U.S. patent application number 11/273899 was filed with the patent office on 2006-03-23 for mechanical thrombectomy device for use in cerebral vessels.
Invention is credited to Gerald Dorros, Michael Hogendijk, Claudio Javier Schonholz.
Application Number | 20060064073 11/273899 |
Document ID | / |
Family ID | 46150213 |
Filed Date | 2006-03-23 |
United States Patent
Application |
20060064073 |
Kind Code |
A1 |
Schonholz; Claudio Javier ;
et al. |
March 23, 2006 |
Mechanical thrombectomy device for use in cerebral vessels
Abstract
Apparatus and methods for treating cerebral occlusions are
provided, comprising a thrombectomy device having at least one
deployable element. The deployable element is advanced through the
occlusion in a contracted state, then self-deploys distal of the
occlusion or, alternatively, may be deployed to a wide range of
configurations using a physician-actuated deployment knob. The
thrombectomy device then may be retracted to cause the deployable
element to snare the occlusion, and/or rotated circumferentially to
cause the fibrin strands of the occlusion to be wrapped around the
deployable element.
Inventors: |
Schonholz; Claudio Javier;
(Shreveport, LA) ; Dorros; Gerald; (Scottsdale,
AZ) ; Hogendijk; Michael; (Palo Alto, CA) |
Correspondence
Address: |
GORE ENTERPRISE HOLDINGS, INC.
551 PAPER MILL ROAD
P. O. BOX 9206
NEWARK
DE
19714-9206
US
|
Family ID: |
46150213 |
Appl. No.: |
11/273899 |
Filed: |
November 14, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10278183 |
Oct 21, 2002 |
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11273899 |
Nov 14, 2005 |
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09972225 |
Oct 4, 2001 |
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10278183 |
Oct 21, 2002 |
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60314269 |
Aug 22, 2001 |
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Current U.S.
Class: |
604/500 |
Current CPC
Class: |
A61M 29/00 20130101;
A61M 25/1002 20130101; A61B 17/3207 20130101; A61B 2017/22034
20130101; A61B 17/22031 20130101; A61M 2025/09166 20130101; A61B
2017/22044 20130101; A61B 17/221 20130101; A61M 2025/09008
20130101; A61B 17/12136 20130101; A61B 2017/3435 20130101; A61B
17/22 20130101; A61M 2025/1052 20130101; A61B 17/12109 20130101;
A61B 2017/22094 20130101; A61B 17/12022 20130101; A61M 2025/09083
20130101 |
Class at
Publication: |
604/500 |
International
Class: |
A61M 31/00 20060101
A61M031/00 |
Claims
1-18. (canceled)
19. A method for treating a cerebral occlusion, the method
comprising: providing apparatus comprising a catheter body having
proximal and distal ends, a handle affixed to the proximal end, an
engagement section affixed to the distal end, the engagement
section comprising at least one deployable element provided in a
contracted state, and an atraumatic tip affixed to a distal end of
the engagement section; advancing the deployable element through an
occlusion in the contracted state; deploying the deployable element
distal of the occlusion; and retracting the deployable element to
engage the occlusion.
20. The method of claim 19 wherein deploying the deployable element
comprises actuating a deployment knob.
21. The method of claim 20 further comprising selectively deploying
the deployable element to at least one intermediate state between
the contracted state and a fully deployed state.
22. The method of claim 19 further comprising: providing a micro
catheter having proximal and distal ends and a lumen extending
therebetween; advancing the distal end of the micro catheter to a
location distal of the occlusion; advancing the deployable element
through the micro catheter in the contracted state; and
self-deploying the deployable element distal of the distal end of
the micro catheter.
23. The method of claim 19 wherein the deployable element is
retracted to snare the occlusion.
24. The method of claim 19 wherein the deployable element is
rotated circumferentially to engage and wrap fibrin strands of the
occlusion around the deployable element.
25. The method of claim 19 further comprising: providing an emboli
removal catheter having proximal and distal ends, a working lumen
extending therebetween and an occlusive element disposed on the
distal end; positioning the distal end of the emboli removal
catheter proximal of the occlusion; deploying the occlusive element
to occlude antegrade flow into a treatment vessel; and providing
retrograde flow through the working lumen to influence flow in the
treatment vessel.
26. The method of claim 25 further comprising removing emboli from
the treatment vessel using the retrograde flow provided.
Description
REFERENCE TO RELATED APPLICATION
[0001] The present application is a divisional of U.S. patent
application Ser. No. 10/278,183 filed Oct. 21, 2002 which is a
continuation-in-part of U.S. patent application Ser. No. 09/972,225
filed Oct. 4, 2001.
FIELD OF THE INVENTION
[0002] The present invention relates to improved apparatus and
methods for removal of vascular occlusions. More specifically, the
apparatus and methods of the present invention are directed to
removing cerebral occlusions by providing a device having at least
one deployable element configured to snare and/or rotationally
engage fibrin strands of the occlusion.
BACKGROUND OF THE INVENTION
[0003] Cerebral occlusions that lead to stroke require swift and
effective therapy to reduce morbidity and mortality rates
associated with the disease. Many current technologies for treating
stroke are inadequate because emboli generated during the procedure
may travel downstream from the original occlusion and cause
ischemia. There is currently a need for a stroke treatment system
that provides a swift and efficient treatment for occlusions while
simultaneously controlling cerebral flow characteristics.
[0004] In the initial stages of stroke, a CT scan or MRI may be
used to diagnose the cerebral occlusion, which commonly occurs in
the middle cerebral arteries. Many current technologies position a
catheter proximal of the occlusion, then deliver clot dissolving
drugs to treat the lesion. A drawback associated with such
technology is that delivering drugs may require a period of up to
six hours to adequately treat the occlusion. Another drawback
associated with lytic agents (i.e., clot dissolving agents) is that
they often facilitate bleeding.
[0005] When removing a thrombus using mechanical thrombectomy
devices, it is beneficial to engage the thrombus and remove it as
cleanly as possible, to reduce the amount of emboli that are
liberated. However, in the event that emboli are generated during
mechanical disruption of the thrombus, it is imperative that they
be subsequently removed from the vasculature.
[0006] Several methods are known for mechanically removing clots to
treat cerebral occlusions. For example, U.S. Pat. No. 5,895,398 to
Wensel et al. (Wensel) describes a shape-memory coil affixed to an
insertion mandrel. The coil is contracted to a reduced profile
state within the lumen of a delivery catheter, and the catheter is
used to cross a clot. Once the coil is disposed distal of the clot,
the coil is deployed and retracted proximally to engage and remove
the clot.
[0007] A primary drawback associated with the device described in
the Wensel patent is that the deployed coil contacts the intima of
the vessel, and may damage the vessel wall when the coil is
retracted to snare the occlusion. Additionally, the configuration
of the coil is such that the device may not be easily retrieved
once it has been deployed. For example, once the catheter has been
withdrawn and the coil deployed distal of the occlusion, it may be
difficult or impossible to exchange the coil for another of
different dimensions.
[0008] U.S. Pat. No. 5,972,019 to Engelson et al. (Engelson)
describes a deployable cage assembly that may be deployed distal of
a clot. Like the Wensel device, the device described in the
Engelson patent is depicted as contacting the intima of the vessel,
and presents the same risks as the Wensel device. In addition,
because the distal end of the device comprises a relatively large
profile, the risk of dislodging emboli while crossing the clot is
enhanced, and maneuverability of the distal end of the device
through tortuous vasculature may be reduced.
[0009] In view of these drawbacks of previously known devices, it
would be desirable to provide apparatus and methods for removal and
recovery of thrombi and/or emboli above the carotid
bifurcation.
[0010] It also would be desirable to provide apparatus and methods
that quickly and efficiently treat cerebral occlusions while
reducing trauma imposed upon cerebral vessels.
[0011] It further would be desirable to provide apparatus and
methods for a thrombectomy device that may be used to snare an
occlusion and/or rotationally engage fibrin strands of the
occlusion.
[0012] It still further would be desirable to provide apparatus and
methods for a thrombectomy device that selectively may be actuated
to deploy to a plurality of deployment configurations while
disposed within a treatment vessel.
SUMMARY OF THE INVENTION
[0013] In view of the foregoing, it is an object of the present
invention to provide apparatus and methods for removal and recovery
of thrombi and/or emboli above the carotid bifurcation.
[0014] It also is an object of the present invention to provide
apparatus and methods that quickly and efficiently treat cerebral
occlusions while reducing trauma imposed upon cerebral vessels.
[0015] It further is an object of the present invention to provide
apparatus and methods for a thrombectomy device that may be used to
snare an occlusion and/or rotationally engage fibrin strands of the
occlusion.
[0016] It is a further object of the present invention to provide
apparatus and methods for a thrombectomy device that selectively
may be actuated to deploy to a plurality of deployment
configurations while disposed within a treatment vessel.
[0017] These and other objects of the present invention are
accomplished by providing a thrombectomy device having proximal and
distal ends and an occlusion engagement section disposed near the
distal end. The engagement section comprises proximal and distal
ends and at least one deployable element disposed therebetween. The
deployable element has a contracted state suitable for insertion
into a vessel and at least one deployed state in which the
deployable element extends radially outward from the engagement
section. In one of the deployed states, the deployable element
preferably comprises a hook shape configured to snare an occlusion
when the thrombectomy device is retracted proximally. The
deployable element further is configured to engage and wrap fibrin
strands of the occlusion about the deployable element when the
thrombectomy device is rotated circumferentially.
[0018] In a first embodiment of the present invention, the
thrombectomy device comprises a catheter body affixed to the
proximal end of the engagement section, an atraumatic tip affixed
to the distal end of the engagement section, and a handle disposed
at the proximal end of the thrombectomy device.
[0019] In a preferred method of operation, an emboli removal
catheter is advanced over a guidewire and disposed proximal of an
occlusion. Natural or suctionassisted aspiration is provided
through the emboli removal catheter to induce a retrograde flow in
the treatment vessel. With retrograde flow established, the
guidewire is advanced through the occlusion. A micro catheter
having a lumen then is advanced over the guidewire and through the
occlusion, and the guidewire is removed from within the micro
catheter.
[0020] The engagement section of the thrombectomy device is
advanced distally through the lumen of the micro catheter with the
deployable element being constrained in the contracted state within
the micro catheter. Once the deployable element is advanced distal
of the micro catheter, the deployable element selfdeploys to the
predetermined, preferably hook shape.
[0021] At this time, the thrombectomy device may be retracted
proximally to cause the deployable element to snare the occlusion,
and/or rotated circumferentially to cause the deployable element to
engage and wrap fibrin strands of the occlusion about the
deployable element. Emboli generated during the procedure are
directed into the emboli removal catheter due to the established
retrograde flow in the treatment vessel. An increased level of
retrograde flow temporarily may be provided through the emboli
removal catheter to enhance retrograde flow during disruption of
the occlusion. Upon satisfactory removal of thrombi and/or emboli,
the deployable element is retracted proximally and contracted
against the distal end of the emboli removal catheter, then removed
from the patient's vessel.
[0022] In an alternative embodiment of the present invention, the
above-described thrombectomy device comprises a physician-actuated
handle used to deploy the deployable element to a plurality of
configurations. In this embodiment, a rod affixed to a deployment
knob engages selected notches of the handle that represent the
various deployment configurations.
[0023] When the rod engages a first notch, the deployable element
is provided in a contracted state. When the deployment knob is
actuated by a physician and the rod engages a second notch, the
deployable element is transformed to a fully deployed state. At
least one intermediate notch also may be provided to allow the
deployable element to be deployed to at least one intermediate
state between the contracted and fully deployed states.
[0024] The thrombectomy device of the alternative embodiment
preferably is used in conjunction with the above-described emboli
removal catheter. In operation, the distal end of the thrombectomy
device, which has handling characteristics similar to those of a
traditional guidewire, is advanced through the emboli removal
catheter and through the occlusion under retrograde flow
conditions. When the deployable element is disposed distal of the
occlusion, e.g., under fluoroscopic guidance, a physician actuates
the deployment knob to transform the deployable element from the
contracted state to either the fully deployed state or an
intermediate state. The thrombectomy device then is retracted
proximally to cause the deployable element to snare the occlusion,
and/or rotated circumferentially to wrap the fibrin strands of the
occlusion about the deployable element, as described hereinabove.
Upon removal of thrombi and/or emboli, the deployment knob is
actuated to return the deployable element to the contracted state
for removal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] 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:
[0026] FIGS. 1A-1B provide side views illustrating features of a
deployable element of the present invention;
[0027] FIG. 2 provides a side view of a first embodiment of a
thrombectomy device of the present invention;
[0028] FIGS. 3A-3D are side sectional views illustrating a
technique for preparing the thrombectomy device of FIG. 2 for use
in a patient's vessel;
[0029] FIGS. 4A-4D are side views illustrating a preferred method
of using the apparatus of FIGS. 2-3 to treat a cerebral
occlusion;
[0030] FIGS. 5A-5C are, respectively, top views illustrating an
alternative thrombectomy device of the present invention in
contracted, intermediate and fully deployed states;
[0031] FIG. 6 provides a side sectional view of the handle of the
thrombectomy device of FIGS. 5A-5C; and
[0032] FIGS. 7A-7B are side views illustrating features of the
distal end of the thrombectomy device of FIGS. 5A-5C.
DETAILED DESCRIPTION OF THE INVENTION
[0033] Referring to FIG. 1, a preferred method for manufacturing a
hook-shaped deployable element, for use with a thrombectomy device
of the present invention, is described. In FIG. 1A, tubular member
18 having proximal and distal ends 22 and 24 and a lumen extending
therebetween is provided and preferably comprises a shape memory
material, for example, a nickel-titanium alloy (commonly known in
the art as Nitinol). Plurality of longitudinal slits 25 are formed
at selected locations about the circumference of tubular member 18
to define at least one deployable element 26. As shown in FIG. 1A,
plurality of longitudinal slits 25 preferably are disposed about
tubular member 18 so that they do not extend to proximal and distal
ends 22 and 24 of tubular member 18.
[0034] When proximal end 22 is advanced distally with respect to
distal end 24, and/or distal end 24 is advanced proximally with
respect to proximal end 22, deployable element 26 becomes biased
radially outward from tubular member 18. Deployable element 26
further may be biased in a proximal direction, e.g., by applying
external forces, then may be heat treated to self-deploy to the
predetermined hook-shaped configuration depicted in FIG. 1B. In the
context of the present invention, the term "hook-shaped" refers
generally to a bent shape extending radially outward from tubular
member 18 and in a proximal direction.
[0035] Techniques are known for setting of a custom shape in a
piece of Nitinol, e.g., by constraining the Nitinol element on a
mandrel or fixture in the desired shape and applying an appropriate
heat treatment. In accordance with such techniques, tubular member
18 and deployable element 26 are heat treated to form occlusion
engagement section 20, which has a deployed configuration adapted
to engage a cerebral occlusion, as described hereinbelow.
[0036] Referring now to FIG. 2, thrombectomy device 10 constructed
in accordance with a first embodiment of the present invention is
described. Thrombectomy device 10 preferably comprises catheter
body 12 having proximal and distal ends and a lumen extending
therebetween, occlusion engagement section 20 of FIG. 1B,
atraumatic tip 32, and handle 34, which is affixed to the proximal
end of catheter body 12.
[0037] The distal end of catheter body 12 is affixed to proximal
end 22 of occlusion engagement section 20, e.g., using a
biocompatible adhesive, and distal end 24 of engagement section 20
is affixed to atraumatic tip 32. Atraumatic tip 32 preferably
comprises a platinum coil to facilitate insertion of the distal end
of device 10 under fluoroscopy. Thrombectomy device 10 preferably
further comprises proximal and distal radiopaque markers 15 and 16,
which may be disposed on proximal and distal ends 22 and 24 of
engagement section 20, respectively. Proximal and distal radiopaque
markers 15 and 16 may be used to facilitate positioning of
deployable element 26 under fluoroscopy, as described
hereinbelow.
[0038] Referring now to FIG. 3, thrombectomy device 10 of FIG. 2
preferably is used conjunction with a loading device and micro
catheter to facilitate delivery of deployable element 26 in a
contracted state to a location distal of an occlusion. In FIG. 3A,
loading device 40 comprises body 41 having proximal and distal ends
and bore 43 extending therebetween, and further comprises male luer
fitting 42 at the proximal end and female luer fitting 44 at the
distal end.
[0039] Atraumatic tip 32 and catheter body 12 comprise outer
diameters that are slightly smaller than an inner diameter of bore
43. In a preferred embodiment, the outer diameters are about 0.014
inches. When deployable element 26 is provided in the contracted
state, i.e., by the application of external forces, engagement
section 20 comprises an outer diameter that preferably is about
0.014 inches and substantially flush with atraumatic tip 32 and
catheter body 12. This allows atraumatic tip 32, engagement section
20 and the distal end of catheter body 12 to be advanced distally
through bore 43, as shown in FIG. 3B. The advancement of engagement
section 20 through bore 43 causes deployable element 26 to be
constrained in the contracted state within bore 43.
[0040] Micro catheter 50 having proximal and distal ends and lumen
53 extending therebetween further is provided to facilitate
delivery of deployable element 26. Lumen 53 preferably comprises an
inner diameter that is approximately equal to the inner diameter of
bore 43 of loading device 40. Micro catheter 50 further preferably
comprises male luer fitting 52 at the proximal end which is
configured to engage female luer fitting 44 of loading device
40.
[0041] Referring now to FIG. 3C, female luer fitting 44 of loading
device 40 is coupled to male luer fitting 52 of micro catheter 50
and engagement section 20 is advanced distally through lumen 53 of
micro catheter 50. Deployable element 26 remains in the contracted
state as engagement section 20 is advanced through micro catheter
50.
[0042] At this time, male luer fitting 52 may be disengaged from
female luer fitting 44. Loading device 40 then is retracted
proximally over catheter body 12 until the proximal end of loading
device 40 contacts handle 34 of thrombectomy device 10. Female luer
fitting 35 of handle 34 then is coupled to male luer fitting 42 of
loading device 40 to provide a proximal handle assembly that is
adapted to be grasped by a physician, as shown in FIG. 3D.
[0043] Referring now to FIG. 4, a preferred method for using
thrombectomy device 10 to treat a cerebral occlusion is described.
In a first method step, guidewire 65 is advanced through a
patient's vasculature and is disposed proximal of occlusion S in
treatment vessel V, e.g., a middle cerebral artery, using
techniques that are per se known in the art. Emboli removal
catheter 60 having proximal and distal ends, working lumen 61
extending therebetween, and occlusive element 62 disposed at the
distal end is inserted over guidewire 65 with occlusive element 62
in a contracted state. The distal end of emboli removal catheter 60
is positioned at a location proximal of occlusion S, and occlusive
element 62 is deployed, e.g., by inflating a balloon, to occlude
antegrade flow into treatment vessel V.
[0044] A substantially continuous level of retrograde flow then is
provided through working lumen 61 of emboli removal catheter 60,
e.g., using natural or suctionassisted aspiration techniques
described hereinbelow, to cause flow in treatment vessel V to flow
in a retrograde fashion. The direction of flow in treatment vessel
V is illustrated by the arrows in FIG. 4A, which is toward emboli
removal catheter 60. For an occlusion S residing in a patient's
cerebral vasculature, it is preferred that emboli removal catheter
60 is disposed in a patient's carotid artery.
[0045] Emboli removal catheter 60 preferably is provided in
accordance with the catheter described in commonly-assigned U.S.
Pat. No. 6,423,032. The proximal end of emboli removal catheter may
be coupled to a venous return sheath (not shown) to form an
arterialvenous shunt suitable for providing retrograde flow in
treatment vessel V. This natural aspiration embodiment comprising
an arterial-venous shunt is described in detail in the
above-referenced patent. Alternatively, a suction-assisted
aspiration device, e.g., a syringe, may be coupled to a suction
port (not shown) disposed at the proximal end of emboli removal
catheter 60 and may be used alone or in conjunction with the
arterial-venous shunt to induce retrograde flow in treatment vessel
V. With retrograde flow established in treatment vessel V using
natural and/or suction-assisted techniques, guidewire 65 is
advanced distally to pierce through occlusion S.
[0046] Referring now to FIG. 4B, the distal end of micro catheter
50 of FIG. 3 is advanced over guidewire 65, through working lumen
60 of emboli removal catheter 60, and through occlusion S with
retrograde flow having been established in treatment vessel V. When
the distal end of micro catheter 50 is disposed distal of occlusion
S, guidewire 65 is retracted proximally and removed from within
lumen 53 of micro catheter 50.
[0047] At this time, the steps described hereinabove with respect
to FIGS. 3A-3D may be performed to facilitate insertion of
deployable element 26 in the contracted state through micro
catheter 50. Specifically, engagement section 20 of thrombectomy
device 10 is advanced distally into loading device 40 to cause
deployable element 26 to assume the contracted state. The distal
end of loading device 40 then is coupled to the proximal end of
micro catheter 50 and deployable element 26 is advanced distally
into lumen 53 of micro catheter 50. The distal end of loading
device 40 then may be disengaged from the proximal end of micro
catheter 50, and the proximal end of loading device 40 then may be
coupled to handle 34 and grasped by a physician.
[0048] Referring now to FIG. 4C, engagement section 20 of device 10
is advanced distally through micro catheter 50 and is disposed
distal of micro catheter 50 to cause deployable element 26 to
self-deploy in treatment vessel V distal of occlusion S. Micro
catheter 50 then may be retracted proximally through occlusion S
and into the confines of emboli removal catheter 60, while
deployable element 26 is held stationary distal of occlusion S.
[0049] Referring now to FIG. 4D, thrombectomy device 10 of FIG. 2
may be retracted proximally to cause hookshaped deployable element
26 to snare occlusion S, and/or rotated circumferentially to cause
the fibrin strands of occlusion S to be wrapped about deployable
element 26. Emboli E liberated during the procedure are directed
into working lumen 61 of emboli removal catheter 60 for removal.
Increased rates of suction-assisted aspiration preferably are
applied, e.g., using a syringe (not shown) coupled to the proximal
end of emboli removal catheter 60, when occlusion S is
disrupted.
[0050] Thrombectomy device 10 then is retracted proximally under
fluoroscopic guidance until deployable element 26 contacts the
distal end of emboli removal catheter 60. At this time, further
retraction of device 10 causes deployable element 26 to be inverted
and then contracted within working lumen 61.
[0051] It should be noted that the inversion and contraction of
deployable element 26 is not expected to impose significant trauma
upon a patient's vasculature. This is because deployable element 26
preferably is used to remove occlusions in a patient's cerebral
vasculature, e.g., a middle cerebral artery, which comprises a
relatively small diameter. In the deployed state, deployable
element 26 self-deploys to a predetermined outer diameter that is
smaller than an inner diameter of the cerebral vessel, as depicted
in FIGS. 4C-4D. Deployable element 26 then is retracted proximally
through the cerebral vasculature in the deployed state under
fluoroscopic guidance using radiopaque markers 15 and 16.
Deployable element 26 is not inverted and contracted until it
contacts the distal end of emboli removal catheter 60, which
preferably is disposed in a patient's carotid artery. Because the
carotid artery comprises a larger inner diameter relative to
cerebral vessels, the inversion and contraction of deployable
element 26 is not expected to impose significant trauma upon a
patient's vasculature.
[0052] Referring now to FIG. 5, an alternative embodiment of a
thrombectomy device of the present invention is described.
Thrombectomy device 110 comprises occlusion engagement section 120,
which preferably is provided in accordance with occlusion
engagement section 20 of FIG. 1B. Specifically, engagement section
120 comprises a tubular member having a plurality of slits disposed
in a lateral surface of the tubular member to form at least one
deployable element 126. Deployable element 126 comprises a
contracted state, as shown in FIG. 5A, and a fully deployed state,
as depicted in FIG. 5C.
[0053] Preferably, deployable element 126 comprises a shape-memory
material and is heat treated, using techniques described
hereinabove, to be inclined to selfdeploy to the fully deployed
state shown in FIG. 5C. In this embodiment, deployable element 126
advantageously may be deployed to achieve a plurality of
intermediate states between the contracted and fully deployed
states, as illustratively shown in FIG. 5B.
[0054] Thrombectomy device 110 preferably comprises catheter body
112 having proximal and distal ends and a lumen extending
therebetween, handle 134, deployment knob 135, and core wire 150
having proximal and distal ends, which is disposed through the
lumen of catheter body 112, as shown in FIGS. 6-7. Proximal end 122
of engagement section 120 is affixed to the distal end of catheter
body 112, while distal end 124 of engagement section 126 is affixed
to atraumatic tip 132.
[0055] Handle 134 preferably comprises slot 136, which is coupled
to a plurality of notches. In a preferred embodiment, handle 134
comprises first notch 140 corresponding to the contracted state of
deployable element 126, second notch 142 corresponding to the fully
deployed state, and at least one intermediate notch 141
corresponding to an intermediate state, as described
hereinbelow.
[0056] Referring now to FIG. 6, preferred features of handle 134
and deployment knob 135 are described in greater detail. Deployment
knob 135 is affixed to a proximal end of rod 139. A distal end of
rod 139 comprises pin 137, which is configured to be disposed in a
selected notch. Rod 139 further comprises a bore extending between
the proximal and distal ends that is configured to contain a
proximal section of core wire 150, as shown in FIG. 6. The proximal
end of core wire 150 is affixed to deployment knob 135. By
advancing deployment knob 135 proximally or distally with respect
to handle 134, core wire 150 translates the force to the distal end
of device 110 to actuate deployable element 126, as described in
detail in FIG. 7 hereinbelow.
[0057] The proximal end of catheter body 112 is disposed within
handle 134, as shown in FIG. 6, and preferably is affixed to handle
134 in the vicinity of region 146. The bore of rod 139 comprises an
inner diameter that is slightly larger than an outer diameter of
catheter body 112 to permit rod 139 to be longitudinally advanced
over catheter body 112 within handle 134. Handle 134 preferably
comprises spring 152, which biases rod 139 and deployable knob 135
in a proximal direction, as shown in FIG. 6.
[0058] Referring now to FIG. 7, features of the distal end of
thrombectomy device 110 are described in greater detail. Core wire
150 extends from deployment knob 135 of FIG. 6, through lumen 113
of catheter body 112, through the tubular member of engagement
section 120, and preferably is affixed to distal end 124 of
engagement section 120 and further affixed to atraumatic tip
132.
[0059] In FIG. 7A, deployable element 126 is provided in a
contracted state when deployment knob 135 is advanced distally and
pin 137 of rod 139 is disposed within first notch 140. In the
contracted state, core wire 150 serves to impose a tensile force
upon engagement section 120 that prevents atraumatic tip 132 from
being advanced proximally towards catheter body 112. In the
contracted state, engagement section 120 preferably comprises an
outer diameter of about 0.014 inches, which is substantially flush
with outer diameters of atraumatic tip 132 and catheter body
112.
[0060] When deployment knob 135 is retracted proximally and pin 137
is disposed within second notch 142, core wire 150 also is
retracted proximally to cause atraumatic-tip 132 to be advanced
towards catheter body 112. The retraction of core wire 150 imposes
a compressive force upon engagement section 120 to cause deployable
element 126 to bow radially outward and deploy to the fully
deployed state, as shown in FIGS. 5C and 7B. Deployable element 126
will be inclined to assume the hook shape shown, i.e., whereby
deployable element 126 extends radially outward and in a proximal
direction, when heat treated to deploy to that shape using
techniques described hereinabove.
[0061] Deployable element 126 also may assume any intermediate
configuration between the contracted and fully deployed states by
disposing pin 137 in an intermediate notch. For example, when pin
137 is disposed within intermediate notch 141, core wire 150 holds
deployable element in an intermediate state, as shown in FIG. 5B.
Because pin 137 is temporarily locked within notch 141, deployable
element 126 will retain the intermediate configuration until pin
137 is rotated and disengaged from notch 141.
[0062] Deployable element 126 may be returned from the intermediate
or fully deployed states of FIGS. 5B and 5C, respectively, to the
contracted state of FIG. 5A by distally advancing deployment knob
135, which in turn causes core wire 150 to reimpose the tensile
force upon engagement section 120. As will be appreciated by those
skilled in the art, handle 134 may comprise any number of
intermediate notches that cause deployable element 126 to deploy to
any number of intermediate configurations.
[0063] The intermediate configuration depicted in FIG. 5B comprises
a profile having an outer diameter which illustrates the maximum
outer diameter that deployable element 126 may achieve between the
contracted state shown in FIG. 5A and the fully deployed state
shown in FIG. 5C. Diameter `x` preferably is configured to be
slightly smaller than an inner diameter of a treatment vessel, to
reduce trauma to the treatment vessel caused by the actuation of
deployable element 126.
[0064] Thrombectomy device 110 preferably comprises physical
characteristics associated with those of a traditional guidewire.
Specifically, core wire 150 is configured to provide pushability
for the device, while atraumatic tip 132 preferably comprises a
platinum coil that allows a physician to maneuver the distal end of
the device through a patient's vasculature.
[0065] In operation, thrombectomy device 110 preferably is used in
conjunction with emboli removal catheter 60 of FIG. 4. In a first
step, emboli removal catheter 60 is advanced over a guidewire (not
shown) and is disposed in a patient's vessel proximal of an
occlusion. Retrograde flow then is established in treatment vessel
V via working lumen 61, as described hereinabove, and the guidewire
is removed from within working lumen 61.
[0066] Thrombectomy device 110 then is advanced through working
lumen 61 with deployable element 126 in the contracted state shown
in FIG. 5A. Atraumatic tip 132 serves to guide the distal end of
thrombectomy device 110 from the distal end of emboli removal
catheter 60 to the site of occlusion S in treatment vessel V. As
noted hereinabove, when occlusion S is situated in a middle
cerebral artery, it is preferred that emboli removal catheter 60 is
disposed in a patient's carotid artery.
[0067] With retrograde flow established in treatment vessel V,
atraumatic tip 132 is advanced distally to pierce through occlusion
S. Thrombectomy device 110 further is advanced distally, under
fluoroscopic guidance using radiopaque markers 115 and 116, until
proximal radiopaque marker 115 is disposed distal of occlusion S.
At this time, deployment knob 135 may be actuated, as described in
detail hereinabove, to transform deployable element 126 from the
contracted state to an intermediate state or the fully deployed
state, as shown in FIGS. 5B5C, respectively.
[0068] Handle 134 then may be retracted proximally to cause
deployable element 126 to engage occlusion S. As described
hereinabove with respect to FIG. 4D, thrombectomy device 110 may be
retracted proximally to cause deployable element 126 to snare the
occlusion, and/or may be rotated circumferentially to cause the
fibrin strands of the occlusion to be wrapped around the deployable
element. Emboli liberated during the procedure are directed
proximally towards emboli removal catheter 60 due to the
established retrograde flow. Increased rates of aspiration may be
provided, e.g., using a syringe coupled to the proximal end of
emboli removal catheter 60, to enhance the removal of emboli when
the occlusion is disrupted. Advantageously, a physician selectively
may actuate deployment knob 135 during the procedure to cause
deployable element 126 to be transformed from a first deployment
configuration to a second deployment configuration, without having
to remove device 110 from the patient's vessel.
[0069] Upon disruption of the occlusion, deployment knob 135 is
advanced distally to cause deployable element 126 to be returned to
the contracted state, as shown in FIG. 5A. The distal end of
thrombectomy device 110 then is retracted proximally into working
lumen 61, and emboli removal catheter 60 may be removed from the
patient's vessel.
[0070] 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 therein without
departing from the invention. The appended claims are intended to
cover all such changes and modifications that fall within the true
spirit and scope of the invention.
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