Wire braid-reinforced microcatheter

• US 20040153049A1
• Filed: 10/10/2003
• Published: 08/05/2004
• Est. Priority Date: 10/10/2002
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Micro Therapeutics, Inc. (Medtronic Plc)
• Inventors: Martel, Michael D., Hewitt, Todd J.
• Granted Patent: US 7,507,229 B2
• Time in Patent Office: Days
• US Class Current: 604/527
• CPC Class Codes: A61M 2025/0042 Microcatheters, cannula or the like having outside diameters around 1 mm or less
• CPC Class Codes: A61M 2025/0046 Coatings for improving slidability
• 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 25/0053 having a variable stiffness along the longitudinal axis, e.g. by varying the pitch of the coil or braid
• CPC Class Codes: A61M 25/0054 with regions for increasing flexibility

Abstract

This invention is directed to a multi-layer catheter for navigation to remote locations within the body, comprising a liner layer, a braid layer and an outer jacket. The catheter provides a high degree of flexibility needed to traverse the vasculature and a high degree of strength needed to withstand the high pressures associated with catheter-delivery of viscous embolizing compositions.

Claims

1. A braid-reinforced microcatheter comprising:

a) a cylindrical inner layer of polymer having a proximal end and a distal end and a flexibility at its distal end greater than at its proximal end;

b) a braided wire layer over the inner layer, the braided wire layer including a distal segment of a first pic rate and a proximal segment of a second pic rate which is smaller than the first pic rate, the braided wire layer extending from the proximal end to within about 1 cm of the distal end of the catheter; and

c) an outer jacket surrounding the braided wire having a proximal durometer higher than a distal durometer.

26. A kit of parts comprising the catheter of claim 1 or claim 2 or claim 3 in combination with a premeasured amount of a liquid embolizing composition having a viscosity greater than 150 cSt at 40°

C.

2. A braid-reinforced microcatheter comprising:

a) an inner layer of a lubricious polymer and having an overlayer of strengthening polymer, wherein the strengthening polymer tapers to zero at the distal end of the inner layer;

b) a braided wire layer over the inner layer, the braided wire layer including a distal segment of a first pic rate and a proximal segment of a second pic rate which is smaller than the first pic rate; and

c) an outer jacket surrounding the braided wire having a proximal durometer higher than its distal durometer.

3. A high pressure-tolerant, high flexibility microcatheter having a distal end for delivery into a patient and a proximal end, the catheter comprising in combination:

a) a continuous cylindrical low friction liner extending from the distal end to the proximal end, said liner being highly flexible and having an interior diameter of from about 0.008 to 0.035 inches (0.25 to 0.75 mm);

b) a polyimide overliner covering about the proximal end half of the low friction liner, the overliner strengthening the about half of the low friction liner it covers relative to the uncovered half;

c) a wire braid reinforcing layer surrounding the overliner and a substantial portion of the distal about half of the low friction liner not covered by the overliner;

the wire braid reinforcing layer varying in pic rate, and thus flexibility, with a relatively low pic rate, low flexibility, proximal end covering the proximal about ⅔

of the cylindrical low friction liner and increasing in pic rate and flexibility moving proximal to distal along its length and terminating near but not completely at the distal end of the low friction liner; and

d) a polymer jacket extending continuously over the length of the wire braid reinforcing layer, the jacket varying in flexibility from a least flexible first section corresponding to and covering the proximal about half of the length of the low friction liner and joined thereto a plurality of shorter sections of serially increasing flexibility extending from the first section over the remainder of the length of the braided wire reinforcing layer.

4. The microcatheter of claim 3 wherein the wire braid comprises Nitinol.

5. The microcatheter of claim 3 wherein the wire braid comprises stainless steel.

6. The microcatheter of claim 3 wherein the wire braid consists essentially of Nitinol.

7. The microcatheter of claim 3 or 4 or 6 wherein the wire braid contains about 8 wires.

8. The microcatheter of claim 3 or 4 or 6 wherein the wire in the braid is elliptical in cross section.

9. The microcatheter of claim 3 or 4 or 6 wherein the pic rate of the wire braid in its least flexible portion is less than ¼

the pic rate of its most flexible portion.

10. The microcatheter of claim 3 wherein the pic rate of the wire braid changes continuously.

11. The microcatheter of claim 3 wherein the pic rate of the wire braid changes stepwise.

12. The microcatheter of claim 11 wherein the pic rate changes in at least 3 steps.

13. The microcatheter of claim 11 wherein the pic rate changes in 4 steps.

14. The microcatheter of claim 3 wherein the low friction liner is a fluorocarbon.

15. The microcatheter of claim 14 wherein the fluorocarbon liner consist essentially of PTFE.

16. The microcatheter of claim 3 wherein the polyimide overlayer is tapered in cross-section at the boundary of its covering the low friction liner.

17. The microcatheter of claim 3 wherein the polymer jacket comprises polyamide/nylon at its proximal end.

18. The microcatheter of claim 3 or 16 wherein the polymer jacket comprises polyether-polyamide block copolymer at its distal end.

19. The microcatheter of claim 3 wherein the polymer jacket comprises at least one segment of polyamide/nylon and at least two segments of polyether-polyamide block copolymer.

20. The microcatheter of claim 3 wherein the most flexible segments of the polymer jacket have a durometer of about 35 or less.

21. The microcatheter of claim 3 wherein the most flexible segments of the polymer jacket have a durometer of about 35.

22. The microcatheter of claim 3 wherein the most flexible segments of the polymer jacket have a durometer of about 25.

25. The method of claims 21 or 22 additionally comprising:

f) overcoating the distal end of the outer jacket with a lubricious polymer coating.

23. A method for constructing a high pressure-tolerant, high flexibility catheter comprising the steps of:

a) placing a lubricous inner liner having an inner surface defining the inside of the catheter, said liner having a proximal end and a distal end and being more flexible at its distal end than at its proximal end on a mandrel;

b) placing a wire braid reinforcement over the inner liner on the mandrel, the wire braid having a variable weave with a higher pic rate at its distal end than at its proximal end, thereby imparting greater flexibility to its distal end that to its proximal end;

c) forming a multisegmented cylindrical outer jacket by placing together a plurality of sections of cylindrical polymer of varying flexibility, the segments being ordered such that the least flexible sections are at the proximal end of the jacket and the most flexible sections are at the distal end.

d) placing the outer jacket over the wire braid reinforcement; and

e) shrinking the outer jacket over the wire braid and fusing the outer jacket segments into a continuous jacket.

24. A method for constructing a high pressure-tolerant, high flexibility catheter comprising the steps of:

a) placing a lubricous inner liner having an inner surface defining the inside of the catheter, said liner having a proximal end and a distal end and being more flexible at its distal end than at its proximal end on a mandrel;

b) placing a wire braid reinforcement over the inner liner on the mandrel, the wire braid having a variable weave with a higher pic rate at its distal end than at its proximal end, thereby imparting greater flexibility to its distal end that to its proximal end;

c) forming a multisegmented cylindrical outer jacket by joining together a plurality of sections of cylindrical polymer of varying flexibility, the segments being ordered such that the least flexible sections are at the proximal end of the jacket and the most flexible sections are at the distal end.

d) placing the outer jacket over the wire braid reinforcement; and

e) shrinking the outer jacket over the wire braid and fusing the outer jacket segments into a continuous jacket.