News Column

Patent Issued for Process for Producing a Haemocompatible Article of Complex Configuration and Article Thus Obtained

June 2, 2014



By a News Reporter-Staff News Editor at Cardiovascular Week -- According to news reporting originating from Alexandria, Virginia, by NewsRx journalists, a patent by the inventors Capel, Antoine (Clamart, FR); Carpentier, Alain (Paris, FR); Melot, Marion (Paris, FR), filed on April 28, 2008, was published online on May 20, 2014 (see also Carmat).

The assignee for this patent, patent number 8728264, is Carmat (Velizy Villacoublay, FR).

Reporters obtained the following quote from the background information supplied by the inventors: "It is known that the surfaces of implanted medical devices, in direct contact with blood, must in no way impair blood tissue, nor stem the flow of blood. They must therefore be perfectly hemocompatible.

"Moreover, it is known that expanded polytetrafluoroethylene, generally denoted in the art by e-PTFE, is widely used for producing such hemocompatible articles (see, for example, the documents U.S. Pat. No. 4,743,480, WO-95/05277, WO-96/00103, U.S. Pat. No. 5,665,114, EP-0 692 264, U.S. Pat. No. 6,039,755, WO-02/100454 and WO-03/093356). The reason for this is that e-PTFE has remarkable hemocompatibility properties, especially as regards chemical stability and porosity. However, its high degree of crystallinity (close to 95%) and its unique three-dimensional structure consisting of nodes and fibers give it a high shape memory, even at high temperature.

"Therefore, the hemocompatible articles made of e-PTFE that can be obtained at the present time necessarily have simple shapes, such as sheets or tubes."

In addition to obtaining background information on this patent, NewsRx editors also obtained the inventors' summary information for this patent: "The aim of the present invention is to remedy this drawback by providing hemocompatible articles of complex configuration.

"For this purpose, according to the invention, the method for producing a hemocompatible article, in which method: a forming mold having the configuration of said article is produced; a polytetrafluoroethylene membrane is conformed to the configuration of said article by heating it and applying it against said forming mold by means of a pressure difference generated between the two faces of said membrane; said membrane thus conformed is cooled while still keeping it applied against said forming mold; and said conformed membrane is removed from said forming mold, is noteworthy in that: said membrane is made of an expanded polytetrafluoroethylene which has not been thermally stabilized, prior to its conformation to the configuration of said article, and the fibers of which membrane have no preferred orientation; and said membrane is heated while it is being conformed to the configuration of said article, up to a temperature above the gel point of said expanded polytetrafluoroethylene.

"The Applicant has noted that, hitherto, the e-PTFEs used for producing hemocompatible articles have a structure in which said fibers have a preferred orientation and that if, on the contrary, an e-PTFE is used in which the fibers do not have any preferred orientation, this e-PTFE can be conformed by thermoforming, as is usual in the case of ordinary polytetrafluoroethylenes (see, for example, WO 96/16601).

"Thanks to the present invention, it is therefore possible to obtain hemocompatible articles made of e-PTFE having a complex shape.

"Advantageously, said membrane is heated with hot air. The temperature to which said membrane is heated may be around 400.degree. C.

"Preferably, the heated membrane is applied against said forming mold by a vacuum through the latter.

"In addition, said cooling of the conformed membrane may be accelerated cooling, for example by blowing cold air.

"Said hemocompatible article obtained by implementing the present invention may advantageously form a coating for an implantable prosthesis or prosthesis part having said configuration. In this case, after said membrane conformed to the configuration of said prosthesis or prosthesis part has been removed from said forming mold, said membrane is bonded to said prosthesis or prosthesis part, for example by means of an elastomer, such as a silicone.

"For bonding the conformed membrane to said prosthesis or prosthesis part, said conformed membrane may be mounted on an inflatable tool of similar shape and, after said conformed membrane has been brought into contact with said prosthesis or prosthesis part via at least one layer of adhesive, said tool is inflated so as to compress said layer and ensure that it has a uniform thickness.

"It goes without saying that the method according to the present invention may be implemented for producing all kinds of hemocompatible articles. However, in one particularly advantageous application, the hemocompatible article constitutes a coating for a cardiac prosthesis or part of a cardiac prosthesis, such as an artificial ventricle. Said cardiac prosthesis is therefore noteworthy in that at least one of its parts has such a hemocompatible coating.

"The figures of the appended drawing will clearly explain how the invention can be realized. In these figures, identical references denote similar elements."

For more information, see this patent: Capel, Antoine; Carpentier, Alain; Melot, Marion. Process for Producing a Haemocompatible Article of Complex Configuration and Article Thus Obtained. U.S. Patent Number 8728264, filed April 28, 2008, and published online on May 20, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=105&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=5210&f=G&l=50&co1=AND&d=PTXT&s1=20140520.PD.&OS=ISD/20140520&RS=ISD/20140520

Keywords for this news article include: Carmat, Cardiology, Prosthetics, Medical Devices.

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Cardiovascular Week


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