Principles of Clinical and Engineering Integration in Hemocompatibility - Biomaterials Science: An Integrated Clinical and Engineering Approach - page 20

TABlE 2.1
Suggested Potential Advantages and Disadvantages of Biodegradable Cardiac Stents.
(These have been compared to permanent metallic cardiac stents. Important clinical
considerations are mentioned in both the advantages and disadvantages sections.)

Suggested Advantages Suggested Disadvantages

Possible higher drug-loading capacity [57,70,76] More data clinical data needed for their use

to limit important adverse effects such as
late stent thrombosis [60,70,71]

May facilitate enhanced targeted drug delivery,
limit smooth muscle cell proliferation and
enhance endothelialization on lumen [70]

Not as strong and can result in early recoil
post implantation [60]

May reduce need for a protracted dual
antiplatelet therapy [81]

May be associated with significant degree
of local inflammation [60]

May assist repeated percutaneous
revascularization or surgical intervention if
metallic stents can be avoided [78]

Relatively slow bioabsorption rate;
moreover, still may result in restenosis
[60]

Prevention of jailing of side branches and
difficulties at ostial lesions [79]

Radiolucent, which can interfere with their
positioning [60]

Facilitated magnetic resonance imaging/CT as
metallic artifacts seen in metallic stents may be
disruptive [80]

Possible difficulties with stent deployment
without fluoroscopic visualization
assistance [60]

Lack of freeze stent recoil, thereby allowing late
favorable positive remodeling [79]

Limited mechanical performance may be
abserved [60]
Limited recoil rate, thereby necessitating
thick struts. These can limit their profile
and deliver capacities particularly in
small vessels [60]
May need special storage conditions and
shorter shelf life [60]

Therefore, there are still not sufficient clinical data to make an assessment
for the clinical utility of these biodegradable stents when they are compared
to DES. More follow-up data are needed, particularly when assessing late
stent thrombosis [2, 60].

Bioabsorbable Stents

When discussing bioabsorbable stents, it is noteworthy to describe metal bio-
absorbable stents. Mg- and Fe-based alloys are two common classes. Fe and
Mg both possess low toxicity. Metals have superior mechanical properties
compared to polymers, as these alloys have similar mechanical properties to
316L, a particularly common alloy for fabricating stents. The alloy 316L has
been considered a standard reference for mechanical properties related to
new biomaterials for various stent applications [51-60].
An important clinical use for the bioabsorbable Mg-based stent has been in
pediatrics. A successful implantation of such a stent into the left pulmonary