Stent technology for the treatment of heart disease continues to advance in the effective management of coronary artery disease, but there are still challenges that need to be addressed. It is important to develop technologies that are bio-stable and biocompatible, and advances in these areas will play an important role in shaping the future of heart disease treatment.
To keep the heart, the engine of the human body, functioning smoothly, the heart muscle must be supplied with sufficient oxygen and nutrients. This is accomplished by supplying blood through the arteries that surround the heart. The blood vessels that supply the heart are called coronary arteries. The heart beats about 100,000 times a day, pumping 7,500 liters of blood throughout the body. The role of the coronary arteries in this process is very important, and even the slightest problem with them immediately affects heart function.
If cholesterol, protein, and other waste products build up in the coronary arteries and prevent the blood supply from flowing smoothly, various heart diseases such as myocardial infarction and angina can occur. Heart disease is the third leading cause of death among adults in Korea after cancer and cerebrovascular disease. In particular, the incidence of cardiovascular disease is increasing rapidly in modern society due to high-fat, high-carbohydrate diets and lack of exercise. Against this backdrop, the prevention and treatment of coronary artery disease has become an increasingly important issue. In recent years, the prevention and treatment of coronary artery disease has become an increasingly important issue.
In the past, once coronary artery narrowing was identified, there were few solutions. Drugs such as thrombolytic agents were injected to dissolve the accumulated waste, but this was only a temporary solution. Even when heart surgery was necessary, it was often not performed due to various factors such as the patient’s physical strength and age. However, the invention of stents changed this problem.
Stents are a type of biomaterial that is inserted into coronary arteries, cerebral vessels, etc. in the form of a metal mesh to dilate blood vessels and facilitate blood flow to treat circulatory diseases. Stents are increasingly being used to treat not only coronary artery disease, but also peripheral vascular disease, aneurysms, and even urethral strictures. Stents were introduced as non-functional tubes in 1964 by Charles Theodore Dotter. In 1986, Jacques Pue implanted the first coronary stent in a human. Stents are generally elastically expanded to reduce narrowing of blood vessels, and are divided into self-expanding stents using the metal’s own expansion force and balloon-expandable stents according to the expansion method. In the case of balloon-expandable stents, a guide wire is first inserted into the blood vessel, the balloon and stent are inserted, the balloon is inflated, and the balloon and guide wire are removed. Once inserted, the stent dilates the vessel, allowing blood to circulate better.
In the early days of stenting, stents were made of metal, but they had their own problems. First, the endothelial tissue of the blood vessel would grow through the mesh of the stent, causing the blood vessel to narrow again. It was also discovered that the metal could oxidize and leach metal ions into the blood, changing the pH of the environment and causing physical and chemical reactions with the surrounding tissue. This led to inflammatory reactions around the stent and recurrent stenosis, which is a serious problem for patients. Another problem with metal stents was the potential for ions to produce deformed nucleic acids, which can be carcinogenic. Stent thrombosis, a condition in which platelets, cholesterol, etc. become entangled in the stent and obstruct blood flow, was also noted. To solve this problem, researchers have been coating stents with drugs since the mid-1990s. As studies showed that drug-eluting stents were more effective than metal stents, drug-eluting stents became mainstream. Initially, there were concerns about the drug coating, but as clinical studies demonstrated its effectiveness and safety, it became widely used. The first generation of drug-releasing stents were coated with a biocompatible polymer that made it easier to control the rate at which the drug was released into the body. The second generation of drug-releasing stents were coated with a polymer that mimics the structure of human blood, making them even more stable. However, as with conventional metal stents, the problem of obstructed blood flow due to stent thrombosis was not completely solved.
To solve this problem, researchers are working on changing the polymer structure of the stent surface to make it less attractive to proteins. Since proteins tend to adhere to hydrophobic surfaces and detach from hydrophilic surfaces, this research is being done by adding large amounts of hydrophilic substituents to the polymer. In addition, instead of a stent that lasts forever, researchers are working on stents that retain their function for a period of time and then dissolve in the body once the drug release function is complete. These bioresorbable stents are expected to be safer in the long run compared to traditional metal stents. These dissolvable stents are a promising solution to the aforementioned stent thrombosis.
The treatment of heart disease is constantly evolving, and technological advances in stents are at the center of it. The development of stents as a treatment for heart disease is still a work in progress. However, this progress is not without its challenges. Since stents are biomaterials, biostability, which refers to the body’s immune response, and biocompatibility, which refers to the properties of the material, must be considered. Biostability is the absence of pyrogenic, inflammatory, antigenic, or carcinogenic reactions after implantation of the stent. Biocompatibility requires the stent to be mechanically, volumetrically, and biochemically compatible with the surrounding tissue. Successful implantation of a stent requires a customized design for the patient and a treatment plan that takes into account factors such as genetics, lifestyle, and pre-existing conditions. What started as a simple metal mesh has become a part of the body and the subject of numerous scientific studies. As the quality of life improves, the prevention and treatment of diseases will become a concern for everyone, and the need for safer and more effective treatments will arise. In the field of heart disease, stents are at the forefront of such therapies.
