Stent


Image Caption : Stent with Umbrella Filter : An angioplasty in the carotid arteries can pose the very serious risk of creating embolisms, tiny blood clots, which may travel to the smaller blood vessels of the brain. There they can become lodged and cause a stroke. To guard against this, a tiny umbrella-like filter can be attached to the stent, a coil of wire mesh used to expand the blocked vessel. At the end of the stenting procedure, the filter and its debris are removed from the artery.

What Is a Stent?

A stent is a small mesh tube that's used to treat narrow or weak arteries. Arteries are blood vessels that carry blood away from your heart to other parts of your body.

A stent is placed in an artery as part of a procedure called percutaneous coronary intervention (PCI), also known as coronary angioplasty. PCI restores blood flow through narrow or blocked arteries. A stent helps support the inner wall of the artery in the months or years after PCI.

Doctors also may place stents in weak arteries to improve blood flow and help prevent the arteries from bursting.

Stents usually are made of metal mesh, but sometimes they're made of fabric. Fabric stents, also called stent grafts, are used in larger arteries.

Some stents are coated with medicine that is slowly and continuously released into the artery. These stents are called drug-eluting stents. The medicine helps prevent the artery from becoming blocked again.

National Heart, Lung and Blood Institute / NIH

How Is Percutaneous Coronary Intervention Done?

Before you have percutaneous coronary intervention (PCI), your doctor will need to know the location and extent of the blockages in your coronary (heart) arteries. To find this information, your doctor will use coronary angiography (an-jee-OG-rah-fee). This test uses dye and special x rays to show the insides of your arteries.

During angiography, a small tube (or tubes) called a catheter is inserted into an artery, usually in the groin (upper thigh). The catheter is threaded to the coronary arteries.

Special dye, which is visible on x-ray pictures, is injected through the catheter. Thex-ray pictures are taken as the dye flows through your coronary arteries. The dye shows whether blockages are present and their location and severity.

During PCI, another catheter with a balloon at its tip (a balloon catheter) is inserted in the coronary artery and placed in the blockage. Then, the balloon is expanded. This pushes the plaque against the artery wall, relieving the blockage and improving blood flow.

PERCUTANEOUS CORONARY INTERVENTION

Figure A shows the location of the heart and coronary arteries. Figure B shows a deflated balloon catheter inserted into a coronary artery narrowed by plaque. The inset image shows a cross-section of the artery with the inserted balloon catheter. In figure C, the balloon is inflated, compressing the plaque against the artery wall. Figure D shows the widened artery with increased blood flow. The inset image shows a cross-section of the widened artery and compressed plaque.
Figure A shows the location of the heart and coronary arteries. Figure B shows a deflated balloon catheter inserted into a coronary artery narrowed by plaque. The inset image shows a cross-section of the artery with the inserted balloon catheter. In figure C, the balloon is inflated, compressing the plaque against the artery wall. Figure D shows the widened artery with increased blood flow. The inset image shows a cross-section of the widened artery and compressed plaque.


A small mesh tube called a stent usually is placed in the artery during the procedure. The stent is wrapped around the deflated balloon catheter before the catheter is inserted into the artery.

When the balloon is inflated to compress the plaque, the stent expands and attaches to the artery wall. The stent supports the inner artery wall and reduces the chance of the artery becoming narrow or blocked again.

Some stents are coated with medicine that is slowly and continuously released into the artery. They are called drug-eluting stents. The medicine helps prevent scar tissue from blocking the artery following PCI.

PERCUTANEOUS CORONARY INTERVENTION WITH STENT PLACEMENT

Figure A shows the location of the heart and coronary arteries. Figure B shows the deflated balloon catheter and closed stent inserted into the narrow coronary artery. The inset image shows a cross-section of the artery with the inserted balloon catheter and closed stent. In figure C, the balloon is inflated, expanding the stent and compressing the plaque against the artery wall. Figure D shows the stent-widened artery. The inset image shows a cross-section of the compressed plaque and stent-widened artery.
Figure A shows the location of the heart and coronary arteries. Figure B shows the deflated balloon catheter and closed stent inserted into the narrow coronary artery. The inset image shows a cross-section of the artery with the inserted balloon catheter and closed stent. In figure C, the balloon is inflated, expanding the stent and compressing the plaque against the artery wall. Figure D shows the stent-widened artery. The inset image shows a cross-section of the compressed plaque and stent-widened artery.
National Heart, Lung, and Blood Institute / NIH

In medicine, a stent is a metal or plastic tube inserted into the lumen of an anatomic vessel or duct to keep the passageway open, and stenting is the placement of a stent. There is a wide variety of stents used for different purposes, from expandable coronary, vascular and biliary stents, to simple plastic stents used to allow the flow of urine between kidney and bladder. Stent is also used as a verb to describe the placement of such a device, particularly when a disease such as atherosclerosis has pathologically narrowed a structure such as an artery.

A stent should be differentiated from a "shunt". A shunt is a tube that connects two previously unconnected parts of the body to allow fluid to flow between them. Stents and shunts can be made of similar materials, but perform two different tasks.


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