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Angiography: Bare Metal and Drug Eluting stents

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Angioplasty’s Fight against Restenosis:
Drug Eluting Stents & Bare Metal Stents
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.
Diagram of Angioplasty Procedure
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
Restenosis of Balloon Angioplasty
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.
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
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.
Early Palmaz-Schatz stent
Stenting Diagram
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.
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.
Diagram of Reoccurring Restenosis
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)
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%
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
Cypher stent which uses Sirolimus
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 paclitaxeleluting stents reduce restenosis and the need
for revascularization with a neutral effect on
mortality and myocardial infarction risk.
Taxus Stent which uses
Paclitaxel
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.
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.
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