U.S. patent application number 11/130727 was filed with the patent office on 2005-09-29 for guidewire apparatus for temporary distal embolic protection.
This patent application is currently assigned to Medtronic Vascular, Inc.. Invention is credited to Douk, Nareak, Jennings, Ellen M., Poole, Matt S., Rafiee, Nasser, Strickler, Peter G..
Application Number | 20050216053 11/130727 |
Document ID | / |
Family ID | 27765448 |
Filed Date | 2005-09-29 |
United States Patent
Application |
20050216053 |
Kind Code |
A1 |
Douk, Nareak ; et
al. |
September 29, 2005 |
Guidewire apparatus for temporary distal embolic protection
Abstract
A guidewire apparatus for use during percutaneous catheter
interventions, such as angioplasty or stent deployment. A
protection element comprising a filter or an occluder is mounted
near the distal end of a steerable guidewire, which guides a
therapeutic catheter. The guidewire apparatus comprises a hollow
shaft movably disposed about a core wire and, optionally, a
slippery liner interfitted there between. The shaft and core wire
control relative displacement of the ends of the protection
element, causing transformation of the protection element between a
deployed configuration and a collapsed configuration.
Inventors: |
Douk, Nareak; (Lowell,
MA) ; Rafiee, Nasser; (Andover, MA) ;
Strickler, Peter G.; (Tewksbury, MA) ; Poole, Matt
S.; (Bradford, MA) ; Jennings, Ellen M.;
(Danvers, MA) |
Correspondence
Address: |
MEDTRONIC VASCULAR, INC.
IP LEGAL DEPARTMENT
3576 UNOCAL PLACE
SANTA ROSA
CA
95403
US
|
Assignee: |
Medtronic Vascular, Inc.
Santa Rosa
CA
|
Family ID: |
27765448 |
Appl. No.: |
11/130727 |
Filed: |
May 17, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11130727 |
May 17, 2005 |
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10099399 |
Mar 15, 2002 |
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6911036 |
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10099399 |
Mar 15, 2002 |
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09918441 |
Jul 27, 2001 |
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6818006 |
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09918441 |
Jul 27, 2001 |
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09824832 |
Apr 3, 2001 |
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6866677 |
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Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61B 17/12109 20130101;
A61M 25/09 20130101; A61M 2025/1015 20130101; A61F 2/011 20200501;
A61F 2230/0067 20130101; A61B 17/12172 20130101; A61F 2230/0006
20130101; A61M 25/09025 20130101; A61M 2025/09183 20130101; A61F
2002/018 20130101; A61B 2017/22038 20130101; A61B 17/12022
20130101; A61B 17/1204 20130101; A61F 2002/015 20130101; A61M
2025/09008 20130101; A61F 2/013 20130101; A61F 2230/0071 20130101;
A61B 2017/1205 20130101; A61B 2017/22045 20130101 |
Class at
Publication: |
606/200 |
International
Class: |
A61M 029/00 |
Claims
1-13. (canceled)
14. The guidewire apparatus of claim 47, wherein the
torque-transmitting element is a filamentous tube having proximal
and distal ends and a variable length to permit longitudinal
displacement between the shaft and the core wire, the tube disposed
about the core wire distal end at a location extending from the
shaft distal end towards the tip member, the tube proximal end
being fixed to the shaft distal end and the tube distal end fixedly
connected to a proximal end of the tip member.
15. The guidewire apparatus of claim 47, wherein the
torque-transmitting element is a filamentous tube having proximal
and distal ends and a variable length to permit longitudinal
displacement between the shaft and the core wire, the tube disposed
about the core wire distal end at a location extending from the
shaft distal end towards the tip member, the tube proximal end
being fixed to the shaft distal end and the tube distal end fixedly
connected to the core wire adjacent to a proximal end of the tip
member.
16. The guidewire apparatus of claim 47, wherein the
torque-transmitting element comprises a flat formed on the core
wire and a corresponding dimple formed in the hollow shaft, the
dimple being slidingly engaged with the flat to permit longitudinal
displacement between the shaft and the core wire, the dimple being
keyed with the flat for transmitting rotation forces from the
hollow shaft to the core wire.
17-46. (canceled)
47. A guidewire apparatus comprising: an elongate hollow shaft
having an inner wall and proximal and distal ends; a core wire
movably disposed within the shaft and having a distal end extending
there from; a torque-transmitting element capable of transmitting
rotation force from the hollow shaft to the core wire; a flexible
tip member fixed about the core wire distal end, and a generally
tubular protection element having a distal end coupled to the tip
member and a proximal end coupled adjacent the shaft distal end,
wherein relative longitudinal movement between the distal and
proximal ends of the protection element accompanies a
transformation of the protection element between a collapsed
configuration and an expanded configuration.
48. The guidewire apparatus of claim 47, further comprising: a
liner interfitted between the core wire and the shaft inner wall,
the liner having an inner surface and an outer surface, wherein at
least one of the surfaces has a low coefficient of friction.
49. The guidewire apparatus of claim 47, further comprising: a
transition sleeve being slidably disposed about the shaft distal
end and extending distally there from such that a sleeve distal end
surrounds and couples with a proximal portion of the tip member,
wherein the tubular protection element distal end is fixed to the
transition sleeve.
50. The guidewire apparatus of claim 49 wherein the transition
sleeve distal end is fixedly coupled with the tip member proximal
portion.
51. The guidewire apparatus of claim 49 wherein the sleeve distal
end is slidingly coupled about the tip member and restrained by
stop members from sliding proximally off of the tip member.
52. The guidewire apparatus of claim 47 wherein the protection
element is a filter.
53. The guidewire apparatus of claim 47 wherein the protection
element is an occluder.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This patent application is a continuation-in-part of U.S.
patent application Ser. No. 09/918,441 to Douk et al. filed Jul.
27, 2001, which is a continuation-in-part of U.S. patent
application Ser. No. 09/824,832 to Douk et al. filed Apr. 3, 2001
entitled "Temporary Intraluminal Filter Guidewire and Methods of
Use."
FIELD OF THE INVENTION
[0002] The present invention relates generally to intraluminal
devices for capturing particulate in the vessels of a patient. More
particularly, the invention relates to a filter or an occluder for
capturing emboli in a blood vessel during an interventional
vascular procedure, then removing the captured emboli from the
patient after completion of the procedure. Furthermore, the
invention concerns a filter or an occluder mounted on a guidewire
that can also be used to direct an interventional catheter to a
treatment site within a patient.
BACKGROUND OF THE INVENTION
[0003] A variety of treatments exists for dilating or removing
atherosclerotic plaque in blood vessels. The use of an angioplasty
balloon catheter is common in the art as a minimally invasive
treatment to enlarge a stenotic or diseased blood vessel. When
applied to the vessels of the heart, this treatment is known as
percutaneous transluminal coronary angioplasty, or PTCA. To provide
radial support to the treated vessel in order to prolong the
positive effects of PTCA, a stent may be implanted in conjunction
with the procedure.
[0004] Thrombectomy is a minimally invasive technique for removal
of an entire thrombus or a sufficient portion of the thrombus to
enlarge the stenotic or diseased blood vessel and may be
accomplished instead of a PTCA procedure. Atherectomy is another
well-known minimally invasive procedure that mechanically cuts or
abrades a stenosis within the diseased portion of the vessel.
Alternatively, ablation therapies use laser or RF signals to
superheat or vaporize a thrombus within the vessel. Emboli loosened
during such procedures may be removed from the patient through the
catheter.
[0005] During each of these procedures, there is a risk that emboli
dislodged by the procedure will migrate through the circulatory
system and cause ischaemic events, such as infarction or stroke.
Thus, practitioners have approached prevention of escaped emboli
through use of occlusion devices, filters, lysing, and aspiration
techniques. For example, it is known to remove the embolic material
by suction through an aspiration lumen in the treatment catheter or
by capturing emboli in a filter or occlusion device positioned
distal of the treatment area.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Features, aspects and advantages of the present invention
will become better understood with reference to the following
description, appended claims, and accompanying drawings where:
[0007] FIG. 1 is an illustration of a filter system in accordance
with the invention deployed within a blood vessel;
[0008] FIG. 2 is an illustration of a filter system in accordance
with the invention deployed within a portion of the coronary
arterial anatomy;
[0009] FIG. 3 is an illustration of a prior art expandable mesh
device, shown with the mesh in a collapsed configuration;
[0010] FIG. 4 is an illustration of a prior art expandable mesh
device, shown with the mesh in a deployed configuration;
[0011] FIG. 5 is a longitudinal sectional view of a first guidewire
embodiment in accordance with the invention;
[0012] FIG. 6 is a longitudinal sectional view of a second
guidewire embodiment in accordance with the invention;
[0013] FIG. 7 is a cross-sectional view of the second guidewire
embodiment taken along the lines 7-7 of FIG. 6;
[0014] FIG. 8 is a modified form of the cross-sectional view shown
in FIG. 7;
[0015] FIG. 9 is another modified form of the cross-sectional view
shown in FIG. 7;
[0016] FIG. 10 is an enlarged supplementary view of a portion of
FIG. 8, which has been modified to illustrate alternative
embodiments of the invention;
[0017] FIG. 11 is a longitudinal sectional view of a segment of a
hollow shaft and liner in accordance with the invention;
[0018] FIG. 12 is a partially sectioned longitudinal view of a
third guidewire embodiment in accordance with the invention;
and
[0019] FIG. 13 is a partially sectioned longitudinal view of a
fourth guidewire embodiment in accordance with the invention;
[0020] FIG. 14 is a alternative form of the fourth guidewire
embodiment shown in FIG. 13.
SUMMARY OF THE INVENTION
[0021] The guidewire apparatus of the invention includes a
protection element comprising a filter or an occluder mounted near
the distal end of a steerable guidewire, which guides a therapeutic
catheter. The guidewire apparatus comprises a hollow shaft movably
disposed about a core wire and, optionally, a slippery liner
interfitted there between. The shaft and core wire control relative
displacement of the ends of the protection element, causing
transformation of the protection element between a deployed
configuration and a collapsed configuration.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The present invention is a guidewire apparatus for use in
minimally invasive procedures. While the following description of
the invention relates to vascular interventions, it is to be
understood that the invention is applicable to other procedures
where the practitioner desires to capture embolic material that may
be dislodged during the procedure. Intravascular procedures such as
PTCA or stent deployment are often preferable to more invasive
surgical techniques in the treatment of vascular narrowings, called
stenoses or lesions. With reference to FIGS. 1 and 2, deployment of
balloon expandable stent 5 is accomplished by threading catheter 10
through the vascular system of the patient until stent 5 is located
within a stenosis at predetermined treatment site 15. Once
positioned, balloon 11 of catheter 10 is inflated to expand stent 5
against the vascular wall to maintain the opening. Stent deployment
can be performed following treatments such as angioplasty, or
during initial balloon dilation of the treatment site, which is
referred to as primary stenting.
[0023] Catheter 10 is typically guided to treatment site 15 by a
guidewire. In cases where the target stenosis is located in
tortuous vessels that are remote from the vascular access point,
such as coronary arteries 17 shown in FIG. 2, a steerable guidewire
is commonly used. According to the present invention, a guidewire
apparatus generally guides catheter 10 to treatment site 15 and
includes a distally disposed protection element to collect embolic
debris that may be generated during the procedure. Various
embodiments of the invention will be described as either filter
guidewires or occluder guidewires. However, it is to be understood
that filters and occluders are interchangeable types of protection
elements among the inventive structures disclosed. The invention is
directed to embolic protection elements wherein relative movement
of the ends of the protection element either causes or accompanies
transformation of the element between a collapsed configuration and
an expanded, or deployed configuration. Such transformation may be
impelled by external mechanical means or by self-shaping memory
(either self-expanding or self-collapsing) within the protection
element itself The protection element may be self-expanding,
meaning that it has a mechanical memory to return to the expanded,
or deployed configuration. Such mechanical memory can be imparted
to the metal comprising the element by thermal treatment to achieve
a spring temper in stainless steel, for example, or to set a shape
memory in a susceptible metal alloy such as a nickel-titanium
(nitinol) alloy.
[0024] Filter guidewires in accordance with the invention include
distally disposed filter 25, which may comprise a tube formed by
braided filaments that define pores and have at least one
proximally-facing inlet opening 66 that is substantially larger
than the pores. Alternative types of filters may be used in filter
25, such as filter assemblies that include a porous mesh mounted to
expandable struts. Optionally, adding radiopaque markers to filter
ends 27, 29, as shown in FIG. 12, can aid in fluoroscopic
observation of filter 25 during manipulation thereof.
Alternatively, to enhance visualization of braided filter 25 under
fluoroscopy, at least one of the filaments may be a wire having
enhanced radiopacity compared to conventional non-radiopaque wires
suitable for braiding filter 25. At least the majority of braiding
wires forming filter 25 should be capable of being heat set into
the desired filter shape, and such wires should also have
sufficient elastic properties to provide the desired self-expanding
or self-collapsing features. Stainless steel and nitinol
monofilaments are suitable for braiding filter 25. A braiding wire
having enhanced radiopacity may be made of, or coated with, a
radiopaque metal such as gold, platinum, tungsten, alloys thereof,
or other biocompatible metals that, compared with stainless steel
or nitinol, have a relatively high X-ray attenuation coefficient.
One or more filaments having enhanced radiopacity may be
inter-woven with non-radiopaque wires, or all wires comprising
filter 25 may have the same enhanced radiopacity.
[0025] In accordance with the invention, maintaining filter 25 in a
collapsed configuration during introduction and withdrawal of
filter guidewire 20 does not require a control sheath that
slidingly envelops filter 25. Thus, this type of device is
sometimes termed as "sheathless." Known types of sheathless
vascular filter devices are operated by a push-pull mechanism that
is also typical of other expandable braid devices, as shown in
FIGS. 3 and 4. Prior art expandable mesh device 30 includes core
wire 32 and hollow shaft 34 movably disposed there about. Tubular
mesh, or braid 36 surrounds core wire 32 and has a braid distal end
fixed to core wire distal end 40 and a braid proximal end fixed to
shaft distal end 41. To expand braid 36, core wire 32 is pulled and
shaft 34 is pushed, as shown by arrows 37 and 39 respectively in
FIG. 4. The relative displacement of core wire 32 and shaft 34
moves the ends of braid 36 towards each other, forcing the middle
region of braid 36 to expand. To collapse braid 36, core wire 32 is
pushed and shaft 34 is pulled, as shown by arrows 33 and 35
respectively in FIG. 3. This reverse manipulation draws the ends of
braid 36 apart, pulling the middle region of braid 36 radially
inward toward core wire 32.
[0026] Referring now to FIG. 5, in a first embodiment of the
invention, filter guidewire 20 includes core wire 42 and flexible
tubular tip member 43, such as a coil spring, fixed around the
distal end of core wire 42. Thin wires made from stainless steel
and/or one of various alloys of platinum are commonly used to make
coil springs for such use in guidewires. Core wire 42 can be made
from shape memory metal such as nitinol, or a stainless steel wire,
and is typically tapered at its distal end. For treating small
caliber vessels such as coronary arteries, core wire 42 may measure
about 0.15 mm (0.006 inch) in diameter.
[0027] In filter guidewire 20, hollow shaft 44 is movably disposed
around core wire 42, and includes relatively stiff proximal portion
46 and relatively flexible distal portion 48. Proximal portion 46
may be made from thin walled stainless steel tubing, usually
referred to as hypo tubing, although other metals, such as nitinol,
can be used. Various metals or polymers can be used to make
relatively flexible distal portion 48. One appropriate material for
this element is thermoset polyimide (PI) tubing, available from
sources such as HV Technologies, Inc., Trenton, Ga., U.S.A. The
length of distal portion 48 may be selected as appropriate for the
intended use of the filter guidewire. In one example, portion 48
may be designed and intended to be flexible enough to negotiate
tortuous coronary arteries, in which case the length of portion 48
may be 15-35 cm (5.9-13.8 inches), or at least approximately 25 cm
(9.8 inches). In comparison to treatment of coronary vessels,
adaptations of the invention for treatment of renal arteries may
require a relatively shorter flexible portion 48, and neurovascular
versions intended for approaching vessels in the head and neck may
require a relatively longer flexible portion 48.
[0028] When filter guidewire 20 is designed for use in small
vessels, shaft 44 may have an outer diameter of about 0.36 mm
(0.014 inch). The general uniformity of the outer diameter may be
maintained by connecting proximal portion 46 and distal portion 48
with lap joint 49. Lap joint 49 may use any suitable adhesive such
as cyanoacrylate instant adhesives from Loctite Corporation, Rocky
Hill, Conn., U.S.A., or Dymax Corporation, Torrington, Conn.,
U.S.A. Lap joint 49 can be formed by any conventional method such
as reducing the wall thickness of proximal portion 46 in the region
of joint 49, or by forming a step-down in diameter at this location
with negligible change in wall thickness, as by swaging.
[0029] Expandable tubular filter 25 is positioned generally
concentrically with core wire 42, and is sized such that when it is
fully deployed, as shown in FIGS. 1 and 2, the outer perimeter of
filter 25 will contact the inner surface of the vessel wall. The
surface contact is maintained around the entire vessel lumen to
prevent any emboli from slipping past filter 25. Cyanoacrylate
adhesive may be used to secure filter distal end 27 to tip member
43, and to secure filter proximal end 29 near the distal end of
shaft 44. As shown in FIGS. 12 and 13, radiopaque marker bands,
such as platinum rings, can be incorporated into the adhesive
joints securing filter ends 27, 29 respectively to tip member 43
and shaft 44. Filter 25 is deployed by advancing, or pushing shaft
44 relative to core wire 42 such that filter distal and proximal
ends 27, 29 are drawn toward each other, forcing the middle, or
central section of filter 25 to expand radially. Filter 25 is
collapsed by withdrawing, or pulling shaft 44 relative to core wire
42 such that filter distal and proximal ends 27, 29 are drawn apart
from each other, forcing the middle, or central section of filter
25 to contract radially.
[0030] Transition sleeve 45 is fixed about core wire 42 and is
slidably located within the distal end of flexible distal portion
48 of hollow shaft 44. Transition sleeve 45 may be made of
polyimide tubing similar to that used in distal portion 48 and
extends distally there from. By partially filling the annular space
between core wire 42 and shaft 44, and by contributing additional
stiffness over its length, sleeve 45 supports core wire 42 and
provides a gradual transition in overall stiffness of filter
guidewire 20 adjacent the distal end of shaft 44. Transition sleeve
45 is fixed to core wire 42 with adhesive such as cyanoacrylate,
such that relative displacement between shaft 44 and core wire 42
causes corresponding relative displacement between shaft 44 and
sleeve 45. The length and mounting position of sleeve 45 are
selected such that sleeve 45 spans the distal end of shaft 44
regardless of the configuration of filter 25 and the corresponding
position of shaft 44 relative to core wire 42. When constructed as
described above, filter guidewire 20 provides the functions of a
temporary filter combined with the performance of a steerable
guidewire.
[0031] FIG. 6 depicts a second embodiment of the invention in which
filter guidewire 120 incorporates a number of elements similar to
the elements that make up filter guidewire 20. Such similar
elements will be identified with the same reference numerals
throughout the description of the invention. Filter guidewire 120
includes core wire 142 and flexible tubular tip member 43 fixed
around the distal end of core wire 142, similar to the arrangement
of guidewire 20, supra. Hollow shaft 144 is movably disposed around
core wire 142 and is comparable, throughout its length, to
relatively stiff proximal portion 46 of filter guidewire 20. Filter
25 is positioned generally concentrically with core wire 142.
Filter distal end 27 is fixedly coupled to tip member 43, and
filter proximal end 29 is fixedly coupled near the distal end of
shaft 144.
[0032] Optionally, a portion of core wire 142 within the proximal
end of shaft 144 has one or more bends 160 formed therein. The
amplitude, or maximal transverse dimension of bends 160 is selected
such that the bent portion of core wire 142 fits, with
interference, within shaft 144. The interference fit provides
sufficient friction to hold core wire 142 and shaft 144 in desired
axial positions relative to each other, thereby controlling the
shape of filter 25, as described supra with respect to filter
guidewire 20.
[0033] In filter guidewire 120, liner 145 is interfitted as a
low-friction axial bearing in the annular space between core wire
142 and shaft 144. With respect to the three coaxially arranged
elements, the selected dimensions and the stack-up of dimensional
tolerances will determine how liner 145 functions during the
push-pull operation of core wire 142 within shaft 144.
[0034] For example, FIG. 7 depicts a cross-section of filter
guidewire 120 in which there is radial clearance between liner
inner surface 150 and core wire 142, and there is also radial
clearance between liner outer surface 151 and the inner wall of
shaft 144. In this arrangement, liner 145 is radially free-floating
in the annular space between core wire 142 and shaft 144. The
length of liner 145 is selected such that it also "floats" axially
along core wire 142. The axial movement of liner 145 along core
wire 142 is limited proximally by a stop formed at the engagement
of bends 160 with the inner wall of shaft 144. Tip member 43 limits
the axial distal movement of liner 145 along core wire 142. The
radial and axial flotation of liner 145 in filter guidewire 120
provides an axial bearing wherein the components with the lesser
relative coefficient of friction can slide against each other. For
example, if the coefficient of friction between liner inner surface
150 and core wire 142 is less than the coefficient of friction
between liner outer surface 151 and the inner wall of shaft 144,
then liner 145 will remain longitudinally fixed within shaft 144,
and push-pull action will cause core wire 142 to slide within liner
145. Conversely, if the coefficient of friction between liner inner
surface 150 and core wire 142 is greater than the coefficient of
friction between liner outer surface 151 and the inner wall of
shaft 144, then liner 145 will remain longitudinally fixed about
core wire 142, and push-pull action will cause shaft 144 to slide
over liner 145. The relative coefficients of friction for the
movable components of the guidewire assembly may be designed-in by
selection of materials and/or coatings, as will be described infra.
Alternatively, the degree of sliding friction may result from
unplanned events, such as the formation of thrombus on one or more
component surfaces or embolic debris entering the annular space(s)
there between.
[0035] FIG. 8 depicts a modified form of the cross-sectional view
shown in FIG. 7 in which liner 145' is fitted against the inner
wall of shaft 144, leaving radial clearance only between liner
inner surface 150' and core wire 142. FIG. 9 depicts another
modified form of the cross-sectional view shown in FIG. 7 in which
liner 145" is fitted against core wire 142, leaving radial
clearance only between liner outer surface 151' and the inner wall
of shaft 144.
[0036] When filter guidewire 120 is designed for use in small
vessels, shaft 144 may have an outer diameter of about 0.36 mm
(0.014 inch), and core wire 142 may measure about 0.15 mm (0.006
inch) in diameter. Shaft 144, which can be made from hypo tubing,
may have an inside diameter of about 0.23 mm (0.009 inch). For
liner 145 to "float" in an annular space between core wire 142 and
shaft 144 with such dimensions, liner outer surface 151 may measure
about 0.22 mm (0.0088 inch) in diameter and liner inner surface 150
may measure about 0.18 mm (0.0069 inch) in diameter. Liner 145'
does not require clearance around its outside diameter, because it
is fitted against the inner wall of shaft 144. As compared to liner
145, liner 145' may have a greater wall thickness, and liner inner
surface 150' may have a similar inner diameter of about 0.18 mm
(0.0069 inch). Liner 145" does not require inside clearance because
it is fitted against core wire 142. As compared to liner 145, liner
145" may also have greater wall thickness, and liner outer surface
151' may have a similar outer diameter of about 0.22 mm (0.0088
inch).
[0037] Liners 145, 145' and 145" may be formed of polymers selected
to provide low coefficients of friction on their sliding surfaces.
Typical of such polymers are polytetrafluoroethylene (PTFE),
fluorinated ethylene-propylene (FEP), high-density polyethylene
(HDPE), and various polyamides (nylons). Alternatively, liners 145,
145' and 145" may be formed of a material selected for physical
properties other than a low coefficient of friction, i.e. stiffness
or ability to be formed with tight dimensional tolerances. For such
materials, a slippery coating, such as silicone, may be applied to
the sliding surface(s) in order to achieve the desired low-friction
axial bearing properties.
[0038] Thermoset polyimide (PI) is an example of a liner material
that may be selected for properties other than its coefficient of
friction. PI tubing is noted for its ability to be formed with
tight dimensional tolerances because it is typically formed by
building up several layers of cured PI coating around a solid glass
core, which is removed by chemical etching. One method of creating
a slippery surface on PI tubing is to add a fluoropolymer filler,
such as PTFE or FEP, to the PI coating to form one or more
low-friction layers at the desired surface(s). Such
polyimide/fluoropolymer composite tubing is available from
MicroLumen, Inc., Tampa, Fla., U.S.A. FIG. 10 illustrates a
modified form of the invention wherein the inner surface of liner
145' comprises lubricious coating 150'. Also shown in FIG. 10 is
slippery coating 155, which may be applied to core wire 142 in
conjunction with, or instead of, a slippery inner surface of liners
145 or 145'. Coating 155 may comprise a thin film of, for example,
silicone or a fluoropolymer.
[0039] Another example of a liner material that may be selected for
properties other than its coefficient of friction is a block
copolymer thermoplastic such as polyethylene block amide (PEBA).
Although a slippery coating may be applied to this material,
alternatively, its coefficient of friction may be reduced by
polymerizing the surface with plasma. Plasma-aided surface
functionalization to achieve high lubricity is described in U.S.
Pat. No. 4,693,799 (Yanagihara et al.), and plasma surface
modification is available from AST Products, Inc., Billerica,
Mass., U.S.A. Plasma treated PEBA may be substituted for PTFE in
liners to make use of improved physical properties, including the
ability to be plastically extruded.
[0040] FIG. 11 depicts a variant of liner 145' disposed within
hollow shaft 144. In this example, liner 145' comprises a coiled
filament, which may be plastic, metal, or coated or surface-treated
forms of either material. The coiled variant may be applied to any
of liners 145, 145' or 145", and it provides reduced contact area
and concomitantly lower friction as compared to solid tubular
liners. Hollow tube 144 and core wire 142 will only touch coiled
liner 145' on helical curvilinear portions of the outer and inner
surfaces, respectively. If coiled liner 145' is made with an outer
diameter larger than the inner diameter of hollow tube 144, then
liner 145' will generally hold itself in assembled position against
the inner diameter of hollow tube 144. Similarly, if liner 145" is
made as a coil with an inner diameter smaller than the diameter of
core wire 142, then liner 145" will generally hold itself in
assembled position around core wire 142.
[0041] FIG. 12 depicts a third embodiment of the invention in which
filter guidewire 220 incorporates several elements that are similar
to the components of filter guidewires 20 and 120. Core wire 242 is
disposed within liner 145, which is disposed within hollow shaft
144. Core wire 242 is comprised of proximal section 256 and
separate distal section 258, which extends distally from shaft 144.
Sliding clearance(s) may be formed between different elongate
movable components, as described supra and as shown in FIGS. 7, 8
and 9. If liner 145 is fitted against core wire 242, as shown in
FIG. 9, then liner 145 will comprise separate proximal and distal
sections (not shown) corresponding to core wire proximal section
256 and core wire distal section 258. Flexible tubular tip member
43 is fixed around the distal end of core wire distal section 258.
Transition sleeve 270 is slidably disposed about a distal portion
of hollow shaft 144 and extends distally there from to a fixed
coupling location on tip member 43. Filter 25 is self-expanding and
is positioned generally concentrically with the distal portion of
shaft 144. Filter distal end 27 is fixedly coupled to transition
sleeve 270, and filter proximal end 29 is fixedly coupled to shaft
144 adjacent the distal portion thereof.
[0042] Prior to negotiating vascular anatomy with filter guidewire
220, filter 25 may be collapsed by advancing core wire proximal
section 256 within shaft 144 and liner 145 until the distal end of
proximal section 256 abuts the proximal end of distal section 258,
forming continuous core wire 242. Continued advancement of core
wire 242 through shaft 144 and liner 145 will displace tip member
43 distally away from shaft 144. The axial translation of tip
member 43 will draw sleeve 270 distally along, but not off of, the
distal portion of hollow shaft 144. The relative longitudinal
movement of sleeve 270 with respect to shaft 144 causes filter
distal end 27 to move away from filter proximal end 29,
transforming filter 25 from its expanded configuration to its
collapsed configuration. Optionally, filter guidewire 220 may
include bends 160 in core wire proximal section 256 (not shown) to
provide frictional engagement between core wire 242 and the
proximal end of shaft 144. As described supra, the optional
friction mechanism thus created can hold core wire 242 in a
selected axial position within shaft 144, thereby retaining filter
25 in the collapsed configuration.
[0043] Withdrawing core wire proximal section 256 proximally
through shaft 144 and liner 145 allows filter 25 to transform
itself towards the expanded configuration by drawing filter ends
27, 29 closer together. The self-transformation of filter 25
towards the expanded configuration causes simultaneous proximal
movement of sleeve 270, tip member 43 and core wire distal section
258 relative to shaft 144. The self-expansion of filter 25 stops
when a) filter 25 reaches its pre-formed expanded configuration,
orb) filter 25 encounters a radial constraint, such as apposition
with a vessel wall in a patient, or c) filter 25 encounters an
axial constraint, such as the proximal end of sleeve 270 contacting
filter proximal end 29, as depicted in FIG. 12. After
self-expansion of filter 25 has stopped, any further withdrawal of
core wire proximal section 256 will cause it to separate from core
wire distal section 258, thereby allowing core wire distal section
258, tip member 43, and sleeve 270 to move freely with respect to
the distal end of hollow shaft 144. In this configuration, core
wire proximal section 256 will not interfere with self-expansion or
self-adjustment of filter 25 in its apposition with the vessel
wall.
[0044] Transition sleeve 270 may be made of polyimide tubing and
may be fixed to tip member 43 and to filter distal end 27 with
adhesive, such as cyanoacrylate. The length and mounting position
of sleeve 270 are selected such that sleeve 270 always surrounds
the distal end of shaft 144, regardless of the configuration and
length of filter 25. Sleeve 270 can support core wire 242 across
the longitudinal gap between the distal end of shaft 144 and the
proximal end of tip member 43. By contributing additional stiffness
over its length, sleeve 270 also provides a transition in overall
stiffness of filter guidewire 220 adjacent the distal end of shaft
144.
[0045] FIG. 13 depicts a fourth embodiment of the invention in
which occluder guidewire 320 incorporates several elements that are
similar to the components of filter guidewires 20, 120, and 220. As
distinguished from filter guidewire embodiments of the invention,
occluder guidewires are typically used to temporarily obstruct
fluid flow through the vessel being treated. Any embolic debris
trapped upstream of the occluder element may be aspirated using a
separate catheter, with or without irrigation of the area. Core
wire 342 is disposed within liner 145, which is disposed within
hollow shaft 144. Alternatively, liners 145' or 145" may be
substituted for liner 145 such that different sliding clearance(s)
may be formed between different elongate movable components, as
described supra and as shown in FIGS. 7, 8 and 9. Flexible tubular
tip member 43 is fixed around the distal end of core 342.
Transition sleeve 270 is slidably disposed about a distal portion
of hollow shaft 144 and extends distally there from to a sliding
coupling location on tip member 43. Stop 381 protrudes radially
outward from the proximal end of tip member 43, and stop 382
protrudes radially inward from the distal end of transition sleeve
270. Stops 381, 382 interact to prevent the distal end of
transition sleeve 270 from sliding proximally off of tip member 43.
Stop 381 may comprise a portion of tip member 43, such as one or
more enlarged turns at the proximal end of a coil spring.
Alternatively, stop 381 may be created with metal or plastic
elements, such as solder or polyimide bands. Stop 382 may comprise
a portion of transition sleeve 270, such as a rim or neck of
reduced diameter formed at the distal end thereof. Alternatively,
stop 382 may be created with metal or plastic elements, such as
polyimide bands.
[0046] Occluder 325 is self-expanding and is positioned generally
concentrically with the distal portion of shaft 144. Occluder 325
may comprise a tubular braid similar to filter 25, which is coated
with an elastic material to render it non-porous. Alternatively,
occluder 325 may include self-expanding struts (not shown) that
support a non-porous elastic membrane, as known to those of
ordinary skill in the art. A non-porous coating or membrane may be
made from a variety of elastic materials, such as silicone rubber
or a thermoplastic elastomer (TPE). Occluder distal end 327 is
fixedly coupled to transition sleeve 270, and occluder proximal end
329 is fixedly coupled to shaft 144 proximally adjacent the distal
portion thereof.
[0047] In occluder guidewire 320, occluder 325 may be collapsed by
advancing core wire 342 through shaft 144 and liner 145, causing
tip member 43 to translate within transition sleeve 270 until stop
381 engages stop 382, as shown in FIG. 13. Continued advancement of
core wire 342 through shaft 144 and liner 145 will displace tip
member 43 distally from shaft 144, drawing sleeve 270 along, but
not off of, the distal portion of hollow shaft 144. The relative
longitudinal movement of sleeve 270 with respect to shaft 144
causes occluder distal end 327 to move away from occluder proximal
end 329, which transforms occluder 325 from its expanded
configuration to its collapsed configuration. Reversing the above
manipulation, i.e. drawing core wire 342 proximally through shaft
144 and liner 145, permits occluder 325 to expand itself.
Self-expansion of occluder 325 will stop when one of several
conditions is met, as described above with respect to
self-expanding filter 25 of filter guidewire 220. Thereafter,
continued withdrawal of core wire 342 will draw tip member 43
proximally within transition sleeve 270, creating axial separation
(not shown) between stops 381, 382, thereby allowing the distal end
of transition sleeve 270, with stop 382, to slide freely along tip
member 43. In this configuration, core wire 342 and tip member 43
will not interfere with self-expansion or self-adjustment of
occluder 325 in its apposition with the vessel wall.
[0048] FIG. 13 illustrates the portion of core wire 342 within
hollow shaft 144 having a first proximal segment 390, which also
extends proximally from hollow shaft 144. First proximal segment
390 is sized to fit slidingly within hollow shaft 144, but without
sufficient radial clearance for liners 145, 145' or 145". First
proximal segment 390 may comprise a major length of core wire 342,
such that relatively short core wire distal segment 391 is
dimensioned to receive liners 145, 145' or 145". For example, if
occluder guidewire 320 is designed for use in coronary arteries,
then the overall length of core wire 342 may be about 175 cm, and
the length of core wire distal segment 391 may be about 15 to 25
cm. Alternatively, first proximal segment 390 may have a relatively
short length such that core wire distal segment 391 and surrounding
liners 145, 145' or 145" extend through a major length of hollow
shaft 144.
[0049] The transition in diameter between core wire distal segment
391 and first proximal segment 390 may occur as step 398, which can
limit the proximal slippage of free-floating liner 145 along core
wire 342. Optionally, occluder guidewire 320 may exclude any liner
while still incorporating stepped diameter core wire 342 shown in
FIG. 13. In such an arrangement, the annular space that would
otherwise be occupied by a liner can provide enlarged clearance and
accompanying reduced friction between core wire 342 and hollow
shaft 144, especially when occluder guidewire 320 is curved through
tortuous anatomy. Core wire 342 may also optionally include bends
160 (not shown) located distal to first proximal segment 390.
[0050] In order to steer a distal protection guidewire in
accordance with the invention through tortuous vasculature, tip
member 43 is typically bent or curved prior to insertion of the
device, which should transmit to tip member 43 substantially all of
the rotation, or torque applied by the clinician at the proximal
end of the device. It is most convenient for the physician to steer
the device by grasping and rotating shaft 144, and having such
rotation imparted to tip member 43, either directly or through the
core wire. In distal protection guidewires of the instant
invention, various design features reduce longitudinal friction
between the hollow shaft and the core wire. These same
friction-reducing features also reduce rotational friction between
the hollow shaft and the core wire, which would otherwise be useful
in transmitting rotation to steer the device. In filter guidewires
20, 120 and 220, torque is transmissible from shaft 144 to tip
member 43 through the braided structure of filter 25, however this
action is generally effective only when filter 25 is in the
collapsed configuration. In occluder guidewire 320, occluder distal
end 327 is slidably connected to tip member 43 through transition
sleeve 270 such that torque cannot be transmitted from shaft 144 to
tip member 43 through occluder 325.
[0051] It is therefore advantageous, as shown in occluder guidewire
320, to include a torque-transmitting element, such as torque
member 384. Torque member 384 can comprise metal or plastic
filaments that form a hollow tube of counter wound spirals or a
braid. To minimize bulk and stiffness, torque member 384 may
include only a single filament in each of the clockwise and counter
clockwise winding directions. The proximal end of torque member 384
is bonded to the distal end of shaft 144 and extends distally there
from to surround core wire 342 over a relatively short distance.
The distal end of torque member 384 is bonded to the proximal end
of tip member 43, or to core wire 342 adjacent thereto. The
braided, or spirally wound tubular structure of torque member 384
permits it to transmit rotation forces between shaft 144 and tip
member 43, and to do so at any length required to accommodate
longitudinal displacement of shaft 144 and tip member 43 during
transformation of occluder element 325 between a collapsed
configuration and an expanded configuration.
[0052] FIG. 14 illustrates occluder guidewire 320', which
incorporates an alternative torque-transmitting element. Core wire
distal segment 391' includes flat 386, as may be formed thereon by
grinding. Dimple 388 is formed in shaft 144', as by controlled
crimping, to extend through an opening in liner 145 and to slidably
engage flat 386. Dimple 388 permits limited longitudinal
displacement of shaft 144' and core wire 342' during transformation
of occluder element 325 between a collapsed configuration and an
expanded configuration. Dimple 388 engages with flat 386 to perform
as a key and keyway arrangement, transmitting rotation between
shaft 144' and core wire 342'.
[0053] In occluder guidewire 320, second proximal segment 392 is
located proximally of first proximal segment 390 and has an
enlarged diameter approximating the outer diameter of shaft 144.
Reinforcement coil 396 surrounds first proximal segment 390 between
second proximal segment 392 and the proximal end of hollow shaft
144. Coil 396 has about the same outer diameter as shaft 144, and
helps prevent kinking of the portion of first proximal segment 390
that extends from hollow shaft 144. Alternatively, FIG. 14 shows
reinforcement coil 396', which is formed as an integral, spirally
cut section at the proximal end of shaft 144'. The proximal end of
reinforcement coil 396' is bonded to first proximal segment 390, as
by adhesive or solder, to effectively form second proximal segment
392. Reinforcement coils 396 and 396' can vary in length to
accommodate longitudinal displacement of shaft 144' and core wire
342' during transformation of occluder element 325 between a
collapsed configuration and an expanded configuration.
[0054] Third proximal segment 394 is located proximally of second
proximal segment 392 and is adapted for engagement to a guidewire
extension (not shown), as is well known to those of ordinary skill
in the art of guidewires. Examples of guidewire extensions usable
with occluder guidewire 320 and other embodiments of the invention
are shown in U.S. Pat. No. 4,827,941 (Taylor), U.S. Pat. No.
5,113,872 (Jahrmarkt et al.) and U.S. Pat. No. 5,133,364 (Palermo
et al.)
[0055] To adjust and maintain the relative longitudinal and/or
rotational positions of core wires and the surrounding hollow
shafts in the various embodiments of the invention, a removable
handle device (not shown) of a type familiar to those of skill in
the art may be used. Such handle devices can have telescoping
shafts with collet-type clamps that grip respectively the core
wires and shafts in the various embodiments of guidewire
apparatuses according to the present invention. The handle device
can also serve as a steering handle, or "torquer" which is useful
for rotating steerable-type guidewires that are incorporated in the
instant invention.
[0056] A method of using of a guidewire apparatus of the invention
is described as follows. It should be noted that the example
described infra is unnecessarily limited to a filter guidewire
embodiment. Filter guidewire 20, having self-expanding filter 25
and hollow shaft 44 is provided, and advancing core wire 62 through
shaft 44 collapses filter 25. With filter 25 in the collapsed
configuration, filter guidewire 20 is advanced into the patient's
vasculature until filter 25 is beyond intended treatment site 15.
Withdrawal of core wire 62 allows filter 25 to expand. With filter
25 deployed into contact with the vessel wall, a therapeutic
catheter is advanced over filter guidewire 20 to treatment site 15,
and therapy, such as balloon angioplasty, is performed. Any embolic
debris generated during the therapy is captured in filter 25. After
the therapy is completed, the therapeutic catheter is prepared for
withdrawal, as by deflating the balloon, if so equipped. Advancing
core wire 62 through shaft 44 collapses filter 25. Finally, filter
guidewire 20 and the therapeutic catheter can be withdrawn
separately or together, along with collected embolic debris
contained within filter 25. If an occluder guidewire of the
invention were substituted for a filter guidewire in the
above-described method, then aspiration of trapped embolic material
would be performed with a separate catheter before collapsing the
occluder element.
[0057] One benefit of the structures of filter guidewires 20, 120
and 220 is that guidewire tip member 43 forms a fixed length tip of
the device, regardless of the configuration of filter 25.
Conversely, in occluder guidewire 320, the tip length changes as
occluder distal end 327 slides along tip member 43 during
transformation of occluder 325 between expanded and collapsed
configurations. The variable tip length of occluder guidewire 320
provides a short tip when occluder 325 is collapsed, but the tip
needs to lengthen distally of treatment site 15, if possible,
during expansion of occluder 325. During deployment of filter
guidewires 20, 120 and 220, the distal tip position of the device
can remain fixed relative to treatment site 15. This is
accomplished by the user holding core wires 42, 142 or 242 anchored
relative to the patient, while applying tension to shafts 44 or 144
in the proximal direction. Filter 25 can be maintained in a
collapsed configuration by a friction mechanism including bends
160, or by applying proximal tension to shafts 44, 144, thus
holding filter proximal end 29 apart from filter distal end 27.
Releasing the tension on shafts 44, 144, or advancing them
manually, allows filter 25 to expand by filter proximal end 29
translating distally towards filter distal end 27. During this
filter deployment, however, the distal tip does not need to move
relative to filter 25 or treatment area 15.
[0058] While the invention has been particularly shown and
described with reference to the preferred embodiments thereof, it
will be understood by those skilled in the art that various changes
in form and detail may be made there in without departing from the
spirit and scope of the invention. For example, the invention may
be used in any intravascular treatment utilizing a guidewire where
the possibility of loosening emboli may occur. Although the
description herein illustrates angioplasty and stent placement
procedures as significant applications, it should be understood
that the present invention is in no way limited to those
environments.
* * * * *