Polyurethane artificial heart valves in animals

Akutsu, Tetsuzo; Dreyer, B.; Kolff, Willem J.

doi:10.1152/jappl.1959.14.6.1045

Cited by 62 publications

(12 citation statements)

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“…Yet, no PHV is currently used in clinical practice; several PHV prototypes, mainly composed of polyurethane-based materials, have been developed since 1960s [1] but, despite their promising short-term outcomes [2][3][4][5][6], none have shown satisfactory long-term reliability, due primarily to calcification and tearing of the leaflets [7][8][9][10]. The achievement of an adequate device lifetime remains the main challenge in the development of a clinically viable polymeric prosthesis.…”

Section: Introductionmentioning

confidence: 99%

A Computational Tool for the Microstructure Optimization of a Polymeric Heart Valve Prosthesis

Serrani

Brubert

Stasiak

et al. 2016

Journal of Biomechanical Engineering

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Styrene-based block copolymers are promising materials for the development of a polymeric heart valve prosthesis (PHV), and the mechanical properties of these polymers can be tuned via the manufacturing process, orienting the cylindrical domains to achieve material anisotropy. The aim of this work is the development of a computational tool for the optimization of the material microstructure in a new PHV intended for aortic valve replacement to enhance the mechanical performance of the device. An iterative procedure was implemented to orient the cylinders along the maximum principal stress direction of the leaflet. A numerical model of the leaflet was developed, and the polymer mechanical behavior was described by a hyperelastic anisotropic constitutive law. A custom routine was implemented to align the cylinders with the maximum Europe PMC Funders Author ManuscriptsEurope PMC Funders Author Manuscripts principal stress direction in the leaflet for each iteration. The study was focused on valve closure, since during this phase the fibrous structure of the leaflets must bear the greatest load. The optimal microstructure obtained by our procedure is characterized by mainly circumferential orientation of the cylinders within the valve leaflet. An increase in the radial strain and a decrease in the circumferential strain due to the microstructure optimization were observed. Also, a decrease in the maximum value of the strain energy density was found in the case of optimized orientation; since the strain energy density is a widely used criterion to predict elastomer's lifetime, this result suggests a possible increase of the device durability if the polymer microstructure is optimized. The present method represents a valuable tool for the design of a new anisotropic PHV, allowing the investigation of different designs, materials, and loading conditions. Keywordspolymeric heart valve; heart valve prosthesis; computational modeling

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Section: Introductionmentioning

confidence: 99%

A Computational Tool for the Microstructure Optimization of a Polymeric Heart Valve Prosthesis

Serrani

Brubert

Stasiak

et al. 2016

Journal of Biomechanical Engineering

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“…2). This heart was made of polyvinyl chloride; subsequently we used polyurethane (2); and then for many years, Silastic (3). We went back to the use of polyurethane; now however (1989), the time has come for Silastic to re-enter the picture.…”

Section: First Artificial Heartmentioning

confidence: 99%

The Invention of the Artificial Heart

1990

Int J Artif Organs

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When we implant an artificial heart, we must remember that the neuromuscular control of the peripheral circulation is still intact. If the artificial heart pumps out the blood which is returned from the peripheral circulation to the heart; or in other words, if it responds to Starling's Law, that should be sufficient control ( Fig. 1). I know there are more extensive control schemes, but I like simple things. This means that if the venous pressure or atrial pressure rises, automatically the cardiac output increases. This also maintains balance between right and left ventricular output.Engineers would expect a so-called hunting phenomena, but it does not happen. Fig. 2 -Our first artificial heart durJ.ng implantation in a dog in December 1957. It was made of PVC. Both ventricles were contained in one housing. One can see a large soft collapsible artificial atrium to the left and the artificial pulmonary artery in front. The large opening In the housing made it possible to drive this artificial heart with either air or liquid. A dog's circulation was subtained for 90 minutes.

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“…Axial and transverse velocity components are also indicated in the figure. The discrete velocity magnitudes are obtained 20 times in a cardiac cycle and the mean and the fluctuating components of the axial and transverse velocity components are obtained using the relationship i= 1 W#) = Wi(t) -iqq (1) In this relationship, Wi(t) is the instantaneous axial velocity in the ith cardiac cycle and at time t in the cardiac cycle. w(t) is the mean axial velocity averaged over N cardiac cycles and W i ( t ) is the fluctuation about the mean.…”

Section: Receivingmentioning

confidence: 99%

In Vitro Comparison of Velocity Profiles and Turbulent Shear Distal to Polyurethane Trileaflet and Pericardial Prosthetic Valves

et al. 1989

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A comparative study of flow dynamics past biomer trileaflet valves and a pericardial bioprosthetic valve under steady and physiological pulsatile flow conditions in vitro is reported in this paper. The velocity profiles and the turbulent shear stresses distal to the valves were measured using laser Doppler anemometry. The authors' results showed that the velocity profiles distal to the trileaflet valves were similar to that measured distal to the pericardial valve. Higher magnitudes of absolute turbulent shear stresses were measured distal to the synthetic valves in comparison to the pericardial valves. However, when the stresses were nondimensionalized with respect to the orifice diameter at the inlet aspect, the stresses were comparable for all of the three valves. With design modifications to increase the orifice diameter at the inlet aspect of the polyurethane valves, the turbulent stresses distal to the valves can be minimized. Such in vitro studies on the flow dynamics past the polyurethane valves can provide information towards design changes to improve the performance characteristics of these valves. Polyurethane valves with flow characteristics comparable to the pericardial valves can be manufactured relatively inexpensively compared to mechanical or tissue valve prosthesis. Hence, the synthetic valves may be a viable alternative for short-term use in total artificial heart devices as a bridge to transplant.

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Polyurethane artificial heart valves in animals

Cited by 62 publications

References 0 publications

A Computational Tool for the Microstructure Optimization of a Polymeric Heart Valve Prosthesis

A Computational Tool for the Microstructure Optimization of a Polymeric Heart Valve Prosthesis

The Invention of the Artificial Heart

In Vitro Comparison of Velocity Profiles and Turbulent Shear Distal to Polyurethane Trileaflet and Pericardial Prosthetic Valves

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