Since its clinical application, coronary stents have developed rapidly and have been used more and more. At present, they have become the main means of myocardial revascularization. In the cardiac catheterization labs of many hospitals, coronary stents are implanted in 80% of percutaneous coronary interventions.
1. The angiographic images after implantation of coronary stents are very good, and the results in the acute phase are good;
2. Since coronary stents can treat acute or near-occlusion caused by balloon dilation, the safety of interventional therapy is significantly improved;
3. Coronary stents can reduce the rate of restenosis and improve the long-term prognosis of patients;
4. The implantation of coronary stent is easy to operate;
5. The application of coronary stent can reduce the operation time;
6. For complex lesions, balloon dilation results are often unsatisfactory, and coronary stent implantation can obtain satisfactory results. These widespread applications are attributed to the improvement of coronary stent technology, the in-depth understanding of vessel wall damage in implanted coronary stents, and the advancement of adjuvant drug therapy.
There are many types of stents in clinical practice. There are many ways to classify stents. Due to the different designs of stents, they can be divided into wallstents, tubular stents, wound stents, and annular stents.
According to the different stent materials, it can be divided into 316L stainless steel stents, nickel stents, and tantalum stents. According to the different delivery methods, it is divided into balloon-expandable stents and self-expandable stents.
Different stents are designed according to special purposes, such as stents suitable for bifurcation lesions and stents suitable for branches, and stents with membranes for coronary aneurysms or perforations.
Classification (by different criteria) of coronary stents:
1. Implantation methods: self-expanding (commonly used for carotid artery intervention) and balloon-expanding (the most commonly used clinically);
2. Stent design: mesh type (obsolete), winding type (obsolete), tubular type (the most common clinical use) and ring type;
3. Mesh size: closed loop, open loop;
4. Stent materials: 316L stainless steel stents (the most commonly used clinically), nickel stents, tantalum stents, cobalt-chromium stents and biodegradable stents made of high molecular polymers (may represent the future of stents, but there are still many problems: supporting force) , degradation rate, and inhomogeneity of degradation lead to the problem of stent fragmentation);
5. Special stents: coated stents, membrane stents, biodegradable stents, bifurcation lesion stents, etc.;
6. Drug-eluting stents and non-drug-eluting stents (bare metal stents).
It is now believed that the ideal coronary stent should have the following characteristics:
2. Good traceability;
3. The profile is small;
4. Opaque to X-ray; (5) Antithrombotic;
5. Good biocompatibility;
6. Reliable expansion performance;
7. Good support;
8. Good coverage;
9. Small surface area;
10. In line with fluid mechanics.
Among the currently used stents, none of the stents can fully meet all the above-mentioned characteristics. Each stent has its own characteristics. Familiarity with the characteristics of various coronary stents is a guarantee for the success of interventional therapy.