scholarly journals Impact of Material Stiffness and Anisotropy on Coaptation Characteristics for Aortic Valve Cusps Reconstructed from Pericardium

Mathematics ◽  
2021 ◽  
Vol 9 (18) ◽  
pp. 2193
Author(s):  
Alexey Liogky ◽  
Pavel Karavaikin ◽  
Victoria Salamatova
Keyword(s):  
Aortic Valve ◽  
Diastolic Pressure ◽  
Central Zone ◽  
Aortic Valves ◽  
Material Stiffness ◽  
Numerical Assessment ◽  
Aortic Leaflet ◽  
Membrane Models ◽  
Shell Formulation ◽  
First Time

The numerical assessment of reconstructed aortic valves competence and leaflet design optimization rely on both coaptation characteristics and the diastolic valve configuration. These characteristics can be evaluated by the shell or membrane formulations. The membrane formulation is preferable for surgical aortic valve neocuspidization planning since it is easy to solve. The results on coaptation zone sensitivity to the anisotropy of aortic leaflet material are contradictive, and there are no comparisons of coaptation characteristics based on shell and membrane models for anisotropic materials. In our study, we explore for the first time how the reduced model and anisotropy of the leaflet material affect the coaptation zone and the diastolic configuration of the aortic valve. To this end, we propose the method to mimic the real, sutured neo-leaflet, and apply our numerical shell and membrane formulations to model the aortic valve under the quasi-static diastolic pressure varying material stiffness and anisotropy directions. The shell formulation usually provides a lesser coaptation zone than the membrane formulation, especially in the central zone. The material stiffness does influence the coaptation zone: it is smaller for stiffer material. Anisotropy of the leaflet material does not affect significantly the coaptation characteristics, but can impact the deformed leaflet configuration and produce a smaller displacement.

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.

Thrombocytopenia Associated with Perceval Sutureless Aortic Valve Replacement in Elderly Patients: A Word of Caution

2015 ◽  
Vol 18 (3) ◽  
pp. 093 ◽  
Author(s):  
Turki B. Albacker
Keyword(s):  
Aortic Valve ◽  
Elderly Patients ◽  
Blood Cells ◽  
Slow Recovery ◽  
Aortic Valves ◽  
Significant Drop ◽  
Extreme Caution ◽  
Packed Red Blood Cells ◽  
Transfusion Requirements ◽  
First Time

<p class="p1"><span class="s1"><strong>Objective:</strong> The aim of this study was to report for the first time the phenomenon of thrombocytopenia associated with the use of sutureless aortic valve replacements (AVR), and try to find an explanation for its occurrence.</span></p><p class="p1"><span class="s2"><strong>Methods:</strong> The data was collected retrospectively for all patients who had sutureless AVR (7 patients) and was compared to patients who underwent sutured AVR (22 patients) by the same surgeon between February 2012 and November 2013. </span></p><p class="p1"><span class="s1"><strong>Results:</strong> Cardiopulmonary bypass and cross-clamp durations were shorter in the sutureless group (96.4 min, <br /> 70.6 min) compared to the sutured group (128.3 min, 97.3 min), <br /> (<em>P</em> = .04, <em>P</em> = .003) respectively. Mean transvalvular gradients were lower in the sutureless group (mean = 9.6 mmHg) compared to the sutured group (mean = 17.3 mmHg). Platelet levels were significantly lower in the Perceval patients compared to the Enable patients and sutured valves. Platelet transfusion was higher for sutureless valves (6.5 units versus 5.4 units for the sutured group, <em>P</em> = .63), especially the Perceval valve (7.6 units versus 5.3 for the Enable valve, <em>P</em> = .35), but was not statistically significant. Packed red blood cells (PRBCs) transfusion was significantly higher in the sutureless group (6 units versus 3.1 for the sutured group, <em>P</em> = .002). </span></p><p class="p1"><span class="s1"><strong>Conclusion:</strong> The implantation of sutureless aortic valves, especially the Perceval valve, was associated with a significant drop in platelet count postoperatively with slow recovery and higher PRBCs transfusion requirements. Extreme caution should be taken before the routine use of these valves in elderly patients who are already at risk of thrombocytopenia postoperatively. </span></p>

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.

Temporal trends in utilization of transcatheter aortic valve implantation and patient characteristics – a nationwide cohort study

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
J.E Strange ◽  
C Sindet-Pedersen ◽  
G Gislason ◽  
C Torp-Pedersen ◽  
E.L Fosboel ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Transcatheter Aortic Valve Implantation ◽  
Temporal Trends ◽  
Patient Characteristics ◽  
P Value ◽  
Transcatheter Aortic Valve ◽  
History Of ◽  
Aortic Valve Implantation ◽  
Valve Implantation ◽  
First Time

Abstract Introduction In recent years, there has been a surge in the utilization of transcatheter aortic valve implantation (TAVI) for the treatment of severe symptomatic aortic stenosis. Randomized controlled trials have compared TAVI to surgical aortic valve replacement (SAVR) in patients at high-, intermediate-, and low perioperative risk. As TAVI continues to be utilized in patients with lower risk profiles, it is important to investigate the temporal trends in “real-world” patients undergoing TAVI. Purpose To investigate temporal trends in the utilization of TAVI and examine changes in patient characteristics of patients undergoing first-time TAVI. Methods Using complete Danish nationwide registries, we included all patients undergoing first-time TAVI between 2008 and 2017. To compare patient characteristics, the study population was stratified according to calendar year in the following groups: 2008–2009, 2010–2011, 2012–2013, 2014–2015, and 2016–2017. Results We identified 3,534 patients undergoing first-time TAVI. In 2008–2009, 180 patients underwent first-time TAVI compared with 1,417 patients in 2016–2017, resulting in a 687% increase in TAVI procedures performed. During the study period, the median age remained stable (2008–2009: Median age 82 year [25th–75th percentile: 78–85] vs. 2016–2017: Median age 81 years [25th–75th percentile: 76–85]; P-value: 0.06). The proportion of men undergoing first-time TAVI increased over the years (2008–2009: 49.4% vs 2016–2017: 54.9%; P-value for trend: &lt;0.05), also the proportion with diabetes increased (2008–2009: 12.2% vs. 2016–2017: 19.3%; P-value for trend: &lt;0.05). The proportion of patients with a history of stroke decreased over the years (2008–2009: 13.9% vs. 2016–2017: 12.1%; P-value for trend: &lt;0.05). The same trend was seen in patients with a history of myocardial infarction (2008–2009: 24.4% vs. 2016–2017: 11.9%; P-value for trend: &lt;0.05), ischaemic heart disease (2008–2009: 71.7% vs. 2016–2017: 29.4%; P-value for trend: &lt;0.05), and heart failure (2008–2009: 45.6% vs. 2016–2017: 29.4%; P-value for trend: &lt;0.05). Conclusions In this nationwide study, there was a marked increase in the utilization of TAVI in the years 2008–2017. Patients undergoing first-time TAVI had a decreasing comorbidity burden, while the age of the patients at first-time TAVI remained stable. Funding Acknowledgement Type of funding source: None

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&lt;0.001), fibronectin (p&lt;0.01), decorin (p&lt;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&lt;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

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