U.S. patent application number 11/325249 was filed with the patent office on 2006-10-26 for methods for maintaining a filtering device within a lumen.
Invention is credited to Frank Arko, Jeff Elkins, Thomas Fogarty, Eric Johnson, Martin Seery.
Application Number | 20060241677 11/325249 |
Document ID | / |
Family ID | 36648108 |
Filed Date | 2006-10-26 |
United States Patent
Application |
20060241677 |
Kind Code |
A1 |
Johnson; Eric ; et
al. |
October 26, 2006 |
Methods for maintaining a filtering device within a lumen
Abstract
In one embodiment of the present invention there is provided a
method of filtering blood flow in a lumen by positioning an open
loop filter support structure within a lumen; maintaining a
position of the open loop filter support structure within the lumen
using radial force generated by the open loop filter support
structure; and filtering blood flow in the lumen using a filter
supported by the open loop filter support structure. In one aspect,
there is also applying radial force generated by the open loop
filter support structure along the axial dimension of the lumen. In
another embodiment of the present invention there is provided a
method of providing a filter across a lumen flow path by providing
a filter support structure having a first end, a crossover section,
and a second end; and fixing the position of the filter support
structure within the lumen by positioning the first end against a
first portion of the lumen and positioning the second end against a
second portion of the lumen; and using the filter support structure
to provide a filter across the lumen flow path. In one aspect, the
ends do not pierce the lumen surface.
Inventors: |
Johnson; Eric; (Woodside,
CA) ; Fogarty; Thomas; (Portola Valley, CA) ;
Arko; Frank; (Plano, TX) ; Elkins; Jeff;
(Woodside, CA) ; Seery; Martin; (San Rafael,
CA) |
Correspondence
Address: |
WILSON SONSINI GOODRICH & ROSATI
650 PAGE MILL ROAD
PALO ALTO
CA
94304-1050
US
|
Family ID: |
36648108 |
Appl. No.: |
11/325249 |
Filed: |
January 3, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60641327 |
Jan 3, 2005 |
|
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60668548 |
Apr 4, 2005 |
|
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60673980 |
Apr 21, 2005 |
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Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61F 2002/018 20130101;
A61M 2025/0037 20130101; A61F 2230/001 20130101; A61M 25/0021
20130101; A61F 2002/016 20130101; A61F 2230/0008 20130101; A61F
2/01 20130101; A61F 2250/0067 20130101; A61F 2/011 20200501; A61F
2230/0095 20130101; A61F 2230/0067 20130101; A61M 2025/004
20130101; A61B 17/221 20130101; A61M 25/007 20130101 |
Class at
Publication: |
606/200 |
International
Class: |
A61M 29/00 20060101
A61M029/00 |
Claims
1. A method of filtering blood flow in a lumen, comprising:
positioning an open loop filter support structure within a lumen;
maintaining a position of the open loop filter support structure
within the lumen using radial force generated by the open loop
filter support structure; and filtering blood flow in the lumen
using a filter supported by the open loop filter support
structure.
2. The method according to claim 1 wherein maintaining a position
of the open loop filter support structure within the lumen is
performed without piercing the surface of the lumen.
3. The method according to claim 1 wherein maintaining a position
of the open loop filter support structure within the lumen is
performed without perforating the lumen.
4. The method according to claim 1 further comprising: applying
radial force generated by the open loop filter support structure
along the axial dimension of the lumen.
5. The method according to claim 1 wherein maintaining a position
of the open loop filter support structure within the lumen using
radial force generated by the open loop filter support structure
positions the filter centrally within the lumen.
6. The method according to claim 1 further comprising: applying
radial force generated by the open loop filter support structure
around the axial dimension of the lumen.
7. The method according to claim 1 further comprising: maintaining
a nearly constant filtering capacity of the filter supported by the
open loop filter support structure as the size of the lumen
changes.
8. The method according to claim 1 further comprising: maintaining
the filtering capacity of the filter supported by the open loop
filter support structure over a physiological range of lumen
sizes.
9. The method according to claim 1 further comprising: maintaining
the filtering capacity of the filter supported by the open loop
filter support structure independent of the size of the lumen.
10. A method of providing a filter across a lumen flow path,
comprising: providing a filter support structure having a first
end, a crossover section, and a second end; and fixing the position
of the filter support structure within the lumen by positioning the
first end against a first portion of the lumen and positioning the
second end against a second portion of the lumen; and using the
filter support structure to provide a filter across the lumen flow
path.
11. The method of claim 10 wherein the ends do not pierce the lumen
surface.
12. The method of claim 10 wherein fixing the position of the
filter support structure comprises fixing the position of the
filter support structure within the lumen by positioning the first
end against a first portion of the lumen and positioning the second
end against a second portion of the lumen and positioning the
crossover section against a portion of the lumen between the first
and second portions of the lumen.
13. The method according to claim 12 wherein the portion of the
lumen between the first and second portions of the lumen is
opposite the first and second portions of the lumen.
14. The method according to claim 10 further comprising providing
another filter across the lumen flow path.
15. The method according to claim 10 further comprising: changing
the distance between the crossover section and the lumen wall
opposite the crossover section in response to changes in the lumen
diameter.
16. The method according to claim 10 further comprising: changing
the distance between the ends in response to changes in the lumen
diameter.
17. The method according to claim 10 further comprising: delivering
a pharmacological agent within the lumen using the filter support
structure.
18. The method according to claim 10 further comprising: delivering
a pharmacological agent within the lumen using the filter.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/641,327, filed Jan. 3, 2005, U.S. Provisional
Application No. 60/668,548, filed Apr. 4, 2005; U.S. Provisional
Application No. 60/673,980, filed Apr. 21, 2005 each of which is
incorporated herein by reference and, this application is related
to the following copending patent applications filed herewith:
application Ser. No. 11/325,251 entitled "Retrievable Endoluminal
Filter"; application Ser. No. 11/325,611 entitled "Coated
Endoluminal Filter"; application Ser. No. 11/325,230 entitled
"Endoluminal Filter"; application Ser. No. 11/325,622 entitled
"Endoluminal Filter"; application Ser. No. 11/325,229 entitled
"Spiral Shaped Filter"; application Ser. No. 11/325,273 entitled
"Filter Delivery Methods"; application Ser. No. 11/325,247 entitled
"Lumen Filtering Methods"; International Patent Application Serial
No. PCT/US06/00087 entitled "Retrievable Endoluminal Filter", each
of the above applications are incorporated herein by reference in
its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to devices and methods for
providing filtration of debris within a body lumen. More
particularly, the invention provides a retrievable filter placed
percutaneously in the vasculature of a patient to prevent passage
of emboli. Additionally, embodiments of the invention provide a
filter that can be atraumatically positioned and subsequently
removed percutaneously from a blood vessel using either end of the
filter.
[0004] 2. Background of the Invention
[0005] Embolic protection is utilized throughout the vasculature to
prevent the potentially fatal passage of embolic material in the
bloodstream to smaller vessels where it can obstruct blood flow.
The dislodgement of embolic material is often associated with
procedures which open blood vessels to restore natural blood flow
such as stenting, angioplasty, arthrectomy, endarterectomy or
thrombectomy. Used as an adjunct to these procedures, embolic
protection devices trap debris and provide a means for removal for
the body.
[0006] One widely used embolic protection application is the
placement of filtration means in the vena cava. Vena cava filters
(VCF) prevent the passage of thrombus from the deep veins of the
legs into the blood stream and ultimately to the lungs. This
condition is known as deep vein thrombosis (DVT), which can cause a
potentially fatal condition known as pulmonary embolism (PE).
[0007] The first surgical treatment for PE, performed by John
Hunter in 1874, was femoral vein ligation. The next major
advancement, introduced in the 1950's, was the practice of
compartmentalizing of the vena cava using clips, suture or staples.
While effective at preventing PE, these methods were associated
with significant mortality and morbidity (see, e.g., Kinney T B,
Update on inferior vena cava filters, JVIR 2003; 14:425-440,
incorporated herein by reference).
[0008] A major improvement in PE treatment, in which venous blood
flow was maintained, was presented by DeWesse in 1955. This method
was called the "harp-string" filter, as represented in FIG. 1A and
FIG. 1B, in which strands of silk suture 12 were sewn across the
vena cava 11 in a tangential plane below the renal veins 13 to trap
thrombus. Reported clinical results demonstrated the effectiveness
of this method in preventing PE and maintaining caval patency.
(see, e.g., DeWeese M S, A vena cava filter for the prevention of
pulmonary embolism, Arch of Surg 1963; 86:852-868, incorporated
herein by reference). Operative mortality associated with all of
these surgical treatments remained high and therefore limited their
applicability.
[0009] The current generation of inferior vena cava (IVC) filters
began in 1967 with the introduction of the Mobin-Uddin umbrella 21
(FIG. 1C) which is described in further detail in U.S. Pat. No.
3,540,431. The Greenfield filter (FIG. 1D) was introduced in 1973
and is described in further detail in U.S. Pat. No. 3,952,747.
These conical-shaped devices were placed endoluminaly in the IVC
and utilized hooks or barbs 20, 30 to pierce the IVC wall and fix
the position of the device. A variety of conical-shaped,
percutaneously placed vena cava filters, based upon this concept
are now available. For example, the TULIP with a filter structure
41 (FIG. 1E) further described in U.S. Pat. No. 5,133,733; the
RECOVERY with a filter structure 51 (FIG. 1F) further described in
U.S. Pat. No. 6,258,026; and the TRAPESE with a filter structure 61
(FIG. 1G) further described in U.S. Pat. No. 6,443,972.
[0010] The next advancement in filters added the element of
recoverability. Retrievable filters were designed to allow removal
from the patient subsequent to initial placement. Retrievable
filters are generally effective at preventing PE yet they have a
number of shortcomings, such as, for example: failure of the device
to deploy into the vessel properly, migration, perforation of the
vessel wall, support structure fracture, retrievability actually
limited to specific circumstances, and formation of thrombosis on
or about the device.
[0011] Problems associated with retrievable, conical-shaped
devices, such as those illustrated in FIG. 1D, FIG. 1E and FIG. 1F,
have been reported in the medical literature. These reported
problems include tilting which makes it difficult to recapture the
device and compromises filtration capacity. Hooks 30, 40, 50, 60
used to secure these devices have been reported to perforate the
vessel wall, cause delivery complications, and fracture. A
partially retrievable system is described in detail in pending U.S.
Pat. No. 2004/0186512 (FIG. 1H). In this system, the filter portion
71 can be removed from the support structure 70, but the support
structure remains in-vivo. All of these described devices share the
common limitation that they can be retrieved from only one end.
Each of the above referenced articles, patents and patent
application are incorporated herein in its entirety.
[0012] In view of the many shortcomings and challenges that remain
in the field of endoluminal filtering, there remains a need for
improved retrievable, endoluminal filters.
SUMMARY OF THE INVENTION
[0013] In one embodiment of the present invention there is provided
a method of filtering blood flow in a lumen by positioning an open
loop filter support structure within a lumen; maintaining a
position of the open loop filter support structure within the lumen
using radial force generated by the open loop filter support
structure; and filtering blood flow in the lumen using a filter
supported by the open loop filter support structure. In one aspect,
In one embodiment of the present invention there is provided a
maintaining a position of the open loop filter support structure
within the lumen is performed without piercing the surface of the
lumen. In one aspect, maintaining a position of the open loop
filter support structure within the lumen is performed without
perforating the lumen.
[0014] In one aspect, there is also applying radial force generated
by the open loop filter support structure along the axial dimension
of the lumen. In one aspect, maintaining a position of the open
loop filter support structure within the lumen using radial force
generated by the open loop filter support structure positions the
filter centrally within the lumen. In one aspect, there is also
applying radial force generated by the open loop filter support
structure around the axial dimension of the lumen. In one aspect,
there is also maintaining a nearly constant filtering capacity of
the filter supported by the open loop filter support structure as
the size of the lumen changes. In one aspect, there is also
maintaining the filtering capacity of the filter supported by the
open loop filter support structure over a physiological range of
lumen sizes. In one aspect, there is also maintaining the filtering
capacity of the filter supported by the open loop filter support
structure independent of the size of the lumen.
[0015] In another embodiment of the present invention there is
provided a method of providing a filter across a lumen flow path by
providing a filter support structure having a first end, a
crossover section, and a second end; and fixing the position of the
filter support structure within the lumen by positioning the first
end against a first portion of the lumen and positioning the second
end against a second portion of the lumen; and using the filter
support structure to provide a filter across the lumen flow path.
In one aspect, the ends do not pierce the lumen surface.
[0016] In one aspect, fixing the position of the filter support
structure comprises fixing the position of the filter support
structure within the lumen by positioning the first end against a
first portion of the lumen and positioning the second end against a
second portion of the lumen and positioning the crossover section
against a portion of the lumen between the first and second
portions of the lumen. In one aspect, the portion of the lumen
between the first and second portions of the lumen is opposite the
first and second portions of the lumen. In one aspect, there is
also provided another filter across the lumen flow path. In one
aspect, there is also a changing the distance between the crossover
section and the lumen wall opposite the crossover section in
response to changes in the lumen diameter. In one aspect, there is
also a changing the distance between the ends in response to
changes in the lumen diameter. In one aspect, there is also
delivering a pharmacological agent within the lumen using the
filter support structure. In one aspect, there is delivering a
pharmacological agent within the lumen using the filter.
BRIEF DESCRIPTION OF THE FIGURES
[0017] A better understanding of the features and advantages of
embodiments of the present invention will be appreciated through
reference to the following detailed description that sets forth
illustrative embodiments and the accompanying drawings of
which:
[0018] FIGS. 1A-1H illustrate various prior art filters;
[0019] FIGS. 2A-2C illustrate the response of a filtering device to
changes in lumen size;
[0020] FIGS. 3-5 illustrate the interaction of a structural member
with a lumen wall;
[0021] FIGS. 6A-8D illustrate various aspects of the structural
members in a filtering device;
[0022] FIGS. 9A and 9B illustrate various aspects of a generally
planer support frame;
[0023] FIGS. 10A and 10B illustrate various aspects of a non-planer
support frame;
[0024] FIGS. 11-13C illustrate various aspects of and
configurations for material capture structures;
[0025] FIGS. 14-14C illustrate various aspects of a filtering
device having three support frames;
[0026] FIG. 15 illustrates planes of symmetry for filtering
devices;
[0027] FIGS. 16A and 16B illustrate the response of a filtering
device when contacted by debris flowing in a lumen;
[0028] FIGS. 17-19 illustrate alternative filtering device aspects
having different sized support frames and structural member
lengths;
[0029] FIGS. 20-24 illustrate various alternative filtering device
ends and structural member joining techniques;
[0030] FIGS. 25-27C illustrate various alternative retrieval
features;
[0031] FIGS. 28A-28C illustrate various techniques of joining or
forming retrieval features;
[0032] FIG. 29 illustrates a filtering device with a retrieval
feature positioned within a lumen.
[0033] FIGS. 30-53D illustrate several alternatives techniques for
joining material capture structures to support frames and forming
filtering structures;
[0034] FIGS. 54A-65F illustrate several alternative filtering
structures;
[0035] FIGS. 66 and 67 illustrate various filtering device
configurations;
[0036] FIGS. 68A-74D illustrate various techniques related to the
delivery, recovery and repositioning of filtering devices;
[0037] FIGS. 75A-78F illustrate several exemplary methods of using
a filtering device;
[0038] FIGS. 79-82 illustrate several alternative filtering device
configurations adapted for the delivery of pharmacological agents;
and
[0039] FIGS. 83A-87 illustrate several filtering device
prototypes.
DETAILED DESCRIPTION
[0040] There remains a clinical need for improved endoluminal
filter devices and methods. Improved endoluminal filter devices
provide effective filtration over a range of lumen sizes and are
easy to deploy into and retrieve from a lumen. In addition,
improved endoluminal filter devices minimize thrombosis formation
or tissue ingrowth on the device and are resistant to migration
along the lumen. Improved endoluminal filter devices also minimize
device fatigue by eliminating barbs, hooks or other sharp curve
design features that can produce stress points that lead to
fatigue. Embodiments of the filter devices of the present invention
provide many and in some cases all of the features of improved
endoluminal filters and have a number of uses such but are not
limited to: embolic protection, thrombectomy, vessel occlusion, and
tethered or untethered distal protection.
[0041] Several embodiments of the present invention provide
improved filtration devices that are durable, provide effective and
nearly constant filter capacity over a range of lumen sizes and are
easily delivered and removed from a lumen via either end of the
device. Additionally, embodiments of the present invention can be
delivered into and retrieved from a lumen using minimally invasive
surgical techniques. One aspect of an embodiment of the present
invention is the construction of support structure elements using a
shape memory material. The shape memory material may have a
pre-shaped form that ensures the support elements are uniformly
collapsible and, when deployed, provides a pre-defined range of
controllable force against the lumen wall without use of hooks or
barbs.
[0042] The elongate support structure elements are configured to
collapse and expand with natural vessel movements while maintaining
constant apposition with the vessel wall. One result is that the
support structure shape and size track to vessel movements. As a
result, the filter density and capacity of embodiments of the
present invention remain relatively independent of changes in
vessel size. Moreover, the self centering aspect of the support
structure ensures the filtration device provides uniform filtration
across the vessel diameter. As such, embodiments of the present
invention provide generally constant filtration capacity of the
device is maintained across the entire vessel lumen and during
vessel contractions and expansions.
[0043] Uniform filter capacity is a significant improvement over
conventional devices. Conventional devices typically have a filter
capacity that varies radially across a lumen. The radial variation
in filter capacity usually results from the fact that conventional
filtration elements have a generally wider spacing at the periphery
of the lumen and closer spacing along the central lumen axis. The
result is that larger emboli can escape along the lumen periphery.
During vessel expansions and contractions, the radial variations in
filter capacity are exacerbated in conventional devices.
[0044] Another advantage of some embodiments of the present
invention is that when released from a constrained state (i.e.,
within a delivery sheath), the device assumes a predetermined form
with elongate support members that extend along and self center the
device in the vessel. These elongate support members exert
atruamatic radial force against the vessel wall to prevent or
minimize device migration. Utilizing radial force generated by the
elongate support members obviates the need for hooks or barbs to
secure the device within the vessel. As a result, embodiments of
the present invention produce little or no damage to the vessel
wall and lining while producing little or no systemic response from
the body. Additionally, when device retrieval is initiated, the
uniformly collapsible form of the elongate support members causes
the elongate support members to pull away from the vessel wall as
the device is being re-sheathed. The movement of the elongate
members away from the vessel wall facilitates the atraumatic
removal of the device from the vessel wall.
[0045] Additional embodiments of the present invention may include
a retrieval on one or both ends of the device. The use of retrieval
features on both ends of the device allows deployment,
repositioning and removal of the device to be accomplished from
either end of the device. As a result, the use of retrieval
features on both ends of the device enables both antegrade or
retrograde approaches to be used with a single device. The
retrieval feature may be integral to another structural member or a
separate component. In some embodiments, the retrieval feature is
collapsible and may have a curved shape or a generally sinusoidal
shape. Additional aspects of retrieval features are described
below.
[0046] General Principals and Construction
[0047] FIG. 2A illustrates an embodiment of a filtering device 100
of the present invention positioned within a lumen 10. The lumen 10
is cut away to show the position of filter 100 deployed into within
a lumen and in contact with the lumen wall. The filter 100 includes
a first elongate member 105 and a second elongate member 110. The
elongate members are joined to form ends 102, 104. The elongate
members cross but are not joined to one another at crossover 106.
In one embodiment, the elongate members have first and second
sections. First sections extend between the end 102 and the
crossover 106 and the second sections extend from the crossover 106
to the second end 104. While some embodiments contact the lumen in
different ways, the illustrated embodiment has the ends 102, 104
against one side of the lumen interior wall while the crossover 106
contacts the other side of the lumen interior wall with the
elongate bodies in constant or nearly constant apposition along the
lumen interior wall between the ends 102, 104.
[0048] Material (i.e., thrombus, plaque and the like) flowing
through the lumen 10 of a size larger than the filtering size of
the material capture structure 115 is captured between or cut down
by the filaments 118. In the illustrated embodiment of FIG. 2A, the
material capture structure 115 is supported by a rounded frame
formed by the elongate members 105, 110 formed between the end 102
and the crossover 106. Another rounded frame formed between the
crossover 106 and the second end 104 and could also be used to
support a material capture structure of the same or different
construction and filter capacity of the a material capture
structure 115. As such, a material removal structure supported by
one rounded frame may be configured to remove material of a first
size and the material removal structure supported a the other
rounded frame may be configured to remove material of a second
size. In one embodiment, the material removal structure in the
upstream rounded frame removes larger size debris than material
removal structure in the downstream rounded frame. Also illustrated
in FIGS. 2A-2C is how the filter cells 119 that make up the
material capture structure is 115 maintain their size and shape
relatively independent of movement of the first and second
structural members 105, 110 over a physiological range of vessel
diameters.
[0049] FIGS. 2B and 2C illustrate how the elongate support
structure elements of embodiments of the present invention are
configured to collapse and expand with natural vessel movements
while maintaining constant apposition with the vessel wall. FIGS.
2A, 2B and 2C also illustrate how devices according to embodiments
of the present invention are both radially and axially elastic. In
response to vessel size changes, ends 102, 104 move out as the
vessel size decreases (FIG. 2B) and then move in as the vessel size
increases (FIG. 2C). In addition, the device height "h" (measured
from the lumen wall in contact with ends 102, 104 to crossover)
also changes. Device height "h" changes in direct relation to
changes in vessel diameter (i.e., vessel diameter increases will
increase device height "h"). As such, device height ("h") in FIG.
2C is greater than device height ("h") in FIG. 2A which is in turn
greater than the device height ("h") in FIG. 2B.
[0050] FIGS. 2A, 2B and 2C also illustrate how a single sized
device can be used to accommodate three different lumen diameters.
FIG. 2C illustrates a large lumen, FIG. 2A a medium sized lumen and
FIG. 2B a small sized lumen. As these figures make clear, one
device can adapt to cover a range of vessel sizes. It is believed
that only 3 device sizes are needed to cover the range of human
vena cava interior diameters that range from approximately 12-30 mm
with an average interior diameter of 20 mm. Also illustrated is the
static or nearly static filter capacity of the material capture
structure 115. In each different vessel size, the material capture
structure 115, the filaments 118 and filter cell 119 maintain the
same or nearly the same shape and orientation within the support
frame formed by the elongate bodies. These figures also illustrate
the dynamic shape changing aspect of the device that may also be
used to accommodate and conform to vessel irregularities,
tortuosity, flares and tapers and while remaining in apposition to
the wall. Because each elongate body may move with a high degree of
independence with respect to the other, the loops or support frames
formed by the elongate bodies can also independently match the
shape/diameter of the lumen section in which it is placed.
[0051] FIGS. 3, 3A and 3B illustrate the device 100 deployed into
the lumen 10. As illustrated in FIG. 3, the device 100 is oriented
in the lumen with the ends 102, 104 along one side of the interior
vessel wall with the crossover 106 on the opposite side. FIG. 3
illustrates an embodiment of a device of the present invention that
is shaped to fit within the lumen 10 without distending the lumen.
In FIG. 3A the elongate bodies 105, 110 are in contact but are not
joined at crossover 106. In FIG. 3B the elongate bodies 105, 110
cross one another at crossover 106 but are separated (i.e., by a
gap "g").
[0052] FIGS. 4 and 5 illustrate how aspects of the device design
can be modified to increase the radial force applied against the
interior wall of lumen 10. Devices having increased fixation force
may be useful for some applications, such as vessel occlusion or
for distal protection when a large amount of debris is expected. If
a device is not intended to be retrieved (i.e., permanently
installed into a lumen) then high radial force design devices may
be used to ensure the device remains in place and distention may be
used to trigger a systemic response (i.e., a tissue growth
response) in the lumen to ensure device ingrowth and incorporation
with the lumen interior wall.
[0053] Filter device embodiments of the present invention having
low or atraumatic radial force are particularly useful in
retrievable devices. As used herein, atraumatic radial force refer
to radial forces produced by a filtering device embodiment that
meets one or more of the following: radial forces high enough to
hold the device in place with little or no migration and without
damaging or overly distending the lumen interior wall; radial
forces high enough to hold the device in place but while triggering
little or no systemic response for the vessel wall; or forces
generated by device operation that trigger reduced systemic
response or a systemic response below that of a conventional
filter.
[0054] In contrast to the device sized in FIG. 3 to minimize vessel
distention, FIG. 4 illustrates a device 100 configured to exert
greater radial force to a degree to cause lumen wall to distend.
FIGS. 4 and 5 illustrate lumen wall distention by the end 102
(distention 10b), by the crossover 106 (distention 10a), and by the
end 104 (distention 10c). Although not shown in these figures, the
elongate bodies would likely distend the lumen along their length
as well.
[0055] The radial force of a device may be increased using a number
of design factors. Radial force may be increased by increasing the
rigidity of the elongate body by, for example, using an elongate
body with a larger diameter. Radial force may also be increased
when forming the shapes of the elongate bodies (i.e., during the
heat treat/set processes for Nitinol devices and the like), as well
as in the material compostion and configuration.
[0056] Additional details of an embodiment of the support members
105, 110 may be appreciated with reference to FIGS. 6A, 6B and 6C.
FIGS. 6A, 6B illustrate the support members separately and then
assembled together (FIG. 6C) about device axis 121. In general, the
device axis 121 is the same as the axis along the central of a
lumen into which the device is deployed. For purposes of
illustration, the support members 105, 110 will be described with
reference to a sectioned lumen shown in phantom having a generally
cylindrical shape. The support members may also be thought of as
deployed within and/or extending along the surface of an imaginary
cylinder.
[0057] In the illustrative embodiments of FIGS. 6A, 6B and 6C, the
support members 105, 110 are shown in an expanded, pre-defined
shape. In one embodiment, the support members are formed from MRI
compatible materials. The support members contain no sharp bends or
angles to produce stress risers that may lead to fatigue issues,
vessel erosion, and facilitate device collapse. In some
embodiments, each elongate member is conventionally formed by
constraining a shape memory material such as a shape memory metal
alloy or shape memory polymer on a cylindrical shaping mandrel that
contains pins to constrain the material into the desired shape.
Thereafter, the material can be subjected to a suitable
conventional heat treatment process to set the shape. One or more
planes of symmetry (i.e., FIG. 15) may be provided, for example, by
forming both elongate members on a single mandrel and at the same
time. Other conventional processing techniques may also be used to
produce symmetrical filtering device embodiments. Additionally,
retrieval features described herein (if present) may be directly
formed on the wire ends during support member processing. In
addition, multiple devices, in a series on a long mandrel, can be
made using these methods.
[0058] Examples of suitable shape memory alloy materials include,
for example, copper-zinc-aluminium, copper-aluminum-nickel, and
nickel-titanium (NiTi or Nitinol) alloys. Nitinol support
structures have been used to construct a number of working
prototypes of filter devices of the present invention as well as
for use in ongoing animal studies (see experimental results
discussion below). Shape memory polymers may also be used to form
components of the filter device embodiments of the present
invention. In general, one component, oligo(e-caprolactone)
dimethacrylate, furnishes the crystallizable "switching" segment
that determines both the temporary and permanent shape of the
polymer. By varying the amount of the comonomer, n-butyl acrylate,
in the polymer network, the cross-link density can be adjusted. In
this way, the mechanical strength and transition temperature of the
polymers can be tailored over a wide range. Additional details of
shape memory polymers are described in U.S. Pat. No. 6,388,043
which is incorporated herein by reference in its entirety. In
addition, shape memory polymers could be designed to degrade.
Biodegradable shape memory polymers are described in U.S. Pat. No.
6,160,084 which is incorporated herein by reference in its
entirety.
[0059] It is believed that biodegradable polymers may also be
suited to form components of the filter device embodiments of the
present invention. For example, polylactide (PLA), a biodegradable
polymer, has been used in a number of medical device applications
including, for example, tissue screws, tacks, and suture anchors,
as well as systems for meniscus and cartilage repair. A range of
synthetic biodegradable polymers are available, including, for
example, polylactide (PLA), polyglycolide (PGA),
poly(lactide-co-glycolide) (PLGA), poly(e-caprolactone),
polydioxanone, polyanhydride, trimethylene carbonate,
poly(.beta.-hydroxybutyrate), poly(g-ethyl glutamate), poly(DTH
iminocarbonate), poly(bisphenol A iminocarbonate), poly(ortho
ester), polycyanoacrylate, and polyphosphazene. Additionally, a
number of biodegradable polymers derived from natural sources are
available such as modified polysaccharides (cellulose, chitin,
dextran) or modified proteins (fibrin, casein). The most widely
compounds in commercial applications include PGA and PLA, followed
by PLGA, poly(e-caprolactone), polydioxanone, trimethylene
carbonate, and polyanhydride.
[0060] While described as forming the support structures, it is to
be appreciated that other portions of the filter device may also be
formed from shape memory alloys, shape memory polymers or
biodegradable polymers. Other filter device components that may
also be formed from shape memory alloys, shape memory polymers or
biodegradable polymers include, for example, all or a portion of a
retrieval feature, a material capture structure or an attachment
between a material capture structure and a support structure.
[0061] FIG. 6A illustrates the first support member 105 extending
from an end 102 to an end 104 along in a clockwise manner about the
lumen interior wall (sectioned phantom lines) and the device axis
121. The support member 105 extends from the end 102 in section 1
at the 6 o'clock position, up to the 9 o'clock position in section
2, the 12 o'clock position in section 3, the 3 o'clock position in
section 4 to the end 104 at the 6 o'clock position in section 5.
The support member 105 has a two sections 120, 122 on either side
of an inflection point 124. The inflection point 124 is positioned
at about the 12 o'clock position in section 3. The radius of
curvature of the sections 120, 122 may be the same or different.
The cross section shape of the support member 105 is generally
circular but may have one or more different cross section shapes in
alternative embodiments.
[0062] FIG. 6B illustrates the second support member 105 extending
from an end 102' to an end 104' along in a counter-clockwise manner
about the lumen interior wall (sectioned phantom lines) and the
device axis 121. The support member 110 extends from the end 102'
in section 1 at the 6 o'clock position, up to the 3 o'clock
position in section 2, the 12 o'clock position in section 3, 9
o'clock position in section 4 to the end 104' at the 6 o'clock
position in section 5. The support member 110 has two sections 130,
132 on either side of an inflection point 134. The inflection point
134 is positioned at about the 12 o'clock position in section 3.
The radius of curvature of the sections 120, 122 may be the same or
different. The cross section shape of the support member 105 is
generally circular but may have one or more different cross section
shapes in alternative embodiments.
[0063] FIG. 6C illustrates the crossover 106 and first and second
support members 105, 110 joined together at the ends. The first
sections 120, 130 form a rounded frame 126. The angle .beta. is
formed by a portion of the lumen wall contacting end 102 and a
plane containing the frame 126 and is referred to as the take off
angle for the elongate members at end 102. In one alternative, the
angle .beta. is formed by a portion of the lumen wall contacting
end 102 and a plane containing all or a portion of one or both
sections 120, 130. In yet another alternative, the angle .beta. is
formed by a portion of the lumen wall contacting end 102 and a
plane containing all or a portion of end 102 and all or a portion
of the crossover 106. Another angle .beta. is formed on end 104 as
discussed above but in the context of end 104, a portion of the
lumen wall contacting end 104, sections 122, 132 and the rounded
frame 128 as illustrated in FIGS. 7A-7C. An angle formed by the
support frames 126, 128 ranges generally between 20 degrees to 160
degrees in some embodiments and generally between 45 degrees to 120
degrees in some other embodiments.
[0064] FIG. 7A is a side view of section 130 in FIG. 6B, FIG. 7B is
a top down view of FIG. 6B and FIG. 7C is side view of section 132
in FIG. 6B. The angle .beta. ranges generally between 20 degrees to
160 degrees in some embodiments and generally between 45 degrees to
120 degrees in some other embodiments. The angle .alpha. is formed
by a portion of section 120, a portion of section 130 and the end
102. Alternatively, the angle .alpha. is formed by the end 102 and
tangents formed with a portion of the sections 120, 130. Another
angle .alpha. is formed on end 104 as discussed above but in the
context of end 104, a portion of the lumen wall contacting end 104
and sections 122, 132. The angle .alpha. ranges generally between
40 degrees to 170 degrees in some embodiments and generally between
70 degrees to 140 degrees in some other embodiments.
[0065] FIG. 7D illustrates a top down view of FIG. 6C. The angle
.sigma. is defined as the angle between a portion of section 120
between the inflection point 124 and the end 102 on one side and a
portion of section 130 between the inflection point 134 and the end
102' on the other side. The angle .sigma. is also defined as the
angle between a portion of section 122 between the inflection point
124 and the end 104 on one side and a portion of section 132
between the inflection point 134 and the end 104' on the other
side. The angle .sigma. defined by sections 120, 130 may be the
same, larger, or smaller than the angle .sigma. formed by the
sections 122, 132. The angle .sigma. ranges generally between 10
degrees to 180 degrees in some embodiments and generally between 45
degrees to 160 degrees in some other embodiments.
[0066] FIG. 7D illustrates an end view of FIG. 6C taken from end
102. The angle .theta. is defined as the angle between a plane
tangent to a portion of section 120 and a plane containing the end
102 that is also generally parallel to the device axis 121. An
angle .theta. may also be defined as the angle between a plane
tangent to a portion of section 130 and a plane containing the end
102 that is also generally parallel to the device axis 121. The
angle .theta. defined by section 120 may be the same, larger, or
smaller than the angle .theta. formed by the section 130.
Similarly, an angle .theta. may be defined as discussed above and
using as the angle between a plane tangent to a portion of section
122 or 132 and a plane containing the end 102 that is also
generally parallel to the device axis 121. The angle .theta. ranges
generally between 5 degrees to 70 degrees in some embodiments and
generally between 20 degrees to 55 degrees in some other
embodiments.
[0067] FIGS. 7F and 7G are perspective views of an alternative
embodiment of the device illustrated in FIG. 6C. In the embodiment
illustrated in FIGS. 7F and 7G, the support member 110 crosses
underneath and does not contact the support member 105 at the
crossover 106. The gap "g" between the support members is also
illustrated in the FIG. 7G.
[0068] FIG. 8A illustrates the elongate body 105 with a generally
circular cross section. However, many other cross section shapes
are possible and may be used such as, for example, rectangular
elongate body 105a (FIG. 8B), rectangular elongate body with
rounded edges (not shown), oval elongate body 105b (FIG. 8C) and
circular elongate body with a flattened edge 105c (FIG. 8D). In
some embodiments, an elongate body will have the same cross section
along its length. In other embodiments, an elongate body will have
different cross sections along its length. In another embodiment,
an elongate body has a number of segments and each segment has a
cross section shape. The segment cross section shapes may be the
same or different. The cross section shape of the elongate member
is a factor used to obtain the desired radial force along the
elongate member. The material used to form the elongate body (i.e.,
a biocompatible metal alloy such as Nitinol) may be drawn to have a
desired cross section shape, or drawn in one cross section shape
and then treated using conventional techniques such as grinding,
laser cutting and the like to obtain the cross section shape were
desired.
[0069] FIGS. 9A, 9B illustrate an embodiment of a material capture
structure 115 extended across a generally planar, rounded frame 126
formed by the support members. FIG. 9A is a slight perspective view
of a side view of the device. In this embodiment, sections 120, 130
of the support members lie mostly within in a single plane (i.e.,
in a side view of FIG. 9A section 110 is visible and blocks view of
section 120) that also holds the rounded frame 126. FIG. 9B is a
perspective view showing the material capture structure 115
extended between and attached to rounded frame 126. In this
embodiment, the capture structure 115 extends across and is
attached to the first sections 120, 130. In this embodiment, the
material capture structure is a plurality of generally rectangular
filter cells 119 formed by intersecting filaments 118. Other types
of filter structures are described in greater detail below and may
also be supported by the support frames formed by the structural
members. In some embodiments such as FIGS. 9A and 9B, the angle
.beta. may also define the angle between the device axis and a
plane containing a material capture structure.
[0070] The support frame 126 and the material capture structure 115
is not limited to planar configurations. Non-planar and compound
configurations, for example, are also possible as illustrated in
FIGS. 10A and 10B. FIG. 10A is a side view of a non-planar
structural support 110' having another inflection point 134'
between the inflection point 134 and the end 102. The structural
support 110' has more than one different radius of curvature
between the end 102 and the crossover 106. In some embodiments,
there could be more than one radius of curvature between the end
102 and the inflection point 134' as well as be more than one
radius of curvature between the inflection point 134' and the
inflection point 134. As a result, section 130' is a section
possibly having different shapes, a number of different curvatures
and at least one inflection point. As seen in FIG. 10B, the support
structure 105' is also non-planar with more than one different
radius of curvature between the end 102 and the inflection point
124. In some embodiments, there could be more than one radius of
curvature between the end 102 and the inflection point 124' as well
as be more than one radius of curvature between the inflection
point 124' and the inflection point 124. As a result, section 120'
is a section having different shapes, a number of different
curvatures and one or more inflection points. Similar non-planar
configurations may be used on end 104. The material capture
structure 115' is adapted to conform to the shape of non-planar
frame 126' to produce a non-planar filter support structure.
[0071] FIG. 11 illustrates a material capture structure 115 that
remains in a generally planar arrangement between opposing portions
of the support members 105, 110. In addition to FIG. 10B above,
other alternative non-planar capture structures are possible even
if the support frame is generally planar. FIG. 12A is a perspective
view of a non-planar capture structure 245 within a generally
planar support frame formed by support members 105, 110. Capture
structure 245 is formed by intersecting strands, fibers, filaments
or other suitable elongate material 218 to form filter cells 219.
The capture structure 245 is slightly larger than the support frame
dimensions resulting in a filter structure that is deformed out of
the plane formed by the support structure as illustrated in FIG.
12B.
[0072] The material capture structure 115 may be in any of a number
of different positions and orientations. FIG. 13A illustrates an
embodiment of a filter of the present invention having two open
loop support frames formed by support members 105, 110. Flow within
the lumen 10 is indicated by the arrow. In this embodiment, the
material capture structure 115 is placed in the upstream open loop
support structure. In contrast, the material capture structure may
be positioned in the downstream open loop support structure (FIG.
13B). In another alternative configuration, both the upstream and
the downstream support frames contain material capture structures
115. FIG. 13C also illustrates an embodiment where a material
capture structure is placed in every support loop in the
device.
[0073] There are filter device embodiments having equal numbers of
support frames with capture structures as support frames without
capture structures (e.g., FIGS. 13A and 13B). There are other
embodiments having more support frames without capture structures
than there are support frames with capture structures. FIG. 14
illustrates a filter embodiment 190 having more support frames
without capture structures than support frames with captures
structures. The filter device 190 has two support members 105, 110
that are positioned adjacent to one another to form a plurality of
support frames that are presented to the flow within the lumen 10.
Alternatively, the plurality of support frames positioned to
support a material capture structure across the flow axis of the
device 190 or the lumen 10. The support members are joined together
at end 192 and have two inflection points before being joined at
end 194. The support members 105, 110 cross over one another at
crossovers 106 and 196. The support frame 191 is between end 192
and crossover 106. The support frame 193 is between the crossovers
106, 196. The support frame 195 is between the cross over 196 and
the end 194.
[0074] In addition, the filter device 190 has a retrieval feature
140 on each end. The retrieval feature 140 has a curved section 141
ending with a ball 142. The retrieval feature 140 rises up above
the lumen wall placing the ball 142 and all or a portion of the
curved section 141 into the lumen flow path to simplify the process
of snaring the device 190 for retrieval or repositioning. Having a
retrieval feature on each end of the device allows the device 190
to be recovered from the upstream or downstream approach to the
device in the lumen 10. Various aspects of retrieval feature
embodiments of the present invention are described in greater
detail below.
[0075] FIG. 14A illustrates the filter 190 imposed on a phantom
cylinder having 7 sections. The retrieval features 140 have been
omitted for clarity. The first support member 105 extends clock
wise from end 192 about and along the axis of the device 121. The
first support member 105 crosses section 2 at the 9 o'clock
position, section 3 and the crossover 106 at the 12 o'clock
position, section 4 at the 3 o'clock position, section 5 and the
crossover 196 at the 6 o'clock position, section 6 at the 9 o'clock
position and section 7 and the end 194 at the 12 o'clock position.
The second support member 110 crosses section 2 at the 3 o'clock
position, section 3 and the crossover 106 at the 12 o'clock
position, section 4 at the 9 o'clock position, section 5 and the
crossover 196 at the 6 o'clock position, section 6 at the 3 o'clock
position and section 7 and the end 194 at the 12 o'clock position.
FIG. 14B illustrates an alternative device embodiment 190a that is
similar to the device 190 except that all support frames formed by
the elongate members is used to support a material capture
structure. In the illustrated embodiment, frames 191, 193 and 195
each support at material capture structure 115.
[0076] FIG. 14C illustrates an alternative configuration of filter
190. The filter device 190b is similar to device 190 and 190a and
includes an additional support member 198 extending along the
support member 105. In one embodiment, the additional support
member 198 extends along the device axis 121, is positioned between
the first and the second support members 105, 110 and is attached
to the first end 192 and the second end 194. In the illustrative
embodiment, the third support member 198 begins at end 192 and the
6 o'clock position in section 1, crosses section 3 and the
crossover 106 at the 12 o'clock position, crosses section 5 and the
crossover 196 at the 6 o'clock position, and ends at the 12 o'clock
position in section 7 at the end 194.
[0077] FIG. 15 illustrates the planes of symmetry found in some
filter device embodiments of the present invention. The filtering
structure that would be supported by one or both of the support
frames is omitted for clarity. In one aspect, FIG. 15 illustrates
an embodiment of an endoluminal filter of the present invention
having a support structure that is generally symmetrical about a
plane 182 that is orthogonal to the flow direction of the filter or
filter axis 121 and contains a crossover point 106 between two
structural elements of the support structure 105, 110. In another
aspect, FIG. 15 illustrates an embodiment of an endoluminal filter
of the present invention having a support structure that is
generally symmetrical about a plane 184 that is parallel to the
flow direction of the filter (i.e., axis 121) and contains both
ends of the support structure 102, 104. It is to be appreciated
that some filter device embodiments of the present invention may
have either or both of the above described symmetrical attributes.
It is to be appreciated that the above described symmetrical
attributes are also applicable to the construction of embodiments
of the material capture structures alone or as installed in a
filter.
[0078] FIGS. 16A and 16B illustrate the response of a filter device
200 in response to a piece of clot material 99 contacting the
material capture structure 115. The direction of flow and movement
of the clot material 99 within lumen 10 is indicated by the arrows.
The filter device 200 is similar to the embodiments described above
with regard to FIGS. 6A-7G with the addition of the retrieval
features 240 added to the ends 102, 104. The retrieval feature 240
has a curved section with multiple curves 141 that terminate with
an atraumatic end 242. The multiple curves 141 are advantageously
configured to collapse about a retrieval device (i.e, a snare in
FIGS. 71A, 71B) to facilitate device 100 capture during retrieval.
In this illustrative embodiment the multiple curves are generally
shaped like a sinusoid and the end 242 is shaped like a ball or a
rounded tip.
[0079] It is believed that upon embolic entrapment, the force fluid
flow acting on clot material 99 is transmitted from the capture
structure 115 to support frame 126 securing the capture structure
115. The force acting on the support frame 126 and in turn the
support members 105, 110 urges the end 104 into the lumen wall.
This action effectively fixes the second support frame 128. The
force acting on the support frame 126 causes the angle .beta.
associated with the support frame 126 to increase the support frame
126 wedges further into the lumen wall.
[0080] FIGS. 17, 18, and 19 illustrate various alternative filter
device embodiments with support structures of different size and
that may not be in contact with the lumen wall. FIG. 17 illustrates
a perspective view of a filter device 300 according to one
embodiment of the present invention. In this embodiment, elongate
members 305, 310 are joined at ends 302, 304, to form frame 309
from end 302, sections 301, 303 and crossover 306 and frame 311
from end 304, sections 307, 308 and cross over 306. The frame 309
supports another embodiment of a material capture according to the
present invention. The illustrated material capture structure 312
includes a plurality of strands 313 joined 314 to form a plurality
of filter cells 315. The strands 313 may be joined using processes
described below (e.g., FIG. 53A-53D) or may be formed by extruding
the desired shape and size filter cell 315 from a material (e.g.,
FIG. 56).
[0081] FIG. 17 illustrates a so-called capacitor design because the
elongate members that form frame 311 are configured to expand and
contract the size and shape of frame 311 in response to changes in
frame 309. This design feature allows an embodiment of the present
invention to accommodate a large range of sizing and diameter
changes. FIG. 18 illustrates an embodiment of the filter device 300
having a capture structure 350 having filter cells 354 formed by
intersecting strands 352. FIG. 18 illustrates how inward movement
of the frame 309 (indicated by the arrows) is corresponds to
outward movement (indicated by the arrows) in the frame 308.
[0082] FIG. 19 illustrates an alternative filter device embodiment
where the second frame is not closed. The filter device 340
includes support members 341, 343 that form a rounded support frame
344 to support the material capture device 115. The support members
341, 343 extend some distance beyond the cross over 342 but are not
joined to form another end. A portion 346 of the support member 343
is shown extending beyond the cross over 342. The support members
341, 343 may extend for some distance along the device axis after
the cross over 342 and may follow the same or a different shape as
the shape of the support members in frame 309. The support members
may extend along the device axis similar to earlier described two
loop embodiments but stop short of being joined at a second end
(e.g., FIG. 87).
[0083] The ends of the filter devices of the present invention may
be formed in a number of ways. A portion of the support structures
105, 110 may be wound 180 around one another (FIG. 20). In the
illustrated embodiment, the wound portion 180 is used to form the
end 102. In another alternative, the filtering device is formed
from a single support member 105 that loops back on itself. In the
illustrative embodiment of FIG. 21, support member 105 is formed
into loop 181 to form the end 102. In an alternative to loop 181,
the loop may contain a plurality of undulations (i.e., loop 181a in
FIG. 22) or be formed into the shape of a retrieval feature or
other component of the filter device. In yet another alternative, a
cover is used to clamp, to join or otherwise bond the structural
members together. In the illustrative example of FIG. 23, a
generally cylindrical cover 183 is used to join together members
105, 110. The cover 183 may use any conventional joining method to
secure the support members together such as adhesive, welding,
crimping and the like. An alternative tapered cover 185 is
illustrated in the embodiment of FIG. 24. The tapered cover 185 has
a cylindrical shape and a tapered end 186. The tapered end 186
around the end having the tapered cover 185 and facilitates
deployment and retrieval of the device. In one embodiment, the
cover 185 is made of the same material as the structural member
and/or the retrieval feature.
[0084] Some filter device embodiments of the present invention may
include one or more retrieval features to assist recapturing and
partially or fully recovering a deployed filter device. Retrieval
features may be placed in any of a number of positions on the
device depending upon the specific filter device design. In one
embodiment, the retrieval device is positioned not only for ease of
device recovery but also attached to the device in such a way that
pulling on the retrieval device actually facilities removal of the
device. In one embodiment, pulling on the retrieval device pulls
the structural members away from the lumen wall. These and other
aspects of the cooperative operation of the retrieval features
during deployment and recapture will be described below with regard
to FIGS. 72A-73D.
[0085] Several alternative embodiments of retrieval devices of the
present invention are illustrated in FIGS. 25-27C. FIG. 25
illustrates a retrieval device 240 with a simple curve 241 formed
in the end. FIG. 26 illustrates a retrieval device 240 with a curve
244 that is has a sharper radius of curvature than the curve 241 in
FIG. 25. FIG. 27A illustrates a retrieval feature 140 having a
curved section 141 with an atraumatic end 142. In the illustrative
embodiment, the atraumatic end 142 is a ball than may be added to
the end of curve 141 or formed on the end of the member used to
form the feature 140. A ball 142 may be formed by exposing the end
of the curved section 141 to a laser to melt the end into a ball.
FIG. 27B illustrates a retrieval feature with a plurality of curved
sections 241. In one embodiment, the curved sections 241 have a
generally sinusoidal shape. In another embodiment, the curved
sections 241 are configured to collapse when pulled on by a
retrieval device like a snare (i.e., FIGS. 71A, 71B) FIG. 27C
illustrates a retrieval feature 240 having a plurality of curved
sections 241 and a ball 142 formed on the end. In additional
embodiments, retrieval features of the present invention may
include markers or other features to help increase the visibility
or image quality of the filter device using medical imaging. In the
illustrative embodiment of FIG. 27C, a radio opaque marker 248 is
placed on the curved section 241. The marker 248 may be made from
any suitable material such as platinum, tantalum or gold.
[0086] A cover placed about the ends may also be used to join a
retrieval feature to an end or two support members. A cover 183 may
be used to join a retrieval feature 240 to a support member 105
(FIG. 28A). In this illustrative embodiment, the support structure
105 and the retrieval feature 240 are separate pieces. A cover 183
may also be used to join together two members 110, 105 to a
retrieval feature 140 (FIG. 28B). In another alternative
embodiment, the retrieval feature is formed from a support member
that is joined to the other support member. In the illustrative
embodiment of FIG. 28C, the support member 105 extends through the
tapered cover 185 and is used to form a retrieval feature 240. The
tapered cover 185 is used to join the first support member and
second support member 105, 110. In one alternative of the
embodiment illustrated in FIG. 28C, the diameter of the support
member 105 is greater than the diameter of the retrieval feature
240. In another embodiment, the diameter of the retrieval feature
240 is less than diameter of the support member 105 and is formed
by processing the end of the support member down to a smaller
diameter and is then shaped to form the retrieval feature 240. In
another embodiment, the ball 242 or other atraumatic end is formed
on the end of the retrieval feature.
[0087] FIG. 29 illustrates a partial side view of a filter device
in a lumen 10. This figure illustrates the retrieval feature angle
.tau. formed by the retrieval feature and the interior lumen wall.
The retrieval feature angle .tau. is useful in adjusting the height
and orientation of the retrieval curves 214 and ball 242 within the
lumen to improve the retrievably of the device. Generally,
retrievably improves as the retrieval feature moves closer to the
device axis 121 (i.e., central to the lumen axis as well).
Additional curves may be added to the support members 110, 105 as
needed to provide the desired range of retrieval feature angles. In
one embodiment, .tau. ranges from -20 degrees to 90 degrees. In
another embodiment, .tau. ranges from 0 degrees to 30 degrees.
[0088] Attachment of Material Capture and Other Filtering
Structures to Support Structures
[0089] A number of different techniques may be used to attach
material capture structures to support members. For clarity, the
material capture structure has been omitted from the illustrations
that follow but would be suitably secured using the line 351 or a
loop. In FIG. 30 illustrates a line 351 with a number of turns 353
about a support member 105. The line 351 is secured back onto
itself using a clip 351a. FIG. 31 illustrates a line 351 with a
number of turns 353 about the support member 105 to secure a loop
353a that may be used to tie off or otherwise secure a material
capture structure. A line 351 may also be glued 355 to a support
105 (FIG. 32). In another alternative embodiment, holes 356 formed
in the support member are used to secure one or more lines 351 that
are used in turn to secure a material capture structure. In an
alternative to the linear arrangement of holes 356, FIG. 36
illustrates how holes 356 may be provided in a number of different
orientations to assist in securing a material capture to the
support structure 105. Alternatively, the line 351 may be glued 355
into the hole 356 (FIG. 34A and in section view 34B).
[0090] In other alternative embodiments, the holes 356 are used to
secure lines 351 as well as provide a cavity for another material
to be incorporated into the support structure 105. Other materials
that may be incorporated into the support structure 105 include,
for example, a pharmacological agent or a radio opaque material.
The use of a radio opaque marker may be useful, for example, when
the support structure is formed from a material with low imaging
visibility such as, for example, shape memory polymers or
biodegradable polymers. FIG. 34C illustrates an embodiment where
one hole 356 is used to secure a line 351 and the other is filled
with material or compound 357. In another alternative, some or all
of the holes 356 may be filled with another material as in FIG. 35.
In yet another alternative, the holes 356 are filled with small
barbs 358 that may be used to secure the device to the lumen wall.
The illustrative embodiment of FIG. 37 the barbs 358 are only long
enough to break the surface of the lumen interior wall and not
pierce through the lumen wall. While each of the above has been
described with regard to the support member 105, it is to be
appreciated that these same techniques could be applied to the
support member 110 or other structure used to support a material
capture structure.
[0091] It is to be appreciated that the support structure
embodiments are not limited to single member constructions. FIG.
38A illustrates an alternative braided support member 105'. Braided
support structure 105' is formed by 4 strands a, b, c, and d. FIG.
38B illustrates another alternative braided support member 105''.
Braided support structure 105'' is formed by 3 strands a, b, and c.
FIG. 38B also illustrates how the braid structure may be used to
secure a line 351. As can be seen in this embodiment, by using the
line 351 a material capture structure (not shown) is secured to at
least one strand within the braided structure 105''.
[0092] FIGS. 39 and 40 illustrate additional alternative techniques
to secure a filter support structure to a support member. As
illustrated in FIG. 39, there is illustrated a technique to secure
a material capture structure securing line 351 to a support frame
105 using a material 481 wrapped around the support frame 105. In
this manner, the material capture structure (not shown but attached
to the lines 351) is attached to a material 481 that at least
partially covers the first support structure 105. The lines 351 are
passed between the material 481 and the support structure 105 as
the material 481 as wraps 483 are formed along the support
structure 105. The lines 351 are omitted in the embodiment
illustrated in FIG. 40 as the material 481 forms wraps 483 and is
used to secure the material capture structure (not shown). In one
embodiment, the material 481 forms a tissue ingrowth minimizing
coating over at least a portion of support structure.
Alternatively, the filtering structure (not shown) is attached to
the support structure 105 using a tissue ingrowth minimizing
coating 481.
[0093] FIGS. 41, 42 and 43 relate to securing the material capture
structure to a lumen disposed around the support member. FIG. 41
illustrates a lumen 402 that has been cut into segments 402a, 402b,
402c that are spaced by a distance "d." Lines 351 are attached
around the support member and in the space "d" between adjacent
segments. The segments may remain apart or be pushed together to
reduce or eliminated the spacing "d." In contrast the segments in
FIG. 41, the lumen 402 in FIG. 42 provides notches 403 for securing
line 351. FIG. 43 illustrates a lumen 405 having a tissue growth
inhibiting feature 408 extending away from the support member 105.
As seen in section view 406 the inhibiting feature 408 has a
different cross section shape than the support member 105. In
addition, in some embodiments, the lumen 405 is selected from a
suitable tissue ingrowth minimizing material so that is acts like a
tissue ingrowth minimizing coating on the support structure. In
other embodiments, the cross section shape 406 is configured to
inhibit tissue growth over the tissue ingrowth minimizing
coating.
[0094] FIGS. 44 and 45 illustrate filter device embodiments
utilizing dual lumen structures. The dual lumen structure 420
includes a lumen 422 and a lumen 424 and has a generally teardrop
shaped cross section area. In this illustrative embodiment, the
support structure 105 is disposed in the lumen 422 and the second
lumen 424 is used to hold lines 351 and secure a material capture
device (not shown). In the illustrative embodiment, the lumen
structure 420 has been cut to form a number of segments 420a, b, c
and d in the lumen 424. The connection rings formed by the segments
420a-d are used to secure lines 351 as needed. FIG. 45 illustrates
an alternative configuration for the lumen structure 420. In this
alternative configuration, a release line 430 extends through the
notched lumen 424. The lines 351 extend about the release line 430
and hence to secure the material capture structure (not shown).
Since the lines 351 are connected using the release line, removal
of the release line from lumen 424 will allow the material capture
structure secured using the lines 351 to be released from the
support structure and removed from the lumen. A configuration such
as that shown in FIG. 45 provides a filtering structure that would
be releasably attached to an open loop (i.e., an open loop frame
formed by the support structure). The embodiment illustrated in
FIG. 45 provides a release line 430 positioned along the open loop
(formed by member 105) and a filtering structure (not shown) is
attached to the open loop using the release line.
[0095] In another embodiment, a filter device of the present
invention is configured to be a coated endoluminal filter. In
addition to coating all or a portion of the support structures or
filter elements of this device, the coating on the support members
may also be used to secure a filtering structure to the support
structure. In one embodiment, a coated endoluminal filter has a
support structure, a filtering structure attached to the support
structure and a coating over at least a portion of support
structure. In one aspect, the coated support structure may form a
rounded support frame, an open loop or other structure to support a
filtering structure described herein. In one embodiment, the
coating over at least a portion of support structure is used to
secure a plurality of loops (i.e., flexible form or rigid form) to
the support structure. The plurality of loops are then used to
secure a filtering structure such as a material capture structure,
for example, within the coated endoluminal filter. In one
embodiment, the coating is a tissue ingrowth minimizing
coating.
[0096] It is to be appreciated that a filtering structure may also
be attached to the support structure using the tissue ingrowth
minimizing coating. In some embodiments, the tissue ingrowth
minimizing coating is wrapped around the support structure or,
alternatively, it may take the form of a tube. If a tube is used,
the tube may be a continuous tube or comprise a plurality of tube
segments. The tube segments may be in contact or spaced apart. The
tube may have the same or different cross section shape than the
support member. In another embodiment, the tissue ingrowth
minimizing coating is in the shape of a tube and the support
structure is in the interior of the tube.
[0097] In some other embodiments, a bonding material is provided
between the tissue ingrowth minimizing coating and the support
structure. The bonding material may be wrapped around the support
structure or may take the form of a tube. If a tube is used, the
tube may be a continuous tube or comprise a plurality of tube
segments. The tube segments may be in contact or spaced apart. The
bonding material tube may have the same or different cross section
shape than the support member or the coating about the bonding
material. In one embodiment, the bonding material is in the shape
of a tube with the support member extending through the bonding
material tube lumen. In one embodiment, a plurality of loops (i.e.,
flexible form or rigid form) are secured to the support structure
by sandwiching the line used to form the loops between a bonding
material around the support member and a coating around the bonding
material. In one embodiment, the bonding material has a lower
reflow temperature than the coating around the boding material. In
this embodiment, the line used to form the loops is secured at
least in part by reflowing the bonding material to secure the line
between the coating around the bonding material and the support
structure. In another alternative, the coating around the bonding
material is a shrink fit coating that also shrinks around the
bonding structure and the support member during or after a process
that reflows the bonding material. In any of the above
alternatives, the plurality of loops may be used to secure a
filtering structure such as a material capture structure, for
example, within the coated endoluminal filter.
[0098] Some embodiments of the coated endoluminal filter include
some or all of the other features described herein such as, for
example, a retrieval feature on the support structure, a retrieval
feature on each end of the support structure, a support structure
having two elongate bodies that are joined together to form a
rounded frame, and a support structure having two spiral shaped
elongate bodies. In addition, some coated endoluminal filters have
a support structure that is generally symmetrical about a plane
that is orthogonal to the flow direction of the filter and contains
a crossover point. In another alternative coated endoluminal filter
embodiment, the support structure of the coated endoluminal filter
is generally symmetrical about a plane that is parallel to the flow
direction of the filter and contains both ends of the support
structure.
[0099] FIGS. 46-51B illustrate several aspects of coated
endoluminal filter embodiments. These figures are not to scale and
have exaggerated dimensions to make clear certain details. FIG. 46
illustrates a number of segments 450 of a coating placed about the
support member 105. One or more lines 451 extend between the
segment 450 and the support member 105 and form a plurality of
loops 453. In one embodiment, the line 451 is a single continuous
line. Once formed, the segments 450 undergo suitable processing to
shrink the segment diameter around the line 451 and the support
member 105 thereby securing the line 451 and loops 453 against the
support structure (FIG. 47). The segment 450 is secured about the
support member 105 as illustrated in the end view of FIG. 51A. The
segments 450 in the embodiment shown in FIG. 47 are spaced apart.
In other embodiments, the segments 450 may be in contact or have
spacing different from that illustrated in FIG. 47. The sizes of
the various components illustrated in FIGS. 46, 47 and 51A are
exaggerated to show detail. The dimensions of one specific
embodiment are: the support member 105 is a NiTi wire having an
outside diameter of between 0.011'' and 0.015''; the segments 450
are 0.2'' long cut from a PTFE heat-shrink tubing having and a
pre-shrunk outside diameter of 0.018'' and a wall thickness of
0.002''; the line 451 is monofilament ePTFE of an outer diameter of
0.003'' and the loops 453 have a nominal diameter of between about
0.1'' to about 0.4''.
[0100] FIGS. 48, 49 and 51B illustrate a bonding material 456 about
the support member 105 and a number of segments 455 about the
bonding material 456. One or more lines 451 extend between the
segments 455 and the bonding material 456 and form a plurality of
loops 453. In one embodiment, the line 451 is a single continuous
line. Once formed, bonding material 456 and/or the segments 450
undergo suitable processing to secure the line 451 between the
bonding material 456 and the coating 455 thereby securing the line
451 and loops 453 against the support structure (FIG. 49). The
coating segment 450 and the bonding material 456 is secured about
the support member 105 as illustrated in the end view of FIG. 51B.
The segments 455 in the embodiment shown in FIG. 48 are spaced
apart by spacing "d." In other embodiments, the segments 455 may be
in contact after processing (FIG. 49) or have spacing different
from that illustrated in FIG. 48. In a preferred embodiment, the
spacing between the segments 455 is removed by a portion of the
boding material 456 flowing between and securing adjacent segments
455. The sizes of the various components illustrated in FIGS. 48,
49 and 51B are exaggerated to show detail. The dimensions of one
specific embodiment are: the support member 105 is a NiTi wire
having an outside diameter of between 0.011'' and 0.015''; the
segments 455 are 0.3'' long cut from a PTFE heat-shrink tubing
having a pre-shrunk outside diameter of 0.022'' and a wall
thickness of 0.002''; the bonding material is a tube of FEP heat
shrink tubing having a pre-shrunk outside diameter of 0.018'' and a
wall thickness of 0.001''; line 451 is 0.002'' outer diameter PET
monofilament and the loops 453 have a nominal diameter of between
about 0.1'' to about 0.4''. It is to be appreciated that the
segments 450, 455 and bonding material 456 may be formed, for
example, from: ePTFE, PTFe, PET, PVDF, PFA, FEP and other suitable
polymers. Moreover, embodiments of strands, lines, fibers and
filaments described herein may also be formed from ePTFE, PTFe,
PET, PVDF, PFA, FEP and other suitable polymers.
[0101] FIG. 50 illustrates the use of a continuous flexible line
452 passed through a continuous coating segment 450 forming loops
454. The loops 454 are disposed along the length of the coating 450
at regular intervals; the continuous coating segment 450 are
uniform in length to the support members 105 using a PTFE heat
shrink tubing having pre-shrunk diameter of 0.018'' and a wall
thickness of 0.002''. The line 452 is monofilament ePTFE of an
outer diameter of 0.003'' and the loops 454 have a nominal diameter
of between about 0.1'' to about 0.4''.
[0102] FIGS. 52A-53D illustrate alternative techniques for forming
and/or attaching a filtering structure to a support structure. FIG.
52A illustrates an embodiment of a support frame 126 formed by
support members 105, 110 between the end 102 and crossover 106 as
described above. Loops 453/454 are formed using lines 451/452 as
described above with regard to FIGS. 46-51B. Thereafter, a filament
461 is suitably attached 462 to a line 451/452 by tying, welding,
gluing or by incorporating the filament 461 during the processing
steps described with regard to FIGS. 46-51B. Next, the filament is
traverses across the frame 126 and about the loops 453/454. In this
embodiment, the lacing pattern between loops crosses a line
extending between the end 102 and the crossover 106. The general
pattern is that the filament extends across the frame 126 and
around one right side loop (1) and back across the frame 126 (2)
and around (3) a left side loop 453/454. The lacing process
continues as shown in FIGS. 52B and 52C. When completed, the lacing
process produces a filtering structure 465 from one or more
filaments secured to loops 451/452 that are secured to the support
members 105/110. The filament in the filtering structure 465 may be
taut between the loops 451/452 or have some degree of sag (as
illustrated in FIG. 52D). Filament 461 or other material used to
form material capture structure may be coated with a
pharmacological agent (coating 466 in FIG. 58). The pharmacological
agent may be any of a wide variety of compounds, drugs and the like
useful in the procedures performed using or the operation of
various filtering device embodiments of the present invention. The
pharmacological agent coating 466 may include pharmacological
agents useful in preventing or reducing thrombus formation on the
filtering structure, chemically lysing debris captured in the
filtering structure and the like.
[0103] FIG. 53A illustrates an embodiment of a support frame 126
formed by support members 105, 110 between the end 102 and
crossover 106 as described above. Loops 453/454 are formed using
lines 451/452 as described above with regard to FIGS. 46-51B.
Thereafter, a filament 461 is suitably joined 462 to a line 451/452
by tying, welding, gluing or by incorporating the filament 461
during the processing steps described with regard to FIGS. 46-51B.
Next, the filament 461 was laced as described above with regard to
FIG. 52A about the loops 453/454. In this embodiment, however, the
lacing pattern between loops remains generally parallel to a line
extending between the end 102 and the crossover 106. When
completed, the lacing process produces a filtering structure from
one or more filaments 461 that extend parallel to a line between
the end 102 and crossover 106 and are secured to loops 451/452
secured to the support members 105/110. This filtering structure
(FIG. 53A) may be used within a filter device of the present
invention. In addition, the filtering structure in FIG. 53A (as
well as the structure in FIG. 52D) may be further processed to join
468 adjacent filaments 461 to form filter cells 469 as part of a
filtering structure 470. The process used to join 468 adjacent
filaments 461 may include any conventional joining technique such
as tying, welding, bonding, gluing, and the like. In addition,
segments of tubing (i.e., segments 450, 455 456 described above)
could be used to join 468 portions of adjacent filaments 461. In
one specific embodiment, the filament 461 is ePTFE monofilament
with an outer diameter of 0.003'' joined 468 using a piece of FEP
heat shrink tubing having a pre-shrunk outer diameter of 0.008''
and a wall thickness of 0.001''. The filtering structure 470 may be
taut between the loops 451/452 or have some degree of sag (as
illustrated in by the filtering structure in FIG. 52D). The filter
cells 469 may be formed in numerous sizes and shapes as described
in greater detail below.
[0104] Alternatively, the filtering structures in FIG. 53A and FIG.
52D may incorporate additional loops 491 formed by looping the
filament 461 as illustrated in FIG. 57A.
[0105] Alternative Filtering and/or Material Capture Structures
[0106] In some embodiments, the material capture structure contains
a number of filter cells. Filter cells may be formed in a number of
different ways and have a number of different shapes and sizes. The
shape, size and number of filter cells in a specific filter may be
selected based on the use of a particular filter. For example, a
filter device of the present invention configured for distal
protection may have a filter cell size on the order of tens to
hundreds of microns to less than 5 millimeters formed by a
selecting a filter material with a pore size (FIGS. 63A, 63B)
suited to the desired filtration level. In other applications, the
filter cell may be formed by overlapping (i.e., joined or crossed
without joining) filaments to form cells that will filter out
debris in a lumen above a size of 2 mm. Various other filter sizes
and filtration capacities are possible as described herein.
[0107] Intersecting filaments (FIG. 54C) may be used to form
diamond shaped filter cells (FIG. 54A), as well as rectangular
shaped filter cells (FIGS. 54B, 2A and 9B). Multiple strand
patterns may also be used such as the three strand 461a, 461b and
461c array illustrated in FIG. 57B. Intersecting filaments may also
be knotted, tied or otherwise joined 468 (FIGS. 55A and 55E).
Intersecting filaments may form the same or different filter cell
shapes such as, for example, an elongated oval in FIG. 55C, one or
more joined diamonds as in FIG. 55B and an array of joined polygons
as in FIG. 55D. Cells may also be formed using the techniques
described above in FIGS. 52A-53D. In one embodiment, a filter cell
is defined by at least three intersecting filaments 461. The filter
element 461 may be formed from any of a wide variety of acceptable
materials that are biocompatible and will filter debris. For
example, filaments, lines and strands described herein may be in
the form of a multifilament suture, a monofilament suture a ribbon,
a polymer strand, a metallic strand or a composite strand.
Additionally, filaments, lines and strands described herein may be
formed from expanded polytetrafluoroethylene (ePTFE),
polytetrafluoroethylene (PTFe), Poly(ethylene terephthalate) (PET),
Polyvinylidene fluoride (PVDF),
tetrafluoroethylene-co-hexafluoropropylene (FEP), or
poly(fluoroalkoxy) (PFA), other suitable medical grade polymers,
other biocompatible polymers and the like.
[0108] The joined polygons may have any of the shapes illustrated
in FIGS. 60A-60F. It is to be appreciated that filter cells may
have any, one or more, or hybrid combinations of shapes such as,
for example, circular (FIG. 60A), polygonal (FIG. 60B), oval (FIG.
60C), triangular (FIG. 60D), trapezoidal or truncated conical (FIG.
60E).
[0109] In addition, the material capture structure may have filter
cells formed by extruding a material into a material capture
structure. FIG. 56 illustrates an exemplary filtering structure 312
where a material is extruded into strands 313 that are joined 314
and spaced apart for form one of more filter cells 315. In one
embodiment, the strands are extruded from Polypropylene material,
forming diamond shaped filter cells approximately 4 mm in height
and 3 mm in width.
[0110] FIGS. 59A-63B illustrate several different filtering
structure configurations. For simplicity of illustration, the
filtering material is shown attached to a circular frame 501. It is
to be appreciated that the circular frame 501 represents any of the
various open loop, rounded frame or other support frames described
herein. FIG. 59A illustrates a frame pattern similar to FIG. 52D.
FIG. 59B adds an additional transverse filaments 461a at an angle
to the filaments 461. FIG. 59C illustrates a plurality of filaments
461a extending up from the frame bottom 501a about a central
filament 461c and a plurality of filaments 461b extending down from
the frame top 501b about a central filament 461c. In this
illustrative embodiment, the filaments 461a,b are arranged
symmetrically about the central filament 461c. Other
non-symmetrical configurations are possible. More than one central
filament 461c may be used to form a variety of different size and
shaped polygonal filter cells (e.g., FIG. 59E).
[0111] Filaments may also be arranged using a variety of radial
patterns. Fr example, multiple filaments 461 may from a common
point 509 out the edge of frame 501. In some embodiments, the
common point is central to the frame 501 (FIG. 59D) and in other
embodiments the common point 509 is in a different, non-central
location. The sectors formed by the multiple filaments (FIG. 59D)
may be further divided into multiple filter cell segments by
winding a filament 461a about and across segment filaments 461b. In
contrast to a single filament spirally out from the point 509 as in
FIG. 59G, the segmented filter cells in FIG. 59F are formed by
attaching single filament 461a to the segment filaments 461b.
[0112] FIGS. 61A-C and FIG. 62 illustrate the use of a sheet of
material 520 to form a filter structure. The material 520 may have
any of a variety of shapes formed in it using any suitable process
such as punching, piercing, laser cutting and the like. FIG. 61A
illustrates a circular pattern 521 formed in material 520. FIG. 61B
illustrates a rectangular pattern 523 formed in material 520. FIG.
61C illustrates a complex pattern 522 cut into material 522. It is
to be appreciated that the material 520 may also be placed in the
frame 501 without any pattern (FIG. 62). The illustrative
embodiment of FIG. 62 may be useful for occluding the flow within a
lumen. Suitable materials 520 for an occlusion application include
for example, wool, silk polymer sheets, other material suited to
prevent blood flow in a lumen when extended across a lumen and the
like. Additionally, the filter material 520 may be a porous
material having pores 530 (FIG. 63A). The material 520 may be
selected based on the average size of individual pores 530 (FIG.
63B) depending upon the procedure or use of the filter device. For
example, the material 520 may be any of the porous materials using
in existing distal protection and embolic protection devices. In
general, a wide variety of pore 530 sizes are available and may
range from 0.010'' to 0.3''. Other pore sizes are also available
depending upon the material 520 selected.
[0113] FIGS. 64-65F illustrate the use of nets or other web
structures within the filtering device. The various net structure
embodiments described herein are used as material capture
structures within filter device embodiments of the present
invention. Each of these alternative is illustrated in a support
structure similar to that of device 100 in FIG. 2A and elsewhere.
When deployed within the lumen 10, the material capture structure
560 has a defined shape such as a cone with a discrete apex 565
(FIG. 64A). In this embodiment, the net structure is long enough to
contact the sidewall of the lumen 10 when deployed in the lumen 10.
Alternatively, the apex 565 may be attached to the end 104 to keep
the net 560 in the lumen flow path and out of contact with the
lumen sidewall (FIG. 64B). The net 565 may also have a rounded apex
565 (FIG. 65A) or a truncated cone (flat bottom) (FIG. 65D).
Alternatively, the net 560 may a discrete apex 565 so short that it
will not contact the lumen sidewall when deployed (FIG. 65B). The
short net may also have a rounded apex 565 (FIG. 65B), a flat apex
(FIG. 65E) or a sharp apex (FIG. 65C). In addition, the net 560 may
have a compound apex 565 (FIG. 65F).
[0114] FIGS. 66 and 67 illustrate how various different features
described above can be combined. For example, FIG. 66 illustrates a
multi-support frame device 480 having a retrieval feature on only
one end and an open frame (i.e., no filter structure). FIG. 67
illustrates an alternative multi-support frame device 485 having
different retrieval features on each end, filter structures in each
of the support structures and each of the filter structures having
a different filter capacity. It is to be appreciated that the above
described details of the construction, components, sizes, and other
details of the various filter device embodiments described herein
may be combined in a number of different ways to produce a wide
array of alternative filter device embodiments.
[0115] Delivery, Recovery and Repositioning of a Filtering
Device
[0116] FIG. 68A illustrates an embodiment of the filter device 100
of the present invention loaded into an intravascular delivery
sheath 705. The device 100 is illustrated and described above, for
example, in relation to FIG. 16A. Using conventional endoluminal
and minimally invasive surgical techniques, the device can be
loaded into the proximal end of the sheath 705, before or after
advancing the sheath 705 into the vasculature, and then advanced
through the sheath using a conventional push rod. The push rod is
used to advance the device 100 through the delivery sheath lumen as
well as fix the position of the device (relative to the sheath 705)
for device deployment. In one preferred technique, the device is
loaded into the proximal end of a delivery sheath that has already
been advanced into a desired position within the vasculature (FIG.
68B). The device 100 may be pre-loaded into a short segment of
polymeric tubing or other suitable cartridge that allows the device
100 to be more readily advanced through a hemostasis valve.
[0117] When used with a compliant delivery sheath 705, the
pre-formed shape of the device 100 deforms the sheath to conform to
the device shape (FIGS. 69A, 69B). Accordingly, a flexible,
compliant sheath 705 assumes the curvature of the stowed device.
The deformation of the delivery sheath 705 helps stabilize the
position of the sheath 705 in the vasculature and facilitates
accurate deployment of the device 100 to the intended delivery
site. In contrast, a non-compliant delivery sheath 705 (i.e., a
sheath that is not deformed to conform to the preformed shape of
the device 100) maintains a generally cylindrical appearance even
through the device 100 is stowed within it (FIG. 69C). Regardless
of the type of sheath used, device delivery is accomplished by
using the push rod on the proximal side of the device to fix the
position of the device within the sheath 705 and then withdrawing
the sheath 705 proximally. As the device 100 exits the distal end
of sheath 705, it assumes the pre-formed device shape (FIG.
69D).
[0118] The symmetrical device shape (see e.g., devices in FIGS. 15
and 16A), facilitates the deployment and retrieval of the device
from multiple access points in the vasculature. A device 100 is
shown positioned in the vasculature within the inferior vena cava
11 immediately below the renal veins 13 (FIG. 70). A femoral access
path (solid) and a jugular 14 access path (phantom) are
illustrated. The femoral access path (solid) and a jugular access
path may each be used for device deployment, repositioning and
retrieval. Alternatively, the vena cava could be accessed via
brachial or antecubital access for device deployment, repositioning
and retrieval.
[0119] Retrieval of the devices is most preferably accomplished by
endoluminal capture using one of the retrieval features described
herein. (i.e., FIGS. 27A-E) The retrieval features described herein
have been designed to work well using a commercially available
snares two of which are illustrated in FIG. 71A and FIG. 71B. The
single loop gooseneck snare 712 is illustrated in FIG. 71 inside of
a recovery sheath 710. The multiple loop Ensnare 714 is illustrated
in FIG. 71B inside of a recovery sheath 710. These conventional
snares are controlled by a physician using a flexible, integral
wire.
[0120] The sequence of device recapture and removal from a body
lumen (here the vena caval 1) is illustrated in FIGS. 72A-C. In
these figures, the solid lines are for a femoral recovery and the
phantom lines are for a jugular recovery (e.g., FIG. 70). A
collapsed snare is advanced via a delivery sheath to the proximity
of the retrieval feature 240 (FIG. 72A). Once in place, the snare
712 is exposed and assumes a pre-defined expanded loop shape which
is looped over the retrieval feature 240 as illustrated from either
end in FIG. 72B.
[0121] The snared device 100 can then be either pulled into the
sheath 710, or alternatively and more preferably, the recovery
sheath 710 is advanced over the device 100 while maintaining
positive control of the snare 712 as the sheath 710 advances over
the device 100. Advancing the recovery sheath 710 over the device
100 facilitates atraumatic removal of the device 100 from any
tissue that has grown in or around the device 100. The retrieval
action, which tends to collapse the device radially inward (FIG.
72D), also facilitates removal from any tissue layer formed on the
device. Recovering the filtering device by pulling on a flexible
retrieval feature attached to the filtering device. Moreover,
pulling on a portion of the filter structure (i.e., a retrieval
feature) removes the opposing spiral elements from the lumen
wall.
[0122] As the device is drawn into the sheath 710, the pre-formed
shape of the device also urges the support members away from the
lumen wall which also assists in atraumatic device removal.
[0123] The flexible retrieval element 240 assumes a collapsed
configuration as it is being drawn into the recovery sheath as
illustrated in FIG. 72C and FIG. 72E. Note that the retrieval
feature 240 on the opposite end of the device assumes a
straightened configuration as is drawn into the recovery sheath
(FIG. 72F). An additional embodiment, in which a single curved
retrieval feature 140 (FIG. 27A) is withdrawn into the delivery
sheath 710 as shown in FIG. 73A. The distal retrieval feature
(relative to the snare) assumes a straightened configuration FIG.
73C from a curved configuration FIG. 73B as is completely withdrawn
into the sheath FIG. 73D.
[0124] Additionally, repositioning the filter 100 from one lumen
position to another is illustrated in FIGS. 74A-74D. Because of the
atraumatic design of filter devices of the present invention,
repositioning of the filter device 100 may be accomplished by fully
recapturing (FIG. 74C) or only partially recapturing (FIG. 74B) the
device 100 into a recovery sheath 710. The atraumatic design of the
device 100 allows the device to simply secured by one end (FIG.
74B) and pulled along the lumen wall into the desired position and
then released. The delivery sheath and recovery sheath are provided
with the same reference numbers since filter devices of the present
invention may be deployed into and recovered from the vasculature
using sheaths that are about the same size. As such, devices of the
present invention may be deployed into the vasculature from a
delivery sheath having a first diameter. Then, the device may be
retrieved from the vasculature using a recovery sheath having a
second diameter no more than 2 Fr larger than the first diameter (1
Fr=0.013''=1/3 mm). Alternatively, the second diameter may be no
more than 1 Fr larger than the first diameter or, alternatively,
the first diameter is about the same as the second diameter.
[0125] In a full recovery, the device is pulled completely into a
recovery sheath (FIG. 74A), the sheath is repositioned from the
original position (FIGS. 74A, 74C) to a second position (FIG. 74D)
and deployed into the vasculature again (FIG. 69D). In the case
where the snare wire columnar strength is insufficient to redeploy
the device, the snare can be delivered within a secondary inner
sheath within the retrieval sheath. This allows the positive
control of the retrieval feature to be obtained, such as
illustrated in FIG. 74B, the device withdrawn into the retrieval
sheath and then redeployed with the inner sheath acting as a push
rod.
[0126] Various Methods of Using Filtering Devices
[0127] Embodiments of filter devices of the present invention may
be used in methods of providing distal protection in procedures
such as, for example, thrombectomy, arthrectomy, stenting,
angioplasty and stent grafting. It is to be appreciated that
embodiments of filter devices of the present invention may be used
in veins and arteries. An exemplary procedure is illustrated in
FIGS. 75A-I and FIGS. 76A-E. In each procedure, the device 100 is
positioned in an un-tethered fashion adjacent to the treatment
region 730. The sequence FIGS. 75A-I illustrate the delivery sheath
710 positioning FIG. 75A, complete deployment FIG. 75B into the
lumen 10. A conventional treatment device 750 using mechanical,
electrical energy or other suitable method is used to clear the
undesired material 732 from the lumen wall (FIG. 75C). Some debris
734 removed from the lumen wall through the use of treatment device
750 is subsequently embolized into the blood stream (FIG. 75C) and
trapped by the filter 100 (FIG. 75D). The conventional treatment
device 750 is removed (FIG. 75E) and thereafter the advancement of
recapture sheath 710 is advanced into recovery position (FIG.
75F).
[0128] The entrapped debris 734 is then removed prior to
recapturing the device with methods such as, for example,
aspiration, delivery of therapeutic agents or maceration.
Additionally, the device and entrapped debris can be recaptured in
whole and removed via the same sheath used to recapture the device
as illustrated in FIG. 75G. The device 100 and debris 734 are then
withdrawn into the sheath 710 (FIG. 75H), and the sheath withdrawn
from the vasculature (FIG. 75I).
[0129] Similarly, an additional use of the invention as un-tethered
distal protection is illustrated in FIGS. 76A-E, in which a balloon
751 is used to expand the lesion 732 such as in the case of balloon
angioplasty, often performed prior to stenting a vessel to keep it
open. For this procedure a balloon catheter is advanced to the
lesion site and inflated FIG. 76 B, plaque 732 is pushed outward by
the balloon (FIG. 76C), thus reestablishing normal blood flow. Any
particulate matter 734 embolized by the procedure is trapped by the
filter (FIG. 76D). The debris 734 can then be removed prior to
filter retrieval as previously described or the device with trapped
debris can be removed together.
[0130] An additional method practiced widely in the art is the use
of tethered distal protection adjunctive to the previously
described procedures (i.e., the device 100 remains tethered during
the procedure). Embodiments of the filtering device of the present
invention may also be used for this purpose as illustrated in FIGS.
77A-77E. Positive control of the filter 100 is maintained via an
integral wire or snare connected to the device 100. The connection
between the integral wire or snare to the device 100 is maintained
during the procedure and may be, in some embodiments, used as a
guidewire. As illustrated in FIG. 77B, connection to the device 100
is maintained a while performing a procedure to treat the
vasculature in proximity to the location (i.e, treat the lesion
732).
[0131] An example of a tethered distal protection method is
illustrated in FIGS. 77A-77E. An embodiment of a filter device 100
is deployed distal to the lesion 732 to be treated (FIG. 77A), the
treatment is initiated (FIG. 77B), and embolized material 734 is
captured in the filter 100 (FIG. 77C). Thereafter, the debris 734
is removed prior to filter recapture or, alternatively, with
treatment in the filter 100 via a sheath as previously described.
The device 100 is recovered into the sheath (FIG. 77D) and removed
from the lumen 10 (FIG. 77E).
[0132] A tethered device (FIGS. 77A, 78A) can also be employed to
mechanically dislodge and remove embolic material 732 from a vessel
10, such as in the case of a thrombectomy. This offers a simple
means of removing and trapping debris without requiring multiple
devices to achieve the same goal. For this method, the tethered
device is advanced downstream of the lesion site (FIG. 78A), and
deployed (FIG. 78B). The tethered, deployed filter 100 is then
drawn across the lesion 732 (FIG. 78C) to pull the thrombus from
the vessel wall and into the filter 100 (FIG. 78D). The embolized
material 734 is then removed via the methods previously described
(FIG. 78E), tethered device is drawn into the sheath and removed
from the lumen (FIG. 78F).
[0133] Delivery of Pharmacological Agents Using Filtering
Devices
[0134] Embodiments of the filter device of the present invention
may also be used for delivering a pharmacological agent within a
lumen. Delivery of the a pharmacological agent within a lumen may
be accomplished using any component of the filtering device. For
example, the filter support structure may deliver a pharmacological
agent. In one alternative, the support structure is covered by a
multi-lumen structure and the multi-lumen structure is configured
to release a pharmacological agent. In one alternative, a lumen of
the multi-lumen structure is at least partially filled with a
pharmacological agent. In another aspect, a lumen in a multi-lumen
structure has ports that allow for the release of a pharmacological
agent stored within the lumen. In one alternative, a cavity formed
in a support member is filled with a material. In one aspect, the
material in the cavity is a pharmacological agent. The filter may
deliver a pharmacological agent. In one aspect the material capture
structure is coated with a pharmacological agent.
[0135] Additional embodiments of the invention provide for the
ability to deliver therapeutic agents via the material capture
structure as well as the support structure covering. FIG. 79
illustrates a therapeutic agent coating 780 attached to a filament
118/461. FIG. 80 illustrates a composite structure 789 formed by
having one or more cavities formed in a support structure 105
filled with one or more therapeutic agents or other material. The
cavities may be formed as described above with regard to FIGS. 33,
35 and 36. These composite structures can be designed to elute a
therapeutic agent via a specific elution curve by varying
thickness, density as well as location of the therapeutic agent on
the filter device component. This therapeutic agent could be, for
example, any pharmacological agent used in the treatment of the
body, an anti-coagulant coating (i.e., Heparin), an agent prevent
or sloe fibrous tissue growth, other agents selected from those
used in vascular stents including drug eluting stents.
[0136] FIG. 81 and FIG. 82 illustrate the use of the covering 420,
420a positioned over a support structure as the delivery means for
providing pharmacological agents into a lumen. FIG. 81 illustrates
a pharmacological agent 782 in a lumen 424a of a multi-lumen
structure such as described above with regard to FIGS. 44, 45. As
illustrated in FIG. 82, the therapeutic agent 784 fills a lumen 424
in a multi-lumen covering 420a over the support structure 105.
Release ports 785 formed in the side of lumen 424 allow delivery of
the agent to the blood or tissue. Control of the therapeutic agent
elution parameters could be controlled via the size or spacing of
the release ports 785 and/or through the use of controlled release
pharmacological agents.
[0137] Prototype Filtering Devices
[0138] FIGS. 83A-83E illustrate perspective (FIG. 83A), plan (FIG.
83B), bottom (FIG. 83C), side (FIG. 83D) and end (FIG. 83E) views
of a prototype filter according to an embodiment of the present
invention. The prototype has previously described features and
common elements have the same reference numbers have been
incorporated into these illustrations. The support structure 105,
110 was formed with electropolished 0.013'' OD Nitinol wires, shape
set to form two substantially equal open loops 126, 128 of
approximately 1'' diameter. The support structure wire used for
support structure 105 was ground down to a wire diameter of 0.010''
and used to form flexible retrieval feature 240 on each end (i.e.,
FIG. 28C). An atraumatic feature (here ball 242) is created on the
end of the wire by exposing the wire to plasma. A radio opaque
marker, here a Tantalum marker band 248 attached below the ball
242. The material capture structure 115 has filter cells 119
constructed with filaments 118. The filaments 118 are 7-0 ePTFE
suture. The filaments are attached to the support structure using
method shown in FIG. 47. The cover 185 used to join the ends is a
tapered Nitinol tube 186 that is crimped around the support
structures, as illustrated in FIG. 24.
[0139] FIGS. 84A-84E illustrate perspective (FIG. 84A), plan (FIG.
84B), bottom (FIG. 84C), side (FIG. 84D) and end (FIG. 84E) views
of a prototype filter according to an embodiment of the present
invention. This embodiment is similar to the embodiment of FIG.
83A. In this embodiment, the material capture structure 115 is
replaced with material capture structure 312 an made of extruded
polymeric netting described above with regard to FIG. 56. This
embodiment also illustrates how the support structures 105, 110 are
not in contact (i.e., separated by a distance "d") at the crossover
106.
[0140] FIGS. 85A-85E illustrate perspective (FIG. 85A), plan (FIG.
85B), side (FIG. 85D) and end (FIG. 85C) views of a prototype
filter according to an embodiment of the present invention. This
embodiment is similar to the filter device described in FIG. 14A
and common reference numbers are used. In this embodiment, a
material capture structure is constructed from a continuous sheet
of polymeric material 520 into which circular holes 521 are created
via mechanical or laser cutting (as described above with regard to
FIG. 61A).
[0141] FIGS. 86A-86D illustrate perspective (FIG. 86A), plan (FIG.
86B), side (FIG. 86D) and end (FIG. 85C) views of a prototype
filter according to another embodiment of the present invention. In
this prototype filter, a material capture structure constructed
from a continuous sheet of polymeric material 520 into which a
pattern 522 voids are created via mechanical or laser cutting to
create a net-like structure (FIG. 61C).
[0142] FIG. 87 is a perspective view of a prototype filter
according to an embodiment of the present invention similar to the
embodiment described in FIGS. 83A-83E above. In this embodiment the
elongate structural members 105, 110 are joined at only one end
(i.e., end 102). The support structure elements on the unconnected
end are finished with plasma balls 242 to prevent vessel
perforation and facilitate deployment and retrieval.
[0143] Summary of Experimental Results
[0144] The inventors are currently evaluating the performance of
filter device embodiments of the present invention. Device
performance is currently being evaluated in ongoing in-vivo animal
and in-vitro bench studies. In particular, several device
performance attributes have been evaluated, such as: device loading
and advancement within a delivery sheath, deployment accuracy,
thrombus capturing ability, fluoroscopic visibility, positional
stability, device durability, and retrieval at three weeks
following implantation. For the animal work completed to date, an
ovine animal model has been used, as it is an accepted model used
to study vascular implants, with anatomy and healing response
similar to the adult human inferior vena cava (see, e.g., Brountzos
E, et. al. "A new optional vena cava filter: retrieval at 12 weeks
in an animal model", J Vasc Interv Radiol. 2003 June; 14(6):763-72;
Crochet D, et. al., "Evaluation of the LGM Vena-Tech infrarenal
vena cava filter in an ovine venous thromboembolism model", J Vasc
Interv Radiol. 2001 June; 12(6):739-45; and Smouse B.,
"Second-generation optional vena cava filter" Endovascular Today.
2005 January, 4(1): 64-66, each of which is incorporated herein by
reference in its entirety).
[0145] To date, thrombus trapping ability of the device has been
evaluated using an in-vitro model. This model is constructed using
segments of silicone "mock" vena cava connected to a flow circuit,
in which fluid is pumped at approximately 3 L/min and maintained at
20 mm/Hg. Results have confirmed device stability and the "wedging"
effect illustrated in FIG. 16A and FIG. 16B, when subjected to an
embolic load that substantially covers the filter surface.
[0146] Initial animal study feasibility experiments have
successfully demonstrated: [0147] (a) loading and advancement of
devices FIG. 68A in a compliant 6 Fr delivery sheath; [0148] (b)
compliance and positional stability of the device loaded in the
sheath as shown in FIG. 69B; [0149] (c) device visibility using
both intravascular ultrasound (IVUS) and fluoroscopy; [0150] (d)
deployment accuracy; [0151] (e) acute and sub-chronic positional
stability; [0152] (f) axial distensibility of the device (FIG.
2A-C); [0153] (g) ability to acutely capture and reposition device
(FIGS. 74A-D) using commercially available snares (FIGS. 71A-B);
[0154] (h) device durability; and [0155] (i) the ability to easily
recapture and remove a device after a three week dwell time using a
6 Fr sheath. The recapture was performed in less than 3 minutes
(FIGS. 72A-F). Recaptured devices have indicated freedom from
significant tissue incorporation or thrombus formation as well as
in-vivo device durability.
[0156] At present, ongoing animal studies will be used to evaluate
device performance and retrievability after one and two month
implant durations (i.e., vessel dwell times).
[0157] It is understood that this disclosure, in many respects, is
only illustrate of the numerous alternative filtering device
embodiments of the present invention. Changes may be made in the
details, particularly in matters of shape, size, material and
arrangement of various filtering device components without
exceeding the scope of the various embodiments of the invention.
Those skilled in the art will appreciate that the exemplary
embodiments and descriptions thereof are merely illustrative of the
invention as a whole. While several principles of the invention are
made clear in the exemplary embodiments described above, those
skilled in the art will appreciate that modifications of the
structure, arrangement, proportions, elements, materials and
methods of use, may be utilized in the practice of the invention,
and otherwise, which are particularly adapted to specific
environments and operative requirements without departing from the
scope of the invention.
* * * * *