U.S. patent application number 12/102678 was filed with the patent office on 2008-09-04 for delivery systems for embolic filter devices.
This patent application is currently assigned to ADVANCED CARDIOVASCULAR SYSTEMS, INC.. Invention is credited to William J. Boyle, Benjamin C. Huter, Scott J. Huter.
Application Number | 20080215084 12/102678 |
Document ID | / |
Family ID | 24776626 |
Filed Date | 2008-09-04 |
United States Patent
Application |
20080215084 |
Kind Code |
A1 |
Boyle; William J. ; et
al. |
September 4, 2008 |
DELIVERY SYSTEMS FOR EMBOLIC FILTER DEVICES
Abstract
A delivery system for an expandable filter device includes a
dual lumen delivery sheath which has a lumen for receiving the
expandable filter device and a lumen for receiving a primary guide
wire. The primary guide wire is utilized to place the delivery
sheath and expandable filter into the desired region of the
patient's vasculature via an over-the-wire or rapid-exchange
arrangement. The delivery sheath can be protracted over the
expandable filter device to allow the filter to be deployed within
the patient's vasculature at the desired location. The delivery
system can be embodied in an alternative design in which the
primary guide wire extends through a guide wire lumen located in an
obturator which forms part of the expandable filter device. Again,
the primary guide wire is utilized to maneuver the filter device
into the desired area via an over-the-wire arrangement. A slit
extending longitudinally along the length of the sheath facilitates
the removal of the guide wire and delivery sheath from the
patient's vasculature.
Inventors: |
Boyle; William J.;
(Fallbrook, CA) ; Huter; Benjamin C.; (Murrieta,
CA) ; Huter; Scott J.; (Temecula, CA) |
Correspondence
Address: |
JUNE JAMES
650 PR 180
HELOTES
TX
78023
US
|
Assignee: |
ADVANCED CARDIOVASCULAR SYSTEMS,
INC.
Santa Clara
CA
|
Family ID: |
24776626 |
Appl. No.: |
12/102678 |
Filed: |
April 14, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10385162 |
Mar 10, 2003 |
|
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|
12102678 |
|
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|
|
09691463 |
Oct 17, 2000 |
6537294 |
|
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10385162 |
|
|
|
|
Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61F 2002/018 20130101;
A61F 2/95 20130101; A61F 2230/008 20130101; A61M 25/0668 20130101;
A61F 2230/0006 20130101; A61F 2/013 20130101; A61F 2230/0067
20130101 |
Class at
Publication: |
606/200 |
International
Class: |
A61M 29/00 20060101
A61M029/00 |
Claims
1. A system for delivering a filter device within a body vessel,
comprising: a guide wire having a proximal end and a distal end;
and a sheath having a proximal end and a distal end and including a
first lumen for receiving the filter device and a second lumen for
receiving the guide wire therethrough, the filter device and sheath
being moveable along the guide wire for positioning the filter
device within the body vessel, the sheath being retractable over
the filter device for deploying the filter device within the body
vessel for deployment.
2. The delivery system of claim 1, wherein: the filter device is
self-expanding.
3. The delivery system of claim 1, wherein: the second lumen for
receiving the guide wire extends substantially along the length of
the sheath.
4. The delivery system of claim 1, wherein: the second lumen for
receiving the guide wire is a short tubular segment located near
the distal end of the sheath.
5. The delivery system of claim 1, wherein: the first lumen for
receiving the filter device extends into the second lumen for
receiving the guide wire near the distal end of the sheath.
6. The delivery system of claim 5, wherein: the first lumen for
receiving the filter device has a diameter which decreases as the
first lumen extends toward the distal end of the sheath.
7. The delivery system of claim 5, wherein: the distal end of the
first lumen is tapered at the region where it connects with the
second lumen to reduce the overall diameter of the sheath at its
distal end.
8. The delivery system of claim 1, wherein: the sheath includes
perforations located near its distal end which causes at least a
portion of the sheath to rupture as the sheath is retracted over
the filter device.
9. The delivery system of claim 8, wherein: the distal end of the
sheath includes a line of perforations which extend longitudinally
along the length of the sheath in the distal region of the
sheath.
10. A delivery sheath for delivering a filter device within a body
vessel, comprising: an elongated tubular member having a proximal
end and a distal end and including a first lumen for receiving the
filter device and a second lumen for receiving a guide wire
therethrough; wherein the filter device and elongated tubular
member are moveable along a guide wire for positioning the vessel
within the body vessel and the tubular member retractable over the
filter device to deploy the filter device within the body
vessel.
11. The delivery sheath of claim 10, wherein: the filter device is
self-expanding and is mounted on a second guide wire.
12. The delivery sheath of claim 10, wherein: the second lumen for
receiving the guide wire extends substantially along the length of
the elongated tubular member.
13. The delivery sheath of claim 10, wherein: the second lumen for
receiving the guide wire is a short tubular segment located near
the distal end of the tubular member.
14. The delivery sheath of claim 10, wherein: the first lumen for
receiving the filter device extends into the second lumen for
receiving the guide wire near the distal end of the tubular
member.
15. The delivery sheath of claim 14, wherein: the first lumen for
receiving the filter device has a diameter which decreases as the
first lumen extends towards the distal end of the tubular
member.
16. The delivery sheath of claim 15, wherein: the distal end of the
first lumen is tapered at a region where it connects with the
second lumen to reduce the overall diameter of the tubular member
at its distal end.
17. The delivery sheath of claim 10, wherein: the tubular member
includes perforations located near its distal end which cause at
least a portion of the tubular member to rupture as a tubular
member is retracted over the filter device.
18. The delivery sheath of claim 10, wherein: the first lumen for
receiving the filter device is a short tubular segment located near
the distal end of the tubular member.
19. The delivery system of claim 18, wherein: the first lumen has a
first end and a second end and a primary diameter sufficient to
receive the filter device in a collapsed position with a narrower
diameter near the first and second ends to resist movement of the
filter device from the sheath as it is being delivered within the
body vessel.
20. The delivery sheath of claim 10, wherein: the first lumen for
receiving the filter device includes a slit extending
longitudinally from the proximal end of the tubular member to a
region adjacent to the sleeve which houses the filter device for
facilitating removal of the second guide wire therethrough.
21. The delivery sheath of claim 10, wherein: the second lumen for
receiving the guide wire includes a slit extending longitudinally
from the proximal end to the tubular member to a region adjacent to
the portion of the sheath which houses the filter device to
facilitate removal of the guide wire therethrough.
22. A system for delivering a filter device within a body vessel,
comprising: a guide wire having a proximal end and a distal end; a
filter device moveable between a collapsed position and an expanded
position which includes an obturator located at the distal end of
the filter device, the filter device being attached to the guide
wire near its distal end; and a guide wire lumen extending through
the obturator which is adapted to receive a second guide wire used
to deliver the filter device into the body vessel utilizing an
over-the-wire technique.
23. The delivery system of claim 21, wherein the obturator has a
central distal tip and the guide wire lumen extends through the
central distal tip.
24. The delivery system of claim 21, wherein: the obturator has a
central distal tip and the guide wire lumen extends through the
obturator offset from the central distal tip.
Description
BACKGROUND OF THE INVENTION
[0001] This application is a continuation of application Ser. No.
10/385,162, filed Mar. 10, 2003; which is a continuation of Ser.
No. 09/691,463 filed Oct. 17, 2000, U.S. Pat. No. 6,537,294, issue
date of Mar. 25, 2003 which is assigned to the same Assignee as the
present application.
[0002] The present invention relates generally to filtering devices
and systems which can be used when an interventional procedure is
being performed in a stenosed or occluded region of a blood vessel
to capture embolic material that may be created and released into
the bloodstream during the procedure. The system of the present
invention is particularly useful when performing balloon
angioplasty, stenting procedures, laser angioplasty, atherectomy,
or other interventional procedures in critical vessels,
particularly in vessels such as the carotid arteries, 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. While the embolic
protection system of the present invention is particularly useful
in carotid procedures, the invention can be used in conjunction
with any vascular interventional procedure in which there is an
embolic risk.
[0003] 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 carotid PTA procedures, a guiding catheter or sheath is
percutaneously introduced into the cardiovascular system of a
patient through the femoral artery and advanced through the
vasculature until the distal end of the guiding catheter is in the
common carotid artery. A guide wire and a dilatation catheter
having a balloon on the distal end are introduced through the
guiding catheter with the guide wire sliding within the dilatation
catheter. The guide wire 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 guide wire 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.
[0004] 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.
[0005] 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.
[0006] 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
compressed 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 collapsed 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.
[0007] The above non-surgical 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 non-surgical 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.
[0008] When any of the above-described procedures are performed in
the carotid or arteries, the release of emboli into the circulatory
system can be extremely dangerous and sometimes fatal to the
patient. 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.
[0009] Medical devices have been developed to attempt to deal with
the problem created when debris or fragments 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.
[0010] 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 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 filtering systems, particularly during the
expansion and collapsing of the filter within the body vessel. If
the filtering device does not have a suitable mechanism for closing
the filter, there is a possibility that trapped embolic debris can
backflow through the inlet opening of the filter and enter the
blood-stream as the filtering system is being collapsed and removed
from the patient. In such a case, the act of collapsing the filter
device may actually squeeze trapped embolic material through the
opening of the filter and into the bloodstream.
[0011] Some of the prior art filters which can be expanded within a
blood vessel are attached to the distal end of a guide wire or
guide wire-like tubing which allows the filtering device to be
placed in the patient's vasculature when the guide wire is
manipulated in place. Once the guide wire is in proper position in
the vasculature, the embolic filter can be deployed within the
vessel to capture embolic debris. The guide wire can then be used
by the physician to deliver interventional devices, such as a
balloon angioplasty dilatation catheter or a stent, into the area
of treatment.
[0012] While expandable filters placed on the distal end of a guide
wire or guide wire like catheter are generally capable of reaching
many stenosis in a patient's vasculature, there still can be some
instances encountered by a physician in which the guide wire cannot
reach or cross a particularly tight distal lesion. This can
sometimes occur when the expandable filter device is to be placed
across a tight lesion in the distal carotid arteries when a femoral
approach is taken by the physician. In those cases, the physician
often can steer the filter device to a location close to the area
of treatment, but cannot cross the lesion for one reason or
another. Some physicians deal with this situation by removing the
filter device from the patient's vasculature and attempting to
cross the lesion using a separate guide wire which can be used to
somewhat straighten the body vessel, making it easier for the
physician to re-attempt the placement of the filter device across
the lesion. In such cases, the physician is required to maneuver
the steerable filter device back to the area of treatment to
re-attempt the crossing of the lesion. The filter device may be
then able to cross the lesion and be placed downstream of the area
of treatment to capture any embolic debris which can may be created
during the subsequent interventional procedure. However, this
procedure causes the physician to perform additional steps which
are time-consuming due to the increased number of times that the
physician has to maneuver the filtering device and additional guide
wire into the patient's vasculature.
[0013] What has been needed is a reliable system for use with an
expandable filter device which allows the physician to steer
through tortuous anatomy to distal lumens where the filtering
device can be deployed to capture or remove embolic debris from the
bloodstream. The system should be relatively easy for a physician
to use and should provide a suitable delivery system for placing a
filtering device into distal and tight lesions of a patient's
anatomy. Moreover, the system should be relatively easy to deploy
and remove from the patient's vasculature. The invention disclosed
herein satisfies these and other needs.
SUMMARY OF THE INVENTION
[0014] The present invention provides a delivery system which can
be utilized to place an expandable filter device past a distal
lesion in a patient's vasculature in order to capture embolic
debris which may be created during the performance of a therapeutic
intereventional procedure, such as a balloon angioplasty or
stenting procedure, in order to prevent embolic debris from
entering the bloodstream and blocking vessels downstream from the
area of treatment. The present invention can be used in conjunction
with either a steerable or non-steerable expandable filtering
device. The present invention eliminates the need for a physician
to remove and re-insert the expandable filtering device in the
patient since a separate guide wire is utilized to reach the
desired area of treatment. The system creates an over-the-wire
delivery system for placing the expandable filter device in the
area of treatment. As a result, the present invention should
eliminate additional steps when placing an expandable filtering
device into certain distal locations in a patient's
vasculature.
[0015] In one aspect of the present invention, a dual lumen
delivery sheath is used with an expandable filter device and a
separate guide wire as the delivery system. The dual lumen delivery
sheath can be made from an elongate tubular member which is adapted
to receive both the expandable filter device and the guide wire
which can be used as a primary component for placing the filtering
device into the area of treatment. In one aspect of the present
invention, two separate lumens are formed in the delivery sheath,
one for receiving the expandable filtering device and the other for
the primary guide wire. In this arrangement, the primary guide wire
is extendable within its own separate lumen so that it can be
maneuvered by the physician through the tortuous anatomy of the
patient into the area of treatment. The delivery sheath can be
placed into the area of treatment using over-the-wire techniques
which places both the delivery sheath and the expandable filter
device past the lesion to be treated.
Thereafter, the primary guide wire can be removed from the
patient's vasculature with the delivery sheath and expandable
filter device remaining in place downstream from the area of
treatment. The delivery sheath can then be retracted to allow the
expandable filter device to move into its expanded condition within
the body lumen where it will be deployed for capturing any embolic
debris which may be collected during the subsequent interventional
procedure. If the filter device is mounted on its own guide wire,
an interventional device can be delivered into the area of
treatment using over-the-wire techniques.
[0016] In another aspect of the invention, the guide wire lumen
extends along the entire length of the delivery sheath.
Alternatively, a rapid exchange type delivery sheath can be created
which utilizes only a short segment which receives the primary
guide wire. Usually, the guide wire segment is located at the
distal end of the delivery sheath to ensure that both the distal
ends of the sheath and filter device will properly track along the
primary guide wire. In another aspect of the present invention, the
distal end of the filter lumen has a smaller diameter than the
collapsed filter device to prevent the filter device from entering
into the guide wire lumen until the expandable filter device is
ready to be deployed within the patient's vasculature. This narrow
lumen helps prevent the primary guide wire and filter device from
possibly becoming "tangled" during delivery with the patient's
vasculature. The narrow portion of the lumen should not affect the
ability of the sheath to be retracted over the collapsed filter
device since the narrower lumen should stretch somewhat over the
filter device. Alternatively, the narrow portion of the sheath may
be scored or provided with one or more lines of perforations which
will cause the sheath to split a controlled amount making it easier
to retract the sheath over the filter device.
[0017] The filter lumen of the present invention also can be made
from a short segment to create a rapid exchange type delivery
sheath. In one aspect, the filter lumen would be created from a
short segment formed adjacent to the guide wire lumen. In an
alternative design, both the guide wire lumen and filter lumen
could be short segments forming a rapid exchange type sheath. The
sheath could be mounted to a mandrel or third wire which would be
used to retract the sheath from the expandable filter.
[0018] The delivery sheath made in accordance with the present
invention also can be provided with a slit extending substantially
along the length of the sheath to provide a slotted exchange sleeve
which facilitates exchanges of the delivery sheath during use. As a
result, the time needed to remove the delivery sheath from the
patient's vasculature can be reduced.
[0019] In an alternative delivery design, the primary guide wire
can be utilized in accordance with an expandable filter device
which utilizes an obturator for delivering the filter device within
the patient's vasculature. An obturator is generally a tapered tip
made from a soft pliable material which creates an atraumatic tip
which helps prevent trauma from being inflicted on the walls of the
patient's vasculature as the filter device is being steered
therethrough. In this aspect of the present invention, the
obturator is equipped with a lumen through which the primary guide
wire can extend to provide an over-the-wire delivery system that is
easy to operate. The guide wire lumen on the obturator could be
either set off center from the distal tip of the obturator or could
extend substantially through the center portion of the distal tip
of the obturator. In use, including its own delivery sheath, rides
over the primary guide wire (via the guide lumen of the obturator)
and into the desired area of deployment within the patient's
vasculature.
[0020] These and other inventions of the present invention will
become more apparent from the following detailed description, when
taken in conjunction with the accompanying exemplary drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is an elevational view, partially in cross-section,
of one embodiment of a dual lumen delivery sheath embodying
features of the present invention showing an expandable filtering
device held in its collapsed position within the delivery sheath
along with a primary guide wire extended within the guide wire
lumen.
[0022] FIG. 2 is an exploded elevation view of the expandable
filter device of FIG. 1 which depicts just one type of filter
device that can be used with the present invention.
[0023] FIG. 3A is a cross-sectional view of the dual lumen delivery
sheath of FIG. 1 taken along lines 3-3.
[0024] FIG. 3B is a cross-sectional view of another configuration
of a dual lumen delivery sheath made in accordance with the present
invention.
[0025] FIG. 4 is an elevational view, partially in cross-section
showing the delivery sheath and expandable filter device of FIG. 1,
along with the primary guide wire placed past a stenosis located in
a body vessel.
[0026] FIG. 5 is an elevational view, partially in cross-section,
showing the dual lumen delivery sheath of the present invention
placed across the stenosis in the body vessel.
[0027] FIG. 6 is an elevational view, partially in cross-section,
showing the dual lumen delivery sheath of the present invention
retracted past the expandable filter device allowing the filter
device to move into its expanded position within the body
vessel.
[0028] FIG. 7 is an elevational view, partially in cross-section,
showing the distal end of a rapid-exchange embodiment of a dual
lumen delivery sheath made in accordance with the present
invention.
[0029] FIG. 8 is an elevational view showing a perforation or score
line located on the dual lumen delivery sheath which aids in
retracting the sheath over the collapsed filter device.
[0030] FIG. 9 is an elevational view, partially in cross-section,
showing another embodiment of a delivery system made in accordance
with the present invention.
[0031] FIG. 10 is an elevational view, partially in cross-section,
showing another embodiment of a delivery system made in accordance
with the present invention.
[0032] FIG. 11 is an elevational view, partially in cross-section,
showing another embodiment of a dual lumen delivery sheath made in
accordance with the present invention.
[0033] FIG. 12 is a cross-sectional view of the dual lumen delivery
sheath of claim 11 taken along lines 12-12.
[0034] FIG. 13 is an elevational view, partially in cross-section,
showing another embodiment of a dual lumen delivery sheath made in
accordance with the present invention.
[0035] FIG. 14 is an elevation view, partially in cross-section,
showing another embodiment of a delivery system made in accordance
with the present invention.
[0036] FIG. 15 is a cross-sectional view of the delivery system of
FIG. 14 taken along lines 15-15.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] Turning now to the drawings, in which like reference
numerals represent like and corresponding elements in the drawings,
FIG. 1 represents a dual lumen delivery sheath 10 incorporating
features of the present invention. In the particular embodiment
shown in FIG. 1, the dual lumen delivery sheath 10 is adapted to
receive both an expandable filter device 12 and a primary guide
wire 14. The delivery sheath 10 includes a pair of lumens, namely,
a filter lumen 16 which is adapted to receive the expandable filter
device 12 and a guide wire lumen 18 which receives the primary
guide wire 14. As is shown in FIGS. 4-6, the delivery sheath 10 can
be placed within an artery 20 or other blood vessel of a patient.
This portion of the artery 20 has an area of treatment 22 in which
arthroscopic plaque 24 has built up against the inside wall 26 of
the artery 20. In use, the filter device 12 is to be placed distal
to, and downstream from, the area of treatment 22, as shown in FIG.
6. Methods for deploying the system of FIG. 1 will be described in
greater detail below.
[0038] The present invention is described herein in conjunction
with a self-expanding filter device 12 which is capable of
self-expanding from a contracted or collapsed position to an
expanded or deployed position within the patient's vasculature. The
filter lumen 16 of the delivery sheath 10 is thus utilized to
maintain the expandable filter device 12 in its collapsed state for
delivery into the patient's vasculature. Later, when the device is
to be deployed at the particular location downstream from the area
of treatment, the sheath 10 is retracted to allow the filter device
to expand to its open or expanded position within the body vessel.
It should also be appreciated that other types of expandable filter
devices could be used in conjunction with the present invention in
order to deliver the filter device to the desired location in a
patient's vasculature. Additionally, the filter device need not be
self-expanding, but could utilized mechanical components to open
and close the filter as desired. For that reason, the type of
filter device utilized in accordance with the present invention can
include a number of different embodiments and is not limited to the
particular filter device disclosed herein.
[0039] As can be seen best in FIG. 2, one particular type of filter
device 12 which can be used with the present invention is shown
mounted on a separate guide wire 28 that can be utilized by the
physician to introduce interventional devices into the area of
treatment. This expandable filter device 12 includes an expandable
filtering assembly 30 having an expandable strut assembly 32
consisting of a number of struts 34 which expand radially outward
to open a filter 36 that is attached to the strut assembly 32.
[0040] As can be seen in FIGS. 1 and 2, the expandable strut
assembly 32 is attached to the guide wire 28 at its proximal collar
38 which is fixed between two stop fittings 40 and 42. This allows
the distal collar 44 of the strut assembly to move axially along
the guide wire 28 and allows the struts 34 to expand and collapse
as needed. This arrangement also allows the filter assembly to spin
on the guide wire 28. Attached to the distal end of the strut
assembly 30 is an obturator 46 which provides an atraumatic tip
which prevents trauma from being inflicted on the walls of the
patient's vasculature. The obturator 46 is bonded or otherwise
attached to the filtering assembly 30.
[0041] In one particular procedure in using the present invention,
a balloon angioplasty catheter (not shown), for example, can be
introduced within the patient's vasculature in a conventional
SELDINGER technique through a guide wire catheter (not shown). The
guide wire 28 of the deployed filter device 12 would be disposed
through the area of treatment and the dilitating catheter can be
advanced over the guide wire 28 within the artery until the balloon
portion is directly in the area of treatment. The balloon of the
dilitation catheter can be expanded, expanding the plaque and
artery to create a larger opening in the area of treatment to
reduce the blockage in the vessel at the position of the plaque and
increase blood flow. After the dilitating catheter is removed from
the patient's vasculature, a stent could also be delivered into the
area of treatment using over-the-wire techniques to help hold and
maintain this portion of the artery and help prevent re-stenosis
from occurring in the area of treatment. Any embolic debris which
is created during the intereventional procedure will be released
into the blood stream and will enter the filtering assembly located
downstream from the area of treatment. Once the procedure is
completed, the filter device 12 can be collapsed and removed from
the patient's vasculature, taking with it all embolic debris
trapped within the filter 36.
[0042] Although the procedure described herein is directed to an
angioplasty and stenting procedure which can be performed in the
patient's vasculature utilizing the present invention, it should be
appreciated to those skilled in the art that any one of a number of
interventional procedures could be utilized in the area of
treatment as well. For example, laser angioplasty, atherectomy and
still other interventional procedures could be performed in the
area of treatment utilizing the present invention. Moreover, the
present invention can be utilized in a number of other body vessels
including, but not limited to, the coronary arteries, renal
arteries, saphenous vein grafts and other peripheral arteries.
[0043] Referring now to FIGS. 4-6, one method of utilizing the
present invention is herein disclosed. The dual lumen delivery
sheath 10 of the present invention can be introduced with the
filter device placed in its collapsed position within the artery 20
in which the interventional procedure is to be performed.
Initially, the primary guide wire 14 is placed within the patient's
vasculature and is maneuvered by the physician into the area of
treatment 20. As is shown in FIG. 4, the primary guide wire 14 is
maneuvered past the area of treatment 22 to a downstream location
where the filter device will be deployed. After the primary guide
wire is in place, the delivery sheath and filter device can be
backloaded onto the proximal end of the guide wire. The physician
can then move the delivery sheath 10 and the filter device 12 over
the primary guide wire 14 using over-the-wire techniques known in
the art. As can be seen in FIG. 5, the entire delivery sheath 10
and filter device 12 have been placed downstream from the area of
treatment 22 to the location where the filter device 12 is to be
deployed. Once the delivery sheath and filter device are in the
desired location, the physician can remove the primary guide wire
14 from the patient to allow the filter device 12 to expand within
the artery without any obstructions. As is shown in FIG. 6, the
primary guide wire 14 has been removed and the delivery sheath 10
has been retracted proximally to allow the expandable filter device
12 to move into its open or expanded position within the artery 20.
Thereafter, the entire delivery sheath 10 can be removed from the
guide wire 28 of the filter device 12 allowing interventional
devices to be positioned into the area of treatment 22 utilizing
over-the-wire techniques. In the event that any embolic debris is
created during the interventional procedure, the embolic debris
will be released into the blood stream where it should collect
within the filter element 36 of the filter device 12.
[0044] After the interventional procedure is completed, the
physician can remove the interventional device from the guide wire
28. Thereafter, the physician may wish to leave the filter device
12 in place in the artery to insure that all embolic debris
generated during the procedure is driven into the filter portion 36
of the filter device 12. Thereafter, once the physician is assured
that all embolic debris has been collected, he/she can then place
another sheath (not shown) over the guide wire 28 which would
contact the strut assembly 32 causing the struts and the filter to
move back to its collapsed position. Thereafter, the entire filter
device 12 could be collapsed within the sheath and removed from the
patient's vasculature.
[0045] Referring specifically now to FIGS. 1 and 8, the distal most
end of the delivery sheath 10 is shown. As can be seen in FIG. 1,
the filter lumen 16 extends into the guide wire lumen 18 near the
distal end to create a low profile component capable of reaching
distal and tight lesions. The distal end of the filter lumen 16 has
a region 48 with a diameter less than the diameter of the main
portion of the filter lumen 16. This particular configuration can
be utilized to create a small profile diameter at the distal most
end 50 of the delivery sheath 10 and to prevent the sheath from
"digging" or "snow plowing" into the artery walls as the delivery
sheath 10 is being delivered over the primary guide wire 14.
Otherwise, if the distal opening of the delivery sheath 10 is too
large, it is possible for the distal end to inflict trauma to the
artery walls as it is being pushed up through the anatomy.
Moreover, this reduced region 48 on the filter lumen 16 also helps
to prevent the filter device 12 from extending into the guide wire
lumen and prevent the coil tip 52 of the guide wire 28 from
becoming tangled with the primary guide wire 14 as the components
are being manipulated into the patient's vasculature.
[0046] This reduced diameter region 48 of the filter lumen 16
should not prevent the sheath from retracting over the filter
device 12 since the delivery sheath 10 can be made from a material
which will stretch somewhat as the sheath 10 is being retracted
over the filter device. However, this region 48 of the sheath 10
can be formed or scored with perforations 54 which extend
longitudinally along the sheath at this area and will cause the
sheath to split a controlled amount as the sheath 10 is being
retracted over the filter device 12. FIG. 8 shows one particular
way of scoring the lumen with perforations 54 which will open as
the reduced region 48 is being retracted over the filter device.
These perforations should assure that the sheath will be properly
retracted over the filter device.
[0047] Referring now to FIGS. 3A and 3B, it can be seen that the
guide wire lumen 18 can be formed within the interior of the
delivery sheath 10 as is shown in FIG. 3A or it could alternatively
be formed as a separate lumen which extends outside the filter
lumen 16 as is shown in FIG. 3B. It should be appreciated that
other configurations having lumens of different shapes and sizes
can be utilized in accordance with the present invention which
would not depart from the spirit and scope of the present
invention.
[0048] Referring now to FIG. 7, an alternative embodiment of a
delivery sheath 60 made in accordance with the present invention is
shown. In this particular embodiment, the delivery sheath includes
both a guide wire lumen 62 and a filter lumen 64, however, the
guide wire lumen 66 does not extend along the entire length of the
sheath 60 as does the previous embodiment described herein. Rather,
the guide wire lumen 62 is a short lumen incorporated into the
sheath 60 to create a rapid exchange type delivery sheath. This
particular sheath 60 has the same features of the embodiment
previously described and would be capable of delivering the filter
device 12 into the area of treatment in the same manner described
herein.
[0049] Referring now to FIGS. 9 and 10, an alternative delivery
system made in accordance with the present invention is shown. In
these particular figures, the primary guide wire 14 is not disposed
within the delivery sheath itself, but rather, is placed within a
lumen created within an obturator 70 located on the distal end of
the filter device 12. Referring initially first to FIG. 9, the
obturator 70 is shown having a guide wire lumen 72 which extends
within the obturator and receives the primary guide wire 14 during
use. This obturator 70 creates an atraumatic tip as it is made from
a soft material such as PEBAX or other soft polymeric material.
Again this obturator helps prevent trauma to the inner walls of the
patient's vasculature as the device is being delivered to the
target area. The obturator 70 is attached to the filter device 12
via the strut assembly 32 and the distal end of the guide wire 28.
This particular embodiment of the filter device 12 is substantially
similar to the filter device shown in FIG. 2. The major difference
is that the distal end of the guide wire 28 does not extend through
the obturator 70 as does in the filter device shown in FIG. 2.
Rather, the obturator 70 is attached to the strut assembly 32 and
the distal end of the guide wire 28. This allows the guide wire
lumen 72 to extend through the main portion of the obturator 70 and
out the center of the distal tip 74 of the obturator.
[0050] As can be seen in FIG. 10, the guide wire lumen 76 can
alternatively be placed off center from the obturator to create a
lumen which extends substantially parallel with the longitudinal
axis of the delivery sheath 78. However, both of these guide wire
lumens 72 and 76 perform the same function of providing a means for
delivering the filter device 12 into the desired area utilizing an
over-the-wire technique.
[0051] The delivery system shown in FIGS. 9 and 10 can be used in a
similar manner as described herein in that the primary wire would
be first positioned across the lesion. The filter device 12 can
then be backloaded onto the proximal end of the guide wire (via the
obturator) and advanced over the wire to cross the lesion. The
primary guide wire would then be removed and the sheath 78 would be
retracted to deploy the filter device 12 within the artery. Again,
interventional devices could be advanced over the guide wire 28 to
perform the interventional procedure. Thereafter, the filter device
could be collapsed by the restraining sheath and removed from the
patient's vasculature.
[0052] Referring now to FIGS. 11 and 12, an alternative embodiment
of a delivery sheath 80 made in accordance with the present
invention is shown. In this particular embodiment, the expandable
filter device 12 is placed within a filter lumen 16 and the primary
guide wire 14 is receivable within a guide wire lumen 18. The guide
wire lumen 18 includes a slit 82 and the filter lumen 16 includes a
slit 84 which both extend longitudinally along the tubular member
forming the sheath 80. The slit 84 of the filter lumen 16 can
extend along the length of the sheath 80 just proximal to the end
of the filter device 12. This will create and maintain a sheath
which will hold the filter device 12 in its expanded condition
until it is ready to be deployed by the physician. Thereafter, once
the filter device 12 has been deployed, the slit 84 will facilitate
the removal of the entire delivery sheath 80 from the patient's
vasculature. In like fashion, the slit 82 located along the length
of the guide wire lumen 18 could also be used to facilitate the
quick removal of the sheath in the event that the primary guide
wire 14 is to remain within the patient's vasculature. Thereafter,
an exchange of interventional devices can be quickly and easily
made. It should be appreciated that either of the guide wire lumen
or filter lumen could be provided with this longitudinal slit, or
both, and that such a longitudinal slit could be utilized with the
other embodiment disclosed herein.
[0053] Referring now to FIG. 13, a rapid exchange type dual lumen
delivery sheath 90 is shown which can be made in accordance with
the present invention. In this particular embodiment, the filter
lumen 92 is made from a short segment of tubing which creates a
pod-like container for storing the collapsed filter device 12 until
it is ready to be deployed. In use, the sheath portion which covers
the filter 12 can be moved by retracting the proximal end of the
guide wire lumen portion of the sheath as needed. This particular
configuration can also utilize perforations cut or scored into the
sheath, as shown in FIG. 8, in order to facilitate the easy
retraction of the sheath from the filter 12. Also, as can be seen
from FIG. 13, the proximal end of the filter lumen 92 has a
narrower diameter than the main portion of the lumen 92 in order to
help prevent the filter 12 from "backing out" of its sheath as it
is being delivered within the patient's vasculature. This narrowing
at the proximal region 94 does not interfere with the sheath's
ability to be drawn back and retracted over the filter device
12.
[0054] Referring now to FIG. 14, still another embodiment of the
present invention is shown in which the delivery sheath 100
includes a rapid-type exchange arrangement for both the filter
lumen 102 and the primary guide wire lumen 104. This particular
configuration enjoys the benefits of rapid exchange with regard to
both the filter device 12 and the primary guide wire 14. This
particular sheath 100 includes a third lumen 106 in which a mandrel
or third guide wire 108 is utilized to provide axial stiffness to
the structure as the sheath is being retracted past the collapsed
filter device 12. In this manner, a three-wire delivery system can
be utilized.
[0055] In use, the delivery sheath 100 and filter device 12 are
delivered into the target area in the same manner as described
above, namely, by moving along the primary guide wire 14 in a
over-the-wire fashion. The mandrel 108 is also deployed with the
delivery sheath 100 since it is adhesively fixed or bonded within
the lumen 106. Once the delivery sheath 100 reaches the area in
which the filter device 12 is to be deployed, the primary guide
wire 14 can then be removed from the patient's vasculature. The
sheath portion of the filter lumen 102 can be retracted over the
filter device to deploy it within the patient's vasculature by
pulling back on the proximal end of the mandrel 108. The entire
delivery sheath 110 can then be removed from the patient's
vasculature and the appropriate interventional devices can be
advanced into the target area via the guide wire 28 of the filter
device 12. The filter lumen 102 of the sheath 100 also includes a
proximal area 110 in which the diameter is reduced in order to
prevent the filter device 12 from backing out of the lumen 102
during usage. Again, this reduced diameter creates a composite
pod-like container for the collapsed filter 12 until it is ready to
be deployed within the patient's vasculature. The mandrel 108
utilized in accordance with the present invention can be any
mandrel well-known in the art or an alternative could be a guide
wire which is fixed within the lumen 106 of the delivery sheath
100. It should also be appreciated that the lumen 106 does not need
to extend all the way back to the proximal end of the mandrel 108,
but rather, it could terminate with the proximal end of the filter
lumen and guide wire lumen. Thus, a composite delivery sheath can
be created which provides a low profile device that can be easily
advanced into the patient's vasculature.
[0056] The obturator utilized in conjunction with the present
invention can be made from material such as PEBAX 40D, or other
polymeric materials or alloys which are capable of providing a soft
atromatic tip for the filter device. The material used to make the
obturator can be loaded with radiopaque materials, such as bismuth
or barium, which will help locate the tip of the device when using
visualization equipment during the procedure. The obturator can be
attached to the distal end of the strut assembly of the filter
device utilizing adhesive or other bonding techniques to provide a
strong bond between the components. The guide wire lumen formed in
the obturator can be mechanically drilled or drilled utilizing a
laser source.
[0057] The strut assemblies of the filter device can be made in
many ways. However, the one particular method of making the strut
assembly is to cut a thin-walled tubular member, such as
nickel-titanium hypotube, to remove portions of the tubing in the
desired pattern for each strut, leaving relatively untouched the
portions of the tubing which are to form each strut. The tubing may
be cut into the desired pattern by means of a machine-controlled
laser.
[0058] The tubing used to make the strut assembly may be made of
suitable biocompatible material such as stainless steel. The
stainless steel tube may be alloy-type: 316L SS, Special Chemistry
per ASTM F138-92 or ASTM F139-92 grade 2. Special Chemistry of type
316L per ASTM F138-92 or ASTM F139-92 Stainless Steel for Surgical
Implants in weight percent.
[0059] The strut size is usually very small, so the tubing from
which it is made must necessarily also have a small diameter.
Typically, the tubing has an outer diameter on the order of about
0.020-0.040 inches in the unexpanded condition. The wall thickness
of the tubing is about 0.076 mm (0.003-0.006 inches). For strut
assemblies implanted in body lumens, such as PTA applications, the
dimensions of the tubing maybe correspondingly larger. While it is
preferred that the strut assembly be made from laser cut tubing,
those skilled in the art will realize that the strut assembly can
be laser cut from a flat sheet and then rolled up in a cylindrical
configuration with the longitudinal edges welded to form a
cylindrical member.
[0060] Generally, the hypotube is put in a rotatable collet fixture
of a machine-controlled apparatus for positioning the tubing
relative to a laser. According to machine-encoded instructions, the
tubing is then rotated and moved longitudinally relative to the
laser which is also machine-controlled. The laser selectively
removes the material from the tubing by ablation and a pattern is
cut into the tube. The tube is therefore cut into the discrete
pattern of the finished struts. The strut assembly can thus be
laser cut much like a stent is laser cut. Details on how the tubing
can be cut by a laser are found in U.S. Pat. Nos. 5,759,192
(Saunders) and U.S. Pat. No. 5,780,807 (Saunders), which have been
assigned to Advanced Cardiovascular Systems, Inc.
[0061] The process of cutting a pattern for the strut assembly into
the tubing generally is automated except for loading and unloading
the length of tubing. For example, a pattern can be cut in tubing
using a CNC-opposing collet fixture for axial rotation of the
length of tubing, in conjunction with CNC X/Y table to move the
length of tubing axially relative to a machine-controlled laser as
described. The entire space between collets can be patterned using
the CO.sub.2 or Nd:YAG laser set-up. The program for control of the
apparatus is dependent on the particular configuration used and the
pattern to be ablated in the coding.
[0062] A suitable composition of nickel-titanium which can be used
to manufacture the strut assembly of the present invention is
approximately 55% nickel and 45% titanium (by weight) with trace
amounts of other elements making up about 0.5% of the composition.
The austenite transformation temperature is between about
-15.degree. C. and 0.degree. C. in order to achieve
superelasticity. The austenite temperature is measured by the bend
and free recovery tangent method. The upper plateau strength is
about a minimum of 60,000 psi with an ultimate tensile strength of
a minimum of about 155,000 psi. The permanent set (after applying
8% strain and unloading), is approximately 0.5%. The breaking
elongation is a minimum of 10%. It should be appreciated that other
compositions of nickel-titanium can be utilized, as can other
self-expanding alloys, to obtain the same features of a
self-expanding stent made in accordance with the present
invention.
[0063] The strut assembly of the present invention can be laser cut
from a tube of nickel-titanium (Nitinol) whose transformation
temperature is below body temperature. After the strut pattern is
cut into the hypotube, the tubing is expanded and heat treated to
be stable at the desired final diameter. The heat treatment also
controls the transformation temperature of the strut assembly such
that it is super elastic at body temperature. The transformation
temperature is at or below body temperature so that the stent is
superelastic at body temperature. The strut assembly is usually
implanted into the target vessel which is smaller than the diameter
if the strut assembly in the expanded position so that the struts
apply a force to the vessel wall to maintain the filter element in
the expanded position.
[0064] The strut assembly could be manufactured to remain in its
open position while at body temperature and would move to its
collapsed position upon application of a low temperature. One
suitable method to allow the strut assembly to assume a change
phase which would facilitate the strut and filter assembly being
mounted into the delivery sheath include chilling the filter
assembly in a cooling chamber maintained at a temperature below the
martensite finish temperature through the use of liquid nitrogen.
Once the strut assembly is placed in its collapsed state, the
restraining sheath can be placed over the device to prevent the
device from expanding once the temperature is brought up to body
temperature. Thereafter, once the filter device is to be utilized,
the delivery sheath is retracted to allow the filter assembly/strut
assembly to move to its expanded position within the patient's
vasculature.
[0065] The polymeric material which can be utilized to create the
filter element include, but is not limited to, polyurethane and
Gortex, a commercially available material. Other possible suitable
materials include ePTFE. The material can be elastic or
non-elastic. The wall thickness of the filtering element can be
about 0.0005-0.005 inches. The wall thickness may vary depending on
the particular material selected. The material can be made into a
cone or similarly sized shape utilizing blow-mold technology. The
perfusion openings can be any different shape or size. A laser, a
heated rod or other process can be utilized to create to perfusion
openings in the filter material. The holes, would of course be
properly sized to catch the particular size of embolic debris of
interest. Holes can be laser cut in a spiral pattern with some
similar pattern which will aid in the re-wrapping of the media
during closure of the vice. Additionally, the filter material can
have a "set" put in it much like the "set" used in dilatation
balloons to make the filter element re-wrap more easily when placed
in the collapsed position.
[0066] The materials which can be utilized for the delivery sheath
and can be made from similar polymeric material such as
cross-linked HDPE. It can alternatively be made from a material
such as polyolifin which has sufficient strength to hold the
compressed strut assembly and has relatively low frictional
characteristics to minimize any friction between the filtering
assembly and the sheath. Friction can be further reduced by
applying a coat of silicone lubricant, such as Microglide.RTM. or
Dow 360, to the inside surface of the restraining sheath before the
sheaths are placed over the filtering assembly.
[0067] In view of the foregoing, it is apparent that the system and
device of the present invention substantially enhance the safety of
performing certain interventional procedures by significantly
reducing the risks associated with embolic material being created
and released into the patient's bloodstream. Further modifications
and improvements may additionally be made to the system and method
disclosed herein without departing from the scope of the present
invention. Accordingly, it is not intended that the invention be
limited, except as by the appended claims.
* * * * *