U.S. patent application number 11/654757 was filed with the patent office on 2007-07-05 for expandable emboli filter and thrombectomy device.
Invention is credited to David Hancock, Olin Palmer, Saypin Phonthalasa, William Stephen Tremulis, Larry Voss, Gary A. Walker.
Application Number | 20070156170 11/654757 |
Document ID | / |
Family ID | 27758019 |
Filed Date | 2007-07-05 |
United States Patent
Application |
20070156170 |
Kind Code |
A1 |
Hancock; David ; et
al. |
July 5, 2007 |
Expandable emboli filter and thrombectomy device
Abstract
Expandable emboli filter and thrombectomy devices adapted for
use with microcatheters to remove debris from blood vessels. The
devices embody expanded profiles that span the entirety of various
sized target vessels and thus are particularly effective in the
engagement of debris found in vessels.
Inventors: |
Hancock; David; (San
Francisco, CA) ; Tremulis; William Stephen; (Redwood
City, CA) ; Phonthalasa; Saypin; (San Francisco,
CA) ; Palmer; Olin; (Mountain View, CA) ;
Voss; Larry; (San Jose, CA) ; Walker; Gary A.;
(Fremont, CA) |
Correspondence
Address: |
FULWIDER PATTON LLP
HOWARD HUGHES CENTER
6060 CENTER DRIVE, TENTH FLOOR
LOS ANGELES
CA
90045
US
|
Family ID: |
27758019 |
Appl. No.: |
11/654757 |
Filed: |
January 18, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09768653 |
Jan 23, 2001 |
6610077 |
|
|
11654757 |
Jan 18, 2007 |
|
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|
Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61F 2230/0065 20130101;
A61F 2/013 20130101; A61F 2002/018 20130101; A61F 2230/0069
20130101; A61F 2230/0097 20130101; A61F 2230/008 20130101; A61F
2002/016 20130101 |
Class at
Publication: |
606/200 |
International
Class: |
A61M 29/00 20060101
A61M029/00 |
Claims
1-32. (canceled)
33. An embolic filtering device for capturing embolic debris from
the body fluid flowing in a body vessel, comprising: an elongate
member having a distal end portion; a loop extending from the
distal end portion of the elongate member, the loop being movable
between a pre-deployment collapsed position and a deployed expanded
position in which the loop assumes a specific per-formed shape; a
filter coupled to the loop; and a generally elongate microcatheter
having an internal bore, the microcatheter adapted to receive the
elongate member and at least a portion of the loop and filter
within the internal bore.
34. The embolic filtering device of claim 33 wherein the loop
expands at a generally perpendicular angle to the elongate member
when deployed from the microcatheter.
35. The embolic filtering device of claim 33, wherein the loop
assumes a generally circular pre-formed shape when placed in the
deployed expanded position.
36. The embolic filtering device of claim 33, wherein the loop is
self-expanding.
37. The embolic filtering device of claim 33, wherein the loop
assumes a generally circular pre-formed shape generally
perpendicular to the longitudinal axis of the elongate member when
placed in the deployed expanded position.
38. The embolic filtering device of claim 33, wherein the loop
assumes a generally circular pre-formed shape generally at an acute
or obtuse angle with perpendicular to the longitudinal axis of the
elongate member when placed in the deployed expanded position.
39. The embolic filtering device of claim 33, wherein the loop is
self-expanding and generally conforms to the shape of the inside
circumference of the body vessel.
40. The embolic filtering device of claim 37, wherein the elongate
member and microcatheter assume a position contacting the wall of
the body vessel when the loop is placed in the deployed expanded
position.
41. The embolic filtering device of claim 33, wherein the loop
expands the entirety of the circumference of the body vessel when
placed in the deployed expanded position.
42. The embolic filtering device of claim 33, the filter includes a
plurality of mini-loops, the mini-loops adapted for receiving a
portion of the loop.
43. The embolic filtering device of claim 33, the filter further
comprising a plurality of proximally extending members, the
proximally extending members adapted for receiving at least a
portion of the loop.
44. The embolic filtering device of claim 33, wherein the loop
expands the entirety of the circumference of the body vessel when
placed in the deployed expanded position.
45. An embolic filtering device for capturing embolic debris from
the body fluid flowing in a body vessel, comprising: an elongate
member having a distal end portion; a loop coupled to the distal
end portion of the elongate member, the loop being movable between
a pre-deployment collapsed position and a deployed expanded
position in which the loop assumes a specific per-formed shape; a
filter coupled to the loop; and a microcatheter having an internal
bore, the microcatheter adapted to receive the elongate member,
loop and filter within the internal bore, the microcatheter having
an small outer diameter which allows the microcatheter to remain in
the body vessel while the filter device.
46. The embolic filtering device of claim 45, wherein the loop
expands at a generally perpendicular angle to the elongate member
when deployed from the microcatheter.
47. The embolic filtering device of claim 45, wherein the loop
assumes a generally circular pre-formed shape when placed in the
deployed expanded position.
48. The embolic filtering device of claim 45, wherein the loop is
self-expanding.
49. The embolic filtering device of claim 45, wherein the loop
assumes a generally circular pre-formed shape generally
perpendicular to the longitudinal axis of the elongate member when
placed in the deployed expanded position.
50. The embolic filtering device of claim 45, wherein the loop
assumes a generally circular pre-formed shape generally at an acute
or obtuse angle with perpendicular to the longitudinal axis of the
elongate member when placed in the deployed expanded position.
51. The embolic filtering device of claim 45, wherein the
microcatheter is steerable into the body vessel.
52. A method for capturing embolic debris in the body fluid flowing
in a body vessel, comprising: providing a filtering device having
an elongate member having a distal end portion, a loop extending
from the distal end portion of the elongate member, the loop being
movable between a pre-deployment collapsed position and a deployed
expanded position in which the loop assumes a specific per-formed
shape, a filter coupled to the loop and a generally elongate
microcatheter having an internal bore, the microcatheter adapted to
receive the elongate member and at least a portion of the loop and
filter within the internal bore; introducing the filtering device
into the body vessel while the loop is restrained in the
pre-deployment collapsed position; placing the loop into the
deployed expanded position; filtering embolic debris from the body
fluid flowing in the body vessel; and moving the loop at least
partial back into the pre-deployment collapsed position; and
removing the filtering device from the body lumen.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to filtering and
thrombectomy devices and systems which can be used to capture
embolic material or thrombi found in blood vessels. The filtering
devices and systems of the present invention are particularly
useful when performing balloon angioplasty, stenting procedures,
laser angioplasty or atherectomy in critical vessels where the
release of embolic debris into the bloodstream can occlude the flow
of oxygenated blood to the brain or other vital organs, which can
cause devastating consequences to the patient. The thrombectomy
devices are suited for the removal of thrombus in a variety of
vessels. While the embolic filtering and thrombectomy devices and
systems of the present invention are particularly useful in the
cerebral vasculature and neurovasculature, the inventions can be
used in conjunction with any vascular interventional procedure in
which there is an embolic risk.
[0002] A variety of non-surgical interventional procedures have
been developed over the years for opening stenosed or occluded
blood vessels in a patient caused by the build up of plaque or
other substances on the wall of the blood vessel. Such procedures
usually involve the percutaneous introduction of the interventional
device into the lumen of the artery, usually through a catheter. In
typical PTA procedures, a guiding catheter or sheath is
percutaneously introduced into the cardiovascular system of a
patient through the femoral artery and advanced to near the target
vasculature. A guidewire and a dilatation catheter having a balloon
on the distal end are introduced through the guiding catheter with
the guidewire sliding within the dilatation catheter. The guidewire
is first advanced out of the guiding catheter into the patient's
vasculature and is directed across the arterial lesion. The
dilatation catheter is subsequently advanced over the previously
advanced guidewire until the dilatation balloon is properly
positioned across the arterial lesion. Once in position across the
lesion, the expandable balloon is inflated to a predetermined size
with a radiopaque liquid at relatively high pressures to radially
expand the atherosclerotic plaque of the lesion and thereby dilate
the lumen of the artery. The balloon is then deflated to a small
profile so that the dilatation catheter can be withdrawn from the
patient's vasculature and the blood flow resumed through the
dilated artery. As should be appreciated by those skilled in the
art, while the above-described procedure is typical, it is not the
only method used in angioplasty. Another procedure is laser
angioplasty which utilizes a laser to ablate the stenosis by super
heating and vaporizing the deposited plaque. Atherectomy is yet
another method of treating a stenosed blood vessel in which cutting
blades are rotated to shave the deposited plaque from the arterial
wall. A vacuum catheter is usually used to capture the shaved
plaque or thrombus from the blood stream during this procedure.
[0003] In the procedures of the kind referenced above, abrupt
reclosure may occur or restenosis of the artery may develop over
time, which may require another angioplasty procedure, a surgical
bypass operation, or some other method of repairing or
strengthening the area. To reduce the likelihood of the occurrence
of abrupt reclosure and to strengthen the area, a physician can
implant an intravascular prosthesis for maintaining vascular
patency, commonly known as a stent, inside the artery across the
lesion. The stent is crimped tightly onto the balloon portion of
the catheter and transported in its delivery diameter through the
patient's vasculature. At the deployment site, the stent is
expanded to a larger diameter, often by inflating the balloon
portion of the catheter.
[0004] Prior art stents typically fall into two general categories
of construction. The first type of stent is expandable upon
application of a controlled force, as described above, through the
inflation of the balloon portion of a dilatation catheter which,
upon inflation of the balloon or other expansion means, expands the
stent to a larger diameter to be left in place within the artery at
the target site. The second type of stent is a self-expanding stent
formed from, for example, shape memory metals or super-elastic
nickel-titanum (NiTi) alloys, which will automatically expand from
a compressed state when the stent is advanced out of the distal end
of the delivery catheter into the body lumen. Such stents
manufactured from expandable heat sensitive materials allow for
phase transformations of the material to occur, resulting in the
expansion and contraction of the stent.
[0005] The above minimally invasive interventional procedures, when
successful, avoid the necessity of major surgical operations.
However, there is one common problem which can become associated
with all of these types of procedures, namely, the potential
release of embolic debris into the bloodstream that can occlude
distal vasculature and cause significant health problems to the
patient. For example, during deployment of a stent, it is possible
that the metal struts of the stent can cut into the stenosis and
shear off pieces of plaque which become embolic debris that can
travel downstream and lodge somewhere in the patient's vascular
system. Pieces of plaque material can sometimes dislodge from the
stenosis during a balloon angioplasty procedure and become released
into the bloodstream. Additionally, while complete vaporization of
plaque is the intended goal during a laser angioplasty procedure,
quite often particles are not fully vaporized and thus enter the
bloodstream. Likewise, not all of the emboli created during an
atherectomy procedure may be drawn into the vacuum catheter and, as
a result, enter the bloodstream as well.
[0006] When any of the above-described procedures are performed in
the vessels supplying blood to the brain, the release of emboli
into the circulatory system can be extremely dangerous and
sometimes fatal to the patient. Naturally occurring debris can also
be highly dangerous to a patient. That is, debris which travels
through the blood vessel as a natural result of bodily functions or
disease states and not as a result of an intervention procedure.
Debris that is carried by the bloodstream to distal vessels of the
brain can cause these cerebral vessels to occlude, resulting in a
stroke, and in some cases, death. Therefore, although cerebral
percutaneous transluminal angioplasty has been performed in the
past, the number of procedures performed has been limited due to
the justifiable fear of causing an embolic stroke should embolic
debris enter the bloodstream and block vital downstream blood
passages.
[0007] Medical devices have been developed to attempt to deal with
the problem created when debris or fragments that naturally occur
or that enter the circulatory system following vessel treatment
utilizing any one of the above-identified procedures. One approach
which has been attempted is the cutting of any debris into minute
sizes which are unlikely to occlude major vessels within the
patient's vasculature. However, it is often difficult to control
the size of the fragments which are formed, and the potential risk
of vessel occlusion still exists, making such a procedure in the
carotid arteries a high-risk proposition.
[0008] Other techniques which have been developed to address the
problem of removing embolic debris include the use of catheters
with a vacuum source which provides temporary suction to remove
embolic debris from the bloodstream. However, as mentioned above,
there have been complications with such systems since the vacuum
catheter may not always remove all of the embolic material from the
bloodstream, and a powerful suction could injure the patient's
vasculature or remove more blood than is safe. Other techniques
which have had some limited success include the placement of a
filter or trap downstream from the treatment site to capture
embolic debris before it reaches the smaller blood vessels
downstream. However, there have been problems associated with
conventional filtering systems. In particular, certain previously
developed filtering devices do not optimize the area for embolic
collection. That is, conventional filtering devices may not present
a collection device that spans the entity of the vessel or it may
include supporting structure that itself impedes emboli collection.
Certain other devices are not effective when used in conjunction
with a microcatheter.
[0009] Moreover, thrombectomy and foreign matter removal devices
have been disclosed in the art. However, such devices have been
found to have structures which are either highly complex or lacking
in sufficient or effective expansion and retraction capabilities.
Disadvantages associated with the devices having highly complex
structure include difficulty in manufacturability as well as use in
conjunction with microcatheters. Other less complex devices can
pull through clots due to in part the lack of experience in using
the same, or lack an adequately fine mesh for capturing clots or
foreign bodies.
[0010] Furthermore, systems heretofore disclosed in the art are
generally limited by size compatibility and the increase in vessel
size as the emboli is drawn out from the distal vascular occlusion
location to a more proximal location. If the thrombectomy device is
too large for the vessel it will not deploy correctly to capture
the clot or foreign body, and if too small in diameter it cannot
capture thromboembolic material or foreign bodies across the entire
cross section of the blood vessel. Thus, a thrombectomy device that
can be expanded to a relatively large diameter from a relatively
small diameter is desirable as is the ability to effectively
control such expansion and contraction.
[0011] What has been needed is a reliable filtering or thrombectomy
device and system for use when treating blood vessels. The filter
devices should be capable of filtering any naturally occurring
embolic debris or that which may be released into the bloodstream
during an interventional treatment, while minimizing the area
occupied by structure supporting the filter so as to minimally
obstruct blood flow, and safely contain the debris until the
filtering device is removed from the patient's vasculature. The
thrombectomy devices should embody an expanded profile that
completely occupies the vessel at the repair site as well as
structure for effectively expanding and retracting the device.
Moreover, such devices should be relatively easy to deliver through
a microcatheter, as well as be deployed and removed from the
patient's vasculature and also should be capable of being used in
narrow and very distal vasculature such as the cerebral
vasculature. The following invention addresses these needs.
SUMMARY OF THE INVENTION
[0012] Briefly and in general terms, the present invention is
directed toward expandable devices for repairing blood vessels. The
expandable devices are particularly suited for removing emboli or
thrombi from the bloodstream of a human or animal. One significant
advantage provided by the present invention is the potential use of
the expandable devices in narrow and very distal vasculature.
[0013] In one aspect of the invention, there is provided a loop
with an embolic filter attached thereto. The loop is configured to
self-expand generally perpendicularly to and optionally offset to a
longitudinal axis of a delivery catheter. A tether is provided to
effect the deployment from and withdrawal into the delivery
catheter. The self-expandable loop and filter structure
advantageously expands to occupy the entire cross-section of the
lumen into which it is deployed. When the device is in its expanded
configuration, the shape of the loop is defined by the lumen and
the tether is positioned near a wall of the lumen.
[0014] In another aspect, the present invention includes multiple
loops that are connected by longitudinally extending fibers. The
connecting fibers may be crossing or non-crossing and may terminate
at a superior loop or continue distally to define a tapered distal
end. A catheter is provided for deploying the double loop device as
is a tether which effectuates the delivery and withdrawal of the
device. The multiple loops are intended to self-expand to occupy
the entirety of the cross-section of the blood vessel into which it
is deployed, the loops assuming the geometry of the vessel.
Additionally, when the device is in its expanded configuration, the
tether is intended to generally lie adjacent a wall defining the
lumen thereby accomplishing less blood flow obstruction. The distal
loops may also provide internal support for an embolic filter,
facilitating material entry into the filter.
[0015] In a third aspect of the invention, an embolectomy snare is
provided which has the advantage of being able to assume a very
small profile when packed within a delivery catheter. The
embolectomy snare is characterized by including a basket that is
formed from non-overlapping elongate members.
[0016] In a fourth aspect of the invention, improved expansion
control and a means for optimizing expansion profiles is
incorporated into a thrombectomy device. In particular, one or more
stops are provided on an elongate member to cause a basket-like
thrombectomy device configured coaxially about the elongate member
to thereby open and close the basket. By varying the weave pattern
of the basket of the thrombectomy device, upon expansion of the
same, a concavity can be formed, the same being particularly useful
for engaging and removing clots from a blood vessel.
[0017] These and other objects and advantages of the invention will
become apparent from the following more detailed description, when
taken in conjunction with the accompanying drawings of illustrative
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1A is a perspective view, partially in cross-section,
of an expandable device of the present invention in its deployed
configuration;
[0019] FIG. 1B is a perspective view, depicting a loop and an
expandable device that is integral with an elongate member;
[0020] FIG. 2A is a perspective view, partially in cross-section,
of an alternate embodiment of the present invention in its deployed
configuration;
[0021] FIG. 2B is a perspective view, depicting a loop configured
with mini-loops for spacing tethers;
[0022] FIG. 3 is a perspective view of another embodiment of an
expandable device of the present invention in its expanded
configuration;
[0023] FIG. 4A is a perspective view of yet another embodiment of
an expandable device of the present invention in its expanded
configuration;
[0024] FIG. 4B is a perspective view, depicting an expandable
device of the present invention with a medical loop;
[0025] FIG. 5A is a side view of an emboli snare of the present
invention shown in its expandable state;
[0026] FIG. 5B is a cross-sectional view taken along B-B of the
device shown in FIG. 5A;
[0027] FIG. 6 is a cross-sectional view of the device depicted in
FIG. 5A when withdrawn within a delivery catheter;
[0028] FIG. 7 is a side view of a thrombectomy device of the
present invention shown in its fully contracted configuration;
[0029] FIG. 8 is a side view of the device depicted in FIG. 7
advanced distally with respect to an elongate member;
[0030] FIG. 9 is a side view of the device depicted in FIG. 8 which
is further advanced distally and placed in an expanded
configuration; and
[0031] FIG. 10 is a side view of the device depicted in FIG. 9 in
its fully expanded configuration.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] Turning now to the drawings, and particularly to FIG. 1A,
there is shown an expandable device 20 of the present invention.
The expandable device 20 is suited for repairing vessels and in
particular, for capturing emboli 22 found in the bloodstream of a
patient. Due to its novel structure, the repair device 20 embodies
an expanded profile that is highly effective in filtering unwanted
material from vasculature and is capable of being deployed within
very narrow and distal vasculature, including the cerebral
vasculature.
[0033] In one presently preferred embodiment, the expandable device
20 includes a loop 24 attached by conventional means to a distal
end 26 of an elongate member 28. Attached to the loop 24 is an
emboli filter 30. The loop 24 can be soldered to the elongate
member 28 or can be affixed thereto using epoxy or other forms of
adhesive. Alternatively, the loop 24 can be an integral part of the
elongate member 28 (See FIG. 1B). A band or other mechanical
fixation devices (not shown) could also be used for this purpose.
The emboli filter 30 could be attached to the loop 24 using a
plurality of proximally extending anchors or fibers 32, each of
which are configured into small hoops 34 that engage the loop
member 24.
[0034] An elongate, tubular catheter 36, preferably a microcatheter
or otherwise a lumen of a conventional stent delivery catheter, is
also provided. The microcatheter 36 includes an internal bore 38
that is adapted to coaxially and slidably receive the elongate
member 28 as well as the looped member 24 and emboli filter 30
assembly. The delivery catheter 36 is capable of being manipulated
independent of the elongate member 28 and loop/filter assembly, for
example, by holding the delivery catheter 36 in a particular
longitudinal position while advancing the elongate member 28.
Alternatively, the delivery catheter 36 can be withdrawn or
advanced while maintaining a desired longitudinal position of the
elongate member 28.
[0035] The loop 24 is preferably made from a looped length of
superelastic wire. The elongate member 28 can be formed from a
guide wire.
[0036] Significantly, the loop 24 is configured so that when it
exits the distal end 40 of the delivery catheter 36, the loop 24
projects generally perpendicularly to longitudinal axes of the
elongate member 28 and catheter 36. It is also contemplated, that
for particular purposes, the loop 24 could project at an acute or
obtuse angle respecting the elongate member 28. Accordingly, it is
contemplated that the loop 21 also embodies shape retaining
material and a material that permits the loop 24 to quickly and
repeatedly return to a desirable pre-formed shape.
[0037] It is also highly significant that the loop 24 embodies
sufficient flexibility so that upon ejection from the delivery
catheter 36, the loop 24 generally conforms to an inside
circumference of a blood vessel 42 into which it is deployed. In
doing so, the elongate member 28 and distal portion 40 of the
delivery catheter 36 are generally positioned adjacent walls 44
defining an interior lumen of the blood vessel 42. Thus, the
expandable loop 24 spans the entirety of the circumference of the
vessel 42. Moreover, the elongate member 28 and delivery catheter
36 are advantageously displaced from the center or median of the
bloodflow, such that debris traveling through the vessel can avoid
these components and must pass through the loop 24.
[0038] In an alternative embodiment (FIG. 2A), the loop 24 can
embody a plurality of members 46, preferably two such members,
entwined about each other. The twined configuration 46
advantageously embodies additional hoop strength without
sacrificing the other advantages of the loop configuration such as
the ability to assume the contour of the interior 44 of the blood
vessel 42. The twined configuration also provides structure for
maintaining a desired spacing between anchors or fibers 32 which
are used to attach the filter 32 to the loop 24. Further, rather
than relying on an interference fit between the hoops 34 and the
loop 24 to accomplished desired spacing, the anchors 32 can embody
single mini-loops which encircle one of the twined members 46. In
yet another aspect of the invention, the loop 24 can embody
mini-loops 47 that serve to correctly space the tethers 32 (See
FIG. 2B).
[0039] The filter 30 includes a proximally directed opening 48 to
an interior 50. The body 52 of the filter 30 can have any exterior
profile but it is preferred that its exterior generally assume a
hemispherical or conical shape. The fully expanded filter 30 has an
opening 48 to the body 52 that is generally circular but can be
modified for a particular application. In one preferred embodiment,
the body 52 is made from a mesh-fabric material through which blood
can readily flow. The mesh contains apertures or pores 54 through
which the blood passes but which are small enough so that debris
does not flow therethrough. Alternatively, the filter can embody
laser cut mylar or is defined by ultrasonically welded polymer
fibers. In yet another aspect, the fiber crossing can be bonded
with flexible adhesive.
[0040] The filter sub-assembly 30 can be made from surgical mesh or
alternatively the filter 30 can embody a network of braided members
or fibers. For example, the filter can embody a braided expansion
wire 50. In one presently preferred embodiment, the expandable
device 20 consists of an elongate member 28 or guidewire with a
metal braided basket (not shown) attached to a loop or otherwise
directly attached to a superior end of the wire.
[0041] It is additionally contemplated that, as shown in FIG. 3,
the weaved basket 56 may be formed from polypropylene suture 58. In
order to manufacture the weaved basket 56, the polypropylene suture
58 is wrapped in an over and under weaving pattern about a mandrel
(not shown) which can embody a tapered or straight cylindrical
profile. A proximal or inferior end portion 60 includes reversals
of direction 62. A distal or superior end portion 64 is tied to
form a closed structure. The tied end is cut to provide an even
profile and a polymide tube 66 having the smallest diameter
possible is placed about the closed end. Thereafter, an adhesive is
applied to retain the polymide tubing 66 on the braided basket
56.
[0042] A shape set loop 24 is then threaded through the reversals
62. By doing so, the braided basket 56 is fixed to the loop 24. In
a presently preferred embodiment, the polypropylene suture 58 has a
diameter of 0.003 inches, the polymide tubing 66 has an inner
diameter of 0.0318 inches and an outer diameter of 0.0364 inches,
and the loop 24 is formed from 0.003 inch diameter nickel titanium
wire.
[0043] It is contemplated that in one preferred embodiment the
braided basket 56 comprises an 8-strand pattern that results in a
closed net. The length of the basket 56 will vary depending on the
size of the material to be removed. The diameter of the basket 56
will also vary from 2 mm to 50 mm depending on the lumen diameter
of the vessel from which material is to be removed. The basket 56
is attached to a loop 24 which opens the proximal end of the basket
51, allowing entry of material into the basket 56. The loop 24 may
be formed of a variety of elastic 24 or superelastic materials. The
diameter of the loop 24 will match that of the basket 56. The loop
24 may be covered, in part or in full, with a platinum coil to
minimize the potentiality of trauma caused by the device, and/or to
enhance attachment of the basket 56 to the loop 24. The inner
diameter of this coil corresponds to the outer diameter of the loop
strand, allowing for clearance. A typical coil is 0.009 inches in
inner diameter with a wire diameter of .0025 inches. The loop 24 is
attached to the elongate member 28 via soldering and other joining
technology.
[0044] The expandable devices 20 advantageously embody a simple
structure that can assume a very small contracted profile. Thus,
the device can be used in conjunction with a flexible microcatheter
36 that can traverse very narrow, tortuous and distal vasculature.
Upon expansion, the self-expanding loop 24 assumes the contour of
the vessel into which it is deployed thereby providing an optimized
structure for capturing debris. Moreover, when the loop 24 is
expanded, the microcatheter 36 and elongate member 28 lie adjacent
a wall defining vessel and substantially out of the way of the flow
path. Accordingly, the expandable device 20 can be used to
effectively repair virtually any portion of a patient's vasculature
by simply modifying the range of expanded loop 24 sizes.
[0045] Referring now to FIG. 4A, another preferred embodiment of an
expandable device is shown. In this embodiment, the present
invention is embodied in a dual-looped, expandable device 70. The
dual-looped device includes a first or inferior self expanding loop
72, a second or superior expanding loop 74, each of which are
attached to a distal end of an elongate member or wire 28. Highly
flexible connecting fibers 76 are routed between the first 72 and
second 74 loops to thereby define an emboli receiving cavity 78
when the device is in its expanded configuration. The connecting
fibers 76 act as structure for engaging and capturing emboli and
can be cross or non-crossing. Additionally, the connecting fibers
76 may embody a single continuous fiber or may include multiple
fibers. The fibers may be tied to the second loop 74 or they can
extend (not shown) beyond the second loop 74, tapering off and
terminating with a pointed end.
[0046] In one preferred embodiment of the dual looped device 70,
the elongate member 28 is comprised of Nitinol and includes a 0.004
inch outer diameter reduced section for receiving portions of the
loops 72, 74. Platinum coils (not shown) are employed to accomplish
affixing via soldering or similar means, the loops 72, 74 to the
elongate member 28. The connecting fibers 76 comprise polypropylene
strands. Further, in a preferred embodiment, the connecting fibers
76 are routed such that there are five (5) points of connection per
loop 72, 74, however, few or as many as 10 or more points of
connection are contemplated.
[0047] The dual-looped device 70 is also contemplated to be used
with a generally tubular delivery catheter 76 that is adapted to
slidably receive the elongate member 28 as well as receive
compressed loops 72, 74. The dual-loop device 70 also embodies the
advantages associated with the single loop design. That is, the
loops 72, 74 self-expand to assume the entire contour of a blood
vessel into which it is employed in such a manner that the delivery
catheter 36 and elongate member 28 lie adjacent to the vessel wall
that is substantially out of the flow path. FIG. 4B depicts another
preferred embodiment in which an additional loop 79 between loops
72 and 74 provides support for the filaments, enhancing entry of
material to an interior defined by the device.
[0048] In use, the expandable devices depicted in FIGS. 1-4 are
contemplated to be packed in a compressed state within the tubular
delivery catheter 36. Access is gained to the patient's vasculature
via conventional methods and the delivery catheter/expandable
device assembly is placed within the patient's vasculature. The
assembly is then advanced through the patient's vasculature to a
repair site and the distal end 40 of the delivery catheter 36 is
positioned beyond the repair site. Thereafter, the expandable
device 20, 70 is translated longitudinally with respect to the
delivery catheter 36 so that the expandable device exits the distal
end of the delivery catheter 36, which in turn, allows the
expandable device 20, 70 to self-expand.
[0049] As the expandable device 20, 70 expands, it projects at a
generally perpendicular angle (though any angle is possible) with
respect to the elongate member 28 and the loop 24 or loops 72, 74
assume the contour of the interior of the vessel of lumen.
Moreover, the filter body 52 is opened by the expansion of the loop
24 and in the case of the dual-looped device 70, the expansion of
the loops 72, 74 facilitate the formation of the embolic receiving
cavity 78.
[0050] Once it is in its fully deployed configuration, the
expandable devices 20, 70 are capable of capturing emboli or other
debris traveling antegrade in the bloodstream. The debris enters an
opening to the filter body 52 or the emboli receiving cavity 76 and
is captured therein. Once the debris is captured, the expandable
device 20, 70 may be removed from the vasculature, or other means
such as a suction device can be employed to independently first
remove the debris and thereafter, the expandable device can be
withdrawn.
[0051] With reference to FIG. 5A, there is shown another embodiment
of an expandable device of the present invention which is
specifically adapted for use as an embolectomy snare device 80. The
snare device 80 includes a plurality of shape memory elements 82
that are configured in alternating and generally undulating
sections to form a basket structure which defines an interior
pocket 84 and a proximally directed opening thereto (See FIG. 5B).
Adjacent elements 82 on one side of the generally conical,
basket-like profile may be laser welded or fixed to each other at
points of proximity. A proximal end 88 of the shaped memory
elements 82 is affixed by conventional means to an elongate member
90. Further, the snare device 80 is contemplated to be used in
conjunction with a generally tubular delivery catheter 36 which is
adapted to slidably receive the elongate member 90 as well as the
basket 83 in a compressed configuration.
[0052] The snare device 80 advantageously embodies elements which
are non-overlapping. To wit, snare device 80 can be packed very
tightly within an interior 38 of the delivery catheter 36 such as a
microcatheter. This feature is shown in FIG. 6, which depicts a
cross-sectional view of a snare device loaded within the delivery
catheter 36. Due to its ability to be packed into a very small
diameter microcatheter, the snare device 80 is well-suited for use
in narrow and distal vasculature.
[0053] In use, the snare device 80 is placed in its compressed
state within a delivery catheter 38 that is advanced within
vasculature to a repair site. The snare device 80 is then ejected
from a distal end 40 of the delivery catheter 36 and permitted to
self-expand within the target vessel. The expanded snare device 80
is then brought into engagement with embolic material found in the
bloodstream. The pocket defined by the basket profile 83 then
receives and captures the embolic material, which is then capable
of being removed from a patient's vasculature.
[0054] It is also to be recognized, however, that the devices
described herein can also be delivered through a guidewire lumen of
a balloon or stent catheter. This allows for direct placement
without requiring the use of a micro-catheter.
[0055] Turning now to FIGS. 7-10, there is shown an expandable
device 100 which concludes an actuating basket 102 defined by
elements 103. The elements 103 are weaved together in a generally
helical fashion. Although this expandable basket device 100 is
primarily intended for use in thrombectomy procedures, the device
has applications to the capture of emboli in the bloodstream as
well. The basket device 100 can be used in conjunction with a
microcatheter (not shown) or it can be deployed within vasculature
without using a microcatheter. As shown in the figures, the basket
device 100 may be attached to a distal end 104 of an elongate,
tubular carrier 106.
[0056] A retainer 108 is provided at a distal end 110 of the basket
device 100. The retainer 108 has a generally cylindrical profile
and includes an internal bore (not shown). The retainer 108
functions to maintain the distal end 110 of the basket device in a
closed configuration both when the basket 100 is unexpanded and
when it is expanded.
[0057] The basket device assembly device 100 is adapted to be
slidably placed about an elongate member 112 in a coaxial
arrangement. The elongate member 112 is likewise received in the
retainer 108 in a coaxial arrangement. Elongate member 112 includes
a plurality of beads 114, the outer profile which is greater than
the internal bore of the retainer 108 but smaller than an internal
diameter of the elongate tubular member 106.
[0058] The beads 114 have a dual function. A proximally positioned
bead 114 is employed, as shown in FIG. 7 to retain the basket
device 100 in a compressed configuration by holding the proximal
bead 114 in engagement with a proximal side 116 with a retainer
108. Expansion of the basket device 100 is achieved by translating
the basket device 100 distally with respect to the elongate member
112 and by causing the distal side 118 of the retainer 108 to
engage a distally positioned bead 114, the further the basket
device 100 is translated distally, the greater the radial
expansion. Accordingly, the basket device 100 can be controllably
and repeatedly expanded and contracted to the extent desired to
engage vessel walls of varied diameters. It is contemplated that
the basket device 100 embody wire elements 102 which have more
stiff distal portions than proximal portions so that when the
basket continues to expand, a concavity 120 is formed.
Alternatively, the concavity 120 can be formed if the basket device
100 is leashed to the elongate tubular member, for example.
[0059] As stated, the basket device 100 can also be used in
combination with the microcatheter. In a first step of use, the
microcatheter is employed to deliver an elongate wire 112 which
includes only a single bead 114. The microcatheter is then
completely withdrawn from a patient's vasculature and a basket
device 100 is threaded over the elongate member 112. Once the
retainer 108 of the basket device 100 is advanced sufficiently to
engage the bead 114, the basket device 100 can be made to expand
radially outwardly. In the event use of a microcatheter is
essential to the specific application, this alternative approach
allows for the use of a basket device 100 with an elongate tubular
member that has a larger outer diameter than an inner diameter of
the microcatheter, which advantageously allows for increased
pushability and column strength on the elements 103 defining the
basket portion 102.
[0060] In view of the foregoing, it is clear that the expandable
devices of the present invention are useful for the repair of
vasculature. In particular, the disclosed expandable devices are
particularly useful for the capture of emboli as well as for use in
thrombectomy procedures.
[0061] It will be apparent from the foregoing that, while
particular forms of the invention have been illustrated and
described, various modifications can be made without departing from
the spirit and scope of the invention. Accordingly, it is not
intended that the invention be limited, except by the appended
claims.
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