RU96121354A - UROLOGICAL STENT AND DEVICE FOR ITS DEPLOYMENT - Google Patents

Claims (9)

1. A stent adapted to be placed in the urethra in order to keep the diameter of the urethra above a critical value, containing a tape spiral made of a metal alloy with the effect of two-sided memory of a shape having two memory states, and in the first state, this alloy is soft and is capable of significantly deforming, and in the second state, the specified alloy has the properties of superelasticity and is essentially not able to deform, the alloy passes from the first about the state in the second at the first temperature of the phase transition, which is above the physiological temperature of the body, and goes from the second state to the first at the second temperature of the phase transition, which is below the physiological temperature of the body; in said second state, successive turns of the tape are adjacent to each other so as to together form a substantially continuous cylindrical tube whose diameter is above the specified critical value; in said first state, said tape forms a spiral structure having a maximum outer diameter of such a magnitude as to permit deployment of the stent in the urethra.  2. The stent according to claim 1, in which the turns of the stent in its first state at least partially overlap, so that the total length of the stent does not change during the transition from the first state to the second. 3. A stent according to claim 1 or 2, having a chemical composition represented by the following formula: Ni ₁ Ti _m A _n
where A-Ni, Co, Cr or V;
l, m, n - fractions of metal ions in
alloy, and the sum of l, m, n is 1; wherein l = 0.5; m = 0.5 - n; n is from 0.003 to 0.02. 4. The stent according to any one of paragraphs. 1-3, in which the transition from the first state to the second state takes place in the temperature range of 39-55 ^o C, and the transition between these two states takes place in the temperature range of 1-4 ^o C. 5. The stent according to any one of claims 1 to 4, in which the second transition temperature is in the temperature range of 20-32 ^o C.  6. A stent according to any one of the preceding claims 1 to 5, having a diameter in the first state of about 3-7 mm and a diameter in the second state of about 8-14 mm, said tape having a width of about 1.0-6.0 mm and a thickness of about 0.1-0.5 mm (approx. per.) in the original claims in English, probably approximately 0.5-0.5 mm are mistakenly written.  7. A device for deploying a stent in a predetermined portion of the urethra, comprising a catheter having a front end adapted to be inserted into the urethra and a rear end, and comprising at least one discharge tube and at least one tube for guiding fluid; moreover, the specified discharge tube is connected to a balloon that is able to increase in volume, which is located near the front end of the catheter and which is adapted to increase the volume while inside the bladder; the specified discharge tube is capable of being connected at its rear end to a source of liquid under pressure; the specified tube for directing the fluid, having holes in its rear part and at a distance from the specified cylinder, is capable of being connected at its rear end to a source of fluid; the specified part is adapted to hold on it a spiral stent; the part of the urethra where the specified stent is deployed is determined by the specified distance.  8. The device according to claim 7, wherein said first tube is held in said second tube, and there is a gap between the outer walls of said first tube and the inner walls of said second tube to allow fluid to pass through from the rear end of said second tube to the holes.  9. The device according to claim 7 or 8, in which the catheter contains a retractable nozzle adapted to cover the stent when the helix is on the indicated part before deployment.