U.S. patent application number 10/664490 was filed with the patent office on 2004-12-30 for embolic protection devices.
Invention is credited to Boylan, John F., Boyle, William J., Denison, Andy E., Dutta, Debashis, Huter, Benjamin C., Huter, Scott J., Muller, Paul F., Patel, Samir, Sanchez, Francisco, Stalker, Kent C.B., Tarapata, Christopher J., Wang, Chicheng.
Application Number | 20040267301 10/664490 |
Document ID | / |
Family ID | 29406993 |
Filed Date | 2004-12-30 |
United States Patent
Application |
20040267301 |
Kind Code |
A1 |
Boylan, John F. ; et
al. |
December 30, 2004 |
Embolic protection devices
Abstract
An embolic protection device for use in a blood vessel when an
interventional procedure is being performed in a stenosed or
occluded region to capture any embolic material which may be
created and released into the bloodstream during the procedure. The
device includes a filtering assembly having a self-expanding strut
assembly and a filter element attached thereto. In one embodiment,
the filtering assembly is attached to the distal end of a guide
wire and is deployed within the patient's vasculature as the guide
wire is manipulated into the area of treatment. A restraining
sheath placed over the filtering assembly in a coaxial arrangement
maintains the filtering assembly in its collapsed position until it
is ready to be deployed by the physician. Thereafter, the sheath
can be retracted to expose the filtering assembly which will then
self-expand within the patient's vasculature. Interventional
devices can be delivered over the guide wire and any embolic debris
created during the interventional procedure and released into the
blood stream will enter the filtering assembly and be captured
therein. Other embodiments include filtering assemblies attached to
an outer tubular member and inner shaft member which apply axial
force to the distal ends of the assembly to either expand or
contract the struts as needed.
Inventors: |
Boylan, John F.; (Murrieta,
CA) ; Boyle, William J.; (Fallbrook, CA) ;
Denison, Andy E.; (Temecula, CA) ; Dutta,
Debashis; (Santa Clara, CA) ; Huter, Benjamin C.;
(Murrieta, CA) ; Huter, Scott J.; (Temecula,
CA) ; Muller, Paul F.; (San Carlos, CA) ;
Patel, Samir; (Del Mar, CA) ; Tarapata, Christopher
J.; (North Andover, MA) ; Wang, Chicheng;
(Highland Park, NJ) ; Sanchez, Francisco;
(Temecula, CA) ; Stalker, Kent C.B.; (San Marcos,
CA) |
Correspondence
Address: |
FULWIDER PATTON LEE & UTECHT, LLP
HOWARD HUGHES CENTER
6060 CENTER DRIVE
TENTH FLOOR
LOS ANGELES
CA
90045
US
|
Family ID: |
29406993 |
Appl. No.: |
10/664490 |
Filed: |
September 17, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10664490 |
Sep 17, 2003 |
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09727102 |
Nov 28, 2000 |
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6702834 |
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09727102 |
Nov 28, 2000 |
|
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09490319 |
Jan 24, 2000 |
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6540722 |
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09490319 |
Jan 24, 2000 |
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09476159 |
Dec 30, 1999 |
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6695813 |
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Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61F 2230/0006 20130101;
A61F 2002/015 20130101; A61F 2230/0067 20130101; A61F 2230/008
20130101; A61F 2002/018 20130101; A61F 2/01 20130101; A61F 2230/005
20130101 |
Class at
Publication: |
606/200 |
International
Class: |
A61M 029/00 |
Claims
1. An embolic protection device for capturing embolic debris
released into a body vessel of a patient, comprising: a shaft
member having a distal and a proximal end; and a filtering assembly
rotatably mounted on the shaft member near the distal end thereof,
the filtering assembly including an expandable strut assembly and a
filter attached to the strut assembly for capturing embolic debris,
the filtering assembly being mounted on an outer tubular member
which is coaxially disposed over an inner tubular member having a
length shorter than the outer tubular member, wherein one end of
the inner tubular member is adapted to abut against the stop
fitting located on the shaft member for limiting axial movement of
the filtering assembly along the guide wire.
2. The embolic protection device of claim 1, wherein: the shaft
member is a guide wire and includes a distal spring tip coil, the
spring tip coil serving as the stop fitting which abuts against the
inner tubular member.
3. The embolic protection device of claim 2, wherein: the guide
wire includes a second stop fitting in an abutting relationship
with the proximal ends of the outer and inner tubular members.
4. The embolic protection device of claim 2, wherein: the outer
tubular member extends over a portion of the spring tip coil of the
guide wire.
5. The embolic protection device of claim 2, wherein: the outer and
inner tubular members are made from polyimide.
6-31. (Canceled).
32. An embolic protection device for capturing embolic debris
released into the body vessel of a patient, comprising: a shaft
member having a distal end and a proximal end; a filtering element
mounted on the shaft member near the distal end thereof, the
filtering element including an expandable strut assembly and a
filter attached to the strut assembly for capturing embolic debris,
and a layer of polymeric material having a coefficient of friction
less than the coefficient of friction of the material of the strut
assembly deposited on at least part of the strut assembly proximal
to the filter.
33. The embolic protection device of claim 32, wherein: the
polymeric material is selected from the group consisting of PTFE,
polyimide, and heparin.
34. The embolic protection device of claim 32, wherein: the entire
strut assembly is coated with the polymeric material.
35. The embolic protection device of claim 34, wherein: the
polymeric material is selected from the group consisting of PTFE,
polyimide, and heparin.
36. An embolic protection device for capturing embolic debris
released into the body vessel of a patient, comprising: a shaft
member having a distal end and a proximal end; a filtering element
mounted on the shaft member near the distal end thereof, the
filtering element including an expandable strut assembly and a
filter attached to the strut assembly for capturing embolic debris,
the expandable strut assembly being movable between an expanded
position and an unexpanded position and having regions which
experience high strain and regions which experience low strain
during movement between the unexpanded position and the expanded
position; and a layer of polymeric material deposited on the
regions which experience low strain, the layer of polymeric
material having a coefficient of friction less than the coefficient
of friction of the material forming the strut assembly.
37. The embolic protection device of claim 36, wherein the
polymeric material is selected from the group consisting of PTFE
and polyimide.
38. An embolic protection device for capturing embolic debris
released into the body vessel of a patient, comprising: a shaft
member having a distal end and a proximal end; a filtering element
mounted on the shaft member near the distal end thereof, the
filtering element including an expandable strut assembly and a
filter attached to the strut assembly for capturing embolic debris,
and a coating made from a substance having a coefficient of
friction less than the coefficient of friction of the material
forming the strut assembly selectively deposited on portions of the
strut assembly proximal to the filter.
39. The embolic protection device of claim 38, wherein the coating
substance is a hydrophilic substance.
40. The embolic protection device of claim 38, wherein the coating
substance is heparin.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of Ser. No. 09/727,102
filed Nov. 28, 2000, which is a continuation-in-part of application
Ser. No. 09/490,319 filed Jan. 24, 2000, which is a
continuation-in-part of application Ser. No. 09/476,159 filed Dec.
30, 1999, which are assigned to the same assignee as the present
application.
BACKGROUND OF THE INVENTION
[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 embolic filtering devices
and systems of the present invention are particularly useful when
performing balloon angioplasty, stenting procedures, laser
angioplasty or atherectomy 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 devices and systems of the present invention are
particularly useful in carotid procedures, the inventions 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-titanium (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] Many 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. When a combination of embolic filter and guide wire
is utilized, the proximal end of a guide wire can be rotated by the
physician, usually unintentionally, when the interventional device
is being delivered over the guide wire in an over-the-wire fashion.
If the embolic filter is rigidly affixed to the distal end of the
guide wire, and the proximal end of the guide wire is twisted or
rotated, that rotation will be translated along the length of the
guide wire to the embolic filter, which can cause the filter to
rotate or move within the vessel and possibly cause trauma to the
vessel wall. Additionally, it is possible for the physician to
accidentally collapse or displace the deployed filter should the
guide wire twist when the interventional device is being delivered
over the guide wire. Moreover, a shockwave (vibratory motion)
caused by the exchange of the delivery catheter or interventional
devices along the guide wire can ajar the deployed filtering device
and can possibly result in trauma to the blood vessel. These types
of occurrences during the interventional procedure are undesirable
since they can cause trauma to the vessel which is detrimental to
the patient's health and/or cause the deployed filter to be
displaced within the vessel which may result in some embolic debris
flowing past the filter into the downstream vessels.
[0012] What has been needed is a reliable filtering device and
system for use when treating stenosis in blood vessels which helps
prevent the risk associated when embolic debris that can cause
blockage in vessels at downstream locations is released into the
bloodstream. The device should be capable of filtering any embolic
debris which may be released into the bloodstream during the
treatment and safely contain the debris until the filtering device
is to be collapsed and removed from the patient's vasculature. The
device should be relatively easy for a physician to use and should
provide a failsafe filtering device which captures and removes any
embolic debris from the bloodstream. Moreover, such a device should
be relatively easy to deploy and remove from the patient's
vasculature. The inventions disclosed herein satisfy these and
other needs.
SUMMARY OF THE INVENTION
[0013] The present invention provides a number of filtering devices
and systems for capturing embolic debris in a blood vessel created
during the performance of a therapeutic interventional procedure,
such as a balloon angioplasty or stenting procedure, in order to
prevent the embolic debris from blocking blood vessels downstream
from the interventional site. The devices and systems of the
present invention are particularly useful while performing an
interventional procedure in critical arteries, such as the carotid
arteries, in which vital downstream blood vessels can easily become
blocked with embolic debris, including the main blood vessels
leading to the brain. When used in carotid procedures, the present
invention minimizes the potential for a stroke occurring during the
procedure. As a result, the present invention provides the
physician with a higher degree of confidence that embolic debris is
being properly collected and removed from the patient's vasculature
during the interventional procedure.
[0014] An embolic protection device and system made in accordance
with the present invention includes an expandable filtering
assembly which is affixed to the distal end of a tubular shaft
member, such as a guide wire. The filtering assembly includes an
expandable strut assembly made from a self-expanding material, such
as nickel-titanium (NiTi) alloy or spring steel, and includes a
number of outwardly extending struts which are capable of
self-expanding from a contracted or collapsed position to an
expanded or deployed position within the patient's vasculature. A
filter element made from an embolic capturing media is attached to
the expandable strut assembly and moves from the collapsed position
to the expanded position via the movement of the expandable struts.
This expandable strut assembly is affixed to the guide wire in such
a manner that the entire filtering assembly rotates or "spins"
freely on the guide wire to prevent the filtering assembly from
being rotated after being deployed within the patient's
vasculature. In this manner, any accidental or intentional rotation
of the proximal end of the guide wire is not translated to the
deployed filtering assembly, which will remain stationary within
the patient's vasculature and, as such, the threat of trauma to the
vessel wall and displacement of the filter caused by the rotation
and/or manipulation of the guide wire can be virtually
eliminated.
[0015] The expandable struts of the strut assembly can be biased to
remain in their expanded position until an external force placed on
the struts to collapse and maintain the struts in their contracted
or collapsed position is removed. This is done through the use of a
restraining sheath which is placed over the filtering assembly in a
coaxial fashion to maintain the strut assembly in its collapsed
position. The composite guide wire and filtering assembly, with the
restraining sheath placed over the filtering assembly, can then be
placed into the patient's vasculature. Once the physician properly
manipulates the guide wire into the target area, the restraining
sheath can be retracted off of the expandable strut assembly to
deploy the struts into their expanded position. This can be easily
performed by the physician by simply retracting the proximal end of
the restraining sheath (which is located outside of the patient)
along the guide wire. Once the restraining sheath is retracted, the
self-expanding properties of the strut assembly cause the struts to
move radially outward away from the guide wire to contact the wall
of the blood vessel. Again, as the struts expand radially, so does
the filter element which will now be in place to collect any
embolic debris that may be released into the bloodstream as the
physician performs the interventional procedure. The filter
sub-assembly could be bonded to the core wire at both distal and
proximal ends of the embolic protection device. The core wire could
be made from stainless steel or shaped memory biocompatible
materials. The guide wire with the embolic protection device could
be loaded into a delivery sheath. The delivery sheath could be
torqued, steering the device into the intended vessel site.
[0016] The filtering assembly can be rotatably affixed to the guide
wire by rotatably attaching the proximal end of the filtering
assembly to the guide wire. The distal end of the strut assembly
can move longitudinally along the guide wire and is also rotatable
on the guide wire as well. This allows the strut assembly to move
between its collapsed and expanded positions while still allowing
the entire filtering assembly to freely rotate or "spin" about the
guide wire. This attachment of the proximal end of the strut
assembly to the guide wire allows the restraining sheath to be
retracted from the filtering assembly and permits a recovery sheath
to be placed over the expanded strut assembly to move the strut
assembly back to the collapsed position when the embolic protection
device is to be removed from the patient's vasculature.
[0017] The filtering assembly also may include a dampening element
or member which is utilized to absorb some of the shockwave
(vibratory motion) that may be transmitted along the length of the
guide wire during the handling of the guide wire by the physician.
Since a sudden shock to the filtering assembly can cause the filter
to scrape the wall of the blood vessel or become displaced in the
vessel, the dampening member acts much like a "shock absorber" to
absorb some of the shock and prevent the transmission of the shock
force to the filtering assembly. This shock can be produced via a
number of ways, for example, through the exchange of interventional
devices along the guide wire. Also, when the restraining sheath is
removed from the filtering assembly, a shockwave can be created if
the self-expanding struts open too quickly. As a result of
utilizing the dampening member, shock and trauma to the patient's
vasculature are minimized and the chances of displacing the filter
are virtually eliminated. In one aspect of the dampening member, a
helical spring is formed on the proximal end of the expandable
strut assembly to provide dampening to the assembly. Other methods
of obtaining dampening can be utilized, such as attaching a
separately formed spring or elastomeric member to the strut
assembly.
[0018] The expandable strut assembly made in accordance with the
present invention may be made from a length of tubing (also known
as a "hypotube") made from a shape memory alloy or other
self-deploying material. Stainless steel or other biocompatible
metals or polymers can be utilized to form the struts of the
assembly. Another material is nickel-titanium (NiTi). The
individual struts of the expandable strut assembly are formed on
the length of hypotube by selectively removing material from the
tubing to form the particular size and shape of the strut. For
example, the wall of the hypotube can be laser cut with slots to
form the individual struts. Small tabs can also be lazed into the
tubing along the strut which can be used to hold the filter member
in place. By selectively removing portions of the hypotube by a
high precision laser, similar to lasers utilized in the
manufacturer of stents, one can achieve a very precise and well
defined strut shape and length. In one aspect of the present
invention, the pattern of the material to be removed from the
hypotubing can be a repeating diamond-shaped which creates a strut
pattern in the form of two inverted triangles meshed together. This
particular strut pattern provides greater strength along the strut
where it would have a tendency to break or become weakened. Such a
strut pattern also provides for a more natural bending position for
each strut, allowing the expandable strut assembly to open and
close more uniformly. In one particular pattern, the strut pattern
requires the removal of a repeating truncated diamond pattern by
laser or other means to create the shape of the strut. In this
particular pattern, each strut has a relatively straight center
section formed between two inverted triangles, somewhat similar to
the strut pattern described above. This particular strut pattern
provides an expanded center section which allows the struts to
expand to a greater volume, which helps in the capture of emboli by
allowing a larger filter to be placed on the strut assembly. The
center section located between the two inverted triangles also
provides a sufficient working area to attach the filter element
onto the strut assembly. These same features can be accomplished by
curved sections which have a reduced width in the center
section.
[0019] The embolic protection device may also include a filtering
assembly with a strut assembly which is not self-expanding, but
utilizes the application of a force on the proximal and distal ends
of the strut assembly to deploy and collapsed the assembly. In this
particular form of the invention, the embolic protection device
includes an inner shaft member and an outer tubular member which is
coaxially disposed over the inner shaft member. The distal end of
the expandable strut assembly can be attached to the inner shaft
member with the proximal end of the strut assembly being attached
to the distal end of the outer tubular member. When there is
relative movement between the inner shaft member and outer tubular
member, a force is created which is imparted to the expandable
strut assembly to cause the struts to either contract or expand.
For example, when the outer tubular member and inner shaft member
are moved relative to each other to produce an inward force acting
on the proximal and distal ends of the strut assembly, the force
causes the expandable struts to move from the collapsed position
into the expanded position. Thereafter, when the strut assembly is
to be collapsed, the outer tubular member and inner shaft member
can be moved relative to each other to create an outward force
acting on the proximal and distal end of the strut assembly to
cause the expanded struts to move back to their collapsed position.
A physician easily can manipulate the proximal ends of the inner
shaft member and outer tubular member to deploy and collapse the
filtering assembly as needed. The filtering assembly could be
self-expanding with the movement of the inner and outer members
providing the means for expanding and collapsing the assembly
without the need for an outer sheath.
[0020] The inner shaft member can be a guide wire which can be
utilized to move the filtering assembly directly into position
downstream from the lesion for capturing any embolic debris which
may be released into the bloodstream. The inner shaft member could
also be an elongated tubular member which has an inner lumen that
can track along a guide wire once the guide wire has been
maneuvered into position into the patient's vasculature. The entire
embolic protection device can then be delivered to the desired
location over the guide wire using over-the-wire techniques.
[0021] The filtering element utilized in conjunction with the
embolic protection device can take on many different forms as are
disclosed herein. In one aspect, the filter includes a proximal
cone section which expands to the diameter of the artery in which
the embolic protection device is to be deployed. This proximal cone
section funnels blood flow and embolic debris into a main or
central filter located distal to the proximal cone section. This
proximal cone may or may not provide filtering itself. Its primary
function is flow direction and its ability to collapse and expand
with the expandable struts of the strut assembly. A main or central
filter may comprise an elongated tubular shaped member is located
distal to the proximal cone section. It is integral with the distal
end of the proximal cone section and provides a large filtering
area that acts as a storage reservoir for holding embolic material.
Ideally, it is sized so that it receives any and all of the embolic
material which it is to be filtered by the embolic protection
device. It includes a number of perfusion openings which allow
blood to pass through but retain embolic material. The central
filter may not be collapsible or expandable, but rather may be made
somewhat rigid and has an outer diameter large enough to provide a
storage reservoir for holding embolic material yet can be withdrawn
and delivered through the particular guiding catheter utilized to
deploy the embolic protection device into the patient's
vasculature. The central filter also could be made from collapsible
material, but should have an outer diameter which is large enough
to provide an adequate storage reservoir yet can be withdrawn
through the guiding catheter as well. Although this central filter
may have a substantially fixed diameter, it can also be tapered and
should have an outer diameter small enough to fit through the inner
diameter of the specific guiding catheter utilized to deploy the
device.
[0022] As with all of the filter elements made in accordance with
the present invention, the material which can be utilized includes
a variety of materials such as polymeric material which is foldable
and recovers elastically to aid in the capture of the emboli
trapped in the filter. Other suitable materials include braided or
woven bio-compatible material which can significantly filter the
desired size of the embolic debris to be captured by the filter.
The filter can be formed by blowing a suitable material into the
proposed shape and then cutting off unwanted portions. The
perfusion openings can be drilled into the material using a laser,
such as an excimer laser, or by mechanically drilling and punching
the openings to the desired size and shape. Laser drilling of the
holes provides accuracy, quickness and the ability to drill complex
hole shapes, circles, ovals and slots. Alternatively, the central
filter can be made from the same or different material from the
proximal cone portion and can be welded or bonded to create an
integral unit.
[0023] Still another type of filter material can be utilized in
accordance with the present invention which does not require the
use of mechanical drilling or laser cutting to create the precise
openings in the filter which allows adequate blood perfusion while
capturing the desired size of embolic debris. This filtering
material utilizes an open-celled microporous structure which has
uniform porosity and a network-like structure which traps embolic
particles. Such filtering material has the benefit of being both
mechanically strong and more tear resistant while being most
effective in trapping embolic debris since the particles must
travel through an intricate network of patterns in order to escape
through the filter. Due to the open-celled microporous structure,
the probability that embolic debris will somehow escape through the
structure is extremely minimal.
[0024] The method for making this open-celled microporous filtering
material consists of dissolving a selected polymer into a solvent
to produce a polymer/solvent solution. This polymer/solvent
solution is then cast or sprayed as a film into the desired shape
and thickness. For example, the film can be cast onto a cone-shaped
rotating mandrel which improves the uniformity of the film
thickness. Then, a non-solvent is cast or sprayed onto the film
before complete evaporation of the solvent. This non-solvent
induces a phase-separation of the polymer to create the microporous
structures. The resulting microporous material can then be placed
onto the strut assembly to create the composite emboli-catching
device.
[0025] In one particular filter made in accordance with the present
invention, the proximal cone includes advantageous features which
help prevent the filter from slipping off the expandable strut
assembly. These features also help to prevent trapped embolic
debris from being squeezed out of the filter as the filter is being
collapsed for removal from the patient's vasculature. The filter
may include, for example, a set of restraining straps designed to
be attached to each of the proximal ends of the struts to help
secure the filter onto the strut assembly. These straps can include
tabs which can be wrapped around each of the struts and permanently
affixed thereto utilizing a suitable adhesive. The proximal cone
section of the filter may also include a number of indented flaps
which cooperate to close off the inlet opening of the central
filter. These indented flaps are formed on the proximal cone and
move into position to cover the opening of the central filter when
the proximal cone section is collapsed by the strut assembly.
Therefore, the possibility that any embolic debris trapped within
the deep reservoir of the central filter will be discharged through
the inlet opening is greatly diminished since the opening will be
closed off by these indented flaps. Likewise, the proximal cone
section of the filter can also include inwardly inverting flaps
located near the inlet opening of the proximal cone section which
cooperate to close off the large inlet opening of the proximal cone
section whenever the strut assembly is collapsed. These elements
help to prevent accidental leakage of trapped embolic debris
whenever the filtering assembly is collapsed for removal from the
patient.
[0026] In other aspects of the present invention, variations can be
made to the devices described above which enhance their performance
characteristics. For example, a strut assembly can be utilized
which utilizes struts having different lengths which allows greater
ease in re-sheathing the expanded strut/filter assembly since the
filter and struts can be incrementally introduced into the
restraining sheath, rather than having the struts and filter
material enter the sheath all at once. Likewise, the filter itself
can be made with a proximal edge which has a scalloped pattern
which helps prevent the filter material from entering into the
sheath all at once. As a result, the filtering assembly can be more
easily retracted by the recovery sheath and collapsed to its
smaller profile when the device is to be removed from the patient's
vasculature.
[0027] Other advantages associated with the present invention
include the placement of a surface coating on the strut of the
strut assembly for reducing the coefficient of friction at selected
areas of the strut assembly to help prevent possible embolic
material from sticking to struts. Embolic debris which does not
make its way into the filter and becomes "stuck" on proximal struts
of the filter assembly can possibly be released into the
bloodstream when the filter assembly is being collapsed and
withdrawn from the patient's vasculature. In one aspect, selective
deposition of a slippery polymer to the proximal struts of the
strut assembly can be utilized to reduce the coefficient of
friction between the embolic debris and the struts. This helps
allow the embolic material to be less likely to stick on a strut
assembly and more likely to pass into the filter. High areas of
strain of the strut assembly may cause the coating material to
crack if the coating is not sufficiently elastic. Additionally,
high strain regions of the device would not be coated if the
coating would affect the performance of the expansion of the strut
assembly. Such materials include polyimide and PTFE coatings, which
can be applied to a strut assembly without affecting the mechanical
properties of the base material. In another aspect of the
invention, a coating of "slippery" polymer deposited on the entire
strut assembly provided that the polymer was sufficiently elastic
so as not to crack or affect the ability of the struts to bend
throughout the device.
[0028] These and other advantages of the present invention will
become more apparent from the following detailed description of the
invention, when taken in conjunction with the accompanying
exemplary drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is an elevational view, partially in cross section,
of an embolic protection device embodying features of the present
invention showing the expandable filtering assembly in its
collapsed position within a restraining sheath and disposed within
a vessel.
[0030] FIG. 2 is an elevational view, partially in cross section,
similar to that shown in FIG. 1, wherein the expandable filtering
assembly is in its expanded position within the vessel.
[0031] FIG. 3 is a perspective view of the strut assembly which
forms part of the filtering assembly of the present invention as
shown in its collapsed position.
[0032] FIG. 4 is a plan view of a flattened section of the
expandable strut assembly shown in FIG. 3 which illustrates one
particular strut pattern for the expandable strut assembly.
[0033] FIG. 5 is a perspective view of another embodiment of an
expandable strut assembly which forms part of the filtering
assembly of the present invention in its collapsed position.
[0034] FIG. 6 is a plan view of a flattened section of the
expandable strut assembly of FIG. 5 which shows an alternative
strut pattern for the expandable strut assembly.
[0035] FIG. 7 is an elevational view, partially in cross section,
of the proximal end of the expandable strut assembly of FIG. 2 as
it is rotatably attached to the guide wire.
[0036] FIG. 8 is an elevational view, partially in section and
fragmented, showing the distal end of the filtering assembly of
FIG. 2 as it is slidably mounted on the guide wire.
[0037] FIG. 9 is a perspective view of another embodiment of an
embolic protection device made in accordance with the present
invention.
[0038] FIG. 10 is an elevational view of the various components
making up the embolic protection device of FIG. 9.
[0039] FIG. 11 is an elevational view of the embolic protection
device of FIG. 9 in its expanded position.
[0040] FIG. 12 is an end view of the filter element of the embolic
protective device of FIG. 11 taken along lines 12-12.
[0041] FIG. 13 is an end view of the filtering element of FIG. 12
which shows the retaining tabs of the filter prior to being wrapped
around the struts of the expandable strut assembly to help retain
the filer element on the strut assembly.
[0042] FIG. 14 is an end view, similar to that shown in FIG. 12, of
another embodiment of the filter element of the embolic protection
device which shows an alternative embodiment of retaining tabs and
structural elements that can be used to help retain the filter
element on the strut assembly.
[0043] FIG. 15 is an end view of the filter element of FIG. 14,
showing the retaining tabs of the filter element prior to being
wrapped around the struts of the expandable strut assembly to help
retain the filter element on the strut assembly.
[0044] FIG. 16 is a cross sectional view of the central filter of
the filtering device of FIG. 11 taken along lines 16-16.
[0045] FIG. 17 is an elevational view, partially in cross-section
and fragmented, of the embolic protection device of FIG. 11 showing
the indented flaps of the proximal cone section in the expanded
position.
[0046] FIG. 18 is an elevational view, partially in cross-section
and fragmented, showing the indented flaps of the proximal cone
section in the collapsed position which causes the indented flaps
to close the inlet opening of the central filter of the device.
[0047] FIG. 19 is a perspective view of an embolic protection
device made in accordance with the present invention which includes
inverted flaps which help close the inlet opening of the proximal
cone section of the filter element when the device is
collapsed.
[0048] FIG. 20 is an elevational view, partially in cross-section
and fragmented, of the embolic protection device of FIG. 19 showing
the proximal cone section and inverted flaps in an expanded
position.
[0049] FIG. 21 is an elevational view, partially in cross-section
and fragmented, of the embolic protection device of FIG. 19 wherein
the proximal cone section is collapsed which causes the inverted
flaps to close off the inlet opening of the proximal cone section
of the filter element.
[0050] FIG. 22 is a perspective view of an alternative embodiment
of a filter element made in accordance with the present
invention.
[0051] FIG. 23 is an elevational view of the various components
which make up another embodiment of an embolic protection device
made in accordance with the present invention.
[0052] FIG. 24 is an elevational view depicting the embolic
protection device of FIG. 23 in the expanded position.
[0053] FIG. 25 is an elevational view of the various components
which make up another embodiment of an embolic protection device
made in accordance with the present invention.
[0054] FIG. 26 is an elevated view depicting the embolic protection
device of FIG. 25 in the expanded position.
[0055] FIG. 27 is an elevational view, partially in section,
depicting the embolic protection device of FIG. 25 in a collapsed
position and disposed within a vessel.
[0056] FIG. 28 is an elevational view, partially in section,
similar to that shown in FIG. 27, wherein the embolic protection
device is expanded within the vessel.
[0057] FIG. 29 is another embodiment of an embolic protection
device made in accordance with the present invention.
[0058] FIG. 30 is an elevational view, partially in section, of the
embolic protection device of FIG. 29 in its expanded condition
within a vessel.
[0059] FIG. 31 is another embodiment of an embolic filtering device
made in accordance with the present invention.
[0060] FIG. 32 is an elevational view, partially in section, of the
embolic filtering device of FIG. 31 in its expanded condition and
disposed within a vessel.
[0061] FIG. 33 is an elevational view of the various components
making up another embodiment of an embolic protection device made
in accordance with the present invention.
[0062] FIG. 34 is an elevational view depicting the embolic
protection device of FIG. 33 in its expanded position.
[0063] FIG. 35 is an elevational view depicting the embolic
protection device of FIG. 34 in its collapsed position.
[0064] FIG. 36 is an elevational view, partially in section, of an
alternative embodiment of an embolic protection device similar to
that shown in FIG. 34.
[0065] FIG. 37 is an elevational view of two deployment members
which move the struts of the strut assembly into the expanded or
collapsed positions.
[0066] FIG. 38 is an end view of the filtering assembly of FIG. 34
taken along lines 38-38.
[0067] FIG. 39A is an elevational view depicting an alternative
strut assembly made in accordance with the present invention which
allows the assembly to be collapsed to a lower profile.
[0068] FIG. 39B is an elevational view depicting an alternative
strut assembly made in accordance with the present invention which
allows the assembly to be collapsed to a lower profile.
[0069] FIG. 40 is an expanded side view showing the arrangement of
struts on the strut assembly of FIG. 39.
[0070] FIG. 41 is an alternative embodiment of a filter assembly
with an alternative filter element made in accordance with the
present invention.
[0071] FIG. 42 is an enlarged side view of the filter element of
the filtering assembly of FIG. 41.
[0072] FIG. 43 is an elevational view of a proximal locking
mechanism which can be utilized in accordance with embodiments of
the embolic protection device made in accordance with the present
invention.
[0073] FIG. 44 is an elevational view, partially in section,
showing the biasing spring of the locking mechanism of FIG. 39
which can maintain the embolic protection device either in the
collapsed or expanded position.
[0074] FIG. 45 is an elevational view of the various components
making up another embodiment of an embolic protection device made
in accordance with the present invention.
[0075] FIG. 46 is an elevational view depicting the embolic
protection device of FIG. 45 in its expanded position.
[0076] FIG. 47 is an elevation view depicting the embolic
protection device of FIG. 46 as it is being moved into its
collapsed position.
[0077] FIG. 48 is a cross-sectional view of the embolic protection
device of FIG. 46.
[0078] FIG. 49 is an elevational view of another embodiment of the
embolic protection device made in accordance with the present
invention.
[0079] FIG. 50 is a cross-sectional view depicting the embolic
protection device of FIG. 49 in its expanded position.
[0080] FIG. 51 is an elevational view, partially in cross-section,
showing an alternative way to rotatably mount the filter assembly
of FIG. 49 to the guide wire.
[0081] FIG. 52 is an elevational view of another embodiment of the
embolic protection device make in accordance with the present
invention.
[0082] FIG. 53 is a cross-sectional view showing the distal end of
the embolic protection device of FIG. 52.
[0083] FIG. 54 is an elevational view of another embodiment of an
embolic protection device made in accordance with the present
invention.
[0084] FIG. 55 is an elevational view, partially in cross-section,
similar to that shown in FIG. 54, wherein the expandable filtering
assembly is in its collapsed position.
[0085] FIG. 56 is a cross-sectional view of the embolic protection
device of FIG. 54 taken along line 56-56.
[0086] FIG. 57 is an elevational view of a proximal end of an
expandable strut assembly showing a dampening member associated
with a filtering assembly which is rotatably attached to a guide
wire.
[0087] FIG. 58 is a cross-sectional view of the proximal end of a
filtering assembly made in accordance with the present invention
showing one particular example of attaching an obturator to a strut
assembly.
[0088] FIG. 59 is an elevational view depicting an embolic
protection device made in accordance with the present invention
which includes a coating that reduces the frictional coefficient
between embolic debris and the struts of the strut assembly to help
prevent embolic particles from sticking to the strut
assemblies.
[0089] FIG. 60 is a schematic elevational view of a rotating
mandrel utilized to create an open-celled microporous filtering
material made in accordance with the present invention.
[0090] FIG. 61 is an elevational view of another embodiment of an
embolic protection device embodying features of the present
invention showing the expandable filter assembly in its collapsed
position within a restraining sheath.
[0091] FIG. 62 is an elevational view, partially in cross-section,
similar to that shown in FIG. 61, wherein the expandable filtering
assembly is in its expanded position outside of the restraining
sheath.
[0092] FIG. 63 is an elevational view, partially in cross-section,
similar to that shown in FIG. 62, wherein an actuating member is
being utilized to retract the expanded filtering assembly shown in
FIG. 62 to its collapsed position.
[0093] FIG. 64 is an elevational view depicting the embolic
protection device of FIG. 63 as it is being moved into a
restraining sheath.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0094] Turning now to the drawings, in which like reference
numerals represent like or corresponding elements in the drawings,
FIGS. 1 and 2 illustrate an embolic protection device 10
incorporating features of the present invention. In the particular
embodiment shown in FIGS. 1 and 2, the embolic protection device 10
comprises a filtering or filter assembly 12 which includes an
expandable strut assembly 14 and a filter element 16. The filter
assembly 12 is rotatably mounted on the distal end of an elongated
tubular shaft, such as a guide wire 18. Additional details
regarding particular structure and shape of the various elements
making up the filter assembly 12 are provided below.
[0095] The embolic protection device 10 is shown as it is placed
within an artery 20 or other blood vessel of the patient. This
portion of the artery 20 has an area of treatment 22 in which
atherosclerotic plaque 24 has built up against the inside wall 26
of the artery 20. The filter assembly 12 is placed distal to and
downstream from, the area of treatment 22 as is shown in FIGS. 1
and 2. Although not shown, a balloon angioplasty catheter can be
introduced within the patient's vasculature in a conventional
SELDINGER technique through a guiding catheter (not shown). The
guide wire 18 is disposed through the area of treatment and the
dilatation catheter can be advanced over the guide wire 18 within
the artery 20 until the balloon portion is directly in the area of
treatment. The balloon of the dilatation catheter can be expanded,
expanding the plaque 24 against the inside wall 26 of the artery 20
to expand the artery and reduce the blockage in the vessel at the
position of the plaque 24. After the dilatation catheter is removed
from the patient's vasculature, a stent 25 (shown in FIG. 2) could
also be delivered to the area of treatment 22 using over-the-wire
techniques to help hold and maintain this portion of the artery 20
and help prevent restenosis from occurring in the area of
treatment. Any embolic debris 27 which is created during the
interventional procedure will be released into the bloodstream and
will enter the filtering assembly 12 located downstream from the
area of treatment 22. Once the procedure is completed, the
filtering assembly 12 is collapsed and removed from the patient's
vasculature, taking with it all embolic debris trapped within the
filter element 16.
[0096] One particular form of the expandable strut assembly 14 is
shown in FIGS. 1-4. As can be seen in these figures, the expandable
strut assembly 14 includes a plurality of radially expandable
struts 28 which can move from a compressed or collapsed position as
shown in FIG. 1 to an expanded or deployed position shown in FIG.
2. FIG. 3 shows a length of tubing 30 which can be utilized to form
this expandable strut assembly 14.
[0097] The expandable strut assembly 14 includes a proximal end 32
which is rotatably attached to the guide wire 18 and a distal end
34 which is free to slide longitudinally along the guide wire 18
and also can rotate thereabout. The distal end 34 moves
longitudinally along the guide wire whenever the struts move
between the expanded and contrasted positions. The proximal end 32
includes a short tubular segment or sleeve 36 which has a coil
spring formed therein which acts as a dampening member or element
38. The function of this dampening element 38 will be explained
below. The distal end 34 of the tubing 30 also includes a short
segment or sleeve 40 which is slidably and rotatably disposed on
the guide wire 18.
[0098] Referring now to FIGS. 1, 2 and 7, the proximal end 32 of
the expandable strut assembly 14 is mounted between a tapered
fitting 42 located proximal to the dampening element 38 and a
radiopaque marker band 44 located distal to the proximal end 32.
The tapered end fitting 42 and marker band 44 fix the proximal end
32 onto the guide wire 18 to prevent any longitudinal motion of the
proximal end along the guide wire but allow for rotation of the
proximal end 32 and the filtering assembly 12. This particular
construction allows the expandable strut assembly to rotate or
"spin" freely about the guide wire. In this manner, the filtering
assembly 12 will remain stationary should the guide wire 18 be
rotated at its proximal end after the embolic detection device 10
has been deployed within the patient's vasculature. This is just
one way of affixing the expandable strut assembly 14 onto the guide
wire 18 to allow it to spin or rotate on the guide wire 18. Other
ways of performing this same function can be employed with the
present invention.
[0099] The benefits of mounting the proximal end 32 of the
expandable strut assembly 14 to the guide wire 18 include the
ability to precisely deploy the filtering assembly 12 within the
artery once the guide wire 18 has been positioned in the patient's
vasculature. Since the proximal end 32 cannot move longitudinally
along the guide wire, the physician can be sure that the filtering
element 12 will be placed exactly where he/she places it once the
restraining sheath 46 is retracted to allow the expandable struts
to move into their expanded position. Additionally, since the
proximal end 32 is affixed to the guide wire, any movement of the
filtering element as the restraining sheath 46 is retracted should
not occur. Since the expandable struts 28 can be made from
self-expanding materials, there may be some stored energy in the
filtering assembly 12 as it is held in its collapsed position by
the restraining sheath 46. As that restraining sheath 46 is
retracted, there can be a frictional build-up which can cause the
strut assembly 14 to move outward if the proximal end 32 were not
affixed to the guide wire 18. As a result, if the ends of the strut
assembly 14 were not somehow fixed onto the guide wire, there could
be a tendency of the filtering element 12 to spring out of the
restraining sheath 46 as it is being retracted. As a result, the
placement of the filtering element 12 will not be as accurate since
the physician will not be able to pre-determine if and how much the
filtering assembly 12 would move as the restraining sheath 46 is
retracted.
[0100] The dampening element 38, which in this particular
embodiment of the invention is shown as a helical coil formed on
the proximal end 32 of the strut assembly 14, helps to dampen any
shockwaves (vibratory motion) which may be transmitted along the
guide wire 18, for example, when interventional devices are being
delivered or exchanged over the guide wire in an over-the-wire
fashion. Similarly, this dampening element 38 also helps dampen any
shock forces which may result as the restraining sheath 46 is
retracted to allow the radial expandable struts to move into their
expanded position as shown in FIG. 2. The helical coil can also act
as an attachment method which helps retain guide wire flexibility.
The dampening element 38 should somewhat also dampen shock which
may be created as the recovery sheath 48 (FIG. 2) contacts the
struts to collapse the filter assembly 12 when the embolic
protection device is to be removed from the patient's vasculature.
As a result, this dampening element 38 will absorb and dissipate
forces which would otherwise act on the expanded filtering assembly
12 and could cause the assembly 12 to scrape the inside wall 26 of
the artery 20 or otherwise cause trauma to the vessel. This
dampening element 38 also helps prevent displacement or
misalignment of the filter element within the artery which may
result from a sudden shock transmitted along the guide wire 18.
[0101] The filter element 16 utilized in conjunction with this
preferred embodiment of the invention includes a tapered or cone
shaped section 50 which has a plurality of openings 52 which allow
the blood to flow through the filter 16 but captures emboli within
the inside of the cone shaped section. The filter element 16
includes a short proximal section 52 which is integral with the
cone shaped section 50 and expands to a substantially cylindrical
shape when the struts 28 of the strut assembly 14 are deployed. The
inlet opening 51 allows any embolic debris 27 to enter the filter
element 16 for capture. This short cylindrical section 52 also
serves as a suitable location where the filter element 16 can be
adhesively or otherwise affixed to each strut 28 of the strut
assembly 14. The filter element 18 includes a short distal
cylindrical section 54 which is integral with the remaining
sections of the filter and is attached to the sleeve segment 40
which forms the distal end 34 of the expandable strut assembly 14.
This distal cylindrical section 54 can be attached to the sleeve 40
using adhesives or other bonding techniques.
[0102] Referring again to FIG. 1, the filter assembly 12 is
maintained in its collapsed or compressed position through the use
of a restraining sheath 46 which contacts the struts 28 and filter
elements 16 to maintain the filtering assembly 12 collapsed.
Although not shown, the guide wire and restraining sheath 46 have
proximal ends which extend outside the patient. The struts 28 can
be manipulated into the expanded position by retracting the
restraining sheath 46 (via its proximal end) to expose the struts
28. Since the struts 28 are self expanding, the removal of the
restraining sheath 46 allows the struts 28 and filter element 16 to
move to the expanded position within the artery 20.
[0103] The guide wire 18 includes a small sphere 56 affixed thereto
which is beneficial during the delivery of the embolic protection
device 10 into the patient's vasculature. This sphere 56 is
approximately as large as the inner diameter of the restraining
sheath 46 and is utilized as a "nosecone" to prevent possible "snow
plowing" of the embolic protection device as it is being delivered
through the patient's arteries. The sphere 56 is atraumatic and has
a smooth surface to help the embolic protection device travel
through the patient's vasculature and cross lesions without causing
the distal end of the restraining sheath 46 to "dig" or "snow plow"
into the wall of the arteries. When the embolic protection device
10 is to be removed from the patient's vasculature, a recovery
catheter 48 is utilized to collapse and recover the filter assembly
12. (FIG. 2). Generally, this recovery sheath 48 has a slightly
larger inner diameter than the restraining sheath 46 since the
struts 28 are now deployed and may require some increased hoop
strength at the distal end 47 of the recovery sheath 48 to properly
move the strut assembly 14 back into its collapsed position. The
collapse of the expandable strut assembly 14 can be accomplished by
holding the guide wire 18 and moving the proximal end (not shown)
of the recovery sheath 48 forward which will move the distal end 47
of the sheath 48 over the struts 28. Alternatively, the recovery
sheath 48 can be held stationary while the proximal end of the
guide wire is retracted back to pull the entire filter assembly 12
into the sheath 48. Upon collapse of the filter assembly 12, any
embolic debris generated and entering the bloodstream during the
interventional procedure will remain trapped inside the filter
element 16 and will be withdrawn from the bloodstream when the
embolic protection device 10 is removed from the patient's
vasculature.
[0104] A radiopaque marker 58 located approximately at the
longitudinal center of the expandable strut assembly 14 is also
affixed to the guide wire 18 to provide the physician with a
reference marker when positioning the device within the patient's
artery 20.
[0105] The number of struts 28 formed on the expandable strut
assembly 14 can be any number which will provide sufficient
expandability within the artery to properly deploy and maintain the
filter element 16 in place. In the embodiment shown in FIGS. 1 and
2, the expandable strut assembly has four self-expanding struts 28.
Likewise, the particular size and shape of each strut 28 can be
varied without departing from the spirit and scope of the present
invention. In this preferred embodiment, the strut pattern includes
a first portion 60 having an inverted triangular shape, a
substantially straight center section 62, and a second inverted
triangular shaped section 64 which completes the strut. This
particular strut pattern is preferred since the design provides
greater strength in regions of the strut where there would be a
tendency for the strut to break or become weakened. These regions
include the very proximal and distal ends of each strut which are
designed with a wider base. This particular design also allows the
composite strut assembly to open and close more uniformly which is
beneficial especially when collapsing the struts for removal from
the patient. Additionally, the center section 62 allows the struts
28 to expand to a greater volume, which allows a larger filter
element to be placed on the strut assembly 14, if needed.
[0106] Referring now specifically to FIG. 4, a plan view of a
rolled out flat sheet of the tubing 30 utilized to form the struts
28 is shown. As can be seen from FIG. 5, a particular design
pattern is cut into wall of the tubing 30 in order to form each
strut 28. In the case of the embodiment shown in FIG. 3, that
pattern consists of a truncated diamond shape 65 which helps form
the first section 60, the center section 62 and the second section
64. By selectively removing portions of the tubing 30 through laser
cutting or other suitable means, each particular strut 28 can be
made to a precise shape, width and length. This truncated diamond
pattern 68 repeats as can be seen in FIG. 4 to provide uniform size
to each of the struts 28 formed therein.
[0107] An alternative preferred embodiment of the expandable strut
assembly 14 is shown in FIGS. 5 and 6. This particular strut
assembly 14 is similar to the one shown in FIGS. 3 and 4 except
that there is no center section. The struts 68 shown in FIGS. 5 and
6 consist of a pair of inverted triangles which form a first
section 70 and a second section 72. The plan view of the flat sheet
of the tubing 30 used to form the strut assembly 14, as shown in
FIG. 6, shows a repeating diamond pattern 74 which is cut into the
tubing to create each individual strut 28. Again, this particular
pattern is preferred since greater strength is provided near the
proximal and distal ends of each strut where there would be a
tendency for breakage or a weakness of the strut. When the
particular pattern is cut into the tubing, whether it be the
pattern shown in FIGS. 3-4 or 5-6 or some other pattern, the sleeve
36 which forms the proximal end 32 of the strut assembly 14 can
thereafter be similarly cut to create the helical coil which forms
the damping element 38 on the strut assembly 14.
[0108] Another embodiment of the present invention is shown in
FIGS. 9-11. As can be seen in FIG. 9, the embolic protection device
100 includes a filter assembly 102 having an expandable strut
assembly 104 and a unique filter element 106. The particular strut
assembly 104 utilized with this embolic protection device 100 is
similar to the structure of the expandable strut assembly 14 shown
in the previous embodiment. The filter element 106, which will be
described in greater detail below, is utilized in its expanded
position to collect any embolic debris for removal from the blood
stream of the patient.
[0109] The various elements making up this particular embodiment of
the embolic protection device 100 are shown in FIG. 10. In this
particular embodiment, the strut assembly 104 does not necessarily
have to be made from a self-expanding material, as the strut
assembly 14 disclosed in the previous embodiment. Rather, it could
be made from stainless steel or other materials which require the
application of external axial force on the proximal end 110 and
distal end 112 of the strut assembly 104 to move the struts 108
between the contracted and expanded positions. As is shown in FIGS.
10 and 11, the proximal end 110 of the assembly 104 includes a
short tubular or sleeve-like segment 114 and a similar distal
segment 116. The struts 108 are moved from a contracted to a
deployed position by imparting an inward axial force on the
proximal end 110 and distal end 112 of the strut assembly 104. This
can be accomplished by first attaching the distal end 112 of the
assembly 104 directly to the guide wire 118. The proximal end 110
of the strut assembly 104, can then, in turn, be attached to an
outer tubular member 120 which, along with the guide wire 118, has
a proximal end which extends outside of the patient. The proximal
ends (not shown) of both the outer tubular member 120 and the guide
wire 118 can be manipulated by the physician to either impart an
inward axial force on the two ends 110 and 112 of the strut
assembly 104 to move the struts 108 to the deploy position or can
be moved to impart an outward axial force on both ends 110 and 112
to collapse the struts 108 back to their collapsed position.
[0110] The struts 108 of the strut assembly 104 can be made from a
piece of tubing (hypotube) in which select portions of the tubing
are removed to form the particular size and shape of each strut.
The strut assembly 104 could also be made from a self-expanding
material such as nickel-titanium (NiTi) if desired. The struts 108
would then be biased into either the collapsed or expanded position
with the outer tubular member 120 being used to move the proximal
end 110 in order to expand or contract the strut assembly 104,
depending upon, of course, the manner in which the expandable
struts 108 are biased. Again, in the embodiment shown in FIG. 10,
the struts 108 have a similar shape as the struts 28 shown in the
embodiment of FIGS. 1-4. This particular embodiment of an embolic
protection device thus eliminates the need to utilize both a
restraining sheath and recovery sheath which would be otherwise
needed in order to deploy and contract the embolic protection
device. This particular design, however, does not allow for the
filter assembly 102 to rotate as freely along the guide wire 118 as
does the previous embodiments, although there can be some rotation.
However, the outer tubular member 120 and guide wire 118 are
utilized in a similar fashion by allowing interventional devices to
be delivered over the outer tubular member in an over-the-wire
fashion after the embolic protection device 110 is in place within
the patient's vasculature.
[0111] It should be appreciated that the strut assembly 104 could
also be made from a self-expanding material which maintains the
struts 108 biased in their expanded position. The outer tubular
member 120 would still be utilized in order to move the expanded
struts 108 back into their collapsed position. The proximal ends of
the outer tubular member 120 and guide wire 118 can be attached to
a simple locking mechanism 600 (shown in FIGS. 39 and 40) which can
be utilized to move the outer tubular member relative to the guide
wire for maintaining the strut assembly 104 in its collapsed
position until ready to be deployed within the patient's
vasculature. It should further be appreciated that the particular
embolic protection device 100 can also be modified to eliminate the
outer tubular member 120 and be a self-expanding assembly like the
one shown in FIGS. 1-2. In such a case, the proximal end 110 of the
strut assembly 104 can be rotatably attached to the guide wire 118
with the distal end 112 being slidably mounted on the guide wire to
allow for longitudinal motion and rotational motion about the guide
wire 118.
[0112] The filter element 106 utilized in conjunction with this
particular embodiment, or which can be utilized with any of the
other embodiments disclosed herein, has a unique shape to provide a
large reservoir to collect and maintain any embolic debris which
may be trapped within the filter 106. Referring now to
[0113] FIGS. 9-12, the various sections of the filter element 106
will be described in greater detail. It should be noted that the
filter element 122 of FIG. 22 incorporates many of the same filter
sections as the filter element 106 shown in FIGS. 10-12. Therefore,
corresponding sections of these filters will be described
simultaneously in order to better understand the principles
underlying these unique filter elements. Both filter elements
include a proximal cone section 124 which expands to fit within the
diameter of the artery. This particular proximal cone section 124
blocks or funnels blood flow and embolic debris into the main or
central filter 126. In both of the filter elements shown in FIGS. 9
and 22, the proximal cone section 124 includes a plurality of
openings 128 which are utilized in filtering the embolic debris.
However, it is possible to eliminate the openings 128 on the
proximal cone section 124 to allow it to primarily direct blood
flow and embolic debris directly into the central filter 126. This
central filter 126 is integral with the proximal cone section 124
and includes a number of openings 128 utilized to permit blood flow
through this section of the filter but to retain any embolic debris
which is larger than the size of the openings 128. The openings 128
can be laser cut or otherwise punched into this central filter 126.
This central filter 126 has a substantially cylindrical shape and
acts as a large reservoir for holding the embolic debris. Ideally,
it is sized such that when it is completely full of embolic
material, it does not collapse to a smaller profile. However, is
should be able to be withdrawn into the guiding catheter (not
shown) when in its fully expanded condition with embolic debris
trapped therein. Thus, the maximum outer expanded diameter of this
central filter 126 should be smaller than the inner diameter of the
guiding or sheath utilized in deploying the embolic protection
device 100 in the patient's vasculature. The central filter can be
made from a stiffer polymeric material which will maintain the
shape and outer diameter to prevent the filter from collapsing
after use. The resulting stiffer central filter cannot be squeezed
during the collapse and removal of the filtering assembly from the
artery which should prevent any trapped embolic debris from being
squeezed out of the reservoir portion of the central filter.
[0114] Both filters 106 and 122 include a distal tapered region 130
which tapers down to the shaft of the guide wire 118. The taper of
this particular region of the filter elements 106 and 122
facilitates the delivery of the embolic protection device 100 and
helps prevent the "snow plow" effect when being delivered through
the patient's vasculature. There is a small distal section 132
which also forms a part of the filter element and is utilized to
attach the distal end of the filter directly onto the guide wire.
This distal section 132 can be fastened utilizing well-known
adhesives or other bonding techniques to permanently affix it to
the guide wire 118 and prevent any embolic debris from escaping
through the distal opening of this distal section 132.
[0115] The primary benefit of utilizing a large central filter with
a proximal cone section is that there is a large filtering area
provided by the central filter 126 which is less likely to squeeze
out trapped embolic debris when the embolic protection device 100
is being removed from the patient's vasculature. As can be seen in
FIG. 22, the central filter 126 has a general cylindrical shape
while the central filter 126 of FIG. 9 can be a generally
cylindrically shaped but can also include side creases 134 which
produce a unique-looking design. The particular cross-sectional
view of the central filter 126 of filter element 106 is shown in
FIG. 16 and shows just one of a number of different shapes that can
be used to create the central filter 126. In use, the filter
element 122 of FIG. 22 would be attached to the strut assembly 104
and guide wire 118 utilizing adhesives or other bonding
techniques.
[0116] The filter element 106 of FIG. 9 also incorporates some
unique features which are not shown in the more basic filter design
shown in FIG. 22. These advantages include the unique
cross-sectional shape of the central filter 126 shown in FIG. 16,
along with other features which help maintain the filter element
106 securely attached to the struts 108 of the strut assembly 104.
Referring again to FIGS. 10-12, the filter element 106 includes a
short outer rim 136 which is proximal to the end of the cone
section 124 and has a large inlet opening 125 for receiving the
blood flow and any embolic debris released into the bloodstream.
This proximal outer rim 136 is ring-shaped and can be utilized to
help attach the filter onto the struts 108 of the assembly 104. As
can be seen in FIG. 10, this proximal outer ring is attached to the
middle section 138 of each strut 108 and includes a tab 123 which
can be wrapped around and attached to the strut 108. This proximal
outer ring 136 also helps maintain the circular inlet opening 125
which must be expanded and maintained within the artery of the
patient. Attached to the front of the outer rim 136 are restraining
straps 142 which are likewise utilized to help hold the filter onto
the struts 108 of the assembly 104. Each restraining strap 142
includes tab-like projections 144 which can wrap around each
individual strut and be affixed thereto utilizing a bonding agent
such as adhesive. These elements allow the restraining straps 142
to hold the filter element 106 onto the strut assembly 104. It
should be appreciated that any number of different tab-like
projections 144 can be utilized in conjunction with these
restraining straps 142 to help secure the filter onto the assembly
104. The proximal end of each restraining strap 144 is attached to
a sleeve 146 which also can be adhesively fixed to the tubular
segment 114 formed at the proximal end 110 of the strut assembly
104. These various sections of the filter 106 can be made as one
composite unit and can be formed by cutting a pattern into a
pre-formed filter blank. Thereafter, the openings 128 along the
length of the filter element 106 can be placed accordingly.
[0117] The proximal cone section 126 of the filter element 106
shown in FIG. 9 includes a plurality of indented flaps 148 which
are utilized to help close the opening of the central filter 126
when the proximal cone 124 is in its collapsed position. Each of
these indented flaps 148, as shown in FIGS. 11, 17 and 18, are
created such that as the proximal cone section 124 is being closed,
the flaps join together and cooperate to form a barrier which
prevents embolic debris from being released through the inlet
opening 127 of the central filter 126. In the particular embodiment
shown in FIG. 9, four such indented flaps can be utilized (only two
of which are shown in FIGS. 11, 17 and 18) in order to create the
barrier necessary to close the opening to the central filter 126.
However, the number of indented flaps 148 and the size and shape of
each flap 148 can be varied accordingly in order to create a
protective barrier which helps prevent trapped embolic debris from
escaping from the central filter 126 as the device 100 is being
collapsed for removal from the patient.
[0118] Referring now to the FIGS. 19, 20 and 21, a variation of the
indented flaps 148 is shown in the proximal cone section 124 of the
filter element 106. As can be seen in these figures, there are a
pair of flap portions 150 which are located within the proximal
cone section 124 and are utilized as a mechanism for closing the
inlet opening 127 of the filter element 106 when the filter
assembly is collapsed. These flap portions 150 act much like the
indented flaps 148 in that as the proximal cone section 124 is
being collapsed, these flap portions 150 extend across the inlet
opening 127 of the filter element 106 to create a barrier which
helps prevent trapped embolic debris from being released back into
the bloodstream. These flap portions 150 can be small appropriately
shaped pieces which extend across the inlet opening when the filter
is expanded but do not interfere with the flow of blood going into
the filter element 106. Blood simply travels around the flap
portions 150, along with any embolic debris, to the center filter
126 where the embolic debris will be trapped in the debris
reservoir. This feature provides a preventive measure to diminish
the possible release of trapped embolic debris when the embolic
protection device 100 is being collapsed and removed from the
patient's vasculature.
[0119] Referring now to FIGS. 14 and 15, an alternative form of the
restraining straps and tabs which are utilized to affix the filter
element 106 is shown. In these particular figures, the restraining
strap 152 extends along each strut 108 and a tab like projection
154 is utilized to affix the restraining strap to each individual
strut 108. Additional lateral strapping members 156 which extend
laterally from each restraining strap 152 can also be utilized to
help prevent the filter element 106 from moving off the strut
assembly 104 during usage. These various designs show alternative
ways of affixing the filter element 106 onto the strut assembly
104. It should be appreciated that still other forms of attaching
the filter element 106 to the strut assembly 104 can be utilized
without departing from the spirit and scope of the present
invention.
[0120] Another embodiment of the present invention is shown in
FIGS. 23 and 24. In this particular embodiment, the embolic
protection device 200 includes a filter assembly 202 having a strut
assembly 204 and a filter element 206. The strut assembly 204 is
similar to the strut assembly shown in FIGS. 1-4. It includes
self-expanding struts 208 which are expandable from a collapsed
position to a fully expanded position. This strut assembly 204
includes a proximal end 210 and a distal end 212. This strut
assembly 204 can be made from a piece of tubing in which the struts
are created by selectively removing portions of the tubing. In this
particular embodiment, the tubing can be hypotubing made from a
shape memory material such as nickel-titanium (NiTi). The resulting
strut assembly 204 is normally biased to remain in the expanded
position and require the applications of force on the ends 210 and
212 to deploy the struts 208 back to their collapsed position.
[0121] The proximal end 210 includes a segment of tubing 214 and
the distal end 212 includes a similar segment of tubing 216 as
well. The distal end 212 is permanently attached to the guide wire
218 near the distal coil 220 of the guide wire. The distal end 212
can be bonded using adhesives or welded, brazed or soldered to the
guide wire 218. Likewise, the proximal end 210 of the strut
assembly 204 can be bonded, welded, brazed or soldered to an
elongated outer tubular member 222 which has a proximal end which
extends outside of the patient. The proximal ends of the elongated
tubular member 222 and the guide wire 218 can be manipulated by the
physician to either open or close the filter assembly 202. A
suitable locking mechanism 600 for maintaining the strut assembly
204 in its collapsed or closed position is disclosed in FIGS. 43
and 44 and is described in greater detail below.
[0122] The filter element 206 comprises of a cone shape portion 224
which is attached to the center section 226 of each strut 208. A
plurality of openings 228 are laser cut or otherwise formed in the
filter 206 which allows blood to flow through the filter but
captures embolic debris which is larger than the size of the
openings. This is another more example of a variation of the
embolic protection device which can be made in accordance with the
present invention.
[0123] Another embodiment of the present invention is shown as an
embolic protection device 300 in FIGS. 25-28. Like the other
embodiments, this device 300 includes a filtering assembly 302
which has an expandable strut assembly 304 and a filter element 306
attached to the strut assembly 304. Individual struts 308 are
formed on the strut assembly 304 for moving the filtering element
306 into an expanded position within the patient's vasculature. The
strut assembly 304 is somewhat similar to the previous embodiments
disclosed above in that an outer elongated tubular member 310 is
utilized in conjunction with a guide wire 312 to collapse and
deploy the strut assembly 304. Although not shown in FIGS. 25 and
26, the outer tubular member 310 has a proximal end which extends
with the proximal end of the guide wire outside of the patient to
allow the physician to move the proximal ends to deploy or collapse
the filtering assembly 302. The strut assembly 304 can be formed by
selectively removing material from the outer tubular member 310
near its distal end to create the individual struts 308. The struts
will open upon application of an inward force on ends of the
individual struts 308. Alternatively, the strut assembly 304 can be
made from a piece of hypotubing which can be affixed to the outer
tubular member 310 as is shown in some of the previous embodiments
of the invention. The entire outer tubular member 310 with the
strut assembly 304 is free to slide along the length of the guide
wire 312 which allows the filtering assembly 302 to be positioned
within the patient's vasculature in an over-the-wire fashion.
[0124] As can be seen in FIGS. 25-28, a stop element 320 is located
near the distal coil 322 of the guide wire 312. This distal stop
element 320 is utilized in conjunction with the outer tubular
member 310 to produce the force necessary to expand the struts 308
into the expanded position. The embolic protection device 300 can
be utilized in the following matter. First, the physician maneuvers
the guide wire 312 into position past the lesion or area of
treatment. Thereafter, the outer tubular member 310 with the strut
assembly 304 is advanced over the guide wire 312 in an
over-the-wire technique. The embolic protection device 300 remains
in its collapsed position while being delivered over the guide wire
312 to the distal end 313 of the guide wire, as is shown in FIG.
27. Thereafter, the physician allows the distal sleeve 312 of the
outer tubular member 310 to contact the stop element 320 located on
the guide wire 312. By applying additional force at the proximal
end of the elongated tubular member 310, the physician will cause
the struts 308 to expand radially outward for deployment within the
artery. The resulting expansion of the struts 308 thereby opens up
the filter element 306 within the artery. The physician can then
deliver interventional debris into the area of treatment and
perform the procedure on the lesion. Any embolic debris which may
be created during the interventional procedure will be collected
within the interior of the filter 306.
[0125] A simple locking mechanism 600 device located at the
proximal end of the outer tubular member and guide wire, as is
shown in FIGS. 43 and 44, can be utilized to move and maintain the
strut assembly 304 in the expanded condition. Thereafter, once the
embolic protection device 300 is desired to be removed from the
vasculature, the physician merely retracts the proximal end of the
outer tubular member 310 to remove the force on the strut assembly
304 allowing the struts 308 to move back to the collapsed position.
Thereafter, the embolic protection device 300 and guide wire 312
can be removed from the patient's vasculature.
[0126] The filter element 306 takes on a some what different shape
from the previous filter element in that the main portion of the
filter element 306 has a shape of a half of a dilatation balloon
utilized in angioplasty procedures. Perfusion openings 313 are
located on the filter elements 306 for allowing blood perfusion
while capturing embolic debris. The proximal end of the filter
element 306 includes a plurality of restraining straps 314 which
extend to a proximal sleeve 316 which is affixed to the outer
tubular member 310 proximal of the struts 308. The distal end 318
of the filter element 306 is also attached to the distal sleeve 321
which is formed on the outer tubular member 310 when the struts 308
are formed.
[0127] FIGS. 29 and 30 show another embodiment of a embolic
protection device 400 made in accordance with the present
invention. This particular embodiment is somewhat similar to the
previous embodiments in that an external force is generated on the
ends of the struts of the strut assembly to facilitate the outward
expansion and inward contraction of the struts. Referring
specifically now to FIG. 29, the embolic protection device 400
includes a filter assembly 402 having a strut assembly 404 which
has a filter element 406 attached thereto. The individual struts
408 are formed on an outer tubular member 410 which has a distal
end 412 attached to the distal end 413 of an inner tubular member
414. Both the inner member 414 and the outer member 410 have
proximal ends which are located outside of the patient's
vasculature. The struts 408 are radially expanded by moving the
outer tubular member 410 relative to the inner tubular member 414
to apply the necessary axial force to cause the struts to deploy
outward. An opposite axial force is necessary to cause the struts
408 to move back to the collapsed position when the device is to be
removed from the patient's vasculature. In this embodiment, more
than four struts 408 are used to expand the filter element 406
within the artery 420. Again, the number, size and shape of the
struts 408 can be varied without departing from the spirit and
scope of the present invention.
[0128] The filter element 406 also has the shape of one half of a
dilatation balloon utilized in angioplasty procedures and includes
openings 416 which allows blood to flow through the filter but
captures the desired size of the embolic debris. The proximal end
of the filter element 406 which includes an inlet opening 417 is
attached to each of the center sections 418 of the struts 408. The
distal end 420 of the filter 406 is attached to the distal end 412
of the strut assembly 404.
[0129] The lumen 422 of the inner tubular member 414 can be
utilized for a number of purposes, such as blood perfusion past the
deployed filter assembly 402 when placed in the artery. Therefore,
should the openings 416 of the filter element 406 become clogged
with debris which prevents blood from flowing through the filter;
oxygenated blood can be perfused to downstream vessels via the
inner lumen of the inner tubular member 414. This lumen can also be
utilized for delivering the embolic protection device 404 over a
guide wire in an over-the-wire fashion.
[0130] FIGS. 31 and 32 show a variation of the previous filter
element which can be utilized in conjunction with the present
invention. The filter embolic protection device 400 is basically
the same device shown in FIGS. 29 and 30 except that the filter
element 430 has a different design. As can be seen in FIG. 31, the
filter element 430 includes a proximal cone shape portion 431 which
extends in front of the inlet opening 432 of the filter element
430. This type of filter 430 has advantages in that it may be
easier to attach to the strut assembly 404. Additionally, the wall
of the artery is insulated from the struts 408 by restraining
straps 434. This device also has the benefits of being low profile
and allows the use of any guide wire, as well as allowing for guide
wire exchanges. This particular embodiment, like the previous
embodiments, allows for the exchange of the interventional device
in an over-the-wire procedure.
[0131] Referring now to FIGS. 33-38, two different embodiments of
the present invention are shown which utilize a different mechanism
for deploying the struts of the strut assembly. In FIG. 33, an
embolic protection device 500 is shown as including a filter
assembly 502 having an expandable strut assembly 504 and a filter
element 506. As with the other embodiments, the strut assembly 504
includes a plurality of radially expandable struts 508 which are
utilized to place the filter element 506 into an expanded position
within the patient's vasculature. The mechanism for deploying the
radially expandable struts 508 utilizes a number of self-expanding
deployment members 510 which are attached to each of the struts 508
making up the expandable strut assembly 504. The self-expanding
deployment members 510 are made from self-expanding materials, such
as nickel-titanium alloy, which can be compressed to a very small
profile and expanded to a rather large expanded position which
moves the struts 508 and filter 506 to the fully expanded position.
As is seen in FIGS. 33 and 34, there are a number of deployment
members 510 which are located along the length of each of the
struts 508. There is a proximal set 512 of deployment members 510
located along the proximal region of each strut 508. There is a
center set 514 of deployment members 510 located at the center
section of each stent 508. As can be seen in FIG. 34, the coverage
of the filter element 506 begins at this center set 514. A third or
distal set 516 of deployment members 510 is located on the struts
in the region where the filter element 506 is placed to enhance the
deployment of each strut.
[0132] As can be seen in FIG. 37, each deployment member 510 is
basically a collapsible piece of self-expanding material which will
expand to a final size when fully deployed. FIG. 38 shows an end
view of the center set 514 and distal set 516 of the deployment
members as they are located along the struts 508. Each of the sets
of deployment members 510 will fully expand to a quarter-circle
segment which cooperate to form a "ring" when the sets of the
deployment members are fully expanded. As a result of using this
particular construction, the filter element 506 will fully deploy
and maintain a circular-shaped opening 507 which will contact the
wall of the artery when the embolic protection device 500 is
deployed within the patient's vasculature.
[0133] In the first embodiment of this particular embolic
protection device 500, the distal end 518 of the expandable strut
assembly 504 is permanently attached to the guide wire 520. The
proximal end 522 of the strut assembly 504 is, in turn, attached to
an elongated outer tubular member 524 which has a proximal end (not
shown) which extends outside of the patient's vasculature along
with the proximal end of the guide wire. The embolic protection
device 500 can be moved into its collapsed position as shown in
FIG. 35 by simply retracting the proximal end of the outer tubular
member 524 to impart an outward force on the ends of the strut
assembly 504. The force which will be imparted on the ends of the
strut assembly 504 should be sufficient to collapse each deployment
members 510 which will, in turn, cause each of the struts 508 to
move back to the collapsed position. As with the other embodiments,
once the struts 508 are placed in its collapsed position, the
filter element 506 will likewise collapse and will trap and
encapsulate any embolic debris which may have been trapped within
the filter element 506.
[0134] Referring now to FIG. 36, an alternative embodiment of an
embolic protection device similar to the one shown in FIG. 33 is
disclosed. This particular embolic protection device 530 utilized
the same filter assembly 502 and strut assembly 504 as shown in the
previous embodiment. The differences between the strut assembly 532
of the embolic protection device 530 includes the elimination of
the proximal set 512 of deployment members 510 from this strut
assembly 532. Otherwise, the filter assembly 534 is virtually the
same as the filter assembly 502 of the previous device 500.
[0135] The distal end 518 of the strut assembly 534 is also
permanently affixed to the guide wire 520 in this particular
embodiment. The proximal end of this particular strut assembly 534
is free to move longitudinally along the length of the guide wire
when being moved from a deployed to a contracted position and visa
versa. The mechanism for deploying the filter assembly 532 is
restraining sheath 536 which places a force on the deployment
members 510 which prevent them from expanding until the restraining
sheath 536 is retracted. Once the embolic protection device 530 is
properly in place within the patient's vasculature, the proximal
end (not shown) of the restraining sheath 536 is retracted to allow
the deployment members 510 to open the struts 508 and filter
element 506 to the fully expanded position within the artery. When
the device is to be removed from the patient's vasculature, the
restraining sheath 536 is placed against the proximal region 535 of
the struts 508 and is retracted over the struts to force the
deployment members 510 back into their collapsed position.
Thereafter, any embolic debris which may be trapped within the
filter element 506 is retained and safely removed from the
patient's vasculature. A proximal set of deployment members 510 may
not have to be used with this particular embodiment since there may
be a need to reduce the amount of expansive force applied to the
struts in this proximal region 535. However, it is still possible
to place a first set of deployment members at this proximal region
535 provided that the sheath has sufficient strength to collapse
the struts in this region.
[0136] The filter element 506 shown in FIGS. 33-38 is made from a
mesh material which allows blood to perfuse therethrough but
captures embolic material. The mesh material can be made from any
interwoven fabric which contains small size openings which will
trap the desired size of emboli. Alternatively, the filter 506 can
be made from a polymeric material with perfusion openings found
therein.
[0137] Referring now to FIGS. 39A, 39B and 40, an alternative strut
assembly 550 which could be utilized in conjunction with any of the
filtering assemblies made in accordance with the present invention
is shown. The strut assembly 550 includes struts 552 and a
deployment member 554 which is used to expand the struts 552 into
the deployed expanded position. This deployment member 554 acts in
the same manner as the previously described deployment members in
that the deployment member 554 can be made from a self-expanding
material which will expand to a final size once fully deployed. The
deployment member 554 also could be collapsed to an unexpanded
position when an external force is placed on the assembly to
maintain the deployment member 554 in its collapsed position. As
can be seen in FIGS. 39A, 39B and 40, the deployment member 554 has
a serpentine pattern made of peaks 556 and valleys 558 which are
accordingly attached to the struts 552 of the assembly 550. In
these particular embodiment of the invention, the deployment member
554 has a sinusoidal wave pattern which includes the peaks 556 and
valleys 558 that are attached to the ends of the struts 552. This
particular pattern allows the struts to be offset or staggered from
one another to allow the assembly 550 to be collapsed to a lower
profile which enhances the assembly's ability to reach tighter
lesions and to be maneuvered into even distal anatomy. The
staggered strut design also increases the assembly's flexibility
which enhances the ability to move the assembly within the
patient's anatomy. A filter element could be likewise placed over
or within the struts 552 to create a composite filter assembly. The
deployment member 554 provides complete vessel wall opposition,
forcing a seal of the filter edge to the wall of the vessel. The
deployment member 554 can have multiple geometries without
departing from the spirit and scope of the present invention. This
particular strut assembly 550 also could be created from a lazed
hypotube which incorporates the staggered strut design. The number
of struts can be varied along with the particular lengths of the
struts. Alternatively, the deployment member 554 could be made from
a separate piece of material from the struts and could be attached
using methods such as soldering, brazing or bonding, using suitable
adhesives. As can be seen from FIGS. 39A and 39B, the attachment of
the struts 552 to the peaks 556 and valleys 558 of the deployment
554 can be varied as shown. Both of these particular designs allow
the strut assembly to be collapsed to a low profile.
[0138] Referring now to FIGS. 41 and 42, an alternative filter
element 570 with an angulated filter edge 572 is shown which is
used to help in the loading and retrieval of the embolic protection
device into a restraining sheath. The filter element 570 is similar
to the filters previously described in that the filter element 570
includes a central section 574 which has a plurality of openings
576 that are utilized in filtering the embolic debris. The filter
element 570 includes an edge 572 which is configured similar to a
crown, with pointed peaks 578 and valleys 580. This configuration
of the filter edge 572 allows the filter to be incrementally
introduced into the restraining sheath, thus preventing the
material from entering the sheath all at once. As can be seen in
FIGS. 41 and 42, the edge 572 has a somewhat sinusoidal
configuration which would reduce the stress concentration in the
valley regions 580 of the filter. The peaks 578 of the filtering
element 570 would be matched up with the struts 582 of the strut
assembly 584. The number of peaks 578 could vary with the number of
struts 582 on the strut assembly 584. In this particular
embodiment, the filtering element 570 could be placed within the
inside of the strut assembly 584, or, alternatively, the filter
could be placed on the outside of the assembly 584. It should be
appreciated that other filter elements described herein also could
either replace on the inside or outside of the strut assembly used
in connection with a particular filtering assembly. As the strut
assembly 584 is being loaded or retrieved, the peaks 578 of the
filter element 570 would enter the restraining sheath first. This
prevents all of the filtering material from entering the sheath at
once, causing a gradual and incremental loading of the filter
element 570 into the sheath. Additionally, dimensions A and B shown
in FIG. 42 show the difference in the valley depths in the
sinusoidal pattern of the filter edge 572. This allows for a
variety of configurations. One possible configuration is A=B=0.
Additionally, B.gtoreq.A.gtoreq.0 so that the loading of the filter
into the sheath will be in a smooth operation. This particular
configuration eliminates or virtually eliminates all of the valley
portions 580 from entering the sheath at the same time. The filter
edge 572 may or may not have openings 576. The peaks 578 can also
have varying heights. Dimensions C, D and E shown in FIG. 42 shows
a difference in the peak heights on the sinusoidal pattern of the
filter edge 572. This particular pattern also allows for a variety
of configurations. One possible configuration is C=D=E=0.
Additionally, E.gtoreq.D.gtoreq.C.gtoreq.0 to correspond, or
alternatively, not to correspond with the depths of the valleys
580.
[0139] Referring now to FIGS. 45-48, an alternative embodiment of
an embolic protection device 640 is disclosed. This particular
embolic protection device 640 utilizes a filter assembly 642 and
strut assembly 644 which is somewhat similar to the strut assembly
550 shown in FIG. 39B. The particular strut assembly 644 includes a
set of proximal struts 646 attached to a deployment member 648
which moves between an unexpanded or collapsed position and an
expanded position in the same manner as the previously described
deployment members. This deployment member 648 can be made from a
self-expanding material which will expand to a final diameter once
fully deployed. This deployment member 648 is collapsible when a
sheath or sleeve is placed over the assembly. A set of distal
struts 650 are attached to the deployment member 648 and also are
expandable and collapsible with the deployment member 648. The
deployment member 648 has a substantial V-shaped wave pattern which
permits the strut assembly to more easily collapse to a low
profile. A filter element 652 is attached to the strut assembly 644
and has a shape much like the filter element 570 shown in FIGS. 41
and 42. The filter element 652 includes an edge portion 654 which
is configured with alternating peaks 656 and valleys 658. This
configuration of the filter edge portion 654 also allows the filter
to be incrementally introduced into the restraining sheath 660,
thus preventing the filtering material from entering the sheath 660
all at once. As can be seen in FIGS. 45 and 46, the filter element
652 has a somewhat tulip-like shape due to the construction of the
peaks 656 and valleys 658. As is shown in FIG. 46, the peaks 656 of
the filter element 652 are matched up with the wave pattern of the
deployment member 648 and are attached thereto using adhesives or
other bonding techniques. The filter can extend along and outside
the struts with the edge portion 654 adhesively attached to the
inside edge of the deployment member 648.
[0140] The filter element 652 can be made from a mesh material
which allows blood to profuse therethrough but captures embolic
material. The mesh material can be made from interwoven fabric
which contains small size openings which would trap the desired
size of emboli. Alternatively, the filter element 652 can be made
from a polymeric material with profusion openings formed
therein.
[0141] In this particular embodiment of the embolic protection
device 640, an obturator 662 is located at the distal end 664 of
the filter assembly 642 and is utilized for obtaining smooth
deployment through the patient's vasculature. This particular
obturator 662 acts much like the sphere 56 shown in FIGS. 1 and 2
which prevents "snow plowing" of the embolic protection device as
it is being delivered through the patient's arteries. This
obturator 662 also has a smooth surface which tapers from a smaller
diameter distally to a larger diameter that corresponds to the
outer diameter of the restraining sheath 660. A smooth outer
surface is created when the obturator 662 and restraining sheath
660 are placed adjacent to each other. This obturator can be made
from a material such as PEBAX 40D, or other polymeric materials or
alloys which are capable of performing the desired function.
[0142] As is shown in the cross-sectional view of the device in
FIG. 48, the obturator 660 is attached (via adhesive or other
bonding material) to a tubular member 666, which is made from a
material such as polyimide tubing. This tubular member 666 is
adhesively or otherwise attached to the distal ends 668 of the
distal struts 650. The tubular member 666 is not, however,
adhesively attached to the guide wire 672, but rather, is allowed
to rotate free around the coils 670. The obturator 662 also extends
over a portion of the coils 670 of the guide wire 672 and is free
to rotate about the coils 670. The proximal end 674 of the filter
assembly 642 is attached to the guide wire 672 in such a manner to
allow it to rotate freely about or "spin" on the guide wire 672 as
well. The filter assembly 642 is attached to the guide wire 672
much like the embodiment shown in FIGS. 1 and 2. As can be seen in
FIGS. 46 and 48, a stop fitting 676 is attached to the guide wire
672 to prevent the proximal end 674 from moving past that
particular fitting. A second stop fitting 678, located within the
filter assembly 642, helps prevent the filter assembly 642 from
moving axially any substantial distance along the guide wire
672.
[0143] The proximal ends 680 of the proximal struts 646 are
attached to a pair of tubular segments 682 and 684 which are in a
coaxial relationship. A marker band (not shown) can be partially
sandwiched between these two tubular segments 682 and 684 to
provide the physician with a reference when placing the embolic
protection device 640 in the patient's vasculature. The tubular
segments 682 and 684 are adhesively affixed to each other and the
marker band to form a composite tubular extension member 686. This
composite tubular extension member 686 extends between the two stop
fittings 676 and 678. The extension member 686 may include a
dampening element 679 which is formed on a portion of the segment
to help dampen some of the vibratory motion which may be
transmitted along the guide wire 672. It can be cut into the
extension member 686 much like the dampening element 38 is cut on
the embodiment shown in FIGS. 1-3. It should be appreciated that
this extension member 686 can be formed from a single piece of
tubing and need not be two separately formed segments glued
together. This extension member 686 also helps to increase the
torque response of the embolic protection device 640 on the guide
wire and allows more room for the filter assembly to rotate, if
needed.
[0144] Additional marker bands 688 can be placed on the strut
assembly 644 to provide additional reference sources for the
physician to rely on when maneuvering the device in the patient's
arteries. Like the previously described filter assemblies, this
particular filter assembly 642 will remain in place within the
patient's vasculature, once deployed therein, and will remain
stationary even if the guide wire 672 is rotated by the physician
during an exchange of interventional devices along the guide wire.
As a result, there is less chance of trauma to the patient's artery
at the location where the filter assembly 642 contacts the wall of
the artery.
[0145] The particular configuration of the filter assembly 642 and
its attachment to the guide wire 672 allows the physician to
eliminate any air bubbles which may be trapped within the
restraining sheath 660 as it covers the filter assembly 642 in its
collapsed state. The present design allows the physician to flush a
solution, such as saline, through the lumen of the restraining
sheath 660 out to its distal end to cause any trapped air bubbles
to be vented through the distal opening 661 of the obturator 662.
As a result, the possibility that an air bubble possibly could be
released into the patient's artery can be virtually eliminated by
thoroughly flushing saline through the restraining sheath 660 to
eliminate any trapped air bubbles. The tubular member 666 acts as a
conduit for the saline to flow out of the obturator 662. Fluid is
allowed to flow through the restraining sheath 660 through the
inner lumen 688 of the tubular member 666 and out the distal
opening 661 of the obturator 662.
[0146] Referring now to FIGS. 49 and 50, another alternative
embodiment of an embolic protection device 690 is shown. In this
particular embodiment, the filter assembly 692 includes a strut
assembly 694 which includes only a proximal set of struts 696 that
are attached to a deployment member 698. This particular filter
assembly 692 is somewhat similar to the assembly shown in FIGS.
45-48, except that a distal set of struts are not utilized. The
filter element 700 is attached directly to the deployment member
698 and has a distal end 702 which is attached to a segment of
tubing 704 made from a material such a polyimide. This tubing 704
extends from the proximal end 706 of the filter assembly 692 to the
distal end 702 of the filter 700 and is rotatable on the guide wire
710.
[0147] In this particular embodiment, the proximal end 706 of the
filter assembly 692 is attached directly to a tubing member 704.
The proximal end 706 of the filter assembly 692 terminates in a
collar 708 as is shown in FIGS. 49 and 50. It is attached to the
tubing 704 using adhesives or other bonding techniques. This entire
filter assembly 692, which includes the tubing member 704, is
rotatable upon the guide wire 710 to allow the device to remain
stationary within the patient's artery even if the guide wire is
rotated by the physician during a device exchange. A stop fitting
712 located on the guide wire 710 acts to prevent the filter
assembly 692 from moving axially along the length of the guide wire
710. The distal end 714 of tubing member 704 abuts against the most
proximal coil 716 formed on the guide wire 710. In this manner, the
coil 716 acts as a stop fitting to prevent axial movement of the
tubing member 704 along the guide wire 710.
[0148] The distal end 702 of the filter 700 is attached to the
tubing member 704 using adhesives or other bonding agents. The
distal end 702 of the filter does not have to be movable axially
along the guide wire, as with the previous embodiments, since the
filter 700 itself is pliable and will move as the strut assembly
694 moves between its expanded and collapsed positions. When the
strut assembly 694 is moved from its unexpanded to expanded
position, the filter 700 will "stretch" somewhat as the deployment
member 698 and struts 696 move outward and somewhat away from the
distal end 702 of the filter 700. As with the previous embodiments,
a restraining sheath (not shown) is utilized to move the filter
assembly 692 between its expanded and unexpanded positions.
[0149] Referring now to FIG. 51, an alternative method for mounting
the filter assembly 692 to the guide wire 710 is shown. In this
particular embodiment, the strut assembly 694 is attached to an
outer segment of tubing 704, which can be made from materials such
as polyimide. This outer tubing 704 is in turn bonded, or otherwise
attached to, an inner tubing 705 which is slightly shorter than the
length of the outer tubing 704. For example, the outer tubing 704
and inner tubing 705 can be attached to each other utilizing a
suitable adhesive. As can be seen in FIG. 51, the inner tubing 705
has a distal end 707 which abuts against the coil of the spring tip
711 of the guide wire 710. This allows a portion of the outer
tubing 704 to extend over some of the proximal coils of the spring
tip 711. The proximal ends of the outer tubing 704 and inner tubing
705 are adapted to abut the stop fitting 712 located on the guide
wire which also helps prevent the filter assembly 692 from moving
axially along the length of the guide wire. This inner tubing 705
can also be made from a number of different materials, including
polyimide. Also, the length of the inner tubing 704 and outer
tubing 705 can be adjusted such that the radiopaque spring tip 711
can be used to indicate corresponding device positions under
fluoroscopy.
[0150] Referring now to FIGS. 51 and 52, a variation of the filter
assembly of FIGS. 49 and 50 is shown. In this particular
embodiment, the filter assembly 692 includes a strut assembly 694
in which only a proximal set of struts 696 are attached to a
deployment member 698. The filter element 700 is attached directly
to the deployment member 698 and has a distal end which can be
attached either directly to the guide wire 710 or to a small
segment of tubing 713 (FIG. 53) which will allow the filter element
700 and strut assembly 694 to spin about the guide wire 710 in the
manner which has been previously described.
[0151] In this particular embodiment, the inner tubing upon which
the previously described embolic protection device 690 is mounted
has been removed to obtain a slightly lower profile for the
composite device. As can be seen in FIG. 51, the proximal end 706
of the filter assembly 692 terminates at a collar 708 which is
directly attached to the guide wire 710. A stop fitting 712 located
on the guide wire 710 acts to prevent the filter assembly 692 from
moving axially along the length of the guide wire.
[0152] Referring specifically now to FIG. 53, the distal end 715 of
the filter element 700 includes the short segment of tubing 713
which allows the filter 700 to spin about the guide wire 710. This
particular tubing can be made from any one of a number of different
materials, including polyimide. Alternatively, the distal end of
the filter 700 could be attached directly to the guide wire
utilizing adhesives or other bonding techniques. The entire filter
assembly 692 would still be able to rotate slightly on the guide
wire since the filter element 700 can be made from a pliable
material which would "twist" to a certain degree on the guide wire.
This would still allow the strut assembly 694 to remain stationary
in place within the patient's vasculature in the event that the
guide wire is slightly rotated at the proximal end by the
physician. Again, the filter element and strut assembly can be made
in accordance with the methods described herein.
[0153] Referring now to FIGS. 43 and 44, a simple locking mechanism
600 for expanding and collapsing the filter assembly described
herein are shown. These particular mechanisms are useful whenever
the embolic protection device utilizes an inner shaft member and
outer tubular member for moving the strut assemblies into the
expanded or collapsed position. Referring first to FIG. 43, the
proximal end 602 of the outer tubular member 604 is shown with a
locking mechanism 600 which can be utilized to lock the embolic
protection device in either an expanded or unexpanded position. The
locking mechanism 600 includes an elongated slot 606 which is cut
into the wall of the outer tubular member 604 and includes a first
locking position 608 and a second locking position 610. The inner
shaft member 612, which can be either a solid shaft such as a guide
wire or a hollow tubular shaft, has a raised dimple 614 which moves
within this elongated slot 606. This raised dimple 614 can be moved
into either the first locking position 608 or second locking
position 610 to either maintain the filter assembly in an expanded
or unexpanded position. It should be appreciated that only two
locking positions are shown on this particular embodiment, however,
it is possible to use a number of different locking positions if
the user desires to have several expanded positions. If the filter
assembly is self-expanding, then a removable handle that pushes and
pulls the inner and outer members could be used. The handle would
push/pull the inner and outer members to hold the assembly closed;
then be removed so that other interventional devices could be
passed over the inner tubular member. Thereafter, the handle could
be placed back onto the proximal ends of the inner and outer
members to collapse and remove the filter assembly.
[0154] The proximal end 602 of the outer tubular member includes a
small section of knurling 616, as does the inner shaft member 612,
which provides the physician with a surface to grip when holding
and maneuvering the proximal ends of these devices. The locking
mechanism 600 can also include a biasing spring 618 located within
the inner lumen 620 of the outer tubular member 604 for biasing the
inner shaft member 612 with an outward force which maintain the
raised dimple 614 near the first locking position 608. This biasing
mechanism includes a shoulder region 621 located at the proximal
end of the outer tubular member and a collar 622 located on the
inner shaft member 612. The force of the spring 618 again helps to
maintain the dimple 614 at or near the first locking position 608.
Such a mechanism is preferable when the device is designed to be
maintained in an unexpanded position until it is ready to be
deployed. It may be beneficial to keep the filter assembly in its
unexpanded position until ready for use since it is possible to
cause damage to the filter assembly if left in an expanded
position. When the filter assembly is desired to be placed into the
deployed or expanded position, the physician merely grasps the
proximal end of the inner shaft member and pulls it back until the
dimple 614 is placed into the second locking position 610. When the
strut assembly is made from elements which are self-expanding, then
there may not be a need to have a biasing spring 618 since the
struts on the strut assembly will act somewhat like a biasing
spring to maintain the filter assembly in an expanded position.
[0155] Referring now to FIGS. 54-56, an alternative embodiment of a
filter assembly 750 is shown. The filter assembly 750 includes a
strut assembly 752 which includes a proximal set of struts 754 that
are attached to a deployment member 756 which comprises a
circumferential range which is integrally connected to each of the
struts 754. A filter 758 is attached to the deployment member 756
and terminates at a distal end 760 which is slidable along the
guide wire 762. A pair of stop fittings 764 and 766 allows the
composite filter assembly 750 to rotatably spin on the guide wire
762 as has been previously described in connection with other
embodiments disclosed herein.
[0156] The lengths of the four individual struts 754 which make up
the strut assembly 752 as indicated by arrows 11, 12, 13, and 14
vary so that as the filter assembly 750 is being resheathed into
the restraining sheath, the filter assembly 750 can be
incrementally introduced into the restraining sheath, thus
preventing the filter and individual struts from entering the
sheath all at once. This particular arrangement helps in the
collapse and resheathing of the filter assembly in the patient's
vasculature, especially when the filter portion of the filter
assembly is being resheathed.
[0157] As can be seen in FIG. 56, when the filter assembly 750 is
expanded, the deployment member 756 is substantially round and has
a slight distal bow when viewed longitudinally (as shown in FIG.
54), to facilitate collapsing of the assembly. In manufacturing
this particular strut assembly 752, a tubing of material, such as
nitinol, can be laser cut with the strut assembly heat set in the
open (expanded) shape and then delivered and removed from the
patient's vasculature with a low profile sheath. The longitudinal
struts that open and employ the filter 758 can be intrically
connected with the circumferential deployment member 756, which as
shown in FIGS. 54-56 is a ring that can be cut from the same tubing
as the struts. This deployment member 756 would completely contact
with the lumen wall when fully deployed. As the struts are
withdrawn into the sheath, the deployment member between each strut
will be formed by bowing distally convex, as is shown in FIG. 55.
Thus, a complete collapse, the deployment member 756, along with
the filter 758, can be drawn into the sheath. Additionally, this
deployment member 756 can be heat set completely round when fully
deployed as is shown in FIG. 56.
[0158] Referring now to FIG. 57, a dampening element 770, similar
to one which has been described above, is utilized accordance with
a filter assembly 772 made in accordance with the present
invention. In this particular embodiment, the dampening element 770
is shown as a separate coil spring which acts as a shock absorber
when placed between the proximal end 774 of the strut assembly 776
and the proximal stop element 778. This particular arrangement is
similar to the one shown in FIGS. 1-2 and 7, except that the
dampening element 770 is a separate element from the strut assembly
of 776. In this manner, the dampening element 770 can be made from
a material which is different from the material used to form the
strut assembly 776. This dampening element 770 also will act to
dissipate at least some of the vibratory motion which may be
transmitted along the guide wire 783.
[0159] Referring now to FIG. 58, and also to the particular
embodiment shown in FIGS. 45-48, another method for attaching the
obturator 660 to the strut assembly 644 is shown. In FIG. 58, the
obturator 660 is shown as it is adhesively attached to the strut
assembly 644 which allows for greater bond strength and flexibility
during usage. As can be seen in FIG. 58, the distal end of the
filter 652 is cut short of the distal end 664 of the strut assembly
644 to allow more of the strut assembly 644 to be exposed to the
obturator 660. As a result, an adhesive 665 can be placed between
the obturator 660 to directly contact the strut assembly 644 and
achieve a stronger bond. The assembly still includes the tubular
member 666, which be made from a material such as polyimide, or
other suitable material, which allows the filter assembly 642 to
spin on the guide wire 672. Again, the strut assembly 664 itself is
bonded to this tubular member 666 to allow the distal end to spin
freely about the guide wire 672. The bond strength is maximized
through this increased surface area on the strut assembly 664 which
is in direct contact with the obturator 660. In one embodiment, the
tubular member 666 can extend out approximately 5 mm from the
distal end of the strut assembly 644. This should eliminate any
possible contact of adhesive to the guide wire. Again, this
construction allows for a smooth rotation of the filter 652 on the
guide wire. Any excess adhesive from the obturator should collect
on the tubing to further increase the bond contact of the obturator
to the filter assembly 642.
[0160] One of the requirements of the design of the filter
assemblies shown and described herein is that embolic material must
pass around proximal struts of the assembly into the filter portion
of the device. Embolic debris which may collect or "stick" to a
proximal strut may pose a problem when the filter assembly is being
collapsed and withdrawn into the restraining sheath for removal
from the patient's vasculature. Should embolic debris collect on a
proximal strut, it may not be driven into the filter assembly for
collection and could possibly be released into the patient's blood
stream when the filter assembly is being collapsed for removal from
the patient. In such an event, the physician must face the prospect
of having to treat possible blockage to downstream vessels caused
by such embolic debris.
[0161] In order to alleviate or help reduce this unwanted release
of embolic debris from occurring, it is possible to selectively
coat the strut assembly with a material which makes the struts
"slippery", i.e., reduces the coefficient of friction between the
embolic debris and struts, to help reduce the chances of embolic
debris sticking to the struts.
[0162] Referring now to FIG. 59, a typical filter assembly 790 is
shown including a strut assembly 792 which includes proximal struts
794 that are located upstream from the filter 796. It is in the
region of these proximal struts that one or more pieces of embolic
debris can collect, rather than being driven into the filter 796.
However, the proximal struts 794 can be coated with a polymer which
reduces the coefficient of friction to help prevent, or at least
make it more difficult for, embolic debris to stick onto a strut.
For example, a polymer coating can be placed selectively on these
proximal struts. The intent in selectively depositing a slippery
polymer coating to these struts is to prevent the coating from
extending to areas of the strut assembly which experience high
strain during device expansion. This may include the deployment
member 798 which helps to deploy the filter 796 during usage. The
high strain area of this deployment member may cause certain
coating material to crack if the coating is not sufficiently
elastic to "stretch" as the strut assembly expands. Alternatively,
a very elastic coating material could be selected which will allow
the entire strut assembly to be coated. Materials of interest
include polyimide and PTFE coatings which could be applied to a
nickel titanium strut assembly without significantly affecting the
mechanical properties of the struts. It should be important to
select a polymer coating which reduces the coefficient of friction
yet does not affect the mechanical properties of the struts. If the
material proves to be too stiff, the performance characteristics of
the strut assembly could be affected. However, it is still possible
to account for the stiff characteristics of the polymer through the
strut design, i.e., the struts could be designed to be more
flexible which would offset the stiffness caused by the polymer.
Other coatings which could be utilized include hydrophilic coatings
or heparin.
[0163] An alternative material for forming the filter used to trap
the friable embolic debris utilizes an open-cell microporous
material having a network-like porous structure that captures the
debris. This particular filter material eliminates the need to
either mechanically drill or laser cut the filter material to
create a porous filter which still allows blood perfusion during
the procedure. Use of the filter membrane in a microporous
structure allows for perfusion and can be mechanically strong and
more tear resistant than films with direct holes. This microporous
structure also allows for more efficient trapping of emboli since
the particles of debris have to travel through the intricate
pattern of the filter in order to escape. Since a very fine
micro-structure can be created, the chances of embolic debris
passing through the microporous filter are extremely small.
[0164] Referring now to FIG. 60, a cone-shaped rotating mandrel 797
is shown that can be utilized in creating a microporous
film/membrane for forming the filters. The sequence of making the
microporous film is a follows, namely, a polymer is first dissolved
in a solvent to produce a polymer/solvent solution. This resulting
polymer/solvent solution can be then sprayed or cast into the
desired shape and thickness. For example, the film can be sprayed
(via a spray nozzle 799 or by other means) on the rotating mandrel
shown in FIG. 60 to create a cone-shaped structure. The rotating
mandrel can be made in a number of sizes and shapes to create the
desired filter element. Rotation of the mandrel usually improves
the uniformity of the film thickness. After the polymer/solvent
solution is sprayed or cast into the desired shape and thickness,
it can then be either dipped or sprayed with a non-solvent before
complete evaporation of the solvent occurs. This non-solvent
induces phase-separation of the polymer which creates the
microporous structures throughout the material.
[0165] In one example of a microporous polymer film made in
accordance with the present invention, the film can be made from
Tecophilic 60D, a flexible polyurethane. Pellets of Tecophilic 60D
can be dissolved in THF solvent, and sprayed onto a cone-shaped
rotating mandel. The thickness of the film can be controlled by
several factors, including the concentration of the solution, the
rotational speed of the mandrel, and the amount of solution
sprayed. After the film is cast, water (a non-solvent) then can be
sprayed on the film to induce phase-separation and create the
microporous structure. The porosity of the Tecophilic 60D film can
be varied by controlling the type of solvent and concentration of
the solvent used. Since this particular process is thermal dynamic,
there should be no material restrictions. The choice of polymer
will depend upon attributes like flexibility and strength of
film.
[0166] Referring now to FIGS. 61-64, still another embodiment of an
embolic protection device is disclosed. This particular embolic
protection device 800 utilizes a filter assembly 802 and a strut
assembly 804 mounted on the distal end of a guide wire 806. The
strut assembly 804 is self-expanding so that a restraining sheath
808 is required to maintain the assembly in its collapsed position,
ready for deployment within the patient's vasculature.
[0167] The strut assembly 804 has a different configuration from
the previously described strut assemblies. As can be seen in FIG.
62, the strut assembly 804 includes several forward radial
expandable struts 810 which extend from the distal end 812 of the
filter assembly 802. The forward struts 810 help to deploy the
filter 814 in the patient's vasculature during usage. The forward
struts 810 are attached to several activating struts 816 which are
attached at a collar 818 that is slidable along the guide wire 808.
The composite forward struts 810 and activating struts 816 provide
a mechanism for opening the filter 814 once the restraining sheath
808 is retracted from the filter assembly 802. The filter 814 can
have an scalloped filter edge 820 which, as described in a previous
embodiment above, prevents the entire filter from entering the
sheath at the same time when the device is being collapsed for
removal from the patient's vasculature. A pair of stop fittings 822
and 824, which also act as radiopaque markers to assist in locating
fluoroscopically within the patient, are located at the distal end
812 of the strut assembly 804 to attach the assembly to the guide
wire 806. This particular design allows the filter assembly 802 to
rotate or spin freely around the guide wire 806, while remaining
fixed to the guide wire 806.
[0168] After the filter assembly 802 has been deployed and it is
desired to remove it from the patient's vasculature, an outer
tubular member 826 (shown in FIG. 63) is utilized to push the
activating struts 816 and collar 818 distally to collapse the strut
assembly 804 back to its collapsed position. This outer tubular
member 826 should have sufficient stiffness to push the collar 818
distally along the guide wire 806. After the filter assembly 802 is
collapsed, a restraining sheath is used to resheath the entire
device for removal from the patient. (See FIG. 64.)
[0169] The materials which are utilized to create this particular
embodiment are similar to these previously described and include
self-expanding metals and alloys, such as nickel titanium, which
can be utilized for the strut assembly. The filter can likewise be
made from materials described herein. Likewise, the restraining
sheath can be made from materials described herein, along with any
other suitable materials, which should produce a flexible
restraining device having sufficient hoop strength to hold the
filter assembly in its collapsed position.
[0170] The strut assemblies of the present invention 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.
[0171] 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.
[0172] 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.
[0173] 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. No. 5,759,192
(Saunders) and U.S. Pat. No. 5,780,807 (Saunders), which have been
assigned to Advanced Cardiovascular Systems, Inc. and are
incorporated herein by reference in their entirely.
[0174] 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 CO2 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.
[0175] 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.
[0176] 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.
[0177] The piece of tubular hypotube which can be utilized in
accordance with the present invention to form the strut assemblies
can be one continuous piece which forms both the outer tubular
member and the strut assembly as well. In some of the embodiments
disclosed herein, the strut assembly is shown as being made from a
short segment of hypotube which is selectively cut to form the
strut patterns. Thereafter, the proximal end of the strut assembly
is bonded to, either by adhesives, welding, brazing or soldering to
the distal end of the outer tubular member. However, these two
separate pieces can be formed from a piece of single tubing in a
particular embodiment of the invention.
[0178] The dampening element which is shown in one of the
embodiments of the present invention could also be used with any of
the other embodiments disclosed herein. The dampening element could
either be cut into the proximal end of the strut assemblies, as is
shown in FIGS. 1 and 2, or an alternative dampening element could
be attached to the strut assembly. For example, a separate spring
made from a different material or similar material could be welded,
brazed or soldered to the end of the strut assembly. Also, other
dampening materials could be used besides a helical spring in order
to achieve dampening. For example, a segment of elastomeric
material could be bonded to the strut assembly as well to act as a
"shock absorber" for the system.
[0179] The outer tubular member could be made from various
materials such as stainless steel, nickel-titanium alloy or
materials which have memory. As discussed above, when using a
separate outer member attached to the strut assembly, the distal
end can be easily affixed to the strut assembly by known bonding
methods. The inner diameter of the outer tubular member must of
course be comparable to the outer diameter of the inner shaft
member to allow the outer tubular member to slide in a coaxial
arrangement. The inner shaft member can also be made from stainless
steel, nickel-titanium alloys or shape-memory materials. In one
embodiment, the inner shaft member is shown as a tubular member
which has an inner lumen which allows the device to slide over a
guide wire in an over-the-wire fashion. Other embodiments show the
inner shaft member as a guide wire or guide wire-like shaft.
Generally, when the inner shaft member is utilized as a guide wire,
it should include an atraumatic guide wire coil tip to prevent
injury to the vessel as the guide wire is being maneuvered through
the patient's vasculature. It should be appreciated that the coil
tip does not have to be placed directly next to the filtering
assembly in those embodiments which utilize a guide wire as the
inner shaft member. The filtering assembly could be placed much
more proximal to the coil tip to create a short, distal segment of
guide wire which may be pre-bent by the physician to aid in
steering through the patient's vasculature.
[0180] Again, the tubing or hypotube which could be utilized to
create the strut assembly can be a nickel-titanium alloy, such as
Nitinol, or other shape-memory materials. It is also possible to
utilize stainless steel to form the strut assembly as well. The
strut assembly could also be made from a self-expanding material
even in embodiments in which the outer tubular member and inner
shaft member are utilized to provide the axial forces necessary to
expand or contract the device during use. Additionally, the strut
assembly could be either biased to remain in its collapsed position
or expanded position as may be desired. It should be appreciated
that the stent assembly can be made from either pseudo elastic NiTi
stressed induced martensite or shape memory NiTi.
[0181] One way of making the strut assemblies of the present device
is to utilize a shape-memory material, such as nickel titanium,
which has the struts cut utilizing a machine-controlled laser. A
tubular piece of material could be utilized in this process. 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 restraining
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
device is to be utilized, the restraining sheath is simply
retracted to allow the filter assembly/strut assembly to move to
its expanded position within the patient's vasculature.
[0182] The polymeric material which can be utilized to create the
filtering 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 0.00050-0.0050 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 lazed in a spinal 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.
[0183] The materials which can be utilized for the restraining
sheath and recovery sheath can be made from similar polymeric
material such as cross-linked HDPE. It can alternatively be made
from a material such as polyolefin 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.,
to the inside surface of the restraining sheath before the sheaths
are placed over the filtering assembly.
[0184] 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.
* * * * *