Nitinol stent for hollow body conduits

• US 5,147,370 A
• Filed: 06/12/1991
• Issued: 09/15/1992
• Est. Priority Date: 06/12/1991
• Status: Expired due to Term

• Current Assignee: Gregory Mednik, Thomas O. Mcnamara
• Original Assignee: Gregory Mednik, Thomas O. Mcnamara
• Inventors: McNamara, Thomas O., Mednik, Gregory
• Primary Examiner(s): Pellegrino, Stephen C.
• Assistant Examiner(s): Dawson, Glenn K.
• Application Number:
  US07/713,770
• Time in Patent Office: 461 Days
• Field of Search: 604/96, 604/104, 604/281, 606/108, 606/194, 606/195, 606/198, 623/1
• US Class Current: 623/1.11
• 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 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 2210/0019 operated at only one temperature whilst inside or touching the human body, e.g. constrained in a non-operative shape during surgery, another temperature only occurring before the operation

Abstract

Disclosed is a coil stent constructed from a nitinol alloy having the ends thereof shaped to interact with a placement device specifically designed to hold the stent in a reduced diameter while it is being maniuplated to its desired position in the patient'"'"'s body. The placement device is a hollow tube which has holes in it surface allowing placement of the ends of the stent therethrough so that they can be held in place inside the interior of the placement device by a mandril which is threaded through the center of the placement device. The combination of the features of the shapes on the end of the stent, the holes in the placement device and the mandril which passes through the placement device and the shapes on the end of the stent allow the interventional radiologist to accurately and rapidly place the stent in its desired position before it changes shape to its final pre-set configuration.

Claims

1. A system for positioning in a hollow body organ an expendable stent having a first retention means formed on a first end of the stent and a second retention means formed on a second end of the stent comprising:

an elongated tube having a proximal end for placement into the hollow body organ, a distal end spaced from the proximal end, and a lumen extending through the tube from the proximal end to the distal end,

said elongated tube having a first and second hole in the surface thereof, said first and second holes being separated from each other along the length of the tube and being located between the distal end and the promixal end of the tube, the holes extending from the exterior of the tube into the lumen and being sized so that the first retention means formed on the stent can be inserted through the first hole into the lumen and the second retention means formed on the stent can be inserted through the second hole into the lumen,

a removable mandril extending through and enclosed within the lumen from at least the distal end to the proximal end of the tube, the mandril being sized to interlock with the first and second retention means on the stent which are positionable in the lumen of the tube.

2. The system of claim 1 wherein the outer diameter of the tube between the first and second hole is smaller than the outer diameter of the remainder of the tube.

3. The system of claim 1 wherein the lumen has a uniform diameter throughout the length of the catheter.

4. The system of claim 1 wherein the lumen has an enlarged diameter at the location of the first and second hole and a uniform but smaller diameter through the remainder of the length of the catheter.

5. A system for placing a support at a desired location in a tubular body organ comprising:

an elongated catheter having a proximal end for placement in the tubular body organ and a distal end spaced from the proximal end so that after placement of the proximal end in the tubular body organ at the desired location, the distal end extends out of the tubular body organ,

at least one lumen extending through the catheter from the proximal end to the distal end,

a first and second cut-out, each cut-out extending through the wall of the catheter into the lumen, the first cut-out being located near the proximal end of the catheter, the second cut-out being located distal to the first cut-out,

an expandable stent comprising a wire of a fixed length having first and second attachment means formed on the ends of the wire, the wire being spirally wound around the outer surface of the catheter with the first attachment means being placed through the first cut-out and the second attachment means being placed through the second cut-out,

an elongated removable mandril extending through the catheter lumen from the distal end at least past the first cut-out, the mandril retaining the first and second attachment means in the lumen in a releasable manner.

6. The system for placing a support of claim 5 wherein the wire is composed of a shape memory alloy which can be formed into a spiral conforming to the outer surface of the catheter at a first temperature and which reforms into a shape of dimensions different from the spiral by exposing the wire to a second temperature higher than the first temperature.

7. The system for placing a support of claim 6 wherein the shape memory alloy has a transition temperature range less than the normal temperature of the human body.

8. The system for placing a support of claim 7 wherein the alloy is nitinol.

9. A method of placing an internal support into a hollow structure utilizing a tubular placement device, the tubular placement device having a central lumen extending along its length comprising:

forming a fixed length wire of a shape memory alloy into a first shape sized to fit within and support the hollow structure, said wire having first and second retention means on the ends thereof,

cooling the wire to a temperature below the transition temperature range of the shape memory alloy,

placing the first retention means through a first opening in the wall of the tubular placement device,

securing the first retention means within the lumen of the tubular placement device by advancing an end of a mandril along a portion of the length of the lumen and through the first retention means,

wrapping the wire around the outer surface of the tubular placement device and placing the second retention means through a second opening in the wall of the tubular placement device into the lumen,

securing the second retention means in the lumen by advancing the end of the mandril further along the length of the tubular placement device through the second retention means and past the second opening,

advancing the tubular placement device with the wire wound on its outer surface into the hollow structure until the first retention means is at a desired location in the hollow structure,

releasing the second retention means by withdrawing the end of the mandril to a point between the first and second opening in the wall,

allowing the wire to at least partially reform to its first shape an amount sufficient to retain the wire within the hollow structure, said reformation being caused by exposing the wire to a temperature greater than the transition temperature range of the alloy,

releasing the first retention means by withdrawing the end of the mandril past the first opening, and

withdrawing the tubular placement device and mandril from the hollow structure.

10. The method of claim 9 wherein the hollow structure is a tubular organ in the human body and the tubular placement device is catheter sized to fit within the tubular organ.