U.S. patent application number 17/474796 was filed with the patent office on 2021-12-30 for layered tube for improved kink resistance.
The applicant listed for this patent is BIOSENSE WEBSTER (ISRAEL) LTD.. Invention is credited to Christopher Thomas BEECKLER.
Application Number | 20210402140 17/474796 |
Document ID | / |
Family ID | 1000005839636 |
Filed Date | 2021-12-30 |
United States Patent
Application |
20210402140 |
Kind Code |
A1 |
BEECKLER; Christopher
Thomas |
December 30, 2021 |
Layered Tube for Improved Kink Resistance
Abstract
A catheter shaft is produced by forming a first polymeric layer
onto a flexible inner core while maintaining the inner core in a
solid state, and solidifying the first polymeric layer, wherein the
solidified first polymeric layer fails to bond with the inner core
and is slidable thereon upon flexion of the shaft. A second
polymeric layer may be formed over the first polymeric layer, and
is slidable thereon when the shaft bends.
Inventors: |
BEECKLER; Christopher Thomas;
(Brea, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BIOSENSE WEBSTER (ISRAEL) LTD. |
YOKNEAM |
|
IL |
|
|
Family ID: |
1000005839636 |
Appl. No.: |
17/474796 |
Filed: |
September 14, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15386461 |
Dec 21, 2016 |
11123519 |
|
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17474796 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 48/08 20190201;
B29K 2077/00 20130101; B29C 39/18 20130101; B29K 2079/08 20130101;
B29K 2023/0683 20130101; B29C 48/23 20190201; B29L 2031/7542
20130101; B29C 39/146 20130101; A61M 25/0009 20130101; B29C 48/09
20190201; B29C 48/154 20190201; A61M 25/0141 20130101; B29C 48/151
20190201; B29C 48/21 20190201; A61L 29/02 20130101; B29C 48/10
20190201; A61L 29/085 20130101; A61M 2025/0047 20130101; B29C 48/18
20190201; A61M 2025/0048 20130101; A61M 25/0045 20130101; A61M
25/005 20130101; A61L 2420/08 20130101 |
International
Class: |
A61M 25/00 20060101
A61M025/00; B29C 48/10 20060101 B29C048/10; B29C 48/151 20060101
B29C048/151; A61M 25/01 20060101 A61M025/01; B29C 48/154 20060101
B29C048/154; B29C 48/21 20060101 B29C048/21; B29C 48/23 20060101
B29C048/23; A61L 29/02 20060101 A61L029/02; A61L 29/08 20060101
A61L029/08; B29C 39/18 20060101 B29C039/18 |
Claims
1. A method of making a catheter shaft, comprising the steps of:
forming a first polymeric layer onto a flexible inner core while
maintaining the inner core in a solid state; and solidifying the
first polymeric layer, in which the solidified first polymeric
layer fails to bond with the inner core and is slidable thereon
upon flexion of the inner core.
2. The method according to claim 1, in which forming a first
polymeric layer is performed by extruding.
3. The method according to claim 1, in which forming a first
polymeric layer is performed by film casting.
4. The method according to claim 1, further comprising the steps
of: forming a second polymeric layer onto the solidified polymeric
first layer; and solidifying the second polymeric layer, in which
the solidified second polymeric layer fails to bond with the
solidified first polymeric layer and is slidable thereon upon
flexion of the inner core.
5. The method according to claim 4, in which forming a second
polymeric layer is performed by extruding.
6. The method according to claim 4, in which forming a second
polymeric layer is performed by film casting.
7. The method according to claim 4, in which a kinetic coefficient
of friction between the solidified first polymeric layer and the
solidified second polymeric layer does not exceed 0.5.
8. The method according to claim 4, in which the solidified first
polymeric layer and the solidified second polymeric layer are
composed of identical materials.
9. The method according to claim 8, in which the solidified first
polymeric layer and the solidified second polymeric layer are
composed of polyimide.
10. The method according to claim 4 in which the solidified first
polymeric layer and the solidified second polymeric layer are
composed of different materials.
11. The method according to claim 10, in which one of the
solidified first polymeric layer and the solidified second
polymeric layer is ultra-high-molecular-weight polyethylene and
another of the solidified first polymeric layer and the solidified
second polymeric layer is polyether block amide.
12. The method according to claim 1, in which the inner core
comprises a metallic braid.
Description
CROSS-REFERENCE TO CO-PENDING APPLICATION
[0001] The present application is a Divisional Application under 35
U.S.C. .sctn. 121 of U.S. patent application Ser. No. 15/386,461,
filed Dec. 21, 2016. The entire content of this application is
incorporated by reference herein in its entirety.
COPYRIGHT NOTICE
[0002] A portion of the disclosure of this patent document contains
material that is subject to copyright protection. The copyright
owner has no objection to the facsimile reproduction by anyone of
the patent document or the patent disclosure, as it appears in the
Patent and Trademark Office patent file or records, but otherwise
reserves all copyright rights whatsoever.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0003] This invention relates to instruments for performing medical
examinations of the interior of cavities or tubes of the body. More
particularly, this invention relates to a medical catheter
constructed by a process for applying fluent materials to a surface
or part of a surface.
2. Description of the Related Art
[0004] It is common to map and ablate endocardial tissue in
subjects having electrical conduction abnormalities. The procedures
are performed with an elongate catheter having a lumen extending
longitudinally through it. One technique, described in U.S. Pat.
No. 5,993,462, involves inserting a core wire into a catheter via
the lumen. The core wire includes a pre-shaped region. Such
catheters includes a proximal section that is sufficiently rigid to
straighten the core wire when the core wire is disposed within the
proximal section. A distal section of the catheter is significantly
more flexible than the proximal section.
[0005] Deflectable catheters are widely used for a variety of
applications. In the area of electrophysiology. However, due to
their inherent flexibility and limited kink resistance, catheters
can be difficult to control as precisely as would be desired.
Conventional approaches to increasing kink resistance include:
increasing wall thickness, reinforcing the wall with a coil,
replacing a large open lumen with a multi-lumen arrangement, or
changing the material so that it can stretch and bend more
easily.
SUMMARY OF THE INVENTION
[0006] According to disclosed embodiments of the invention, a
catheter shaft is constructed using multiple film-cast, extruded or
coextruded layers of materials that do not chemically bond
together. The layers are in extremely good mechanical contact, but
when the construction is bent, they are able to slip with respect
to each other, which makes the tube more resistant to kinking.
[0007] There is provided according to embodiments of the invention
a method of making a catheter shaft, which is carried out by
forming a first polymeric layer onto a flexible inner core while
maintaining the inner core in a solid state, and solidifying the
first polymeric layer, wherein the solidified first polymeric layer
fails to bond with the inner core and is slidable thereon upon
flexion of the inner core.
[0008] According to one aspect of the invention wherein forming the
first polymeric layer is extruded.
[0009] According to yet another aspect of the method, the first
polymeric layer is film cast.
[0010] A further aspect of the method is carried out by forming a
second polymeric layer onto the solidified polymeric first layer,
and solidifying the second polymeric layer, wherein the solidified
second polymeric layer fails to bond with the solidified first
polymeric layer and is slidable thereon upon flexion of the inner
core.
[0011] According to an additional aspect of the method, the second
polymeric layer is extruded.
[0012] According to still another aspect of the method, the second
polymeric is film cast.
[0013] According to yet another aspect of the method, a kinetic
coefficient of friction between the solidified first polymeric
layer and the solidified second polymeric layer does not exceed
0.5.
[0014] According to still another aspect of the method the
solidified first polymeric layer and the solidified second
polymeric layer are composed of identical materials.
[0015] According to an additional aspect of the method, the
solidified first polymeric layer and the solidified second
polymeric layer are composed of polyimide.
[0016] According to a further aspect of the method the solidified
first polymeric layer and the solidified second polymeric layer are
composed of different materials.
[0017] According to another aspect of the method, one of the
solidified first polymeric layer and the solidified second
polymeric layer is ultra-high-molecular-weight polyethylene and
another of the solidified first polymeric layer and the solidified
second polymeric layer is polyether block amide.
[0018] According to one aspect of the method, the inner core
includes a metallic braid.
[0019] There is further provided according to embodiments of the
invention a catheter shaft having a flexible inner core, a first
polymeric layer formed onto the flexible inner core, and a second
polymeric layer onto the first polymeric layer, wherein upon
flexion of the flexible inner core the first polymeric layer is
slidable on the flexible inner core and on the second polymeric
layer.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0020] For a better understanding of the present invention,
reference is made to the detailed description of the invention, by
way of example, which is to be read in conjunction with the
following drawings, wherein like elements are given like reference
numerals, and wherein:
[0021] FIG. 1 is a schematic diagram of a medical catheter
according to an embodiment of the invention;
[0022] FIG. 2 is a cross sectional view of the shaft of the
catheter shown in FIG. 1 in accordance with an embodiment of the
invention; and
[0023] FIG. 3 is a group of two schematic longitudinal sections of
portions of the shaft of the catheter shown in FIG. 1 in accordance
with an embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0024] In the following description, numerous specific details are
set forth in order to provide a thorough understanding of the
various principles of the present invention. It will be apparent to
one skilled in the art, however, that not all these details are
necessarily needed for practicing the present invention. In this
instance, well-known circuits, control logic, and the details of
computer program instructions for conventional algorithms and
processes have not been shown in detail in order not to obscure the
general concepts unnecessarily.
[0025] Documents incorporated by reference herein are to be
considered an integral part of the application except that, to the
extent that any terms are defined in these incorporated documents
in a manner that conflicts with definitions made explicitly or
implicitly in the present specification, only the definitions in
the present specification should be considered.
[0026] Turning now to the drawings, reference is initially made to
FIG. 1, which is a schematic diagram of a medical catheter 10
according to an embodiment of the invention. The catheter 10
comprises an elongated shaft 12 having a relatively stiff proximal
section 14, relatively flexible distal section 16 with respect to
the proximal section 14 and an intermediate section 18. One or more
electrodes or other devices are mounted on the distal section 16
for performing mapping, ablation or another desired function, and a
control handle 20 is located at the proximal section 14 of the
shaft 12. An infusion tube 22 is provided to introduce fluid
through a lumen (not shown) of the shaft 12. A luer hub 24 is
mounted on the proximal end of the infusion tube 22 to facilitate
introduction of the fluid into the catheter 10.
[0027] Reference is now made to FIG. 2, which is a cross sectional
view of the shaft 12 (FIG. 1) in accordance with an embodiment of
the invention. The shaft is constructed by extrusion or coextrusion
of thermoplastic materials, as described in the detailed
description below. In the depicted embodiment, the shaft 12
includes lumens 26, 28, 30, 32 surrounded by a relatively soft
inner extrusion 34, which is drawn through a metallic braid 36.
While 4 lumens are shown, a catheter may comprise more or fewer
lumens, depending on the application intended.
[0028] The inner extrusion 34 and braid 36 are surrounded by a
series of layers. Respective outer, middle, and inner layers 38,
40, 42 are shown in the example of FIG. 2; however, the shaft 12
may be constructed with more or fewer layers. The layers may be
applied in successive extrusion operations using conventional screw
extruders, preferably having barrel cooling systems to obtain good
mixing efficiency and melt uniformity, and to avoid surge effects.
Dealing with these issues is well known in the extrusion art, and
is not dealt with further herein. Alternatively, the layers may be
coextruded with the inner extrusion 34.
[0029] It is important that the layers 38, 40, 42 and the inner
extrusion 34 do not bond to one another, although they are in close
physical proximity; indeed in "contact with one another. This
requirement enables the layers 38, 40, 42 and the inner extrusion
34 to slide upon one another when the shaft flexes. The layers 38,
40, 42 may be constructed of the same material, e.g., polyimide or
a thermoplastic such as polyethylene terephthalate (PET),
Pebax.RTM., Polyurethane," or Nylon.TM.. If a thermoplastic is
used, layers can be prevented from bonding to one another by
keeping each successive inner layer below the melt point of a
currently extruding outer layer. When identical materials are used
bonding can be avoided if the inner layer is cold and the outer
extrusion is put on with at a temperature that is barely high
enough for the material to flow. In that case as soon as the outer
extrusion touches the inner layer it cools immediately and does not
melt into the inner core and form a bond. When film casting is used
with polyimide, if the inner layer is solidified it does not make a
bond with the outer layer.
[0030] Alternatively, the shaft 12 may be built up by alternating
layers of different materials that do not bond to each other, for
example, ultra-high-molecular-weight polyethylene (UHMWPE) and a
polyether block amide, such as Pebax.
[0031] Regardless of the materials chosen, it is desirable that
there be a low kinetic coefficient of friction between adjacent
layers 38, 40, 42 and also between the layer 38 and the inner
extrusion 34. A coefficient of friction of 0.5 is satisfactory.
[0032] Reference is now made to FIG. 3, which is are schematic
longitudinal sections of portions of the shaft 12 in accordance
with an embodiment of the invention. In the upper portion of the
figure, the shaft 12 is extended. On one side of the shaft 12
marker 44 in the outer layer 38, marker 46 in middle layer 40 and
marker 48 in inner layer 42 are aligned with one another and with
reference marker 50 in the inner extrusion 34. On the opposite side
of the shaft 12, marker 52 in the outer layer 38, marker 54 in the
middle layer 40 and marker 56 in the inner layer 42 are also
aligned with reference marker 50.
[0033] In the lower portion of the figure the shaft 12 is in a
state of flexion at an angle of nearly 90 degrees about a pivot
point 58. The markers 44, 46, 48, and markers 52, 54, 56 are no
longer in alignment with one another nor with the reference marker
50, because the layers 38, 40, 42 have slid over one another and in
the case of inner layer 42, over the inner extrusion 34. At the
right side of the shaft 12 the markers 44, 46, 48 are now axially
displaced relative to the marker 50, generally toward the pivot
point 58 in a direction indicated by arrow 60. The marker 44 in the
outer layer 38 has the largest displacement from the reference
marker 50, with successively smaller displacements of the markers
46, 48. On the opposite side of the shaft 12, the markers 52, 54,
56 are also displaced relative to the marker 50, but in an opposite
direction, generally away from the pivot point 58 as indicated by
arrow 62. Marker 52 in the outer layer 38 has the largest
displacement from the reference marker 50, with successively
smaller displacements of the markers 54, 56.
[0034] Of the three layers 38, 40, 42, the layer 38 is under the
most compression. The movement of the layers with respect to each
other has prevented the shaft 12 from kinking tightly despite the
flexion.
Alternate Embodiment
[0035] Continuing to refer to FIG. 2 and FIG. 3, in this embodiment
the layers 38, 40, 42 are formed on the inner extrusion 34, which
is now used as a mandrel by a process of polymer solution casting
or film casting, which is known in the art. The same materials used
in the first embodiment are suitable, as they possess desired
characteristics of lubricity and durometer. Moreover, the layers
can be prevented from bonding to one another by film casting an
outer layer onto a solidified inner layer.
[0036] It will be appreciated by persons skilled in the art that
the present invention is not limited to what has been particularly
shown and described hereinabove. Rather, the scope of the present
invention includes both combinations and sub-combinations of the
various features described hereinabove, as well as variations and
modifications thereof that are not in the prior art, which would
occur to persons skilled in the art upon reading the foregoing
description.
* * * * *