a really awesome presentation by my friend "fiz"

1. Bioabsorbable Coronary
Stents
Submitted To: Dr. Shagufta Naz
Roll no:329
BS-IV (8th Semester)
Department of Zoology
Lahore College for Women University

2. Introduction
 In medicine, a stent is any device which is inserted
into a blood vessel or other internal duct in order to expand the
vessel to prevent or alleviate a blockage.
 A bioresorbable, biodegradable, or bioabsorbable
stent serves the same purpose,
but is manufactured from a
material that may dissolve or be
absorbed in the body.
 Bioabsorbable scaffolds have been
heralded as the fourth revolution
interventional cardiology----a novel
concept in the treatment of coronary
artery disease.

3. Introduction
 Unique ability to permit the restoration of vascular physiology
and integrity as they provide a temporary scaffold.
 That is necessary to maintain the patency of the vessel after
intervention, and then they gradually dissolve, liberating the
vessel from its cage.
 Thus, it is expected that Bioabsorbable stents will potentially
overcome the limitations of the traditional stents, such as the
risk of late stent thrombosis, and the local inflammation caused
by the presence of a foreign body.

4. Material
Characteristic
s for Stents
 The material for bioabsorbable stents is requested to
have at least the following characteristics:
 It must be biocompatible.
 Degradation products of the material must also be
biocompatible.
 The material must stay in the place for several months before
its complete bioabsorption.

5. Bioabsorbable
Stent Design
 The ideal design should have:
Mechanical properties
Must be biocompatible and would be made of biocompatible
Adequate degradation time,
have good deliverability.
Ideally, it should be able to carry an antiproliferative drug in
order to reduce restenosis.

6. Mechanism of
Absorption
Degradation of polymers generally refers to cleavage
of covalent bonds between repeating units. During this chemical
process, long backbones break into smaller oligomers (or
monomers) by hydrolysis, oxidation, and enzymatic mechanisms.

7. Types of
Stents
 Regarding the material, there are two possibilities that
are being tested:
 Polymer-based materials Among the polymers, the one
that has been used more frequently is Poly-L-lactic acid
(PLLA).
 Absorbable metals such as magnesium-based alloys.

8. Bioabsorbable
Polymeric
Stents
 They employ a wide variety of polymers, such as those made
from lactic acid, glycolic and caprolactone.
 The most used polymer for is composed of poly-L-lactic acid
(PLLA). PLLA is already found in many medical items,
including dissolvable sutures and various implants, and itself has
a degradation time of 12-18 months.
 Another polymer used is the polymer-tyrosine derived
polycarbonate and it primarily degrades into L-tyrosine.

10. Dissolvable
Metallic Stents
 The biodegradable or dissolvable metallic stents consist of
either magnesium-based (Mg) or iron-based (Fe) alloys.
 These metals are alloyed with calcium (Ca), zinc (Zn) and
manganese (Mn) as they are well tolerated in the human body.
 The alloying of Fe with other metals is necessary to alter its
ferromagnetism which can reduce MRI compatibility.
 As for magnesium, it is alloyed to decrease its degradation rate
and increase its ductility and strength.

11. Magnesium based
Bioabsorbable Stent
• Mg has low
thrombogenicity + good
compatibility
• The first metallic
bioabsorbable stent
implanted in humans was
studied in the
PROGRESS-AMS trial
where 71 magnesium
stents, were implanted in
63 patients…no
thrombosis, heart attack

12. Iron based
Bioabsorbable
Stents
 This stent is made of 41mg pure iron and was
implanted in New Zealand white rabbits into its
descending aorta.
 The results from the implantation showed no significant
evidence of inflammatory response or neointimal (scar tissue
formation) proliferation.
 Iron is also an interesting candidate……
Mechanical properties.
It has a high radial strength and high ductility because of its
higher elastic modulus.
 Iron can interconvert between ferric (Fe2+) and ferrous (Fe3+)
,making it a useful component for cytochromes, oxygen-binding
molecules (hemoglobin and myoglobin), and many enzymes

13. Bioabsorbable
Coronary
Stents:
Current Status
& Clinical
Trials
 Presently, 14 different bioabsorbable stents are in preclinical
and clinical testing worldwide.
 As bioabsorbable stents receive FDA approval, the US will
acquire market share and steadily become the largest market
through 2018 and beyond.
Global Data estimates bioabsorbable stent sales to be US$4.2m
in 2012 across the US, France, Germany, Italy, Spain and the
UK, growing to over US$700m by the end of 2018.

14. Conclusion
 Bioabsorbable Scaffold have been announced as the fourth
revolution in interventional cardiology, introduce
a new concept in the treatment of coronary artery
disease.
 Since metallic stents provide better treatment but it is required to
last for 6–12 months. After this period, the presence of stent
within the body cannot provide any beneficial effects. Thus, the
development of bioabsorbable stents, which can fulfill the
mission and step away, is the logical approach.
 The advantages of the BAS are manifold, with the most key being
that it provides no triggers for stent thrombosis.
 Lastly, the use of this stent will allow a level of psychological
relief of concern to patients who dislike the idea of having a
foreign material in their bodies for the rest of their lives.

15. Put down the remote and go for walk…………
Thanks…..