U.S. patent application number 14/272068 was filed with the patent office on 2014-11-13 for guiding medical devices and associated methods of manufacturing.
This patent application is currently assigned to St. Jude Medical, Atrial Fibrillation Division, Inc.. The applicant listed for this patent is St. Jude Medical, Atrial Fibrillation Division, Inc.. Invention is credited to Gregory James Dakin, Jennifer Marie Heisel, Somally Mom.
Application Number | 20140336572 14/272068 |
Document ID | / |
Family ID | 50928285 |
Filed Date | 2014-11-13 |
United States Patent
Application |
20140336572 |
Kind Code |
A1 |
Heisel; Jennifer Marie ; et
al. |
November 13, 2014 |
Guiding Medical Devices and Associated Methods of Manufacturing
Abstract
A catheter assembly includes an inner liner made of flexible
material and an outer layer having a steering mechanism. A catheter
assembly is provided that includes an inner liner made of flexible
material, and an outer layer having a steering mechanism that
includes at least one wire and a corresponding lumen for each of
the at least one wire through which the respective wire may travel.
The outer layer includes a braided wire assembly that includes at
least two wires braided into a wire mesh, and further includes a
see-through portion positioned proximate a pull wire extraction
location to facilitate extraction.
Inventors: |
Heisel; Jennifer Marie;
(Princeton, MN) ; Dakin; Gregory James; (Edina,
MN) ; Mom; Somally; (Savage, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
St. Jude Medical, Atrial Fibrillation Division, Inc. |
St. Paul |
MN |
US |
|
|
Assignee: |
St. Jude Medical, Atrial
Fibrillation Division, Inc.
St. Paul
MN
|
Family ID: |
50928285 |
Appl. No.: |
14/272068 |
Filed: |
May 7, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61820545 |
May 7, 2013 |
|
|
|
Current U.S.
Class: |
604/95.04 ;
264/259 |
Current CPC
Class: |
A61L 29/06 20130101;
A61B 2018/00577 20130101; A61B 2018/00357 20130101; A61M 2210/125
20130101; B29C 41/08 20130101; B29K 2995/007 20130101; A61M 25/0108
20130101; B29K 2077/00 20130101; A61B 2218/002 20130101; A61M
25/0147 20130101; A61M 2025/015 20130101; B29L 2031/7542 20130101;
A61M 2025/0008 20130101; A61B 18/1492 20130101; A61M 2205/583
20130101; B29C 41/22 20130101; A61B 2090/3966 20160201; A61M
25/0012 20130101; A61M 25/0045 20130101; A61M 2025/0046 20130101;
A61M 25/0009 20130101; A61M 25/005 20130101; A61L 29/06 20130101;
C08L 77/12 20130101 |
Class at
Publication: |
604/95.04 ;
264/259 |
International
Class: |
A61M 25/00 20060101
A61M025/00; A61M 25/01 20060101 A61M025/01 |
Claims
1. A catheter assembly, comprising: an inner liner made of flexible
material; and an outer layer having a steering mechanism, the
steering mechanism comprising: at least one wire; and a
corresponding lumen for each of the at least one wire through which
the wire may travel; wherein the outer layer comprises a braided
wire assembly that includes at least two wires braided into a wire
mesh; and wherein the outer layer comprises a see-through portion
positioned proximate a pull wire extraction location to facilitate
extraction.
2. The catheter assembly of claim 1, wherein the braided wire
assembly is braided in a substantially consistent braid pattern
over its length.
3. The catheter assembly of claim 1, wherein the outer layer
comprises a plurality of segments of decreasing durometer from
proximal end to distal end.
4. The catheter assembly of claim 3, wherein a distal segment of
the plurality of segments is of a lower durometer PEBAX than a
proximal segment of the plurality of segments.
5. The catheter assembly of claim 4, wherein a distal segment of
the plurality of segments is of a higher durometer PEBAX than a
proximal segment of the plurality of segments.
6. A method of manufacturing a catheter, comprising the steps of:
providing a mandrel; placing a lining material over the mandrel to
form an inner liner; placing a thermoplastic elastomer layer over
the inner liner, at least along the mandrel at a location where one
or more pull wires will be extracted; providing at least one pull
wire; placing a flexible liner over each of the at least one pull
wires to create at least one lumen; placing a braided wire assembly
over the inner liner and the at least one lumen, the braided wire
assembly including at least two wires braided into a wire mesh;
providing pull wire access areas in the braided wire assembly;
covering the braided wire assembly with one or more melt processing
polymers having decreasing durometers from proximal to distal end
of the mandrel; covering a portion of the braided wire assembly
proximate the location where the one or more pull wires will be
extracted with a melt processing polymer that is substantially
see-through; applying sufficient heat to the one or more melt
processing polymers and the see-through melt processing polymer to
raise the temperature of the polymer above its melting point;
cooling the assembly; and removing the mandrel, thereby forming a
catheter.
7. The method of claim 6, wherein the braided wire assembly is
placed over the inner liner and the at least one lumen in a
consistent braid pattern.
8. A method of manufacturing a catheter, comprising the steps of:
providing a mandrel; placing a lining material over the mandrel to
form an inner liner; providing at least one wire; placing a
flexible liner over each of the at least one wires to create at
least one lumen; placing a braided wire assembly over the inner
liner and the at least one lumen, the braided wire assembly
including at least two wires braided into a wire mesh; covering the
braided wire assembly with one or more melt processing polymers
having a durometer at the proximal end that differs from the
durometer at the distal end of the mandrel; applying sufficient
heat to the melt processing polymers to raise the temperature of
the polymer above their melting point; cooling the assembly; and
removing the mandrel, thereby forming a catheter.
9. The method of claim 8, wherein the durometer at the distal end
is greater than the durometer at the proximal end.
10. The method of claim 8, wherein the durometer at the distal end
is less than the durometer at the proximal end.
11. The method of claim 8 further comprising the steps of: covering
a portion of the braided wire assembly proximate the location where
the one or more pull wires will be extracted with a melt processing
polymer that is substantially see-through; applying sufficient heat
to the one or more melt processing polymers and the see-through
melt processing polymer to raise the temperature of the polymer
above its melting point.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
application No. 61/820,545, filed 7 May 2013, which is hereby
incorporated by reference as though fully set forth herein.
BACKGROUND
[0002] The present disclosure is generally related to medical
devices useable in the human body. More particularly, the present
disclosure is directed to steerable introducers, catheters or other
medical devices capable of facilitating delivery of and/or access
of other medical devices therethrough.
[0003] Catheters are used for an ever-growing number of procedures.
For example, catheters are used for diagnostic, therapeutic, and
ablative procedures, to name just a few examples. Typically, the
catheter is manipulated through the patient's vasculature and to
the intended site, for example, a site within the patient's heart
or other organ. The catheter may carry one or more electrodes,
which may be used for ablation, diagnosis, or the like. Such
medical devices may instead or additionally facilitate the delivery
of other devices to targeted locations within the body.
[0004] To facilitate placement of catheters or other medical
devices at a location of interest within the patient, it may be
introduced through another catheter, often referred to as a
"guiding catheter," "introducer catheter" "introducer," "sheath,"
or the like, and the terms may be used interchangeably herein.
Generally speaking, an introducer generally refers to a tube that
may be used to place other catheters or medical devices into
specific areas of the body. In some cases, the introducers may be
steerable, and used to place catheters and/or other medical devices
that have little or no directional control, into specific areas of
the patient's body.
[0005] Generally, an introducer would have an overall outside
diameter small enough to negotiate blood vessels or other anatomy
while retaining an inner diameter ("bore size") large enough to
accommodate the medical device therethrough. Furthermore, since the
path within the patient may be long, tortuous, and/or involve
intricate placement of another medical device(s), maneuverability
via steering the introducer may be particularly beneficial.
Steerability may involve steering mechanisms, that can be difficult
to manufacture while maintaining desired yields.
SUMMARY
[0006] In accordance with one embodiment, a catheter assembly is
provided that includes an inner liner made of flexible material,
and an outer layer having a steering mechanism that includes at
least one wire and a corresponding lumen for each of the at least
one wire through which the respective wire may travel. The outer
layer includes a braided wire assembly that includes at least two
wires braided into a wire mesh, and further includes a see-through
portion positioned proximate a pull wire extraction location to
facilitate extraction.
[0007] In accordance with one embodiment, a catheter assembly is
provided that includes an inner liner made of flexible material,
and an outer layer having a steering mechanism that includes at
least one wire and a corresponding lumen for each of the at least
one wire through which the respective wire may travel. The outer
layer includes a braided wire assembly that includes at least two
wires braided into a wire mesh, where the braided wire assembly is
braided in a substantially consistent braid pattern over its
length.
[0008] In accordance with one embodiment, a catheter assembly is
provided that includes an inner liner made of flexible material,
and an outer layer having a steering mechanism that includes at
least one wire and a corresponding lumen for each of the at least
one wire through which the respective wire may travel. The outer
layer includes a braided wire assembly that includes at least two
wires braided into a wire mesh, where the outer layer comprises a
plurality of segments of decreasing durometer from proximal end to
distal end.
[0009] In accordance with another embodiment, a method of
manufacturing a catheter is provided. The method includes providing
a mandrel, placing a lining material over the mandrel to form an
inner liner, placing a thermoplastic elastomer layer over the inner
liner, at least along the mandrel at a location where one or more
pull wires will be extracted, providing at least one pull wire,
placing a flexible liner over each of the at least one pull wires
to create at least one lumen, placing a braided wire assembly over
the inner liner and the at least one flat lumen in a consistent
braid pattern where the braided wire assembly includes at least two
wires braided into a wire mesh, providing pull wire access areas in
the braided wire assembly, covering the braided wire assembly with
one or more melt processing polymers having decreasing durometers
from proximal to distal end of the mandrel, covering a portion of
the braided wire assembly proximate the location where the one or
more pull wires will be extracted with a melt processing polymer
that is substantially see-through, applying sufficient heat to the
one or more melt processing polymers and the see-through melt
processing polymer to raise the temperature of the polymer above
its melting point, cooling the assembly, and removing the mandrel
to form a catheter.
[0010] In accordance with another embodiment, a method of
manufacturing a catheter is provided. The method includes providing
a mandrel, placing a lining material over the mandrel to form an
inner liner, placing a thermoplastic elastomer layer over the inner
liner at least along the mandrel at a location where one or more
pull wires will be subsequently be extracted, providing at least
one pull wire, placing a flexible liner over each of the at least
one pull wires to create at least one lumen, placing a braided wire
assembly over the inner liner and the at least one lumen where the
braided wire assembly includes at least two wires braided into a
wire mesh, covering the braided wire assembly with a melt
processing polymer, applying sufficient heat to the melt processing
polymer to raise the temperature of the polymer above its melting
point, cooling the assembly, and removing the mandrel to form a
catheter.
[0011] In accordance with another embodiment, a method of
manufacturing a catheter is provided. The method includes providing
a mandrel, placing a lining material over the mandrel to form an
inner liner, providing at least one wire, placing a flexible liner
over each of the at least one wires to create at least one lumen,
placing a braided wire assembly over the inner liner and the at
least one lumen consistent braid pattern where the braided wire
assembly includes at least two wires braided into a wire mesh,
covering the braided wire assembly with a melt processing polymer,
applying sufficient heat to the melt processing polymer to raise
the temperature of the polymer above its melting point, cooling the
assembly, and removing the mandrel to form a catheter.
[0012] In accordance with another embodiment, a method of
manufacturing a catheter is provided. The method includes providing
a mandrel, placing a lining material over the mandrel to form an
inner liner, providing at least one wire, placing a flexible liner
over each of the at least one wires to create at least one lumen,
placing a braided wire assembly over the inner liner and the at
least one lumen, the braided wire assembly including at least two
wires braided into a wire mesh, covering the braided wire assembly
with one or more melt processing polymers having decreasing
durometers from proximal to distal end of the mandrel, applying
sufficient heat to the melt processing polymers to raise the
temperature of the polymer above their melting point, cooling the
assembly, and removing the mandrel to form a catheter.
[0013] In accordance with another embodiment, a method of
manufacturing a catheter is provided. The method includes providing
a mandrel, placing a lining material over the mandrel to form an
inner liner, providing at least one pull wire, placing a flexible
liner over each of the at least one wires to create at least one
lumen, placing a braided wire assembly over the inner liner and the
at least one lumen, the braided wire assembly including at least
two wires braided into a wire mesh, providing pull wire access
areas in the braided wire assembly towards a proximal end of the
mandrel, covering the braided wire assembly with a melt processing
polymer, covering a portion of the braided wire assembly proximate
the location where the one or more steering wires will be extracted
with a melt processing polymer that is substantially see-through,
applying sufficient heat to the one or more melt processing
polymers and the see-through melt processing polymer to raise the
temperature of the polymer above its melting point, cooling the
assembly, and removing the mandrel to form a catheter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is perspective view of an embodiment of an introducer
or catheter in which the principles described herein may be
implemented;
[0015] FIG. 2 illustrates a perspective view of a section of an
introducer according to one embodiment, cut away to show
details;
[0016] FIG. 3 is a representative cross-sectional view taken along
line 3-3 in FIG. 2;
[0017] FIG. 4 is a representative cross-sectional view taken along
line 4-4 in FIG. 2;
[0018] FIG. 5 is a representative cross-sectional view taken along
line 5-5 in FIG. 2;
[0019] FIG. 6 is a representative cross-sectional view of an
introducer assembly prior to the application of heat to melt
process the outer layer;
[0020] FIG. 7 is a representative cross-sectional view of an
introducer after the application of heat to melt process the outer
layer;
[0021] FIG. 8 illustrates a perspective view of a partially
assembled representative introducer in accordance with another
embodiment, cut away to show details;
[0022] FIG. 9 illustrates a representative pull ring that may be
used in an introducer in which the principles described herein may
be implemented;
[0023] FIG. 10 is a sectional view of the pull ring of FIG. 9 taken
along line 10-10.
[0024] FIG. 11 is a representative cross-sectional view of a
steerable, large bore introducer in accordance with another
embodiment;
[0025] FIG. 12 depicts a reflow mandrel assembly used in the method
of manufacturing introducers;
[0026] FIG. 13 depicts an inner layer disposed over a reflow
mandrel assembly in accordance with one representative method of
manufacture;
[0027] FIG. 14 depicts a torque transfer layer disposed over an
inner layer in accordance with one representative method of
manufacture;
[0028] FIG. 15 depicts an outer sheath of varying components
disposed over a torque transfer layer in accordance with a
representative method of manufacture;
[0029] FIG. 16 depicts the components of an introducer assembled
over a reflow mandrel assembly having a distal configuration for a
tip assembly;
[0030] FIG. 17 depicts a tip component, having a radiopaque marker,
attached to the distal end of the introducer depicted in FIG.
16;
[0031] FIG. 18 depicts another tip component, having a radiopaque
marker, attached to the distal end of the introducer depicted in
FIG. 16;
[0032] FIGS. 19A/19B depict a flow diagram of a representative
method for manufacturing an introducer shaft in accordance with one
embodiment;
[0033] FIG. 20 is a representative cross-sectional view of an
exemplary introducer assembly prior to the application of heat to
melt process the outer layer;
[0034] FIG. 21 is a representative cross-sectional view of an
exemplary introducer after the application of heat to melt process
the outer layer; and
[0035] FIG. 22 is a representative cross-sectional view of an
exemplary introducer assembly implementing a see-through outer
layer proximate the pull wire extraction site.
DETAILED DESCRIPTION
[0036] The disclosure sets forth improved steerable introducers,
catheters, and/or other medical devices that facilitate passage of
one or more other medical devices therethrough, where improved
manufacturing materials, mechanisms and/or techniques enhance
quality and cast a wider net of collaborative medical devices.
[0037] FIG. 1 is a perspective view of a catheter assembly or
introducer assembly 110 according to one embodiment including a
catheter or an introducer 100 having a proximal portion 150 and a
distal portion 190. The introducer 100 may be operably connected to
a handle assembly 106 which assists in guiding or steering the
introducer during procedures. The introducer 110 further includes a
hub 108 operably connected to an inner lumen (not shown) within the
handle assembly 106 for insertion or delivery of catheter
assemblies, fluids, or any other devices known to those of ordinary
skill in the art. Optionally, the catheter assembly 110 further
includes a valve 112 operably connected to the hub 108.
[0038] FIG. 2 illustrates a perspective view of an exemplary
introducer, cut away to show details. An exemplary method of
manufacture of introducer 100 according to a representative
embodiment will be described with reference to FIGS. 2, 3, 4, 6, 7
and 8. As they are assembled, the introducer components may be
collectively referred to as an introducer assembly or a catheter
assembly.
[0039] Inner liner 20 may be an extruded polytetrafluoroethylene
(PTFE) tubing, such as TEFLON.RTM. brand tubing, which is available
commercially. Inner liner 20 may also be made of other melt
processing polymers, including, without limitation, etched
polytetrafluoroethylene, polyether block amides, nylon and other
thermoplastic elastomers. Once such elastomer is PEBAX.RTM., made
by Arkema, Inc. PEBAX of various durometers may be used, including,
without limitation, PEBAX 30D to PEBAX 72D. In one embodiment,
inner liner 20 is made of a material with a melting temperature
higher than that of an outer layer 60, which will be further
described below, such that inner liner 20 will withstand melt
processing of outer layer 60.
[0040] A wire 30 is placed longitudinally along inner liner 20. The
wire 30 may be any shape or configuration, and is depicted as a
flat wire in the illustrated embodiment. For purposes of this
description, a "flat wire" or a "flat pull wire" generally refers
to a wire that is characterized by a cross-section that, when
measured along two orthogonal axes, is substantially flat. A flat
wire typically has a rectangular cross-section. For example, the
rectangular cross-section may be approximately
0.004''.times.0.012''. The cross-section need not be perfectly
rectangular. For example, the present invention contemplates a
cross-section of the flat wire may be oval, provided that the
overall cross-section is generally flat. For example, a wire may be
properly characterized as a flat wire if it has a cross-section
that is measured X in one direction and greater than X in a second
direction (e.g., at least 3.times.) generally orthogonal to the
first direction. A wire whose cross-section is substantially
I-shaped may also be a flat wire if, generally, its height is
substantially greater than its width at its widest measurement. One
of ordinary skill will appreciate that a flat wire may be defined
in the context of the overall teachings of this application.
[0041] Flat wire 30 may be constructed of stainless steel and may
be about 0.002'' by about 0.016'', or about 0.004'' by about
0.012.'' In one embodiment, at least a portion of flat wire 30 is
encased inside another preformed tube 40 before placement along
inner liner 20 to form a flat lumen 42. Preformed tube 40 need not
have the same shape as the cross-section of flat wire 30, but
instead may be round, oval, rectangular, or another like shape.
Preferably, preformed tube 40 has a cross-section that is not the
same shape as the cross-section of flat wire 30 in order to
facilitate movement of flat wire 30 in preformed tube 40. Preformed
tube 40 may be formed of polytetrafluoroethylene, polyether block
amides, nylon, other thermoplastic elastomers, or another
substance. Preferably, preformed tube 40 has a higher melting point
than outer layer 60, which will be further described below, so that
preformed tube 40 will not melt when outer layer 60 is subjected to
melt processing.
[0042] In alternative embodiments, flat wire 30 may be covered with
lubricious materials including silicone, TEFLON.RTM., siloxane, and
other lubricious materials (not shown), before placement.
Alternatively, flat wire 30 may also be coated with a lubricious
layer to promote slideability. It is also contemplated that flat
wire 30 may be manufactured with a smooth surface to promote
slideability. While stainless steel is a preferred material from
which to compose flat wire 30, other materials may be used,
including, without limitation, materials that are used for
conventional round pull wires.
[0043] More than one flat wire 30 may also be used. In such cases,
each such flat wire 30 may be encased inside its own flexible tube
40 to form separate flat lumens 42. Preferably, a pair of flat
wires 30 are used, spaced apart about 180 degrees about the
circumference of inner liner 20. Although still additional wires 30
may additionally be used to realize additional deflection
directions.
[0044] In one embodiment, outer layer 60 is placed over inner liner
20, flat wires 30, and preformed tube 40 forming flat lumen 42.
Outer layer 60 may be made of either single or multiple sections of
tubing that may be either butted together or overlapped with each
other. In one embodiment, outer layer 60 is an extruded
polytetrafluoroethylene tubing, such as TEFLON.RTM. brand tubing,
which is available commercially. Outer layer 60 may also be made of
other melt processing polymers, including, without limitation,
etched polytetrafluoroethylene, polyether block amides, nylon and
other thermoplastic elastomers. Once such elastomer is PEBAX.RTM.
made by Arkema, Inc. PEBAX of various durometers may be used,
including, without limitation, PEBAX30D to PEBAX 72D. Outer layer
60 may also comprise more than one layer, including for example two
or more tubes of a melt processing polymer.
[0045] Optionally, a braided wire assembly 50 may be placed over
inner liner 20 and any flat wires 30 before outer layer 60 is
applied. Braided wire assembly 50 may be formed of stainless steel
wire, including for example 0.003'' high tensile stainless steel
wire. Braided wire assembly 50 may be formed in a standard braid
pattern and density, for example, about 16 wires at about 10 to
about 60 pics per inch ("PPI") density. These and other consistent
braid patterns may be used in connection with the described (and
analogous) introducers or other guiding medical devices and
described herein.
[0046] Alternatively, a braid may be used that is characterized by
a varying braid density. More particularly, the outer diameter of
the introducer may be minimized at the distal tip by an improved
braided wire assembly, such as the use of a braid that is
characterized by a varying braid density from the proximal end to
the distal tip. In one embodiment, the braid is less dense at the
tip than at the proximal end of the catheter. Some applications may
be better suited if the braid density is more dense at the tip than
at the proximal end, while other applications may be better suited
if the braid density is greater on both ends than in the middle of
the catheter. Thus, for example, braided wire assembly 50 may be
characterized by a first braid density at proximal end 150 of
introducer 100 and then transition to one or more different braid
densities as braided wire assembly 50 approaches distal end 190 of
introducer 100. The braid density of distal end 190 may be greater
or less than the braid density at proximal end 150. In one example,
the braid density at the base (i.e., proximal end 150) is about 50
PPI and the braid density at distal end 190 is about 10 PPI. In
another embodiment, the braid density at distal end 190 is about
20% to about 35% of the braid density at the base/proximal end 150.
In another example, the braid density at proximal end 150 is about
10 PPI and the braid density at distal end 190 is about 50 PPI, or
the braid density at proximal end 150 is about 20% to about 35% of
the braid density at distal end 190.
[0047] As depicted in FIG. 6, the representative mandrel 10 is
round in cross-section in the illustrated embodiment, and may range
from, for example, about 6 inches to about 4 feet or more in
length. The mandrel 10 may represent a component of the introducer
assembly 200, and may be the first component thereof during
manufacture of introducer 100. Mandrel 10 has a distal end and a
proximal end. In one embodiment, the manufacturing process begins
by placing an inner liner 20 on mandrel 10. Inner liner 20 may be
knotted at one end (e.g. the distal end) and then fed onto mandrel
10.
[0048] In one embodiment, and as noted above, the introducer 100
may include a high pic-per-inch (PPI) at the distal end to aid with
deflection, while using a lower PPI in the body which lowers
material costs. This can be accomplished by pulling the braid tight
onto a reflow mandrel 10 having a diameter to match the French size
of the finished introducer. This diameter may be smaller than the
braiding mandrel, and once the braid is pulled down tight on the
reflow mandrel, there may be little difference between the high PPI
and low PPI areas. In cases where the difference does not warrant
additional complexity to the build or risk to the yield by cutting
the braid at specific locations to accommodate the differing PPI
and properly orienting it on the reflow mandrel, a continuous braid
PPI may be used on the braid mandrel. As one representative
example, a substantially consistent braid pattern having
approximately 18-21 PPI on the mandrel 10 may be utilized. Using a
continuous braid PPI over the length of braiding enables the braid
to be cut from anywhere on the reflow mandrel or elsewhere. For
example, the braid can be pulled down tightly on a reflow mandrel
to provide one continuous PPI, and therefore orientation on the
mandrel is not an issue. Further, an easier process may lead to
less "scrap" and therefore higher yields. Thus, in some cases,
benefits of using a consistent braid pattern may include reduced
scrap cost, reduced production time, potentially reduced
part-to-part variability since the braid used throughout the sheath
is the same (PPI) versus variable and operator dependent, etc.
[0049] Braided wire assembly 50 may be formed separately on a
mandrel or disposable core. One or more portions of braided wire
assembly 50 may be heat tempered and cooled before incorporation
into catheter assembly 200 though methods that are known to those
of ordinary skill. The action of heat tempering may help to release
the stress on the wire and help reduce radial forces.
[0050] FIG. 6 displays a cross-section of catheter
assembly/introducer assembly 200 having two flat wires 30 and
braided wired assembly 50 encompassed by outer layer 60 before
lamination of the materials by heating. In one embodiment, a layer
of heat shrink 70 is placed over the top of outer layer 60 as
depicted in FIG. 6. Heat shrink 70 may be, for example, a
fluoropolymer or polyolefin material.
[0051] FIG. 7 depicts introducer assembly 200 after a lamination
process. Catheter assembly 200 may be laminated by heating catheter
assembly 200 until the material comprising outer layer 60 flows and
redistributes around the circumference thereof as depicted in FIG.
7. Heat shrink 70 has a higher melting temperature than outer layer
60; and during the melt process, heat shrink 70 retains its tubular
shape and forces the liquefied outer layer 60 material into braided
wire assembly 50 (if present) and into contact with tubes 40 and
inner liner 20. Introducer assembly 200 may then be cooled. In FIG.
7, mandrel 10 is still in place.
[0052] Mandrel 10 may be removed from introducer assembly 200,
leaving behind a lumen 80 as illustrated in FIG. 4, which depicts
an introducer 100 made in accordance with representative methods
described herein following the application of heat for the
lamination process. Optionally, heat shrink 70 may be left in place
around outer layer 60, as depicted in FIG. 7, even after mandrel 10
is removed.
[0053] If heat shrink 70 is removed, outer layer 60 becomes the
outermost layer of catheter 100. The result is a substantially
circular introducer 200 with pull wires 30 embedded within outer
layer material as illustrated in FIGS. 3 and 4. FIG. 3 is a
cross-sectional view taken at the point of a pull ring 90 as
depicted in FIG. 2, while FIG. 4 is a cross-sectional view taken at
a point proximal to pull ring 90. FIG. 8 is a perspective view of
catheter assembly 200, cut away to show certain details of
construction.
[0054] Introducer assembly 200 may be manufactured using
alternative techniques. In one embodiment, introducer assembly 200
may be formed by extruding outer layer 60 over inner layer 20 and
braid wire assembly 50. In another embodiment, introducer assembly
200 may formed by using a combination of heat and a press that has
a mold for defining the final shape of catheter 100. Still other
variations on representative manufacturing processes are described
below.
[0055] Introducer 100 formed using the methods described herein may
have varying sizes and various uses. For example, introducer 100
may be used in atrial fibrillation cases as well as atrial
tachycardia cases. In connection with certain heart applications,
catheter 100 manufactured using the improvements discussed herein
is preferably less than about 12 French outer diameter, and more
preferably less than about 10 French outer diameter. For use as a
steerable introducer, an outer diameter of approximately 11 French
may be suitable. In other embodiments, the inner diameter may be
from about 10 to 16 French when the introducer 100 is used to
deliver devices such as left atrial appendage occluders. Indeed, by
using flat wires to form braided wire assembly 50, one can achieve
very thin-walled shafts 100, allowing for larger lumen sizes for
given outside dimensions.
[0056] In another embodiment, construction of introducer 100 may be
modified to utilize materials of various durometer hardness (as
measured, for example, using a Shore durometer hardness scale). For
example, proximal end 150 of introducer 100 may be made of a
material such as nylon 11, and the remainder of introducer 100 may
be made of one or more PEBAX materials. In one embodiment, the
durometer hardness levels will decrease as introducer 100 shaft
approaches distal end 190. For example, a nylon base may then be
followed by one or more of the following PEBAX segments: 72D PEBAX;
63D PEBAX; 55D PEBAX; 40D PEBAX; 35D PEBAX; 30D PEBAX. Introducer
100 may also use one or more blends of the foregoing PEBAX
materials, including for example, a 70D/63D PEBAX blend made by
co-extrusion, or a 40D/35D PEBAX blend made by co-extrusion, or a
72D/63D PEBAX blend made by co-extrusion. In one embodiment,
introducer 100 made with one or more segments of varying durometers
will be reflowed together during manufacturing. The length of the
segments may vary. Proximal end 150 of catheter 100 may be the
longest segment, and more distal segments may vary between (for
example) about 0.25'' to about 6'', or possibly from about 0.25''
to about 3''. The hardness levels of the segments and the lengths
of the segments may be adjusted for specific applications, and
preferably, the distal tip segment may have the lowest durometer of
all segments. The segments may be selected to optimize shaft
flexiblity and torque delivery for the specific application.
[0057] In one embodiment, PEBAX is used rather than nylon 11 for
the proximal shaft for purposes of flexibility. In another
embodiment, an additional portion of the distal end is made from a
lower durometer PEBAX than one or more segments positioned
proximally along the shaft. For example, in one particular
embodiment, an additional six inches of a lower durometer PEBAX is
added to the distal end of the shaft for shaft compatibility when,
for example, tracking through the heart to the left atrial
appendage for safety concerns. Thus, in one embodiment, using
different durometer configurations enables shaft integrity and
steerability to be maintained throughout the shaft while having a
softer flexible distal portion to prevent damage to the heart. The
lower durometer portion at the distal end may be positioned at the
distal portion of the proximal shaft yet prior to a most distal
segment that includes a tip, or may be positioned as the last
segment including distal tip itself.
[0058] FIG. 5 illustrates another embodiment in which outer layer
60 is composed of multiple segments 61, 62, 63, 64, each of which
has different material properties, such as degree of hardness,
stiffness, or tensile strength. In one embodiment, segment 61 has
the greatest degree of hardness; segments 62, 63, and 64 are more
flexible than segment 61; segments 63 and 64 are more flexible than
segments 61 and 62; and finally, segment 64 is more flexible than
each of segments 61, 62 and 63. The number of segments may vary, as
well as the relative lengths of the segments. In another
representative embodiment, a more proximal portion such as portion
61 may be more flexible than an adjacent portion immediately distal
to the portion 61. In yet other embodiments, the more proximal
portion 61 may be more flexible than a plurality of the portions
more proximal thereto.
[0059] In yet another embodiment, a modified braided wire assembly
50 is inserted between inner liner 20 and outer layer 60. Braided
wire assembly 50 may be designed to have transitional braid
densities starting at one braid density and transitioning to a
lower braid density. In one embodiment, the braid may begin at a
braid density of about 50 to about 60 PPI, or between about 50 and
about 55 PPI, and then transition to a braid density at the tip of
about 5 to about 20 PPI, or in other examples between about 5 to
about 15 PPI. In another embodiment, the braid may begin at a braid
density of about 5 to about 20 PPI and then transition to a braid
density at the tip of about 50 to about 60 PPI. The braid density
may transition slowly, or it may change using one or more segments.
For example, there may be an intermediate zone with a braid density
of about 30 to about 45 PPI. Variations in the braid density of
braided wire assembly 50 may be used to increase or decrease
flexibility of catheter 100 depending on the desired
application.
[0060] In another embodiment, pull ring 90 is utilized to provide
steerability. FIGS. 9 and 10 illustrate a preferred embodiment for
pull ring 90. Pull ring 90 is a generally circular band with a
cross-sectional shape (measured orthogonally to a tangential line
relative to the circle of the band) that is substantially
rectangular. The rectangular cross-section is more clearly depicted
in FIG. 10. The outer dimension of pull ring 90 is preferably
determined based on the application for catheter 100 to be
manufactured. In one embodiment, pull ring 90 is about 0.10'' in
diameter.
[0061] Pull ring 90 may have at least one slot 91 that is
configured to accommodate flat pull wire 30. Flat pull wire 30 may
be secured within slot 91 by any technique that is appropriate
given the materials of pull ring 90 and flat or other shaped pull
wires 30. Acceptable techniques may include, but are not limited
to, laser welding and/or other welding and bonding techniques.
[0062] In another embodiment, pull ring 90 may include one or more
flow holes 95 as illustrated in FIGS. 9 and 10. During a melting
process, the material of outer layer 60 melts and flows through
flow holes 95. Upon cooling, the material of outer layer 60 bonds
to pull ring 90 to provide better adhesion between pull ring 90 and
the remaining components of catheter assembly 200, thereby
improving performance of catheter 100. While flow holes 95 are
depicted as circular, other shapes may be used. In one embodiment,
pull ring 90 includes two 0.025'' flow holes 95 spaced about 180
degrees apart around the circumference of pull ring 90. The size
and shape of flow holes 95 may be adjusted based on the materials
being used to form inner liner 20 and/or outer layer 60.
[0063] In another embodiment, pull ring 90 is utilized with
non-flat pull wires. Pull ring 90 of this embodiment may utilize a
circular band with a cross-sectional shape (measured orthogonally
to a tangential line relative to the circle of the band) that is
substantially rectangular. Pull ring 90 may have at least one slot
that is configured to accommodate a non-flat pull wire (such as a
round wire). Preferably, the tip of the non-flat pull wire is
tapered to facilitate joinder with pull ring 90. The non-flat pull
wire may be secured within the slot by any technique that is
appropriate given the materials of pull ring 90 and the pull wires.
Acceptable techniques may include, but are not limited to, laser
welding and/or other welding and bonding techniques. In one
embodiment, the non-flat pull wire is located within a preformed
tube 40. Preformed tube 40 need not be the same shape as the
cross-section of the pull wire, but instead, may be round, oval,
rectangular, or another like shape. Preformed tube 40 may have, for
example, a cross-section that is not the same shape as the
cross-section of the pull wire in order to facilitate movement of
the pull wire in the preformed tube. Preformed tube 40 may be
formed of polytetrafluoroethylene, polyether block amides, nylon,
other thermoplastic elastomers or another substance. In one
embodiment, preformed tube 40 has a higher melting point than outer
layer 60 so that the preformed tube will not melt when outer layer
60 is subjected to melt processing. In alternative embodiments, the
pull wire may be covered with lubricious materials, such as
silicone and other lubricious materials, before placement.
Alternatively, the pull wire may be coated with a lubricious layer
to promote slideability, and it is also contemplated that the pull
wire may be manufactured with a smooth surface to promote
slideability. While stainless steel is a preferred material to
compose the pull wire, other materials may be used, including,
without limitation, materials that are used for conventional pull
wires.
[0064] Pull ring 90 is typically utilized near distal end 190 of
introducer 100, but it is anticipated that pull ring 90 may be
located at any position along introducer 100. Moreover, more than
one pull ring 90 may be utilized in the same catheter 100. In one
embodiment of catheter 100, two separate pull rings 90 may be
utilized, each of which has its own flat pull wires 30 connected
thereto.
[0065] Although multiple embodiments have been described above with
a certain degree of particularity, those skilled in the art could
make numerous alterations to the disclosed embodiments without
departing from the teachings set forth herein. For example, pull
ring 90 may be made of stainless steel or other materials,
including, without limitation, materials that are used to form
conventional pull ring assemblies. In addition, braided wire
assembly 50 may be made of stainless steel or other materials,
including materials that are used to form conventional braided wire
assemblies.
[0066] The present disclosure further describes a torque transfer
layer using braided flat wires for a catheter, and a large bore
introducer catheter. For purposes of description, certain
embodiments are described in connection with a flat wire guided, or
steerable, introducer catheter. It is contemplated, however, that
the described features may be incorporated into any number of
catheters or introducers as would be appreciated by one of ordinary
skill in the art. The large bore introducer catheter includes a
combination of components and may be manufactured by either a
reflow process or an extrusion process, allowing for introducer
catheters having an internal diameter of at least about 6 F while
maintaining the desirable improved properties of pushability,
torqueability, and flexibility, for outer diameters of sufficient
size for navigation of cardiac vasculature.
[0067] FIG. 11 depicts a cross-sectional view of an introducer
catheter 1200 in accordance with a representative embodiment. The
illustrated introducer catheter 1200 comprises a tubular polymeric
inner liner 1202, a torque transfer layer 1204, an outer sheath
1206 comprised of a melt-processing polymer, and a heat shrink
layer 1208. In the instance where the introducer is a steerable
introducer, the introducer catheter 1200 further includes at least
one steering wire, such as flat wire 1210, disposed longitudinally
along the length of the introducer catheter 1200. For purposes of
this invention, a "flat wire" refers to a wire that is
characterized by a cross-section that, when measured along two
orthogonal axes, is substantially flat. A flat wire typically has a
rectangular cross section, though the cross section need not be
perfectly rectangular. For example, the present invention
contemplates that a cross section of the flat wire may be oval,
provided that the overall cross section is generally flat. As the
term is used herein, a wire may be properly characterized as a flat
wire if it has a cross section that is measured x in one direction
and at least 2.times. in a second direction generally orthogonal to
the first direction. A wire whose cross section is substantially
I-shaped may also be a flat wire if, generally, its height is
substantially greater than its width at its widest measurement. One
of ordinary skill will appreciate that a flat wire may be defined
in the context of the overall teachings of this application.
[0068] The at least one flat wire 1210 may be further encased
inside another polymeric tubular member 1212 forming a lumen 1214
for housing the flat wire 1210. The introducer catheter according
to this embodiment is manufactured by a reflow bonding process in
which the components are individually fed over a mandrel as
discussed in more detail below.
[0069] In one embodiment, the inner liner 1202 is a polymeric
material, such as polytetrafluoroethylene (PTFE) or etched PTFE.
The inner liner 1202 may also be made of other melt processing
polymers, including, without limitation, polyether block amides,
nylon and other thermoplastic elastomers. Once such elastomer is
PEBAX.RTM. made by Arkema, Inc. PEBAX of various durometers may
also be used, including without limitation, PEBAX 30D or less to
PEBAX 72D or more. In one embodiment, the inner liner 1202 is made
of a material with a melting temperature higher than the outer
sheath 1206 such that the inner liner 1202 will withstand the melt
processing of the outer sheath 1206.
[0070] Inner liner 1202 defines a lumen 1216 therethrough, having a
diameter 1218 of, for example, at least about 6 French, or at least
about 7 French, and in other embodiments a larger bore between
about 10 French and about 24 French. However, in some embodiments,
it is contemplated that lumen 1216 may have a diameter 1218 of up
to about 32 French or more, such as between about 7 French and
about 32 French.
[0071] A torque transfer layer 1204 may be disposed between the
inner liner 1202 and the heat shrink layer 1208, more preferably
between the outer sheath 1206 and the inner liner 1202. In the
instance where the introducer is a steerable introducer utilizing,
for example, at least one longitudinal wire 1210, the torque
transfer layer 1204 may be disposed between the inner layer 1202
and the outer sheath 1206 or between the outer sheath 1206 and the
heat shrink layer 1208. The torque transfer layer 1204 may be made
of stainless steel (for example, 304 or 316) wire or other
acceptable materials known to those of ordinary skill in the
art.
[0072] The torque transfer layer 1204 may be formed of a braided
wire assembly comprised of flat wires, such as stainless steel
wires including, for example, high tensile stainless steel wires.
The torque transfer layer 1204 may be formed in any number of known
braid patterns, including one-over-one (involving at least two
wires), two-over-two (involving at least four wires) crossover
patterns, etc. The braided flat wires typically have a thickness of
at least about 0.0005'' and a width of at least about 0.003''.
Examples of larger sizes include 0.001''.times.0.005'' and
0.002''.times.0.006''. For lumen diameters of at least about 6
French, braided flat wires of at least about 0.003'' thick by at
least about 0.007'' wide, which heretofore were not used to form a
wire mesh for the torque transfer layer, have produced surprisingly
good results of increased pushability, torqueability, flexibility,
and kink resistance over non-flat wires and smaller flat wires. In
general, the individual wires have a ratio of width to the
thickness of at least about 2:1, including, for example, 2:1 to
5:1. Flat wires of about 0.004'' thick by about 0.012'' wide and of
about 0.004'' thick by about 0.020'' wide have also been braided
with success to form torque transfer layers of superior
performance.
[0073] The braid density, commonly measured in pixels per inch
("PPI"), is typically between about 5 and 100, and will depend on
the size of the flat wires as well as the size of the catheter. For
flat wires of at least about 0.003'' thick by about 0.007'' wide
and a catheter having an inner lumen of at least about 6 French,
the PPI is preferably between about 10 and about 90, more
preferably between about 10 and about 55. For example, the PPI for
flat wires of about 0.003'' thick by about 0.007'' wide is
preferably between about 20 and about 90, more preferably between
about 35 and about 55 for an inner lumen of at least 6 French, and
most preferably between about 35 and about 45 for an inner lumen of
at least about 10 French. The PPI for flat wires of about 0.004''
thick by about 0.012'' wide is preferably between about 15 and
about 70, and more preferably between about 15 and about 22 for an
inner lumen of at least about 6 French. The PPI for flat wires of
about 0.004'' thick by about 0.020'' wide is preferably between
about 5 and about 50, and more preferably between about 10 and
about 20 for an inner lumen of at least about 6 French, and most
preferably between about 10 and about 20 for an inner lumen of at
least about 16 French. Thus, as previously noted, the braid density
may be non-varying or substantially consistent over the braiding
length. Among other things, this enables the braid to be cut from
anywhere on the reflow mandrel. For example, the braid can be
pulled down tightly on a reflow mandrel to provide one
substantially continuous PPI, or at least not intentionally varied.
In these cases, placement or orientation on the mandrel is not an
issue, resulting in less wasted braiding.
[0074] Alternatively, the torque transfer layer 1204 may utilize a
varying braid density construction along the length of the
introducer catheter 1200. For example, the torque transfer layer
may be characterized by a first braid density at the proximal end
of the introducer catheter 1200 and then transition to one or more
braid densities as the torque transfer layer 1204 approaches the
distal end of the introducer catheter 1200; the braid density of
the distal end may be greater or less than the braid density at the
proximal end. In one example, the braid density at the proximal end
is about 50 PPI and the braid density at the distal end is about 10
PPI. In another embodiment, the braid density at the distal end is
about 20-35% of the braid density at the proximal end. In another
example, the braid density at the proximal end is about 20-35% of
the braid density at the distal end.
[0075] The torque transfer layer 1204 may be formed separately on a
mandrel or disposable core and subsequently slipped around the
inner liner 1202. One or more portions of the torque transfer layer
1204 may be heat tempered and cooled before incorporation into the
introducer body 1200 through methods that are known to those of
ordinary skill in the art. The action of heat tempering may help to
release the stress on the wire and help reduce radial forces. It is
also contemplated that torque transfer layer 1204 may be braided
directly on the inner liner 1202.
[0076] In one embodiment, a torque transfer layer 1204 comprises
0.003'' by 0.007'' 304 stainless steel wires at 35 PPI for an inner
lumen of 6-10 French. Another representative torque transfer layer
1204 comprises 0.004'' by 0.012'' 304 stainless steel wires at 22
PPI for an inner lumen of 12 French. Yet another representative
torque transfer layer 1204 comprises 0.004'' by 0.020'' 304
stainless steel wires at 13 PPI for an inner lumen of 16 French.
These exemplary torque transfer layers may be manufactured on a
commercially available horizontal braid machine utilizing a
commercially available mandrel or disposable core. Other suitable
methods of manufacturing the torque transfer layer 1204 will be
apparent to those of ordinary skill in the art.
[0077] The outer sheath 1206 may be constructed of an extruded
PEBAX or PTFE tubing. The melt-processing polymer of the outer
sheath 1206 occupies a plurality of voids of the wire mesh in the
torque transfer layer. The outer sheath 1206 may also be made of
other melt processing polymers, including, without limitation,
etched PTFE, polyether block amides, nylon and other thermoplastic
elastomers, at varying durometers. The outer sheath 1206 may also
comprise more than one layer, including, for example, two or more
tubes of a melt processing polymer. Alternatively, as shown in FIG.
15, the outer sheath 306 may be comprised of varying segments 322,
324, 326, 328, 330 differing in hardness and/or material along the
length of the introducer 300 and being reflow bonded together. This
may be accomplished by layering or by placing annular rings of
differing materials along the length of the introducer 300. Varying
the sheath composition in this manner provides the additional
benefit of adjusting flexibility, torqueability, and pushability at
various points along the introducer 300.
[0078] In embodiments where the introducer is a steerable
introducer (e.g., as shown in FIG. 11), at least one flat wire 1210
is provided, preferably extending along substantially the entire
length of the introducer. The flat wire 1210 may be composed of
stainless steel having dimensions of about 0.002''.times.about
0.016'', or about 0.004''.times.about 0.012'' or 0.016'', or other
dimensions. The flat wire may be selected such that the ratio of
the width to thickness is at least about 2:1. In one embodiment, at
least a portion of the flat wire is encased inside a preformed tube
1212 before placement along the inner liner 1202 to form a flat
lumen 1214. The preformed tube 1212 need not be the same shape as
the cross section of the flat wire, but instead, may be round,
oval, rectangular, or another like shape. Preferably, the preformed
tube 1212 has a cross section that is not the same shape as a cross
section of the flat wire 1210, in order to facilitate movement of
the flat wire in the preformed tube. The preformed tube may be
formed of PTFE, etched PTFE, polyether block amides (such as
PEBAX), nylon, other thermoplastic elastomers, or any other known
material to one of ordinary skill in the art. In one embodiment,
the preformed tube 1212 has a higher melting point than the outer
sheath 1206 so that the preformed tube 1212 will not melt when the
introducer catheter 1200 is subjected to melt processing. In
alternative embodiments the flat wire 1210 may be covered with
lubricious materials (not shown) before placement, including
silicone and other lubricious materials. Alternatively, the flat
wire 1210 may also be coated with a lubricious layer to promote
slideability, and it is also contemplated that the flat wire 1210
may be manufactured with a smooth surface to promote slideability.
While stainless steel is a preferred material to compose the flat
wire 1210, other materials may be used, including, without
limitation, materials that are used for conventional pull wires.
More than one flat wire 1210 may also be used, and in such cases,
each such flat wire 1210 may be encased inside its own flexible
tube 1212. Preferably, as shown in FIG. 11, a pair of flat wires
1210 are used that are spaced at 180 degrees apart. The flat wires
1210 are preferably connected to at least one steering ring
typically located near the distal end of the introducer (see, e.g.,
similar flat wires 30 connected to steering ring 90 in FIG. 2). The
proximal ends of the flat wires 1210 are then operably connected to
a steering mechanism (not shown) allowing for manipulation, or
steering, of the introducer catheter 1200 during use.
[0079] A representative method of manufacture is described in
reference to FIGS. 12-18. As the various components are assembled,
the introducer components may be collectively referred to as an
introducer. As depicted in FIGS. 12-18, a mandrel 300 is depicted,
which may be round in cross-section and may have a length ranging
from about 6 inches to about 4 feet in length. Other shapes of
mandrels may be used, depending on what medical device(s) is to be
delivered via the lumen 1216. As depicted in FIG. 12, the mandrel
300 has a distal end 350 and a proximal end 352. As depicted in
FIG. 13, an inner liner 302 is placed on the mandrel 300. The inner
liner 302 is fed on to the mandrel 300 and in one embodiment is
then knotted on one end 320, or both ends. In one embodiment, the
inner liner 302 is a PTFE material.
[0080] As depicted in FIG. 14, a torque transfer layer 304 is then
placed over the inner liner 302 in the illustrated embodiment. In
the case of a steerable introducer catheter, the braided wire
assembly (not shown) may then be placed over the torque transfer
layer 304. Alternatively, the braided wire assembly may be placed
over an outer sheath 306. Another sheath layer (not shown) may
additionally be placed over the braided wire assembly. In one
embodiment, the torque transfer layer terminates proximally of the
distal end of the catheter.
[0081] Next, as depicted in FIG. 15, an outer sheath 306 is placed
over the torque transfer layer 304 and may be made of either single
or multiple sections of tubing that are either butted together or
overlapped with each other. The multiple segments, or layers, of
sheath material may be any length and/or hardness (durometer)
allowing for flexibility of design. FIG. 15 identifies a plurality
of segments, 322, 324, 326, 328 and 330. In this embodiment, the
proximal end 330 of the outer sheath 306 may be made of a material
such as nylon, and the remainder of the introducer may be made of
one or more PEBAX materials. The lengths of the various segments
may vary, but in one embodiment, the durometer hardness levels will
decrease as the outer sheath 306 approaches its distal end. For
example, a nylon base may then be followed by one or more of the
following PEBAX segments: 72D PEBAX; 63D PEBAX; 55D PEBAX; 40D
PEBAX; 35D PEBAX; 30D PEBAX. The introducer shaft may also use one
or more blends of the foregoing PEBAX materials, including, for
example, 70D/63D PEBAX blend made by co-extrusion, or a 40D/35D
PEBAX blend made by co-extrusion, or a 72D/63D PEBAX blend made by
co-extrusion. The various components of the outer sheath 306
according to this embodiment may be reflowed together during
manufacturing. The proximal end of the shaft is the longest segment
in one embodiment, and more distal segments may vary between, for
example, 0.25'' to 6'', or from 0.25'' to about 3'', etc. The
hardness levels of the segments and the lengths of the segments may
be adjusted for specific applications, and in one embodiment the
distal end may have the lowest durometer levels of all segments.
The shaft segments may be selected to improve flexibility,
torqueability, and pushability for the specific application, as
appreciated by one of ordinary skill in the art. Alternatively, the
introducer may be formed by placing a thin inner jacket or layer
(e.g., PTFE layer) onto a mandrel (e.g., stainless steel mandrel)
or extruding a thin inner jacket or layer (e.g., PEBAX layer) onto
an extrusion mandrel (e.g., acetal mandrel), forming a torque
transfer layer over the inner layer, and extruding an outer jacket
or sheath (e.g., PEBAX jacket) over the torque transfer layer.
[0082] As noted above, PEBAX or similar material may be used rather
than nylon 11 for the proximal shaft for purposes of flexibility.
In another embodiment, an additional portion at or near the distal
end is made from a lower durometer material than an adjacent
portion proximal to this additional portion. For example, in one
embodiment, an additional number of inches of a lower durometer
PEBAX is provided at the distal end of the shaft for shaft
compatibility when, for example, tracking through the heart to the
left atrial appendage for safety concerns. Thus, in one embodiment,
using different durometer configurations enables shaft integrity
and steerability to be maintained throughout the shaft while having
a softer flexible distal portion to prevent damage to the heart. In
one particular example, the plurality of segments, 322, 324, 326,
328 and 330 of FIG. 15 may become more rigid with each segment
moving in the proximal direction, whether the plurality of segments
includes any two or more such segments. As a more particular
example, two different segments may be used, such as segment 322
which is positioned adjacent to the main proximal shaft segment
330, such that segments 324, 326, 328 are not present. In this
example, segment 322 may be made of a lower durometer material
relative to the segment 330 (and/or other segment proximal to
segment 322) to provide a softer flexible distal portion.
[0083] For purposes of example, one embodiment thus involves making
a portion of the distal segment 322 of the outer sheath 306, such
as the most distal six inches, from a lower durometer PEBAX or
similar material. The lengths of the two or more segments may vary,
but in one embodiment, the durometer hardness levels will decrease
as the outer sheath 306 approaches its distal end. For example,
PEBAX segments may include a decreasing durometer as the segments
approach the distal end, such as ranging from 72D PEBAX through 30D
PEBAX for segments 330 and 322 respectively, and intermediate
segments 324, 326, etc. (if any) therebetween.
[0084] In one embodiment, a heat shrink layer 308 is placed over
the assembled introducer assembly prior to reflow lamination. The
heat shrink layer 308 may be a fluoropolymer or polyolefin
material, such as FEP, or other suitable material as appreciated by
one of ordinary skill in the art.
[0085] After assembly of the various components, the exemplary
introducer assembly 300 is subjected to a reflow lamination
process. FIG. 11 depicts a cross sectional view of the introducer
assembly after this reflow process. Introducer assembly 1200 may be
laminated by heating the assembly until the material comprising the
outer sheath 1206 flows and redistributes around the circumference.
Preferably, the heat shrink layer 1208 has a higher melt
temperature than the outer sheath 1206, and during the melt
process, the heat shrink layer 1208 retains its tubular shape and
forces the liquefied sheath layer material 1206 into the torque
transfer layer 1204 and into contact with the preformed tubes 1212
and the inner liner 1202. The introducer assembly 1200 may then be
cooled. The mandrel is preferably left in place during the cooling
process as it helps the introducer assembly to retain its inner
lumen of, for example, at least about 6 French. The heat shrink
layer 1208 may be left on the introducer assembly 1200, or
optionally removed. If the heat shrink layer 1208 is removed, the
outer sheath 1206 becomes the outside layer of the introducer
catheter 1200.
[0086] Additionally, as shown in FIGS. 16-18, one embodiment
contemplates the inclusion of a tip assembly for use in medical
procedures, such as an atraumatic tip, including, for example, a
radiopaque material contained therein for location of the tip
during use. For example, FIGS. 16-18 depict a cross section of an
introducer catheter 700 having a distal portion 730 configured to
accept a tip assembly 732 or 734. In both examples, the tip 732 or
734 includes a ring 736, e.g., a radiopaque marker, for location of
the tip 732 or 734 during use. Additionally, FIG. 18 further
includes a tip assembly 734 configured with a plurality of port
holes 738 for delivery of, for example, irrigation fluid. The tip
assembly may further be configured with ablation electrodes (not
shown) operably connected to a power supply (not shown), for use in
cardiac ablation procedures.
[0087] Another representative method of manufacture is now
described in connection with FIGS. 19A and 19B. The illustrated
method of FIG. 19A/B provides one example of a general method for
manufacturing an introducer or other guiding medical device having
particular characteristics, although additional, fewer and/or
different method steps may be implemented in different embodiments.
Further, the description below may be applied to other
manufacturing methods described herein.
[0088] In the example of FIG. 19A/B, an inner liner is placed 1900
on a mandrel 10. For example, a PTFE liner may be placed and
stretched over a reflow mandrel 10. In one embodiment, a thin layer
of PEBAX or analogous layer is added 1902 between the PTFE or other
liner and outer layers (e.g., a braid). In one embodiment, this
layer is added 1902 along the length of the mandrel 10, while in
other embodiments it is added 1902 over some lesser portion of the
mandrel 10. In one particular embodiment, the layer is added over
the length of the mandrel 10, while in another embodiment the layer
is added at least proximate where the pull wires (not yet added to
the assembly) will exit the reflow shaft to attach to an introducer
handle. In one particular embodiment, approximately two inches of
72 durometer PEBAX is slid over the proximal end of the reflow
mandrel 10 and positioned at a location where the pull wires will
exit the reflow shaft to attach to a introducer handle. In one
embodiment, an introducer configured to deliver a left atrial
appendage occluder is manufactured to add this layer of PEBAX
between approximately 36.5 inches and 38.5 inches from the distal
end. In such an embodiment, the pull wires will exit to the handle
somewhere in this range where the underlying layer of PEBAX or
other analogous material was added 1902. FIGS. 20 and 21 are
respective cross-sectional views of an exemplary introducer
assembly prior to and after the application of heat to melt process
the outer layer. Using like reference numbers to those in FIGS. 6
and 7 for corresponding items, the layer of PEBAX or other material
2000 is depicted over the inner liner 20. The cross sectional area
shown in FIGS. 20 and 21 corresponds to at least the portion
proximate to the location where the pull wires will be extracted
from the shaft assembly on the mandrel 10 or the reflowed shaft, as
the case may be.
[0089] Returning to FIG. 19A, a layer of heat shrink may be added
and reflowed via the addition of heat, as shown at block 1904.
After sufficient cooling, the heat shrink layer may be removed 1906
after the PEBAX or other layer 2000 has been reflowed onto the
assembly.
[0090] In one embodiment, the introducer is manufactured to be
steerable, such as bi-directionally steerable. In the example of
FIG. 19A/B, a pull ring and pull wire assembly is prepared and
placed on the mandrel 10, as shown at block 1908. For example, the
pull wires may be attached to the pull ring on substantially
opposite sides of the pull ring in order to facilitate deflection
in substantially opposite directions. In one particular embodiment,
preformed tubes 40 are first placed over the pull wires up to a
position at or near the pull ring, and this assembly is then pulled
over an end (e.g., the distal end) of the reflow mandrel 10. In one
embodiment, at least the pull ring area is reflowed at this time.
Pull wires may then be properly aligned and retained in a desired
position along the assembly.
[0091] One embodiment further involves utilizing a layer, such as
braiding, shown in FIGS. 20 and 21 as braided wire assembly 50. The
braid may be stretched 1910 over the pull ring/pull wire assembly
on the mandrel 10, which in one embodiment is stretched to maintain
a substantially constant or continuous PPI. A stop tube may be
positioned over the distal end point of the braid wire assembly 50,
such as approximately two inches from the distal end of the reflow
mandrel 10, enabling the braid to be stretched 1910 and cut, tied
off, or otherwise managed at the proximal end of the reflow mandrel
10. As previously noted, a continuous braid PPI may be used on the
braid mandrel 10, thereby enabling the braid wire assembly 50 to be
cut from anywhere on the reflow mandrel 10 or elsewhere. For
example, the braid can be pulled down tightly on the reflow mandrel
10 to provide one continuous PPI, whereby orientation on the
mandrel 10 is not an issue, less "scrap" may occur, etc.
[0092] As shown at block 1912, the braid may be spread at
predetermined proximal locations corresponding to the location
where the pull wires will be extracted from the assembly to
ultimately attach to a handle, such as a handle having a steering
mechanism to enable pulling of the pull wires to responsively
deflect the distal end of the introducer. For each pull wire in
which the braid is spread, the braid opening is secured 1914. In
one embodiment, this is performed for each of the pull wires, as
determined at block 1916, until the braid has been spread 1912 and
secured 1914 for each of the pull wires being implemented on that
particular shaft.
[0093] One or more materials are added to the mandrel 10 as shown
at blocks 1918, 1920. For example, one or more outer layer PEBAX or
similar material segments may be added 1918 over the mandrel 10. In
one embodiment, multiple segments having different durometers may
be added 1918 to allow the flexibility of the shaft to differ along
the length of the shaft as desired.
[0094] In one embodiment, at least one transparent, clear,
translucent or otherwise sufficiently "see-through" outer layer
segment 80 is added 1920 along with one or more of the other outer
layers added 1918. This see-through layer may be added 1920 at a
position along the mandrel to correspond to where the braid
openings were made to facilitate extraction of the pull wires for
later attachment to the handle. One or more additional outer layer
segments may optionally be added 1922 to abut this "window" created
from the clear or at least see-through layer. In one embodiment,
this window is created with natural PEBAX that is sufficiently
clear so that the pull wires can, in a later step, be seen for ease
of extraction of the end of the pull wires for attachment to the
handle.
[0095] An example of such a window is shown in FIG. 22. In this
exemplary depiction, the cross sectional view is shown at a
location commensurate with the placement of the see-through layer
that was added at block 1920. A layer of heat shrink may be placed
over any outer layers that have been added 1918, 1920, 1922, and
reflowed, as depicted at block 1924. When the heat shrink layer 70
has been removed 1926, the preformed tube 40 and wire 30 are
visible through the sufficiently clear outer layer 80. This
facilitates extraction of the pull wires for connection to the
handle (now shown), and reduces risk of leakage at the
window/extraction site. It also optionally allows the pull wires to
be pulled between the picks of the braid, thereby increasing
structural integrity of the introducer at the pull wire site.
[0096] Connector 1928 continues the representative method at FIG.
19B, where the pull wires are extracted from the mandrel assembly.
The extraction is accomplished with the assistance of the
"see-through" outer layer that facilitates viewing and access to
the pull wires for extraction and ultimate connection to the
steering mechanism in the handle.
[0097] Block 1930 depicts one representative manner in which the
pull wire(s) may be extracted from the mandrel assembly. This
embodiment is described for purposes of example only, as other
manners of accessing the pull wires using the
transparent/translucent outer layer portion are contemplated. In
this particular example, a cutting mandrel may be inserted 1930-1
into the proximal end of the shaft for cutting support in the
window area. Thus, the cutting mandrel is inserted at least to, and
preferably beyond, the position along the shaft in which the pull
wires are located. The material (e.g., natural PEBAX) that is in
the vicinity of the spread braid picks that reveal the pull wires
is removed 1930-2 over the respective pull wire. This provides
access to the pull wire. If access to all pull wires is not yet
complete as determined at block 1930-3, the next pull wire 1930-4
is processed by removing 1930-2 that material.
[0098] When all pull wires have been processed in this fashion, it
may be determined 1930-5 whether the pull wires are sufficiently
exposed through the window. If not, the part may be rejected
1930-6, such as if the inner liner is cut or damaged, the pull wire
is not exposed, etc. Otherwise, the pull wires are ready to be
extracted.
[0099] In one embodiment, the pull ring may be pulled until the end
of the pull wires are visible in the window, at which time each
pull wire may be retrieved 1930-7 through the spread braid picks. A
tool may be used to access each pull wire and pull the end out of
the sheath assembly. The pull wires may then be pulled 1930-8 or
otherwise manipulated in order to position the pull ring in a
proper location. From this point, additional steps may be performed
such as assembling/attaching 1932 a distal portion. For example, in
one embodiment, a tip design may be used to deliver particular
medical devices, such as including a tip design capable of
delivering left atrial appendage ("LAA") occlusion devices and/or
other devices. Still additional steps may include connecting 1934
pull wires to a handle steering mechanism, etc.
[0100] Among other things, this provides an improved process for
getting pull wires out of the reflow shaft. The improved process
includes any one or more of adding a layer, such as a thin layer of
PEBAX, between the braid layer and the PTFE or other inner liner at
least where the pull wires exit the reflow shaft to attach to the
handle. The window is also reflowed with natural PEBAX or other
suitable see-through material, to be clear enough so that the pull
wires can be seen. Among other things, this reduces the risk of
leak at the window site, and allows the pull wires to be pulled
between the picks of the braid increasing the structural integrity
of the introducer at the pull wire site.
[0101] Such methods enhance manufacturability of large bore
introducers, as well as smaller bore introducers. In one
embodiment, a large bore steerable sheath (approx. 12-14 French) is
designed to improve the alignment with the LAA for delivering
devices, such as LAA occluders (e.g., AMPLATZER.TM. Amulet.TM.
device of St. Jude Medical), implantable structural heart devices,
and the like. Among other things, the present disclosure describes
a large bore steerable sheath large enough to deliver such
devices.
[0102] Although several embodiments have been described above with
a certain degree of particularity, those skilled in the art could
make numerous alterations to the disclosed embodiments without
departing from the spirit or scope of this invention. All
directional references (e.g., upper, lower, upward, downward, left,
right, leftward, rightward, top, bottom, above, below, vertical,
horizontal, clockwise, and counterclockwise) are only used for
identification purposes to aid the reader's understanding of the
present invention, and do not create limitations, particularly as
to the position, orientation, or use of the invention. Joinder
references (e.g., attached, coupled, connected, and the like) are
to be construed broadly and may include intermediate members
between a connection of elements and relative movement between
elements. As such, joinder references do not necessarily infer that
two elements are directly connected and in fixed relation to each
other. It is intended that all matter contained in the above
description or shown in the accompanying drawings shall be
interpreted as illustrative only and not limiting. Changes in
detail or structure may be made without departing from the spirit
of the invention as defined in claims created from this
disclosure.
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