U.S. patent application number 11/102884 was filed with the patent office on 2005-12-01 for split ends closure device.
This patent application is currently assigned to NMT Medical, Inc.. Invention is credited to Chanduszko, Andrzej J..
Application Number | 20050267524 11/102884 |
Document ID | / |
Family ID | 35426405 |
Filed Date | 2005-12-01 |
United States Patent
Application |
20050267524 |
Kind Code |
A1 |
Chanduszko, Andrzej J. |
December 1, 2005 |
Split ends closure device
Abstract
A device closes a patent foramen ovale (PFO), thus reducing or
eliminating blood flow through the defect. The device is formed
from a tubular structure having split ends, such that, after
insertion, struts defined by the split ends pivot in a radial
direction away from the tube, thereby securing the device within
the septal defect.
Inventors: |
Chanduszko, Andrzej J.;
(Chandler, AZ) |
Correspondence
Address: |
WILMER CUTLER PICKERING HALE AND DORR LLP
60 STATE STREET
BOSTON
MA
02109
US
|
Assignee: |
NMT Medical, Inc.
Boston
MA
|
Family ID: |
35426405 |
Appl. No.: |
11/102884 |
Filed: |
April 8, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60561544 |
Apr 9, 2004 |
|
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Current U.S.
Class: |
606/213 |
Current CPC
Class: |
A61B 17/0057 20130101;
A61B 2017/00575 20130101; A61B 2017/00867 20130101; A61B 2017/00592
20130101; A61B 2017/00606 20130101; A61B 2017/00243 20130101 |
Class at
Publication: |
606/213 |
International
Class: |
A61B 017/08 |
Claims
What is claimed:
1. A device for use with a septal defect comprising a first
configuration having dimensions suitable for insertion into a
catheter, the device in the first configuration including a tubular
structure with a central axis, a proximal end, and a distal end,
wherein at least one of the ends has a plurality of slits extending
in an axial direction away from the end, the slits defining struts
that are pivotable away from the rest of the tubular structure.
2. The device of claim 1, wherein the plurality of slits is
selected from the group consisting of 2, 3, 4, 5, 6, 7, 8, 9, and
10 slits.
3. The device of claim 1, wherein the plurality of slits have
different lengths.
4. The device of claim 1, wherein the slits are distributed evenly
around the circumference.
5. The device of claim 1, wherein the slits are distributed
unevenly around the circumference.
6. The device of claim 1, wherein the proximal and distal ends each
have slits, wherein each slit extending from the proximal end is
aligned with a corresponding slit extending from the distal
end.
7. The device of claim 1, wherein the proximal and distal ends each
have slits, wherein each slit extending from the proximal end is
offset at a circumferential angle of less than 180 degrees with
respect to a corresponding slit from the distal end.
8. The device of claim 1, wherein an axially central portion of the
structure has whiskers that provoke an inflammatory response.
9. The device of claim 1, further comprising a collar including a
sponge-like material at an axially central portion of the
structure.
10. The device of claim 1, further comprising a drug coating at an
axially central portion of the structure.
11. The device of claim 1, further comprising an anticoagulant at
an axially central portion of the structure.
12. The device of claim 1 further comprising means for causing the
struts to extend radially away from the central axis of the tubular
structure in a second configuration when released from a catheter
and into the body.
13. The device of claim 12, wherein the means includes a tissue
scaffold attached to at least one of the struts.
14. The device of claim 13, wherein the tissue scaffold includes at
least one of a bioresorbable material, a flexible biocompatible
material capable of promoting tissue growth, a polyester fabric, a
Teflon-based material, a polyurethane, a metallic mesh, polyvinyl
alcohol, an extracellular matrix, a synthetic bioabsorbable
polymeric scaffold, and collagen.
15. The device of claim 12, wherein the means includes a tensioner
comprising at least one of an elastic band and a string, the
tensioner attached at one end to a strut extending from the distal
end of the tubular structure and at the other end to an opposing
strut extending from the proximal end of the tubular structure.
16. The device of claim 12, wherein the structure comprises a
polymer with shape memory properties.
17. The device of claim 12, wherein the second configuration is
suitable for blocking part or all of a patent foramen ovale (PFO)
and the struts secure the device within the PFO.
18. The device of claim 12, wherein prior to insertion into the
body, the second configuration comprises distal end struts having
ends that are closer to the proximal end of the structure than the
ends of the proximal end struts.
19. The device of claim 12, wherein the second configuration
comprises at least one pair of distal end struts that are curved so
as to touch in a region near the end of each member of the pair,
and at least one pair of proximal end struts that are curved so as
to touch in a region near the end of each member of the pair.
20. The device of claim 12, further comprising a recovery wire
attached to a plurality of struts, such that a tension applied to
the recovery wire causes the second configuration to deform in a
manner that permits the device to be retracted into the
catheter.
21. A PFO closure device comprising a tubular structure having a
central axis, a proximal end, and a distal end, wherein at least
one of the ends has a plurality of slits extending in an axial
direction from the end, the slits defining struts that extend
radially away from the central axis of the tubular structure, the
struts securing the device within a tunnel of the PFO.
22. The device of claim 21, wherein each proximal end strut is
circumferentially aligned with a corresponding distal end
strut.
23. The device of claim 21, wherein at least one proximal end strut
is circumferentially offset with respect to a corresponding distal
end strut.
24. The device of claim 21 further comprising a tissue scaffold
attached to at least one of the struts.
25. A method for closing a PFO, the method comprising: inserting a
tubular structure into the PFO via a catheter, the tubular device
having a central axis, a proximal end, and a distal end, wherein at
least one of the ends has a plurality of slits extending in an
axial direction from the end, the slits defining struts; causing
the struts to extend radially away from the central axis such that
the struts secure a central portion of the tubular structure within
a tunnel of the PFO; and closing the PFO.
26. The method of claim 25, wherein the tubular structure comprises
a material selected from the group consisting of a polymer, a metal
with shape memory properties, and a metal with elastic recovery
properties, such that the radial extension of the struts is caused
by at least one of a temperature change associated with insertion
into the PFO and elastic recovery upon removal of the device from
the catheter.
27. The method of claim 25, wherein the radial extension of the
struts is assisted by at least one tensioner comprising at least
one of an elastic band and a string, the tensioner attached at one
end to a strut extending from the distal end of the tubular
structure and at the other end to an opposing strut extending from
the proximal end of the tubular structure.
28. The method of claim 25, wherein a tissue scaffold is attached
to at least one of the struts.
29. The method of claim 25, wherein the tubular device includes a
central structure that assists a healing of a tissue adjacent to
the PFO following insertion of the device, the central structure
comprising at least one of whiskers attached to the exterior of the
tubular structure and a collar including a drug-dispensing
sponge-like material.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application 60/561,544, filed Apr. 9, 2004, the entire contents of
which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The invention relates to devices and methods for closing
defects such as a patent foramen ovale (PFO).
[0003] A PFO is a persistent, one-way, usually flap-like opening in
the wall between the right atrium and left atrium of the heart.
Since left atrial (LA) pressure is normally higher than right
atrial (RA) pressure, the flap typically stays closed. Under
certain conditions, however, RA pressure can exceed LA pressure,
creating the possibility for right to left shunting that can allow
blood clots to enter the systemic circulation.
[0004] In utero, the foramen ovale serves as a physiologic conduit
for right-to-left shunting. After birth, with the establishment of
pulmonary circulation, the increased left atrial blood flow and
pressure results in functional closure of the foramen ovale. This
closure is typically followed by anatomical closure of the two
over-lapping layers of tissue, septum primum and septum secundum.
However, a PFO has been shown to persist in a significant minority
of adults.
[0005] The presence of a PFO has no therapeutic consequence in
otherwise healthy adults, however, patients suffering a stroke or
TIA in the presence of a PFO and without another cause of ischemic
stroke are considered for prophylactic medical therapy to reduce
the risk of a recurrent embolic event. These patients can be
treated with oral anticoagulants, but such drugs have the potential
for adverse side effects such as hemorrhaging, hematoma, and
interactions with other drugs. In certain cases, such as when the
use of anticoagulation drugs is contraindicated, surgery may be
used to suture a PFO closed. Suturing a PFO requires attachment of
septum secundum to septum primum with a stitch (continuous or
interrupted), which is the common way a surgeon shuts the PFO under
direct visualization.
[0006] Non-surgical closure of PFOs has become possible with
umbrella devices and a variety of other similar mechanical closure
designs developed initially for percutaneous closure of atrial
septal defects (ASD). These devices allow patients to avoid the
potential side effects often associated with anticoagulation
therapies.
SUMMARY OF THE INVENTION
[0007] Embodiments of the invention include devices and methods for
closing a septal defect, including a PFO. In one embodiment, the
device includes a tubular structure having dimensions suitable for
insertion into a catheter, and slits extending from one or both
ends that define struts that can pivot away from the rest of the
tube to provide desirable anchoring of the device within a septal
defect. The slits can be spaced at regular or irregular intervals
along the tube circumference, and can have different lengths. A
slit extending from one end of the tube can be aligned or offset
with respect to a corresponding slit extending from the other end.
The configuration of slits can be designed to optimize the
distribution of clamping forces provided by the struts defined by
the slits. In some embodiments, prior to insertion into the body,
struts defined by slits from one end can overlap or touch
corresponding struts defined by slits from the other end. The
device can further include a recovery wire attached to one or more
struts, such that tension applied to the recovery wire can enable
the device to be retracted into the catheter.
[0008] The device is preferably made from a polymer with shape
memory properties, and can also include a means for causing the
struts to extend radially when released from the catheter into the
body. The means can include a tissue scaffold attached to at least
one of the struts, and/or a tensioner, such as an elastic band or
string. The tissue scaffold can be made of a bioresorbable
material, a flexible biocompatible material capable of promoting
tissue growth, a polyester fabric, a Teflon-based material, a
polyurethane, a metallic mesh, polyvinyl alcohol, an extracellular
matrix, a synthetic bioabsorbable polymeric scaffold, collagen, and
combinations thereof. At an axially central portion, the device can
further include whiskers to provoke an inflammatory response, a
collar including a sponge-like material, a drug coating, or an
anticoagulant.
[0009] Benefits of certain embodiments can include atraumatic
shape, good conformity to the anatomy (especially when used for a
PFO), small diameter delivery sheath, no permanent foreign
material, ease of manufacturing, cost effectiveness, and overall
simplicity. Other features and advantages will become apparent from
the following detailed description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a perspective view of a tube with slits used to
form a closure device.
[0011] FIG. 2 is a perspective view of the tube of FIG. 1 with the
ends shown split extending outwardly.
[0012] FIGS. 3 and 4 are a perspective view and front elevational
view, respectively, of an embodiment with three struts and whiskers
and/or sponge material.
[0013] FIGS. 5 and 6 are side and front (through line 6-6 of FIG.
5) views of the device of FIGS. 3 and 4, shown positioned in the
PFO.
[0014] FIG. 7 is a perspective view of an alternative embodiment to
FIG. 3 with a tissue scaffold.
[0015] FIGS. 8 and 9 are further embodiments of a closure device,
and
[0016] FIGS. 10 and 11 are perspective views of the device of FIG.
8 with the addition of a connector and shown in vivo.
[0017] FIGS. 12-16 are views of another embodiment of the present
invention.
[0018] FIGS. 17-23 are views of another embodiment shown with and
without a tissue scaffold.
DETAILED DESCRIPTION
[0019] The present invention includes embodiments of a closure
device for a PFO, atrial septal defect (ASD), or other suitable
defect, preferably formed from a single tube with cuts made to
produce the final device shape. The device can have struts that
extend radially outwardly from a central portion, or loops that
extend from the central portion and back to the central portion,
preferably in a plane that is parallel to the defect (such as the
PFO tunnel).
[0020] Referring to FIG. 1, in one embodiment a closure device is
made from a single polymer tube 10 by providing slits 12, 14 at
both ends and setting a desired shape, such as by thermo-mechanical
treatment, to produce a design as shown in FIG. 2. This treatment
can include heating or other thermal steps, and mechanical steps,
such as folding back the struts.
[0021] This device has a first set of struts 16a, 16b and a second
set of struts 18a, 18b at the opposite end. A center portion 20 is
between the ends and typically has no cuts. As shown in FIG. 2, a
recovery wire 22 and lug 24 can optionally be provided at a
proximal end (right atrium in case of use for a PFO) and coupled to
struts 16a, 16b. The device can be collapsed and loaded into a
delivery sheath by grabbing the lug and bringing the split ends on
a proximal side back together.
[0022] The device is formed back into a tube for deployment via a
catheter. Upon deployment, the occluder reverts to its designed
shape due to elastic recovery of the polymer, shape memory
recovery, or/and the use of strings, springs, or elastic sheet
(tensile elements). Even though tensile elements may be thinner
than the frame, they can produce much higher forces than the frame
itself, thus assisting the frame in its recovery. This is possible
because the primary mode of deformation is in tension, while the
frame deformation mode is in bending and torsion. Tensile elements
also provide a way for centering so the occluder can be positioned
properly in a wide defect.
[0023] Without a wire and a lug or other method to grab the struts
at the proximal end, if the proximal end needed to be withdrawn
back into a catheter, the struts would fold over the outside of the
central portion, thereby increasing the cross-sectional profile.
This may be acceptable, but a smaller profile would be obtained by
pulling the ends of the struts back into the tubular shape. At the
distal end where struts 18a, 18b are (the left atrial end in case
of use in a PFO), a pulling action of the device back into a
catheter would naturally urge the struts back into the tubular
configuration.
[0024] The number of radially extending parts (struts) formed from
each end of a tube could be greater than two, such as any number
from 3 to 10. Using many more struts, such as more than 10, may be
possible but could be impractical because there could be a
considerable decrease in their stiffness due to the decrease in
thickness. More struts at each end may be possible with appropriate
materials.
[0025] FIGS. 3 and 4 show a closure device 30 with 3 slits made at
each end of a tube to form three struts 32a-32c, 34a-34c at each
end of the tube. Small strips, referred to here as whiskers 36,
made of the same material as the tube or some other materials can
be attached to the central portion 38, or material can be partially
shaved from the center region 38 of the tube. These whiskers can
produce an inflammatory response and speed up the healing process.
The whiskers can have a drug coating, such as with an
anti-coagulant, or can be made of a drug that is slowly dissolved.
Rather than the whiskers as shown, a collar with a foam or
sponge-like material, such as polyvinyl alcohol, can be used, and
can include an anti-coagulant.
[0026] FIGS. 5 and 6 show the embodiment of FIGS. 3 and 4 as
deployed in a PFO tunnel. As indicated here, struts 32a and 34a
have ends that contact septum primum 50, and struts 32b and 34b
have ends that contact septum secundum 52. Struts 32c and 34c are
not shown in FIG. 5, but as indicated in FIG. 6, they could be
positioned against septum primum or septum secundum. These struts
cooperate to provide a compressive clamping force to the PFO.
[0027] Center portion 38 can extend through the PFO tunnel and can
be at an acute angle A relative to a downward vertical direction.
This is an example of how the configuration can conform well to the
anatomy.
[0028] As shown in top view FIG. 4, the struts can be formed so
that they are evenly distributed circumferentially. Generally, the
struts can be equally spaced by 360.degree./n in the
circumferential direction, where n is the number of struts; for 3
struts, each strut is at 120.degree. relative to adjacent struts.
The struts at one end can be offset by (360.degree./n)/2 from the
struts at the other end.
[0029] Such an even distribution at each end and equal offset of
the two ends relative to each other can be used, but such
relationships are not required. The slits at each end of the tube
can be formed in one of a number of different ways, and can produce
struts that have different widths. In addition, while the slits may
be rather narrow as shown, such that the sum of the widths of the
struts is just a little less than the circumference of the tube,
the slits can be made wider so that the struts are narrower,
although it is generally preferable to have wider struts to provide
good support.
[0030] FIG. 7 is a perspective view of a device similar to that of
FIGS. 3 and 4, but with the addition of a tissue scaffold. While
preferably bioresorbable, the tissue scaffold may be formed of any
flexible, biocompatible material capable of promoting tissue
growth, including but not limited to polyester fabrics,
Teflon-based materials such as ePTFE, polyurethanes, metallic
meshes, polyvinyl alcohol (PVA), extracellular matrix (ECM), or
other bioengineered material, synthetic bioabsorbable polymeric
scaffolds, other natural materials (e.g. collagen), or combinations
of the foregoing materials. Also, a tissue scaffold may be formed
of a thin metallic film or foil. The scaffold may be attached to
one or both sides of the device. The tissue scaffold or the frame
can have drugs or biological agents to accelerate the defect
healing process and/or decrease thrombosis.
[0031] Referring to FIG. 8, in another embodiment, the tube has
four slits at each end to produce four struts at each end of the
tube. As indicated above, whiskers and/or sponge material and
tissue scaffolds could be added, as could a recovery wire and
lug.
[0032] Referring to FIG. 9, an embodiment similar to that of FIG. 8
is shown with the addition of elastic bands or strings 90, 92
extending from ends of struts at one end to ends of struts at
another end. These bands can be provided for some or all of the
opposing struts. As shown here, the struts can be located at the
same circumferential position at each end (and not offset, unlike
in FIG. 4). The strings help to bend back the struts, and can also
help to orient and center the device as shown below.
[0033] In the embodiments of FIGS. 10 and 11, device 100 has four
struts at each end. From each of two of the struts, an elastic band
102, 104 extends from one strut to a corresponding strut at the
opposite end of the device. The bands can provide centering and/or
be inflammatory.
[0034] FIGS. 12-15 show another embodiment. Referring specifically
to FIG. 12, the tube has several different slits, including two
longer slits, 180.degree. apart, at each end to form bases 120 and
122 for struts, and two shorter slits are made, offset by
90.degree. from the longer slits, to form struts 124, 126, 128, and
130 at one end. As also shown in FIGS. 13 and 14, struts 124-130
can be formed at one end to be offset at a circumferential angle of
90.degree. with respect to struts at the other end, identified here
as struts 132, 134, 136, and 138.
[0035] Referring to FIG. 15, in this side view, it is shown that
the struts can be formed during manufacture such that the ends of
the struts at opposite ends overlap when treated and before
deployment. In other words, a distal end strut 126 and a proximal
end strut 136 cross such that the end of strut 126 is closer to the
proximal end than the end of proximal strut 136.
[0036] This configuration may be more suitable for a polymer
embodiment or for another type of material that may not have full
recovery force. Nitinol, for example, has rather high recovery
force and is better able to reassume its original shape after being
folded into a catheter and then deployed. A polymer may not have
quite as much recovery force, and therefore it can be useful to
compensate partially for this by allowing struts at one end to
cross the struts at the other end in the manufactured
configuration. The struts will be contacting tissue that separates
them, and therefore in the deployed position, the struts will be
spaced part and not overlap.
[0037] Referring to FIG. 16, the tube in this case is shown with
slits that are somewhat similar to that in FIG. 12, except that
rather than the long slits being offset as in FIG. 12, the long
slits in FIG. 16 at opposite ends are circumferentially aligned. In
this embodiment, struts 162, 164, 166 and 168 are produced at one
end, with similar struts at the other end. Unlike the embodiment as
shown in FIG. 13, in which struts 124 and 128 extend substantially
parallel, struts 162 and 166 are curved to come together at an end
170. Other struts are matched up pairwise in a similar manner,
forming in effect four loops.
[0038] Each of these loops is preferably parallel to the defect.
This allows most of the loop to be in contact with the tissue, such
as one of the septa in the case of a PFO. The loop can be
perpendicular to the defect, which is more like a strut that
doubles back to the central portion. This configuration is possible
but less desirable.
[0039] As shown in FIG. 19, the ends 170, 172 of these loops can be
formed to be very close together or even touch when manufactured.
As described above, a material with a recovery that does not fully
come back into place may be compensated by bringing the ends
together or overlapping as described above.
[0040] FIG. 20 shows still another embodiment. As shown here,
shorter and longer axial slits are not that much different, thereby
producing larger loops when ends of the struts are brought together
as shown in FIGS. 21 and 22 to create loops in a manner similar to
that shown in FIG. 17. In this case, a tissue scaffold can also be
provided in advance and during manufacture to the loops to result
in the scaffold on the device as shown in FIGS. 21 and 22.
[0041] As indicated, the slits can have different widths, different
numbers, and different slits can be formed with different lengths.
In the case of struts, the ends of the struts contact the tissue,
while in the case of the loops, as shown in FIGS. 17 and 21, for
example, the loop may contact the tissue over a larger area,
thereby producing less trauma to the patient. To reduce trauma with
struts, ends of the struts can be modified, such as rounded to
reduce trauma that may be provided to septum primum and septum
secundum when implanted.
[0042] The proximal and distal end loops in FIG. 17 are aligned,
but they could be rotationally offset, preferably by 90 degrees so
the ends are perpendicular to each other. This can be accomplished
by changing the pattern of slits in a tube.
[0043] As indicated before, the device can be deployed through a
catheter using generally conventionally known processes. This
description relates to the use for a PFO, where the proximal side
is the right atrium and the distal side is the left atrium, but the
process could be used for other types of defects or treatments.
[0044] The occluder in its manufactured form is essentially folded
back into the tubular form and inserted into a catheter. The distal
end of the catheter is inserted into the left atrium where the
catheter and the occluder are moved relative to each other so that
the struts, loops, or other radial pieces can fan out to contact
septum primum and septum secundum. This movement can be
accomplished by pushing the occluder out of the catheter or
retracting the catheter so that the occluder is not constrained and
can fan out. At this stage, it should not be difficult to pull the
device back into the catheter if necessary to remove or reposition,
as the radial pieces will tend to go back into the catheter.
[0045] When positioning at the distal end is satisfactory, the
catheter is retracted through the PFO tunnel between septum primum
and septum secundum to expose the central portion, and is then
moved further in the proximal direction to the device so that the
catheter ceases to constrain the radial pieces from fanning out in
the right atrium. As indicated above in FIG. 2, a recovery lug can
be provided so that if the device is positioned and it is desirable
to retrieve it, hooks or arms can be used to grab the lug to pull
the proximal end in the right atrium back into a tubular
configuration. Further distal direction movement of the catheter
relative to the device will cause the distal (left atrium) end to
be drawn back into the catheter.
[0046] As indicated before, the device can be made of nitinol or
some other metal with good recovery or shape memory properties, or
it can be made of a polymer. In the case of a polymer, the polymer
is preferably treated to make it make it radiopaque so that it can
be seen on x-ray or other imaging equipment.
[0047] The shape and construction of such devices can have some
advantages over other PFO closure devices. It has atraumatic shape,
good embolization resistance in some embodiments, and the ability
to conform to the anatomy, especially in a defect tunnel due to the
angled joint between the proximal and distal side. The device can
be repositioned or/and removed during delivery. It has a small
profile after deployment. It can be made of bioresorbable
components. Certain embodiments can be used to close symmetric
defects (e.g., atrial septal defects) or asymmetric defects (e.g.,
PFO) using two versions of the device, i.e., one with a straight
center tube and one with an angled center tube.
[0048] Occluders as described herein can be used with
anti-thrombogenic compounds, including but not limited to heparin
and peptides, to reduce thrombogenicity of the occluder and/or to
enhance the healing response of the septal tissue following
deployment of the occluder in vivo. Similarly, the occluders
described herein may be used to deliver other drugs or
pharmaceutical agents (e.g., growth factors, peptides, or cells).
The anti-thrombogenic compounds, drugs, and/or pharmaceutical
agents may be included in the occluders of the present invention in
several ways, including by incorporation into the tissue scaffold,
as previously described, or as a coating, e.g. a polymeric coating,
on the tube(s) forming the distal side and proximal side of the
occluder. Furthermore, the occluders described herein may include
cells that have been seeded within the tissue scaffold or coated
upon the tube(s) forming the distal side and proximal side of the
occluder.
[0049] In some of the embodiments, such as that of FIG. 1, the
occluder can be unitary or even monolithic (except for coatings or
other surface treatments).
[0050] Having described preferred embodiments of the invention, it
should be apparent that various modifications may be made without
departing from the spirit and scope of the invention. While the
device can be made from an extruded tube, pieces of polymer or
other material can also be used to make the device by applying
different joining methods such as welding, gluing, etc. The strands
may have circular or polygonal cross-sections. The device can also
be molded. The tube cross-section may be circular or polygonal
(including square and rectangular). While in most cases, each end
has the same number of slits or loops, either aligned or offset,
each end can be formed differently; e.g., one end could have a
different number or configuration of struts.
* * * * *