Stenting is a catheter-based procedure in which a small, expandable wire mesh tube (stent) is inserted into a diseased artery, serving as a scaffold to hold it open. Currently, stenting is performed most often in conjunction with other catheter-based procedures, such as balloon angioplasty or atherectomy. The other procedures are used to partially reduce the narrowing caused by atherosclerosis, and the stent typically allows for an excellent final result to be obtained with little to no narrowing remaining within the coronary arteries. By doing a stent insertion along with these other procedures, the risk of the artery re-narrowing (restenosis) is reduced, and the risk of abrupt vessel closures during or within 24 hours of the procedure is nearly eliminated.

Within one month, the stent becomes covered with a thin layer of the artery’s inner lining cells. It will not be affected by a metal detector or most mechanical equipment. The success of a stenting procedure can be threatened by risk factors such as smoking or high cholesterol levels, which unchecked could lead to new blockages in the coronary arteries. Therefore, people receiving stents are strongly encouraged to learn and practice healthy lifestyle behaviors for good heart health.

What is stenting?

First performed in the mid-1980s, and approved by the FDA in 1994, coronary artery stenting is a catheter-based procedure in which a stent (a small, expandable wire mesh tube) is inserted into a diseased artery to hold it open. Its most common use is in conjunction with a balloon angioplasty to treat coronary artery disease. After the angioplasty reduces the narrowing of the coronary artery, the stent is immediately inserted, typically leaving less than 10 percent of the original blockage in the artery. In fact, stenting is done about 75 percent of the time after a balloon angioplasty and/or atherectomy (in which plaque is removed from an artery). Stents may also be used to restore normal blood flow in arteries that have been torn or otherwise damaged by previous catheter-based procedures (e.g., angioplasty or atherectomy).

In addition to treating the coronary arteries, stents may be inserted in many other arteries in the body, such as those affected by plaque accumulation occurring in the course of peripheral arterial disease (PAD). PAD most often occurs in the primary arteries of the brain, lower abdomen, pancreas, legs and kidneys. Stenting in PAD, for example, can be used to support and hold open arteries in the kidney (renal arteries) or the iliac arteries that supply blood to the legs. Special stents (stent-grafts) are also used to treat aneurysms, including abdominal aortic aneurysms. In a stent-graft procedure, the physician prevents blood from flowing through the aneurysm by placing one stent just above the aneurysm and a second stent just below the aneurysm. The two stents are connected by a patch of synthetic material (a graft), which provides a channel for blood to flow without entering the aneurysm.

Additional research is investigating the use of minimally invasive balloon angioplasty and stenting procedures in PAD of the carotid arteries, which supply oxygen-rich blood to the brain. During carotid artery stenting, the catheter is inserted into a blood vessel (usually the femoral artery in the groin) and fed all the way up to the blocked carotid artery.

By nearly eliminating blockage in a coronary artery, stenting can improve circulation, with potential benefits such as the following:

• Reduced chest pain, pressure or discomfort (angina)
• Less shortness of breath (dyspnea)
• Lower risk of heart attack
• Less need for additional medical treatment with drugs
• Less pain from peripheral arterial disease (if stents were placed in a limb)
• Less risk of the artery re-closing (restenosis)
• Nearly no risk of abrupt vessel closures (which occur in about 5 percent of patients who have balloon procedures without stenting, within the first 24 hours of the procedure)

The overall safety of coronary stenting has been shown in both male and female patients. While studies have shown a statistically higher risk of heart attack or death in women one month after stent insertion, the rates equaled those of men at one year.

Stenting has also impacted on individuals with diabetes. In contrast to non-diabetics, diabetics have a significantly greater risk of atherosclerosis. In addition, up to two-thirds of diabetics develop life-threatening heart or blood vessel disease. Stenting has compared favorably to balloon angioplasty in reducing the incidence of heart attack and need for repeat artery-widening procedures.

Stents are not “one size fits all.” They come in a variety of different textures, plasticities, elasticities, strengths, diameter sizes, chemistries and other properties. Whether or not stenting can or should be done depends upon a number of factors, including the following:

• The size of the artery in question
• Where the blockage is located
• The extent of the blockage
• The extent of blockage in other arteries
• The strength of the heart muscle

Stents are permanent devices that essentially become part of the cardiovascular system. Stents carry a risk of two long-term complications. First, there is the possibility of recurrence of narrowing at the site of stent placement (restenosis). The risk of restenosis is approximately 20 percent within six months of stent placement as opposed to the 40 to 50 percent risk of restenosis following a catheter-based procedure without stenting. Second, there is a 0.5 percent risk of a blood clot (thrombus) forming in the stent within three weeks of placement. To minimize this risk, medications such as aspirin and other antiplatelet drugs may be prescribed. Metal detectors have not been found to interfere with or detect the presence of stents.

What happens before stenting?
Before stenting, patients will discuss their medical history with their physician and inform him or her of any medications being taken. Certain medications may need to be discontinued or reduced at some point prior to the procedure. Aspirin may be recommended in order to help reduce the chance of blood clots forming at the stent site. Because local anesthesia is used, patients will be asked to refrain from eating and drinking after midnight before the procedure (patients with diabetes should consult with their physician regarding food and insulin intake).





What happens during stenting?
The stenting procedure takes place in a catheterization laboratory, which is usually cool and softly lit. To the patient, the “cath lab” may resemble an operating room with its many monitoring devices, video displays and x-ray cameras.

The patient will lie down on a table under an x-ray camera. He or she will be given a mild sedative and remain awake but relaxed for the duration of the procedure. Once the patient is comfortable, heart monitoring begins, an intravenous line (I.V.) is established and the area where the sheath is to be inserted is sterilely prepped and locally anesthetized. The majority of stent procedures are performed via the femoral artery in the groin. However, the brachial artery in the arm or the radial artery in the wrist can be utilized as well. The injection of the local anesthesia may result in a brief period of minimal discomfort. This is normal and should be no cause for concern. An anticoagulant is then administered through the I.V. to prevent blood clot formation within the artery during the procedure. In selected stent procedures, the use of additional anticoagulants (e.g., intravenous antiplatelet antibodies) have been shown to lower complication rates dramatically and reduce restenosis. The guiding catheter is then advanced through the sheath to the heart and is positioned near the origin of the coronary artery. The physician will inject dye (contrast medium) through the catheter. The dye can be seen on a special x-ray (fluoroscope) and serves as a road map for the procedure.

The physician and other attending medical staff may ask the patient to perform tasks such as coughing, turning the head, taking a deep breath or not speaking for a while. Throughout the procedure, heart rate will be monitored.

A guide wire is then passed through the catheter into the coronary artery and to the narrowing of the coronary artery. In most cases, the physician then performs a balloon angioplasty.

Stenting is then performed. Equipped with a premounted stent, a balloon-tipped catheter is advanced to the target area. The balloon is inflated for several seconds to several minutes, expanding the stent, which adheres to the wall of the artery. The balloon catheter is removed while the stent remains permanently fixed to the artery. About 10 percent of stenting procedures use self-expanding stents (which are not attached to a balloon-tipped catheter). By approximately four to six weeks after the stent is inserted, it will become completely covered by a thin layer of arterial tissue.






What happens after stenting?
Once the procedure is completed, the patient will be transferred to a cardiac recovery room. He or she may feel groggy from the sedative. The catheter insertion site may be bruised and sore.

If the groin area was used as the point of catheter insertion, then the patient will be instructed to lie in bed with legs out straight. The physician may choose to use one of two techniques for removing the sheath that was placed at the initiation of the procedure. The traditional technique is to wait until the effects of the anticoagulant have passed (four to six hours) and then to apply pressure while removing the sheath from the femoral artery. Another technique allows the sheath to be removed immediately after the procedure through the use of hemostatic devices that seal or stitch the femoral artery.

If the wrist or arm was used as the point of catheter insertion, then the patient does not need to stay in bed. Throughout the post-procedure monitoring, the point of catheter entrance will be checked for bleeding, swelling or inflammation. Vital signs will be continuously monitored during this observation period. Usually, the patient will stay overnight for further observation.

During the first day or two after stenting, patients should drink plenty of fluids to prevent dehydration and to help flush from the body the dye that was used during the procedure. Patients are also advised to avoid driving, bathing or smoking during this time.

Patients are given instructions from the medical staff regarding the following:

• Exercise and exertion. Patients are reminded to refrain from lifting heavy objects and engaging in strenuous exercise or sexual activity for 24 hours after the procedure.
• Care of the incision area. Bruising and soreness is possible and normal. Undue pain, swelling or inflammation may require medical attention.
• The function and use of medications and procedures. Patients will be prescribed medications (e.g., aspirin) to prevent the formation of blood clots (thrombosis) in the stent. These medications will be taken for life. Also, for four weeks following the procedure, patients will be prescribed an additional antiplatelet medication to minimize the risk of blood clot formation within the stent. Finally, in the first eight weeks after the procedure, patients will need to take antibiotics before any dental, medical or surgical procedure. Having an MRI (magnetic resonance imaging) is typically discouraged for up to six months after stent insertion, since within this timeframe the stent may be moved by the magnetic field.

What risks are associated with stenting?

Early post-stenting complications are minimal. There is, however, a small chance that stents will damage the vessel when implanted, sometimes causing a tear or dissection of the artery. However, statistics have shown that this generally does not affect long-term prognosis.

To prevent the formation of obstructing blood clots, the physician will prescribe aspirin and other antiplatelet drugs.

Approximately 20 percent of stents re-narrow (restenose) within six months of placement. This is especially true in those who have undergone balloon angioplasty, which can provoke a build-up of cells in the artery.

While restenosis does pose a risk, the restenosis rates noted for balloon angioplasty, atherectomy and other techniques are significantly greater (40 to 50 percent) when stenting is not used. Newer stenting techniques and materials continue to evolve in offering long-term vessel opening with less risk of complication. Still, depending on the type of cardiac impairment, there are patients for whom coronary artery bypass surgery may be the preferred modality to stenting.

Neglecting to alter controllable risk factors (e.g., smoking) can also affect the success rate of the stenting and any other catheter-based procedures (e.g., angioplasty).

What are the recent developments in stenting?
Recent or future developments in coronary stenting include the following:

• Smaller diameter stents (less than 2.5 millimeters) for smaller vessels
• Custom-designed stents for an optimal fit
• Stents designed for multiple sites within the same artery (including stents with side branches)
• Radioactive stents to minimize restenosis
• Delivery of radiation directly to a stent that has restenosed (intravascular brachytherapy)
• Stents coated with chemotherapeutic drugs (e.g., sirolimus) that are released into the wall of the artery to potentially minimize restenosis and the growth of scar tissue
• Anticoagulant-coated stents to prevent the formation of a blood clot in the stent
• Use of cholesterol-reducing drugs (e.g., statins) after stenting to enhance overall survival
• Stenting as an alternative or broader option for different patient groups, such as individuals otherwise needing bypass surgery or those having prior heart surgeries