Talk:Bioresorbable stent

Introduction
"absorbable" links to a disambiguation page, but none of the entries there seems relevant. Should thislink be removed until there is an appropriate article to link to? —Preceding unsigned comment added by 132.244.246.25 (talk) 09:32, 16 December 2009 (UTC)

Requested edits
I am an employee of Manifest, a marketing agency representing Abbott Vascular. I would like to request edits to this page as follows. If there are errors with citation format, please let me know and I will adjust. Thank you.

In the first paragraph, third sentence, change “or bioabsorbable stent” to “or bioabsorbable, or naturally dissolving, stent”

In the “Contents” section, rename section 2 “Base Materials and Design” and delete “2.1 Iron”, “2.2 Magnesium”, and “2.3 Zinc”

Also in the “Contents” section, rename section 3 “Clinical Research”

In the “Background” section, second paragraph, first sentence, change “or bioabsorbable stents” to “or bioabsorbable, or naturally dissolving, stents.

In the “Background” section, third paragraph, second sentence, change “the goal of a bioresorbable” to “the goal of a naturally dissolving”

Change the name of the “Material Selection” section to “Base Materials” and replace the text of the section with the following:

Bioabsorbable scaffolds, or naturally dissolving stents, that have been investigated include base materials that are either metals or polymers. Those that have been approved in markets around the world and thus have gained the most traction are based on polymers that are similar to those used in dissolvable stitches.

===Polymer-based===

Polymer-based stents have been approved for use in some countries around the world. These are based on poly(L-lactide) (PLLA), chosen because it is able to maintain a radially strong scaffold that breaks down over time into lactic acid, a naturally occurring molecule that the body can use for metabolism. Other polymers in development include tyrosine poly carbonate and salicylic acid.

The Absorb naturally dissolving stent (Abbott) has several design components and features: base scaffold: a poly(L-lactide) polymer similar to that in dissolvable stitches is shaped into a tube made up of zigzag hoops linked together by bridges; drug-eluting layer: a mixture of poly-D, L-lactide (PDLLA) and everolimus; markers: a pair of radio-opaque platinum markers at the ends that allow the device to be visualized during angiography; delivery system: a balloon delivery system.

===Metal-based===

The two primary metal-based stent material candidates are magnesium, iron, and their alloys. Other traditional biocompatible base metals, such as tantalum, titanium, chromium, etc., do not degrade at an appreciable rate in the body due to passivation and thus would not be absorbed in a reasonable amount of time. Elements that are already known to play physiological roles in the human body are generally biocompatible in their metallic forms and therefore have been used as candidates for constructing bioabsorbable stents.

Magnesium is a relatively new biomaterial that has recently gained traction. While degrading harmlessly, it has been shown to possess a functional degradation time of about 30 days in vivo. This is much shorter than the three- to six-month window desired for naturally dissolving stents. Therefore, many novel methods, such as alloying, coating, etc., have been used to minimize the corrosion rate. One of the most successful has involved the creation of bioabsorbable metallic glasses through rapid solidification. As an alternative, magnesium-rare earth (Mg-RE) alloys are being developed. These benefit from the low cytotoxicity of RE elements. The application method for coatings and sophisticated materials may be altered to further decrease the corrosion rate. However, a number of issues remain limiting the further development of Mg biomaterials in general.

After the new “Base Materials” section (which replaced the “Material Selection” section), add the following new section:

==Clinical Research==

Clinical research has shown that resorbable scaffolds, or naturally dissolving stents, offer comparable efficacy and safety profile to drug-eluting stents. Specifically, the Absorb naturally dissolving stent has been investigated in single-arm trials and in randomized trials comparing it to a drug-eluting stent (DES). Early and late major adverse cardiac events, revascularizations, and scaffold thromboses have been uncommon and similar to the Xience DES, a market leader in the drug eluting stent category. Studies in real-world patients are ongoing.

Imaging studies show that the Absorb naturally dissolving stent begins to dissolve from six to 12 months and is fully dissolved between two to three years after it is placed in the artery. Two small platinum markers remain to mark the location of the original PCI. The artery is able to dilate and contract, called vasomotion, similar to a healthy blood vessel at two years. .

Recommend deleting the “Testing Bioabsorbable Materials” section because it seems out of date since it is mostly discussing in vitro testing and we have scaffolds in clinical use now.
 * ✅ Text preserved here as it may be useful for a history section

== Testing bioabsorbable materials ==

Testing bioabsorbable materials is a special challenge. Many researchers prefer to use in vitro corrosion simulations using pseudo-physiological solutions such as EMEM or HBSS. It is a point of contention, however, whether or not these solutions accurately mimic degradation in the mammillian artery. One methodological summary of in vitro corrosion concluded that DMEM, a variant of EMEM, was a suitable corrosion solution; summarized in vivo methodology and its application to magnesium alloys; reported several embodiments of in vitro corrosion tests; and argued in favor of tensile testing as a means for quantitative assessment of degradation. The variants of in vitro corrosion included typical bare wire submersion, submersion of a fibrin-coated wire, and laminar flow over a similarly coated specimen, with each approach having unique advantages. The argument for tensile testing was built on a prior publication, which demonstrated that measuring the effective tensile strength of samples with a wire geometry resulted in data that was sensitive to different materials and different corrosive environments.

Under the “See also” section, add s bullet point (note, this is for a page to be created):

Absorb Bioresorbable Vascular Scaffold

Tom at Manifest (talk) 23:47, 16 November 2015 (UTC)
 * I'm inclined to make some of these changes, but am a bit concerned that they (understandably) give too much weight to the product that you represent at he expense of competitors (for example Reva's Fantom II that is also in promising clinical trials.
 * I doubt that a single product will qualify as notable enough for its own page: time will tell however. I wouldn't support a link from here until the product page exists. Mcewan (talk) 13:41, 26 November 2016 (UTC)