Method of making a kink-resistant catheter

• US 6,702,972 B1
• Filed: 08/23/2000
• Issued: 03/09/2004
• Est. Priority Date: 06/09/1998
• Status: Expired due to Term

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Diametrics Medical Limited (Allegro Biodiesel Corp.)
• Inventors: Markle, David Reed
• Primary Examiner(s): Lee, Edmund H.
• Application Number:
  US09/643,761
• Time in Patent Office: 1,294 Days
• Field of Search: 604/526, 264/130, 264/135, 264/255, 264/275, 264/230, 264/313, 264/334
• US Class Current: 264/230
• CPC Class Codes: A61M 25/0012 with embedded structures, e.g. coils, braids, meshes, strands or radiopaque coils
• CPC Class Codes: A61M 25/0045 multi-layered, e.g. coated coating materials A61L29/08
• CPC Class Codes: A61M 25/005 with embedded materials for reinforcement, e.g. wires, coils, braids
• CPC Class Codes: F16L 11/081 comprising one or more layers of a helically wound cord or wire in combination with braided layers F16L11/088
• CPC Class Codes: F16L 9/18 Double-walled pipes; Multi-channel pipes or pipe assemblies

Abstract

A catheter which has resistance to collapsing when bent, and a method for producing such a catheter. The method includes (i) supporting a helical metallic coil having turns on a mandrel which has a release surface comprising a polytetrafluoroethylene (PTFE) or fluorinated ethylene propylene copolymer (FEP) tube supported on the mandrel; (ii) introducing the helical coil while supported on the mandrel into a first tube, the first tube being formed from a material which is flowable at a first elevated temperature and said first tube being received within a second tube, the second tube being heat shrinkable at a second temperature which is equal to or greater than the first temperature; (iii) heating the resulting assembly to a temperature equal to or greater than the second temperature, whereby shrinkage of the second tube causes material of the first tube to flow between turns of the coil and substantially encapsulate the coil; (iv) removing the mandrel while leaving the sheathing tube within the coil; and (v) removing the sheathing tube by tensioning the tube longitudinally of the coil. Catheters having small internal bores and very thin walls are prepared by this method. The catheter includes a first, thermo-flowed tube having a helical coil at least partially enveloped in the material of the tube. A second tube surrounds the first tube and is formed from heat shrunk material.

Claims

1. A method of making a kink-resistant catheter;

the method comprising forming an assembly by;

(a) supporting a helical metallic coil having a plurality of turns on a mandrel;

(i) the mandrel supporting a sheathing tube comprising polytetrafluoroethylene (PTFE) or fluorinated ethylene propylene copolymer (FEP);

(b) introducing the helical coil while supported on the mandrel into a first tube;

(i) the first tube being formed from a material which is flowable at a first temperature; and

(ii) the first tube being received within a second tube to form an assembly;

(A) the second tube being heat shrinkable at a second temperature which is equal to or greater than the first temperature;

(c) heating the assembly to a temperature equal to or greater than the second temperature to cause shrinkage of the second tube;

(i) the shrinkage of the second tube causing material of the first tube to flow between turns of the helical coil and substantially encapsulate the helical coil;

(d) removing the mandrel from at least the first tube and the helical coil while leaving the sheathing tube within the helical coil; and

(e) longitudinally tensioning the sheathing tube to remove the sheathing tube from at least the first tube and the helical coil.

2. A method as claimed in claim 1 wherein:

(a) the sheathing tube is longer than the helical coil, the first tube, and the second tube; and

(b) the sheathing tube extends beyond one or both ends of the helical coil, the first tube, and the second tube; and

(c) the step of removing the sheathing tube includes pulling on one or both ends of the sheathing tube.

3. A method as claimed in claim 2 wherein:

(a) the helical coil is shorter than the first tube and is positioned on the mandrel so that the first tube extends beyond one or both ends of the helical coil; and

(b) the step of heating the assembly causes an inwardly tapered tip to be formed at one or both ends of the helical coil.

4. A method as claimed in claim 1 further including:

(a) after the step of heating, removing the second tube from the first tube and the helical coil.

5. A method as claimed in claim 4 wherein:

(a) the step of removing the second tube includes slitting the second tube.

6. A method as claimed in claim 1 wherein:

(a) the first tube is heat flowable at a first temperature in the range of 100 to 300°

C.; and

(b) the second tube is heat shrinkable at a second temperature greater than the first temperature and in the range of 150 to 350°

C.