The shape of various coronary stents can vary widely from one manufacturer to another. The five main categorical shapes of coronary stents are tubular, coil, ring, mesh and multi-design. Balloon-expanded stents are typically of stainless steel construction while shape-memory alloys are typically self-expanding. Because of the nature of their use, stents should ideally be very flexible while possessing enough radial strength to resist external compressive forces.
Strut thickness can negatively affect in-stent restenosis. The best-selling stent on the market, Abbott’s Xience V/Promus stent, has one of the thinnest struts available at 0.0032”. In studies comparing J&J’s sirolimus-eluting Cypher to a thin-strut, cobalt-chromium stent, Cypher was associated with a greater antiproliferative effect (P. Ortolani, et al., Catheter Cardiovasc Interv, 69[6]: 799–800, May 1, 2007). However, larger, longer-term studies would need to be conducted to produce conclusive results.
Slotted tube stents, often cut by laser from a cylinder tube, have shown themselves to be generally safer than spiral stents because the later often develops a less-smooth surface when expanded within the artery. While some stainless steel stents are laser-cut, others are welded, which (again) can cause a rougher surface, thus provoking chronic inflammation, among other complications.
Alternate stent designs, even from the same manufacturer, incorporate different shapes to facilitate more effective elution of the drug coatings to inhibit restenosis. See at right the different constructions incoporated by Boston Scientific for its Taxus Express versus Liberte stents. From Medgadget: "Boston Scientific believes that the physical shape of the stent provides better coverage and results in a more consistent deployment of the embedded drug.
The TAXUS® Liberté® Paclitaxel-Eluting Coronary Stent System is engineered specifically for consistent drug elution and impressive performance. Enhanced deliverability features allow access to the target lesion, because first you have to get there.
* Uniform stent geometry promotes even and consistent neointimal coverage
* Thin struts and enhanced stent delivery system improve deliverability
* Proven performance of paclitaxel supported by the rigor of theTAXUS clinical program
Unique Uniform Cell Geometry
* Supports even drug delivery and distribution
* Provides uniform vessel coverage for arterial support
* Reduces gaps in drug concentration loaded on the stent
Excerpt, in part, from MedMarket Diligence report #C245, "Worldwide Drug-Eluting, Bare and Other Coronary Stents Market, 2008-2017."
