New Polyurethane Valves in New Soft Artificial Hearts

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) blend films were prepared by solvent-cast method. The nonisothermal crystallization results showed that PHBV and P3/4HB are miscible due to a single glass transition temperature (T g ), which is dependent on blend composition. The isothermal crystallization results demonstrate that the crystallization rate of PHBV becomes slower after adding amorphous P3/4HB with 19.2 mol% 4HB, which could be proved through depression of equilibrium melt point (T C and 84 C, respectively. FTIR analysis showed that PHBV/P3/4HB blend films would maintain the helical structure, similar to pure PHBV. Meanwhile, with increasing P3/4HB content, the inter-and intrainteractions of PHBV and P3/4HB decrease gradually. Besides, a lower elastic modulus and a higher elongation at break were obtained, which show that the addition of P3/ 4HB would make the brittle PHBV to ductile materials.

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Section: Discussionmentioning

confidence: 99%

Miscibility, crystallization kinetics, and mechanical properties of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)(PHBV)/poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)(P3/4HB) blends

Wang

Chen

et al. 2010

J of Applied Polymer Sci

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“…Furthermore, polyurethane failure mechanisms in circulatory implants such as prosthetic heart valve leaflets involve not only biodegradation, but other important processes such as calcification 12 and thrombosis. 25 Research by our group has demonstrated that covalent modification of polyurethanes with the attachment of bisphosphonate compounds to PU-hard segment nitrogens can confer resistance to biomineralization. 12 In addition, other research by our group has shown that chemical strategies also involving hard segment modification and bromoalkylation can be used to attach heparin thereby conferring relative thrombo resistance.…”

Section: Discussionmentioning

confidence: 99%

Biological stability of polyurethane modified with covalent attachment of di‐tert‐butyl‐phenol

Stachelek

Alferiev

Fulmer

et al. 2007

J Biomedical Materials Res

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Polyurethane cardiovascular implants are subject to oxidation initiated surface degradation, which is mediated by monocyte-derived macrophages (MDM); this often leads to surface cracking and device failure. The present studies examined the hypothesis that covalently attaching antioxidant, di-tert-butylphenol (DBP), to the urethane nitrogens of a polyether polyurethane (PU) via bromo-alkylation reactions could prevent this problem. PU was configured with two dosages of DBP, 0.14 mM DBP/g PU of DBP (PU-DBP) and a more highly modified (HM) 0.40 mM DBP/g PU (PU-DBP-HM). THP-1 cells, a human MDM cell line, stimulated with phorbol ester and seeded on PU, PU-DBP, and PU-DBP-HM films were assessed for reactive oxygen species (ROS) production via a fluorescent based dihydrorhodamine-123 assay. Results from these studies showed a significant dose-dependent reduction of ROS levels for THP-1 cells seeded on PU-DBP versus unmodified PU. PU, PU-DBP, or PU-DBP-HM films were implanted into subdermal pouches of Sprague-Dawley rats. Films were explanted after 10 weeks and assessed for oxidative degradation via light and scanning electron microscopy (SEM) and Fourier transformation infrared spectroscopy (FTIR). Light microscopy showed extensive surface cracking, which was confirmed via SEM, on unmodified PU surfaces that was absent in both PU-DBP and PU-DBP-HM explanted films. FTIR analysis showed reduction in oxidation-induced ether crosslinking that was directly related to DBP dosages. It is concluded that modifying PU with the covalent attachment of an antioxidant confers biodegradation resistance in vivo in a dose dependent manner; this effect is likely due to quenching of the ROS generated by the adherent macrophages.

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“…PU bi-leaflet inflow valves and tricusp PU outflow valves (2,6) were mounted in the reinforced valve area. The separate components of the ventricles are made by vacuum-forming the housing, diaphragm, and base over their individual molds.…”

Section: Methodsmentioning

confidence: 99%

“…The pumping diaphragm was double-layered, with graphite between both layers. PU bi-leaflet inflow valves and tricusp PU outflow valves (2,6) were mounted in the reinforced valve area. For the purpose of this study (comparing soft and rigid ventricles), soft ventricles were made rigid by completely covering them with fiberglass sheets dipped in epoxy resin, using tetrahydrofuran as a bonding agent.…”

Section: Methodsmentioning

confidence: 99%

Concept of a Soft, Compressible Artificial Ventricle Under Evaluation

Topaz

et al. 1991

Artificial Organs

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This study was designed to compare the relative merits of soft and rigid artificial ventricles. A cascade mock circulation was used to measure cardiac output under different circumstances. The data show that these soft air driven ventricles show a Starling's-like response over a wider range of filling pressures than identical, but rigid, ventricles. Compression of soft ventricles by high intrathoracic pressures was simulated in vitro. Air pressures up to + 20 mm Hg did not seriously affect soft ventricles. Cardiac tamponade was simulated by compressing the ventricle in a closed fluid compartment. Tamponade became severe when volume reduction of the ventricle rose to 60 ml. Hemolysis caused by soft and rigid ventrides was tested in a blood bag set-up and was ---I _

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New Polyurethane Valves in New Soft Artificial Hearts

Cited by 13 publications

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Miscibility, crystallization kinetics, and mechanical properties of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)(PHBV)/poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)(P3/4HB) blends

Miscibility, crystallization kinetics, and mechanical properties of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)(PHBV)/poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)(P3/4HB) blends

Biological stability of polyurethane modified with covalent attachment of di‐tert‐butyl‐phenol

Concept of a Soft, Compressible Artificial Ventricle Under Evaluation

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