U.S. patent application number 10/738351 was filed with the patent office on 2004-07-08 for methods and devices for removing an obstruction from a blood vessel.
Invention is credited to Dieck, Martin, Gia, Son, Sepetka, Ivan.
Application Number | 20040133233 10/738351 |
Document ID | / |
Family ID | 24422442 |
Filed Date | 2004-07-08 |
United States Patent
Application |
20040133233 |
Kind Code |
A1 |
Sepetka, Ivan ; et
al. |
July 8, 2004 |
Methods and devices for removing an obstruction from a blood
vessel
Abstract
The devices and methods of the invention are directed to various
aspects of removing obstructions in a blood vessel. A power source
may be provided to facilitate advancement of the device and
engagement with the obstruction. The obstruction removal device may
have alternating large and small sections or may have one or more
loops. In another aspect, the obstruction removal device may have
alternating sections wound with filament and substantially exposed
sections.
Inventors: |
Sepetka, Ivan; (Los Altos,
CA) ; Gia, Son; (San Jose, CA) ; Dieck,
Martin; (Cupertino, CA) |
Correspondence
Address: |
HOEKENDIJK & LYNCH, LLP
P.O. BOX 4787
BURLINGAME
CA
94011-4787
US
|
Family ID: |
24422442 |
Appl. No.: |
10/738351 |
Filed: |
December 16, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10738351 |
Dec 16, 2003 |
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09605143 |
Jun 29, 2000 |
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6730104 |
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Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61F 2002/018 20130101;
A61B 18/1492 20130101; A61B 17/22031 20130101; A61B 2017/22034
20130101; A61M 25/0068 20130101; A61M 25/008 20130101; A61B
2017/2212 20130101; A61B 2017/2217 20130101; A61B 2017/2215
20130101; A61M 25/0074 20130101; A61F 2002/016 20130101; A61B
17/221 20130101; A61F 2230/0091 20130101; A61M 25/0082 20130101;
A61B 2018/00898 20130101; A61B 2018/00214 20130101 |
Class at
Publication: |
606/200 |
International
Class: |
A61M 029/00 |
Claims
What is claimed is:
1. A method of removing an obstruction, comprising the steps of:
providing an obstruction removing device, the obstruction removing
device having an element movable from a collapsed position to an
expanded position, the element being contained within a lumen in a
delivery device in the collapsed position; advancing the delivery
device through the patient's vascular system to an obstruction in a
vessel; expanding at least part of the engaging element toward the
expanded position; coupling the engaging element to a supply of
power; moving the engaging element into contact with the
obstruction; and supplying power to the element when the engaging
element is in contact with the obstruction.
2. The method of claim 1, wherein: the coupling step is carried out
with the supply of power producing an electrical charge at the
engaging element.
3. The method of claim 2, wherein: the coupling step is carried out
with the supply of power producing a negative charge during the
moving step.
4. The method of claim 2, wherein: the coupling step is carried out
with the supply of power producing a positive charge during the
supplying step.
5. The method of claim 1, wherein: the coupling step is carried out
with the supply of power being an RF generator.
6. The method of claim 1, wherein: the providing step is carried
out with the engaging element being naturally biased toward the
expanded position.
7. A method of constructing an obstruction removing device,
comprising the steps of: providing an elongate element; positioning
at least one strand against the elongate element; and positioning a
tube over the fiber to trap the fiber.
8. The method of claim 7, wherein: the positioning step is carried
out with the fiber has a diameter of less than 0.001 inch.
9. The method of claim 8, wherein: the positioning step is carried
out with the fiber being a thermoplastic multifilament yarn spun
from a liquid crystal polymer.
10. The method of claim 7, wherein: the positioning step is carried
out with the elongate element being made of superelastic
material.
11. The method of claim 7, wherein: the positioning step is carried
out with the elongate element being naturally biased toward an
expanded position.
12. The method of claim 7, wherein: the positioning step is carried
out with the elongate element being biased toward an expanded
position.
13. The method of claim 7, wherein: the providing step is carried
out with the diameter of the elongate element being 0.005-0.018
inch.
14. An obstruction removal device, comprising: an insertion element
having an expandable element extending from the insertion element;
at least one strand extending along at least the expandable
element; and a tube of material which traps the at least one
strand.
15. The device of claim 14, wherein: the strand has a diameter of
less than 0.005 inch.
16. The device of claim 15, wherein: the strand is a thermoplastic
multifilament yarn spun from a liquid crystal polymer.
17. The device of claim 14, wherein: the elongate element being
made of superelastic material.
18. The device of claim 14, wherein: the elongate element having a
diameter of 0.005-0.018 inch.
19. The device of claim 14, wherein: the elongate element being
biased toward an expanded position.
20. The device of claim 14, wherein: the elongate element has an
diameter of 0.005-0.010 inch.
21. A kit for removing an obstruction in a blood vessel,
comprising: an obstruction removing device having an elongate
insertion element and an expandable obstruction engaging element
extending from the elongate insertion element; and a catheter
having an expandable balloon mounted thereto, the catheter having
at least one lumen sized to receive the obstruction removal
device.
22. The kit of claim 21, further comprising: a delivery catheter
which extends through the lumen of the catheter, the delivery
catheter having a lumen in which the obstruction removing device is
positioned.
23. The kit of claim 21, wherein: the obstruction engaging element
is in a straightened configuration when collapsed.
24. A method of removing an obstruction in a blood vessel,
comprising the steps of: providing an obstruction removal device
and a guide catheter, the obstruction removing device having an
elongate insertion element and an expandable obstruction engaging
element extending from the elongate insertion element, the guide
catheter having a flow restricting element mounted thereto, the
delivery catheter having at least one lumen sized to receive the
obstruction removal device; advancing the obstruction removal
device through the guide catheter to an obstruction in a blood
vessel; expanding the flow restricting element to at least reduce
blood flow in the blood vessel; engaging the obstruction with the
obstruction removal device while the flow restricting element is
expanded; and removing the obstruction.
25. An obstruction removal device, comprising: an elongate element
extending from an insertion element, the elongate element being
movable from a collapse position to an expanded position, the
elongate element forming helical coils having varying diameter,
wherein the coils at a distal portion are larger than the coils at
an intermediate portion.
26. The device of claim 25, wherein: the elongate element has a
proximal portion which has coils which are larger than the coils at
the intermediate portion.
27. A method of removing an obstruction from a patient, comprising
the steps of: providing an obstruction removal device, the
obstruction removal device having an engaging element extending
from an insertion element, the engaging element being movable from
a collapsed condition to an expanded condition, the engaging
element having a proximal portion and a distal portion; passing the
obstruction removal device through an obstruction in a vessel with
the engaging element in the collapsed position; expanding the
distal portion at a location distal to the obstruction so that the
distal portion forms a trap to prevent the obstruction from
traveling downstream; and engaging the obstruction with the
proximal portion of the obstruction removal device after the
expanding step.
28. An obstruction removal device, comprising: an elongate
insertion element; and an obstruction engaging element extending
from the insertion element, the obstruction removing element being
movable from a collapsed position to an expanded position, the
obstruction removing device forming at least one closed loop in the
expanded position, the closed loop exerting substantially equal and
opposing radial forces when collapsed.
29. The device of claim 28, wherein: the obstruction engaging
element forms at least two loops in the expanded position, a first
loop lying in a first plane when expanded and a second loop lying
in a second plane when expanded.
30. The device of claim 29, wherein: the first plane is
substantially perpendicular to the first plane.
31. The device of claim 29, wherein: the first loop is larger than
the second loop, the first loop being positioned distal to the
second loop.
32. The device of claim 28, wherein: the engaging element is formed
by a core element and a filament wrapped around the core
element.
33. An obstruction removal device, comprising: an elongate
insertion element; and an obstruction engaging element movable from
a collapsed position to an expanded condition, the engaging element
having at least two wound sections having a filament wound around a
core element, the wound sections being separated by a section
substantially free of the filament.
34. The device of claim 33, wherein: the section which is
substantially free of the filament is at least 1 mm long.
35. The device of claim 33, wherein: the section which is
substantially free of the filament is at least 3 mm long.
36. The device of claim 33, wherein: the section which is
substantially free of the filament is no more than 6 mm long.
37. An obstruction removing device, comprising: an elongate
insertion element; and an obstruction engaging element movable from
a collapsed position to an expanded condition, the engaging element
having a first section, a second section, and a third section, the
second section being positioned between the first and third
sections, the second section forming coils having a smaller
diameter than coils formed by the first and third sections.
38. The device of claim 37, wherein: the obstruction engaging
element has a fourth section and a fifth section, the fourth
section being positioned between the third and fifth sections, the
fourth section forming coils having a smaller diameter than coils
formed by the third and fifth sections.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention is directed to methods and devices for
removing obstructions from blood vessels. The device may be used to
retrieve and remove clots and other biological obstructions. The
device may also be used to retrieve embolic coils and the like
which have been misplaced or have migrated to an undesirable
location.
[0002] One such obstruction removal device is disclosed in U.S.
Pat. No. 5,895,398 which is hereby incorporated by reference. The
device has an expandable engaging member which is introduced into
the blood vessel to engage the obstruction for removal.
[0003] The present invention is directed to additional devices and
methods for removing obstructions in a blood vessel.
SUMMARY OF THE INVENTION
[0004] In accordance with the present invention, device and methods
for removing obstructions are provided. In a first aspect of the
invention, an obstruction removal device is provided which has an
obstruction engaging element extending from an insertion element.
The engaging element is movable from a collapse position to an
expanded position. The engaging element forms coils having varying
diameter wherein the coils at a distal portion are larger than
coils at an intermediate portion. The distal portion forms a
relatively closed structure which prevents the obstruction, or any
part thereof, from migrating downstream. The distal portion is
expanded distal to the obstruction while the proximal portion
engages and holds the obstruction.
[0005] In another aspect of the present invention, another
obstruction removal device is provided which has at least one
closed loop and preferably two closed loops. The closed loop
provides an advantage when advanced through a catheter or sheath in
that the closed loop produces opposing radial forces on the
catheter or sheath through which the loop is advanced. In this
manner, the obstruction removal device can be advanced more easily
through the catheter or sheath to prevent binding or kinking of the
device during advancement. In a preferred embodiment, the
obstruction removal device has two loops of varying diameter with
the distal loop having a larger diameter. Each of the loops lie in
a plane with the planes of the two loops preferably being
perpendicular to one another.
[0006] In another aspect of the invention, another obstruction
removal device is provided which has wound sections formed by one
or more filaments which are separated by sections substantially
free of the filaments. The intermittent wound sections provide
discrete portions where the obstruction can be engaged. In an
embodiment, the wound sections can slide on the core element to
provide flexibility when advancing the obstruction removal device.
The wound sections and sections free of filament are preferably
about 1-5 mm long. The obstruction removal device preferably has at
least three wound sections and more preferably at least five wound
sections.
[0007] In still another aspect of the invention, another
obstruction removal device is provided which has alternating large
and small diameter portions. In a preferred embodiment, the
obstruction removal device has at least four large diameter
sections and three smaller diameter portions. The alternating large
and small diameter portions may help to engage certain types of
obstructions and can also help to prevent parts of the obstruction
from breaking off and migrating downstream.
[0008] Any of the obstruction removal devices described herein may
also be used with a source of power coupled to the obstruction
removal device for use as described below. The source of power may
simply produce a positive or negative charge or may be an RF energy
source. The source of power may be used to help the obstruction
removal device penetrate and engage the obstruction and may also be
used to adhere the obstruction to the obstruction removal device as
will be described. In a preferred embodiment, a negative charge is
provided when advancing the obstruction removal device into the
obstruction and a positive charge, or RF energy, is supplied to
adhere the device to the obstruction.
[0009] The devices of the present invention may be manufactured in
any suitable manner. In another aspect of the present invention,
the obstruction removal device has a core element surrounded by a
sheath. A strand, preferably about four strands, are positioned
between the core element and the tube. The strand and the tube
prevent any part of the obstruction removal device from breaking
free should the core element fail. The strand and tube will hold
the obstruction removal device together even if the core element
breaks. The sheath is preferably flexible so that the sheath can
undergo much larger deflections than the core element.
[0010] The obstruction removal devices of the present invention may
also be advanced through a guide catheter having a flow restricting
element which is preferably a balloon but may be any other suitable
structure. The flow restricting element is expanded to reduce blood
flow through the obstructed vessel to minimize the likelihood that
the obstruction will migrate downstream.
[0011] These and other advantages of the invention will become
apparent from the following description, drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 shows a system for removing an obstruction.
[0013] FIG. 2 shows the obstruction removal device in a collapsed
condition.
[0014] FIG. 3 shows the obstruction removal device with a distal
portion of the obstruction removal device expanded.
[0015] FIG. 4 shows the obstruction removal device with a proximal
portion expanded to engage an obstruction.
[0016] FIG. 5 shows another obstruction removal device.
[0017] FIG. 6 shows yet another obstruction removal device.
[0018] FIG. 7 shows still another obstruction removal device.
[0019] FIG. 8 is an end view of the obstruction removal device of
FIG. 7.
[0020] FIG. 9 is an exploded view showing a method of constructing
an obstruction removal device.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] Referring now to FIGS. 1-4, a system 2 for removing an
obstruction is shown. A guide catheter 4 is advanced to a location
proximal to an obstruction. When accessing the cerebral
vasculature, for example, the guide catheter 4 is often positioned
in the carotid or vertebral artery. Of course, the guide catheter 4
may not be necessary or may be positioned in any other suitable
location depending upon the location of the obstruction. The guide
catheter 4 preferably has a flow restricting element 6 which
restricts or even stops blood flow through the vessel as described
below. The flow restricting element 6 is preferably a balloon 5
coupled to a source of inflation fluid 7 which is used to inflate
the balloon 5.
[0022] An obstruction removing device 8 is advanced through the
guide catheter 4 to the obstruction. A microcatheter 10 may also be
positioned within the guide catheter 4 to deliver the obstruction
removing device 8 further into the vasculature. The obstruction
removing device may be advanced by itself through the microcatheter
10 or may be contained within a sheath 12 which is advanced through
the microcatheter 10. A source power 14 may also be coupled to the
obstruction removal device 8 for use in the manner explained below.
The power source 14 may simply produce a positive or negative
charge or may be an RF or other suitable power source.
[0023] The obstruction removing device 8 has an engaging element 16
extending from an insertion element 18. The engaging element 16 is
movable from a collapsed position (FIG. 2) to an expanded position
(FIGS. 3 and 4). When the engaging element 16 is contained within
the sheath 12 or microcatheter 10, the engaging element 16 is in a
relatively straight configuration. The engaging element 16 has a
distal portion 20, 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
16 has a proximal portion 22 which is formed with smaller coils
than the distal portion 20. The proximal portion 22 engages the
obstruction as described below.
[0024] The engaging element 16 preferably has a number of markers
23, 25, 27 which provide an indication as to how much of the
engaging element 16 extends from the sheath 12 or microcatheter 10.
For example, markers 23, 25, 27 may indicate when the engaging
element 16 is 1/2, 3/4 or fully exposed. In this manner, the user
may quickly advance the engaging element engaging element 16
through the sheath 12 or microcatheter 10 without inadvertently
exposing and advancing the engaging element 16 out of the sheath 12
or microcatheter. The markers 23, 25, 27 can also be used to
provide a controlled diameter of the engaging element 16 since the
diameter of the engaging element 16 is known for the various
positions corresponding to the markers 23, 25, 27. The markers 23,
25, 27 may also be used to size the vessel in which the engaging
element 16 is positioned by observing when the engaging element 16
engages the vessel walls and determining the size of the engaging
element 16 using the markers 23, 25, 27.
[0025] The insertion element 18 is preferably made 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 18 is preferably a solid, elongate element, the
insertion element 18 may take any other suitable structure such as
a hollow tube. The engaging element 16 is preferably 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 16 has a rounded,
atraumatic tip 24 to prevent damage to the vessel and facilitate
advancement through the vessel, microcatheter 10 and/or sheath 12.
A radiopaque wire 26, such as platinum ribbon 28 having a width of
0.004 inch and a thickness of 0.002 inch, is preferably wrapped
around the engaging element 16 to improve radiopacity.
[0026] The device 8 is preferably self-expanding but may also be
expanded with an actuator 29. The actuator 29 is preferably a thin
filament which is tensioned to move the device 8 to the expanded
position. An advantage of the invention is that the filament 29
extends through the same lumen as the device 8 thereby minimizing
the overall size of the device. It is understood that throughout
discussion of the devices and methods herein that any of the
devices may be expanded using the actuator 29 rather than being
self-expanding without departing from the scope of various aspects
of the invention.
[0027] The device 8 may also include a cover 9 which extends
between adjacent coils. The cover 9 may be a number of individual
strands 11 which extend between the coils or may be an elastic
membrane which covers the coils. The strands 11 are preferably
elastic to stretch when the device 8 is expanded.
[0028] Use of the obstruction removing device 8 is now described.
The guide catheter 4 is introduced into the patient and delivered
proximal to the target vessel such as to the carotid or vertebral
artery. The microcatheter 10 is then advanced through the guide
catheter 4 further into the vasculature to a position proximal to,
within or distal to the obstruction. The obstruction removal device
8 is then advanced through the microcatheter 10 either by itself or
pre-loaded within the sheath 12. The obstruction removal device 8
is then advanced to the obstruction. Before advancing the
obstruction removal device 8 further, the flow restricting element
6 on the guide catheter 4 is expanded to reduce and even stop flow
through the vessel. Stopping flow in the vessel may help prevent
the obstruction, or any parts thereof, from migrating downstream.
Reducing flow through the vessel may also reduce the likelihood
that the obstruction is disrupted by a combination of flow and the
obstruction removal device 8.
[0029] The obstruction removal device 8 is then placed into the
obstruction and preferably through the obstruction. The engaging
element 16 is then advanced out of the microcatheter 10 or sheath
12 to permit the distal portion 20 of the engaging element 16 to
expand at a location beyond the obstruction. In this manner, the
relatively closed distal portion 20 prevents the obstruction, or
any part thereof, from migrating downstream. The proximal portion
22 is then advanced out of the sheath 12 or microcatheter 10 so
that the smaller coils of the proximal portion 22 engage the
obstruction as shown in FIG. 4.
[0030] Referring to FIG. 5, another obstruction removal device 8A
is shown wherein the same or similar reference numbers refer to the
same or similar structure. The obstruction removal device 8A has a
first section 30 with larger diameter coils than a second section
32. A third section 34 also has larger coils than the second
section 32 with the second section 32 positioned between the first
and third sections 30, 34. The obstruction removal device 8A may
have a number of alternating small and large sections 30, 32, 34
which can enhance the ability of the obstruction removal device 8A
to engage various obstructions. In the preferred embodiment of FIG.
5, the obstruction removal device 8A has four large sections 32, 34
with relatively large coils and three sections 30 having smaller
coils.
[0031] The obstruction removal device 8A may be used in any
suitable manner to engage the obstruction. For example, the
microcatheter 10 or sheath 12 may be advanced through the
obstruction and then retracted to expose the obstruction removal
device 8A. The obstruction removal device 8A is then retracted into
the obstruction to engage the obstruction. The obstruction removal
device 8A may be rotated when moved into the obstruction to take
advantage of the generally helical shape of the obstruction removal
device. The obstruction removal device 8A may also be used to
engage the obstruction by simply retracting the microcatheter 10 or
sheath 12 with the obstruction removal device 8A expanding within
the obstruction. Finally, the engaging element 16A may be exposed
and expanded proximal to the obstruction and then advanced into the
obstruction. When advancing the obstruction removal device 8A into
the obstruction, the user may also twist the obstruction removal
device 8A to take advantage of the generally helical shape. The
alternating large and small sections 30, 32, 34 enhance the ability
of the engaging element 16A to engage varying shapes and sizes of
obstructions.
[0032] Referring to FIG. 6, still another obstruction removal
device 8B is shown wherein the same or similar reference numbers
refer to the same or similar structure. The obstruction removal
device 8B has the insertion element 18 with an engaging element 16B
extending therefrom. The engaging element 16B forms a helical coil
38 with a generally frustoconical shape, however, the engaging
element 16B may take any other shape without departing from the
scope of the invention including any shape disclosed in this
application or any patent incorporated by reference herein.
[0033] A filament 40, preferably a radiopaque filament, is wrapped
around the engaging element 16B. The filament 40 is wrapped
somewhat loosely around the engaging element 16B so that the
filament 40 provides additional surface area to engage the
obstruction. The filament 40 forms a wound section 42, and more
preferably at least five wound sections 42, which are separated by
substantially exposed sections 44 of the engaging element 16B. The
wound and exposed sections 42, 44 may be 1-5 mm long. Stated
another way, the wound and exposed sections 42, 44 are at least 1
mm, more preferably at least 3 mm long, and no more than 8 mm long.
The wound sections 42 may be formed by a single filament 40 which
extends continuously between the wound sections 42 or may be formed
by independent filaments 40 at each wound section 42 which are
attached to the engaging element 16B.
[0034] The wound sections 40 may be movable along the engaging
element 16B to provide flexibility when advancing the obstruction
removal device 8B through small and tortuous vessels. The movable
wound sections 40 may also allow different parts of the obstruction
removal device 8B to grip different parts of the obstruction to
hold the obstruction together or engage different parts of the
obstruction. The obstruction removal device 8B is used in
substantially the same manner as the other obstruction removal
devices described herein. The obstruction removal device 8B has a
handle 41 with a lead screw 43 which engages threads 55. The handle
41 is rotated to advance and retract the engaging element 16B.
[0035] Referring to FIG. 7, still another obstruction removal
device 8C is shown wherein the same or similar reference numbers
refer to the same or similar structure. The obstruction removal
device 8C has an engaging element 16C, which forms a first closed
loop 50, and a second closed loop 52. The first loop 50 is
preferably somewhat larger than the second closed loop 52 with the
first loop 50 having a diameter of about 1.5-8.0 mm and the second
loop 52 having a diameter of about 1.5-6.0 mm. A tip 54 extends
from the first loop 50 for a distance of about 5 mm. A radiopaque
element 56, such as platinum ribbon, is preferably wrapped around
the loops 50, 52 to improve radiopacity and to enhance the ability
of the engaging element 16C to hold the obstruction. The radiopaque
element 56 also may provide advantages when engaging an obstruction
in a manner similar to the obstruction removal devices described
above with reference to FIG. 6.
[0036] An advantage of the obstruction removal device 8C is that
the loops 50, 52 exert substantially equal and opposing forces on
the sheath 12 or microcatheter 10 through which the obstruction
removal device 8C is advanced. In this manner, kinking or binding
of the obstruction removal device 8C during advancement can be
minimized or reduced altogether. Referring to the end view of FIG.
8, the first and second loops 50, 52 preferably lie in first and
second planes 58, 60, respectively, which are preferably
perpendicular to one another.
[0037] Referring to FIG. 9, an exploded view of a construction of
the obstruction removal device 8, 8A, 8B, 8C is shown. A tube 62,
which is preferably a thermoplastic polymer such as polyester or
urethane is positioned over a core element 64. As mentioned above,
the core element 64 is preferably a superelastic or stainless steel
element at either the insertion element 18 or the engaging element
16 (FIGS. 2-7). A reinforcing strand 66 is trapped between the tube
62 and the core element 64 to reinforce the obstruction removal
device. The strand 66 is preferably small and has a diameter or
thickness of less than 0.005 inch, more preferably less than 0.0001
inch, so that the overall size of the obstruction removal device is
not increased significantly with use of the strand 66. The strand
66 may be made of any suitable material including VECTRAN made by
Celanese Acetate LLP or DACRON or KEVLAR which are both
manufactured by Dupont. VECTRAN is a thermoplastic multifilament
yarn spun from a liquid crystal polymer.
[0038] The strand 66 provides a degree of safety in that the strand
66 and tube 62 together prevent any part of the obstruction removal
device from breaking free from the rest of the device. The tube 62
will resist breaking since it is more flexible than the core
element 64 and can undergo larger deflections and displacements
without breaking. In a preferred embodiment, 2-8 strands 66,
preferably about 4 strands 66, are used. The overall size of the
device is also relatively small with the outer diameter of the
resulting structure being no more than 0.020 inch and more
preferably no more than 0.012 inch.
[0039] The power source 14 may be also be used with any of the
obstruction removal devices in the following manner, however, the
methods and devices of the present invention may, of course, be
practiced without the power source 14. As mentioned above, the
power source 14 may simply produce a charge at the engaging element
16 or may be a source of RF energy. In one particular method of the
present invention, the power source 14 produces a negative charge
while advancing the engaging element 16 through the obstruction.
The negative charge may aid in passing the engaging element 16
through the obstruction and may help to dissolve part of the
obstruction. The power supply is then changed to produce a positive
charge to adhere the obstruction to the engaging element 16.
Alternatively, the power source 14 may be an RF energy source,
which delivers RF to the engaging element 16 which also adheres the
obstruction to the engaging element 16 and may help provide a
controlled penetration into the obstruction. The obstruction is
then removed by moving the obstruction into the guide catheter 4,
which is then withdrawn to remove the obstruction. Use of the power
source 14 is particularly useful when the obstruction is a biologic
structure such as a clot.
[0040] While the above is a description of the preferred
embodiments of the invention, various alternatives, substitutions
and modifications may be made without departing from the scope
thereof, which is defined by the following claims. Thus, the
preferred embodiments should not be taken as limiting the scope of
the invention. For example, although all of the obstruction removal
devices described herein are self-expanding structures, the
obstruction removal devices may also have actuating mechanisms for
moving the engaging element between the expanded and collapsed
positions. Furthermore, the present invention is directed to a
number of separate inventions and each of these inventions may be
claimed independently of one another. Each feature, aspect and
advantage of the invention may be claimed independent of one
another without departing from the scope of the invention. For
example, use of the power source 14 is independent of the using the
intermittent wound sections 42 but may be used with any of the
devices and methods described herein. Thus, the invention does not
include a single essential feature, aspect or advantage and the
invention should not be limited as such. Finally, the preferred
dimensions, materials and methods of manufacture described for any
of the embodiments is equally applicable for other embodiments.
* * * * *