U.S. patent application number 10/419412 was filed with the patent office on 2003-10-16 for septal defect occluder.
This patent application is currently assigned to MICROVENA CORPORATION, A MINNESOTA CORPORATION, AND INTO EV3 INC., A DELAWARE CORPORA, MICROVENA CORPORATION, A MINNESOTA CORPORATION, AND INTO EV3 INC., A DELAWARE CORPORA. Invention is credited to Thill, Gary A..
Application Number | 20030195530 10/419412 |
Document ID | / |
Family ID | 25057949 |
Filed Date | 2003-10-16 |
United States Patent
Application |
20030195530 |
Kind Code |
A1 |
Thill, Gary A. |
October 16, 2003 |
Septal defect occluder
Abstract
A septal defect occluder is provided having first and second
occluder panels. Each occluder panel includes a fabric support
structure and fabric suspended therefrom. The occluder panels are
conjoined at a plurality of discrete points which are located
within an area bounded by each perimeter of the fabric support
structures, as well as on the fabric, to thereby form a defect
conforming region for the occluder. In an alternate embodiment,
each occluder panel includes a cambered fabric support structure
and fabric suspended from a perimeter thereof, the occluder panels
being arranged in cooperative cambered opposition such that the
perimeters of the cambered fabric support structures impart a
clamping force upon tissue adjacent a tissue defect interposed
there between when the occluder is deployed for tissue defect
occlusion.
Inventors: |
Thill, Gary A.; (Vadnais
Heights, MN) |
Correspondence
Address: |
Lawrence M. Nawrocki
NAWROCKI, ROONEY & SIVERTSON, P.A.
Suite 401, Broadway Place East
3433 Broadway Street Northeast
Minneapolis
MN
55413
US
|
Assignee: |
MICROVENA CORPORATION, A MINNESOTA
CORPORATION, AND INTO EV3 INC., A DELAWARE CORPORA
|
Family ID: |
25057949 |
Appl. No.: |
10/419412 |
Filed: |
April 21, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10419412 |
Apr 21, 2003 |
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09760056 |
Jan 12, 2001 |
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6551344 |
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09760056 |
Jan 12, 2001 |
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09558717 |
Apr 26, 2000 |
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6214029 |
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Current U.S.
Class: |
606/151 ;
606/157 |
Current CPC
Class: |
A61B 2017/00526
20130101; A61B 2017/00606 20130101; A61B 2017/00623 20130101; A61B
17/0057 20130101; A61B 2017/00597 20130101; A61B 2018/00392
20130101; A61B 17/076 20130101; A61B 2017/00575 20130101; A61B
2017/00247 20130101; A61B 2017/00867 20130101; A61B 2017/00592
20130101 |
Class at
Publication: |
606/151 ;
606/157 |
International
Class: |
A61B 017/08 |
Claims
What is claimed is:
1. A tissue defect occluder comprising first and second occluder
panels, each occluder panel including a cambered fabric support
structure and fabric suspended from a perimeter of said cambered
fabric support structure, said occluder panels being arranged in
cooperative cambered opposition such that the perimeters of said
cambered fabric support structures impart a clamping force upon
tissue adjacent a tissue defect interposed there between when said
occluder is deployed for tissue defect occlusion.
2. The occluder of claim 1 wherein the retrieval force into a
catheter for said occluder is less than five pounds.
3. The occluder of claim 2 wherein the distance between the
perimeter edges of the occluder panels is less than two millimeters
post deployment from a catheter.
4. The occluder of claim 3 wherein the camber of said cambered
fabric support structure is about 15% of the diameter of said
cambered fabric support structure.
5. The occluder of claim 1 wherein said occluder panels are
conjoined at a plurality of discrete points to thereby form a
defect conforming region.
6. The occluder of claim 5 wherein said discrete conjoined points
are located within each of the cambered fabric support structures,
as well as on said fabric.
7. The occluder of claim 6 wherein said cambered fabric support
structure includes perimeter and traversing segments.
8. The occluder of claim 7 wherein the conjoined points within the
cambered fabric support structure comprise loops formed in the
traversing segments of each of the cambered fabric support
structures, thereby defining internal eyelets for said support
structures.
9. The occluder of claim 8 wherein said internal eyelets
substantially delimit said defect conforming region.
10. The occluder of claim 9 wherein the fabric of each of said
cambered fabric support structures is conjoined at a single
location so as to define a center fabric attachment point for said
occluder.
11. The occluder of claim 10 wherein the perimeter segments of at
least one of said cambered fabric support structures include loops
formed therein, thereby defining perimeter eyelets for said support
structure, said perimeter eyelets aiding in the symmetrical
collapse of said cambered fabric support structure as during
reversible retrieval of said occluder into a catheter.
12. The occluder of claim 11 wherein said internal eyelets are
symmetrical about said center fabric attachment point.
13. The occluder of claim 12 wherein said fabric comprises a
polymeric material.
14. The occluder of claim 13 wherein said polymeric material
comprises a polyester knit.
15. The occluder of claim 13 wherein said polymeric material
comprises a 20 denier polyester knit.
16. The occluder of claim 15 wherein said occluder panels are
substantially round.
17. A septal defect occluder comprising first and second occluder
panels, each panel including a cambered fabric support structure
and fabric substantially affixed to a perimeter thereof, each of
said cambered fabric support structures comprising cooperating
cambered frames, the occluder panels being conjoined at internal
frame points located within the perimeter of each of said cambered
fabric support structures, the fabric of each of said cambered
fabric support structures being joined so as to form a center
fabric attachment point.
18. The occluder of claim 17 wherein each of said cooperating
cambered frames has an axis of maximum dimension and an axis of
minimum dimension.
19. The occluder of claim 17 wherein each of said cooperating
cambered frames further has a camber axis, said camber axis being
in substantial conformity with said axis of minimum dimension.
20. The occluder of claim 19 wherein said cooperating cambered
frames are perpendicularly overlaying, the axis of maximum
dimension of one frame substantially aligning with the axis of
minimum dimension of the other frame.
21. The occluder of claim 20 wherein said internal frame points
comprise loops formed in each of said cambered frames, said loops
delimiting a minimum frame dimension and thereby defining internal
eyelets for each of said cambered fabric support structures.
22. The occluder of claim 21 wherein the frames of one of said
cambered fabric support structures comprise loops formed in said
frame of one of said fabric support structures, said loops
delimiting a maximum frame dimension and thereby defining perimeter
eyelets for said cambered fabric support structure.
23. The occluder of claim 22 wherein said perimeter eyelets
cooperatively engage means for urging said occluder from a catheter
for reversible deployment in and about a septal defect site.
24. The occluder of claim 23 wherein said fabric comprises a
polymeric material.
25. The occluder of claim 24 wherein said polymeric material
comprises a polyester knit.
26. The occluder of claim 24 wherein said polymeric material
comprises a 20 denier polyester knit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of co-pending
application Ser. No. 09/558,717, filed Apr. 26, 2000, for SEPTAL
DEFECT OCCLUDER.
TECHNICAL FIELD
[0002] The present invention generally relates to devices for
occluding septal defects or shunts in the heart or the vascular
system, and particularly provides a low profile septal defect
conforming device reversibly deliverable via catheter to a septal
defect site.
BACKGROUND OF INVENTION
[0003] The term "septal defect" generally refers to a perforation
or other type hole (i.e., a defect) which passes through a thin
wall of muscle or other tissue (i.e., a septum) which divides or
separates "areas" within the body. Such defects can occur, either
congenitally or by acquisition, between chambers of the heart
(i.e., atrium or ventricle) or the great vessels (interatrial and
interventricular septal defects or patent ductus arteriosus and
aortico-pulmonary window respectively), causing shunting of blood
through the opening.
[0004] In the case of the atrium, the presence of a significantly
large septal defect can allow blood to shunt across the defect from
the left atrium to the right atrium and hence on to the left
ventricle, aorta and brain. If the defect is not closed, the risk
of stroke is increased.
[0005] Shunting of blood from the right to the left side can also
have negative consequences. This can lead to death due to cardiac
failure or hemoptysis.
[0006] In patients with significant sized ventricular septal
defects or patent ductus arteriosus, there is shunting of blood
from the high pressure left ventricle or aorta, into the right side
chambers and pulmonary arteries which normally have much lower
pressures. The torrential increase in flow at a high pressure can
lead to cardiac failure and death, apart from the serious long-term
complication of high pulmonary pressures which can cause a reversal
of the direction of the shunt.
[0007] Atrial septal defects were initially corrected by open heart
surgery which required the surgeon to open the chest of a patient
and bypass the heart temporarily (e.g., by means of a
cardiopulmonary bypass and moderate hypothermia) The surgeon would
then physically cut into the heart and suture small defects closed.
In the case of larger defects, a patch of a biologically compatible
material would be sewn onto the septum to cover (i.e., "patch") the
defect.
[0008] In order to avoid the morbidity, mortality and long recovery
times associated with open heart surgery, a variety of
transcatheter closure techniques have been attempted. In such
techniques, an occluding device is delivered through a catheter to
the septal defect site. Once the closure device is positioned
adjacent the defect, it must be attached to the rest of the septum
in a manner which permits it to effectively block the passage of
blood through the defect.
[0009] One such closure device, as illustrated in U.S. Pat. No.
3,874,388 (King et al.), includes a pair of complex mechanical
umbrellas, each having a plurality of arms extending radially from
a central hub. The hubs of the two umbrellas are mechanically
connected to one another and each umbrella includes a fabric
covering over the arms, much like a common umbrella. The ends of
each arm are provided with barbs which are anchored into the septum
to hold the occluder in place. The complex umbrellas prove rather
difficult to unfold after passage through a catheter, requiring an
array of cables to deploy the arms. This makes proper placement of
the device difficult, and the barbs on the arms prevent retraction
or repositioning of the device once it is in place. Use of this
device has been limited to adult patients because the device
requires a large catheter, such as about 23 French (7.3 mm), for
delivery.
[0010] Rashkind proposed a single-umbrella closure device capable
of delivery through a 5 mm system which permitted use in children
weighing at least about 20 kg. Similar to the King device, this
umbrella utilizes barbed hooks on the ends of umbrella arms to
ensure attachment to the septum, with the single umbrella being
placed on the left side of the atrial septal defect. The barbs
prevent disengagement of the device, and poorly centered or seated
devices requiring open heart surgery for correction are common.
[0011] Due to the low success rate of previous devices, a "modified
double-umbrella Rashkind occluder" in which the arms of the device
are hinged to permit them to fold back against themselves was
developed. A more compact collapsed condition and a less intrusive
delivery as by an 11 French (3.7 mm) catheter were thereby
facilitated. Furthermore, such a "clamshell" occluder did not
include barbs at the end of the radial arms of the umbrella,
allowing it to be readjusted and retrieved. Typically, this could
be accomplished only once, and without subsequent redeployment due
to damage or destruction of the device. Although arguably an
improvement over heretofore known devices, such a device generally
requires a complex loading jig for deployment and remains
susceptible to moderately high shunting.
[0012] Sideris, in U.S. Pat. No. 4,917,089, proposed an occlusion
device which combines a single umbrella with a separate anchoring
device. Like the previous defect occlusion devices, Sideris'
invention utilizes an umbrella with a plurality of radially
extending arms. A string connects the arms of this umbrella to a
generally rhomboidally shaped anchor which includes an internal
wire skeleton and a central, rhomboidally shaped piece of rubber.
The string attached to the struts of the umbrella is affixed to the
central rubber element of the anchor. The anchor is placed on the
opposite side of the septum from the umbrella, and the length of
the string limits movement of the occlusion device with respect to
the septum. This style of occluder is difficult to deploy, and its
overall bulkiness in the heart causes potential clot emboli due to
protrusion into the atrial cavities.
[0013] Kotula et al., U.S. Pat. No. 5,725,552, provides a
collapsible device comprising a heat-set woven metal fabric
configured as a bell, hourglass, etc. for occluding an abnormal
opening in a body organ. The device of Kotula et al. does not
adequately "fill" the defect nor fit flat against, or readily
conform to, the structures within the heart, thereby increasing the
embolization potential with the use of such device.
[0014] Das, U.S. Pat. No. 5,334,217, teaches a non-retrievable
occluder having paired disks, each of which comprises a membrane,
and an elastically deformable frame carried about the periphery of
each membrane. The disks are joined only at central portions of
each membrane, thereby defining a conjoint disk. The Das device is
intended to be self-centering within the defect. Since the ability
to achieve defect conformity is limited due to the defined conjoint
disk structure, residual shunting can occur. Furthermore, with such
a device, the conjoint disk cannot uniformly apply and distribute a
force to the "second" disk (e.g., as when the second disk follows
the first disk into the catheter for purposes of retrieval. As a
result, the occluder is caused to contort, resulting in
non-symmetrical collapse, and the problems associated
therewith.
[0015] All of the prior art devices described above suffer
shortcomings. First, most of these systems (i.e., the occluder and
delivery means) are mechanically complex and require a great deal
of remote manipulation for deployment or retrieval, if the device
is retrievable. This extensive remote manipulation, such as by
applying tension to one or more cables in order to deploy the arms
of an umbrella or to anchor the device in place, not only increases
the difficulty of the procedure, but tends to increase the
likelihood that the device will be improperly deployed. This can
necessitate retrieval or repositioning so as to effectively occlude
the defect in order to minimize the risk of embolization.
[0016] Second, all of these devices, except for Kotula and Das,
essentially teach two separate members joined to each other at a
single interface. With such device, when the left atrial member is
opened, the central point tends to ride to the lower margin of the
defect. Proper centering of the device is quite difficult, and when
a self centering device as disclosed by Das is employed, it is at
the cost of defect conformity.
[0017] Third, heretofore many known devices have a geometry which
tends to prevent the occluder from remaining flat against, or
within, the defect once deployed from a catheter, which is in and
of itself problematic, and which is likely to deform the tissue
adjacent the tissue defect. A further limitation associated with
such devices is that intimate contact between the perimeter of the
occluder and the tissue adjacent the tissue defect (e.g., a septal
wall), a prerequisite for the formation of a smooth endothelial
growth layer in the final stages of healing, is difficult to obtain
using heretofore known occluders.
[0018] Fourth, heretofore many known devices possess retrieval
limitations, while others are fully not retrievable.
[0019] It is desirable, therefore, to provide a simple, collapsible
compact closure device which may be delivered through a catheter.
It is also highly advantageous to have such a device which can be
readily reversibly deployed and retrieved with a minimum of remote
manipulation and applied force. Further, a device which is
self-centering and self-occluding, particularly one that possesses
a defect conforming variable geometry to fill slit-like defects
such as a patent foramen ovale, and one that can be released while
still being tethered to the delivery mechanism to assure proper
placement and function prior to release, would be superior to
heretofore known devices. This is particularly true in view of the
need to test for shunting of blood around the occluder device with
the septal wall in unrestrained motion prior to release.
SUMMARY OF THE INVENTION
[0020] The present invention is a septal defect occluder which has
first and second occluder panels. Each occluder panel includes a
fabric support structure and fabric suspended from a perimeter
thereof. The occluder panels are conjoined at a plurality of points
which are located within an area bounded by the perimeter of each
fabric support structure, as well as on the fabric, to thereby form
a defect conforming region for the occluder.
[0021] In an alternate embodiment, a septal defect occluder is
provided having first and second occluder panels. Each occluder
panel includes a cambered fabric support structure and fabric
suspended from a perimeter thereof. The occluder panels are
arranged in cooperative cambered opposition such that the
perimeters of the cambered fabric support structures impart a
clamping force upon tissue adjacent a tissue defect interposed
there between when the occluder is deployed for tissue defect
occlusion.
[0022] The present invention is thus an improved device over
structures known in the prior art. More specific features and
advantages obtained in view of those features will become apparent
with reference to the drawing figures and DETAILED DESCRIPTION OF
THE INVENTION.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a side elevational view of the septal defect
occluder of the present invention deployed in a septal defect;
[0024] FIG. 2 is an end view of an occluder panel of the septal
defect occluder of the present invention, particularly illustrating
a center fabric attachment point;
[0025] FIG. 3 is an end view of the frame members of the device of
the subject invention having two pairs of opposing inward
eyelets;
[0026] FIG. 4 depicts a fabric sheet suitable for use with the
invention;
[0027] FIG. 5 is an end view of two frame members of FIG. 3
arranged to form a fabric support structure having both internal
and perimeter eyelets;
[0028] FIG. 6 depicts a first occluder half, corresponding to the
fabric support structure of FIG. 5, showing the relationship
between the fabric sheet of FIG. 4 and the underlaying support
structure;
[0029] FIG. 7 depicts a second occluder half, corresponding to the
second fabric support structure of FIG. 5, showing the relationship
between the fabric sheet of FIG. 4 and the underlaying support
structure;
[0030] FIG. 8 is an overhead perspective view of an alternate
occluder panel;
[0031] FIG. 9 is an overhead perspective view of the underlaying
cambered fabric support structure of the alternate occluder panel
of FIG. 8;
[0032] FIG. 10 is an overhead perspective view of a frame member of
the cambered fabric support structure being formed using a cambered
winding fixture;
[0033] FIG. 11 is a side view of the present invention being
delivered within a catheter to a septal defect site;
[0034] FIG. 12 is a side view of the present invention being
initially deployed within the septal defect, the second occluder
half having expanded to conform to a portion of the defect;
[0035] FIG. 13 is a side view of the present invention deployed
within the septal defect while under the control of tension
imparting means;
[0036] FIG. 14 is a side view of the present invention being
initially retrieved into the catheter from the septal defect site,
the first occluder half being collapsed for catheter entry;
and,
[0037] FIG. 15 is a side view of the present invention on its way
to complete retrieval into the catheter from the septal defect
site.
DETAILED DESCRIPTION OF THE INVENTION
[0038] As shown generally in FIG. 1, a septal defect closure device
20 of the invention may be attached to the septum S (e.g., an
atrial septum) to effectively conform to and block the defect,
without protruding into atrial cavities and the like. As described
in detail below, once the closure device 20 is in place, it becomes
anchored to the septum and prevents the flow of blood through the
atrial septum to the adjoining chambers of the heart. This will
permit the heart to operate normally.
[0039] Referring now to FIGS. 1 and 2, the extremely low profile
closure device includes first and second occluder panels 30, 60.
Each panel 30, 60 is generally round (e.g., circular, oval,
elliptical etc.) so as to facilitate positioning, and minimizes
chances of erosion and puncture. Each panel 30, 60 generally
comprises a fabric support structure 32, 62 and fabric 33 suspended
from a perimeter 34, 64 of the fabric support structures 32, 62.
The occluder panels 30, 60 are conjoined at a plurality of discrete
points, located or positioned within the bounds of each of the
fabric support structures 32, 62 (i.e., within an area bounded by
each perimeter 34, 64 of the support structures 32, 62), as well as
on the fabric 33 (which will be further explained with reference to
FIGS. 2, 7 and 8). A defect conforming region 80 for the occluder
20 is thereby formed. The nature (i.e., structure, relationships
there between and function) of the defect conforming region will be
detailed herein below, particularly with reference to FIGS. 1, 2
and 9-14. At this point it may be said that the region 80
expandingly conforms to substantially completely and thoroughly
satisfy the perimeter of the defect geometry. This stabilizes
panels 30, 60 so that complete coverage of the defect from either
direction is achieved. The defect is thereby occluded without
distortion of the defect.
[0040] The fabric support structures 32, 62 of the occluder are
generally flexible and elastically deformable, and include
perimeter and traversing segments 36, 38. Resilient fabric 33 (FIG.
4) is suspended or otherwise affixed to the perimeter segments 36
of the fabric support structures 32, 62. As particularly shown in
FIG. 2, the perimeter segments 36 of the fabric support structures
32, 62 extend substantially around the periphery 35 of the fabric
33. The fabric 33 may be formed of a thin, flexible material which
can be folded and pulled taut without being damaged. Elastic
polymeric materials such as, for example, polyester knit, nylon,
polypropylene, polytetrafluoroethylene (e.g., Teflon.RTM.), and
expanded polytetrafluoroethylene (e.g., GoreTex.RTM.), as well as
natural fabrics such as silk, are acceptable.
[0041] To accommodate the need of the fabric support structure to
distort when retrieving the occluder 20 into the catheter, excess
fabric can be provided. On an area basis relative to the support
structure, an excess of fabric in the range, typically, of about
30-35 percent, and up to 50 percent, is sufficient. This range is
required for low stretch fabric that otherwise may prevent the
support structure from collapsing in a manner suitable to get into
the catheter. However, the 20 denier polyester knit is advantageous
in that it is of approximately 50% less bulk than known jersey
style knit configurations which facilitates the use of smaller
delivery catheters, and allows for the occluders to be retrieved
into such catheters at forces that are not detrimental to either
the catheter or the occluder (e.g., a 40 mm occluder may be pulled
into a 12 French catheter using a reasonable peak force of about
four pounds). A further advantage is that two complete fabric
"patches" may be incorporated, into the closure device (i.e., no
need to remove material to reduce bulk), which thereby creates a
device having a high reliability of successful closure.
[0042] The fabric 33 may be attached to their respective support
structures 32, 62 by any suitable means. For instance, the fabric
33 may be directly attached to the support structures 32, 62 by
means of an adhesive or the like, or the periphery 35 of the fabric
33 may be wrapped about each of the support structures 32, 62 and
the peripheral edge attached to the rest of the fabric so as to
essentially define a sleeve about each of the support structures
32, 62. In the latter instance, the sleeve may fit the support
structure relatively loosely so that the structure may move within
the sleeve with respect to the fabric. The peripheral edge of the
fabric may be affixed to the rest of the fabric sheet 33 in any
suitable fashion such as by sewing. Preferably, though, the
periphery of the fabric can be sewn to at least some portion of the
perimeter segments 36 of the support structures 32, 62 using
polyester, non-adsorbable suture.
[0043] Referring to FIG. 1, the fabric support members 32, 62 of
the occluder panels 30, 60 are shown as being spaced from one
another for purposes of the present explanation, but this is not
the normal configuration (i.e., static condition) of the panels. In
a static, non deployed condition, the fabric support structures of
the device take a generally planar form, with the two fabric
support structures 32, 62 generally abutting against, or closely
proximate, one another.
[0044] Again referring to FIGS. 1 and 2, the occluder panels 30, 60
are conjoined at a plurality of discrete points, the points being
selected to effectively link each of the fabric support structures
32, 62 together, as well as associate each sheet of fabric 33
carried thereby, so as to form the variably configurable defect
conforming region 80. With such arrangement, the resilient fabric
33 is not only inherently or indirectly positionable in response to
the defect geometry, but also directly responsive vis-a-vis the
conjoined support structures 32, 62.
[0045] The conjoined points within the fabric support structures
32, 62, which responsively link the opposing structures, comprise
loops formed in the traversing segments 38 thereof, these loops
defining internal eyelets 40 for the structures 32, 62. The
internal eyelets 40 of each of the structures 32, 62 are shown as
being joined by suture (e.g., polyester, non-absorbable or other
suitable material), and to some extent delimit the defect
conforming region 80, and serve to center the occluder 20 within
the defect. The remaining points of conjointment comprise the
union, at a single point, of the fabric of each of the fabric
support structures so as to define a generally central fabric
attachment point 42. It is important that fabric 33 of each support
structure 32, 62 be limitingly controlled via the union, however it
is equally important that the fabric 33 remain substantially
suspended for expansion during deployment, preferably exclusively
about or by its periphery 35.
[0046] As best seen in FIG. 2, the center attachment point 42 of
the occluder 20 is preferably but not exclusively configured as a
sutured cross stitch positioned in the center of the fabric 33.
Other attachment configurations or geometries are contemplated, to
the extent that the center attachment point 42 maintains its
functionality, namely that of control of the peripherally supported
fabric, and generally contributing to a centering function for the
occluder. Preferably the internal eyelets 40 are symmetrically
oriented about the center fabric attachment point 42.
[0047] In addition to internal eyelets 40 which are formed in the
traversing segments 38 of each of the fabric support structures 32,
62, the perimeter segments 36 of at least one (i.e., structure 62)
of the fabric support structures 32, 62 include loops formed
therein, thereby defining perimeter eyelets 44 for that particular
support structure 62. As best seen in FIGS. 1 and 8-12, the
perimeter eyelets 44 cooperate with urging means 46 carried by and
or through a catheter 47 so as to aid in the symmetrical collapse
of each of the fabric support structures 32, 62, and the occluder
panels 30, 60 thereby, during reversible retrieval of the device 20
into the catheter 47. The perimeter eyelets 44 associated with the
"catheter side" occluder panel 60 transmit and distribute
deployment and retrieval forces imparted thereupon through the
defect conforming region 80 and to the other occluder panel 30. As
will subsequently be discussed, the unique configuration of the
fabric support structure components, and the relationships there
between, provide numerous advantages (for example: symmetrical
collapse of the occluder, less peak force for retrieval into a
catheter for deployment, and heretofore unsurpassed sealing of
narrow slit defects without the distorting effects typically
associated with fixed geometry conjoint areas such as
circumferential conjoint disks).
[0048] Referring now to FIGS. 3-7, the fabric support structures
comprise cooperating frames 50, each of which preferably resembles
a "bowtie," as best seen in FIG. 3. A more technical description
for the frame geometry might be to characterize it as an octagon
(i.e., a frame of eight legs or segments), particularly an octagon
having a concave, rather than convex, "top" and "bottom" (i.e.,
ceiling and floor). Put yet another way, the frames resemble
elongated hexagons whose long sides are "pinched" towards each
other. The frames 50 may be generally characterized as having
maximum and minimum dimensions and corresponding axes of maximum
and minimum dimension 52, 54. The above frame description is
intended to be illustrative, not limiting, with alternating frame
geometries satisfying the general characterization being
possible.
[0049] The internal eyelets 40 of the fabric support structures 32,
62 are formed in each of the frames 50 along the axis of minimum
dimension 54 (FIG. 3), as illustrated. The resilient internal
eyelets 40 are generally disposed between adjacent ends of two legs
or frame segments 51, one end of the eyelet being attached to each
leg 51. The internal eyelets 40 are shown as laying generally in
the same plane as the legs 51 and may extend generally outwardly of
the periphery of each of the support structures 32, 62, or may
preferably extend inwardly of the periphery of the structures as
shown in the figures. As will be later discussed with respect to an
alternate occluder panel design, each of the frames 50, 50A of the
fabric support structures 32, 62 may be cambered about their
minimum dimension (i.e., the internal eyelets 40 do not lay in the
same plane as the legs 51, or more specifically, the internal
eyelets 40 and perimeter eyelets 44 are not coplanar) so as to,
among other things, provide an occluder capable of exerting a
clamping force at the perimeter edge of the tissue defect when
deployed. The eyelets are desirably formed to function as spring
hinges. This will serve to ensure that the occluder panels 30, 60,
particularly the catheter side panel 60, elastically return
substantially to a plane-defining configuration even after they
have been collapsed and delivered through a catheter.
[0050] Frames 50 of the device have internal eyelets 40, as
previously explained. The internal eyelets 40 of one fabric support
structure (i.e., 32) mate (i.e., align or register) with those of
the other support structure (i.e., 62) so as to thereby conjoin the
occluder panels 30, 60 (FIG. 2). The perimeter eyelets 44 of fabric
support structure 62 on the other hand are formed in its frames 50A
along the axis of maximum dimension 54 (FIG. 3). The perimeter
eyelets 44 cooperatively engage urging means 46 so as to enable
remote manipulation of the occluder 20 during retrieval.
[0051] Each fabric support structure 32, 62 comprises
perpendicularly overlaying frames, the axis of maximum dimension 52
of one frame 50 or 50A substantially aligning with the axis of
minimum dimension 54 of the other frame (FIG. 5). The somewhat
oversized fabric 33 is shown in FIG. 6 underlaying the cooperating
frames, the periphery thereof being sewn or otherwise affixed to
those portions of the frames, which when configured as shown in
FIG. 5, form a perimeter 34, 64 for each of the fabric support
structures 32, 62. It is again noted that the preferred fabric 33
contributes to an occluder 20 that has complete opposing fabric
patches suspended by the fabric support structures 32, 62, which in
turn include a frame geometry and arrangement that generally reduce
deployment and retrieval forces. In return, fabric and stitch wear
and tear and frame "break through" (i.e., separation of the
perimeter segments 36 from the fabric 33 upon expansion of the
occluders 30, 60) are minimized.
[0052] Each frame 50 is preferably formed of a single elongate
strand of wire W. As best seen in FIG. 3, each of the legs 51 may
simply comprise a length of the wire, and the wire may be bent
through greater than 360 degrees to define adjacent legs 51 and to
form the loops or eyelets 40, 44. The ends of the wire may be
attached to each other in any secure fashion, such as by means of a
weldment or a suitable biocompatible cementitious material.
[0053] The frames 50 should be formed of a flexible, elastically
deformable material such as a metal, and the wire comprising the
frame is formed of a superelastic material. One such material
currently known in the art is a near-stoichiometric nickel/titanium
alloy, commonly referred to as Nitinol or NiTi. Such superelastic
materials may be elastically deformed to a much greater extent than
most other materials, yet substantially fully recover their
original shape when released. This permits the frame to be deformed
sufficiently for insertion into, and passage through, a
small-diameter catheter yet automatically elastically return to its
initial shape upon exiting the catheter.
[0054] The frames are preferably manufactured with nitinol wire
that can be wound around the pins of a forming die and subjected to
heat treatment. Each device consists of four frames, two frames for
each support structure. More particularly, each support structure
32, 62 comprises matchingly paired frame styles (i.e., as shown in
FIGS. 6 and 7, occluder panel 30 has a pair of frames 50 whereas
occluder panel 60 has a pair of frames 50A). All eyelets 40, 44 can
be made having generally a 0.030 inch inside diameter, and, as
previously noted, be inward facing (i.e., directed toward the
center fabric attachment point 42). The wire ends of each frame can
be connected with a titanium hypo tube using a compression crimp.
The titanium is more ductile than the nitinol, providing a reliable
grip with excellent corrosion resistance. Alternately, the
preferred shape of the frame may be cut out from a sheet of such
superelastic material as a single block, by chemical etching,
punching with a suitable punch and die, or any other appropriate
forming method.
[0055] In order to enhance radiopacity so that the frame can be
viewed remotely during deployment, the frame may be provided with a
radiopaque coating, such as gold or platinum. For instance, the
wire W may be plated with a thin layer of gold or platinum. In one
particularly useful embodiment, a helically wound length of a thin
radiopaque wire (not shown) is placed over the wire W; such
core/coil structures are well known in the art. Alternatively,
radiopaque marking bands (not shown), which are commercially
available, may be employed. By placing one such band on each leg of
the frame, a physician can remotely visualize the frame as a
plurality of small bands; when the bands are appropriately spaced
from one another on a monitor, the physician knows that the frame
is properly deployed.
[0056] Referring now to FIGS. 8 through 10, an alternate embodiment
of the occluder panel 30 (FIG. 8) and, more particularly the fabric
support structure 37 (FIG. 9), are shown for the defect occluder of
the subject invention. Each occluder panel 30 includes a cambered
fabric support structure 37 which otherwise conforms with/to the
fabric support structure previously disclosed (i.e., the fabric
support structure 37 of FIG. 8, and frame member 39 shown being
formed in FIG. 10, each have the general end view appearance as the
embodiment depicted in FIGS. 2 and 3 respectively, including
eyelets which have been omitted from FIGS. 8 through 10 for the
sake of clarity). Each of the occluder panels 30 are arranged in
cooperative cambered opposition such that the perimeters 41 of the
cambered fabric support structures 37 impart a clamping force upon
tissue adjacent a tissue defect interposed there between when the
occluder is deployed for tissue defect occlusion. Furthermore,
because the entire perimeter 35 of the fabric 33 is supported by
the cambered fabric support structure 37, and because the occluder
panels 30 are urged together at the perimeter edge of the defect
due to their arrangement in biased opposition, intimate contact of
the occluder with the tissue is assured which is advantageous in
supporting endothelial tissue growth during the final stages of
healing.
[0057] The aforementioned occluder panel design substantially
improves performance in the area of the occluder "go flat"
characteristic. Such "go flat" characteristic (i.e., "flatness") is
specified as the distance between the perimeter edges of the
occluder panels after deployment from the catheter. Heretofore
known occluders, particularly larger devices (i.e., in excess of
about 28 mm across), sometimes have difficulty returning to a
"flat" shape (i.e., less than about 2 mm separation between
occluder panels or halves) post deployment from a catheter. Force
testing of smaller devices utilizing 0.007" diameter nitinol wire
indicated that the return energy of the fabric support structures
was far greater than the energy in larger devices utilizing 0.010"
diameter nitinol wire, thereby permitting the fabric support
structures to substantially overcome the forces associated with the
fabric suspended thereover, and thus lay "flat". Solution of the
"go flat" problem via an increase in frame wire diameter yielded a
less than desirable catheter retrieval force, namely a retrieval
force in excess of 5 lbs. Occluder panels having a cambered fabric
support structure, and alignment of the panels in biased
opposition, provide a tissue defect occluder having a preloaded or
added energy effect without increasing wire diameter, and thereby
increasing catheter retrieval force.
[0058] Each of the frame members or elements 39 of each of the
fabric support structures 37 are cambered about their minimum
dimension 43 (i.e., the internal eyelets do not lay in the same
plane as the legs, or more specifically, the internal eyelets and
perimeter eyelets are not coplanar). Said another way, each frame
element 39 has a camber axis 45 which is in substantial conformity
with the axis of minimum dimension 43, compare FIGS. 3 and 10. Each
cambered fabric support structure 37 comprises perpendicularly
overlaying frames 39, the axis of maximum dimension 48 of one frame
substantially aligning with the axis of minimum dimension 43 and
camber 45 of the other frame. Furthermore, as best seen in FIGS. 8
and 9, the cambered frame members 39 are arranged in forming the
cambered fabric support structure 49 such that a support structure
apex 49 is formed, the apex 49 being defined as the intersection of
camber axis 45 for the cooperating frame members 39. The somewhat
oversized fabric 33 indicated by dashed line in FIG. 8, has a
periphery 35 sewn or otherwise affixed, as the embodiment
illustrated in FIGS. 2, 6, and 7, to those portions of the frame
elements 39 which form a perimeter 41 for each of the fabric
support structures 37. It is again noted that the preferred fabric
carried by the fabric support structures of the subject invention
contributes to an occluder that has complete opposing fabric
patches suspended by the cambered fabric support structures, which
in turn yields a preloaded frame geometry and occluder panel
arrangement that generally reduces deployment and retrieval forces
while enhancing the stay flat characteristics of the device.
[0059] Although the cambered frame members which comprise the
cambered fabric support structures are manufactured much like the
"planar" frames of FIG. 3, namely with nitinol wire that can be
wound around the pins 53 of a forming die 55 and subjected to heat
treatment, during the winding process, a biasing mandrel (not
shown) is used in combination with the forming die 55 to form the
cambered frame member 39. Alternately, the forming die 55 itself
may be contoured so as to produce a cambered frame as is depicted
in FIG. 10.
[0060] As with the case of the occluder of FIGS. 1 and 2, the
occluder panels are conjoined at a plurality of discrete points,
the points being selected to effectively link each of the cambered
fabric support structures together, as well as associate each sheet
of fabric carried thereby, so as to form the variably configurable
defect conforming region. With such arrangement, the resilient
fabric is not only inherently or indirectly positionable in
response to the defect geometry, but also directly responsive
vis-a-vis the conjoined support structures.
[0061] Referring now to FIGS. 11 through 15, the general closure
device 20 of the invention (i.e., those embodiments previously
described) is shown being deployed to occlude a defect in a septum
S. The first panel 60 (i.e., catheter side occluder panel) of the
device 20 is positioned on one side of the defect while the second
panel 30 is generally disposed on the other side. The frames 50 or
50A of the fabric support structures 32, 62 are elastically biased
toward the position shown in FIG. 2. The defect conforming region
80 is positioned within, and expands so as to occlude the defect.
Because the support structures 32, 62, vis-a-vis their frames 50 or
50A, are elastically biased toward their deployed configuration,
they are biased generally toward one another and engage opposing
sides of the septum about the defect. Since there are no
compressive forces acting on the frames which might cause them to
collapse, this serves to effectively hold the device in place and
occlude the defect. The device is further shown in FIGS. 14 and 15
being retrieved from a septal defect site, as might be required in
the event of inadvertent initial placement, size mismatch, or
otherwise.
[0062] The fabric sheets 33 are formed of a relatively porous
material (FIG. 4). While this may seem to contradict the purpose of
the device, blood will tend to coagulate on the latticework
provided by the porous material. Blood flow across the defect is
usually substantially blocked after minimal time passage. If so
desired, the conjoint portion of the device (or the entire device)
may be treated with a thrombogenic agent to speed this natural
process or may be impregnated with a biocompatible polymeric
compound or the like to make it relatively impervious to
fluids.
[0063] The primary purpose of using a porous fabric is to
accelerate the process of permanently anchoring the device in
place. The support structures hold the fabric tautly and in
intimate contact with the surface of the septum S. This intimate
contact between the septum and perimeter of the occluder permits
ingrowth of collagen and fibrous tissue from the septum into the
fabric. Over time, the membrane resting against the septum will
become securely anchored to the septal wall and be covered by a
layer of endothelial cells.
[0064] The design of this device is in stark contrast to the septal
defect closure devices known in the art. As explained in detail
above, prior art devices employ a mechanical umbrella of one design
or another. The radially extending arms of the umbrella contact the
septum and serve to space all but the peripheral edge of the
umbrella away from the septum. Endothelial cells, collagen and
fibrous tissue are therefore permitted to grow into only the very
periphery of the umbrella. Thus, while a closure device of the
invention essentially becomes an integral part of the septum, the
complex mechanical structure of prior art devices does not enable
as complete integration as the present invention.
[0065] The mechanical complexity of prior art devices also tends to
markedly affect their durability. In the case of atrial or
ventricular septal defects, for example, the heart obviously
continues to beat after the device is in place. Since beating of
the heart is accomplished by flexure of the heart muscles, the
septum will flex to some degree with every beat of the heart. The
radial arms must therefore flex with the septum with each and every
time the heart beat. The number of cycles of this stress-inducing
movement produces repeated stresses on the arms, which can
eventually lead to mechanical failure and fracture of the arms.
[0066] When a closure device of the invention is deployed, the
tension of the frame of the support structure opens the panel to
occlude the defect. Since there are no radial arms to prop open the
device, the occurrence of repeated flexion does not occur due to
the beating of the heart or pressure differences between the
cardiac chamber during the phase of contraction of the heart. To
the contrary, any pressure difference would urge a frame and panel
against the septum, more firmly occluding the defect. In addition,
the superelastic material of the frame tolerates flexural stresses
much better than the rigid steel arms of the prior art devices. The
present device therefore will continue to flex with the septum
without any significant effect on its structural integrity.
[0067] Although the foregoing has focused on application of the
present invention to occlude atrial septal defects, the invention
is not limited to occluding such defects. For instance, the instant
closure device can be used to treat ventricular septal defects,
patent ductus arteriosus, patent foramen ovale (PFO), or any other
congenital or acquired orificial or tubular communications between
vascular chambers or vessels.
[0068] While a preferred embodiment of the present invention has
been described, it should be understood that various changes,
adaptations and modifications may be made therein without departing
from the spirit of the invention. Changes may be made in details,
particularly in matters of shape, size, material, and arrangement
of parts without exceeding the scope of the invention. Accordingly,
the scope of the invention is as defined in the language of the
appended claims.
1 ATTACHMENT A SER. NO. FILING DATE PATENT NO. ISSUE DATE 2.
09/760,056 Jan. 1, 2001 3. 09/628,211 Jul. 28, 2000 6,440,152 B1
Aug. 27, 2002 4. 10/227,773 Aug. 26, 2002 5. 09/628,212 Jul. 28,
2000 6. 09/631,482 Aug. 3, 2000 7. 09/936,248 Sep. 7, 2001 8.
10/184,327 Jun. 27, 2002 9. 09/981,769 Oct. 17, 2001 10. 10/074,740
Feb. 12, 2002 11. 10/056,588 Jan. 23, 2002 12. 10/100,686 Mar. 14,
2002 13. 10/165,803 Jun. 7, 2003 14. 10/209,797 Jul. 30, 2002 15.
10/290,426 Nov. 7, 2002 16. 10/290,392 Nov. 7, 2002
Article Five
[0069] The Agreement of Merger is on file at the following place of
business of the Surviving Company: ev3 Inc., 1861 Buerkle Road,
White Bear Lake, Minn. 55110.
Article Six
[0070] A copy of the Agreement of Merger will be furnished by the
Surviving Company, on request and without cost, to any stockholder
of any constituent corporation.
Article Seven
[0071] The aggregate number of shares of stock which the Merging
Company has authority to issue is 35,450,000 shares, which consist
of 32,500,000 shares of Class A Common Stock, 200,000 shares of
Class B Common Stock, 1,600,000 shares of Series A Convertible
Preferred Stock, 150,000 shares of Series B Convertible Preferred
Stock, 347,755 shares of Series C Convertible Preferred Stock and
652,245 shares of undesignated stock. The par value of each share
of capital stock of the Merging Company is 5.01.
* * * * *