The idea of dilating disease-narrowed arteries with balloons
on catheter tips came into prominence in the 1970s due to the pioneering work
of Andreas Gruentzig, a brilliant and courageous Swiss radiologist. The first
catheters used in humans were fashioned by hand on his kitchen table. In 1977
he performed the first cath lab procedure on an awake patient. By 1980, 1,000
angioplasty procedures had been performed. It was apparent by then that one of
the major difficulties was acute closure of the artery during or just after the
procedure. Most procedures were performed with heart surgeons standing by.
Recurrent blockage over the next 6-12 months also was a problem.
It was
apparent that something needed to be done to improve the procedure. Many
biomedical engineers and scientists had been working on various devices ranging
from intra coronary cutting devices (Rotablator, Directional Atherectomy) to
stents (expandable metallic matrices that open and maintain the expansion in
narrowed arteries).
The
first coronary stent approved was the Palmaz-Schatz-Balloon Expandable Stent,
which reduced the incidence of restenosis or repeat narrowing by 25-35% over the six months post-procedure. Although the use of this stent exploded, it
was recognized that there were significant issues that limited its successful
use:
- It was somewhat rigid, making it difficult to
place
- It could not be used over long areas of narrowing
- It was disposed to clotting, and the drugs used
to prevent this caused bleeding and lengthened hospital stays
In spite
of these issues, the initial success of the Palmaz stent was encouraging. The industry
saw a huge market, the medical profession realized the breakthrough this device
had become, and the biomedical community realized that this was a fertile field
for research and development. Areas for improvement included more flexible but equally
strong materials and design, the potential for drug eluting stents, absorbable
stents, radiation delivering stents, and multiple other designs and features.
No doubt some of these ideas were science fiction, but
others were real and effective. They represented the work of many multidisciplinary
groups around the world. Today there are many device-manufacturing companies
with several models of stents and balloon catheters competing in the market
place. One of the problems along the way has been that the explosive R and D
has lead to there being many catheter improvements and stent improvements being
released before the previous device had been thoroughly used and evaluated. In
spite of this acute clotting during the procedure has been virtually eliminated
and the incidence of re-stenosis or recurrent narrowing is very low at present.
My two stents have been open for 16 years!
image credit
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Re: Coronary Stents-A Biomedical Triumph
