A covered stent is a flexible tube used to repair or support a damaged section of a blood vessel. These stents are made of a metallic frame and are covered by an extremely durable fabric. Placing a covered stent into a damaged blood vessel is a relatively simple surgery even when the blood vessels are around the heart.
The frame inside a covered stent is made out of a metal mesh, which keeps the stent from losing its form, as the blood pressure normally applied to the wall of the vessel is applied to the stent instead. A durable fabric, such as polyester, is fitted around the frame. In some cases, this fabric may only cover a portion of the stent or may only cover the inside or the outside of it. Using a stent that is completely covered decreases the risk of a tumor developing because of the device, though it is not always practical to cover the entire stent.
The most common use for this type of stent is to prevent an aneurysm in a blood vessel from rupturing. An aneurysm causes a blood vessel to balloon as a result of weakness in the wall of the vessel. Over time, the ballooning makes the vessel susceptible to tearing or ripping. When this happens in a major blood vessel, such as the aorta, it can lead to the death of the patient. Using a covered stent to provide structure and support to a damaged blood vessel can greatly decrease a patient’s risk of having a serious episode related to the presence of the aneurysm.
In most cases, a covered stent can be inserted into a patient's blood vessel through a relatively noninvasive procedure. The doctor inserts the stent into the vessel through an easy-to-access area and feeds the stent up through the vessel until it reaches the damaged section. While the doctor is maneuvering the stent into position, it is contracted into a narrow tube, making it possible for the doctor to move the stent through the blood vessel.
Once the covered stent reaches the damaged section of the blood vessel, the doctor uses a balloon to expand the stent to its full size. Once expanded, the stent fits snugly within the wall of the damaged blood vessel. The blood pressure to which the wall of the blood vessel had been subjected, now presses against the stent instead, which keeps the wall of the blood vessel from sustaining further damage.