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The stent is a small tube that is placed inside an artery in order to keep it open, restoring or preventing the decrease in blood flow due to clogging and maintaining tissue oxygenation. Generally, stent use is indicated in emergency situations to treat coronary artery blockage in the heart or to prevent rupture of aneurysms in the brain, aorta, or other blood vessels.
Most stents are made with metal or polymer, but they can also be manufactured with a special fabric, and some can be coated with drugs, called drug-eluting stents, which deliver the drug directly into the artery, which helps prevent clots from forming in the artery, which can cause it to become clogged.
Stent use should always be indicated by a cardiologist or angiologist and placed through a surgery called angioplasty. Learn how angioplasty is performed.
What is it for
The stent is used to open blood vessels that have their diameter reduced due to the accumulation of fat on the artery wall or the formation of clots that cause their clogging, preventing blood from reaching the organs and, in this way, restore and improve blood flow and the amount of oxygen in the tissues.
Generally, stents are indicated when 70% or more of the blood vessel is clogged, being used in cases of people who have obstruction of the coronary arteries in the heart, such as in acute myocardial infarction or unstable angina or even, in cases of silent ischemia, in which the person discovers that they have a clogged blood vessel through routine exams.
Stent placement must be done in hospital by the doctor, using local anesthesia with sedation or general anesthesia, with a hole being made in the groin, arm or neck where a catheter is inserted to reach the clogged artery.
In addition to coronary arteries, stents can also be used to unclog and open the passage of carotid or iliac arteries, bile ducts, bronchi, ureters, urethra, trachea, esophagus, colon, pancreas or duodenum.
Main types
Stents can have different shapes such as spiral that are more flexible, coil that adapt to the curves of blood vessels or in the form of mesh, which is a mixture of the other two types, spiral and coil.
In addition, stents are classified according to their structure and the type of material they are made of and include:
1. Bare stent
The conventional stent is made with a metal mesh such as stainless steel, cob alt-chromium or nickel-titanium, also known as a metallic stent, it does not have a special coating, acting as if it were a scaffold, supporting the vessels blood vessels and preventing their contraction, which keeps them open.
After placement of the bare metal stent and as the artery heals, blood vessel cells grow around the stent, keeping it in place, but over time, particularly in the first 12 months, and overgrowth of these cells, scarring can occur on the stent, which can again lead to clogging of the artery. In this case, a new procedure may be necessary to place a new stent inside the old one.
2. Drug-eluting stent
The drug-eluting stent is also made with a metal mesh, but it is different from the conventional stent as it is coated with drugs with anti-inflammatory and immunosuppressive action, such as sirolimus, paclitaxel, zotarolimus or everolimus, which are slowly released directly into the blood vessel and prevent scar formation and artery blockage.
This type of stent, due to its high cost, is indicated in cases of people at high risk of having a new vessel closure, such as diabetics, people with extensive blood vessel injuries or who require placement of many stents, for example.
3. Biodegradable stent
The biodegradable stent, also called bioabsorbable stent, is made with polymers such as polylactic acid, which has a more flexible structure and dissolves over time, transforming into lactic acid that is fully absorbed by the body after 2 3 years after placement.
This type of stent can be coated with a drug such as everolimus that is slowly released into the blood vessel, preventing clogging of the artery.
4. Radioactive stent
The radioactive stent delivers small doses of ionizing radiation continuously into the blood vessel, reducing the risk of scar tissue formation and accumulation and artery clogging.
This type of stent is seldom used, being indicated only for intracoronary brachytherapy, a type of radiotherapy used to prevent re-clogging of the coronary artery in people who had obstruction even after using another type of stent.
