U.S. patent application number 13/151893 was filed with the patent office on 2011-10-20 for vena cava fliter having hourglass shape.
This patent application is currently assigned to ABBOTT LABORATORIES. Invention is credited to David Mackiewicz.
Application Number | 20110257675 13/151893 |
Document ID | / |
Family ID | 40877056 |
Filed Date | 2011-10-20 |
United States Patent
Application |
20110257675 |
Kind Code |
A1 |
Mackiewicz; David |
October 20, 2011 |
VENA CAVA FLITER HAVING HOURGLASS SHAPE
Abstract
The present invention is a luminal filter including: a plurality
of filter elements interconnected so as to form a filter body
shaped in a free recovery form and having a plurality of apertures
disposed between and defined by the interconnected filter elements.
The apertures are dimensioned so as to inhibit a thrombus of a
selected size from passing through the apertures and being
dimensioned so as to allow blood components smaller than the
selected size to pass through the apertures. The filter body
includes a first funnel and second funnel coupled at least
indirectly coupled together at their small ends.
Inventors: |
Mackiewicz; David; (Scotts
Valley, CA) |
Assignee: |
ABBOTT LABORATORIES
Abbott Park
IL
|
Family ID: |
40877056 |
Appl. No.: |
13/151893 |
Filed: |
June 2, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12338981 |
Dec 18, 2008 |
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13151893 |
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61016273 |
Dec 21, 2007 |
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61016266 |
Dec 21, 2007 |
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Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61F 2230/005 20130101;
A61F 2/01 20130101; A61F 2230/0078 20130101; A61F 2002/018
20130101; A61F 2230/0006 20130101; A61F 2002/016 20130101 |
Class at
Publication: |
606/200 |
International
Class: |
A61F 2/01 20060101
A61F002/01 |
Claims
1. A filter for use in a body lumen of a subject, the filter
comprising: a plurality of filter elements interconnected so as to
form a filter body having a plurality of apertures disposed between
and defined by the interconnected filter elements, said filter body
comprising: a first funnel having a first funnel-shaped body
defining a first conduit having a first larger end fluidly coupled
to and opposite of a first smaller end, said first funnel-shaped
body having a plurality of first apertures defined by the
interconnected filter elements; and a second funnel having a second
funnel-shaped body defining a second conduit having a second larger
end fluidly coupled to and opposite of a second smaller end, said
second funnel-shaped body having a single spiral filter element
that spirals from the second smaller end to the second larger end,
with the single spiral filter element being wound tighter at the
second smaller end than at the second larger end.
2. The filter as in claim 1, wherein the single spiral filter
element defines an aperture that spirally extends from the second
smaller end to the second larger end.
3. The filter as in claim 2, wherein a cross section of the
aperture increases as the aperture spirally extends from the second
smaller end to the second larger end.
4. The filter as in claim 1, wherein the filter body is configured
such that the first larger end of the first funnel and the second
larger end of the second funnel each have a reduced dimension when
tensile longitudinal forces are applied to the filter body.
5. The filter as in claim 4, wherein the filter body is configured
such that the first larger end of the first funnel and the second
larger end of the second funnel have an enlarged dimension when
compressive longitudinal forces are applied to the filter body or
tensile forces are released from the filter body.
6. The filter as in claim 5, wherein at least one of the first
funnel or second funnel is shaped to trap the thrombus of the
selected size within the respective conduit at a central axial
position, and at least one of the first apertures or second
apertures are dimensioned so as to inhibit the thrombus of the
selected size from passing therethrough and being dimensioned so as
to allow blood components smaller than the selected size to pass
therethrough.
7. The filter as in claim 5, wherein the filter body has sufficient
rigidity to reconfigure the body lumen from an oblong-shaped cross
section to a circular-shaped cross section.
8. A filter for use in a body lumen of a subject, the filter
comprising: a plurality of filter elements interconnected so as to
form a filter body having a plurality of apertures disposed between
and defined by the interconnected filter elements, said filter body
comprising: a first funnel having a first funnel-shaped body
defining a first conduit having a first larger end fluidly coupled
to and opposite of a first smaller end, said first funnel-shaped
body having a first single spiral filter element that spirals from
the first smaller end to the first larger end, with the first
single spiral filter element being wound tighter at the first
smaller end than at the first larger end; a second funnel having a
second funnel-shaped body defining a second conduit having a second
larger end fluidly coupled to and opposite of a second smaller end,
said second funnel-shaped body having a single spiral filter
element that spirals from the second smaller end to the second
larger end, with the second single spiral filter element being
wound tighter at the second smaller end than at the second larger
end; and a median portion having a median body defining a median
conduit having a first end coupled to the first smaller end of the
first funnel and having a second end coupled to the second smaller
end of the second funnel, said median conduit being dimensioned so
as to inhibit a thrombus of a selected size from passing through
the median conduit.
9. The filter as in claim 8, wherein the first single spiral filter
element and defines a first aperture that spirally extends from the
first smaller end to the first larger end, a cross section of the
first aperture increases as the second aperture spirally extends
from the first smaller end to the first larger end.
10. The filter as in claim 9, wherein the second single spiral
filter element and defines a second aperture that spirally extends
from the second smaller end to the second larger end, a cross
section of the second aperture increases as the second aperture
spirally extends from the second smaller end to the second larger
end.
11. The filter as in claim 8, wherein the filter body is configured
such that the first larger end of the first funnel and the second
larger end of the second funnel have a reduced dimension when
tensile longitudinal forces are applied to the filter body.
12. The filter as in claim 11, wherein the filter body is
configured such that the first larger end of the first funnel and
the second larger end of the second funnel have an enlarged
dimension when compressive longitudinal forces are applied to the
filter body or tensile forces are released from the filter
body.
13. The filter as in claim 8, said filter body further comprising
at least one of the following: a first tube having a first
tube-shaped body defining a first tube conduit and having a first
end fluidly coupled to the first larger end of the first
funnel-shaped body, said first tube having a first length; or a
second tube having a second tube-shaped body defining a second tube
conduit and having a second end fluidly coupled to the second
larger end of the second funnel-shaped body, said second tube
having a second length.
14. The filter as in claim 13, wherein at least one of the
following: the first length of the first tube is dimensioned to
inhibit the filter from migrating within the body lumen of the
subject; or the second length of the second tube is dimensioned to
inhibit the filter from migrating within the body lumen of the
subject.
15. The filter as in claim 13, wherein at least one of the first
length or second length has a dimension from about 0 mm to about 50
mm.
16. The filter as in claim 15, wherein at least one of the first
funnel or second funnel is shaped to trap the thrombus of the
selected size within the respective conduit at a central axial
position, and at least one of the first apertures or second
apertures are dimensioned so as to inhibit the thrombus of the
selected size from passing therethrough and being dimensioned so as
to allow blood components smaller than the selected size to pass
therethrough.
17. The filter as in claim 8, wherein the filter body has
sufficient rigidity to reconfigure the body lumen from an
oblong-shaped cross section to a circular-shaped cross section.
18. A filter for use in a body lumen of a subject, the filter
comprising: a plurality of filter elements interconnected so as to
form a filter body having a plurality of apertures disposed between
and defined by the interconnected filter elements, said filter body
comprising: a first funnel having a first funnel-shaped body
defining a first conduit having a first larger end fluidly coupled
to and opposite of a first smaller end, said first funnel-shaped
body having a first single spiral filter element that spirals from
the first smaller end to the first larger end and a first aperture
that spirally extends from the first smaller end to the first
larger end, the single spiral filter element being wound tighter at
the first smaller end than at the first larger end; a second funnel
having a second funnel-shaped body defining a second conduit having
a second larger end fluidly coupled to and opposite of a second
smaller end, said second funnel-shaped body having a second single
spiral filter element that spirals from the second smaller end to
the second larger end and a second aperture that spirally extends
from the second smaller end to the second larger end, the second
single spiral filter element being wound tighter at the second
smaller end than at the second larger end; and a median portion
having a median body defining a median conduit having a first end
coupled to the first smaller end of the first funnel and having a
second end coupled to the second smaller end of the second funnel,
said median conduit being dimensioned so as to inhibit a thrombus
of a selected size from passing through the median conduit.
19. The filter as in claim 18, said filter body further comprising
at least one of the following: a first tube having a first
tube-shaped body defining a first tube conduit and having a first
end fluidly coupled to the first larger end of the first
funnel-shaped body, said first tube having a first length; or a
second tube having a second tube-shaped body defining a second tube
conduit and having a second end fluidly coupled to the second
larger end of the second funnel-shaped body, said second tube
having a second length.
20. The filter as in claim 19, wherein the first tube or the second
tube comprises the plurality of interconnected filter elements.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation application of U.S. patent
application Ser. No. 12/338,981, filed Dec. 18, 2008, and entitled
"Vena Cava Filter Having Hourglass Shape", which claims the benefit
of and priority to U.S. Provisional Patent Application No.
61/016,273, filed Dec. 21, 2007, and entitled "Vena Cava Filter
Having Hourglass Shape" and U.S. Provisional Patent Application No.
61/016,266 filed Dec. 21, 2007, and entitled "Vena Cava Filter
Having Wall Contacts", each of which is incorporated herein by
reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. The Field of the Invention
[0003] The present invention relates to a filter for use in a body
lumen, such as the vena cava. More particularly, the present
invention relates to a lumen filter that has substantially an
hourglass shape or other substantially symmetrical shape about a
central point.
[0004] 2. Background
[0005] Vein thrombosis is a medical condition wherein a blood clot,
or thrombus, has formed inside a vein. Such a clot often develops
in the calves, legs, or lower abdomen, but can also affect other
veins in the body. The clot may partially or completely block blood
flow, and may break off and travel through the bloodstream.
Commonly, the clot is caused by a pooling of blood in the vein,
often when an individual is bed-ridden for an abnormally long
duration of time, for example, when resting following surgery or
suffering from a debilitating illness, such as a heart attack or
traumatic injury. However, there are many other situations that
cause the formation of a blood clot.
[0006] Vein thrombosis is a serious problem because of the danger
that the clot may break off and travel through the bloodstream to
the lungs, causing a pulmonary embolism. This is similar to a
blockage of the blood supply to the lungs that causes severe
hypoxia and cardiac failure, and frequently results in death. For
many patients, anti-coagulant drug therapies may be sufficient to
dissipate the clots. For example, patients may be treated with
anticoagulants such as heparin and with thrombolytic agents such as
streptokinase.
[0007] Unfortunately, some patients may not respond to such drug
therapy or may not tolerate such therapy. Also, there may be other
reasons why an anticoagulant is not desirable. For example,
patients may have an acute sensitivity to heparin or may suffer
from prolonged internal and/or external bleeding as a result of
such drug therapies. Also, such drug therapies simply may be
ineffective in preventing recurrent pulmonary emboli. In such
circumstances, surgical procedures are required to prevent
pulmonary emboli. Methods for prevention of primary or recurrent
pulmonary emboli when anticoagulation therapies are ineffective are
well-defined in the prior art. The current standard of therapy for
prevention of pulmonary emboli in patients who are classified
high-risk or are unable to be anticoagulated is percutaneous
insertion and placement of an inferior vena cava filter device.
[0008] Additionally, a pulmonary embolism is an obstruction of the
pulmonary artery or one of its branches by a blood clot or other
foreign substance. A pulmonary embolism can be caused by a blood
clot which migrated into the pulmonary artery or one of its
branches. Mechanical interruption of the inferior vena cava
presents an effective method of preventing of pulmonary
embolisms.
[0009] Vena cava filters are devices which are implanted in the
inferior vena cava, providing a mechanical barrier to undesirable
particulates. The filters are used to filter peripheral venous
blood clots and other particulates, which if remaining in the blood
stream can migrate in the pulmonary artery or one of its branches
and cause harm.
[0010] Conventional implantable blood filters employing a variety
of geometries are known. Many are generally basket shaped, in order
to provide adequate clot-trapping area while permitting sufficient
blood flow. Also known are filters formed of various loops of wire,
including some designed to partially deform the vessel wall in
which they are implanted. A detailed discussion of the construction
and use of such filters is contained in U.S. Pat. No. 5,893,869
issued to Barnhart, which is incorporated herein by reference.
Additional information on such filters can also be found in an
article entitled "Percutaneous Devices for Vena Cava Filtration" by
Daniel E. Walsh and Michael Bettmann contained in Current Therapy
in Vascular Surgery (3d ed. 1995) at pages 945-949; this article is
also incorporated herein by reference.
[0011] Along with their many functional shapes, conventional
filters may include other features. For example, peripheral arms
may be provided to perform a centering function so that a filter is
accurately axially aligned with the vessel in which it is
implanted. In order to prevent migration under the pressure induced
by normal circulation, many filters have anchoring features. Such
anchoring features may include hook or ridges.
[0012] Many presently used vena cava filters are permanently
implanted in the inferior vena cava and remain there for the
duration of the patient's life or are removably implanted, but
still which remain in position for long durations. As such, the
filters can incur tissue ingrowth from the surrounding tissue,
resulting in a decreased blood flow and in blood clots. While some
permanent filters are designed to be percutaneously retrievable,
they often become embedded as their anchoring features become
endothelialized by the vessel wall and retrieval must be done
surgically.
BRIEF SUMMARY OF THE INVENTION
[0013] The present invention provides a filter for use in a body
lumen. For example, as the filter can be a vena cava filter. More
particularly, the present invention provides a lumen filter that
has substantially an hourglass shape or other substantially
symmetrical shape about a central point that is formed by being
laser cut from a tube or braided and then formed into the free
recovery shape so as to longitudinally elongate and radially
collapse during deployment or retrieval and to longitudinally
shorten and radially expand after being set.
[0014] In one embodiment, the present invention is a filter for use
in a body lumen of a subject. Such a filter includes a plurality of
filter elements interconnected so as to form a filter body having a
plurality of apertures disposed between and defined by the
interconnected filter elements. The apertures are dimensioned so as
to inhibit a thrombus of a selected size from passing through the
apertures and are dimensioned so as to allow blood components
smaller than the selected size to pass through the apertures. The
filter body includes: a first funnel having a first funnel-shaped
body defining a first conduit having a first larger end fluidly
coupled to and opposite of a first smaller end, the first
funnel-shaped body having a plurality of first apertures defined by
the interconnected filter elements; and a second funnel having a
second funnel-shaped body defining a second conduit having a second
larger end fluidly coupled to and opposite of a second smaller end,
the second funnel-shaped body having a plurality of second
apertures defined by the interconnected filter elements, the second
smaller end of the second funnel is fluidly coupled to the first
smaller end of the first funnel, the first smaller end and second
smaller end are dimensioned so as to inhibit a thrombus of a
selected size from passing therethrough.
[0015] In one embodiment, a luminal filter includes the following:
a plurality of filter elements interconnected so as to form a
filter body having a plurality of apertures disposed between and
defined by the interconnected filter elements, the apertures are
dimensioned so as to inhibit a thrombus of a selected size from
passing through the apertures and are dimensioned so as to allow
blood components smaller than the selected size to pass through the
apertures; a first funnel having a first funnel-shaped body
defining a first conduit having a first larger end fluidly coupled
to and opposite of a first smaller end, the first funnel-shaped
body having a plurality of first apertures defined by the
interconnected filter elements; a second funnel having a second
funnel-shaped body defining a second conduit having a second larger
end fluidly coupled to and opposite of a second smaller end, the
second funnel-shaped body having a plurality of second apertures
defined by the interconnected filter elements; and a median portion
having a median body defining a median conduit having a first end
coupled to the first smaller end of the first funnel and having a
second end coupled to the second smaller end of the second funnel,
the median conduit being dimensioned so as to inhibit a thrombus of
a selected size from passing through the median conduit.
[0016] In one embodiment, the filter body is configured such that
the first larger end of the first funnel and the second larger end
of the second funnel each have a reduced dimension when tensile
longitudinal forces are applied to the filter body. Also, the
filter body is configured such that the first larger end of the
first funnel and the second larger end of the second funnel each
have an enlarged dimension when compressive longitudinal forces are
applied to the filter body.
[0017] In one embodiment, the filter body further includes at least
one of the following: a first tube having a first tube-shaped body
defining a first tube conduit and having a first end fluidly
coupled to the first larger end of the first funnel-shaped body,
said first tube having a first length; or a second tube having a
second tube-shaped body defining a second tube conduit and having a
second end fluidly coupled to the second larger end of the second
funnel-shaped body, said second tube having a second length. The
first length of the first tube and/or the second length of the
second tube can be dimensioned to inhibit the filter from migrating
within the body lumen of the subject. This can include at least one
of the first length or second length having a dimension from about
0 (or 0.0001 millimeters) to about 10 millimeters, or any size
therebetween.
[0018] In one embodiment, at least one of the first funnel or
second funnel is shaped to trap the thrombus of the selected size
within the respective conduit at a central axial position and to
allow removal of the thrombus when the filter is removed. At least
one of the first apertures or second apertures are dimensioned so
as to inhibit the thrombus of the selected size from passing
therethrough and being dimensioned so as to allow blood components
smaller than the selected size to pass therethrough.
[0019] In one embodiment, the filter body has sufficient rigidity
to reconfigure the body lumen from an oblong-shaped cross section
to a circular-shaped cross section. In one embodiment, the
interconnected filter elements are formed from laser shaping the
filter body. In one embodiment, the interconnected filter elements
are formed from braids.
[0020] In one embodiment, the present invention provides a method
of utilizing a luminal filter in a body lumen of a subject. Such a
method includes the following: providing a luminal filter having a
plurality of filter elements interconnected so as to form a filter
body having a plurality of apertures disposed between and defined
by the interconnected filter elements, the apertures being
dimensioned so as to inhibit a thrombus of a selected size from
passing through the apertures and being dimensioned so as to allow
blood components smaller than the selected size to pass through the
apertures, the filter body is configured as described herein;
longitudinally elongating the filter body such that the larger ends
of the filter have a reduced dimension; delivering the elongated
filter body to a desired deployment site within the body lumen of
the subject; and longitudinally shortening the filter body such
that the larger ends of the filter each have an enlarged dimension
that applies radial forces to an inner wall of the body lumen.
[0021] In one embodiment, such a method can optionally further
include: longitudinally elongating the filter body such that the
larger ends filter have a reduced dimension with a cross section
that is smaller than the body lumen; and retrieving the elongated
filter body from the desired deployment site within the body lumen
of the subject.
[0022] In one embodiment, at least one of delivering or retrieving
the filter is performed with a catheter.
[0023] These and other embodiments and features of the present
invention will become more fully apparent from the following
description and appended claims, or may be learned by the practice
of the invention as set forth hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] To further clarify the above and other advantages and
features of the present invention, a more particular description of
the invention will be rendered by reference to specific embodiments
thereof which are illustrated in the appended drawings. It is
appreciated that these drawings depict only typical embodiments of
the invention and are therefore not to be considered limiting of
its scope. The invention will be described and explained with
additional specificity and detail through the use of the
accompanying drawings. Moreover, the features of the drawings are
not drawn to scale it is understood that one of ordinary skill in
the arts would understand the appropriate size and size-relatedness
of the various features shown in the figures.
[0025] FIG. 1A is a schematic representation illustrating a side
view of an embodiment of a filter having a free recovery shape.
[0026] FIG. 1B is a cross-sectional view of the filter of FIG.
1A.
[0027] FIGS. 2A-2D are schematic representations illustrating side
views of embodiments of filters having free recovery shapes.
[0028] FIGS. 3A-3F are schematic representations illustrating
cross-sectional profiles for embodiments of filters having a free
recovery shape.
[0029] FIG. 4A is a schematic representation illustrating a cutaway
view of an embodiment of a delivery system delivering an embodiment
of the filter into a body lumen.
[0030] FIG. 4B is a schematic representation illustrating a cutaway
view of the filter of FIG. 4A after being deployed within the body
lumen.
DETAILED DESCRIPTION
[0031] The present invention provides a filter for use in a body
lumen, such a lumen filter can be configured as a vena cava filter.
More particularly, the present invention provides a lumen filter
that has substantially an hourglass shape or other substantially
symmetrical shape about a central point that is formed by being
laser cut from a tube or braided and then formed into the free
recovery shape so as to longitudinally elongate and radially
collapse during delivery or retrieval and to longitudinally shorten
and radially expand after being set. The substantially hourglass
shape can be referred to as a free recovery shape because it allows
for the body to longitudinally elongate and radially collapse
during delivery or retrieval and to longitudinally shorten and
radially expand after being set. Thus, the free recovery shape
allows for easy delivery and provides for the possibility of
retrieval.
I. Introduction
[0032] Accordingly, the present invention is a filter that is
implantable in a blood vessel or other lumen in the body of the
patient. Such filters may utilize one or more members arranged to
capture particulates within the blood flow, without substantially
interfering with the normal blood flow. Such a filter can be formed
from a shape memory material for implantation into a vessel and
subsequent extraction therefrom. The vascular filter captures
particulates (e.g. thrombus) within the blood flow in the vessel,
and retains such particulates during extraction. Prior to
implantation, the filter is generally longitudinally elongated and
radially collapsed. The filter can be delivered with a delivery
device that is compatible with or includes a catheter. After being
inserted to the place of deployment, the filter reverts to a
predetermined shape that is suitable for filtering the blood flow
by radially expanding and longitudinally shortening.
[0033] The predetermined shape of the filter includes a plurality
of interconnected members that are disposed about a longitudinal
axis and that form a bi-conical portion and optional symmetric
cylindrical portions in order to provide the free recovery shape.
The bi-conical portion can be described as two funnels or funnels
coupled at their respective tips or a portion of each funnel or
funnel proximal of a tip or central axis, which can include the
bottom aperture of two conical members being joined so that a
conduit of appropriate size extends therethrough. When referred to
as funnels, the filter includes two funnels coupled together at or
near their small openings.
[0034] In an embodiment, the filter of the present invention is a
vena cava filter. The vena cava filter can be implantable in the
inferior vena cava, and is utilized to filter peripheral venous
blood clots, a thrombus, and/or other appropriately sized
particulates. The filter can be permanently or removably implanted.
While the free recovery design allows for a more readily
extractable filter, the filter is also suitable for long-term or
permanent implantation. Accordingly, the filter can be configured
to be deployed at the aortic arch of the aorta providing cerebral
embolic protection. The filter can be positioned in the base of the
aortic arch, between the aortic valve and the brachiocephalic
artery. Any potential emboli are captured by the filter, thereby
preventing entry into the neurovasculature. However, the filter of
the present invention can be positioned at any suitable portion of
the vena cava, or even configured for deployment in a
non-vasculature lumen such as the urethra.
[0035] In one embodiment, multiple filters of the present invention
can be employed. For example, a first filter can be positioned in
the brachiocephalic artery and a second filter can be positioned in
the left common carotid artery of the aortic arch. Any potential
emboli are thereby captured by the filters so as to prevent entry
into the neurovasculature.
[0036] In a further embodiment, the filter of the present invention
may be utilized as anatomic junction or bridge. An anatomic
junction can be used in the repair of damaged or grafted vessels.
Also, the filter can be used similarly as a stent.
II. Lumen Filter
[0037] Generally, the filter of the present invention includes a
filter body disposed about a longitudinal axis. The filter can be
made of a shape memory alloy, which when in a delivery and/or
retrieval orientation has first and second portions that are in a
narrowed configuration, and when deployed and set having an
expanded configuration. The filtering portion, which is
substantially bi-conical, can be configured to be similarly
narrowed during delivery and/or retrieval, and expanded after being
deployed and set. This provides the free recovery shape. However,
the bi-conical portion can be configured to maintain substantially
a constant size during deployment and after being deployed and set.
The largest diameter portions of the filter have a diameter of
sufficient size to contact the inner walls of the vessel. As such,
the largest diameter portions of the filter can provide a force
against the inner wall of the vessel so as to hold the filter at
the site of deployment. Accordingly, increasing the length of the
large diameter end portions can increase the contact area with the
vessel and decrease the chance for the filter to move from the site
of deployment. The force of the first and second large diameter
portions act together to anchor and stabilize the filter at the
site of deployment within the vessel. The narrowed section, which
includes the bi-conical portion, is formed by strut elements or
braids (e.g., filter elements) that provide a conduit having a
progressively decreasing diameter from the large end to small end
of each funnel. The strut elements or braids can be provided in a
spaced apart arrangement of an appropriate distance to capture
particulates within the blood flow without substantially
interfering with the normal blood flow.
[0038] Generally, a filter of the present invention can include at
least a first set of interconnected strut elements (e.g., filter
elements) that cooperatively define the body of the filter.
Usually, each strut element can be defined by a cross-sectional
profile as having a width and a thickness, and including a first
end and a second end bounding a length. The stent element can be
substantially linear, arced, rounded, squared, combinations
thereof, or other configurations. The strut element can include a
bumper, crossbar, connector, inter-connector, intersection, elbow,
foot, ankle, toe, heel, medial segment, lateral segment,
combinations thereof, or the like which are well known in the
endoprosthetic arts. Generally, the strut element can be configured
to a corresponding element of a stent.
[0039] The present invention provides a filter having a free
recovery shape that allows for easy delivery and retrieval.
Accordingly, the figures illustrate embodiments of filters that
have the free recovery shapes.
[0040] FIG. 1A is a schematic representation of a filter 10 having
a central axis 76, which is shown in side a view, in accordance
with the present invention. The filter 10 has an hourglass-like
shape that is defined by the body 12, which includes a first body
portion 20, second body portion 32, first funnel body 44, second
funnel body 56, and median body 68. The filter 10 is arranged such
that the first body portion 20 is coupled to the first funnel body
44, which is coupled to the median body 68, which is coupled to the
second funnel body 56, which is coupled to the second body portion
32. The body 12 can include of a plurality of filter structural
elements 14 (e.g., strut element, braids, or the like) that
cooperate to provide structural integrity to the filter 10. The
body 12 and structural elements 14 can be shaped and/or otherwise
configured similarly to an endoprosthesis configured for deployment
into a body lumen, examples of which include lumen filters, stents,
and the like. The structural elements 14 include annular elements,
helical elements, crossbars, connectors, junctions, braids, and
other like features that are commonly employed in stent and/or
filter endoprostheses.
[0041] The hourglass shape of the body 12 at least partially
defines a first end 16 that includes a first opening 18 formed
therein. The first end 16 is disposed at a longitudinal end of the
body 12, and the first opening 18 can be substantially the same
dimensions as the first end 16. The segment of the body 12 that
defines the first end 16 is the first body portion 20. The first
body portion 20 can have various shapes and sizes; however, it is
depicted as being substantially cylindrical in FIG. 1A. The first
body portion 20 defines a first large conduit 22 that is fluidly
coupled with the first opening 18 such that an object can pass
through the first opening 18 and into the first large conduit 22,
or vice versa. The first large conduit 22 has a first large
diameter 24 that has a uniform or varying dimension. The first
large diameter 24 can be substantially uniform such that the first
body portion 20 has a substantially uniform cross-sectional
profile. The first body portion 20 and/or the first large conduit
22 has a first length 26 that extends from the first end 16 and/or
first opening 18 to the opposite end of the first body portion 20
and/or first large conduit 22.
[0042] Additionally, the opposite end of the hourglass shape of the
body 12 from the first end 16 at least partially defines a second
end 28 that includes a second opening 30 formed therein. The second
end 28 is disposed at a longitudinal end of the body 12, and the
second opening 30 can be substantially the same dimensions as the
second end 28. The segment of the body 12 that defines the second
end 28 is the second body portion 32. The second body portion 32
can have various shapes and sizes; however, it is depicted as being
substantially cylindrical in FIG. 1A, which is similar to the first
body portion 20. The second body portion 32 defines a second large
conduit 34 that is fluidly coupled with the second opening 30 such
that an object can pass through the second opening 30 and into the
second large conduit 34, or vice versa. The second large conduit 34
has a second large diameter 36 that has a uniform or varying
dimension. The second large diameter 36 can be substantially
uniform such that the second body portion 32 has a substantially
uniform cross-sectional profile. The second body portion 32 and/or
the second large conduit 34 has a second length 38 that extends
from the second end 28 and/or second opening 30 to the opposite end
of the second body portion 32 and/or second large conduit 34.
[0043] The first body portion 20 is fluidly coupled with a first
funnel body 44 such that the end of the first body portion 20
opposite of the first end 16 and/or first opening 18 is coupled to
the first funnel large end 40. As such, the first funnel large end
40 can be considered to be a junction with the first body portion
20. The first funnel body 44 also has a first funnel small end 42
that is opposite of the first funnel large end 40. As shown, the
first funnel large end 40 has a larger diameter and/or opening
compared to the first funnel small end 42. The first funnel body 44
defines a first funnel conduit 50 which is disposed therein. The
first funnel body 44 and/or first funnel conduit 50 includes a
first funnel diameter 46 that decreases from the first funnel large
end 40 to the first funnel small end 42 such that the
cross-sectional profile of the first funnel body 44 and/or first
funnel conduit 50 correspondingly decreases. The first funnel body
44 and/or the first funnel conduit 50 has a first funnel length 48
that extends from the first funnel large end 40 to the opposite
first funnel small end 42.
[0044] The second body portion 32 is fluidly coupled with a second
funnel body 56 such that the end of the second body portion 32
opposite of the second end 28 and/or second opening 30 is coupled
to the second funnel large end 52. As such, the second funnel large
end 52 can be considered to be a junction with the second body
portion 32. The second funnel body 56 also has a second funnel
small end 54 that is opposite of the second funnel large end 52. As
shown, the second funnel large end 52 has a larger diameter and/or
opening compared to the second funnel small end 54. The second
funnel body 56 defines a second funnel conduit 62 which is disposed
therein. The second funnel body 56 and/or second funnel conduit 62
includes a second funnel diameter 58 that decreases from the second
funnel large end 52 to the second funnel small end 54 such that the
cross-sectional profile of the second funnel body 56 and/or second
funnel conduit 62 correspondingly decreases. The second funnel body
56 and/or the second funnel conduit 62 has a second funnel length
60 that extends from the second funnel large end 52 to the opposite
second funnel small end 54.
[0045] The first funnel small end 42 of the first funnel body 44 is
coupled to the first median end 64 of the median body 68, and the
second funnel small end 54 of the second funnel body 56 is coupled
to the second median end 66 of the median body 68. This
configuration disposes the median body 68 between the first funnel
body 44 and the second funnel body 56. The median body 68 defines a
median conduit 74 having a median diameter 70 and a median length
72. The median diameter 70 can have a dimension that is
substantially the same from the first median end 64 to the second
median end 66, or the dimension can be varied, such as increasing,
decreasing, parabolic, and the like.
[0046] The filter 10 can be configured such that each corresponding
portion along the central axis 76 is similar or different. For
example, the first body portion 20 can have shapes and/or
dimensions that are the same or different from the shapes and/or
dimensions of the second body portion 32; the first funnel body 44
can have shapes and/or dimensions that are the same or different
from the shapes and/or dimensions of the second funnel body 56.
Also, the median body 68 can be configured such that the median
conduit 74 is extremely small so that blood clot particulates do
not pass therethrough. This allows the filter 10 to filter the
blood. Also, the first length 26 of the first body portion 20
and/or the second length 38 of the second body portion 32 can be
dimensioned to improve the static disposition of the filter 10
within a body lumen such that the filter 10 is substantially
immobile after deployment. This can impart an enlarged contact
surface area with the body lumen that allows the filter 10 to have
increased contact with the body lumen. Additionally, the first
funnel length 48 and/or second funnel length 60 can be dimensioned
to improve the filtering capability of the filter 10, wherein such
dimension changes can include sharper or more gradual slopes of the
conical shape. Moreover, the dimensions of the median body 68 can
be modulated so as to change the filtering characteristics of the
filter 10, where a smaller median conduit 74 can catch smaller
particles and a larger median conduit 74 can allow larger particles
to pass therethrough. Thus, the diameter, shape, and/or length of
the median conduit 74 can be tailored for a particular body lumen
and/or for the size of particulates to be captured and filtered
from the body fluid.
[0047] For example, the large diameters 24, 36 can be from about
0.001 mm to about 10 mm, from about 0.01 mm to about 5 mm, and/or
about 0.1 mm to about 1 mm. The lengths 26, 38 can be from about 0
mm to about 50 mm, about 0.001 to about 25 mm, and/or about 0.1 mm
to about 10 mm. The funnel diameters 46, 58 can be from about 0 mm
to about 10 mm, from about 0.001 mm to about 5 mm, and/or about
0.01 mm to about 1 mm. The funnel lengths 48, 60 can be from about
0.01 mm to about 50 mm, from about 0.1 mm to about 25 mm, and/or
about 0.5 mm to about 1 mm. The median diameter 70 can be from
about 0 mm to about 1 mm, from about 0.0001 mm to about 0.5 mm,
and/or about 0.001 mm to about 0.01 mm. The median length 72 can be
from about 0 mm to about 50 mm, from about 0.001 mm to about 25 mm,
and/or about 0.01 mm to about 10 mm. However, other sizes can be
employed and determined by routine studies of the vasculature or
other body lumen in which the filter will be placed.
[0048] FIG. 1B is a schematic representation of a cross-sectional
profile of the filter 10 taken at lines B show in FIG. 1A, which
mainly depicts the cross-sectional profile of the first body
portion 20, the first funnel body 44, and the median conduit 74. As
shown, the first body portion 20 has a first large diameter 24 that
is substantially similar to the size of the first funnel large end
40. The first funnel body 44 narrows the first funnel conduit 50
until reaching the small opening of the median conduit 74, which
has a small median diameter 70. The first funnel body 44 can
include a plurality of structural elements 14 that cooperate to
form filter apertures 15 (i.e., apertures) that are substantially
filter pores. The size and/or shapes of the filter apertures 15 can
be configured to be larger or smaller depending on the size of
particulates to be trapped and filtered from the body fluid. For
example the filter apertures 15 can have a dimension ranging from
about 0.00001 mm to about 0.1 mm, from about 0.0001 mm to about
0.01 mm, and/or from about 0.001 mm to about 0.001 mm.
[0049] FIGS. 1A-1B also show an example of an embodiment of the
configuration of the structural elements 14 and the corresponding
filter apertures 15. As shown, the filter apertures 15 proximate to
the first funnel large end 40 have substantially the same
dimensions as the filter apertures 15 that are proximate to the
first funnel small end 42. However, the filter apertures 15
proximate to the first funnel large end 40 can be larger than the
filter apertures 15 that are proximate to the first funnel small
end 42, or vice versa. However, the filter apertures 15 can have
any functional shape and/or size to function as a filter pore.
[0050] FIGS. 2A-2D illustrate schematic representations of
additional embodiments of an endoprosthesis in accordance with the
present invention. As illustrated, the endoprosthesis can be
configured into a filter for a body lumen.
[0051] FIG. 2A is a schematic representation of a side view of a
filter 200 in accordance with the present invention. The filter 200
has a shape and size that is defined by a filter body 202 having an
interconnected diamond pattern. As shown, the filter body 202 is in
the shape of a double funnel filter. That is, the filter body 202
is shaped substantially similarly to two funnels 204, 206 that are
coupled together at the median point 208 (e.g., median conduit).
The various features of the filter body 202 can be configured
similarly to the filter 10 of FIG. 1A. Accordingly, the first
funnel 204 can have an opening that allows a body fluid to flow
therethrough with the filter body 202 that decreases the
cross-sectional profile until reaching the median point 208. The
second funnel 206 is substantially similar to the first funnel 204;
however, it is oriented in the opposite direction. This allows the
filter 200 to be bidirectional and can be placed in the body lumen
with either end receiving the flow of body fluid, and the opposite
end being the exit for the body fluid.
[0052] FIG. 2B is a schematic representation of a side view of
another embodiment of a filter 220 in accordance with the present
invention. The filter 220 has a shape and size that is defined by a
filter body 222 having an interconnected square pattern. As shown,
the filter body 222 is in the shape of an extended double funnel
filter. That is, the filter body 222 is shaped substantially
similarly to two extended funnels 228, 230 that have tubes 224, 226
coupled to the wide portion of the funnels 228, 230 that are in
turn coupled together at the median point 232. The various features
of the filter body 220 can be configured similarly to the filter 10
of FIG. 1A. Accordingly, the first funnel 228 can have an opening
that allows a body fluid to flow therethrough with the filter body
222 having a first tube 224 that is coupled to a first funnel 228
that decreases the cross-sectional profile until reaching the
median point 232. The second tube 226 and second funnel 230 are
substantially similar to the first tube 224 and first funnel 228;
however, it is oriented in the opposite direction. This allows the
filter 220 to be bidirectional and can be placed in the body lumen
with either end receiving the flow of body fluid, and the opposite
end being the exit for the body fluid.
[0053] FIG. 2C is a schematic representation of a side view of
another embodiment of a filter 240 in accordance with the present
invention. The filter 240 has a shape and size that is defined by a
filter body 242 having an interconnected sinusoidal pattern. As
shown, the filter body 242 is in the shape of a double funnel
filter with a median conduit 248 disposed between a first funnel
filter 244 and a second funnel filter 246. That is, the filter body
242 is shaped substantially similarly to two funnels 244, 246 that
are coupled together with a median conduit 248. The various
features of the filter body 242 can be configured similarly to the
filter 10 of FIG. 1A. Accordingly, the first funnel filter 244 can
have an opening that allows a body fluid to flow therethrough with
the filter body 242 forming a funnel that decreases the
cross-sectional profile until reaching the median conduit 248,
which can have any shape and size so as to filter selected
particulate sizes from the body fluid. The second funnel filter 246
is substantially similar to the first funnel filter 244; however,
it is oriented in the opposite direction on the other side of the
median conduit 248. This allows the filter 240 to be bidirectional
and can be placed in the body lumen with either end receiving the
flow of body fluid, and the opposite end being the exit for the
body fluid.
[0054] FIG. 2D is a schematic representation of a side view of
another embodiment of a filter 260 in accordance with the present
invention. The filter 260 has a shape and size that is defined by a
filter body 262 having a checkerboard pattern. As shown, the filter
body 262 is in the shape of a tube that has a parabolically
narrowed central region. That is, the filter body 262 is shaped
substantially similarly to two tubes 264, 266 that are coupled
together at a parabolic median 268. The various features of the
filter body 262 can be configured similarly to the filter 10 of
FIG. 1A. Accordingly, the first tube 264 can have an opening that
allows a body fluid to flow therethrough with the filter body 262
having a parabolic median 268 that decreases the cross-sectional
profile until reaching a central point, and then the parabolic
median 268 increases in cross-sectional profile until reaching the
second tube 266. The second tube 266 is substantially similar to
the first tube 264; however, it is oriented in the opposite
direction. This allows the filter 260 to be bidirectional and can
be placed in the body lumen with either end receiving the flow of
body fluid, and the opposite end being the exit for the body
fluid.
[0055] FIGS. 3A-3D illustrate schematic representations of
embodiments of the substantially funnel-shaped filter portion of an
endoprosthesis in accordance with the present invention. As
illustrated, the funnel-shaped filter portion can have different
configurations in order to filter or selectively filter
particulates from a body fluid in a body lumen.
[0056] FIG. 3A illustrates an embodiment of a substantially
funnel-shaped filter 300 in accordance with the present invention.
As shown, the funnel-shaped filter 300 has a twisted funnel-shaped
body 301 that is shaped by structural elements 303 (i.e., filter
elements) that cooperate to form the funnel-shaped filter 300. The
funnel-shaped filter 300 is illustrated to show the features of the
filter 300 between a funnel large end 302 and the funnel small end
304. Structural elements 303 are formed by a plurality of radial
members 306 that spiral from the funnel small end 304 to the funnel
large end 302. As such, the radial members 306 cooperatively form
apertures 310 that increase in cross section from the funnel small
end 304 to the funnel large end 302. The smaller cross section of
the apertures 310 at the funnel small end 304 allows for the
filtering of smaller particles in the body fluid and the larger
cross section of the apertures 310 at the funnel large end 302
allows for similarly sized particles to pass therethrough. The
apertures 310 thereby trap larger particles near the funnel small
end 304 and allow smaller particles to pass through near the funnel
large end 302. Optionally, the funnel-shaped filter 300 can include
circular members 308 as shown by the dashed lines. The circular
members 308 can cooperate with the radial members 306 so as to form
much smaller apertures 310 that are configured similarly to pores
of standard filters. This allows for size-exclusion selection of
which particles will be filtered from the body fluid and which
particles will be allowed to pass through the filter 300 and
continue flowing in the body lumen.
[0057] FIG. 3B illustrates an embodiment of a substantially
funnel-shaped filter 320 in accordance with the present invention.
As shown, the funnel-shaped filter 320 has a target-shaped body 321
that is shaped by structural elements 323 that cooperate to form
the filter 320. The funnel-shaped filter 320 is illustrated to show
the features of the filter 320 between funnel large end 322 and
funnel small end 324. The structural elements 323 are formed by a
plurality of radial members 326 that extend substantially linearly
or straight without spiraling from the funnel small end 324 to the
funnel large end 322. As such, the radial members 326 cooperatively
form apertures 340 that increase in cross section from the funnel
small end 324 to the funnel large end 322. The smaller cross
section of the apertures 340 at the funnel small end 324 allows for
the filtering of smaller particles in the body fluid and the larger
cross section at the funnel large end 322 allows for similarly
sized particles to pass therethrough. The apertures 340 thereby
trap larger particles near the funnel small end 324 and allow
smaller particles to pass through near the funnel large end 322. As
shown, the funnel-shaped filter 320 includes circular members 328.
The circular members 328 cooperate with the radial members 326 so
as to form much smaller apertures 340 that are configured similarly
to pores of standard filters. This allows for size-exclusion
selection of which particles will be filtered from the body fluid
and which particles will be allowed to pass through the filter 300
and continue flowing in the body lumen.
[0058] FIG. 3C illustrates an embodiment of a substantially
funnel-shaped filter 350 in accordance with the present invention.
As shown, the funnel-shaped filter 350 has a checkerboard-shaped
body 351 that is shaped by structural elements 353 that cooperate
to form the filter 350. The funnel-shaped filter 350 is illustrated
to show the features of the filter 350 between the funnel large end
352 and the funnel small end 354. The structural elements 353 are
formed by a plurality of vertical members 356 and a plurality of
horizontal members 358 that cooperatively form apertures 360 that
are substantially the same size from the funnel small end 354 to
the funnel large end 352. The substantially similar apertures 360
at the funnel small end 354 and funnel large end 352 allows for the
filtering of the same sized particles in the body fluid so that
there is a size exclusion cutoff size. Accordingly, same sized
apertures 360 thereby trap the same size particles near the funnel
small end 354 and the funnel large end 352. This allows for
size-exclusion selection of which particles will be filtered from
the body fluid and which particles will be allowed to pass through
the filter 350 and continue flowing in the body lumen.
[0059] FIG. 3D illustrates an embodiment of a substantially
funnel-shaped filter 370 in accordance with the present invention.
As shown, the funnel-shaped filter 370 has a wheel spoke-shaped
body 371 that is shaped by structural elements 373 that cooperate
to form the filter 370. The funnel-shaped filter 370 is illustrated
to show the features of the filter 370 between the funnel large end
372 and the funnel small end 374. The structural elements 373 are
formed by a plurality of radial members 376 that extend
substantially linearly or straight without spiraling from the
funnel small end 374 to the funnel large end 372. As such, the
radial members 376 cooperatively form apertures 378 that increase
in cross section from the funnel small end 374 to the funnel large
end 372. The smaller cross section of the apertures 378 at the
funnel small end 374 allows for the filtering of smaller particles
in the body fluid and the larger cross section of the apertures 378
at the funnel large end 372 allows for similarly sized particles to
pass therethrough. The apertures 378 thereby trap larger particles
near the funnel small end 374 and allow smaller particles to pass
through near the funnel large end 372. This allows for
size-exclusion selection of which particles will be filtered from
the body fluid and which particles will be allowed to pass through
the filter 370 and continue flowing in the body lumen.
[0060] FIG. 3E illustrates an embodiment of a substantially
funnel-shaped filter 380 in accordance with the present invention.
As shown, the funnel-shaped filter 380 has a sectioned
spiral-shaped body 381 that is shaped by structural elements 383
that cooperate to form the filter 380. The funnel-shaped filter 380
is illustrated to show the features of the filter between the
funnel large end 382 and the funnel small end 384. The structural
elements 383 are formed by a single spiral member 386 that spirals
from the funnel small end 384 to the funnel large end 382. As such,
the spiral member 386 cooperatively forms an aperture 390 that
spirally extends and optionally increases in cross section from the
funnel small end 384 to the funnel large end 382. Optionally, the
funnel-shaped filter 380 can include radial members 388 as shown by
the dashed lines, wherein the radial members 388 can be
substantially similar with other radial members depicted in the
other embodiments. The radial members 388 can cooperate with the
spiral member 386 so as to form much smaller apertures 390 that are
configured similarly to pores of standard filters. This allows for
size-exclusion selection of which particles will be filtered from
the body fluid and which particles will be allowed to pass through
the filter 380 and continue flowing in the body lumen.
[0061] FIG. 3F illustrates an embodiment of a substantially
funnel-shaped filter 392 in accordance with the present invention.
As shown, the funnel-shaped filter 392 has a sectioned
spiral-shaped body 391 that is shaped by structural elements 393
that cooperate to form the filter 392. The funnel-shaped filter 392
is illustrated to show the features of the filter between the
funnel large end 394 and the funnel small end 396. The structural
elements 393 are formed by a single spiral member 398 that spirals
from the funnel small end 396 to the funnel large end 394. As such,
the spiral member 398 cooperatively forms an aperture 399 that
spirally extends and increases in cross section from the funnel
small end 396 to the funnel large end 394. This is because the
spiral member 398 is wound tighter at the funnel small end 396
compared to the funnel large end 394. However, the spiral member
398 can be wound tighter at the funnel large end 394 compared to
the funnel small end 396, or any other variation. This allows for
size-exclusion selection of which particles will be filtered from
the body fluid and which particles will be allowed to pass through
the filter 392 and continue flowing in the body lumen.
[0062] The size of the aperture(s), which function as pores, can be
dimensioned as needed for different applications. As such, the
aperture(s) can have smaller dimensions when the filter is designed
to filter out smaller particulates. Conversely, the aperture(s) can
have larger dimensions when smaller particulates are needing to be
filtered, but the aperture(s) still filter out particles larger
than the cutoff dimension. For example the aperture(s) can have a
dimension ranging from about 0.00001 mm to about 0.1 mm, from about
0.0001 mm to about 0.01 mm, and/or from about 0.001 mm to about
0.001 mm.
[0063] The filter can be inserted into the vessel through a
catheter or other similar type device in a compressed or flattened
form, where the filter expands in the vessel, such that the maximum
diameter of the larger end portions stabilize and secure the
position of the filter within the vessel. Such a compressed or
flattened delivery configuration can be achieved by pulling apart,
increasing the axial distance between, the filter ends. This
longitudinally stretches and radially compresses the filter. In
this manner, the maximum diameter sections of each of the larger
ends is drawn radially toward the central longitudinal axis. Upon
deployment and setting, the material properties of the filter
expand, drawing together, decreasing the axial distance between,
the filter ends. This longitudinally compresses and radially
expands the filter. In this manner, the maximum diameter end
sections of the filter are radially expanded toward the vessel
wall. It is contemplated that the filter can be inserted either
through a femoral or jugular approach as previously described.
However, the filter can be configured for placement in almost any
vessel or other body lumen.
[0064] To adequately hold the filter in place, the larger diameter
ends exert a radial force normal to the vena cava walls. The strut
elements, and thereby the larger diameter ends, are sufficiently
resilient to be compressed into the introducer catheter and to
regain their original shape after being released.
III. Deploying Filter
[0065] The filters of the present invention are configured for use
in a body lumen so as to filter the body fluid that flows through
the body lumen. This can filter particulates that are larger than a
selected size from the body fluid. As such, the present invention
includes a method of delivering a lumen filter into a body lumen of
a subject. Such a method includes: providing a lumen filter as
described herein; orienting the filter into a delivery orientation
by longitudinally elongating the filter body such that the larger
ends filter have a reduced dimension with a cross section that is
smaller than the body lumen; inserting the filter in the delivery
orientation into a delivery device, such as a deliver catheter that
can be configured substantially as a catheter for delivering a
stent; delivering the elongated filter body to a desired deployment
site within the body lumen of the subject; removing the filter from
the delivery device; and longitudinally shortening the filter body
such that the larger ends of the filter each have an enlarged
dimension that applies radial forces to an inner wall of the body
lumen.
[0066] FIG. 4A is a schematic representation illustrating a
delivery system 500 for delivering a filter 520a into a body lumen
540, such as a blood vessel like the vena cava. The filter 520a
includes a body 522 having a first large portion 524 coupled to a
first funnel 528 that is coupled to a second funnel 530 through an
intermediate portion 532, wherein the second funnel 530 is coupled
to a second large portion 526 so as to form the free recovery form.
The delivery system includes an endoprosthesis delivery catheter
502 configured for delivering a filter 520a that is retained by the
delivery catheter 502 in a delivery orientation (e.g.,
longitudinally elongated and radially compressed). The delivery
catheter 502 includes a delivery member 504 that defines a delivery
lumen 507 that is shaped and dimensioned to retain the filter 520a
in the delivery orientation. Accordingly, the delivery member 504
is substantially tubular and configured similarly as any delivery
catheter member. An internal surface 506 defined by the delivery
member 504 holds the filter 520a within the delivery catheter
502.
[0067] The delivery system 500 delivers the filter 520a with
delivery catheter 502 similarly to the method of delivering other
endoprostheses into a body lumen. As such, an insertion site (not
shown) is formed through the skin (not shown) that traverses into a
body lumen 540. A guidewire (not shown) is then inserted through
the insertion site, through the body lumen 540, to the delivery
site 544. A catheter (not shown) is then inserted into the body
lumen 540 to the delivery site 544 over the guidewire, and the
guidewire is optionally extracted. The delivery catheter 502 is
then inserted through the catheter (not shown) until reaching the
delivery site 544 and the catheter is withdrawn.
[0068] Optionally, the catheter is the delivery catheter 502, and
in this instance, the delivery catheter 502 is retained at the
delivery site 544 and the filter 520a is delivered to the delivery
site 544 through the delivery lumen 507 of the delivery catheter
502. A pusher 510 can be used to push the filter 520a within the
delivery lumen 507 of the delivery catheter 502 to the delivery
site 544.
[0069] Accordingly, the delivery system 500 is inserted through
percutaneous insertion site (not shown) that traverses from the
skin (not shown) into the body lumen 540 until reaching the
delivery site 544. The pusher 510 includes a distal end 512 that
pushes the filter 520a from the distal end 508 of the delivery
member 504. This is shown by the arrow pointing toward the distal
end 508 of the delivery member 504, which shows the relative
movement of the pusher 510 and thereby the filter 520a relative to
the delivery member 504 and body lumen 540. Alternatively, the
filter 520a can be disposed at the distal end 508 of the delivery
member 504, and the pusher 510 holds the filter 520a at the
delivery site 544 and the delivery member 504 is retracted over the
filter 520a and pusher 510, which is shown by the arrows. Thus, the
pusher 510 can push the filter from the delivery catheter 502 or
the delivery member 504 can be withdrawn over the filter 520a and
pusher 510 in order to deploy the filter 520a.
[0070] FIG. 4B illustrates a filter 520b in the deployed
configuration at the delivery site 544 within the body lumen 540.
As such, the filter 520b is longitudinally shortened and radially
expanded so as to contact the inner wall 542 of the body lumen
540.
[0071] In one embodiment, the present invention can include a
method of extracting a filter from the body lumen, which can
include: inserting a filter-extracting medical device into the body
lumen so as to come into contact with the filter; engaging the
filter-extracting medical device with the filter; longitudinally
elongating the filter body such that the larger ends of filter have
a reduced dimension with a cross section that is smaller than the
body lumen; and retrieving the elongated filter body from the
desired deployment site within the body lumen of the subject.
Optionally, the elongated filter can be received into the
filter-extracting medical device, which can be substantially
similar to a catheter.
[0072] In one embodiment, at least one of delivering or retrieving
the filter is performed with a catheter. Catheters configured for
delivering and/or retrieving endoprostheses from a body lumen can
be adapted for delivering and/or retrieving the filter of the
present invention.
IV. Filter Members
[0073] In one embodiment, the filter may be formed from a plurality
of strut members (i.e., filter members) that are interconnected
together similar to the interconnected structure of annular
element, such as a stent. The members can be formed of shape memory
materials (SMM), where multiple types of SMMs can be employed
together in a single filter.
[0074] In one embodiment, the strut member of the filter can be
formed from several wires braided together in order to produce a
braided wire with a desired outer diameter. Furthermore, a single
wire may be encapsulated in a multi-strand braid. The braided wires
can include a combination of SMMs, such that the combination of
number braided wires and elements permits a desired filter function
during deployment, filtering, and extraction.
[0075] In one embodiment, the body of the filter can be formed from
a plurality of braided members. That is, the braided members can be
substituted for the strut members, but be disposed in a braided
configuration. For example, elongate members similar in form and
function to the strut members can be substituted for the strut
members and be fashioned together so as to form a braided body.
Such elongate members themselves can be prepared from braided wires
or other braided members that have much smaller diameters compared
to the elongate members and/or strut members.
[0076] In one embodiment, the filter may be formed from a plurality
of strut members that are interconnected together similar to the
interconnected structure of an annular element, such as a stent.
The members can be formed of shape memory materials (SMM), where
multiple types of SMMs can be employed together in a single
filter.
[0077] In one embodiment, each strut member can include a plurality
of braided wires. The strut members can be substantially in the
shape of a ribbon. That is, the strut member can have a
substantially flat shape. The strut members can have a circular,
oval, square, triangular, rectangular, polygonal, or other shape.
In a method of manufacture, the braided wires forming the strut
elements are heat set in the braid. The braided wires can be
coated/jacketed with the biocompatible, biodegradable, and/or
bioneutral material.
[0078] In presently described embodiments, strut elements having a
rectangular, ribbon, or strip cross-sectional profile is employed,
though oval-shaped or round cross-sections can also be employed. In
the case of rectangular or oval cross-section, the strut element
can be oriented so that the long dimension is parallel with and
adjacent to the vena cava wall, with the narrow direction arranged
radially. The thickness of the strut element can be between 0.003
and 0.015 inch and/or between 0.005 and 0.009 inch. The width of
the strut element can be between 0.020 and 0.045 inch and/or
between 0.025 and 0.035 inch.
[0079] In one embodiment, the large diameter portions of the filter
can include an outer coating. The outer coating can be
biocompatible, optionally biodegradable, and cover at least a
portion of the large diameter portions that contact the body lumen.
The coating can leave the apertures between the strut elements or
braids open, or it can seal the apertures so as to provide a
sleeve. As such, the outer coating can be configured to prevent
adhesion of the tissue of the vessel to the filter. As such, the
filter can be removed without substantially tearing or damaging the
repaired vessel.
[0080] Furthermore, the filter, such as in the coating described
above, can include a drug or pharmaceutical agent. The drug can
include an anti-restenotic drug which decreases or prevents
encapsulation of the filter with tissue growth. Exemplary
anti-restenotic drugs include sirolimus, everolimus, taxol,
paclitaxel, and the like. Additionally, a drug can be provided
which promotes healing the vessel adjacent to the filter.
[0081] The filters of the present invention can be made of a
variety of materials, such as, but not limited to, those materials
which are well known in the art of endoprosthesis manufacturing.
This can include, but not limited to, a filter having a primary
material for the large portions and the tapered portions.
Alternatively, the tapered central portion can be made of a
different material compared to the large end portions. Generally,
the materials for the filter can be selected according to the
structural performance and biological characteristics that are
desired.
[0082] In one configuration, the large end portions and/or the
tapered central portions include a primary material. The large end
portions and/or the tapered central portions can include
resiliently flexible materials or rigid and inflexible materials.
For example, materials such as Ti3Al2.5V, Ti6A14V, 3-2.5Ti, 6-4Ti
and platinum may be particularly good choices for adhering to a
flexible material, such as, but not limited to, Nitinol and
providing good crack arresting properties. The use of resiliently
flexible materials can provide shock-absorbing characteristics to
the large end portions and/or the tapered central portions, which
can also be beneficial for absorbing stress and strains, which may
inhibit crack formation at high stress zones. For example, types of
materials that are used to make an endoprosthesis can be selected
so that the endoprosthesis is capable of being collapsed during
placement and expanded when deployed. Usually, the endoprosthesis
can be self-expanding, balloon-expandable, or can use some other
well-known configuration for deployment.
[0083] In one embodiment, a filter of the present invention can
include a material made from any of a variety of known suitable
materials, such as a shape memory material (SMM). For example, the
SMM can be shaped in a manner that allows for restriction to induce
a substantially tubular, linear orientation while within a delivery
shaft, but can automatically retain the memory shape of the filter
once extended from the delivery shaft. SMMs have a shape memory
effect in which they can be made to remember a particular shape.
Once a shape has been remembered, the SMM may be bent out of shape
or deformed and then returned to its original shape by unloading
from strain or heating. Typically, SMMs can be shape memory alloys
(SMA) including metal alloys, or shape memory plastics (SMP)
including polymers.
[0084] Usually, an SMA can have any non-characteristic initial
shape that can then be configured into a memory shape by heating
the SMA and conforming the SMA into the desired memory shape. After
the SMA is cooled, the desired memory shape can be retained. This
allows for the SMA to be bent, straightened, compacted, and placed
into various contortions by the application of requisite forces;
however, after the forces are released, the SMA can be capable of
returning to the memory shape. This can include the specific sizes
of the large end portions and/or the tapered central portions. The
main types of SMAs are as follows: copper-zinc-aluminium;
copper-aluminium-nickel; nickel-titanium (NiTi) alloys known as
nitinol; and cobalt-chromium-nickel alloys or
cobalt-chromium-nickel-molybdenum alloys known as elgiloy alloys.
The temperatures at which the SMA changes its crystallographic
structure are characteristic of the alloy, and can be tuned by
varying the elemental ratios.
[0085] For example, the primary material of a filter can be of a
NiTi alloy that forms superelastic nitinol. In the present case,
nitinol materials can be trained to remember a certain shape,
straightened in a shaft, catheter, or other tube, and then released
from the catheter or tube to return to its trained shape. This also
includes the hourglass shape or the shape of the large end portions
and/or the tapered central portions. Also, additional materials can
be added to the nitinol depending on the desired
characteristic.
[0086] A Shape Memory Plastic (SMP) can be fashioned into a filter
in accordance with the present invention. When an SMP encounters a
temperature above the lowest melting point of the individual
polymers, the blend makes a transition to a rubbery state. The
elastic modulus can change more than two orders of magnitude across
the transition temperature (Ttr). As such, an SMP can form into a
desired shape of a filter, braid, and/or strut element by heating
it above the Ttr, fixing the SMP into the new shape, and cooling
the material below Ttr. The SMP can then be arranged into a
temporary shape by force, and then resume the memory shape once the
force has been applied. Examples of SMPs include, but are not
limited to, biodegradable polymers, such as
oligo(.epsilon.-caprolactone)diol, oligo(.rho.-dioxanone)diol, and
non-biodegradable polymers such as, polynorborene, polyisoprene,
styrene butadiene, polyurethane-based materials, vinyl
acetate-polyester-based compounds, and others yet to be determined.
As such, any SMP can be used in accordance with the present
invention.
[0087] A filter having an SMM or suitable superelastic material and
other suitable layers can be compressed or restrained in its
delivery configuration (e.g., longitudinally elongated and radially
compressed) within a delivery device using a sheath or similar
restraint, and then deployed to its desired deployment
configuration (e.g., longitudinally compressed and radially
expanded) at a deployment site by removal of the restraint as is
known in the art. A filter made of a thermally-sensitive material
can be deployed by exposure of the filter to a sufficient
temperature to facilitate expansion as is known in the art.
[0088] In one embodiment, the filter, braid, and/or strut element
can include a variety of known suitable deformable alloy metal
materials, including stainless steel, silver, platinum, tantalum,
palladium, cobalt-chromium alloys or other known biocompatible
alloy metal materials.
[0089] In one embodiment, the filter can include a suitable
biocompatible polymer in addition to or in place of a suitable
metal. The polymeric filter can include biodegradable or
bioabsorbable materials, which can be either plastically deformable
or capable of being set in the deployed configuration. If
plastically deformable, the material can be selected to allow the
filter to be expanded in a similar manner using an expandable
member so as to have sufficient radial strength and scaffolding and
also to minimize recoil once expanded. If the polymer is to be set
in the deployment configuration, the expandable member can be
provided with a heat source or infusion ports to provide the
required catalyst to set or cure the polymer. Alternative known
delivery devices and techniques for self-expanding endoprostheses
likewise can be used. That is, the filter can be delivered and
deployed much like other endoprostheses, such as stents.
[0090] Examples of such biocompatible materials for the filter can
include a suitable hydrogel, hydrophilic polymer, biodegradable
polymers, bioabsorbable polymers and bioneutral polymers. Examples
of such polymers can include poly(alpha-hydroxy esters), polylactic
acids, polylactides, poly-L-lactide, poly-DL-lactide,
poly-L-lactide-co-DL-lactide, polyglycolic acids, polyglycolide,
polylactic-co-glycolic acids, polyglycolide-co-lactide,
polyglycolide-co-DL-lactide, polyglycolide-co-L-lactide,
polyanhydrides, polyanhydride-co-imides, polyesters,
polyorthoesters, polycaprolactones, polyesters, polyanydrides,
polyphosphazenes, polyester amides, polyester urethanes,
polycarbonates, polytrimethylene carbonates,
polyglycolide-co-trimethylene carbonates, poly(PBA-carbonates),
polyfumarates, polypropylene fumarate, poly(p-dioxanone),
polyhydroxyalkanoates, polyamino acids, poly-L-tyrosines,
poly(beta-hydroxybutyrate), polyhydroxybutyrate-hydroxyvaleric
acids, combinations thereof, or the like.
[0091] Furthermore, the filter can be formed from a ceramic
material. In one aspect, the ceramic can be a biocompatible ceramic
which optionally can be porous. Examples of suitable ceramic
materials include hydroxylapatite, mullite, crystalline oxides,
non-crystalline oxides, carbides, nitrides, silicides, borides,
phosphides, sulfides, tellurides, selenides, aluminum oxide,
silicon oxide, titanium oxide, zirconium oxide, alumina-zirconia,
silicon carbide, titanium carbide, titanium boride, aluminum
nitride, silicon nitride, ferrites, iron sulfide, and the like.
Optionally, the ceramic can be provided as sinterable particles
that are sintered into the shape of a filter, braid, and/or stent
element.
[0092] Moreover, the filter can include a radiopaque material to
increase visibility during placement. Optionally, the radiopaque
material can be a layer or coating any portion of the filter. The
radiopaque materials can be platinum, tungsten, silver, stainless
steel, gold, tantalum, bismuth, barium sulfate, or a similar
material.
[0093] It is further contemplated that the external surface and/or
internal surface of the filter, braid, and/or strut element (e.g.,
exterior and luminal surfaces) can be coated with another material
having a composition different from the primary filter material.
The use of a different material to coat the surfaces can be
beneficial for imparting additional properties to the filter, such
as providing radiopaque characteristics, drug-reservoirs, and
improved biocompatibility.
[0094] In one configuration, the external and/or internal surfaces
of a filter can be coated with a biocompatible polymeric material
as described herein. Such coatings can include hydrogels,
hydrophilic and/or hydrophobic compounds, and polypeptides,
proteins or amino acids or the like. Specific examples can include
polyethylene glycols, polyvinylpyrrolidone (PVP), polyvinylalcohol
(PVA), parylene, heparin, phosphorylcholine, polytetrafluorethylene
(PTFE), or the like.
[0095] The coatings can also be provided on the filter to
facilitate the loading or delivery of beneficial agents or drugs,
such as therapeutic agents, pharmaceuticals and radiation
therapies. As such, the endoprosthetic material and/or holes can be
filled and/or coated with a biodegradable material.
[0096] Accordingly, the coating material can contain a drug or
beneficial agent to improve the use of the filter. Such drugs or
beneficial agents can include antithrombotics, anticoagulants,
antiplatelet agents, thrombolytics, antiproliferatives,
anti-inflammatories, agents that inhibit hyperplasia, inhibitors of
smooth muscle proliferation, antibiotics, growth factor inhibitors,
or cell adhesion inhibitors, as well as antineoplastics,
antimitotics, antifibrins, antioxidants, agents that promote
endothelial cell recovery, antiallergic substances, radiopaque
agents, viral vectors having beneficial genes, genes, siRNA,
antisense compounds, oligionucleotides, cell permeation enhancers,
and combinations thereof.
[0097] In one configuration, different external surfaces of a
filter, such as a low stress zone less susceptible to flexing, can
be coated with functional layers of an imaging compound or
radiopaque material. The radiopaque material can be applied as a
layer at low stress zones of the filter. Also, the radiopaque
material can be encapsulated within a biocompatible or
biodegradable polymer and used as a coating. For example, the
suitable radiopaque material can be palladium, platinum, tungsten,
silver, stainless steel, gold, tantalum, bismuth, barium sulfate,
or a similar material. The radiopaque material can be applied as
layers on selected surfaces of the filter using any of a variety of
well-known techniques, including cladding, bonding, adhesion,
fusion, deposition or the like.
V. Method of Making Endoprostheses
[0098] Various different manufacturing techniques are well known
and may be used for fabrication of the filters, braids, and/or
strut elements of the present invention. Generally, processes for
preparing endoprostheses, such as stents or filters, can be used to
prepare the filters of the present invention. The filter is formed
such that the braids and/or strut elements cooperate so as to form
apertures, which function as the pores in a filter. For example,
the filter can be formed from a hollow tube using a known
technique, such as laser cutting, EDM, milling, chemical etching,
hydro-cutting, and the like. Also, the filter can be prepared to
include multiple layers or coatings deposited through a cladding
process such as vapor deposition, electroplating, spraying, or
similar processes. Once the generally tubular shape is formed, the
tube can be shaped into the substantially hourglass shape as shown
in the figures. Such shaping into the hourglass shape can be done
before or after the forming the apertures that serve the function
as a filter. Also, various other processes can be used such as
those described below and or others known to those skilled in the
art in light of the teaching contained herein.
[0099] In one embodiment, the filter can be fabricated from a sheet
of suitable material, where the sheet is rolled or bent about a
longitudinal axis into the desired tubular shape. Additionally,
either before or after being rolled into a tube, the material can
be shaped to include filter elements and pores by being shaped with
well-known techniques such as laser-cutting, milling, etching or
the like. If desired, the lateral edges of the structure can be
joined together, such as by welding or bonding, to form a closed
tubular structure, or the lateral edges can remain unattached to
form a coiled, rolled sheet or open tubular structure. Such
fabrication techniques are described in more detail below and known
to those skilled in the art.
A. Sintering
[0100] A method of making a filter can include sintering sinterable
particles to provide a sintered article having the shape of the
filter. The sintering can be conducted in molds that are in the
shape of a general tube or in the shape of an hourglass.
[0101] In one configuration, the sintered body can be obtained from
a molded green body prepared by molding a mixture of sinterable
particles with or without a binder into the shape of a filter or
body intermediate. Sintering a molded green body that has the shape
of a filter can provide a sintered body that can function as a
filter with no or minimal further processing. Alternatively, after
the green body has been formed in the mold and sintered into a
hardened filter, the process can include shaping the sintered body
with a stream of energy and/or matter in order to obtain a desired
shape. This can include laser-cutting the apertures and/or forming
the shape of the hourglass. Thus, sintering a green body in a mold
can result in a filter that is either ready for use, or requires
additional processing or finishing.
[0102] Additionally, the sintered body can be shaped into a filter
as described herein. Also, the filter can be further processed
after sintering and/or shaping such as by grinding, sanding, or the
like to provide enhanced surface characteristics.
B. Drawing Concentric Tubes
[0103] In one configuration, a multilayered filter in accordance
with the present invention can be prepared by a drawing process
that draws two or more distinct concentric tubes into a single tube
having two or more layers. Additionally, such a drawing process can
combine multiple concentric tubes into a single multilayered tube.
Alternatively, the different layers can function as the different
portions, such as the large diameter ends and the tapered center.
The drawing process can be configured to produce junctions
separating adjacent layers or bonds that bond adjacent layers. As
such, the sequentially-adjacent concentric tubes can be drawn
together and progressively reduced in a cross-sectional profile
until the desired size and residual clamping stress is
attained.
[0104] Accordingly, a metallurgical bond can be prepared with
elements of each sequentially-concentric tube diffusing together
and bonding so as to form a strong metallurgical bond. Such a
metallurgical bond can be achieved by applying significant pressure
and heat to the tubes. As such, a metallurgical bond can form a
diffusion layer at the interface between sequentially-adjacent
concentric tubes (i.e., layers). The characteristics of these
diffusion layers can be controlled by the proper heat treatment
cycle. In part, this is because the heat treatment, temperature,
and time of processing can control the rates of transfer of the
diffusing elements that produce the diffusion layers. Also, the
pressure at the interface between layers can be developed so as to
result in the residual radial clamping stress in the tube after
drawing.
[0105] In one example of this process, an outer tube of nitinol, a
middle tube of tantalum, and an inner tube of nitinol can be
arranged to form the composite structure. The multilayered material
can be produced to result in bonding between the layers so as to
achieve a residual clamping stress of at least about 50 p.s.i.
Accordingly, the annealing process can be performed within a
limited range of time and temperatures. For example, the lower
limit can be at least about 1550.degree. F. for at least six
minutes, and the upper limit can be less than about 1850.degree. F.
for less than 15 minutes.
[0106] In another configuration, a metallic interleaf layer can be
placed between separate tubes so as to bond the tubes together and
form a multilayered material. The multiple tubes separated by the
metallic interleaf layer can be drawn together and progressively
reduced until the desired cross-sectional profile and residual
clamping stress is attained, as described above. The drawn tubes
can be heat-treated to form a diffusion bond between the separate
layers. As such, the metallic interleaf layer can enhance the
diffusion rate or type of diffusing atoms that are transported
across a diffusion region between one layer and the interleaf
layer.
[0107] In one configuration, a multilayered sheet can be prepared
to have separate layers of different materials or the same
material. For example, the multilayered sheet can have a top layer
of nitinol, a middle layer of tantalum, and a bottom layer of
Nitinol. The sheet can be prepared by metallurgically bonding the
layers prior to a deep drawing process, which is well known in the
art. During the deep drawing process, the sheet can be placed over
a die and forced into the die, such as by a punch or the like. A
tube having a closed end and a defined wall thickness can be formed
in the die. This process can be repeated using a series of dies
that have progressively decreasing diameters until a multilayered
tube is formed having the desired diameter and wall thickness. For
certain material combinations, intermediate heat treatments can be
performed between the progressive drawing operations to form a
multilayered material that is resistant to delaminating. Once a
multilayered tube of desired thickness and dimensions has been
formed, the closed end and the curved edges can be cut off. Then,
the tube can be heat treated, as described above, until proper
inter-metallic bonds are formed between the layers.
C. Shaping
[0108] Accordingly, a filter material can be shaped by various
methods as described in more detail below. Such shaping techniques
can utilize streams of energy and/or streams of matter in order to
impart shapes into the filter material. The streams of energy
include photons, electromagnetic radiation, atomic, and sub-atomic
materials, as described above. On the other hand, the streams of
matter are considered to include materials larger than atomic scale
particles, and can be microscopic or macroscopic in size. In any
event, the shaping can be designed to direct a stream of energy or
a stream of matter at the filter material to form an endoprosthetic
element and/or holes therein.
[0109] In one configuration, a stream of energy can cut, shape,
and/or form a tube into a filter by generating heat at the site
where the stream intersects the material, as is well known in the
art. The thermal interaction can elevate the local temperature to a
point, which can cut, melt, shape, and/or vaporize portions of the
filter material from the rest of the material.
[0110] Accordingly, one configuration of the stream-cutting
apparatus can operate and shape the filter material by thermal
interactions. As such, any of the thermal processes described
herein can be used for thermal-cutting. For example, such thermal
interactions can arise from laser beam treatment, laser beam
machining, electron beam machining, electrical discharge machining,
ion beam machining, and plasma beam machining
[0111] In one configuration, by knowing the thermal properties of
the filter material, precise energy requirements can be calculated
so that the thermal beam provides the appropriate or minimum energy
for melting and/or vaporizing the material without significantly
melting undesirable portions of the material. For example, laser
beams are a common form of a stream of energy that can be used to
shape the filter material. Additionally, there are instances where
a laser is preferred over all other cutting techniques because of
the nature of the resulting filter as well as the characteristics
of the filter material.
[0112] In one configuration, a filter may be manufactured as
described herein using a femtosecond laser. A femtosecond laser may
be desirable in producing an endoprosthesis in accordance with the
multilayered composite structure of the present invention because
it produces a smaller heat influence zone (HIZ) or heat affected
zone (HAZ) compared to other lasers, or it can substantially
eliminate the HIZ or HAZ. In comparison, cutting a filter using
known methods can result in the tubular material being melted away,
and thereby forming the pattern in the tubular member. Such melting
can result in embrittlement of some materials due to oxygen uptake
into the HIZ.
[0113] In one configuration, electrical discharge machining is used
to shape filter material and/or form holes in the material as
desired. As such, electrical discharge machining can be capable of
cutting all types of conductive materials such as exotic metal
including titanium, hastaloy, kovar, hard tool steels, carbides,
and the like. In electrical discharge, the main interaction between
the stream of energy and the filter material is thermal, where heat
is generated by producing electrical discharges. This can lead to
the filter material being removed by melting and evaporation. Some
examples of electrical discharge machining include wire electron
discharge machining, CNC-controlled electrical discharge machining,
sinker electrical discharge machining, small hole discharge
machining, and the like.
[0114] In another configuration, a charged particle beam can be
used for shaping the filter material, wherein electron beams and
ion beams exemplify charged particle beams. A charged particle beam
is a group of electrically-charged particles that have
approximately the same kinetic energy and move in approximately the
same direction. Usually, the kinetic energies are much higher than
the thermal energies of similar particles at ordinary temperatures.
The high kinetic energy and the directionality of these charged
beams can be useful for cutting and shaping of the green bodies, as
described herein. Additionally, there are some instances where
electron beams or ion beams are preferred over other cutting
techniques.
[0115] In one configuration, a stream of chemical matter can be
used in order to shape or form holes in the filter material.
Chemical jet milling, for example, provides selective and
controlled material removal by jet and chemical action. As such,
the process is similar to water jet cutting, which is described in
more detail below. In any event, chemical-jet milling can be useful
for shaping various types of filter materials, which provides
intricate shaping capabilities.
[0116] In another configuration, electrochemical shaping can be
based on a controlled electrochemical dissolution process similar
to chemical jet milling a filter material. As such, the filter
material can be attached to an electrical source in order to allow
an electrical current to assist in the shaping.
[0117] In one configuration, hydro-cutting or water jet cutting can
be used to shape a filter material. Hydro-cutting is a water-jet
technology that uses the high force and high pressure of a stream
of water directed at the filter material in order to cut and shape
the material as desired. Hydro-cutting can be preferred over some
of the other stream-cutting technologies because it can be free of
heat, flame, and chemical reactions, and can provide a precise cold
shaping technique. Also, heated water with or without being doped
with reactive chemicals can also be used. Hydro-cutting is
particularly suitable for polymeric filters, but can be used for
metal materials when combined with abrasive particles, as described
below.
[0118] Additionally, hydro-cutting can be enhanced by the
introduction of particulate materials into the water feed line. As
such, some hydro-cutting techniques utilize garnet or other rigid
and strong materials in order to apply an abrasive cutting force
along with the force applied by the water itself. Also, the
hydro-cutting process in the present invention can be used with or
without inclusion of such abrasives.
[0119] Additionally, one of the benefits of hydro-cutting is the
ability to reutilize and recycle the spent water jet material. As
such, the filter material can be easily separated from the spent
water, thereby enabling the recycling and reuse of the water during
the hydro-cutting process.
[0120] In one configuration, sandblasting, which fits into the
regime of stream of matter cutting, can be used to shape a filter
material by projecting a high energy stream of sand particles at
the material. Sandblasting cuts materials in a manner similar to
hydro-cutting, especially when the water jet is doped with abrasive
particulates. Additionally, various other particulate streams other
than sand can be used in the stream-cutting techniques and
machinery.
D. Heat Setting
[0121] In general, a filter may be manufactured into the free
recovery shape through heat setting a superelastic material. If the
superelastic filter is required for a particular application, such
as inside of a superficial femoral artery, the large ends of the
filter may need to be as large as about 10 millimeters. Increasing
the diameter of the large ends of the filter and/or forming the
conical shape can be a gradual process with individual steps often
being expansions of only 1 millimeter. This allows the diameter of
the large end portions and the enlargement of the conical portions
to be gradually increased in size from the center point or the
center conduit of the filter. The number of steps that are repeated
can be up to and over 10 steps. Therefore, in the case of having a
superelastic nitinol hollow tube with an inner diameter of 1.3
millimeters, after about 8 steps, the diameter of the large end
portions may be around 10 millimeters, which is sufficient for most
intraluminal endoprosthestic applications within the human body.
The beginning diameter and the final diameter of the large end
portions may be smaller or larger depending upon the desired final
diameter that a filter needs to be for a particular
application.
[0122] When the filter is configured to have the final diameter
necessary (e.g., diameter of large end portions) for its particular
application, the filter may then be heated according to the method
of the present invention in order to provide the substantially
hourglass shape.
[0123] In one embodiment, a nickel titanium or nitinol filter can
be heat set. Heat setting is a process whereby the nitinol, or
other superelastic material, is heated to a temperature far above
its austenitic finish temperature in a desired shape, (e.g., large
end portions, tapered central portion, cones, hourglass and/or the
like), followed by water quenching. A filter may be deformed at the
heat set temperature into a new shape, such as being transformed
from a cylindrical shape to the hourglass shape. When the filter is
cooled so it is in the martensitic form, the filter may be deformed
into the delivery configuration. When the deformed, martensitic
filter is introduced into a body lumen, for example, the
temperature of the filter rises to (and above) the austenitic
finish temperature and the filter will then reform to the heat set
hourglass shape.
[0124] The temperature and the time of heating of the filter depend
upon the composition of the superelastic metal and the particular
application of filter. For example, a nitinol superelastic metal
alloy having a composition of 49% nickel and 51% titanium can have
different characteristics than a nitinol superelastic metal alloy
having a binary composition of nickel and titanium. Using a
standard superelastic nitinol (55.3-56.3 wt. % Ni), a temperature
of about 500 degrees Celsius for about 30 seconds or more to
configure the filter into the hourglass shape. A useable range of
temperatures for standard superelastic nitinol metals is from about
400 to about 600 degrees Celsius for greater than about 30 seconds.
Temperature ranges and times of heat treatment also change when
strengthening elements such as Cr are added.
E. Additional Processing
[0125] An additional step of passivation can be performed during
the manufacturing stage of the filter in order to form a
homogeneous oxide layer for corrosion-resistance. The passivation
process may be performed prior to installation of the markers in
accordance with the present invention or it may be performed after
installation of the radiopaque markers. Alternatively, multiple
passivation processes may be performed, once prior to application
of the markers, and again after insertion of the markers.
[0126] As originally shaped and/or fabricated, the filter can
correspond to its delivery configuration, to a deployed
configuration, or to a configuration therebetween. The filter can
be fabricated with a configuration at least slightly larger than
the delivery configuration. In this manner, the filter can be
crimped or otherwise compressed into its delivery configuration in
a corresponding delivery device.
[0127] In another configuration, the filter can be originally
fabricated from a tube having a diameter corresponding to the
deployed configuration. The filter can be designed to match the
target vessel in which the filter is to be deployed. For example, a
stent can be provided with an outer diameter in the deployed
configuration ranging from about 1 mm for neurological vessels to
about 25 mm for the aorta. Similarly, a stent can be provided with
a length ranging from about 5 mm to about 200 mm. Variations of
these dimensions will be understood in the art based upon the
intended application or indication for the filter.
[0128] The present invention may be embodied in other specific
forms without departing from its spirit or essential
characteristics. The described embodiments are to be considered in
all respects only as illustrative and not restrictive. The scope of
the invention is, therefore, indicated by the appended claims
rather than by the foregoing description. All changes which come
within the meaning and range of equivalency of the claims are to be
embraced within their scope.
* * * * *