Enhanced Biocompatibility of GPC by MeV Ion Bombardment

2005 ◽  
Vol 873 ◽  
Author(s):  
R. Zimmerman ◽  
I. Gurhan ◽  
S. Sarkisov ◽  
C. Muntele ◽  
D. Ila ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Heart Valves ◽  
Surface Hardness ◽  
Ion Bombardment ◽  
Blood Stream ◽  
Hard Material ◽  
Collagenous Tissue ◽  
Artificial Heart Valves ◽  
Model Cell

AbstractGlassy Polymeric Carbon (GPC) is completely biocompatible and is widely used as a material for artificial heart valves and in other biomedical applications. Although it is ideally suited for fluid flow in the blood stream, collagenous tissue that normally forms around the moving parts of a GPC heart valve sometimes loses adhesion and creates embolisms downstream. We have shown that moderate fluence of MeV ions, especially oxygen ions, increases the surface roughness of GPC on a scale appropriate for enhancing tissue adhesion. Silver ion implantation is shown to inhibit cell growth on GPC. Ion bombardment also increases the surface hardness of GPC, already an extremely hard material. In vitro biocompatibility tests have been carried out with model cell lines to demonstrate that MeV ion bombardment can favorably influence the surface of GPC for biomedical applications.

Enhanced Biocompatibility of GPC by Ion Implantation and Deposition

2005 ◽  
Vol 908 ◽  
Author(s):  
Robert Lee Zimmerman ◽  
Ismet Gürhan ◽  
Claudiu I. Muntele ◽  
Daryush Ila ◽  
Feyzan Özdal-Kurt ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Biomedical Applications ◽  
Heart Valves ◽  
Cell Attachment ◽  
Blood Stream ◽  
Silver Deposition ◽  
In Vitro Biocompatibility ◽  
Artificial Heart Valves ◽  
Model Cell

AbstractBiocompatible Glassy Polymeric Carbon (GPC) is used for artificial heart valves and in other biomedical applications. Although it is ideally suited for implants in the blood stream, tissue that normally forms around the moving parts of a GPC heart valve sometimes loses adhesion and creates embolisms downstream. Here we compare silver ion implantation and silver deposition, each of which strongly inhibits cell attachment on GPC. Inhibition of cell adhesion is a desirable improvement to current GPC cardiac implants. In vitro biocompatibility tests have been carried out with model cell lines to demonstrate that traces of silver can favorably influence the surface of GPC for biomedical applications.

Calcification Modelling in Artificial Heart Valves

1992 ◽  
Vol 15 (5) ◽  
pp. 284-288 ◽  
Author(s):  
A.C. Fisher ◽  
G.M. Bernacca ◽  
T.G. Mackay ◽  
W.R. Dimitri ◽  
R. Wilkinson ◽  
...  
Keyword(s):  
Artificial Heart ◽  
Heart Valves ◽  
Test Protocol ◽  
Tissue Sections ◽  
Artificial Heart Valves ◽  
In Vivo Tests ◽  
Tissue Contents ◽  
Histological Staining

This study has examined a range of methods of studying the calcification process in bovine pericardial and polyurethane biomaterials. The calcification methods include static and dynamic, in vitro and in vivo tests. The analytical methods include measurement of depletion rates of calcium and phosphate from in vitro calcifying solutions, analysis of tissue contents of calcium, histological staining of tissue sections for calcium, X-ray elemental analysis, by scanning electron microscopy, of calcium and phosphorus distributions over valve leaflets calcified in vitro under dynamic conditions. Bovine pericardium, in all test settings, calcified to a much greater degree than polyurethane biomaterials. Polyurethane extracts calcified to a greater degree than bulk polyurethanes. The test protocol used allows progress through increasily demanding calcification tests, with the possibility of eliminating unsuitable materials with tests of limited complexity and expense.

Parameters and Methods for Testing Artificial Heart Valves

1989 ◽  
Vol 12 (4) ◽  
pp. 252-260 ◽  
Author(s):  
J.C. Köhler ◽  
J.G. Tech
Keyword(s):  
Heart Valves ◽  
Close Correlation ◽  
Test Methods ◽  
In Vitro Tests ◽  
Geometrical Parameters ◽  
Test Standards ◽  
Artificial Heart Valves ◽  
Minimum Requirements ◽  
Definition Of

The report describes the development of heart valve test standards. The aim is comprehensive quality assurance by in vitro tests. The project includes three test fields: general basis, development and definition of test methods and test devices and comparative in vitro assessment of valves for the definition of minimum requirements. A preliminary list of test parameters and test steps has been defined: geometrical, flow, deformation, force, and conditioning parameters. A system of geometrical parameters has been developed for standardized aortic models. Geometrical parameters of 31 valves of six types and different sizes underline a close correlation between geometrical and hemodynamic parameters. The relative ostium cross-section Ae/AT increases with valve size and lies between 0.3 and 0.5. Two new measurement devices with quasi-steady flow are proposed as quick testers for leakage flow and pressure loss.

A Method to Measure the Station of Artificial Mechanical Heart Valves

2013 ◽  
Vol 683 ◽  
pp. 712-715
Author(s):  
Feng Zhou ◽  
Liang Liang Wu ◽  
Yuan Yuan Cui ◽  
Ying Chen ◽  
Jie Yang ◽  
...  
Keyword(s):  
High Speed ◽  
Heart Valves ◽  
Ultrasonic Method ◽  
High Speed Photography ◽  
In Vitro Experiments ◽  
In Vivo Experiments ◽  
Artificial Heart Valves ◽  
Economic Injury

The experiments of artificial heart valves were divided into in vivo and in vitro experiments; in vivo experiments provide accurate experimental parameters serving in vitro research. Simulation experiment used in vitro usually goes like this, firstly design a similar model or prototype phenomenon, then analysis the model working out the regular parameters related to the process, ruled out the possibility of impact on the study of individual exist in vivo experiment. In vitro experiments are likely designed; performance can be simplified and prominently concerned about contents, even designed some extreme conditions to test. A number of means related to fluid experimental measurement are included, such as the Particle Image Velocimetry（PIV）[1], Dual Catheter Method [2]，and ultrasonic method[3] and so on. However, these methods have different kinds of limitations, for example the Dual Catheter Method cannot be used as a routine determination for clinic due to its destructiveness, and PIV test requires expensive equipment. This study was designed by the image processing technology of high-speed photography aiming at the production of a reliable, simple, economic, injury-free and non-contact measurement method.

In Vitro Blood Damage by High Shear Flow: Human versus Porcine Blood

2002 ◽  
Vol 25 (4) ◽  
pp. 306-312 ◽  
Author(s):  
S. Klaus ◽  
S. Körfer ◽  
K. Mottaghy ◽  
H. Reul ◽  
B. Glasmacher
Keyword(s):  
Human Blood ◽  
Heart Valves ◽  
High Shear ◽  
Blood Damage ◽  
Shear Rates ◽  
Porcine Blood ◽  
High Shear Rates ◽  
Blood Pumps ◽  
Artificial Heart Valves

Devices for modern heart support are minimized to reduce priming blood volume and contact area with foreign surfaces. Their flow fields are partly governed by very high velocity gradients. In order to investigate blood damage, porcine and human blood was passed through a narrow Couette type shear gap applying defined high shear rates within the typical range for devices such as blood pumps or artificial heart valves (γ = 1800/s to 110,000/s for 400 ms). Traumatization profiles of both blood species were recorded in terms of hemolysis and platelet count. Sublethal damage in terms of platelet (PF4) and complement activation (C5a) was additionally measured for human blood. Results for porcine and human blood were very similar. Hemolysis was not started until critical shear rates of about 80,000/s. Impact on platelets was severe with drops in cell count of up to 65% (at γ = 55,000/s to 110,000/s) likely to set stronger limits to the design layout of devices than hemolysis. Concentrations of PF4 and C5a clearly increased with shear rate exhibiting stronger gradients where hemolysis started. Due to the similar results of porcine and human blood for hemolysis and platelet drop, porcine blood seems to be suitable for device testing. Selection of blood species would thus depend on handling, availability and analysis demands.

In Vitro Testing of Artificial Heart Valves: Comparison Between Newtonian and Non-Newtonian Fluids

1996 ◽  
Vol 20 (1) ◽  
pp. 37-46 ◽  
Author(s):  
Manfred Pohl ◽  
Max Otto Wendt ◽  
Sabine Werner ◽  
Brigitte Koch ◽  
Dietmar Lerche
Keyword(s):  
Artificial Heart ◽  
Heart Valves ◽  
Newtonian Fluids ◽  
In Vitro Testing ◽  
Artificial Heart Valves

The Influence of Open Leaflet Geometry on the Haemodynamic Flow Characteristics of Polyurethane Trileaflet Artificial Heart Valves

1996 ◽  
Vol 210 (4) ◽  
pp. 273-287 ◽  
Author(s):  
J Corden ◽  
T David ◽  
J Fisher
Keyword(s):  
Axial Velocity ◽  
Heart Valves ◽  
Flow Characteristics ◽  
Manufacturing Method ◽  
Blood Damage ◽  
Flow Recirculation ◽  
Maximum Value ◽  
Artificial Heart Valves

In vitro velocity data were obtained downstream of two versions of the Leeds polyurethane trileaflet heart valve in a simulated pulsatile flow regime using laser Doppler velocimetry. The main difference between the two valves studied was the manufacturing method used to create the valves. The film-fabricated valve was constructed from solvent-cast sheets of polyurethane, thermally formed into the correct leaflet geometry. The dip-cast valve used a stainless steel mould which was dipped into a polyurethane solution to produce the valve leaflets. Significant differences were visible between the fully open leaflet shape of each valve. The distribution of mean axial velocity and Reynolds normal stress (RNS) was shown to be dependent on the shape of the fully open valve orifice. For the film-fabricated valves, flow recirculation and high values of RNS were present downstream of the frame posts. The maximum value of RNS obtained downstream of the film-fabricated valve at peak systole was 147 N/m2. Results for the dip-cast valve showed a more uniform distribution of mean axial velocity and RNS resulting from the more circular central orifice produced by the dip-cast leaflets. The maximum value of RNS obtained downstream of the dip-cast valve at peak systole was 109 N/m2. These results demonstrate the effect of the open valve geometry on the flow characteristics downstream of trileaflet valves and that minor changes to the open leaflet geometry can significantly affect the flow characteristics and the possibility of flow-related blood damage occurring in vivo.

Fresh Human Aortic and Artificial Heart Valves Studied in Vitro Using Ultramicroscope Anemometry. Further Results

1982 ◽  
Vol 30 (05) ◽  
pp. 273-280 ◽  
Author(s):  
D. Schramm ◽  
H. Müller-Mohnssen ◽  
W. Baldauf ◽  
H. Meisner
Keyword(s):  
Artificial Heart ◽  
Heart Valves ◽  
Artificial Heart Valves
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