U.S. patent application number 12/966948 was filed with the patent office on 2011-04-14 for methods and systems for treatment of acute ischemic stroke.
Invention is credited to Tony M. Chou, Michi E. Garrison, Gregory M. Hyde.
Application Number | 20110087147 12/966948 |
Document ID | / |
Family ID | 42035628 |
Filed Date | 2011-04-14 |
United States Patent
Application |
20110087147 |
Kind Code |
A1 |
Garrison; Michi E. ; et
al. |
April 14, 2011 |
METHODS AND SYSTEMS FOR TREATMENT OF ACUTE ISCHEMIC STROKE
Abstract
Methods and devices are disclosed that enable safe, rapid and
relatively short and straight access to the cerebral arteries for
the introduction of interventional devices to treat acute ischemic
stroke. In addition, the disclosed methods and devices provide
means to securely close the access site to the cerebral arteries to
avoid the potentially devastating consequences of a transcervical
hematoma.
Inventors: |
Garrison; Michi E.; (Half
Moon Bay, CA) ; Chou; Tony M.; (Hillsborough, CA)
; Hyde; Gregory M.; (Menlo Park, CA) |
Family ID: |
42035628 |
Appl. No.: |
12/966948 |
Filed: |
December 13, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12645179 |
Dec 22, 2009 |
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12966948 |
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61140601 |
Dec 23, 2008 |
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61176463 |
May 7, 2009 |
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Current U.S.
Class: |
604/8 ; 604/509;
606/128; 606/185; 623/1.11 |
Current CPC
Class: |
A61B 17/320725 20130101;
A61F 2/013 20130101; A61M 1/3613 20140204; A61M 2025/0681 20130101;
A61M 29/02 20130101; A61M 1/3653 20130101; A61M 1/3656 20140204;
A61M 2205/7545 20130101; A61M 2025/0031 20130101; A61M 2025/0037
20130101; A61N 7/00 20130101; A61N 2007/0043 20130101; A61M 25/0662
20130101; A61M 2025/0042 20130101; A61M 2025/1052 20130101; A61B
2017/320716 20130101; A61M 25/10 20130101; A61M 1/3659 20140204;
A61M 1/3621 20130101; A61B 17/22004 20130101; A61M 25/007 20130101;
A61B 2017/320733 20130101 |
Class at
Publication: |
604/8 ; 606/185;
606/128; 604/509; 623/1.11 |
International
Class: |
A61M 1/00 20060101
A61M001/00; A61B 17/34 20060101 A61B017/34; A61M 29/02 20060101
A61M029/02; A61B 17/22 20060101 A61B017/22; A61M 25/10 20060101
A61M025/10; A61F 2/82 20060101 A61F002/82 |
Claims
1. A method for accessing a cerebral artery to treat acute ischemic
stroke, comprising: forming a transcervical puncture opening
through a wall of a common carotid artery; inserting through the
puncture opening an arterial access sheath system configured to be
inserted directly into the common carotid artery without previously
inserting an introducer sheath through the opening, the arterial
access sheath system comprising: an arterial access sheath having
an internal lumen extending between a proximal end region and a
distal end region of the arterial access sheath; a dilator inserted
through the internal lumen and extending distal from the distal end
region of the arterial access sheath; and a first occlusion element
coupled to a distal region of the arterial access sheath; providing
access to the cerebral artery via the internal lumen of the
arterial access sheath; and expanding the occlusion element of the
arterial access sheath to occlude an artery selected from the group
consisting of the common carotid artery and an internal carotid
artery.
2. A method as in claim 1, wherein forming the transcervical
puncture opening comprises making the puncture opening directly
into the common carotid artery accessed through a transcervical
surgical incision.
3. A method as in claim 1, wherein forming the transcervical
puncture opening comprises performing a percutaneous puncture into
the common carotid artery.
4. A method as in claim 1, wherein the dilator comprises an outer
diameter that approaches an inner diameter of the distal end region
of the arterial access sheath.
5. A method as in claim 1, further comprising: reversing a
direction of natural blood flow in the internal carotid artery or
common carotid artery; and shunting blood from the cerebral artery
of the patient via the arterial access sheath.
6. A method as in claim 1, wherein the occlusion element is an
inflatable balloon.
7. A method as in claim 1, further comprising: inserting
therapeutic device through the internal lumen of the arterial
access sheath and into the cerebral artery; and treating a
thrombotic blockage in the cerebral artery.
8. A method as in claim 7, wherein the therapeutic device is a
stent delivery catheter and treating the thrombotic blockage
comprises deploying a stent using the stent delivery catheter.
9. A method as in claim 7, wherein the therapeutic device includes
a device adapted to remove a thrombotic blockage.
10. A method as in claim 9, wherein the device adapted to remove a
thrombotic blockage comprises at least one of a coil, a basket, a
snare, or a grasper.
11. A method as in claim 7, wherein the therapeutic device includes
a device adapted to disrupt a thrombotic blockage.
12. A method as in claim 11, wherein the device adapted to disrupt
a thrombotic blockage comprises at least one of a mechanical,
hydraulic, vortex, sonic, ultrasonic, or other energy source.
13. A method as in claim 7, wherein the therapeutic device includes
a device adapted to aspirate the thrombotic blockage or debris
generated from the thrombotic blockage.
14. A method as in claim 7, wherein the therapeutic device includes
a device adapted to infuse thrombolytic agents into a thrombotic
blockage.
15. A method as in claim 7, wherein the therapeutic device is a
device adapted to establish a lumen through the thrombotic
blockage.
16. A method as in claim 15, wherein the device adapted to
establish a lumen through the thrombotic blockage comprises at
least one of a balloon catheter, a temporary stent, or a permanent
stent.
17. A method as in claim 1, wherein the distal end region of the
sheath is tapered and wherein a distal end region of the dilator is
tapered.
18. A system for treating acute ischemic stroke, comprising: an
arterial access sheath comprising an internal lumen extending
between a proximal end region and a distal end region, wherein the
arterial access sheath is adapted to provide access to a cerebral
artery through a puncture opening in a wall of a common carotid
artery; a dilator adapted to be inserted through the internal lumen
and extending distal to the distal end region of the arterial
access sheath; and an occlusion element coupled to the arterial
access sheath at a distal region of the arterial access sheath,
wherein the occlusion element is adapted to expand and occlude an
artery selected from the group consisting of the common carotid
artery and an internal carotid artery.
19. A system as in claim 18, wherein the arterial access sheath
comprises a stepped or tapered configuration wherein the distal end
region has a reduced diameter relative to the proximal end region
of the arterial access sheath.
20. A system as in claim 18, wherein the arterial access sheath has
a hoop strength sufficient to resist buckling of the arterial
access sheath as the arterial access sheath is introduced into the
common carotid artery.
21. A system as in claim 18, wherein the dilator comprises a
tapered distal end and an outer diameter that approaches an inner
diameter of the distal end region of the arterial access
sheath.
22. A system as in claim 18, further comprising a shunt fluidly
connected to the arterial access sheath, wherein the shunt provides
a pathway for blood to flow from the arterial access device to a
return site.
23. A system as in claim 22, further comprising a flow control
assembly coupled to the shunt and adapted to regulate blood flow
through the shunt between at least a first blood flow state and at
least a second blood flow state, wherein the flow control assembly
includes one or more components that interact with the blood flow
through the shunt.
24. A system as in claim 18, wherein a distal tip of the arterial
access sheath is configured to puncture the common carotid artery
such that the arterial access sheath does not require a separate
introducer device in order to be introduced into the common carotid
artery.
25. A system as in claim 18, wherein the distal end region of the
sheath is tapered.
Description
CROSS-REFERENCES TO PRIORITY DOCUMENTS
[0001] This application is a continuation of co-pending U.S.
application Ser. No. 12/645,179, filed Dec. 22, 2009, which claims
priority of U.S. Provisional Patent Application Ser. No.
61/140,601, filed on Dec. 23, 2008 and U.S. Provisional Patent
Application Ser. No. 61/176,463, filed on May 7, 2009. Priority of
the aforementioned filing dates is hereby claimed and the
disclosures of the patent applications are hereby incorporated by
reference in their entirety.
BACKGROUND
[0002] The present disclosure relates generally to medical methods
and devices. More particularly, the present disclosure relates to
methods and systems for accessing the cerebral arterial vasculature
and establishing retrograde blood flow during the interventional
treatment of acute ischemic stroke.
[0003] Acute ischemic stroke is the sudden blockage of adequate
blood flow to a section of the brain, usually caused by thrombus
lodging or forming in one of the blood vessels supplying the brain.
If this blockage is not quickly resolved, the ischemia may lead to
permanent neurologic deficit or death. The timeframe for effective
treatment of stroke is within 3 hours for IV thrombolytic therapy
and 6 hours for site-directed intra-arterial thrombolytic therapy
or interventional recanalization of a blocked cerebral artery.
Reperfusing the ischemic brain after this time period has no
overall benefit to the patient, and may in fact cause harm due to
the increased risk of intracranial hemorrhage from fibrinolytic
use. Even within this time period, there is strong evidence that
the shorter the time period between onset of symptoms and
treatment, the better the results. Unfortunately, the ability to
recognize symptoms, deliver patients to stroke treatment sites, and
finally to treat these patients within this timeframe is rare.
Despite treatment advances, stroke remains the third leading cause
of death in the United States.
[0004] Endovascular treatment of acute stroke is comprised of
either the intra-arterial administration of thrombolytic drugs such
as recombinant tissue plasminogen activator (rtPA), or mechanical
removal of the blockage, or often a combination of the two. As
mentioned above, these interventional treatments must occur within
hours of the onset of symptoms. Both IA thrombolytic therapy, and
interventional thrombectomy involve accessing the blocked cerebral
artery. Like IV thrombolytic therapy, IA thrombolytic therapy has
the limitation in that it may take several hours of infusion to
effectively dissolve the clot.
[0005] Mechanical therapies have involved either capturing and
removing clot, dissolving the clot, or disrupting and suctioning
the clot. The most widely used of these mechanical devices is the
MERCI Retriever System (Concentric Medical, Redwood City, Calif.).
This system uses a balloon guide catheter and a microcatheter to
deliver a coiled retriever across the clot, and then during balloon
occlusion and aspiration of the proximal vessel, pulling the
retriever with the clot into the guide catheter. This device has
had initially positive results as compared to thrombolytic therapy
alone.
[0006] Other thrombectomy devices utilize expandable cages,
baskets, or snares to capture and retrieve clot. A series of
devices using active laser or ultrasound energy to break up the
clot have also been utilized. Other active energy devices have been
used in conjunction with intra-arterial thrombolytic infusion to
accelerate the dissolution of the thrombus. Many of these devices
are used in conjunction with aspiration to aid in the removal of
the clot and reduce the risk of emboli. Frank suctioning of the
clot has also been attempted using microcatheters and syringes,
with mixed results. Devices which apply powered fluid vortices in
combination with suction have been utilized to improve the efficacy
of this method of thrombectomy. Finally, balloons and stents have
been used to create a patent lumen through the clot when clot
removal or dissolution was not possible.
[0007] Some Exemplary Issues with Current Technology
[0008] Interventions in the cerebral vasculature often have special
access challenges. Most neurointerventional procedures use a
transfemoral access to the carotid or vertebral artery and thence
to the target cerebral artery. However, this access route is often
tortuous and may contain stenosis plaque material in the aortic
arch and carotid and brachiocephalic vessel origins, presenting a
risk of embolic complications during the access portion of the
procedure. In addition, the cerebral vessels are usually much
narrower than coronary or other peripheral vasculature. In recent
years, interventional devices such as wires, guide catheters,
stents and balloon catheters, have all been scaled down and been
made more flexible to better perform in the neurovascular anatomy.
However, many neurointerventional procedures remain either more
difficult or impossible because of device access challenges. In the
setting of acute ischemic stroke where "time is brain," these extra
difficulties may have a significant clinical impact.
[0009] Another challenge of neurointerventions is the risk of
cerebral emboli. During the effort to remove or dissolve clot
blockages in the cerebral artery, there is a significant risk of
thrombus fragmentation creating embolic particles which can migrate
downstream and compromise cerebral perfusion, leading to neurologic
events. In carotid artery stenting procedures CAS, embolic
protection devices and systems are commonly used to reduce the risk
of embolic material from entering the cerebral vasculature. The
types of devices include intravascular filters, and reverse flow or
static flow systems. Unfortunately, because of the small anatomy
and access challenges as well as the need for rapid intervention,
these embolic protection systems are not used in interventional
treatment of acute ischemic stroke. Some of the current mechanical
clot retrieval procedures use aspiration as a means to reduce the
risk of emboli and facilitate the removal of the clot. For example,
the MERCI Retrieval System recommends attaching a large syringe to
the guide catheter, and then blocking the proximal artery and
aspirating the guide catheter during pull back of the clot into the
guide. However, this step requires a second operator, may require
an interruption of aspiration if the syringe needs to be emptied
and reattached, and does not control the rate or timing of
aspiration. This control may be important in cases where there is
some question of patient tolerance to reverse flow. Furthermore,
there is no protection against embolic debris during the initial
crossing of the clot with the microcatheter and deployment of the
retrieval device.
[0010] Another limitation of current systems is the difficulty in
aspirating from the target artery only. Guide catheters are usually
placed proximally in the carotid, vertebral or basilar artery below
the blocked artery. Aspiration on the guide catheter pulls flow not
just from the target artery but from other arteries branching off
from the proximal artery. This reduces the suction force on the
target artery and furthermore may reduce the level of blood flow to
other tissue beds.
[0011] One severe drawback to current acute stroke interventions is
the amount of time required to achieve recanalization, either
during to access of the blocked cerebral artery, or time required
to remove the blockage. Recanalization, either through thrombolytic
therapy, mechanical thrombectomy, or other means, often takes hours
during which time brain tissue is deprived of adequate oxygen.
During this period, there is a risk of permanent injury to the
brain tissue. Means to shorten the procedure time, and/or to
provide oxygen to the brain tissue during the procedure, would
reduce this risk.
SUMMARY
[0012] Disclosed are methods and devices that enable safe, rapid
and relatively short and straight access to the cerebral arteries
for the introduction of interventional devices to treat acute
ischemic stroke. In addition, the disclosed methods and devices
provide means to securely close the access site to the cerebral
arteries to avoid the potentially devastating consequences of a
transcervical hematoma. The methods and devices include a vascular
access with retrograde flow system that can be used safely and
rapidly in the neurointerventional procedures. The system offers
the user a degree of blood flow control so as to address the
specific hemodynamic requirements of the cerebral vasculature. The
disclosed methods also include means to protect the cerebral
penumbra during the procedure, to minimize injury to brain.
[0013] In one aspect, there is disclosed In one aspect, there is
disclosed a system of devices for treating acute ischemic stroke,
comprising: an arterial access sheath adapted to be introduced into
a common carotid, internal carotid, or vertebral artery and receive
blood from the artery; a shunt fluidly connected to the arterial
access sheath, wherein the shunt provides a pathway for blood to
flow from the arterial access sheath to a return site; a flow
control assembly coupled to the shunt and adapted to regulate blood
flow through the shunt; and a therapeutic device adapted to be
introduced into the artery through the arterial access sheath and
configured to treat a thrombotic blockage from a cerebral
artery.
[0014] In another aspect, there is disclosed a system of devices
for treating acute ischemic stroke, comprising: an arterial access
sheath adapted to be introduced into a common carotid or vertebral
artery and receive blood from the artery; a shunt fluidly connected
to the arterial access sheath, wherein the shunt provides a pathway
for blood to flow from the arterial access sheath to a return site;
a flow control assembly coupled to the shunt and adapted to
regulate blood flow through the shunt; and a perfusion catheter
adapted to be introduced in into the artery through the arterial
access sheath and positioned in a site adjacent to or through a
thrombotic blockage in a cerebral artery, wherein the perfusion
catheter has at least one perfusion lumen for perfusing fluid into
the cerebral artery.
[0015] In another aspect, there is disclosed a method for accessing
a cerebral artery to treat acute ischemic stroke, comprising:
forming a penetration in a wall of a common carotid, internal
carotid, or vertebral artery; positioning an arterial access sheath
through the penetration into the artery; occluding at least one of
the common or internal carotid artery or vertebral or basilar
artery; and treating a thrombotic blockage in the cerebral
artery.
[0016] In another aspect, there is disclosed a method for accessing
a cerebral artery to treat acute ischemic stroke, comprising:
forming a percutaneous penetration in a wall of a common carotid,
internal carotid, or vertebral artery; applying a closure device at
a site of penetration before placement of an arterial access
sheath; positioning an arterial access sheath through the
penetration into the artery; treating a thrombotic blockage in the
cerebral artery; and closing the access site with the closure
device.
[0017] In another aspect, there is disclosed a method for accessing
a cerebral artery to treat acute ischemic stroke, comprising:
forming a penetration in a wall of a common carotid, internal
carotid or vertebral artery; positioning an arterial access sheath
through the penetration; inserting a treatment device through the
arterial access sheath into the artery; positioning at least a
portion of the treatment device in the cerebral artery; removing
thrombotic blockage in the cerebral artery using the treatment
device.
[0018] In another aspect, there is disclosed a method for accessing
a cerebral artery to treat acute ischemic stroke, comprising:
forming a penetration in a wall of a common carotid or vertebral
artery; positioning an arterial access sheath through the
penetration; infusing a thrombolytic drug through the arterial
access sheath to a thrombotic blockage in the cerebral artery; and
removing thrombotic blockage in the cerebral artery using the
thrombolytic drug.
[0019] In another aspect, there is disclosed a method for accessing
a cerebral artery to treat acute ischemic stroke, comprising:
forming a penetration in a wall of a common carotid or vertebral
artery; positioning an arterial access sheath through the
penetration; infusing a thrombolytic drug through the arterial
access sheath to a thrombotic blockage in the cerebral artery;
removing thrombotic blockage in the cerebral artery using the
thrombolytic drug.
[0020] Other features and advantages should be apparent from the
following description of various embodiments, which illustrate, by
way of example, the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 schematically depicts normal, antegrade cerebral
circulation with a thrombotic occlusion in the left middle cerebral
artery.
[0022] FIG. 2 depicts the blood flow circulation after retrograde
flow has been established using the retrograde flow system
described herein.
[0023] FIG. 3 shows the cerebral vasculature with a mechanical
thrombectomy device inserted through an exemplary arterial access
device.
[0024] FIG. 4 shows an alternate embodiment wherein a secondary
interventional device is advanced through the arterial access
device and into a collateral cerebral artery.
[0025] FIG. 5A shows an exemplary embodiment of a vascular access
and reverse flow system that can be used to establish retrograde
flow during removal of the thrombotic occlusion.
[0026] FIG. 5B shows an enlarged view of the common carotid artery,
internal carotid artery, and middle cerebral artery with an
arterial access device and a thrombectomy device deployed.
[0027] FIG. 6 shows an enlarged view of a distal region of an
exemplary thrombectomy device in a collapsed condition in a blood
vessel.
[0028] FIG. 7 shows the thrombectomy device advanced further into
the vasculature to a position distal to the thrombotic
occlusion.
[0029] FIG. 8 shows coils of the thrombectomy device engaging the
thrombotic occlusion.
[0030] FIG. 9 shows another embodiment of a thrombectomy
device.
[0031] FIG. 10A illustrates an arterial access device useful in the
methods and systems of the present disclosure.
[0032] FIG. 10B illustrates an additional arterial access device
construction with a reduced diameter distal end.
[0033] FIGS. 11A and 11B illustrate a tube useful with the sheath
of FIG. 10A.
[0034] FIG. 12A illustrates an additional arterial access device
construction with an expandable occlusion element.
[0035] FIG. 12B illustrates an additional arterial access device
construction with an expandable occlusion element and a reduced
diameter distal end.
[0036] FIG. 13 illustrates a first embodiment of a venous return
device useful in the methods and systems of the present
disclosure.
[0037] FIG. 14 illustrates an alternative venous return device
useful in the methods and systems of the present disclosure.
[0038] FIG. 15 shows an example of the reverse flow system with a
schematic representation of the flow control assembly.
[0039] FIG. 16A-16D, FIGS. 17A-17D, FIGS. 18A and 18B, FIGS.
19A-19D, and FIGS. 20A and 20B, illustrate different embodiments of
a variable flow resistance component useful in the methods and
systems of the present disclosure.
[0040] FIGS. 21A-21B, FIGS. 22A-22B, FIGS. 23A-23D, and FIGS.
24A-24B illustrate further embodiments of a variable flow
resistance system useful in the methods and systems of the present
disclosure.
[0041] FIG. 25 shows a perfusion catheter positioned adjacent to a
thrombotic blockage in the vasculature.
[0042] FIG. 26 shows the perfusion catheter positioned across the
thrombotic blockage to enable perfusion distal to the blockage.
[0043] FIG. 27A shows a perfusion catheter that includes an
occlusion balloon with perfusion holes.
[0044] FIGS. 27B-27C shows alternate embodiments of perfusion
catheters.
[0045] FIG. 28 shows an arterial access device having a stepped
configuration, with an occlusion element.
[0046] FIG. 29 shows an arterial access device, and an additional
sub-selective sheath with occlusion element placed through the
arterial access device and occluding a distal artery
[0047] FIG. 30 shows the arterial access device, and a telescoping
extension with an occlusion element which extends the lumen of the
arterial access device into a distal artery and occludes the distal
artery.
DETAILED DESCRIPTION
[0048] Disclosed are methods and devices that enable safe, rapid
and relatively short and straight access to the cerebral arteries
for the introduction of interventional devices to treat acute
ischemic stroke. In addition, the disclosed methods and devices
provide means to securely close the access site to the cerebral
arteries to avoid the potentially devastating consequences of a
transcervical hematoma. The methods and devices include a vascular
access with retrograde flow system that can be used safely and
rapidly in the neurointerventional procedures. The system offers
the user a degree of blood flow control so as to address the
specific hemodynamic requirements of the cerebral vasculature. The
disclosed methods also include means to protect the cerebral
penumbra during the procedure, to minimize injury to brain.
[0049] FIG. 1 schematically depicts normal, antegrade cerebral
circulation with a thrombotic occlusion 10 in the left middle
cerebral artery RMCA. The left middle cerebral artery RMCA branches
from the left internal carotid artery RICA. The middle cerebral
arteries are large arteries that have tree-like branches that bring
blood to the entire lateral aspect of each hemisphere of the brain.
The thrombotic occlusion 10 occludes or limits blood flow through
the left middle cerebral artery. Thus, blood supply to the brain is
severely interrupted by the presence of the thrombotic occlusion 10
in the left middle cerebral artery, creating an ischemic stroke
condition.
[0050] Pursuant to use of methods and systems described herein, a
treatment method includes obtaining vascular access to the cerebral
arteries and establishing retrograde flow in at least a portion of
the cerebral circulation in order to safely treat the thrombotic
occlusion. Retrograde flow is sometimes referred to as reverse
flow. A mechanical thrombectomy device is inserted into the
cerebral vasculature to remove the thrombotic occlusion under
retrograde flow conditions, as described below. FIG. 2 depicts the
blood flow circulation after retrograde flow has been established
using the retrograde flow system described herein. The system
includes an arterial access device 110 that enters the left common
carotid artery LCCA to provide access to the cerebral vasculature.
An expandable occlusion element 129 on the arterial access device
110 can be used to occlude an artery in the cerebral vasculature
and establish retrograde flow, as described more fully below.
Various arteries may be occluded including, for example, the common
carotid artery, internal carotid artery, and/or vertebral artery.
Exemplary embodiments of the system and its components are
described in detail below.
[0051] FIG. 3 shows the cerebral vasculature with a mechanical
thrombectomy device 15 inserted through the arterial access device
110. The thrombectomy device 15 includes an elongate catheter that
can be advanced through the arterial access device 110 to the
location of the thrombotic occlusion 10. The thrombectomy device 15
has a distal region that includes a thrombus engaging element 68
that is adapted to interact with and remove the thrombotic
occlusion 10, as described more fully below. Various embodiments of
the thrombectomy device 15 are described below.
[0052] FIG. 4 shows an alternate embodiment wherein a secondary
interventional device, such as a balloon catheter 25, is advanced
through the arterial access device 110 and into a collateral
cerebral artery such as the anterior cerebral artery ACA. The
balloon catheter 25 includes an expandable balloon 30 that can be
expanded in the collateral cerebral artery to occlude that artery.
Occlusion of the collateral cerebral artery enhances suction and
reverse flow through the cerebral vasculature, as described in
detail below.
[0053] FIG. 5A shows an exemplary embodiment of a vascular access
and reverse flow system 100 that can be used to establish
retrograde flow during removal of the thrombotic occlusion 10. The
system 100 includes the arterial access device 110, a venous return
device 115, and a shunt 120 that provides a passageway for
retrograde flow from the arterial access device 110 to the venous
return device 115. A flow control assembly 125 interacts with the
shunt 120. The flow control assembly 125 is adapted to regulate
and/or monitor the retrograde flow through the shunt 120, as
described in more detail below. The flow control assembly 125
interacts with the flow pathway through the shunt 120, either
external to the flow path, inside the flow path, or both.
[0054] In an embodiment, the arterial access device 110 at least
partially inserts into the common carotid artery CCA and the venous
return device 115 at least partially inserts into a venous return
site, such as the femoral vein or internal jugular vein, as
described in more detail below. The venous return device 115 can be
inserted into the femoral vein FV via a percutaneous puncture in
the groin. The arterial access device 110 and the venous return
device 115 couple to opposite ends of the shunt 120 at connectors.
As shown in FIG. 5B, the distal end of the arterial access device
110 with the occlusion element 129 may be positioned in the ICA.
Alternately, in some circumstances where the ICA access is
extremely tortuous, it may be preferable to position the occlusion
element more proximally in the common carotid artery. When flow
through the internal carotid artery is blocked (using the occlusion
element 129), the natural pressure gradient between the internal
carotid artery and the venous system causes blood to flow in a
retrograde or reverse direction from the cerebral vasculature
through the internal carotid artery and through the shunt 120 into
the venous system. The flow control assembly 125 modulates,
augments, assists, monitors, and/or otherwise regulates the
retrograde blood flow.
[0055] The thrombectomy device 15 is deployed into the left middle
cerebral artery through the arterial access device and via the
internal carotid artery. A distal region of the thrombectomy device
15 is positioned in the middle cerebral artery in interaction with
the thrombotic occlusion. A proximal region of the thrombectomy
device 15 protrudes from an access port in the arterial access
device 110. This is described in more detail with reference to FIG.
5B, which shows an enlarged view of the common carotid artery CCA,
internal carotid artery ICA, and middle cerebral artery MCA with
the arterial access device 110 and the thrombectomy device 15
deployed. The arterial access device 110 accesses the common
carotid artery via a transcervical approach such as via a direct
cut down to the common carotid artery CCA or a percutaneous
puncture of the CCA. The thrombectomy device 15 gains access to the
internal carotid artery ICA via insertion through an internal lumen
of the arterial access device 110, such as by being inserted into a
hemostasis valve that provides access into the arterial access
device 110. As mentioned, the arterial access device 110 can
include an occlusion element 129 that occludes the internal or
common carotid artery. An exemplary manner in which the
thrombectomy device 15 removes the thrombotic occlusion is
described in detail below.
[0056] As discussed, the arterial access device 110 provides access
to the anterior and middle cerebral arteries via the common carotid
artery CCA using a transcervical approach. Transcervical access
provides a short length and non-tortuous pathway from the vascular
access point to the target treatment site thereby easing the time
and difficulty of the procedure, compared for example to a
transfemoral approach. Additionally, this access route reduces the
risk of emboli generation from navigation of diseased, angulated,
or tortuous aortic arch or common carotid artery anatomy. In
another embodiment, the arterial access device provides access to
the basilar artery BA or posterior cerebral arteries PCA via a cut
down incision to in the vertebral artery or a percutaneous puncture
of the vertebral artery.
[0057] In an embodiment, transcervical access to the common carotid
artery is achieved percutaneously via an incision or puncture in
the skin through which the arterial access device 110 is inserted.
If an incision is used, then the incision can be about 0.5 cm in
length. An occlusion element 129, such as an expandable balloon,
can be used to occlude the internal carotid artery ICA or the
common carotid artery CCA at a location proximal of the distal tip
of the arterial access device 110. The occlusion element 129 can be
located on the arterial access device 110 or it can be located on a
separate device. In an alternate embodiment, the arterial access
device 110 accesses the common carotid artery CCA via a direct
surgical transcervical approach. In the surgical approach, the
common carotid artery can be occluded using a tourniquet.
[0058] In another embodiment, the arterial access device 110
accesses the common carotid artery CCA via a transcervical approach
while the venous return device 115 access a venous return site
other than the femoral vein, such as the internal jugular vein. In
another embodiment, the system provides retrograde flow from the
carotid artery to an external receptacle rather than to a venous
return site. The arterial access device 110 connects to the
receptacle via the shunt 120, which communicates with the flow
control assembly 125. The retrograde flow of blood is collected in
the receptacle 130. If desired, the blood could be filtered and
subsequently returned to the patient. The pressure of the
receptacle 130 could be set at zero pressure (atmospheric pressure)
or even lower, causing the blood to flow in a reverse direction
from the cerebral vasculature to the receptacle 130. Optionally, to
achieve or enhance reverse flow from the internal carotid artery,
flow from the external carotid artery can be blocked, typically by
deploying a balloon or other occlusion element in the external
carotid artery just above the bifurcation with the internal carotid
artery.
[0059] In another embodiment, reverse flow may be replaced or
augmented by application of an aspiration source to a port 131
(such as a stopcock) that communicates with the flow shunt 120.
Examples of an aspiration source include a syringe, pump, or the
like. Alternately, the system may include an active pump as part of
the flow control assembly 125, with controls for pump flow rate
and/or flow monitoring included in the assembly.
[0060] In yet another embodiment, the system may be used to deliver
intra-arterial thrombolytic therapy, such as through a sidearm in
the arterial access device 110. For example, thrombolytic therapy
may be infused to the thrombotic occlusion 10 through the arterial
access device 110 via a flush line 635. In another embodiment, the
system may be used to deliver intra-arterial thrombolytic therapy
via a micro catheter which is inserted into the arterial access
device 110. The micro catheter is delivered to the site of the
thrombotic occlusion 10 to infuse a thrombolytic drug. The
thrombolytic therapy may be delivered either in conjunction with or
as an alternative to mechanical thrombectomy such as the
thrombectomy device 15.
[0061] In another embodiment, the system 100 may include a means to
perfuse the cerebral vasculature and ischemic brain tissue via a
perfusion catheter delivered, for example, through the arterial
access device 110 to a site distal to the thrombotic occlusion 10.
The perfusion catheter is adapted to deliver a perfusion solution
to a desired location. Perfusion solution may include, for example,
autologous arterial blood, either from the AV shunt 120 or from
another artery, oxygenated solution, or other neuroprotective
agents. In addition, the perfusion solution may be hypothermic to
cool the brain tissue, another strategy which has been shown to
minimize brain injury during periods of ischemia. The perfusion
catheter may also be used to deliver a bolus of an intra-arterial
thrombolytic agent pursuant to thrombolytic therapy. Typically,
thrombolytic therapy may take up to 1-2 hours or more to clear a
blockage after the bolus has been delivered. Mechanical
thrombectomy may also take up to 1 to 2 hours to successfully
recanalize the blocked artery. Distal perfusion of the ischemic
region may minimize the level of brain injury during the stroke
treatment procedure.
[0062] Another embodiment of the system 100 includes a means for
retroperfusion of the cerebral vasculature during the acute stroke
treatment procedure. Cerebral retroperfusion as described by Frazee
et al involves selective cannulation and occlusion of the
transverse sinuses via the internal jugular vein, and infusion of
blood via the superior sagittal sinus to the brain tissue, during
treatment of ischemic stroke. The following articles, which are
incorporated herein by reference in their entirety, described
cerebral retroperfusion and are incorporated by reference in their
entirety: Frazee, J. G. and X. Luo (1999). "Retrograde transvenous
perfusion." Crit Care Clin 15(4): 777-88, vii.; and Frazee, J. G.,
X. Luo, et al. (1998). "Retrograde transvenous neuroperfusion: a
back door treatment for stroke." Stroke 29(9): 1912-6. This
perfusion, in addition to providing protection to the cerebral
tissue, may also cause a retrograde flow gradient in the cerebral
arteries. Used in conjunction with the reverse flow system 100, a
retroperfusion component may provide oxygen to brain tissue, as
well as aid in capture of embolic debris into the reverse flow
shunt during recanalization of the thrombotic occlusion 10.
Exemplary Embodiments of Thrombectomy Device
[0063] FIG. 6 shows an enlarged view of a distal region of an
exemplary thrombectomy device 15 in a collapsed condition in a
blood vessel such as the left middle cerebral artery. As discussed,
the distal end of the thrombectomy device 15 is advanced to the
left middle cerebral artery and the thrombotic occlusion 10 through
the arterial access device 110. The thrombectomy device 15 may
include a microcatheter 60 to assist in delivering the device into
the distal vasculature
[0064] The thrombectomy device 15 has a thrombus engaging element
68 extending from an insertion element 69 comprised of an elongate
body. The engaging element has a coiled or substantially-coiled
configuration that engages the thrombotic occlusion as described
below. Exemplary embodiments of the engaging element are described
below although it should be appreciated that the configuration of
the engaging element 68 may vary. The engaging element 68 is
movable from a collapsed position (shown in FIG. 6) to an expanded
position (shown in FIGS. 7 and 8). When the engaging element 68 is
contained within a sheath 65 or microcatheter 60, the engaging
element 68 is in a relatively straight configuration. The engaging
element 68 has a distal portion 70 (FIG. 7), which forms a
relatively closed structure, which can catch or trap the
obstruction, or any part thereof, to prevent migration of the
obstruction or part thereof. The engaging element 68 has a proximal
portion 71 (FIG. 8) which is formed with smaller coils than the
distal portion 70. The proximal portion 71 engages the thrombotic
occlusion as described below.
[0065] The engaging element 68 may have a number of markers which
provide an indication as to how much of the engaging element 68
extends from the sheath 65 or microcatheter 60. For example,
markers may indicate when the engaging element 68 is 1/2, 3/4 or
fully exposed. In this manner, the user may quickly advance the
engaging element 68 through the sheath 65 or microcatheter 60
without inadvertently exposing and advancing the engaging element
68 out of the sheath 65 or microcatheter. The markers can also be
used to provide a controlled diameter of the engaging element 68
since the diameter of the engaging element 68 is known for the
various positions corresponding to the markers. The markers may
also be used to size the vessel in which the engaging element 68 is
positioned by observing when the engaging element 68 engages the
vessel walls and determining the size of the engaging element 68
using the markers.
[0066] The insertion element 69 can be made, for example, of a
superelastic material or stainless steel having a diameter of 0.004
to 0.038 inch and preferably about 0.010 inch. Although the
insertion element 69 can be a solid, elongate element, the
insertion element 69 may take any other suitable structure such as
a hollow tube. The engaging element 68 can be made of a
superelastic material, such as nitinol, and has a diameter of
0.005-0.018 inch, more preferably 0.005-0.010 inch and most
preferably about 0.008 inch. The engaging element 68 may have a
rounded, atraumatic tip 72 to prevent damage to the vessel and
facilitate advancement through the vessel, microcatheter 60 and/or
sheath 65. A radiopaque wire 73, such as platinum ribbon 74 having
a width of 0.004 inch and a thickness of 0.002 inch, may be wrapped
around the engaging element 68 to improve radiopacity.
[0067] The thrombectomy device 15 can be self-expanding but may
also be expanded with an actuator. The actuator can be a thin
filament which is tensioned to move the thrombectomy device 15 to
the expanded position.
[0068] The thrombectomy device 15 may also include a cover 75 which
extends between adjacent coils. The cover 75 may be a number of
individual strands which extend between the coils or may be an
elastic membrane which covers the coils. The thrombectomy device 15
may also include a flush lumen and/or an aspiration lumen.
[0069] It should be appreciated that the thrombectomy device 15 is
not limited to the specific embodiments described above and that
other embodiments of thrombectomy devices or therapeutic devices
may also be used. For example, the device may be an expandable
cage, basket, snare, or grasper which is used to capture and remove
the thrombotic blockage. The device may also be a clot disruption
device, which may be used to break up the thrombus for easier
aspiration and removal. The clot disruption device may be, for
example, a mechanical disrupter, sonic or ultrasonic energy source,
or other energy source, or a hydraulic or vortex energy source, to
break up the clot. The thrombectomy device may also comprise a
aspiration means to remove the thrombotic blockage.
[0070] Other means for providing flow through a thrombotic blockage
include recanalizing means, for example delivering a balloon
catheter and dilating a passage through the blockage, or deploying
a stent through the thrombotic blockage to create a lumen through
the blockage. A stent device may be a permanent implantable stent
or may be a temporary stent to open up the blocked passage for a
period of time before being retrieved. The blockage may be removed
by the stent or by some other thrombectomy means. Both thrombectomy
and recanalization devices may be used in conjunction with
thrombolytic infusion. Some exemplary stent-related devices and
methods are described in the following U.S. patents, which are
incorporated herein by reference in their entirety: U.S. Pat. No.
5,964,773 and U.S. Pat. No. 5,456,667.
[0071] Use of the vascular access and reverse flow system with the
thrombectomy device 15 is now described. The arterial access device
110 is introduced into the common carotid artery CCA of the patient
and positioned in the distal common carotid artery or internal
carotid artery, as shown in FIG. 5B. The thrombectomy device 15 is
then advanced through the arterial access device 110, either with
or without the microcatheter 60, into the carotid artery. Before
advancing the thrombectomy device 15 further, the occlusion element
129 on the arterial access device 110 may be expanded to reduce or
even stop antegrade flow through the vessel. Stopping flow in the
vessel may help prevent the thrombotic emboli or any parts thereof
from migrating downstream due to antegrade flow during positioning
of the thrombectomy device 15 or retrieval of the thrombus. The
thrombectomy device 15 is then advanced, either through the
microcatheter 60 or by itself within the sheath 65, further into
the vasculature to a position proximal to, within or distal to the
thrombotic occlusion 10, as shown in FIG. 7. During any part of the
procedure, reverse flow may be initiated in the vessel via a
retrograde flow system (described below) and/or via active
aspiration.
[0072] The thrombectomy device 15 is then placed into the
thrombotic occlusion 10 and possibly through the thrombotic
occlusion. The engaging element 68 is then advanced out of the
microcatheter 60 or sheath 65 to permit the distal portion 70 of
the engaging element 68 to expand at a location beyond the
thrombotic occlusion. In this manner, the relatively closed distal
portion 70 prevents the thrombotic occlusion, or any part thereof,
from migrating downstream. The proximal portion 71 is then advanced
out of the sheath 65 or microcatheter 60 so that the smaller coils
of the proximal portion 71 engage the thrombotic occlusion 10 as
shown in FIG. 8.
[0073] Referring to FIG. 9, another thrombectomy device 15A is
shown wherein the same or similar reference numbers refer to the
same or similar structure. The thrombectomy device 15A has a first
section 80 with larger diameter coils than a second section 81. A
third section 82 also has larger coils than the second section 81
with the second section 81 positioned between the first and third
sections. The thrombectomy device 15A may have a number of
alternating small and large sections which can enhance the ability
of the thrombectomy device 15A to engage various thrombotic
occlusions.
[0074] The thrombectomy device 15A may be used in any suitable
manner to engage the thrombotic occlusion. For example, the
microcatheter 60 or sheath 65 may be advanced through the
thrombotic occlusion and then retracted to expose the thrombectomy
device 15A. The thrombectomy device 15A is then retracted into the
thrombotic occlusion to engage the thrombotic occlusion. The
thrombectomy device 15A may be rotated when moved into the
thrombotic occlusion to take advantage of the generally helical
shape of the obstruction removal device. The thrombectomy device
15A may also be used to engage the thrombotic occlusion by simply
retracting the microcatheter 60 or sheath 65 with the thrombectomy
device 15A expanding within the thrombotic occlusion. Finally, the
engaging element 68A may be exposed and expanded proximal to the
thrombotic occlusion and then advanced into the thrombotic
occlusion.
[0075] When advancing the thrombectomy device 15A into the
thrombotic occlusion, the user may also twist the thrombectomy
device 15A to take advantage of the generally helical shape. The
alternating large and small sections enhance the ability of the
engaging element 68A to engage varying shapes and sizes of
thrombotic occlusion. Another method of aiding mechanical capture
of an thrombotic occlusion is to coat the device and elements of
the device with a material 77 which helps to adhere the thrombotic
occlusion, and in particular thrombus, to the device or element.
The material may be, for example, fibrin or may be any other
suitable material.
[0076] It may be appreciated that other mechanical thrombectomy
catheters may be used in a similar manner with the vascular access
and reverse flow system as described above. Mechanical thrombectomy
devices may include variations on the thrombus retrieval device
described above, such as expandable cages, wire or filament loops,
graspers, brushes, or the like. These clot retrievers may include
aspiration lumens to lower the risk of embolic debris leading to
ischemic complications. Alternately, thrombectomy devices may
include clot disruption elements such as fluid vortices, ultrasound
or laser energy elements, balloons, or the like, coupled with
flushing and aspiration to remove the thrombus. Some exemplary
devices and methods are described in the following U.S. patents and
Patent Publications, which are all incorporated by reference in
their entirety: U.S. Pat. No. 6,663,650, U.S. Pat. No. 6,730,104;
U.S. Pat. No. 6,428,531, U.S. Pat. No. 6,379,325, U.S. Pat. No.
6,481,439, U.S. Pat. No. 6,929,632, U.S. Pat. No. 5,938,645, U.S.
Pat. No. 6,824,545, U.S. Pat. No. 6,679,893, U.S. Pat. No.
6,685,722, U.S. Pat. No. 6,436,087, U.S. Pat. No. 5,794,629, U.S.
Patent Pub. No. 20080177245, U.S. Patent Pub. No. 20090299393, U.S.
Patent Pub. No. 20040133232, U.S. Patent Pub. No. 20020183783, U.S.
Patent Pub. No. 20070198028, U.S. Patent Pub. No. 20060058836, U.S.
Patent Pub. No. 20060058837, U.S. Patent Pub. No. 20060058838, U.S.
Patent Pub. No. 20060058838, U.S. Patent Pub. No. 20030212384, and
U.S. Patent Pub. No. 20020133111.
Exemplary Embodiments of Perfusion Catheter
[0077] Some exemplary embodiments of perfusion catheters are now
described. FIG. 25 shows a perfusion catheter 2510 positioned
adjacent to a thrombotic blockage B in the vasculature. FIG. 26
shows the perfusion catheter 2510 positioned across the thrombotic
blockage B, to enable perfusion distal to the blockage. In an
embodiment, the catheter is 2510 positioned over a guidewire placed
through a lumen in the catheter. The lumen may serve as both a
guidewire lumen and a perfusion lumen. Once placed, the guidewire
may be removed to maximize the throughspace of the lumen available
for perfusion. Alternately, the guidewire lumen and the perfusion
lumen may be two separate lumens within the catheter, so that the
guidewire may remain in place in the guidewire lumen during
perfusion without interfering with the perfusion lumen. Perfusion
exit holes 2515, which communicate with the perfusion lumen, are
located in a distal region of the catheter 2510. The perfusion exit
holes 2515 may be used to perfuse the vasculature distal to the
blockage B, as exhibited by the arrows P in FIG. 26, which
represent the flow of perfusion solution out of the catheter 2510.
Alternately, the catheter 2510 may be positioned relative to the
blockage B such that the perfusion exit holes 2515 are initially
positioned just proximal to, or within, the thrombotic blockage B
during a bolus of thrombolytic infusion. The catheter can then be
re-positioned so that at least some of the perfusion exit holes
2515 are located distal of the blockage B to provide distal
perfusion with blood or an equivalent solution to the ischemic
penumbra.
[0078] In a variation to this embodiment, shown in FIG. 27A, the
perfusion catheter 2510 may include an occlusion balloon 2705, with
perfusion exit holes 2515 positioned distal to, and/or proximal to
the occlusion balloon 2705. As with the previous embodiment, the
perfusion catheter 2510 may be used in conjunction with
recanalization therapies such as thrombectomy devices or
intra-arterial thrombolytic infusion. The catheter 2510 is placed
in the vasculature so that the occlusion balloon 2705 is positioned
distal to the blockage B. The catheter 2510 may be configured to
perfuse the region distal of the balloon 2705 with blood or
equivalent, and the region proximal of the balloon 2705 with
thrombolytic agents. In this regard, the catheter 2510 may include
separate perfusion lumens 2720a and 2720b that communicate with
separate perfusion exit holes, as shown in FIG. 27B. Alternately,
the distal and proximal perfusion exit holes are connected to the
same perfusion lumen 2720, and regions both distal and proximal to
the occlusion balloon are used to infuse blood or equivalent, as
shown in FIG. 27C. The proximal perfusion provides a pressure
gradient just proximal to the blockage, and causes any embolic
debris generated during recanalization of the occlusion 10 into the
reverse flow path at the terminal internal carotid artery ICA, as
shown in FIG. 27A. In addition, the proximal perfusion can supply
blood to smaller vessels (perforators) originating in or just
proximal to the occlusion.
[0079] It should be appreciated that other perfusion catheters may
be used with the system 100, for example those described by U.S.
Pat. Nos. 6,435,189 and 6,295,990, which are incorporated by
reference in their entirety.
Exemplary Embodiment of Retrograde Blood Flow System
[0080] As discussed, the system 100 includes the arterial access
device 110, venous return device 115, and shunt 120 which provides
a passageway for retrograde flow from the arterial access device
110 to the venous return device 115. The system also includes the
flow control assembly 125, which interacts with the shunt 120 to
regulate and/or monitor retrograde blood flow through the shunt
120. Exemplary embodiments of the components of the system 100 are
now described.
[0081] Arterial Access Device
[0082] FIG. 10A shows an exemplary embodiment of the arterial
access device 110, which comprises a distal sheath 605, a proximal
extension 610, a flow line 615, an adaptor or Y-connector 620, and
a hemostasis valve 625. The distal sheath 605 is adapted to be
introduced through an incision or puncture in a wall of a common
carotid artery, either an open surgical incision or a percutaneous
puncture established, for example, using the Seldinger technique.
The length of the sheath can be in the range from 5 to 15 cm,
usually being from 10 cm to 12 cm. The inner diameter is typically
in the range from 7 Fr (1 Fr=0.33 mm), to 10 Fr, usually being 8
Fr. Particularly when the sheath is being introduced through the
transcervical approach, above the clavicle but below the carotid
bifurcation, it is desirable that the sheath 605 be highly flexible
while retaining hoop strength to resist kinking and buckling. Thus,
the distal sheath 605 can be circumferentially reinforced, such as
by braid, helical ribbon, helical wire, or the like. In an
alternate embodiment, the distal sheath is adapted to be introduced
through a percutaneous puncture into the femoral artery, such as in
the groin, and up the aortic arch into the target common carotid
artery CCA.
[0083] The distal sheath 605 can have a stepped or other
configuration having a reduced diameter distal region 630, as shown
in FIG. 10B, which shows an enlarged view of the distal region 630
of the sheath 605. The distal region 630 of the sheath can be sized
for insertion into the carotid artery, typically having an inner
diameter in the range from 2.16 mm (0.085 inch) to 2.92 mm (0.115
inch) with the remaining proximal region of the sheath having
larger outside and luminal diameters, with the inner diameter
typically being in the range from 2.794 mm (0.110 inch) to 3.43 mm
(0.135 inch). The larger luminal diameter of the proximal region
minimizes the overall flow resistance of the sheath. In an
embodiment, the reduced-diameter distal section 630 has a length of
approximately 2 cm to 4 cm or 3 cm to 5 cm. In another embodiment,
the length of the reduced-diameter distal section 630 has a length
of approximately 10 cm to 15 cm. The relatively short length of the
reduced-diameter distal section 630 permits this section to be
positioned in the common carotid artery CCA via the transcervical
approach with reduced risk that the distal end of the sheath 605
will contact the bifurcation B. Moreover, the reduced diameter
section 630 also permits a reduction in size of the arteriotomy for
introducing the sheath 605 into the artery while having a minimal
impact in the level of flow resistance.
[0084] With reference again to FIG. 10A, the proximal extension 610
has an inner lumen which is contiguous with an inner lumen of the
sheath 605. The lumens can be joined by the Y-connector 620 which
also connects a lumen of the flow line 615 to the sheath. In the
assembled system, the flow line 615 connects to and forms a first
leg of the retrograde shunt 120 (FIG. 5A). The proximal extension
610 can have a length sufficient to space the hemostasis valve 625
well away from the Y-connector 620, which is adjacent to the
percutaneous or surgical insertion site. By spacing the hemostasis
valve 625 away from a percutaneous insertion site, the physician
can introduce a stent delivery system or other working catheter
into the proximal extension 610 and sheath 605 while staying out of
the fluoroscopic field when fluoroscopy is being performed.
[0085] A flush line 635 can be connected to the side of the
hemostasis valve 625 and can have a stopcock 640 at its proximal or
remote end. The flush-line 635 allows for the introduction of
saline, contrast fluid, or the like, during the procedures. The
flush line 635 can also allow pressure monitoring during the
procedure. A dilator 645 having a tapered distal end 650 can be
provided to facilitate introduction of the distal sheath 605 into
the common carotid artery. The dilator 645 can be introduced
through the hemostasis valve 625 so that the tapered distal end 650
extends through the distal end of the sheath 605, as best seen in
FIG. 11A. The dilator 645 can have a central lumen to accommodate a
guide wire. Typically, the guide wire is placed first into the
vessel, and the dilator/sheath combination travels over the guide
wire as it is being introduced into the vessel.
[0086] Optionally, a tube 705 may be provided which is coaxially
received over the exterior of the distal sheath 605, also as seen
in FIG. 11A. The tube 705 has a flared proximal end 710 which
engages the adapter 620 and a distal end 715. Optionally, the
distal end 715 may be beveled, as shown in FIG. 11B. The tube 705
may serve at least two purposes. First, the length of the tube 705
limits the introduction of the sheath 605 to the exposed distal
portion of the sheath 605, as seen in FIG. 11A. Second, the tube
705 can engage a pre-deployed puncture closure device disposed in
the carotid artery wall, if present, to permit the sheath 605 to be
withdrawn without dislodging the closure device.
[0087] The distal sheath 605 can be configured to establish a
curved transition from a generally anterior-posterior approach over
the common carotid artery to a generally axial luminal direction
within the common carotid artery. The transition in direction is
particularly useful when a percutaneous access is provided through
the common carotid wall. While an open surgical access may allow
for some distance in which to angle a straight sheath into the
lumen of the common carotid artery, percutaneous access will
generally be in a normal or perpendicular direction relative to the
access of the lumen, and in such cases, a sheath that can flex or
turn at an angle will find great use.
[0088] The sheath 605 can be formed in a variety of ways. For
example, the sheath 605 can be pre-shaped to have a curve or an
angle some set distance from the tip, typically 2 to 3 cm. The
pre-shaped curve or angle can typically provide for a turn in the
range from 20.degree. to 90.degree., preferably from 30.degree. to
70.degree.. For initial introduction, the sheath 605 can be
straightened with an obturator or other straight or shaped
instrument such as the dilator 645 placed into its lumen. After the
sheath 605 has been at least partially introduced through the
percutaneous or other arterial wall penetration, the obturator can
be withdrawn to allow the sheath 605 to reassume its pre-shaped
configuration into the arterial lumen.
[0089] Other sheath configurations include having a deflection
mechanism such that the sheath can be placed and the catheter can
be deflected in situ to the desired deployment angle. In still
other configurations, the catheter has a non-rigid configuration
when placed into the lumen of the common carotid artery. Once in
place, a pull wire or other stiffening mechanism can be deployed in
order to shape and stiffen the sheath into its desired
configuration. One particular example of such a mechanism is
commonly known as "shape-lock" mechanisms as well described in
medical and patent literature.
[0090] Another sheath configuration comprises a curved dilator
inserted into a straight but flexible sheath, so that the dilator
and sheath are curved during insertion. The sheath is flexible
enough to conform to the anatomy after dilator removal.
[0091] In an embodiment, the sheath has built-in puncturing
capability and atraumatic tip analogous to a guide wire tip. This
eliminates the need for needle and wire exchange currently used for
arterial access according to the micropuncture technique, and can
thus save time, reduce blood loss, and require less surgeon
skill.
[0092] FIG. 12A shows another embodiment of the arterial access
device 110. This embodiment is substantially the same as the
embodiment shown in FIG. 10A, except that the distal sheath 605
includes an occlusion element 129 for occluding flow through, for
example the common carotid artery. If the occluding element 129 is
an inflatable structure such as a balloon or the like, the sheath
605 can include an inflation lumen that communicates with the
occlusion element 129. The occlusion element 129 can be an
inflatable balloon, but it could also be an inflatable cuff, a
conical or other circumferential element which flares outwardly to
engage the interior wall of the common or internal carotid artery
to block flow therepast, a membrane-covered braid, a slotted tube
that radially enlarges when axially compressed, or similar
structure which can be deployed by mechanical means, or the like.
In the case of balloon occlusion, the balloon can be compliant,
non-compliant, elastomeric, reinforced, or have a variety of other
characteristics. In an embodiment, the balloon is an elastomeric
balloon which is closely received over the exterior of the distal
end of the sheath prior to inflation. When inflated, the
elastomeric balloon can expand and conform to the inner wall of the
common carotid artery. In an embodiment, the elastomeric balloon is
able to expand to a diameter at least twice that of the
non-deployed configuration, frequently being able to be deployed to
a diameter at least three times that of the undeployed
configuration, more preferably being at least four times that of
the undeployed configuration, or larger.
[0093] As shown in FIG. 12B, the distal sheath 605 with the
occlusion element 129 can have a stepped or other configuration
having a reduced diameter distal region 630. The distal region 630
can be sized for insertion into the carotid artery with the
remaining proximal region of the sheath 605 having larger outside
and luminal diameters, with the inner diameter typically being in
the range from 2.794 mm (0.110 inch) to 3.43 mm (0.135 inch). The
larger luminal diameter of the proximal region minimizes the
overall flow resistance of the sheath. In an embodiment, the
reduced-diameter distal section 630 has a length of approximately 2
cm to 4 cm or 3 cm to 5 cm. In another embodiment, the length of
the reduced-diameter distal section 630 has a length of
approximately 10 cm to 15 cm. The relatively short length of the
reduced-diameter distal section 630 permits this section to be
positioned in the common carotid artery CCA via the transcervical
approach with reduced risk that the distal end of the sheath 605
will contact the bifurcation B. In an alternate embodiment, shown
in FIG. 28, the reduced diameter distal section 630 is tapered or
stepped and has a length of approximately 10 cm to 15 cm, such that
the distal tip can be positioned in the internal carotid artery
ICA.
[0094] In another embodiment, shown in FIG. 29, the arterial access
device 110 is introduced into an incision in the common carotid
artery CCA via a transcervical approach, and is used to introduce a
separate sub-selective sheath 2805 into the internal carotid artery
ICA. The sub-selective sheath 2805 can be smaller in diameter and
more flexible than the access sheath 605 of the arterial access
device 110, to allow catheterization of the more distal and
potentially more tortuous vessel. The sub-selective sheath 2805 may
be co-axial with the access sheath 605, with a reduced diameter
that allows introduction through the access sheath 605.
Alternately, as shown in FIG. 30, the sub-selective sheath 2805 may
be constructed in a telescoping manner with the access sheath 605
to extend the lumen of the access sheath 605. In this
configuration, the sub-selective sheath 2805 takes up minimal
luminal area in the access sheath 605, thus optimizing the reverse
flow rate. In either configuration, the occlusion element 129 is
located on the distal end of the subselective sheath 2805 rather
than on the access sheath 605.
[0095] Venous Return Device
[0096] Referring now to FIG. 13, the venous return device 115 can
comprise a distal sheath 910 and a flow line 915, which connects to
and forms a leg of the shunt 120 when the system is in use. The
distal sheath 910 is adapted to be introduced through an incision
or puncture into a venous return location, such as the jugular vein
or femoral vein. The distal sheath 910 and flow line 915 can be
permanently affixed, or can be attached using a conventional luer
fitting, as shown in FIG. 13. Optionally, as shown in FIG. 14, the
sheath 910 can be joined to the flow line 915 by a Y-connector
1005. The Y-connector 1005 can include a hemostasis valve 1010,
permitting insertion of a dilator 1015 to facilitate introduction
of the venous return device into the internal jugular vein or other
vein. As with the arterial access dilator 645, the venous dilator
1015 includes a central guide wire lumen so the venous sheath and
dilator combination can be placed over a guide wire. Optionally,
the venous sheath 910 can include a flush line 1020 with a stopcock
1025 at its proximal or remote end.
[0097] In order to reduce the overall system flow resistance, the
arterial access flow line 615 and Y-connector 620 (FIG. 10A) and
the venous return flow line 915, and Y-connectors 1005 (FIG. 13 or
14), can each have a relatively large flow lumen inner diameter,
typically being in the range from 2.54 mm (0.100 inch) to 5.08 mm
(0.200 inch), and a relatively short length, typically being in the
range from 10 cm to 20 cm. The low system flow resistance is
desirable since it permits the flow to be maximized during portions
of a procedure when the risk of emboli is at its greatest. The low
system flow resistance also allows the use of a variable flow
resistance for controlling flow in the system, as described in more
detail below. The dimensions of the venous return sheath 910 can be
generally the same as those described for the arterial access
sheath 605 above. In the venous return sheath, an extension for the
hemostasis valve 1010 is not required.
[0098] Retrograde Shunt
[0099] The shunt 120 can be formed of a single tube or multiple,
connected tubes that provide fluid communication between the
arterial access catheter 110 and the venous return catheter 115 to
provide a pathway for retrograde blood flow therebetween. As shown
in FIG. 5A, the shunt 120 connects at one end to the flow line 615
of the arterial access device 110, and at an opposite end to the
flow line 915 of the venous return catheter 115.
[0100] In an embodiment, the shunt 120 can be formed of at least
one tube that communicates with the flow control assembly 125. The
shunt 120 can be any structure that provides a fluid pathway for
blood flow. The shunt 120 can have a single lumen or it can have
multiple lumens. The shunt 120 can be removably attached to the
flow control assembly 125, arterial access device 110, and/or
venous return device 115. Prior to use, the user can select a shunt
120 with a length that is most appropriate for use with the
arterial access location and venous return location. In an
embodiment, the shunt 120 can include one or more extension tubes
that can be used to vary the length of the shunt 120. The extension
tubes can be modularly attached to the shunt 120 to achieve a
desired length. The modular aspect of the shunt 120 permits the
user to lengthen the shunt 120 as needed depending on the site of
venous return. For example, in some patients, the internal jugular
vein IJV is small and/or tortuous. The risk of complications at
this site may be higher than at some other locations, due to
proximity to other anatomic structures. In addition, hematoma in
the neck may lead to airway obstruction and/or cerebral vascular
complications. Consequently, for such patients it may be desirable
to locate the venous return site at a location other than the
internal jugular vein IJV, such as the femoral vein. A femoral vein
return site may be accomplished percutaneously, with lower risk of
serious complication, and also offers an alternative venous access
to the central vein if the internal jugular vein IJV is not
available. Furthermore, the femoral venous return changes the
layout of the reverse flow shunt such that the shunt controls may
be located closer to the "working area" of the intervention, where
the devices are being introduced and the contrast injection port is
located.
[0101] In an embodiment, the shunt 120 has an internal diameter of
4.76 mm ( 3/16 inch) and has a length of 40-70 cm. As mentioned,
the length of the shunt can be adjusted.
[0102] In an embodiment, the shunt may contain a port which can be
connected to an aspiration source such as a syringe, suction pump,
or the like.
[0103] In an additional embodiment, the shunt may contain an
element that connects to an active pump, for example a peristaltic
pump, a diaphragm pump, an impeller pump, or a syringe pump.
[0104] Flow Control Assembly--Regulation and Monitoring of
Retrograde Flow
[0105] The flow control assembly 125 interacts with the retrograde
shunt 120 to regulate and/or monitor the retrograde flow rate from
the common carotid artery to the venous return site, such as the
internal jugular vein, or to the external receptacle. In this
regard, the flow control assembly 125 enables the user to achieve
higher maximum flow rates than existing systems and to also
selectively adjust, set, or otherwise modulate the retrograde flow
rate. Various mechanisms can be used to regulate the retrograde
flow rate, as described more fully below. The flow control assembly
125 enables the user to configure retrograde blood flow in a manner
that is suited for various treatment regimens, as described
below.
[0106] In general, the ability to control the continuous retrograde
flow rate allows the physician to adjust the protocol for
individual patients and stages of the procedure. The retrograde
blood flow rate will typically be controlled over a range from a
low rate to a high rate. The high rate can be at least two fold
higher than the low rate, typically being at least three fold
higher than the low rate, and often being at least five fold higher
than the low rate, or even higher. In an embodiment, the high rate
is at least three fold higher than the low rate and in another
embodiment the high rate is at least six fold higher than the low
rate. While it is generally desirable to have a high retrograde
blood flow rate to maximize the extraction of emboli from the
carotid arteries, the ability of patients to tolerate retrograde
blood flow will vary. Thus, by having a system and protocol which
allows the retrograde blood flow rate to be easily modulated, the
treating physician can determine when the flow rate exceeds the
tolerable level for that patient and set the reverse flow rate
accordingly. For patients who cannot tolerate continuous high
reverse flow rates, the physician can chose to turn on high flow
only for brief, critical portions of the procedure when the risk of
embolic debris is highest. At short intervals, for example between
15 seconds and 1 minute, patient tolerance limitations are usually
not a factor.
[0107] In specific embodiments, the continuous retrograde blood
flow rate can be controlled at a base line flow rate in the range
from 10 ml/min to 200 ml/min, typically from 20 ml/min to 100
ml/min. These flow rates will be tolerable to the majority of
patients. Although flow rate is maintained at the base line flow
rate during most of the procedure, at times when the risk of emboli
release is increased, the flow rate can be increased above the base
line for a short duration in order to improve the ability to
capture such emboli. For example, the retrograde blood flow rate
can be increased above the base line when the stent catheter is
being introduced, when the stent is being deployed, pre- and
post-dilatation of the stent, removal of the common carotid artery
occlusion, and the like.
[0108] The flow rate control system can be cycled between a
relatively low flow rate and a relatively high flow rate in order
to "flush" the carotid arteries in the region of the carotid
bifurcation prior to reestablishing antegrade flow. Such cycling
can be established with a high flow rate which can be approximately
two to six fold greater than the low flow rate, typically being
about three fold greater. The cycles can typically have a length in
the range from 0.5 seconds to 10 seconds, usually from 2 seconds to
5 seconds, with the total duration of the cycling being in the
range from 5 seconds to 60 seconds, usually from 10 seconds to 30
seconds.
[0109] FIG. 15 shows an example of the system 100 with a schematic
representation of the flow control assembly 125, which is
positioned along the shunt 120 such that retrograde blood flow
passes through or otherwise communicates with at least a portion of
the flow control assembly 125. The flow control assembly 125 can
include various controllable mechanisms for regulating and/or
monitoring retrograde flow. The mechanisms can include various
means of controlling the retrograde flow, including one or more
pumps 1110, valves 1115, syringes 1120 and/or a variable resistance
component 1125. The flow control assembly 125 can be manually
controlled by a user and/or automatically controlled via a
controller 1130 to vary the flow through the shunt 120. For
example, varying the flow resistance, the rate of retrograde blood
flow through the shunt 120 can be controlled. The controller 1130,
which is described in more detail below, can be integrated into the
flow control assembly 125 or it can be a separate component that
communicates with the components of the flow control assembly
125.
[0110] In addition, the flow control assembly 125 can include one
or more flow sensors 1135 and/or anatomical data sensors 1140
(described in detail below) for sensing one or more aspects of the
retrograde flow. A filter 1145 can be positioned along the shunt
120 for removing emboli before the blood is returned to the venous
return site. When the filter 1145 is positioned upstream of the
controller 1130, the filter 1145 can prevent emboli from entering
the controller 1145 and potentially clogging the variable flow
resistance component 1125. It should be appreciated that the
various components of the flow control assembly 125 (including the
pump 1110, valves 1115, syringes 1120, variable resistance
component 1125, sensors 1135/1140, and filter 1145) can be
positioned at various locations along the shunt 120 and at various
upstream or downstream locations relative to one another. The
components of the flow control assembly 125 are not limited to the
locations shown in FIG. 15. Moreover, the flow control assembly 125
does not necessarily include all of the components but can rather
include various sub-combinations of the components. For example, a
syringe could optionally be used within the flow control assembly
125 for purposes of regulating flow or it could be used outside of
the assembly for purposes other than flow regulation, such as to
introduce fluid such as radiopaque contrast into the artery in an
antegrade direction via the shunt 120.
[0111] Both the variable resistance component 1125 and the pump
1110 can be coupled to the shunt 120 to control the retrograde flow
rate. The variable resistance component 1125 controls the flow
resistance, while the pump 1110 provides for positive displacement
of the blood through the shunt 120. Thus, the pump can be activated
to drive the retrograde flow rather than relying on the perfusion
stump pressures of the ECA and ICA and the venous back pressure to
drive the retrograde flow. The pump 1110 can be a peristaltic tube
pump or any type of pump including a positive displacement pump.
The pump 1110 can be activated and deactivated (either manually or
automatically via the controller 1130) to selectively achieve blood
displacement through the shunt 120 and to control the flow rate
through the shunt 120. Displacement of the blood through the shunt
120 can also be achieved in other manners including using the
aspiration syringe 1120, or a suction source such as a vacutainer,
vaculock syringe, or wall suction may be used. The pump 1110 can
communicate with the controller 1130.
[0112] One or more flow control valves 1115 can be positioned along
the pathway of the shunt. The valve(s) can be manually actuated or
automatically actuated (via the controller 1130). The flow control
valves 1115 can be, for example one-way valves to prevent flow in
the antegrade direction in the shunt 120, check valves, or high
pressure valves which would close off the shunt 120, for example
during high-pressure contrast injections (which are intended to
enter the arterial vasculature in an antegrade direction).
[0113] The controller 1130 communicates with components of the
system 100 including the flow control assembly 125 to enable manual
and/or automatic regulation and/or monitoring of the retrograde
flow through the components of the system 100 (including, for
example, the shunt 120, the arterial access device 110, the venous
return device 115 and the flow control assembly 125). For example,
a user can actuate one or more actuators on the controller 1130 to
manually control the components of the flow control assembly 125.
Manual controls can include switches or dials or similar components
located directly on the controller 1130 or components located
remote from the controller 1130 such as a foot pedal or similar
device. The controller 1130 can also automatically control the
components of the system 100 without requiring input from the user.
In an embodiment, the user can program software in the controller
1130 to enable such automatic control. The controller 1130 can
control actuation of the mechanical portions of the flow control
assembly 125. The controller 1130 can include circuitry or
programming that interprets signals generated by sensors 1135/1140
such that the controller 1130 can control actuation of the flow
control assembly 125 in response to such signals generated by the
sensors.
[0114] The flow control assembly 125 may also include an active
pump actuator which interfaces with an element in the shunt to
enable active retrograde pumping of blood, such as a pump head for
a roller pump, a rotary motor for an impeller-style pump, or the
like. The controller 1130 would provide controls for the pump
rate.
[0115] The representation of the controller 1130 in FIG. 15 is
merely exemplary. It should be appreciated that the controller 1130
can vary in appearance and structure. The controller 1130 is shown
in FIG. 15 as being integrated in a single housing. This permits
the user to control the flow control assembly 125 from a single
location. It should be appreciated that any of the components of
the controller 1130 can be separated into separate housings.
Further, FIG. 15 shows the controller 1130 and flow control
assembly 125 as separate housings. It should be appreciated that
the controller 1130 and flow control regulator 125 can be
integrated into a single housing or can be divided into multiple
housings or components.
[0116] Flow State Indicator(s)
[0117] The controller 1130 can include one or more indicators that
provides a visual and/or audio signal to the user regarding the
state of the retrograde flow. An audio indication advantageously
reminds the user of a flow state without requiring the user to
visually check the flow controller 1130. The indicator(s) can
include a speaker 1150 and/or a light 1155 or any other means for
communicating the state of retrograde flow to the user. The
controller 1130 can communicate with one or more sensors of the
system to control activation of the indicator. Or, activation of
the indicator can be tied directly to the user actuating one of the
flow control actuators 1165. The indicator need not be a speaker or
a light. The indicator could simply be a button or switch that
visually indicates the state of the retrograde flow. For example,
the button being in a certain state (such as a pressed or down
state) may be a visual indication that the retrograde flow is in a
high state. Or, a switch or dial pointing toward a particular
labeled flow state may be a visual indication that the retrograde
flow is in the labeled state.
[0118] The indicator can provide a signal indicative of one or more
states of the retrograde flow. In an embodiment, the indicator
identifies only two discrete states: a state of "high" flow rate
and a state of "low" flow rate. In another embodiment, the
indicator identifies more than two flow rates, including a "high"
flow rate, a "medium" flow rate, and a "low" rate. The indicator
can be configured to identify any quantity of discrete states of
the retrograde flow or it can identify a graduated signal that
corresponds to the state of the retrograde flow. In this regard,
the indicator can be a digital or analog meter 1160 that indicates
a value of the retrograde flow rate, such as in ml/min or any other
units.
[0119] In an embodiment, the indicator is configured to indicate to
the user whether the retrograde flow rate is in a state of "high"
flow rate or a "low" flow rate. For example, the indicator may
illuminate in a first manner (e.g., level of brightness) and/or
emit a first audio signal when the flow rate is high and then
change to a second manner of illumination and/or emit a second
audio signal when the flow rate is low. Or, the indicator may
illuminate and/or emit an audio signal only when the flow rate is
high, or only when the flow rate is low. Given that some patients
may be intolerant of a high flow rate or intolerant of a high flow
rate beyond an extended period of time, it can be desirable that
the indicator provide notification to the user when the flow rate
is in the high state. This would serve as a fail safe feature.
[0120] In another embodiment, the indicator provides a signal
(audio and/or visual) when the flow rate changes state, such as
when the flow rate changes from high to low and/or vice-versa. In
another embodiment, the indicator provides a signal when no
retrograde flow is present, such as when the shunt 120 is blocked
or one of the stopcocks in the shunt 120 is closed.
[0121] Flow Rate Actuators
[0122] The controller 1130 can include one or more actuators that
the user can press, switch, manipulate, or otherwise actuate to
regulate the retrograde flow rate and/or to monitor the flow rate.
For example, the controller 1130 can include a flow control
actuator 1165 (such as one or more buttons, knobs, dials, switches,
etc.) that the user can actuate to cause the controller to
selectively vary an aspect of the reverse flow. For example, in the
illustrated embodiment, the flow control actuator 1165 is a knob
that can be turned to various discrete positions each of which
corresponds to the controller 1130 causing the system 100 to
achieve a particular retrograde flow state. The states include, for
example, (a) OFF; (b) LO-FLOW; (c) HI-FLOW; and (d) ASPIRATE. It
should be appreciated that the foregoing states are merely
exemplary and that different states or combinations of states can
be used. The controller 1130 achieves the various retrograde flow
states by interacting with one or more components of the system,
including the sensor(s), valve(s), variable resistance component,
and/or pump(s). It should be appreciated that the controller 1130
can also include circuitry and software that regulates the
retrograde flow rate and/or monitors the flow rate such that the
user wouldn't need to actively actuate the controller 1130.
[0123] The OFF state corresponds to a state where there is no
retrograde blood flow through the shunt 120. When the user sets the
flow control actuator 1165 to OFF, the controller 1130 causes the
retrograde flow to cease, such as by shutting off valves or closing
a stop cock in the shunt 120. The LO-FLOW and HI-FLOW states
correspond to a low retrograde flow rate and a high retrograde flow
rate, respectively. When the user sets the flow control actuator
1165 to LO-FLOW or HI-FLOW, the controller 1130 interacts with
components of the flow control regulator 125 including pump(s)
1110, valve(s) 1115 and/or variable resistance component 1125 to
increase or decrease the flow rate accordingly. Finally, the
ASPIRATE state corresponds to opening the circuit to a suction
source, for example a vacutainer or suction unit, if active
retrograde flow is desired. The suction source can be coupled to
any portion of the circuit, including the shunt 120 or the arterial
access device 110.
[0124] The system can be used to vary the blood flow between
various states including an active state, a passive state, an
aspiration state, and an off state. The active state corresponds to
the system using a means that actively drives retrograde blood
flow. Such active means can include, for example, a pump, syringe,
vacuum source, etc. The passive state corresponds to when
retrograde blood flow is driven by the perfusion stump pressures of
the ECA and ICA and possibly the venous pressure. The aspiration
state corresponds to the system using a suction source, for example
a vacutainer or suction unit, to drive retrograde blood flow. The
off state corresponds to the system having zero retrograde blood
flow such as the result of closing a stopcock or valve. The low and
high flow rates can be either passive or active flow states. In an
embodiment, the particular value (such as in ml/min) of either the
low flow rate and/or the high flow rate can be predetermined and/or
pre-programmed into the controller such that the user does not
actually set or input the value. Rather, the user simply selects
"high flow" and/or "low flow" (such as by pressing an actuator such
as a button on the controller 1130) and the controller 1130
interacts with one or more of the components of the flow control
assembly 125 to cause the flow rate to achieve the predetermined
high or low flow rate value. In another embodiment, the user sets
or inputs a value for low flow rate and/or high flow rate such as
into the controller. In another embodiment, the low flow rate
and/or high flow rate is not actually set. Rather, external data
(such as data from the anatomical data sensor 1140) is used as the
basis for affects the flow rate.
[0125] The flow control actuator 1165 can be multiple actuators,
for example one actuator, such as a button or switch, to switch
state from LO-FLOW to HI-FLOW and another to close the flow loop to
OFF, for example during a contrast injection where the contrast is
directed antegrade into the carotid artery. In an embodiment, the
flow control actuator 1165 can include multiple actuators. For
example, one actuator can be operated to switch flow rate from low
to high, another actuator can be operated to temporarily stop flow,
and a third actuator (such as a stopcock) can be operated for
aspiration using a syringe. In another example, one actuator is
operated to switch to LO-FLOW and another actuator is operated to
switch to HI-FLOW. Or, the flow control actuator 1165 can include
multiple actuators to switch states from LO-FLOW to HI-FLOW and
additional actuators for fine-tuning flow rate within the high flow
state and low flow state. Upon switching between LO-FLOW and
HI-FLOW, these additional actuators can be used to fine-tune the
flow rates within those states. Thus, it should be appreciated that
within each state (i.e. high flow state and low flow states) a
variety of flow rates can be dialed in and fine-tuned. A wide
variety of actuators can be used to achieve control over the state
of flow.
[0126] The controller 1130 or individual components of the
controller 1130 can be located at various positions relative to the
patient and/or relative to the other components of the system 100.
For example, the flow control actuator 1165 can be located near the
hemostasis valve where any interventional tools are introduced into
the patient in order to facilitate access to the flow control
actuator 1165 during introduction of the tools. The location may
vary, for example, based on whether a transfemoral or a
transcervical approach is used. The controller 1130 can have a
wireless connection to the remainder of the system 100 and/or a
wired connection of adjustable length to permit remote control of
the system 100. The controller 1130 can have a wireless connection
with the flow control regulator 125 and/or a wired connection of
adjustable length to permit remote control of the flow control
regulator 125. The controller 1130 can also be integrated in the
flow control regulator 125. Where the controller 1130 is
mechanically connected to the components of the flow control
assembly 125, a tether with mechanical actuation capabilities can
connect the controller 1130 to one or more of the components. In an
embodiment, the controller 1130 can be positioned a sufficient
distance from the system 100 to permit positioning the controller
1130 outside of a radiation field when fluoroscopy is in use.
[0127] The controller 1130 and any of its components can interact
with other components of the system (such as the pump(s),
sensor(s), shunt, etc) in various manners. For example, any of a
variety of mechanical connections can be used to enable
communication between the controller 1130 and the system
components. Alternately, the controller 1130 can communicate
electronically or magnetically with the system components.
Electro-mechanical connections can also be used. The controller
1130 can be equipped with control software that enables the
controller to implement control functions with the system
components. The controller itself can be a mechanical, electrical
or electro-mechanical device. The controller can be mechanically,
pneumatically, or hydraulically actuated or electromechanically
actuated (for example in the case of solenoid actuation of flow
control state). The controller 1130 can include a computer,
computer processor, and memory, as well as data storage
capabilities.
[0128] Sensor(s)
[0129] As mentioned, the flow control assembly 125 can include or
interact with one or more sensors, which communicate with the
system 100 and/or communicate with the patient's anatomy. Each of
the sensors can be adapted to respond to a physical stimulus
(including, for example, heat, light, sound, pressure, magnetism,
motion, etc.) and to transmit a resulting signal for measurement or
display or for operating the controller 1130. In an embodiment, the
flow sensor 1135 interacts with the shunt 120 to sense an aspect of
the flow through the shunt 120, such as flow velocity or volumetric
rate of blood flow. The flow sensor 1135 could be directly coupled
to a display that directly displays the value of the volumetric
flow rate or the flow velocity. Or the flow sensor 1135 could feed
data to the controller 1130 for display of the volumetric flow rate
or the flow velocity.
[0130] The type of flow sensor 1135 can vary. The flow sensor 1135
can be a mechanical device, such as a paddle wheel, flapper valve,
rolling ball, or any mechanical component that responds to the flow
through the shunt 120. Movement of the mechanical device in
response to flow through the shunt 120 can serve as a visual
indication of fluid flow and can also be calibrated to a scale as a
visual indication of fluid flow rate. The mechanical device can be
coupled to an electrical component. For example, a paddle wheel can
be positioned in the shunt 120 such that fluid flow causes the
paddle wheel to rotate, with greater rate of fluid flow causing a
greater speed of rotation of the paddle wheel. The paddle wheel can
be coupled magnetically to a Hall-effect sensor to detect the speed
of rotation, which is indicative of the fluid flow rate through the
shunt 120.
[0131] In an embodiment, the flow sensor 1135 is an ultrasonic or
electromagnetic flow meter, which allows for blood flow measurement
without contacting the blood through the wall of the shunt 120. An
ultrasonic or electromagnetic flow meter can be configured such
that it does not have to contact the internal lumen of the shunt
120. In an embodiment, the flow sensor 1135 at least partially
includes a Doppler flow meter, such as a Transonic flow meter, that
measures fluid flow through the shunt 120. It should be appreciated
that any of a wide variety of sensor types can be used including an
ultrasound flow meter and transducer. Moreover, the system can
include multiple sensors.
[0132] The system 100 is not limited to using a flow sensor 1135
that is positioned in the shunt 120 or a sensor that interacts with
the venous return device 115 or the arterial access device 110. For
example, an anatomical data sensor 1140 can communicate with or
otherwise interact with the patient's anatomy such as the patient's
neurological anatomy. In this manner, the anatomical data sensor
1140 can sense a measurable anatomical aspect that is directly or
indirectly related to the rate of retrograde flow from the carotid
artery. For example, the anatomical data sensor 1140 can measure
blood flow conditions in the brain, for example the flow velocity
in the middle cerebral artery, and communicate such conditions to a
display and/or to the controller 1130 for adjustment of the
retrograde flow rate based on predetermined criteria. In an
embodiment, the anatomical data sensor 1140 comprises a
transcranial Doppler ultrasonography (TCD), which is an ultrasound
test that uses reflected sound waves to evaluate blood as it flows
through the brain. Use of TCD results in a TCD signal that can be
communicated to the controller 1130 for controlling the retrograde
flow rate to achieve or maintain a desired TCD profile. The
anatomical data sensor 1140 can be based on any physiological
measurement, including reverse flow rate, blood flow through the
middle cerebral artery, TCD signals of embolic particles, or other
neuromonitoring signals.
[0133] In an embodiment, the system 100 comprises a closed-loop
control system. In the closed-loop control system, one or more of
the sensors (such as the flow sensor 1135 or the anatomical data
sensor 1140) senses or monitors a predetermined aspect of the
system 100 or the anatomy (such as, for example, reverse flow rate
and/or neuromonitoring signal). The sensor(s) feed relevant data to
the controller 1130, which continuously adjusts an aspect of the
system as necessary to maintain a desired retrograde flow rate. The
sensors communicate feedback on how the system 100 is operating to
the controller 1130 so that the controller 1130 can translate that
data and actuate the components of the flow control regulator 125
to dynamically compensate for disturbances to the retrograde flow
rate. For example, the controller 1130 may include software that
causes the controller 1130 to signal the components of the flow
control assembly 125 to adjust the flow rate such that the flow
rate is maintained at a constant state despite differing blood
pressures from the patient. In this embodiment, the system 100 need
not rely on the user to determine when, how long, and/or what value
to set the reverse flow rate in either a high or low state. Rather,
software in the controller 1130 can govern such factors. In the
closed loop system, the controller 1130 can control the components
of the flow control assembly 125 to establish the level or state of
retrograde flow (either analog level or discreet state such as
high, low, baseline, medium, etc.) based on the retrograde flow
rate sensed by the sensor 1135.
[0134] In an embodiment, the anatomical data sensor 1140 (which
measures a physiologic measurement in the patient) communicates a
signal to the controller 1130, which adjusts the flow rate based on
the signal. For example the physiological measurement may be based
on flow velocity through the MCA, TCD signal, or some other
cerebral vascular signal. In the case of the TCD signal, TCD may be
used to monitor cerebral flow changes and to detect microemboli.
The controller 1130 may adjust the flow rate to maintain the TCD
signal within a desired profile. For example, the TCD signal may
indicate the presence of microemboli ("TCD hits") and the
controller 1130 can adjust the retrograde flow rate to maintain the
TCD hits below a threshold value of hits. (See, Ribo, et al.,
"Transcranial Doppler Monitoring of Transcervical Carotid Stenting
with Flow Reversal Protection: A Novel Carotid Revascularization
Technique", Stroke 2006, 37, 2846-2849; Shekel, et al., "Experience
of 500 Cases of Neurophysiological Monitoring in Carotid
Endarterectomy", Acta Neurochir, 2007, 149:681-689, which are
incorporated by reference in their entirety.
[0135] In the case of the MCA flow, the controller 1130 can set the
retrograde flow rate at the "maximum" flow rate that is tolerated
by the patient, as assessed by perfusion to the brain. The
controller 1130 can thus control the reverse flow rate to optimize
the level of protection for the patient without relying on the user
to intercede. In another embodiment, the feedback is based on a
state of the devices in the system 100 or the interventional tools
being used. For example, a sensor may notify the controller 1130
when the system 100 is in a high risk state, such as when an
interventional catheter is positioned in the sheath 605. The
controller 1130 then adjusts the flow rate to compensate for such a
state.
[0136] The controller 1130 can be used to selectively augment the
retrograde flow in a variety of manners. For example, it has been
observed that greater reverse flow rates may cause a resultant
greater drop in blood flow to the brain, most importantly the
ipsilateral MCA, which may not be compensated enough with
collateral flow from the Circle of Willis. Thus a higher reverse
flow rate for an extended period of time may lead to conditions
where the patient's brain is not getting enough blood flow, leading
to patient intolerance as exhibited by neurologic symptoms. Studies
show that MCA blood velocity less than 10 cm/sec is a threshold
value below which patient is at risk for neurological blood
deficit. There are other markers for monitoring adequate perfusion
to the brains, such as EEG signals. However, a high flow rate may
be tolerated even up to a complete stoppage of MCA flow for a short
period, up to about 15 seconds to 1 minute.
[0137] Thus, the controller 1130 can optimize embolic debris
capture by automatically increasing the reverse flow only during
limited time periods which correspond to periods of heightened risk
of emboli generation during a procedure. These periods of
heightened risk include the period of time while an interventional
device (such as the thrombectomy device 15) crosses the thrombotic
occlusion 10. During lower risk periods, the controller can cause
the reverse flow rate to revert to a lower, baseline level. This
lower level may correspond to a low reverse flow rate in the ICA,
or even slight antegrade flow in those patients with a high ECA to
ICA perfusion pressure ratio.
[0138] In a flow regulation system where the user manually sets the
state of flow, there is risk that the user may not pay attention to
the state of retrograde flow (high or low) and accidentally keep
the circuit on high flow. This may then lead to adverse patient
reactions. In an embodiment, as a safety mechanism, the default
flow rate is the low flow rate. This serves as a fail safe measure
for patient's that are intolerant of a high flow rate. In this
regard, the controller 1130 can be biased toward the default rate
such that the controller causes the system to revert to the low
flow rate after passage of a predetermined period of time of high
flow rate. The bias toward low flow rate can be achieved via
electronics or software, or it can be achieved using mechanical
components, or a combination thereof. In an embodiment, the flow
control actuator 1165 of the controller 1130 and/or valve(s) 1115
and/or pump(s) 1110 of the flow control regulator 125 are spring
loaded toward a state that achieves a low flow rate. The controller
1130 is configured such that the user may over-ride the controller
1130 such as to manually cause the system to revert to a state of
low flow rate if desired.
[0139] In another safety mechanism, the controller 1130 includes a
timer 1170 (FIG. 15) that keeps time with respect to how long the
flow rate has been at a high flow rate. The controller 1130 can be
programmed to automatically cause the system 100 to revert to a low
flow rate after a predetermined time period of high flow rate, for
example after 15, 30, or 60 seconds or more of high flow rate.
After the controller reverts to the low flow rate, the user can
initiate another predetermined period of high flow rate as desired.
Moreover, the user can override the controller 1130 to cause the
system 100 to move to the low flow rate (or high flow rate) as
desired.
[0140] In an exemplary procedure, embolic debris capture is
optimized while not causing patient tolerance issues by initially
setting the level of retrograde flow at a low rate, and then
switching to a high rate for discreet periods of time during
critical stages in the procedure. Alternately, the flow rate is
initially set at a high rate, and then verifying patient tolerance
to that level before proceeding with the rest of the procedure. If
the patient shows signs of intolerance, the retrograde flow rate is
lowered. Patient tolerance may be determined automatically by the
controller based on feedback from the anatomical data sensor 1140
or it may be determined by a user based on patient observation. The
adjustments to the retrograde flow rate may be performed
automatically by the controller or manually by the user.
Alternately, the user may monitor the flow velocity through the
middle cerebral artery (MCA), for example using TCD, and then to
set the maximum level of reverse flow which keeps the MCA flow
velocity above the threshold level. In this situation, the entire
procedure may be done without modifying the state of flow.
Adjustments may be made as needed if the MCA flow velocity changes
during the course of the procedure, or the patient exhibits
neurologic symptoms.
[0141] Exemplary Mechanisms to Regulate Flow
[0142] The system 100 is adapted to regulate retrograde flow in a
variety of manners. Any combination of the pump 1110, valve 1115,
syringe 1120, and/or variable resistance component 1125 can be
manually controlled by the user or automatically controlled via the
controller 1130 to adjust the retrograde flow rate. Thus, the
system 100 can regulate retrograde flow in various manners,
including controlling an active flow component (e.g., pump,
syringe, etc.), reducing the flow restriction, switching to an
aspiration source (such as a pre-set VacLock syringe, Vacutainer,
suction system, or the like), or any combination thereof.
[0143] In the situation where an external receptacle or reservoir
is used, the retrograde flow may be augmented in various manners.
The reservoir has a head height comprised of the height of the
blood inside the reservoir and the height of the reservoir with
respect to the patient. Reverse flow into the reservoir may be
modulated by setting the reservoir height to increase or decrease
the amount of pressure gradient from the CCA to the reservoir. In
an embodiment, the reservoir is raised to increase the reservoir
pressure to a pressure that is greater than venous pressure. Or,
the reservoir can be positioned below the patient, such as down to
a level of the floor, to lower the reservoir pressure to a pressure
below venous or atmospheric pressure.
[0144] The variable flow resistance in shunt 120 may be provided in
a wide variety of ways. In this regard, flow resistance component
1125 can cause a change in the size or shape of the shunt to vary
flow conditions and thereby vary the flow rate. Or, the flow
resistance component 1125 can re-route the blood flow through one
or more alternate flow pathways in the shunt to vary the flow
conditions. Some exemplary embodiments of the flow resistance
component 1125 are now described.
[0145] As shown in FIGS. 16A, 16B, 16C, and 16D, in an embodiment
the shunt 120 has an inflatable bladder 1205 formed along a portion
of its interior lumen. As shown in FIGS. 16A and 16C, when the
bladder 1205 is deflated, the inner lumen of the shunt 120 remains
substantially unrestricted, providing for a low resistance flow. By
inflating the bladder 1205, however, as shown in FIGS. 16B and 16D,
the flow lumen can be greatly restricted, thus greatly increasing
the flow resistance and reducing the flow rate of atrial blood to
the venous vasculature. The controller 1130 can control
inflation/deflation of the bladder 1205 or it can be controlled
manually by the user.
[0146] Rather than using an inflatable internal bladder, as shown
in FIGS. 16A-16D, the cross-sectional area of the lumen in the
shunt 120 may be decreased by applying an external force, such as
flattening the shunt 120 with a pair of opposed plates 1405, as
shown in FIGS. 17A-17D. The opposed plates are adapted to move
toward and away from one another with the shunt 120 positioned
between the plates. When the plates 1405 are spaced apart, as shown
in FIGS. 17A and 17C, the lumen of the shunt 120 remains
unrestricted. When the plates 1405 are closed on the shunt 120, as
shown in FIGS. 17B and 17D, in contrast, the plates 1405 constrict
the shunt 120. In this manner, the lumen remaining in shunt 120 can
be greatly decreased to increase flow resistance through the shunt.
The controller 1130 can control movement of the plates 1405 or such
movement can be controlled manually by the user.
[0147] Referring now to FIGS. 18A and 18B, the available
cross-sectional area of the shunt 120 can also be restricted by
axially elongating a portion 1505 of the shunt 120. Prior to axial
elongation, the portion 1505 will be generally unchanged, providing
a full luminal flow area in the portion 1505, as shown in FIG. 18A.
By elongating the portion 1505, however, as shown in FIG. 18B, the
internal luminal area of the shunt 120 in the portion 1505 can be
significantly decreased and the length increased, both of which
have the effect of increasing the flow resistance. When employing
axial elongation to reduce the luminal area of shunt 120, it will
be advantageous to employ a mesh or braid structure in the shunt at
least in the portion 1505. The mesh or braid structure provides the
shunt 120 with a pliable feature that facilitates axial elongation
without breaking. The controller 1130 can control elongation of the
shunt 120 or such it can be controlled manually by the user.
[0148] Referring now to FIGS. 19A-19D, instead of applying an
external force to reduce the cross-sectional area of shunt 120, a
portion of the shunt 120 can be made with a small diameter to begin
with, as shown in FIGS. 19A and 19C. The shunt 120 passes through a
chamber 1600 which is sealed at both ends. A vacuum is applied
within the chamber 1600 exterior of the shunt 120 to cause a
pressure gradient. The pressure gradient cause the shunt 120 to
increase in size within the chamber 120, as shown in FIGS. 16B and
12D. The vacuum may be applied in a receptacle 1605 attached to a
vacuum source 1610. Conversely, a similar system may be employed
with a shunt 120 whose resting configuration is in the increased
size. Pressure may be applied to the chamber to shrink or flatten
the shunt to decrease the flow resistance. The controller 1130 can
control the vacuum or it can be controlled manually by the
user.
[0149] As yet another alternative, the flow resistance through
shunt 120 may be changed by providing two or more alternative flow
paths. As shown in FIG. 20A, the flow through shunt 120 passes
through a main lumen 1700 as well as secondary lumen 1705. The
secondary lumen 1705 is longer and/or has a smaller diameter than
the main lumen 1700. Thus, the secondary lumen 1705 has higher flow
resistance than the main lumen 1700. By passing the blood through
both these lumens, the flow resistance will be at a minimum. Blood
is able to flow through both lumens 1700 and 1705 due to the
pressure drop created in the main lumen 1700 across the inlet and
outlet of the secondary lumen 1705. This has the benefit of
preventing stagnant blood. As shown in FIG. 20B, by blocking flow
through the main lumen 1700 of shunt 120, the flow can be diverted
entirely to the secondary lumen 1705, thus increasing the flow
resistance and reducing the blood flow rate. It will be appreciated
that additional flow lumens could also be provided in parallel to
allow for a three, four, or more discrete flow resistances. The
shunt 120 may be equipped with a valve 1710 that controls flow to
the main lumen 1700 and the secondary lumen 1705 with the valve
1710 being controlled by the controller 1130 or being controlled
manually by the user. The embodiment of FIGS. 20A and 20B has an
advantage in that this embodiment in that it does not require as
small of lumen sizes to achieve desired retrograde flow rates as
some of the other embodiments of variable flow resistance
mechanisms. This is a benefit in blood flow lines in that there is
less chance of clogging and causing clots in larger lumen sizes
than smaller lumen sizes.
[0150] The shunt 120 can also be arranged in a variety of coiled
configurations which permit external compression to vary the flow
resistance in a variety of ways. Arrangement of a portion of the
shunt 120 in a coil contains a long section of the shunt in a
relatively small area. This allows compression of a long length of
the shunt 120 over a small space. As shown in FIGS. 21A and 21B, a
portion of the shunt 120 is wound around a dowel 1805 to form a
coiled region. The dowel 1805 has plates 1810a and 1810b which can
move toward and away from each other in an axial direction. When
plates 1810a and 1810b are moved away from each other, the coiled
portion of the shunt 105 is uncompressed and flow resistance is at
a minimum. The shunt 120 is large diameter, so when the shunt is
non-compressed, the flow resistance is low, allowing a high-flow
state. To down-regulate the flow, the two plates 1810a and 1810b
are pushed together, compressing the coil of shunt 120. By moving
the plates 1810a and 1810b together, as shown in FIG. 21B, the
coiled portion of the shunt 120 is compressed to increase the flow
resistance. The controller 1130 can control the plates or they can
be controlled manually by the user.
[0151] A similar compression apparatus is shown in FIGS. 22A and
22B. In this configuration, the coiled shunt 120 is encased between
two movable cylinder halves 1905a and 1905b. The halves 1905a and
1905b can slide along dowel pins 1910 to move toward and away from
one another. When the cylinder halves 1905 are moved apart, the
coiled shunt 120 is uncompressed and flow resistance is at a
minimum. When the cylinder halves 1905 are brought together, the
coiled shunt 120 is compressed circumferentially to increase flow
resistance. The controller 1130 can control the halves 1905 or they
can be controlled manually by the user.
[0152] As shown in FIGS. 23A through 23D, the shunt 120 may also be
wound around an axially split mandrel 2010 having wedge elements
2015 on opposed ends. By axially translating wedge elements 2015 in
and out of the split mandrel 2010, the split portions of the
mandrel are opened and closed relative to one another, causing the
coil of tubing to be stretched (when the mandrel portions 2010 are
spread apart, FIG. 23C, 23D) or relaxed (when the mandrel portions
2010 are closed, FIG. 23A, 23B.) Thus, when the wedge elements 2015
are spaced apart, as shown in FIGS. 23A and 23B, the outward
pressure on the shunt 120 is at a minimum and the flow resistance
is also at a minimum. By driving the wedge elements 2015 inwardly,
as shown in FIGS. 23C and 23D, the split mandrel halves 2020 are
forced apart and the coil of shunt 120 is stretched. This has the
dual effect of decreasing the cross sectional area of the shunt and
lengthening the shunt in the coiled region, both of which lead to
increased flow resistance.
[0153] FIGS. 24A and 24B show an embodiment of the variable
resistance component 1125 that uses a dowel to vary the resistance
to flow. A housing 2030 is inserted into a section of the shunt
120. The housing 2030 has an internal lumen 2035 that is contiguous
with the internal lumen of the shunt 120. A dowel 2040 can move
into and out of a portion of the internal lumen 2035. As shown in
FIG. 24A, when the dowel 2040 is inserted into the internal lumen
2035, the internal lumen 2035 is annular with a cross-sectional
area that is much smaller than the cross-sectional area of the
internal lumen 2035 when the dowel is not present. Thus, flow
resistance increases when the dowel 2040 is positioned in the
internal lumen 2035. The annular internal lumen 2035 has a length S
that can be varied by varying the portion of the dowel 2040 that is
inserted into the lumen 2035. Thus, as more of the dowel 2040 is
inserted, the length S of the annular lumen 2035 increases and
vice-versa. This can be used to vary the level of flow resistance
caused by the presence of the dowel 2040.
[0154] The dowel 2040 enters the internal lumen 2035 via a
hemostasis valve in the housing 2030. A cap 2050 and an O-ring 2055
provide a sealing engagement that seals the housing 2030 and dowel
2040 against leakage. The cap 2050 may have a locking feature, such
as threads, that can be used to lock the cap 2050 against the
housing 2030 and to also fix the position of the dowel 2040 in the
housing 2040. When the cap 2050 is locked or tightened, the cap
2050 exerts pressure against the O-ring 2055 to tighten it against
the dowel 2040 in a sealed engagement. When the cap 2050 is
unlocked or untightened, the dowel 2040 is free to move in and out
of the housing 2030.
[0155] Any type of closing element, including a self-closing
element, may be deployed about the penetration in the wall of the
common carotid artery prior to withdrawing the sheath 605 at the
end of the procedure. Usually, the closing element will be deployed
at or near the beginning of the procedure, but optionally, the
closing element could be deployed as the sheath is being withdrawn,
often being released from a distal end of the sheath onto the wall
of the artery where the penetration occurs, such as the common
carotid artery. Use of a self-closing element is advantageous since
it affects substantially the rapid closure of the penetration in
the common carotid artery as the sheath is being withdrawn. Such
rapid closure can reduce or eliminate unintended blood loss either
at the end of the procedure or during accidental dislodgement of
the sheath. In addition, such a self-closing element may reduce the
risk of arterial wall dissection during access. Further, the
self-closing element may be configured to exert a frictional or
other retention force on the sheath during the procedure. Such a
retention force is advantageous and can reduce the chance of
accidentally dislodging the sheath during the procedure. A
self-closing element eliminates the need for vascular surgical
closure of the artery with suture after sheath removal, reducing
the need for a large surgical field and greatly reducing the
surgical skill required for the procedure.
[0156] The disclosed systems and methods may employ a wide variety
of closing elements, typically being mechanical elements which
include an anchor portion and a closing portion such as a
self-closing portion. The anchor portion may comprise hooks, pins,
staples, clips, tine, suture, or the like, which are engaged in the
exterior surface of the common carotid artery about the penetration
to immobilize the self-closing element when the penetration is
fully open. The self-closing element may also include a spring-like
or other self-closing portion which, upon removal of the sheath,
will close the anchor portion in order to draw the tissue in the
arterial wall together to provide closure. Usually, the closure
will be sufficient so that no further measures need be taken to
close or seal the penetration. Optionally, however, it may be
desirable to provide for supplemental sealing of the self-closing
element after the sheath is withdrawn. For example, the
self-closing element and/or the tissue tract in the region of the
element can be treated with hemostatic materials, such as
bioabsorbable polymers, collagen plugs, glues, sealants, clotting
factors, or other clot-promoting agents. Alternatively, the tissue
or self-closing element could be sealed using other sealing
protocols, such as electrocautery, suturing, clipping, stapling, or
the like. In another method, the self-closing element will be a
self-sealing membrane or gasket material which is attached to the
outer wall of the vessel with clips, glue, bands, or other means.
The self-sealing membrane may have an inner opening such as a slit
or cross cut, which would be normally closed against blood
pressure. Any of these self-closing elements could be designed to
be placed in an open surgical procedure, or deployed
percutaneously.
[0157] In an embodiment, the closing element is a is a suture-based
blood vessel closure device that can perform the dilation of an
arteriotomy puncture, and therefore does not require previous
dilation of the arteriotomy puncture by a separate device or by a
procedural sheath dilator. The suture-based vessel closure device
can place one or more sutures across a vessel access site such
that, when the suture ends are tied off after sheath removal, the
stitch or stitches provide hemostasis to the access site. The
sutures can be applied either prior to insertion of a procedural
sheath through the arteriotomy or after removal of the sheath from
the arteriotomy. The device can maintain temporary hemostasis of
the arteriotomy after placement of sutures but before and during
placement of a procedural sheath and can also maintain temporary
hemostasis after withdrawal of the procedural sheath but before
tying off the suture. Some exemplary suture-based blood vessel
disclosure devices are described in the following U.S. patents,
which are incorporated herein by reference in their entirety: U.S.
Pat. No. 7,001,400, and U.S. Pat. No. 7,004,952.
[0158] While this specification contains many specifics, these
should not be construed as limitations on the scope of an invention
that is claimed or of what may be claimed, but rather as
descriptions of features specific to particular embodiments.
Certain features that are described in this specification in the
context of separate embodiments can also be implemented in
combination in a single embodiment. Conversely, various features
that are described in the context of a single embodiment can also
be implemented in multiple embodiments separately or in any
suitable sub-combination. Moreover, although features may be
described above as acting in certain combinations and even
initially claimed as such, one or more features from a claimed
combination can in some cases be excised from the combination, and
the claimed combination may be directed to a sub-combination or a
variation of a sub-combination. Similarly, while operations are
depicted in the drawings in a particular order, this should not be
understood as requiring that such operations be performed in the
particular order shown or in sequential order, or that all
illustrated operations be performed, to achieve desirable
results.
[0159] Although embodiments of various methods and devices are
described herein in detail with reference to certain versions, it
should be appreciated that other versions, embodiments, methods of
use, and combinations thereof are also possible. Therefore the
spirit and scope of the appended claims should not be limited to
the description of the embodiments contained herein.
* * * * *