Insight of drug coated stent for coronary angioplasty
Dr R Ravikumar and Dr A H M Waliul Islam
A gentleman on the way to office or wakes up from deep sleep with intense agonising pain in central chest and heaviness with a feeling of about to die, sweating, perspiration and collapsed. He was immediately taken to hospital and ECG showed his heart attack (Myocardial Infarction). Center had facilities of cardiac catheterisation laboratory; cardiologist attending the patient told him that they were planning for primary PTCA + Stenting with Drug coated stent rather than thrombolysis (as success of establishing blood flow to coronary is more). Patient may not understand what is stent or drug coated stent. This is a common picture of MI patient or their family member facing. Here, is brief introduction of it.What is a heart attack?
A heart attack occurs when the blood supply to part of the heart muscle itself -- the myocardium -- is severely reduced or stopped. The medical term for heart attack is myocardial infarction (MI). The reduction or stoppage happens when one or more of the coronary arteries supplying blood to the heart muscle is blocked. This is usually caused by the buildup of plaque (deposits of fat-like substances), a process called atherosclerosis. The plaque can eventually burst, tear or rupture, creating a snag where a blood clot forms and blocks the artery. This leads to a heart attack. A heart attack is also sometimes called a coronary thrombosis or coronary occlusion. If the blood supply is cut off for more than a few minutes, muscle cells suffer permanent injury and die. This can kill or disable someone, depending on how much heart muscle is damaged. Sometimes coronary artery temporarily contracts or goes into spasm. When this happens the artery narrows and blood flow to part of the heart muscle decreases or stops. A spasm can occur in normal-appearing blood vessels as well as in vessels partly blocked by atherosclerosis. A severe spasm can cause a heart attack. What is cardiac catherisation?
This is a procedure done on the heart. In it, a doctor inserts a thin plastic tube (catheter) into an artery or vein in the arm or leg. From there it can be advanced into the chambers of the heart or into the coronary arteries. Catheters are also used to inject dye into the coronary arteries. This is called coronary angiography or coronary arteriography. This is done to see if the arteries have blockage that could cause a heart attack. This test can measure blood pressure within the heart and how much oxygen is in the blood. It is also used to get information about the pumping ability of the heart muscle. Catheters with a balloon on the tip are used in the procedure called Percutaneous Transluminal Coronary Angioplasty (PTCA). Catheterisation is also done on infants and children to examine or treat congenital heart defects. What is coronary angioplasty?
Coronary angioplasty is a procedure that opens blocked arteries and allows blood to flow to your heart muscle. Angioplasty is not surgery. It opens a clogged coronary artery by inflating a tiny balloon in it. What is coronary artery restenosis?
Restenosis is the reocclusion, or reclogging, of a coronary artery following a successful intravascular procedure, such as balloon angioplasty or stent replacement, to reestablish adequate blood flow through the vessel lumen. What is a stent and how is one used?
A stent is a wire mesh tube used to prop open an artery that has recently been cleared using angioplasty. The stent is collapsed to a small diameter and put over a balloon catheter. It is then moved into the area of the blockage. When the balloon is inflated, the stent expands, locks in place and forms a scaffold. This holds the artery open. The stent stays in the artery permanently, holds it open, improves blood flow to the heart muscle and relieves symptoms (usually chest pain). When are stents used?
A stent may be used instead of -- or along with -- angioplasty. Stents are used depending on certain features of the artery blockage. This includes the size of the artery and where the blockage is. Stenting is a fairly common procedure; in fact, it now represents 70-90 percent of procedures. What are the advantages of using a stent?
In certain patients, stents reduce the re-narrowing that occurs after balloon angioplasty or other procedures that use catheters. Stents also help restore normal blood flow and keep an artery open if it has been torn or injured by the balloon catheter. Can stented arteries reclose?
Yes. Reclosure (restenosis) is also a problem with the stent procedure. In-stent restenosis is essentially tissue regrowth -- the body's overzealous attempt to heal the intima (innermost layer of vessel lining) where it was disturbed by the placement of the coronary artery stent. In response to vascular trauma, growth factors are produced. These growth factors stimulate smooth muscle cells to start dividing, a process known as neointimal hyperplasia. As the smooth muscle cells multiply, they push through the openings in the stent mesh and, over time, cause a narrowing in the stent lumen. In recent years doctors have used new types of stents called drug-eluting stents. These are coated with drugs that are slowly released and help keep the blood vessel from reclosing. These new stents have shown some promise for improving the long-term success of this procedure. What precautions should be taken after a stent procedure?
Patients who have had a stent procedure must take one or more blood-thinning agents after the prescription of a cardiologist. For the next four weeks a magnetic resonance imaging (MRI) scan should not be done without a cardiologist's approval. But metal detectors don't affect the stent. Reassess the patency of stent at 6 and 12 month if possible. Is there a way to minimise in-stent restenosis?
Until recently, cardiologists have had little recourse but to wait and see if restenosis occurs and then treat it. The new CYPHER® Sirolimus-eluting Coronary Stent and Paclitaxel-Eluting Stent -- described as a potential "breakthrough in interventional cardiology" -- is intended to minimize the risk of in-stent restenosis. The writers work at The Apollo Heart Center, Apollo Hospitals Dhaka.
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