angioplasty’s fight against restenosis: drug eluting stents & bare metal stents
TRANSCRIPT
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Angioplasty’s Fight against Restenosis: Drug Eluting Stents & Bare Metal Stents
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Balloon Angioplasty
• minimally invasive treatment to open blocked arteries.
• Within this procedure, a balloon catheter is employed to enlarge a narrowed vessel lumen stenosis.
• have shown increased coronary arterial lumen diameter, increased coronary blood flow, and decreased chest pain.
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Diagram of Angioplasty Procedure
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What is Restenosis?
• the re-narrowing of a coronary artery after dilation Coronary Angioplasty has been performed.
• six months after the procedure restenosis typically affects between 25% to 45% of patients within results in a repeat procedure.
• Restenosis is also considered an exaggeration of “vascular healing” and “remodeling” that probably occurs to some degree in all cases
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Restenosis of Balloon Angioplasty
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Fighting Restenosis
• Prior to the mid 1990’s, balloon angioplasty was the primary treatment of arteriosclerosis
• In the mid 1980's, radiologists and cardiologists worked on solutions to reduce restenosis rates;
• rotational polishers, tiny shavers, and lasers, to be delivered via catheters.
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Bare Metal Stents
• are small expandable metal tubular structures that support the vessel wall and maintain blood flow through the opened vessel (5).
• In 2001, 84% of the 1,000,000 percutaneous coronary interventions were treated with stents. Of those million, 20% or 200,000 patients develop in-stent restenosis
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History of the Bare Metal Stent
• The first stent was inserted into a human coronary artery by European researchers in 1986, in France, by Julio Palmaz and Richard Schatz.
• Julio Palmaz and Richard Schatz, lead to the first stents to be approved in the United States in 1994
• The first company to produce a coronary artery stent was Cordis, a Johnson & Johnson company, in 1994.
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Early Palmaz-Schatz stent
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Stenting Diagram
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Neointimal Hyperplasia
• is an abnormal increase in the number of cells causing a thickening of the intima of a blood vessel.
• caused by platelets that are attracted by the damaged tissue caused by the placement of a stent.
• tissue grows through the openings in the stent and eventually narrows the lumen of the vessel, therefore, reducing myocardial blood flow.
• This restenosis leads to a repeat procedure.
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Restenosis of Bare Metal Stents
• Prevalent in 10 to 30% of patients who receive bare metal stents .
• usually eliminate abrupt closures, but typically result in a restenosis rate of 25% six months after being placed.
• The majority of restenosis occurring after a bare metal stent is placed usually occurs within 30 days.
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Diagram of Reoccurring Restenosis
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Drug Eluting Stents
The invention of the drug-eluting stent came into the angiographic procedures in 2002.
The three major elements of drug-eluting stents are:
• Stent • Drug• The mechanism for controlling drug release
(usually a polymer to protect and control release)
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Two Main Types of Drug Eluting Stents
1.Cordis CYPHER sirolimus-eluting stent (April of 2003)
2.Boston Scientific TAXUS paclitaxel-eluting stent system (March of 2004)
• Both stents have shown benefits toward reducing restenosis rates up to 9%
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Cordis CYPHER Sirolimus-eluting stent
• Sirolimus is a drug used to help prevent the body from rejecting organ and bone marrow transplants.
• it helps to limit normal tissue overgrowth (restenosis) following coronary stent implantation.
• The polymer allows the drug to be released over 30 days which decreased restenosis effects.
• Since the FDA approval it is estimated that almost 450,000 of these stents have been implanted in 300,000 U.S. patients
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Cypher stent which uses Sirolimus
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Boston Scientific TAXUS Paclitaxel-eluting stent
• The drug Paclitaxel is an antineoplastic agent that inhibits cell migration and proliferation
• coated with a polymer chemical compound called Transulte (also known as SIBS).
• The Boston Corporation : Taxus I-VI studies. • These clinical trials have shown that paclitaxel-
eluting stents reduce restenosis and the need for revascularization with a neutral effect on mortality and myocardial infarction risk.
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Taxus Stent which uses Paclitaxel
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Controversy Arises with the use of Drug-Eluting Stents
• Drug eluting vs. Bare metal stent. • Research shows that the revascularization rate for bare
metal stents is only 12 to 14 percent. • It is said that the financial impact is not with the patient,
but it is the hospital taking the biggest loss. (stage the procedure, ethical or not)
• Drug eluting stents are about 2,000 dollars more than bare metal stents. (decrease $ for repeated procedures and decrease in surgery)
• An Economical Analysis (Cincinnati network of hospitals)– 3 million dollars in costs to the provider or to the hospital for
every 1000 treated patients.
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The Future of Angioplasty and Restenosis
• It is estimated that 800,000 to 900,000 individuals in the United States undergo some kind of percutaneous coronary intervention annually. Most of the procedures involve stenting.
• Drug eluting stent research seems to be at the tip of the ice berg.
• As studies progress, it will be clearer to health care providers of the details and benefits of the use drug eluting stents or bare metal stents.