CH R C (CH 2 C) x (CH 2 ) x C CHCH 2 C n n n R R CH 2 CH 2 (CH 2 ) x C n n (CH 2 CH 2 CH 2 C) y n C (CH 2 ) x C n (CH 2 ) x C n (NH CH C) x R CN CH 2 C CR n R ( CH R C) y n P R N n
N H CH R C n N H CH R C n H H H H H CH H NHR H CH R CH 2 C n CH 2 CH H n B P ( ) n
H 2 Catalyst Enzyme Enzyme H 2 Catalyst Enzyme H 2 Catalyst (Tg < T) (Tg > T)
GPa GPa % L DL- G L = 9 1 = 9 1 ( ) ( ) [ ( ) ] [ ( ) ] - - - - [ ( ) ]
PGA
PTCA)
Coil type coronary stent Slotted tube type coronary stent Wiktor stent Palmaz-Schatz stent
(2002 ) 350 70 10
Short and Long-term Vascular Tissue Response to the Duke Biodegradable Stent Zidar JP, Gammon RS, Chapman GD, Culp SC, Brott BC, Clark, H, Bauman RP, Waller BF, Phillips HR, Stack RS Presented at ACC, 1993 JACC vol.21,439a PLLA stent in dog femoral artery Conclusion: Hemocompatible and noninflammatory to the dog femoral artery Duke self-expandable PLLA stent
Marked Inflammatory Sequelae to Implantation of Biodegradable and Nonbiodegradable Polymers in Porcine Coronary Arteries van der Giessen WJ, Lincoff AM, Schwartz RS, van Beusekom HMM, Serruys PW, Holmes Jr DR, Ellis SG, Topol EJ Circulation. 1996 ; 94:1690-1697 Five different biodegradable and some non-biodegradable polymers were implanted in pig coronary arteries Conclusion: Marked inflammatory and neointimal response to an array of biodegradable as well as nonbiodegradable polymers after implantation in the porcine coronary artery
Poly(L-lactic acid) Poly(glycolic acid) Glycolic acid/lactic acid copolymer (85/25) Poly(ε-caprolactone) Poly(hydroxybutyrate-co-hydroxyvalerate) (78/22) Polyurethane Poly(dimethyl siloxane) Poly(ethylene terephthalate) Internal Elastic lamina neointima Polymer Lumen Stent wire Wiktor stent
X Local drag delivery
Knitted PGA stent PGA Knitted PGA stent
Knitted PGA stent 2 weeks 12 weeks 24 weeks S : stent strut L : lumen M : media N : neointima
Knitted PGA Knitted PLLA stent PGA 2 weeks 4 weeks PLLA S : stent strut L : lumen M : media N : neointima 2 weeks 4 weeks
PGA PLLA PGA PGA ph PLLA
PLLA 2 weeks 4 weeks 2 weeks 4 weeks
Coil type PLLA stent (zig zag helical coil) Material : PLLA(poly-L-lactic acid) medical grade 5, 6, 6 7, 8 /36mm 5 /78mm Stent design : Zig zag helical coil self-expanding ability (+) Strut thickness :.007inch (.170mm) Radio-opaque markers : 2 gold markers Currently available diameters : 3.0, 3.5, 4.0 mm Currently available length : 12 mm Surface area : 24% Deployment : balloon expandable
% stenosis 120 100 80 60 40 PGA knit PLLA knit Palmaz-Schatz PLLA helical coil 20 Immediately 6 weeks 0 5 min 2 weeks 4 weeks Time after implantation Coil type 2 weeks 16 weeks
Histological Findings (Pigs) H.E. 2 weeks 6 weeks 16 weeks
Histological Findings (Pigs) H.E. 2 weeks 6 weeks 16 weeks
Mechanical Properties Inner tube Contracted stent Cover tube Force gauge Measurement of bending rigidity
Mechanical Properties 0.1 N ptical Microscope Stent Weight Measurement of compressive destruction 0.1 N
Biodegradable Polymer Stent 1. Knitted type PGA stent in dog coronary artery 2. Knitted type PGA stent in pig coronry artery 3. Knitted type PLLA stent in pig coronary artery 4. Coil type PLLA stent in pig coronary artery 5. Coil type PLLA stent in human coronary artery
Biodegradable Drug Eluting Stent 3.5 / 12 mm