Urological stent therapy system and method

• US 20020151967A1
• Filed: 02/28/2002
• Published: 10/17/2002
• Est. Priority Date: 04/09/1996
• Status: Active Grant

• Current Assignee: Endocare Inc. (Siemens AG)
• Original Assignee: Endocare Inc. (Siemens AG)
• Inventors: Moseley, William G., Eum, Jay J., Mikus, Paul W.
• Granted Patent: US 6,702,846 B2
• Time in Patent Office: Days
• US Class Current: 623/1.22
• CPC Class Codes: A61F 2/88 the wire-like elements formed as helical or spiral coils forming a net-like or mesh-like structure A61F2/90
• CPC Class Codes: A61F 2/95 Instruments specially adapted for placement or removal of stents or stent-grafts
• CPC Class Codes: A61F 2/9517 handle assemblies therefor
• CPC Class Codes: A61F 2002/048 Ureters
• CPC Class Codes: A61F 2002/9505 having retaining means other than an outer sleeve, e.g. male-female connector between stent and instrument
• CPC Class Codes: A61F 2002/9511 the retaining means being filaments or wires
• CPC Class Codes: A61F 2250/0039 differing in diameter
• CPC Class Codes: A61M 27/008 pre-shaped, for use in the urethral or ureteral tract

Abstract

A stent system and method for use in the prostate gland. The stent is made of a shape memory alloy such as nitinol, and has a low temperature martensite state, with a martensite transition temperature below body temperature, and a high temperature austenite state, with an austenite transition temperature at or above body temperature, and a memorized shape in the high temperature austenite state which is a helical coil of diameter large enough to hold the prostatic urethra open. The stent is used to heat the prostate and is left in the prostatic urethra while the prostate heals. After the prostate is substantially healed, the stent is cooled to its martensite state and is easily removed from the urethra.

Claims

1. A stent for use within the prostatic urethra, said stent comprising:

a length of wire having a substantially helical configuration and being expandable between a collapsed shape and an expanded shape, said expanded shape including a proximal end and a distal end and a substantially cylindrical portion extending from the distal end toward the proximal end, and an enlarged region proximal of the cylindrical portion wherein an outer diameter of the enlarged region progressively increases toward the proximal end.

2. The stent of claim 1, wherein the wire is flat.

3. The stent of claim 1, wherein the diameter of the stent in its cylindrical portion is less than about 1 cm.

4. The stent of claim 1, wherein the diameter of the stent in its cylindrical portion is about 0.6 to about 1 cm.

5. The stent of claim 1, wherein the diameter of the stent at its proximal end is about 25% or more larger than the diameter of the stent in its cylindrical portion.

6. The stent of claim 1, wherein the diameter of the stent at its proximal end is about 50% or more larger than the diameter of the stent in its cylindrical portion.

7. The stent of claim 1, wherein the diameter of the stent at its proximal end is about 75% or more larger than the diameter of the stent in its cylindrical portion.

8. The stent of claim 1, wherein the stent is enlarged only at its proximal end.

9. The stent of claim 1, wherein the wire is made of a shape memory material.

10. The stent of claim 9, wherein the wire is superelastic.

11. The stent of claim 9, wherein the wire is made of nitinol.

12. The stent of claim 1, wherein the expanded shape corresponds to a high temperature austenite state and the collapsed shape corresponds to a low temperature martensite state.

13. The stent of claim 12, wherein the high temperature austenite state is achieved upon heating to a temperature range of about 38-60°

C., and the low temperature martensite state is achieved upon cooling to the temperature range of about 30-35°

C.

15. The method of claim 14, wherein the wire is flat.

16. The method of claim 14, wherein the diameter of the stent in its cylindrical portion is less than about 1 cm.

17. The method of claim 14, wherein the diameter of the stent in its cylindrical portion is about 0.6 to about 1 cm.

18. The method of claim 14, wherein the diameter of the stent at its proximal end is about 25% or more larger than the diameter of the stent in its cylindrical portion.

19. The method of claim 14, wherein the diameter of the stent at its proximal end is about 50% or more larger than the diameter of the stent in its cylindrical portion.

20. The method of claim 14, wherein the diameter of the stent at its proximal end is about 75% or more larger than the diameter of the stent in its cylindrical portion.

21. The method of claim 14, stent of claim 1, wherein the wire is made of a shape memory material.

22. The method of claim 21, wherein the expanded shape corresponds to a high temperature austenite state and the collapsed shape corresponds to a low temperature martensite state.

23. The method of claim 22, wherein the stent is collapsed in its low temperature martensite state.

24. The method of claim 22, wherein the stent is expanded in its high temperature austenite state.

14. A method for delivering a stent into the prostatic urethra of a patient, the method comprising:

providing a length of wire having a substantially helical configuration and being expandable between a collapsed shape and an expanded shape, said expanded shape including a proximal end and a distal end and a substantially cylindrical portion extending from the distal end toward the proximal end, and an enlarged region proximal of the cylindrical portion wherein an outer diameter of the enlarged region progressively increases toward the proximal end;

delivering the stent in its collapsed shape into the prostatic urethra of the patient; and

expanding the stent to its expanded shape within the prostatic urethra of the patient, wherein the proximal end of the stent is located relatively closer to the external sphincter and the distal end of the stent is located relatively closer to the bladder neck sphincter.