CURRENT CORONARY STENTING Written by James F. Smith, M.D., F.A.C.C., F.S.C.A.I. Much of the work of an interventional Cardiologist is in performing coronary stent procedures and caring for those patients before and after the procedure. Recent advances have made coronary stenting safe and effective. Coronary stenting is done to clear cholesterol blockages from the arteries of patients with coronary heart disease. This is done by first placing a tube from the femoral artery (where the pulse is felt in the groin) to the coronary arteries under the guidance of X-ray. The coronary arteries are the blood vessels that provide blood supply to the heart. Next, a small guide wire is steered down the coronary artery across the blockage in that artery. This provides a track for the balloon devices, stents, or cutting devices to be passed down the artery to clear away the blockages. This is analogous to a railroad track for a train car with the guide wire being the track and the stents or other device being the train car. In most cases the first "train car" is a cigar-shaped balloon that is placed at the site of the blockage and inflated for a few minutes, then deflated and removed from the artery. In most patients the procedure doesn't stop there. The next "train car" is a stent delivery system which is another balloon catheter, but this one will have a stent mounted on the balloon. The stent is a wire mesh tube that is wrapped tightly on the balloon much like a little chicken wire fence rolled in the shape of a tube. As this balloon is inflated, the wire mesh is expanded and smashed into the artery. When the balloon is deflated, the stent stays behind as a permanent structure to hold the artery open. After the procedure is over, the catheters are removed from the groin and the patient stays in the hospital overnight usually going home the next day. Over the next few weeks the artery's inner-most lining called the endothelium will grow over the metal of the stent so there will eventually be no more metal exposed to the circulating blood. This process is called endotheliazation. There are two main problems that can occur after the coronary stent procedure. One is coronary stent thrombosis which is the sudden formation of a blood clot in the artery at the stented site. This occurs because the metal of the stent activates the body's clotting system before the endothelium has had time to cover the stent. Stent thrombosis is a devastating problem and usually causes heart attack and often death. This problem has largely been eliminated by treating the patient with anti-platelets (medicines that make it more difficult to allow the blood to clot) for several weeks to months after the stent has been implanted. The most commonly used anti-platelets are aspirin and Plavix. The other main problem is called restenosis. Restenosis is the gradual in growth of scar tissue that will then close the opening through the stent. Essentially, the endothelium forgot to stop growing once the stent became covered with the endothelium. This process occurs usually in the first six to eight months after the stent is implanted if it is going to occur. This occurs in approximately twenty percent of patients but can be as low as five percent and as high as fifty percent depending on several factors including the length and diameter of the stent and whether or not the patient has diabetes. Restenosis, although it can be a problem and cause of recurrent symptoms, does not cause death and almost never causes heart attack. This problem has been greatly diminished with the advent of the drug eluting stents (DES). DES are stents that have been coated with a drug that delays endotheliazation of the stent, thereby preventing the growth of scar tissue which causes restenosis . Since it takes longer for the stents to be covered by the endothelium, antiplatelets are necessary for a longer period of time after implantation to prevent stent thrombosis. Because anti-platelets are needed longer, some patients may not be good candidates for DES, such as someone in need of another major surgical procedure in the near future. Such patients would have an unacceptable risk of bleeding from the surgery if done while anti-platelets are continued throughout the time of surgery. With long-lasting results and low risk of complications, coronary stenting can be an excellent strategy in treating patients with coronary heart disease. If you have comments, questions or problems with this website, please contact: WebMaster@arklatexcardio.com Ark-La-Tex Cardiology, APMC. All Rights Reserved.