CORONARY STENTS yStent DR KRISHNA KUMAR. K MD DM FACC.
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Transcript of CORONARY STENTS yStent DR KRISHNA KUMAR. K MD DM FACC.
CORONARY STENTS
yStent
DR KRISHNA KUMAR. K MD DM FACC
BrachytherapyCutting BalloonDirectional AtherectomyExtraction AtherectomyLaser AtherectomyPerfusion BalloonRotational Atherectomy
19771977
20112011
Balloon Angioplasty ( March 1977)Balloon Angioplasty ( March 1977)
Bare Metal Stent (1986)Bare Metal Stent (1986)
Drug Eluting Stent (2002) Drug Eluting Stent (2002)
11stst Gen Gen
Drug Eluting Stent (2002) Drug Eluting Stent (2002)
11stst Gen GenAngioscopyDoppler Flow
Intravascular UltrasoundOptical Coherence
TomographyPalpography
Pressure MeasurementsThermography
Virtual Histology
Drug Eluting Stent (2005) Drug Eluting Stent (2005) 22ndnd gen gen
Drug Eluting Stent (2005) Drug Eluting Stent (2005) 22ndnd gen gen
Historical Overview
• 1967 - Coronary Artery Bypass Graft Surgery (CABG)• 1977 - Percutaneous Transluminal Coronary Angioplasty (PTCA)• 1978 - Idea of stent conceived• 1987 - First balloon expandable stent (Palmaz-Schatz™) implant in
human coronary artery• 1992 - Julio Palmaz and Richard Schatz: If you could only
coat this stent with a drug…..• 1993 - Introduction of Coronary Stents (BiodivYsio PC polymer
coated stent)• 2002 - Cypher Drug-eluting Stent• 2003 - Taxus Drug-eluting Stent• 2005 - Endeavor Drug-eluting Stent• 2006 - Xience V Drug-eluting Stent• 2007 - Endeavor Sprint, • 2008- Endeavor Resolute and Promus Drug-eluting Stents• 2009- Biodegradable polymer stents• 2010- Bioabsorbable stents• Future – Integrity- Newer generations of Bare-metal Stents and Drug-eluting Stents
1977
• Gruntzig – Plain balloon angioplasty.
• Dissection and acute vessel closure
• Recoil
• Restenosis
• In 1986, working in Toulouse, France, Jacques Puel and Ulrich Sigwart implanted the first stent into a human coronary artery
In 1986, working in Toulouse, France, Jacques Puel and Ulrich Sigwart implanted the first stent into a human coronary artery
TLR – 28%
TVR – 38%
2% ST
BVS Needs a drug to prevent restenosis
Type of Drug
Type of Polymer
Stent DeliverySystem
Stent Platform
The Four Key Components of STENT DesignScientific Design & Integration
Approach to Stent Material-ALLOY
• A new stent material had to meet all of the following requirements:
• L-605 cobalt chromium and 316L stainless steel have a protective chromium oxide layer and similar biocompatibility.
• Because of the different element mix, cobalt chromium is stronger and more radiopaque than stainless steel.
Cobalt Chromium Compared to Stainless Steel
Cobalt Chromium Strength• Cobalt chromium is 76% stronger than stainless
steel.• Strength of cobalt chromium allows cc stent to
have thin struts while maintaining better radial strength.
New alloy• Properties of Platinum Chromium:
• Over 2 times more dense than Iron or Cobalt, providing superior radiopacity
• Increases strength when alloyed with 316L Stainless Steel
• Vascular compatibility
• Platinum Chromium takes strength, flexibility & radiopacity a generation beyond Cobalt Chromium.
Advantages• Radial strength,
• Exceptional deliverability • Hgh visibility.
• The thin-strut stent is designed for improved conformability, minimal recoil and uniform lesion coverage and drug distribution.
• The advanced low-profile delivery system, coupled with the
radiopacity, facilitates precise delivery of the stent across challenging lesions.
Connecting Link
Terms
Element Length
Crests
Ring
Crests per Ring
1
23
54
1
2 3
5
4
6
6 Crests per Ring
5 Crests per Ring
Crests per Ring• Less Crests More Crests
• Less Scaffolding More Scaffolding
• Easier to reduce profiles
• Less Expansion Range
1
2
3
4 5
12
34
6
Connections per Ring• Less More• More Flexible Less Flexible• Less Scaffolding More Scaffolding
Element Length• Shorter
• Better scaffolding• Higher radial strength
• Wider• Poorer scaffolding
• Lower radial strength
Stent Struts
• Strut Thickness– Distance from the
inner stent surface to the outer stent surface
Width
Thickness
Thin Strut Advantage Reduce deep wall trauma
18%15%
31%26%
0%
5%
10%
15%
20%
25%
30%
35%
ISAR STEREO 1 ISAR STEREO 2
ThinMulti-link®
Thick
Strut thickness appears to have a significant impact on long-term restenosis after stent implantation.1,2
6-month binary restenosis
ThinMulti-link®
Thick
Strut Thickness TradeoffThinner
Less Visible
Less Metal in the Vessel
ThickerMore Visible
More Metal in the Vessel
Radial strength
is generally defined as the pressure which a stent exerts to the vessel or lumen into which it is implanted.
Longitudinal Foreshortening
Peak to peak
Peak to Valley connector
Offset peak-to-peak
Four Stent Design Families
Peak-to-valley
Peak-to-peak
Mid-strut connector
Element platform
Driver platform
Integrity platform
Juno platform
Nobori platform
Veriflexplatform
ProNova platform
Cypher Select platform
Coroflex Blue platform
PRO-Kinetic Energy
platform
MULTI-LINK VISION platform
MULTI-LINK 8 platform
Firebird2 platform
Express2platform
Images on file at Abbott Vascular.
Synergy platform
Promus Premier platform
Information contained herein is not intended for physicians from France or the United States.©2013 Abbott. All rights reserved. AP2938378-OUS Rev. B 04/13
1.3 1.4 1.62.6 2.5 2.9 3.2
4.65.3
1.82.7 2.8
3.6
13.2
0
2
4
6
8
10
12
14
XIENCEPRIME
0.0032 inCoCr
XIENCE V 0.0032 in
CoCr
TAXUSExpress 0.0052 in
SS
Firebird20.0034 in
CoCr
Endeavor(Driver)0.0036 in
CoNi
Nobori0.0054 in
SS
IntegrityResolute 0.0036 in
CoNi
BioMatrix Flex
0.0054 inSS
TAXUSLiberte 0.0038 in
SS
CypherSelect+0.0055 in
SS
PRO-KineticEnergy
0.0024 inCoCr
Coroflex Blue
0.0026 inCoCr
ProNOVA0.0024 in
CoCr
Element 0.0032 in
PtCr
Lo
ng
itu
din
al s
ten
t c
om
pre
ss
ion
(m
m)
81 mm81 mm
132 mm86 mm
91 mm137 mm
91 mm 137 mm 97 mm 140 mm
61 mm
66 mm61 mm 81 mm
Bench Testing: Longitudinal Stent Compression
Effect of Stent Design
Weaker
Stronger
Peak-to-valley designs Mid-strut connector designsOffset peak-to-
peak designPeak-to-peak designs
Amount of longitudinal compression under 50 gf
Tests performed by and data on file at Abbott Vascular.
Information contained herein is not intended for physicians from France or the United States.©2013 Abbott. All rights reserved. AP2938378-OUS Rev. B 04/13
What can result from LSD? The Spectrum of Adverse Events
Poor lesion coverage
Plaque prolapse
Post-dilatation of deformed stent
Difficulty re-entering stent for post dilatation
Additional stenting
Prolonged procedure as a result of additional intervention
Stent thrombosis
Restenosis
Increased vessel injury
Lack of tissue or lesion coverage
Dissection
Death
Cardiac surgery
Procedural Events Post-Procedural Events
1. Mamas, M. EuroIntervention, March 2012. 2. Williams, P. EuroIntervention, Oct. 2011. 3. Source: Bartorelli et al., Stent longitudinal distortion: strut separation (pseudo-fracture) and strut compression (“concertina” effect), EuroIntervention June 2012. 4.Stone, G. Everolimus-Eluting Stents 2011/2012 Stent Design Evolution and Clinical Trial Update, TCT 2011. 5. Leibundgut, G et al. Longitudinal Compression of the Platinum-Chromium Everolimus Eluting Stent During Coronary Implantation. Catheterization and Cardiovascular Interventions. Accepted Article. Doi 10.1002/ccd.24472.
Leibundgut, PCR 2012
OCT image showing stent crowding as a result of LSD5
Information contained herein is not intended for physicians from France or the United States.©2013 Abbott. All rights reserved. AP2938378-OUS Rev. B 04/13
Reported Clinical Events from Longitudinal Stent Deformation1,2,3,4:
Stent Platform Characteristics
• Struts thickness– Thinner struts result in:
• Lower profile stent• Improved flexibility of the stent
• Strut geometry– For DES, the greater the surface area, the higher the quantity of drug that can be
bound and delivered to target tissue.
• Material / composition– Common stent materials include stainless steel, cobalt alloy,
nitinol, tantalum.
• Cell area
• Cell design (Open versus Closed Cell)– Open cell design offers less coverage but more flexibility, side branch access and
conformity to the vessel wall.– Closed cell design offers more coverage for large plaque burden but less flexibility.
Stent Design Summary
Improve Scaffolding: More crests per ring• Shorter element length• More connections per
ring
Improve Flexibility:• Shorter element length• Less connections per
ring• Shaped or staggered
connections
Visibility:• Thicker struts
Profiles:• Thinner struts• Less crests per ring
• Expansion Range:• More crests per ring
Metal in Vessel:• Thicker struts• More crests• Shorter element length
Stent Delivery System
• Balloon-expandable – Factory mounted on a
balloon delivery system
• Self-expanding– Stent placed under a sheath– Sheath retraction allows
stent expansion
Balloon material - determines control of stent expansion and trackability.
Balloon Markers (visibility/location) - provide for ease and accuracy of stent placement.
Discrete Balloon length - minimum balloon overhang post deployment and aid in reducing potential risk of edge dissection.
Stent Security – describes the ability of the stent to stay on the delivery system, especially in tortuous trackability or during system withdrawal.
Additional Stent Design Considerations
An Ideal Stent Delivery System
Minimal Balloon Overhang
Stent Platform - Xience V and Promus DES
• Stent platform - Multi-link Vision• Slotted tube design• Cobalt Chromium – increases strength and visibility• Open-cell design enhance vessel conformability
Information available on company website and subject to change
Stent Platform – Endeavor/Sprint, Endeavor Resolute DES
• Stent platform – Driver• Modular design - thin, edgeless struts enable atraumatic delivery• Cobalt alloy composition increases strength and visibility• Open-cell design and short modular elements enhance vessel conformability
Earlier Generation Medtronic Stents
The Preferred Mechanism of Action (MOA)
The drug would ideally act early in the G1 phase, preventing entry into the S phase
G2
M
G0G1
S
CellCellcyclecycle
G0:G0: Resting (zero) stateResting (zero) state
G1:G1: Cell clears Cell clears ““checkpointscheckpoints”” in in readiness to greadiness to grow and prepare row and prepare chromosomes for replicationchromosomes for replication
S:S: DNA duplicatesDNA duplicates
G2:G2: Cell duplicates organelles, Cell duplicates organelles, prepares for Mprepares for M
M:M: Cell physically dividesCell physically divides
2 Drugs with 2 Different Targets: Pimecrolimus-Paclitaxel
Isoflavone-SirolimusDexamethazone-Zotarolimus
TacrolimusPimecrolim
us
Sirolimus, Biolimus A9 Everolimus, Zotarolimus
Isoflavone Inhibitor
Paclitaxel
Smooth Muscle Cell Mechanism of Action (MOA)
Some drugs are cytostatic and stop proliferation before the cell is committed to division
Ideal Drug for DES
All illustrations are artist renderings.
Proven Clinical Performance
– Efficacious
– Safe in systemic uses
Preferred Mechanism of Action (MOA)
– Cytostatic
– Non-inflammatory
Wide Therapeutic Window
– Excellent tissue compatibility
– Effective at multiple doses with minimal toxicity
Drug Stability
– Product yield (manufacturing)
– Shelf-life
Polymers
• Durable (permanent polymer)
• Bio-degradabale polymer
Polymer Coating Configurations
Stent
Stent
StentMatrix Only Design
Primer and Matrix Design
Primer, Matrix, and Topcoat
Design
Primer: May be applied to improve adhesion to stent
Matrix Coating: Mixture of drug and polymer
Topcoat: May be applied if needed to slow the release rate of the drug
High Drug Loading Capacity
A polymer with a high drug loading capacity, allows for a thin polymer coating
Polymer Thickness
on outer diameter (O.D.)7.8 µm
System Crossing Profile
.041"
7.8 µm
Directional Drug Delivery(abluminal preference)
• Selective coating on the
outside surface of the stent– Reduced drug/polymer– Luminal surface BMS– Drug only where needed
Properties of an Ideal DES Polymer
Hemocompatibility
– Non-thrombogenic and non-inflammatory
– Proven in other blood contacting applications
Controlled release of the drug
– Release throughout the restenosis cascade
– Complete release of drug over time
High drug loading capacity
– Thin coating thickness
– Minimizes crossing profile
Uniform Coating Integrity
– Toughness for coating integrity during delivery
– Elastic for coating integrity upon expansion
Adhere to the stent, but not the balloon
Can we do away with the polymer?
Polymer free drug-delivery
Do we need a scaffold permanently?
Late Disease Progression
Accelerated by the Presence of a Stent?
1Guiteras-Val, P., et al. Am J Cardiol. 1999;83:868-874. / 2Hatrick, R., et al. EuroIntervention. 2009;5:121-126. / 3Kimura, T., et al. Circulation. 2002;105:2986-2991.
Disease Progression: PTCA versus BMS
The Clinical Need for a Bioresorbable Vascular Scaffold
RationaleVessel scaffolding is only needed transiently*Vessel scaffolding is only needed transiently*
Vision
Potential Benefits
Rationale
Vision
Potential Benefits
Improve Long Term Outcomes for Patientsby Leaving No Scaffold Behind1
Improve Long Term Outcomes for Patientsby Leaving No Scaffold Behind1
Restore the vessel to a more natural state, capable of natural vascular function
Eliminate chronic sources of vessel irritation and inflammation
Vessels remain free for future treatment options (i.e. CABG)
Reduce the need for long-term DAPT2
Allows for use of non-invasive imaging techniques (CCTA)
Improve patient quality of life
Restore the vessel to a more natural state, capable of natural vascular function
Eliminate chronic sources of vessel irritation and inflammation
Vessels remain free for future treatment options (i.e. CABG)
Reduce the need for long-term DAPT2
Allows for use of non-invasive imaging techniques (CCTA)
Improve patient quality of life
*Serruys PW, et al., Circulation 1988; 77: 361. Serial study suggesting vessels stabilize 3-4 months following PTCA.1 – Small platinum markers at scaffold edges remain for fluoroscopic landmarking. 2. The Absorb IFU recommends DAPT for a minimum of 6 months.
Lactate
KrebsCycle
H2O
CO2
Scaffold Strut
DIFFUSION
Lactic Acid Lactate
Intracellular Mitochondrion
Lactic acid is readily converted to lactate, a common fuel source for multiple
metabolic pathways1
Lactic Acid
Resorb: Absorb is Resorbed by a Natural Process
BioMime MorphTM - Sirolimus Eluting Coronary
Stent System
Device Description Unique tapered coronary stent. Tapering diameters (1/2 sized)
Distal to Proximal – 3.50→3.00 mm & 3.00→2.50 mm
Longest lengths – 50, 60 mm Mounted on a newly created extra support Rx balloon
catheter with tapered diameters 1.25 µg/mm2 of Sirolimus, 30-days release kinetics. Biodegradable polymer base
Ø 3.50Ø 3.00
Proximal l – 50, 60 mm Distal
Ø 3.00Ø 2.50
Ø 3.50Ø 3.00
Ø 3.00Ø 2.50
= D1
= D2
D1 > D2
Actual device photographs. Data on file Meril Life Sciences.
Unmet Clinical Need A stent that matches the diameter differentials from
distal to proximal in long diffused lesions. One & done.
NEW DESIGNS
• M –GUARD
• STENTYS
• DEDICATED BIFURCATION STENTS
• Endothelial progenitor cell capturing stent
Pro-Healing approach
• Endothelial progenitor cells have been identified as a key factor in the re-endothelialization process after stent implantation.
• Orbus
• HEALING – II Study
Surfaces to Encourage Cell GrowthBioactive surfaces to accelerate functional endothelialization
Orbus – EPC Capture cell
drugpeptide
protein
device surface
Peptide linkers
Cell specific peptide linkers (Affinergy)
Nanotextured Surfaces
Example of IrOx
What will be the future?DES
Thin strut Bio-absorbable radio-opaque scaffold.
Potent limus group of drug / multiple drugs.
Non-polymer drug delivery, nano particle based.
Focus will be on Prohealing and fast re-endothelialization
Dedicated stents for bifurcations and small vessels
Definitely we can expect more….
Thank You