U.S. patent application number 13/043402 was filed with the patent office on 2011-06-30 for apparatus and methods for reducing embolization during treatment of carotid artery disease.
Invention is credited to Mark C. Bates, Michael Hogendijk, Juan Carlos Parodi.
Application Number | 20110160762 13/043402 |
Document ID | / |
Family ID | 28039859 |
Filed Date | 2011-06-30 |
United States Patent
Application |
20110160762 |
Kind Code |
A1 |
Hogendijk; Michael ; et
al. |
June 30, 2011 |
APPARATUS AND METHODS FOR REDUCING EMBOLIZATION DURING TREATMENT OF
CAROTID ARTERY DISEASE
Abstract
Methods and apparatus are provided for removing emboli during an
angioplasty, stenting or surgical procedure comprising a catheter
having an occlusion element, an aspiration lumen, and a blood
outlet port in communication with the lumen, a guide wire having a
balloon, a venous return sheath with a blood inlet port, and tubing
that couples the blood outlet port to the blood inlet port.
Apparatus is also provided for occluding the external carotid
artery to prevent reversal of flow into the internal carotid
artery. The pressure differential between the artery and the vein
provides reverse flow through the artery, thereby flushing emboli.
A blood filter may optionally be included in-line with the tubing
to filter emboli from blood reperfused into the patient.
Inventors: |
Hogendijk; Michael; (Palo
Alto, CA) ; Parodi; Juan Carlos; (Buenos Aires,
AR) ; Bates; Mark C.; (Charleston, WV) |
Family ID: |
28039859 |
Appl. No.: |
13/043402 |
Filed: |
March 8, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11156865 |
Jun 20, 2005 |
7927347 |
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13043402 |
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10100630 |
Mar 15, 2002 |
6908474 |
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11156865 |
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09418727 |
Oct 15, 1999 |
6423032 |
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10100630 |
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09333074 |
Jun 14, 1999 |
6206868 |
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09418727 |
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PCT/US99/05469 |
Mar 12, 1999 |
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09333074 |
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09078263 |
May 13, 1998 |
6413235 |
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PCT/US99/05469 |
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Current U.S.
Class: |
606/194 |
Current CPC
Class: |
A61M 25/104 20130101;
A61B 2217/005 20130101; A61F 2/01 20130101; A61B 2017/00243
20130101; A61F 2230/0006 20130101; A61M 2025/1052 20130101; A61M
2025/09175 20130101; A61M 25/1002 20130101; A61M 2025/1015
20130101; A61B 17/221 20130101; A61B 17/12109 20130101; A61M
2025/1097 20130101; A61B 2017/320716 20130101; A61B 17/12045
20130101; A61F 2/013 20130101; A61M 25/0045 20130101; A61M 29/00
20130101; A61M 2025/09008 20130101; A61M 2025/109 20130101; A61M
2205/75 20130101; A61B 17/12136 20130101; A61B 2017/22067 20130101;
A61B 17/22 20130101; A61M 2025/0681 20130101; A61B 17/12 20130101;
A61F 2/011 20200501 |
Class at
Publication: |
606/194 |
International
Class: |
A61M 29/00 20060101
A61M029/00 |
Claims
1. A method of delivering an interventional instrument for treating
a stenosis in an internal carotid artery comprising: a) inserting
an occlusion mechanism having a distal occlusion member and a
balloon into a person's vasculature; b) positioning the distal
occlusion member to a desired position in the common carotid artery
and the balloon to a desired position in the external carotid
artery; and c) operating the distal occlusion member and the
balloon to occlude the external carotid artery and the central
carotid artery.
2. A method according to claim 1, wherein said occlusion mechanism
further comprises a catheter having a proximal end and a distal
end, an aspiration lumen extending therethrough, and said distal
occlusion member positioned at said distal end of said
catheter.
3. A method according to claim 2, further comprising: aspirating
blood through said aspiration lumen.
4. A method according to claim 2, further comprising: inducing
reverse flow to cause blood and emboli to flow into the aspiration
lumen of the catheter.
5. A method according to claim 4 wherein inducing reverse flow
further comprises: a) providing a venous return sheath having a
proximal end and a distal end, a lumen extending therethrough, and
a blood inlet port coupled to the lumen; and b) causing blood flow
between the aspiration lumen of the catheter and the blood inlet
port of the venous return sheath to induce reverse flow.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional of pending U.S.
patent application Ser. No. 11/156,865, filed Jun. 20, 2005, which
is a divisional of pending U.S. patent application of Ser. No.
10/100,630, filed Mar. 15, 2002, now U.S. Pat. No. 6,908,474,
issued Jun. 21, 2005, which is a continuation-in-part of U.S.
patent application Ser. No. 09/418,727, filed Oct. 15, 1999, now
U.S. Pat. No. 6,423,032, issued Jul. 23, 2002, which is a
continuation-in-part of U.S. patent application Ser. No.
09/333,074, filed Jun. 14, 1999, now U.S. Pat. No. 6,206,868, which
is a continuation-in-part of International Application
PCT/US99/05469, filed Mar. 12, 1999, which is a
continuation-in-part of U.S. patent application Ser. No.
09/078,263, filed May 13, 1998, now U.S. Pat. No. 6,413,235, Issued
Jul. 2, 2002.
FIELD OF THE INVENTION
[0002] This invention relates to apparatus and methods for
protecting against embolization during vascular interventions, such
as carotid artery angioplasty and endarterectomy. More
particularly, the apparatus and methods of the present invention
induce substantially continuous retrograde flow through the
internal carotid artery during treatment during an interventional
procedure, without significant blood loss.
BACKGROUND OF THE INVENTION
[0003] Carotid artery stenoses typically manifest in the common
carotid artery, internal carotid artery or external carotid artery
as a pathologic narrowing of the vascular wall, for example, caused
by the deposition of plaque, that inhibits normal blood flow.
Endarterectomy, an open surgical procedure, traditionally has been
used to treat such stenosis of the carotid artery.
[0004] An important problem encountered in carotid artery surgery
is that emboli may be formed during the course of the procedure,
and these emboli can rapidly pass into the cerebral vasculature and
cause ischemic stroke.
[0005] In view of the trauma and long recuperation times generally
associated with open surgical procedures, considerable interest has
arisen in the endovascular treatment of carotid artery stenosis. In
particular, widespread interest has arisen in transforming
interventional techniques developed for treating coronary artery
disease, such as angioplasty and stenting, for use in the carotid
arteries. Such endovascular treatments, however, are especially
prone to the formation of emboli.
[0006] Such emboli may be created, for example, when an
interventional instrument, such as a guide wire or angioplasty
balloon, is forcefully passed into or through the stenosis, as well
as after dilatation and deflation of the angioplasty balloon or
stent deployment. Because such instruments are advanced into the
carotid artery in the same direction as blood flow, emboli
generated by operation of the instruments are carried directly to
the brain by antegrade blood flow. Stroke rates after carotid
artery stenting have widely varied in different clinical series,
from as low as 4.4% to as high as 30%. One review of carotid artery
stenting including data from twenty-four major interventional
centers in Europe, North America, South America and Asia, had a
combined initial failure and combined mortality/stroke rate of more
than 7%. Cognitive studies and reports of intellectual changes
after carotid artery stenting indicate that embolization is a
common event causing subclinical cerebral damage.
[0007] Several previously known apparatus and methods attempt to
remove emboli formed during endovascular procedures by trapping or
suctioning the emboli out of the vessel of interest. These
previously known systems, however, provide less than optimal
solutions to the problems of effectively removing emboli.
[0008] Solano et al. U.S. Pat. No. 4,921,478 describes cerebral
angioplasty methods and devices wherein two concentric shafts are
coupled at a distal end to a distally-facing funnel-shaped
structure. A lumen of the innermost shaft communicates with an
opening in the funnel-shaped structure at the distal end, and is
open to atmospheric pressure at the proximal end. In use, the
funnel-shaped structure is deployed proximally (in the direction of
flow) of a stenosis, occluding antegrade flow. An angioplasty
balloon catheter is passed through the innermost lumen and into the
stenosis, and then inflated to dilate the stenosis. The patent
states that when the angioplasty balloon is deflated, a pressure
differential between atmospheric pressure and the blood distal to
the angioplasty balloon causes a reversal of flow in the vessel
that flushes any emboli created by the angioplasty balloon through
the lumen of the innermost catheter.
[0009] While a seemingly elegant solution to the problem of emboli
removal, several drawbacks of the device and methods described in
the Solano et al. patent seem to have lead to abandonment of that
approach. Chief among these problems is the inability of that
system to generate flow reversal during placement of the guide wire
and the angioplasty balloon across the stenosis. Because flow
reversal does not occur until after deflation of the angioplasty
balloon, there is a substantial risk that any emboli created during
placement of the angioplasty balloon will travel too far downstream
to be captured by the subsequent flow reversal. It is expected that
this problem is further compounded because only a relatively small
volume of blood is removed by the pressure differential induced
after deflation of the angioplasty balloon.
[0010] Applicant has determined another drawback of the method
described in the Solano patent: deployment of the funnel-shaped
structure in the common carotid artery ("CCA") causes reversal of
flow from the external carotid artery ("ECA") into the internal
carotid artery ("ICA"). Consequently, when a guide wire or
interventional instrument is passed across a lesion in either the
ECA or ICA, emboli dislodged from the stenosis are introduced into
the blood flow and carried into the cerebral vasculature via the
ICA.
[0011] The insufficient flow drawback identified for the system of
the Solano patent is believed to have prevented development of a
commercial embodiment of the similar system described in EP
Publication No. 0 427 429. EP Publication No. 0 427 429 describes
use of a separate balloon to occlude the ECA prior to crossing the
lesion in the ICA. However, like Solano, that publication discloses
that flow reversal occurs only when the dilatation balloon in the
ICA is deflated.
[0012] Chapter 46 of Interventional Neuroradiology: strategies and
practical techniques (J. J. Connors & J. Wojak, 1999),
published by Saunders of Philadelphia, Pa., describes using a
coaxial balloon angioplasty system for patients having proximal ICA
stenoses. In particular, a small, deflated occlusion balloon on a
wire is introduced into the origin of the ECA, and a guide catheter
with a deflated occlusion balloon is positioned in the CCA just
proximal to the origin of the ECA. A dilation catheter is advanced
through a lumen of the guide catheter and dilated to disrupt the
stenosis. Before deflation of the dilation catheter, the occlusion
balloons on the guide catheter and in the ECA are inflated to block
antegrade blood flow to the brain. The dilation balloon then is
deflated, the dilation catheter is removed, and blood is aspirated
from the ICA to remove emboli.
[0013] Applicant has determined that cerebral damage still may
result from the foregoing previously known procedure, which is
similar to that described in EP Publication No. 0 427 429, except
that the ICA is occluded prior to the ECA. Consequently, both of
these previously known systems and methods suffer from the same
drawback--the inability to generate flow reversal at sufficiently
high volumes during placement of the guide wire and dilation
catheter across the stenosis. Both methods entail a substantial
risk that any emboli created during placement of the balloon will
travel too far downstream to be captured by the flow reversal.
[0014] Applicants note, irrespective of the method of aspiration
employed with the method described in the foregoing Interventional
Neuroradioloqy article, substantial drawbacks are attendant. If,
for example, natural aspiration is used (i.e., induced by the
pressure gradient between the atmosphere and the artery), then only
a relatively small volume of blood is expected to be removed by the
pressure differential induced after deflation of the angioplasty
balloon. If, on the other hand, an external pump is utilized,
retrieval of these downstream emboli may require a flow rate that
cannot be sustained for more than a few seconds, resulting
insufficient removal of emboli.
[0015] Furthermore, with the dilation balloon in position, the
occlusion balloons are not inflated until after inflation of the
dilation balloon. Microemboli generated during advancement of the
dilation catheter into the stenosed segment may therefore be
carried by antegrade blood flow into the brain before dilation,
occlusion, and aspiration are even attempted.
[0016] Imran U.S. Pat. No. 5,833,650 describes a system for
treating stenoses that comprises three concentric shafts. The
outermost shaft includes a proximal balloon at its distal end that
is deployed proximal of a stenosis to occlude antegrade blood flow.
A suction pump then draws suction through a lumen in the outermost
shaft to cause a reversal of flow in the vessel while the innermost
shaft is passed across the stenosis. Once located distal to the
stenosis, a distal balloon on the innermost shaft is deployed to
occlude flow distal to the stenosis. Autologous blood taken from a
femoral artery using an extracorporeal blood pump is infused
through a central lumen of the innermost catheter to provide
continued antegrade blood flow distal to the distal balloon. The
third concentric shaft, which includes an angioplasty balloon, is
then advanced through the annulus between the innermost and
outermost catheters to dilate the stenosis.
[0017] Like the device of the Solano patent, the device of the
Imran patent appears to suffer the drawback of potentially
dislodging emboli that are carried into the cerebral vasculature.
In particular, once the distal balloon of Imran's innermost shaft
is deployed, flow reversal in the vasculature distal to the distal
balloon ceases, and the blood perfused through the central lumen of
the innermost shaft establishes antegrade flow. Importantly, if
emboli are generated during deployment of the distal balloon, those
emboli will be carried by the perfused blood directly into the
cerebral vasculature, and again pose a risk of ischemic stroke.
Moreover, there is some evidence that reperfusion of blood under
pressure through a small diameter catheter may contribute to
hemolysis and possible dislodgment of emboli.
[0018] In applicant's co-pending U.S. patent application Ser. No.
09/333,074, filed Jun. 14, 1999, which is incorporated herein by
reference, applicant described the use of external suction to
induce regional reversal of flow. That application further
described that intermittently induced regional flow reversal
overcomes the drawbacks of naturally-aspirated systems such as
described hereinabove. However, the use of external suction may in
some instances result in flow rates that are too high to be
sustained for more than a few seconds. In addition, continuous use
of an external pump may result in excessive blood loss, requiring
infusion of non-autologous blood and/or saline that causes
hemodilution, reduced blood pressure, or raise related safety
issues.
[0019] In view of these drawbacks of the previously known emboli
removal systems, it would be desirable to provide methods and
apparatus for removing emboli from within the carotid arteries
during interventional procedures, such as angioplasty or carotid
stenting, that reduce the risk that emboli are carried into the
cerebral vasculature.
[0020] It also would be desirable to provide methods and apparatus
for removing emboli from within the carotid arteries during
interventional procedures, such as angioplasty or carotid stenting,
that provide substantially continuous retrograde blood flow from
the treatment zone, thereby reducing the risk that emboli are
carried into the cerebral vasculature.
[0021] It further would be desirable to provide emboli removal
methods and apparatus that prevent the development of reverse flow
from the ECA and antegrade into the ICA once the CCA has been
occluded, thereby enhancing the likelihood that emboli generated by
a surgical or interventional procedure are effectively removed from
the vessel.
[0022] It also would be desirable to provide methods and apparatus
that allow for placement of an interventional device so that
retrograde flow may be achieved in the treatment vessel prior to
having a guide wire cross the lesion.
[0023] It also would be desirable to provide methods and apparatus
for removing emboli during an angioplasty or carotid stenting
procedure that enable filtering of emboli and reduced blood
loss.
SUMMARY OF THE INVENTION
[0024] In view of the foregoing, it is an object of this invention
to provide methods and apparatus for removing emboli from within
the carotid arteries during interventional procedures, such as
angioplasty or carotid stenting, that reduce the risk that emboli
are carried into the cerebral vasculature.
[0025] It also is an object of the present invention to provide
methods and apparatus for removing emboli from within the carotid
arteries during interventional procedures, such as angioplasty or
carotid stenting, that provide substantially continuous retrograde
blood flow from the treatment zone, thereby reducing the risk that
emboli are carried into the cerebral vasculature.
[0026] It is another object of the present invention to provide
emboli removal methods and apparatus that prevent the development
of reverse flow between the ECA and ICA once the common carotid
artery has been occluded, thereby enhancing the likelihood that
emboli generated by a surgical or interventional procedure are
effectively removed from the vessel.
[0027] It is still a further object of the present to provide
methods and apparatus that allow for placement of an interventional
device so that retrograde flow may be achieved in the treatment
vessel prior to having a guide wire cross the lesion.
[0028] It is yet another object of the present invention to provide
methods and apparatus for removing emboli during an angioplasty or
carotid stenting procedure that enable filtering of emboli and
reduced blood loss.
[0029] The foregoing objects of the present invention are
accomplished by providing interventional apparatus comprising an
arterial catheter, an occlusion element disposed on a guide wire, a
venous return sheath, and optionally a blood filter. The arterial
catheter has proximal and distal ends, an aspiration lumen
extending therethrough, an occlusion element disposed on the distal
end, and a hemostatic port and blood outlet port disposed on the
proximal end that communicate with the aspiration lumen. The
aspiration lumen is sized so that an interventional instrument,
e.g., an angioplasty catheter or stent delivery system, may be
readily advanced therethrough to the site of a stenosis in either
the ECA (proximal to the occlusion element) or the ICA.
[0030] In accordance with the principles of the present invention,
the arterial catheter is disposed in the CCA proximal of the
ICA/ECA bifurcation, the occlusion element on the guide wire is
disposed in the ECA to occlude flow reversal from the ECA to the
ICA, and the blood outlet port of the arterial catheter is coupled
to the venous return sheath, with or without the blood filter
disposed therebetween. Higher arterial than venous pressure,
especially during diastole, permits substantially continuous flow
reversal in the ICA during the procedure (other than when a
dilatation balloon is inflated), thereby flushing blood containing
emboli from the vessel. The blood is filtered and reperfused into
the body through the venous return sheath.
[0031] In an alternative embodiment, the occlusion element disposed
on the guide wire may be omitted, and replaced with apparatus
comprising a self-expanding element having proximal and distal
ends, a retrieval wire coupled to the proximal end and an
atraumatic tip coupled to the distal end. In this embodiment, a
dilator having a lumen may be disposed within the aspiration lumen
of the catheter so that the occlusion element is provided in a
contracted state within the lumen of the dilator. The occlusion
element then is ejected from the dilator and self-expands to
occlude the ECA. The dilator then is removed from the aspiration
lumen of the catheter, and the distal end of the catheter is
re-positioned in the CCA proximal of the carotid bifurcation. Flow
reversal is induced in the ICA, as described above, and the
self-expanding occlusion element may be contracted using the
retrieval wire provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Further features of the invention, its nature and various
advantages will be more apparent from the accompanying drawings and
the following detailed description of the preferred embodiments, in
which:
[0033] FIGS. 1A and 1B are schematic views of previously known
emboli protection systems;
[0034] FIG. 2 is a schematic view of an emboli protection system in
accordance with principles of the present invention;
[0035] FIGS. 3A-3D are, respectively, a schematic view of apparatus
in accordance with a first embodiment of the present invention,
detailed side and sectional views of the distal end of an
interventional device of the present invention, and a
cross-sectional view of an interventional device of the present
invention;
[0036] FIGS. 4A and 4B are views of the distal end of an
alternative interventional device suitable for use in the system of
the present invention;
[0037] FIGS. 5A-5D illustrate a method of using the system of FIG.
3 in accordance with the principles of the present invention;
[0038] FIGS. 6A-6C are, respectively, a schematic view and
cross-sectional views of the proximal and distal ends of a catheter
of an alternative embodiment of the present invention;
[0039] FIGS. 7A-7B depict features of the self-expanding occlusion
element of FIG. 6; and
[0040] FIGS. 8A-8D illustrate a method of using the system of FIG.
6 in accordance with the principles of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] Referring to FIGS. 1A and 1B, drawbacks of previously known
emboli removal catheters are described with reference to performing
percutaneous angioplasty of stenosis S in common carotid artery
CCA.
[0042] With respect to FIG. 1A, drawbacks associated with
naturally-aspirated emboli removal systems, such as described in
the above-mentioned patent to Solano and European Patent
Publication, are described. No flow reversal is induced by those
systems until after balloon 10 of angioplasty catheter 11 first is
passed across the stenosis, inflated, and then deflated. However,
applicant has determined that once member 15 of emboli removal
catheter 16 is inflated, flow within the ECA reverses and provides
antegrade flow into the ICA, due to the lower hemodynamic
resistance of the ICA. Consequently, emboli E generated while
passing guide wire 20 or catheter 11 across stenosis S may be
carried irretrievably into the cerebral vasculature, before flow in
the vessel is reversed and directed into the aspiration lumen of
emboli removal catheter 16 by opening the proximal end of the
aspiration lumen to atmospheric pressure. Furthermore,
natural-aspiration may not remove an adequate volume of blood to
retrieve even those emboli that have not yet been carried all the
way into the cerebral vasculature.
[0043] In FIG. 1B, system 17 described in the above-mentioned
patent to Imran is shown. As described hereinabove, deployment of
distal balloon 18, and ejection of blood out of the distal end of
the inner catheter, may dislodge emboli from the vessel wall distal
to balloon 18. The introduction of antegrade flow through inner
catheter 19 is expected only to exacerbate the problem by pushing
the emboli further into the cerebral vasculature. Thus, while the
use of positive suction in the Imran system may remove emboli
located in the confined treatment field defined by the proximal and
distal balloons, such suction is not expected to provide any
benefit for emboli dislodged distal of distal balloon 18.
[0044] Referring now to FIG. 2, apparatus and methods in accordance
with the present invention are described. Apparatus 30 comprises
catheter 31 having an aspiration lumen and occlusion element 32,
and guide wire 35 having inflatable balloon 36 disposed on its
distal end. In accordance with the principles of the present
invention, antegrade blood flow is stopped when both occlusion
element 32 in the CCA and inflatable balloon 36 are deployed.
Furthermore, the aspiration lumen of catheter 31 is connected to a
venous return sheath (described hereinbelow), disposed, for
example, in the patient's femoral vein. In this manner a
substantially continuous flow of blood is induced between the
treatment site and the patient's venous vasculature. Because flow
through the artery is towards catheter 31, any emboli dislodged by
advancing a guide wire or angioplasty catheter 33 across stenosis S
causes the emboli to be aspirated by catheter 31.
[0045] Unlike the previously known naturally-aspirated systems, the
present invention provides substantially continuous retrograde
blood flow through the ICA while preventing blood from flowing
retrograde in the ECA and antegrade into the ICA, thereby
preventing emboli from being carried into the cerebral vasculature.
Because the apparatus and methods of the present invention
"recycle" emboli-laden blood from the arterial catheter through the
blood filter and to the venous return sheath, the patient
experiences significantly less blood loss.
[0046] Referring now to FIG. 3A, embolic protection apparatus 40
constructed in accordance with the principles of the present
invention is described. Apparatus 40 comprises arterial catheter
41, guide wire 45, venous return sheath 52, tubing 49 and optional
blood filter 50.
[0047] Catheter 41 includes distal occlusion element 42, proximal
hemostatic port 43, e.g., a Touhy-Borst connector, inflation port
44, and blood outlet port 48. Guide wire 45 includes balloon 46
that is inflated via inflation port 47. Tubing 49 couples blood
outlet port 48 to filter 50 and blood inlet port 51 of venous
return sheath 52.
[0048] Guide wire 45 and balloon 46 are configured to pass through
hemostatic port 43 and the aspiration lumen of catheter 41 (see
FIGS. 3C and 3D), so that the balloon may be advanced into and
occlude the ECA. Port 43 and the aspiration lumen of catheter 41
are sized to permit additional interventional devices, such as
angioplasty balloon catheters, atherectomy devices and stent
delivery systems to be advanced through the aspiration lumen when
guide wire 45 is deployed.
[0049] Guide wire 45 preferably comprises a small diameter flexible
shaft having an inflation lumen that couples inflatable balloon 46
to inflation port 47.
[0050] Inflatable balloon 46 preferably comprises a compliant
material, such as described hereinbelow with respect to occlusion
element 42 of emboli removal catheter 41.
[0051] Venous return sheath 52 includes hemostatic port 53, blood
inlet port 51 and a lumen that communicates with ports 53 and 51
and tip 54.
[0052] Venous return sheath 52 may be constructed in a manner per
se known for venous introducer catheters. Tubing 49 may comprise a
suitable length of a biocompatible material, such as silicone.
Alternatively, tubing 49 may be omitted and blood outlet port 48 of
catheter 41 and blood inlet port 51 of venous return sheath 52 may
be lengthened to engage either end of filter 50 or each other.
[0053] With respect to FIGS. 3B and 3C, distal occlusion element 42
comprises expandable bell or pear-shaped balloon 55. In accordance
with manufacturing techniques that are known in the art, balloon 55
comprises a compliant material, such as polyurethane, latex or
polyisoprene which has variable thickness along its length to
provide a bell-shape when inflated. Balloon 55 is affixed to distal
end 56 of catheter 41, for example, by gluing or a melt-bond, so
that opening 57 in balloon 55 leads into aspiration lumen 58 of
catheter 41. Balloon 55 preferably is wrapped and heat treated
during manufacture so that distal portion 59 of the balloon extends
beyond the distal end of catheter 41 and provides an atraumatic tip
or bumper for the catheter.
[0054] As shown in FIG. 3D, catheter 41 preferably comprises inner
layer 60 of low-friction material, such as polytetrafluoroethylene
("PTFE"), covered with a layer of flat stainless steel wire braid
61 and polymer cover 62 (e.g., polyurethane, polyethylene, or
PEBAX). Inflation lumen 63 is disposed within polymer cover 62 and
couples inflation port 44 to balloon 55. In a preferred embodiment
of catheter 41, the diameter of lumen 58 is about 7 Fr, and the
outer diameter of the catheter is about 9 Fr.
[0055] Referring now to FIGS. 4A and 4B, an alternative embodiment
of occlusion element 42 of the system of FIG. 3A is described. In
FIGS. 4A and 4B, occlusion element 42 of emboli removal catheter 41
comprises self-expanding wire basket 65 covered with elastomeric
polymer 66, such as latex, polyurethane or polyisoprene.
Alternatively, a tightly knit self-expanding wire mesh may be used,
with or without an elastomeric covering.
[0056] Catheter 41 is contained within movable sheath 67. Catheter
41 is inserted transluminally with sheath 67 in a distalmost
position, and after basket 65 has been determined to be in a
desired position proximal to a stenosis, sheath 67 is retracted
proximally to cause basket 65 to deploy. Upon completion of the
procedure, basket 65 is again collapsed within sheath 67 by moving
the sheath to its distalmost position. Operation of the system of
FIG. 3A using the emboli removal catheter of FIGS. 4A and 4B is
similar to that described hereinbelow for FIGS. 5A-5D, except that
the occlusion element self-expands when sheath 67 is retracted,
rather than by infusing an inflation medium to balloon 55.
[0057] Referring now to FIGS. 5A-5D, use of the apparatus of FIG. 3
in accordance with the methods of the present invention is
described. In FIG. 5, stenosis S is located in internal carotid
artery ICA above the bifurcation between the ICA and the external
carotid artery ECA. In a first step, guide wire 80 is inserted into
a patient's arterial vasculature and a distal end of guide wire 80
preferably is disposed just proximal of the carotid bifurcation, as
shown in FIG. 5A. A dilator (not shown), which is disposed within
catheter 41, then may be inserted over guide wire 80 to advance
catheter 41 to a position proximal of stenosis S, as shown in FIG.
5A, and the dilator may be removed. Balloon 55 of distal occlusion
element 42 then is inflated via inflation port 44, preferably using
a radiopaque contrast solution, and guide wire 80 may be removed.
Once balloon 55 of distal occlusion element 42 is inflated, flow
within the ECA reverses and provides antegrade flow into the ICA,
as shown in FIG. 5A, due to the lower hemodynamic resistance of the
ICA.
[0058] Venous return sheath 52 then is introduced into the
patient's femoral vein, either percutaneously or via a surgical
cut-down. Filter 50 then is coupled between blood outlet port 48 of
catheter 41 and blood inlet port 51 of venous return sheath 52
using tubing 49, and any air is removed from the line. Once this
circuit is closed, negative pressure in the venous sheath during
diastole will establish a low rate continuous flow of blood through
aspiration lumen 58 of catheter 41, to the patient's vein via
venous return sheath 52.
[0059] Guide wire 45 and balloon 46 then may be advanced through
aspiration lumen 58. When balloon 46 is disposed within the ECA, as
determined, e.g., using a fluoroscope and a radiopaque inflation
medium injected into balloon 46, balloon 46 is inflated. The
deployment of balloon 46 in the ECA, in conjunction with the
negative pressure in the venous sheath during diastole, will
established a retrograde flow dynamic in the ICA, as shown in FIG.
5B.
[0060] This continuous retrograde flow in the ICA due to the
difference between venous pressure and arterial pressure will
continue throughout the interventional procedure. Specifically,
blood passes through aspiration lumen 58 and blood outlet port 48
of catheter 41, through biocompatible tubing 49 to filter 50, and
into blood inlet port 51 of venous return sheath 52, where it is
reperfused into the remote vein. Filtered emboli collect in filter
50 and may be studied and characterized upon completion of the
procedure.
[0061] Continuous blood flow (except during inflation of any
dilatation instruments) with reperfusion in accordance with the
present invention provides efficient emboli removal with
significantly reduced blood loss. Alternatively, filter 50 may be
omitted, in which case emboli removed from the arterial side will
be introduced into the venous side, and eventually captured in the
lungs. Because of a low incidence of septal defects, which could
permit such emboli to cross-over to the left ventricle, the use of
filter 50 is preferred.
[0062] Referring to FIG. 5C, an interventional instrument, such as
conventional angioplasty balloon catheter 71 having balloon 72, is
loaded through hemostatic port 43 and aspiration lumen 58 and
positioned within the stenosis, preferably via guide wire 73.
Hemostatic port 43 is closed and instrument 71 is actuated to
disrupt the plaque forming stenosis S.
[0063] As seen in FIG. 5D, upon completion of the angioplasty
portion of the procedure using catheter 71, balloon 72 is deflated.
Throughout the procedure, except when the dilatation balloon is
fully inflated, the pressure differential between the blood in the
ICA and the venous pressure causes blood in the ICA to flow in a
retrograde direction into aspiration lumen 58 of emboli removal
catheter 41, thereby flushing any emboli from the vessel. The blood
is filtered and reperfused into the patient's vein.
[0064] As set forth above, the method of the present invention
protects against embolization, first, by preventing the reversal of
blood flow from the ECA to the ICA when distal occlusion element 42
is inflated, and second, by providing continuous, low volume blood
flow from the carotid artery to the remote vein in order to filter
and flush any emboli from the vessel and blood stream.
Advantageously, the method of the present invention permits emboli
to be removed with little blood loss, because the blood is filtered
and reperfused into the patient. Furthermore, continuous removal of
blood containing emboli prevents emboli from migrating too far
downstream for aspiration.
[0065] Referring now to FIG. 6, apparatus 240 constructed in
accordance with the present invention is described. Apparatus 240
is an alternative embodiment of apparatus 40 described hereinabove
and comprises arterial catheter 241 having proximal and distal
ends, distal occlusion element 242 disposed on the distal end,
proximal hemostatic port 243, inflation port 244 and blood outlet
port 248. Self-expanding occlusion element 246 having proximal and
distal ends preferably comprises non-expanding occlusion base 256
disposed at the proximal end, wherein occlusion base 256 comprises
proximal taper 269. Occlusion element 246 is coupled to retrieval
wire 247 at the proximal end and atraumatic tip 245 at the distal
end, e.g., by affixing retrieval wire 247 to proximal taper 269 of
occlusion base 256 and affixing atraumatic tip 245 to a distal end
of occlusion base 256, as shown in FIG. 6A. Biocompatible tubing
249 couples blood outlet port 248 to filter 250 and to blood inlet
port 251 of venous return sheath 252. Arterial catheter 241, venous
return sheath 252 and tubing 249 are constructed as described
hereinabove, except as noted below.
[0066] Catheter 241 comprises aspiration lumen 258, as shown in
FIG. 6B, which is sized to permit interventional devices, such as
angioplasty balloon catheters, atherectomy devices and stent
delivery systems to be advanced through port 243 and the aspiration
lumen. Retrieval wire lumen 264 is sized to permit longitudinal
movement of retrieval wire 247 of occlusion element 246. Retrieval
wire lumen 264 spans from the proximal end of catheter 241 to a
location just proximal of the distal end, e.g., about 1 to 2 cm
proximal of the distal end of catheter 241. At this location,
retrieval wire lumen 264 merges with aspiration lumen 258 to form
channel 265, as shown in FIG. 6C.
[0067] Referring to FIG. 7, deployment of occlusion element 246 is
described. Occlusion element 246 initially is provided in a
contracted state, as shown in FIG. 7A. In the contracted state,
occlusion element 246 is disposed within a lumen of dilator 270,
which in turn is disposed within aspiration lumen 258 of catheter
241. Dilator 270 comprises proximal and distal ends, with occlusion
element 246 being positioned within a slot in the distal end. The
distal end of dilator 270 tapers and extends distal to catheter
241, as shown in FIG. 7A. Atraumatic tip 245 of occlusion element
246 extends distal to dilator 270 and facilitates guidance of the
device through a patient's vasculature.
[0068] Push member 272 having proximal and distal ends is
configured for longitudinal movement within the lumen of dilator
270. During delivery of catheter 241, the distal end of push member
272 preferably abuts occlusion base 256 of occlusion element 246,
while the proximal end of push member 272 may be manipulated by a
physician. Dilator 270 comprises slot 271 disposed at the distal
end. Slot 271 allows retrieval wire 247 to extend from a distal
point in which it is coupled to occlusion base 256, to a proximal
point in which it enters retrieval wire lumen 264, as shown in FIG.
7A.
[0069] Upon positioning the distal end of catheter 241 at a
selected location, push member 272 is held stationary while dilator
270 is retracted proximally, so that occlusion element 246
effectively is no longer constrained within the lumen of dilator
270. This causes occlusion element 246 to self-expand to a
predetermined shape, as shown in FIG. 7B. Occlusion element 246 is
sized to occlude flow in the external carotid artery in this
deployed state.
[0070] Dilator slot 271 allows retrieval wire 247 to move freely
during the deployment of occlusion element 246. After deployment of
occlusion element 246, dilator 270 and push member 272 are removed
from within aspiration lumen 258, as shown in FIG. 7B. Catheter 241
then may be positioned separately from occlusion element 246, as
described hereinbelow with respect to FIG. 8, and may be used to
deliver other interventional apparatus, such as angioplasty
catheters or stent delivery systems.
[0071] At the completion of the interventional procedure, occlusion
element 246 is contracted by proximally retracting retrieval wire
247. Occlusion element 246 is retrieved when the proximal load
exerted on retrieval wire 247 exceeds the frictional forces between
occlusion element 246 and the external carotid artery wall. After
occlusion element 246 is contracted, occlusion base 256, occlusion
element 246 and atraumatic tip 245 may be retracted partially or
fully into aspiration lumen 258. Channel 265 of FIG. 6C may be used
to provide a transition at the distal end of catheter 241 so that
occlusion element 246 is effectively guided into aspiration lumen
258 when retrieval wire 247 is retracted proximally. In effect,
this allows occlusion element 246 to be contained within at least a
distal portion of catheter 241, to allow for safe removal of
catheter 241.
[0072] Referring to FIG. 8, method steps for using the apparatus of
FIGS. 6-7 to treat carotid artery disease is provided. In FIG. 8,
stenosis S is located in the ICA above the carotid bifurcation. In
a first step, catheter 241 is inserted, either percutaneously and
transluminally or via a surgical cut-down, to a position proximal
of stenosis S. Occlusion element 246 is disposed within a lumen at
the distal end of dilator 270, as described in FIG. 7A, and
atraumatic tip 245 is used to guide catheter 241. The distal end of
catheter 241 preferably is positioned within the ECA, as shown in
FIG. 8A, so that occlusion element 246 will be deployed into the
ECA.
[0073] Push member 272 of FIG. 7A then is held stationary while
dilator 270 is retracted proximally, so that occlusion element 246
is no longer constrained by dilator 270. Occlusion element 246 then
self-expands to occlude flow in the ECA, as shown in FIG. 8B.
Dilator 270 and push member 272 then are removed from within
aspiration lumen 258, and catheter 241 is retracted to a location
just proximal of the carotid bifurcation, as shown in FIG. 8B.
Distal occlusion element 242 of catheter 241 then may be inflated
via inflation port 244 to occlude antegrade flow in the CCA.
[0074] Venous return sheath 252 may be introduced into the
patient's femoral vein, either percutaneously or via a surgical
cut-down, and filter 250 may be coupled between blood outlet port
248 of catheter 241 and blood inlet port 251 of venous return
sheath 252 using tubing 249. Once this circuit is closed, negative
pressure in the venous sheath establishes a continuous retrograde
flow of blood through aspiration lumen 258 of catheter 241, as
shown in FIG. 8B, to the patient's vein via venous return sheath
252. Alternatively, venous return sheath 252 may be omitted, and
the proximal end of catheter 241 connected to a receptacle to
collect blood aspirated through aspiration lumen 258.
[0075] Referring to FIG. 8C, with distal occlusion element 242
inflated and a retrograde flow established in the ICA, an
interventional instrument, such as conventional angioplasty balloon
catheter 281 having balloon 282, is loaded through hemostatic port
243 and aspiration lumen 258 and positioned within stenosis S,
preferably via guide wire 283. Hemostatic port 243 is closed and
instrument 281 is actuated to disrupt stenosis S.
[0076] As shown in FIG. 8D, upon completion of the angioplasty
portion of the procedure using catheter 281, balloon 282 is
deflated. Throughout the procedure, except when the dilatation
balloon is fully inflated, the pressure differential between the
blood in the ICA and the venous pressure causes blood in the ICA to
flow in a retrograde direction and into aspiration lumen 258 of
emboli removal catheter 241, thereby flushing any emboli E from the
vessel. Upon satisfactory removal of emboli, occlusion element 246
is contracted by proximally retracting retrieval wire 247.
Occlusion element 246 still further may be contracted when it
contacts the distal end of catheter 241. When occlusion element 246
has been contracted, it then may be retracted either partially or
fully into aspiration lumen 258 of catheter 241 via channel 265.
Distal occlusion element 242 of catheter 241 then is deflated and
the apparatus is removed from the patient's vessel.
[0077] While preferred illustrative embodiments of the invention
are described above, it will be apparent to one skilled in the art
that various changes and modifications may be made. The appended
claims are intended to cover all such changes and modifications
that fall within the true spirit and scope of the invention.
* * * * *