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| United States Patent |
6,375,606
|
|
Garibaldi
, et al.
|
April 23, 2002
|
Methods of and apparatus for treating vascular defects
Abstract
A method of and apparatus for treating vascular defects. A catheter having
a selectively energizeable coil on its distal end. The catheter is
particularly adapted for the delivery of magnetic embolic materials. The
coil can be energized to aid in the magnetic navigation of the catheter,
to help retain magnetic material in the catheter, to draw ejected magnetic
material back into the catheter. A catheter can also be used to deliver a
magnetic patch that can be magnetically applied to a vascular defect such
as an aneurysm.
| Inventors:
|
Garibaldi; Jeffrey M. (St. Louis, MO);
Hogg; Bevil J. (Town and Country, MO);
Hastings; Roger N. (Maple Grove, MN);
Ren; Brooke (Champlin, MN)
|
| Assignee:
|
Stereotaxis, Inc. (St. Louis, MO)
|
| Appl. No.:
|
430118 |
| Filed:
|
October 29, 1999 |
| Current U.S. Class: |
600/12 |
| Intern'l Class: |
A61M 037/00; A61N 002/00 |
| Field of Search: |
600/12,9,11,585
606/32,108,198
424/9
|
References Cited
U.S. Patent Documents
| 5353807 | Oct., 1994 | DeMarco | 600/585.
|
| 5851218 | Dec., 1998 | Lev | 606/198.
|
| 5895385 | Apr., 1999 | Gugliemi et al. | 606/32.
|
| 5951566 | Sep., 1999 | Lev | 606/108.
|
| 6015414 | Jan., 2000 | Werp et al. | 606/108.
|
Other References
Laksne et al, Iron-acrylic Compound for Stereotaxic Aneurysm Thrombosis, J
Neurosurgery 47:137-141 (1977).
|
Primary Examiner: Nasser; Robert L.
Assistant Examiner: Szmal; Brian
Attorney, Agent or Firm: Harness, Dickey & Pierce, PLC
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of prior U.S. patent application
Ser. No. 09/271,118, filed Mar. 17, 1999, entitled "Magnetic Vascular
Defect Treatment System" incorporated herein by reference.
Claims
What is claimed:
1. A catheter adapted for magnetic guidance inside the body, the catheter
having a proximal end, a distal end, and a lumen therebetween, a magnetic
material in the lumen adjacent the distal end and adapted for ejection
from the distal end; a coil on the distal end, and leads extending along
catheter to the coil for applying a current to the coil to magnetize the
distal end of the catheter to increase the responsiveness to an externally
applied magnetic field.
2. A catheter adapted for magnetic guidance inside the body, the catheter
having a proximal end, a distal end, and a lumen therebetween, a magnetic
material in the lumen adjacent the distal end and adapted for ejection
from the distal end; a coil on the distal end, and leads extending along
catheter to the coil for selectively applying a current to the coil to
selectively block the ejection of magnetic material from the distal end of
the catheter.
3. The catheter according to claim 2 wherein the magnetic material includes
a permanent magnetic material.
4. A method of treating a vascular defect comprising:
navigating the distal end of a catheter having a lumen therein with a
magnetic embolic material in the lumen, and a coil associated with the
distal end, to the site of the vascular defect while maintaining a current
on the coil to retain the magnetic embolic material in the lumen;
ejecting the magnetic embolic material from the lumen of the catheter and
guiding with an externally applied magnetic field to form an embolus that
occludes the vascular defect;
withdrawing the distal end of the catheter while maintaining a current on
the coil to retain the magnetic embolic material in the lumen.
5. The method according to claim 4 wherein the magnetic embolic material
contains a permanent magnetic material.
6. The method according to claim 4 wherein the magnetic embolic material
contains a permeable magnetic material.
7. A method of treating a vascular defect comprising:
navigating the distal end of a catheter having a lumen therein with a
magnetic embolic material in the lumen, and a coil associated with the
distal end, to the site of the vascular defect by applying a current to
the coil to create a magnetic moment at the distal end of the catheter and
using an externally applied magnetic field to orient the distal end of the
catheter;
ejecting the magnetic embolic material from the lumen of the catheter, and
applying a magnetic field to guide the ejected material to form an embolus
that occludes the defect.
8. The method according to claim 7 wherein the current to the coil is
reduced before ejecting magnetic embolic material from the lumen.
9. The method according to claim 7 wherein the magnetic field to guide the
ejected material is applied before the material is ejected.
10. The method according to claim 7 wherein a magnetic field of a first
direction is applied and material is ejected from the lumen and wherein
thereafter a magnetic field of a second direction is applied and
additional material is ejected from the lumen.
11. The method according to claim 7 wherein gradient of the magnetic field
at the site of the vascular defect is perpendicular to the direction of
the magnetic field.
12. The method according to claim 7 wherein the gradient of the magnetic
field at the site of the vascular defect is parallel to the direction of
the magnetic field.
13. The method according to claim 7 wherein the intensity of the magnetic
field is reduced as the magnetic embolic material is ejected.
14. A method of treating a vascular defect comprising:
navigating the distal end of a catheter having a lumen therein with a
magnetic embolic material in the lumen, and a coil associated with the
distal end, to the site of the vascular defect;
ejecting the magnetic embolic material from the lumen of the catheter and
guiding with an externally applied magnetic field to form an embolus that
occludes the vascular defect;
applying a current to the coil to selectively draw excess ejected magnetic
embolic material back into catheter.
15. A method of treating a vascular defect, comprising:
navigating the distal end of a catheter having a lumen to the site of the
vascular defect;
deploying a magnetic patch from the distal end of the catheter;
applying a magnetic field to the deployed patch to urge the patch against
the vascular defect.
16. The method according to claim 15 wherein the patch comprises a flexible
sheet material, and a resilient hoop which extends the flexible sheet
material.
17. A method of treating an aneurysm defect, comprising:
navigating the distal end of a catheter having a lumen into the aneurysm;
deploying a magnetic patch from the distal end of the catheter into the
aneurysm;
applying a magnetic field to the deployed patch to urge the patch against
the opening of the aneurysm to close the aneurysm.
18. The method according to claim 17 wherein the patch comprises a flexible
sheet material, and a resilient hoop which extends the flexible sheet
material.
19. A method of treating an aneurysm, the method comprising:
navigating the distal end of a catheter through the vasculature and into
the aneurysm;
deploying a magnetic patch from the distal end of the catheter into the
aneurysm;
applying a magnetic field to the aneurysm to urge the magnetic patch
against the opening of the aneurysm.
20. The method of treating an aneurysm according to claim 19 wherein the
patch comprises a flexible sheet material, and a resilient hoop which
extends the flexible sheet material.
21. A method of treating an aneurysm that opens to a blood vessel through a
neck, the method comprising:
navigating the distal end of a catheter through the vasculature and into
the neck of the aneurysm;
ejecting a coil, having a proximal end and a distal end and a magnet on the
distal end, through the distal end of the catheter by pushing the coil
with a guide inside the lumen of the catheter, the guide having a magnet
on its distal end for magnetically engaging the magnet on the proximal end
of the coil;
applying a magnetic force to the juncture between the coil and the guide to
break the magnetic engagement between the coil and the guide, and release
the coil into the aneurysm.
22. A method of treating an aneurysm that opens to a blood vessel through a
neck, the method comprising:
navigating the distal end of a catheter through the vasculature and into
the neck of the aneurysm; the catheter having a first coil, having a
proximal end and a distal end and a magnet on the distal end, at least one
intermediate coil, each intermediate coil having a proximal end and a
distal end, and a magnet on each end; the magnets on adjacent ends of
adjacent coils magnetically engaging each other, and the guide having a
magnet on its distal end for magnetically engaging the magnet on the
proximal end of the most proximal intermediate coil;
ejecting the first coil and at least one intermediate coil from the distal
end of catheter;
applying a magnetic force to the juncture with the ejected coils to break
the magnetic engagement between the coil and the guide, and release the
coil into the aneurysm.
Description
FIELD OF THE INVENTION
This invention relates to methods of and apparatus for treating vascular
defects, such as aneurysms and atriovenous malformations, and in
particular a method and related apparatus for treating such defects with
magnetically manipulated objects and materials.
BACKGROUND OF THE INVENTION
There are many types of vascular defects that can be treated by blocking
the defect. One example of such a defect is an aneurysm, which is a
permanent, abnormal blood-filled dilatation or ballooning of a blood
vessel that may be congenital or the result of disease. Aneurysms
typically have thin walls vulnerable to rupture. If an aneurysm ruptures,
the resulting hemorrhage that can put injurious pressure on surrounding
tissue, impair downstream blood flow, and even cause death. Another
example of a vascular defect is an atriovenous malformation--a typically
congenital shunt formed between an artery and a vein that often carries a
substantial blood flow. One of the principal complications in treating
these and other vascular defects is the blood flow in the adjacent vessels
which impairs treatment, but should be maintained for the health of the
patient.
Current treatments for aneurysms include embolizing the aneurysm to remove
the dilatation or balloon from the wall of the vessel. In the most mature
technique, the surgeon accesses the region of the aneurysm under direct
visualization and places one or more aneurysm clips on the opening or
"neck" of the aneurysm. While this conventional surgical technique has a
high rate of success, it is highly invasive and for that reason it is
undesirable. More recently, less invasive techniques have been developed
for the treatment of aneurysms. One such technique involves the
introduction of small wire coils into the aneurysm. A catheter is
navigated to the site of the aneurysm, and the coils are delivered through
the lumen of the catheter into the aneurysm. The coils reduce the blood
flow through the aneurysm, which results in clotting within the aneurysm.
This coiling procedure can be time consuming both in navigating the
catheter through the vasculature to the site of the aneurysm, and in
introducing the coils into the aneurysm. In some cases, the shape of the
aneurysm allows the coils to escape from the aneurysm, requiring the coil
to be retrieved and replaced.
Another less invasive technique for treating vascular defects is the
delivery of embolic materials to the site of the vascular defect to
occlude the defect. In the case of an aneurysm a balloon is inflated over
the neck of the aneurysm and a liquid embolic agent is introduced into the
aneurysm. Attempts have been made to deliver embolic agents directly into
the dilation or balloon of the aneurysm. Embolic agents have also been
used to occlude atriovenous malformations, but it can be difficult to
accurately deliver the embolic agents. In one of the more common
procedures a catheter is navigated to the site of the atriovenous
malformation and particles of polyvinyl alcohol with sizes selected for
the particular application are introduced. This procedure requires
guessing at the proper size of the particles and there is limited control
over the placement of the particles, which upon release follow the path of
greatest flow.
SUMMARY OF THE INVENTION
The present invention provides improved methods and related devices for
treating vascular defects. According to one aspect of this invention,
various magnetic objects are provided that can be delivered
intravascularly through a catheter and which can be guided into and/or
held in place in the vascular defect with an applied magnetic field. One
embodiment of these magnetic objects includes magnetic coils. These coils
may either be magnetic, or include magnetic elements. Another embodiment
of these magnetic objects includes a magnetic patch, adapted to cover the
vascular defect. The magnetic patch may include a hoop for ensuring that
the patch is fully deployed.
In another aspect of this invention, a catheter is provided for delivering
the magnetic objects and materials of the present invention. The catheter
has a proximal end and a distal end, and lumen therebetween. There is a
coil at the distal end, and leads extending along the catheter by which a
current can be selectively applied to the coil at the distal end 26 of the
catheter. Current can be selectively applied to the coil on the distal end
of the catheter to selectively enhance the magnetic responsiveness of the
distal end of the catheter so that it can be navigated in the body with an
externally applied magnetic field, but the coil can be disconnected from
current so that the coil does not interfere with the delivery of magnetic
objects or magnetic materials through the lumen. The magnetism created by
the current in the coil is enhanced by the presence of the magnetic
objects or the magnetic material in the lumen of the catheter. The coil
can also be energized to help retain magnetic materials in the lumen of
the catheter. A second coil may be provided on the catheter to enhance
magnetic responsive and to enhance the ability to retain magnetic
materials in the lumen. In another embodiment, lateral coils (as opposed
to circumferential coils) are provided in the sidewall of the catheter.
These coils facilitate movement of the distal end 26 of the catheter, for
example when it is n the opening of an aneurysm.
Thus, the method and devices of the present invention allows a catheter to
be brought to the procedure site through magnetically assisted navigation,
but the catheter can remain at the site as a further magnetic procedure,
such as the magnetic delivery of magnetic objects and magnetic materials,
is conducted.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation view of a first embodiment of a magnetic coil
constructed according to the principles of this invention;
FIG. 2A is a side elevation view of the magnetic coil of the first
embodiment shown as it is being inserted in an aneurysm without an
externally applied magnetic field;
FIG. 2B is a side elevation view of the magnetic coil of the first
embodiment shown as it is being inserted in an aneurysm with an externally
applied magnetic field in accordance with the present invention;
FIG. 3 is a side elevation view of a second embodiment of a coil with a
magnetic element constructed according to the principles of this
invention;
FIG. 4A is a side elevation view of the coil of the second embodiment shown
as it is being inserted into an aneurysm without an externally applied
magnetic field;
FIG. 4B is a side elevation view of the coil of the second embodiment shown
as it is being inserted into an aneurysm with an externally applied
magnetic field;
FIG. 5 is a side elevation view of a third embodiment of a coil with two
magnetic elements constructed according to the principles of this
invention;
FIG. 6A is a side elevation view of the coil of the third embodiment shown
as it is being inserted in an aneurysm without an externally applied
magnetic field;
FIG. 6B is a side elevation view of the coil of the third embodiment shown
as it is being inserted in an aneurysm with an externally applied magnetic
field;
FIG. 7 is a longitudinal cross-sectional view of a catheter and push wire
combination adapted for delivery coils in accordance with the principles
of the present invention;
FIG. 8 is a perspective view of a fourth embodiment of a coil constructed
according to the principles of this invention;
FIG. 9A is a longitudinal cross-sectional view of a catheter adapted for
delivering the coil of the fourth embodiment, prior to delivery of the
coil;
FIG. 9B is a longitudinal cross-sectional view of a catheter adapted for
delivering the coil of the fourth embodiment, subsequent to delivery of
the coil;
FIG. 10 is a top plan view of a magnetic patch constructed according to the
principles of this invention;
FIG. 11 is a cross-sectional view of a the patch taken along the plane of
line 8--8 in FIG. 7;
FIG. 12A is a side elevation view of the patch deployed in an aneurysm;
FIG. 12B is a perspective view of an alternate apparatus for deploying the
patch;
FIG. 13 is a cross-sectional view of the aneurysm, showing the patch
occluding the opening of the aneurysm;
FIG. 14 is a cross-sectional view of a magnetic pellet constructed
according to the principles of this invention;
FIG. 15 is a side elevation view of a catheter incorporating a coil in the
distal end in accordance with the principles of this invention;
FIG. 16 is a longitudinal cross-sectional view of the catheter shown in
FIG. 15;
FIG. 17 is a side elevation view of a catheter incorporation two coils in
the distal end 26 in accordance with a first alternate embodiment.
FIG. 18 is a transverse cross-sectional view of a catheter incorporating
three coils in the distal end in accordance with a second alternative
embodiment;
FIG. 19 is a side elevation view of the second alternative embodiment of a
catheter;
FIG. 20 is a side elevation view of the second alternative embodiment of
the catheter shown as it could be positioned in the neck of an aneurysm;
FIG. 21A is a perspective view of a catheter constructed according to the
principles of this invention; and
FIG. 21B is a perspective view of the split rectangular coil incorporated
into the catheter of FIG. 21A.
Corresponding reference numerals indicate corresponding parts throughout
the several views of the drawings.
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of a magnetic coil constructed according to the
principles of this invention is indicated generally as 20 in FIG. 1. The
magnetic coil 20 is preferably made from a permeable magnetic material,
such as 400 series stainless steel of Hiperco.TM. wire, or some other
suitable material. The magnetic coil 20 could also be made from a
permanent magnetic material, such as a combination of neodymium iron boron
powder in a polymer binder. The magnetic coil 20 preferably has a length
of between about 20 mm and about 200 mm, and a diameter of between about
0.010 inches and about 0.018 inches.
As shown in FIG. 2, the magnetic coil 20 is delivered to the site of the
vascular defect in the patient, in this case an aneurysm, inside a
catheter 22. The catheter 22 may be a conventional catheter having a
proximal end, a distal end 26, and a lumen extending therebetween. The
distal end 26 of the catheter 22 is navigated to the aneurysm, for example
using a guide wire. Once at the site of the aneurysm, the coil 20 is then
ejected from the distal end 26 of the catheter 22. A magnetic field, as
indicated by arrows B, is applied at the site of the aneurysm to draw the
coil 20 into the aneurysm. (The magnetic gradient is preferably parallel
to the magnetic field). The coil 20 is advanced from the distal end 26 of
the catheter 20, and in contrast to when no magnetic field is applied as
shown in FIG. 2A, the application of the magnetic field helps keep the
coil within the aneurysm as shown in FIG. 2B, so that the coil 20 coils
upon itself in the aneurysm. Additional coils 20 may be inserted in the
aneurysm until the aneurysm is substantially filled, and blood flow in the
aneurysm is reduced. This allows clotting in the aneurysm. Eventually the
aneurysm is completely occluded.
A second embodiment of a magnetic coil constructed according to the
principles of this invention is indicated generally as 30 in FIG. 3. The
magnetic coil is preferably made from a nonmagnetic material, such as
platinum, or some other suitable material. The magnetic coil 30 preferably
has a length of between about 20 mm and about 200 mm, and a diameter of
between about 0.010 inches and about 0.018 inches. The magnetic coil 30
has first and second ends 32 and 34. A magnetic element 36 is secured at
the first end 32 of the coil 30. The magnetic element 36 can be a
magnetically permeable material such as Hiperco.TM. or cold rolled steel.
The magnetic element 36 may also be a permanent magnetic material, such as
Neodymium Iron Boron.
As shown in FIG. 4, the magnetic coil 30 is delivered to the site of the
vascular defect in the patient, in this case an aneurysm, inside a
catheter 22. Once at the site of the aneurysm, the first end 32 of the
coil 30 is ejected from the distal end 26 of the catheter. A magnetic
field, indicated by arrows B, is applied at the site of the aneurysm to
draw the coil 30 into the aneurysm. (The magnetic gradient is preferably
parallel to the magnetic field). The coil 30 is advanced from the distal
end 26 of the catheter 22, and in contrast to when no magnetic field is
applied as shown in FIG. 4A, the application of the magnetic field helps
steer the end of the coil within the aneurysm as shown in FIG. 4B, so that
the coil 30 coils upon itself in the aneurysm. Additional coils 30 may be
inserted in the aneurysm until the aneurysm is substantially filled, and
blood flow in the aneurysm is reduced.
A third embodiment of a magnetic coil constructed according to the
principles of this invention is indicated generally as 40 in FIG. 5. The
magnetic coil 40 is preferably made from a nonmagnetic material, such as
platinum, or some other suitable material. The magnetic coil 40 preferably
has a length of between about 20mm and about 200 mm, and a diameter of
between about 0.010 inches and about 0.018 inches. The magnetic coil 40
has first and second ends 42 and 44. A magnetic element 46 is secured to
the first end 42, and a magnetic element 48 is secured to the second end
44. The magnetic elements 46 and 48 can be a magnetic permeable material
such as Hiperco.TM. or cold rolled steel. The magnetic elements 46 and 48
may also be a magnetic material, such as Neodymium Iron Boron. The
magnetic elements 46 and 48 allow the coils 40 to be joined end to end in
the lumen 28 of the catheter 22. This allows the coils to be delivered
into the aneurysm in a continuous strand, if desired.
As shown in FIG. 6, a series of magnetic coils 40 is delivered to the site
of the vascular defect in the patient, in this case an aneurysm, inside a
catheter 22. Once at the site of the aneurysm, the first end 42 of the
distal most coil 40 is ejected from the distal end 26 of the catheter 22.
A magnetic field indicated by arrows B, is applied at the site of the
aneurysm to draw the coil 40 into the aneurysm. (The magnetic gradient is
preferably parallel to the magnetic field). The coils 40 are advanced from
the distal end 26 of the catheter 22, and in contrast to when no magnetic
field is applied as shown in FIG. 6A, the application of the magnetic
field helps steer the ends 42 and 49 of the coil 40 within the aneurysm as
shown in FIG. 6B, so that the coil 40 coils upon itself in the aneurysm.
Additional coils 40 may be inserted in the aneurysm, either as a
continuous strand, or separately until the aneurysm is substantially
filled, and blood flow in the aneurysm is reduced. Adjacent coils 40 can
be separated by changing the direction of the magnetic field or gradient
to separate the adjacent coils.
The distal end of a catheter 50 for delivering the coil 40 is shown in FIG.
7. The catheter 50 could also be used to deliver coils 20 or 30 or any of
the other magnetic objects of the present invention. The catheter 50 has a
proximal end, a distal end 52, and a central lumen 54 therein. A push wire
56 is disposed in the lumen 54. The push wire 56 has a magnet 58 on its
distal end. The push wire 56 also has a coil 60 on its distal end,
generally surrounding the magnet 58. Leads 62 and 64 extend proximally
from the coil 60, allowing the coil to be selectively connected to a power
supply. The magnet 58 on the distal end of the push wire 56 magnetically
engages the magnet 48 on the second end 44 of the coil 40, allowing the
push wire 56 to push the coil 40 out of the lumen 54 of the catheter 50.
Once the coil 40 has been pushed out of the catheter 50, then the coil 60
can be energized, to neutralize the magnetic attraction between the magnet
58 and the magnet 48 on the second end 44 of the coil 40, to thereby
release the coil 40.
A fourth embodiment of a coil constructed according to the principles of
this invention is indicated generally as 70 in FIG. 8. Coil 70 comprises a
coil section 72, and has a having a first end 74 and a second end 76.
There is a magnet 78 at the first end 74, and a magnet 80 on the second
end 76. The magnets 78 and 80 are preferably tube-shaped.
The distal end of a catheter 90 for delivering the coil 70 is shown in
FIGS. 9A and 9B. The catheter 90 has a proximal end, a distal end 92. The
catheter 90 has a central lumen 94 with a circular cross-section,
surrounded by an annular lumen 96. The distal end of the annular lumen 96
is resiliently closed with a flap 98. A push wire 100 having a magnet 102
on its distal end 104, can slide in the central lumen 94. As show in FIG.
9A, the magnet 102 magnetically engages the magnet 80 on the second end 76
of the coil 70. The push wire 100 can be advanced distally in the lumen
which pushes the coil 70 distally out of the distal end of the lumen 96.
Once the coil 70 has been pushed out of the lumen 96, the flaps 98 close
behind it. As shown in FIG. 9B, when the push wire 90 is drawn proximally
back into the central lumen 94, the flaps 98 separate the coil 70 from the
push wire 100.
A magnetic patch 120 constructed according to the principles of this
invention is shown in FIGS. 10 and 11. The patch 120 is made from a highly
flexible material such as silicone or polyurethane, or some other suitable
material. In some embodiments it may be desirable to make the patch from a
bioadsorbable material. In the preferred embodiment the patch 120 includes
a hoop 122 of nitinol "memory" wire, which allows the patch to be
compressed to be delivered through the lumen of a catheter or by being
wrapped around the distal end of the catheter. The hoop 122 causes the
patch 120 to open to its normal (preferably round) shape. Of course some
other structure or construction can be provided to cause the patch to
assume its extended configuration. The patch 120 includes magnet material,
for example particles of a magnetically responsive material or magnetic
wire mesh. The magnetically responsive material may be a permeable
magnetic material or it may be a permanent magnetic material. For example
food grade iron particles of between about 0.05 .mu.m and about 50 .mu.m.
As shown in FIG. 12A, the patch is delivered to the interior of the
aneurysm. This is conveniently done by navigating the distal end 26 of the
catheter 22 into the aneurysm. The patch 120 is then deployed from the
lumen of the catheter 22, and the hoop 122 causes the patch 120 to open to
its full shape. Alternatively, as shown in FIG. 12B, the patch could be
delivered wrapped on the outside of the distal end portion of the catheter
22, and retained thereon by a retractable sheath 126. The catheter 22 is
navigated to the site of the vascular defect and the sheath 126 retracted
distally to release the patch 120 at the site of the defect. A magnetic
field, indicated as arrows B, is then applied to the patch 120 to urge the
patch against the interior of the neck of the aneurysm, as shown in FIG.
13. Preferably a transverse magnetic gradient (gradient perpendicular to
the field direction) is applied, with the patch 120 being magnetized along
a long axis (along its surface) and the transverse gradient pulling the
patch parallel to its thickness. The edge margins 124 of the patch 120
preferably have a wettable adhesive thereon, such as a hydrogel, cellulose
ether, collagen, or even cyanoacrylate so that the edge margins of the
patch adhere to the margins of the interior of the aneurysm surrounding
the neck or opening of the aneurysm. Alternatively, the edge margins 124
of the patch 120 may have an adhesive activated by some other agent, such
as a chemical agent, ultraviolet light, or laser. Thus the patch 120
covers the opening of the aneurysm. The patch can also have growth
promoting substances on its surface, such as Vascular Endothelial Growth
Factor (VEGF) promote growth of epithelial cells over the patch to close
covered aneurysm opening.
The patch 120 could also be used to cover injured sections on the inside
walls of the patient's vasculature. In this use, the patch might contain
agents which promote healing and/or tissue growth, such as VEGR and even
cells. The patch 120 could be applied to sites of plaque rupture, or to
sites of intra-vascular therapy such as angioplasty or atherectomy. A
patch 120 can be applied to one side of a blood vessel, while being held
in place by a transverse gradient field, or multiple patches could be
applied sequentially around the inside circumference of a blood vessel by
successive rotating the field gradient direction. In this latter case, the
patches would collectively form a continuous interior wall reinforcement,
like a stent. This stent could be adsorbable over time by the body, and
contain agents which promote healing of the arterial wall.
As shown in FIG. 14 the magnetic object can also be a pellet 130 comprising
magnetically responsive particle 132, with a coating 134 of a
biocompatible material such as polyvinyl alcohol. The magnetically
responsive particle 132 may be iron and preferably has a diameter of
between about 1 .mu.m and about 500 .mu.m. With the coating 134, the
pellet preferably has a diameter of between about 100 .mu.m and about 1000
.mu.m. The pellets 130 can be delivered from the lumen of a catheter
navigated to the site of the vascular defect. A magnetic field can be
applied from an external source magnet to guide the pellets 130 into a
particular branch of an atriovenous malformation, and hold them in place
to occlude the malformation.
In accordance with the methods of this invention, magnetic fields are used
to deploy and place magnetic objects and magnet materials to treat
vascular defects. However this means that magnetic navigation techniques
generally cannot be used to navigate the delivery catheter, because
magnetizing the distal end 26 of the catheter would interfere with the
delivery of the magnetic objects. However, in accordance with another
aspect of this invention, and as shown in FIGS. 15 and 16, a catheter 150,
having a proximal end 152, a distal end 154, and a lumen 156 therebetween,
is provided with a coil 158 formed in its distal end 154. Leads 160 and
162 extend along the wall 164 of the catheter to selectively apply an
electric current to the distal end 154 of the catheter 150. The
application of current to the coil 158 magnetizes the distal end 154 of
the catheter 150, allowing it be navigated by the application of a
magnetic field with an external source magnet. Thus with current applied
to the coil 158 via leads 160 and 162, the distal end 154 of the catheter
150 can be conveniently navigated to the site of the vascular defect by
the application of a magnetic field, or with the assistance from an
applied magnetic field. While the magnetic objects in the lumen 156 are
not sufficiently responsive to allow magnetic navigation of the catheter
150 containing them, magnetic objects or magnetic material in the lumen,
together with the energized coil 158, render the catheter sufficiently
magnetically responsive so that it can be magnetically navigated or at
least navigated with magnetic assistance. The coil 158 may be 5 mm (0.200
inch) long, and comprises 5 layers, each layer having 200 turns of AWG 50
insulated copper or silver magnet wire. The magnetic material in the lumen
will typically have a .mu. ranging from about 10 to about 100. For a
magnetic material with a .mu. of 25, a current of 0.2 A will achieve a
magnetization of 1 T, which is comparable to permanent magnets used in
magnetic navigation. With a current of 0.5 A, a magnetic material in the
lumen having a .mu. of 10 will achieve a similar level of magnetization.
Currents as high as 0.5 A in this coil should not significantly raise the
local temperature, provided there is adequate blood flow for cooling.
The coil 158 in catheter 150 also facilitates the delivery of magnetic
materials, such as magnetic embolic agents. The coil 158 can be energized
to help retain the magnetic embolic material in the catheter 150 as the
catheter is navigated to and navigated from the site of the vascular
defect, functioning as a valve.
An alternative construction of catheter 150 indicated as 150' is shown in
FIG. 17. Catheter 150', in addition to having coil 158, also has coil 166,
with leads 168 and 170 extending along wall 164. The coil 166 can be
connected in series with coil 158 to enhance the magnetic effect at the
distal tip of the catheter 150'. The coil 166 can also be connected
oppositely from coil 158, so that together the coils cut off the flow of
magnetic embolic material through the lumen 156 of the catheter 150', but
the net magnetic effect distal to the catheter is negligible so that the
catheter 150' does not disturb the magnetic embolic agent that has already
been deposited.
As shown in FIGS. 18 and 19, a catheter 200, having a proximal end 202, a
distal end 204, and a lumen 206 therebetween, is provided with three coils
208, 210, and 212 formed in its distal end 204. The sidewall 214 of the
catheter 200 contains leads 216 and 218 extending to coil 208, leads 220
and 222 extending to coil 210, and leads 224 and 226 extending to coil
212. The leads allow the coils 208, 210 and 212 to be selectively
energized. The coils 208, 210, and 212 can be energized to facilitate
magnetic navigation of the distal end 204 of the catheter 200 to the
vascular defect. The coils can also be selectively energized at the site
of the vascular defect to manipulate the distal end 204 of the catheter
200 to control the delivery of a magnetic embolic agent. For example, as
shown in FIG. 20, if the catheter 200 has been navigated to an aneurysm
and is being used to deliver a magnetic embolic agent into the dilatation
or balloon of the catheter, the tip of the catheter would be pointing into
the neck of the aneurysm, and the applied magnetic field would be
preferably oriented transversely to the neck of the aneurysm, with the
gradient oriented toward the back wall of the aneurysm, to deposit the
magnetic embolic agent in layers in the aneurysm. Selectively energizing
one or more of the coils 208, 210, and 212 allows the position of the
distal end 204 of the catheter 200 to be adjusted.
The catheters 150 and 150' of the present invention also permit ejected
magnetic material to be drawn into the lumen of the catheter. By properly
energizing the coil 158, magnetic material can be magnetically drawn into
the lumen even when the viscosity of the magnetic material and small lumen
size would make it difficult or impossible to suction the material back
into the lumen. With the catheter 200' of the present invention, the coils
158 and 166 can be differentially energized to apply a force to draw in
magnetic material immediately adjacent the distal end of the catheter, and
to repel magnetic material more than a few millimeters away. This prevents
the catheter from drawing a string of material from the mass of ejected
material or otherwise disturbing the mass of ejected material.
A catheter 300 having a proximal end, a distal end 304, and a lumen 306
therebetween is shown in FIG. 21A. The wall 308 of the catheter 300 has a
coil 310 embedded therein. As shown in FIG. 21B, the coil 310 is a split
longitudinal coil. Leads 312 and 314 extend longitudinally in the wall 308
to the proximal end of the catheter 300 to permit the coil to be
selectively connected to a power supply. Catheter 300, like catheter 200
can be manipulated within an applied magnetic field by selectively
applying power to the coil 310.
An important aspect of this invention is the ability to visually monitor
the treatment process. A preferred method is the use of bi-planar
fluoroscopy to provide images of the treatment site in the patient. In
bi-planar imaging two images of the treatment site are provided from
different angles (preferably 90.degree. apart). Real time imaging has
generally not been available in prior magnetic treatment procedures
because the magnetic fields interfered with the operation of the imaging
equipment. However, the inventors have discovered that by using shielded
x-ray sources and digital imaging plates such as LAST plates, available
from Varian Medical Systems, Inc., real time imaging can be provided in
the presence of the relatively strong magnetic fields (which typically
range from about 0.01 T to 0.5 T at the treatment site) for the magnetic
treatment procedures of the present invention.
Bi-planar imaging also provides a convenient interface for physician
control of the procedure. By computer processing and display of the
images, the displays can be used by the physician to identify the current
positions of the treatment devices and the desired future positions and
orientations of the treatment devices. For example, the user can
manipulate a cursor or other indicator on the display with a mouse,
joystick, or other input device and "click" at the points to identify a
particular point. By identifying a point on each of the two bi-planar
displays the point is uniquely identified in three dimensional space. The
computer can then determine and implement the necessary movements of the
external source magnet to achieve the desired future positions and
orientations.
The physician can also identify desired field and/or gradient directions on
the displays, and the computer can then determine and implement the
necessary movements of the external source magnet or electrical current
changes in an electromagnet to achieve the desired field and/or gradient
directions.
OPERATION
In operation, a magnetic object for treating a vascular defect is delivered
by navigating the distal end of a catheter to the site of the vascular
defect. The magnetic object may or may not already be in the distal
portion of the lumen of the catheter during this navigation. In the case
of a coil 20, 30, or 40, the coil is preferably at least partly ejected
from the distal end 204 of the catheter and a magnetic field applied from
an external source magnet. The field is preferably aligned in the
direction of the opening of the aneurysm, and the gradient is preferably
toward the back wall of the aneurysm.
In the case of the magnetic coil 20, as the coil is advanced, as shown in
FIG. 28 the applied magnetic field compresses the coil, pulling it toward
the back wall of the aneurysm, and away from the open neck of the
aneurysm. As more of the coil 20 is advanced into the aneurysm. The
applied magnetic field prevents the end of the coil from snaking out the
open neck, and allows the coil to be wound inside the aneurysm to
substantially occlude the aneurysm. Additional coils 20 can be delivered
in this manner until the aneurysm is satisfactorily occluded.
In the case of the coil 30 with magnetic elements on at least one end, as
the coil is advanced, as shown in FIG. 4B the applied magnetic field
steers the magnetic element 36 on the first end 22 of the coil toward the
back wall of the aneurysm, and away from the open neck of the aneurysm.
The applied magnetic field prevents the first end 32 of the coil 30 from
snaking out the open neck, and allows the coil to be wound inside the
aneurysm to substantially occlude the aneurysm. Additional coils 30 can be
delivered in this manner until the aneurysm is satisfactorily occluded.
In the case of the coil 40 with magnetic elements on each end, as the coil
is advanced as shown in FIG. 6B, the applied magnetic field steers the
magnetic elements 46 and 48 on the ends 42 and 44 of the coil toward the
back wall of the aneurysm, and away from the open neck of the aneurysm.
This prevents the ends of the coil from snaking out the open neck, and
allows the coil to be wound inside the aneurysm to substantially occlude
the aneurysm. The coils 40 can be inserted continuously end to end, or
each coil can be separately introduced. The coils can be separated at the
distal end of the catheter 22 by turning the magnetic field to torque the
magnetic element 48 on the proximal end 44 of the distal most coil 40 from
the magnetic element 46 on the distal end 42 of the adjacent coil. A
continuous strand of several coils 40, or several separate coils 40, can
be inserted until the aneurysm is satisfactorily occluded.
In the case of a magnetic patch 50, the catheter 22 is navigated to the
neck of the aneurysm, and the patch is introduced into the aneurysm. The
resilient hoop 52 causes the patch to expand to its normal flat
configuration. The blood present in the aneurysm wets the adhesive on the
edge margins 54 of the patch 50. A magnetic field is applied to the
aneurysm to urge the patch 50 against the opening of the aneurysm. The
magnetic field helps to hold the patch 50 in place until the patch is
secured, occluding the opening of the aneurysm.
In the case of the magnetic pellets 60, the catheter 22 is navigated to the
site of the vascular defect and the pellets are released from the distal
end 26 of the catheter. A magnetic field is applied to the vascular
defect, in a direction of the branch to be occluded. The pellets 60 align
in the direction of the applied magnetic field and travel in the direction
of the applied gradient to occlude the vascular defect.
In the case of a magnetic embolic agent, the catheter is navigated to the
site of the vascular defect. A magnetic field is applied and the magnetic
embolic agent is ejected from the distal end of the catheter. The magnetic
field rigidfies the ejected magnetic embolic agent. Thus, the magnetic
field can be applied to rigidify the magnetic embolic agent and hold its
shape until the magnetic embolic agent hardens on its own. A long rigid
plug can be extruded from the catheter for occluding an atriovenous
malformation. The applied magnetic field rigidifies and helps the plug
retain its shape as the plug is advanced into the atriovenous
malformation.
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