Constructions of the mechanical-bearingless centrifugal blood pumps utilize different types of non-contact physical bearings, which allows to balance the forces that have an impact on the pump impeller, stabilizing its position in the pump house without wall contact. The paper presents investigations of the hybrid (passive magnetic bearings and hydrodynamic bearings) suspension system for the centrifugal blood pump. Numerical simulations were used to evaluate the hydrodynamic bearing lifting force and magnetic bearing forces interaction. An important aspect of rotor suspension system design was the nominal gap in hydrodynamic bearing area in order to reduce the blood damage risk in this region. The analyses results confirmed that for a small diameter centrifugal pump, the nominal operating hydrodynamic bearing gap could be established within the range from 0.033 to 0.072 mm.Keywords: titanium nitride layers, athrombogenic coatings, implantable rotary pump, heart assistance Konstrukcje pomp odśrodkowych pozbawionych łożysk mechanicznych wykorzystują różne rodzaje bezkontaktowych łożysk fizycznych, które pozwalają balansować siły oddziałujące na wirnik pompy, stabilizując jego pozycję w obudowie pompy bez kontaktu ze ścianami. Artykuł przedstawia badania hybrydowego (pasywne łożyska magnetyczne i łożyska hydrodynamiczne) systemu zawieszenia wirnika dla odśrodkowej pompy krwi. Symulacji numerycznych użyto dla zbadania siły unoszącej łożyska hydrodynamicznego oraz reakcji łożysk magnetycznych. Ważnym aspektem konstrukcji systemu zawieszenia wirnika było zwięk-szenie nominalnego prześwitu w obszarze łożyska hydrodynamicznego, aby zredukować ryzyko uszkadzania krwi w tym rejonie. Wyniki analiz potwierdziły możliwość wyznaczenia nominalnego prześwitu w łożysku hydrodynamicznym, dla pomp odśrodkowych małej średnicy, w przedziale od 0,033 do 0,072 mm.
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+Ti 2 N+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.Keywords: biomaterial biocompatybility evaluation, ventricular assist device, polyurethanes, diffusive layers, titanium nitride 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+Ti 2 N+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.
The results indicate that a-C:H-based coatings with the thickness of 110 nm do not induce an immune response and do not influence the origin of platelet microparticle formation; thus, these type of coatings are the most promising for the parts which are planned to withstand blood contact under the high value of shear stress.
Cardiac surgical approaches require the development of new materials regardless of the polyurethanes used for pulsatile blood pumps; therefore, an innovative biomaterial, a copolymer of poly(ethylene terephthalate) and dimer fatty acid (dilinoleic acid) modified with D-glucitol, hereafter referred to as PET/DLA, has been developed, showing non-hemolytic and atrombogenic properties and resistance to biodegradation. The aim of this work was to evaluate in vivo inflammatory responses to intramuscular implantation of PET/DLA biomaterials of different compositions (hard to soft segments). Two copolymers containing 70 and 65 wt.% of hard segments, as in poly(ethylene terephthalate) and dilinoleic acid in soft segments modified with D-glucitol, were used for implantation tests to monitor tissue response. Medical grade polyurethanes Bionate II 90A and Bionate II 55 were used as reference materials. After euthanasia of animals (New Zealand White rabbits, n = 49), internal organs and tissues that contacted the material were collected for histopathological examination. The following parameters were determined: peripheral blood count, blood smear with May Grunwald–Giemsa staining, and serum C-reactive protein (CRPP). The healing process observed at the implantation site of the new materials after 12 weeks indicated normal progressive collagenization of the scar, with an indication of the inflammatory–resorptive process. The analysis of the chemical structure of explants 12 weeks after implantation showed good stability of the tested copolymers in contact with living tissues. Overall, the obtained results indicate great potential for PET/DLA in medical applications; however, final verification of its applicability as a structural material in prostheses is needed.
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