U.S. patent application number 15/297214 was filed with the patent office on 2017-02-09 for method and apparatus for allowing blood flow through an occluded vessel.
This patent application is currently assigned to Perflow Medical Ltd.. The applicant listed for this patent is Perflow Medical Ltd.. Invention is credited to Gilad CIBULSKI, Avraham RAPAPORT.
Application Number | 20170035446 15/297214 |
Document ID | / |
Family ID | 42983641 |
Filed Date | 2017-02-09 |
United States Patent
Application |
20170035446 |
Kind Code |
A1 |
RAPAPORT; Avraham ; et
al. |
February 9, 2017 |
METHOD AND APPARATUS FOR ALLOWING BLOOD FLOW THROUGH AN OCCLUDED
VESSEL
Abstract
A device arranged to sustain and/or provide at least partial
patency of a small blood vessel exhibiting an occlusion, the device
constituted of a tubular body expandable from a first small
diameter state for manipulation to, and through, the occlusion of
the small blood vessel and a second large diameter state, the inner
dimensions of the second large diameter state being no more than
50% of the diameter of the small blood vessel at the occlusion
location, the device presenting a conduit for blood flow through
the occlusion when in the large diameter state. In one embodiment
the small blood vessel is an intracranial blood vessel.
Inventors: |
RAPAPORT; Avraham;
(Tel-Aviv, IL) ; CIBULSKI; Gilad; (Zur-Moshe,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Perflow Medical Ltd. |
Tel-Aviv |
|
IL |
|
|
Assignee: |
Perflow Medical Ltd.
Tel-Aviv
IL
|
Family ID: |
42983641 |
Appl. No.: |
15/297214 |
Filed: |
October 19, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13378053 |
Dec 14, 2011 |
9510855 |
|
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PCT/IL2010/000470 |
Jun 15, 2010 |
|
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15297214 |
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61186942 |
Jun 15, 2009 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2220/0075 20130101;
A61F 2220/005 20130101; A61F 2/88 20130101; A61B 17/320725
20130101; A61B 2090/3966 20160201; A61B 2017/22034 20130101; A61M
29/02 20130101; A61F 2250/0098 20130101; A61B 90/39 20160201; A61B
2017/2215 20130101; A61F 2250/0059 20130101; A61F 2/01 20130101;
A61B 17/221 20130101; A61F 2/844 20130101; A61F 2/86 20130101; A61F
2230/0078 20130101; A61B 2017/00893 20130101; A61F 2220/0058
20130101 |
International
Class: |
A61B 17/221 20060101
A61B017/221; A61B 90/00 20060101 A61B090/00; A61F 2/86 20060101
A61F002/86 |
Claims
1. A device for retrieving at least a portion of an occlusion from
a small blood vessel of 5 mm or less inner diameter, comprising: a
first section comprising a tubular body deliverable into and across
said occlusion, said tubular body expandable within said occlusion,
said tubular body defining a distal end and a proximal end; said
tubular body comprising braided filaments; a second member section
extending from said proximal end of said tubular body and
comprising filaments interweaved in said braided filaments of said
tubular body, wherein said second member section is configured to
be tensioned so as to reduce a diameter of said tubular body.
2. The device according to claim 1, wherein said small blood vessel
is an intracranial blood vessel.
3. The device according to claim 1, wherein said member section is
inherently connected to said tubular body, defining an elongated
protrusion of said expandable tubular body.
4. The device according to claim 1, wherein said braided filaments
of said tubular body are arranged in a `one over one under`
braiding pattern.
5. The device according to claim 1, wherein said tubular body
comprises between 8 and 36 filaments.
6. The device according to claim 1, wherein said device is sized to
fit within a delivery catheter.
7. The device according to claim 6, wherein tensioning of said
member section reduces a diameter of said tubular body enough to
provide for retracting said tubular body into said delivery
catheter.
8. The device according to claim 6, wherein said member section
extends throughout the delivery catheter and is long enough to be
accessible from outside said delivery catheter.
9. The device according to claim 1, wherein said tubular body is
coated with an elastic non-porous material.
10. The device according to claim 1, further comprising a flexible
rod or a filament connected to said distal end of said tubular
body.
11. The device according to claim 10, wherein said flexible rod or
filament comprise a cross sectional area of less than 0.1 mm 2.
12. The device according to claim 10, wherein said flexible rod or
filament is pullable or pushable with respect to said member
section to increase or decrease a length of said tubular body
between said proximal end and said distal end, thereby reducing or
enlarging a diameter of said tubular body.
13. The device according to claim 10, wherein said device is sized
to fit within a delivery catheter and wherein said flexible rod or
filament extends throughout the delivery catheter and is long
enough to be accessible from outside said delivery catheter.
14. The device according to claim 10, wherein said flexible rod or
filament extends distally beyond said distal end of said tubular
body.
15. The device according to claim 1, wherein a length of said
tubular body is between 2 mm and 40 mm longer than a length of said
occlusion.
16. The device according to claim 1, wherein said tubular body is
expandable from an initial small diameter state to a second large
diameter state, said large diameter state limited to a maximal
allowed value determined according to a diameter of said blood
vessel at the occlusion location.
17. The device according to claim 1, wherein the braiding angle of
said braided filaments of the tubular body is between 60.degree.
and 150.degree..
18. The device according to claim 1, wherein in its largest
diameter state said tubular body comprises a generally circular
profile.
19. The device according to claim 1, wherein said tubular body is
configured to allow blood to flow through.
20. The device according to claim 1, wherein said second member
section is formed of a bundle of filaments.
21. The device according to claim 1, wherein at least a part of
said tubular body is formed of radiopaque material.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/378,053 filed on Dec. 14, 2011, which is a
National Phase of PCT Patent Application No. PCT/IL2010/000470
having International Filing Date of Jun. 15, 2010, which claims the
benefit of priority under 35 USC .sctn.119(e) of U.S. Provisional
Patent Application No. 61/186,942 filed on Jun. 15, 2009. The
contents of the above applications are all incorporated by
reference as if fully set forth herein in their entirety.
FIELD AND BACKGROUND OF THE INVENTION
[0002] The invention relates generally to the field of medical
devices, specifically to medical devices that are useful in
treating stroke, and more particularly to a device allowing for the
flow of oxygenated blood through an obstructed artery thus
sustaining at least partial patency.
[0003] Stroke is a leading cause of disability, death and health
care expenditure. Most strokes are ischemic, i.e. caused by a
decrease in the blood supply to a portion of the brain due to a
clot obstructing the flow of blood. A total or hemodynamically
significant occlusion of a cerebral artery in an acute ischemic
stroke is mostly due to thrombus formation, an embolus, and/or
other unwanted matter. When an artery is obstructed, tissue
ischemia (lack of oxygen and nutrients) quickly develops. The organ
most sensitive to ischemia is the brain. Ischemia will rapidly
progress to tissue infarction (cell death) if the occlusion of
blood flow persists. In patients experiencing a typical large
vessel acute ischemic stroke, it has been estimated that within
each hour of no cerebral perfusion, about 20 million neurons are
lost. Therefore, cerebral artery occlusions that lead to stroke
require swift and effective therapy to reduce the morbidity
associated with the disease. The term occlusion as used herein is
meant to include any partial or complete blockage of a blood
vessel, as by thrombosis, embolism or gradual narrowing.
[0004] The functionally impaired region that surrounds the infarct
core and is threatened by cell death has been termed the ischemic
penumbra. The ischemic penumbra, although physiologically impaired,
is potentially salvageable tissue, however the window of
opportunity for recovery of the reversibly injured neurons in the
ischemic penumbra is relatively short. Failure to timely restore
blood flow triggers a biochemical and metabolic cascade ultimately
leading to irreversible brain injury by progressive transformation
of the ischemic penumbra into infarcted tissue, i.e. the infarct
core expands as the penumbra tissue experiences necrosis.
[0005] Traditionally, emergency management of acute ischemic stroke
consisted of mainly general supportive care, e.g. hydration,
monitoring neurological status, blood pressure control, and/or
anti-platelet or anti-coagulation therapy. In 1996 intra-arterial
administration of tissue plasminogen activator (t-PA) was approved
by the FDA for the treatment of acute ischemic stroke in selected
cases within the first few hours from onset. More recently
percutaneous catheter-based technologies have been advanced,
including: placing a microcatheter near the clot and infusing a
thrombolytic agent in order to dissolve the clot; extracting the
clot by distal embolectomy devices in which various wire corkscrews
and baskets are advanced distally through the clot in order to
capture it; and using proximal devices in which the clot is
aspirated or captured and removed. Other methods of removing or
disrupting the clot, include: facilitating fibrinolysis by an
outside energy source such as ultrasound or laser energy;
mechanical manipulation of the clot by primary angioplasty; and
employing stents permanently or transiently are also widely
used.
[0006] Often, more than one method is required until arterial
patency is restored. Such treatment approaches have a common
purpose of restoring artery patency as quickly as possible by
removing or disrupting the obstructing clot. Achieving artery
patency by any of these above methods or any combination of them
(multimodal therapy) is often complex, requires multiple steps and
is time consuming. Even if the treatment is successful, during the
treatment progressive transformation of the penumbra into infarcted
tissue occurs.
[0007] A key therapeutic goal of acute ischemic stroke treatment
consists of re-establishment of arterial potency prior to cell
death. The sooner arterial patency is achieved the greater the
clinical benefit, therefore early restoration of blood flow in the
affected territory of the brain may save brain tissue.
[0008] Cells within an infarction zone have dramatically reduced
blood flow to less than 20% of normal blood flow. As a result,
cells within this infarction zone will be irreversibly damaged
within a few minutes. The blood flow in the ischemic penumbra,
surrounding the infarction zone, is between 20% and 50% of normal.
Cells in this area are endangered, but not irreversibly damaged.
Studies have indicated that a critical focal stenosis of .about.75%
decrease in diameter is usually required to compromise flow in a
major cerebral artery, in face of insufficient collateral flow from
other arteries.
[0009] U.S. Patent Application Publication S/N 2007/0208367
published Sep. 6, 2007 to Fiorella et al is directed to a method of
increasing blood flow through an obstructed blood vessel includes
providing an expandable member substantially made of a mesh having
a plurality of interstices. The expandable member is expanded to
bring at least a portion of the member body into contact with the
occlusion. An outward radial force is exerted on the occlusion to
dislodge at least one fragment from the occlusion and to enhance
blood flow through the blood vessel past the occlusion.
Disadvantageously, the radial force required may traumatize the
blood vessel exhibiting the occlusion. A means for capturing the
dislodged fragment is provided, however the blood flow interruption
due to the capturing mesh itself induces flow resistance.
Additionally, aggregation of the dislodged fragments in the
capturing mesh disrupts and subsequently decreases the blood
flow.
[0010] U.S. Pat. No. 6,295,990 issued Oct. 2, 2001 to Lewis et al,
the entire contents of which is incorporated herein by reference,
is addressed to methods for treating total and partial occlusions
by employing a perfusion conduit which is penetrated through the
occlusive material. Oxygenated blood or other medium is then
perfused through the conduit in a controlled manner, preferably at
a controlled pressure below the arterial pressure, to maintain
oxygenation and relieve ischemia in tissue distal to the occlusion.
The device and method of Lewis is based on an elongated solid
catheter extending from outside the patient body until penetrating
the occlusion. In an embodiment in which passive perfusion is
implemented, blood inlet ports are provided near the proximal end
with blood outlet ports provided at the distal end. The requirement
for inlet and outlet ports fails to take full advantage of the
pressure differential between the proximal and distal sides of the
occlusion.
[0011] An article by Kelly et al published in Stroke, June 2008 at
pages 39: 1770-1773 entitled "Recanalization of an Acute Middle
Cerebral Artery Occlusion Using a Self-Expanding, Reconstrainable,
Intracranial Microstent as a Temporary Endovascular Bypass is
addressed to providing a temporary bypass using a self expanding
stent. Disadvantageously, the self expanding stent exerts radial
force against the occlusion, which may result in undesired breaking
up of the occlusion with significant fragments being dislodged to
proceed further into the bloodstream resulting in potential brain
damage.
[0012] There is thus a need for a method and apparatus for
passively perfusing oxygenated blood through an obstructing clot
while minimizing undesired radial force against the occlusion.
SUMMARY OF THE INVENTION
[0013] In view of the discussion provided above and other
considerations, the present disclosure provides methods and
apparatuses for sustaining patency through an occlusion. This is
accomplished in certain embodiments by providing a device arranged
to provide and/or sustain at least partial patency of a small blood
vessel exhibiting an occlusion. The device comprises a tubular body
expandable from an initial small diameter state for manipulation
adjacent, and/or through, the occlusion of the small blood vessel
and a second large diameter state. In some embodiments, the second
large diameter is limited to a maximal allowed value, thus
preventing undesired radial force against the occlusion.
Optionally, the second large diameter state is no more than 50% of
the diameter of the blood vessel at the occlusion location. The
term small blood vessel as used herein is defined as a blood vessel
of 5 mm or less of inner diameter and may be constituted of an
intracranial blood vessel.
[0014] In one embodiment the device is a self expanding device. In
one embodiment the device in its large diameter state is of a
generally circular shape. In one embodiment the device is an
expanded collapsible conduit between 2 and 40 millimeters longer
than the maximal length of the occlusion.
[0015] Certain embodiments provide for a device arranged to sustain
at least partial patency of a small blood vessel exhibiting an
occlusion, the device comprising a tubular body exhibiting a first
small diameter state for manipulation to, and through, the
occlusion of the small blood vessel, the device expandable to a
second large diameter state within the occlusion, the inner
dimensions of the second large diameter state being no more than
50% of the diameter of the small blood vessel at the occlusion
location, the device presenting a conduit through the tubular body
for blood flow through the occlusion when in the large diameter
state.
[0016] In some embodiments the tubular body in the second large
diameter state does not urge to expand beyond 50% of the diameter
of the small blood vessel. In some embodiments the tubular body in
the second large diameter state exhibits a length at least 14 times
the inner diameter of the tubular body in the second large diameter
state.
[0017] In some embodiments the tubular body in the second large
diameter state exhibits an inner diameter no more than twice the
inner diameter of the tubular body in the first small diameter
state. In some embodiments the device further comprises a distal
filtering extension coupled to a first end of the tubular body. In
certain further embodiments the distal filtering extension is
arranged to expand to meet the inner wall of the small blood vessel
distal of the occlusion. In certain further embodiments the device
further comprises a proximal securing member coupled to a second
end of the tubular body, opposing the first end, the second
securing portion arranged to expand to meet the inner wall of the
small blood vessel.
[0018] In some embodiments the device further comprises a
retraction mechanism arranged to collapse the device from the
second large diameter state within the occlusion, wherein the
device may be withdrawn. In some embodiments the device is coated
with an elastic non-porous material.
[0019] In some embodiments the device is constituted of self
expanding braided filaments. In some embodiment the device further
comprises further comprising a clot retrieval device arranged to
retrieve at least a portion of the occlusion, the clot retrieval
device in communication with the tubular body and exhibiting a
diameter greater than 50% of the diameter of the small blood vessel
at the occlusion location.
[0020] In some embodiments the tubular body is coated with an
elastic porous material. In some embodiments the small blood vessel
is an intracranial blood vessel.
[0021] Independently certain embodiments provide for a temporary
endovascular conduit system arranged to sustain partial patency of
a small blood vessel exhibiting an occlusion, the temporary
endovascular conduit system comprising: a catheter exhibiting an
inside diameter; a device comprising a tubular body exhibiting a
first small diameter state exhibiting an inner diameter less than
the catheter inside diameter, the device expandable to a second
large diameter state when the device is within the occlusion, the
inner diameter of the second large diameter state being no more
than 50% of the diameter of the small blood vessel at the occlusion
location, the device presenting a conduit through the tubular body
for blood flow through the occlusion when in the second large
diameter state.
[0022] In some embodiments the tubular body in the second large
diameter state does not urge to expand beyond 50% of the diameter
of the small blood vessel at the occlusion location. In some
embodiments the tubular body in the second large diameter state
exhibits a length at least 14 times the inner diameter of the
tubular body in the second large diameter state.
[0023] In some embodiments the tubular body in the second large
diameter state exhibits an inner diameter no more than twice the
inner diameter of the tubular body in the first small diameter
state. In some embodiments the device further comprises a distal
filtering extension member coupled to a first end of the tubular
body. In certain further embodiments the distal filtering extension
member is arranged to expand to meet the inner wall of the small
blood vessel distal of the occlusion. In certain further
embodiments the temporary endovascular conduit system further
comprises a proximal securing member coupled to a second end of the
tubular body, opposing the first end, the proximal securing member
arranged to expand to meet the inner wall of the small blood
vessel.
[0024] In some embodiments the temporary endovascular conduit
system further comprises a pair of members in communication with
the device, the device collapsible from the second large diameter
state to the first small diameter state responsive to respective
motion of the members. In some embodiments the tubular body is
coated with an elastic non-porous material.
[0025] In some embodiments the tubular body is coated with an
elastic porous material. In some embodiments the device is
constituted of self expanding braided filaments. In some
embodiments the temporary endovascular conduit system further
comprises a clot retrieval device arranged to retrieve at least a
portion of the occlusion, the clot retrieval device in
communication with the tubular body and exhibiting a diameter
greater than 50% of the diameter of the small blood vessel at the
occlusion location.
[0026] In some embodiments the small blood vessel is an
intracranial blood vessel. In some embodiments the temporary
endovascular conduit system further comprises a member in
communication with the device, the device collapsible from the
second large diameter state to the first small diameter state
responsive to pulling of the member.
[0027] Independently a system for restoring partial patency to a
small blood vessel having an inner diameter and an occlusion is
provided, the system comprising: a delivery catheter including a
shaft having a shaft diameter and a recess adjacent a distal end of
the shaft; and a hollow meshed tube deliverable into the small
blood vessel and across the occlusion by the delivery catheter when
retained in the recess and expandable from a first small diameter
that is substantially similar to or less than the shaft diameter to
a second large diameter that is substantially smaller than the
small blood vessel diameter; wherein the hollow mesh tube is
selectively expandable to the second large diameter in the
occlusion thereby disassociated from the recess and deployed to
sustain a dimension of a passage traveling through the clogged
portion previously created by the delivery catheter.
[0028] In some embodiments the second large diameter is no more
than 200% of the first small diameter. In some embodiments the
second larger diameter is no more than 50% of the small blood
vessel diameter at the occlusion.
[0029] Independently a method of providing blood flow through a
target small blood vessel exhibiting an occlusion is provided, the
method comprising: selecting an expandable tubular body exhibiting
a first small diameter state and a second large diameter state, the
inner dimensions of the second large diameter state being no more
than 50% of the diameter of the target blood vessel at the
occlusion; advancing the selected expandable tubular body while in
the first small diameter state through the occlusion; and expanding
the selected and advanced expandable tubular body towards the
second large diameter state thereby providing a conduit for blood
flow through the occlusion, thereby allowing blood to flow through
the selected expanded tubular body.
[0030] In some embodiments the selected expandable tubular body in
the second large diameter state does not urge to expand beyond 50%
of the diameter of the target small blood vessel at the occlusion.
In some embodiments the method further comprises: selecting the
expandable tubular body such that the further selected expandable
tubular body in the second large diameter state exhibits a length
at least 14 times the inner diameter of the expandable tubular body
in the second large diameter state. In some embodiments the
selected expandable tubular body in the second large diameter state
exhibits an inner diameter no more than twice the inner diameter of
the tubular body in the first small diameter state.
[0031] In some embodiments the selected expandable tubular body
further comprises a distal filtering extension coupled to a distal
end of the selected expandable tubular body. In some further
embodiments the method comprises expanding the distal filtering
extension to meet the inner wall of the target blood vessel distal
of the occlusion. In some further embodiment the selected
expandable tubular body further comprises a proximal securing
member coupled to a proximal end of the selected expandable tubular
body, the method further comprising expanding the proximal securing
member to meet the inner wall of the target small blood vessel
proximal of the occlusion.
[0032] In some embodiments the method further comprises:
contracting the selected expanded tubular body from the second
large diameter state within the occlusion; and withdrawing the
contracted selected tubular body from the target small blood
vessel. In some further embodiments the contracting is to the first
small diameter state.
[0033] In some embodiments the method further comprises delivering
a medicament to the occlusion through the selected expanded tubular
body. In some embodiments the method further comprises withdrawing
at least a portion of the occlusion from the target blood
vessel.
[0034] Independently a method of providing blood flow through a
target small blood vessel exhibiting an occlusion is provided, the
method comprising: providing an expandable tubular body exhibiting
a first small diameter state and a second large diameter state, the
inner dimensions of the second large diameter state being no more
than 50% of the diameter of the target small blood vessel at the
occlusion; advancing the provided expandable tubular body while in
the first small diameter state through the occlusion; and expanding
the provided and advanced expandable tubular body towards the
second large diameter state thereby creating a conduit for blood
flow through the occlusion, the conduit constituted of the provided
expanded tubular body.
[0035] In some embodiments the provided expandable tubular body in
the second large diameter state does not urge to expand beyond 50%
of the diameter of the target blood vessel at the occlusion. In
some embodiments the provided expandable tubular body in the second
large diameter state exhibits a length at least 14 times the inner
diameter of the expandable tubular body in the second large
diameter state. In some embodiments the provided expandable tubular
body in the second large diameter state exhibits an inner diameter
no more than twice the inner diameter of the tubular body in the
first small diameter state.
[0036] In some embodiments the provided expandable tubular body
further comprises a distal filtering extension coupled to a distal
end of the selected expandable tubular body. In some further
embodiments the method further comprises expanding the distal
filtering extension to meet the inner wall of the target small
blood vessel distal of the occlusion. In some further embodiments
the provided expandable tubular body further comprises a proximal
securing member coupled to a proximal end of the selected
expandable tubular body, the method further comprising expanding
the proximal securing member to meet the inner wall of the target
small blood vessel proximal of the occlusion.
[0037] In some embodiments the method further comprises:
contracting the provided expanded tubular body from the second
large diameter state within the occlusion; and withdrawing the
contracted provided tubular body from the target small blood
vessel. In some embodiments the contracting is to the first small
diameter state. In some embodiments the method further comprises
delivering a medicament to the occlusion through the provided
expanded tubular body. In some embodiments the method further
comprises withdrawing at least a portion of the occlusion from the
target small blood vessel.
[0038] Additional features and advantages of the invention will
become apparent from the following drawings and description.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
[0039] For a better understanding of the invention and to show how
the same may be carried into effect, reference will now be made,
purely by way of example, to the accompanying drawings in which
like numerals designate corresponding elements or sections
throughout.
[0040] With specific reference now to the drawings in detail, it is
stressed that the particulars shown are by way of example and for
purposes of illustrative discussion of the preferred embodiments of
the present invention only, and are presented in the cause of
providing what is believed to be the most useful and readily
understood description of the principles and conceptual aspects of
the invention. In this regard, no attempt is made to show
structural details of the invention in more detail than is
necessary for a fundamental understanding of the invention, the
description taken with the drawings making apparent to those
skilled in the art how the several forms of the invention may be
embodied in practice. In the accompanying drawings:
[0041] FIG. 1 illustrates a high level schematic diagram of a
sectioned view of a first embodiment of a temporary endovascular
conduit system, comprising a self expanding device;
[0042] FIGS. 2A-2E illustrate high level schematic diagrams of
partially sectioned views of the distal portion of the temporary
endovascular perfusion conduit system of FIG. 1, showing sequential
steps in the deployment of the self expanding device in a vessel
according to an exemplary embodiment;
[0043] FIG. 3 illustrates a high level schematic diagram of a
partially sectioned view of the distal portion of the temporary
endovascular perfusion conduit system of FIG. 1 and a delivery
mechanism for intra-arterial administration of a medicament
according to an exemplary embodiment;
[0044] FIG. 4 illustrates a high level schematic diagram of a
sectioned view of a second embodiment of a temporary endovascular
conduit system, comprising an expanding device;
[0045] FIGS. 5A-5D illustrate high level schematic diagrams of
partially sectioned views of the distal portion of the temporary
endovascular perfusion conduit system of FIG. 4, showing sequential
steps in the deployment of the expanding device in a vessel
according to an exemplary embodiment;
[0046] FIG. 6 illustrates a high level schematic diagram of a
partially sectioned view of the distal portion of the temporary
endovascular perfusion conduit system of FIG. 4 and a delivery
mechanism for intra-arterial administration of a medicament
according to an exemplary embodiment;
[0047] FIG. 7A illustrates a high level schematic diagram of a
sectioned view of an embodiment of a temporary endovascular
perfusion conduit exhibiting a distal filtering extension
member;
[0048] FIG. 7B illustrates a high level schematic diagram of a
sectioned view of an embodiment of a temporary endovascular
perfusion conduit exhibiting a proximal securing member and a
distal filtering extension member;
[0049] FIG. 8 illustrates a high level schematic diagram of a
sectioned view of an embodiment of a temporary endovascular
perfusion conduit comprising a clot retrieval device; and
[0050] FIG. 9 illustrates a high level flow chart of a method of
providing temporary endovascular perfusion and optional clot
retrieval.
DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION
[0051] Before explaining at least one embodiment of the invention
in detail, it is to be understood that the invention is not limited
in its application to the details of construction and the
arrangement of the components set forth in the following
description or illustrated in the drawings. The invention is
applicable to other embodiments or of being practiced or carried
out in various ways. Also, it is to be understood that the
phraseology and terminology employed herein is for the purpose of
description and should not be regarded as limiting.
[0052] FIG. 1 illustrates a high level schematic diagram of a
sectioned view of a first embodiment of a temporary endovascular
conduit system, denoted temporary endovascular conduit system 50,
deployed in an occlusion 10 occluding a body lumen 15. Temporary
endovascular conduit system 50 comprises: a catheter 40, exhibiting
a proximal portion 60 and a distal portion 80; a hub 90; a pair of
members 26 and 26A; a guide wire 30; and a self expanding device
20, exhibiting a proximal end 22 and a distal end 24, illustrated
in a large diameter state. The diameter of body lumen 15 in the
area of occlusion 10 is denoted D2, and the inner diameter of self
expanding device 20 in the large diameter state, denoted D1, is
preferably between 1/3 and 1/2 of D2. Body lumen 15 is a small
blood vessel, exhibiting an inner diameter D2 of 5 mm or less, as
described above. Advantageously, providing a conduit exhibiting an
inner diameter for blood flow of at least 1/3 of D2 allows a
sufficient blood flow, in the absence of sufficient collateral flow
from other arteries, to prevent or delay cell death, since this
provides for a resultant stenosis of less than 75%.
[0053] Proximal end 22 of self expanding device 20 is positioned
proximally to occlusion 10 and distal end 24 of self expanding
device 20 is positioned distally to occlusion 10. Self expanding
device 20 in the large diameter state provides a conduit for
limited blood flow from proximal end 22 to distal end 24. In one
non-limiting embodiment the length of self expanding device 20 in
the large diameter, denoted L, is at least 5 times D1. In another
non-limiting embodiment length L is at least 10 times D1. In
another non-limiting embodiment length L is at least 15 times D1.
In another non-limiting embodiment length L is at least 20 times
D1. In another non-limiting embodiment length L is at least 30
times D1. In one particular non-limiting embodiment length L is at
least 14 times D1. Thus, a conduit of sufficient length to extend
from a point proximal of occlusion 10 to a point distal of
occlusion 10 is provided. Hub 90 is attached to proximal portion 60
of catheter 40. In one embodiment members 26 and 26A are
respectively connected to proximal end 22 and distal end 24 of self
expanding device 20. Members 26, 26A and guide wire 30 run through
catheter 40 and hub 90 and out therefrom, and are provided to be
long enough so as to be accessible.
[0054] The structure of self expanding device 20 can be of any
kind, provided it is hollow, including, but not limited to, a
tubular tube, a shield tube and a self expanding structure
manufactured by any one of weaving, coiling, laser cutting and
braiding a plurality of filaments. Optionally, self expanding
device 20 is a self expandable braided tubular member, as
illustrated. The braid construction that forms self expanding
device 20 can be produced from many different materials, including,
but not limited to, metals, polymers and composites. More
specifically, these materials can include cobalt-chrome alloys,
stainless steel, nylon, and polyesters. In one embodiment,
superelastic materials such as some nickel titanium alloys, are
used. In one particular embodiment a formulation of nickel titanium
alloy comprising about 51%-56% nickel and about 44%-49% titanium is
used.
[0055] In one embodiment each filament comprising self expanding
device 20 has a round cross section, the diameter of the cross
section usually ranging between about 0.0005 inches and 0.01 inches
and optionally between 0.001 inches and 0.004 inches, and the
number of filaments comprising the braided construction ranges
between 4 and 288. In another embodiment the filaments comprising
self expanding device 20 are flat wires with non-circular cross
sections, the number of filaments ranging between 8 and 64,
optionally between 12 and 24. In one embodiment the braiding angle
is between 60.degree. and 150.degree.. In one particular embodiment
the braiding angle is 90.degree.. In one embodiment the braiding
pattern is a regular pattern known also as herringbone or 1.times.2
pattern. In another embodiment a braiding pattern of 1.times.1 is
used, with such a braiding pattern also known as a "one over one
under" pattern. In one embodiment self expanding device 20 is
permeable to fluids. The inner diameter of self expanding device 20
is in the first small diameter state, denoted D0, when self
expanding device 20 is held within catheter 40 as illustrated in
FIG. 2A described further below. In some embodiments D0 is between
0.5 mm and 1.5 mm, optionally between 0.8 mm and 1.2 mm and
diameter D1 is between 0.8 mm and 2 mm, optionally between 1 mm and
1.5 mm. In certain embodiments the length of self expanding device
20 stays fixed when the diameter of self expanding device 20
changes, and in other embodiments, the length of self expanding
device 20 is reduced when the inner diameter of self expanding
device 20 increases. Alternatively, self expanding device 20 is
substantially not expanded or only slightly expands when elongated
to length L.
[0056] In one embodiment the braid construction that forms self
expanding device 20 is coated with a non-porous elastic material,
illustrated in FIG. 3 as a coating 95. Coating over the porous
braid construction of self expanding device 20 forms a solid
tubular conduit within occlusion 10. The elastic material can be
any of a plurality of materials, including, but not limited to:
polymers such as silicones, polyethers, polyurethanes, polyamides,
hydrogels such as polyvinyl alcohol or polyvinyl pyrrolidone, and
other polymers suitable for intravascular use; permeable,
semi-permeable and non-permeable membranes; and expandable foams.
The elastic material is preferably formed into a fabric mesh and
placed around self expanding device 20. Optionally, the elastic
material is porous, preferably less permeable than self expanding
device 20.
[0057] In the absence of a non-porous elastic material coating, any
particles from occlusion 10 which pass through the relatively small
openings forming self expanding device 20 flow out therefrom,
thereby avoiding harmful disruption of blood flow or occlusion of a
vessel thereof.
[0058] Self expanding device 20 in the large diameter state, as
shown, provides and/or sustains a conduit exhibiting an minimum
inner diameter D1 for sufficient blood flow to the region distal of
occlusion 10 and from there to the affected area, thereby reducing
the infarction rate of penumbral tissue. As a result, the effective
time window for performing endovascular attempts to remove or
disrupt occlusion 10 is expanded. Shortening the length and/or
increasing the hollow cross-section diameter of self expanding
device 20 may result in greater cerebral blood flow to the region
distal to occlusion 10 and from there to the affected area,
resulting in a greater reduction in the infarction rate of
penumbral tissue. In one embodiment length L of self expanding
device 20 in a maximum expanded state is provided to be as short as
possible, while being longer than the length of occlusion 10,
optionally between 2 mm and 40 mm longer than the length of
occlusion 10, and the diameter of the hollow cross-section of self
expanding device 20 in a maximum expanded state is provided to be
between 1/3 and 1/2 of diameter D2 of body lumen 15, as described
above. In one embodiment, where occlusion 10 is 10 mm long, length
L is 20 mm, thereby extending 5 mm proximally of occlusion 10 and 5
mm distally of occlusion 10. In another embodiment, where occlusion
10 is 20-30 mm long, length L between 40 mm and 50 mm, thereby
extending between 5 mm and 15 mm proximally of occlusion 10 and
between 5 mm and 15 mm distally of occlusion 10. Self expanding
device 20 provides enough radial force at diameters up to the
unstressed maximum expanded state of 1/2 of D2 so as to prevent
movement of self expanding device 20 in occlusion 10, while being
small enough so as not traumatize the walls of body lumen 15. In
one non-limiting embodiment, the inside diameter of self expanding
device 20 in its maximum expanded state represents a conduit with a
cross section of at least 0.685 mm.sup.2. When self expanding
device 20 is at its maximum expanded state it is considered to be
at its resting state, since no radial expansion force is exhibited
by self expanding device 20, in particular self expanding device 20
does not urge to expand beyond said second large diameter state.
Thus, self expanding device 20 may exhibit outward radial force
when within occlusion 10, until expansion has reached the
unstressed maximum expanded state of 1/2 of D2. Once self expanding
device 20 has reached the unstressed maximum expanded state of 1/2
of D2 no radial force is applied to occlusion 10. Furthermore no
radial force is applied to the walls of body lumen 15 distally and
proximally of occlusion 10.
[0059] Members 26, 26A are provided in order to facilitate the
deployment of self expanding device 20 into occlusion 10,
particularly aiding in control of localization and further
procedures, and/or the ultimate retraction of self expanding device
20 therefrom. Members 26 and 26A are in one embodiment each
constituted of one of a flexible rod, a filament or a bundle of
filaments. In one embodiment the cross section of each of members
26 and 26A are on the same order as the cross section of guidewire
30, with guidewire 30 preferably being a 0.014'' (0.3556 mm)
guidewire known to the art exhibiting a cross-sectional area of
less than 0.1 mm.sup.2. In the embodiment in which member 26 is
connected to proximal end 22 of self expanding device 20 and member
26A is connected to distal end 24 of self expanding device 20,
stretching and compressing of self expanding device 20 is enabled
by respectively relatively pulling and pushing members 26 and 26A
to expand and decrease the length between proximal end 22 and
distal end 24. Stretching self expanding device 20 reduces its
cross-sectional area and enables an operator to change the
placement of self expanding device 20 easily. Compressing self
expanding device 20 enlarges its hollow cross-sectional area so as
to allow more blood flow there through, as described above. As will
be described below in relation to FIG. 2D, self expanding device 20
can be retracted into catheter 40 by pulling member 26 or by
pulling and pushing members 26, 26A, respectively, and withdrawn
from the patient body along with the retraction of catheter 40.
[0060] In another embodiment members 26,26A are inherently
connected to self expanding device 20, i.e. members 26,26A are thin
local elongated protrusions of self expanding device 20. There is
no requirement that a single catheter 40 be provided for both
delivery of self expanding device 20 and withdrawal of self
expanding device 20. In one embodiment, withdrawal of self
expanding device 20 comprises reduction in radial size to a size
greater than the radial size of self expanding device when first
delivered to occlusion 10.
[0061] In order to enable visualization of the construction that
forms self expanding device 20 under fluoroscopy, in one embodiment
numerous radiopaque materials such as gold, platinum, or tungsten
can be applied using various methods such as marker,
electroplating, ion deposition, and coating. In some embodiments,
self expanding device 20 is at least partially coated with a
radiopaque polymer such as silicone mixed with tantalum powder thus
providing visualization.
[0062] Optionally, self expanding device 20 is secured in location
within occlusion 10 by catheter 40 or by another anchoring means
secured externally of the patient body, such as by members 26, 26A
and 26B, to be described further below.
[0063] FIGS. 2A-2E illustrate high level schematic diagrams of
partially sectioned views of the distal portion of temporary
endovascular conduit system 50 of FIG. 1, showing sequential steps
in the deployment of self expanding device 20 within body lumen 15
across occlusion 10 according to an exemplary embodiment, the
description of FIGS. 2A-2E being taken together. In FIG. 2A self
expanding device 20 is in a collapsed state, i.e. a small diameter
state, and secured within catheter 40, and particularly in a distal
portion of catheter 40. Self expanding device 20 is pre-loaded or
back-loaded onto guidewire 30 while secured within catheter 40.
Guidewire 30 is manipulated through body lumen 15 from an entry
site, such as the femoral artery, to the region of body lumen 15
occluded by occlusion 10. A distal tip 32 of guidewire 30 is
advanced across occlusion 10 using appropriate guidewire and
crossing techniques known in the art. Once distal tip 32 of
guidewire 30 passes through the distal end of occlusion 10,
catheter 40 is advanced through occlusion 10. In one embodiment,
after distal tip 32 of guidewire 30 has passed through the distal
end of occlusion 10, a micro catheter can be used to visualize the
patency of both the vasculature proximal to occlusion 10 and the
vasculature distal to occlusion 10 using conventional radiographic
techniques, prior to advancing catheter 40 over guidewire 30.
[0064] In FIG. 2B temporary endovascular conduit system 50
comprising catheter 40 constraining self expanding device 20 is
advanced through occlusion 10, with distal portion 80 of catheter
40 and distal end 24 of self expanding device 20 extending distally
of occlusion 10. In one embodiment, a radiographic solution may be
injected through hub 90 of FIG. 1 prior to advancing temporary
endovascular conduit system 50 into occlusion 10, thus after the
positioning of catheter 40 across occlusion 10 the length of
occlusion 10 can be determined, thereby allowing an operator to
determine the desired positions of distal end 24 and proximal end
22 of self expanding device 20. In another embodiment, determining
of the length of occlusion 10 is performed prior to inserting
temporary endovascular conduit system 50 in the patient body, thus
enabling the operator to choose a specific self expanding device 20
with desired final length and expanded large diameter. Various
methods can be applied to visualize proximal end 22 and distal end
24 of self expanding device 20 under fluoroscopy, as described
above in relation to FIG. 1.
[0065] In FIG. 2C catheter 40 is partially retracted from
restraining self expanding device 20, while members 26, 26A are
held in place, thereby partially releasing self expanding device 20
from catheter 40 through distal portion 80. Due to self expanding
properties the exposed part of self expanding device 20
automatically performs an outward radial expansion and preferably
forms into a generally circular configuration. Optionally, inner
diameter D1 of self expanding device 20 in the large diameter state
is no greater than twice, optionally no greater than 1.5 times, and
further optionally no greater than 1.2 times the inner diameter D0
of self expanding device 20 in the first small diameter state when
held within catheter 40.
[0066] In FIG. 2D catheter 40 is retracted until self expanding
device 20 is fully released. Self expanding device 20 expands to
its large diameter state, presenting a conduit for blood flow
through occlusion 10. Catheter 40 may be fully retracted from the
patient body. In one embodiment guidewire 30 remains positioned in
occlusion 10 to provide guidance for maneuvering medical means to
the site of occlusion 10. In another embodiment guidewire 30 is
removed from the patient body and member 26 and/or member 26A
provides guidance for maneuvering medical means to the site of
occlusion 10, thus enabling extended medical procedures without the
need of guidewire 30.
[0067] Temporary endovascular conduit system 50 can be fully
retracted out of the patient body, whenever necessary. In one
embodiment this is accomplished by expanding the length of self
expanding device 20 by manipulation of members 26, 26A thereby
reducing the diameter of self expanding device 20. Once the
diameter of self expanding device 20 has been reduced, catheter 40
is preferably advanced over self expanding device 20 while self
expanding device 20 is held in the small diameter state by members
26, 26A, and catheter 40 containing therein self expanding device
20 is then removed from the patient body. Alternatively, catheter
40 is held stationary and self expanding device 20 in the small
diameter state is withdrawn from the area of occlusion 10 towards
distal portion 80 of catheter 40, and then drawn within catheter
40. In an alternative embodiment, self expanding device 20 is
maintained in the small diameter state by the manipulation of
members 26, 26A and removed from the patient body by further
manipulation of members 26, 26A.
[0068] Advantageously, since self expanding device 20 may be
collapsed and returned within catheter 40, numerous deployments of
self expanding device 20 at various locations may be performed as a
single endovascular procedure.
[0069] In another embodiment illustrated in FIG. 2E, a member 26B
constituted of one of a flexible rod, a filament or a bundle of
filaments is attached to proximal end 22 of self expanding device
20. Member 26B can be produced by many different techniques,
including but not limited to looping, tying, stitching,
interweaving, gluing, welding and soldering, to one or more
locations within proximal end 22. In a preferred embodiment member
26B is looped into the collapsible braided construction of proximal
end 22 and thus reduces the diameter of self expanding device 20
while tensioned. Self expanding device 20 can be retracted into
catheter 40 by tensioning holding member 26B and advancing distal
portion 80 of catheter 40 from proximal end 22 to distal end 24 of
self expanding device 20. In this particular embodiment a stopper
27 with an outer diameter fits into the inner diameter of catheter
40 and facilitates deployment of self expanding device 20 into
occlusion 10 since stopper 27 is in contact with proximal end 22 of
self expanding device 20 when retracting catheter 40 out of its
position across occlusion 10.
[0070] FIG. 3 illustrates a high level schematic diagram of a
partially sectioned view of the distal portion of temporary
endovascular conduit system 50 of FIG. 1 and a delivery mechanism
70 for intra-arterial administration of t-PA according to an
exemplary embodiment, with device 20 illustrated with coating 95.
Coating 95 is in some embodiments non-permeable, and in other
embodiments permeable. Self expanding device 20 is shown in its
large diameter state, i.e. its fully expanded uncompressed state,
inside occlusion 10, thereby sustaining at least some blood flow
through occlusion 10, as described above. Thus, penumbral tissue
preservation is facilitated, thereby prolonging the time window for
any effective catheter based recanalization procedure, as described
above. In one embodiment, temporary endovascular conduit system 50
is temporarily deployed, so as to supply oxygenated blood to the
ischemic penumbrae, and thereafter removed prior to any
endovascular procedure for attempting to remove or disrupt
occlusion 10, and optionally redeployed between repeated procedures
for attempting to remove or disrupt occlusion 10. In another
embodiment, as illustrated in FIG. 3, temporary endovascular
conduit system 50 is deployed prior to any endovascular procedure
for recanalization of lumen 15, and self expanding device 20
remains expanded inside occlusion 10 during the procedure, thereby
maintaining blood flow during the procedure. Optionally, coating 95
is permeable, and thus allows for the passage of a fluid from
delivery mechanism 70 to occlusion 10. In such an embodiment,
delivery mechanism 70 is preferably delivered to be within self
expanding device 20 optionally formed of a mesh exhibiting openings
such that fluid exiting delivery mechanism 70 is received to the
circumference of self expanding device 20 deployed across occlusion
10. In another embodiment catheter 40 is used as a passage of a
fluid from outside of the body to the occlusion site eliminating
the need for delivery mechanism 70.
[0071] Delivery mechanism 70 is manipulated through body lumen 15
from an entry site, such as the femoral artery, to a region
proximal to occlusion 10. In the embodiment in which temporary
endovascular conduit system 50 has been removed and guidewire 30
has been left in place, delivery mechanism 70 can be manipulated
over guidewire 30. In the embodiment in which guidewire 30 has also
been removed, or in the embodiment in which temporary endovascular
conduit system 50 has not been removed, as illustrated, delivery
mechanism 70 can be manipulated over a dedicated additional
guidewire and/or through a guiding catheter, or by using any other
technique known in the art. Delivery mechanism 70 administers a
drug such as a neuro-protective agent, or a thrombolytic agent such
as t-PA or any other antithrombotic agent into occlusion 10, thus
breaking down occlusion 10. In another embodiment, other means of
removing or disrupting occlusion 10, such as: thrombolytic agent
infusing techniques; distal or proximal embolectomy devices;
various wire corkscrews and baskets; clot capturing devices; and
clot aspiration and removing devices, can be used. Other methods of
removing or disrupting occlusion 10, such as: facilitating
fibrinolysis by an outside energy source such as ultrasound or
laser energy; and mechanical manipulation of occlusion 10 by
primary angioplasty and/or by employing stents permanently or
transiently, may be used.
[0072] FIG. 4 illustrates a high level schematic diagram of a
sectioned view of a second embodiment of a temporary endovascular
perfusion conduit system, denoted temporary endovascular perfusion
conduit system 150, deployed in an occlusion 10 occluding a body
lumen 15. Temporary endovascular perfusion conduit system 150
comprises: a catheter 40, exhibiting a proximal portion 60 and a
distal portion 80; a hub 90; a pair of members 126 and 126A; and an
expanding device 120, exhibiting a proximal end 122 and a distal
end 124, illustrated in a large diameter state. A guide wire 30 is
also provided. The diameter of body lumen 15 in the area of
occlusion 10 is denoted D2, and the inner diameter of expanding
device 120 in the large diameter state denoted D1, is between 1/3
and 1/2 of D2. Advantageously providing a conduit exhibiting an
inner diameter for blood flow of at least 1/3 of D2 allows a
sufficient blood flow, in the absence of sufficient collateral flow
from other arteries, to prevent or delay cell death since this
provides for a resultant stenosis of less than 75%.
[0073] Proximal end 122 of expanding device 120 is positioned
proximally to occlusion 10 and distal end 124 of expanding device
120 is positioned distally to occlusion 10. Expanding device 120 in
the large diameter state provides a conduit for limited blood flow
from proximal end 122 to distal end 124. Optionally, the length of
expanding device 120 in the large diameter, denoted L, is at least
5 times D1. In another non-limiting embodiment length L is at least
10 times D1. In another non-limiting embodiment length L is at
least 15 times D1. In another non-limiting embodiment length L is
at least 20 times D1. In another non-limiting embodiment length L
is at least 30 times D1. In one particular non-limiting embodiment
length L is at least 14 times D1. Thus, a conduit of sufficient
length to extend from a point proximal of occlusion 10 to a point
distal of occlusion 10 is provided.
[0074] Hub 90 is attached to proximal portion 60 of catheter 40. In
one embodiment members 126 and 126A are respectively connected to
one or both of proximal end 122 and distal end 124 of expanding
device 120. In one particular embodiment member 126 is connected to
proximal end 122 of expanding device 120 and member 126A is
connected to distal end 124 of expanding device 120, as will be
described further hereinto below. Members 126 and 126A and guide
wire 30 run through catheter 40 and hub 90 and out therefrom, and
are provided to be long enough so as to be accessible.
[0075] The structure of expanding device 120 can be of any kind,
providing it is hollow, including, but not limited to, a tubular
tube, a shield tube and a self expanding structure manufactured by
weaving, braiding, laser cutting, or by coiling a filament.
Optionally expanding device 120 is a self expandable coiled tubular
member, as illustrated, formed by winding a filament spirally and
closely over a predetermined diameter and arranged such that when
in a fully expanded state each wind is in contact with an adjacent
wind, thereby forming a solid tubular shape. The coil forming
expanding device 120 can be produced from many different materials,
including, but not limited to, metals, polymers and composites.
More specifically, these materials can include cobalt-chrome
alloys, stainless steel, nylon, and polyesters. In a preferred
embodiment, superelastic materials such as some nickel titanium
alloys, are used. Further preferably, a formulation of nickel
titanium alloy comprising about 51%-56% nickel and about 44%-49%
titanium is used. Optionally, expanding device 120 is not
self-expandable, but is instead balloon-expandable, shape memory
altered by temperature change or externally stretchable without
limitation.
[0076] In one embodiment the filament comprising expanding device
120 has a round cross section, the diameter of the cross section
usually ranging between about 0.001 inches and 0.006 inches and
optionally between 0.001 inches and 0.0035 inches. In another
embodiment the filament comprising expanding device 120 is a flat
wire with a non-circular cross section.
[0077] In one embodiment (not shown) the coil forming expanding
device 120 is coated with a non-porous elastic material. Coating
over the porous coil will form a solid tubular conduit within
occlusion 10. The elastic material can be any of a plurality of
materials, including, but not limited to: polymers such as
silicone, polyethers, polyurethanes, polyamides, hydrogels such as
polyvinyl alcohol or polyvinyl pyrrolidone, and other polymers
suitable for intravascular use; permeable, semi-permeable and
non-permeable membranes; and expandable foams. The elastic material
is formed into a fabric mesh and placed around expanding device
120. Optionally, the elastic material is porous, preferably less
permeable than expanding device 120.
[0078] In the absence of a non-porous elastic material coating any
particles from occlusion 10 which pass through the relatively small
openings forming expanding device 120 flow out therefrom, thereby
avoiding harmful disruption of blood flow or occlusion of a vessel
thereof.
[0079] Expanding device 120 in the large diameter state, as shown,
provides and sustains a conduit exhibiting an inner diameter D1 for
sufficient blood flow to the region distal of occlusion 10 and from
there to the affected area, thereby reducing the infarction rate of
penumbral tissue. As a result, the effective time window for
performing endovascular attempts to remove or disrupt occlusion 10
is expanded. Shortening the length and/or increasing the hollow
cross-section diameter of expanding device 120 may result in
greater cerebral blood flow to the region distal to occlusion 10
and from there to the affected area, resulting in a greater
reduction in the infarction rate of penumbral tissue. In one
embodiment length L of expanding device 120 in a maximum expanded
state is provided to be as short as possible, while being longer
than the length of occlusion 10, optionally between 2 mm and 40 mm
longer than the length of occlusion 10, and the diameter of the
hollow cross-section of expanding device 120 in a maximum expanded
state is provided to be between 1/3 and 1/2 of diameter D2 of body
lumen 15, as described above. In one embodiment, where occlusion 10
is 10 mm long, length L is 20 mm, thereby extending 5 mm proximally
of occlusion 10 and 5 mm distally of occlusion 10. In another
embodiment, where occlusion 10 is 20-30 mm long, length L between
40 mm and 50 mm, thereby extending between 5 mm and 15 mm
proximally of occlusion 10 and between 5 mm and 15 mm distally of
occlusion 10.
[0080] Expanding device 120 provides enough radial force at
diameters up to the unstressed maximum expanded state of 1/2 of D2
so as to prevent movement of expanding device 120 in occlusion 10,
while being small enough so as not traumatize the walls of body
lumen 15. In one non-limiting embodiment, the inside diameter of
expanding device 120 in its maximum expanded state represents a
conduit with a cross section of at least 0.685 mm.sup.2. When
expanding device 120 is at its maximum expanded state it is
considered at resting state, since no radial expansion force is
exhibited by expanding device 120, in particular expanding device
120 does not urge to expand beyond said second large diameter
state. Thus, expanding device 120 may exhibit outward radial force
when within occlusion 10, until expansion has reached the
unstressed maximum expanded state of 1/2 of D2. Once expanding
device 120 has reached the unstressed maximum expanded state of 1/2
of D2 no radial force is applied to occlusion 10. Furthermore no
radial force is applied to the walls of body lumen 15 distally and
proximally of occlusion 10.
[0081] Further preferably the hollow cross-sectional area of
expanding device 120 is small enough so as to allow simultaneous
use of expanding device 120 and a device for dislodging, removing
and/or dissolving the clot, as will be described below in relation
to FIG. 6.
[0082] Optionally, expanding device 120 is secured in location
within occlusion 10 by catheter 40 or by another anchoring means
secured externally of the patient body, such as by members 126,
126A or 126B to be described further below
[0083] Optional members 126,126A are provided in order to
facilitate the deployment of expanding device 120 into occlusion 10
particularly aiding in control of localization and further
procedures, and/or the ultimate retraction of expanding device 120
therefrom. Members 126 and 126A are in one embodiment each
constituted of one of a flexible rod, a filament or a bundle of
filaments. In one embodiment the cross section of each of members
126 and 126A are on the same order as the cross section of
guidewire 30, with guidewire 30 preferably being a 0.014'' (0.3556
mm) guidewire known to the art exhibiting a cross-sectional area of
less than 0.1 mm.sup.2. In the embodiment in which member 126 is
connected to proximal end 122 of expanding device 120 and member
126A is connected to distal end 124 of expanding device 120,
stretching and compressing of expanding device 120 is enabled by
respectively relatively pulling and pushing members 126 and 126A to
expand and decrease the length between proximal end 122 and distal
end 124. Stretching expanding device 120 reduces its
cross-sectional area and enables an operator to change the
placement of expanding device 120 easily. Compressing expanding
device 120 enlarges its hollow cross-sectional area so as to allow
more blood flow there through, as described above. As will be
described below in relation to FIG. 5D, expanding device 120 can be
retracted into the catheter 40 using members 126, 126A and
withdrawn from the patient body along with the retraction of
catheter 40.
[0084] In another embodiment members 126,126A are inherently
connected to expanding device 120, i.e. members 126,126A are thin
local elongated protrusions of expanding device 120. There is no
requirement that a single catheter 40 be provided for both delivery
of expanding device 120 and withdrawal of expanding device 120. In
one embodiment, withdrawal of expanding device 120 comprises
reduction in radial size to a size greater than the radial size of
expanding device when first delivered to occlusion 10.
[0085] In order to enable visualization of the coil that forms
expanding device 120 under fluoroscopy, in one embodiment numerous
radiopaque materials such as gold, platinum, or tungsten can be
applied using various methods such as marker, electroplating, ion
deposition, and coating. In a preferred embodiment, expanding
device 120 is coated with a radiopaque polymer such as silicone
mixed with tantalum powder.
[0086] FIGS. 5A-5E illustrate high level schematic diagrams of
partially sectioned views of the distal portion of temporary
endovascular perfusion conduit system 150 of FIG. 4, showing
sequential steps in the deployment of expanding device 120 within
body lumen 15 across occlusion 10 according to an exemplary
embodiment, the description of FIGS. 5A-5D being taken together. In
FIG. 5A expanding device 120 is in a collapsed state, i.e. a small
diameter state, and secured within catheter 40, and particularly in
a distal portion of catheter 40. Expanding device 120 is pre-loaded
or back-loaded onto guidewire 30 while secured within catheter 40.
Guidewire 30 is manipulated through body lumen 15 from an entry
site, such as the femoral artery, to the region of body lumen 15
occluded by occlusion 10. A distal tip 32 of guidewire 30 is
advanced across occlusion 10 using appropriate guidewire and
crossing techniques known in the art. Once distal tip 32 of
guidewire 30 passes through the distal end of occlusion 10,
catheter 40 is advanced through occlusion 10. In one embodiment,
after distal tip 32 of guidewire 30 has passed through the distal
end of occlusion 10, a micro catheter can be used to visualize the
patency of both the vasculature proximal to occlusion 10 and the
vasculature distal to occlusion 10 using conventional radiographic
techniques, prior to advancing catheter 40 over guidewire 30.
[0087] In FIG. 5B temporary endovascular conduit system 150
comprising catheter 40 constraining expanding device 120 is
advanced through occlusion 10, with distal portion 80 of catheter
40 and distal end 124 of expanding device 120 extending distally of
occlusion 10. In one embodiment, a radiographic solution may be
injected through hub 90 of FIG. 4 prior to advancing temporary
endovascular conduit system 150 into occlusion 10, thus after the
positioning of catheter 40 across occlusion 10 the length of
occlusion 10 can be determined, thereby allowing an operator to
determine the desired positions of distal end 124 and proximal end
122 of expanding device 120. In another embodiment, determining of
the length of occlusion 10 is performed prior to inserting
temporary endovascular conduit system 150 in the patient body, thus
enabling the operator to choose a specific expanding device 120
with a desired final length and expanded large diameter. Various
methods can be applied to visualize proximal end 122 and distal end
124 of expanding device 120 under fluoroscopy, as described above
in relation to FIG. 4.
[0088] In FIG. 5C catheter 40 is partially retracted from expanding
device 120 while members 126,126A are held in place, thereby
partially releasing expanding device 120 from catheter 40 through
distal portion 80. In the embodiment in which expanding device 120
is self expandable, due to self expanding properties the exposed
part of expanding device 120 automatically performs an outward
radial expansion and preferably forms into a generally circular
configuration. Optionally, inner diameter D1 of expanding device
120 in the large diameter state is no greater than twice,
optionally no greater than 1.5 times, and further optionally no
greater than 1.2 times the inner diameter of expanding device 120
in the first small diameter state when held within catheter 40,
denoted D0.
[0089] In FIG. 5D catheter 40 is retracted until expanding device
120 is fully released. Expanding device 120 expands to its large
diameter state presenting a conduit for blood flow through
occlusion 10. Catheter 40 may be fully retracted from the patient
body. In one embodiment guidewire 30 remains positioned in
occlusion 10 to provide guidance for maneuvering medical means to
the site of occlusion 10. In another embodiment guidewire 30 is
removed from the patient body and member 126 and/or member 126A
provides guidance for maneuvering medical means to the site of
occlusion 10, thus enabling extended medical procedures without the
need of a guide wire 30.
[0090] Temporary endovascular perfusion conduit system 150 can be
fully retracted out of the patient body, whenever necessary. In one
embodiment this is accomplished by expanding the length of
expanding device 120 by manipulation of members 126, 126A thereby
reducing the diameter of expanding device 120. Once the diameter of
expanding device 120 has been reduced, catheter 40 is preferably
advanced over expanding device 120 while expanding device 120 is
held in the small diameter state by members 126, 126A, and catheter
40 containing therein expanding device 120 is then removed from the
patient body. Alternatively, catheter 40 is held stationary and
expanding device 120 in the small diameter state is withdrawn from
the area of occlusion 10 towards proximal end 80 of catheter 40,
and then drawn within catheter 40. In an alternative embodiment,
expanding device 120 is maintained in the small diameter state by
the manipulation of members 126, 126A and removed from the patient
body by further manipulation of members 126, 126A.
[0091] Advantageously, since expanding device 120 may be collapsed
and returned within catheter 40, numerous deployments of expanding
device 120 at various locations may be performed as a single
endovascular procedure.
[0092] In another embodiment illustrated in FIG. 5E, expanding
device 120 can be retracted into catheter 40 by a holding member
126B by tensioning holding member 26B and advancing distal portion
80 of catheter 40 from proximal end 122 to distal end 124 of
expanding device 120. In this particular embodiment a stopper 27
exhibiting an outer diameter fits into the inner diameter of
catheter 40 and facilitates the deployment of expanding device 120
into occlusion 10 by keeping stopper 27 in constant contact against
the proximal end 122 of expanding device 120 and pushing it
gradually during the retraction of catheter 40 out of its position
across occlusion 10.
[0093] FIG. 6 illustrates a high level schematic diagram of a
partially sectioned view of the distal portion of temporary
endovascular perfusion conduit system 150 of FIG. 4 and a delivery
mechanism 70 for intra-arterial administration of t-PA according to
an exemplary embodiment. Expanding device 120 is shown in its large
diameter state, i.e. its fully expanded uncompressed state, inside
occlusion 10, thereby sustaining at least some blood flow through
occlusion 10, as described above. Thus, penumbral tissue
preservation is facilitated, thereby prolonging the time window for
any effective catheter based recanalization procedure, as described
above. In one embodiment, temporary endovascular perfusion conduit
system 150 is temporarily deployed, so as to supply oxygenated
blood to the ischemic penumbrae, and thereafter removed prior to
any endovascular procedure for attempting to remove or disrupt
occlusion 10, and optionally redeployed between repeated procedures
for attempting to remove or disrupt occlusion 10. In another
embodiment, illustrated in FIG. 6, temporary endovascular perfusion
conduit system 150 is deployed prior to any endovascular procedure
for attempting to remove or disrupt occlusion 10, and expanding
device 120 remains expanded inside occlusion 10 during the
procedure, thereby maintaining blood flow during the procedure.
Optionally, expanding device 120 is permeable, and thus allows for
the passage of a fluid from delivery mechanism 70 to occlusion 10.
In such an embodiment, delivery mechanism 70 is preferably
delivered to be within expanding device 120 optionally formed as a
spiral winding wherein successive turns are not in contact with
previous turns thus forming a structure such that fluid exiting
delivery mechanism 70 is received to the circumference of expanding
device 120 deployed across occlusion 10. In another embodiment
catheter 40 is used as a passage of a fluid from outside of the
body to the occlusion site eliminating the need for delivery
mechanism 70.
[0094] Delivery mechanism 70 is manipulated through body lumen 15
from an entry site, such as the femoral artery, to a region
proximal to occlusion 10. In the embodiment in which temporary
endovascular perfusion conduit system 150 has been removed and
guidewire 30 has been left in place, delivery mechanism 70 can be
manipulated over guidewire 30. In the embodiment in which guidewire
30 has also been removed, or in the embodiment in which temporary
endovascular perfusion conduit system 150 has not been removed, as
illustrated, delivery mechanism 70 can be manipulated over a
dedicated additional guidewire and/or through a guiding catheter,
or by using any other technique known in the art. Delivery
mechanism 70 administers a drug such as a neuro-protective agent,
or a thrombolytic agent such as t-PA, or any other antithrombotic
agent, into occlusion 10, thus breaking down occlusion 10. In
another embodiment, other means of removing or disrupting occlusion
10, such as: thrombolytic agent infusing techniques; distal or
proximal embolectomy devices; various wire corkscrews and baskets;
clot capturing devices; and clot aspiration and removing devices,
can be used. Other methods of removing or disrupting occlusion 10,
such as: facilitating fibrinolysis by an outside energy source such
as ultrasound or laser energy; and mechanical manipulation of
occlusion 10 by primary angioplasty and/or by employing stents
permanently or transiently, may be used.
[0095] FIG. 7A illustrates a high level schematic diagram of a
sectioned view of an embodiment of a temporary endovascular
perfusion conduit 220 exhibiting a distal filtering extension
member 240, coupled to distal end 24 of self expanding device 20
via transition portion 230. Self expanding device 20 is
substantially as described above in relation to FIG. 1, exhibiting
an inner diameter between 1/3 and 1/2 of D2, i.e. the diameter of
body lumen 15 in the area of occlusion 10. In an exemplary
embodiment distal filtering extension member 240 is sized so as to
meet the inner walls of lumen 15 in the area distal of occlusion
10. In an exemplary embodiment, distal filtering extension member
240 is arranged to be at the resting state for diameters of 0.25
mm-1.5 mm larger than the inner walls of lumen 15 in the area
distal of occlusion 10, thus ensuring that distal filtering
extension member 240 meets the inner walls of lumen 15 and further
optionally provides a securing or anchoring functionality.
Transition portion 230 is optionally a flared portion, and both
transition portion 230 and distal filtering extension member 240
may be provided in a single integrated braid using an appropriately
shaped mandrel, as described in U.S. Pat. No. 7,093,527 issued Aug.
22, 2006 to Rapaport et al, entitled "Method and Apparatus for
Making Intraluminal Implants and Construction Particularly Useful
in such Method and Apparatus", the entire contents of which is
incorporated herein by reference. In an exemplary embodiment,
distal filtering extension member 240 is arranged to trap particles
greater than a predetermined size. In one preferred embodiment the
predetermined size is 500 microns. In another embodiment the
predetermined size is 350 microns. In another embodiment the
predetermined size is 200 microns, and in yet another embodiment
the predetermined size is 80 microns.
[0096] In another embodiment transition portion 230 and distal
filtering extension member 240 are of a different element than that
of temporary endovascular perfusion conduit 220, such as of silicon
or rubber. The distal portion of distal filtering extension member
240 may be open, may exhibit a filter, or be closed in the area
opposing transition portion 230 without exceeding the scope. The
filter of distal filtering extension member 240 may be more or less
permeable than the walls of temporary endovascular perfusion
conduit 220 without exceeding the scope.
[0097] FIG. 7B illustrates a high level schematic diagram of a
sectioned view of an embodiment of a temporary endovascular
perfusion conduit 320 exhibiting distal filtering extension member
240 coupled to distal end 24 of self expanding device 20 via
transition portion 230, and further exhibiting a proximal securing
member 330 coupled to proximal end 22 of self expanding device 20
via a transition portion 340. Self expanding device 20 is
substantially as described above in relation to FIG. 1, exhibiting
an inner diameter between 1/3 and 1/2 of D2, i.e. the diameter of
body lumen 15 in the area of occlusion 10 and distal filtering
extension member 240 is substantially as described above in
relation to FIG. 7A.
[0098] Proximal securing member 330 is preferably sized so as to
meet the inner walls of lumen 15 in the area proximal of occlusion
10, thus occlusion 10 is completely encased by the combination of
self expanding device 20, distal filtering extension member 240 and
proximal securing member 330. In an exemplary embodiment, proximal
securing member 330 is arranged to be at resting state for
diameters of 0.25 mm-1.5 mm larger than the inner walls of lumen 15
in the area proximal of occlusion 10, thus ensuring that proximal
securing member 330 meets the inner walls of lumen 15, thus
securing particles detached from occlusion 10 to flow out
therefrom, thereby avoiding harmful disruption of blood flow or
occlusion of a vessel thereof, and optionally providing a securing
or anchoring functionality. Transition portion 340 is preferably a
flared portion, and both transition portion 340 and proximal
securing member 340 may be provided in a single integrated braid
using an appropriately shaped mandrel, as described in U.S. Pat.
No. 7,093,527 incorporated above by reference.
[0099] FIG. 8 illustrates a high level schematic diagram of a
sectioned view of an embodiment of a temporary endovascular
perfusion conduit 420 comprising a clot retrieval device 430 in
communication with self expanding device 20 shown disposed within
body lumen 15 at occlusion 10. Self expanding device 20 is in all
respects similar to self expanding device 20 of FIG. 1, with the
addition of clot retrieval device 430 constituted of an additional
braid external to that of self expanding device 20. Clot retrieval
device 430 is arranged to be at resting state for diameters of 0.5
mm-1.5 mm larger than the inner walls of lumen 15 in the area
distal of occlusion 10, thus meet the inner walls of body lumen
15.
[0100] Clot retrieval device 430 is in an exemplary embodiment an
open braid having 1/2 or less of the number of filaments
constituting self expanding device 20, and thus expands to trap
within clot retrieval device 430 portions 440 of occlusion 10.
Retrieval of clot retrieval device 430, preferably in combination
with retrieval of self expanding device 20 thus removes at least a
portion of occlusion 10 from body lumen 15 while providing and/or
sustaining a conduit for blood passage having a diameter for
sufficient blood flow to the region distal of occlusion 10. In one
embodiment, not shown for simplicity, distal filtering extension
member 240, described above in relation to FIG. 7A is further
provided. Additionally, or optionally, axial motion of clot
retrieval device 430 may break apart a portion of occlusion 10.
Preferably, in such an embodiment clot retrieval device 430 is
provided in cooperation with distal filtering extension member 240
of FIG. 7A, thus distal filtering extension member 240 is arranged
to trap any portions of occlusion 10 which have been broken apart
by clot retrieval device 430.
[0101] Production of temporary endovascular perfusion conduit 420
is in one embodiment performed by braiding self expanding device 20
with additional filaments coupled to inherent structural filaments
of self expanding device 20, the additional filaments will
ultimately appear only in clot retrieval device 430. Section 450 of
self expanding device 20 is braided, and the additional filaments
are removed from the braiding machine, so that the balance of self
expanding device 20 will not exhibit the additional filaments.
Braiding of self expanding device 20 continues up to section
460.
[0102] As self expanding device 20 is braided to section 460, the
filaments of self expanding device 20 are removed from the braiding
machine, and a tube with an inner diameter larger than that of self
expanding device 20 and an outer diameter of the desired size at
the resting state of clot retrieval device 430 is placed over the
braided portion of self expanding device 20. The additional
filaments of portion 450 are then braided over the tube, up to
section 460. The tube is then removed, and all filaments, including
the filaments of self expanding device 20 and the additional
filaments are braided to completely form section 460.
[0103] The above has been described in an embodiment in which
temporary endovascular perfusion conduit 420 is a braided device,
however this is not meant to be limiting in any way. In another
embodiment temporary endovascular perfusion conduit 430 is
manufactured by any one of weaving, coiling and laser cutting.
[0104] FIG. 9 illustrates a high level flow chart of a method of
providing temporary endovascular perfusion and optional clot
retrieval. In stage 1000, an expandable tubular body is provided,
preferably selected so as to exhibit a first small diameter state
and a second large diameter state. The expandable tubular body
exhibits a diameter in the second large diameter state no more than
50% of the diameter of a target blood vessel at the sight of the
occlusion.
[0105] In optional stage 1010, the length of the expandable tubular
body of stage 1000 is selected so as to be at least 14 times the
inner diameter of the expandable tubular body in the second large
diameter state. In optional stage 1020, the inner diameter of the
expandable tubular body of stage 1000 in the large diameter state
is selected so as to be no greater than twice the diameter of the
expandable tubular body of stage 1000 in the small diameter state.
The inner diameter of the small diameter state may not be inherent,
and in an exemplary embodiment is defined by the parameters of the
delivery catheter, such as catheter 40.
[0106] In stage 1030, the expandable tubular body of stage 1000 is
advanced in the small diameter state through the occlusion.
Alternatively or additionally, a distal portion or a tip of the
catheter is first broached through the occlusion thereby opening
and/or widening a passage therethrough, later to be occupied and
sustained by the expandable tubular body, as the catheter is
further advanced. Optionally, the expandable tubular body is
manipulated through the body and advanced through the occlusion
while loaded onto the distal portion of a delivery catheter, such
as catheter 40.
[0107] In stage 1040, the advanced tubular body of stage 1030 is
expanded towards the second large diameter state, thus providing a
conduit through the expanded tubular body to maintain blood flow
patency through the occlusion. There is no requirement that the
expansion be complete to the second large diameter state, and the
only requirement is that sufficient blood flow patency is restored
by providing blood flow of at least 25% of the unoccluded blood
flow volume. Advantageously, by proper selection of the second
large diameter state no additional radial force is supplied by the
expanded tubular body to the occlusion, thus preventing unintended
and uncontrolled break up.
[0108] In optional stage 1050, a medicament is delivered to the
occlusion. Preferably the tubular body is permeable by the
medicament when in the second large diameter state and thus the
medicament is delivered through the tubular body to the occlusion
surrounding the tubular body.
[0109] In optional stage 1060, a distal filtering extension is
provided distal of the tubular body of stage 1000, the distal
filtering extension being expanded to meet the blood vessel walls
distal of the occlusion. Advantageously, the distal filtering
extension traps any dislodged fragments of the occlusion.
[0110] In optional stage 1070, a proximal securing mechanism is
provided proximal of the tubular body of stage 1000, the proximal
securing mechanism being expanded to meet the blood vessel walls
proximal of the occlusion. Advantageously, the proximal securing
mechanism secures the occlusion and its potentially damaging
fragments from dislodging and proceeding further into the
bloodstream.
[0111] In option stage 1080, the tubular body is contracted,
preferably to the first diameter state, and withdrawn from the
blood vessel. Optionally, a portion of the occlusion is withdrawn
along with the tubular body.
[0112] Thus the present embodiments enable a conduit system
passively perfusing oxygenated blood through an obstructing clot
and allowing for clot retrieval. This is accomplished in certain
embodiments by inserting the conduit system into an occluded blood
vessel providing for at least partial blood flow through the
occluded blood vessel, thereby reducing the infarction rate of
penumbral tissue. In one embodiment this is achieved by providing a
conduit system exhibiting a collapsible conduit. The conduit system
is placed inside the clot occluding the occluded blood vessel. The
collapsible conduit is then expanded, forming a conduit inside the
clot, thereby allowing at least partial blood flow
therethrough.
[0113] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable
sub-combination.
[0114] Unless otherwise defined, all technical and scientific terms
used herein have the same meanings as are commonly understood by
one of ordinary skill in the art to which this invention belongs.
Although methods similar or equivalent to those described herein
can be used in the practice or testing of the present invention,
suitable methods are described herein.
[0115] All publications, patent applications, patents, and other
references mentioned herein are incorporated by reference in their
entirety. In case of conflict, the patent specification, including
definitions, will prevail. In addition, the materials, methods, and
examples are illustrative only and not intended to be limiting.
[0116] It will be appreciated by persons skilled in the art that
the present invention is not limited to what has been particularly
shown and described hereinabove. Rather the scope of the present
invention is defined by the appended claims and includes both
combinations and sub-combinations of the various features described
hereinabove as well as variations and modifications thereof, which
would occur to persons skilled in the art upon reading the
foregoing description.
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