Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent structure
Patent
1998-01-22
1999-12-28
Willse, David H.
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent structure
623 12, A61F 206
Patent
active
060075740
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates in general to medicine and more specifically to surgery and can find predominant application for endoreconstruction of blood vessels and other hollow organs and structures of human body. The invention also enables one to carry out reconstruction of perforating lesions.
BACKGROUND ART
Modern medicine is capable of reconstructing blood vessels, ducts, and perforating lesions of human organs, using special framework-type devices named stents. Use of stents makes it possible to restore the natural function of an defected anatomical structure without having recourse to direct operative interference techniques.
In order to function as an effective and reliable endoprostheses stents must possess a number of specific properties. First and foremost stents must provide unobstructed motion of body fluids through the implanted structure. Such stents must be very flexible and at the same time must be rigid enough to withstand the pressure exerted by walls of blood vessels or body cavities, with uniform pressure distribution over entire side of the stent. Moreover, the stent construction must be convenient for being transported to the zone of reconstruction and positioned there, as well as must not produce any injurious effect upon the surrounding tissues in the course of implantation and further functioning.
One state-of-the-art hollow tubular stent is known to have end portions and a surface formed by a plurality of intersecting elastic elements at least part of which are interconnected at the stent ends (U.S. Pat. No. 733,665).
The stent can be of two different diametrical dimensions due to radial deformation of its elastic elements. Before being positioned at the place of reconstruction the stent is deformed so as to minimise its diametrical dimension. Then the stent is placed, in the deformed state, inside a transporting means by arranging it on a special setting bulb. Once the stent has been transported to the place of reconstruction the setting bulb is expanded so that the stent diameter is expanded to its maximal value.
It is due to its rigid construction that the stent withstands rather high pressure of the walls of the organ being prosthesized and provides for a uniform distribution of the resultant stresses over the prosthesized surface.
However, the stent in question features but lower elasticity due to a restricted axial deformation, which affects the quality of endoprosthesizing.
Another prior-art stent is known to be in the form of a hollow tubular springlike body made of a material having a shape memory effect (SME). Stents made from such a material are capable of restoring their shape upon a change in the temperature conditions.
The advantages of said stent are determined by the properties of the material it is made from that provides for complete restoration of the stent shape in the zone of reconstruction, as well as a possibility of its convenient withdrawal from the organ being prosthesized upon cooling of the stent. The procedure of the stent positioning is improved, too.
A variety of stent embodiments are possible. In particular, the stent may have a construction disclosed in the aforediscussed invention (U.S. Pat. No. 733,665).
One more stent embodiment presents its construction as a hollow tubular element established by the coils of a wire or the turns of a strip. The construction of such a stent is more elastic since the stent is deformable both radially and axially.
However, with this stent it is not always possible to provide and optimum value of the pitch of spring coils or of strip turns because with too a large pitch a uniform pressure distribution over the surface being prosthesized is affected, which may result in partial vessel stenosis, whereas in the case of too a small pitch stent implantation may cause hyperplasia of the intima of the vascular wall in the organ under reconstruction, as well as early thrombotic complications.
Still more stent of the prior art is known to appear as a three-dimensional tubular structure established by a
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Karev Andrei Vladimirovich
Pulnev Sergei Appolonovich
Schukin Sergei Vladimirovich
Jackson Suzette J.
Willse David H.
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