Biomedical Engineering Reference
In-Depth Information
materials, manufacturing processes, greater understanding of biocompati-
bility issues and the development of stents with the ability to deliver local
sustained release of pharmacological agents.
Stents consist of a fl exible tubular mesh and have developed in a number
of forms and from a range of different materials selected for their ability
to match a number of desirable attributes including mechanical strength to
provide adequate scaffolding with thinner struts for improved fl exibility,
deliverability and reduced in-stent restenosis rates, biocompatibility and
degree of radiopacity during delivery to the target vessel and through
lesions.
Stents are designed either as metallic coils or slotted tubes (Fig. 7.1) and
may be either self-expanding, relying on the high elastic modulus of the
memory-shape alloy material, or balloon expandable. In small calibre
(a)
(b)
(c)
(d)
7
.
1
Examples of different stent structures: (a) Aqua
T3
(Cordis);
(b) Boston monorail Express
2
(Boston Scientifi c); (c) Sonic (Cordis);
(d) Frontier (Abbott Vascular).
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