The past and present of coronary stents

The past and present of coronary stents – Medical Device Coating – Cheersonic

Percutaneous coronary intervention (PCI) is one of the main treatment methods for coronary heart disease. The advent of coronary stents has changed the history of coronary heart disease treatment. The medical sages have developed coronary stents to this day with their persevering spirit of exploration.

1. “Past Life” of Coronary Stent

In 1977, Swiss Dr. Adreas Gruentzig performed the world’s first epoch-making percutaneous coronary angioplasty (PTCA) for a 38-year-old male patient with angina pectoris, ushering in a new era of coronary interventional therapy. Dr. Adreas Gruentzig is also known as the “Father of Interventional Cardiology”.

PTCA is the delivery of a balloon catheter to the vascular lesions through the peripheral artery, and the vascular stenosis is relieved by balloon dilation to restore coronary blood flow.

However, in subsequent clinical applications, PTCA has been observed to have serious problems, including restenosis and acute vascular occlusion. Therefore, people have to make improvements. The most direct idea is to prop up a stent at the narrowed blood vessel as a support, and the stent is born, thereby significantly reducing the restenosis rate of PTCA. In the following 40 years, the development of coronary stents has experienced several stages from bare metal stents to drug-eluting stents, and then to absorbable stents.

2. The “life” of coronary stents

(1) Bare metal bracket

In 1986, the first coronary stent implantation was performed. Bare metal stents can open up blocked blood vessels, effectively prevent acute elastic recoil of blood vessels, and basically solve the problem of acute vascular occlusion. Two landmark clinical trials published in 1993 confirmed the superiority of bare metal stents compared to PTCA and established bare metal stents as the gold standard for PCI. In 1994, the US Food and Drug Administration (FDA) approved bare metal stents for clinical use, which is the first generation of stents. Coronary interventional therapy has officially entered the era of stents.

However, after stent implantation, smooth muscle cells proliferate excessively during the healing process of vascular intimal injury, and the delayed healing of vascular endothelium leads to in-stent restenosis, and the problem of in-stent thrombosis remains unresolved.

(2) Drug-eluting stents

In response to the high restenosis rate of bare metal stents, scientists have come up with another idea, which is to coat the surface of the stent with a drug that inhibits cell proliferation, so that the drug can be released slowly, effectively inhibiting the proliferation of vascular smooth muscle cells, thereby reducing the occurrence of vascular restenosis. .

First-generation drug-eluting stents

The first-generation drug-eluting stents are represented by sirolimus-coated stents and paclitaxel-coated stents, both of which use stainless steel skeletons as platforms, with relatively thick stent walls and non-degradable polymer coating materials. The advent of drug-eluting stents has opened a new chapter in the interventional treatment of coronary heart disease, and has been rapidly promoted and applied around the world.

However, the global craze for first-generation drug-eluting stents was quickly extinguished, as multiple clinical studies showed that although it can significantly reduce the incidence of restenosis, it may increase the risk of late stent thrombosis. Because stent thrombosis is often fatal, scientists have begun to develop a new generation of drug-eluting stents.

Second-generation drug-eluting stents

Drug-eluting stents are mainly composed of stent skeleton, polymer coating and anti-proliferative drugs. The second-generation drug-eluting stents have been improved in these three aspects.

First, the stent skeleton was replaced by a stainless steel material with a higher strength cobalt-chromium alloy or platinum-chromium alloy, which made the thickness of the stent wall thinner; on the polymer coating, phosphorylcholine, vinylidene fluoride and other biocompatible materials were selected. Good polymers can reduce local inflammatory reactions or allergic reactions; anti-proliferative drugs are replaced by everolimus, zotarolimus and other less cytotoxic derivatives of sirolimus to reduce local inflammatory effects. Through the continuous improvement of stent materials and technologies, the rate of restenosis after stenting and the incidence of stent thrombosis have been continuously reduced.

Biodegradable polymer drug-eluting stents

Biodegradable polymer drug-eluting stents have become a research hotspot in recent years. Although second-generation drug-eluting stents significantly reduce the incidence of stent thrombosis, the permanent polymer coating contained is highly sensitizing, and can cause chronic vascular inflammation and increase the risk of in-stent restenosis.

Scientists once again focused on the coating, hoping to reduce the inflammatory response caused by the polymer and speed up the endothelial repair by using a fully degradable polymer coating, so the biodegradable polymer drug-eluting stent came into being. . However, so far, several studies have shown that biodegradable polymer drug-eluting stents do not bring additional clinical benefits compared with second-generation drug-eluting stents.

(3) Absorbable stent

Regardless of whether it is a bare metal stent or a drug-eluting stent, there is inevitably a “permanent” residual metal skeleton in the blood vessel, which cannot completely solve problems such as stent thrombosis in restenosis, and also affects the compliance of the blood vessel. Scientists have therefore come up with a bolder idea. Can the stent be put in and it will disappear on its own after it completes its “mission”? At present, many medical companies at home and abroad are working on the research of absorbable stents, and “intervention without implantation” has become a reality.

The ideal absorbable stent provides support for the blood vessel in the early stage of implantation; it is gradually degraded and absorbed in the later stage to avoid inflammatory reaction as a foreign body and reduce the occurrence of late stent thrombosis events; with the complete disappearance of the stent, the natural shape of the blood vessel is finally restored. Relaxation function.

3. The “future” of stents

The process of continuous innovation of stents is a process of human struggle against diseases, and the invention of each new type of stents all condensed the great efforts of scientific researchers and clinicians. Medicine is endless. With the development of technology, it is believed that coronary stents will be updated in the future. However, it is worth mentioning that stent implantation is not the end point of coronary heart disease treatment. It is even more important to take “heart protection” treatment after surgery, and to take antiplatelet drugs, statins, and beta-blockers according to the doctor’s order.

Source of this article: Heart Hope News.

The ultrasonic drug-eluting stent spray coating system can be applied to the preparation of polymer coating for preventing vascular restenosis on the surface of implantable drug-eluting stent. Compared to conventional two-fluid nozzles, ultrasonic nozzles can spray a more uniform drug coating that completely covers the stent without the orange peel and adhesion to a complex stent. The soft atomized spray adheres well to surfaces and coating morphology characteristics can be adjusted by modifying process parameters. In addition, the stent coating obtained by ultrasonic spray coating technology is thinner than dip-coating. Ultrasonic spray coating technology can precisely control the amount of drug sprayed on the stent, making the control of the spraying more precisely.

Cheersonic is the leading developer and manufacturer of ultrasonic coating systems for applying precise, thin film coatings to protect, strengthen or smooth surfaces on parts and components for the microelectronics/electronics, alternative energy, medical and industrial markets, including specialized glass applications in construction and automotive.