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Drug-Eluting Coronary Stents
By the Tovally Men:Todd Goodall Shiva Mehta
Aymen MaktariBilly Chen Max Cornell
April 17th, 2014
Overview
• Anatomy of Coronary Arteries
• Coronary Artery Disease (CAD)
• History of Treatments for CAD
• Form of the Promus Drug-Eluting Stent
• Function of the Promus Drug-Eluting Stent
Overview
• Materials of the Promus Drug-Eluting Stent
• Alternative Treatments for CAD
• Limitations of the Promus Drug-Eluting Stent
• Research and Development of Drug-Eluting Stents
• Design Recommendation for the Promus Drug-Eluting Stent
Introduction
• CAD kills 600,000 annually in the U.S.
• The drug-eluting coronary stent treats CAD.
• 640,000 stents are implanted annually in the U.S.
• Promus drug-eluting stent is a current model.
The Heart
Adapted from studyblue.com.
Right atrium
Right ventricle
Left ventricle
Left atrium
Aorta
Pulmonary artery
Coronary Arteries
Adapted from picstopin.com.
Right coronary artery
Left coronary artery
Posterior coronary artery
Aorta
Artery Cross-Section
Adapted from health.allrefer.com.
Smooth muscle
Inner lining
Exterior wall
Coronary Artery Disease
Adapted from heart.org.
Inner lining
Smooth muscle
Plaque
Normal Artery Narrowed Artery
Risk Factors for CAD
• High cholesterol• High blood pressure• Low physical activity• Unhealthy diet• Smoking• Old age• Genetics
Symptoms of CAD
• Angina
• Shortness of breath
• Rapid heartbeat
• Nausea
Causation of the Heart Attack
Adapted from myhealth.alberta.ca.
Cap Rupture Clot FormationCompletely Blocked Artery
Coronary Artery Bypass Grafting (1964)
Adapted from cardiosurgeon.co.uk and Healthwise Incorporated.
Vein graft from legInternal mammary artery graft
Coronary arteries
Before After
Balloon Angioplasty (1977)
Adapted from nhlbi.nih.gov.
Catheters
Plaque
Expandedballoon
Compressed plaque
Increased blood flow
Narrowed Artery
Widened Artery
Expanding Artery
Coronary Stents (1989 - Present)
Adapted from webmd.com and Healthwise, Inc.
Coronary stent
General Stent Structure
Connectors
Sciencedirect.com
Sinusoidal Rings
Stent Strut Cross-Section
Everolimus
PVDF-HFP Polymer
Platinum Chromium Platform
Collapsed Stent vs. Expanded Stent
Adapted from ev3.net
8 mm
2.25 mm
38 mm
4 mm
Coronary Angioplasty
Adapted from mayfieldclinic.com.
Aorta
Femoral artery
Catheter
Balloon Expansion
Adapted from hopkinsmedicine.org.
Coronary artery
Plaque
Balloon
Catheter
Guide wire
Collapsed Stent
Adapted from the British Heart Foundation.
Artery
Guide wire Stent
Plaque
Expanding Stent
Adapted from the British Heart Foundation.
Artery
Plaque
StentBalloon
Stent in Place
Adapted from the British Heart Foundation.
Plaque
Stent Artery
Drug release
Platinum Chromium Alloy Properties
Property Value UnitsYield Strength 480 MPaElastic Modulus 203 GPaCorrosion Resistance ExcellentBiocompatibility GoodDuctility 44.8% EL
PVDF-HFP Properties
Property Value UnitsElastic Modulus 0.44 GPaTensile Strength 24 MPaDegradation Period 6 MonthsBiocompatibility Excellent
Minimally Invasive Coronary Artery Bypass Grafting
Vein graft from legInternal mammary artery graft
Coronary arteries
Adapted from cardiosurgeon.co.uk and Healthwise Incorporated.
Incision Comparison
Traditional CABG Incision Minimally Invasive CABG Incision
Adapted from umm.edu
Bioabsorbable Coronary Stent
Adapted from REVA Medical, Inc.
Smooth Muscle
Plaque Stent
Stent Recoil
Inner Lining
Smooth Muscle
Plaque
Stent
Late Stent Thrombosis
Inner Lining
Smooth Muscle
Plaque
Stent
Blood Cells
Restenosis
Inner Lining
Smooth Muscle
Plaque
Stent
Tissue Overgrowth
Uneven Polymer Degradation
Drug
Polymer
Metallic Platform
Ideal Drug-Eluting Stent Properties
• High flexibility• High radial strength• Low toxicity• Bioactive nature• Consistent drug delivery
Non-Polymeric Stents
DrugMetallic Platform
Porous Surface
DrugMetallic Platform
Endothelial Progenitor Cell (EPC) Capture Stent
Antibody Coating Drug
Metallic Platform
Polymer Coating
EPC Capture Mechanism
Antigen
Endothelial Progenitor Cell
Antibody
Design Recommendation
Antibody Coating Drug
316L Stainless Steel Platform
Material ComparisonProperty Value Units (316L SS) Value Units (Platinum Chromium)Yield Strength 170 MPa 480 MPaElastic Modulus 193 GPa 203 GPaCorrosion Resistance Excellent ExcellentDuctility 40.0% EL 44.8% ELBiocompatibility Excellent Good
Advantages of the Design
Antibody Coating Drug
316L Stainless Steel Platform
Endothelial Cell
Summary
• Problem: CAD is the buildup of plaque in arteries.
• Solution: Drug-eluting coronary stents keep arteries open.
• Limitation: Arteries may still become blocked after stent implantation.
• Design Recommendation: A stent with a non-polymeric surface and an antibody coating prevents many problems.
References
• AllRefer (2010). Artery cut section. Retrieved April 15, 2014, from http://health.allrefer.com/pictures-images/artery-cut-section.html• American Heart Association (2009). Bioabsorbable coronary stents.
Retrieved April 15, 2014, from http://circinterventions.ahajournals.org/content/2/3/255/F1.expansion.html• British Heart Foundation (2012). Coronary angioplasty. London, Britain:
British Heart Foundation.• Boston Scientific Corporation (2009). The Element Stent Series. Retrieved
from http://multivu.prnewswire.com/mnr/bostonscientific/36501/docs/36501-Element_White_Paper.pdf
References
• Covidien (2013). Covidien. Retrieved March 12, 2014, from http://www.ev3.net/peripheral/intl/be-stents/paramount-mini-gps-balloon-expanding-peripheral-stent-system.htm• Crashing Patient (2011, July 14). Acute Coronary Syndromes.
Retrieved April 15, 2014, from http://crashingpatient.com/medical-surgical/cardiology/acute-coronary-syndromes.htm/• Healthwise (2013, April 17). How a Heart Attack Happens. Retrieved
April 1, 2014, from https://myhealth.alberta.ca/health/pages/conditions.aspx?hwid=zm2431
References
• Johns Hopkins Medicine (n.d.). Percutaneous Coronary Intervention (PCI), Coronary Angioplasty, and Stent Placement. Retrieved April 15, 2014, from http://www.hopkinsmedicine.org/healthlibrary/test_procedures/cardiovascular/percutaneous_transluminal_coronary_angioplasty_ptca_and_stent_placement_92,P07981/• Krasopoulos, G. (n.d.). Bypass (CABG) | Dr Krasopoulos. Retrieved March
4, 2014, from http://cardiosurgeon.co.uk/treatment-guide/bypass-cabg/• Minimally Invasive Cardiac Surgery. (2013, July 4). Retrieved from
http://filipinoinventionsanddiscoveries.blogspot.com/2013/07/minimally-invasive-cardiac-surgery-mics.html
References• NHLBI NIH (2012, February 1). How Is Coronary Angioplasty Done?
Retrieved April 15, 2014, from http://www.nhlbi.nih.gov/health/health-topics/topics/angioplasty/howdone.html• National Heart Lung and Blood Institute (2012, February 1). Explore coronary
angioplasty. Retrieved March 3, 2014, from http://www.nhlbi.nih.gov/health/health-topics/topics/angioplasty/• REVA Medical, Inc. (n.d.). Coronary Scaffold / REVA Medical, Inc. Retrieved
April 12, 2014, from http://www.teamreva.com/coronary-stent.shtml• StudyBlue (2014). Module 3 cardiovascular assessment and health promotion.
Retrieved April 16, 2014, from http://www.studyblue.com/notes/note/n/module-3-cardiovascular-assessment-and-health-promotion/deck/3911124• WebMD (2013, February 13). Coronary Stent. Retrieved April 15, 2014, from
http://www.webmd.com/heart-disease/coronary-stent
