U.S. patent application number 11/761123 was filed with the patent office on 2008-01-17 for single disc occlusionary patent foramen ovale closure device.
Invention is credited to Rudolph Cedro, Chao-Chin Chen, Randy David B. Grishaber, John O'Brien, Daniel Olsen.
Application Number | 20080015635 11/761123 |
Document ID | / |
Family ID | 38668837 |
Filed Date | 2008-01-17 |
United States Patent
Application |
20080015635 |
Kind Code |
A1 |
Olsen; Daniel ; et
al. |
January 17, 2008 |
SINGLE DISC OCCLUSIONARY PATENT FORAMEN OVALE CLOSURE DEVICE
Abstract
The present invention is a method and device for closing a
passageway in a body, for example a patent foramen ovale (PFO) in a
heart, and related methods of using such closure devices for
closing the passageway.
Inventors: |
Olsen; Daniel; (Wharton,
NJ) ; Grishaber; Randy David B.; (Asbury, NJ)
; Chen; Chao-Chin; (Edison, NJ) ; Cedro;
Rudolph; (Clinton, NJ) ; O'Brien; John;
(Piscataway, NJ) |
Correspondence
Address: |
PHILIP S. JOHNSON;JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
NEW BRUNSWICK
NJ
08933-7003
US
|
Family ID: |
38668837 |
Appl. No.: |
11/761123 |
Filed: |
June 11, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60804376 |
Jun 9, 2006 |
|
|
|
Current U.S.
Class: |
606/213 ;
606/216 |
Current CPC
Class: |
A61B 2017/0437 20130101;
A61B 2017/00862 20130101; A61B 17/0057 20130101; A61B 2017/00575
20130101; A61B 2017/0464 20130101; A61B 2017/0412 20130101; A61B
2017/00592 20130101; A61B 2017/00579 20130101; A61B 2017/00615
20130101 |
Class at
Publication: |
606/213 ;
606/216 |
International
Class: |
A61D 1/00 20060101
A61D001/00 |
Claims
1. A medical device for closing a passageway in a body comprising:
a closure line having a first and a second end; an expandable
tissue anchor connected to the first end of the closure line, the
tissue anchor being adapted to pierce into tissue within close
approximation to the passageway and subsequently expand to embed
into the tissue; and an expandable flow occluder located along the
second end of the closure line, the expandable flow occluder having
a locking mechanism integrated therein, the locking mechanism
allowing the closure line to uni-axially slide through the
expandable flow occluder in one direction, and prevent sliding
movement in the opposite direction.
2. The medical device of claim 1 wherein the closure line is
elastic.
3. The medical device of claim 1 wherein the closure line is a
biocompatible filament.
4. The medical device of claim 3 wherein the biocompatible filament
is a surgical suture.
5. The medical device of claim 4 wherein the surgical suture is a
multifilament non-biodegradable suture.
6. The medical device of claim 4 wherein the surgical suture is a
forced entangled fiber filament.
7. The medical device of claim 1 wherein at least one of the
expandable tissue anchor or expandable flow occluder are made from
a structurally deformable material.
8. The medical device of claim 1 wherein the expandable tissue
anchor has a needle-like tip configured to pierce the tissue and at
least one barb extending in a substantially radial outward
direction to anchor into the tissue.
9. The medical device of claim 1 wherein the expandable tissue
anchor and expandable flow occluder are self-expanding members.
10. The medical device of claim 1 wherein the expandable flow
occluder is covered with a biocompatible fabric.
11. The medical device of claim 10 wherein the biocompatible fabric
is made from a non-biodegradable polymeric fabric.
12. The medical device of claim 10 wherein the biocompatible fabric
is made from a biodegradable polymeric fabric.
13. The medical device of claim 12 wherein the biodegradable
polymeric fabric resorbs into the body as a function of time.
14. The medical device of claim 12 wherein the biodegradable
polymeric fabric resorbs into the body as a function of applied
stress.
15. The medical device of claim 12 wherein the biodegradable
polymeric fabric resorbs into the body as a function of time and
applied stress.
16. The medical device of claim 1 wherein the expandable tissue
anchor and expandable flow occluder are made from a super elastic
material.
17. The medical device of claim 16 wherein the super elastic
material is a nickel titanium alloy.
18. The medical device of claim 16 wherein the super elastic
material is a resilient polymer.
19. The medical device of claim 16 wherein the super elastic
material is an elastically compressed spring temper biocompatible
metal.
20. The medical device of claim 1 wherein the expandable tissue
anchor and expandable flow occluder are mechanically
expandable.
21. The medical device of claim 20 wherein the expandable tissue
anchor and expandable flow occluder are made from a plastically
deformable material.
22. The medical device of claim 21 wherein the plastically
deformable material is spirally wound stainless steel.
23. A method of closing a passageway in a body, the passageway
having a first and a second open end, comprising: locating a distal
end of a closure device adjacent to the passageway, the closure
device having a closure line with proximal and distal ends, an
expandable tissue anchor located along the distal end of the
closure line, and an expandable occluder member located along the
proximal end of the closure line; deploying the expandable tissue
anchor into tissue adjacent to the passageway; deploying the
expandable occluder member adjacent to the passageway such that the
expandable occluder member substantially covers the second opening
to the passageway.
24. The method of claim 23 wherein deploying the expandable tissue
anchor further comprises piercing a surface of the tissue with the
expandable tissue anchor and expanding the tissue anchor within the
tissue.
25. The method of claim 23 wherein deploying the expandable
occluder member adjacent to the passageway comprises expanding the
occluder member from a first configuration to a second
configuration, and tensioning the occluder against the tissue to
substantially cover the passageway.
26. The method of claim 26 wherein tensioning the occluder against
the tissue comprises unilaterally displacing the occluder distally
along the closure line.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application, Ser. No. 60/804,376, filed Jun. 9, 2006, which is
incorporated by reference herein.
FIELD OF THE INVENTION
[0002] This invention relates to devices for closing a passageway
in a body, for example a patent foramen ovale (PFO) in a heart, and
related methods of using such closure devices for closing the
passageway.
BACKGROUND OF THE INVENTION
[0003] Patent foramen ovale (PFO) is an anatomical interatrial
communication with potential for right-to-left shunting of blood.
Foramen ovale has been known since the time of Galen. In 1564,
Leonardi Botali, an Italian surgeon, was the first to describe the
presence of foramen ovale at birth. However, the function of
foramen ovale in utero was not known at that time. In 1877,
Cohnheim described paradoxical embolism in relation to patent
foramen ovale.
[0004] Patent foramen ovale is a flap-like opening between the
atrial septa primum and secundum at the location of the fossa
ovalis that persists after age one year. In utero, the foramen
ovale serves as a physiologic conduit for right-to-left shunting of
blood in the fetal heart. After birth, with the establishment of
pulmonary circulation, the increased left atrial blood flow and
pressure presses the septum primum (SP) against the walls of the
septum secundum (SS), covering the foramen ovale and resulting in
functional closure of the foramen ovale. This closure is usually
followed by anatomical closure of the foramen ovale due to fusion
of the septum primum (SP) to the septum secundum (SS).
[0005] Where anatomical closure of the foramen ovale does not
occur, a patent foramen ovale (PFO) is created. A patent foramen
ovale is a persistent, usually flap-like opening between the atrial
septum primum (SP) and septum secundum (SS) of a heart. A patent
foramen ovale results when either partial or no fusion of the
septum primum (SP) to the septum secundum (SS) occurs. In the case
of partial fusion or no fusion, a persistent passageway (PFO track)
exists between the septum primum (SP) and septum secundum (SS).
This opening or passageway is typically parallel to the plane of
the septum primum, and has a mouth that is generally oval in shape.
Normally the opening is relatively long, but quite narrow. The
opening may be held closed due to the mean pressure in the left
atrium (LA) being typically higher than in the right atrium (RA).
In this manner, the septum primum acts like a one-way valve,
preventing fluid communication between the right and left atria
through the PFO track. However, at times, the pressure may
temporarily be higher in the right atrium, causing the PFO track to
open up and allow some fluid to pass from the right atrium to the
left atrium. Although the PFO track is often held closed, the
endothelialized surfaces of the tissues forming the PFO track
prevent the tissues from healing together and permanently closing
the PFO track.
[0006] Studies have shown that a relatively large percentage of
adults have a patent foramen ovale (PFO). It is believed that
embolism via a PFO may be a cause of a significant number of
ischemic strokes, particularly in relatively young patients. It has
been estimated that in 50% of cryptogenic strokes, a PFO is
present. Blood clots that form in the venous circulation (e.g., the
legs) can embolize, and may enter the arterial circulation via the
PFO, subsequently entering the cerebral circulation, resulting in
an embolic stroke. Blood clots may also form in the vicinity of the
PFO, and embolize into the arterial circulation and into the
cerebral circulation. Patients suffering a cryptogenic stroke or a
transient ischemic attack (TIA) in the presence of a PFO often are
considered for medical therapy to reduce the risk of a recurrent
embolic event.
[0007] Pharmacological therapy often includes oral anticoagulants
or antiplatelet agents. These therapies may lead to certain side
effects, including hemorrhage. If pharmacologic therapy is
unsuitable, open heart surgery may be employed to close a PFO with
stitches, for example. Like other open surgical treatments, this
surgery is highly invasive, risky, requires general anesthesia, and
may result in lengthy recuperation.
[0008] Nonsurgical closure of a PFO is possible with umbrella-like
devices developed for percutaneous closure of atrial septal defects
(ASD) (a condition where there is not a well-developed septum
primum (SP)). Many of these conventional devices used for ASD,
however, are technically complex, bulky, and difficult to deploy in
a precise location. In addition, such devices may be difficult or
impossible to retrieve and/or reposition should initial positioning
not be satisfactory. Moreover, these devices are specially designed
for ASD and therefore may not be suitable to close and seal a PFO,
particularly because the septum primum (SP) overlaps the septum
secundum (SS).
SUMMARY OF THE INVENTION
[0009] The present invention relates to devices for closing a
passageway in a body, for example a patent foramen ovale (PFO) in a
heart, and related methods of using such closure devices for
closing the passageway. The closure device includes a closure line
having a first and a second end. A first expandable member is
connected to the first end of the closure line. A second expandable
member is located along the second end of the closure line, and is
capable of sliding along the closure line in one direction while
preventing sliding movement in the opposite direction.
Alternatively the second expandable member is fixed along the
second end of the closure line.
[0010] Another embodiment of the invention includes a closure line
having a first and a second end. An expandable tissue anchor is
connected to the first end of the closure line, the tissue anchor
being adapted to pierce into tissue within close approximation to
the passageway and subsequently expand to embed into the tissue. An
expandable flow occluder is located along the second end of the
closure line, the expandable flow occluder having a locking
mechanism integrated therein. The locking mechanism allows the
closure line to uni-axially slide through the expandable flow
occluder in one direction, and prevent sliding movement in the
opposite direction.
[0011] Another embodiment of the invention includes a method for
closing a passageway in a body, the passageway having a first and a
second open end. The method includes locating a distal end of a
closure device adjacent to the passageway, the closure device
having a closure line with proximal and distal ends, an expandable
tissue anchor located along the distal end of the closure line, and
an expandable occluder member located along the proximal end of the
closure line. The expandable tissue anchor is deployed into tissue
adjacent to the passageway. The expandable occluder member is
deployed adjacent to the passageway such that the expandable
occluder member substantially covers the second opening to the
passageway.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a short axis view of the heart at the level of the
right atrium (RA) and the left atrium (LA), in a plane generally
parallel to the atrio-ventricular groove, and at the level of the
aortic valve, showing a PFO track.
[0013] FIG. 2 is a cross-sectional view of the PFO track of FIG. 1
in a closed configuration.
[0014] FIG. 3 is a close-up section view illustrating the PFO track
held in the closed position by left atrial pressure.
[0015] FIG. 4A is a cross-sectional view of the PFO track of FIG. 2
in an open configuration.
[0016] FIG. 4B is a close-up section view illustrating the PFO
track in an open configuration.
[0017] FIG. 5A is a cross-sectional view illustrating the PFO tract
of FIG. 1.
[0018] FIG. 5B is a section view taken along line A-A in FIG.
4B.
[0019] FIG. 5C is a section view taken along line A-A in FIG.
3.
[0020] FIG. 5D is a close-up section view of the PFO track, showing
the tunnel formed by the tissue extension.
[0021] FIG. 6A illustrates the closure device deployed with the
distal anchor member in the septum secundum, and the proximal
occluder member against the septum primum and septum secundum
substantially occluding he PFO track, according to one embodiment
of the present invention.
[0022] FIG. 6B is a close-up perspective view illustrating the
relationship between the distal anchor member, the closure line and
the proximal occluder member according to one embodiment of the
present invention.
[0023] FIG. 7A shows one embodiment of a suture locking device
integrated into the occluder member according to one embodiment of
the present invention.
[0024] FIG. 7B shows one embodiment of a suture locking device
operatively associated with a separate occluder member according to
one embodiment of the present invention.
[0025] FIG. 8A is a perspective view illustrating one an asymmetric
proximal occluder member according to one embodiment of the present
invention.
[0026] FIG. 8B is a close-up perspective view illustrating an
asymmetric proximal occluder member according to one embodiment of
the present invention.
[0027] FIG. 9 illustrates a PFO closure device deployed to close a
PFO track in the presence of an atrial septal defect according to
one embodiment of the present invention.
[0028] FIG. 10A is a section view illustrating the closure device
600 loaded into a delivery device 630 according to one embodiment
of the present invention.
[0029] FIG. 10B is a section view illustrating the closure device
600 loaded into a delivery device 630 according to another
embodiment of the present invention.
[0030] FIG. 11 is a perspective view illustrating the closure
device, wherein the distal anchor member is initially set in the
septum secundum according to one embodiment of the present
invention.
[0031] FIG. 12 illustrates the closure device in a substantially
deployed configuration according to one embodiment of the present
invention.
[0032] FIG. 13 is a perspective view of the closure device
according to one embodiment of the present invention cinched in
place.
[0033] FIG. 14A is a section view of a heart illustrating the
location of a delivery device having an axially asymmetric
expansion member as backup support feature according to one
embodiment of the present invention.
[0034] FIG. 14B is a section view of a heart illustrating the
location of a delivery device having a spine member as a backup
support feature according to one embodiment of the present
invention.
[0035] FIG. 14C is a section view of a heart illustrating the
location of a delivery device having a shaped member as a backup
support feature according to one embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0036] The various figures show embodiments of the patent foramen
ovale (PFO) closure device and methods of using the device to close
a PFO. The device and related methods are described herein in
connection with mechanically closing a PFO. These devices, however,
also are suitable for closing other openings or passageways,
including other such openings in the heart, for example atrial
septal defects, ventricular septal defects, and patent ducts
arterioses, as well as openings or passageways in other portions of
a body such as an arteriovenous fistula. The invention therefore is
not limited to use of the inventive closure devices to close
PFO's.
[0037] A human heart has four chambers. The upper chambers are
called the left and right atria, and the lower chambers are called
the left and right ventricles. A wall of muscle called the septum
separates the left and right atria and the left and right
ventricles. That portion of the septum that separates the two upper
chambers (the right and left atria) of the heart is termed the
atrial (or interatrial) septum while the portion of the septum that
lies between the two lower chambers (the right and left ventricles)
of the heart is called the ventricular (or interventricular)
septum.
[0038] FIG. 1 illustrates a short-axis view of the heart 100 at the
level of the right atrium (RA) and left atrium (LA), in a plane
generally parallel to the atrio-ventricular groove, and at the
level of the aortic valve. This view is looking from caudal to
cranial. FIG. 1 also shows the septum primum (SP) 105, a flap-like
structure, which normally covers the foramen ovale 115, an opening
in the septum secundum (SS) 110 of the heart 100. In utero, the
foramen ovale 115 serves as a physiologic conduit for right-to-left
shunting of blood in the fetal heart. After birth, with the
establishment of pulmonary circulation, the increased left atrial
blood flow and pressure presses the septum primum (SP) 105 against
the walls of the septum secundum (SS) 110, covering the foramen
ovale 115 and resulting in functional closure of the foramen ovale
115. This closure is usually followed by anatomical closure of the
foramen ovale 115 due to fusion of the septum primum (SP) 105 to
the septum secundum (SS) 110.
[0039] The PFO results when either partial or no fusion of the
septum primum 105 to the septum secundum 110 occurs. When this
condition exists, a passageway (PFO track) 120 between the septum
primum 105 and septum secundum 110 may allow communication of blood
between the atria. This PFO track 120 is typically parallel to the
plane of the septum primum 105, and has an opening that is
generally oval in shape. FIG. 2 illustrates the opening of the PFO
track 120 as viewed from an end of the track. Normally the opening
is relatively tall, but quite narrow. The opening may be held
closed by the mean pressure in the left atrium, which is typically
higher than the right atrium. FIG. 3 is a close-up section view of
the PFO track 120 held in the closed position by left atrial
pressure. In this position, the septum primum 105 acts like a
one-way valve, preventing fluid communication between the right and
left atria through the PFO track 120. Occasionally, the pressure in
the right atrium may temporarily be higher than the left atrium.
When this condition occurs, the PFO track 120 opens and allow some
fluid to pass from the right atrium to the left atrium, as
indicated in FIGS. 4A and 4B. In particular, FIG. 4A is a
cross-sectional view showing the PFO track of FIG. 2 in an open
configuration. Similarly, FIG. 4B is a close-up section view
illustrating the PFO track in an open configuration.
[0040] Although the PFO track 120 is often held closed, the
endothelialized surfaces of the tissues forming the PFO track 120
prevent the tissue from healing together and permanently closing
the PFO track 120. As can be seen in FIGS. 5A - 5C, (a view from
line "C-C" of FIG. 1), the septum primum 105 is firmly attached to
the septum secundum 110 around most of the perimeter of the Fossa
Ovalis 115, but has an opening along one side. The septum primum
105 is often connected, as shown, by two or more extensions of
tissue along the sides of the PFO track 120 forming a tunnel. FIG.
5D is a magnified section view of the PFO track 120, showing the
tunnel formed by the tissue extensions. Typically, the tunnel
length in an adult human can range between 2 and 13 mm.
[0041] The present invention relates to a system and method for
closing a passageway in a body. In a particular embodiment, the
device is used to close the Patent Foramen Ovale in a human heart.
One of ordinary skill in the art would understand that similar
embodiments could be used to close other passageways and openings
in the body without departing from the general intent or teachings
of the present invention.
[0042] FIG. 6A illustrates a device used to close the PFO according
to one embodiment of the present invention. The device 600
comprises a flexible closure line 625 coupled to two expandable
members, distal anchor member 620 and proximal occluder member 621
respectively. Anchor member 620 is an anchor coupled to the distal
end of the closure line 625, while occluder member 621 is an
expandable geometric structure coupled to the proximal end of the
flexible closure line 625. Occluder member 621 is capable of
sliding along closure line 625 and locking in desired location to
cinch or take-up slack in closure line 625 length, bringing the
proximal occluder member 621 into contact with the septal wall
comprised of septum secundum 110 and the septum primum 105 such
that blood flow to the PFO tunnel is closed off.
[0043] It should be noted that the septum secundum 110 and the
septum primum 105 do not have to be touching to effect proper
closure of the PFO. Instead, the proximal member 621 occludes flow
to the PFO track (tunnel) 120 by substantially covering the tunnel
entrance. It should also be noted that the proximal occluder member
621 may or may not be covered with a biocompatible polymeric fabric
to assist in substantially occluding blood flow. For a design in
which a fabric covering is not used, blood flow would eventually be
shunted by the heart's incorporation of the device.
[0044] The distal anchor member 620 is a tissue anchor that is
delivered into the septum secundum 110 or septum primum 105 via a
catheter delivery system and is deployed. Upon deployment, the
distal member 620 is anchored into the tissue forming the septum
secundum 110 or the septum primum 105 such that the anchor member
620 is immobile and can withstand the pull force needed to properly
seat the proximal occluder member 621 against the septal wall
without the distal anchor member 620 detaching from the septal
tissue.
[0045] In one embodiment, the distal anchor member 620 comprises a
main body having a needle like tip capable of penetrating the
septum (septum secundum 110 and/or the septum primum 105) and one
or more barbs 622 that project outward from the main body. The
characteristics of the barbs 622 are such that after delivery of
the anchor into the septum tissue, the barbs 622 extend outward in
a radial direction and prevent the distal anchor member 620 from
being withdrawn from the tissue--very similar to the barb
integrated into a fish hook.
[0046] A locking mechanism 627 is operatively incorporated into the
occluder member 621 to secure the occluder member 621 to the
closure line 625. In one embodiment, the locking member may be an
integral part of the occluder member 621, formed into the hub of
the occluder member 621. In another embodiment of the invention,
the locking mechanism 627 may be a separate component or member
functionally that although is physically a separate member, is
functionally integrated with the occluder member 621. That is to
say, the locking mechanism 627 can secure to the closure line 625
and prevent relative movement between the closure line 625 and the
occluder member 621 when the hub of the occluder member 621 comes
in contact with the locking mechanism 627.
[0047] FIG. 7A is an isometric view of an occluder member 621 with
a locking mechanism 627 integrated into the occluder member's 621
proximal end. Similarly, FIG. 7B is an isometric view of an
occluder member 621 operatively associated with a separate and
distinct locking mechanism 627 along a closure line 625. In this
embodiment, the locking mechanism 625 secures to the closure line
625, and effectively secures the occluder member 621 relative the
closure line 625 when the hub 621a of the occluder member 621 comes
in contact with the locking mechanism 627.
[0048] In one embodiment, the locking mechanism 627 allows the
closure line 625 to slide through occluder member 621 in one
direction, and prevent sliding movement in the opposite direction.
Examples of functionally similar commercial locking mechanisms
include the DePuy Mitek RAPIDLOC.TM. device; zip ties; and similar
linear locking devices known in the art. In a preferred embodiment
of the locking mechanism 627, mechanical appendage or tang 628 is
used to lock onto the closure line 625 by having small finger-like
protrusions that impinge on and push between the individual woven
strands of the closure line 625.
[0049] Alternatively, the proximal occluder member 621 may be fixed
to the closure line 625 at a predetermined distance from anchor
member 620. This may particularly be the case when the closure line
625 has an elastic or recoil ability and is capable of exerting
tension when deployed, pulling the proximal and distal members 621,
620 together and effectively compressing proximal occluder member
621 against the septal wall inside the right atrium of the heart.
In still a further embodiment of the invention, a closure device
600 may include an elastic closure line 625 and a slideable
proximal occluder member 621. In this embodiment, the occluder
member 621 is capable of allowing the flexible closure line 625 to
slide through the occluder member 621 in one direction, and prevent
sliding movement in the opposite direction, while the closure line
625 exerts tension between the proximal and distal members 621, 620
respectively. These configurations should not necessarily be
considered limiting, and other combinations of components are
contemplated, such as, for example, both members 620 and 621 being
slideable along a substantially elastic or inelastic closure line
625.
[0050] The closure line 625 may be any biocompatible filament known
in the art that is capable of securing the proximal occluder member
621 against the septum secundum 110 and septum primum 105. In a
preferred embodiment the closure line 625 is a surgical suture,
such as a multifilament non-biodegradable suture, or a forced
entangled fiber filament. Alternatively, the closure line 625 may
be made from an elastic material capable of exerting tension when
stretched.
[0051] The proximal and distal members 621, 620 respectively, are
expandable from a first, predeployed unexpanded configuration to a
second expanded configuration. The expandable members 620, 621 are
preferably constructed from a structurally deformable material.
[0052] Structurally deformable materials are materials that can
elastically or plastically deform without compromising their
integrity. Geometric structures, such as proximal and distal
members 621, 620, made from a deformable material are capable of
changing shape when acted upon by an external force, or removal or
an external force. Geometric structures made from structurally
deformable materials are typically self expanding or mechanically
expandable. In a preferred embodiment, the proximal and distal
members 621, 620 made from a self-expanding material, such as
Nitinol or a resilient polymer. However, the self-expanding members
621, 620 may also be made from elastically compressed spring temper
biocompatible metals. These self-expanding structures are held in a
constrained configuration by an external force, typically a capture
sheath, and elastically deform when the constraining force is
released.
[0053] Some structurally deformable materials may also be
mechanically expandable. Geometric structures can be mechanically
expanded by introduction of an external force, through, for
example, a mechanical expansion means. Mechanical expansion means
are well known in the art and include balloon or cage expansion
devices.
[0054] Once an external mechanical force is introduced to the
geometric structure, the structure plastically deforms to its
desired final configuration.
[0055] The proximal and distal members 621, 620 in their
constrained state are capable of being held in a restrained low
profile geometry for delivery, and assume an expanded shape that
facilitates the distal member 620 anchoring into the septal wall
(septum secundum 110 or septum primum 105) and the proximal member
621 substantially covering and occluding the PFO track 120
entrance.
[0056] In a preferred embodiment, the proximal and distal members
621, 620 are cut from a Nitinol hypotube by methods known in the
art.
[0057] Nitinol is utilized in a wide variety of applications,
including medical device applications as described above. Nitinol
or NiTi alloys are widely utilized in the fabrication or
construction of medical devices for a number of reasons, including
its biomechanical compatibility, its biocompatibility, its fatigue
resistance, its kink resistance, its uniform plastic deformation,
its magnetic resonance imaging compatibility, its ability to exert
constant and gentle outward pressure, its dynamic interference, its
thermal deployment capability, its elastic deployment capability,
its hysteresis characteristics, and is moderately radiopaque.
[0058] Nitinol, as described above, exhibits shape memory and/or
super-elastic characteristics. Shape memory characteristics may be
simplistically described as follows. A metallic structure, for
example, a Nitinol tube that is in an Austenitic phase may be
cooled to a temperature such that it is in the Martensitic phase.
Once in the Martensitic phase, the Nitinol tube may be deformed
into a particular configuration or shape by the application of
stress. As long as the Nitinol tube is maintained in the
Martensitic phase, the Nitinol tube will remain in its deformed
shape. If the Nitinol tube is heated to a temperature sufficient to
cause the Nitinol tube to reach the Austenitic phase, the Nitinol
tube will return to its original or programmed shape. The original
shape is programmed to be a particular shape by well-known
techniques.
[0059] Super-elastic characteristics may be simplistically
described as follows. A metallic structure for example, a Nitinol
tube that is in an Austenitic phase may be deformed to a particular
shape or configuration by the application of mechanical energy. The
application of mechanical energy causes a stress induced
Martensitic phase transformation. In other words, the mechanical
energy causes the Nitinol tube to transform from the Austenitic
phase to the Martensitic phase. By utilizing the appropriate
measuring instruments, one can determined that the stress from the
mechanical energy causes a temperature drop in the Nitinol tube.
Once the mechanical energy or stress is released, the Nitinol tube
undergoes another mechanical phase transformation back to the
Austenitic phase and thus its original or programmed shape. As
described above, the original shape is programmed by well know
techniques. The Martensitic and Austenitic phases are common phases
in many metals.
[0060] Medical devices constructed from Nitinol are typically
utilized in both the Martensitic phase and/or the Austenitic phase.
The Martensitic phase is the low temperature phase. A material is
in the Martensitic phase is typically very soft and malleable.
These properties make it easier to shape or configure the Nitinol
into complicated or complex structures. The Austenitic phase is the
high temperature phase. A material in the Austenitic phase is
generally much stronger than the material in the Martensitic phase.
Typically, many medical devices are cooled to the Martensitic phase
for manipulation and loading into delivery systems. When the device
is deployed at body temperature, they return to the Austenitic
phase.
[0061] Other materials that have shape memory characteristics may
also be used, for example, some polymers and metallic composition
materials. It should be understood that these materials are not
meant to limit the scope of the invention.
[0062] Once the proximal and distal members 621, 620 are cut from
the Nitinol hypotube, they are formed into a desired expanded
configuration and annealed to assume a stress-free (relaxed) state.
In one embodiment of the invention, the distal anchor member 620 is
formed into an anchor shaped configuration, having a plurality of
pointed legs with barbs 622 that can puncture and anchor in tissue.
Correspondingly, in this embodiment, the proximal member 621 is
formed into a slightly concaved woven-looking basket that could
flatten into a woven-looking disc when pulled against the septal
wall. An isomeric view of both the proximal and distal expandable
members 621, 620, respectively, according to one embodiment of the
present invention are illustrated in FIGS. 6A and 6B.
[0063] Once the closure device 600 is deployed, the distal anchor
member 620 is anchored into septal wall (septum secundum 110 or
septum primum 105) and the basket shaped occluder member 621
collapses under tensioning of the closure line 625, into a
flattened disc shape as illustrated in FIGS. 6A and 6B. In this
configuration, occluder member 621 is under strain. The super
elastic properties of the occluder member 621 under strain exert an
axially outward force against the adjacent tissue, putting the
closure line 625 in tension.
[0064] This design should not be considered a limiting feature of
the invention, as other shapes and configurations of proximal and
distal members 621, 620 are also contemplated by the present
design. These may include, for example, expandable disc design,
star design, j-hook design, or any expandable symmetric or
asymmetric geometric shape. In addition other materials exhibiting
similar characteristics, such as non-biodegradable swellable
polymers, are similarly contemplated by the present invention.
[0065] FIGS. 8A and 8B illustrate an asymmetric proximal member 621
according to another embodiment of the present invention. In the
illustrated embodiment, the proximal member 621 is asymmetric about
the hub incorporating locking mechanism 627. This asymmetry may
allow the member 621 to more closely conform the shape of the
surrounding tissue, taking advantage of the atrial anatomy.
[0066] The PFO closure device 600 can be used to facilitate closing
the PFO track 120 when other defects in the septal wall are
present. For example, the PFO closure device 600 may be used when
an atrial septal aneurysm (ASA) is present. An ASA is characterized
as a saccular deformity, generally at the level of the fossa ovale,
which protrudes to the right or left atrium, or both. FIG. 9
illustrates the PFO closure device 600 deployed to close a PFO
track 120 in the presence of an atrial septal defect.
[0067] The present invention utilizes a removable deployment device
630 to introduce the mechanical closure device 600 into the atrium
of the heart, preferably through a minimally invasive, transluminal
procedure.
[0068] FIGS. 10A and 10B are section views illustrating the closure
device 600 loaded into a delivery device 630 according to two
embodiments of the present invention. In each embodiment the
delivery device 630 includes an outer tubular structure or catheter
635 and an inner tubular structure 636. The delivery device 630 may
also include a guidewire lumen (not shown) to allow the delivery
device 630 to track over a guidewire (not shown). The inner tubular
structure 636 is slideably engaged within the outer tubular
structure 635 and acts as a "pusher" to deploy the closure device
600 from the distal end of the outer tubular structure 635. In the
embodiment illustrated in FIG. 10A, the inner tubular structure 636
is sized to push against the proximal end of the occluder 621,
causing the occluder 621 to be displaced distally, and subsequently
displacing the distal anchor member 620 from the distal end of the
outer tubular structure 635. Similarly, in the embodiment
illustrated in FIG. 10B, the inner tubular structure 636 is sized
be slideably engaged with the proximal occluder 621, and to push
against the proximal end of the distal anchor 620, causing the
distal anchor member 620 be displaced distally. As the distal
anchor 620 is distally displaced, the proximal occluder member 621
is similarly displaced--by virtue of its relative position within
the inner tubular structure 636, or alternatively, because it is
operatively connected to the distal anchor ember 620 via the
closure line 625.
[0069] Minimally invasive heart surgery refers to several
approaches for performing heart operations that are less difficult
and risky than conventional open-heart surgery. These approaches
restore healthy blood flow to the heart without having to stop the
heart and put the patient on a heart-lung machine during surgery.
Minimally invasive procedures are carried out by entering the body
through the skin, a body cavity or anatomical opening, but with the
smallest damage possible to these structures. This results in less
operative trauma for the patient. It also less expensive, reduces
hospitalization time, causes less pain and scarring, and reduces
the incidence of complications related to the surgical trauma,
speeding the recovery.
[0070] One example of a minimally invasive procedure for performing
heart surgery is a trans-thoracic laparoscopic (endoscopic)
procedure. The part of the mammalian body that is situated between
the neck and the abdomen and supported by the ribs, costal
cartilages, and sternum is known as the thorax. This division of
the body cavity lies above the diaphragm, is bounded peripherally
by the wall of the chest, and contains the heart and lungs. Once
into the thorax, the surgeon can gain access to the atrium of the
heart through an atriotomy, a surgical incision of an atrium of the
heart. For example, if the surgeon wishes to gain access to the
right atrium they will perform an atriotomy in the right atrial
appendage.
[0071] The primary advantage of a trans-thoracic laparosopic
procedure is that there is no need to make a large incision.
Instead, the surgeon operates through 3 or 4 tiny openings about
the size of buttonholes, while viewing the patient's internal
organs on a monitor. There is no large incision to heal, so
patients have less pain and recover sooner. Rather than a 6- to
9-inch incision, the laparoscopic technique utilized only 4 tiny
openings--all less than 1/2 inch in diameter.
[0072] Another minimally invasive technique for gaining access to
the heart and deploying the closure device is a percutaneous
transluminal procedure. Percutaneous surgical techniques pertain to
any medical procedure where access to inner organs or other tissue
is done via needle-puncture of the skin, rather than by using an
"open" approach where inner organs or tissue are exposed (typically
with the use of scalpel). The percutaneous approach is commonly
used in vascular procedures, where access to heart is gained
through the venous or arterial systems. This involves a needle
catheter getting access to a blood vessel, followed by the
introduction of a wire through the lumen of the needle. It is over
this wire that other catheters can be placed into the blood vessel.
This technique is known as the modified Seldinger technique. The
PFO closure device 600 may also be deployed via percutaneous
methods by steerable catheters or guidewires.
[0073] In the Seldinger technique a peripheral vein (such as a
femoral vein) is punctured with a needle, the puncture wound is
dilated with a dilator to a size sufficient to accommodate an
introducer sheath, and an introducer sheath with at least one
hemostatic valve is seated within the dilated puncture wound while
maintaining relative hemostasis.
[0074] With the introducer sheath in place, the guiding catheter or
delivery member of the closure device is introduced through the
hemostatic valve of the introducer sheath and is advanced along the
peripheral vein, into the region of the vena cavae, and into the
right atrium.
[0075] By way of example, in one embodiment of the present
invention, using right atrial access, the right atrium is first
accessed by the delivery device (and closure device 600). The
delivery device may be a catheter having a distal end specifically
designed to hold the closure device 600, particularly the distal
anchor member 620 and proximal occluder member 621 in a radially
collapsed position. As previously described, FIGS. 10A and 10B
illustrate two embodiments of the closure device 600 stored in the
delivery device 630 as a payload for delivery.
[0076] The closure device 600 may then be deployed by first
inserting the distal anchor member 620 into the septal tissue of
either the septum secundum 110 or septum primum 105 and deploying
the distal anchor member 620 associated with the closure device 600
into the tissue. As previously disclosed, initial deployment of the
distal anchor member 620 may be by distally displacing the inner
tubular structure 636 relative to the outer tubular structure 635.
FIG. 11 is a perspective view illustrating the closure device 600
wherein the distal anchor member 620 is initially set in the septum
secundum 110 according to one embodiment of the present
invention.
[0077] After successful deployment of the distal anchor member 620,
the delivery device 630 may be withdrawn from the septal wall into
the right atrial chamber, leaving the distal anchor member 620 in
place. The proximal occluder member 621 associated with the closure
device 600 can then be deployed into the right atrial chamber. This
may be achieved by the continued distal displacement of the inner
tubular structure 636 relative to the outer tubular structure 635,
or by simple retraction of the delivery device 630. FIG. 12
illustrates the closure device 600 in a substantially deployed
configuration according to one embodiment of the present
invention.
[0078] Once the proximal occluder member 621 is deployed, the
closure device 600 may be cinched to bring the proximal occluder
member 621 against the septal wall, which is comprised of the
septum secundum 110 and the septum primum 105. This results in the
proximal occluder member 621 being compressed against the septal
wall, covering over the PFO tunnel entrance 120, and substantially
occluding or blocking blood flow to the tunnel, resulting in
"closure" of the Patent Foramen Ovale. Cinching may be performed by
tensioning the closure line 625 i.e. by proximally displacing the
closure line 625 relative to the proximal occluder member 621. FIG.
13 is a perspective view of the closure device 600 according to one
embodiment of the present invention cinched in place.
[0079] It should be noted that the proximal occluder member 621 may
or may not be coated or covered with a biocompatible polymeric
fabric that could assist in occluding blood flow into the tunnel.
In the case that the proximal occluder member 621 is not covered,
blood flow shunting through the PFO track 120 might not decrease as
rapidly as it would in the covered case, however eventually the
incorporation of the proximal occluder 621 would block a sufficient
amount of flow such that the PFO track (tunnel) 120 would be
substantially closed or considered closed.
[0080] To achieve and maintain the proximal occluder member 621
against the septum secundum 110 and the septum primum 105, it may
be necessary to adjust the proximal occluder member 621 by
uni-axially cinching or sliding the proximal member 621 along
closure line 625. In one embodiment of the invention, cinching
comprises uni-axially adjusting the proximal occluder member 621
relative to a closure line 625 associated with the closure device
600. In another embodiment of the invention, cinching comprises
incrementally adjusting the proximal occluder member 621 relative
to a closure line 625 associated with the closure device 600.
[0081] Once the closure device 600 is cinched in place the method
may further comprise assessing the degree of blockage of the PFO
track 120.
[0082] In one embodiment of the invention, the clinician may
visually assess the proximation though an endoscopic or
fluoroscopic procedure. In addition, other methods may be used to
measure the blockage or closure of the PFO track 120, such as
through pressure observation or infrared imaging.
[0083] After proper cinching, any unwanted length of closure line
625 that remains unconstrained within the right atrium may be
mechanically removed. Devices known in the art capable of removing
the excess closure line 625 include catheter-based snare and cut
devices. In addition to independent devices, a mechanical cut and
removal mechanism may be integrated into the deployment device.
[0084] The closure device 600 will then be in position, with the
anchor member 620 open and anchored in the septal wall (septum
secundum 110 or septum primum 105), with the proximal occluder
member 621 flattened against the septum secundum 110 and/or septum
primum 105, and the closure line 625 connecting the proximal and
distal expandable members 621, 620, respectively, thus holding the
proximal occluder member 621 against the septal wall.
[0085] Another embodiment of the invention may include a location
monitoring system to facilitate placement of the deployment device
630. In particular, the location monitoring device will assist in
determining whether the clinician is in the correct chamber of the
heart.
[0086] In a preferred embodiment, the location monitoring system
includes the ability to measure localized pressure relative to the
distal end of the deployment device 630. The pressure measurement
read by the location monitoring system may be achieved by
electronic, mechanical and/or physical means, such as a solid-state
pressure transducer, spring loaded diaphragm, hydraulic pressure
port, and/or communicating manometer. These and other pressure
measurement techniques would be known by one of skill in the
art.
[0087] By way of example it is well known that pressures vary in
different locations within the cardiovascular system. Specifically,
gage pressure in the right and left atrium are know to range from
approximately 1-6 mmHg to 10 mmHg respectfully. Similarly, gage
pressure within the ascending aorta ranges from approximately 120
to 160 mmHg during systole.
[0088] For delivery to the heart, the deployment device 630 (and
thus the closure device 600) is used in conjunction with an
accessory device (not shown) known in the art. In a preferred
embodiment, the accessory device may be a guiding catheter that
tracks over a guidewire, and is steered through the vasculature
into the right atrium.
[0089] In another embodiment, the accessory device and deployment
device 630 may be formed as an integrated component, capable of
being steered through the vasculature.
[0090] To facilitate deployment of the closure device 600, the
deployment device 630 may include features that provide backup
support. This backup support may include, for example: an axially
asymmetric expansion member attached along an outer shaft (outer
tubular structure) 635, such as a balloon or self expanding cage
640; a spline 645; or imparting a shape 650 along the body of the
deployment device 630. Examples of these backup support features
are illustrated in FIGS. 14A through 14C, respectively. It should
be understood that the outer shaft 635 may be part of the guiding
catheter, or integrated into the deployment device 630. These and
other such backup support devices would be understood by one of
skill in the art. These backup support features can also be
incorporated onto accessory devices, such as the guide
catheter.
[0091] Still other embodiments utilizing known methods and
apparatus to deliver the deployment device 630 and closure device
600 into the atrium of heart 100 would be obvious to one of skill
in the art.
* * * * *