Viscoelastic memory and self-expansion of self-reinforced bioabsorbable stents.
The possibility to decide the speed and rate of expansion of stents is of great clinical importance by reason of the varying requirements for different indications to use stents. Self-reinforced bioabsorbable stents can be made self-expanding owing to the viscoelastic memory of the material. Stents are stable at room temperature and expansion occurs at body temperature. The level at which the expansion stops depends on the material, crystallinity, initial diameter of spira and annealing temperature. The expansion rate can be estimated by logarithmic equation, if material, draw ratio and diameter of stent wire are constant. This is, however, possible only if processing parameters are constant. Based on the present results annealing temperature and expansion time were seen to be directly proportional to the expansion rate of the stent.
Institute of Biomaterials, Tampere University of Technology, Finland. valimaa@cc.tut.fi
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Välimaa
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Laaksovirta
T L J
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Tammela
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Laippala
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Talja
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Isotalo
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Pétas
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Taari
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Törmälä
D000818:Animals; D001672:Biocompatible Materials; D004548:Elasticity; D006801:Humans; D066298:In Vitro Techniques; D019344:Lactic Acid; D008297:Male; D008422:Materials Testing; D011091:Polyesters; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers; D011467:Prostate / Q000601:surgery; D015607:Stents; D013696:Temperature; D014783:Viscosity
D001672:Biocompatible Materials; D011091:Polyesters; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C033616:poly(lactide)