNPs group exhibited significant increase of accumulation in the aortic valves compared with PBS and control NP group. PNPs displayed high degrees of proximity or co-localization with vWF, collagen and fibrin, which exhibited good targeting to sclerotic aortic valves by mimicking platelet multiple adhesive mechanisms. Conclusion PNPs could provide a promising platform for the molecular diagnosis and targeting treatment of aortic valve disease. Targeting combination Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): National Natural Science Foundation of China

Presence of adipose tissue in aortic valves from aortic regurgitation patients: pathophysiological role and clinical implications

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
A Sadaba Cipriain ◽  
A.M Navarro Echeverria ◽  
C.R Tiraplegui Garjon ◽  
A Garcia De La Pena Urtasun ◽  
V Arrieta Paniagua ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Aortic Valve ◽  
Aortic Regurgitation ◽  
Systolic Function ◽  
Statistical Significance ◽  
Left Ventricular Systolic Function ◽  
Left Ventricular ◽  
Funding Source ◽  
Matrix Remodeling ◽  
Aortic Valves

Abstract Introduction Adipose tissue is a common constituent of the heart and it is located, without great clinical relevance, frequently in the pericardium. The presence of adipose tissue in the aortic valve is rare, with unknown significance on valve structural properties and function. Aortic regurgitation (AR) is the third most prevalent valve disease, although it is uncommon to find it in isolation. Myxoid degeneration may be the cause or result of AR, although the pathophysiology remains poorly understood. Purpose To describe and characterize the presence of adipose tissue in the aortic valves from a cohort of AR patients. Methods 116 patients undergoing aortic valve replacement due to severe AR were enrolled. We classified them in two groups according to the histological results showing presence or absence of adipose tissue in the aortic valves. In the valve tissue molecular analysis were performed by RT-PCR, Western Blot and ELISA to analyze markers of adipocytes (leptin, adiponectin, resistin), inflammation (Rantes, interleukin-6, interleukin-1β), extracellular matrix remodeling (metalloproteinases-1, -2 and -9), proteoglycans (aggrecan, hyaluronan, lumican, syndecan-1, decorin) and fibrosis (collagens, fibronectin). Results Adipose tissue was found in 63% of the aortic valves analyzed. Baseline characteristics (age, hypertension, dyslipidemia, diabetes, smoking, left ventricular telediastolic diameter, left ventricular systolic function, ascending aorta) were similar in patients presenting valve adipose tissue as compared with patients without valve adipose tissue. Valves containing adipocytes exhibited a higher leptin content (p<0.001), fibronectin (p<0.01), decorin (p<0,0001), hyaluronan (p=0.03), aggrecan (p=0.04) and metalloproteinase 1 (p=0.03). Interestingly, the presence of adipocytes in the valve was positively correlated with valve thickness measured by echocardiogram (Pearson chi2 statistical significance = 26.3345 p<0.001). Conclusion To our knowledge, this is the first study that describes the presence of adipose cells in aortic valves from a cohort of AR patients. Aortic valves containing adipocytes were thicker and exhibited significant higher levels of proteoglycans, suggesting that adipocytes could contribute to the myxomatous degeneration process. Our results propose that the valve adipose tissue could play a role in the pathophysiology of AR. Funding Acknowledgement Type of funding source: Public hospital(s). Main funding source(s): Gobierno de Navarra

scholarly journals Application of Hyperelastic Nodal Force Method to Evaluation of Aortic Valve Cusps Coaptation: Thin Shell vs. Membrane Formulations

Mathematics ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 1450
Author(s):  
Yuri Vassilevski ◽  
Alexey Liogky ◽  
Victoria Salamatova
Keyword(s):  
Aortic Valve ◽  
Finite Elements ◽  
Shell Model ◽  
Thin Shell ◽  
Aortic Valves ◽  
Shear Moduli ◽  
Force Method ◽  
Elastic Potentials ◽  
Shell Analysis ◽  
First Time

Coaptation characteristics are crucial in an assessment of the competence of reconstructed aortic valves. Shell or membrane formulations can be used to model the valve cusps coaptation. In this paper we compare both formulations in terms of their coaptation characteristics for the first time. Our numerical thin shell model is based on a combination of the hyperelastic nodal forces method and the rotation-free finite elements. The shell model is verified on several popular benchmarks for thin-shell analysis. The relative error with respect to reference solutions does not exceed 1–2%. We apply our numerical shell and membrane formulations to model the closure of an idealized aortic valve varying hyperelasticity models and their shear moduli. The coaptation characteristics become almost insensitive to elastic potentials and sensitive to bending stiffness, which reduces the coaptation zone.

Essential Ingredients for the Computation of Steady and Unsteady Blade Boundary Layers

1991 ◽  
Vol 113 (4) ◽  
pp. 608-616 ◽  
Author(s):  
H. M. Jang ◽  
J. A. Ekaterinaris ◽  
M. F. Platzer ◽  
T. Cebeci
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Stokes Equations ◽  
Inviscid Flow ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Transitional Region ◽  
Low Reynolds Numbers ◽  
Flow Equations ◽  
Low Reynolds

Two methods are described for calculating pressure distributions and boundary layers on blades subjected to low Reynolds numbers and ramp-type motion. The first is based on an interactive scheme in which the inviscid flow is computed by a panel method and the boundary layer flow by an inverse method that makes use of the Hilbert integral to couple the solutions of the inviscid and viscous flow equations. The second method is based on the solution of the compressible Navier–Stokes equations with an embedded grid technique that permits accurate calculation of boundary layer flows. Studies for the Eppler-387 and NACA-0012 airfoils indicate that both methods can be used to calculate the behavior of unsteady blade boundary layers at low Reynolds numbers provided that the location of transition is computed with the en method and the transitional region is modeled properly.

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