SELF-EXPANDING ENDOPROSTHESIS Russian patent published in 2004 - IPC

FIELD: medicine, in particular, stents. SUBSTANCE: the transparent endoprosthesis has a self-expanding, multiple-thread braiding framework, radially expansible to the preset nominal diameter, made of braided metal threads of shape-memorizing alloy. The framework is made for compression to a decreased diameter for introduction to the body canal. At a release the frame, irrespective of the ambient temperature, spontaneously takes the preset nominal diameter, which in essence corresponds to the diameter of the treated anatomic canal. The braided threads form with one another - when the braided framework has its nominal diameter - angle α between 30 and 95 degrees, and preferably between 50 and 90 degrees, the thread metal is selected from a group consisting of nickel-titanium and nickel-titanium-cobalt alloys with a weight content of nickel within 52 to 56%. The framework is subjected to heat treatment, as a result of which the metal of all threads is subjected to a complete and stable phase transition bringing it from the given rigidity to a higher rigidity at a temperature equal to or lower than the temperature of the organism, but higher than the ambient temperature. The invention concerns also the method for manufacture of the described endoprosthesis, which includes the following operations: a flexible shape-memorizing alloy is selected from a group consisting of nickel-titanium alloys and nickel-titanium-cobalt alloys with a weight content of nickel within 52 to 56%, threads are made of this alloy, these threads are braided around the mandrel so as to obtain a braiding with the nominal diameter corresponding in essence to the corresponding diameter of the treated anatomic canal, the treads form with one another angle α within 30 to 95 degrees, the sections of this braiding at this nominal diameter are subjected to heat treatment realizing a complete and stable phase transition causing a change of the braiding metal rigidity from the given rigidity to a higher rigidity at a temperature equal to or lower than the temperature of the organism, a coat is applied to a discretion onto the mentioned framework, sections of the braiding are cut to segments of the necessary length. EFFECT: enhanced flexibility of the endoprosthesis at its introduction, sufficiently high resistibility to the compressive force, better stability at the place of implantation, expanded range of diameters and possibility of implantation in anatomic canals of a large diameter. 8 cl, 3 dwg, 1 tbl