Definition & Overview
A stent is a tubular, metal or plastic-mesh like material used to either expand narrow arteries or strengthen weak arteries with the goal to improve blood flow and prevent the development of various conditions including heart attack. The placing of stent is usually a part of a procedure called percutaneous coronary intervention (PCI).
PCI, which is also referred to as coronary angioplasty, is a non-surgical procedure that inserts a thin tube with a balloon at its tip through the skin either in the upper thigh or arm to reach the blocked artery. Arteries are typically blocked by a buildup of a waxy substance (plaque) that prevents the normal flow of blood to the heart. This condition is called atherosclerosis (for any type of artery) but is called coronary heart disease (CHD) when the coronary arteries are blocked. This condition causes worrying symptoms such as discomfort and chest pain (known as angina). If the plaque ruptures, a blood clot is formed that can totally block blood flow to the heart, and this can lead to a heart attack.
A basic coronary angioplasty involves the insertion of a balloon mounted on a catheter. The balloon is inflated at the site of the blocked artery to open it up, compressing the plaque against the artery wall to let the blood flow normally. However, despite the fact that coronary angioplasty has been practiced for decades, it still has a few areas that need improvement. For instance, a balloon can be inflated unevenly depending on the hardness of the plaque. The irregular surface of the inner lining of the artery created by the uneven balloon may increase the risk of complete arterial blocked in some patients. Thus, stenting is recommended.
Stenting starts out similarly like a coronary angioplasty where a balloon is inserted to open up the blocked area. This is called as pre-dilation and is required to easily position the stent. The stent is already mounted on the balloon and as the balloon is inflated, the plaque is pushed to the arterial wall. The stent will then be placed to keep the diseased artery open. When the cardiologist is satisfied with the size of the opening and the normal flow of blood is restored, the balloon is deflated and is retracted together with the catheter. If not, the balloon may be reinflated until the desired size is achieved. The stent remains in place.
The insertion of a stent has a high satisfactory result in the removal of the blockage. It also reduces the abrupt closure of the artery compared to angioplasty and provides a better chance that the blockage will not return.
Who Should Undergo & Expected Results
Since stents are normally used to improve and normalize blood flow in blocked arterial passages, an evaluation is necessary if stenting is the right procedure for the patient. Factors to be considered include:
- The patient’s overall health
- The size of the affected blood vessel and number of coronary arteries involved
- The location of the affected coronary artery
- If the blockage can be cleared out by angioplasty
- The patient's health history particularly conditions that affect the heart
How Does the Procedure Work?
The first step in determining whether a patient is a candidate for a stent procedure is the evaluation of his medical history. Factors to consider include:
* If the patient is a candidate for coronary heart disease
* If he is a candidate, what treatments has he undergone
* If the patient has been evaluated for stent procedure
Here, the doctor will be able to determine if the patient is a candidate for coronary heart disease. In some cases, a patient may have previously been diagnosed with coronary heart disease but has yet to be evaluated for a stenting procedure.
The next step may involve diagnostic and laboratory tests. An angiogram may be recommended to confirm whether the patient has blocked coronary arteries. This will also determine if the patient requires simple angioplasty or stenting. The patient may also need cardiac catheterization, a medical procedure that inserts a catheter into a blood vessel in the arm, groin, or neck threaded to the heart. Through this catheter and the injection of a special type of dye, the doctor can take pictures of the heart. The dye is useful in highlighting the build-up of plaque inside the coronary arteries. Any of these processes can determine the severity of the blockage in the arteries and can help guide the doctor in recommending a stent procedure to treat the problem.
The third step may be considered a Q & A session between the patient and doctor. To fully understand the procedure, the patient is encouraged the following questions.
- What type of stent is right for me?
- Will I have the stent permanently? How will it affect my life?
- Can the stent move or be dislocated?
- Will the metal stent trigger airport metal detectors or security checkpoints?
- Will I experience the symptoms I had before I had the stent procedure?
- Is there a possibility of my artery re-narrowing?
Possible Risks and Complications There are certain risks with percutaneous coronary intervention (PCI), which stenting is a part of and these include:
- Bleeding at the location where the catheter is inserted
- Blood vessel damage from the catheter
- Damage to kidneys from the dye used in the procedure
- Allergy to the dye used in the procedure
The more serious complications, which rarely occur, include the development of blood clots a few months after the stent procedure. To counter this, the doctor may recommend aspirin and/or other anti-clotting medicine to take for a year or more after having the stent procedure.
Another risk is the development of too much tissue around the stent area that may lead to the artery getting blocked again. Drug-eluting stents are a work-around to this problem.
Amarenco P, Labreuche J, and Mazighi M: Lessons from carotid endarterectomy and stenting trials. Lancet. 2010;376(9746):1028-31. PMID: 20870079 www.ncbi.nlm.nih.gov/pubmed/20870079.
Brott TG, Hobson RW, Howard G, et al: Stenting versus endarterectomy for treatment of carotid-arery stenosis. N Engl J Med. 2010;363(1):11-23. PMID: 20505173 www.ncbi.nlm.nih.gov/pubmed/20505173.