Different materials for cardiovascular stents

1. Materials for
Cardiovascular
stents
MSE 536
Student- Koushik Kosanam

2. List of contents
Introduction
Coronary Artery Bypass Grafting (CABG)
Treatments for CAD
Balloon Angioplasty
Stent with Angioplasty
In stent Restenosis
Design criteria for stents
Types of stents
Conclusions
References

3. Introduction
Coronary Heart Disease (CHD),
or Coronary Artery Disease (CAD),
develops when the coronary arteries become
too narrow. The coronary arteries are the
blood vessels that supply oxygen and blood
to the heart. CHD tends to develop when
cholesterol builds up on the artery walls,
creating plaques.
Coronary Heart Disease (CHD) is the
leading cause of death globally. In Europe,
each year it is responsible for around 1.8
million deaths

4. Coronary Artery Bypass Grafting (CABG)
Complex Surgery
Chances of grafting failures
Reactions to anesthesia
Memory loss or difficulty thinking
Kidney, or renal, failure
Blood clots
Risk of bleeding from site of attached graft
and other sources
A coronary artery bypass graft involves taking a blood vessel from another part of the body
(usually the chest, leg or arm) and attaching it to the coronary artery above and below the
narrowed area or blockage. This new blood vessel is known as a graft

5. 92000 coronary artery revascularizations are currently carried out by PCI
annually, compared to around 17,000 by CABG

6. Balloon Angioplasty
Balloon angioplasty is a procedure used to open narrowed or blocked arteries.
It uses a balloon attached to a catheter that's inserted into an artery. At the
place where deposits of plaque have closed off or narrowed the channel for
blood flow, the balloon is inflated

7. A stent is a metal or plastic tube inserted into the lumen of an
anatomic vessel or duct to keep the passageway open, and stenting is
the placement of a stent

8. Stenting

9. Design criteria for stents
• Stent width – 1-2.5 mm
• Length of stent-15 to 20 mm
• Struct thickness - 95 to 200 μm
• Type of mesh
• Recoiling resistance
• High radial strength
• High elastic modulus
• Radiopacity

11. Bare Metal Stents
Materials Features
Polymers Low elastic modulus
Fe alloys High elastic modulus and susceptible to corrosion
Co-Cr Superior corrosion resistance, high radial strength,
Different grades of SS Superior corrosion resistance
NiTi Self expandable stents
Pt Ir Light weight, Superior corrosion resistance
First generation stent materials

12. In Stent Restenosis (ISR)
 blockage of artery walls in presence of stents
 injure the endothelium cells of vessels and the body starts its healing process
 involves excessive platelet adhesion/activation and recruitment and activation of neutrophils, monocytes, and macrophages,
release of cytokines and growth factors triggers smooth muscle cells to proliferate and migrate towards the lumen which
decreases the lumen diameter and blocking the blood flow after a certain period

13. Drug Eluting Stents (DES)
A drug-eluting stent is a peripheral or coronary stent
placed into narrowed, diseased peripheral or
coronary arteries that slowly releases a drug to block
cell proliferation. This prevents fibrosis that,
together with clots, could otherwise block the
stented artery, a process called restenosis.
Drug delivery rate is controlled by
 Permanent polymers -phosphorylcholine,
polyvinylpyrrolidone
 Biodegradable polymers - poly (lactide-co-
glycolide) and Poly(D,l)lactide

14. Bioresorbable Stents (BS)
Most bioresorbable stents are made of polylactic acid, a naturally
dissolvable material that is used in medical implants such as dissolving
sutures.
Limitations
recoil after expansion, stent thickness causing maneuverability and
crossing issues,
difficulty visualizing a non-metallic stent on fluoroscopy and stents
not crimping firmly on delivery balloons.

15. Conclusions
Stents play a very crucial role in solving CHD replacing complex artery bypass
surgeries. Each year in the world more than 1 million stents are being implanted
Pt Ir will become a novel stent material due to their superior corrosion resistance
and high radial strength.
DES replaced BMS and gained a lot of importance due to their drug delivery
mechanisms and latest advances like polymer-controlled Drug delivery systems and
biodegradable polymer-controlled drug delivery systems.
Bioresorbable stents are future materials for stents and many researches have been
performing using magnesium alloys for these stents

16. References
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Disease Statistics 2012, European Heart Network/ European Society of Cardiology, Brussels/Sophia Antipolis, 2012.
 Benjamin E.J., Blaha M.J., Chiuve S.E., Cushman M., Das S.R., Deo R., Floyd J., Fornage M., Gillespie C., Isasi C.R., et
al. Heart disease and stroke statistics—2017 update: A report from the American Heart Association. Circulation.
2017;135:e146–e603. doi: 10.1161/CIR.0000000000000485.
 Fuster V, Stein B, Ambrose JA, Badimon L, Badimon JJ, Chesebro JH. Atherosclerotic plaque rupture and thrombosis.
Evolving concepts. Circulation. 1990 Sep;82(3 Suppl):II 47-59. PMID: 2203564.
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Brand, E.J. Bass, N. Van Dyck, K. Leadley, K.D. Dawkins, F.W. Mohr, Percutaneous coronary intervention versus
coronary-artery bypass grafting for severe coronary artery disease, N. Engl. J. Med. 360 (10) (2009) 961–972.
 J. Gerard Wall, Halina Podbielska, Magdalena Wawrzyńska, Functionalized Cardiovascular Stents, Woodhead
Publishing,2018,Pages 45-56,
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drug-incorporated biodegradable stent matrices, J. Control. Release 98 (1) (2004) 67–74.
 Daniel Hoare Anubhav Bussooa Steven Neale Nosrat Mirzai John Mercer, The Future of Cardiovascular Stents:
Bioresorbable and Integrated Biosensor Technology, Advanced Science, 2019, 1900856.
 Torrey Schmidt and J. Dawn Abbott, Coronary Stents: History, Design, and Construction, Journal of clinical medicine,
MDPI, 2018, Vol-7.