Biomedical Engineering Reference
In-Depth Information
demonstrated to be more effective than medical therapy in controlling symptoms
of angina pectoris (Strauss et al. , 1995) and was rapidly established in routine clin-
ical practice. The phenomenon of re-stenosis in the first three months following
angioplasty led to further intensive research, and ultimately to the development of
intra-coronary stents. These consist of tiny metal cylinders in which multiple “cuts”
had been placed, such that when stretched over an inflated angioplasty balloon,
they stent the dilated artery. Early bare metal stents were successful in reducing
re-stenosis but not in preventing it entirely (Serruys et al. , 1994). The most recent
innovation has been to cover stents with a biodegradable material containing drugs
that inhibit re-stenosis. Gradual local release is achieved, and this further reduces
the risk of re-stenosis. Known as drug-eluting stents, they represent the most recent
innovation of the technique. Early studies suggest a substantial further reduction in
the rate of re stenosis (Morice et al. , 2002).
Thus, the evolution of coronary angiography and intervention has been a remark-
able collaboration between physicians, clinical scientists, engineers and technolo-
gists. It is also an example of where the initial invention has undergone profound
change and development through repeated innovation that was driven by the chal-
lenge to meet a major unmet clinical need, and a confidence in the ability to do so.
Development and Innovation in Cardiovascular Therapies
Several drugs in regular use today were introduced prior to the development of
modern pharmacology. Digoxin, a glycoside from the foxglove digitalis purpurea,
was used as a plant extract for many decades. Aspirin was first extracted from wil-
low as salicin in 1825 and introduced in synthetic form in 1874. Thomas Lauder
Brunton demonstrated the anti-anginal properties of amyl nitrate in the early 19th
century, long before the cause of this condition was understood. Modern develop-
ments in cardiovascular pharmacology originate in our understanding of receptor
pharmacology.
β -blockers
The discovery of adrenergic receptors (Ahlquist, 1948)and their role in autonomic
regulation of cardiovascular function led to the discovery of receptor antagonists.
β
-Blockers, discovered by Sir James Black (Black et al. , 1965), have a well-
established place in the modern therapy of angina pectoris, hypertension and cardiac
failure. The benefits of
β
-blockade all relate to antagonism of
β
-adrenergic stim-
ulation, as do most of the adverse effects associated with
β
-blockers. Successful
widespread use of
-blockers required a detailed understanding of pharmacolog-
ical effects mediated by
β
-adrenergic receptor subtypes (Lands et al. , 1967), and
on innovations in drug design to achieve selective receptor antagonism. The most
β
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