U.S. patent application number 13/911515 was filed with the patent office on 2013-12-12 for apparatus for replacing a native heart valve and method of making the same.
The applicant listed for this patent is Boston Scientific Scimed Inc.. Invention is credited to Peter W. Gregg, Ali Salahieh, Benjamin T. Sutton, Jarad Waisblatt, Jianhua Yang.
Application Number | 20130331931 13/911515 |
Document ID | / |
Family ID | 48703830 |
Filed Date | 2013-12-12 |
United States Patent
Application |
20130331931 |
Kind Code |
A1 |
Gregg; Peter W. ; et
al. |
December 12, 2013 |
Apparatus for Replacing a Native Heart Valve and Method of Making
the Same
Abstract
An apparatus for replacement a native heart valve is herein
provided. The apparatus includes a replacement heart valve, an
expandable anchor, and a plurality of rivets. The expandable anchor
comprises a woven braid structure that surrounds at least a portion
of the replacement heart valve and has a plurality of braid
intersections. At least some of the braid intersections have rivets
extending therethrough.
Inventors: |
Gregg; Peter W.; (Santa
Cruz, CA) ; Yang; Jianhua; (Saratoga, CA) ;
Waisblatt; Jarad; (San Jose, CA) ; Sutton; Benjamin
T.; (Scotts Valley, CA) ; Salahieh; Ali;
(Saratoga, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Boston Scientific Scimed Inc. |
Maple Grove |
MN |
US |
|
|
Family ID: |
48703830 |
Appl. No.: |
13/911515 |
Filed: |
June 6, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61656746 |
Jun 7, 2012 |
|
|
|
Current U.S.
Class: |
623/2.11 |
Current CPC
Class: |
A61F 2/90 20130101; A61F
2/2418 20130101; A61F 2/243 20130101; A61F 2220/0041 20130101; A61F
2/2412 20130101; A61F 2/2427 20130101 |
Class at
Publication: |
623/2.11 |
International
Class: |
A61F 2/24 20060101
A61F002/24 |
Claims
1. An apparatus for replacing a native heart valve comprising: an
expandable anchor; a replacement heart valve attached to the
expandable anchor; and a plurality of rivets; the expandable anchor
comprising a woven braid structure surrounding at least a portion
of the replacement heart valve, the woven braid structure having a
plurality of braid intersections, each braid intersection having a
first wire segment and a second wire segment overlapping the first
wire segment; one of the rivets extending through the first wire
segment and the second wire segment at the braid intersection,
wherein the first wire segment is hingeable with respect to the
second wire segment.
2. The apparatus of claim 1, wherein the rivets comprise a central
portion and two end portions, the central portion having a smaller
cross-section than the two end portions.
3. The apparatus of claim 1, wherein the anchor is formed from a
single strand of wire.
4. The apparatus of claim 1, wherein the anchor comprises a
plurality of rows of braid intersections including a first row of
braid intersections, the first row of braid intersections having a
plurality of rivets.
5. The apparatus of claim 4, wherein the anchor comprises a
plurality of columns of braid intersections, wherein the first row
of braid intersections has rivets in at least two adjacent
columns.
6. The apparatus of claim 5, wherein the first two of braid
intersections has rivets in at least four adjacent columns.
7. The apparatus of claim 1 further comprising a plurality of
buckles attached to the anchor, the anchor having braid
intersections on both sides of the buckles, at least one of the
braid intersections on at least one side of the buckles having a
rivet.
8. The apparatus of claim 7, wherein the braid intersections on
both sides of the buckles have a rivet.
9. The apparatus of claim 1 further comprising a plurality of posts
and buckles, the posts insertable into the buckles.
10. The apparatus of claim 1, wherein at least one of the first and
second wire segments comprises a wear resistant oxide layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This Application claims the benefit of and priority to U.S.
Provisional Application No. 61/656,746, filed Jun. 7, 2012, the
entire contents of which are herein incorporated by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] Not Applicable
BACKGROUND OF THE INVENTION
[0003] Various types of replacement heart valve stents and devices
are known in the art. In particular, self-expanding medical devices
are widely used in percutaneous implantation. Certain types of
these devices suffer from a number of drawbacks, however. In
particular, when used to replace heart valves, these devices
undergo cyclical loading due to the opening and closing of the
valve. These cyclical loads can translate into fatigue, which is
undesirable because it can cause valve failure having catastrophic
implications for the patient. Consequently, there remains a need
for a replacement heart valve and anchor with increased fatigue
resistance.
[0004] The art referred to and/or described above is not intended
to constitute an admission that any patent, publication or other
information referred to herein is "prior art" with respect to this
invention. In addition, this section should not be construed to
mean that a search has been made or that no other pertinent
information as defined in 37 C.F.R. .sctn.1.56(a) exists.
[0005] All US patents and applications and all other published
documents mentioned anywhere in this application are incorporated
herein by reference in their entirety.
[0006] Without limiting the scope of the invention a brief summary
of some of the claimed embodiments of the invention is set forth
below. Additional details of the summarized embodiments of the
invention and/or additional embodiments of the invention may be
found in the Detailed Description of the Invention below.
BRIEF SUMMARY OF THE INVENTION
[0007] In some embodiments, an apparatus for replacing a native
heart valve comprises an expandable anchor and a replacement heart
valve attached to the expandable anchor. In some embodiments, the
apparatus further comprises a plurality of rivets. In some
embodiments, the expandable anchor comprises a woven braid
structure surrounding at least a portion of the replacement heart
valve, the woven braid structure having a plurality of braid
intersections. In some embodiments, each braid intersection has a
first wire segment and a second wire segment overlapping the first
wire segment. In some embodiments, one of the rivets extends
through the first wire segment and the second wire segment at the
braid intersection, the first wire segment is hingeable with
respect to the second wire segment.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of a replacement heart valve
and anchor.
[0009] FIG. 2A shows a side view of an embodiment of a braid
intersection.
[0010] FIG. 2B shows a cross-sectional view of the braid
intersection of FIG. 2A.
[0011] FIGS. 3A-3D show flat-patterns of the braid anchor 42.
[0012] FIG. 4 shows a flat-pattern of an embodiment of the braid
anchor 42.
[0013] FIG. 5 shows an embodiment of a braid intersection having a
coating thereon.
[0014] FIG. 6A shows a strain plot.
[0015] FIG. 6B shows a PRIOR ART Goodman Diagram.
[0016] FIG. 6C shows a Goodman Diagram of an embodiment of the
braid anchor 42.
[0017] FIGS. 7 and 8 show embodiments of the braid anchor 42 having
a variable braid density.
DETAILED DESCRIPTION OF THE INVENTION
[0018] While this invention may be embodied in many different
forms, there are described in detail herein specific embodiments.
This description is an exemplification of the principles of the
invention and is not intended to limit it to the particular
embodiments illustrated.
[0019] For the purposes of this disclosure, like reference numerals
in the figures shall refer to like features unless otherwise
indicated.
[0020] In some embodiments, an apparatus for replacing a native
heart valve comprises a replacement heart valve 40 and an anchor
42. In some embodiments, the anchor 42 comprises a woven braid
structure, for example as shown in FIG. 1. The woven braid
structure comprises a plurality of braid intersections 44.
[0021] Turning to FIGS. 2A and 2B, in some embodiments, one or more
of the braid intersections 44 has a rivet 46 extending
therethrough. The braid intersections 44 are formed at the overlap
of a first wire segment 20 and a second wire segment 22. The first
and second wire segments 20, 22 are able to pivot or scissor about
rivet axis 24.
[0022] In some embodiments, the rivet 46 comprises a central
portion 26 and end portions 28 on either side of the central
portion 26. The end portions 28 have a greater cross-sectional area
than the central portion 26. In some embodiments, the rivet 46
[0023] In some embodiments, the rivet 46 is inserted through holes
in the first and second wire segments 20, 22. In some embodiments,
the holes are cut through the wire segments 20, 22 by way of
Electrical Discharge Machining (EDM) or laser cutting. Other
methods are also suitable.
[0024] In some embodiments, the rivet 46 is a blind rivet. In some
embodiments, the rivet 46 is a solid rivet. In some embodiments,
the rivet 46 pins the braid intersection 44 together without a
tight interference fit between the central portion 26 and the hole
through which it extends. In this way, the first and second wire
segments 20, 22 are permitted to freely scissor about the rivet
axis 24 without deformation.
[0025] In some embodiments, the rivet 46 is made from the same
material as the wire segments 20, 22 to prevent corrosion due to
dissimilar materials. In particular, in some embodiments, the
rivets 46 are made from titanium or a nickel-titanium alloy. Other
materials are also suitable.
[0026] As shown in FIGS. 3A-D, in some embodiments, the anchor 42
is formed in a plurality of rows 30 and a plurality of columns 32.
The rows 30 and columns 32 intersect one another at the braid
intersections 44. For the purpose of illustration, the rows 30 are
labeled A through O' and columns are labeled 1 through 15.5, as
shown.
[0027] In some embodiments, the anchor 42 has a plurality of posts
36 and buckles 38. In some embodiments, the posts 36 engage the
buckles 38 as discussed in US Publication No. 2005/0143809, which
is herein incorporated by reference. As shown in FIG. 3A, in some
embodiments, the anchor 42 has rivets 46 adjacent to buckles 38 and
in between posts 36. In particular, as shown, each buckle 38 has a
single rivet 46 at an adjacent braid intersection 44. Rivets 46 are
placed along row B' at columns 11.5, 6.5, and 1.5.
[0028] As further shown in FIG. 3A, rivets 46 are disposed along
row O at columns 9, 4, and 14, staggered between posts 36. Row O is
the first row from the bottom 48 or inlet side of the anchor 42. In
some embodiments, rivets 46 are placed between posts 36 and near
the bottom 48 of anchor 42 in order to provide fatigue resistance.
In particular, in some embodiments, stress is induced in the anchor
42 due to actuation of the replacement heart valve 40 (FIG. 1) as
it operates. Without being bound by a particular theory, it is
believed that placement of the rivets 46 between posts 36 reduces
fatigue in the anchor 42. Moreover, in some embodiments, the rivets
46 prevent overlapping first and second wire segments 20, 22 from
being pulled apart as the replacement heart valve 40 actuates. In
some embodiments, rivets 46 prevent first and second wire segments
20, 22 from being pulled apart in a radial direction, an axial
direction, and a circumferential direction. Nonetheless, the first
and second wire segments 20, 22 can pivot relative to another about
rivet axis 24 (FIG. 2B).
[0029] Turning to FIG. 3B, in some embodiments, rivets 46 are
placed on both sides of the buckles 38, for example along row B' at
columns 11.5, 10.5, 6.5, 5.5, 1.5, and 15.5. Further, rivets 46 are
placed between posts 36 along row O at columns 9, 8, 4, 3, 14, and
13. In this way, there are two adjacent braid intersections 44
along row O with rivets 46, followed by a braid intersection 44
without a rivet, followed by a post 36, followed by another braid
intersection 44 without a rivet, followed by two rivets 46 at
adjacent braid intersections 44.
[0030] As shown in FIG. 3C, the anchor 42 comprises two rivets 46
on either side of the buckles 38. In some embodiments, rivets 46
are located along row A' at columns 11.5, 10.5, 6.5, 5.5, 1.5, and
15.5 and along row B' at columns 11.5, 10.5, 6.5, 5.5, 1.5, and
15.5. In addition, rivets 46 are located along row O at columns 10,
9, 8, 7, 5, 4, 3, 2, 15, 14, 13, and 12.
[0031] With reference to FIG. 3D, the anchor 42 comprises two
rivets 46 on either side of the buckles 38. In some embodiments,
rivets 46 are located along row A' at columns 11.5, 10.5, 6.5, 5.5,
1.5, and 15.5 and along row B' at columns 11.5, 10.5, 6.5, 5.5,
1.5, and 15.5. Additionally, in some embodiments, rivets 46 are
located along row N' at columns 9.5, 8.5, 7.5, 4.5, 3.5, 2.5, 14.5,
13.5, and 12.5 and along row O at columns 10, 9, 8, 7, 5, 4, 3, 2,
15, 14, 13, and 12.
[0032] As further shown in each of FIGS. 3A-3D, in some
embodiments, the anchor 46 has a radiopaque marker 50. The
radiopaque marker 50 provides visibility during and after
implantation of the anchor 42. In some embodiments, the radiopaque
marker 50 is made from tantalum. Other radiopaque materials can
also be used.
[0033] Turning to FIG. 4, an anchor 42 is shown therein having a
woven braid structure comprising a plurality of braid intersections
44. Throughout most of the woven braid structure of the anchor 42,
the wire 18 follows an over-under-over-under pattern of weaving. In
this way, the wire 18 is woven over an intersecting segment of wire
and woven under the adjacent intersecting segment, and so-forth.
Along portions of the anchor 42, for example at or near the buckles
38, however, the wire 18 is woven in a modified pattern. As shown
for example at column 7, row C; column 6.5, row B'; and column 6,
row B, the second wire segment 22a is routed over three adjacent
first wire segments 20a. Further, at column 7, row B and column
6.5, row B', the second wire segment 22a is routed over the
adjacent first wire segments 20a. Finally, at column 6, row C and
column 5.5, row C', the first wire segment 20a is routed over the
adjacent second wire segments 22a.
[0034] In some embodiments, the anchor 42 follows this modified
pattern at the braid intersections 44 adjacent to the buckles 38.
In some embodiments, this modified pattern reduces wear in the wire
18. Without being bound by a particular theory, it is believed that
due to loading and separation of first and second wire segments
20a, 22a at the braid intersections 44 near the buckles 38, the
wire 18 of the wire segments 20a, 22a near the buckles 38 undergoes
more wear than at braid intersections 44 that are further away from
the buckles 38. The loading and separation is caused by actuation
of the replacement heart valve 40 (FIG. 1). In particular, as the
replacement heart valve 40 actuates, it flexes the first and second
wire segments 20a, 22a. Moreover, the wire segments 20a, 22a near
the buckles 38 experience the greatest amount of stress because, in
some embodiments, the replacement heart valve 40 is attached to the
buckles 38 which are, in turn, attached to the wire segments 20a,
22a of the anchor 42. Consequently, actuation of the replacement
heart valve 40 separates the first and second wire segments 20a,
22a at the braid intersections 44 by pulling them apart in a radial
direction (in/out of the page in the flat pattern of FIG. 4). In
some embodiments, for example as shown in FIG. 4, arranging the
wire 18 in such a modified pattern at the braid intersections 44
adjacent to the buckles 38, decreases wire wear. In addition to the
foregoing, in some embodiments, the wire 18 is routed in such a
modified pattern at the braid intersections 44 adjacent to each of
the buckles 38.
[0035] In some embodiments, the anchor 42 has a different braid
density at the bottom 48 of the anchor 42 than at the top 64 or
outlet. In some embodiments, the braid wires 18 are closer together
at the bottom 48 of the anchor 42 than at the top 64. In some
embodiments, the bottom 48 or inlet side of the anchor 42
experiences greater loading due to opening and closing of the
replacement heart valve 40 than does the top 64 of the anchor 42.
Consequently, in some embodiments, the area(s) of greater loading
have a higher braid density, with more braid intersections 44 per
unit area, than the area(s) of lesser loading.
[0036] In some embodiments, a higher braid density is achieved by
varying the pin spacing on the braid mandrel. An example of a braid
mandrel is shown in FIGS. 3-4D of US Publication No. 2008/0125859,
which is herein incorporated by reference. Moreover, in some
embodiments, the wire is heat-set on the mandrel to maintain the
shape of the anchor 42 upon removal from the mandrel.
[0037] Further, in some embodiments, the braid density increases
gradually throughout the length of the anchor 42. In some
embodiments, however, the change in braid density is more abrupt.
Suitable embodiments of anchors 42 having increased braid density
along a portion of the anchor are shown for example in FIGS. 7 and
8.
[0038] In some embodiments, the wire 18 is formed from a
nickel-titanium alloy. Additionally, in some embodiments, the wire
18 is heat treated and a wear resistant oxide layer is formed on
the surface of the wire 18. In some embodiments, the entire length
of the wire 18 has an oxide layer. Alternatively, in some
embodiments, only portions of the wire 18 have an oxide layer.
[0039] Turning to FIG. 5, in some embodiments, the wire 18 has a
biocompatible coating 53 over a portion, or the entire length,
thereof. Further, in some embodiments, the biocompatible coating 53
promotes tissue growth at the braid intersections 44. In some
embodiments, the biocompatible coating 53 comprises polyurethane.
Moreover, in some embodiments, the biocompatible coating 53 is
placed on the wire 18 at the braid intersections 44 and the
portions of wire 18 between the braid intersections 44 do not have
biocompatible coating thereon. In some embodiments, portions of the
wire 18 are masked off prior to coating. In this way, the wire 18
can have biocompatible coating 53 on selected portions. Having
biocompatible coating 53 on only selected portions of the wire 18
can be advantageous when compared to embodiments having the coating
over the entire length of the wire 18. In particular, the
biocompatible coating 53 has a thickness, t, which can increase the
profile of the anchor 42 in its unexpanded configuration. Coating
only selected portions of the wire 18 with the biocompatible
coating 53, however, permits the anchor 42 to have a smaller
profile in the unexpanded configuration, thereby reducing the
potential for complications during the implantation procedure.
[0040] In some embodiments, the wire 18, or portions thereof, is
pre-strained in tension. This provides the anchor 42 with improved
fatigue life. In particular, opening and closing of the replacement
heart valve 40 applies a cyclical load to the braid wires 18,
especially where the braid wires 18 are attached to the replacement
heart valve 40. The loading induces strain in the braid wires 18,
which causes fatigue.
[0041] The strain can be broken down into two components, namely
"mean strain," .epsilon..sub.m and "alternating strain,"
.epsilon..sub.a. As will be appreciated by the skilled artisan, in
a reversing load application, the alternating strain,
.epsilon..sub.a, is defined as 1/2 of the peak-to-peak strain,
or:
a = max - min 2 ##EQU00001##
[0042] where .epsilon..sub.max is the maximum strain and
.epsilon..sub.min is the minimum strain, for example as shown in
FIG. 6A. Further, the mean strain, .epsilon..sub.m, is defined
as:
m = max + min 2 ##EQU00002##
[0043] Turning to FIGS. 6B and 6C, strain-based Goodman Diagrams
are shown therein depicting a typical Nitinol fatigue failure
envelope at reference numeral 52. Further shown along the limits of
the fatigue failure envelope 52 are the values of R, the strain
ratio in fatigue cycling. In general:
R = min max ##EQU00003##
[0044] Additionally, R is equal to negative one where the mean
strain, .epsilon..sub.m, is zero and the alternating strain,
.epsilon..sub.a, is fully reversing. R is equal to zero wherein the
mean strain, .epsilon..sub.m, and the alternating strain,
.epsilon..sub.a, are equal; .epsilon..sub.min is zero in this
instance. Finally R is equal to positive one when the alternating
strain, .epsilon..sub.a, is equal to zero.
[0045] FIG. 6B depicts the strain relationship of a PRIOR ART
replacement valve stent, shown with dashed line 54. In particular,
a PRIOR ART self-expanding valve stent expands to a diameter equal
to or smaller than its stress free diameter. When such a valve
stent is implanted and operating, the valve portion opens and
closes to permit proper blood flow. When the valve portion is open,
the strain on the self-expanding stent is at a minimum. In this
case, the strain is at a constant, k, greater than or equal to
zero, as shown below:
.epsilon..sub.min=.gtoreq.0
Moreover, when the valve portion of the PRIOR ART self-expanding
valve stent is in a closed configuration, the strain increases to a
maximum strain .epsilon..sub.max. The PRIOR ART self-expanding
valve stent can therefore be modeled as:
.epsilon..sub.min=.epsilon..sub.m-.epsilon..sub.a=k.gtoreq.0
This, in-turn, can be re-written as:
.epsilon..sub.m=.epsilon..sub.a+k
It will appreciated, therefore, that the slope of the line modeling
the PRIOR ART self-expanding valve stent is one (1), as shown in
FIG. 6B with reference numeral 54. It will further be appreciated
that with increasing mean strain, .epsilon..sub.m, the average
strain, .epsilon..sub.a, also increases.
[0046] Contrastingly, and turning to FIG. 6C, in some embodiments,
the braided wires 18 of the immediate replacement heart valve
anchor 42 (FIG. 1) are pre-strained to counteract physiological
loading. In particular, in some embodiments, upon implantation, the
anchor 42 is expanded to a diameter larger than its stress free
diameter. In this instance, the braid wires 18 are in tension when
the anchor 42 is expanded, and without any applied loading from the
replacement heart valve 40. During operation, the replacement heart
valve 40 applies additional force to the anchor 42. Specifically,
in some embodiments, for example as shown in FIG. 1, the
replacement heart valve 40 is attached to the anchor 42, in-part,
along the bottom 44. As a result, when the replacement heart valve
40 opens and closes it induces strain on the anchor 42. In some
embodiments, the strain is concentrated along the bottom 44 in
regions opposite the apex 58 of the valve leaflet 60.
[0047] In some embodiments of the immediate anchor 42, maximum
tension in the braid wires 18 occurs when the replacement heart
valve 40 is open. In this way, the strain is at a maximum,
.epsilon..sub.max. Additionally, in some embodiments, the strain is
reduced as the replacement heart valve 40 closes, reaching a
minimum, .epsilon..sub.min, when the replacement heart valve 40 is
closed. As described previously, it will be appreciated that in
some embodiments this occurs because the anchor 42 has been
expanded to a diameter larger than its stress free diameter.
Consequently, the maximum strain, .epsilon..sub.max, is equal to
the sum of the mean strain, .epsilon..sub.m, and the alternating
strain, .epsilon..sub.a. In algebraic form, the anchor 42 can be
modeled as:
.epsilon..sub.max=.epsilon..sub.m+.epsilon..sub.a
This, in turn, can be re-written as:
.epsilon..sub.m=.epsilon..sub.max-.epsilon..sub..alpha.
where .epsilon..sub.max is the strain induced upon expansion and
implantation of the anchor 42, and can be set to a predetermined
value.
[0048] It will appreciated, therefore, that the slope of the line
modeling the immediate anchor 42 stent is negative one (-1), as
shown in FIG. 6C with reference numeral 56. It will further be
appreciated that with increasing mean strain, .epsilon..sub.m, the
average strain, .epsilon..sub.a, decreases. As further shown in
FIG. 6C, the behavior of the immediate anchor, modeled via line 56,
is expected to have a greater fatigue life than the known PRIOR ART
self-expanding valve stents, as modeled via line 54 in FIG. 6B,
because line 56 extends away from the horizontal fatigue failure
limit line 62.
[0049] In addition to the foregoing, and without being bound by a
particular theory, it is believed that line 56 is more likely to
remain in the austenitic phase of the nickel-titanium alloy, for
example Nitinol.RTM., than that of line 54, thereby further
reducing the likelihood of material fracturing due to phase
change.
[0050] In some embodiments, the curvature of the wire 18 is
increased at the braid intersections 44 and reduced between braid
intersections 44. In this way, in some embodiments, at the braid
intersections 44, the wires 18 are curved to maximize contact
therebetween. Without being bound by a particular theory, this is
believed to reduce localized wear in the wire 18 at the
intersections 44 by increasing the contact patch between the wires
18 at the braid intersections 44. Additionally, in some
embodiments, the wire 18 cross-section is flattened at the braid
intersections 44. Further, in some embodiments, one or more of the
intersecting wires 18 is notched at the braid intersections 44. In
some embodiments, the wire 18 is has a reduced or increased
cross-section at the braid intersections 44. Finally, in some
embodiments, the wire 18 has a non-uniform cross-section; for
example, in some embodiments, portions of the wire have circular
cross-sections while other portions have oval cross-sections. Other
suitable geometries can also be employed.
[0051] Further, in some embodiments, the wire 18 undergoes an
electro-polishing process. In some embodiments, the
electro-polishing process is a multi-stage process wherein the wire
diameter of the wire 18 is reduced by 20%. In some embodiments, the
multi-stage process involves electro-polishing the entire length of
the wire in a first step. Subsequently, only portions of the wire
18 are polished to selectively reduce the diameter of the wire 18
in specific locations. For example, in some embodiments, the
portion of the wire 18 forming the top 64 of the anchor 42 are only
polished a single time, while the remainder of the wire 18 is
polished two or more times.
[0052] The above disclosure is intended to be illustrative and not
exhaustive. This description will suggest many variations and
alternatives to one of ordinary skill in this art. The various
elements shown in the individual figures and described above may be
combined or modified for combination as desired. All these
alternatives and variations are intended to be included within the
scope of the claims where the term "comprising" means "including,
but not limited to".
[0053] Further, the particular features presented in the dependent
claims can be combined with each other in other manners within the
scope of the invention such that the invention should be recognized
as also specifically directed to other embodiments having any other
possible combination of the features of the dependent claims. For
instance, for purposes of claim publication, any dependent claim
which follows should be taken as alternatively written in a
multiple dependent form from all prior claims which possess all
antecedents referenced in such dependent claim if such multiple
dependent format is an accepted format within the jurisdiction
(e.g. each claim depending directly from claim 1 should be
alternatively taken as depending from all previous claims). In
jurisdictions where multiple dependent claim formats are
restricted, the following dependent claims should each be also
taken as alternatively written in each singly dependent claim
format which creates a dependency from a prior
antecedent-possessing claim other than the specific claim listed in
such dependent claim below.
[0054] This completes the description of the invention. Those
skilled in the art may recognize other equivalents to the specific
embodiment described herein which equivalents are intended to be
encompassed by the claims attached hereto.
* * * * *