Experimentelle Untersuchungen am porzinen „over-sized coronary stent“-

Experimental investigations at the porcine over-sized coronary stent-model for in-stent-restenosis rate after implantation of uncoated niob-zirkonium stents and niob-zirkonium stents coated with iridiumoxide. Background: The treatment of atherosclerotic stenosis in coronary artery disease with balloon expandable coronary stents has been successfully practised in minimal invasive cardiology in the last two decades. Today almost all commercially coronary stents are made of stainless steel (316L) and there is a great variety in design and coatings available. Until now no interventional procedure has been successful to stop the vicious circle of arterial stenosis, intervention and restenosis. Methods: In 23 pigs (German land breed) Inflow Dynamics Starflex Design Stents were implanted into the LAD and LCX by random for 28 days. In the porcine over-sized coronary stent model three groups were compared: uncoated niob-zirkonium stents, niob-zirkonium stents coated with iridiumoxide and stainless steel stents (control group). The implantation procedure and angiography were documented and histological and histomorphometric studies were performed to interpret the in-stent-restenosis rate. The statistical evaluation of the differences between the test groups was done by the analysis of variance (One Way ANOVA-Test) and specified (Post Hoc-Test). Results: Three animals died postoperatively. 38 stents were evaluated. The implantation procedure in the experimental groups was complicated due to the elastic and plastic properties of the niob-zirkonium stents. The injury score (IS) and the measured neointimal area (NF) were significantly higher in the group of niob-zirkonium stents coated with iridiumoxide. The histomorphometric and angiographic parameters of restenosis did not point out any significant difference between the test groups. The histological response of the arterial wall after stent implanation provided a homogenous appearance of tissue shaped by the score of vascular irritation. Conclusion: A direct comparison in the stents of uncoated niob-zirkonium and niob-zirkonium stents coated with iridiumoxide with stainless steel stents was not possible. No new findings for the in-stent-restenosis rate were provided by the results of the control stents. The prototypes of the uncoated niob-zirkonium stents and the niob-zirkonium stents coated with iridiumoxide have to be optimized in their metallurgical characteristics to guarantee an implantation procedure without complications. The alloy niob-zirkonium and the iridiumoxide-coating are excellently biocompatible. Even SUMMARY 117 after a high vascular irritation the stents are embeded into a neointima with only a minimum of cellular response.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Ludwig-Maximilians-Universität

Year

2003

Author dc:creator

• Reimer, Cornelia

Repository record source_url

https://edoc.ub.uni-muenchen.de/1348/

OAI identifier oai:identifier

oai:edoc.ub.uni-muenchen.de:1348