Biological properties of surface layers for ring of heart valve application

Oryginalna sztuczna komora wspomagania serca POLVAD opracowana w Polsce, została zastosowana dotychczas w leczeniu ponad 210 pacjentów. Najdłuższe wspomaganie serca za pomocą komory POLVAD trwało ponad rok. Dla protezy tej opracowywana jest innowacyjna zastawka dyskowa, z nisko profilowym pierścieniem wykonanym ze stopu tytanu. Dla zminimalizowania trombogenności pierścienia zastawki opracowano dyfuzyjne warstwy powierzchniowe: azotowaną typu TiN+Ti2N+αTi(N) i tlenoazotowaną typu TiO2+TiN+Ti2N+αTi(N), wytwarzane obróbką jarzeniową na potencjale plazmy. Trombogenność różnych kompozycji warstw została porównana w aspekcie aktywacji i adhezji płytek krwi do powierzchni biomateriału. Oceniono również wpływ metody sterylizacji biomateriału na intensywność adhezji trombocytów do jego powierzchni. Warstwy TiN oraz TiO2wykazały najniższą trombogenność, przy czym dla warstwy TiN korzystniejsza jest sterylizacja gazowa, podczas gdy dla warstwy TiO2- sterylizacja plazmowa.The original ventricular assist device POLVAD developed in Poland was used in over 210 patients so far. The longest POLVAD heart assistance excided one year. The innovative tilting disk valve with low profile ring made of titanium is developed for POLVAD. To minimize the valve ring thrombogenicity the diffusive surface layers were manufactured: nitriding TiN+Ti2N+αTi(N) and oxynitriding TiO2+TiN+Ti2N+αTi(N), in the glow discharge process on the plasma potential level. The thrombogenicity of different layers compositionwas compared regarding platelets activation and platelets adhesion to the material surface. The influence of material sterilization method on the platelets adhesion intensity was evaluated in addition. The nitriding TiN and oxynitriding TiO2layers have demonstrated the lowest thrombogenicity while the gas sterilization was the most profitable for nitriding layers – TiN and the plasma sterilization for oxynitriding layers – TiO2

The physical parameters estimation of physiologically worked heart prosthesis

One of possible cardiac failure therapy is mechanical heart supporting. The following types of ventricular assist devices (VAD) are clinically used: diaphragm displacement, centrifugal and axial pumps. Each of supporting devices produces different hemodynamical effect and affects the circulatory system in various ways. It causes impossibility of therapeutic effect comparison obtained by different pumps' treatment. A lack of defined physical parameters describing phenomena inside the pump and its influence on circulatory system are an obstacle during new supporting devices designing. The goal of investigations is to create a set of physical parameters which characterized pump's operating and its cooperation with circulatory system

Selected problems of mechanical heart supporting automation

Mechanical heart supporting is one of possible therapy in case of circulatory system insufficiency. Each of ventricular assist devices affect the circulatory system by various way. A lack of predefined physical ratios describing heart assist device influence on circulatory system is a problem during establishing brief foredesign of new ventricular assist devices types and comparison of supporting effects obtained by various VAD types usage. It causes necessity of creation a set of physical parameters which characterize pump's operating and its cooperation with circulatory system. The paper describes selected problems related to automation of mechanical heart supporting process

The methods of physical parameters measurement regarding the heart supporting automation

During heart insufficiency therapy by ventricular assist device it is important to maintain proper supporting conditions independently on personal anatomical differences, various courses of disease and temporary variations of patient's circulatory system state. It causes necessity of assist device operation automation and estimation of its particular parameters: output flow, pressures in characteristic points and extremely membrane position. The paper describes selected problems related to automation of mechanical heart supporting process and measurement of selected physical supporting parameters

Polish Artificial Heart - new coatings, technology, diagnostics

Since 1991, the Foundation for Cardiac Surgery Development in Zabrze has been implementing research on the artificial heart. In 1995, an artificial ventricle, POLVAD, was implanted to a patient, and in 1998, the prototype of a clinical controller, POLPDU-401, was created. A further development of the studies on an implantable artificial heart requires an integrated approach and an application of advanced methods of materials sciences in order to develop new materials suitable for the contact with blood, as well as to apply a multilateral biomedical diagnostics in hydrodynamic conditions. The estimation of the cell–material interaction plays an important role in the biomaterial design. An analysis of the influence of the carbon content in titanium nitride on the biological and biophysical properties of biomaterial coatings was studied. The cell-material reactions were considered in dynamic and static conditions. Three groups of materials were under examinations – titanium nitride (TiN), as well as titanium carbonitride with a low and high carbon content – of which the best properties were observed for TiN. We found a strong influence of the stoichiometry of TiN (atomic ratio of Ti/N) on the biocompatibility. A non-stoichiometric TiN could have a negative influence on the surrounding tissue

Biokompatybilna ocena biomateriałów stosowanych w nowej polskiej pozaustrojowej pulsacyjnej protezie serca ReligaHeart EXT

The innovative extracorporeal heart support device ReligaHeart (RH EXT) has been developed, based on POLVAD ventricular assist device clinical experience, collected in more than 300 patient applications. The innovative surface engineering technologies are applied in ReligaHeart EXT device. The pump is manufactured of new generation, modified surface structure, biocompatible polyurethanes, and equipped with original tilting disc valves, Moll type. The valve ring is made of titanium alloy, TiN+Ti2N+αTi(N) diffusive layer modified, produced with glow discharge at plasma potential, in order to obtain the lowest thrombogenicity. The valve disc is made of polyether ether ketone. The complex in vitro and in vivo biological evaluations were performed, confirming both biomaterials biocompatible properties and device biocompatibility, proved in 30 days animal heart support.Na podstawie doświadczeń klinicznych protezy serca POLVAD, zastosowanej u ponad 300 pacjentów, opracowano zmodernizowaną pozaustrojową pompę wspomagania serca ReligaHeart EXT (RH EXT). W protezie RH EXT zostały zastosowane innowacyjne technologie inżynierii powierzchni. Pompa wykonana jest z nowej generacji biozgodnych poliuretanów o modyfikowanej strukturze powierzchni i jest wyposażona w oryginalne zastawki dyskowe typu Moll. Pierścień zastawki jest wykonany ze stopu tytanu z dyfuzyjną warstwą TiN+Ti2N+αTi(N) wytwarzaną w procesie obróbki jarzeniowej na potencjale plazmy, dla osiągnięcia niskiej trombogenności. Dysk zastawki jest wykonany z polieteroketonu. Wykonano kompleksową ocenę biozgodności in vitro i in vivo, potwierdzając biozgodne własności biomateriałów i protezy RH EXT, także w czasie 30 dniowego wspomagania serca w modelu zwierzęcym

Biocompatibility in vitro investigations of Religa Heart EXT ventricular assist device structural polymers, treated with technological process

Celem badań była ocena biozgodności w testach in vitro polimerów konstrukcyjnych polskiej pozaustrojowej pulsacyjnej pompy wspomagania serca Religa Heart EXT. Badaniu poddano próbki polimerów Bionate® II 90A, Bionate® II 55D i ChronoFlex® AR-LT przygotowane po procesach przetwórstwa, odpowiadających wytworzeniu pompy Religa Heart EXT. Przedmiotem badań była ocena oddziaływania polimerów na wybrane elementy komórkowe, takie jak: erytrocyty, płytki krwi i fibroblasty. Przeprowadzono testy hemolizy, trombogenności, cytotoksyczności oraz struktury chemicznej polimerów. Badania wykonano zgodnie z polską normą PN-EN ISO 10993. Rezultaty wykazały, że polimery konstrukcyjne po przetwórstwie nie oddziaływały negatywnie na elementy morfotyczne krwi, nie aktywowały płytek krwi i leukocytów oraz nie oddziaływały toksycznie na komórki fibroblastów. Ponadto, nie stwierdzono istotnych zmian w strukturze chemicznej polimerów konstrukcyjnych po procesie przetwórstwa technologicznego.The aim of the investigations was in vitro biocompatibility evaluation of Polish extracorporeal pulsatile ventricular assist device Religa Heart EXT structural polymers. Samples of polymers: Bionate® II 90A, Bionate® 55D and ChronoFlex® AR-LT were tested, had been treated before with technological processes matching the conditions of Religa Heart EXT pump manufacturing. The subject of the investigation was the interaction between polymers and cellular elements (erythrocytes, platelets and fibroblasts). The following tests were performed: haemolysis, thrombogenicity, cytotoxicity and chemical structure analyses. The tests were performed according to Polish standard PN-EN ISO 10993. The results revealed: no negative interaction between blood cells and structural polymers, after technological process; no activation of platelets and leukocytes, and no fibroblasts toxicity. Furthermore, no essential changes in the chemical structure of the examined polymers after technological process were observed

Prototype of wireless energy transfer system

W artykule opisano prototyp układu bezprzewodowej transmisji energii elektrycznej, który może być zastosowany do zasilania protezy serca. Opisano poszczególne podzespoły prototypu oraz zaprezentowano wybrane wyniki pomiarów przy mocy wyjściowej ~30 W i odległości pomiędzy planarnymi cewkami sprzężonymi magnetycznie 10÷15 mm. Przy mocy wyjściowej 32,5 W i odległości pomiędzy cewkami 13 mm, pomimo wysokiej częstotliwości pracy układu (800 kHz), uzyskano całkowitą sprawność 92,3%. W artykule zaproponowano metodę projektowania układu oraz oszacowano rozkład strat mocy w jego podzespołach.A prototype of a wireless energy transfer system is described in the paper. It could be applicable for powering the artificial heart. Wire-less energy transfer is based on magnetically coupled planar coils (Fig. 4). The coils are attached to the coordinate table (Fig. 2) which is used to set the distance between them. The system operates at 800 kHz with output power of ~30 W and distance between the coils of 10÷15 mm. It is powered by a Class E inverter (Fig. 3). A synchronous rectifier (Fig. 6) and capacitive output filter are used to supply a resistive load with high efficiency. In order to minimize power losses of the system, an appropriate design procedure is included and explained in the paper. The prototype system was fabricated and tested to confirm theoretical predictions. Meas-ured voltage and current waveforms illustrates the inverter and synchronous rectifier operation (Fig. 7). The DC-DC efficiency and output power of the system as a function of the distance between the coils were also measured (Fig. 8). The maximum efficiency of 92,3% was obtained for the distance between the coils of 13 mm and output power of 32,5 W. Additionally, the analysis of power losses distribution in each component of the system was included (Fig. 9). The results confirm satisfactory performances of the tested prototype system