A catheter 1 suitable for advancement through a body passageway of a patient. The catheter 1 comprises a catheter body 4 which is flexible to provide the necessary trackability for the catheter 1 to advance through a body passageway, and two stainless steel reinforcement wires 5 extending along the catheter body 4 which provide the necessary pushability to advance the catheter 1 through the passageway. The reinforcements 5 are positioned diametrically opposed to one another by approximately 180 degrees on opposite sides of the longitudinal axis of the catheter 1, and the catheter body 4 is relatively soft and twistable. This configuration enables the entire catheter 1 to spontaneously twist during advancement so that the reinforcements 5 orientate themselves along a plane of neutral bending during advancement of the catheter 1. In this way, any resistance to the trackability of the catheter 1 due to the stiff reinforcements 5 is minimized.
1. A catheter for advancement through a body passageway, the catheter comprising:
a flexible catheter body; and
two reinforcements extending at least partially along the catheter body;
the two reinforcements being located on opposite sides of the longitudinal axis of the catheter, and
the product (EI max ) R of the Young's modulus and the maximum second moment of area of the reinforcement is greater than the product (EI) m of the Young's modulus and the second moment of area of the catheter body material.
2. A catheter as claimed in claim 1 wherein (EI max ) R is at least 2 times greater than (EI) m .
3. A catheter as claimed in claim 1 wherein (EI max ) R is at least 4 times greater than (EI) m .
4. A catheter as claimed in claim 1 wherein (EI max ) R is at least 6 times greater than (EI) m .
5. A catheter as claimed in claim 1 wherein (EI max ) R is at least 8 times greater than (EI) m .
6. A catheter as claimed in claim 1 wherein (EI max ) R is at least 10 times greater than (EI) m .
7. A catheter as claimed in claim 1 wherein the product (EI) m of the Young's modulus and the second moment of area of the catheter body material is greater than the product (EI min ) R of the Young's modulus and the minimum second moment of area of the reinforcement.
8. A catheter as claimed in claim 7 wherein (EI) m is at least 10 times greater than (EI min ) R .
9. A catheter as claimed in claim 7 wherein (EI) m is at least 50 times greater than (EI min ) R .
10. A catheter as claimed in claim 7 wherein (EI) m is at least 100 times greater than (EI min ) R .
11. A catheter as claimed in claim 7 wherein (EI) m is at least 200 times greater than (EI min ) R .
12. A catheter as claimed in claim 1 wherein the Young's modulus of the reinforcement E R is substantially greater than the Young's modulus of the catheter body material E m .
13. A catheter as claimed in claim 12 wherein E R is at least 20 times greater than E m .
14. A catheter as claimed in claim 12 wherein E R is at least 100 times greater than E m .
15. A catheter as claimed in claim 12 wherein E R is at least 1,000 times greater than E m .
16. A catheter as claimed in claim 1 wherein a first radial line which passes through the longitudinal axis of the catheter and one reinforcement subtends an angle in the range of from 140 degrees to 180 degrees with a second radial line which passes through the longitudinal axis of the catheter and the other reinforcement.
17. A catheter as claimed in claim 16 wherein the first radial line subtends an angle in the range of from 160 degrees with the second radial line.
18. A catheter as claimed in claim 16 wherein the first radial line subtends an angle of approximately 180 degrees with the second radial line.
19. A catheter as claimed in claim 1 wherein the reinforcement is fixed relative to the catheter body.
20. A catheter as claimed in claim 19 wherein the reinforcement is at least partially embedded in the catheter body.
21. A catheter as claimed in claim 20 wherein the catheter body is oversized around the reinforcement.
22. A catheter as claimed in claim 1 wherein the reinforcement is provided at least partially on an external surface of the catheter body.
23. A catheter as claimed in claim 1 wherein the reinforcement is provided at least partially on an internal surface of the catheter body.
24. A catheter as claimed in claim 1 wherein the catheter body is over-extruded over the reinforcements.
25. A catheter as claimed in claim 1 wherein the reinforcement is of stainless steel, or nitinol, or kevlar, or carbon fibre.
26. A catheter as claimed in claim 1 wherein the reinforcement comprises a wire.
27. A catheter as claimed in claim 1 wherein the reinforcement comprises a spring.
28. A catheter as claimed in claim 1 wherein the reinforcement comprises a section of hard polymeric material.
29. A catheter as claimed in claim 1 wherein the reinforcement comprises a cluster of one or more reinforcing elements.
30. A catheter as claimed in claim 29 wherein the reinforcing elements are interconnected.
31. A catheter as claimed in claim 29 wherein the reinforcing elements are braided together.
32. A catheter as claimed in claim 29 wherein the reinforcing element comprises a wire.
33. A catheter as claimed in claim 32 wherein the reinforcement comprises a cluster of two wires.
34. A catheter as claimed in claim 33 wherein the two wires are located at substantially the same radial distance from the longitudinal axis of the catheter.
35. A catheter as claimed in claim 33 wherein the two wires are radially aligned along a radial line which passes through the longitudinal axis of the catheter and both wires.
36. A catheter as claimed in claim 32 wherein the reinforcement comprises a cluster of four wires.
37. A catheter as claimed in claim 36 wherein the four wires are clustered into a square with each wire at a corner of the square.
38. A catheter as claimed in claim 37 wherein a diagonal of the square passes through the longitudinal axis of the catheter.
39. A catheter as claimed in claim 32 wherein the wire is of stainless steel, or nitinol, or kevlar, or carbon fibre.
40. A catheter as claimed in claim 29 wherein the reinforcing element comprises a spring.
41. A catheter as claimed in claim 29 wherein the reinforcing element comprises a section of hard polymeric material.
42. A catheter as claimed in claim 1 wherein one reinforcement is interconnected with the other reinforcement by a connecting arm.
43. A catheter as claimed in claim 42 wherein the connecting arm extends at least partially circumferentially around the catheter body.
44. A catheter as claimed in claim 42 wherein the connecting arm extends at least partially as a chord across the catheter body.
45. A catheter as claimed in claim 44 wherein the connecting arm is aligned along a line which passes through the two reinforcements.
46. A catheter as claimed in claim 42 wherein the connecting arm extends longitudinally along the catheter.
47. A catheter as claimed in claim 42 wherein the connecting arm is provided at least partially on an external surface of the catheter body.
48. A catheter as claimed in claim 42 wherein the connecting arm is provided at least partially on an internal surface of the catheter body.
49. A catheter as claimed in claim 42 wherein the connecting arm is at least partially embedded in the catheter body.
50. A catheter as claimed in claim 1 wherein the reinforcement has a generally rectangular cross-section.
51. A catheter as claimed in claim 50 wherein the reinforcement is aligned with the long side of the rectangle substantially parallel to a radial line which passes through the longitudinal axis of the catheter and the reinforcement.
52. A catheter as claimed in claim 50 wherein the reinforcement is aligned with the short side of the rectangle substantially parallel to a radial line which passes through the longitudinal axis of the catheter and the reinforcement.
53. A catheter as claimed in claim 1 wherein the reinforcement has a generally “I” shaped cross-section.
54. A catheter as claimed in claim 53 wherein the reinforcement is aligned with the end parts of the “I” substantially parallel to a radial line which passes through the longitudinal axis of the catheter and the reinforcement.
55. A catheter as claimed in claim 1 wherein the reinforcement has a generally round cross-section.
56. A catheter as claimed in claim 1 wherein the reinforcement has a generally annular cross-section.
57. A catheter as claimed in claim 1 wherein the cross-sectional area of the reinforcement is small relative to the cross-sectional area of the catheter body.
58. A catheter as claimed in claim 1 wherein the cross-sectional area of the reinforcement and/or of the catheter body varies along the length of the catheter.
59. A catheter as claimed in claim 1 wherein the mechanical properties of the reinforcement and/or of the catheter body varies along the length of the catheter.
60. A catheter as claimed in claim 1 wherein the catheter comprises a guide to facilitate ease of relative movement of the catheter.
61. A catheter as claimed in claim 60 wherein the guide is provided at least partially on an external surface of the catheter.
62. A catheter as claimed in claim 60 wherein the guide is provided at least partially on an internal surface of the catheter.
63. A catheter as claimed in claim 60 wherein the guide extends along the catheter.
64. A catheter as claimed in claim 60 wherein the guide extends at least partially circumferentially around the catheter.
65. A catheter as claimed in claim 60 wherein the guide comprises one or more protrusions on the catheter.
66. A catheter as claimed in claim 65 wherein the protrusion is provided at least partially by the reinforcement.
67. A catheter as claimed in claim 65 wherein the protrusion is provided at least partially by the catheter body.
68. A catheter as claimed in claim 65 wherein the protrusion is shaped for a smooth crossing profile.
69. A catheter as claimed in claim 60 wherein the guide comprises a sheath.
70. A catheter as claimed in claim 1 wherein the catheter comprises at least one reinforcement column extending along the catheter body.
71. A catheter as claimed in claim 70 wherein the column extends at least partially longitudinally along the catheter body.
72. A catheter as claimed in claim 70 wherein the column extends along the catheter body at least partially in a spiral.
73. A catheter as claimed in claim 70 wherein the column is at least partially embedded in the catheter body.
74. A catheter as claimed in claim 71 wherein the column is provided at least partially on an external surface of the catheter body.
75. A catheter as claimed in claim 70 wherein the column is provided at least partially on an internal surface of the catheter body.
76. A catheter as claimed in claim 1 wherein the catheter comprises means to centre the catheter during advancement through a body passageway.
77. A catheter as claimed in claim 77 wherein the centring means comprises a centring catheter for protruding distally of a distal end of the catheter.
78. A catheter as claimed in claim 77 wherein the centring catheter is retractable relative to the catheter.
79. A catheter as claimed in claim 77 wherein the centring catheter has a tip shaped for a smooth crossing profile.
80. A catheter as claimed in claim 79 wherein the tip is arrow-head shaped, or rounded, or ball-nose shaped.
81. A catheter as claimed in claim 1 wherein the catheter is configured to facilitate rapid exchange of the catheter over a guidewire.
82. A catheter as claimed in claim 81 wherein the catheter comprises a guidewire lumen extending partially through the catheter from a distal end of the catheter to a rapid exchange port.
83. A catheter as claimed in claim 82 wherein the reinforcements extend along the catheter body distally of the rapid exchange port.
84. A catheter as claimed in claim 1 wherein the catheter comprises a hydrophilic coating.
85. A catheter as claimed in claim 1 wherein the catheter is an intravascular catheter.
86. A catheter as claimed in claim 1 wherein the catheter is a retrieval catheter.
87. A catheter as claimed in claim 1 wherein the catheter is a delivery catheter.
88. A catheter for advancement through a body passageway, the catheter comprising:
a flexible catheter body; and
two reinforcements extending at least partially along the catheter body;
the two reinforcements being located on opposite sides of the longitudinal axis of the catheter,
the product (EI max ) R of the Young's modulus and the maximum second moment of area of the reinforcement is greater than the product (EI) m of the Young's modulus and the second moment of area of the catheter body material, and
(EI) m is greater than the product (EI min ) R of the Young's modulus and the minimum second moment of area of the reinforcement.
89. A catheter as claimed in claim 88 wherein the reinforcement has a generally rectangular cross-section.
90. A catheter as claimed in claim 89 wherein the reinforcement is aligned with the short side of the rectangle substantially parallel to a radial line which passes through the longitudinal axis of the catheter and the reinforcement.
91. A catheter for advancement through a body passageway, the catheter comprising:
a flexible catheter body; and
two reinforcements extending at least partially along the catheter body;
the two reinforcements being located on opposite sides of the longitudinal axis of the catheter,
the product (EI max ) R of the Young's modulus and the maximum second moment of area of the reinforcement is greater than the product (EI) m of the Young's modulus and the second moment of area of the catheter body material, and
the Young's modulus of the reinforcement E R is at least 20 times greater than the Young's modulus of the catheter body material E m .
92. A catheter as claimed in claim 91 wherein the reinforcement has a generally rectangular cross-section.
93. A catheter as claimed in claim 92 wherein the reinforcement is aligned with the short side of the rectangle substantially parallel to a radial line which passes through the longitudinal axis of the catheter and the reinforcement.