Flexible microcatheter

• US 6,355,027 B1
• Filed: 06/09/1999
• Issued: 03/12/2002
• Est. Priority Date: 06/09/1999
• Status: Expired due to Term

• Current Assignee: Boston Scientific Limited (Boston Scientific Corporation)
• Original Assignee: Possis Medical, Inc. (Bayer AG)
• Inventors: Le, Hieu V., Dutcher, Robert G., Setum, Cindy M., Morris, John Edward
• Primary Examiner(s): Seidel, Richard K.
• Assistant Examiner(s): Maynard, Jennifer J
• Application Number:
  US09/328,761
• Time in Patent Office: 1,007 Days
• Field of Search: 604/523, 604/524, 604/525, 604/526, 604/527, 604/529, 604/533, 604/264, 604/265, 604/93.01, 604/48
• US Class Current: 604/525
• CPC Class Codes: A61M 2025/0042 Microcatheters, cannula or the like having outside diameters around 1 mm or less
• CPC Class Codes: A61M 25/005 with embedded materials for reinforcement, e.g. wires, coils, braids
• 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

Flexible microcatheter having regions of different flexibility integrally and strategically placed along and about the length of a one-piece composite catheter tube. Distally the flexible microcatheter exhibits pronounced flexibility with respect to locations or regions of flexibility located proximally for navigation along tortuous vascular paths. Different regions of flexibility are formed by applying resins of different Shore hardness readings either singularly or in combination along and about a braid which overlies an inner resin layer. The encapsulated braid provides resistance to kinking and bending of the flexible microcatheter as well as providing for torque transmission and pushability along the length of the flexible microcatheter.

Claims

1. A microcatheter comprising:

a. a one-piece tubing formed of a polyether and polyamide copolymer, or a fluoroplastic inner layer;

b. a braid of stainless steel wires over the inner layer to provide kink resistance or minimization of ovalization with bending and to increase torque transfer; and

,

c. an outer layer made up of a mixture of a polyamide base material, a polyether and polyamide base material, a polyurethane base material, one material having a 70-80 D Shore hardness value and the other material having a 25-35 D Shore hardness value; and

wherein the amounts of the materials of said mixture forming said outer layer continuously vary along the length of said outer layer such that the hardness of said outer layer at a first point along the length of said outer layer is different than at any other point along the length of said outer layer, thereby attaining continuously variable stiffness of the microcatheter along its entire length.

2. A microcatheter comprising:

a. a one-piece tubing formed of a polyether and polyamide copolymer, or a fluoroplastic inner layer;

b. a braid of stainless steel wires over the inner layer to provide kink resistance or minimization of ovalization with bending and to increase torque transfer; and

,

c. a continuously variable outer layer made up of a mixture or blend of a polyamide base material, a polyether and polyamide base material, or a polyurethane base material, one material having a 70-80 D Shore hardness value and the other material having a 25-35 D Shore hardness value, whereby the outer layer is continuously variable in flexibility and hardness over its length and has a distal end of said catheter of 25-35 D Shore hardness value, a transition region of the catheter increasing from 25-80 D Shore hardness value, and a proximal end is the catheter is 70-80 D Shore hardness value and wherein the amounts of the materials of said mixture forming said outer layer continuously vary along the length of said outer layer such that the hardness of said outer layer at a first point along the length of said outer layer is different than at any other point along the length of said outer layer, thereby attaining continuously variable stiffness of the microcatheter along its entire length.

3. The microcatheter of claim 2, wherein said continuously variable outer layer is produced by extrusion with a mixture or blend of the two materials of different hardness values being varied during the extrusion process, thereby attaining variable stiffness of the tubing along the length.

4. A microcatheter comprising:

a. a first section, a second section, and a third section, each of said sections including, in order, a continuous inner layer of constant composition extending through the first, second and third sections, a continuous braid extending through the first second and third sections, and a continuous outer layer made of a mixture two materials of different durometers and extending through the first, second and third sections;

b. said outer layer in said first section being about 100% soft durometer material;

c. said outer layer in said second section being continuously variable in durometer from about 100% soft to about 100% hard durometer material; and

,

d. said outer layer in said third section being about 100% hard durometer material and wherein the amounts of the two materials of said mixture forming said outer layer continuously vary along the length of said outer layer such that the hardness of said outer layer at a first point along the length of said outer layer is different than at any other point along the length of said outer layer, thereby attaining continuously variable stiffness of the microcatheter along its entire length.

5. A catheter comprising:

a. an elongated tubular means, with a first end and a second end, for passing material from said first end to said second end, said elongated tubular means including a single contiguous extrusion;

b. said single contiguous extrusion including at least two polymeric materials of differing elastic modulus, said polymeric materials being capable of processing to form a mixture with variable proportions of each polymeric material;

c. said polymeric materials being disposed along the length of said elongated tubular means to form a wall structure of said elongated tubular means;

d. said polymeric materials being combined as a mixture, with proportions varying along the length of said wall structure;

e. said varying proportions of said polymeric materials forming said wall structure and providing said wall structure with varying stiffness due to the variation in proportions of said polymeric materials of differing elastic modulus; and

,

f. said wall structure of varying stiffness providing said elongated tubular means with at least one region of relatively greater bending stiffness and at least one region of relatively lesser bending stiffness disposed at different distances relative to said first end and said second end along the length of said elongated tubular means;

and wherein the amounts of the two polymeric materials of said mixture forming said wall structure continuously vary along the length of said wall structure such that the hardness of said wall structure at a first point along the length of said wall structure is different than at any other point along the length of said wall structure, thereby attaining continuously variable stiffness of the catheter along its entire length.

6. The catheter of claim 5, further comprising:

a. a tubular polymeric inner layer;

b. a tubular middle layer comprising stiffening filament, disposed radially outside of and concentric with said inner layer;

c. said varying stiffness wall structure being disposed radially outside of and concentric with said middle layer; and

,

d. a hub disposed at said first end of said elongated tubular means, said hub providing for connection of said elongated tubular means to other devices and thereby providing for passage of material between the other devices and said elongated tubular means.

7. The catheter of claim 6, and further comprising a short atraumatic tip disposed at said second end of said elongated tubular means.

8. The catheter of claim 6, and further comprising a radio-opaque marking means.

9. The catheter of claim 5, wherein said elongated tubular means has a uniform inner diameter and a uniform outer diameter along its length between said first end and said second end.

10. The catheter of claim 5 comprising a region located between said first end and said second end of said elongated tubular means wherein said wall structure of varying stiffness has a gradual and continuous variation in stiffness along the length thereof, said gradual and continuous variation in stiffness being provided by a gradual and continuous variation in proportions of said polymeric materials.

11. The catheter of claim 5, wherein:

a. said wall structure of varying stiffness comprises an outer layer of said elongated tubular means;

b. a tubular braided metallic middle layer is disposed concentric with and radially inside and adjacent to said outer layer; and

,

c. a tubular polymeric inner layer is disposed concentric with and radially inside and adjacent to said outer layer.