Stent

Definition of stent

A stent is an artificial stent and is used to keep closed vessels open over the long term. In addition, stents can also be used in other hollow organs if there are occlusions or unnatural connections to other organs or if there is a threat of occlusion due to a disease process.

Indication for a stent

In most cases, stents will be used in vessels or hollow organs used when the Function through a lock (Stenosis) different cause disturbed is.

A decision is made to implant a stent in a blood vessel if a Vessel narrowed so far is that one adequate supply the underlying tissue or even an entire organ or body part is no longer guaranteed. At the most common are stents in the Coronary arteries implanted. This is often necessary when in the course of a coronary artery disease the Blood flow to the heart muscle is no longer guaranteed and so too Limitations in cardiac function comes or even one Heart attack has taken place.

Further indications are in addition to the use on the heart Vascular occlusions in the area of

• Renal arteries
• large pelvic vessels or the
• Carotid arteriesthat for the Supply of the brain are responsible and their Function therefore vital is.

In addition to vessels, stents can also keep other hollow organs of the body open. So they are an important support in the Therapy of various cancers. The one to be mentioned here Esophageal cancer, in the course of which it becomes a through tumor growth Occlusion of the esophagus can come. The implantation of a stent can die Keep the esophagus open and thus prevent a considerable impairment of the patient's quality of life from obstruction of the esophagus no independent food intake and the Ingestion of saliva allowed.

Also in other cancers, the structures like that Biliary tract or respiratory tract misplaced stents can be used in the symptomatic treatment be helpful and prevent complications. Another indication is a esophago-tracheal fistula represent, so one unnatural opening between the esophagus and windpipe. This can be closed with a stent.

Implantation of a stent in a vessel

When implanted in a vessel, the stent is usually over the strip with the help of a catheter inserted so that it can be used during surgery no big wound comes. The patient is awake only the puncture sitewhere the doctor will puncture the vessel locally anesthetized and the patient receives one Sedatives. The Inner walls of vessels do not contain Pain receptors, which is why the implantation of the stent itself not painful is.

First, in the Groin region, or more rarely, an artery on the arm is found and punctured. Now becomes one so-called lock put so it no blood loss coming through the lesion on the artery. She writes the punctured point in the vessel and keeps it open. A can now pass through the lock Catheter inserted into the vessel become.

The first thing is a Guide wire inserted, with the help of which the affected area in the vessel can be visited. Here you make use of the fact that the Metal wire very good in one X-ray image you can see. The doctor can keep checking the position during the intervention Make x-rays and so always knows exactly where it is in the vessel. Once in the right place, the catheter can now be inserted over the wire. To the Degree of constriction to be able to judge exactly again, can Contrast agent injected through the catheter the vessel can be represented well. When stenting the heart, the Administration of contrast medium by the patients more often than felt warm feeling in the chest.

After selecting the appropriate stent, the stent introduced on a balloon and up to the narrowed point advanced in the vessel. The balloon is used to dilate (widen) the vessel several times by inflating the balloon under very high pressure. Once the affected area has reached the desired internal diameter, the catheter and balloon are withdrawn again and the stent now remains on the previously narrowed point and keeps it open from now on. There are also stents that do it do not need to them with one To expand the balloon in the vesselas they unfold yourself can. In this case, however, it is necessary that the constriction is widened sufficiently with the aid of a balloon before implantation, since the stent alone cannot do this.

Following the implantation will be above the puncture site a Pressure bandage applied, so that not to rebleeding comes. This pressure bandage is allowed only removed after 24 hours be after a doctor thoroughly examined the site and found it normal. The doctor listens to him for this stethoscope the vessel off and looks for hematomas, around Damage to the vessel to recognize.

Implantation of a stent in a hollow organ

This stent implantation takes place in general anesthetic instead of. In the case of a tumor that has the The diameter of the hollow organ is reduced, this must be done beforehand by means of X-rays be examined precisely for position and size. It is advisable to provide the dimensions with metal markings, for example on the patient's chest wall, in order to find the optimal location with the aid of an X-ray image when the stent is implanted.

The stent must just as long like the area covered by the tumor, so be one long-term opening of the organ guaranteed is. If necessary, the affected bottleneck is first dilated with a balloon before implantation, then the stent is inserted. Depending on the location of the stenosis will be Stents of different materials used. Is the Stent in the appropriate place placed, it expands, this takes some time and is only fully completed after one day. Then the stent has its maximum strength reached.

Complications of stent placement

The implantation of a stent in a vessel is a low-risk procedure that rarely results in serious complications. As mentioned, bleeding or hematomas may occur at the puncture site. To avoid infection, it is essential that work is carried out under sterile conditions. The area of ​​skin over the artery to be punctured should be well disinfected so that no skin germs get into the body when the skin is pierced. An arteriovenous fistula can also occur at the injection site. This is an unnatural connection between an artery and a vein that has to be removed with the help of a laser or vascular surgery.

The contrast medium used to visualize the vessels can cause allergic reactions. With pre-existing kidney damage, caution should be exercised. Contrast media are excreted via the kidneys and can worsen impaired kidney function, which is why kidney function is checked before use. Some contrast media contain iodine; these must not be used in thyroid diseases as it can lead to a hyperthyroid crisis. Because of these risks, the function of the kidneys and the thyroid gland is also tested before an operation.

Other very rare complications are cardiac arrhythmias when a stent is implanted in the heart, which usually disappear again after the operation, but in the worst case it can also happen that a patient has to be resuscitated. Since the stent is a foreign body in the vessel, a blood clot can form. Under certain circumstances, this thrombus can block downstream vessels, which leads to the formation of an infarction in the affected tissue. In the example of the heart, a heart attack can be triggered in this way. To prevent this complication, the patient will be given highly effective anticoagulants during the intervention, which will prevent the formation of a blood clot. However, these drugs also have side effects, such as the risk of bleeding increases due to poor coagulation, and intolerance reactions can also occur.

During implantation in hollow organs, bleeding can occur due to tissue damage caused by the doctor. Bleeding or tissue damage in the area of ​​the stent is also possible. Another risk is the stent slipping, which, depending on its location, for example in the esophagus, can damage the gastrointestinal tract. The stent in the esophagus can also constrict the trachea, which leads to shortness of breath.

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