U.S. patent application number 11/831937 was filed with the patent office on 2008-01-24 for medical device for navigation through anatomy and method of making same.
This patent application is currently assigned to PRECISION VASCULAR SYSTEMS, INC.. Invention is credited to D. KENT BACKMAN, CLARK C. DAVIS, STEPHEN C. JACOBSEN, TED W. LAYMAN, CLAY W. NORTHROP, KEVIN T. OLSON, EDWARD J. SNYDER, TODD H. TURNLUND.
Application Number | 20080021408 11/831937 |
Document ID | / |
Family ID | 31188536 |
Filed Date | 2008-01-24 |
United States Patent
Application |
20080021408 |
Kind Code |
A1 |
JACOBSEN; STEPHEN C. ; et
al. |
January 24, 2008 |
MEDICAL DEVICE FOR NAVIGATION THROUGH ANATOMY AND METHOD OF MAKING
SAME
Abstract
Medical devices for navigation through anatomy, including
guidewires, which may have a core wire, a slotted tubular member,
or both. Embodiments may have coils, including non-circular
cross-section edge-wound marker coils, extended coil tips, and
soldered or glued mesial joint coils. Core wires may have a step,
ridge, or taper at the joints to the tubular member, and may be
flattened at the distal tip. Radiopaque material may be located
inside the tubular member, and the distal tip may be heat treated
to make it shapeable. Additional tubular members or coils may be
used concentrically or in line and may enhance flexibility, provide
radiopacity, reduce friction, or reduce material or manufacturing
cost. Tubular members may be chamfered or tapered continuously or
incrementally. Slots may be arranged in groups, such as groups of
three, and may be equal in depth or unequal in depth to provide a
steerable or compressible tip.
Inventors: |
JACOBSEN; STEPHEN C.; (SALT
LAKE CITY, UT) ; DAVIS; CLARK C.; (HOLLADAY, UT)
; NORTHROP; CLAY W.; (SALT LAKE CITY, UT) ;
LAYMAN; TED W.; (PARK CITY, UT) ; OLSON; KEVIN
T.; (SALT LAKE CITY, UT) ; SNYDER; EDWARD J.;
(PARK CITY, UT) ; BACKMAN; D. KENT; (SALT LAKE
CITY, UT) ; TURNLUND; TODD H.; (PARK CITY,
UT) |
Correspondence
Address: |
CROMPTON, SEAGER & TUFTE, LLC
1221 NICOLLET AVENUE
SUITE 800
MINNEAPOLIS
MN
55403-2420
US
|
Assignee: |
PRECISION VASCULAR SYSTEMS,
INC.
2405 West Orton Circle
West Valley City
UT
84119
|
Family ID: |
31188536 |
Appl. No.: |
11/831937 |
Filed: |
July 31, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10604504 |
Jul 25, 2003 |
|
|
|
11831937 |
Jul 31, 2007 |
|
|
|
60399046 |
Jul 25, 2002 |
|
|
|
Current U.S.
Class: |
604/164.13 |
Current CPC
Class: |
A61M 25/09016 20130101;
A61M 25/01 20130101; A61M 25/09 20130101; A61M 25/0013
20130101 |
Class at
Publication: |
604/164.13 |
International
Class: |
A61M 25/09 20060101
A61M025/09 |
Claims
1. A method for manufacturing a medical device, the method
comprising the steps of: providing a core member; providing a
tubular member, the tubular member having a plurality of slots
formed therein; wherein the tubular member includes a material
having super elastic properties; heat treating a region of the
tubular member to locally reduce the super elastic properties of
the material at the heat treated region; and disposing the tubular
member over at least a portion of the core member.
2. The method of claim 1, further comprising disposing an edge
wound coil adjacent to the core member.
3. The method of claim 1, wherein the tubular member includes a
nickel-titanium alloy.
4. The method of claim 1, wherein heat treating a region of the
tubular member to locally reduce the super elastic properties of
the material at the heat treated region includes heat treating a
distal region of the tubular member.
5. The method of claim 1, wherein heat treating a region of the
tubular member to locally reduce the super elastic properties of
the material at the heat treated region allows the heat treated
region of the tubular member to be shapeable.
6. The method of claim 1, wherein heat treating a region of the
tubular member to locally reduce the super elastic properties of
the material at the heat treated region includes heating the region
of the tubular member to about 600 degrees Celsius.
7. The method of claim 6, wherein heating the region of the tubular
member to about 600 degrees Celsius includes heating the region of
the tubular member to about 600 degrees Celsius for about 10
seconds.
8. The method of claim 1, wherein heat treating a region of the
tubular member to locally reduce the super elastic properties of
the material at the heat treated region allows a user to achieve a
permanent bend in the tubular member.
9. A medical device manufactured according to the method of claim
1.
10. A medical device, comprising: a core member; a nickel-titanium
alloy tubular member disposed over at least a portion of the core
member, the tubular member having a plurality of slot formed
therein, a first section, and a second section; wherein the first
section of the tubular member has super elastic properties; and
wherein the second section of the tubular member is shapeable.
11. The medical device of claim 10, further comprising an edge
wound coil disposed adjacent to the core member.
12. The medical device of claim 10, wherein the second section is
defined by heat treating a portion of the tubular member.
13. The medical device of claim 10, wherein the second section is
defined by heating a portion of the tubular member to about 600
degrees Celsius.
14. The medical device of claim 13, wherein the portion of the
tubular member heated to about 600 degrees Celsius is heated to
about 600 degrees Celsius for about 10 seconds.
15. The medical device of claim 10, wherein the second section is
defined by annealing a portion of the tubular member.
16. The medical device of claim 10, wherein the second section is
disposed adjacent to a distal end of the tubular member.
17. The medical device of claim 10, wherein the second section of
the tubular member is adapted to take a permanent bend.
18. A method for manufacturing a medical device, the method
comprising the steps of: providing a tubular member, the tubular
member including a material having super elastic properties;
forming a plurality of slots in the tubular member; and reducing
the super elastic properties in a first portion of the tubular
member while leaving intact the super elastic properties in a
second portion of the tubular member.
19. The method of claim 18, wherein the tubular member includes a
nickel-titanium alloy.
20. The method of claim 18, wherein the first portion of the
tubular member is disposed adjacent to a distal end of the tubular
member.
21. The method of claim 18, wherein the first portion of the
tubular member is shapeable.
22. The method of claim 18, reducing the super elastic properties
in a first portion of the tubular member while leaving intact the
super elastic properties in a second portion of the tubular member
includes heating the first portion of the tubular member to about
600 degrees Celsius.
23. The method of claim 22, heating the first portion of the
tubular member to about 600 degrees Celsius includes heating the
first portion of the tubular member to about 600 degrees Celsius
for about 10 seconds.
24. The method of claim 18, wherein reducing the super elastic
properties in a first portion of the tubular member while leaving
intact the super elastic properties in a second portion of the
tubular member includes annealing the first portion of the tubular
member.
25. The method of claim 18, wherein reducing the super elastic
properties in a first portion of the tubular member while leaving
intact the super elastic properties in a second portion of the
tubular member allows a user to achieve a permanent bend in the
tubular member.
26. A medical device manufactured according to the method of claim
18.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/604,504 filed Jul. 25, 2003, now U.S.
Patent Publication No. US 2004/0181174 A2, which claims the benefit
of priority to U.S. Provisional Application No. 60/399,046, filed
Jul. 25, 2002, the entire disclosures of which are all hereby
incorporated by reference.
FIELD OF INVENTION
[0002] This invention relates generally to medical devices for
navigating through anatomy and methods of making them.
BACKGROUND OF INVENTION
[0003] Medical devices, such as endovascular or intravascular
devices, have been used for many years for purposes such as
performing various medical procedures. A medical device such as an
intravascular device may be introduced into a patient's anatomy or
vasculature at a relatively accessible location, and guided through
the patient's anatomy to the desired location. X-ray fluoroscopy
has been used to observe the tip of the medical device and the
device has been rotated at bifurcations in the anatomy or
vasculature before being pushed further to guide the device to the
desired target location. Medical devices of this type may be solid,
for example, a guidewire, or may be hollow and tubular, for
example, a catheter. Guidewires may be used to guide one or more
tubular intravascular devices to a particular location, and
catheters may be used, for instance, to deliver fluids, extract
fluids, or deliver various objects, agents, or devices to the
particular location.
[0004] In many applications it is desirable that a medical device
or intravascular device bend easily in order to allow it to make
the various bends and turns that are necessary to navigate through
the anatomy or vasculature, and in some cases also to minimize
trauma to the anatomy or vasculature. However, in many applications
it is also desirable that the medical device is stiff enough to not
prolapse, for example, when navigating through relatively large
vasculature. It may also be desirable that such medical devices be
relatively stiff in torsion in order to allow precise control of
rotation in order to guide the device through bifurcations in
vasculature or around obstacles. Another desirable feature of many
embodiments is that they minimize friction with the anatomy to
facilitate their insertion, removal, or both. It may also be
desirable for these medical devices to have adequate radiopacity,
particularly at the distal end, to make them observable under X-ray
fluoroscopy for purposes of navigation.
[0005] In addition, it is desirable that medical devices, such as
guidewires, are strong and durable enough to assure their complete
removal from the patient. Thus, it is desirable that such devices
have adequate tensile strength and resist fatigue during use.
Further, where expensive materials such as nitinol are used, or
expensive fabrication techniques such as forming many slots, it is
desirable that the quantity of these materials or techniques be
limited to locations where they are actually needed in order to
make the devices as inexpensive to manufacture as possible. Other
features and benefits are also desirable, at least some of which
are described herein or are apparent from this document.
SUMMARY OF INVENTION
[0006] The present invention provides medical devices including
intravascular devices such as guidewires. Features of various
embodiments of the present invention include that the devices
provide the desired flexibility in bending, provide excellent
stiffness in torsion, reduce friction with the anatomy, provide
better radiopacity than the prior art, particularly at the distal
end, resist fatigue, minimize trauma to the patient's anatomy, are
capable of navigating through tortuous vasculature, provide the
necessary tensile strength to assure complete removal of the
medical device, and are inexpensive to manufacture. Other features
and benefits are described herein or are apparent from this
document, including features and benefits for particular
embodiments of the present invention.
[0007] Accordingly, the present invention provides a medical device
for navigation through anatomy having an elongate body with a
proximal end, a distal end, and a longitudinal axis extending at
least from the proximal end to the distal end. Such a medical
device may include a helical coil formed from wire having a
substantially non-circular cross section, and the cross section may
have a greater dimension in the radial direction than in the axial
direction. The body may include a tubular member with a plurality
of slots, which may be configured to make the body or tubular
member more flexible in bending. The coil may be located at or near
the distal end of the tubular member, and may be made of a
substantially radiopaque material. The body may further have a core
wire, and at least part of the core wire may be located inside the
tubular member, inside the coil, or both. Such a medical device may
be a guidewire, for example.
[0008] The present invention also provides a medical device
configured to be guided to a target location in anatomy, having a
tubular member and a core wire extending proximally from the
tubular member and attached there with a joint. This joint may have
a coil circumscribing the core wire, and at least partially inside
the tubular member, and may utilize solder, adhesive, or both. For
instance, the core wire and the coil may be metal, and the joint
may have solder attaching the coil to the core wire and adhesive
attaching the coil, solder, core wire, or a combination thereof, to
the tubular member. To allow room for solder, adhesive, or both
between the windings, at least a portion of the coil may have a
pitch of at least 1.5 times the diameter of the coil wire.
[0009] In some embodiments, the core wire may have a tapered
portion, and the joint may be located at least partially within the
tapered portion. And in some embodiments, the core wire may have a
feature configured to facilitate mechanical interlock of the solder
or adhesive, and the joint may be located at that feature. Such a
feature may include, for example, a step, a ridge, or both. Thus,
in some embodiments of the present invention, the core wire may
have at least one abrupt change in cross-sectional dimension, for
example, between its proximal and distal sections. The core wire
may be attached to the tubular member with the proximal end of the
tubular member abutting the abrupt change in cross-sectional
dimension or abutting a proximal coil attached to the core wire.
There may be a smaller diameter mesial coil circumscribing at least
a portion of the core wire, which may be soldered to the core wire,
and the tubular member may be attached to the mesial coil, for
example, with adhesive. And in various embodiments, the core wire
may further be attached to the tubular member at the distal end of
the tubular member, at one or more locations intermediate the
proximal end and the distal end, or both.
[0010] In some embodiments of the present invention, the core wire
may generally have a substantially round cross section, but a
distal section of the core wire located inside the tubular member
may have a flattened cross section for at least a portion of its
length. Such an embodiment may have substantially radiopaque
material located inside the tubular member at the distal section or
end, which may have a substantially semicircular cross section and
may be located on opposite sides of the flattened cross section of
the core wire.
[0011] In some embodiments of the present invention, there may be a
coil extending distally from the distal end of the tubular member.
Such a coil may be made of a substantially radiopaque material, and
there may be a mesial coil of another material proximal to the
radiopaque coil. The core wire may extend distal to the tubular
member inside the coil, and may attach at the distal end of the
coil, core wire, or both. In such embodiments, the core wire may be
axially but not torsionally constrained relative to the coil at the
distal tip of the core wire.
[0012] In other embodiments of the present invention, the tubular
member may extend distal to the distal tip of the core wire and the
medical device may have at least one piece of radiopaque material
inside the tubular member, at or adjacent to the distal end of the
tubular member, and distal to the distal tip of the core wire. In
such embodiments, the core wire may be attached to the tubular
member at the distal tip of the core wire. The radiopaque material
may be in the shape of a helical coil, for example. In some
embodiments, the tubular member may have superelastic properties,
and at least part of the distal end may be heat treated to reduce
its superelastic properties, for example, to make it shapeable by
the user. And in some embodiments, the tubular member may have a
chamfer at its proximal end.
[0013] The present invention still further provides embodiments
having a tapered body, at least in its outside diameter over at
least a portion of its length. The taper may have a decreasing
outside diameter in the distal direction, and may be either
continuous or incremental. In some embodiments, the core wire may
have a larger outside diameter along at least a majority of its
proximal section than that of the tubular member. But in some
embodiments, the tapered portion may include the tubular member. In
an incrementally tapered embodiment of the tubular member, the
tubular member may have an outside diameter that changes in at
least one step between the proximal end and the distal end. In some
such embodiments, the tubular member may have a plurality of
sections which may have different outside diameters, and the
sections may be attached to each other to form the tubular
member.
[0014] Various embodiments of the tubular member include a
plurality of groups of slots formed therein, which may be
substantially perpendicular to the axis, and these groups may
include a plurality of slots at substantially the same location
along the axis. At least a plurality of the longitudinally adjacent
groups of slots may be rotated at an angle around the axis from the
previous group, and the angle may be in the range of 180 degrees
plus or minus no more than 40 degrees, that quantity divided by the
number of slots in the group. In some embodiments, at least a
plurality of the groups may have at least three slots or may
consist of precisely three slots. In such embodiments, the angle of
rotation between adjacent groups may be 180 degrees divided by the
number of slots in the group, plus or minus no more than 10
degrees.
[0015] In some embodiments, each slot in at least a plurality of
the groups may be substantially equal in size and equally spaced
around the axis. But in some embodiments, in at least some groups,
at least one slot may be substantially deeper than at least one
other slot. In such embodiments, the medical device may be
configured so that tensioning the core wire causes the distal end
of the tubular member to change in shape, such as bending or
changing the angle of bend. In addition, in some embodiments, the
spacing between adjacent groups of slots may vary gradually or
incrementally along at least part of the tubular member providing a
varying bending stiffness along that distance, and these groups may
be more closely spaced at the distal end.
[0016] Further, some embodiments of the present invention may have
another tubular member. Thus, some embodiments of the present
invention may have two tubular members which may share a common
longitudinal axis, and may be attached to each other, to the core
wire, or both. One or both tubular members may circumscribe at
least a portion of the core wire, and the two tubular members may
be concentric or in line with each other. One or both tubular
members may have a plurality of slots configured to make it more
flexible in bending, but one or both tubular members may also have
a portion without slots, which may be proximal to the portion with
slots. In some embodiments, one tubular member may lack slots
altogether, and may be made of a polymer material. In some
embodiments, one tubular member may be made of a substantially
radiopaque material. There may also be at least one coil concentric
with at least one of the tubular members, the core wire, or a
combination thereof. One coil may be inside at least one of the
tubular members, and some embodiments may have at least one coil
circumscribing the core wire. At least one tubular member may be at
least partially located inside a coil. Such coils may be used in
joints, provide additional bending stiffness, or provide a greater
or smoother outside diameter, for example.
BRIEF DESCRIPTION OF DRAWINGS
[0017] The figures in this document illustrate various exemplary
embodiments of the present invention. Embodiments of the present
invention may include part or all of the features shown in one of
these drawings, or may include features from two or more figures.
Embodiments of the present invention may also include features
described in the specification, or limitations to features
described in the specification. Furthermore, embodiments of the
present invention may include features that would be familiar to a
person of ordinary skill in the art having studied this
document.
[0018] FIG. 1 is a partially cross-sectional side view illustrating
an embodiment of a medical device in accordance with the present
invention inserted in vasculature in anatomy;
[0019] FIG. 1A is a detail cross-sectional side view of part of the
embodiment illustrated in FIG. 1;
[0020] FIG. 2 is a partially cross-sectional side view illustrating
a mid-portion and distal end of an embodiment of a medical device
in accordance with the present invention having a coil inside a
slotted tubular member;
[0021] FIG. 3 is a partially cross-sectional side view illustrating
a mid-portion and distal end of an embodiment of a medical device
in accordance with the present invention having an extended coil
tip;
[0022] FIG. 4 is a side view illustrating a partially wound coil
made from wire having a non-circular cross section;
[0023] FIG. 5 is a cross-sectional side view illustrating the
distal end of an embodiment of a medical device in accordance with
the present invention having an extended coil tip and a core wire
configured to be free to rotate within the tip of the device;
[0024] FIG. 6 is a cross-sectional side view illustrating the
distal end of an embodiment of a medical device in accordance with
the present invention having an extended coil tip and an internal
coil;
[0025] FIG. 7 is a cross-sectional side view illustrating the
distal end of an embodiment of a medical device in accordance with
the present invention having two tubular members arranged in
line;
[0026] FIG. 8 is a cross-sectional side view illustrating the
distal end of an embodiment of a medical device in accordance with
the present invention having a core wire that terminates proximal
to the distal end of the device, and substantially radiopaque
material inside the distal end of a tubular member;
[0027] FIG. 9 is a cross-sectional side view illustrating the
distal end of an embodiment of a medical device in accordance with
the present invention having a core wire with a distal section
comprised of a plurality of strands of material twisted
together;
[0028] FIG. 10 is a cross-sectional side view illustrating the
distal end of an embodiment of a medical device in accordance with
the present invention having a core wire with a flattened distal
end;
[0029] FIG. 11 is a partially cross-sectional side view
illustrating an embodiment of a mesial joint in accordance with the
present invention having a coil around a core wire and inside a
tubular member;
[0030] FIG. 12 is a partially cross-sectional side view
illustrating an embodiment of a mesial joint in accordance with the
present invention having at least two coils around a core wire at
least one located at least partially inside a tubular member;
[0031] FIG. 13 is a partially cross-sectional side view
illustrating an embodiment of a mesial joint in accordance with the
present invention having two coils and a core wire with a ridge
forming an abrupt change in diameter;
[0032] FIG. 14 is a side view illustrating an embodiment of a
mesial joint in accordance with the present invention a coil
partially located within a helical cutout in a tubular member;
[0033] FIG. 15 is a partially cross-sectional side view
illustrating an embodiment of a mesial joint in accordance with the
present invention having two coils, one inside a tubular member,
and the other abutting the tubular member;
[0034] FIG. 16 is an isometric view of a section of one embodiment
of a tubular member in accordance with the present invention having
slots formed therein in groups of three, wherein the slots are
equal in size and equally spaced around the axis of the tubular
member;
[0035] FIGS. 16A through 16D are cross-sectional end views showing
cross sections of the slots and segments there between of the
embodiment of the tubular member illustrated in FIG. 16;
[0036] FIG. 17 is an isometric view of a section of one embodiment
of a tubular member in accordance with the present invention having
equal size slots formed therein in groups of two, wherein adjacent
groups are rotated 85 degrees around the axis of the tubular
member;
[0037] FIGS. 17A through 17D are cross-sectional end views showing
cross sections of the slots and segments there between of the
embodiment of the tubular member illustrated in FIG. 17 showing the
angle of rotation between adjacent groups of slots and
segments;
[0038] FIG. 18 is an isometric view of a section of one embodiment
of a tubular member in accordance with the present invention having
slots formed therein in groups of two, wherein some groups of slots
contain slots of unequal depth;
[0039] FIGS. 18A through 18D are cross-sectional end views showing
cross sections of the slots and segments there between of the
embodiment of the tubular member illustrated in FIG. 18;
[0040] FIG. 19 is an isometric view of a section of one embodiment
of a tubular member in accordance with the present invention having
slots formed therein in groups of two, wherein all of the groups
contain slots of unequal depth;
[0041] FIGS. 19A through 19D are cross-sectional end views showing
cross sections of the slots and segments there between of the
embodiment of the tubular member illustrated in FIG. 19;
[0042] FIG. 20 is a partially cross-sectional side view
illustrating an embodiment of a steerable medical device in
accordance with the present invention having a tubular member with
slots formed and arranged like the embodiment shown in FIG. 18;
[0043] FIG. 20A is a partially cross-sectional side view
illustrating the tip of the embodiment of a steerable medical
device shown in FIG. 20 adjusted into a bend;
[0044] FIG. 21 is a cross-sectional side view illustrating the
distal end of an embodiment of a medical device in accordance with
the present invention having three tubular members arranged
coaxially;
[0045] FIG. 22 is a cross-sectional side view illustrating the
distal end of an embodiment of a medical device in accordance with
the present invention having two tubular members and a coil on the
outside;
[0046] FIG. 23 is a cross-sectional side view illustrating the
distal end of an embodiment of a medical device in accordance with
the present invention having two tubular members arranged in line;
and
[0047] FIG. 24 is a cross-sectional side view illustrating the
distal end of an embodiment of a medical device in accordance with
the present invention a tapered portion of a tubular member in line
with a slotted portion of a tubular member.
DETAILED DESCRIPTION
[0048] The present invention provides medical devices and
intravascular devices such as guidewires and catheters,
improvements to such devices, and methods of making these devices.
Included in the present invention are various embodiments providing
substantially radiopaque material at or near the distal end to
facilitate X-ray fluoroscopy including edge-wound coils, and
substantially radiopaque material located inside a tubular member,
which may be slotted to improve its bending flexibility. The
present invention also includes various embodiments of flexible
distal tips including extended coil tips, and tips with a flattened
core wire. The present invention even further includes various
embodiments of a mesial joint between a core wire and tubular
member. Many such embodiments use a coil between the core wire and
proximal end of the tubular member, and solder, adhesive, or both.
The present invention still further includes various embodiments of
medical devices with a coil or second tubular member sharing a
common longitudinal axis with the first tubular member, which may
reduce the necessary length of the first tubular member, provide
radiopacity, reduce friction, seal the slots, provide better
bending flexibility, or a combination of these benefits. The
present invention also includes embodiments of various geometry of
slots formed in a tubular member, including arrangements of slots
in groups of two, three, or more, and geometries wherein different
slots in at least some groups are unequal in depth. These later
embodiments provide a steerable device. The present invention also
provides embodiments having tapered bodies, which may include
tapered tubular members.
[0049] Accordingly, FIG. 1 illustrates an exemplary embodiment of
the present invention, guidewire 100. Use as a guidewire is one
example of a use or function of a medical device in accordance with
the present invention. Various elements of the present invention
may be used for other purposes including various medical purposes.
Guidewire 100 may include tubular member 130 and core wire 150,
which may be attached to each other, for example, at joint 140.
Tubular member 130, core wire 150, or both, may form an elongate
body of guidewire 100, which may have a common axis through its
length from at least the proximal end to the distal end. In other
words, tubular member 130 and core wire 150 may share a common
longitudinal axis. As used herein, components are said to share a
longitudinal axis if they are coaxial or in line. The body of
guidewire 100 may have a proximal end 154 and a distal end 138 or
tip 137. This body may include an elongate section 159 proximal to
joint 140 and an elongate section distal to joint 140. The distal
elongate section may include tubular member 130 distal section 158
of core wire 150, or both, for example. Tubular member 130 may have
distal end 138 and proximal end 139. Distal end 138 may include
distal tip 137 of guidewire 100, which may be rounded as shown.
Joint 140 is at proximal end 139 of tubular member 130, in the
exemplary embodiment illustrated.
[0050] Core wire 150 may extend proximally from tubular member 130
(e.g. from proximal end 139 or joint 140 as shown). Core wire 150
may also extend distally from joint 140 inside tubular member 130
as shown. Core wire 150 may have a circular cross section, and may
have a proximal section 159, which may have a constant outside
diameter along part or all of its length, and a distal section 158,
which may have a smaller diameter than proximal section 159. In
some embodiments, proximal section 159 may have a substantially
constant diameter along a majority of its length. In some
embodiments, proximal section 159, distal section 158, portions
thereof, or a combination of these, may be tapered with a
decreasing diameter toward distal tip 137. Distal section 158 of
core wire 150 may be located at least partially inside tubular
member 130 as shown. In various embodiments, tubular member 130 may
have an outside diameter that is smaller, larger, or the same size
as proximal section 159 of core wire 150. The outside diameter of
tubular member 130 may be substantially constant along all or a
majority of its length, or may be tapered, exemplary embodiments of
which are described below. Similarly, the inside diameter of
tubular member 130, and the wall thickness, may be substantially
constant along the length of tubular member 130, or may be
tapered.
[0051] Guidewire 100 may be configured to be flexible in bending,
particularly near distal end 138. The bending stiffness of
guidewire 100 may gradually or incrementally decrease along
guidewire 100 toward distal tip 137, or along a portion of
guidewire 100. For example, the bending stiffness may be constant
along proximal section 159 of core wire 150, but may decrease
gradually along distal section 158 or tubular member 130, for
instance, from proximal end 139 to distal end 138. This flexibility
may be accomplished, at least in part, with a plurality of slots
135 formed in at least part of tubular member 130 as shown in
several figures including FIG. 1. Slots 135 may be micromachined
into tubular member 130, and may be configured to make tubular
member 130 more flexible in bending. To provide a change in bending
stiffness along the length of tubular member 130, slots 135 may be
closer together, deeper, or wider, near distal end 138, in
comparison with proximal end 139. In some embodiments, proximal end
139 of tubular member 130 may have no slots 135, as shown in FIG.
1. In other embodiments, proximal end 139 may contain slots 135,
but they may be farther apart than at proximal end 138, for
example. This spacing may vary gradually along tubular member 130,
or may change incrementally. In many embodiments, slots 135 may
actually be closer together than what is shown in FIG. 1.
[0052] In some embodiments, the stiffness of all or part of core
wire 150 (for example, distal section 158) may also change along
its length by reducing in dimension or diameter. In some
embodiments, varying flexibility along guidewire 100 may be
accomplished or aided by using materials with different properties
at different locations. In some embodiments, more flexible
materials may be used at the distal end, while stiffer materials
may be used at the proximal end. In some embodiments, more flexible
materials may be used at the outside surface farther from the
longitudinal axis, while stiffer materials may be used in the
center or near the axis. Different components made of two or more
different materials having different elasticity may be joined with
joints. For example, tubular member 130 may be made of a
superelastic material such as nitinol, to allow it to bend more
without yielding or fatiguing. In comparison, core wire 150 may be
made of a stiffer material having a greater modulus of elasticity,
for example, stainless steel. As used herein, materials that have
two percent recoverable strain, or more, are considered to be
superelastic materials and have superelastic properties. Nitinol,
for example, may have a recoverable strain of up to ten percent,
depending on the chemistry, heat treatment, and the like. Nitinol
having a recoverable strain of at least two percent is considered
herein to be superelastic.
[0053] In embodiments wherein tubular member 130 is made of a
superelastic material and core wire 150 is made of a stiffer or
more common material such as stainless steel, there may be various
advantages to using more of one component than the other, or
relying on one component rather than the other to provide various
properties such as bending stiffness. For instance, a stainless
steel core wire 150 may have a lower material cost than
superelastic nitinol tubular member 130. In addition, it may be
expensive to form slots 135 in tubular member 130. Thus, there may
be a cost benefit to minimizing the length of tubular member 130.
In addition, slots 135 may substantially reduce the tensile
strength of tubular member 130. Therefore, it may be an advantage
for core wire 150 to be as large as possible to provide adequate
tensile strength when the medical device is removed. On the other
hand, due to its superelastic properties, tubular member 130 may be
able to bend or twist more without failing or deforming
plastically. In addition, due to its shape or cross section,
slotted tubular member 130 may provide a greater torsional
stiffness relative to its bending stiffness, than core wire 150,
thus providing greater rotational control of distal tip 137 from
chuck 152. Thus, there may also be advantages to having a
relatively long tubular member 130, or using tubular member 130 to
provide bending stiffness rather than distal section 158 of core
wire 150.
[0054] As an example, some embodiments of the present invention may
have a proximal end 139 of tubular member 130 without slots 135
(illustrated, for example, in FIGS. 1, 20, and 24), whereas other
embodiments of the present invention may have a shorter tubular
member 130 omitting a proximal end 139 without slots 135
(illustrated, for example in FIG. 3), and providing the desired
bending stiffness in this area with a larger diameter of core wire
150. The first such type of embodiments may be more expensive to
make (assuming tubular member 130 is longer), but may be able to
bend more sharply at unslotted proximal end 139 of tubular member
130 without undergoing plastic deformation or experiencing fatigue.
The first such type of embodiments may also be stiffer in torsion
at that location. In this example, the first type of embodiments
may provide adequate tensile strength at unslotted proximal end
139, since there are no slots reducing the tensile strength of
proximal end 139. Further, it may be beneficial to attach tubular
member 130 to core wire 150 at the distal end of the unslotted
portion. Both such types of embodiments are described in more
detail below.
[0055] Guidewire 100 is shown in FIG. 1 navigating through anatomy
101. Specifically, guidewire 100 is shown penetrating through an
opening 102 that has been cut into the surface of skin 103 and into
vasculature 105. Guidewire 100 is shown passing a distance through
vasculature 105, including trough two bifurcations 107 and 108.
Distal end 138 may include bend 133, which may facilitate
navigating guidewire 100, for example, through the desired branch
of bifurcations 107 and 108. Core wire 150 may contain a handle or
chuck 152, which may be attached or clamped to proximal end 154 or
proximal section 159 of core wire 150, and may be manipulated to
rotate guidewire 100 about its axis. For instance, guidewire 100
may be manually rotated as it is advanced through vasculature 105
to select the desired passageways, for example, at bifurcations 107
and 108.
[0056] Accordingly, it is generally desirable that embodiments of
the present invention move easily through anatomy 101. Various
features and components are described herein which may facilitate
such movement, for example, by reducing friction between guidewire
100 and anatomy 101. For instance, all or part of various
embodiments of the present invention including guidewire 100 may be
coated on its exterior surface with a lubricious coating or
lubricant. As examples, guidewire 100 may be coated with a PTFE,
Parylene, hydrophilic, or hydrophobic coating.
[0057] In some embodiments of the present invention, the tip or
distal end 138 is constructed with a particular preformed bend 133.
In embodiments having a distal end 138 made of a superelastic
material, it may be difficult or impossible for a user to change
bend 133. One reason for this may be that the superelastic material
of tubular member 130, core wire 150, or both cannot be bent
sharply enough to take a permanent set. Accordingly, embodiments of
the present invention include a method for making a medical device
or guidewire 100 that includes locally reducing the superelastic
properties in the tip or distal end 138 of the medical device or
guidewire 100, enough that the tip or distal end 138 can be shaped
by bending it around a tight radius.
[0058] This may be done, for example, by first forming the medical
device, at least part from a superelastic material such as nitinol,
and then heat treating or annealing the part of the tip or distal
end 138 that is desired to be shapeable. An example of such a cycle
consists of heating the tip or distal end 138 to approximately 600
degrees C. for 10 seconds. The result may be a reduction in the
superelastic effect in the heat treated zone which may provide the
ability to achieve a permanent set or bend 133 in the material of
distal end 138 when it is bent sharply.
[0059] A user of such a medical device or guidewire 100 with a
shapeable tip, such a doctor or surgeon, may determine the optimal
angle and location of bend 133, for example, from the type of
procedure to be performed, the anatomy of the particular patient
(e.g., the geometry of bifurcations 107 and 108), or both. The user
may then bend tip 133, and proceed to insert guidewire 100 into
opening 102 of anatomy 101 and into vasculature 105, and to observe
distal end 138 of guidewire 100 with x-ray fluoroscopy, for
example, while navigating guidewire 100 through vasculature 105. In
some embodiments, magnetic resonance imaging (MRI) may be used for
observation instead or in addition. At bifurcations 107 and 108,
the user may rotate chuck 152 to turn bend 133 to point distal tip
137 toward the desired direction and advance guidewire 100 to the
target location. Once at the target location, the user may perform
a medical procedure or advance a catheter over guidewire 100 to
that location to perform a procedure. When the procedure is
completed, or when the catheter is installed, the user may pull
guidewire 100 out through opening 102.
[0060] The present invention includes techniques for construction
and embodiments of small diameter guidewires 100. Various
embodiments of the present invention may be advantageous, for
example, in medical devices having small diameters (for example,
outside diameter (OD) of the guidewire <0.014''). In such
embodiments, the outer diameter of proximal section 159 of core
wire 150 proximal to tubular member 130 may be larger than the
outer diameter of tubular member 130. This may give proximal
section 159 of core wire 150 more torsional stiffness, but this may
be at the expense of greater bending stiffness. In many
applications, the greater bending stiffness may not be a problem
for small diameter guidewires 100 because the tortuosity of the
anatomy (e.g., of vasculature 105) that the proximal section 159 of
core wire 150 must traverse may be low enough to permit greater
bending stiffness.
[0061] In some embodiments of the present invention, including
small-diameter guidewires 100, it may be beneficial to have a
relatively-stiff (in bending) portion of guidewire 100 proximal to
distal end 138. Relatively-high stiffness in this area may prevent
prolapsing when guidewire 100 is being advanced in relatively-large
vessels 105, and may facilitate catheter tracking where a sharp
branch is negotiated off a relatively-large vessel 105. This
relatively-stiff portion may be created, for example, by spacing
slots 135 further apart in this relatively-stiff portion of tubular
member 130. As an example, guidewire 100 may be constructed with a
bending stiffness of approximately 0.00005 pound inches squared
(lb-in.sup.2) for the first one half centimeter (cm) of length from
distal tip 137, followed by a gradual increase in stiffness to
0.0002 lb-in.sup.2 one cm from distal tip 137. The stiffness may
then remain constant until about four cm from distal tip 137, at
which location the stiffness may decrease gradually to about 0.0001
lb-in.sup.2 five cm from distal tip 137. The stiffness may then
remain constant until about eight cm from distal tip 137, at which
location the stiffness may increase gradually to about 0.0004
lb-in.sup.2 approximately twenty cm from distal tip 137. The
bending stiffness may then remain substantially constant (e.g.,
along proximal section 159 of guidewire 100).
[0062] In a variety of embodiments, medical devices in accordance
with the present invention, including guidewire 100, may have a
dense material in distal end 138 or tip 137, for example, to make
the end or tip more easily observable under x-ray fluoroscopy. An
exemplary embodiment of a guidewire 100 with a substantially
radiopaque coil 200 is illustrated in FIG. 2. This embodiment of
guidewire 100 utilizes a micromachined or slotted nitinol torque
tube or tubular member 130 surrounding section 158 of core wire
150. Marker coil 200 may lie inside tubular member 130 at or near
distal end 138, and may circumscribe or surround distal end 257 of
core wire 150. The helical coil shape of coil 200 may allow distal
end 138 to remain flexible in bending, while tubular member 130 may
maintain relative torsional stiffness of guidewire 100 to tip 137.
Coil 200 may be made of a dense material such as, for example, a
platinum-tungsten or platinum-iridium alloy to achieve adequate
radiopacity for distal end 138. Such metals are "substantially
radiopaque", as that phrase is used herein. In general, materials
having substantially more radiopacity than stainless steel or
nitinol are considered herein to be substantially radiopaque. Some
embodiments of the present invention may have a coil 200 that is
not made of a substantially radiopaque material. Such a helical
coil 200 may, for example, contribute to the bending stiffness of
the device, center core wire 150, facilitate bonding between other
components, or a combination of these functions.
[0063] One problem to be overcome in small diameter guidewires is
providing adequate radiopacity. In order to increase the
radiopacity coil 200 to a required or desired level, the diameter
of the platinum or tungsten wire may be increased. But because the
annular space between core wire 150 and the inner diameter of the
micromachined tubular member 130 may be small, there may not be
enough space to provide an adequately radiopaque coil 200 between
core wire 150 and tubular member 130. In addition, increasing the
diameter of the wire used to wind marker coil 200 may have the
undesired effect of increasing the bending stiffness of marker coil
200. Several approaches in accordance with the present invention
may be used to overcome this problem.
[0064] In an exemplary embodiment illustrated in FIG. 3, helical
coil 200 is larger in diameter than coil 200 shown in FIG. 2, and
extends beyond distal end 138 of tubular member 130 rather than
being located inside tubular member 130. Thus, FIG. 3 illustrates
an exemplary embodiment of the present invention having an extended
coil tip 300. Section 158 of core wire 150 may provide the desired
stiffness in bending and torsion, and may provide tensile strength.
Coil 200 may contribute to the stiffness of extended coil tip 300,
especially in bending. In some embodiments, coil 200 may provide
all of the bending stiffness of extended coil tip 300. Some such
embodiments may lack core wire 150, at least within part of or all
of extended coil tip 300.
[0065] Helical coil 200 may be attached to distal end 138 of
tubular member 130, and may extend distally therefrom, for example,
to distal tip 137. Extended coil tip 300 may provide radiopacity,
an atraumatic diameter to contact the anatomy that is significantly
larger in diameter than core wire 150, or both. An extended coil
tip 300 having helical marker coil 200 illustrated in FIG. 3, may
be used, for example, in a 0.014-inch OD coronary guidewire. The
length of extended coil tip 300 or coil 200 may range, for example,
from 0.5 to 5 cm.
[0066] In some embodiments of the present invention, coil 200 may
be wound from wire having a round or circular cross section. But
other embodiments, wire with a non-circular or substantially
non-circular cross section may be used. In some embodiments, such a
non-circular cross section may have at least one flat side, or two,
three, or four flat sides, for example. As illustrated in FIGS.
2-5, coil 200 may be formed from an edge wound strip, which may
give coil 200 a high degree of bending flexibility, greater
radiopacity, or both. Thus, the cross section of the wire from
which coil 200 is made, may have a greater dimension in the radial
direction than in the axial direction (i.e., relative to the
longitudinal axis). Edge wound coil 200 may also provide improved
torsional stiffness, strength, or both, when compared with other
embodiments.
[0067] The edge-wound flat, trapezoidal, or rectangular
cross-section illustrated for coil 200 allows the construction of a
coil 200 with a higher radiopacity (density), a lower bending
stiffness, or both, in comparison with a coil 200 wound from round
wire. This is because when a strip is wound on edge to form coil
200 (i.e., has a greater dimension in the radial direction than in
the axial direction) it may result in a lower stiffness, and a
greater density (and hence radiopacity), or both, when compared to
a coil with the same inside diameter (ID) and outside diameter (OD)
wound from round wire. Specifically, a rectangular strip coil 200
may have, for example, about 1/7.sup.th of the lateral stiffness
and 1/3 more density, when compared with a round wire coil 200. The
increase in density generally stems from better utilization of
space. The stiffness may be decreased because there are more turns
of a less stiff wire in a given length of the rectangular wire coil
200 than in the same length on round wire coil 200. For instance,
coil 200 may have a 0.003-inch ID and a 0.009-inch OD. When made of
a round wire, with a diameter of 0.003 inches, coil 200 may have a
0.005-inch pitch, a lateral stiffness of 20 (in.sup.2-lbs), and a
density of 9 g/in. In comparison, a coil 200 with a rectangular
cross section may have a thickness (in the axial direction) of
0.0016 inches, a width (in the radial direction) of 0.003 inches, a
0.0027-inch pitch, a lateral stiffness of 3 .mu.(in.sup.2-lbs), and
a density of 12 g/in. This embodiment may be implemented, for
example, in coronary or neuro guidewires.
[0068] Referring now to FIG. 4, coil 200 may be wound from wire
420. The cross section 440 of wire 420 may distort or change into
cross section 405 when wire 420 is would into coil 200. In order to
obtain a particular cross section 405 of the wire forming coil 200,
the effect of this distortion may be taken into consideration in
selecting the cross section 440 of wire 420. In one embodiment of
the present invention, wire 420 may have a circular cross section
before being wound, and may have a slightly distorted circular
cross section after being wound. As used herein, such a slightly
distorted circular cross section is considered to be substantially
circular. But in other embodiments, coil 200 may be made so that,
when wound, it has a substantially non-circular cross section 405,
which may have at least one substantially flat side, for example,
side 406. In some embodiments, cross section 405 may also have
another substantially flat side 407, which may be substantially
parallel to side 406. In some embodiments, cross section 405 may
also have substantially flat sides 408, 409, which may be parallel
to each other, and may be shorter than sides 406 and 407. Some
embodiments may have some combination of substantially flat sides
406, 407, 408, and 409. Cross section 405 may be substantially in
the shape of a parallelogram or trapezoid. In the exemplary
embodiment illustrated, cross section 405 is substantially in the
shape of a rectangle. In embodiments of coil 200 where sides 406
and 407 are large relative to sides 408 and 409 (edge-wound coils
or coils having a greater dimension in the radial direction than in
the axial direction), the distortion from cross section 440 to
cross section 405 will be greatest, but the flexibility of coil 200
will also be greatest, relative to the radial distance [(OD
402)/(ID 401)]/2 available.
[0069] Coil 200 may be wound from wire 420, which may have a
substantially non-circular cross section 440. Cross section 440 may
have two substantially flat opposite non-parallel sides 446 and
447. In some embodiments, sides 446 and 447 may be substantially
parallel, and when wound into coil 200, sides 406 and 407 may be
out of parallel, with side 408 longer than side 409. In some such
embodiments, cross section 440 may have the shape of a rectangle,
and cross section 405 may have the shape of a trapezoid. In another
embodiment, sides 446 and 447 may be out of parallel by angle 444.
Cross section 440 may also have substantially flat sides 448 and
449, which may be shorter than sides 446 and 447, and may form a
trapezoid which may be an isosceles trapezoid. In an isosceles
trapezoid cross section 440, sides 446 and 447 are of equal length,
and sides 448 and 449 are parallel. In some embodiments, side 448,
449, or both, may be curved, and may be convex. Similarly, in some
embodiments, side 408, 409, or both, may be curved, and may be
convex. In some embodiments, the effect of this curvature may be
small or insignificant. But in some embodiments where coil 200
forms the outer surface of the device (e.g., in the embodiments
shown in FIGS. 3 and 5), convex curvature of side 409, or a
rounding or chamfering of its corners, for example, may improve the
lubricity of the medical device against anatomy 101, particularly
in locations where extended distal tip 300 is bent around a
curve.
[0070] In some embodiments, angle 444 and the radius of coil 200
(half of ID 401, half of OD 402, or half of a nominal diameter
between 401 and 402) may be selected such that sides 446 and 447
become substantially parallel when wire 420 is wound into coil 200,
and sides 446 and 447 become sides 406 and 407 respectively. Thus
the amount of keystone shape or angle 444 that may be needed or
desirable may depend on the diameter (e.g., ID 401 or OD 402) of
the coil 200 to be wound. The smaller the coil 200 diameter, the
more keystone shape or angle 444 may be needed to compensate for
the deformation in the wire 420 as it bends into coil 200. Other
variables may affect the angle 444, including the thickness (in the
axial direction) of cross section 405 (e.g., the length of side 408
or 409). The shape of cross section 440 may be determined by
calculation, empirically, or a combination thereof, to obtain a
desired cross section 405. Cross section 440 may be formed, for
example, by drawing, rolling, grinding, or machining wire 420, or a
combination thereof. Once the wire is formed with cross section
440, the wire may be wound into coil 200 with cross section 405. In
various embodiments of the present invention, coil 200 may be wound
onto a medical device such as guidewire 100, or may be installed
onto the medical device in a separate step.
[0071] FIG. 2 also illustrates an exemplary embodiment of the
present invention having a proximal chamfer 231 in proximal end 139
of tubular member 130. Proximal chamfer 231 may be flat (e.g., a
conic section) or curved (e.g., a radiused corner). Proximal
chamfer 231 may be beneficial, for example, in embodiments wherein
core wire 150 is gradually tapered at joint 140, or wherein
proximal section 159 of core wire 150 has a smaller OD than that of
proximal end 139 of tubular member 130. For example, chamfer 231
may help provide a smooth transition in diameter from that of
proximal section 159 of core wire 150 to proximal end 139 of
tubular member 130. This may facilitate removal of guidewire 100,
reduce trauma to anatomy during removal, or both. Proximal chamfer
231 may also facilitate a more gradual change in bending stiffness,
reduce stress concentration, provide more surface area for bonding,
or a combination of these benefits. Proximal chamfer 231 may be
implemented, for example, in neuro guidewires.
[0072] FIG. 2 also illustrates an exemplary embodiment of the
present invention having a relatively soft material 261 between at
least part of distal section 158 of core wire 150 and tubular
member 130. In addition, or in the alternative, material 261 may
fill or partially fill at least some of slots 135. Material 261 may
comprise urethane, an epoxy, an adhesive, or a polymer, for
example. Material 261 may increase the stiffness of guidewire 100.
Thus, more slots 135 may be required to obtain a desired bending
stiffness. The greater number of slots 135, with less angle of
bending per slot 135, may result in a greater fatigue life of
tubular member 130. Increasing stiffness with material 261 rater
than by using a larger diameter distal section 158 of core wire 150
may help to avoid plastic deformation or fatigue of section 158 of
core wire 150 for a given radius of bending, for example in
particularly tortuous vasculature 105. In addition, in embodiments
where material 261 fills at least some of slots 135, material 261
may provide a more constant outside diameter reducing friction
between at lest that portion of guidewire 100 and anatomy 101.
[0073] FIGS. 2 and 3 also illustrate that section 158 of core wire
150 may extend distally from joint 140 to distal tip 257 at distal
end 138 of tubular member 130 or to distal tip 137. Distal tip 257
of section 158 of core wire 150 may attach to tubular member 130.
In some embodiments, this may be accomplished by attaching distal
end 138 of tubular member 130 and distal tip 257 of core wire 150
both to distal tip 137. As used herein, core wire 150 is said to be
attached to tubular member 130 if core wire 150 is attached
directly to tubular member 130 (e.g., with solder or adhesive) or
if core wire 150 is attached (e.g., with solder or adhesive 347) to
a coil (e.g., 1141 or 200), busing (e.g., 757) or tip 137, for
example, and tubular member 130 is also attached (e.g., with solder
or adhesive 347) to this same coil, bushing, or tip 130 at
substantially the same location along the longitudinal axis of the
device.
[0074] In embodiments having an extended coil tip 300, the distal
end of coil 200 and the distal tip 257 of core wire 150 may be
attached to each other directly or via tip 137. An exemplary
embodiment is illustrated in FIG. 3, In some embodiments, distal
end 138 of tubular member 130 may be attached to core wire 150, for
example, through a coil, solder, adhesive, or a combination
thereof. An exemplary embodiment where in core wire 150 is attached
to distal end 138 of tubular member 130 (via coil 200 and solder or
adhesive 337) is illustrated in FIG. 6. In the embodiment
illustrated, distal tip 257 of core wire 150 is also attached to
distal tip 137 and the distal end of extended coil tip 300. But
extended coil tip 300 may not be very stiff in torsion. Thus, if
tip 137 is rotated relative to tubular member 130, for example, and
distal section 158 of core wire 150 is completely attached at
distal end 138 of tubular member 130, and at distal tip 137, then
section 158 of core wire 150 may be damaged by exceeding its yield
stress or recoverable strain in torsion.
[0075] To solve this potential problem, the connection of core wire
150 to distal end 138 of tubular member 130, to coil 200, or to tip
137 may be configured in some embodiments to protect core wire 150
inside the extended coil tip 300 from exposure to excessive toque.
For instance, in some embodiments, core wire 150 may not be bonded
to distal end 138 of tubular member 130, or to coil 200 at that
location. An example of such an embodiments is illustrated in FIG.
3. A bushing 338 may be used at distal end 138 of tubular member
130 to isolate section 158 of core wire 150 from the adhesive or
solder 347 used to attach distal end 138 of tubular member 130 to
coil 200 of extended coil tip 300. Bushing 338 may also provide
more bending strength, tensile strength, torsional strength, or a
combination thereof in the joint, and may center guidewire 150.
Bushing 338 may be, for example, a section of tube or coil.
[0076] In another exemplary embodiment illustrated in FIG. 5,
distal tip 257 of core wire 150 may be axially but not torsionally
constrained at distal tip 137 of extended coil tip 300. In the
embodiment illustrated, bushing 538 is attached to the distal end
of extended coil tip 300 or to distal tip 137 of guidewire 100.
Distal section 158 passes through bushing 538 and its distal tip
257 is attached to bushing 557. Bushings 538 and 557 may be
sections of tube or coils, for example. Thus, distal tip 257 of
core wire 150 is free to rotate within extended coil tip 300, but
when distal section 158 of core wire 150 is loaded in tension,
bushing 557 will push on bushing 538, allowing section 158 of core
wire 150 to pull distal tip 137.
[0077] FIG. 6 illustrates another exemplary embodiment of the
present invention having an extended coil tip 300, this embodiment
having coil 600 with a substantially circular cross section. Coil
600 may be made of a substantially radiopaque material. As
illustrated, such an embodiment may also comprise coil 200, which
may be an edge wound coil, and may have a substantially rectangular
cross section as shown. Coil 200 in this embodiment may be made of
a substantially radiopaque material and may provide additional
radiopacity to that of coil 600. Coil 200 may also contribute to
the joint between tubular member 130, coil 600, core wire 150, or
some combination of these components. Solder or adhesive 347 may
bond to tubular member 130, coil 200, coil 600, core wire 150, or
some combination of these. As an example, in the embodiment
illustrated, solder or adhesive 347 is located at both ends of coil
200. Solder or adhesive 347 may also be used to bond coil 600,
distal end 137, core wire 150, coil 200, or some combination of
these components, at distal tip 137, distal end 138, or distal tip
257. In other embodiments, a second tubular member (slotted or
otherwise) may be used in lieu of coil 200, coil 600, or both.
[0078] Another exemplary embodiment of the present invention that
may provide adequate radiopacity is illustrated in FIG. 7 and
involves a second tubular member 730 of a substantially radiopaque
material, which may have good spring characteristics, such as
platinum/tungsten, platinum/iridium, or platinum/iridium/rhodium.
Tubular member 730 may have a plurality of slots 735 configured to
make tubular member 730 more flexible in bending. For example,
slots 735 may be like an embodiment of slots 135 described herein
for tubular member 130. Tubular member 730 may be located at the
distal section 158 of core wire 150, and may extend to or near
distal tip 257. This embodiment may allow better torque
transmission to tip 137 than would be provided by an extended coil
tip 300, and may also provide high radiopacity, when compared with
other embodiments such as the embodiment illustrated in FIG. 2. In
some embodiments, a coil 200 may be located within tubular member
730 which may provide additional stiffness, radiopacity, or
both.
[0079] The length of tubular member 730 may be, for example, within
the range from 0.5 cm to 5 cm. In various embodiments, the wall
thickness of the radiopaque tubular member 730 may be substantially
the same or different than that of tubular member 130. Coils or
bushings 738, 757, or both may be used at the ends of tubular
member 730 to center core wire 150 in the joint, to facilitate
attachment, or both. Solder or adhesive 347 may be used to attach
distal end 138 of tubular member 130, core wire 150, or both, to
tubular member 730. Solder or adhesive 347 may also be used in some
embodiments to attach tubular member 730 to distal tip 137 of
guidewire 100, distal tip 257 of core wire 150, or both.
[0080] Still another exemplary embodiment of the present invention
that may provide adequate radiopacity is illustrated in FIG. 8. In
this exemplary embodiment, core wire 150 is terminated at distal
tip 257 proximal to distal end 138 of the micromachined tubular
member 130, or proximal to distal tip 137. Thus the full lumen
diameter of tubular member 130 distal to distal tip 257 of core
wire 150, or a greater part of this diameter, may then be available
to be filled with radiopaque material. This substantially
radiopaque material may be, as examples, in the form of disks 801,
spheres, coils 802, or micromachined or slotted wire. Distal tip
257 of core wire 150 may attach to tubular member 130, for example,
through coil or bushing 738, solder, adhesive, or a combination
thereof.
[0081] Various embodiments of the present invention include medical
devices, such as guidewire 100, with a tip or distal end 138 with a
relatively high flexibility, a relatively high tensile strength, or
both, as well as methods for constructing such devices.
Specifically, in many embodiments of the present invention, it may
be desirable that the tip or distal end 138 of guidewire 100, for
example, be of low stiffness to prevent perforation or dissection,
for example, of anatomy 101 or vasculature 105. This may be
achieved by grinding distal section 158 of core wire 150 to a small
diameter or by creating a flat or ribbon shaped wire at the distal
end. In guidewire 100, tubular member 130 may carry the torsion
load (e.g., during removal of guidewire 100), at least in the
section distal to joint 140, and section 158 of core wire 150 may
only be required to carry tensile loads in that section. It may
also be desirable to allow tubular member 130 (rather than section
158 of core wire 150) to provide most of the desired bending
stiffness in the section distal to joint 140 because this may
maximize the torque carrying ability of tubular member 130.
[0082] Thus, referring to FIG. 9, it may be advantageous to utilize
a section 158 of core wire 150 for guidewire 100 that maximizes its
tensile strength and minimizes its bending stiffness. This may be
achieved by making section 158 of core wire 150 from a plurality of
smaller wires 958 which may be braided or twisted together to
achieve the same tensile strength as one much larger wire. In other
embodiments, strands or wires 958 may be parallel. Another
embodiment is to utilize a polymer filament with high tensile
strength but low stiffness such as polyethylene (for example,
SPECTRA fiber from ALLIED SIGNAL) or polypropylene, for section 158
of guidewire 150. The polymer core wire may also be stranded in
some embodiments, for example, for additional bending flexibility,
and may be twisted, braided, or parallel.
[0083] In embodiments of the present invention wherein section 158
of core wire 150 has a plurality of metal strands 958, for example
braded or twisted stainless steel cable or wire rope, distal
section 158 may be attached to proximal section 159 of core wire
150 with solder or adhesive 347 as shown in FIG. 9. Distal section
158 may also be attached to distal tip 137, for example, with
solder or adhesive 347. In various embodiments, distal section 137
may be formed from a ball or hemisphere of solder or adhesive 347
surrounding the distal tip 257 of distal section 158. Embodiments
of the present invention wherein section 158 comprises one or more
polymer filaments may be similar, except that an adhesive may be
used rather than solder. For example, an epoxy may be used. The
bond between section 158 and 159 of core wire 150 may be tensile
tested for quality assurance purposes.
[0084] FIG. 10 illustrates another embodiment of the present
invention having a relatively high bending flexibility in the tip,
but only in one direction of bending. This exemplary embodiment has
a flattened core wire 150 at the distal tip 257 of distal section
158. Specifically, the distal end 257 of core wire 150 may be
flattened to achieve a more flexible distal tip 1057. This may be
done on embodiments with or without an extended coil distal tip 300
(e.g., coil 200 illustrated in FIG. 3). As used herein, a tip or
cross section is considered to be flattened if it has one dimension
(perpendicular to the axis) that is at least twice the other
dimension (perpendicular to both the axis and to the first
dimension). An example of a flattened tip 1057 would be 1 cm long
and flattened from a 0.002-inch round core wire (section 158) to
0.001-inch.times.0.003-inch. In various embodiments, the range of
flattened length may be from 0.5 to 5 cm, for example. In some
embodiments, a portion of distal section 158 other than distal tip
257 may be flattened. Flattening a section of core wire 150, for
example, from a substantially round cross section, may provide
greater flexibility in one plane, while providing less flexibility
in a perpendicular plane, both planes passing through the axis of
guidewire 100. Distal tip 1057 may be flattened by rolling or
forging, for example.
[0085] In embodiments having a flattened distal tip 1057, one or
more pieces of substantially radiopaque material 1001 may be
located inside tubular member 130, for example, at distal end 138.
Material 1001 may be in the form of one or more pieces which may
have a substantially semicircular cross section, be slotted disks,
or be in the shape of a coil or a coil with a notch formed in the
ID, for example. Material 1001 may be located on opposite sides of
the substantially flat cross section of the distal section 158 or
distal tip 257 of core wire 150.
[0086] The present invention also includes medical devices having a
number of embodiments of joint 140, for example, medical devices
such as guidewire 100 having tubular member 130 and core wire 150.
Various embodiments of joint 140 are illustrated, as examples, in
FIGS. 11-15. The present invention also includes various methods of
fabricating these devices, which are described herein. The
construction of the proximal joint 140 between the micromachined
tube or tubular member 130 and the core wire 150 in various
embodiments of a guidewire 100 with these components may be a
factor in the performance of the guidewire 100. Referring to FIG.
1, joint 140 may, in various exemplary embodiments, transfer the
torque from the proximal section 159 of the core wire 150 to the
proximal end 139 of tubular member 130. In many embodiments, it may
be desirable that joint 140 be sufficiently short, flexible or
both, so as to not adversely affect the bending stiffness profile
or characteristics of guidewire 100. Joint 140 may, in an exemplary
embodiment of the present invention, also be strong and rugged
enough to undergo the simultaneous or separate application of
torsion, tension, and bending that may occur during use.
[0087] Referring now to FIGS. 11-15, common to various embodiments
of joint 140 may be the use of a coil or section of coil 1141
circumscribing core wire 150 and at least partially inside tubular
member 130 to strengthen joint 140 between core wire 150 and
tubular member 130. Section or coil 1141 may be located at least
part way inside proximal end 139 of tubular member 130 as shown,
and may be stretched, for example, with a pitch of from 1.5 to 5
times the diameter of the wire from which coil 1141 is made. Coil
1141 may be attached to core wire 150 and tubular member 130 with
solder 1147, adhesive 1148, or both. In some embodiments, coil 1141
may be attached to core wire 150 with solder 1147, and then
attached to tubular member 130 with adhesive 1148. Such a joint 140
may be stronger than adhesive 1148 alone because adhesive 1148 may
flow in and around coil 1141 and in some embodiments also cuts or
slots 135 in tubular member 130 and create a mechanically
interlocked structure that may have strength even in the event of a
complete lack of microscopic adhesion of adhesive 1148 to core wire
150, tubular member 130, or both. Coil 1141 may be made from a
metal, for example, stainless steel, or in some embodiments, a
substantially radiopaque material such as platinum or tungsten.
[0088] Various embodiments of the present invention may have one or
more intermediate bonds between core wire 150 and tubular member
130. In such embodiments of the present invention, tubular member
130 may be bonded (e.g., with adhesive 1148) directly to core wire
150, or to a coil, which may be similar to coil 1141. Such bonds
may be, for example, at one or more points intermediate proximal
end 139 and distal end 138 of tubular member 130. These bonds may
transfer torsional or axial forces or both between the two
structural members (tubular member 130 and core wire 150). This
embodiment may be implemented, for example, in neuro
guidewires.
[0089] In exemplary embodiment 1240 of the present invention
illustrated in FIG. 12, joint 140 may be constructed at least
partially within a tapered portion 1253 of core wire 150. A mesial
coil 1243, a proximal coil 345, or both may also be soldered to
core wire 150, for example, in the locations shown. In alternate
embodiments, coil 1141 may be part of mesial coil 1243 (but may
have a different pitch) or may be a separate coil. Mesial coil 1243
may be a marker coil, such as coil 200 illustrated in FIG. 3. It
may be advantageous in some embodiments to terminate a marker coil
(e.g., 200) and begin another coil (e.g., mesial coil 1141 or 1243)
of another material. For instance, one material may be less
expensive than the other, but may be suitable for use in part of
the coil. For example, a platinum marker coil 200 could be
terminated and a stainless steel coil 1141 could continue in its
place. In addition, or in the alternative to a reduction in
material cost, using another material may provide more compressive
strength or stiffness to a medical device such as guidewire 100.
Such an embodiment may be implemented, for example, in a coronary
wire.
[0090] In order to provide a smoother diameter transition,
particularly for embodiments of guidewire 100 that have a
relatively short micromachined tubular member 130, a proximal coil
345 may be used. Proximal coil 345 is shown, for example, in FIGS.
3 and 12-15. Proximal coil 345 may have an outside coil diameter
that may be about the same as that of proximal section 159 of core
wire 150, slotted tubular member 130, or both. Proximal coil 345
may be made, for instance, of stainless steel or other metals. In
various exemplary embodiments, the length of proximal coil 345 may
range from 1 to 30 cm. The termination of proximal coil 345 on its
proximal end may be, for example, at the point where the inner
diameter of proximal coil 345 matches the outer diameter of core
wire 150. This embodiment of the present invention may be
implemented, for instance, in a coronary wire.
[0091] In embodiments having solder 1147 and adhesive 1148, the
quantity of solder 1147 in the spaced or stretched coil 1141 (or
section 1141 of the mesial coil 1243) may be controlled so that
coil 1141 may be soldered to core wire 150 but solder 1147 does not
completely fill the spaces between the loops of coil 1141. Tubular
member 130 may then be slid over coil 1141, mesial coil 1243, or
both, and may butt up against proximal coil 345. Adhesive or glue
1148 may then be wicked into the space between the core wire and
the tube in the location shown, attaching core wire 130 at its
proximal end 139 to coil 1141 and core wire 150. Adhesive 1148 may
form a mechanical interlock against coil 1141, within slots 135, or
both.
[0092] Referring to FIG. 13, which illustrates another exemplary
embodiment of joint 140, joint embodiment 1340 may be constructed
over a feature in core wire 150 or an abrupt change in
cross-sectional dimension or diameter, such as a ridged section
1351 of core wire 150, which may be located between proximal
section 159 and distal section 158. Ridge or ridged section 1351
may be a feature in core wire 150 configured to facilitate
mechanical interlock of solder or adhesive 347, for example, used
for joint 140. Other such features or abrupt changes in
cross-sectional dimension or diameter may include steps, ridges of
other shapes (e.g., shorter in axial length), grooves, slots,
changes in cross section (e.g., round to polygonal), or a
combination of such features.
[0093] Ridged section 1351 may be formed, for example, by grinding
down the remainder of core wire 150, or by installing a coil or
sleeve on core wire 150, which may be soldered, welded, bonded,
shrunk fit, cast, or crimped in place. A coil 1141, which may be
part of a mesial coil 1143, may be soldered to core wire 150 just
distal to the ridge 1351 as shown. Again, the quantity of solder
1147 in the spaced coil section 1141 of the mesial coil 1143 may be
controlled so that the coil 1141 may be soldered to the wire but,
in some embodiments, solder 1147 may not fill the spaces between
the loops of coil 1141. In some embodiments, a proximal coil 345
may be soldered to the proximal section 159 of core wire 150, to
ridge 1351, or both. Tubular member 130 may then be installed over
core wire 150, for instance, to the point where proximal end 139
butts up to proximal coil 345. Adhesive or glue 1148 may be wicked
into the space between tubular member 130 and core wire 150 in the
location shown.
[0094] The embodiment of joint 140 illustrated in FIG. 11 may have
the advantage of not requiring a specific feature or abrupt change
in cross-sectional dimension or diameter like a step, ridge, or
shelf on the ground section of core wire 150. But this embodiment
may have the disadvantage of having a point at or just proximal to
proximal end 139 of tubular member 130 where the bending stiffness
of the assembled guidewire 100 may be lower than the adjacent
portions of guidewire 100. In some applications, this may lead to
fatigue and failure at joint 140 in use. Joint embodiment 1340,
illustrated in FIG. 13, may have a short extra stiff segment at the
proximal end 139 of tubular member 130 at ridge 1351 in core wire
150. This embodiment 1340, however, may yield a more rugged joint
140 when exposed to repeated bending stress. In some embodiments,
the diameter of ridge 1351, other factors, or a combination
thereof, may be selected to obtain a relatively continuous bending
stiffness in the area of joint 140.
[0095] FIG. 14 illustrates still another exemplary embodiment of
the present invention, joint 140 embodiment 1440, which, like the
embodiment illustrated in FIG. 11, may be constructed on a tapered
portion of core wire 150. Mesial coil 1143 and proximal coil 345
may be attached to core wire 150 in the locations shown in FIGS. 11
and 14, for example, with adhesive 1148, solder 1147, or both. In
embodiments having both solder 1147 and adhesive 1148, the quantity
of solder 1147 in the spaced coil section 1141 of mesial coil 1143
may be controlled so that solder 1147 does not fill the spaces
between the loops of coil 1141. In embodiment 1440, proximal coil
345 may have a short spaced-apart region 1442 at it's distal end
that screws into a matching helical cutout 1432 in tubular member
130. Solder 1147 or adhesive or glue 1148 may be wicked into the
space between tubular member 130 and core wire 150 in the location
shown. Thus, joint 140 embodiment 1440 may interlock proximal coil
345 with tubular member 130, which may provide a stronger
connection than some alternatives.
[0096] FIG. 15 illustrates yet another exemplary embodiment of the
present invention, joint 140 embodiment 1540, which may be
constructed at an abrupt change in cross-sectional dimension such
as step 1551 in the diameter of core wire 150. Step 1551 may be a
feature in core wire 150 configured to facilitate mechanical
interlock of solder or adhesive 347, for example, used for joint
140. In various embodiments, step 1551 may be a relatively steep
taper as shown, or may be a square step in diameter, i.e., with a
surface perpendicular to the axis of core wire 150. Radiused inside
corners (for example, such as those shown for ridge 1351 in FIG.
13) may reduce stress concentration. Coil 1141 or section 1141 of
mesial coil 1143 may be attached to core wire 150 at or just distal
to step 1551 as shown. As in other embodiments, solder 1147,
adhesive 1148, or both, may be used to attach coil or section 1141
to core wire 150. In some embodiments, the end of proximal coil 345
may be attached proximal to step 1551 as shown. Tubular member 130
may then be installed on core wire 150 to the point where it butts
up to proximal coil 345. Solder 1147 or adhesive or glue 1148 may
be wicked into the space between tubular member 130 and core wire
150 in the location shown. Joint 140 embodiment 1540 may be similar
to joint 140 embodiment 1340 in that it may reduce or eliminate a
potential weak spot at proximal end 139 of tubular member 130.
Embodiment 1540 may be less costly to produce because of the step
1551 rather than a ridge 1351, but some embodiments 1540 may be not
be quite as rugged as some embodiments of 1351, for example, in
embodiments having a radial gap between tubular member 130 and core
wire 150 at the extreme proximal end of tubular member 130.
[0097] Joint 140 with step 1551 may be useful, for example, on
guidewires that have a short length of tubular member 130, for
instance, a coronary wire with a 5 cm tubular member 130. In such
an exemplary embodiment, core wire 150 may be substantially smaller
than the inner diameter of tubular member 130. Step 1551 in core
wire 150 may allow joint 140 at proximal end 139 of tubular member
130 to have sufficient strength in bending. Step 1551 in core wire
150 may, as examples, either be ground in place on core wire 150,
or a distal tube may be slid over proximal section 159 of core wire
150 and soldered or bonded, for instance, to core wire 150 as a
separate operation.
[0098] The present invention also includes various embodiments of
arrangements and configurations of features making it more flexible
in bending, for example, slots 135. As mentioned with reference to
FIG. 1, tubular member 130 may have a plurality of slots 135 formed
or cut into tubular member 130 to make it more flexible in bending.
Referring to FIG. 2, slots 135 may be formed part way through
tubular member 130, leaving axial beams or segments 236 joining
rings 234. Various embodiments of tubular member 130 are
illustrated in FIGS. 16-19, with various configurations and
arrangements of slots 135, rings 234, and segments 236.
Specifically, slots 135 may be formed in groups of two, three, or
more slots 135, which may be located at substantially the same
location along the axis of tubular member 130, and may be
substantially perpendicular to the axis. FIG. 2 illustrates an
exemplary embodiment having groups 235 of two slots 135 each, and
FIG. 16 illustrates an exemplary embodiment having groups 1635 of
tree slots 135 each. A ring 234 is formed between any two adjacent
groups (e.g., 235 or 1635) of slots 135, and adjacent rings 234 are
attached by a number of segments 236 equal to the number of slots
135 in the group 235. With groups 235 of two slots 135, bending of
tubular member 130 may result from distortion of segments 236,
rings 234, or both. With groups 235 of three or more slots, bending
of tubular member 130 results more from distortion of rings 234.
Thus, fatigue is less likely occur at segments 236 in embodiments
having three or more slots 135 per group 235.
[0099] Adjacent groups 235 or 1635 of slots 135 may be rotated by
an angle relative to each other (i.e., from the adjacent or
previous group 235 or 1635) about the axis of tubular member 130 as
illustrated in FIG. 3 and FIG. 16. Adjacent groups 235 consisting
of two slots 135 may be rotated by and angle of about 90 degrees,
for example, and adjacent groups 1635 consisting of three slots may
be rotated by an angle of about 60 degrees. Thus, segments 236 may
approximately line up in the axial direction with the midpoints of
the adjacent slots 135. In general, this angle of rotation may be
about 180 degrees divided by the number of slots 135 in the group
(e.g., group 235 or 1635).
[0100] In some embodiments, the angle of rotation may be slightly
more or slightly less than the angle given by this formula. Thus,
segments 236 may be a slight angle from lining up with the midpoint
of slots 135 in adjacent groups. Thus, slots 236 may form a helical
pattern along tubular member 130. This slight angle may be, for
example, 1 to 20 degrees for groups 235 of two slots 135 each, and
may be the same or less for groups having more than two slots 135.
In general, the angle of rotation may be 180 degrees plus or minus
no more than 40 degrees, that quantity divided by the number of
slots 135 in the group (e.g., group 235 or 1635). In other words,
the angle of rotation may be within the range of 140 to 220 degrees
divided by the number of slots 135 in the group (e.g., group 235 or
1635). In other embodiments, the angle of rotation may be 180
degrees plus or minus an angle between 1 and 25 degrees, that
quantity divided by the number of slots 135 in the group (e.g.,
group 235 or 1635). In other embodiments, the angle of rotation may
be 180 degrees plus or minus no more than 5 degrees, that quantity
divided by the number of slots 135 in the group (e.g., group 235 or
1635). In still another embodiment, the angle of rotation may be
180 degrees divided by the number of slots in the group, plus or
minus no more than 10 degrees or 1 to 10 degrees.
[0101] FIG. 17 illustrates an exemplary embodiment wherein groups
235 of two slots 135 each are rotated by an angle of approximately
85 degrees from the adjacent group 235. Thus, group 235 at section
B is rotated approximately 85 degrees from group 235 at section A,
group 235 at section C is rotated approximately 85 degrees from
group 235 at section B, and group 235 at section D is rotated
approximately 85 degrees from group 235 at section C. Thus, in this
embodiment, segments 236 form a helical pattern along tubular
member 130. Slots 135 may be formed by cutting or grinding, for
example, with a semiconductor dicing blade. For instance, each slot
135 in a group 235 may be cut in turn by rotating tubular member
130. Then tubular member 130 may be advanced axially, rotated the
desired amount, and the axially adjacent group 235 of slots 135 may
be cut. In the embodiment illustrated in FIG. 17, this desired
amount would be 85 degrees. Rotating by 95 degrees would provide
the same result, except that the helical pattern would be in the
opposite direction.
[0102] In some embodiments of the present invention, it may be
advantageous to form slots 135 of one or more of the configurations
and arrangements described herein in a solid member or wire rather
than in a tubular member (e.g., tubular member 130). For example,
groups 235 of two slots 135 each may be formed in a solid circular
cylinder or wire, which may be formed from nitinol or stainless
steel, for example. In some embodiments, different materials may be
joined, for example, a stainless steel proximal section and a
nitinol distal section, both of which or just the distal section
being slotted. Tapering or changes in diameter may also facilitate
a lower bending stiffness at the distal end. In comparison with a
slotted tubular member 130, for example, a slotted solid member may
have greater tensile strength due to the center portion.
[0103] As an exemplary embodiment, slots 135 may be formed in part
or all of proximal section 159 or distal section 158 of core wire
150 of the exemplary embodiment's described or illustrated herein.
In one embodiment, such a slotted wire may form a guidewire, which
may have a coil (e.g., an external radiopaque coil 200), tubular
member (e.g., 130), coating, or a combination of these. Some
embodiments may be encapsulated with a radiopaque polymer compound,
for example. In some embodiments, there may be a slotted wire in a
slotted tubular member 130, in a radiopaque slotted tubular member
730 (shown in FIG. 7), or both. In another example, such a slotted
solid member or wire may be formed of a substantially radiopaque
material and used as a marker, for example, in lieu of disks 801 or
coil 802 in the exemplary embodiment illustrated in FIG. 8.
[0104] In some embodiments, slots 135 may be substantially equally
spaced around the axis, as shown, for example, in FIGS. 2, 3, and
16. In such embodiments, each slot 135 in a group 235 may be
substantially the same size (e.g., width and depth). However, in
some embodiments, slots 135 may be spaced unequally around the
axis, may be of unequal sizes, or both. As an example, as
illustrated in FIG. 18A, slot 1835a may be substantially deeper
than slot 1835b, thus resulting in segments 1836 being offset from
the center of tubular member 130. In the embodiment illustrated in
FIG. 18, every other (every second) group 236 has unequally sized
slots 135. In the embodiment illustrated in FIG. 19, every group
235 shown has unequally sized slots 135. Further, in the embodiment
illustrated in FIG. 18. all of the groups of unequal depth slots
1835a and 1835b are formed so that segments 1836 are offset in
substantially the same direction relative to the axis of tubular
member 130. In contrast, the embodiment illustrated in FIG. 19
shows that unequal depth slots 1835a and 1835b may be formed so
that segments 1836 are offset in different directions relative to
the axis of tubular member 130. In some embodiments, for example, a
plurality of directions equally spaced around the axis may have
equal numbers of deeper slots 1835a. Such embodiments may have
essentially equal bending characteristics around the axis. In some
embodiments of the present invention, slots 1836b may be omitted,
resulting in one slot 1835a per group 235.
[0105] FIG. 20 illustrates an exemplary embodiment of the present
invention having a tubular member 130 with unequally sized slots
1835a and 1835b of the configuration illustrated in FIG. 18. Other
embodiments may have slots 135 as shown in FIG. 19, for another
example, or may have equally sized slots 135 unequally spaced
around the axis. Steerable medical device 2000 may include tubular
member 130, core wire 150, control knob 2052, and tip 137. Tubular
member 130 and core wire 150 may extend coaxially from control knob
2052 to distal tip 137. In this embodiment, tubular member 130 may
consist of two or more tubes or tubular members attached with one
or more joints, such as joint 140, or may consist of one tube,
which may be slotted at least at distal end 138. For example,
embodiments may be arranged similarly to what is shown in FIG. 7
(with the two tubular members 130 and 730 in line), similarly to
what is shown in FIG. 21 (with the two tubular members 130 and 2130
arranged coaxially), similarly to what is shown in FIG. 22 (with
the two tubular members arranged partially coaxially), or similarly
to what is shown in FIG. 24 (with the two tubular members 130 and
2439 in line or being sections of the same tubular member). Core
wire 150 may be stainless steel, nitinol, or a combination, as
examples, and may have single or multiple strands.
[0106] Medical device 2000 may be steerable by controlling the
shape or amount or angle of bend 133 by applying tension to core
wire 150, for example, with control knob 2052. Increasing the angle
of bend 133 may be accomplished, for example, by pulling on or
turning (screwing) control knob 2052 relative to tubular member
130, inducing bending at unequally sized or offset slots 1835a and
1835b. Unequally sized slots 1835a and 1835b may be located along a
portion of tubular member 130, for example, where bend 133 is
desired. This location may be at or near distal end 138, for
example. In one embodiment, medical device 2000 is a guidewire, and
control knob 2052 is removable to guide a catheter over device
2000. In other embodiments, tubular member 130 may function as a
catheter, which may be usable without a separate guidewire.
[0107] Further, in various embodiments of the present invention, it
may be advantageous to reduce the compressive stiffness along the
axis or column strength or stiffness of at least part of the
medical device or tubular member 130, for example, to avoid
dissection of vasculature 105. In the embodiment illustrated in
FIG. 18, a compressive load on tubular member 130 may cause it to
tend to bend in the direction of slots 1835a. In contrast, in the
embodiment illustrated in FIG. 19, a compressive load on tubular
member 130 may cause it to form a helical shape, bend in a
direction determined by anatomy 101, or just shorten in length
along its axis.
[0108] The present invention also includes various features for
obtaining the desired torsional and bending stiffness of a medical
device such as guidewire 100. Accordingly, FIG. 20 also illustrates
a feature of many embodiments of the present invention, namely
proximal hypotube or sleeve 2062. Sleeve 2062 may be shrunk fit in
place or may be bonded to tubular member 130 (or to proximal
section 159 of core wire 150, for example, in the embodiment
illustrated in FIG. 1), for example with an adhesive, at least at
the ends of sleeve 2062. Sleeve 2062 may be a second tubular
member, and may increase the stiffness, strength, or both, of the
part or parts it is bonded to (e.g., tubular member 130), in
torsion, bending, tension, or a combination thereof. In some
embodiments, sleeve 2062 may be made of a stiffer material than
that to which it is bonded. For example, in the exemplary
embodiment illustrated in FIG. 20, tubular member 130 may be
nitinol, and sleeve 2062 may be stainless steel. In such
embodiments, sleeve 2062 may cover only the proximal end of the
medical device or tubular member 130. In some embodiments, sleeve
2062 may be at least partially slotted, or its outside diameter
tapered, to reduce or control its bending stiffness. For example,
sleeve 2062 may be slotted along its length or at its distal end
similarly to tubular member 130. In some embodiments, control knob
2052 (or chuck 152) may attach or clamp to proximal sleeve 2062. In
some embodiments, such as catheters, sleeve 2062 may substantially
comprise a polymer material, and may seal slots 135.
[0109] FIG. 21 illustrates another exemplary embodiment of the
present invention having tubular member 2130, which may share a
common axis with tubular member 130. Tubular member 2130 may be
concentric with tubular member 130 as shown. Tubular member 2130
may be inside tubular member 130, and tubular member 2130 may have
a plurality of slots 2135 configured to make tubular member 2130
more flexible in bending. Tubular member 2130 may be slotted
similarly to tubular member 130, and slots 2135 may be similar in
arrangement, configuration, or both, to slots 135. Tubular member
2130 may have proximal end 2139 which may be at or near joint 140,
and distal end 2138, which may be located proximal to distal end
138 of tubular member 130 as shown. A substantially radiopaque
marker such as coil 200 may be located at distal end 2138 or distal
to tubular member 2130. Tubular member 2130 may be made of
materials identified herein for tubular member 130, and may be
attached to coil wire 150, tubular member 130, or both, at proximal
end 2139, distal end 2138, or both, for example, with solder or
adhesive 347.
[0110] Still referring to FIG. 21, in some embodiments of the
present invention, part or all of tubular member 130, tubular
member 2130, or both, may lack slots 135 or 2135. For instance, one
tubular member (130 or 2130) may lack slots (135 or 2135) over its
entire length, while the other tubular member (130 or 2130) may
contain slots (135 or 2135). In some such embodiments, part or all
of tubular member 130, tubular member 2130, or both, may contain
slots 135 or 2135 at one or both ends, for example, to smooth the
transition in stiffness at that location. In some embodiments,
portions of tubular member 130, tubular member 2130, or both, that
lack slots 135 or 2135, may be tapered, for example by grinding, to
reduce or control the bending stiffness in such locations.
[0111] As illustrated, some embodiments of the present invention
having two tubular members (e.g., 130 and 2130) may have one or
more abrupt changes in cross-sectional dimension or diameter of
core wire 150, such as steps 2151, 2152, or both, which may be at
the proximal ends of the tubular members. For example, tubular
member 2130 may abut against step 2151, and tubular member 2130 may
abut against step 2152. Steps 2151 and 2152 may be located farther
apart along the axis of core wire 150 than what is shown. Other
embodiments may have a gradual taper in core wire 150 at joint 140,
may comprise coils such as those illustrated in other figures, or
may omit section 159 of core wire 150 proximal to proximal ends 139
and 2139. Some embodiments having two tubular members may be used
in conjunction with extended coil tip 300 described above.
[0112] The embodiment of the present invention with concentric
tubular members 130 and 2130 illustrated in FIG. 21 may have better
resistance to kinking and better fatigue life than other
alternatives, such as alternatives having a single tubular member
130 with fewer slots 135 or a greater wall thickness. Tubular
members 130 and 2130 may be slotted separately or at the same time
(e.g., in concentric configuration). In an exemplary embodiment,
tubular-member 130 may have an OD of 0.0135 inches and an ID of
0.0096 inches, and tubular member 2130 may have an OD of 0.0095
inches and an ID of 0.006 inches.
[0113] In some embodiments of the present invention, it may be
desirable for all or part of the outside diameter of a medical
device such as guidewire 100 to taper gradually or incrementally
(e.g., by stepping) to a smaller OD at distal tip 137. This
tapering may facilitate producing a lower bending stiffness in the
distal direction. In addition, a smaller outside diameter in the
distal end may be desirable, for example, where the medical device
is to navigate through progressively smaller vasculature 105, and
less space is available where distal end 138 is to navigate. As
mentioned with reference to FIG. 1, tubular member 130 may have a
smaller outside diameter than at least part of proximal section 159
of core wire 150. In some embodiments, for example, core wire 150
may taper gradually or incrementally from proximal end 154 to joint
140, for example, and may have a larger OD at end 154 than at joint
140. In another embodiment, proximal section 159 of core wire 150
may have a substantially constant OD, which may be larger than the
OD of tubular member 130.
[0114] In the alternative, or in addition, the OD of tubular member
130 may taper in the distal direction. This taper may be a
continuous gradual taper or an incremental taper, for example. The
inside diameter (ID) of tubular member 130 may also reduce in the
distal direction, or may remain constant. Thus, the wall thickness
of tubular member 130 may also reduce gradually or incrementally in
the distal direction along tubular member 130, or in some
embodiments, may remain substantially constant.
[0115] Tubular member 130 may be tapered, for example, by machining
or grinding its outside surface. In another embodiment, a plurality
of different outside diameter sections of tubular member 130 may be
joined together forming a tubular member 130 that tapers
incrementally, for example, in one or more steps or tapered
portions. The different outside diameter sections may butt together
for joining or may overlap for a distance concentrically, for
example, and may be joined with an adhesive or solder joint or a
weld, for example. In such incrementally tapered embodiments of
tubular member 130, the steps or changes in outside diameter may be
machined or ground to form a chamfer or gradual taper, either along
the entire length of tubular member 130 (i.e., a continuous taper)
or between sections having substantially constant diameters (i.e.,
an incremental taper). Such chamfers or gradual tapers at changes
in diameter may reduce friction and facilitate navigation of the
medical device through anatomy 101. Chamfering or tapering these
changes in diameter may also produce more gradual changes in
stiffness, reduce stress concentration, or both.
[0116] As an exemplary embodiment, and as shown best in FIG. 22,
distal end 2138 of smaller concentric tubular member 2130 may
extend substantially distal to distal end 138 of larger tubular
member 130. Distal tip 137 may be approximately the same size
(e.g., diameter) as the OD of distal end 2138 of tubular member
2130, and may attach thereto, to distal section 158 of core wire
150, or both. In some embodiments, proximal end 2139 of tubular
member 2130 may be where shown in FIG. 21, while in other
embodiments, proximal end 2139 of tubular member 2130 may be just
proximal to distal end 138 of tubular member 130 as shown in FIG.
22. For example, proximal end 2139 of tubular member 2130 may be
far enough proximal to distal end 138 of tubular member 130 to
allow space for a satisfactory joint between proximal end 2139 of
tubular member 2130 and distal end 138 of tubular member 130. Such
a joint may use solder or adhesive 347, for example. In some
embodiments, a bushing or coil 2238 may be located between tubular
member 130, tubular member 2130, or both, or between one or both
tubular members (e.g., 130 and 2130) and distal section 158 of core
wire 150. Tubular member 130, tubular member 2130, or both, may be
attached to distal section 158 of core wire 150 at that location,
for example with solder or adhesive 347 (or a combination of both),
which may surround bushing or coil 2238.
[0117] Referring back to FIG. 21, also illustrated is a feature of
many embodiments of the present invention, sleeve 2162. Sleeve 2162
may be similar to sleeve 2062 illustrated in FIG. 20 and described
above. Sleeve 2162 may be substantially comprised of a flexible
material such as a polymer, and may cover some or all of slots 135
in tubular member 130. Sleeve 2162 may cover all or part of
proximal section 159 of core wire 150 as well, or instead. Further,
in embodiments wherein tubular member 2130 extends distal to distal
end 138 of tubular member 130, sleeve 2162 may extend distal to
distal end 138 of tubular member 130. Thus, sleeve 2162 may cover
at least part of tubular member 2130 and slots 2135 therein. In
some such embodiments, sleeve 2162 may taper or be formed with a
smaller OD distal to distal end 138 of tubular member 130.
[0118] Sleeve 2162 may be shrunk over tubular member 130, tubular
member 2130, proximal section 159 of core wire 150, or a
combination thereof, or may fit loosely (e.g., with a clearance
fit) over other components, and may be affixed for example, with an
adhesive. Sleeve 2162 may be affixed, for example, at both of its
ends. In some embodiments, sleeve 2162 may be affixed at one or
more intermediate locations as well. Sleeve 2162 may improve the
lubricity of tubular member 130 by covering slots 135 and
preventing friction between slots 135 and anatomy 101. Sleeve 2162
may also seal slots 135, for example, to facilitate using the
medical device as a catheter. Further, Sleeve 2162 may increase the
stiffness or strength of the medical device, may increase the OD of
the medical device, or a combination of these effects. In
comparison with other changes that may increase stiffness or OD,
sleeve 2162 may avoid reducing the maximum radius of bend that can
be achieved without plastic deformation, may avoid reducing fatigue
life for a given radius of bend, or both.
[0119] In still another exemplary embodiment of the present
invention illustrated by FIG. 21, tubular member 2130 may be a
polymer tube. A polymer tubular member 2130 may not require slots
2135, but may increase stiffness without reducing maximum elastic
bending radius or fatigue life of the medical device for a given
radius of bend. Tubular member 2130 without slots 2135 may
facilitate use of the medical device as a catheter, for example, in
embodiments lacking core wire 150 or proximal section 159 thereof.
In embodiments having at least distal section 158 of core wire 150,
tubular member 2130 may also serve as a spacer between tubular
member 130 and distal section 158 of core wire 150, and may keep
section 158 of core wire 150 relatively centered within tubular
member 130. Tubular member 2130 may prevent contact between tubular
member 130 and core wire 150, reducing friction or wear. A polymer
tubular member 2130 may be shrunk fit over distal section 158 of
core wire 150, or may fit loosely thereover (e.g., with a clearance
fit).
[0120] Another exemplary embodiment of the present invention having
a second tubular member is illustrated in FIG. 23, which may be an
alternate embodiment of guidewire 100. In this embodiment, second
tubular member 2330 may be located in line with tubular member 130
and may be proximal to tubular member 130 as shown. Core wire 150
may extend through tubular member 2330 and at least part of tubular
member 130, and may further extend proximal to tubular member 2330
as shown. Core wire 150 may have an intermediate section 2356
between proximal section 159 and distal section 158, and tubular
member 2330 may be located at intermediate section 2356. The
diameter of core wire 150 at section 2356 may be less than the
diameter of core wire 150 at section 159, greater than the diameter
of core wire 150 at section 158, or both. There may be an abrupt
change in cross-sectional dimension or diameter (OD) of core wire
150 between proximal section 159 and intermediate section 2356 as
shown, or there may be a gradual taper at that location. Similarly,
there may be an abrupt change in cross-sectional dimension or
diameter (OD) of core wire 150 between intermediate section 2356
and distal section 158, also as shown, or there may be a gradual
taper at that location as well. Core wire 150 may have a great
enough diameter at intermediate section 2356 to provide adequate
strength and stiffness in torsion, as well as in bending.
[0121] As illustrated, such a guidewire 100 may also have a
substantially radiopaque marker, such as coil 200, located at or
near distal tip 137. Tubular member 2330 my be polymer, may be
shrunk fit over section 2356 of core wire 150, or may be attached
with an adhesive. Tubular member 2330 may be attached just at its
ends, at intermediate locations as well, or along the entire length
or at least a portion of tubular member 2330. The use of a polymer
tubular member 2330, or tubular member 2330 made of a
non-superelastic material, may reduce the necessary length of
tubular member 130, reducing the cost of guidewire 100. Tubular
member 2330 may also provide a more lubricious surface (e.g., in
comparison with the surface of slotted tubular member 130), thus
reducing friction between guidewire 100 and anatomy 101 at that
location along the longitudinal axis. Further, tubular member 2330
may provide a larger diameter and stiffer section than section 2356
of core wire 150 alone, thus reducing the likelihood of dissection
of vasculature 105 and increasing the stiffness of guidewire 100 at
that location without reducing bending capability or fatigue
resistance.
[0122] In other embodiments, tubular member 2330 may be slotted,
and may be made of a superelastic metal. In some embodiments,
tubular member 130 may be made of a substantially radiopaque
material. In embodiments where tubular member 2330 is metal, it may
be attached to other metal components with either solder or
adhesive 337, for example.
[0123] FIG. 24 illustrates another exemplary embodiment of the
present invention having a proximal portion of tubular member 130
or a second tubular member 2439 which may be attached to tubular
member 130. Proximal portion of tubular member 130 or second
tubular member 2439 may lack slots 135, but may be tapered at least
at its OD in the distal direction as shown, providing a varying
bending stiffness along at least part of its length. Thus, the wall
thickness of proximal portion of tubular member 130 or second
tubular member 2439 may become thinner in the distal direction, at
least over part of proximal portion or second tubular member 2439.
Tapering proximal portion of tubular member 130 or second tubular
member 2439 may also serve to minimize or avoid a substantial
change in stiffness at the proximal end of the section containing
slots 135. This may serve to reduce fatigue at that location or at
the most proximally located slot or slots 135.
[0124] In embodiments wherein distal portion of tubular member 130
or second tubular member 2439 is a separate piece from tubular
member 130, there may be a joint 2440 between second tubular member
2439 and tubular member 130, an exemplary embodiment of which is
shown. Bushing or coil 2441 may be located part way inside second
tubular member 2439 and part way inside tubular member 130, and may
be attached to each tubular member (i.e., 2439 and 130) with solder
or adhesive 347. In embodiments having core wire 150, bushing or
coil 2441 may also serve as a spacer centering core wire 150, and
may be attached to core wire 150, for example, with solder or
adhesive 347. In another exemplary embodiment of joint 2440, second
tubular member 2439 may be welded to tubular member 130.
[0125] Distal portion of tubular member 130 or second tubular
member 2439 may have an un-tapered (e.g., constant OD) section at
its proximal end. In various embodiments, chamfers 231 may be
provided at one or both ends of portion or member 2439. In
embodiments wherein distal portion of tubular member 130 or second
tubular member 2439 is part of tubular member 130, the assembly
(i.e., tubular member 130) may be made of a superelastic material
such as nitinol. In embodiments with a separate tubular member
2439, tubular member 130, tubular member 2439, or both may be made
of a superelastic material such as nitinol. Or tubular member 2439
may be made of a polymer or stainless steel, for example. In some
embodiments, tubular member 130 may be made of a substantially
radiopaque material.
[0126] Referring once again to FIG. 22, also illustrated is another
feature of various embodiments of the present invention, namely
coil 2266. Coil 2266 may share a common axis with tubular member
130, tubular member 2130 (shown) or both. Further, coil 2266 may be
concentric with and external to tubular member 130, tubular member
2130 (shown) or both. Coil 2266 may extend distally from tubular
member 130 as shown. Thus, coil 2266 may form an extended coil tip
300 having a second tubular member 2130. Coil 2266 may be wound
from wire having a substantially round cross section as shown, or
may be an edge wound coil 200 as described above and shown in other
figures. A lubricious coating 2269 may be applied over coil 2266,
which may occupy all or part of the space between the windings of
coil 2266. The same may be true for coil 345 illustrated in FIGS.
12-15, for example.
[0127] The rounded bumps of coil 2266 or 345 may provide a lower
friction surface than the slotted exterior surface of tubular
member 2130 or 130, for example. In addition, coating 2269 between
the windings of coil 2266 may provide lubricity even when
lubricious coating 2269 from the outermost surface has been worn
away. Embodiments of the present invention having an extended coil
tip 300, (illustrated in FIG. 3) may also have a coil 2266, a
lubricious coating 2269, or both over coil 200. Coil 2266 may be
particularly beneficial to lubricity in such embodiments wherein
coil 200 has a cross section having sharp corners at its outside
diameter. Coil 2266 may comprise a substantially radiopaque
material, or a radiopaque material may be located inside coil 2266,
for example, marker coil 200 shown inside tubular member 2130.
[0128] The above embodiments are illustrative of the present
invention, but are not intended to limit its scope. Numerous
modifications and alternative arrangements may be devised by those
skilled in the art without departing from the spirit and scope of
the present invention, and the appended claims are intended to
cover such modifications and arrangements.
* * * * *