Modeling of Soft Tissue Property Changes Induced by Fatigue Loading

2012 ◽  
Author(s):  
Caitlin Martin ◽  
Wei Sun
Keyword(s):  
Heart Valves ◽  
Fatigue Loading ◽  
Fatigue Properties ◽  
Prosthetic Heart Valves ◽  
Computational Simulations ◽  
Permanent Set ◽  
Mechanical Valves ◽  
Property Changes ◽  
Tissue Specimens

Bio-prosthetic heart valves (BHVs), with glutaraldehyde-treated bovine pericardium (GLBP) leaflets, have been used extensively to replace diseased heart valves. BHVs display superior hemodynamics to mechanical valves; however, their use is limited due to poor durability resulting from in vivo degradation and fatigue damage of the leaflets. Yet, little is known about the fatigue properties of GLBP tissue. Sun et al. [1] has previously studied the effects of fatigue on GLBP tissue specimens which were cyclically stretched up to 65×106 cycles. The fatigued GLBP specimens exhibited altered material properties and geometry (permanent set). Because fatigue experiments are very time-consuming and costly, there is a need to develop predictive models to accurately capture tissue fatigue experimental data. Furthermore, it is desirable that such tissue fatigue models could be incorporated into computational simulations to investigate the effects of complicated loading conditions, such as in BHV applications, on device durability.

Modeling of Tissue Fatigue Damage in Bio-Prosthetic Heart Valve

2011 ◽  
Author(s):  
Caitlin Martin ◽  
Wei Sun
Keyword(s):  
Fatigue Damage ◽  
Heart Valve ◽  
Anticoagulant Therapy ◽  
Heart Valves ◽  
Prosthetic Heart Valve ◽  
Bovine Pericardium ◽  
Prosthetic Heart Valves ◽  
Mechanical Valves ◽  
In Vivo Degradation

Bio-prosthetic heart valves (BHVs) with leaflets made of glutaraldehyde-treated bovine pericardium (GLBP), have been used extensively to replace diseased heart valves. BHVs display superior hemodynamics to mechanical valves and eliminate the need for anticoagulant therapy; however, they exhibit poor durability resulting from in vivo degradation and fatigue damage of the leaflets.

Statistical Analysis of Longevity of Prosthetic Aortic Valves

1976 ◽  
Vol 43 (1) ◽  
pp. 2-7 ◽  
Author(s):  
D. N. Ghista ◽  
Y. K. Lin
Keyword(s):  
Heart Valves ◽  
Prosthetic Heart Valve ◽  
Fatigue Properties ◽  
Prosthetic Heart Valves ◽  
Aortic Valves ◽  
Damage Rate ◽  
Design Charts ◽  
Physiological Fluid ◽  
Fluid Environment

The analysis and procedure for obtaining the average fatigue damage rate, and hence a measure of longevity, of a prosthetic heart valve is presented. Design charts are developed to obtain measures of longevity of prosthetic heart valves, for various values of valve geometry characterizing parameter, valve’s in vivo pressure loading characteristics and the fatigue properties of the valve material. Such design charts can be updated when more reliable information about the fatigue properties of valve material (in a physiological fluid environment) becomes available.

scholarly journals Bioprosthetic Heart Valves: Impact of Implantation on Biomaterials

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Pooja Singhal ◽  
Adriana Luk ◽  
Jagdish Butany
Keyword(s):  
Heart Disease ◽  
Heart Valves ◽  
Prosthetic Heart Valves ◽  
Bioprosthetic Heart Valves ◽  
Modes Of Failure ◽  
Mechanical Valves ◽  
Different Types ◽  
Patient Groups ◽  
Bioprosthetic Valves

Prosthetic heart valves are commonly used in the treatment of valvular heart disease. Mechanical valves are more durable than the bioprosthetic valves; however, the need for long-term anticoagulant therapy renders them unsuitable for some patient groups. In this paper we discuss the different types and models of bioprosthesis, and in particular, pericardial bioprosthesis. We also discuss the preimplantation preparation processes, as well as their postimplantation changes and modes of failure.

scholarly journals SIBS triblock copolymers in cardiac surgery: in vitro and in vivo studies in comparison with ePTFE

2020 ◽  
Vol 21 (4) ◽  
pp. 67-80
Author(s):  
M. A. Rezvova ◽  
E. A. Ovcharenko ◽  
P. A. Nikishev ◽  
S. V. Kostyuk ◽  
L. V. Antonova ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Heart Valves ◽  
Ex Vivo ◽  
Calcium Content ◽  
Positive Control ◽  
Prosthetic Heart Valves ◽  
Solution Casting Method ◽  
Cell Adhesion And Proliferation

Implantation of polymeric heart valves can solve the problems of existing valve substitutes – mechanical and biological. Objective: to comprehensively assess the hemocompatibility of styrene-isobutylene-styrene (SIBS) triblock copolymer, synthesized by controlled cationic polymerization in comparison with expanded polytetrafluoroethylene (ePTFE) used in clinical practice. Materials and methods. SIBS-based films were made by polymer solution casting method; in vitro biocompatibility assessment was performed using cell cultures, determining cell viability, cell adhesion and proliferation; tendency of materials to calcify was determined through in vitro accelerated calcification; in vivo biocompatibility assessment was performed by subcutaneous implantation of rat samples; hemocompatibility was determined ex vivo by assessing the degree of hemolysis, aggregation, and platelet adhesion. Results. The molecular weight of synthesized polymer was 33,000 g/mol with a polydispersity index of 1.3. When studying cell adhesion, no significant differences (p = 0.20) between the properties of the SIBS polymer (588 cells/mm2) and the properties of culture plastics (732 cells/mm2) were discovered. Cell adhesion for the ePTFE material was 212 cells/mm2. Percentage of dead cells on SIBS and ePTFE samples was 4.40 and 4.72% (p = 0.93), respectively, for culture plastic – 1.16% (p < 0.05). Cell proliferation on the ePTFE surface (0.10%) was significantly lower (p < 0.05) than for the same parameters for SIBS and culture plastic (62.04 and 44.00%). Implantation results (60 days) showed the formation of fibrous capsules with average thicknesses of 42 μm (ePTFE) and 58 μm (SIBS). Calcium content in the explanted samples was 0.39 mg/g (SIBS), 1.25 mg/g (ePTFE) and 93.79 mg/g (GA-xenopericardium) (p < 0.05). Hemolysis level of red blood cells after contact with SIBS was 0.35%, ePTFE – 0.40%, which is below positive control (p < 0.05). Maximum platelet aggregation of intact platelet-rich blood plasma was 8.60%, in contact with SIBS polymer – 18.11%, with ePTFE – 22.74%. Conclusion. In terms of hemocompatibility properties, the investigated SIBS polymer is not inferior to ePTFE and can be used as a basis for development of polymeric prosthetic heart valves.

Valvular prostheses

2021 ◽  
pp. 251-270
Author(s):  
Luigi P. Badano ◽  
Denisa Muraru
Keyword(s):  
Biological Tissue ◽  
Heart Valves ◽  
Effective Orifice Area ◽  
Prosthetic Heart Valves ◽  
Aortic Valves ◽  
Orifice Area ◽  
Mechanical Valves ◽  
Stentless Bioprostheses ◽  
Closed Position ◽  
Open Position

Prosthetic heart valves may be mechanical or bioprosthetic. Mechanical valves, which are composed primarily of metal or carbon alloys, are classified according to their design as ball-caged, single-tilting-disc, or bileaflet-tilting-disc valves. In ball-cage valves, the occluder is a sphere which is contained by a metal ‘cage’ when the valve is in its open position, and fills the orifice when the valve is in its closed position. In single-tilting-valves, the occluder is a single circular disc which is constrained in its motion by a cage, a central strut, or a slanted slot in the valve ring, therefore it opens at an angle less than 90° to the sewing ring plane. In bileaflet-tilting-disc valves there two occluders, two semicircular discs that open forming three orifices, a central one and two lateral ones. Biological tissue valves prostheses may be heterografts, which are composed of porcine, bovine, or equine tissue (valvular or pericardial), or homografts, which are preserved human aortic valves. Heterografts include stented and stentless bioprostheses. In stented valves, the biological tissue of the valve is mounted on a rigid stent (plastic or metallic) covered with fabric. Conversely stentless bioprostheses use the patient’s native aortic root as the valve stent. The absence of a stent and sewing ring cuff make it possible to implant a larger valve for a given native annulus size, resulting in a larger effective orifice area (EOA).

In Vivo Observation of Cavitation on Prosthetic Heart Valves

ASAIO Journal ◽  
1996 ◽  
Vol 42 (5) ◽  
pp. M550-554 ◽  
Author(s):  
CONRAD M. ZAPANTA ◽  
DAVID R. STINEBRING ◽  
DEBORAH S. SNECKENBERGER ◽  
STEVEN DEUTSCH ◽  
DAVID B. GESELOWITZ ◽  
...  
Keyword(s):  
Heart Valves ◽  
Prosthetic Heart Valves

An Experimental Study of the Flow-Induced Mass Transfer Distribution in the Vicinity of Prosthetic Heart Valves

1981 ◽  
Vol 103 (1) ◽  
pp. 1-10 ◽  
Author(s):  
F. L. Galanga ◽  
J. R. Lloyd
Keyword(s):  
Mass Transfer ◽  
Experimental Study ◽  
Heart Valves ◽  
Electrochemical Techniques ◽  
Reynolds Numbers ◽  
In Vivo Studies ◽  
High Mass ◽  
Prosthetic Heart Valves ◽  
Disk Valve

An experimental study of the flow-induced mass transfer distribution in the vicinity of a model disk valve and a ball valve was conducted using electrochemical techniques. Reynolds numbers ranged from 1000 to 6000, which are characteristic of physiologic conditions. Local instantaneous and time average data are presented. It was found that the flow-induced mass transfer distribution was high in regions of both low and high shear. It was also demonstrated that the fluctuations in the mass transfer to the wall of the test section around the valve are significantly affected by valve design. The regions of high mass transfer measured in this study were found to correlate very closely to regions where thrombus formations have been documented in in-vivo studies.

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