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The story of coronary stent


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A stent is a small, expandable tube. During a procedure called angioplasty, the stent is inserted into a coronary artery and expanded using a small balloon. A stent is used to open a narrowed or clotted artery.

Published in: Health & Medicine, Business
  • In September 1977, a daring young physician in Zurich, Switzerland, performed the first angioplasty on a conscious patient with a tight lesion of the left anterior descending (LAD) artery. Andreas Grüntzig had been quietly working on a concept that he had conceived while studying under one of the great mentors of radiology, Charles Dotter. Grüntzig had watched Dotter's procedure of dilating peripheral arterial stenoses with progressively larger, tapered tubes. From these observations, he had the idea of adding a balloon to the catheter tip and a central lumen inside the catheter to fill the balloon with contrast material. On expansion of the balloon at the target site, the plaque would give way (like “crushed snow”) and, it was hoped, remain open. Grüntzig struggled to get support from many sources to build a workable prototype and to test it in animal models. He eventually was able to build a catheter suitable for human use and after much difficulty received permission to try the first case in a human. The case was a success, and the 37-year-old patient walked out of the hospital angina free without bypass surgery. The world would never be the same
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The story of coronary stent

  1. 1. The story of the coronary stent RAMACHANDRA
  2. 2. PREFACE PCI is the most common procedure for cardiologist POBA limited by dissections/ recoil/neointima/vessel closure/restenosis BMS limited by neointima[ISR- in 20%-30% of] DES limited by late stent thrombosis(Polymer without drug preventing endothelialisation) BVS limited by cost, long experience is awaited
  3. 3. POBA First successful balloon angioplasty September 16, 1977 Zurich, Switzerland  Andreas Gruentzig
  4. 4. STENT The term “stent” derives from a dental prosthesis developed by the London dentist Charles Stent (1807–1885),indicate any device used for “extending, stretching, or fixing in an expanded state The first stents were implanted in human coronary arteries in 1986 by Ulrich Sigwart, Jacques Puel, and colleagues, who placed the Walls stent sheathed self-expanding metallic mesh scaffold (Medinvent, Laus-anne, Switzerland) in the peripheral and coronary arteries of eight patients  Cesare Gianturco and Gary Roubin developed a balloon-expandable coil stent consisting of a wrapped stainless steel wire resembling a clamshell  A phase II study evaluating the Gianturco-Roubin stent to reverse POBA in acute or threatened vessel closure was started in 1988, ultimately leading to United States Food and Drug Administration (FDA) approval for this indication in June 1993 Julio Palmaz stent devised a balloon-expandable slotted stainless steel stent with rectangular diamond shaped slots is the mother of all the modern stents.
  5. 5. Gianturco-Roubin stent: Outdated Cesare Gianturco and Gary Roubin developed a balloon-expandable coil stent consisting of a wrapped stainless steel wire resembling a clamshell
  6. 6. Palmaz-Schatz stent First coronary Palmaz-Schatz stent was placed in a patient by Eduardo Sousa in São Paulo, Brazil in 1987 with a US pilot study started in 1988,is the mother of all recent stents((Johnson and Johnson Interventional Systems, Warren, NJ) )
  7. 7. Palmaz-Schatz stent Palmaz-Schatz stent, the first stent approved by the USFDA was introduced by Johnson and Johnson (J&J) in 1994
  8. 8. First stent trial(s) 1989, two randomized multicentre studies (STRESS and BENESTENT) comparing POBA to elective Palmatz-Schatz stenting. In these studies, 20% to 30% reduction in clinical and angiographic restenosis compared with POBA. Palmatz-Schatz stent approved by the FDA in 1994
  9. 9. The era and aura of DAP -1990 Antonio Colombo :reduced rates of stent thrombosis using 1.IVUS 2.routine high-pressure (>14 atmospheres) 3.Aspirin and a second antiplatelet(thienopyridine, ticlopidine) vs. warfarin
  10. 10. Stent Design  Composition of strut: Metallic or polymeric  Configuration: Slotted tube versus coiled wire  Bioabsorption:Durable or bioabsorbable  Coatings :None/ passive such as heparin/ PTFE  Bioactive :Eluting rapamycin or paclitaxel in pores in the stent wall or in polymer Implantation:Self-expanding or balloon-expandable
  11. 11. Stent Composition Non-self expanding :stainless steel- 100 to 150 μm thick and Cobalt chromium/ platinum chromium alloys - lower-profile/ thin stent struts (∼75 μm) Self expanding: Nitinol, a nickel/titanium alloy that has super-elastic Biodegradable stents:  1.Polymer of L-lactic acid (PLLA)  2. Non-polymeric :magnesium
  12. 12. Stent Configuration and Design Design Wire coils: First Gianturco-Roubin stent but later all three designs failed(Poor radial and axial strength)-outdated Slotted tubes/multicellular Most of current stent from original Palmatz’ stent Modular designs Stent lengths (8 to 48 mm) and diameters (2.25 to 6.0 mm) The initial modular stent was the Arterial Vascular Engineering Micro-Stent (subsequently purchased by Medtronic Corp., Santa Rosa, CA), which had a series of 4-mm-long, rounded stainless steel corrugated ring subunits welded to each other. Subsequent designs have incorporated an ellipto-rectangular (rounded) strut profile and progressively reduced the length of the individual modules, with progressive reductions in crossing profile and increased surface area coverage.
  13. 13. Configuration Depending on the cellular configuration, multicellular stents can be broadly sub classified as either open cell or closed cell.  Open cell (Not all struts interconnected, open area >5mm²) designs tend to have varying cell sizes and shapes along the stent, and provide increased flexibility, deliverability, and side branch access by staggering the cross-linking elements to provide radial strength. Open cell designs thus tend to conform better on bends, though the cell area may open excessively on the outer curve of an angulated segment  Closed cell (Interconnected stent struts, open area <5mm²) designs typically incorporate a repeating unicellular element that provides more uniform wall cover-age with less tendency for plaque prolapse, at the expense of reduced flexibility and side branch access. Closed cell designs also tend to straighten vessel bends more than open cell designs.
  14. 14. Stent coating to stop ST
  15. 15. Balloon-Expandable Versus SelfExpanding Stents Balloon-expandable  1.Typically 1 to 1.1 times the reference arterial diameter  2.Length several millimetres longer than the lesion  3.. Almost all stents implanted in human coronary arteries Self-expanding 1.Unconstrained diameter 0.5 to 1.0 mm greater than the adjacent reference segment to ensure contact with the vessel wall and adequate expansible force to resist vessel recoil 2. Final optimization of stent expansion usually requires additional dilatation within the stent using a high-pressure, noncompliant angioplasty balloon 3. Only few in use like The Cappella Sideguard Coronary Sidebranch stent
  16. 16. Indication Elective Bail-out
  17. 17. BMS Coronary restenosis became known as the “Achilles’ heel” of coronary stenting 20-30% at 6 months ISR Better than POBA[STRESS and BENESTENT-1 ]
  18. 18. BMS is better Metaanalysis from 13 randomized controlled trials of bare-metal stents compared to balloon angioplasty in acute myocardial infarction in 6,922 patients (adapted from De Luca et al., Int J Cardiol 2008)
  19. 19. DES
  20. 20. DRUGS
  21. 21. Generations of Drug-Eluting Stents
  22. 22. Mortality using DES vs. BMS:Not difference
  23. 23. RD 3 Generation 3rd generation strut 3rd generation polymer 3rd generation drugs Platinum chromium alloy biodegradable polymers, polymer-free stents, and biodegradable stents on the basis of poly-L-lactide (PLLA) or magnesium Zotarolimus Everelimus
  24. 24. Absorb, the 4th Revolution in Interventional Cardiology Absorb defines a new paradigm - Vascular Reparative Therapy (VRT). VRT is designed to restore the vessel to a more natural state§, making natural vascular function possible
  25. 25. BVS:?Is the future
  26. 26. Implant Tech:The operator’s skill Guide catheter  Guide wire Stent selection Adjunctive :IVUS,FFR, OCT,atherectomy, thrombectomy and distal protection devices
  27. 27. Complication of stenting Thrombosis Perforation(0.2% to 1.0%;balloon size>120% ) Dissection Infectious Endarteritis Allergic Reactions Stent embolization Side branch occlusion
  28. 28. Immediate complication of Stenting is ST
  29. 29. Risk factors for stent thrombosis
  30. 30. Minimum duration of DAP is 1 year
  31. 31. Bifurcation Stenting  20% or more of stenosis  Increased procedural complications  DES in main vessel  True bifurcation (+side branch >2mm and diseased)  Provisional stenting(main vessel stented first)
  32. 32. Strategies for bifurcation disease: Louvard et al., Heart 2004 1 & 2. Classic T-stenting beginning with side branch stenting  3. Modified T-stenting=Mini crush  4. “Crush” technique  5. Classic T-stenting beginning with main branch stenting  6. Provisional T-stenting  7. Culottes' or trousers  8. Touching stents completed or not as Y technique  9.Trouser legs and seat  10. SKS  11. Skirt
  33. 33. Dedicated bifurcation NILE PAX BIFURCATION STENT[Heart Beat intervention Pvt. Ltd. ] The Axxess stent (Devax Inc., CA, USA) The SLK-View™ stent (Advanced Stent Technologies, CA, USA) Tryton Side-Branch Stent (Tryton Medical, Inc., MA, USA) The Stentys™ coronary stent (Stentys SAS, Paris, France)
  34. 34. Conclusion Stent but no in-stent restenosis or stent thrombosis DIOR? No polymer if no more drug(Prof Renu Vira mani-2013) Does the future lies in BVS?
  35. 35. Test is dark hour