U.S. patent application number 11/317930 was filed with the patent office on 2006-05-11 for embolic basket.
Invention is credited to Olin Palmer, Christopher T. Shen.
Application Number | 20060100663 11/317930 |
Document ID | / |
Family ID | 29254716 |
Filed Date | 2006-05-11 |
United States Patent
Application |
20060100663 |
Kind Code |
A1 |
Palmer; Olin ; et
al. |
May 11, 2006 |
Embolic basket
Abstract
An intravascular basket device for use in capturing either
naturally occurring or foreign debris found in blood vessels or
other regions of the body. The basket device is fabricated from a
tube and includes a mid-section having at least one ring configured
in an alternating V-pattern. The basket device specifically
embodies structure that provides enhanced radial opening and
angular resistance to collapse.
Inventors: |
Palmer; Olin; (Mountain
View, CA) ; Shen; Christopher T.; (Stanford,
CA) |
Correspondence
Address: |
FULWIDER PATTON
6060 CENTER DRIVE
10TH FLOOR
LOS ANGELES
CA
90045
US
|
Family ID: |
29254716 |
Appl. No.: |
11/317930 |
Filed: |
December 22, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10423300 |
Apr 25, 2003 |
7004956 |
|
|
11317930 |
Dec 22, 2005 |
|
|
|
09939205 |
Aug 24, 2001 |
6575997 |
|
|
10423300 |
Apr 25, 2003 |
|
|
|
09469431 |
Dec 23, 1999 |
6402771 |
|
|
09939205 |
Aug 24, 2001 |
|
|
|
Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61F 2/013 20130101;
A61F 2002/016 20130101; A61M 29/00 20130101; A61B 2017/2212
20130101; A61B 2017/00526 20130101; A61F 2230/0097 20130101; A61B
17/221 20130101; A61F 2002/018 20130101 |
Class at
Publication: |
606/200 |
International
Class: |
A61M 29/00 20060101
A61M029/00 |
Claims
1-37. (canceled)
38. A medical device for treating vasculature of a patient,
comprising: an elongate member, the elongate member having a first
end portion and a second end portion and including a portion which
tapers from a first transverse dimension to a second transverse
dimension; and a filter body, the filter body attached to the
second end portion of the elongate member.
39. The device of claim 38, wherein the elongate member tapers in a
direction from the first end portion to the second end portion.
40. The device of claim 38, wherein the elongate member includes a
tapered portion, the tapered portion characterized by a gradual
taper.
41. The device of claim 38, wherein the elongate member includes a
tapered portion, the tapered portion characterized by a
step-taper.
42. The device of claim 38, wherein the elongate member includes a
tapered portion, the tapered portion characterized by a non-linear
taper.
43. The device of claim 38, wherein the elongate member includes a
tapered portion, the tapered portion characterized by a parabolic
taper.
44. The device of claim 38, wherein the filter body includes a
tab.
45. The device of claim 44, further comprising a coil attaching the
tab to the elongate member.
46. The device of claim 44, further comprising a first coil and a
second coil each attaching the tab to the elongate member.
47. The device of claim 46, wherein the first coil is formed from
304V stainless steel.
48. The device of claim 47, when the second coil is formed from a
platinum alloy.
49. The device of claim 48, wherein the first and second coils are
positioned longitudinally adjacent each other.
50. The device of claim 38, wherein the filter body includes a
distal tip portion.
51. The device of claim 50, wherein the distal tip portion includes
an inner coil and an outer coil.
52. The device of claim 51, wherein the inner and outer coils are
coaxially arranged.
53. The device of claim 52, wherein the inner coil is formed from
nitinol and the outer coil is formed from a platinum alloy.
54. The device of claim 53, wherein the inner and outer coils have
different longitudinal dimensions.
55. The device of claim 52, wherein the distal tip portion includes
a rounded terminal end formed from a soldered joint.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of application
Ser. No. 09/469,431, filed Dec. 23, 1999. The content of that
application is hereby incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to intravascular
devices and systems and more particularly, basket devices which can
be used to capture embolic material or thrombi found in blood
vessels.
[0003] The intravascular basket device and system of the present
invention is 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 basket device is also suited for the removal of
clots adhering to vessel walls. The device is also suitable for
removal of misplaced coils or other foreign material. While the
basket device and system of the present invention is particularly
useful in the cerebral vasculature and neurovasculature, the
invention can be used in conjunction with any vascular
interventional procedure in which there is an embolic risk.
Additionally, it can be used in any region of the body where
removal of debris or foreign material is indicated. Having a
patterned body cut from a single tube element, the basket device
allows for an enhanced radial opening into the basket body that
provides for greater ease of embolic capture. Additionally the
patterned body embodies greater stability during use by resisting
the natural tendency to collapse as seen in most prior art snares
during a typical operation.
[0004] 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 remote introduction of the interventional
device into the lumen of the artery, usually through a catheter. In
typical carotid PTA procedures, a guiding catheter or sheath is
percutaneously introduced into the cardiovascular system of a
patient through the femoral artery and advanced, for example,
through the vasculature until the distal end of the guiding
catheter is in the common carotid artery. 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 carotid 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 compress the atherosclerotic
plaque of the lesion against the inside of the artery wall 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.
[0005] 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.
[0006] 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.
[0007] Prior art stents typically fall into two general categories
of construction. A 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
compressed stent to a larger diameter to be left in place within
the artery at the target site. A 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.
[0008] 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.
[0009] When any of the above-described procedures are performed in
the carotid arteries, cerebral vasculature, or neurovasculature,
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 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.
[0010] 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 pose little chance of becoming occluded in 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.
[0011] In addition, the retrieval of fragmented clot may be
incomplete, also resulting in emboli and distal occlusions, and
further, access through tortuous lumens may prove difficult.
Laser-based disruption devices employ the photo-acoustic effect to
fragment clot. Local disruption may open up a proximal occlusion
but also may cause significant distal emboli.
[0012] 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 otherwise cause problems
to the patient's vasculature. 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
as well. 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 entirety of the vessel or it may include supporting
structure that itself impedes emboli collection. Certain other
devices do not embody sufficient angular resistance to
collapse.
[0013] Moreover, thrombectomy and foreign matter removal devices
have been disclosed in the art. However, in addition to suffering
from the same disadvantages as certain conventional filter devices,
such devices have been found to have structures which are either
highly complex such as with multiple components or highly
convoluted geometry or lacking in sufficient or effective expansion
and retraction capabilities. Disadvantages associated with the
devices having highly complex structure such as with multiple
components or highly convoluted geometry include difficulty in
manufacturability as well as use in conjunction with
microcatheters. Other devices with less coverage can pull through
clots due in part to the lack of experience in using the same or
otherwise lack an expanded profile that is adequate to capture
clots or foreign bodies.
[0014] Furthermore, in current interventional radiology practice,
the need arises to remove a variety of objects from intraluminal
spaces. Among these are embolic coils, guidewire tips, distal
catheter segments, thrombus and other vascular emboli, few of which
can be readily removed with current devices.
[0015] Thrombo-embolic materials can be friable, amorphous, and/or
lubricious in nature contributing to this difficulty. Most current
therapies rely on grasping, fragmenting, or dissolving the
blood-based obstructions. Among the grasping devices are the loop
snares and the wire basket snares. These devices may have limited
effectiveness, due in part to the lack of encapsulation. Objects
are difficult to grasp within these devices, and friable objects,
e.g. blood-based blockages, tend to fragment when grasped or
pulled, introducing multiple emboli.
[0016] Lytic drugs are also used to dissolve blood-based
obstructions. These typically have the disadvantages of lengthy
treatment/infusion times to remove the obstruction (>3 hrs.),
production of emboli, and the potential for systemic iatrogenic
bleeding as a side effect of the drug usage. Also, these drugs are
not typically effective in removing obstructions that are not
blood-based.
[0017] What has been needed is a reliable intravascular basket
device and system for use when treating blood vessels. The basket
devices should be capable of capturing any naturally occurring
embolic debris or that which may be released into the bloodstream
during an interventional treatment, while minimizing profile during
delivery and maximizing coverage when deployed to safely contain
the debris until the basket device is removed from the patient's
vasculature. The devices should embody an expanded profile that
presents a consistent radial opening that completely occupies the
vessel at the repair site as well as structure for effectively
resisting collapse. Moreover, such devices should be relatively
easy to deploy and remove 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
[0018] Briefly and in general terms, the present invention is
directed towards a basket for removing undesired material or
objects and restoring patency of blood vessels. The basket is a
linked or monolithic framework of thin struts that is radially
expansible. The basket of the present invention embodies a
structure that provides a consistent radial opening as well as
improved radial and angular resistance to collapse. That is, as the
device is pulled such as through a vessel, the entrance thereto
will not fall back or tip over. Moreover, the basket device
maintains clearance in its interior space along its length allowing
the material or objects to enter and be captured.
[0019] In one aspect of the invention, the basket includes struts
with very small widths and thicknesses and rings with very small
widths and thicknesses but large expansion ratios. It is
particularly beneficial to manufacture the basket from a piece of
tube stock, as opposed to prior art wire baskets, because the
resulting basket is more ordered upon compression, returns to its
expanded state more reliably and is quicker to manufacture. The
body of the basket device is defined by a plurality of openings
bounded by generally longitudinally and generally circumferentially
extending members. A proximally extending member is attached to an
elongate wire and the assembly is contemplated to be used in
conjunction with a generally tubular delivery catheter. In this
aspect the body provides enhanced stability at the proximal
transition between the wire and the proximally extending members
because the design may allow for varying lengths and widths of the
proximally extending members. The basket may be manufactured from a
single tubular element or from a sheet to form a desired
configuration.
[0020] Overall, the intent of the invention is to provide a
structure that has the capacity to engage, encompass and retain
naturally occurring or foreign bodies while having a minimal
profile that can traverse easily and repeatedly through a standard
microcatheter across tortuous anatomy. The device embodies superior
flexibility to be deployed and retrieved consistently across
difficult anatomy while being able to retain captured material. The
inner diameter of the device is heat-set to a pre-determined size.
It is envisioned that there be a family of devices that have
varying strut lengths, thicknesses, flexibility, and diameters as
deemed appropriate for the specific type of vascular or
non-vascular setting for which the device is to be used.
[0021] In a presently preferred embodiment, the basket device is
self-expanding and includes a mid-section that forms a generally
tubular profile. The proximally extending member projects as an
axial extension of a line at the surface of the cylinder generally
defining the substantially tubular portion to thereby provide an
unobstructed opening at the proximal end of the basket. A terminal
(i.e., distal) end of the basket device can be closed or
constricted so as to form a pocket for receiving emboli or
thrombotic debris.
[0022] The basket device can assume a number of forms. In one
presently contemplated aspect, the basket device of the present
invention embodies first and second end portions, and a mid-section
having a plurality of consecutive rings, each ring having a
plurality of generally straight members configured in an
alternating V-pattern providing a plurality of proximal and distal
apices. In another aspect, the intravascular basket device has a
mid-section defined by a single ring also having generally straight
members configured in an alternating V-pattern providing four
apices on each of the mid-section proximal and distal ends. In yet
another embodiment, the mid-section may embody a double ring design
configured in a four apex pattern. In other aspects, the basket
device mid-section may include rings having different lengths or,
in the alternative, include a proximal section having different
lengths. In the embodiments, the plurality of members can be
curved, S-shaped, angled, tapered etc. rather than straight or can
be a combination of straight and curved, angled, tapered or other
combinations etc.
[0023] Moreover, the present invention embodies a tip for an
endovascular device including an atraumatic soft coil for
preventing damage to tissue and facilitates advanceability. The tip
further includes multiple layers of coiled material to enhance
these objectives as well as to provide stiffness variations.
[0024] 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
[0025] FIG. 1 is a side view, partially in cross-section, of a
vessel occluded by debris and a distal portion of a delivery
catheter and intravascular snare assembly of the present invention
positioned proximate the debris;
[0026] FIG. 2 is a side view, partially in cross-section, of the
intravascular basket as deployed within the vessel of FIG. 1;
[0027] FIG. 3 is a plan view, depicting a pattern of a preferred
embodiment of an intravascular basket of the present invention as
if the basket was cut longitudinally and unrolled to show its
pattern in a flat configuration;
[0028] FIG. 3a is an enlarged view of a portion of an intravascular
basket of the present invention, depicting curvilinear members
defining the basket;
[0029] FIG. 3b is an enlarged view of a portion of an intravascular
basket of the present invention, depicting a filler member
positioned between other members defining the basket;
[0030] FIG. 4 is a plan view, depicting an unrolled pattern of a
second alternative embodiment of an intravascular basket of the
present invention;
[0031] FIG. 5 is a plan view, depicting an unrolled pattern of a
third alternative embodiment of an intravascular basket of the
present invention;
[0032] FIG. 6 is a plan view, depicting an unrolled pattern of a
fourth alternative embodiment of an intravascular basket of the
present invention;
[0033] FIG. 7 is a plan view, depicting an unrolled pattern of a
fifth alternative embodiment of an intravascular basket of the
present invention;
[0034] FIG. 8 is a plan view, depicting an elongate member of the
present invention;
[0035] FIG. 9 is a side view, partially in cross-section, depicting
a plurality of coils configured about a distal end portion of the
elongate members in combination with a basket device of the present
invention;
[0036] FIG. 10 is a cross-sectional view, depicting the assembly of
FIG. 9 taken along lines 10-10;
[0037] FIG. 11 is a side view, partially in cross-section,
depicting a distal end portion of a tip of the basket device of the
present invention;
[0038] FIG. 12 is a cross-sectional view, depicting a portion of
the assembly of FIG. 11 taken along lines 12-12;
[0039] FIG. 13 is a cross-sectional view, depicting the assembly of
FIG. 11 taken along lines 13-13;
[0040] FIG. 14 is a perspective side view, depicting the device
pattern projected onto the tubing which it will be cut from to
produce the basket device of FIG. 3; and
[0041] FIG. 15 is a perspective bottom view, depicting the device
pattern projected onto the tubing which it will be cut from to
produce the basket device of FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] Referring now to the drawings, and in particular FIGS. 1 and
2, there is shown a basket device of the present invention. The
basket device 20 is adapted to provide more consistent and improved
radial opening as well as enhanced angular resistance to collapse.
Moreover, the basket device 20 of the present invention is
configured to facilitate the maintenance of clearance in its
interior space along its length allowing the material or objects to
enter and be captured. Furthermore, since it is contemplated that
the basket device 20 be manufactured from a tubular member to form
elements with very small widths and thicknesses, the device is thus
more easily packed to a relatively smaller diameter and inherently
embodies high longitudinal flexibility.
[0043] The basket device 20 (FIG. 2) of the present invention
includes a body 22 having a proximal end portion 24 and a distal
end portion 26. The proximal end portion 24 is intended to be
affixed to a terminal end portion of an elongate member 30 (i.e.,
wire; described in more detail below). In a presently preferred
embodiment, the body 22 of the basket device 20 is generally
tubular with a proximally directed opening 32 and a generally
closed terminal end 34 to thereby form a basket for receiving
embolus, stones, thrombus and foreign bodies found in vasculature
or other body cavities.
[0044] The basket device 20 for intravascular uses is contemplated
to be used in conjunction with a generally tubular delivery
catheter 40, such as a microcatheter. Additionally, it is
contemplated that a conventional guide catheter (not shown) be used
in combination with the delivery catheter 40 loaded with a basket
device 20. A guide catheter (not shown) is employed to provide a
guide within a patient's vasculature through which the delivery
catheter 40 is inserted. A proximal end of the guide may include a
rotating hemostatic valve or "Y" adapter fitted with sealing
hemostatic valves. The basket device 20 is intended to be
self-expandable, however, it is possible to employ an expandable
member such as a balloon catheter (not shown) to radially expand
the basket device that is not self-expandable, but rather must be
deformed to assume an expanded configuration.
[0045] In use, the body 22 of the basket device 20 is placed
proximally in a compressed configuration coaxially within an
internal bore of the generally tubular delivery catheter 40. The
longitudinally extending elongate member 30 which is attached to
the proximal end 24 of the body 22, is likewise coaxially received
within the delivery catheter 40. Both the body 22 and elongate
member 30 are slidable within the delivery catheter 40 and
accordingly, the delivery catheter 40 and the basket device 20 can
be displaced longitudinally with respect to each other.
[0046] A typical procedure will now be described. In order to
restore patency in a vessel, the basket device/delivery catheter
assembly 42 is introduced into a patient's vasculature using
conventional means such as the Seldinger technique. Sometimes, a
cutdown is made to gain access to the patient's vasculature. Using
standard endovascular techniques, the emboli in the vasculature is
located. The emboli is crossed with an appropriate guidewire (not
shown) then the delivery catheter 40. If the vessel is occluded,
contrast is injected distal to the occlusion to map the distal
vessels. The tip 48 of the delivery catheter 40 is positioned one
basket length or slightly more beyond the emboli. The guidewire is
removed and the basket device 20 is loaded through a rear hub (not
shown) of the delivery catheter 20 with the assistance of an
introducer sheath (not shown). The basket device 20 is advanced
30-40 cm and the introducer sheath is then removed.
[0047] Next, the basket device 20 is advanced until the tip 26 of
the basket is positioned at the distal end of the delivery catheter
40. Radioopaque markers are located on either side of the basket so
that the operator can see when the basket is located just inside of
the end of the delivery catheter 40. The basket device 20 is held
in place by the operator holding the elongate member 30 still while
the catheter 40 is retracted to allow the basket device to expand.
Holding the basket device 20 in place, the catheter 40 is pulled
back until it is proximal to the emboli 46. Then, the basket device
is drawn back allowing the emboli 46 to enter the basket device 20.
Alternatively, the entire system can be drawn back holding relative
positions between the basket device 20 and the catheter 40. This
step can be assisted with a "stuttering" technique where the basket
device 20 is drawn out a small amount, perhaps 2 mm, then the
elongate member 30 is advanced back perhaps 1 mm to allow the mouth
of the basket device 20 to re-open fully, thereby assisting clot or
emboli entry into the basket. Then the system is drawn out another
1 mm. This is repeated until the basket device 20 has traversed a
distance about its own length. To reduce the risk of losing the
material contained in the basket or device, blood flow control may
be used during extraction. For example, a guiding catheter with a
flow control device such as an elastomeric balloon at the distal
tip may be employed to slow or stop blood flow past the device
during retrieval.
[0048] If the emboli 46 is foreign in origin, such as a coil, the
basket device 20 can be moved back and forth past the coil in an
iterative attempt to engage the coil in the struts of the basket.
When this has occurred, the catheter 40 can be advanced causing the
basket to collapse and pinch the coil, locking it into one of the
openings of the basket device 20. If the emboli is not radiopaque,
its position may be checked by a contrast injection and noting a
"filling defect." Also, the radiopaque tip 26 of basket device 20
can be observed under fluoroscopy during this process. A pulsing
motion can indicate restored flow.
[0049] The system 42 is then drawn back until the distal end of a
proximal device marker coil (described below) is at the tip of the
guide. At this point, a large syringe, perhaps 60 cc, is attached
to the guide catheter at the "Y" adapter on the hub. The guide
catheter is aspirated as the basket device 20 and emboli 46 are
drawn into the guide. Aspiration is maintained until the basket
device 20 is fully into the "Y" adapter of the guide catheter, but
the basket device 20 is not yet drawn through the hemostatic valve.
The "Y" adapter is detached and removed with the basket device in
it, allowing a moment of bleed back through the guide to flush any
loose emboli. Optionally, then a second "Y" arm is attached to
prevent excessive bleed back. The guide is then flushed with saline
and the entire procedure repeated as required to remove further
emboli.
[0050] The manner in which the body portion 22 of the basket device
20 self-expands within the vasculature and the resultant expansion
profile provides a number of advantages. In particular, the body 22
expands to conform to the repair site 44. That is, the generally
tubular profile of the body portion 22 substantially conforms to
the walls defining the blood vessel 49. Alternatively, the basket
device 20 can be sized such that upon full expansion it has a
diameter smaller than the diameter of the blood vessel 49 if
desired. Moreover, the expansion of the body 22 facilitates the
maintenance of clearance in its interior space along its length
allowing the material or objects 46 to enter and be captured and
specifically provides a substantially unobstructed access to the
proximally directed opening 32 to the body 22. Significantly, as
the body 22 self-expands, members 50 and 51 leading to the opening
32 to the body 22 are angled or oriented so as to be adjacent to
the walls defining the blood vessel 49 and are therefore
substantially removed from the flow path to thereby provide an
unobstructed opening 32.
[0051] In its expanded state, the basket device 20 is particularly
well-suited to remove embolic or thrombotic debris 46 from the
blood vessel 49. As stated, the basket device 20 can be withdrawn
proximally so that the debris 46 can be captured by the body 22 of
the basket device 20. Alternatively, a separate pusher mechanism
(not shown) can be employed to push the debris 46 within the basket
defined by the body portion 22. Once the debris has been captured,
the system 42 can be removed from the patient's vasculature or the
basket device 20 containing the debris 46 can first be pulled
within the guide catheter (not shown) and then the assembly 42
removed from the target repair site 44. Also, just the proximal end
portion 24 of the basket device 20 can be cinched down to lock the
debris without being fully pulled into the delivery catheter
40.
[0052] It is to be understood, however, that thrombus or other
blood-based material captured within the basket may be eliminated
in a variety of ways. For example, the material may be drawn into
the guide catheter with the aide of suction applied to the guide
catheter, and removed from the body. Also, these materials may be
removed from the occluded vessel and allowed to dissolve under
natural or induced lytic processes. Alternately, the blood-based
material may be inserted into other vasculature more tolerant of
occlusion and released.
[0053] Referring to FIG. 3, in a preferred embodiment of a basket
pattern 125 shown as if it was cut longitudinally and unrolled to
depict its pattern in a flat configuration, a basket 20 includes a
proximal section 126, mid-section 132, and a distal section 127.
The sections 126, 132 and 127 together form a substantially tubular
basket body 22 with a tapered distal end as will be developed
further below. It is contemplated that the body 22 embodying such a
pattern 125 be cut from a tubular member using a laser.
Alternatively, the body can be made from a flat sheet of nitinol
and rolled into a tubular basket body. As best seen in its
flattened or unrolled state, the basket pattern 125 further
includes an elongate member 30 extending proximally from a proximal
end portion 53 of the basket body 22. It is also to be recognized
that each of the members defining the basket body 22 in this or
other embodiments may have curved, arced, S-shaped, partially
straight sections or other configurations (See FIG. 3a, for eg.).
Additionally, it is contemplated that the body can further include
branches 121 with an enlarged or angled terminal end (FIG. 3b)
which act as fillers between other members defining the body 20.
Such fillers 121 aid in providing a basket highly equipped to
contain material.
[0054] The proximal section 126 of the basket 20 includes a
proximal end 23, a distal end 25 and a straight member section 128.
The straight member section 128 includes a plurality of members 130
generally configured in a V-shape in that the members "fan out" or
diverge in a distal direction. In this configuration, the straight
members 130 lead to and aid in defining an opening 32 (see FIGS. 2
and 14) to the body 22, when in its as-cut tubular configuration.
Therefore, the members 130 of the straight member section 128 are
pair-wise configured in a V-shape such that two proximal vertices
129 are formed where the members 130 proximally merge and four
open-ended distal end points 131 are provided to define the distal
end 25 of the member section 128. It is noted that in the current
configuration, the straight member section 128 defines the entirety
of the basket proximal section 126, however, as will be
subsequently discussed, in alternative embodiments, the proximal
section 126 may include a plurality of straight member sections.
Finally, the two proximal vertices 129 of the member section 128
merge into two curved members 50. The curved members 50 converge
proximally to form a tab 53 that may be connected to an elongate
member 30.
[0055] The mid-section 132 of the basket pattern 125 may be of a
four apex design including a single ring 133 that defines the
generally tubular mid-section 132. The ring 133 includes a
plurality of straight members 136 configured in an alternating
V-pattern forming a plurality of proximal apices 135 and distal
apices 137. In order to achieve the four apex design of basket
pattern 125, the ring 133 of the basket mid-section 132 may include
eight straight members 136 converging end to end in an alternating
V-pattern to form four proximal apices 135 and four distal apices
137. Each of the four proximal apices 135 merge into the open-ended
distal end points 131 of the straight members 130 of the basket
proximal section 126.
[0056] The intersection of the four straight members 130 of the
basket proximal section 126 and the straight members 133 of the
basket mid-section 132 at the proximal apices 135 define a
plurality of diamond-shaped apertures 118. Additionally, a single
enlarged diamond-like aperture 116, located substantially within
the basket proximal section 126, is defined by the intersections at
the proximal end of the basket proximal section 126 between the two
curved members 50 and the proximal vertices 129 of the basket
proximal section 126 and the intersections at distal end of the
basket proximal section between the distal end points 131 of the
proximal section 126 to the proximal apices 135 of the basket
mid-section 132.
[0057] Referring still to FIG. 3, the distal section 127 of the
basket 20 includes a single straight member section 139 having
straight members 140 in a V-shape configuration that "fans-in"
(i.e., converge) distally. At the proximal end, the straight
members 140 include four open-ended proximal ends 138 (the branches
of the V-shape) at the distal apices 137 of the basket 20
mid-section 132. At the distal end, straight members converge to
form two vertices 141 at the distally directed members 142. The
junction between the two straight members 140 of the basket distal
section 127 and the straight members 133 of the basket mid-section
132 at the distal apices 137 define a plurality of diamond-shaped
apertures 120.
[0058] The distally directed straight members 142 of the basket
distal portion 127 may be joined together to form a substantially
closed basket. This structure can be joined using soldering or by
employing a coil (described herein below) that is wrapped about
adjacent structures to form a soft tip. The distally directed
extensions 142 may also be trimmed to a desired length.
[0059] Another way to describe the basket device is that it begins
with a proximal elongate member linked to a series of divergent
branches of increasing density covering successively smaller
fractions of the tubular circumference. The increasing density of
the divergent branches wrap around the circumference from the side
where the elongate member ends to form the tube. Linked from the
divergent branches is one or more ring segments in which an equal
number of struts enter and exit at the joints. Branching from the
ring segment is a series of convergent branches of decreasing
density covering successively larger fractions of the tubular
circumference. This section is tapered down to the distal tip to
reduce the required coverage area thus maintaining adequately small
openings for encapsulation.
[0060] It is noted that the dimensions of a basket pattern may be
varied in a number of ways to produce a number of alternative
embodiments of the current invention. From these alternative
embodiments it will be understood that the lengths of the straight
members of the mid-section rings may be varied accordingly to
address any specific application requirement. Similarly, the
lengths of the generally straight members of the member section of
the proximal section may also be varied in length according to the
desired design requirement. In order to have the device collapse
evenly, all continuous (not recursive) paths from the first
bifurcation to the last convergence of members must be of
approximately the same length. Otherwise, during collapse the
longer members are forced to buckle or the shorter members are
forced to stretch to achieve a substantially linear constrained
configuration.
[0061] Referring to FIGS. 4-7, alternative embodiments of the
current invention are depicted. Generally, the basket patterns 145
include a mid-section 148 having two rings 152 and 153 configured
in a "four apex" design. Each ring 152, 153 is defined by a
plurality of connected vees to thereby define a ring having a
generally serpentine pattern. A two ring design having a distal
taper may provide enhanced clot capturing capabilities because of
the smaller sized apertures located at the distal portions of the
basket body 22. In the second and fourth embodiments (FIGS. 4 and
6), the rings 152 and 153 include straight members 155 and 159
having a first length. In the third and fifth embodiments (FIGS. 5
and 7), the rings 152 and 153 include straight members 170 and 174
having a second length that is longer than the first length of
straight members 155 and 159. Therefore, the rings 152 and 153 of
the second and fourth embodiments are shorter in length than the
rings 152 and 153 of the third and fifth embodiments. It is
envisioned that the length of the rings of the third and fifth
embodiments may be two or more times longer than the rings of the
second and fourth embodiments and that there can be any number of
rings.
[0062] As with the previous embodiment described above, in all four
alternative embodiments of basket pattern 145 (FIGS. 4-7), the
straight members of each ring are configured in an alternating
V-pattern layout to produce four apices on both the proximal and
distal ends of each ring. Each ring 152 includes proximal apices
154 and distal apices 156 and each ring 153 includes proximal
apices 158 and distal apices 160. The ring 152 is connected to ring
153 at the connection 157 between apices 156 and 158. Together
rings 152 and 153 form the generally tubular mid-section 148.
[0063] Similar to the first embodiment (as shown in FIG. 3), the
basket patterns 145 of the second through fifth embodiments (FIGS.
4-7) includes a proximal section 146 and a distal section 147
configured and connected to the mid-section 148 in a like manner as
the first embodiment. As mentioned above, the two ring design of
the basket patterns 145 allow for a distally tapering body 22 that
provides for the capture of smaller emboli because the additional
ring results in a body 22 having an increased number of apertures
which are each smaller in size than those of the single ring
design.
[0064] Referring to FIGS. 6 and 7, further variations on the
embodiments of FIGS. 4 and 5 respectively are provided. The
variations include changes to the proximal transition defining
proximal opening 32 of the basket 20. Therefore, in the second and
third embodiments (FIGS. 4 and 5), a first member section 150
includes straight members 151 having a first length, while in the
fourth and fifth embodiments (FIGS. 6 and 7) the first member
section 150 includes straight members 181 having a second length
that is shorter than the length of straight members 151. The change
in the length of the members of the first member section 150 is
intended to increase the radial strength of the device proximally.
Therefore, the radial strength of the proximal transition of the
device body 22 is increased which improves emboli capture by
holding the device open and a shorter tab improves push by
providing greater resistance to column buckling.
[0065] As can be seen from the various embodiments presented
herein, the basket device 20 may be configured having different
mid-section 148 or proximal section 146 lengths or may be designed
to include different numbers of apices within the mid-section.
These changes are only dependent on the design requirements of the
physician, and any such modification will not depart from the scope
of the present invention.
[0066] Referring now to FIG. 8, there is shown one preferred
embodiment of the elongated member 30 of the present invention. The
member 30 embodies a gradual or step-tapered core comprising a
proximal section of 304V stainless steel and a distal section of
nitinol or an equivalent material for the intended purpose. A
proximal portion 200 of the member 30 has a generally constant
cross-sectional profile and a first diameter 201. At a transition
point 202, the member 30 begins to taper in a gradual and
consistent, alternatively in a step-tapered or in parabolic or
other non-linear manner, from the first diameter 201 to a second
diameter 203 along a distal end portion 204.
[0067] As shown in FIGS. 9 and 10, a pair of longitudinally
adjacent arranged coils 206, 208 are employed to attach a proximal
tab 214 of a basket device 20 to the distal end portion 204 of the
elongate member 30. The first, proximal coil 206 is contemplated to
be composed of 304V stainless steel, the first coil being soldered
to the elongate wire 30 near its tapered portion 210. The second
coil 208 is contemplated to embody a medical grade radiopaque wire,
typically a platinum alloy such as about 90% platinum and 10%
iridium alloy. This second coil 208, which serves as a radiopaque
marker, is soldered to the elongate member 30 near a distal end
portion 212 of the first coil 206. Alternatively, the second coil
208 is soldered to the first coil 206. A proximal tab 214 of the
basket device 20 is contained within the second coil 208 and is
soldered 216 to the elongate member 30.
[0068] Turning now to FIGS. 11-13, one presently preferred
embodiment of a distal tip portion 220 of the basket device 20 of
the present invention is described. The distal tip portion 220
embodies two partially coaxial coils 222, 224, the combination of
which retains the distally directed extensions projecting from the
body 22 of the basket device 20. The combination also provides a
soft atraumatic tip with variable stiffness from softest distally
to stiffer proximally. Varying the relative lengths of the tip and
coils 222, 224 results in creating changes in stiffness and thus,
can be selected to provide the device with desired flexibility.
[0069] The inner coil 222 is comprised of nitinol or equivalent
material, and begins at a proximal location 226 and extends to a
distal location 228. The nitinol inner coil 222 provides kink
resistance as well as creates a smooth stiffness transition from
the tip of the basket portion of the basket device 20. The outer
coil 224 is coaxially configured about a distal portion 230 of the
inner coil 222 and is preferably comprised of 90% platinum and 10%
iridium alloy or an equivalent combination of materials. As such,
the outer coil 224 can operate as a radiopaque marker.
[0070] The distal tip portion 220 further includes a rounded
terminal end 232 that provides a blunt atraumatic surface. The
terminal end 232 embodies a soldered joint which acts in retaining
the helical configuration of the outer coil 224.
[0071] With reference to FIGS. 14 and 15, a brief summary of the
process used to manufacture the basket devices 20 of the present
invention is provided, with a specific focus on a second embodiment
of the present invention. As shown in FIG. 3, the preferred
embodiment of the present invention is relatively similar to the
other embodiments disclosed and includes a four apex single ring
pattern 125. It is contemplated that the basket devices 20 of the
present invention be cut from a tube 240 using a laser. In
particular, a specific pattern is programmed into the laser device
and the laser is activated to cut the desired pattern into the
tubular element 240. The excess tubular components are removed,
thereby leaving a manufactured structure such as the basket pattern
125 shown in FIG. 3, corresponding to the desired pattern. In a
presently preferred embodiment, a superelastic material such as
nitinol is a material of choice for the basket device 20.
Thereafter, post-processing such as surface treatment, burr
removal, oxide removal and/or shape setting of the manufactured
structure is performed. Heat treating is also performed for
stress-relief of the device.
[0072] In particular, post-processing steps include taking an
as-cut device and bead blasting the device with aluminum oxide
blasting media. The device is then inspected under a microscope for
residual slag. If slag remains, the device is bead blasted again.
Thereafter, the device is stress relieved in a molten salt bath
without expanding. The device is subsequently heat-expanded in a
molten salt bath mounted on a suitable size mandrel. After heat
expansion, surface oxidation is removed in an aqua regia bath. When
nitinol is the material of choice, the nitinol is etched with HF
solution to desired strut size resulting in desired softness. The
device is then mounted on a guidewire using coils and solder.
[0073] In the case of the pattern 125, the post-processing may
include deforming the pattern 125 and then joining together the
distal end members 142 for the purpose of achieving a closed basket
for receiving debris found in vasculature. Being so configured, the
pair of diverging members 50 define an opening 32 to the resultant
basket and the elongate member 30 extends from a sidewall defined
by the opening.
[0074] The basket devices of the present invention each provide
improved radial opening compared to prior art loop snares since in
an expanded state, the elongate member 30 is positioned
substantially out of the flow path. Additionally, the device
embodies improved resistance to radial and axial loads compared to
prior art loop snares. Moreover, since less deformation is required
to produce a desired basket pattern, in that, angles between
members are provided by laser cutting rather than from local
deformations, for example, there is potentially improved stress
distribution along the basket devices of the present invention
compared to prior art loop snares. Additionally, a greater
reduction in radial profile can be achieved without sacrificing
performance and in particular, the device can be used in
conjunction with microcatheters. As such, the basket devices 20 of
the present invention can be passed through narrow and tortuous
vasculature. The applications of the present invention are more
widespread than that of conventional snare devices because of
greater retrieval characteristics while retaining the
deliverability characteristics.
[0075] The above described invention is principally conceived to be
operational for use in engaging for the purpose of displacing
and/or removing material either foreign or native to the body,
including partial or complete obstructions embolic and/or
thrombotic in nature, from intraluminal or extraluminal spaces of
the body including but not limited to intravascular and/or
intra-arterial regions of the cerebral vasculature, as well as
tubings, stents, or other objects that may or may not be internal
to the body. The purpose of the device is to restore functionality
of the luminal space or systems dependent on the particular luminal
space or as a method of producing any desired effect associated
with the removal or displacement of undesirable material.
[0076] The intended delivery of the disclosed invention is by means
of a commercially available catheter selected for its ability to
access the desired location of engagement. The invention may be
optimized for specific locations or uses by means of sizing the
individual elements in the design and/or the overall dimensions, as
well as selection of materials, mesh configuration, number and
relative geometry of component members to meet the requirements of
the operational space. Optimizations may include tabs protruding
from the sides of members to increase coverage of the open areas
between members, offsetting vertices of joints to increase packing
efficiency, or providing unconnected distal curved path. There may
additionally be variations of the dimensions of length, thickness,
and width of distal and proximal tabs for joining basket with
delivery wire and distal tip to provide smooth stiffness
transitions from tip to basket and basket to delivery wire. Such
optimizations are means of adjusting operational attributes
including: flexibility, applied circumferential force, engagement
effectiveness, deliverability and traversal through tortuous
vasculature, and volume of material to be engaged.
[0077] Alternate or additional materials for the basket portion of
the device may include a shape memory polymer thermoset, elastomer,
thermoplastic constituents such as nylon, or other metal either
pure or alloyed, as well as composite materials such as a
combination of glass, aramid, or carbon in a binding matrix. A
secondary mesh of the same or dissimilar material may be added to
the basket. The wire portion of the device can alternatively be
made from a single metal or combination of metals for kink
resistance and high flexibility. Either or both components may be
tapered to give a transition in stiffness that is appropriate for
the vessel in which the invention is to be delivered. The distal
tip of the device may incorporate concentric coils made of nitinol,
stainless steel, or other metal or plastic to provide a soft
flexible atraumatic end.
[0078] An alternate method of manufacture of the basket portion of
the device may be photo etching, or metal or polymer injection
molding or water jet cutting. Furthermore, the device may employ
any combination of coatings, agents, or features including those
that result from material addition or subtraction to create
grooves, bumps, three dimensional patterns, and textures on inner
and/or outer surfaces or any combination thereof to promote desired
properties such as adherence of materials to be engaged,
radiopacity, and low friction between the device and the vessel
wall or microcatheter lumen.
[0079] In summary, the invention is deliverable to remote regions
of the vasculature by gaining access through the use of a guidewire
and microcatheter in the vasculature and subsequent deployment of
the invention through the lumen of the microcatheter. In a vessel
in which flow is impeded or obstructed by material and/or objects
including those formed by the body such as blood clot, the device
is deployed by withdrawing the microcatheter relative to the
elongate wire and basket. Engagement occurs as the system composed
of the invention is pulled proximal, causing the basket to
encompass the material. After the material has been engaged,
removal of the material is accomplished by withdrawing the system
into a guide catheter lumen through which the microcatheter is
passed with or without simultaneously pulling fluid through the
guide lumen or removing the entire system with the guide
catheter.
[0080] Thus, 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 the parting
from the spirit and scope of the invention. Accordingly, it is not
intended that the invention be limited, except as by the appended
claims.
* * * * *