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.

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.

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.

scholarly journals Hemodynamic Performance of Dysfunctional Prosthetic Heart Valve with the Concomitant Presence of Subaortic Stenosis: In Silico Study

2020 ◽  
Vol 7 (3) ◽  
pp. 90
Author(s):  
Othman Smadi ◽  
Anas Abdelkarim ◽  
Samer Awad ◽  
Thakir D. Almomani
Keyword(s):  
Early Detection ◽  
Heart Valve ◽  
Heart Valves ◽  
Cfd Simulation ◽  
Treatment Plan ◽  
Mechanical Heart Valve ◽  
Prosthetic Heart Valve ◽  
Subaortic Stenosis ◽  
Prosthetic Heart Valves ◽  
The Impact

The prosthetic heart valve is vulnerable to dysfunction after surgery, thus a frequent assessment is required. Doppler electrocardiography and its quantitative parameters are commonly used to assess the performance of the prosthetic heart valves and provide detailed information on the interaction between the heart chambers and related prosthetic valves, allowing early detection of complications. However, in the case of the presence of subaortic stenosis, the accuracy of Doppler has not been fully investigated in previous studies and guidelines. Therefore, it is important to evaluate the accuracy of the parameters in such cases to get early detection, and a proper treatment plan for the patient, at the right time. In the current study, a CFD simulation was performed for the blood flow through a Bileaflet Mechanical Heart Valve (BMHV) with concomitant obstruction in the Left Ventricle Outflow Tract (LVOT). The current study explores the impact of the presence of the subaortic on flow patterns. It also investigates the accuracy of (BMHV) evaluation using Doppler parameters, as proposed in the American Society of Echocardiography (ASE) guidelines.

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.

Warfarin Versus Warfarin and Dipyridamole on the Incidence of Arterial Throms Embolism in Prosthetic Heart Valve Patients

1979 ◽  
Author(s):  
S.M. Rajah ◽  
N. Sreeharan ◽  
S. Rao ◽  
D.A. Watson
Keyword(s):  
Atrial Fibrillation ◽  
Heart Valves ◽  
Prosthetic Heart Valve ◽  
Prosthetic Heart Valves ◽  
Post Mortem ◽  
Randomised Study ◽  
Yearly Incidence ◽  
The Mean ◽  
Prospective Randomised Study

The effect of Warfarin (W) was compared with a combination of Warfarin and Dipyridamole (W+D) on the incidence of arterial thrombo-embolism in patients with prosthetic heart valves in a prospective randomised study. Sixty-four and 53 patients were allocated to W and W+D. The two groups were comparable as regards age, sex, arrhythmias and site and type of valves. The dose of W was determined by regular monitoring of prothrombin ratio 0.9 - 3) and that of D by monitoring serum D levels to between 2 and 4 μmol/l. The mean period of follow-up was 26.98 months (range 1 to 36) for W and 22.02 months (range 1 to 36) for W+D. Six patients in W and 1 in W+D developed arterial thrombo-embolic episodes giving an incidence of 0.0035 per patient month for W and 0.0009 per patient month for W+D. An actuarial analysis of the yearly incidence of thrombo-embolism confirmed the superiority of W+D over W. Of the 6 failures in W, 5 were in sinus rhythm and 1 in atrial fibrillation and all had cerebral embolic episodes. The failure in W+D was a patient in atrial fibrillation who died suddenly 6 weeks after surgery and the post-mortem showed clots on both mitral and aortic prostheses.

Research Contribution of Prosthetic Valve Manufacturers Interfacing Academic-Industry Research Efforts

1999 ◽  
Author(s):  
Xiao Gong ◽  
Yi-Ren Woo ◽  
Ajit P. Yoganathan ◽  
Andreas Anayiotos
Keyword(s):  
Heart Valve ◽  
Heart Valves ◽  
Clinical Performance ◽  
Thrombus Formation ◽  
Academic Research ◽  
Prosthetic Heart Valve ◽  
Structural Safety ◽  
Prosthetic Heart Valves ◽  
Implantable Medical Device ◽  
Valve Design

Abstract Prosthetic heart valve is one of the most successful implantable medical devices. However, introducing better performing and longer lasting prosthetic mechanical heart valves (MHV) into clinical use has been slow because predicting the long term performance of a new valve design is difficult. Although significant progresses in many scientific fronts relevant to prosthetic heart valve development have been achieved, we still have an imperfect understanding of host responses to an implantable medical device and incomplete knowledge in associating hemodynamic characteristics of a valve design to clinical performance. Valve designers, frequently need to over design the valve components to ensure structural safety and thus, sacrifice the opportunity to optimize performance. Complications such as infection, thrombus formation, thromboembolic incidents, and hemorrhage associated to the use of prosthetic valves are still reported and valve designers are working hard to eliminate them. Further advancing scientific knowledge in designing and evaluating prosthetic heart valves is of great interest to many Valve designers and manufacturers. Interfacing Industry and Academic research efforts has been thwarted due to predominantly proprietary issues. Considering the benefits of a better performing MHV to the patients, this industry session will bring researchers from various MHV companies and academic institutions to discuss how to share the results of scientific studies more effectively. This will help accelerate new MHV development without compromising the confidentiality of key valve design information. The issue of standardized MHV testing will also be addressed.

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).

Sign in / Sign up

Export Citation Format

Share Document