Coronary Artery Disease
The inside wall of your arteries is normally smooth and flexible allowing blood to flow through them easily. Over time fatty deposits may build up inside the artery's wall narrowing the vessel and reducing blood flow. As a result less blood is being sent to nourish the heart muscle. When a muscle does not receive enough blood for normal function it sends out an alarm in the form of some type of discomfort. This discomfort is called angina or angina pectoris. Typically angina occurs during physical exertion or times of emotional stress when the heart rate is increased. Angina generally lasts for only a few minutes and goes away with rest. When blood flow is interrupted for 20 minutes or longer, the muscle starts to die and a heart attack (myocardial infarction) occurs.
When vessels are severely diseased and left uncorrected you are at risk for developing serious problems such as heart attacks, a weakened heart muscle (cardiomyopathy) and death. Your physician will determine a treatment plan best suited for you when blockage is observed. All treatment plans will include diet, exercise, cessation of tobacco use (this includes all nicotine products) and medication. A cardiac diet is one low in fat and in salt. Medications will vary depending on your particular situation. The more commonly used medicines include beta blockers, statins, ACE inhibitors, and blood thinners. Other treatment plans include catheter intervention of the diseased vessel or open heart bypass surgery.
Let's Talk About Interventions
When your physician recommends coronary intervention as part of your treatment plan he is recommending treatment be done using catheters placed through the skin and threaded to the area of blockage or narrowing. A procedure that is done by placing a needle through the skin into a blood vessel is known as a percutaneous procedure. As the catheter is threaded through the blood vessels, the procedure becomes a transluminal procedure (treating from within). This method of treatment is known as a percutaneous transluminal intervention.
Common percutaneous transluminal interventions include angioplasty, atherectomy and stenting. The most common of these interventions is the stent implantation. An intervention using balloon catheters to dilate a vessel is known as an angioplasty or PTCA (Percutaneous Transluminal Coronary Angioplasty). An intervention using atherectomy catheters which contain tiny drills or cutters used to ream out or cut through plaque is known as anatherectomy. In a few cases, angioplasty (PTCA) or atherectomy (reaming or cutting) is all that is needed to open a vessel but in most cases a stent is also placed.
Let's Talk About Stents
The stent is without question the most exciting invention to appear in cardiology since balloon angioplasty. Over 100,000 patients had these metal coils embedded in their heart the first year the stent was approved for use. This number has increased dramatically over the years due to its success rate of reducing angina.
Stents come in several designs. Some may look like a small metal coil, some like a slotted tube, and others appear more like a mesh tube. A stent is very tiny. It is usually less than an inch in length, as narrow as a piece of spaghetti and weighs as little as a straight pin. Yet when expanded, it possesses the capacity to stretch to the vessels largest diameter. As the obstructing cholesterol deposit (plaque) is compressed along the sides of the vessel during an angioplasty, a stent is placed to prevent recoil of the plaque. The stent remains snugly nestled in place against the wall of the vessel acting as scaffolding that supports the artery's walls. All stents are made of metal. Some are bare metal while others are coated with a special coating which contains a drug. This coating is slowly released so that only small amounts of the drug is released and absorbed into the wall of the artery at a time. These coated stents are referred to as DES (drug-eluting stents).
How is a Stent Implanted?
The stent is usually mounted on a balloon catheter that is passed over a guide wire to the site of narrowing in the artery. Once the catheter is in place, the balloon is inflated expanding the stent and pressing it against the wall of the artery. This catheter is then deflated and removed leaving the stent securely snuggled against the wall of the artery. Another balloon may be used to fully expand the stent once it is in place. One or more stents may be needed to span the length of the narrowing. These stents remain in the artery permanently. Within a few weeks a thin layer of tissue will begin to grow over the stent covering it completely making it a permanent part of the wall of the artery.
Can the Artery Narrow Again?
Ninety-five percent of the time a stent is successfully inserted into the artery. About 10% of these stents will develop restenosis (blockage) overtime. If this happens it usually occurs within the first six months of implant. After this six month period, the chance of restenosis drops drastically. Should restenosis occur you will notice a return of your previous symptoms. On an average, restenosis occurs in 30 to 40% of patients who have angioplasty alone and in less than 10% of patients who have stents placed.
There are two main causes for restenosis within a stent: blood clot formation and regrowth of tissue. During the first few weeks or months after a stent is implanted, blood clots may form and stick to the surface of the stent. If this happens there will be limited flow in the area of the stent causing you to have angina (heart discomfort) or symptoms like before the stent was implanted. If the stent is completely occluded with clot you are at risk of having a myocardial infarction (heart attack / muscle damage) if not quickly reopened. To help prevent blood clots from forming on the stent, you will go home on antiplatelet therapy (blood thinners).
Over time, narrowing within the stent can occur due to tissue regrowth. This is known as in-stent restenosis. This restenosis develops when excess tissue (scar tissue) forms during the healing process. This excess tissue then acts as a new blockage and symptoms will return same as before the stent was placed. The drug eluting stents help reduce the rate of in-stent restenosis to less than 10% by slowly releasing the drug which reduces the growth of tissue around and within the stent as healing occurs. Your physician will determine which type of stent is best suited for your blockage.
Should restenosis occur, whether it is due to clot formation or tissue regrowth, the treatment is the same. The patient is taken back to the cath lab and an angiogram (heart cath) is done to determine the cause. Often ballooning within the stent is all that is needed to open the vessel. Other times cutting balloons or other atherectomy catheters are used to clear the area within the stent then ballooning and/or restenting can be done. For many patients this second intervention within the stent seems to remain open without reoccurring restenosis. And in some cases, open heart surgery will be needed to bypass the blockage.
Post Procedure Angina
Recurrent angina (chest discomfort or heart pain) may occur during the first couple of weeks following stent implantation. Often this is due to coronary spasm. When a vessel is dilated and stretched it becomes sore and inflamed much like a cut on the skin. Until this area heals the vessel may go into spasm due to it being raw and irritated. If coronary spasm occurs you may feel angina. Whenever you have angina (heart discomfort) you should always quickly use your nitroglycerin. Remember to take the nitroglycerin every 5 minutes x 3 if needed to relieve the discomfort. If the discomfort is not relieved within the 15-20 minutes you need to seek medical attention.
Antiplatelet Therapy (Blood Thinners)
Platelets are tiny blood cells that aid in blood clotting. These cells are sticky and when clumped together form blood clots. Antiplatelet drugs work by inhibiting platelet function thus making these cells less sticky. Studies have shown that when people with known atherosclerotic disease (hardening of the arteries or cholesterol blockage) have been placed on antiplatelet drugs there is a significant reduction of strokes, heart attacks, and unstable angina.
During the first 24 hours of stent implantation the patient may receive IV antiplatelet therapy along with oral antiplatelet therapy. You should expect to go home on oral antiplatelet therapy following stent implantation. The most common of these drugs are Aspirin, Plavix, and Ticlid. Aspirin and Plavix are the most commonly used antiplatelet drugs (blood thinners) following coronary intervention.
You will be on aspirin and Plavix (clopidogrel) for at least 1-3 months following stent implantation and in most cases from 6-12 months. Your physician will determine the length of your antiplatelet therapy depending on the type and number of stents implanted. You will most likely be asked to continue taking a small dose of aspirin the rest of your life unless there are known contraindications to its use. Never stop taking your Plavix and/or aspirin without discussing it with the members of your health team. If you are concerned about the cost of taking Plavix, please let the health care team know immediately. Always remember to tell your physician that you are taking Plavix. If you are in need of elective surgery (this includes oral surgery and eye surgery) you will need to be off Plavix at least 5 days prior to the surgery. Check with your surgeon to see how long before surgery he/she wants you off the Plavix and how long after surgery before you can restart it. Then always check with your cardiologist to make sure it is safe to be off Plavix that long or should other arrangements be made. Never assume it will be OK to stop the Plavix just because another physician has requested you to do so without fully understanding the risks of complications that can occur while being off Plavix.
Even though you are walking around with a foreign object inside your body, the body rarely rejects it. You won't set off alarms at the airport or be launched skyward if you're caught in an electromagnetic field. In fact most magnets will not dislodge a stent because they are so tiny. But you will be advised not to undergo any MRI or MRA testing within the first 3 months of stent implantation without first checking with your cardiologist.
Never stop taking your antiplatelet drugs without first checking with your cardiologist. You have invested a lot of time and energy in maintaining your health and you should not jeopardize your future by stopping any of your medications without knowing the consequences that may occur.
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