U.S. patent application number 17/730625 was filed with the patent office on 2022-08-18 for filamentary devices for treatment of vascular defects.
The applicant listed for this patent is SEQUENT MEDICAL, INC.. Invention is credited to Joseph Emery, Todd Hewitt, Parker Milhous, William R. Patterson, Hussain S. Rangwala, Hung Tran, John Vu.
Application Number | 20220257258 17/730625 |
Document ID | / |
Family ID | 1000006308146 |
Filed Date | 2022-08-18 |
United States Patent
Application |
20220257258 |
Kind Code |
A1 |
Hewitt; Todd ; et
al. |
August 18, 2022 |
FILAMENTARY DEVICES FOR TREATMENT OF VASCULAR DEFECTS
Abstract
Devices and methods for treatment of a patient's vasculature are
described. Embodiments may include a permeable implant such as a
permeable shell or mesh having a radially constrained state
configured for delivery within a catheter lumen, an expanded state,
and a plurality of elongate filaments that are woven together. The
permeable implant may include a stiffer proximal portion that is
configured to sit at the neck of an aneurysm. The stiffer proximal
portion may include additional mesh layers on either the inside or
the outside of a first permeable shell. The distal portion of the
device may be softer and deformable.
Inventors: |
Hewitt; Todd; (Laguna
Niguel, CA) ; Milhous; Parker; (Santa Ana, CA)
; Emery; Joseph; (Riverside, CA) ; Tran; Hung;
(Midway City, CA) ; Vu; John; (Santa Ana, CA)
; Rangwala; Hussain S.; (Villa Park, CA) ;
Patterson; William R.; (Huntington Beach, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SEQUENT MEDICAL, INC. |
Aliso Viejo |
CA |
US |
|
|
Family ID: |
1000006308146 |
Appl. No.: |
17/730625 |
Filed: |
April 27, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16817032 |
Mar 12, 2020 |
11317921 |
|
|
17730625 |
|
|
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|
62819309 |
Mar 15, 2019 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 17/12177 20130101;
A61B 17/12172 20130101; A61B 2017/00526 20130101; A61B 17/12113
20130101 |
International
Class: |
A61B 17/12 20060101
A61B017/12 |
Claims
1. A device for treatment of a patient's cerebral aneurysm,
comprising: a first permeable shell including a radially
constrained elongated state configured for delivery within a
catheter lumen, an expanded state with a longitudinally shortened
configuration relative to the radially constrained state, and a
plurality of elongate filaments that are woven together to form a
mesh, the expanded state having a proximal portion, a distal
portion, and an interior cavity, wherein each of the plurality of
filaments has a proximal end and a distal end, and wherein the
proximal ends of each of the plurality of filaments are gathered by
a proximal hub and the distal ends of each of the plurality of
filaments are gathered by a distal hub; and a second permeable
shell including a radially constrained elongated state configured
for delivery within a catheter lumen, an expanded state with a
longitudinally shortened configuration relative to the radially
constrained state of the second permeable shell, and a plurality of
elongate filaments that are woven together to form a mesh, wherein
at least a portion of the second permeable shell is in contact with
the proximal portion of the first permeable shell, wherein each of
the plurality of filaments of the second permeable shell has a
proximal end and a distal end, wherein the proximal ends of each of
the plurality of filaments of the second permeable shell are
gathered in the proximal hub with the proximal ends of each of the
plurality of filaments of the first permeable shell, wherein the
distal ends of each of the plurality of filaments of the second
permeable shell are not bound together, and wherein a length of the
expanded state of the second permeable shell is smaller than a
length of the expanded state of the first permeable shell.
2. The device of claim 1, wherein the second permeable shell is
stiffer than the first permeable shell.
3. The device of claim 1, wherein an outer surface of the second
permeable shell is in contact with an inner surface of the first
permeable shell.
4. The device of claim 1, wherein the length of the expanded state
of the second permeable shell is between about 10% to about 40% of
the length of the expanded state of the first permeable shell.
5. The device of claim 1, wherein the second permeable shell is
attached to the first permeable shell by welding, adhesive, or
mechanical ties.
6. The device of claim 1, wherein a diameter of each of the
plurality of filaments of the second permeable shell is larger than
a diameter of each of the plurality of filaments of the first
permeable shell.
7. A device for treatment of a patient's cerebral aneurysm,
comprising: a first self-expanding mesh including a radially
constrained elongated state configured for delivery within a
catheter lumen, an expanded state with a longitudinally shortened
configuration relative to the radially constrained state, and a
plurality of elongate filaments that are woven together to form the
first self-expanding mesh, the expanded state having a proximal
portion, a distal portion, and an interior cavity, wherein each of
the plurality of filaments has a proximal end and a distal end, and
wherein the proximal ends of each of the plurality of filaments are
gathered by a proximal hub and the distal ends of each of the
plurality of filaments are gathered by a distal hub; and a second
self-expanding mesh including a radially constrained elongated
state configured for delivery within a catheter lumen, an expanded
state with a longitudinally shortened configuration relative to the
radially constrained state of the second self-expanding mesh, and a
plurality of elongate filaments that are woven together to form the
second self-expanding mesh, wherein at least a portion of the
second self-expanding mesh is in contact with the proximal portion
of the first self-expanding mesh, wherein each of the plurality of
filaments of the second self-expanding mesh has a proximal end and
a distal end, wherein the proximal ends of each of the plurality of
filaments of the second self-expanding mesh are gathered in the
proximal hub with the proximal ends of each of the plurality of
filaments of the first self-expanding mesh, wherein the distal ends
of each of the plurality of filaments of the second self-expanding
mesh are not bound together, and wherein a length of the expanded
state of the second self-expanding mesh is smaller than a length of
the expanded state of the first self-expanding mesh.
8. The device of claim 7, wherein the second self-expanding mesh is
stiffer than the first self-expanding mesh.
9. The device of claim 7, wherein an outer surface of the second
self-expanding mesh is in contact with an inner surface of the
first self-expanding mesh.
10. The device of claim 7, wherein the length of the expanded state
of the second self-expanding mesh is between about 10% to about 40%
of the length of the expanded state of the first self-expanding
mesh.
11. The device of claim 7, wherein the second self-expanding mesh
is attached to the first self-expanding mesh by welding, adhesive,
or mechanical ties.
12. The device of claim 7, wherein a diameter of each of the
plurality of filaments of the second self-expanding mesh is larger
than a diameter of each of the plurality of filaments of the first
self-expanding mesh.
13. A device for treatment of a patient's cerebral aneurysm,
comprising: a first permeable shell including a radially
constrained elongated state configured for delivery within a
catheter lumen, an expanded state with a longitudinally shortened
configuration relative to the radially constrained state, and a
plurality of elongate filaments that are woven together to form a
mesh, the expanded state having a proximal portion, a distal
portion, and an interior cavity, wherein each of the plurality of
filaments has a proximal end and a distal end, and wherein the
proximal ends of each of the plurality of filaments are gathered by
a proximal hub and the distal ends of each of the plurality of
filaments are gathered by a distal hub; and a second permeable
shell including a radially constrained elongated state configured
for delivery within a catheter lumen, an expanded state with a
longitudinally shortened configuration relative to the radially
constrained state, and a plurality of elongate filaments that are
woven together to form a mesh, wherein at least a portion of the
second permeable shell is in contact with the proximal portion of
the first permeable shell, wherein each of the plurality of
filaments has a proximal end and a distal end, wherein the second
permeable shell has an open distal end, wherein the distal ends of
each of the plurality of filaments of the second permeable shell
are not bound together, and wherein a length of the expanded state
of the second permeable shell is smaller than a length of the
expanded state of the first permeable shell.
14. The device of claim 13, wherein the second permeable shell is
stiffer than the first permeable shell.
15. The device of claim 13, wherein the second permeable shell is
attached to the first permeable shell by welding, adhesive, or
mechanical ties.
16. The device of claim 13, wherein the distal ends of each of the
plurality of filaments of the second permeable shell are not
attached to the first permeable shell.
17. The device of claim 13, wherein the proximal ends of each of
the plurality of filaments of the second permeable shell are
gathered in the proximal hub with the proximal ends of each of the
plurality of filaments of the first permeable shell.
18. The device of claim 13, wherein a diameter of each of the
plurality of filaments of the second permeable shell is larger than
a diameter of each of the plurality of filaments of the first
permeable shell.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 16/817,032, filed Mar. 12, 2020, which claims the benefit of
priority under 35 U.S.C. .sctn. 119(e) from U.S. Provisional
Application Ser. No. 62/819,309, filed Mar. 15, 2019, both of which
are hereby expressly incorporated by reference in their entireties
for all purposes.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
FIELD OF THE INVENTION
[0003] Embodiments of devices and methods herein are directed to
blocking a flow of fluid through a tubular vessel or into a small
interior chamber of a saccular cavity or vascular defect within a
mammalian body. More specifically, embodiments herein are directed
to devices and methods for treatment of a vascular defect of a
patient including some embodiments directed specifically to the
treatment of cerebral aneurysms of patients.
BACKGROUND
[0004] The mammalian circulatory system is comprised of a heart,
which acts as a pump, and a system of blood vessels which transport
the blood to various points in the body. Due to the force exerted
by the flowing blood on the blood vessel the blood vessels may
develop a variety of vascular defects. One common vascular defect
known as an aneurysm results from the abnormal widening of the
blood vessel. Typically, vascular aneurysms are formed as a result
of the weakening of the wall of a blood vessel and subsequent
ballooning and expansion of the vessel wall. If, for example, an
aneurysm is present within an artery of the brain, and the aneurysm
should burst with resulting cranial hemorrhaging, death could
occur.
[0005] Surgical techniques for the treatment of cerebral aneurysms
typically involve a craniotomy requiring creation of an opening in
the skull of the patient through which the surgeon can insert
instruments to operate directly on the patient's brain. For some
surgical approaches, the brain must be retracted to expose the
parent blood vessel from which the aneurysm arises. Once access to
the aneurysm is gained, the surgeon places a clip across the neck
of the aneurysm thereby preventing arterial blood from entering the
aneurysm. Upon correct placement of the clip the aneurysm will be
obliterated in a matter of minutes. Surgical techniques may be
effective treatment for many aneurysms. Unfortunately, surgical
techniques for treating these types of conditions include major
invasive surgical procedures which often require extended periods
of time under anesthesia involving high risk to the patient. Such
procedures thus require that the patient be in generally good
physical condition in order to be a candidate for such
procedures.
[0006] Various alternative and less invasive procedures have been
used to treat cerebral aneurysms without resorting to major
surgery. One approach to treating aneurysms without the need for
invasive surgery involves the placement of sleeves or stents into
the vessel and across the region where the aneurysm occurs. Such
devices maintain blood flow through the vessel while reducing blood
pressure applied to the interior of the aneurysm. Certain types of
stents are expanded to the proper size by inflating a balloon
catheter, referred to as balloon expandable stents, while other
stents are designed to elastically expand in a self-expanding
manner. Some stents are covered typically with a sleeve of
polymeric material called a graft to form a stent-graft. Stents and
stent-grafts are generally delivered to a preselected position
adjacent a vascular defect through a delivery catheter. In the
treatment of cerebral aneurysms, covered stents or stent-grafts
have seen very limited use due to the likelihood of inadvertent
occlusion of small perforator vessels that may be near the vascular
defect being treated.
[0007] In addition, current uncovered stents are generally not
sufficient as a stand-alone treatment. In order for stents to fit
through the microcatheters used in small cerebral blood vessels,
their density is usually reduced such that when expanded there is
only a small amount of stent structure bridging the aneurysm neck.
Thus, they do not block enough flow to cause clotting of the blood
in the aneurysm and are thus generally used in combination with
vaso-occlusive devices, such as the coils discussed above, to
achieve aneurysm occlusion.
[0008] Some procedures involve the delivery of embolic or filling
materials into an aneurysm. The delivery of such vaso-occlusion
devices or materials may be used to promote hemostasis or fill an
aneurysm cavity entirely. Vaso-occlusion devices may be placed
within the vasculature of the human body, typically via a catheter,
either to block the flow of blood through a vessel with an aneurysm
through the formation of an embolus or to form such an embolus
within an aneurysm stemming from the vessel. A variety of
implantable, coil-type vaso-occlusion devices are known. The coils
of such devices may themselves be formed into a secondary coil
shape, or any of a variety of more complex secondary shapes.
Vaso-occlusive coils are commonly used to treat cerebral aneurysms
but suffer from several limitations including poor packing density,
compaction due to hydrodynamic pressure from blood flow, poor
stability in wide-necked aneurysms, and complexity and difficulty
in the deployment thereof as most aneurysm treatments with this
approach require the deployment of multiple coils. Coiling is less
effective at treating certain physiological conditions, such as
wide neck cavities (e.g. wide neck aneurysms) because there is a
greater risk of the coils migrating out of the treatment site.
[0009] A number of aneurysm neck bridging devices with defect
spanning portions or regions have been attempted, however, none of
these devices have had a significant measure of clinical success or
usage. A major limitation in their adoption and clinical usefulness
is the inability to position the defect spanning portion to assure
coverage of the neck. Existing stent delivery systems that are
neurovascular compatible (i.e. deliverable through a microcatheter
and highly flexible) do not have the necessary rotational
positioning capability. Another limitation of many aneurysm
bridging devices described in the prior art is the poor
flexibility. Cerebral blood vessels are tortuous, and a high degree
of flexibility is required for effective delivery to most aneurysm
locations in the brain.
[0010] What has been needed are devices and methods for delivery
and use in small and tortuous blood vessels that can substantially
block the flow of blood into an aneurysm, such as a cerebral
aneurysm, with a decreased risk of inadvertent aneurysm rupture or
blood vessel wall damage. In addition, what has been needed are
methods and devices suitable for blocking blood flow in cerebral
aneurysms over an extended period of time without a significant
risk of deformation, compaction or dislocation.
[0011] Intrasaccular occlusive devices are part of a newer type of
occlusion device used to treat various intravascular conditions
including aneurysms. They are often more effective at treating
these wide neck conditions, or larger treatment areas. The
intrasaccular devices comprise a structure which sits within the
aneurysm and provides an occlusive effect at the neck of the
aneurysm to help limit blood flow into the aneurysm. The rest of
the device comprises a relatively conformable structure that sits
within the aneurysm helping to occlude all or a portion of the
aneurysm. Intrasaccular devices typically conform to the shape of
the treatment site. These devices also occlude the cross section of
the neck of the treatment site/aneurysm, thereby promoting clotting
and causing thrombosis and closing of the aneurysm over time.
[0012] These intrasaccular devices are difficult to design for
various reasons. For neurovascular aneurysms, these intrasaccular
devices are particularly small and any projecting structures from
the intrasaccular device can prod into the vessel or tissue,
causing additional complications. In larger aneurysms, there is a
risk of compaction where the intrasaccular device can migrate into
the aneurysm and leave the neck region. There is a need for an
intrasaccular device that addresses these issues.
SUMMARY
[0013] An intrasaccular occlusion device is described that is used
to treat a variety of conditions, including aneurysms and
neurovascular aneurysms. Generally, effective intrasaccular devices
should provide good flow disruption at the neck of the aneurysm to
reduce blood flow into the aneurysm, and should also resist
migration or displacement from the treatment site in order to
properly treat the aneurysm. One way to increase flow disruption at
the neck region is to increase surface coverage of the material at
the neck of the aneurysm. One way to prevent the issue of potential
migration is to increase stiffness at the proximal part of the
intrasaccular device. The following embodiments utilize various
techniques to augment flow disruption and resist migration.
[0014] In one embodiment, a multiple layer occlusion device is
described. A first layer comprises an entire length of the
occlusion device and a second layer comprises only a proximal
section of the occlusion device. The second layer helps to augment
the flow-disruption effect along the proximal section of the device
and provides enhanced proximal anchoring to resist migration.
[0015] In another embodiment, a multiple layer occlusion device is
described. A first layer comprises an entire length of the
occlusion device and a second layer comprises only a proximal
section of the occlusion device so as to augment the
flow-disruption effect along the proximal section of the device. In
one embodiment, the second layer is free-floating or loosely
attached to the first layer of the device, such that the second
layer has a variable height so as to customize the portion of the
occlusion device having the augmented flow-disruptive and/or
occlusive effect.
[0016] In another embodiment, a multiple layer occlusion device is
described. A first layer comprises an entire length of the
occlusion device and a second layer comprises only a proximal
section of the occlusion device so as to augment the
flow-disruption effect along the proximal section of the device. In
one embodiment, the second layer is a secondary mesh.
[0017] In one embodiment, a multiple layer occlusion device
utilizes a relatively soft first layer which comprises an entire
length of the device, and a relatively stiff second layer which
comprises only a proximal section of the device. The second layer
provides augmented rigidity and flow disruption to a proximal
portion of the device, while the relatively soft first layer allows
the device to conform to a geometry of the treatment site.
[0018] In another embodiment, a device for treatment of a patient's
cerebral aneurysm is described. The device includes a first
permeable shell including a radially constrained elongated state
configured for delivery within a catheter lumen, an expanded state
with a longitudinally shortened configuration relative to the
radially constrained state, and a plurality of elongate filaments
that are woven together to form a mesh, the expanded state having a
proximal portion, a distal portion, and an interior cavity, wherein
each of the plurality of filaments has a proximal end and a distal
end, and wherein the proximal ends of each of the plurality of
filaments are gathered by a proximal hub or marker band and the
distal ends of each of the plurality of filaments are gathered by a
distal hub or marker band. The device also includes a second
permeable shell including a radially constrained elongated state
configured for delivery within a catheter lumen, an expanded state
with a longitudinally shortened configuration relative to the
radially constrained state, and a plurality of elongate filaments
that are woven together to form a mesh, wherein at least a portion
of the second permeable shell is in contact with the proximal
portion of the first permeable shell, wherein each of the plurality
of filaments has a proximal end and a distal end. The proximal ends
of each of the plurality of filaments of the second permeable shell
are gathered in the proximal hub or marker band with the proximal
ends of each of the plurality of filaments of the first permeable
shell, and a length of the expanded state of the second permeable
shell is smaller than a length of the expanded state of the first
permeable shell.
[0019] In another embodiment, a method for treating a cerebral
aneurysm having an interior cavity and a neck is described. The
method includes the step of advancing an implant in a microcatheter
to a region of interest in a cerebral artery, wherein the implant
comprises a first permeable shell including a radially constrained
elongated state configured for delivery within a lumen of the
microcatheter, an expanded state with a longitudinally shortened
configuration relative to the radially constrained state, and a
plurality of elongate filaments that are woven together to form a
mesh, the expanded state having a proximal portion, a distal
portion, and an interior cavity, wherein each of the plurality of
filaments has a proximal end and a distal end, and wherein the
proximal ends of each of the plurality of filaments are gathered by
a proximal hub or marker band and the distal ends of each of the
plurality of filaments are gathered by a distal hub or marker band;
and a second permeable shell including a radially constrained
elongated state configured for delivery within the lumen of the
microcatheter, an expanded state with a longitudinally shortened
configuration relative to the radially constrained state, and a
plurality of elongate filaments that are woven together to form a
mesh, wherein at least a portion of the second permeable shell is
in contact with the proximal portion of the first permeable shell,
wherein each of the plurality of filaments has a proximal end and a
distal end. The proximal ends of each of the plurality of filaments
of the second permeable shell are gathered in the proximal hub or
marker band with the proximal ends of each of the plurality of
filaments of the first permeable shell, and a length of the
expanded state of the second permeable shell is smaller than a
length of the expanded state of the first permeable shell. The
implant is then deployed within the cerebral aneurysm, wherein the
first and second permeable shells each expand to their expanded
states in the interior cavity of the aneurysm. The microcatheter is
then withdrawn from the region of interest after deploying the
implant.
[0020] In another embodiment, a device for treatment of a patient's
cerebral aneurysm is described. The device includes a first
self-expanding mesh including a radially constrained elongated
state configured for delivery within a catheter lumen, an expanded
state with a longitudinally shortened configuration relative to the
radially constrained state, and a plurality of elongate filaments
that are woven together to form the mesh, the expanded state having
a proximal portion, a distal portion, and an interior cavity,
wherein each of the plurality of filaments has a proximal end and a
distal end, and wherein the proximal ends of each of the plurality
of filaments are gathered by a proximal hub or marker band and the
distal ends of each of the plurality of filaments are gathered by a
distal hub or marker band; and a second self-expanding mesh
including a radially constrained elongated state configured for
delivery within a catheter lumen, an expanded state with a
longitudinally shortened configuration relative to the radially
constrained state, and a plurality of elongate filaments that are
woven together to form the mesh, wherein at least a portion of the
second self-expanding mesh is in contact with the proximal portion
of the first self-expanding mesh, wherein each of the plurality of
filaments has a proximal end and a distal end. The proximal ends of
each of the plurality of filaments of the second self-expanding
mesh are gathered in the proximal hub or marker band with the
proximal ends of each of the plurality of filaments of the first
self-expanding mesh, and a length of the expanded state of the
second self-expanding mesh is smaller than a length of the expanded
state of the first self-expanding mesh.
[0021] In another embodiment, a method for treating a cerebral
aneurysm having an interior cavity and a neck is described. The
method includes the step of advancing an implant in a microcatheter
to a region of interest in a cerebral artery, wherein the implant
comprises a first self-expanding mesh including a radially
constrained elongated state configured for delivery within a
catheter lumen, an expanded state with a longitudinally shortened
configuration relative to the radially constrained state, and a
plurality of elongate filaments that are woven together to form the
mesh, the expanded state having a proximal portion, a distal
portion, and an interior cavity, wherein each of the plurality of
filaments has a proximal end and a distal end, and wherein the
proximal ends of each of the plurality of filaments are gathered by
a proximal hub or marker band and the distal ends of each of the
plurality of filaments are gathered by a distal hub or marker band;
and a second self-expanding mesh including a radially constrained
elongated state configured for delivery within a catheter lumen, an
expanded state with a longitudinally shortened configuration
relative to the radially constrained state, and a plurality of
elongate filaments that are woven together to form the mesh,
wherein at least a portion of the second self-expanding mesh is in
contact with the proximal portion of the first self-expanding mesh,
wherein each of the plurality of filaments has a proximal end and a
distal end. The proximal ends of each of the plurality of filaments
of the second self-expanding mesh may be gathered in the proximal
hub or marker band with the proximal ends of each of the plurality
of filaments of the first self-expanding mesh, and a length of the
expanded state of the second self-expanding mesh may be smaller
than a length of the expanded state of the first self-expanding
mesh. The implant is then deployed within the cerebral aneurysm,
wherein the first and second self-expanding permeable meshes expand
to each of their expanded states in the interior cavity of the
aneurysm. The microcatheter is then withdrawn from the region of
interest after deploying the implant.
[0022] In another embodiment, a device for treatment of a patient's
cerebral aneurysm is described. The device includes a first
permeable shell including a radially constrained elongated state
configured for delivery within a catheter lumen, an expanded state
with a longitudinally shortened configuration relative to the
radially constrained state, and a plurality of elongate filaments
that are woven together to form a mesh, the expanded state having a
proximal portion, a distal portion, and an interior cavity, wherein
each of the plurality of filaments has a proximal end and a distal
end, and wherein the proximal ends of each of the plurality of
filaments are gathered by a proximal hub or marker band and the
distal ends of each of the plurality of filaments are gathered by a
distal hub or marker band; and a second permeable shell including a
radially constrained elongated state configured for delivery within
a catheter lumen, an expanded state with a longitudinally shortened
configuration relative to the radially constrained state, and a
plurality of elongate filaments that are woven together to form a
mesh, wherein at least a portion of the second permeable shell is
in contact with the proximal portion of the first permeable shell,
wherein each of the plurality of filaments has a proximal end and a
distal end. The second permeable shell may have an open distal end,
and a length of the expanded state of the second permeable shell
may be smaller than a length of the expanded state of the first
permeable shell.
[0023] In another embodiment, a method for treating a cerebral
aneurysm having an interior cavity and a neck is described. The
method includes the step of advancing an implant in a microcatheter
to a region of interest in a cerebral artery, wherein the implant
comprises a first permeable shell including a radially constrained
elongated state configured for delivery within a catheter lumen, an
expanded state with a longitudinally shortened configuration
relative to the radially constrained state, and a plurality of
elongate filaments that are woven together to form a mesh, the
expanded state having a proximal portion, a distal portion, and an
interior cavity, wherein each of the plurality of filaments has a
proximal end and a distal end, and wherein the proximal ends of
each of the plurality of filaments are gathered by a proximal hub
or marker band and the distal ends of each of the plurality of
filaments are gathered by a distal hub or marker band; and a second
permeable shell including a radially constrained elongated state
configured for delivery within a catheter lumen, an expanded state
with a longitudinally shortened configuration relative to the
radially constrained state, and a plurality of elongate filaments
that are woven together to form a mesh, wherein at least a portion
of the second permeable shell is in contact with the proximal
portion of the first permeable shell, wherein each of the plurality
of filaments has a proximal end and a distal end. The second
permeable shell may have an open distal end, and a length of the
expanded state of the second permeable shell may be smaller than a
length of the expanded state of the first permeable shell. The
implant is then deployed within the cerebral aneurysm, wherein the
first and second permeable shells each expand to their expanded
states in the interior cavity of the aneurysm. The microcatheter is
then withdrawn from the region of interest after deploying the
implant.
[0024] In any of the embodiments, the second permeable shell may be
stiffer than the first permeable shell. The second permeable shell
may have a radial stiffness or a normalized radial stiffness of
between about 0.005 N/mm and about 0.025 N/mm, alternatively
between about 0.010 N/mm and about 0.020 N/mm. The first permeable
shell may have a normalized radial stiffness of between about 0.001
N/mm and about 0.025 N/mm, alternatively between about 0.001 N/mm
and about 0.010 N/mm.
[0025] In any of the embodiments, the first permeable shell may
have a soft distal portion that is deformable such that upon
deployment in an aneurysm, the soft distal portion can buckle,
deform, or bend. Thus, an implant having an expanded length when
unconstrained and deployed outside of an aneurysm that is larger
than a height of the aneurysm can still be deployed into and fit in
the cavity of the aneurysm because the soft distal portion can
deform, thereby reducing the effective expanded length of the
device in the aneurysm.
[0026] In any of the embodiments, the second permeable shell or
self-expanding mesh may be on the inside or the outside of the
proximal section of the first permeable shell. Thus, an outer
surface of the second permeable shell may be in contact with an
inner surface of the first permeable shell. Alternatively, an outer
surface of the first permeable shell may be in contact with an
inner surface of the second permeable shell. The first permeable
shell may be in an interior cavity defined by the second permeable
shell. Alternatively, the second permeable shell may be in an
interior cavity defined by the first permeable shell. The second
permeable shell may have an open distal end. The proximal ends of
each of the plurality of filaments of the second permeable shell
are gathered in the proximal hub or marker band with the proximal
ends of each of the plurality of filaments of the first permeable
shell. The distal ends of each of the plurality of filaments of the
second permeable shell may not attached to the first permeable
shell. The distal ends of each of the plurality of filaments of the
second permeable shell may also not be gathered or bound
together.
[0027] In any of the embodiments, the expanded length of the second
permeable shell or self-expanding mesh may less than the expanded
length of the first permeable shell. The length of the expanded
state of the second permeable shell may be about between about 10%
to about 60%, alternatively between about 10% to about 50%,
alternatively between about 10% to about 40% of the length of the
expanded state of the first permeable shell.
[0028] In any of the embodiments, the second permeable shell or
self-expanding mesh is made from a plurality of filaments each
having first and second ends. The first ends of the second
permeable shell may be bound by a hub or marker band. The first
ends may be bound by the same hub or marker band that is binding
the first ends (proximal ends) of the filaments of the first
permeable shell, or they may be bound by a different hub or marker
band. The second ends (distal ends) of the filaments may not be
bound by a hub or marker band or otherwise gathered together, such
that a second or distal end of the second permeable shell has an
open configuration. The second ends of the filaments of the second
permeable shell, i.e., the distal end or distal portion of the
second permeable shell, may not be attached to the first permeable
shell. In an alternative embodiment, the distal end or distal
portion of the second permeable shell may be attached to the first
permeable shell by, e.g., welding, adhesive, or mechanical ties
along a distal section of the second shell 222. A diameter of each
of the plurality of filaments of the second permeable shell may be
larger than a diameter of each of the plurality of filaments of the
first permeable shell.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is an elevation view of an embodiment of a device for
treatment of a patient's vasculature and a plurality of arrows
indicating inward radial force.
[0030] FIG. 2 is an elevation view of a beam supported by two
simple supports and a plurality of arrows indicating force against
the beam.
[0031] FIG. 3 is a bottom perspective view of an embodiment of a
device for treatment of a patient's vasculature.
[0032] FIG. 4 is an elevation view of the device for treatment of a
patient's vasculature of FIG. 3.
[0033] FIG. 5 is a transverse cross sectional view of the device of
FIG. 4 taken along lines 5-5 in FIG. 4.
[0034] FIG. 6 shows the device of FIG. 4 in longitudinal section
taken along lines 6-6 in FIG. 4.
[0035] FIG. 7 is an enlarged view of the woven filament structure
taken from the encircled portion 7 shown in FIG. 5.
[0036] FIG. 8 is an enlarged view of the woven filament structure
taken from the encircled portion 8 shown in FIG. 6.
[0037] FIG. 9 is a proximal end view of the device of FIG. 3.
[0038] FIG. 10 is a transverse sectional view of a proximal hub
portion of the device in FIG. 6 indicated by lines 10-10 in FIG.
6.
[0039] FIG. 11 is an elevation view in partial section of a distal
end of a delivery catheter with the device for treatment of a
patient's vasculature of FIG. 3 disposed therein in a collapsed
constrained state.
[0040] FIG. 12 illustrates an embodiment of a filament
configuration for a device for treatment of a patient's
vasculature.
[0041] FIG. 13 illustrates the components of a multi-layer device
for treatment in a patient's vasculature.
[0042] FIG. 14 illustrates a device for treatment in a patient's
vasculature that has multiple layers in a proximal area of the
device.
[0043] FIG. 15 illustrates an alternative device for treatment in a
patient's vasculature that has multiple layers in a proximal area
of the device.
[0044] FIG. 16 illustrates a multi-layer device deployed within an
aneurysm.
[0045] FIG. 17 is a schematic view of a patient being accessed by
an introducer sheath, a microcatheter and a device for treatment of
a patient's vasculature releasably secured to a distal end of a
delivery device or actuator.
[0046] FIG. 18 is a sectional view of a terminal aneurysm.
[0047] FIG. 19 is a sectional view of an aneurysm.
[0048] FIG. 20 is a schematic view in section of an aneurysm
showing perpendicular arrows which indicate interior nominal
longitudinal and transverse dimensions of the aneurysm.
[0049] FIG. 21 is a schematic view in section of the aneurysm of
FIG. 20 with a dashed outline of a device for treatment of a
patient's vasculature in a relaxed unconstrained state that extends
transversely outside of the walls of the aneurysm.
[0050] FIG. 22 is a schematic view in section of an outline of a
device represented by the dashed line in FIG. 21 in a deployed and
partially constrained state within the aneurysm.
[0051] FIGS. 23-26 show a deployment sequence of a device for
treatment of a patient's vasculature.
[0052] FIG. 27 is an elevation view in partial section of an
embodiment of a device for treatment of a patient's vasculature
deployed within an aneurysm at a tilted angle.
[0053] FIG. 28 is an elevation view in partial section of an
embodiment of a device for treatment of a patient's vasculature
deployed within an irregularly shaped aneurysm.
[0054] FIG. 29 shows an elevation view in section of a device for
treatment of a patient's vasculature deployed within a vascular
defect aneurysm.
DETAILED DESCRIPTION
[0055] Discussed herein are devices and methods for the treatment
of vascular defects that are suitable for minimally invasive
deployment within a patient's vasculature, and particularly, within
the cerebral vasculature of a patient. For such embodiments to be
safely and effectively delivered to a desired treatment site and
effectively deployed, some device embodiments may be configured for
collapse to a low profile constrained state with a transverse
dimension suitable for delivery through an inner lumen of a
microcatheter and deployment from a distal end thereof. Embodiments
of these devices may also maintain a clinically effective
configuration with sufficient mechanical integrity once deployed so
as to withstand dynamic forces within a patient's vasculature over
time that may otherwise result in compaction of a deployed device.
It may also be desirable for some device embodiments to acutely
occlude a vascular defect of a patient during the course of a
procedure in order to provide more immediate feedback regarding
success of the treatment to a treating physician.
[0056] Intrasaccular occlusive devices that include a permeable
shell formed from a woven or braided mesh have been described in US
2017/0095254, US 2016/0249934, US 2016/0367260, US 2016/0249937,
and US 2018/0000489, all of which are hereby expressly incorporated
by reference in their entirety for all purposes.
[0057] Some embodiments are particularly useful for the treatment
of cerebral aneurysms by reconstructing a vascular wall so as to
wholly or partially isolate a vascular defect from a patient's
blood flow. Some embodiments may be configured to be deployed
within a vascular defect to facilitate reconstruction, bridging of
a vessel wall or both in order to treat the vascular defect. For
some of these embodiments, the permeable shell of the device may be
configured to anchor or fix the permeable shell in a clinically
beneficial position. For some embodiments, the device may be
disposed in whole or in part within the vascular defect in order to
anchor or fix the device with respect to the vascular structure or
defect. The permeable shell may be configured to span an opening,
neck or other portion of a vascular defect in order to isolate the
vascular defect, or a portion thereof, from the patient's nominal
vascular system in order allow the defect to heal or to otherwise
minimize the risk of the defect to the patient's health.
[0058] For some or all of the embodiments of devices for treatment
of a patient's vasculature discussed herein, the permeable shell
may be configured to allow some initial perfusion of blood through
the permeable shell. The porosity of the permeable shell may be
configured to sufficiently isolate the vascular defect so as to
promote healing and isolation of the defect, but allow sufficient
initial flow through the permeable shell so as to reduce or
otherwise minimize the mechanical force exerted on the membrane the
dynamic flow of blood or other fluids within the vasculature
against the device. For some embodiments of devices for treatment
of a patient's vasculature, only a portion of the permeable shell
that spans the opening or neck of the vascular defect, sometimes
referred to as a defect spanning portion, need be permeable and/or
conducive to thrombus formation in a patient's bloodstream. For
such embodiments, that portion of the device that does not span an
opening or neck of the vascular defect may be substantially
non-permeable or completely permeable with a pore or opening
configuration that is too large to effectively promote thrombus
formation.
[0059] In general, it may be desirable in some cases to use a
hollow, thin walled device with a permeable shell of resilient
material that may be constrained to a low profile for delivery
within a patient. Such a device may also be configured to expand
radially outward upon removal of the constraint such that the shell
of the device assumes a larger volume and fills or otherwise
occludes a vascular defect within which it is deployed. The outward
radial expansion of the shell may serve to engage some or all of an
inner surface of the vascular defect whereby mechanical friction
between an outer surface of the permeable shell of the device and
the inside surface of the vascular defect effectively anchors the
device within the vascular defect. Some embodiments of such a
device may also be partially or wholly mechanically captured within
a cavity of a vascular defect, particularly where the defect has a
narrow neck portion with a larger interior volume. In order to
achieve a low profile and volume for delivery and be capable of a
high ratio of expansion by volume, some device embodiments include
a matrix of woven or braided filaments that are coupled together by
the interwoven structure so as to form a self-expanding permeable
shell having a pore or opening pattern between couplings or
intersections of the filaments that is substantially regularly
spaced and stable, while still allowing for conformity and
volumetric constraint.
[0060] As used herein, the terms woven and braided are used
interchangeably to mean any form of interlacing of filaments to
form a mesh structure. In the textile and other industries, these
terms may have different or more specific meanings depending on the
product or application such as whether an article is made in a
sheet or cylindrical form. For purposes of the present disclosure,
these terms are used interchangeably.
[0061] For some embodiments, three factors may be critical for a
woven or braided wire occlusion device for treatment of a patient's
vasculature that can achieve a desired clinical outcome in the
endovascular treatment of cerebral aneurysms. We have found that
for effective use in some applications, it may be desirable for the
implant device to have sufficient radial stiffness for stability,
limited pore size for near-complete acute (intra-procedural)
occlusion and a collapsed profile which is small enough to allow
insertion through an inner lumen of a microcatheter. A device with
a radial stiffness below a certain threshold may be unstable and
may be at higher risk of embolization in some cases. Larger pores
between filament intersections in a braided or woven structure may
not generate thrombus and occlude a vascular defect in an acute
setting and thus may not give a treating physician or health
professional such clinical feedback that the flow disruption will
lead to a complete and lasting occlusion of the vascular defect
being treated. Delivery of a device for treatment of a patient's
vasculature through a standard microcatheter may be highly
desirable to allow access through the tortuous cerebral vasculature
in the manner that a treating physician is accustomed. A detailed
discussion of radial stiffness, pore size, and the necessary
collapsed profile can be found in US 2017/0095254, which was
previously expressly incorporated by reference in its entirety.
[0062] As has been discussed, some embodiments of devices for
treatment of a patient's vasculature call for sizing the device
which approximates (or with some over-sizing) the vascular site
dimensions to fill the vascular site. One might assume that scaling
of a device to larger dimensions and using larger filaments would
suffice for such larger embodiments of a device. However, for the
treatment of brain aneurysms, the diameter or profile of the
radially collapsed device is limited by the catheter sizes that can
be effectively navigated within the small, tortuous vessels of the
brain. Further, as a device is made larger with a given or fixed
number of resilient filaments having a given size or thickness, the
pores or openings between junctions of the filaments are
correspondingly larger. In addition, for a given filament size the
flexural modulus or stiffness of the filaments and thus the
structure decrease with increasing device dimension. Flexural
modulus may be defined as the ratio of stress to strain. Thus, a
device may be considered to have a high flexural modulus or be
stiff if the strain (deflection) is low under a given force. A
stiff device may also be said to have low compliance.
[0063] To properly configure larger size devices for treatment of a
patient's vasculature, it may be useful to model the force on a
device when the device is deployed into a vascular site or defect,
such as a blood vessel or aneurysm, that has a diameter or
transverse dimension that is smaller than a nominal diameter or
transverse dimension of the device in a relaxed unconstrained
state. As discussed, it may be advisable to "over-size" the device
in some cases so that there is a residual force between an outside
surface of the device and an inside surface of the vascular wall.
The inward radial force on a device 10 that results from
over-sizing is illustrated schematically in FIG. 1 with the arrows
12 in the figure representing the inward radial force. As shown in
FIG. 2, these compressive forces on the filaments 14 of the device
in FIG. 1 can be modeled as a simply supported beam 16 with a
distributed load or force as show by the arrows 18 in the figure.
It can be seen from the equation below for the deflection of a beam
with two simple supports 20 and a distributed load that the
deflection is a function of the length, L to the 4.sup.th
power:
Deflection of Beam=5FL.sup.4/384 El [0064] where F=force, [0065]
L=length of beam, [0066] E=Young's Modulus, and [0067] l=moment of
inertia.
[0068] Thus, as the size of the device increases and L increases,
the compliance increases substantially. Accordingly, an outward
radial force exerted by an outside surface of the filaments 14 of
the device 10 against a constraining force when inserted into a
vascular site such as blood vessel or aneurysm is lower for a given
amount of device compression or over-sizing. This force may be
important in some applications to assure device stability and to
reduce the risk of migration of the device and potential distal
embolization.
[0069] In some embodiments, a combination of small and large
filament sizes may be utilized to make a device with a desired
radial compliance and yet have a collapsed profile which is
configured to fit through an inner lumen of commonly used
microcatheters. A device fabricated with even a small number of
relatively large filaments 14 can provide reduced radial compliance
(or increased stiffness) compared to a device made with all small
filaments. Even a relatively small number of larger filaments may
provide a substantial increase in bending stiffness due to change
in the moment of Inertia that results from an increase in diameter
without increasing the total cross sectional area of the filaments.
The moment of inertia (I) of a round wire or filament may be
defined by the equation:
I=.pi.d.sup.4/64 [0070] where d is the diameter of the wire or
filament.
[0071] Since the moment of inertia is a function of filament
diameter to the fourth power, a small change in the diameter
greatly increases the moment of inertia. Thus, small changes in
filament size can have substantial impact on the deflection at a
given load and thus the compliance of the device.
[0072] Thus, the stiffness can be increased by a significant amount
without a large increase in the cross sectional area of a collapsed
profile of the device 10. This may be particularly important as
device embodiments are made larger to treat large aneurysms. While
large cerebral aneurysms may be relatively rare, they present an
important therapeutic challenge as some embolic devices currently
available to physicians have relatively poor results compared to
smaller aneurysms.
[0073] As such, some embodiments of devices for treatment of a
patient's vasculature may be formed using a combination of
filaments 14 with a number of different diameters such as 2, 3, 4,
5 or more different diameters or transverse dimensions. In device
embodiments where filaments with two different diameters are used,
some larger filament embodiments may have a transverse dimension of
about 0.001 inches to about 0.004 inches and some small filament
embodiments may have a transverse dimension or diameter of about
0.0004 inches and about 0.0015 inches, more specifically, about
0.0004 inches to about 0.001 inches. The ratio of the number of
large filaments to the number of small filaments may be between
about 2 and 12 and may also be between about 4 and 8. In some
embodiments, the difference in diameter or transverse dimension
between the larger and smaller filaments may be less than about
0.004 inches, more specifically, less than about 0.0035 inches, and
even more specifically, less than about 0.002 inches.
[0074] As discussed above, device embodiments 10 for treatment of a
patient's vasculature may include a plurality of wires, fibers,
threads, tubes or other filamentary elements that form a structure
that serves as a permeable shell. For some embodiments, a globular
shape may be formed from such filaments by connecting or securing
the ends of a tubular braided structure. For such embodiments, the
density of a braided or woven structure may inherently increase at
or near the ends where the wires or filaments 14 are brought
together and decrease at or near a middle portion 30 disposed
between a proximal end 32 and distal end 34 of the permeable shell
40. For some embodiments, an end or any other suitable portion of a
permeable shell 40 may be positioned in an opening or neck of a
vascular defect such as an aneurysm for treatment. As such, a
braided or woven filamentary device with a permeable shell may not
require the addition of a separate defect spanning structure having
properties different from that of a nominal portion of the
permeable shell to achieve hemostasis and occlusion of the vascular
defect. Such a filamentary device may be fabricated by braiding,
weaving or other suitable filament fabrication techniques. Such
device embodiments may be shape set into a variety of
three-dimensional shapes such as discussed herein.
[0075] Referring to FIGS. 3-10, an embodiment of a device for
treatment of a patient's vasculature 10 is shown. The device 10
includes a self-expanding resilient permeable shell 40 having a
proximal end 32, a distal end 34, a longitudinal axis 46 and
further comprising a plurality of elongate resilient filaments 14
including large filaments 48 and small filaments 50 of at least two
different transverse dimensions as shown in more detail in FIGS. 5,
7, and 18. The filaments 14 have a woven structure and are secured
relative to each other at proximal ends 60 and distal ends 62
thereof. The permeable shell 40 of the device has a radially
constrained elongated state configured for delivery within a
microcatheter 61, as shown in FIG. 11, with the thin woven
filaments 14 extending longitudinally from the proximal end 42 to
the distal end 44 radially adjacent each other along a length of
the filaments.
[0076] As shown in FIGS. 3-6, the permeable shell 40 also has an
expanded relaxed state with a globular and longitudinally shortened
configuration relative to the radially constrained state. In the
expanded state, the woven filaments 14 form the self-expanding
resilient permeable shell 40 in a smooth path radially expanded
from a longitudinal axis 46 of the device between the proximal end
32 and distal end 34. The woven structure of the filaments 14
includes a plurality of openings 64 in the permeable shell 40
formed between the woven filaments. For some embodiments, the
largest of said openings 64 may be configured to allow blood flow
through the openings only at a velocity below a thrombotic
threshold velocity. Thrombotic threshold velocity has been defined,
at least by some, as the time-average velocity at which more than
50% of a vascular graft surface is covered by thrombus when
deployed within a patient's vasculature. In the context of aneurysm
occlusion, a slightly different threshold may be appropriate.
Accordingly, the thrombotic threshold velocity as used herein shall
include the velocity at which clotting occurs within or on a
device, such as device 10, deployed within a patient's vasculature
such that blood flow into a vascular defect treated by the device
is substantially blocked in less than about 1 hour or otherwise
during the treatment procedure. The blockage of blood flow into the
vascular defect may be indicated in some cases by minimal contrast
agent entering the vascular defect after a sufficient amount of
contrast agent has been injected into the patient's vasculature
upstream of the implant site and visualized as it dissipates from
that site. Such sustained blockage of flow within less than about 1
hour or during the duration of the implantation procedure may also
be referred to as acute occlusion of the vascular defect.
[0077] As such, once the device 10 is deployed, any blood flowing
through the permeable shell may be slowed to a velocity below the
thrombotic threshold velocity and thrombus will begin to form on
and around the openings in the permeable shell 40. Ultimately, this
process may be configured to produce acute occlusion of the
vascular defect within which the device 10 is deployed. For some
embodiments, at least the distal end of the permeable shell 40 may
have a reverse bend in an everted configuration such that the
secured distal ends 62 of the filaments 14 are withdrawn axially
within the nominal permeable shell structure or contour in the
expanded state. For some embodiments, the proximal end of the
permeable shell further includes a reverse bend in an everted
configuration such that the secured proximal ends 60 of the
filaments 14 are withdrawn axially within the nominal permeable
shell structure 40 in the expanded state. As used herein, the term
everted may include a structure that is everted, partially everted
and/or recessed with a reverse bend as shown in the device
embodiment of FIGS. 3-6. For such embodiments, the ends 60 and 62
of the filaments 14 of the permeable shell or hub structure
disposed around the ends may be withdrawn within or below the
globular shaped periphery of the permeable shell of the device.
[0078] The elongate resilient filaments 14 of the permeable shell
40 may be secured relative to each other at proximal ends 60 and
distal ends 62 thereof by one or more methods including welding,
soldering, adhesive bonding, epoxy bonding or the like. In addition
to the ends of the filaments being secured together, a distal hub
66 may also be secured to the distal ends 62 of the thin filaments
14 of the permeable shell 40 and a proximal hub 68 secured to the
proximal ends 60 of the thin filaments 14 of the permeable shell
40. The proximal hub 68 may include a cylindrical member that
extends proximally beyond the proximal ends 60 of the thin
filaments so as to form a cavity 70 within a proximal portion of
the proximal hub 68. The proximal cavity 70 may be used for holding
adhesives such as epoxy, solder or any other suitable bonding agent
for securing an elongate detachment tether 72 that may in turn be
detachably secured to a delivery apparatus such as is shown in FIG.
11.
[0079] For some embodiments, the elongate resilient filaments 14 of
the permeable shell 40 may have a transverse cross section that is
substantially round in shape and be made from a superelastic
material that may also be a shape memory metal. The shape memory
metal of the filaments of the permeable shell 40 may be heat set in
the globular configuration of the relaxed expanded state as shown
in FIGS. 3-6. Suitable superelastic shape memory metals may include
alloys such as NiTi alloy and the like. The superelastic properties
of such alloys may be useful in providing the resilient properties
to the elongate filaments 14 so that they can be heat set in the
globular form shown, fully constrained for delivery within an inner
lumen of a microcatheter and then released to self expand back to
substantially the original heat set shape of the globular
configuration upon deployment within a patient's body.
[0080] The device 10 may have an everted filamentary structure with
a permeable shell 40 having a proximal end 32 and a distal end 34
in an expanded relaxed state. The permeable shell 40 has a
substantially enclosed configuration for the embodiments shown.
Some or all of the permeable shell 40 of the device 10 may be
configured to substantially block or impede fluid flow or pressure
into a vascular defect or otherwise isolate the vascular defect
over some period of time after the device is deployed in an
expanded state. The permeable shell 40 and device 10 generally also
has a low profile, radially constrained state, as shown in FIG. 11,
with an elongated tubular or cylindrical configuration that
includes the proximal end 32, the distal end 34 and a longitudinal
axis 46. While in the radially constrained state, the elongate
flexible filaments 14 of the permeable shell 40 may be disposed
substantially parallel and in close lateral proximity to each other
between the proximal end and distal end forming a substantially
tubular or compressed cylindrical configuration.
[0081] Proximal ends 60 of at least some of the filaments 14 of the
permeable shell 40 may be secured to the proximal hub 68 and distal
ends 62 of at least some of the filaments 14 of the permeable shell
40 are secured to the distal hub 66, with the proximal hub 68 and
distal hub 66 being disposed substantially concentric to the
longitudinal axis 46 as shown in FIG. 4. The ends of the filaments
14 may be secured to the respective hubs 66 and 68 by any of the
methods discussed above with respect to securement of the filament
ends to each other, including the use of adhesives, solder, welding
and the like. A middle portion 30 of the permeable shell 40 may
have a first transverse dimension with a low profile suitable for
delivery from a microcatheter as shown in FIG. 11. Radial
constraint on the device 10 may be applied by an inside surface of
the inner lumen of a microcatheter, such as the distal end portion
of the microcatheter 61 shown, or it may be applied by any other
suitable mechanism that may be released in a controllable manner
upon ejection of the device 10 from the distal end of the catheter.
In FIG. 11 a proximal end or hub 68 of the device 10 is secured to
a distal end of an elongate delivery apparatus 111 of a delivery
system 112 disposed at the proximal hub 68 of the device 10.
Additional details of delivery devices can be found in, e.g., US
2016/0367260, which was previously incorporated by reference in its
entirety.
[0082] Some device embodiments 10 having a braided or woven
filamentary structure may be formed using about 10 filaments to
about 300 filaments 14, more specifically, about 10 filaments to
about 100 filaments 14, and even more specifically, about 60
filaments to about 80 filaments 14. Some embodiments of a permeable
shell 40 may include about 70 filaments to about 300 filaments
extending from the proximal end 32 to the distal end 34, more
specifically, about 100 filaments to about 200 filaments extending
from the proximal end 32 to the distal end 34. For some
embodiments, the filaments 14 may have a transverse dimension or
diameter of about 0.0008 inches to about 0.004 inches. The elongate
resilient filaments 14 in some cases may have an outer transverse
dimension or diameter of about 0.0005 inch to about 0.005 inch,
more specifically, about 0.001 inch to about 0.003 inch, and in
some cases about 0.0004 inches to about 0.002 inches. For some
device embodiments 10 that include filaments 14 of different sizes,
the large filaments 48 of the permeable shell 40 may have a
transverse dimension or diameter that is about 0.001 inches to
about 0.004 inches and the small filaments 50 may have a transverse
dimension or diameter of about 0.0004 inches to about 0.0015
inches, more specifically, about 0.0004 inches to about 0.001
inches. In addition, a difference in transverse dimension or
diameter between the small filaments 50 and the large filaments 48
may be less than about 0.004 inches, more specifically, less than
about 0.0035 inches, and even more specifically, less than about
0.002 inches. For embodiments of permeable shells 40 that include
filaments 14 of different sizes, the number of small filaments 50
of the permeable shell 40 relative to the number of large filaments
48 of the permeable shell 40 may be about 2 to 1 to about 15 to 1,
more specifically, about 2 to 1 to about 12 to 1, and even more
specifically, about 4 to 1 to about 8 to 1.
[0083] The expanded relaxed state of the permeable shell 40, as
shown in FIG. 4, has an axially shortened configuration relative to
the constrained state such that the proximal hub 68 is disposed
closer to the distal hub 66 than in the constrained state. Both
hubs 66 and 68 are disposed substantially concentric to the
longitudinal axis 46 of the device and each filamentary element 14
forms a smooth arc between the proximal and distal hubs 66 and 68
with a reverse bend at each end. A longitudinal spacing between the
proximal and distal hubs 66 and 68 of the permeable shell 40 in a
deployed relaxed state may be about 25 percent to about 75 percent
of the longitudinal spacing between the proximal and distal hubs 66
and 68 in the constrained cylindrical state, for some embodiments.
The arc of the filaments 14 between the proximal and distal ends 32
and 34 may be configured such that a middle portion of each
filament 14 has a second transverse dimension substantially greater
than the first transverse dimension.
[0084] For some embodiments, the permeable shell 40 may have a
first transverse dimension in a collapsed radially constrained
state of about 0.2 mm to about 2 mm and a second transverse
dimension in a relaxed expanded state of about 4 mm to about 30 mm.
For some embodiments, the second transverse dimension of the
permeable shell 40 in an expanded state may be about 2 times to
about 150 times the first transverse dimension, more specifically,
about 10 times to about 25 times the first or constrained
transverse dimension. A longitudinal spacing between the proximal
end 32 and distal end 34 of the permeable shell 40 in the relaxed
expanded state may be about 25% percent to about 75% percent of the
spacing between the proximal end 32 and distal end 34 in the
constrained cylindrical state. For some embodiments, a major
transverse dimension of the permeable shell 40 in a relaxed
expanded state may be about 4 mm to about 30 mm, more specifically,
about 9 mm to about 15 mm, and even more specifically, about 4 mm
to about 8 mm.
[0085] An arced portion of the filaments 14 of the permeable shell
40 may have a sinusoidal-like shape with a first or outer radius 88
and a second or inner radius 90 near the ends of the permeable
shell 40 as shown in FIG. 6. This sinusoid-like or multiple curve
shape may provide a concavity in the proximal end 32 that may
reduce an obstruction of flow in a parent vessel adjacent a
vascular defect. For some embodiments, the first radius 88 and
second radius 90 of the permeable shell 40 may be between about
0.12 mm to about 3 mm. For some embodiments, the distance between
the proximal end 32 and distal end 34 may be less than about 60% of
the overall length of the permeable shell 40 for some embodiments.
Such a configuration may allow for the distal end 34 to flex
downward toward the proximal end 32 when the device 10 meets
resistance at the distal end 34 and thus may provide longitudinal
conformance. The filaments 14 may be shaped in some embodiments
such that there are no portions that are without curvature over a
distance of more than about 2 mm. Thus, for some embodiments, each
filament 14 may have a substantially continuous curvature. This
substantially continuous curvature may provide smooth deployment
and may reduce the risk of vessel perforation. For some
embodiments, one of the ends 32 or 34 may be retracted or everted
to a greater extent than the other so as to be more longitudinally
or axially conformal than the other end.
[0086] The first radius 88 and second radius 90 of the permeable
shell 40 may be between about 0.12 mm to about 3 mm for some
embodiments. For some embodiments, the distance between the
proximal end 32 and distal end 34 may be more than about 60% of the
overall length of the expanded permeable shell 40. Thus, the
largest longitudinal distance between the inner surfaces may be
about 60% to about 90% of the longitudinal length of the outer
surfaces or the overall length of device 10. A gap between the hubs
66 and 68 at the proximal end 32 and distal end 34 may allow for
the distal hub 66 to flex downward toward the proximal hub 68 when
the device 10 meets resistance at the distal end and thus provides
longitudinal conformance. The filaments 14 may be shaped such that
there are no portions that are without curvature over a distance of
more than about 2 mm. Thus, for some embodiments, each filament 14
may have a substantially continuous curvature. This substantially
continuous curvature may provide smooth deployment and may reduce
the risk of vessel perforation. The distal end 34 may be retracted
or everted to a greater extent than the proximal end 32 such that
the distal end portion of the permeable shell 40 may be more
radially conformal than the proximal end portion. Conformability of
a distal end portion may provide better device conformance to
irregular shaped aneurysms or other vascular defects. A convex
surface of the device may flex inward forming a concave surface to
conform to curvature of a vascular site.
[0087] FIG. 10 shows an enlarged view of the filaments 14 disposed
within a proximal hub 68 of the device 10 with the filaments 14 of
two different sizes constrained and tightly packed by an outer ring
of the proximal hub 68. The tether member 72 may optionally be
disposed within a middle portion of the filaments 14 or within the
cavity 70 of the proximal hub 68 proximal of the proximal ends 60
of the filaments 14 as shown in FIG. 6. The distal end of the
tether 72 may be secured with a knot 92 formed in the distal end
thereof which is mechanically captured in the cavity 70 of the
proximal hub 68 formed by a proximal shoulder portion 94 of the
proximal hub 68. The knotted distal end 92 of the tether 72 may
also be secured by bonding or potting of the distal end of the
tether 72 within the cavity 70 and optionally amongst the proximal
ends 60 of the filaments 14 with mechanical compression, adhesive
bonding, welding, soldering, brazing or the like. The tether
embodiment 72 shown in FIG. 6 has a knotted distal end 92 potted in
the cavity of the proximal hub 68 with an adhesive. Such a tether
72 may be a dissolvable, severable or releasable tether that may be
part of a delivery apparatus 111 used to deploy the device 10 as
shown in FIG. 11 and FIGS. 23-26. FIG. 10 also shows the large
filaments 48 and small filaments 50 disposed within and constrained
by the proximal hub 68 which may be configured to secure the large
and small filaments 48 and 50 in place relative to each other
within the outer ring of the proximal hub 68.
[0088] FIGS. 7 and 8 illustrate some configuration embodiments of
braided filaments 14 of a permeable shell 40 of the device 10 for
treatment of a patient's vasculature. The braid structure in each
embodiment is shown with a circular shape 100 disposed within a
pore 64 of a woven or braided structure with the circular shape 100
making contact with each adjacent filament segment. The pore
opening size may be determined at least in part by the size of the
filament elements 14 of the braid, the angle overlapping filaments
make relative to each other and the picks per inch of the braid
structure. For some embodiments, the cells or openings 64 may have
an elongated substantially diamond shape as shown in FIG. 7, and
the pores or openings 64 of the permeable shell 40 may have a
substantially more square shape toward a middle portion 30 of the
device 10, as shown in FIG. 8. The diamond shaped pores or openings
64 may have a length substantially greater than the width
particularly near the hubs 66 and 68. In some embodiments, the
ratio of diamond shaped pore or opening length to width may exceed
a ratio of 3 to 1 for some cells. The diamond-shaped openings 64
may have lengths greater than the width thus having an aspect
ratio, defined as Length/Width of greater than 1. The openings 64
near the hubs 66 and 68 may have substantially larger aspect ratios
than those farther from the hubs as shown in FIG. 7. The aspect
ratio of openings 64 adjacent the hubs may be greater than about 4
to 1. The aspect ratio of openings 64 near the largest diameter may
be between about 0.75 to 1 and about 2 to 1 for some embodiments.
For some embodiments, the aspect ratio of the openings 64 in the
permeable shell 40 may be about 0.5 to 1 to about 2 to 1.
[0089] The pore size defined by the largest circular shapes 100
that may be disposed within openings 64 of the braided structure of
the permeable shell 40 without displacing or distorting the
filaments 14 surrounding the opening 64 may range in size from
about 0.005 inches to about 0.01 inches, more specifically, about
0.006 inches to about 0.009 inches, even more specifically, about
0.007 inches to about 0.008 inches for some embodiments. In
addition, at least some of the openings 64 formed between adjacent
filaments 14 of the permeable shell 40 of the device 10 may be
configured to allow blood flow through the openings 64 only at a
velocity below a thrombotic threshold velocity. For some
embodiments, the largest openings 64 in the permeable shell
structure 40 may be configured to allow blood flow through the
openings 64 only at a velocity below a thrombotic threshold
velocity. As discussed above, the pore size may be less than about
0.016 inches, more specifically, less than about 0.012 inches for
some embodiments. For some embodiments, the openings 64 formed
between adjacent filaments 14 may be about 0.005 inches to about
0.04 inches.
[0090] FIG. 12 illustrates in transverse cross section an
embodiment of a proximal hub 68 showing the configuration of
filaments which may be tightly packed and radially constrained by
an inside surface of the proximal hub 68. In some embodiments, the
braided or woven structure of the permeable shell 40 formed from
such filaments 14 may be constructed using a large number of small
filaments. The number of filaments 14 may be greater than 125 and
may also be between about 80 filaments and about 180 filaments. As
discussed above, the total number of filaments 14 for some
embodiments may be about 70 filaments to about 300 filaments, more
specifically, about 100 filaments to about 200 filaments. In some
embodiments, the braided structure of the permeable shell 40 may be
constructed with two or more sizes of filaments 14. For example,
the structure may have several larger filaments that provide
structural support and several smaller filaments that provide the
desired pore size and density and thus flow resistance to achieve a
thrombotic threshold velocity in some cases. For some embodiments,
small filaments 50 of the permeable shell 40 may have a transverse
dimension or diameter of about 0.0006 inches to about 0.002 inches
for some embodiments and about 0.0004 inches to about 0.001 inches
in other embodiments. The large filaments 48 may have a transverse
dimension or diameter of about 0.0015 inches to about 0.004 inches
in some embodiments and about 0.001 inches to about 0.004 inches in
other embodiments. The filaments 14 may be braided in a plain weave
that is one under, one over structure (shown in FIGS. 7 and 8) or a
supplementary weave; more than one warp interlace with one or more
than one weft. The pick count may be varied between about 25 and
200 picks per inch (PPI).
[0091] Limiting blood flow into the aneurysm, as discussed above,
is important with intrasaccular devices. In particular, limiting
blood flow at the neck of the aneurysm is key. Furthermore, good
proximal stability is important to resist movement of the device
(e.g., compaction/displacement away from the neck and into the
aneurysm). The following embodiments help address these issues by
offering techniques to augment proximal flow-disruption and
stability of an intrasaccular device.
[0092] FIGS. 14-15 illustrate embodiments of implantable devices
210 for treatment of a vascular defect, such as an aneurysm, that
include a first shell and a second shell. FIG. 13 separately
illustrates the components of the multi-layer devices 210 of FIGS.
14-15. Device 210 includes a first shell 240 spanning an entire
length of the device 210, and having a radially constrained
elongated state configured for delivery within a microcatheter 61,
with the thin woven filaments 214 extending longitudinally from the
proximal end 232 to the distal end 234 radially adjacent each other
along a length of the filaments. The first shell 240 also has an
expanded relaxed state with a longitudinally shortened
configuration relative to the radially constrained state. In the
expanded state, the woven filaments 214 form the self-expanding
resilient permeable shell 240 in a smooth path radially expanded
from a longitudinal axis of the device between the proximal end 232
and distal end 234.
[0093] The device further includes a second shell 222 along a
proximal region of the first shell 240. The second shell 222 also
has a radially constrained elongated state configured for delivery
within a microcatheter 61, with the thin woven filaments 214
extending longitudinally from the proximal end 232 to a distal end
224 radially adjacent each other along a length of the filaments.
The second shell 222 also has an expanded relaxed state with a
longitudinally shortened configuration relative to the radially
constrained state. The woven filaments 214 that form self-expanding
resilient permeable shell 222 have proximal and distal ends. The
proximal ends of the filaments 214 are gathered at a proximal end
of the device to form a closed proximal end. The distal ends of the
filaments are not gathered together, such that in the expanded
state, the permeable shell 222 may have the approximate shape of a
bowl, hemisphere, or spherical cap. The second shell 222 is adapted
to span a proximal portion 233 of the first shell 240. The second
shell 222 may be placed within an inner cavity of the first shell
240 (see FIG. 14) or may be placed such that an inner surface of
the second shell 222 is in contact with an outer surface of the
proximal portion 233 of the first shell 240, i.e., on the outside
of the proximal part of the first shell 240 (see FIG. 15).
[0094] In one embodiment, the second shell 222 and proximal section
233 of the first shell 240 may be attached together only by a
proximal hub or marker band 252b. In one embodiment, the second
shell 222 and proximal section 233 of the first shell 240 may be
attached together only by a proximal hub 252b (sometimes configured
as a tubular marker band). One advantage of a tubular marker band
(e.g. made of a radiopaque material such as tantalum, gold,
platinum, or palladium) is enhanced visualization of one or both
ends of the device when radiographic imaging is used. In another
embodiment, the first shell 240 and the second shell 222 may be
separately braided or woven and then attached, for instance, by
welding, adhesive, or mechanical ties along a distal section of the
second shell 222. In another embodiment, these separate mechanical
attachment points are supplemented with attachment at a common
proximal hub or marker band 252b. In one embodiment, other than the
proximal hub or marker band attachment junction, the rest of the
second shell 222 has some freedom of movement to help propel open
the first shell 240 upon deployment from a catheter. The degree of
attachment can be customized depending on the desired
characteristics. For instance, where relatively high freedom of
movement between first and second shells 240, 222 is desirable,
relatively few attachment junctions can be used. Where relatively
low freedom of movement between first and second shells 240, 222 is
desirable, more attachments/attachment points can be used.
[0095] In one embodiment, attachment between first shell 240 and
second shell 222 is achieved via interbraiding, such that at least
a portion of second shell 222 is interwoven with first shell 222,
resulting in the two shells being connected.
[0096] In one embodiment, the first shell 240 and second shell 222
are formed of similar wire sizes and are wound in a similar manner
such that the stiffness profiles of each shell are substantially
similar. Because the second shell 222 either overlies or sits
radially within the first shell 240, the proximal region of the
device 210 (where the two shells overlap) will still have enhanced
stiffness due to the combined forces of the two shells, and higher
flow disruption properties as the wires of each shell overlap each
other, augmenting the barrier to blood entry.
[0097] In one embodiment, the first shell 240 may be softer and
have a more flexible configuration than the second shell 222. The
first shell 240, for instance, can use relatively smaller wires
and/or a denser wind pattern than the second shell 222 in order to
achieve this more flexible configuration. In contrast, the second
shell 222 may be stiffer than the first shell 240. This enhanced
stiffness may be achieved, for instance, by use of larger sized
wires that are farther apart (e.g. having a smaller pic count). The
second shell 222 can also include radiopaque components, such as
tantalum, to further enhance stiffness and well as to augment
visualization. A good shape memory material, such as nitinol, may
also be used to create the metallic mesh for the first 240 and
second 222 shells. Enhanced stiffness of the second shell 222
relative to the first shell 240 may be desirable, for instance, to
enhance proximal rigidity of the device to prevent displacement
from the neck of the aneurysm. Furthermore, larger wires in second
shell 222 can augment the flow disruption at the proximal end of
device 210, as there is more material that blood will encounter as
it enters the neck of the aneurysm.
[0098] The first shell 240 may be formed by weaving or braiding
between about 36 and 360 filaments, alternatively between about 72
and 216 filaments, alternatively between about 96 and 144
filaments. The filaments that are woven to form the first shell 240
may have a diameter of between about 0.0003'' and 0.00125'',
alternatively between about 0.0005'' and 0.001'', alternatively
between about 0.0006'' and 0.0009''. The first shell 240 may have a
radial stiffness or a normalized radial stiffness between about
0.001 N/mm and 0.020 N/mm, alternatively between about 0.001 N/mm
and 0.010 N/mm, alternatively between about 0.001 N/mm and 0.005
N/mm.
[0099] The second shell 222 may be formed by weaving or braiding
between about 4 and 216 filaments, alternatively between about 4
and 144 filaments, alternatively between about 4 and 36 filaments.
The filaments that are woven to form the second shell 222 may have
a diameter of between about 0.001'' and 0.004'', alternatively
between about 0.001'' and 0.003'', alternatively between about
0.001'' and 0.002''. The second shell 222 may have a radial
stiffness or a normalized radial stiffness between about 0.005 N/mm
and 0.040 N/mm, alternatively between about 0.005 N/mm and 0.025
N/mm, alternatively between about 0.005 N/mm and 0.020 N/mm.
[0100] In one embodiment, the device 210 may include a distal hub
or marker band attachment point or hub 252a as a junction for the
distal ends of the filaments 214 of the first shell 240. The device
210 may also include a proximal hub or marker band attachment point
or hub 252b for the proximal ends of the filaments 214 of the first
shell 240 and second shell 222. The proximal hub or marker band
252b may then be connected, directly or indirectly, to a mechanical
pusher. A severable junction may separate the pusher from the
occlusive device 210, allowing for detachment of the occlusive
device 210 into the treatment site.
[0101] Though FIGS. 13-16 show the hubs or marker bands or hubs
252a, 252b as extending from the ends of the device, these can be
configured in various ways. For instance, a proximal and distal
dimple or recess (e.g., see FIG. 6) can be utilized where the hub
or marker band sits generally within a plane of the recess, as
shown in FIG. 6. Alternatively, a proximal and distal recess may be
used where the hub or marker band projects outwardly from the plane
of the recess so as to extend distally from the plane defining the
mesh itself can be utilized.
[0102] One advantage to the inclusion of second shell 222 is that
the second shell provide augmented proximal rigidity to help
seating at the treatment site, as discussed above. This augmented
proximal force can be beneficial in a few different ways. First, it
can allow for the inclusion of a relatively soft first shell 240
than would otherwise be possible without the inclusion of a second
shell 222. A soft shell 240 has some advantages in that it can more
readily conform to the dimensions of the treatment site (e.g., a
softer shell can manipulate its shape better if its either
undersized or oversized relative to the treatment site)--however a
soft shell 240 also would have less strength due to its soft
nature. The inclusion of a second proximal shell 222 can enhance
the rigidity of the overall device, allowing for a soft shell 240
that can better adopt to the shape of the treatment site, balanced
with augmented anchoring and retention strength due to the
inclusion of second shell 222. Furthermore, the inclusion of a
second shell 222 can also help open a relatively soft first shell
240, by providing an anchoring force element to help pull open a
softer shell 240 (e.g., where the first shell 240 and second shell
222 are connected along one or more locations).
[0103] The device 210 can be manufactured in a number of sizes to
treat different sized aneurysms. In one example, the first shell
240, and specifically the distal part of the first shell 240 is
soft and able to conform to the shape of the treatment site (for
instance, the dome of an aneurysm). In this way, the device 210 can
be oversized relative to the treatment site, but the distal
softness will allow the device 210 to deform and fold into the
treatment site, thereby enhancing the overall occlusive effect of
the device. Thus, the length of the expanded shape of the first
shell 240 when it is not deployed in the aneurysm (i.e.,
unencumbered) may be larger or longer than a height of the aneurysm
in which it is to be implanted. As seen in FIG. 16, the soft distal
portion of the first shell 240 allows for the device 210 to buckle,
deform, or fold and fit into and within the sac or interior cavity
of the aneurysm. Proximal occlusion at or near the neck of the
aneurysm is maximized by the use of the second shell 222, discussed
above, which sits at the proximal end of the device 210 and acts as
an occlusive barrier at the neck of the aneurysm/treatment
site.
[0104] The expanded form of the device 210 or first shell 240 may
have a longitudinal length of at least about 7 mm, alternatively at
least about 8 mm, alternatively at least about 9 mm, alternatively
at least about 10 mm, alternatively between about 7 mm to about 10
mm, alternatively between about 7 mm and about 9 mm. The length of
the expanded form of the second shell 222 may be about 2 mm,
alternatively about 3 mm, alternatively about 4 mm, alternatively
between about 1.5 mm and about 4 mm, alternatively between about 2
mm and about 4 mm, alternatively between about 2 mm and about 3 mm.
The length of the expanded form of the second shell 222 may be
about 10%, alternatively about 20%, alternatively about 30%,
alternatively about 40% of the total length of the expanded form of
the first shell 240. The length of the expanded form of the second
shell 222 may be between about 10% to about 40%, alternatively
between about 10% to about 30%, alternatively between about 20% to
about 40%, alternatively between about 25% to about 40%,
alternatively between about 20% to about 30% of the total length of
the expanded form of the first shell 240.
[0105] The expanded shape of device 210 can be longer than the
aneurysm in which it is to be inserted, i.e., the longitudinal
length of the expanded shape of the device 210 or first shell 240
can be longer than the length or height of the aneurysm in which it
is being placed. The soft first shell 240 may contain wires with
small diameters, which allows the first shell 240 to easily buckle
or deform as it contacts the aneurysm dome. As seen in FIG. 16, the
device 210 can be placed into aneurysms that are significantly
shorter than the length of the expanded device 210. An additional
advantage of the adjustability of the heights of the device 210 is
that a single size of device 10 can treat a range of aneurysms with
different heights. For example, a device 210 with a length or
height of 7 mm may be able to treat 5.5-6 mm diameter aneurysms
with a range of heights as a result of the compressibility of the
soft first shell 240.
[0106] For some embodiments, the permeable shell 40, 240 or
portions thereof may be porous and may be highly permeable to
liquids. In contrast to most vascular prosthesis fabrics or grafts
which typically have a water permeability below 2,000
ml/min/cm.sup.2 when measured at a pressure of 120 mmHg, the
permeable shell 40 of some embodiments discussed herein may have a
water permeability greater than about 2,000 ml/min/cm.sup.2, in
some cases greater than about 2,500 ml/min/cm.sup.2. For some
embodiments, water permeability of the permeable shell 40 or
portions thereof may be between about 2,000 and 10,000
ml/min/cm.sup.2, more specifically, about 2,000 ml/min/cm.sup.2 to
about 15,000 ml/min/cm.sup.2, when measured at a pressure of 120
mmHg.
[0107] Device embodiments and components thereof may include
metals, polymers, biologic materials and composites thereof.
Suitable metals include zirconium-based alloys, cobalt-chrome
alloys, nickel-titanium alloys, platinum, tantalum, stainless
steel, titanium, gold, and tungsten. Potentially suitable polymers
include but are not limited to acrylics, silk, silicones, polyvinyl
alcohol, polypropylene, polyvinyl alcohol, polyesters (e.g.
polyethylene terephthalate or PET), PolyEtherEther Ketone (PEEK),
polytetrafluoroethylene (PTFE), polycarbonate urethane (PCU) and
polyurethane (PU). Device embodiments may include a material that
degrades or is absorbed or eroded by the body. A bioresorbable
(e.g., breaks down and is absorbed by a cell, tissue, or other
mechanism within the body) or bioabsorbable (similar to
bioresorbable) material may be used. Alternatively, a bioerodable
(e.g., erodes or degrades over time by contact with surrounding
tissue fluids, through cellular activity or other physiological
degradation mechanisms), biodegradable (e.g., degrades over time by
enzymatic or hydrolytic action, or other mechanism in the body), or
dissolvable material may be employed. Each of these terms is
interpreted to be interchangeable. bioabsorbable polymer.
Potentially suitable bioabsorbable materials include polylactic
acid (PLA), poly(alpha-hydroxy acid) such as poly-L-lactide (PLLA),
poly-D-lactide (PDLA), polyglycolide (PGA), polydioxanone,
polycaprolactone, polygluconate, polylactic acid-polyethylene oxide
copolymers, modified cellulose, collagen, poly(hydroxybutyrate),
polyanhydride, polyphosphoester, poly(amino acids), or related
copolymer materials. An absorbable composite fiber may be made by
combining a reinforcement fiber made from a copolymer of about 18%
glycolic acid and about 82% lactic acid with a matrix material
consisting of a blend of the above copolymer with about 20%
polycaprolactone (PCL).
[0108] Permeable shell embodiments 40, 240 may be formed at least
in part of wire, ribbon, or other filamentary elements 14, 214.
These filamentary elements 14 may have circular, elliptical, ovoid,
square, rectangular, or triangular cross-sections. Permeable shell
embodiments 40 may also be formed using conventional machining,
laser cutting, electrical discharge machining (EDM) or
photochemical machining (PCM). If made of a metal, it may be formed
from either metallic tubes or sheet material.
[0109] Device embodiments 10, 210 discussed herein may be delivered
and deployed from a delivery and positioning system 112 that
includes a microcatheter 61, such as the type of microcatheter 61
that is known in the art of neurovascular navigation and therapy.
Device embodiments for treatment of a patient's vasculature 10, 210
may be elastically collapsed and restrained by a tube or other
radial restraint, such as an inner lumen 120 of a microcatheter 61,
for delivery and deployment. The microcatheter 61 may generally be
inserted through a small incision 152 accessing a peripheral blood
vessel such as the femoral artery or brachial artery. The
microcatheter 61 may be delivered or otherwise navigated to a
desired treatment site 154 from a position outside the patient's
body 156 over a guidewire 159 under fluoroscopy or by other
suitable guiding methods. The guidewire 159 may be removed during
such a procedure to allow insertion of the device 10, 210 secured
to a delivery apparatus 111 of the delivery system 112 through the
inner lumen 120 of a microcatheter 61 in some cases. FIG. 17
illustrates a schematic view of a patient 158 undergoing treatment
of a vascular defect 160 as shown in FIG. 18. An access sheath 162
is shown disposed within either a radial artery 164 or femoral
artery 166 of the patient 158 with a delivery system 112 that
includes a microcatheter 61 and delivery apparatus 111 disposed
within the access sheath 162. The delivery system 112 is shown
extending distally into the vasculature of the patient's brain
adjacent a vascular defect 160 in the patient's brain.
[0110] Access to a variety of blood vessels of a patient may be
established, including arteries such as the femoral artery 166,
radial artery 164, and the like in order to achieve percutaneous
access to a vascular defect 160. In general, the patient 158 may be
prepared for surgery and the access artery is exposed via a small
surgical incision 152 and access to the lumen is gained using the
Seldinger technique where an introducing needle is used to place a
wire over which a dilator or series of dilators dilates a vessel
allowing an introducer sheath 162 to be inserted into the vessel.
This would allow the device to be used percutaneously. With an
introducer sheath 162 in place, a guiding catheter 168 is then used
to provide a safe passageway from the entry site to a region near
the target site 154 to be treated. For example, in treating a site
in the human brain, a guiding catheter 168 would be chosen which
would extend from the entry site 152 at the femoral artery up
through the large arteries extending around the heart through the
aortic arch, and downstream through one of the arteries extending
from the upper side of the aorta such as the carotid artery 170.
Typically, a guidewire 159 and neurovascular microcatheter 61 are
then placed through the guiding catheter 168 and advanced through
the patient's vasculature, until a distal end 151 of the
microcatheter 61 is disposed adjacent or within the target vascular
defect 160, such as an aneurysm. Exemplary guidewires 159 for
neurovascular use include the Synchro2.RTM. made by Boston
Scientific and the Glidewire Gold Neuro.RTM. made by MicroVention
Terumo. Typical guidewire sizes may include 0.014 inches and 0.018
inches. Once the distal end 151 of the catheter 61 is positioned at
the site, often by locating its distal end through the use of
radiopaque marker material and fluoroscopy, the catheter is
cleared. For example, if a guidewire 159 has been used to position
the microcatheter 61, it is withdrawn from the catheter 61 and then
the implant delivery apparatus 111 is advanced through the
microcatheter 61.
[0111] Delivery and deployment of device embodiments 10, 210
discussed herein may be carried out by first compressing the device
10, 210 to a radially constrained and longitudinally flexible state
as shown in FIG. 11. The device 10, 210 may then be delivered to a
desired treatment site 154 while disposed within the microcatheter
61, and then ejected or otherwise deployed from a distal end 151 of
the microcatheter 61. In other method embodiments, the
microcatheter 61 may first be navigated to a desired treatment site
154 over a guidewire 159 or by other suitable navigation
techniques. The distal end of the microcatheter 61 may be
positioned such that a distal port of the microcatheter 61 is
directed towards or disposed within a vascular defect 160 to be
treated and the guidewire 159 withdrawn. The device 10, 210 secured
to a suitable delivery apparatus 111 may then be radially
constrained, inserted into a proximal portion of the inner lumen
120 of the microcatheter 61 and distally advanced to the vascular
defect 160 through the inner lumen 120.
[0112] Once disposed within the vascular defect 160, the device 10,
210 may then allowed to assume an expanded relaxed or partially
relaxed state with the permeable shell 40, 240 of the device
spanning or partially spanning a portion of the vascular defect 160
or the entire vascular defect 160. The device 10, 210 may also be
activated by the application of an energy source to assume an
expanded deployed configuration once ejected from the distal
section of the microcatheter 61 for some embodiments. Once the
device 10 is deployed at a desired treatment site 154, the
microcatheter 61 may then be withdrawn.
[0113] Some embodiments of devices for the treatment of a patient's
vasculature 10, 210 discussed herein may be directed to the
treatment of specific types of defects of a patient's vasculature.
For example, referring to FIG. 18, an aneurysm 160 commonly
referred to as a terminal aneurysm is shown in section. Terminal
aneurysms occur typically at bifurcations in a patient's
vasculature where blood flow, indicated by the arrows 172, from a
supply vessel splits into two or more branch vessels directed away
from each other. The main flow of blood from the supply vessel 174,
such as a basilar artery, sometimes impinges on the vessel where
the vessel diverges and where the aneurysm sack forms. Terminal
aneurysms may have a well defined neck structure where the profile
of the aneurysm 160 narrows adjacent the nominal vessel profile,
but other terminal aneurysm embodiments may have a less defined
neck structure or no neck structure. FIG. 19 illustrates a typical
berry type aneurysm 160 in section where a portion of a wall of a
nominal vessel section weakens and expands into a sack like
structure ballooning away from the nominal vessel surface and
profile. Some berry type aneurysms may have a well-defined neck
structure as shown in FIG. 19, but others may have a less defined
neck structure or none at all. FIG. 19 also shows some optional
procedures wherein a stent 173 or other type of support has been
deployed in the parent vessel 174 adjacent the aneurysm. Also,
shown is embolic material 176 being deposited into the aneurysm 160
through a microcatheter 61. Either or both of the stent 173 and
embolic material 176 may be so deployed either before or after the
deployment of a device for treatment of a patient's vasculature
10.
[0114] Prior to delivery and deployment of a device for treatment
of a patient's vasculature 10, 210, it may be desirable for the
treating physician to choose an appropriately sized device 10, 210
to optimize the treatment results. Some embodiments of treatment
may include estimating a volume of a vascular site or defect 160 to
be treated and selecting a device 10, 210 with a volume that is
substantially the same volume or slightly over-sized relative to
the volume of the vascular site or defect 160. The volume of the
vascular defect 160 to be occluded may be determined using
three-dimensional angiography or other similar imaging techniques
along with software which calculates the volume of a selected
region. The amount of over-sizing may be between about 2% and 15%
of the measured volume. In some embodiments, such as a very
irregular shaped aneurysm, it may be desirable to under-size the
volume of the device 10, 210. Small lobes or "daughter aneurysms"
may be excluded from the volume, defining a truncated volume which
may be only partially filled by the device without affecting the
outcome. A device 10, 210 deployed within such an irregularly
shaped aneurysm 160 is shown in FIG. 28 discussed below. Such a
method embodiment may also include implanting or deploying the
device 10, 210 so that the vascular defect 160 is substantially
filled volumetrically by a combination of device and blood
contained therein. The device 10, 210 may be configured to be
sufficiently conformal to adapt to irregular shaped vascular
defects 160 so that at least about 75%, in some cases about 80%, of
the vascular defect volume is occluded by a combination of device
10, 210 and blood contained therein.
[0115] In particular, for some treatment embodiments, it may be
desirable to choose a device 10, 210 that is properly oversized in
a transverse dimension so as to achieve a desired conformance,
radial force and fit after deployment of the device 10. FIGS. 20-22
illustrate a schematic representation of how a device 10, 210 may
be chosen for a proper fit after deployment that is initially
oversized in a transverse dimension by at least about 10% of the
largest transverse dimension of the vascular defect 160 and
sometimes up to about 100% of the largest transverse dimension. For
some embodiments, the device 10, 210 may be oversized a small
amount (e.g. less than about 1.5 mm) in relation to measured
dimensions for the width, height or neck diameter of the vascular
defect 160.
[0116] In FIG. 20, a vascular defect 160 in the form of a cerebral
aneurysm is shown with horizontal arrows 180 and vertical arrows
182 indicating the approximate largest interior dimensions of the
defect 160. Arrow 180 extending horizontally indicates the largest
transverse dimension of the defect 160. In FIG. 21, a dashed
outline 184 of a device for treatment of the vascular defect is
shown superimposed over the vascular defect 160 of FIG. 20
illustrating how a device 10, 210 that has been chosen to be
approximately 20% oversized in a transverse dimension would look in
its unconstrained, relaxed state. FIG. 22 illustrates how the
device 10, 210, which is indicated by the dashed line 184 of FIG.
21 might conform to the interior surface of the vascular defect 160
after deployment whereby the nominal transverse dimension of the
device 10, 210 in a relaxed unconstrained state has now been
slightly constrained by the inward radial force 185 exerted by the
vascular defect 160 on the device 10, 210. In response, as the
filaments 14, 214 of the device 10, 210 and thus the permeable
shell 40, 240 made therefrom have a constant length, the device 10,
210 has assumed a slightly elongated shape in the axial or
longitudinal axis of the device 10 so as to elongate and better
fill the interior volume of the defect 160 as indicated by the
downward arrow 186 in FIG. 22.
[0117] Once a properly sized device 10, 210 has been selected, the
delivery and deployment process may then proceed. It should also be
noted also that the properties of the device embodiments 10, 210
and delivery system embodiments 112 discussed herein generally
allow for retraction of a device 10 after initial deployment into a
defect 160, but before detachment of the device 10, 210. Therefore,
it may also be possible and desirable to withdraw or retrieve an
initially deployed device 10 after the fit within the defect 160
has been evaluated in favor of a differently sized device 10, 210.
An example of a terminal aneurysm 160 is shown in FIG. 23 in
section. The tip 151 of a catheter, such as a microcatheter 61 may
be advanced into or adjacent the vascular site or defect 160 (e.g.
aneurysm) as shown in FIG. 24. For some embodiments, an embolic
coil or other vaso-occlusive device or material 176 (as shown for
example in FIG. 19) may optionally be placed within the aneurysm
160 to provide a framework for receiving the device 10, 210. In
addition, a stent 173 may be placed within a parent vessel 174 of
some aneurysms substantially crossing the aneurysm neck prior to or
during delivery of devices for treatment of a patient's vasculature
discussed herein (also as shown for example in FIG. 19). An example
of a suitable microcatheter 61 having an inner lumen diameter of
about 0.020 inches to about 0.022 inches is the Rapid Transit.RTM.
manufactured by Cordis Corporation. Examples of some suitable
microcatheters 61 may include microcatheters having an inner lumen
diameter of about 0.026 inch to about 0.028 inch, such as the
Rebar.RTM. by Ev3 Company, the Renegade Hi-Flow.RTM. by Boston
Scientific Corporation, and the Mass Transit.RTM. by Cordis
Corporation. Suitable microcatheters having an inner lumen diameter
of about 0.031 inch to about 0.033 inch may include the
Marksmen.RTM. by Chestnut Medical Technologies, Inc. and the Vasco
28.RTM. by Balt Extrusion. A suitable microcatheter 61 having an
inner lumen diameter of about 0.039 inch to about 0.041 inch
includes the Vasco 35 by Balt Extrusion. These microcatheters 61
are listed as exemplary embodiments only, other suitable
microcatheters may also be used with any of the embodiments
discussed herein.
[0118] Detachment of the device 10, 210 from the delivery apparatus
111 may be controlled by a control switch 188 disposed at a
proximal end of the delivery system 112, which may also be coupled
to an energy source 142, which severs the tether 72 that secures
the proximal hub 68 of the device 10 to the delivery apparatus 111.
While disposed within the microcatheter 61 or other suitable
delivery system 112, as shown in FIG. 11, the filaments 14, 214 of
the permeable shell 40, 240 may take on an elongated, non-everted
configuration substantially parallel to each other and a
longitudinal axis of the catheter 61. Once the device 10, 210 is
pushed out of the distal port of the microcatheter 61, or the
radial constraint is otherwise removed, the distal ends 62 of the
filaments 14, 214 may then axially contract towards each other so
as to assume the globular everted configuration within the vascular
defect 160 as shown in FIG. 25.
[0119] The device 10, 210 may be inserted through the microcatheter
61 such that the catheter lumen 120 restrains radial expansion of
the device 10, 210 during delivery. Once the distal tip or
deployment port of the delivery system 112 is positioned in a
desirable location adjacent or within a vascular defect 160, the
device 10, 210 may be deployed out the distal end of the catheter
61 thus allowing the device to begin to radially expand as shown in
FIG. 25. As the device 10, 210 emerges from the distal end of the
delivery system 112, the device 10, 210 expands to an expanded
state within the vascular defect 160, but may be at least partially
constrained by an interior surface of the vascular defect 160.
[0120] Upon full deployment, radial expansion of the device 10, 210
may serve to secure the device 10, 210 within the vascular defect
160 and also deploy the permeable shell 40 across at least a
portion of an opening 190 (e.g. aneurysm neck) so as to at least
partially isolate the vascular defect 160 from flow, pressure or
both of the patient's vasculature adjacent the vascular defect 160
as shown in FIG. 26. The conformability of the device 10, 210,
particularly in the neck region 190 may provide for improved
sealing. For some embodiments, once deployed, the permeable shell
40, 240 may substantially slow the flow of fluids and impede flow
into the vascular site and thus reduce pressure within the vascular
defect 160. For some embodiments, the device 10, 210 may be
implanted substantially within the vascular defect 160, however, in
some embodiments, a portion of the device 10, 210 may extend into
the defect opening or neck 190 or into branch vessels.
[0121] For some embodiments, as discussed above, the device 10, 210
may be manipulated by the user to position the device 10, 210
within the vascular site or defect 160 during or after deployment
but prior to detachment. For some embodiments, the device 10, 210
may be rotated in order to achieve a desired position of the device
10 and, more specifically, a desired position of the permeable
shell 40, 240, prior to or during deployment of the device 10, 210.
For some embodiments, the device 10, 210 may be rotated about a
longitudinal axis of the delivery system 112 with or without the
transmission or manifestation of torque being exhibited along a
middle portion of a delivery catheter being used for the delivery.
It may be desirable in some circumstances to determine whether
acute occlusion of the vascular defect 160 has occurred prior to
detachment of the device 10, 210 from the delivery apparatus 111 of
the delivery system 112. These delivery and deployment methods may
be used for deployment within berry aneurysms, terminal aneurysms,
or any other suitable vascular defect embodiments 160. Some method
embodiments include deploying the device 10, 210 at a confluence of
three vessels of the patient's vasculature that form a bifurcation
such that the permeable shell 40 of the device 10, 210
substantially covers the neck of a terminal aneurysm. Once the
physician is satisfied with the deployment, size and position of
the device 10, 210, the device 10, 210 may then be detached by
actuation of the control switch 188 by the methods described above
and shown in FIG. 26. Thereafter, the device 10, 210 is in an
implanted state within the vascular defect 160 to effect treatment
thereof.
[0122] FIG. 27 illustrates another configuration of a deployed and
implanted device in a patient's vascular defect 160. While the
implantation configuration shown in FIG. 26 indicates a
configuration whereby the longitudinal axis 46 of the device 10,
210 is substantially aligned with a longitudinal axis of the defect
160, other suitable and clinically effective implantation
embodiments may be used. For example, FIG. 27 shows an implantation
embodiment whereby the longitudinal axis 46 of the implanted device
10, 210 is canted at an angle of about 10 degrees to about 90
degrees relative to a longitudinal axis of the target vascular
defect 160. Such an alternative implantation configuration may also
be useful in achieving a desired clinical outcome with acute
occlusion of the vascular defect 160 in some cases and restoration
of normal blood flow adjacent the treated vascular defect. FIG. 28
illustrates a device 10, 210 implanted in an irregularly shaped
vascular defect 160. The aneurysm 160 shown has at least two
distinct lobes 192 extending from the main aneurysm cavity. The two
lobes 192 shown are unfilled by the deployed vascular device 10,
210, yet the lobes 192 are still isolated from the parent vessel of
the patient's body due to the occlusion of the aneurysm neck
portion 190. Markers, such as radiopaque markers, on the device 10,
210 or delivery system 112 may be used in conjunction with external
imaging equipment (e.g. x-ray) to facilitate positioning of the
device or delivery system during deployment. Once the device is
properly positioned, the device 10 may be detached by the user. For
some embodiments, the detachment of the device 10, 210 from the
delivery apparatus 111 of the delivery system 112 may be affected
by the delivery of energy (e.g. heat, radiofrequency, ultrasound,
vibrational, or laser) to a junction or release mechanism between
the device 10 and the delivery apparatus 111. Once the device 10,
210 has been detached, the delivery system 112 may be withdrawn
from the patient's vasculature or patient's body 158. For some
embodiments, a stent 173 may be place within the parent vessel
substantially crossing the aneurysm neck 190 after delivery of the
device 10 as shown in FIG. 19 for illustration.
[0123] For some embodiments, a biologically active agent or a
passive therapeutic agent may be released from a responsive
material component of the device 10, 210. The agent release may be
affected by one or more of the body's environmental parameters or
energy may be delivered (from an internal or external source) to
the device 10, 210. Hemostasis may occur within the vascular defect
160 as a result of the isolation of the vascular defect 160,
ultimately leading to clotting and substantial occlusion of the
vascular defect 160 by a combination of thrombotic material and the
device 10, 210. For some embodiments, thrombosis within the
vascular defect 160 may be facilitated by agents released from the
device 10 and/or drugs or other therapeutic agents delivered to the
patient.
[0124] For some embodiments, once the device 10, 210 has been
deployed, the attachment of platelets to the permeable shell 40 may
be inhibited and the formation of clot within an interior space of
the vascular defect 160, device, or both promoted or otherwise
facilitated with a suitable choice of thrombogenic coatings,
anti-thrombogenic coatings or any other suitable coatings (not
shown) which may be disposed on any portion of the device 10, 210
for some embodiments, including an outer surface of the filaments
14 or the hubs 66 and 68. Such a coating or coatings may be applied
to any suitable portion of the permeable shell 40. Energy forms may
also be applied through the delivery apparatus 111 and/or a
separate catheter to facilitate fixation and/or healing of the
device 10, 210 adjacent the vascular defect 160 for some
embodiments. One or more embolic devices or embolic material 176
may also optionally be delivered into the vascular defect 160
adjacent permeable shell portion that spans the neck or opening 190
of the vascular defect 160 after the device 10 has been deployed.
For some embodiments, a stent or stent-like support device 173 may
be implanted or deployed in a parent vessel adjacent the defect 160
such that it spans across the vascular defect 160 prior to or after
deployment of the vascular defect treatment device 10, 210.
[0125] In any of the above embodiments, the device 10, 210 may have
sufficient radial compliance so as to be readily retrievable or
retractable into a typical microcatheter 61. The proximal portion
of the device 10, 210, or the device as a whole for some
embodiments, may be engineered or modified by the use of reduced
diameter filaments, tapered filaments, or filaments oriented for
radial flexure so that the device 10, 210 is retractable into a
tube that has an internal diameter that is less than about 0.7 mm,
using a retraction force less than about 2.7 Newtons (0.6 lbf)
force. The force for retrieving the device 10, 210 into a
microcatheter 61 may be between about 0.8 Newtons (0.18 lbf) and
about 2.25 Newtons (0.5 lbf).
[0126] Engagement of the permeable shell 40, 240 with tissue of an
inner surface of a vascular defect 160, when in an expanded relaxed
state, may be achieved by the exertion of an outward radial force
against tissue of the inside surface of the cavity of the patient's
vascular defect 160, as shown for example in FIG. 29. A similar
outward radial force may also be applied by a proximal end portion
and permeable shell 40, 240 of the device 10, 210 so as to engage
the permeable shell 40 with an inside surface or adjacent tissue of
the vascular defect 160. Such forces may be exerted in some
embodiments wherein the nominal outer transverse dimension or
diameter of the permeable shell 40 in the relaxed unconstrained
state is larger than the nominal inner transverse dimension of the
vascular defect 160 within which the device 10, 210 is being
deployed, i.e., oversizing as discussed above. The elastic
resiliency of the permeable shell 40 and filaments 14 thereof may
be achieved by an appropriate selection of materials, such as
superelastic alloys, including nickel titanium alloys, or any other
suitable material for some embodiments. The conformability of a
proximal portion of the permeable shell 40, 240 of the device 10,
210 may be such that it will readily ovalize to adapt to the shape
and size of an aneurysm neck 190, as shown in FIGS. 20-22, thus
providing a good seal and barrier to flow around the device. Thus,
the device 10 may achieve a good seal, substantially preventing
flow around the device without the need for fixation members that
protrude into the parent vessel.
[0127] Although the foregoing invention has, for the purposes of
clarity and understanding, been described in some detail by way of
illustration and example, it will be obvious that certain changes
and modifications may be practiced which will still fall within the
scope of the appended claims.
* * * * *