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Coronary Angioplasty (PTCA)
A coronary stent delivery system with stent is guided to the site of the lesion, and once properly positioned the stent is expanded by inflating the balloon of the stent delivery system. Fully expanded, the stent is intended to compress the plaque causing the stenosis against the arterial wall.
In some cases plaque modification is needed to prepare the vessel for stent placement. Coronary plaque modification techniques include PTCA, atherotomy using a Cutting Balloon® device, and/or rotational atherectomy.
Post stent deployment, examination via fluoroscopy and/or IVUS, may dictate that further balloon inflations are needed to assure adequate stent expansion and apposition for improved blood flow down the affected artery.
Once optimal stent expansion has been achieved, the balloon catheter, guide wire and guide catheter are removed. Usually several hours post procedure (depending on the anticoagulation therapy that was administered), the sheath will be removed and is followed by mechanical or manual compression on the site until hemostasis is achieved. Unless an entry site closure device has been used, the patient will remain on bed rest for several hours after sheath removal, allowing time for the entry site to sufficiently seal.
Restenosis
In some cases, patients who undergo balloon angioplasty treatment will experience a renarrowing of the artery, or restenosis, in the area that was being treated. The renarrowing can be caused by a combination of factors including vessel recoil and formation of tissue ingrowth in the treated area.
Although coronary artery stents have been shown to reduce the occurrence of restenosis compared to balloon angioplasty, restenosis may still occur.
Drug-Eluting Stent
Sometimes referred to as a "coated" or "medicated" stent, a drug-eluting stent is a normal metal stent that has been coated with a pharmacologic agent (drug) that is known to interfere with the process of restenosis. Restenosis has a number of causes; it is a very complex process and the solution to its prevention is equally complex. However, in the data gathered so far, the drug-eluting stent has been successful in reducing restenosis. There are three major components to a drug-eluting stent:
In addition, there are several decisions made by the interventional cardiologist that factor in a successful placement:Usually the sizing and the assessments of expansion are made by viewing the real-time angiogram in the cath lab, although some cardiologists also use more detailed information obtained through intravascular ultrasound imaging.
Finally, in addition to aspirin, the patient must take an anti-clotting or antiplatelet drug, such as clopidogrel or ticlopidine (brand names Plavix and Ticlid) after the stenting, to help prevent the blood from reacting to the new device by thickening and clogging up the newly expanded artery (thrombosis). Ideally a smooth, thin layer of endothelial cells (the inner lining of the blood vessel) grows over the stent during this period and the device is incorporated into the artery, reducing the tendency for clotting.
