U.S. patent application number 14/709794 was filed with the patent office on 2015-08-27 for variable thickness vascular treatment device systems and methods.
The applicant listed for this patent is Insera Therapeutics, Inc.. Invention is credited to Vikram Janardhan.
Application Number | 20150238303 14/709794 |
Document ID | / |
Family ID | 40468238 |
Filed Date | 2015-08-27 |
United States Patent
Application |
20150238303 |
Kind Code |
A1 |
Janardhan; Vikram |
August 27, 2015 |
VARIABLE THICKNESS VASCULAR TREATMENT DEVICE SYSTEMS AND
METHODS
Abstract
A distal embolic protection device for dedicated use in cerebral
arterial blood vessels is described. The distal embolic protection
device comprises a variable-thickness micro-guidewire and a
collapsible filtering device mounted on the microguidewire over two
mobile attachment points so that in its collapsed configuration,
the thickness of the microguidewire and the filtering device at
this region is less than or equal to 0.017 inch (0.432 mm) in
thickness to be able to pass through existing conventional
microcatheters. The mobile attachment points allow for rotatory and
longitudinal mobility of the microguidewire while the filtering
device is stable thereby decreasing the risk of trauma to the
fragile cerebral arterial blood vessels. Preferably, the filtering
device comprises an expansion assembly, e.g., a plurality of struts
attached to a filter membrane that are in a folded position which
self expand to the desired dimensions within the cerebral blood
vessels. Also described are methods of using the distal embolic
protection devices of this invention.
Inventors: |
Janardhan; Vikram;
(Sacramento, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Insera Therapeutics, Inc. |
Sacramento |
CA |
US |
|
|
Family ID: |
40468238 |
Appl. No.: |
14/709794 |
Filed: |
May 12, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11859272 |
Sep 21, 2007 |
9034007 |
|
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14709794 |
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Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61F 2230/0006 20130101;
A61F 2/95 20130101; A61F 2002/018 20130101; A61F 2/013 20130101;
A61M 25/09 20130101; A61F 2/011 20200501; A61F 2230/008 20130101;
A61F 2002/016 20130101 |
International
Class: |
A61F 2/01 20060101
A61F002/01 |
Claims
1. (canceled)
2. A method of treating vasculature, the method comprising:
tracking a treatment device through a catheter from a proximal end
of the catheter to a distal end of the catheter, the treatment
device comprising: an elongate element comprising: a proximal
segment including a proximal hypotube around a first portion of
core, a distal segment including a distal hypotube around a second
portion of the core, and a third segment comprising a third portion
of the core, the third segment longitudinally between the proximal
segment and the distal segment, and a treatment tool around the
third segment; and deploying the treatment tool out of the
catheter.
3. The method of claim 2, wherein the treatment tool comprises a
balloon.
4. The method of claim 2, wherein the treatment tool comprises a
stent.
5. The method of claim 2, wherein the treatment tool comprises a
filtering device.
6. The method of claim 5, comprising collecting thrombo-embolic
material.
7. The method of claim 6, further comprising at least one of
performing an angioplasty procedure and positioning a stent,
wherein the at least one of performing the angioplasty procedure
and positioning the stent dislodges the thrombo-embolic
material.
8. The method of claim 6, further comprising: advancing a guidewire
across the thrombo-embolic material; tracking the catheter over the
guidewire and across the thrombo-embolic material; and before
tracking the device through the catheter, withdrawing the guidewire
from the catheter.
9. A vascular treatment system comprising: a core; a first hypotube
around a first portion of the core; a second hypotube around a
second portion of the core; a third hypotube around a third portion
of the core, the third hypotube longitudinally between the first
hypotube and the second hypotube, the third hypotube transformable
between a collapsed configuration and an expanded configuration,
the third hypotube comprising: a proximal attachment point, a
distal attachment point, the third hypotube rotatable around the
third portion of the core, and a plurality of struts connecting the
proximal attachment point and the distal attachment point, the
third hypotube longitudinally movable along the third portion of
the core in the expanded configuration; and a filter membrane
coupled to the third hypotube.
10. The system of claim 9, wherein, when the third hypotube is in
the expanded configuration, the filter membrane has a
hemispherical, helical, or conical shape.
11. The system of claim 9, wherein the catheter comprises a balloon
catheter.
12. A vascular treatment system comprising: a treatment device
comprising: a proximal hypotube around a first portion of a core; a
distal hypotube around a second portion of the core, the distal
hypotube longitudinally spaced from the proximal hypotube by a
segment comprising a third portion of the core; a treatment tool in
a collapsed configuration around the segment and between the
proximal hypotube and the distal hypotube, the treatment tool
transformable between the collapsed configuration and an expanded
configuration.
13. The system of claim 12, wherein the treatment tool comprises a
balloon.
14. The system of claim 12, wherein the treatment tool comprises a
stent.
15. The system of claim 12, wherein the treatment tool comprises a
filtering device.
16. The system of claim 15, wherein the filtering device comprises:
a proximal attachment point; a distal attachment point; a plurality
of struts connecting the proximal attachment point and the distal
attachment point, the struts configured to self-expand from the
collapsed configuration to an expanded configuration; and a filter
membrane coupled to the at least one of the struts and the distal
attachment point, wherein the filtering device is rotationally and
longitudinally movable relative to the core.
17. The system of claim 12, further comprising a catheter.
18. The system of claim 17, wherein the treatment tool is trackable
uncovered through the catheter from a proximal end of the catheter
to a distal end of the catheter.
19. The system of claim 17, wherein the catheter comprises a
balloon catheter.
20. The system of claim 17, wherein the catheter comprises a stent
catheter.
21. The system of claim 17, wherein the catheter has an inner
diameter that is no more than 0.017 inches.
Description
INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 11/859,272, filed Sep. 21, 2007 and issued as
U.S. Pat. No. 9,034,007 on May 19, 2015. Any and all applications
for which a foreign or domestic priority claim is identified in the
Application Data Sheet as filed with the present application are
hereby incorporated by reference under 37 C.F.R. .sctn.1.57.
FIELD OF INVENTION
[0002] This invention is related generally to the field of
intravascular medical devices. Particularly a distal embolic
protection device as well as methods for use of the device during
neurovascular interventional procedures in the cerebral arterial
blood vessels.
BACKGROUND OF INVENTION
[0003] Stroke is the leading cause of long term disability in the
United States and the second leading cause of death worldwide with
over 4.4 million deaths in a year (1999)..sup.1 There are over
700,000 new strokes every year in the United States..sup.2 Around
85% of all strokes are acute ischemic strokes caused from a
blockage in a blood vessel or a blood clot occluding a blood
vessel..sup.2 In 1996, the FDA approved a thrombolytic drug to
dissolve blood clots called recombinant tissue plasminogen
activator (r-tpa)..sup.3 Despite practice guidelines from multiple
national organizations stating the intravenous r-tpa is the
standard of care for patients with acute ischemic stroke within 3
hours from symptom onset,.sup.3 only 3-4% of patients with acute
ischemic stroke received this drug in the United States..sup.4
Unlike intravenous r-tpa, Intra-arterial infusion of thrombolytic
agents can be used for up to 6 hours from acute ischemic stroke
symptom onset and could benefit more people..sup.5 Currently,
intra-arterial infusion of thrombolytic agents are administered to
a blood clot and the blood clot breaks up into smaller blood clots
and travel downstream and potentially close up smaller cerebral
blood vessels. With advances in regional stroke networks, there are
more and more stroke patients who are getting access to
intra-arterial thrombolysis and therapies, and are as high as
21.6%..sup.4 However, there is no currently available distal
embolic protection device that is dedicated to the cerebral blood
vessels.
[0004] More than 8% of all acute ischemic strokes are from
blockages in the cervical or neck carotid artery..sup.2 Studies
have shown that performing percutaneous balloon angioplasty and
stenting on these blockages result in emboli or debris being
dislodged downstream and could cause further strokes and therefore
there have been large clinical trials of angioplasty and stenting
of the carotid artery in the neck with distal embolic protection
devices being used..sup.6 In addition to blockages in the neck
region of the carotid artery, more than 8% of all acute ischemic
strokes are due to blockages in the cerebral arterial blood vessels
called intracranial stenosis..sup.2 Recently there has been a new
device approved for intracranial angioplasty and stenting..sup.7
Although the risks of small emboli or debris being dislodged during
intracranial angioplasty and stenting is similar to the cervical
carotid artery and the rest of the body, there are no distal
embolic protection devices in the market dedicated for cerebral
arterial blood vessels. In addition, the distal embolic protection
devices currently available for the cervical carotid artery are too
bulky for use in the tortuous and fragile cerebral arterial blood
vessels.
[0005] Embolic protection devices have been developed for the
cervical carotid artery prior to carotid angioplasty and
stenting..sup.6 However, these devices do not have a small profile
for use in the cerebral arterial blood vessels and will not be able
to track and traverse the tortuous cerebral arterial blood
vessels.
[0006] Barbut in U.S. Pat. No. 6,165,199 has described embolic
protection devices that can be used for the cerebral arterial blood
vessels. This is a proximal embolic protection device wherein the
embolic protection device is before the clot or blockage comprising
of a proximal balloon occlusion catheter to create flow arrest and
an aspiration device to suction out the emboli or debris during the
interventional procedure in the cervical and cerebral blood
vessels. The drawbacks of a proximal protection device are that the
flow arrest performed to decrease emboli or debris from traveling
downstream can be detrimental in itself, since creating a flow
arrest in an already ischemic blood vessel during the long
neurovascular interventional procedures would in itself worsen the
cerebral ischemia and worsen the strokes. Bose et al in U.S. Pat.
No. 6,669,721 describe thin-film distal embolic protection devices
that can be potentially used in the cerebral blood vessels. The
device has one or two rings and a thin-film filter that is attached
to the guidewire. The drawbacks of this device is that during
neurovascular interventional procedures, there is constant exchange
of microcatheters, balloon catheters, and stent catheters over the
guidewire or microguidewire, and a distal embolic protection device
that is rigidly fixed to the guidewire or microguidewire would
cause trauma to the cerebral arterial blood vessel wall as there
will not be any mobility of the wire independent of the distal
embolic protection device. Hopkins et al in U.S. Pat. No. 6,544,279
B1 describe distal embolic protection devices that do have mobility
over a guidewire or microguidewire, however these guidewires or
microguidewires are of uniform thickness and the mobile attachment
point in these devices extend through the entire length of the
device. Current microguidewires used in neurovascular
interventional procedures to perform intracranial angioplasty and
stenting among other procedures use microguidewires in the
thickness of 0.014 inch (0.356 mm)..sup.7 Current microcatheters
used for intracranial cerebral blood vessel catheterization for
stroke as well as during intracranial angioplasty and stenting have
an inner diameter of about 0.017 inch (0.432 mm). Having a distal
embolic protection device mounted on a uniform thickness
microguidewire of a thickness of 0.014 inch (0.356 mm) will not
permit the distal embolic protection device in the collapsed form
to have a thin enough or small enough profile to be compatible with
existing microcatheters that are 0.017 inch (0.432 mm) in inner
diameter. Having a distal embolic protection device mounted on a
uniform thickness microguidewire with a mobile attachment point
that extends through the entire length of the device will increase
the overall thickness of the device in the collapsed configuration
thereby limiting the trackability of the device and inhibiting
access to the tortuous and narrow cerebral arterial blood
vessels.
BRIEF SUMMARY OF INVENTION
[0007] The present invention provides a distal embolic protection
device that can be used for neurovascular interventional procedures
including, but not limited to, intra-arterial thrombolytic or clot
dissolving drug infusion for acute ischemic stroke, as well as
percutaneous transluminal intracranial balloon angioplasty and
stenting procedures for patients at risk for stroke so that the
small emboli or debris that are dislodged during these procedures
can be retrieved safely. The distal embolic protection device of
this invention has a thin and small profile such that they are
compatible with existing standard microcatheters. The distal
embolic protection device of this invention is not attached to a
balloon or stent. The present invention also addresses the
limitations of all the prior art on embolic protection devices
discussed above as well as those that have been referenced.
[0008] An object of this invention is to have a distal embolic
protection device that is dedicated to the cerebral arterial blood
vessels and is suitable for use in cerebral arterial blood vessels
of 1.5 mm to 4.5 mm in diameter. The definition of cerebral
arterial blood vessels is described in the detailed description of
FIGS. 1, 2 and 3.
[0009] Another object of this invention is to have an embolic
protection device that does not have to cause flow arrest to
provide embolic protection. Devices that cause flow arrest have a
risk of worsening a stroke. Therefore the embolic protection device
of this invention is distal rather than proximal to the blockage or
blood clot and not proximal to the blockage or blood clot.
[0010] Another object of this invention is to have a distal embolic
protection device that can pass through the tortuous cerebral
arterial blood vessels with no or little trauma to the vessels.
Current embolic protection devices are transported or moved through
catheters using a small stearable microwire. Due to the bulky
nature of current embolic protection devices, it is very difficult
to navigate through even in straight blood vessels leave alone
tortuous blood vessels.
[0011] Another object of this invention is to have a distal embolic
protection device comprising a collapsible filtering device that
has a small thin profile so that in the collapsed configuration of
the filtering device, the thickness of the distal embolic
protection device is no more than about 0.017 inch (0.432 mm),
preferably no more than about 0.014 inch (0.356 mm), and can be
delivered and retrieved via a standard microcatheter (inner
diameter of 0.017 inch, 0.432 mm), a balloon catheter or stent
catheter that are used in neurovascular interventional procedures.
The filtering device is not attached to a balloon or stent.
[0012] Another object of this invention is a distal embolic
protection device comprising a variable thickness microguidewire
and a collapsible filtering device, wherein the filtering device is
rotatably mounted on the distal segment of the variable thickness
microguidewire. The variable thickness microguidewire comprises a
thinner segment bordered on both ends by thicker segments. The
thinner segment is no more than about 0.010 inches in thickness and
preferably about 0.008 to 0.010 inch (0.203 to 0.254 mm). The
thicker segments, which make up the majority of the microguidewire,
are thicker than the thinner segment and preferably no more than
0.017 inch (0.432 mm) in thickness, more preferably no more than
about 0.014 inch (0.356 mm). The variable thickness microguidewire
may comprise a core microguidewire that extends through the entire
length, or a portion of, of the microguidewire and a coating or
covering or flexible hypotube or a combination thereof over the
core microguidewire. The filtering device is mounted on the thinner
segment, which is in the distal segment of the microguidewire to
maintain a small thin profile so that trackability is maintained as
well as compatibility with existing microcatheters, balloon
catheters and stent catheters that are used in neurovascular
interventional procedures. Preferably the small thin profile is no
more than about 0.017 inch (0.432 mm) and more preferably no more
than about 0.014 inch (0.356 mm).
[0013] Another object of this invention is a distal embolic
protection device comprising a variable thickness microguidewire
and a filtering device, wherein the microguidewire and filtering
device have rotational and longitudinal movement relative to and
independently of each other, such that the filtering device can
remain stable within the blood vessel while there is motion on the
microguidewire both in the rotational as well as longitudinal
directions relative to the filtering device so that there is no, or
very limited, trauma to the fragile cerebral arterial blood
vessels.
[0014] The filtering device of the distal embolic protection device
of this invention may comprise mobile attachment points on its
proximal and distal ends wherein the mobile attachment points
attach the filtering device to the microguidewire. The mobile
attachment points are of such a size that that the thickness of the
filtering device in the collapsed configuration is smaller than a
cerebral arterial blood vessel and can pass through standard
microcatheters that are used in neurovascular interventional
procedures. Preferably the attachment points in conjunction with
the filtering device in the collapsed configuration are no more
than about 0.017 in (0.432 mm), and more preferably not more than
about 0.014 inch (0.356 mm) in thickness. Preferably the attachment
points are short and abut, but do not cover, the thicker segments
of the microguidewire.
[0015] In an embodiment of this invention, the distal embolic
protection device comprises a filtering device rotatably mounted on
the thinner segment of the microguidewire, and further comprises
cylindrical coils that wind around the thinner segment of the
microguidewire and connect the proximal and distal ends of the
filtering device to the proximal and distal stops of the thicker
segments of the microguidewire. The attached cylindrical coils
decrease the shear stress on the thinner segment of the
microguidewire during the retrieval of the distal embolic
protection device.
[0016] Another object of this invention the distal embolic
protection device comprises a radio-opaque portion that enables the
device to be visualized during fluoroscopic neurovascular
interventional procedures. For example, the thicker segments of the
microguidewire, or the distal end of the microguidewire, or the
filtering device itself may comprise radio-opaque sections so that
the operator during a medical procedure can distinguish the
filtering device and its position relative to the thicker and
thinner segments of the microguidewire.
[0017] The distal embolic protection devices of this invention are
dedicated to use in cerebral arterial blood vessels and their use
in the treatment of existing stroke patients and patients that are
at risk for strokes. The methods of this invention include e.g.,
crossing a vascular blockage or blood clot with a standard
microcatheter and microwire. Then removing the microwire and once
the microwire is removed, the distal embolic protection device is
advanced via the microcatheter to the desired location. As the
distal embolic protection device is not involved in navigation, it
is able to pass the tortuous curves of the cerebral blood vessels
due to the novel delivery system. The microguidewire is also
designed to be compatible with existing microcatheters, balloon
catheters and stent catheters used in neurovascular interventions.
In addition, the stops in the distal part of the microguidewire and
the mobile attachment points on the filtering device allow for
mobility of the microguidewire both in the rotatory and
longitudinal directions relative to the filtering device, wherein
the filtering device is stable in the cerebral blood vessel thereby
minimizing vessel trauma or dissections. The variable thickness of
the distal part of the microguidewire also allows for the smaller
overall profile of the device and improves its compatibility with
existing microcatheters, balloon catheters, and stent catheters.
The small profile also allows for easy retrieval of the distal
embolic protection device of this invention using existing
microcatheters, balloon catheters or stent catheters making the
procedure shorter and safer.
[0018] The methods of this invention for collecting thrombo-embolic
material, debris or clots released during percutaneous
neurovascular interventional procedures specifically performed in
the cerebral arterial blood vessels, comprises inserting the distal
embolic protection device of this invention into a cerebral
arterial blood vessel having an area of stenosis or a clot,
deploying the filtering device distal to the area of blockage or
clot and allowing the filtering device to expand to fill the
diameter of the cerebral arterial blood vessel. The methods of this
invention may further comprise advancing a standard microcatheter
over a standard microwire across the area of stenosis or clot,
positioning the microcatheter distal to the stenosis or clot,
withdrawing the microwire, and advancing the distal embolic
protection device through the standard microcatheter. The thickness
of the thicker segments of the variable thickness microguidewire is
no more than about 0.017 inch (0.432 mm) and preferably no more
than about 0.014 inch (0.356 mm) such that it is compatible for use
with standard microcatheters, which have an inner lumen diameter of
about 0.017 inch (0.432 mm). In addition, the methods of this
invention may further comprise withdrawing the microcatheter, while
keeping the microguidewire in position distal to the stenosis or
clot, unsheathing the distal embolic protection device and
expanding the filtering device to the inside size of the cerebral
arterial blood vessel, ranging from 1.5 mm to 4.5 mm, and wherein
the expanded shape of the filter membrane is a hemispherical,
helical or conical shape and spans the cerebral arterial blood
vessel. The method may also comprise maintaining the microguidewire
in position, exchanging the standard microcatheter for (1) a
balloon catheter to perform balloon angioplasty of the cerebral
arterial blood vessels, or (2) a stent catheter to perform stenting
of the cerebral arterial blood vessels, and collecting any debris
or clots that are dislodged during the balloon angioplasty and or
stenting in the cerebral arterial blood vessels in the filter
membrane. The methods of this invention also comprise maintaining
the microguidewire in position and administering clot dissolving
drugs or thrombolytics to a patient in need thereof through a
standard microcatheter, such that any debris or clots that are
dislodged will be collected by the filter membrane. The methods of
this invention may comprise additional steps, e.g., recovering the
distal embolic protection device by advancing a standard
microcatheter, balloon catheter, or stent catheter over the
variable thickness microguidewire, and withdrawing the distal
embolic protection device and the standard microcatheter, balloon
catheter or stent catheter.
[0019] Various embodiments of the present invention are shown in
the figures and described in detail below.
BRIEF DESCRIPTION OF INVENTION/FIGURES
[0020] FIG. 1 is a schematic diagram illustrating the origin of the
great vessels from the heart.
[0021] FIG. 2 is a schematic diagram illustrating the cervical and
cerebral course of the internal carotid arteries and their
branches.
[0022] FIG. 3 is a schematic diagram illustrating the cervical and
cerebral course of the vertebral arteries and their branches.
[0023] FIG. 4 is a schematic diagram illustrating the Circle of
Willis and the main collateral blood vessel pathways in the
brain.
[0024] FIG. 5 illustrates the introducer system for delivery of the
distal embolic protection device into the microcatheter.
[0025] FIG. 6 illustrates the introducer sheath and its
components.
[0026] FIG. 7A illustrates a magnified cross sectional view of an
introducer sheath with the distal embolic protection device
comprising the filtering device and variable thickness
microguidewire. FIG. 7B illustrates a magnified view of the
variable-thickness microguidewire with the filtering device mounted
on it and shown in a collapsed configuration within the
microcatheter.
[0027] FIGS. 8A and 8B illustrate the microguidewires in two
lengths 300 cm and 190 cm respectively.
[0028] FIG. 9A is an illustration of the distal segment of the
microguidewire (distal 30 cm). FIGS. 9B, 9C and 9D are magnified
views of embodiments of the variable thickness microguidewire with
different components of the distal segment of the microguidewire
illustrated (distal 30 cm).
[0029] FIG. 10 is an illustration of one of the embodiments of the
distal embolic protection device.
[0030] FIG. 11 is a schematic diagram illustrating the
cross-sectional view of the distal embolic protection device
described in FIG. 10.
[0031] FIG. 12 illustrates one of the embodiments of a distal
embolic protection device in the expanded configuration showing the
radio-opaque components under fluoroscopy.
[0032] FIG. 13 illustrates another embodiment of a distal embolic
protection device over the variable thickness microguidewire.
[0033] FIG. 14A is an illustration of another embodiment of the
distal embolic protection device.
[0034] FIG. 14B is a schematic diagram illustrating the
cross-sectional view of the distal embolic protection device
described in FIG. 14A.
[0035] FIG. 15A is an illustration of another embodiment of the
distal embolic protection device.
[0036] FIG. 15B is a schematic diagram illustrating the
cross-sectional view of the distal embolic protection device
described in FIG. 15A.
[0037] FIG. 16 is a schematic diagram illustrating a significant
blockage or stenosis 585 in the right middle cerebral artery
105.
[0038] FIG. 17 is a schematic diagram illustrating a microcatheter
being advanced into the right middle cerebral artery over a
microwire.
[0039] FIG. 18 is a schematic diagram illustrating the
microcatheter has been carefully advanced across the blockage in
the right middle cerebral artery over a microwire.
[0040] FIG. 19 is a schematic diagram illustrating the introducer
sheath with the non-expanded distal embolic protection device and
microguidewire are being advanced through the microcatheter.
[0041] FIG. 20 is a schematic diagram illustrating the distal
embolic protection device in the appropriate location distal to the
blockage and the microcatheter being withdrawn to deploy the
device.
[0042] FIG. 21 is a schematic diagram illustrating the distal
embolic protection device fully deployed.
[0043] FIG. 22 is a schematic diagram illustrating intracranial
angioplasty being performed using the distal embolic protection
device.
[0044] FIG. 23 is a schematic diagram illustrating intracranial
stenting being performed using the distal embolic protection
device.
[0045] FIG. 24 is a schematic diagram of a standard microcatheter
used to recover the distal embolic protection device.
[0046] FIG. 25 is a schematic diagram illustrating the stent
catheter or the tip of the standard microcatheter being advanced
over the microguidewire to retrieve the distal embolic protection
device.
[0047] FIG. 26 is a schematic diagram illustrating the distal
embolic protection device being safely retrieved by either the
stent catheter or a standard microcatheter.
[0048] FIG. 27 is a schematic diagram illustrating another use for
this distal embolic protection device namely during intra-arterial
thrombolysis for thrombus or blood clot causing acute ischemic
stroke.
[0049] FIG. 28 is a schematic diagram illustrating a standard
microcatheter being advanced across the thrombus or blood clot in
the right middle cerebral artery over a microwire.
[0050] FIG. 29 is a schematic diagram illustrating a distal embolic
protection device being deployed distal to the thrombus or blood
clot causing the stroke and then the microcatheter is withdrawn
back and intra-arterial thrombolysis is initiated.
[0051] FIG. 30 is a schematic diagram illustrating the retrieval of
the distal embolic protection device with the standard
microcatheter.
DETAILED DESCRIPTION OF INVENTION/FIGURES
[0052] FIG. 1 is a schematic diagram that illustrates the heart,
the aorta and the supra-aortic vessels. The left ventricle 5 is one
of the chambers of the heart and pumps oxygenated blood to the rest
of the body through the aorta 10. The innominate artery 15 is one
of the great vessels originating from the aorta 10 and divides into
two branches namely the right subclavian artery 20 and the right
common carotid artery 25. The right common carotid artery 25 gives
off the right internal carotid artery 30 that continues
intracranially to supply the anterior circulation or the front of
the brain (see FIG. 2 for further details), and the right external
carotid artery 35 which continues to supply the scalp, face and
neck. The right subclavian artery 20 gives off several branches
including the right vertebral artery 40 which continues
intracranially to supply the posterior circulation or the back of
the brain (see FIG. 3 for further details). The next great vessel
originating from the aorta 10 is the left common carotid artery 45.
The left common carotid artery 45 divides into the left internal
carotid artery 50, which continues intracranially to supply the
anterior circulation or the front of the brain (see FIG. 2 for
further details), and the left external carotid artery 55, which
continues to supply the scalp, face and neck. This portion of the
aorta 10 from which the left common carotid artery arises is also
known as the aortic arch 60. The left subclavian artery 65 arises
from the aortic arch 60 and gives off several branches including
the left vertebral artery 70 which continues intracranially to
supply the posterior circulation or the back of the brain (see FIG.
3 for further details). Subsequent to the origin of the left
subclavian artery 65, the aortic arch curves inferiorly or
downwards and is known as the descending aorta 75 which continues
to supply the abdomen, spine and lower extremities.
[0053] FIG. 2 is a schematic diagram illustrating the cervical and
intracranial course of the internal carotid arteries. The right
common carotid artery 25 divides into the right external carotid
artery 35 and the right cervical internal carotid artery 30 in the
neck. The right internal carotid artery in the cervical or neck
portion 30 enters the base of skull and continues as the petrous
portion of the right internal carotid artery 80. The petrous
portion of the right internal carotid artery 80 then continues as
the tortuous cavernous portion of the right internal carotid artery
85. The right internal carotid artery then pierces the dura or
covering layering of the brain to form the supraclinoid portion of
the right internal carotid artery 90 and gives off the right
posterior communicating artery 95 which helps form the circle of
Willis or the collateral pathway to other blood vessels in the
brain (see FIG. 4 for further details). The supraclinoid portion of
the right internal carotid artery 90 then bifurcates 100 into the
right middle cerebral artery 105 as well as the right anterior
cerebral artery 120 at the right internal carotid artery
bifurcation 100. The right middle cerebral artery divides into
several branches and the main ones being the right middle cerebral
artery superior division 110 and the right middle cerebral artery
inferior division 115. The A1 segment of the right anterior
cerebral artery 120 further continues as the A2 segment of the
right anterior cerebral artery 125 and at the junction of the A1
and A2 segments gives off an important branch called the anterior
communicating artery 130 that communicates with the blood vessels
from the left side of the brain to also form the circle of
Willis.
[0054] The left common carotid artery 45 divides into the left
external carotid artery 55 and the left cervical internal carotid
artery 50 in the neck. The left internal carotid artery in the
cervical or neck portion 50 enters the base of skull and continues
as the petrous portion of the left internal carotid artery 180. The
petrous portion of the left internal carotid artery 180 then
continues as the tortuous cavernous portion of the left internal
carotid artery 175. The left internal carotid artery then pierces
the dura or covering layering of the brain to form the supraclinoid
portion of the left internal carotid artery 165 and gives off the
left posterior communicating artery 170 which helps form the circle
of Willis or the collateral pathway to other blood vessels in the
brain. The supraclinoid portion of the left internal carotid artery
165 then bifurcates 145 into the left middle cerebral artery 150 as
well as the left anterior cerebral artery 140 at the left internal
carotid artery bifurcation 145. The left middle cerebral artery
divides into several branches and the main ones being the left
middle cerebral artery superior division 155 and the left middle
cerebral artery inferior division 160. The A1 segment of the left
anterior cerebral artery 140 further continues as the A2 segment of
the left anterior cerebral artery 135 and at the junction of the A1
and A2 segments gives off an important branch called the anterior
communicating artery 130 that communicates with the blood vessels
from the right side of the brain to also form the circle of
Willis.
[0055] In this invention, the internal carotid arteries from the
petrous, cavernous and supraclinoid portions and their branches,
along with the middle cerebral and anterior cerebral arteries and
their branches are considered as cerebral arterial blood vessels
(80 to 180).
[0056] FIG. 3 is a schematic diagram illustrating the course of the
bilateral vertebral arteries and their branches. The right
vertebral artery 40 is a branch of the right subclavian artery 20.
The first portion of the right vertebral artery in the cervical or
neck portion is called the V1 segment of the right vertebral artery
40. The right vertebral artery continues in the neck as the V2
segment of the right vertebral artery 185 and travels close to the
base of brain. It makes a tortuous curve and is called the V3
segment of the right vertebral artery 190 and finally pierces the
dura or outer covering layer of the brain and forms the V4 segment
of the right vertebral artery 195. The V4 segment of the right
vertebral artery 195 gives off an important branch to the right
cerebellum called the right posterior-inferior cerebellar artery
200 and then joins together with the V4 segment of the left
vertebral artery 255 at the vertebro-basilar junction 205 to form
the basilar artery 210. The basilar artery 210 gives off several
branches including the bilateral anterior inferior cerebellar
arteries 215 and 245, as well as, the bilateral superior cerebellar
arteries 220 and 240, and then bifurcates at the basilar apex 225
into the bilateral posterior cerebral arteries 230 and 235. The
right posterior communicating artery 95 communicates with the right
posterior cerebral artery 230 (see FIG. 4 for further details). The
left posterior communicating artery 170 communicates with the left
posterior cerebral artery 235 (see FIG. 4 for further details). The
left vertebral artery 70 is a branch of the left subclavian artery
65. The first portion of the left vertebral artery in the cervical
or neck portion is called the V1 segment of the left vertebral
artery 70. The left vertebral artery continues in the neck as the
V2 segment of the left vertebral artery 265 and travels close to
the base of brain. It makes a tortuous curve and is called the V3
segment of the left vertebral artery 260 and finally pierces the
dura or outer covering layer of the brain and forms the V4 segment
of the left vertebral artery 255. The V4 segment of the left
vertebral artery 255 gives off an important branch to the left
cerebellum called the left posterior-inferior cerebellar artery 250
and then joins together with the V4 segment of the right vertebral
artery 195 at the vertebro-basilar junction 205 to form the basilar
artery 210.
[0057] In this invention, the vertebral arteries from the V2, V3,
and V4 segments and their branches, along with the basilar artery
and the bilateral posterior cerebral arteries and their branches
are also considered as cerebral arterial blood vessels (185 to
265).
[0058] FIG. 4 is a schematic diagram illustrating the main
collateral pathways and communications between the cerebral
arterial blood vessels including the internal carotid artery system
(90 to 170) as well as the vertebro-basilar artery system (205 to
245), and this is known as the Circle of Willis. The supraclinoid
portion of the right internal carotid artery 90 gives off the right
posterior communicating artery 95 which anastomoses or communicates
with the right posterior cerebral artery 230 and helps form the
posterior part of the circle of Willis. The supraclinoid portion of
the right internal carotid artery 90 then bifurcates 100 into the
right middle cerebral artery 105 as well as the right anterior
cerebral artery 120 at the right internal carotid artery
bifurcation 100. The A1 segment of the right anterior cerebral
artery 120 further continues as the A2 segment of the right
anterior cerebral artery 125 and at the junction of the A1 and A2
segments gives off an important branch called the anterior
communicating artery 130 that anastomoses or communicates with the
junction of the A1 segment 140 and A2 segments 135 of the left
anterior cerebral artery and helps form the anterior part of the
circle of Willis. The supraclinoid portion of the left internal
carotid artery 165 gives off the left posterior communicating
artery 170, which anastomoses or communicates with the left
posterior cerebral artery 235 and helps form the posterior part of
the circle of Willis. The supraclinoid portion of the left internal
carotid artery 165 then bifurcates 145 into the left middle
cerebral artery 150 as well as the left anterior cerebral artery
140 at the left internal carotid artery bifurcation 145. The A1
segment of the left anterior cerebral artery 140 further continues
as the A2 segment of the left anterior cerebral artery 135 and at
the junction of the A1 and A2 segments gives off an important
branch called the anterior communicating artery 130 that
communicates with the junction of the A1 segment 120 and A2
segments 125 of the right anterior cerebral artery and helps form
the anterior part of the circle of Willis. The anterior 130 and
posterior communicating arteries 95 and 170 help with the
anastomoses or communication of the internal carotid artery system
(90 to 170) with the vertebro-basilar arterial system (205 to 245)
and helps maintain an adequate collateral pathway for blood supply
in the brain (see FIG. 2 for further details on the course of the
internal carotid arteries and see FIG. 3 for further details on the
course of the vertebral arteries). There are numerous anatomic
variations to this and can play an important role at the time of a
stroke.
[0059] FIG. 5 illustrates an introducer system to deliver the
distal embolic protection device into the microcatheter. The
microguidewire 290 that contains the distal embolic protection
device is housed in a protective spiral polymer case 270 to avoid
kinks or bends in the microguidewire. The spiral loops of the
protective polymer case are kept together by clasps 275. The
proximal end of the microguidewire is at the inner end of the
spiral polymer case. The distal end of the microguidewire with the
distal embolic protection device are kept in an introducer sheath
305 that is made out of a polymer (such as Teflon) and the portion
of the introducer sheath 310 directly overlying the distal embolic
protection device and protecting it is shown in this figure. The
proximal end of the introducer sheath has a hemostatic valve 295
and a port for attaching a saline flush syringe 300 to be able to
saline flush the introducer sheath as well as the distal embolic
protection device of any air. The distal end of the introducer
sheath 315 is the part that helps feed the distal embolic
protection device into the microcatheter. When the distal
protection device needs to be loaded into the microcatheter, the
introducer sheath is removed from the clasps, of the spiral polymer
case 275 and the microguidewire is slowly pulled off the distal
port of the spiral polymer case 285.
[0060] FIG. 6 illustrates the introducer sheath 305 as well as the
portion of the distal end of the introducer sheath 310 directly
overlying the distal embolic protection device and protecting it.
When the saline syringe 325 is connected to port 300 of the
introducer sheath and is flushed, then the hemostatic valve is
locked at the proximal end 295, and saline drops 320 will be noted
to arise from the tip of the introducer sheath 315 because of
saline moving in the direction 330 of the tip of the introducer
sheath 315 suggesting that the introducer sheath 305 and the
portion of the distal end of the introducer sheath 310 directly
overlying the distal embolic protection device have been flushed of
air.
[0061] FIG. 7A illustrates the distal embolic protection device
comprising the filtering device in the collapsed configuration 350
that is back loaded into the introducer sheath 305 over the
microguidewire. FIG. 7B illustrates a magnified view of the distal
embolic protection device comprising the filtering device in a
collapsed configuration mounted on the variable thickness
micro-guidewire. The length of the microguidewire is sufficient for
use in existing microcatheters during interventional neurovascular
procedures and preferably ranges from 190 to 300 cm in length. The
majority of the proximal 290 and distal 335 microguidewire are
around 0.014 inch (0.356 mm) in thickness to be compatible with
existing microcatheters, balloons and stents that are used in
neurovascular interventions. Part of the distal segment of the
microguidewire 335, e.g., 135 cm, is shown in the figure. The
distal segment of the microguidewire has a thinner segment 360 that
is about 0.010 inch (0.254 mm) or less in thickness and this is in
the location where the filtering device is mounted. The filtering
device is depicted in a collapsed configuration 350. The thinner
segment 360 of the microguidewire where the filtering device is
located is much thinner than the rest of the microguidewire 335 and
is no more than about 0.010 inch (0.254 mm) and preferably measures
about 0.008 to 0.010 inch (0.203 mm to 0.254 mm) in thickness. This
is to maintain a small thin profile of the filtering device in the
collapsed or non-expanded configuration within the inner lumen of
the introducer sheath 370 so that the overall thickness of the
distal embolic protection device, comprising the microguidewire and
filtering device in the collapsed configuration are kept to a
thickness less than or equal to 0.017 inch (0.432 mm) to be
compatible with existing microcatheters, balloons, and stents. The
thinner segment 360 of the microguidewire meets the thicker segment
of the microguidewire at the proximal stop 340 and distal stop 375.
The proximal 340 and distal stops 375 are no more than about 0.017
inch (0.432 mm) and preferably range from 0.014 inch to 0.017 of an
inch (0.356 mm to 0.432 mm). The filtering device 350 has proximal
345 and distal 355 attachment points that allow the filtering
device to be mobile over the microguidewire in the rotatory and
longitudinal directions, relative to the microguidewire. The
movement of the filtering device relative to the microguidewire is
limited to within the thinner segment of the microguidewire 360 by
the proximal 340 and distal stops 375. The microguidewire distal
365 to the distal stop 375 comprises several components that are
further described in FIG. 9 and includes a shapeable tip 395,
preferably curved, to enable torquability and to avoid wire
perforation of a small vessel. The microguidewire may comprise a
marker 380 at a predetermined location, e.g. at 135 cm from the
distal tip of the microguidewire, to aid in determining when the
distal embolic protection device is likely to emerge from the
distal end of the microcatheter (normally 135 cm to 175 cm in
length) and in determining the progress and location of the distal
embolic protection device within the cerebral arterial blood
vessel. Preferably the 135 cm marker is visually detectable by the
operator so that fluoroscopy can be avoided till approximately 135
cm of the microguidewire has been advanced through the
microcatheter.
[0062] FIGS. 8A and 8B illustrate the components of the
microguidewire at two lengths namely an exchange length 300 cm
(FIG. 8A) and a non-exchange length microguidewire length 190 cm
respectively (FIG. 8B). The microguidewire is of variable thickness
at the distal end, having a thinner segment to accommodate a distal
embolic protection device. The majority of the microguidewire 335,
other than the thinner segment, is of thickness no more than about
0.014 inch (0.356 mm) and is compatible for use with existing
microcatheters, balloons, and stents used in neurovascular
interventions. A marking 380 on the microguidewire indicates the
135 cm length so that fluoroscopy can be avoided till approximately
135 cm of the microguidewire has been advanced through the
microcatheter. The distal segment of the microguidewire, where the
filtering device is present, comprises a thinner segment 360 having
a thickness that is no more than about 0.010 inch (0.254 mm) to
accommodate the non-expanded filtering device and still maintain an
overall low thickness profile of the distal embolic protection
device. The microguidewire has a proximal 340 and distal 375 stop
that will allow the filtering device to be stationary in a small
cerebral arterial blood vessel despite rotatory and longitudinal
motion of the microguidewire over a small distance. The proximal
and distal stops have a thickness of no more than about 0.017 inch
(0.432 mm) and preferably from 0.014 to 0.017 inch (0.356-0.432
mm). Part of the distal segment of the microguidewire 335 e.g.
distal 30 cm comprises several components that are further
described in detail in FIGS. 9A to 9D. The distal end includes a
distal tip 365 which may comprise radio-opaque shapeable material
to provide some trackability and to retain a curved shape to avoid
small vessel perforation. FIG. 8A shows an exchange length
microguidewire 300 cm in length. FIG. 8B shows a non-exchange
length microguidewire 190 cm in length. The non-exchange length
guidewire has a capability at its proximal end 385 to have an
extension microguidewire 390 attached if it needs to be converted
into an exchange length microguidewire.
[0063] FIG. 9A is an illustration of an embodiment of the distal
segment of the microguidewire e.g. distal 30 cm described in FIG.
8. FIGS. 9B, 9C and 9D are magnified views of the various
components of the distal segment of the variable thickness
microguidewire e.g. distal 30 cm. The microguidewire is of variable
thickness at the distal segment to accommodate a filtering device
at its distal end. The majority of the microguidewire 335 is no
more than about 0.014 inch (0.356 mm) in thickness, and is
compatible with existing microcatheters, balloons, and stents used
in neurovascular interventions. The microguidewire 335 comprises
various components including a core microguidewire 334 that runs
the entire length of the microguidewire and provides support and
trackability that is need for catheterization of the small cerebral
arterial blood vessels. The core microguidewire comprises of a
metal e.g. stainless steel or an alloy e.g nickel-titanium. The
core microguidewire 334 is no more than about 0.014 inch (0.356 mm)
in majority of its length in the proximal segment and is tapered to
no more than about 0.010 inch (0.254 mm) in the distal segment of
the microguidewire e.g distal 30 cm. The distal segment of the
microguidewire e.g. distal 30 cm comprises a core microguidewire
334 depicted in FIG. 9B-D that is no more than about 0.010 inch
(0.254 mm) in thickness forming the thinner segment of the
microguidewire 360 of FIGS. 9C-D, and comprises thicker segments
proximal to the proximal stop 340 as well as distal to the distal
stop 375, where the core may be coated or covered by another layer
or layers, e.g., a coil made up of a radio-opaque material or metal
or alloy such as platinum as shown in FIG. 9C forming the shapeable
tip of the microguidewire 395, or a flexible hypotube 336 of FIG.
9D covering the core microguidewire 334 or a combination of both as
shown in FIG. 9D. The coating, or covering, may provide more
support as well as trackability that is need for catheterization of
the small cerebral arterial blood vessels. The coated core
microguidewire is no more than about 0.014 inch (0.356 mm) in
thickness in the majority of its length. The various components of
this distal segment of the microguidewire are illustrated in more
detail in FIGS. 9B to 9D. The thinner segment of the microguidewire
360 is no more than about 0.010 inch (0.254 mm) to accommodate the
filtering device in its non-expanded state and still maintain an
overall low thickness profile of the distal embolic protection
device. In this thinner segment of the microguidewire where the
filtering device is mounted 360, the components of the
microguidewire are predominantly just the core microguidewire 334
as previously described. The distal end of the microguidewire 365
comprises several components that include a core microguidewire 334
as previously described, and a shapeable tip comprising a radio
opaque material, metal or alloy, e.g., platinum, that is shapeable
to provide some trackability and to retain a curved shape to avoid
small vessel perforation. In addition the shapeable tip of the
distal end of the microguidewire 365 may also include a coating or
covering layer, such as a flexible hypotube 336, covering the core
microguidewire 334 to give it more support and strength and is no
more than about 0.014 inch (0.356 mm) in the majority of its
length. The microguidewire has proximal 340 and distal 375 stops
that allow the filtering device to be stationary in a small
cerebral blood vessel despite rotatory and longitudinal motion of
the microguidewire relative to the filtering device between the
proximal and distal stops. The thickness of the stops is no more
than about 0.017 inch (0.432 mm) and preferably from 0.014 to 0.017
inch (0.356-0.432 mm).
[0064] Various components of the variable thickness microguidewire
may be made up of materials that are biocompatible or surface
treated to produce biocompatibility. Suitable materials include
e.g., stainless steel, platinum, titanium and its alloys including
nickel-titanium, etc. Suitable materials also include a combination
of metals and alloys such that the core of the microguidewire 334
forming the thinner segment 360 could be made from metals or alloys
such as stainless steel or nickel-titanium etc. In order to provide
a shapeable tip that has some trackability, and that has the
capacity to retain a curved shape to avoid small vessel
perforation, as well as be visible during neurovascular
interventional procedures, the distal end of the core
microguidewire 334 is preferably covered by a coating of a
radio-opaque material or metal or alloy, e.g., platinum. To provide
more support to the core microguidewire to be able to advance the
microguidewire along with the filtering device through a
microcatheter, the core microguidewire 334 may have a coating or
covering layer, e.g., a flexible hypotube, and made of metals or
alloys, e.g., nickel, titanium, platinum, tungsten etc. In the
areas where the microguidewire needs to be visible namely the parts
of the distal segment of the microguidewire 335 e.g. distal 30 cm
and the distal tip of the microguidewire 365 including the two
stops 340 and 375, the coating or covering layer over the core
microguidewire, or the flexible hypotube, or the core
microguidewire itself, comprise or are coated with radio-opaque
materials, metals or alloys, including but not limited to platinum,
tantalum, gold, palladium, tungsten, tin, silver, titanium, nickel,
zirconium, rhenium, bismuth, molybdenum, or combinations of the
above etc to enable visibility during neurovascular interventional
procedures.
[0065] FIG. 10 is an illustration of one of the embodiments of the
distal embolic protection device comprising the filtering device
and the microguidewire. The filtering device has a proximal 345 and
distal 355 attachment points that are also the sliding or mobile
components of the filtering device. These mobile attachment points
have a capacity to allow the microguidewire to rotate 430 as well
as move back and forth in the longitudinal direction 435 between
the two stops in the microguidewire (340, 375) while keeping the
filtering device stationary in a small cerebral blood vessel and
thereby decrease friction and trauma on the cerebral blood vessel
walls.
[0066] The filtering device of the distal embolic protection device
of this invention may comprise a filter membrane and an expansion
assembly capable of assuming an expanded configuration and a
collapsed configuration. Preferably the expansion assembly
comprises a plurality of struts (400, 405, 410) that connect the
proximal attachment point 345 to the distal attachment point 355.
The filter membrane may be attached to the struts and the distal
attachment point, and in the expanded configuration the filter
membrane has a hemispherical shape covering the struts.
[0067] The struts comprise a biocompatible material or materials
that are surface treated for biocompatibility. The materials are
preferably self-expanding. Suitable materials include but are not
limited to stainless steel, titanium and its alloys,
cobalt-chromium alloy, carbon fiber and its composites, and various
biomedical polymers, e.g., polyurethane, polyethylene, polyester,
polypropylene, poly tetra fluoro-ethylene, polyamides,
polycarbonate or polyethylene-terephthalate. A shape memory or
super-elastic material such as nickel-titanium alloy is also
suitable. The number of struts will depend on the size of expansion
needed for the diameter of the cerebral blood vessel. The distal
embolic protection device will be suitable for use in cerebral
blood vessels from vessel diameters of 1.5 mm to 4.5 mm.
[0068] In addition to the two stops in the microguidewire 340 and
375, as well as the two mobile attachment points in the filtering
device 345 and 355, various portions of the distal embolic
protection device including parts of the struts 400 to 410, or
parts of the filter membrane 415 may be radio-opaque. Radio-opaque
materials are understood as materials that are visible on a
fluoroscopy screen during neurovascular interventional procedures.
This allows the operator to determine the location of the device
during neurovascular interventions. Radio-opaque materials include,
e.g., metals or alloys including but are not limited to platinum,
tantalum, gold, palladium, tungsten, tin, silver, titanium, nickel,
zirconium, rhenium, bismuth, molybdenum, or combinations of the
above etc. The struts may comprise metals or alloys that are
radio-opaque, e.g., platinum or the others listed above.
Alternatively the struts may comprise shape-elastic alloys such as
nickel-titanium, which are not significantly radio-opaque but small
portions of radio-opaque metals or alloys, e.g., tantalum, can be
attached to non-radio-opaque struts by suturing the filter membrane
to the struts with tantalum wires or other suitable radio-opaque
material.
[0069] The filtering device also comprises a filter membrane 415
for collecting emboli or debris that might be released during the
neurovascular intervention. The filter membrane may comprise a
biomedical polymer, e.g., polyurethane (BioSpan.TM. made by Polymer
Technology Group and Chronoflex.TM. made by CardioTech
International), polyethylene (Rexell.TM. made by Huntsman),
polypropylene (Inspire.TM. made by Dow), polyester (Hytril.TM. made
by Dupont), poly tetra fluoro-ethylene (Teflon.TM. made by Dupont),
polyamides (Durethan.TM. made by Bayer), polycarbonate
(Corethane.TM. made by Corvita Corp), or polyethylene-terephthalate
(Dacron.TM. made by Dupont). The filter membrane may further
comprise a radio-opaque material, e.g., particles of tantalum,
particles of gold, other radio-opaque agents, e.g., barium sulfate,
tungsten powder, bismuth subcarbonate, bismuth oxychloride, iodine
containing agents such as iohexol (Omnipaque.TM. made by Amersham
Health). The filter membrane comprises pores 420 that are of the
dimensions small enough to trap emboli or debris but large enough
to allow the free passage of blood and its components such as blood
cells preferably the pores are of 50 microns to 150 microns. The
arrows 425 indicate the direction of blood flow within the blood
vessel.
[0070] The microguidewire is thinner between the two radio-opaque
stops 340 and 375 and in this thin segment 360, the microguidewire
thickness is no more than about 0.010 inch (0.254 mm). This is to
allow for the thickness of the filtering device comprising the
struts such that in its non-expanded state the distal embolic
protection device overall is no more than about 0.017 inch (0.432
mm). This is to enable the distal embolic protection device to be
delivered through standard microcatheters that are commercially
available (such as Echelon.TM. microcatheter, ev3 Inc;
Excelsior.TM. microcatheter, Boston Scientific Corp; Prowler.TM.
microcatheter, Cordis Neurovascular etc) that have an internal
diameter of around 0.017 inch (0.432 mm).
[0071] FIG. 11 is a schematic diagram illustrating the
cross-sectional view of the distal embolic protection device
described in FIG. 10. Some of the struts 400 and 405 are shown in
an expanded configuration, wherein the filter membrane 415 is
depicted with a hemispherical shape covering the struts. The
microguidewire 360 passing through the center of the filtering
device as well as the distal attachment point 355 of the filtering
device are also shown.
[0072] FIG. 12 is an illustration showing the distal embolic
protection device described in FIG. 10 in an expanded configuration
showing the radio-opaque components under fluoroscopy. The distal
segment of the microguidewire 335 e.g. distal 30 cm is radio-opaque
along with the proximal stop 340 and are made of radio-opaque
metals or alloys, e.g., platinum, as mentioned in description of
FIGS. 8A, 8B and 10. The microguidewire in the thinner segment 360
is not radio-opaque and is made up of a metal or alloy, e.g.,
nickel-titanium or stainless steel. The distal stop 375 as well as
the distal end of the microguidewire 365 including the shapeable
tip 395 are also made of a radio-opaque metal or alloy such as
platinum as described in detail in FIGS. 8A, 8B, and 10. Portions
of the struts 400 to 410 of the distal embolic protection device
described in FIG. 10 are also made of a radio-opaque metal or
alloy, e.g., platinum, or have a covering with a radio-opaque
material, e.g., tantalum as described in FIG. 10 in detail. This
enables the operator performing the neurovascular interventional
procedure to clearly visualize the deployed distal embolic
protection device as well as the position of the
microguidewire.
[0073] FIG. 13 is an illustration of another embodiment of a distal
embolic protection device of this invention comprising a filtering
device rotatably mounted on a variable-thickness microguidewire.
The filtering device has proximal 345 and distal 355 attachment
regions that are also the sliding or mobile components of the
distal embolic protection device. These mobile attachment points
have a capacity to allow the microguidewire to rotate 430 as well
as move back and forth in the longitudinal direction 435 between
the two stops in the microguidewire (340, 375) while keeping the
distal embolic protection device stationary in a small cerebral
blood vessel and thereby help decrease friction and trauma on the
cerebral blood vessel walls. The distal embolic protection device
in this embodiment comprises an expansion assembly comprising a
plurality of struts (400, 405, 410) that connect the proximal
attachment point 345 to the distal attachment point 355 and are
capable of assuming an expanded configuration and a collapsed
configuration The expanded configuration of the plurality of struts
and the filter membrane having a hemispherical shape is depicted.
The distal embolic protection device further comprises two
cylindrical coils 436 and 437. Cylindrical coil 436 connects the
proximal stop 340 to the proximal attachment point 345 of the
filtering device. Cylindrical coil 437 connects the distal
attachment point 355 of the filtering device to the distal stop 375
of the microguidewire. The cylindrical coils allow for rotatory 430
as well as longitudinal movement 435 of the filtering device
relative to the microguidewire in the thinner segment of the
microguidewire 360. The cylindrical coils decrease the shear stress
on the thinner segment of the microguidewire 360 when the distal
embolic protection device is recovered with a microcatheter,
balloon catheter or stent catheter. The coils provide added support
to the thinner segment of the microguidewire 360 and reduce
fracture or stretching of the microguidewire at the region of the
proximal stop 340 or distal stop 375. The cylindrical coils may be
made of a biocompatible material, or a material that is surface
treated to be biocompatible and may comprise radio-opaque metals or
alloys, e.g., platinum, as described in detail in FIG. 10.
[0074] FIG. 14A is an illustration of another of the embodiments of
the filtering device attached to the microguidewire. The filtering
device comprises proximal 455 and distal 460 attachment points that
are also the sliding or mobile components of the distal embolic
protection device. These mobile attachment points have a capacity
to allow the microguidewire to rotate 490 as well as move
longitudinal direction 495 between the two proximal and distal
stops of the microguidewire (340, 375) while the filtering device
remains stationary in the small cerebral blood vessel and thereby
help to decrease friction and trauma on the cerebral blood vessel
walls. The distal embolic protection device in this embodiment
comprises a filter membrane attached to the distal end of the
filtering device and an expansion assembly comprising a plurality
of struts 465, 470, 475 that connect the proximal attachment point
455 of the filtering device to the distal attachment point of the
filtering device 460. The plurality of struts in the expanded
configuration and the filter membrane having a helical or conical
shape and covering the struts is also depicted.
[0075] The struts, preferably made of a biocompatible material or a
material that is surface treated to be biocompatible and preferably
made of a self-expanding material, are detailed in the embodiment
described in FIG. 10. Suitable materials include but are not
limited to stainless steel, titanium and its alloys,
cobalt-chromium alloy, carbon fiber and its composites, and various
polymers. A shape memory or super-elastic material such as
nickel-titanium alloy is also suitable. The number of struts will
depend on the size of expansion needed for the diameter of the
cerebral blood vessel. The distal embolic protection device will be
suitable for use in cerebral blood vessels from vessel diameters
1.5 mm to 4.5 mm.
[0076] In addition to the two stops in the microguidewire 340 and
375, as well as the two mobile attachment points in the filtering
device 455 and 460, various portions of the distal embolic
protection devices of this invention including parts of the struts
505 and 510, or parts of the filter membrane 480 may be
radio-opaque. Radio-opaque materials are understood to be materials
that are visible on a fluoroscopy screen during neurovascular
interventional procedures. This allows the operator to determine
the location of the device during neurovascular interventions.
Radio-opaque materials include metals or alloys including but are
not limited to platinum, tantalum, gold, palladium, tungsten, tin,
silver, titanium, nickel, zirconium, rhenium, bismuth, molybdenum,
or combinations of the above. The struts can be made of metals or
alloys that are radio-opaque, e.g., platinum or the others listed
above. Alternatively the struts are made of shape-elastic alloys
such as nickel-titanium, which are not significantly radio-opaque,
and may further comprise small portions of radio-opaque metals or
alloys such as tantalum, that can be attached to the
non-radio-opaque struts by suturing the filter membrane to the
struts with a radio-opaque material, e.g. tantalum wires etc.
[0077] The filtering device comprises a filter membrane 480 to
capture emboli or debris that might be released during the
neurovascular intervention. The filter membrane is preferably a
biomedical polymer, e.g., polyurethane (BioSpan.TM. made by Polymer
Technology Group and Chronoflex.TM. made by CardioTech
International), polyethylene (Rexell.TM. made by Huntsman),
polypropylene (Inspire.TM. made by Dow), polyester (Hytril.TM. made
by Dupont), poly tetra fluoro-ethylene (Teflon.TM. made by Dupont),
polyamides (Durethan.TM. made by Bayer), polycarbonate
(Corethane.TM. made by Corvita Corp), or polyethylene-terephthalate
(Dacron.TM. made by Dupont). The filter membrane may further
comprise a radio-opaque material, e.g., particles of tantalum,
particles of gold, other radio-opaque agents such as barium
sulfate, tungsten powder, bismuth subcarbonate, bismuth
oxychloride, iodine containing agents such as Omnipaque.TM.. The
filter has pores 485 that are small enough to trap emboli or debris
but large enough to allow the free passage of blood and its
components such as blood cells, preferably the pores are 50 microns
to 150 microns in diameter. The arrows 500 indicate the direction
of blood flow within the cerebral blood vessel.
[0078] The microguidewire is thinner between the two radio-opaque
stops 340 and 375 and in this thinner segment 360, the
microguidewire thickness is no more than about 0.010 inch (0.254
mm). This is to accommodate the filtering device such that in its
non-expanded configuration the thickness of the filtering device is
less than or equal to 0.017 inch (0.432 mm). This is to enable the
distal embolic protection device to be delivered through standard
microcatheters that are commercially available (such as Echelon.TM.
microcatheter, ev3 Inc; Excelsior.TM. microcatheter, Boston
Scientific Corp; Prowler.TM. microcatheter, Cordis Neurovascular
etc) that have an internal diameter of about 0.017 inch (0.432
mm).
[0079] FIG. 14B is a schematic diagram illustrating the
cross-sectional view of the distal embolic protection device
described in FIG. 14A. The struts 465 to 475 are depicted in an
expanded configuration, providing the filtering device with a
helical or conical shape. The filter membrane 480 is depicted as
covering the struts 465, 470, 475. The microguidewire 360 passing
through the center of the filtering device as well as the distal
attachment point 460 of the filtering device are shown.
[0080] FIG. 15A is an illustration of another embodiment of the
distal embolic protection device. The filtering device has proximal
535 and distal 530 attachment points that are also the sliding or
mobile components of the filtering device. These mobile attachment
points have a capacity to allow the microguidewire to rotate 565 as
well as move back and forth in the longitudinal direction 570
relative to the filtering device between the two stops in the
microguidewire (340, 375) while keeping the filtering device
stationary in a small cerebral blood vessel and thereby decrease
friction and trauma on the cerebral blood vessel walls. The
filtering device in this embodiment comprises a filter membrane 555
and a ring 525. The filter membrane is attached to the ring and the
ring is connected to the proximal attachment point 535. The ring in
turn comprises a plurality of struts 540, 545, 550 that connect the
ring 525 to the distal attachment point 530. The ring and if
present the plurality of struts when expanded can provide the
filtering device with a conical shape.
[0081] The ring, and if present the plurality of struts, are made
of biocompatible materials or materials that are surface treated
such that they are biocompatible. The materials are preferably
self-expanding as described in FIG. 10. Suitable materials include
but are not limited to stainless steel, titanium and its alloys,
cobalt-chromium alloy, carbon fiber and its composites, and various
polymers. A shape memory or super-elastic material such as
nickel-titanium alloy is also suitable. The number of struts will
depend on the size of expansion needed for the diameter of the
cerebral blood vessel to be treated. The distal embolic protection
devices of this invention are suitable for use in cerebral blood
vessels from vessel diameters 1.5 mm to 4.5 mm.
[0082] In addition to the two stops in the microguidewire 340 and
375, as well as the two mobile attachment points in the device 535
and 530, various portions of the distal embolic protection device
including the ring 525, or parts of the filter membrane 555 may
further comprise a radio-opaque material. Radio-opaque materials
are understood as materials that are visible on a fluoroscopy
screen during neurovascular interventional procedures. This allows
the operator to determine the location of the device during
neurovascular interventions. Radio-opaque materials can include
metals or alloys, including but not limited to platinum, tantalum,
gold, palladium, tungsten, tin, silver, titanium, nickel,
zirconium, rhenium, bismuth, molybdenum, or combinations of the
above etc. The struts can be made up of metals or alloys that are
radio-opaque such as platinum or the others listed above.
Alternatively the struts may be made of shape-elastic alloys such
as nickel-titanium, which are not significantly radio-opaque, but
may be made radio-opaque by attaching small portions of
radio-opaque metals or alloys, e.g., tantalum, to the
non-radio-opaque struts by suturing the filter membrane to the
struts with a radio-opaque material, e.g., tantalum wires etc.
[0083] The filtering device comprises a filter membrane 555 that
extends from the ring 525 to the distal attachment point 530 and
acts as a filter for emboli or debris that might be released during
the neurovascular intervention. The filter membrane may cover the
struts. Materials for this filter include but are not limited to
biomedical polymers such as, e.g., polyurethane (BioSpan.TM. made
by Polymer Technology Group and Chronoflex.TM. made by CardioTech
International, polyethylene (Rexell.TM. made by Huntsman),
polypropylene (Inspire.TM. made by Dow), polyester (Hytril.TM. made
by Dupont), poly tetra fluoro-ethylene (Teflon.TM. made by Dupont),
polyamides (Durethan.TM. made by Bayer), polycarbonate
(Corethane.TM. made by Corvita Corp), or polyethylene-terephthalate
(Dacron.TM. made by Dupont). The filter has pores 560 that are
small enough to trap emboli or debris but large enough to allow the
free passage of blood and its components such as blood cells.
Preferably the pores are 50 microns to 150 microns. The arrows 575
indicate the direction of blood flow with the cerebral blood
vessel. The filter membrane may further comprise radio-opaque
materials, e.g., as particles of tantalum, particles of gold, other
radio-opaque agents, e.g., barium sulfate, tungsten powder, bismuth
subcarbonate, bismuth oxychloride, iodine containing agents such as
Omnipaque.TM..
[0084] The microguidewire is thinner between the two radio-opaque
stops 340 and 375 and in this thinner segment 360, the
microguidewire thickness is no more than about 0.010 inch (0.254
mm). This is to allow for the thickness of the distal embolic
protection device, the ring and the struts if present such that in
the non-expanded state the ring of the distal embolic protection
device is no more than about 0.017 inch (0.432 mm). This is to
enable the distal embolic protection device to be delivered through
standard microcatheters that are commercially available (such as
Echelon.TM. microcatheter, ev3 Inc; Excelsior.TM. microcatheter,
Boston Scientific Corp; Prowler.TM. microcatheter, Cordis
Neurovascular etc) that have an internal diameter of about 0.017
inch (0.432 mm).
[0085] FIG. 15B is a schematic diagram illustrating the
cross-sectional view of the distal embolic protection device
described in FIG. 15A. The radio-opaque ring is shown 525 and is
attached to a filter membrane 555 connecting the ring to the distal
attachment point 530. The filter membrane has micro-pores 560. In
one of the embodiments of this device, there is also a plurality of
struts 540 to 550 connecting the ring 525 to the distal attachment
point. The microguidewire 360 passing through the side of the
filtering device as well as the proximal 535 and distal attachment
points 530 of the filtering device are shown.
[0086] FIG. 16 is a schematic diagram illustrating a significant
blockage or stenosis 585 in the right middle cerebral artery 105
that is causing mini-strokes and is refractory to medical therapy.
A guide catheter (6 French or larger) 580 has been advanced into
the right internal carotid artery 30 so that intracranial balloon
angioplasty and stenting can be performed.
[0087] FIG. 17 is a schematic diagram illustrating that through the
guide catheter in the right internal carotid artery, a
microcatheter 590 is being advanced in the right internal carotid
artery into the right middle cerebral artery over a microwire 600.
The microwire is carefully advanced across the blockage in the
right middle cerebral artery 585. The microcatheter is then
advanced over the microwire.
[0088] FIG. 18 is a schematic diagram illustrating that the
microcatheter 590 has been carefully advanced across the blockage
in the right middle cerebral artery 585 over a microwire. The
microwire has been removed once the microcatheter is distal to the
blockage 585 in the right middle cerebral artery. Prior to
exchanging the microcatheter for a balloon catheter, a distal
embolic protection device is decided to be advanced to the right
middle cerebral artery through the microcatheter.
[0089] FIG. 19 is a schematic diagram illustrating the introducer
sheath 305 with the non-expanded distal embolic protection device
310 comprising microguidewire 290 are being advanced through the
microcatheter 590. The hemostatic valve 295 at the proximal end of
the introducer sheath is released so that the microguidewire 290
can be advanced. Once the distal embolic protection device 310 has
entered the microcatheter 590 and guide catheter 580, the
introducer sheath 305 can be removed. The guide catheter 580 is
connected to a rotating hemostatic valve 595 to prevent
back-bleeding. The microcatheter 590 passes through the rotating
hemostatic valve 595 and then into the guide catheter 580.
[0090] FIG. 20 is a schematic diagram illustrating the distal
embolic protection device 350 in the non-expanded state in the
appropriate location distal to the blockage 585 in the right middle
cerebral artery. With the microguidewire 365 in position and fixed,
the microcatheter 590 is being withdrawn to deploy the filtering
device. The tip of the microguidewire 395 is shaped to avoid
perforating a small vessel. The distal stop 375 in the
microguidewire acts as the radio-opaque marker.
[0091] FIG. 21 is a schematic diagram illustrating the distal
embolic protection device fully deployed in the right middle
cerebral artery distal to the blockage 585. The radio-opaque distal
part of the microguidewire 365 along with the shapeable tip 395 are
noted. The radio-opaque stops of the microguidewire 340 and 375 are
noted. The filtering device with the plurality of struts 405 and
410 between the two attachment points 345 and 355 are noted. The
filter membrane 415 is noted. With the microguidewire fixed in
position, the microcatheter 590 is being exchanged for a balloon
catheter so that intracranial balloon angioplasty can be
performed.
[0092] FIG. 22 is a schematic diagram illustrating the filtering
device is in place distal to the blockage 585 in the right middle
cerebral artery. With the microguidewire in position, the
microcatheter is exchanged for a balloon catheter 605. The mobile
attachment points 345 and 355 of the filtering device allow for the
filtering device to be stationary even if there is minimal movement
of the microguidewire 335 during the microcatheter exchange. When
the balloon 610 is across the blockage 585 in the right middle
cerebral artery, intracranial balloon angioplasty is performed.
During intracranial balloon angioplasty, emboli or debris are
released 615 and are collected in the distal embolic protection
device by the filter 415.
[0093] FIG. 23 is a schematic diagram illustrating that after
intracranial angioplasty, the balloon 610 shown in FIG. 22 is
deflated and the balloon catheter 605 is exchanged for an
intracranial stent catheter 620 over the microguidewire. When the
stent is in position across the area of blockage 630 in the right
middle cerebral artery where balloon angioplasty was performed, the
stent is deployed. During intracranial stenting, small emboli or
debris are released 615 and are collected in the filter 415 of the
distal embolic protection device. After stenting is performed, the
distal embolic protection device can be retrieved using the stent
catheter 620 by advancing it over the microguidewire till the
radio-opaque markers in struts of the distal embolic protection
device suggest that the filter has closed so that the device can be
safely removed.
[0094] FIG. 24 is a schematic diagram illustrating a standard
microcatheter, which can be alternatively used to retrieve the
distal embolic protection device. In this case, the stent catheter
620 shown in FIG. 23 is exchanged for a standard catheter 590 over
the microguidewire 335. The standard microcatheter has a proximal
640 and distal end 645. Standard microcatheters that are
commercially available (such as Echelon.TM. microcatheter, ev3 Inc;
Excelsior.TM. microcatheter, Boston Scientific Corp; Prowler.TM.
microcatheter, Cordis Neurovascular etc) can be used and their
inner lumen diameter range from 0.017 to 0.021 inch (0.432 mm to
0.533 mm) and are usually 135 to 175 cm in length.
[0095] FIG. 25 is a schematic diagram illustrating the tip of the
standard microcatheter 645 being advanced over the microguidewire
such that the filtering device 350 closes to the collapsed
configuration to prevent spillage of the emboli or debris collected
during the procedure. The stent is noted to be in good position 625
across the angioplastied area 630.
[0096] FIG. 26 is a schematic diagram illustrating the filtering
device 350 in the closed non-expanded state being carefully
withdrawn into the guide catheter 580. The microcatheter tip 645 is
closely approximated to the struts of the filtering device to
prevent spillage of the contents of the distal embolic protection
device namely emboli or debris. The stent is noted to be in good
position 625 across the angioplastied area 630.
[0097] FIG. 27 is a schematic diagram illustrating another use for
this distal embolic protection device. This figure illustrates a
thrombus or blood clot 650 in the right middle cerebral artery and
is occluding this right middle cerebral artery and causing an acute
ischemic stroke. The patient presents after 3 hours from symptom
onset and is a candidate for immediate neurovascular interventional
therapy with intra-arterial thrombolytic infusion. A guide catheter
580 (6 French or greater) is advanced into the right internal
carotid artery.
[0098] FIG. 28 is a schematic diagram illustrating a standard
microcatheter 590 being advanced across the thrombus or blood clot
650 in the right middle cerebral artery over a microwire 600. Once
the microcatheter is across the thrombus or blood clot, the
microwire will be removed and a microcatheter angiogram may be
performed to identify if the cerebral blood vessels distal to the
thrombus or blood clot are patent.
[0099] FIG. 29 is a schematic diagram illustrating a distal embolic
protection device is advanced through the microcatheter 590 into a
position distal to the thrombus or blood clot 650 and then the
microcatheter is withdrawn to the proximal part of the right middle
cerebral artery to deploy the distal embolic protection device. The
radio-opaque stops 340 and 375 in the microguidewire, as well as,
the radio-opaque attachment points 455 and 460 of the distal
embolic protection device are well visualized. Also the distal
radio-opaque microguidewire segment 365 and the shapeable tip 395
are well visualized. Intra-arterial thrombolytic infusion is
initiated through the microcatheter with the microguidewire in
position 335. The thrombus or blood clot is broken down 655 into
smaller emboli or debris 660, which are collected in the filter
membrane 480 of the distal protection device. The struts 470 of the
distal embolic protection device are in the expanded position to
maintain the shape of the filter membrane.
[0100] FIG. 30 is a schematic diagram illustrating after
intra-arterial thrombolysis, the microcatheter 590 is advanced over
the microguidewire such that the filtering device 350 closes to the
collapsed configuration to prevent spillage of the emboli or debris
collected during the procedure. The filtering device 350 in the
closed non-expanded state is then carefully withdrawn into the
guide catheter 580. All through the process, the microcatheter tip
645 is closely approximated to the struts of the distal embolic
protection device to prevent spillage of the contents of the distal
embolic protection device namely emboli or debris.
[0101] While the invention is susceptible to various modifications,
and alternative forms, specific examples thereof have been shown in
the drawings and are herein described in detail. It should be
understood, however, that the invention is not to be limited to the
particular forms or methods disclosed, but to the contrary, the
invention is to cover all modifications, equivalents and
alternatives falling within the spirit and scope of the appended
claims.
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