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Arterial stenting with self-expandable and balloon-expandable endoprostheses
W J van der Giessen1, P W Serruys, L J van Woerkens
1Department of Cardiology, Thoraxcenter, The Netherlands.
Insights
Vascular stents can reduce complications from angioplasty. Self-expandable stents (SES) showed 100% patency with antithrombotic treatment, while balloon-expandable stents (BES) achieved 100% patency without it in swine models.
Area of Science:
- Cardiovascular research
- Biomedical engineering
- Interventional cardiology
Background:
- Coronary angioplasty complications include acute occlusion (2-5%) and late restenosis (20-40%).
- Vascular endoprostheses (stents) offer a potential solution to these complications.
- Metallic stents are undergoing evaluation for clinical use.
Purpose of the Study:
- To evaluate the performance of two metallic stents in swine arteries.
- To compare self-expandable stents (SES) and balloon-expandable stents (BES) in normal arteries.
- To assess the impact of antithrombotic therapy on stent patency.
Main Methods:
- Implantation of self-expandable stainless steel stents (3.5 mm) in peripheral swine arteries (n=17), some deendothelialized.
- Implantation of SES (3.0 and 3.5 mm) and tantalum balloon-expandable stents (BES) in normal coronary arteries of swine.
- Post-implantation antithrombotic therapy varied: acenocoumarol and aspirin, aspirin alone, coumadines, or no treatment.
Main Results:
- All peripheral stented arteries were patent after 1 week with complete neointimal coverage.
- Untreated SES in coronary arteries showed a 38% occlusion rate within 48 hours, with 62% patency at 1 week.
- SES treated with coumadines and untreated BES demonstrated 100% patency at 1 week in coronary arteries.
Conclusions:
- Self-expandable stents (SES) require antithrombotic treatment (coumadines) to achieve 100% patency in normal swine coronary arteries.
- Balloon-expandable stents (BES) demonstrated 100% patency without antithrombotic treatment in normal swine coronary arteries.
- Stent design and antithrombotic regimen significantly influence patency rates.
Abstract:
Coronary angioplasty is complicated by acute occlusion (within 24 hours) and late restenosis (within 6 months) in 2-5% and 20-40% of the cases, respectively. Vascular endoprostheses (stents) may provide the cardiologist with a solution to some of these complications. Several stent-devices are now available for experimental and clinical evaluation. In this study we describe our experience with two metallic stents in normal arteries of swine. Self-expandable, stainless steel stents (3.5 mm diameter) were implanted in 17 peripheral arteries, eight of which were deendothelialized by prior balloon angioplasty. Following implantation, the animals received antithrombotic therapy with acenocoumarol and aspirin (8 stents), or aspirin alone (9 stents). After 1 week repeat angiography was performed, which showed patency of all stented arteries. Microscopy showed complete covering by neointima, 80 microns in thickness. This self-expandable stent (SES) and a balloon-expandable stent (BES), constructed of tantalum, were implanted in normal coronary arteries. SES (3.0 and 3.5 mm) receiving animals were treated with coumadines (10 stents) or received no antithrombotic treatment (16 stents) after implantation. BES receiving animals were also not treated (10 stents). Three untreated animals with SES died suddenly within 48 hours. Postmortem examination showed partial or complete thrombosis of all six stents in these animals, resulting in a patency rate of 62% after 1 week. All animals with SES, which were treated with coumadines, and all animals with BES (untreated) had patent stents after one week. It is concluded that SES implanted in normal coronary arteries of pigs, which do not receive additional antithrombotic treatment, show a 38% occlusion rate within 48 hours, but show 100% patency after 1 week, when the animals are treated with coumadines. BES implanted in normal coronary arteries of pigs, which do not receive antithrombotic drugs, are 100% patent after 1 week.