Some people who have angioplasty will also need to have a stent placed in their blocked artery. The stent is usually inserted in the artery once it is widened by the inflated balloon. The stent supports the walls of the artery to help prevent it from re-narrowing after the angioplasty.
Here's what happens:
- The stent, which is mounted on a balloon at the tip of the catheter, is guided through the artery to the blockage.
- At the blockage, the balloon is inflated and the stent expands and locks into place inside the artery.
- The stent stays in the artery permanently to hold it open and improve blood flow to the heart.
- Once the stent is in place, the balloon catheter is removed and more images (angiograms) are taken to see how well blood flows through the newly widened artery.
After a stent placement, the doctor is likely to prescribe treatment with ‘blood-thinning’ medications called anti-coagulants.
What is a stent?
Stents are small expandable tubes used to treat narrowed or weakened arteries in the body. In patients with coronary artery disease (CAD), stents are used to open narrowed arteries and help reduce symptoms such as chest pain (angina) or to help treat a heart attack.
These types of stents are commonly called heart stents, but they are also referred to as cardiac or coronary stents. Usually made of metal mesh, heart stents are implanted in narrowed coronary arteries during a procedure called a percutaneous coronary intervention (PCI) or angioplasty. Stents help prevent the artery from becoming blocked again (restenosis).
There are currently five types of stents available:
- Dual Therapy Stent (DTS)
- Bioresorbable Vascular Scaffold (BVS)
- Bio-engineered Stent
- Drug Eluting Stent (DES)
- Bare Metal Stent (BMS)
Dual Therapy Stent
Dual Therapy Stent (DTS) is the latest type of coronary stent. It is a first-of-its-kind stent therapy designed to not only reduce the likelihood of the re-narrowing of the artery or of having to undergo a repeat procedure, but also help the healing process of the artery. It combines the benefit of DES and bio-engineered stents and is the only stent to contain a drug with active healing technology.
The DTS has coating both inside and outside, which reduces the likelihood of blood clots, inflammation and helps the healing process of the artery.
The stent surface facing the artery wall contains a drug that is released to help stop the artery blocking again without the worry of swelling or an inflammatory response. The drug is delivered from a bioresorbable polymer that will degrade over time.
The side of the stent which faces blood flow is coated with antibodies, which promote natural healing and helps the healthy artery function properly.
Bioresorbable Vascular Scaffold
The Bio-Vascular Scaffold (BVS) is a drug eluting stent on a dissolvable type of scaffold platform which can be absorbed by the body over time.
Like some of the currently available Drug Eluting Stents (DES), BVS is coated with a drug released from a polymer that disappears over time to reduce the likelihood of the artery re-narrowing (restenosis). The scaffold itself is absorbed overtime. Unlike with the DTS, there is no active element to promote artery healing.
Bio-engineered Stent is also known as antibody-coated stent. This type of stent differs from DES because it does not contain a polymer and does not use a drug. As a result, it helps to speed up the cell lining of the artery (endothelialization), promoting natural healing.
The antibody on the stent's surface attracts circulating Endothelial Progenitor Cells (EPCs) which come from human bone marrow and help speed up the formation of healthy endothelium. This provides rapid coverage over the stent's surface helping to reduce the risk of early and late thrombosis (blood clots).1
Drug Eluting Stent
Drug Eluting Stents (DES) are coated with medication that is released (eluted) to help prevent the growth of scar tissue in the artery lining. This helps the artery remain smooth and open, ensuring good blood flow and reduces the chances of the artery re-narrowing or restenosis. However, it also leads to a higher chance of blood clots (stent thrombosis).2
Due to a relatively slower healing process, patients implanted with DES must strictly follow their doctor's recommendation on drug therapy (DAPT) to help reduce risk of stent thrombosis. Current American Heart Association recommendations are for a minimum DAPT therapy of at least 12 months after DES implantation.3
Bare Metal Stent
Bare metal stents are usually stainless steel and have no special coating. They act as scaffolding to prop open blood vessels after they are widened with angioplasty. As the artery heals, tissue grows around the stent, holding it in place. However, sometimes an overgrowth of scar tissue in the arterial lining increases the risk of re-blockage.4
1 Lim W-H, Seo W-W, Choe W. et al. (2011) Stent Coated With Antibody Against Vascular Endothelial-Cadherin Captures Endothelial Progenitor Cells, Accelerates Re-Endothelialization, and Reduces Neointimal Formation. Arteriosclerosis, Thrombosis, and Vascular Biology. 2011; 31: 2798-2805 http://atvb.ahajournals.org/content/31/12/2798.full
2 Luscher TF, Steffel J (2007) Drug-Eluting Stent and Coronary Thrombosis Biological Mechanisms and Clinical Implications. Circulation 2007; 115: 1051-1058
3 American Heart Association (2011) ACCF/AHA/SCAI Guideline for Percutaneous Coronary Intervention 2011
4 Dangas, G., Kuepper F. (2002) Restenosis: Repeat Narrowing of a Coronary Artery. Circulation 220: 105: 2586-2587