Development of blood‐compatible elastomers. V. Surface structure and blood compatibility of avcothane elastomers

Abstract

The Avcothane 51 elastomer, a member of a series of proprietary materials best characterized as polyurethane/poly(dialkylsiloxane) block copolymers, displays considerable hemocompatibility without any incorporated anticoagulants. In the form of intra-aortic balloons, the elastomer was implanted in several thousands of cardiac patients without intolerable hematologic effects. Hemocompatibility has been assumed to result from a predominantly dispersion-type surface force field whose intensity fluctuates within small domains, maintaning adsorbed blood proteins in an unstable state. The relative hemocompatibility of films, which were obtained from a prepolymer solution cast on substrates impenetrable to the solvent, is a function of the effective surface molecular structure. This can vary as a function of preparative conditions (temperature and rate of evaporation), and has been correlated with an anisotropic distribution of the silicone component in cured films. The concentration of this component in surface layers was quantified independently by IRATR spectroscopy and electron-microprobe analysis, giving consistent results. An IRATR index, which is computed from the ratio of absorptivities measured at 13.00 and 12.62 mu and is inversely proportional to the relative silicone content of surface layers, was found to correlate with the apparent hemocompatibility determined by different in vitro methods. Optimized reproducible hemocompatibility is attained by strict process controls.

Selected topics in biomedical polyurethanes. A review

“…Certain polyetherurethaneureas and a block copoly(dialkyl siloxane) urethane show a high albumin and a low fibrinogen adsorption [146,147]. This specific protein adsorption behavior of polyurethanes is not clear, although it may have to do with phase segregation in these polymers.…”

A New in vivo Evaluation Method of Antithrombogenicity Using a Polymer-Coated Suture Inserted into the Peripheral Vein

“…Therefore, the antithrombogenicity of the Avcothane is relatively weak and is ineffective within 1 week. In the case of H-PSD polymer, a simple relationship with the blood was noticed, that is, a thin layer of plasma protein-like substance led to the stable interaction.…”

“…Avcothane 51 elastomer [1] (registered trademark of Avco Corp.), is composed of poly(ether urethane) (90%) and poly (dimethylsiloxane) (10%), and was obtained from the Avco-Everett Corporation through Dr. Akaike, Tokyo University of Agriculture and Technology. This polymer displays considerable hemocompatibility without any incorporated anticoagulants.…”

“…The H-PSD [2] was supplied by the Basic Research Laboratories of Toray Industries Inc., 1,111 Tebiro, Kamakura, Japan. It is a newly developed heparinized hydrophilic polymer which has heparin ionically bound within the polymer matrix [3].…”

Ein neues Verfahren zur Herstellung von integrierten Taschenklappen für künstliche Blutpumpen - A New Technique for Manufacturing Integrated Leaflet Valves for Artificial Blood Pumps

“…Sie zeigt gegenüber anderen Klappenprothesen eindeutige Vorteile bezüglich Strömungsform, Druckverlust, Regurgitation und Hämolyse [7]. Ein Material, das ausgezeichnete Blutkompatibilität bei ebenso guten mechanischen Eigenschaften besitzt, ist Avco-thane® 1 ), das als 13 °/oige Lösung in einer 2:1 Mischung aus THF/Dioxan vorliegt, also nur im Tauchverfahren verarbeitet werden kann [3,4]. Ein Material, das ausgezeichnete Blutkompatibilität bei ebenso guten mechanischen Eigenschaften besitzt, ist Avco-thane® 1 ), das als 13 °/oige Lösung in einer 2:1 Mischung aus THF/Dioxan vorliegt, also nur im Tauchverfahren verarbeitet werden kann [3,4].…”