Coronary Angioplasty and Drug-Eluting Stents - Applications of Biotechnology in Cardiovascular Therapeutics - page 259

Chapter 9
Coronary Angioplasty and Drug-Eluting Stents
Introduction
Drug-eluting stents (DES) are one of the most important devices in cardiovascular
drug delivery. Since the introduction of these stents in 2002, more than 2 million
have been implanted worldwide. DES are metal stents that are coated with a poly-
mer containing an antiproliferative agent, which is released gradually over the
course of weeks to months after the stent is inserted, thereby providing sustained
inhibition of the neointimal proliferation as a response to vascular injury, which is
responsible for restenosis. This chapter will start with an evolution of DES from
angioplasty and stents.
Percutaneous Transluminal Coronary Angioplasty
Percutaneous transluminal coronary angioplasty (PTCA) is used to widen the
stenosis of the coronary without an open surgical procedure. It is also applied for
the treatment of stenosis of the carotid arteries that supply blood to the brain. It is
carried out by positioning a catheter with a small inflatable balloon on the end
within the narrowed portion of the artery. The balloon is then inflated, which dilates
the stenosed segment of the artery by compressing the atherosclerotic plaque and
stretching the wall of the artery. This procedure is usually followed by insertion of
a stent at the site of stenosis.
Approximately 1.5 million patients undergo percutaneous coronary intervention
in the USA every year. Depending on local practices and the diagnostic criteria
used, 5-30% of these patients (75,000-450,000) have evidence of a periprocedural
myocardial infarction (MI). According to a universal definition of MI, cardiac bio-
marker (preferably cardiac troponin) level, which is more than three times the
upper reference limit is indicative of a periprocedural MI (Thygesen et al. 2007 ).
At the higher estimate, the incidence of these events is similar to the annual rate of
major spontaneous MI. Mechanism of this complication and methods for prevention
as well as management have been reviewed elsewhere (Prasad and Herrmann 2011 ).