What is percutaneous coronary intervention (PCI)?
- Percutaneous coronary intervention is a non-surgical method used to open narrowed arteries that supply heart muscle with blood (coronary arteries).
- Percutaneous means "through unbroken skin." Percutaneous coronary intervention is performed by inserting a catheter through the skin in the groin or arm into an artery.
- At the leading tip of this catheter, several different devices such as a balloon, stent, or cutting device (artherectomy device) can be deployed. The catheter and its devices are threaded through the inside of the artery back into an area of coronary artery narrowing or blockage.
- The "I" in percutaneous coronary intervention is for "Intervention," which means that even if the person is actively having a heart attack (myocardial infarction or MI), percutaneous coronary intervention can be used to intervene and stop the attack by opening up the narrow or blocked coronary artery. This allows blood to flow to the heart muscle.
- Percutaneous coronary intervention began as percutaneous transluminal coronary angioplasty (PTCA), a term still found in the literature, and now encompasses balloons, stents (metal scaffolding expanded inside the artery lumen), and other modifications to the catheter tip, including devices that can cut out plaque and thus open up the narrowed artery.
- Although treatment of acute heart attack is a very important use of percutaneous coronary intervention, it has several other uses. Percutaneous coronary intervention can be used to relieve or reduce angina, prevent heart attacks, alleviate congestive heart failure, and allows some patients to avoid surgical treatment (coronary artery bypass graft or CABG) that involves extensive surgery and often long rehabilitation time.
What is balloon angioplasty?
Balloon angioplasty employs a deflated balloon-tipped narrow catheter that is inserted through the skin of the groin or arm into an artery. The catheter is threaded through the artery until it arrives in the coronary artery where there is narrowing or blockage. The catheter tip is then inserted through the narrowed area. Once in the narrowed area, the balloon is inflated, mashing the plaque into the vessel walls to reduce the narrowing (see Figure 1).
The balloon is then deflated and the catheter removed. The process is viewed by injecting a dye that allows the cardiologist to view the flowing blood as it goes through the arteries. This viewing method (angiogram) can be used to assure that the artery has increased blood flow after the balloon is deflated and removed.
What is a stent?
A stent is an extendable metal scaffold that can be used to keep open previously narrowed coronary arteries after angioplasty has been performed. The mechanism used to place the stent in a narrowed or blocked coronary artery is very similar to balloon angioplasty. The difference is that the un-extended or collapsed stent surrounds the balloon. The stent surrounding the balloon is expanded when the balloon is inflated (see previous diagram). After the stent surrounding the balloon extends, it locks into place against the plaque/arterial vessel wall. The stent stays inside the artery after the balloon is deflated. Stents are useful because they keep the coronary artery open when the balloon is deflated, preventing most arteries from narrowing again (termed elastic recoil) after the balloon is deflated. Recurrent narrowing (restenosis) sometimes may still occur after the stent is placed due to formation of scar tissue.
The newest stents are termed drug-eluting stents. These stents are covered in a drug that slowly comes off the stent and prevents cell proliferation (scarring or fibrosis) at the stent site more effectively than uncoated, bare-metal stents.
There are many other stents beside coronary stents that are used for various other arteries and tissues. These include carotid artery stents (for stroke prevention), femoral artery stents, prostatic stents, esophageal stents, and many others.
How does coronary disease develop?
The major problem that develops with coronary arteries is the narrowing of their inner passageway (lumen), which in turn restricts, or in severe situations stops the flow of blood to the heart muscle. This restriction or stoppage of blood flow causes heart muscle damage or death because of lack of oxygen. If the occluded coronary artery is a small branch, it is possible that only a small segment of heart muscle will be injured or die, but the person will likely survive. If the occluded artery is large, death is more likely. Angina or chest pain occurs when a coronary artery becomes occluded enough to cause a reduced blood flow that does not meet the demand for oxygen required by the heart muscle.
The most frequent cause of coronary artery narrowing is cholesterol deposits (plaques) that build up in the arteries. Limiting cholesterol in the diet or by slowing its synthesis by the body with medication (or both) are major ways to help limit arterial narrowing. Many other factors may play a role in coronary heart disease such as genetics, disease such as diabetes, lifestyles such as choosing to smoke, and even drug abuse such as using cocaine.
How is coronary heart disease treated?
Treatment of coronary artery disease centers around one main issue – the inadequate blood flow in the coronary arteries cannot meet the oxygen demand of the heart muscle. To prevent heart attacks, diet modification and medications (some designed to reduce cholesterol, others to reduce oxygen demand) are used. Mechanical methods, such as percutaneous coronary intervention and CABG (coronary artery bypass grafts) are procedures used to open the narrowed blood vessels of coronary artery disease.
What are the complications of percutaneous coronary intervention?
Although most percutaneous coronary intervention procedures are successful, there are a few patients that still have problems. For example, sometimes the catheter (or its guide wire) cannot get through the narrowed lumen, or a thrombus (blood clot) forms at the site if the inner lining of the artery tears at the balloon site. Although agents are used to chemically prevent clot formations, not all treatments are successful. A small percentage of current percutaneous coronary intervention procedures fail and may require emergent CABG surgery. The risk of a heart attack is minor in people that have percutaneous coronary intervention.
Current percutaneous coronary intervention mortality is less than very low. One large (905 patients) study reports an incidence of 6.7% patients develop a hematoma at the catheter entry site (groin or arm). Some patients may develop an aneurysm in the artery at the catheter entry site. Most patients will experience some bruising and tenderness at the catheter entry site.
How do patients recover after percutaneous coronary intervention?
Patients usually recover well after percutaneous coronary intervention. They are monitored and observed after the procedure. About 4–12 hours later, any catheter equipment still in the skin and artery are removed and pressure is held by hand or by clamps or "sandbags" for about 20 minutes to prevent bleeding into the catheter insertion site. Alternatively, some patients may have the artery sutured shut where the catheter was placed. Blood clots can form at the PCI site that may cause blockage. Patients are treated with blood thinning anti-platelet agents such as clopidogrel bisulfate (Plavix) and aspirin. Most patients will be taking anti-platelet medication indefinitely. Patients are often discharged within 24 hours after percutaneous coronary intervention and are cautioned not to do any vigorous activity or lift over about 20 lbs for about one to two weeks. Some patients may be referred to a rehabilitation center, but most patients are not, and can go back to work (if work is not physically intensive) in about three days after percutaneous coronary intervention.
What are the long-term results of percutaneous coronary intervention?
As the percutaneous coronary intervention technique has advanced from balloon, to balloon plus stent, to balloon plus drug-eluting stent, the long-term results have improved so recurrent narrowing or blockage occurs in less than 10% of patients. If there is no evidence of recurrence of narrowing or blockage (for example, a negative stress test) after about12 months, the majority of stented coronary arteries remain open in the stented area for many years. Unfortunately, other areas of the artery may require an additional stent in the future. Also, patients that fail to take their prescribed anti-platelet medication and continue a lifestyle that promotes coronary artery cholesterol accumulation and arterial narrowing are more likely to have either stent failure or have additional arterial areas develop narrowing or blockage.