U.S. patent application number 14/776518 was filed with the patent office on 2016-02-04 for filters with echogenic characteristics.
This patent application is currently assigned to VOLCANO CORPORATION. The applicant listed for this patent is VOLCANO CORPORATION. Invention is credited to Eric Johnson, Joseph Lauinger, Jeremy Stigall.
Application Number | 20160030151 14/776518 |
Document ID | / |
Family ID | 51581698 |
Filed Date | 2016-02-04 |
United States Patent
Application |
20160030151 |
Kind Code |
A1 |
Johnson; Eric ; et
al. |
February 4, 2016 |
FILTERS WITH ECHOGENIC CHARACTERISTICS
Abstract
There are described a variety of intravascular filters have
wherein at least a portion of the filter has been modified to
provide an enhanced echogenic characteristic of the filter.
Inventors: |
Johnson; Eric; (San Diego,
CA) ; Stigall; Jeremy; (San Diego, CA) ;
Lauinger; Joseph; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VOLCANO CORPORATION |
San Diego |
CA |
US |
|
|
Assignee: |
VOLCANO CORPORATION
San Diego
CA
|
Family ID: |
51581698 |
Appl. No.: |
14/776518 |
Filed: |
March 14, 2014 |
PCT Filed: |
March 14, 2014 |
PCT NO: |
PCT/US14/27259 |
371 Date: |
September 14, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61785204 |
Mar 14, 2013 |
|
|
|
Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61F 2002/018 20130101;
A61B 34/20 20160201; A61F 2/011 20200501; A61B 2090/3995 20160201;
A61F 2/01 20130101; A61B 90/39 20160201; A61F 2002/016 20130101;
A61B 2090/3784 20160201; A61B 2090/3966 20160201; A61B 90/96
20160201; A61F 2250/0096 20130101; A61F 2/013 20130101; A61B
2090/3925 20160201; A61B 8/0833 20130101 |
International
Class: |
A61F 2/01 20060101
A61F002/01; A61B 19/00 20060101 A61B019/00; A61B 8/08 20060101
A61B008/08 |
Claims
1. A filter, comprising: A hub; and A plurality of legs or wires or
segments extending from the hub; wherein at least a portion of the
hub or a portion of one or more of the legs or wires or segments is
modified to provide an enhanced echogenic characteristic of the
filter.
2. The filter of claim 1 wherein the modification to provide an
enhanced echogenic characteristic of the filter is a modification
to a portion of the filter to enhance the echogenic characteristics
of that portion of the filter.
3. The filter of claim 1 wherein the modification to provide an
enhanced echogenic characteristic of the filter is the formation of
dimples into a surface of the filter.
4. The filter of claim 3 wherein the dimples are of sufficient
number and scaled to a suitable size, shape, orientation and
pattern for use with an intravascular ultrasound system.
5. The filter of claim 1 wherein the modification to provide an
enhanced echogenic characteristic of the filter is the formation of
protrusions formed in, placed on or joined to a filter surface.
6. The filter of claim 5 wherein the protrusions are of sufficient
number and scaled to a suitable size, shape, orientation and
pattern for use with an intravascular ultrasound system.
7. The filter of claim 7 wherein the modification to provide an
enhanced echogenic characteristic of the filter is the roughening
one or more surfaces of a filter.
8. The filter of claim 8 wherein the roughening is performed using
a chemical process, a laser or bead blasting technique.
9. The filter of claim 7 wherein the roughening is of sufficient
scale to a suitable size, shape, orientation and pattern for use
with intravascular ultrasound systems.
10. The filter of claim 1 wherein the modification to provide an
enhanced echogenic characteristic of the filter is altering one or
more steps of a filter manufacturing technique to introduce
cavities, voids or pockets to locally modify or adapt one or more
acoustic reflection characteristics to improve echogenicity in one
or more specific regions of the filter.
11. The filter of claim 10 wherein the cavities, voids or pockets
are of sufficient number and scaled to a suitable size, shape,
orientation and pattern for use with an intravascular ultrasound
system.
12. The filter of claim 1 further comprising a separate material
capture structure that is attached to or supported by a portion of
the filter so as to enhance the filtering capabilities of the
filter.
13. The filter claim 1 further comprising at least one fixation
element wherein any portion of the tissue anchor or any portion of
one of the hub, the plurality of legs or wire or segments extending
from the hub is modified to provide an enhanced echogenic
characteristic of the filter related to the use, status, position
orientation of the at least one fixation element or the filter.
14. The filter of claim 1 the first and second support members, the
crossover and the first end or the second end of the first support
member, wherein any portion of one of the above is modified to
provide an enhanced echogenic characteristic of the filter related
to the use, status or of clot burden of the filter.
15. (canceled)
16. (canceled)
17. (canceled)
18. (canceled)
19. A filter delivery catheter adapted and configured to deliver a
filter according to claim 1, comprising: A delivery catheter
adapted and configured for delivery of an endoluminal filter; An
IVUS transducer integrated into the distal portion of the delivery
catheter; and One or more connectors on the proximal end of the
delivery catheter adapted and configured to connect the IVUS
transducer to an appropriate imaging or processing system.
20. (canceled)
21. (canceled)
22. The delivery catheter of claim 19 wherein the IVUS transducer
integrated into the distal portion of the delivery catheter is
adapted and configured whereby advancing and retracting the
delivery catheter generates a plurality of images slices from the
IVUS transducer.
23. The delivery catheter of claim 19 wherein the IVUS transducer
integrated into the distal portion of the delivery catheter is
adapted and configured whereby advancing and retracting the
delivery catheter can provide an output from the IVUS transducer
for positioning guidance of a filter delivered using the delivery
catheter.
24. The delivery catheter of claim 19 wherein the IVUS transducer
is integrated into the distal tip or end of the delivery
catheter.
25. The delivery catheter of claim 19 further comprising: a
pressure transducer.
26. The delivery catheter of claim 25 wherein the pressure
transducer is located proximal to the IVUS transducer.
27. (canceled)
28. (canceled)
29. (canceled)
30. (canceled)
31. (canceled)
32. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application No. 61/785,204, filed Mar. 14, 2013, which is herein
incorporated by reference in its entirety.
INCORPORATION BY REFERENCE
[0002] All publications and patents and patent applications
mentioned in this specification are herein incorporated by
reference to the same extent as if each individual publication or
patent or patent application was specifically and individually
indicated to be incorporated by reference.
FIELD
[0003] Aspects of the invention described herein relate generally
to filters inserted into a patient's body and more particularly to
the provision of echogenic coatings on such devices to enhance
their visibility using one or more of in any combination ultrasound
imaging, intravascular ultrasound imaging, greyscale intravascular
ultrasound imaging, color intravascular ultrasound imaging or
ultrasound image signal processing that included spectral
analysis.
BACKGROUND
[0004] Ultrasonic imaging in the medical field is widely used for a
variety of applications. In addition to imaging physiological
structures and tissue such as organs, tumors, vessels, and the
like, it is often desirable for a physician or technician to have
an image of a medical device which has been inserted into the
tissue or passageway of a patient. Still further, advancements in
the use of intravascular or intraluminal imaging ultrasound
(positioned either within or outside of the body) before, during
and after procedures has led to increasing requirements for
cooperation between device and imaging modality.
[0005] A variety of approaches have been used to enhance ultrasonic
imaging of devices by increasing the acoustic reflection
coefficient of the devices. While echogenic materials have been
described for some uses in medical devices, the conventional uses
of echogenic materials has not kept pace with the advancements in
applications for imaging ultrasound. Moreover, while many
approaches have been attempted, there is still need for
improvements that are particular to the use of specific device
designs. In particular, as medical therapies and procedures
continue to advance, there is, in many medical instances, a need
for more specific information about a device, its placement,
position, orientation or aspect in relation to another object. What
is needed are further improvements to the manner and placement of
echogenic enhancements to obtain these additional benefits.
SUMMARY OF THE DISCLOSURE
[0006] In general, in one embodiment, a filter includes a hub; and
a plurality of legs or wires or segments extending from the hub;
wherein at least a portion of the hub or a portion of one or more
of the legs or wires or segments is modified to provide an enhanced
echogenic characteristic of the filter.
[0007] This and other embodiments include one or more of the
following features. In one aspect, the modification can provide an
enhanced echogenic characteristic of the filter is a modification
to a portion of the filter to enhance the echogenic characteristics
of that portion of the filter. In another aspect, the modification
can provide an enhanced echogenic characteristic of the filter
which can be the formation of dimples into a surface of the filter.
In yet another aspect, the dimples can be of sufficient number and
scaled to a suitable size, shape, orientation and pattern for use
with an intravascular ultrasound system. In a further aspect, the
modification can provide an enhanced echogenic characteristic of
the filter which can be the formation of protrusions formed in,
placed on or joined to a filter surface. In an additional aspect,
the protrusions can be of sufficient number and scaled to a
suitable size, shape, orientation and pattern for use with an
intravascular ultrasound system. In another aspect, the
modification can provide an enhanced echogenic characteristic of
the filter including the roughening one or more surfaces of a
filter. In yet another aspect, the roughening can be performed
using a chemical process, a laser or bead blasting technique. In
still a further aspect, the roughening can be of sufficient scale
to a suitable size, shape, orientation and pattern for use with
intravascular ultrasound systems. In a further aspect, the
modification can provide an enhanced echogenic characteristic of
the filter including altering one or more steps of a filter
manufacturing technique to introduce cavities, voids or pockets to
locally modify or adapt one or more acoustic reflection
characteristics to improve echogenicity in one or more specific
regions of the filter. In an additional aspect, the cavities, voids
or pockets can be of sufficient number and scaled to a suitable
size, shape, orientation and pattern for use with an intravascular
ultrasound system.
[0008] This and other embodiments include one or more of the
following features. In one aspect, the filter can further include
at least one fixation element. Any portion of the tissue anchor or
any portion of one of the hub, the plurality of legs or wire or
segments extending from the hub can be modified to provide an
enhanced echogenic characteristic of the filter related to the use,
status, position orientation of the at least one fixation element
or the filter. In another aspect, the first and second support
members, the crossover and the first end or the second end of the
first support member, any portion of one of the above can be
modified to provide an enhanced echogenic characteristic of the
filter related to the use, status or of clot burden of the filter.
In a further aspect, a method of positioning a filter within a
lumen can include advancing a sheath containing a filter through
the lumen, deploying a portion of the filter from the sheath into
the lumen while maintaining a portion of the filter within the
sheath, either of the above steps can be performed before or after
using imaging from an intravascular ultrasound system. In an
alternative aspect, a method of deploying a filter within a lumen
can include advancing a sheath containing the filter through the
lumen; and deploying the filter into the lumen, wherein, either
step can be initiated, performed, confirmed or completed at least
in part based on information obtained using intravascular
ultrasound from one or more echogenic aspects of the filter. In yet
another aspect, the method can further include maneuvering a snare
towards the filter in a direction to retrieve the filter and
engaging the snare with the filter. The maneuvering step or the
engaging step can be initiated, performed, confirmed or completed
at least in part based on information obtained using intravascular
ultrasound from one or more echogenic aspects of the filter. In
still another aspect, the method can further include engaging the
lumen wall with a fixation element attached to the filter. This
step can be initiated, performed, confirmed or completed at least
in part based on information obtained using intravascular
ultrasound from one or more echogenic aspects of the filter. In one
aspect, a filter delivery catheter can be adapted and configured to
deliver a filter according to any of the previously mentioned
embodiments. A delivery catheter can be adapted and configured for
delivery of an endoluminal filter, an IVUS transducer can be
integrated into the distal portion of the delivery catheter, and
one or more connectors on the proximal end of the delivery catheter
can be adapted and configured to connect the IVUS transducer to an
appropriate imaging or processing system. In another aspect, the
filter delivery catheter can further include a telescoping sleeve
within an moveable relative to the filter delivery catheter. In yet
another aspect, the filter delivery catheter can further include a
pusher rod within a moveable relative to the filter delivery
catheter. In still another aspect, the IVUS transducer integrated
into the distal portion of the delivery catheter can be adapted and
configured whereby advancing and retracting the delivery catheter
generates a plurality of images slices from the IVUS transducer. In
a further aspect, the IVUS transducer integrated into the distal
portion of the delivery catheter can be adapted and configured
whereby advancing and retracting the delivery catheter can provide
an output from the IVUS transducer for positioning guidance of a
filter delivered using the delivery catheter. Is an alternative
aspect, the IVUS transducer can be integrated into the distal tip
or end of the delivery catheter. In yet another aspect, the
delivery catheter can further include a pressure transducer. In
still another aspect, the pressure transducer can be located
proximal to the IVUS transducer. In one aspect, the delivery
catheter can further include a filter as in any of the previously
mentioned embodiments within the delivery catheter. In another
aspect, a method of positioning a filter within a lumen can include
advancing a delivery catheter according to any of the previously
mentioned embodiments and can contain a filter as in any of the
previously mentioned embodiments through the lumen using imaging
information provided by the IVUS transducer on the delivery
catheter to determine relative position before deploying a portion
of the filter from the delivery catheter into the lumen to engage
the lumen wall. In yet another aspect, the method can further
include obtaining IVUS imaging of the lumen using the delivery
catheter prior to deployment of the filter, after the deployment of
the filter or during the deployment of the filter. In still another
aspect, the method can further include obtaining IVUS imaging of
the lumen using the delivery catheter for imaging a deployment
location and estimating the sizing of a filter for the deployment
location prior to performing any of the previously mentioned
methods. In a further aspect, the method can further include
estimating treatment duration using imaging data collected as in
any of the previously mentioned methods. In an alternative aspect,
a filter can further include an IVUS transducer integrated into the
filter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] A better understanding of the features and advantages of the
present invention will be obtained by reference to the following
detailed description that sets forth illustrative embodiments, in
which the principles of the invention are utilized, and the
accompanying drawings of which:
[0010] FIG. 1 is a section view of a wire strut or support element
of a filter (w/s/s) having multiple segments in a concentric
arrangement.
[0011] FIG. 2 is an embodiment of a segment having one or a
plurality of laser drilled holes formed therein.
[0012] FIG. 3 is an embodiment of a segment having one or a
plurality of raised features or alternatively roughed portions
formed thereon.
[0013] FIG. 4 is an embodiment of a segment having one or a
plurality of bubbles formed therein.
[0014] FIG. 5 is an embodiment of a segment having one or a
plurality of dimples formed therein.
[0015] FIG. 6 is an embodiment of a segment having a coil or
braided structure within or about the segment.
[0016] FIG. 7 is an embodiment of a segment having a plurality of
echogenic markers arrayed in rings about the segment to provide an
indication of measurement via the spacing between adjacent
rings.
[0017] FIG. 8 illustrates various alternative configurations for a
segment used alone or in conjunction with other segments.
[0018] FIG. 9 is a view of an exemplary filter illustrating various
alternative aspects of providing a filter with improved echogenic
characteristics.
[0019] FIG. 10 is an end view of the filter as it appears looking
toward the apical hub forming a part of the filter.
[0020] FIG. 11 is a sectional view through the center of the apical
hub forming a part of the filter, and illustrating the manner in
which the legs of the filter are positioned in the apical hub and
are retained therein.
[0021] FIG. 12 is a side view of an embodiment of the blood clot
filtration device.
[0022] FIG. 13 is a perspective view of a vena cava filter
embodiment showing the head and legs thereof.
[0023] FIG. 14 is a perspective view of a vena cava filter showing
the head and legs thereof.
[0024] FIG. 15 is a perspective view of a thrombus filter.
[0025] FIG. 16 is a plan view of the anchor portion of a thrombus
filter.
[0026] FIG. 17 is a schematic representation of a removal process
for use with a thrombus filter.
[0027] FIG. 18 is a schematic representation of a thrombus filter
drawn into the lumen of a removal catheter.
[0028] FIG. 19 is a fragmentary elevation view of the blood clot
filter embodiment in a totally straightened position.
[0029] FIG. 20 is an elevation view of the blood clot filter in a
partially straightened position.
[0030] FIG. 21 is a perspective view of a portion of the inferior
vena cava and having a section removed to show the configuration of
the blood clot filter in its implanted and anchored position within
the inferior vena cava.
[0031] FIG. 22 is a perspective view of an alternative blood clot
filter having two V-shaped struts and a tangle of fine wires.
[0032] FIG. 23 is a view of a filter in place in a vein.
[0033] FIG. 24 is a side view of a blood clot filter.
[0034] FIG. 25 is an embodiment of a filter in its unfolded
state.
[0035] FIG. 26 is a side of the filter in an expanded position.
[0036] FIG. 27 is a view illustrating the filter by chain dot lines
in a collapsed condition.
[0037] FIG. 28 shows schematically in perspective a filter its
unfolded state.
[0038] FIG. 29 is an isometric view of a filter.
[0039] FIG. 30 is an elevation of a vena cava filter shown in its
fully expanded state.
[0040] FIG. 31 illustrates an embodiment of a filter, seen in
perspective.
[0041] FIG. 32 is a perspective view of a filter device, placed in
position in a vein.
[0042] FIG. 33 is an isometric view of an embodiment of an embolus
trap.
[0043] FIGS. 34A-34C illustrate an example of a guidewire having
both a pressure sensor and an IVUS transducer located at the distal
portion of the guidewire.
[0044] FIGS. 35A-35D illustrate two embodiments of an intravascular
ultrasound catheter joined together in parallel with a
catheter.
[0045] FIGS. 36A and 36B, the pressure sensor and/or IVUS
transducer are integrated into a delivery catheter, a retrieval
catheter or a device itself.
DETAILED DESCRIPTION
[0046] Filters are more complex structures in contrast to the
relatively simple designs found in catheters and needles. In a more
complex device like a filter there is a need to identify specific
portions within the device during some medical procedures. In
addition, it would be advantageous as well to determine the
orientation of the device including components within the device to
one another (as used for determining deployment, retrieval and the
various intermediate stages thereof) as well as the overall filter
orientation to the surrounding lumen or vessel. In contrast to the
conventional techniques using location of the tip or start or end
of the entire length, a more complex structure such as a filter
position, orientation or relative placement information would yield
specific benefits. In some cases, aspects, portions or attributes
of the overall filter or filter components or portions will enable
more useful determinations about the filter in relation to the
physiological environment. In one aspect, an intravascular
ultrasound (IVUS) catheter and processing system or signal
processing algorithm is used to confirm filter sizing selection,
guidance for filter placement, filter implantation steps, filter
and/or vessel measuring using IVUS before during and/or after steps
to confirm sizing selection and fit is appropriate under the
physiologic environment and for confirmation and/or documentation
of proper sizing selection, placement, engagement or degree of
engagement of fixation elements (if present), clot burden,
orientation and/or deployment in a patient or physician medical
record.
[0047] In one aspect, embodiments of the present invention are
directed toward medical devices having a complex shape or that are
configured to move from stowed to deployed configurations that may
also have specific orientation and placement criteria for proper
use in a lumen, vessel or hollow organ. One such complex device is
an IVC filter. Aspects of the present invention include such
devices employed within the human body which have enhanced
ultrasound visibility by virtue of incorporation of an echogenic
material using any of the techniques described herein alone or in
any combination.
[0048] In one aspect, there are described herein various
alternative filter designs for increasing the echogenicity of the
filter. A filter with enhanced echogenic characteristics may
include one or more than one of: (a) a modification to one or more
components of the filter to enhance the echogenic characteristics
of the component; (b) formation of dimples into a component surface
of sufficient number and scaled to a suitable size, shape,
orientation and pattern for use with intravascular ultrasound
systems; (c) protrusions formed in, placed on or joined to a filter
surface; (d) roughening one or more surfaces of a filter, for
example using a chemical process, a laser or bead blasting
technique; and (e) altering one or more steps of a filter
manufacturing technique to introduce cavities, voids or pockets to
locally modify or adapt one or more acoustic reflection
characteristics to improve echogenicity in one or more specific
regions of a filter. One example of the manufacturing alteration is
to introduce gaps between the segments of tubing or coverings
whereby the gap provides the echogenic enhancement. In addition,
cavities, voids, pockets, dimples, gaps and the like may be left
empty or, optionally, filed, partially filed or lined with any of
the echogenic materials described herein.
[0049] In one aspect, there are provided embodiments of a filter
having enhanced echogenic characteristics in or related to at least
one or a portion of: an proximal end, a distal end, a terminal
proximal end, a terminal distal end, a retrieval feature, an
atraumatic tip on a retrieval feature, a mid-strut region, a leg or
strut portion having at least one orientation attribute to another
portion of the filter, an indicia of a location of a fixation
element or a retrieval feature, a location on a portion of the
filter selected such that in use with a particular fixation element
the marker in a location that indicates that the fixation element
is fully deployed into a wall of a lumen or portion of a vessel or
hollow organ (i.e., the marker is against the lumen wall or nearly
so when the fixation element is fully engaged. As such, see the
marker against the wall indicates proper deployment, spaced from or
not visible would indicate, respectively, not fully engaged or over
penetration); a portion of the distal tip and/or an elongated
portion. The above described methods may also be applied to the
other techniques and alternatives described herein.
[0050] In still further embodiments, a portion, component or aspect
of an intraluminal filter may have enhanced echogenic attributes by
applying a coating or sleeve containing one or more of the
echogenic materials disclosed herein or fabricated according to any
of the techniques or having any of the attributes to enhance
echogenic qualities as described herein. In some aspects, the
enhanced echogenic attributes are provided by the incorporation
into, application onto or within a component or portion of a filter
one or more echogenic materials or echogenic markers in a specific
configuration, location, orientation or pattern on the filter.
[0051] Enhanced echogenic markers or locations may be devised and
placed for use individually or in combinations such as to
facilitate the identification to an IVUS system or ultrasound
imaging modality an indication or signature for a specific location
on a filter, such as, for example, a retrieval feature, a terminal
proximal end, a terminal distal end, a location of a fixation
element or a location of some other indicia that identifies a
specific aspect of a particular filter design. In addition or
alternatively, two or more enhanced echogenic markers or portions
may be used in combination to provide additional information about
a filter such as orientation with in a vessel, confirmation of
deployment or a portion of a deployment sequence, confirmation of
final placement, confirmation of migration or lack of migration,
confirmation of retrieval or progress in a retrieval sequence and
the like according to the various processes and used for filters
within the vasculature or in lumens of the body. In another
specific embodiment, the use of IVUS techniques with embodiment of
the echogenic enhanced filters describe herein may also be used to
measure the diameter of the vessel at specific device locations
indicated by the echogenic markers during or after deployment or
retrieval of a filter.
[0052] In still further aspects, the use of IVUS techniques with
embodiment of the echogenic enhanced filters describe herein may
also be used to determine, detect or indicate inadequate dilation,
adequate dilation, filter expansion, degree of filter expansion,
filter-vessel engagement and degree or engagement, strut/leg/anchor
position and other attributes relating to the interaction between
the filter and the surrounding physiological environment.
[0053] Still further, the echogenic markers are positioned with
regard to the likely or planned positioning of the IVUS transducer
and/or likely pathways for acoustic energy used by the imaging
system. By way of example, if the IVUS transducer is forward
looking, then those forward looking aspects of the filter will be
provided with the enhanced echogenic aspects. In another example,
if the IVUS transducer is cylindrically shaped and will be
positioned through the interior portion of a filter then the filter
will be provided with enhanced echogenic aspects on interior
surfaces or portions that would receive acoustic energy from such
as transducer in such a position. Other modifications are within
the scope of the invention based on the particular style of IVUS
transducer used, the position relative to the filter and the
placement and type of echogenic feature incorporated into the
filter. Put another way, the echogenic enhancements of the filters
described herein are selected, designed and positioned on the
filter with regard to the IVUS sensor type, acquisition mode and
position relative to the filter. Additional details in the use of
IVUS with filters is further described in U.S. Pat. Nos. 6,645,152
and 6,440,077, both of which are incorporated herein by reference
in their entirety for all purposes.
[0054] In one aspect, the placement and signature of such enhanced
echogenic markers are discernible to a human user viewing an
ultrasound output alone or in combination with being discernible to
a computer system configured for the processing of an ultrasound
return including a return from the enhanced echogenic filter.
[0055] In various alternatives, the echogenic material may either
be applied to a portion of or a component of a filter in any of a
number of different techniques.
[0056] In one example, an echogenic component or additive is
applied to or incorporated into a filter or portion of a filter as
a selective coating applied to a portion or component of a
filter.
[0057] In one example, an echogenic component or additive is
applied to or incorporated into a filter or portion of a filter as
a mold formed to be placed over or joined to a portion of component
of a filter.
[0058] In one example, an echogenic component or additive is
applied to or incorporated into a filter or portion of a filter as
an extruded sleeve formed in a continuous segment to cover a
portion or component of a filter. In one embodiment, one of the
inner tubular member or the outer sleeve or coating may be
fabricated of a material according to the present invention, having
increased echogenicity, with the other of the inner tubular member
fabricated of a biocompatible polymer such as polyurethane or
silicone rubber, for example.
[0059] In one example, an echogenic component or additive is
applied to or incorporated into a filter or portion of a filter as
a compound or two layer structure comprising an inner tube and an
outer tube or sleeve with one or both of the tubes made from or
including or incorporating one or more echogenic materials or
modifications as described herein. In addition or alternatively one
or both sleeves, tubes described herein may include or encapsulate
an echogenic marker or component of specific shape or geometry, for
example, as in the case of a tube structure having within the
sidewall of the tubing a coiled structure. In one aspect, the
coiled structure is made from an echogenic material and the
windings are provided in a manner that is useful in any of the
aspects of the filter described herein. The coil may have a
particular size or variation in size, pitch or variation in pitch
or other attribute useful in providing an echo identifiable aspect
of the filter property being determined. In one specific
embodiment, the dimensions of the coil or other echogenic material
has dimensions selected for increasing acoustic reflection with
regard to the resolution or processing algorithms used in the
imaging ultrasound system.
[0060] In one example, an echogenic component or additive is
applied to or incorporated into a filter or portion of a filter as
a braided structure incorporated into a compound or two layer
structure comprising an inner tube and an outer tube or sleeve with
one or both of the tubes made from or including or incorporating
one or more braid comprising echogenic materials or modifications
as described herein. In addition or alternatively one or both
sleeves, tubes described herein may include or encapsulate an braid
formed into an echogenic marker or component of specific shape or
geometry, for example, as in the case of a tube structure having
within the sidewall of the tubing a braided structure. In one
aspect, the braided structure is made from an echogenic material
and the braided is a small diameter that is when wound around the
tubes or sleeve or directly onto a portion of or component of a
filter. The winding pattern and spacing of the braided materials
are provided in a manner that is useful in any of the aspects of
the filter described herein. The braid may have a particular braid
strand composition, structure, size or variation in size, pitch or
variation in pitch or other attribute useful in providing an echo
identifiable aspect of the filter property being determined. One or
more of the strands in the braid may be formed from an echogenic
material. One or more of the strands may be formed from a material
having improved radiopaque characteristic. One or more of the
strands may be formed from a material having both echogenic and
radiopaque properties. The strands of a braid may be combined using
any of the above described strand characteristics.
[0061] In another alternative, in still another example, an
echogenic component or additive is applied to or incorporated into
a filter or portion of a filter as the a series of short segments
placed adjacent to one another along a portion or component of a
filter in either a close packed or spaced arrangement. In another
embodiment, the spacing or voids between adjacent segments may also
be adjusted or selected so as to enhance echogenic capabilities of
the filter using the material difference introduced by the spacings
or voids.
[0062] In another alternative, in still another example, an
echogenic component or additive is applied to or incorporated into
a filter or portion of a filter as a tubing or sleeve suited to
heat shrink operations. In one aspect, there is a manufacturing or
assembly steps of sliding one or more sleeves over portion of the
filter then apply heat to shrink down the segment about the portion
of the filter. In particular, various embodiments provide for the
specific placement of such a shrink fit tubing having enhanced
echogenic characteristics as described herein. It is to be
appreciated that the sleeves, segment or tubes may be provided from
or have echogenic modifications or elements incorporated into
suitable materials such as, for example, ePTFE, PTFe, PET, PVDF,
PFA, FEP and other suitable polymers. Still further, these and
other materials may be formed in shapes other than tubes but may
also take the form of strands, lines, fibers and filaments to be
applied in accordance with the echogenic enhancement techniques
described herein. In some embodiments, the tubes or segments
applied to a filter may have the same or different composition as
well as have the same width or different widths. In one aspect, the
width or thickness of a plurality of bands is used to provide a
code or information about the filter. The use of echogenic bands of
different widths is a marking technique similar to the way that
different size and color rings on a resistor are arranged in a
pattern to describe the resistor's value.
[0063] In another alternative, in still another example, an
echogenic component or additive is applied to or incorporated into
a filter or portion of a filter is extruded over a portion of or a
component of the filter.
[0064] In another alternative, in still another example, an
echogenic component or additive is applied to or incorporated into
a filter or portion of a filter is by bonding an echogenic material
or components to the filter using a suitable adhesive or bonding
technique.
[0065] In any of the above described configurations, the portion or
component of the filter may be modified with dimples, grooves,
pockets, voids. In other aspects, there may be one or more full or
partial circumferential recesses, rings, surface diffraction
gratings or other surface features to selectively enhance or
provide an echogenic property in that portion of the filter, to aid
in or foster the application of the echogenic materials. In still
further aspects, any of above described surface modifications may
also be used to uniquely identify a portion of a filter or any of
the above in any combination.
[0066] In still further aspects of any of the above echogenic
markers or attributes the thickness of the sleeve or coating or
component may decrease at its proximal and distal ends to provide
for a smooth outer surface. As yet an additional alternative, a
coating, marker or other echogenic material may extend proximally
to or closely adjacent to the distal end or the distal end or both
of the filter component or filtering device.
[0067] In still other alternatives or combinations, some filter
design embodiments alter components of the filter to enhance
echogenicity such as, for example, material selection to
incorporate echogenic materials. Examples of echogenic materials
include palladium, palladium-iridium or other alloys of echogenic
materials.
[0068] In some embodiments, echogenic microbubbles are provided in
a portion of a filter to enhance the acoustic reflections of that
aspect of the filter. Echogenic microbubbles may be prepared by any
convenient means and introduced into the component or portion
thereof or by a coating or sleeve or shell or other transferring
means or mixed with a polymer or other suitable base compound prior
to extension of extrusion, molding casting or other technique. The
echogenic microbubbles may be pre-prepared or prepared inside the
component or element or marker as appropriate. Aspects of the
preparation or use of microbubbles are described in U.S. Pat. Nos.
5,327,891; 4,265,251; 4,442,843; 4,466,442; 4,276,885; 4,572,203;
4,718,433 and 4,442,843. By way of example, echogenic microbubbles
can be obtained by introducing a gas, e.g. carbon dioxide, into a
viscous sugar solution at a temperature above the crystallization
temperature of the sugar, followed by cooling and entrapment of the
gas in the sugar crystals. Microbubbles can be formed in gelatin
and introduced into a component or portion of a device.
Microbubbles can also be produced by mixing a surfactant, viscous
liquid and gas bubbles or gas forming compound, e.g. carbonic acid
salt, under conditions where microbubbles are formed.
[0069] In still further alternatives, there is also the
incorporation of dual mode materials (radiopaque and echogenic)
into a polymer then used to form part of, be applied or otherwise
incorporated with a filter device as described herein. Some of
these polymer compounds may be fabricated to enhance aging and
shelf life and have other beneficial attributes. In one aspect, a
filter or portion thereof includes one or more selected segments
that are constructed using visibility materials compounded with one
or more polymeric materials that make the selected segments visible
using both fluoroscopy and ultrasonic imaging. In one specific
example, the visibility material may take the form of tungsten
and/or tungsten carbide particles dispersed within a polymeric
material. In one specific aspect, the radiopaque and echogenic
material includes tungsten and/or tungsten carbide particles
distributed within a base polymeric material.
[0070] In one embodiment, a portion of or a component of a filter
includes or has been modified to have an inner layer including a
radiopaque and echogenic material. In one alternative, the
radiopaque and echo genic material includes particles distributed
within a base polymeric material (i.e., a first polymeric material)
including a polyether block amide; and an outer layer including an
additional polymeric material (i.e., a second polymeric material).
In certain embodiments, the additional polymeric material is a
thermoplastic elastomer. Optionally, the additional polymeric
material is more resistant to hydrolysis and/or oxidation than the
base polymeric material.
[0071] In still further aspects, a component, a portion or an
element added to a filter may be regarded as an echogenic body
member that is a part of an echogenic filter to be sonically
imaged. The echogenic body member is at least partially made up of
a composite material which is echogenically imagable in the
patient, such as by the use of ultrasonic imaging equipment used
either within the patient or external to the patient. In one
aspect, a composite material includes matrix material with discrete
acoustic reflective particles embedded in matrix material. In one
aspect, the matrix material is a biocompatible plastic. Examples of
suitable plastics may include urethane, ethylene, silicone,
polyethylene, tetrafluorethylene. In one aspect, a matrix is a
formable, pliable material which may be molded and/or extruded to a
variety of shapes, depending upon a specific application. The sound
reflective particles are embedded in matrix material. Particles
are, by way of example, made of a hard material, such as small
glass particles that are solid or filled with an acoustically
reflective medium. In one aspect, glass particles having a
generally spherical shape forming glass microspheres. Glass
microspheres with an outer diameter of about 5 microns is one
acceptable size. Other sized particles may be utilized as, for
example, ranging between 1 and 50 microns and beyond. Particles
sized below the resolution size of the imaging ultrasound system in
use may be arranged into patterns of sufficient size and
orientation to the acoustic waves that result in a discernible
feature by the imaging ultrasound system. Furthermore, the
particles do not necessarily have to be spherical, or may be
partially spherical. Still further, the shape of the particle could
be altered to enhance acoustic reflection by presenting different
shapes of particles, sizes of particles and combinations thereof to
modify acoustic characteristics of the matrix material. By way of
example, the particles may be shaped into an "Ordered array."
"Ordered arrays" can take the form of a macrostructure from
individual parts that may be patterned or unpatterned in the form
of spheres, colloids, beads, ovals, squares, rectangles, fibers,
wires, rods, shells, thin films, or planar surface. In contrast, a
"disordered array" lacks substantial macrostructure.
[0072] By way of example, an echogenic marker may comprise
particles that individually are below the resolution of the imaging
ultrasound system. The echogenic marker is the combination of these
below imaging ultrasound resolution particles in combination, in
1D, 2D or 3D patterns, in graphic arrays, or in machine readable
combinations to make a signature. Based on the specific
characteristics of the combination of particles, the acoustic
returns from an echogenic marker or combination of echogenic
markers may be visually perceptible in a display for interpretation
by a user or may be detected and interpreted by one or more
acoustic reflection or spectral processing algorithms within a
imaging ultrasound processing system.
[0073] In one aspect, the echogenic material is fabricated by
incorporating nanometer sized particles of sonically reflective
materials, for example iron oxide, titanium oxide or zinc oxide
into a biocompatible polymer. In one method of fabrication, the
acoustically reflective particles are mixed with a powdered
thermoplastic or thermosetting material such as a polyether amide,
a polyurethane or an epoxy, or polyvinylchloride followed by
thermal processing of the mixture to provide a material of
increased sonic reflectance which may be applied as a coating on
medical devices of the type discussed above or may be incorporated
as a structural component of the medical devices as described
herein.
[0074] In still further embodiments and aspects, the particles
included to provide echogenic enhancements may be selected,
arranged or incorporated to provide acoustically geometrically
tuned nanostructures, microstructures or macrostructures. The
particles provided herein are formable in all shapes currently
known or to be created for acoustic reflection enhancement. In
non-limiting examples, the nano-, micro- or macro-particles are
shaped as spheres, ovals, cylinders, squares, rectangles, rods,
stars, tubes, pyramids, stars, prisms, triangles, branches, plates
or comprised of an acoustically reflective surface or where one or
more surfaces is adapted such as by roughening or dimpling or other
technique used to alter acoustic reflection properties. In
non-limiting examples, the particles comprise shapes and properties
such as plates, solid shells, hollow shells, rods, rice shaped,
spheres, fibers, wires, pyramids, prisms, or a combination
thereof.
[0075] In one specific aspect, a partially spherical surface may be
provided on the outside and/or the inside of particles, as for
example a particle with a hollow spherical space therein. Particles
are made up of a different material than the matrix. While desiring
not to be bound by theory, it is believed that a spherical shape
provides for sound reflections at a variety of angles regardless of
the direction from which the ultrasonic sound waves are emanating
from, and accordingly, are more likely to reflect at least a
portion of the transmitted signal back to the ultrasonic receiver
to generate an image. Since many of matrix materials available are
relatively ultrasonically transparent in a patient, sound
reflective particles provide adequate reflection. The use of a
composite, rather than a solution, provides adequate size for
acoustic reflection off of the discrete particles embedded in the
matrix. As indicated, a variety of materials may be utilized for
the sound reflective particles, such as aluminum, hard plastic
ceramics, and, metal and/or metal alloys particles, and the like.
Additionally, liquids, gases, gels, microencapsulants, and/or
suspensions in the matrix may alternatively be used either alone or
in combination, so long as they form a composite with the desired
ultrasonically reflective characteristic.
[0076] Any of the above embodiments, alternatives or filter
modifications to enhance echogenic characteristics may also be
designed or implemented in such a way as to provide an echogenic
identifiable or unique trait or acoustic reflection signature that
may be registered by a human operator looking at a display or
identified using signal processing techniques of a return
containing acoustic reflections from the filter in an imaging
ultrasound system. In one example, there is a surface of the filter
having one or more echo registerable or identifiable feature, mark
or indication in a position useful for determining one or more of:
a location of an end of a filter; a location of a fixation element
on a filter; a location of a retrieval feature on a filter; an
orientation of one or more of a leg, a strut, a filter or an end of
a filter relative to another of a leg, a strut, a filter or an end
or the orientation of the overall filter to a lumen, vessel or
hollow organ in a body. Moreover, in another widely applicable
aspect of providing enhanced imaging characteristics to a filter as
described herein, the characteristic or modification--however added
or incorporated into the filter--enable a filter, a filter
component or a specified portion of a filter to be more readily
imaged by intravascular ultrasound as described herein. In still
another aspect, the characteristics or modification to the filter
are oriented and positioned in order to facilitate IVUS imaging via
an IVUS probe borne by a filter deployment or retrieval catheter,
snare, or other implement provided to facilitate the use of
intravascular filters.
[0077] FIG. 1 is a section view of a wire strut or support element
of a filter (w/s/s) having multiple segments in a concentric
arrangement. In this illustrative embodiment, the wire is encased
in alternating tube segments. There is an inner tube (IT) directly
adjacent to the wire. There is an echogenic segment layer (EL)
adjacent to the inner layer. The inner tube may be selected to act
as bonding layer to increase adhesion between the echogenic layer
and the filter wire, strut or support member. In this embodiment,
there is an outer tube (OT) over the echogenic layer. In
alternative configurations, either or both of the inner tube or the
outer tube may be omitted. The echogenic layer is a segment having
one or more of the echogenic characteristics described herein.
[0078] FIGS. 2-7 provide various exemplary embodiments of a segment
87 having one or a plurality of one or more than one type of
echogenic characteristic, property or feature added thereto. Each
of the illustrated echogenic adaptations applied to segment 87
along with segment 87 itself may be sized, scaled and/or shaped as
described herein as needed based upon the requirements of the
portion of the filter and the echogenic characteristic.
[0079] FIG. 2 is an embodiment of a segment 87 having one or a
plurality of laser drilled holes 88 formed therein. The diameter
and the shape of the holes may be selected based upon the size of
the filter or filter component to which the segment 87 will be
attached. The holes 88 may be completely through the wall of the
segment or only partially through the wall. The holes 88 may be
formed in any pattern, spacing or orientation as described
herein.
[0080] FIG. 3 is an embodiment of a segment 87 having one or a
plurality of raised features or alternatively roughed portions 89
formed thereon. The size and shape of the raised features or the
roughness of the surface may be selected based upon the size of the
filter or filter component to which the segment 87 will be
attached. The raised features or portions of roughness 89 may be
formed in any pattern, spacing or orientation as described
herein.
[0081] FIG. 4 is an embodiment of a segment 87 having one or a
plurality of bubbles 90 formed therein. The size, shape, pattern,
and manner of incorporating one bubble 90 or a plurality of bubbles
90 into the segment 87 may be selected based upon the size of the
filter or filter component to which the segment 87 will be
attached. The bubbles 90 may be formed within the segment sidewall,
near the surface of the segment sidewall or near the inner surface
of the sidewall. The bubble or bubbles 90 may be formed in any
pattern, spacing or orientation as described herein.
[0082] FIG. 5 is an embodiment of a segment 87 having one or a
plurality of dimples 91 formed therein. The diameter and the shape
of the dimples may be selected based upon the size of the filter or
filter component to which the segment 87 will be attached. The
dimples 91 may be formed in any pattern, spacing or orientation as
described herein.
[0083] FIG. 6 is an embodiment of a segment 87 having a coil or
braided structure 92 within or about the segment 87. The size,
shape, pattern, and manner of incorporating the coil or braid 92
into the segment 87 may be selected based upon the size of the
filter or filter component to which the segment 87 will be
attached. The coil or braid 92 may be formed within the segment
sidewall, near the surface of the segment sidewall or near the
inner surface of the sidewall. The coil or braid 92 may be part of
a sandwich structure as illustrated and described in FIG. 1. The
coil or braid 92 may be formed in any pattern, spacing or
orientation as described herein to enhance the echogenic
characteristics of the filter or filter portion attached to the
segment 87. The coil or braid 92 may be continuous along the entire
length of a segment 87 or, alternatively, the coil or braid 92 may
be in short lengths selected so that a plurality of coils or braids
are provided within a single segment 87.
[0084] FIG. 7 is an embodiment of a segment 87 having a plurality
of echogenic markers 93 arrayed in rings 93.1, 93.2 and 93.3. For
purposes of illustration the rings are shown in an orientation that
is generally orthogonal to the central longitudinal axis of the
segment 87. The rings are shown with a sample spacing of 1 cm
between them. The spacing may be any suitable distance based on the
factors described herein such as filter size and physiological
environment. Similarly, the rings may be angled in other
orientations relative to the longitudinal axis of the segment. For
example, some ring may be in one angular orientation while other
rings may be in a different angular orientation where the angular
orientation or patent of orientation is utilized to provide one or
more of the filter functionality or echogenic characteristics
described herein. In some specific configurations, the spacing and
sizes used are in the millimeter range. In some specific
configurations, the spacing and sizes are in the micron range. In
some specific configurations, the size and/or spacing of a ring or
between adjacent rings are in a combination of mm and micron ranges
for sizes, spacings and features. The size and spacing of the
echogenic markers 93 may be selected based upon the size of the
filter or filter component to which the segment 87 will be
attached. The markers 93 may be formed in any pattern, spacing or
orientation as described herein in order to facilitate a
measurement using the markers. Still further, the markers 93.1,
93.2 and 93.3 may be utilized for provide for other filter
characteristics as described herein.
[0085] FIG. 8 illustrates various alternative configurations for a
segment used alone or in conjunction with other segments. The
segments are illustrated along an exemplary wire, strut, or
component of a filtering device. The segments may have different
characteristics to enable the segment to be more readily imaged by
a medical imaging modality used externally, internally or
intraluminally. In one aspect, the segment characteristics are
selected to provide for imaging enhancements for a filter being
used within a vein or an artery. In another aspect, the segments
may have different characteristics to enable the segment to be
readily imaged by intravascular ultrasound as described herein. In
still another aspect, the segments are oriented and positioned in
order to facilitate IVUS imaging via an IVUS probe borne by a
filter deployment or retrieval catheter, snare, or other implement.
In one illustrative embodiment, the segments are selected and
arrayed to facilitate imaging utilizing IVUS and an external
medical imaging modality. In one exemplary embodiment, the external
imaging modality is x-ray.
[0086] Also illustrated in FIG. 8 is the use of a combination of
different echogenic characteristics (designated E) and radio-opaque
characteristics (designated RO). These characteristics may be any
of those described herein in any combination. The echogenic
characteristic of a segment may be the same as another segment in a
grouping such as in the E segments 87.9 and 87.5. Alternatively,
the echogenic characteristic of a segment may be different from
those in an adjacent group as with segments 87.2, 87.5 and
87.7.
[0087] FIG. 8 also illustrates not only that different
characteristic and properties of segments may be used but also how
variable segment dimensions may be used to aid in echogenic
enhancement of a filter. As illustrated, the segments have
different widths or thicknesses as indicated along the longitudinal
axis of the wire, strut or component. As such, FIG. 8 illustrates a
series of imagine enhancing segments 87.1-87.10 having a variety of
width or thickness values t1-t10. In one embodiment, the segments
are configured as short rings or bands. The thickness of segments
in groups may be similar as illustrated in segments 87.1, 87.2 and
87.3 where the thicknesses t1, t2 and t3 are about the same.
Similarly, segments 87.4, 87.5 and 87.6 illustrate segments of
similar width or thickness where t4, t5 and t6 are about the same
value. Similarly, segments 87.8, 87.9 and 87.10 illustrate segments
of similar width or thickness where t8, t9 and t10 are about the
same value.
[0088] FIG. 8 also illustrates how segments within a group or
groups of segments may have a variety of different spacing (s1-s6)
to provide enhancements to a filter for improving medical imaging
modality characteristics. For example, in the segment grouping of
87.1, 87.2 and 87.3, there is a spacing s1 between segment 87.1 and
segment 87.2 but then no spacing between segments 87.2 and 87.3. A
spacing s2 is shown between segment 87.3 but then no spacing in the
combination segment grouping formed by segments 87.4, 87.5 and
87.6. A spacing of s3 is shown between the three segment
combination of 87.4, 87.5 and 87.6 to the single segment 87.7. The
single segment 87.7 is spaced apart by spacing s4 from the equally
sized (i.e., t8=t9=t10) and equally spaced (i.e., s5=s6) group of
segments 87.8, 87.9 and 87.10. It is to be appreciated that in
various alternative embodiments, the spacing used in groups of
segments or between groups of segments may be the same or
variable.
[0089] FIG. 9 is a view of an exemplary filter illustrating various
alternative aspects of providing a filter with improved echogenic
characteristics. The filter illustrated is a conical filter. It is
to be appreciated that the filter of FIG. 9 is merely
representative of one type of filter. It is to be appreciated that
the various alternative enhancement, modifications and treatments
described herein may be provided to any intravascular or
intraluminal filter. The exemplary filter is dividing into three
general sections A, B and C. Sections A, B and C may be the same
type of enhancement or have an enhancement different from one
another section. In addition, the type of enhancement in each
section may be the same or different from one another in detection,
response or appearance under ultrasound. In addition, a tag,
feature or enhancement may be different within a section. Circles
902 are used to indicate exemplary locations for an echogenic
feature, tag, marker or modification to an enhanced filter 10. The
illustrative embodiment in FIG. 9 also illustrates a continuous
echogenic layer, feature or modification or treatment 908. The
illustrative embodiment in FIG. 9 also illustrates an echogenic
attribute on/near an inflection point 906 in an enhanced filter
structure 10. The illustrative embodiment in FIG. 9 also
illustrates a segmented echogenic layer, feature or modification or
treatment 904 on an enhanced filter structure 10. Section A is
considered the apex, tip, distal portion or terminal end depending
upon filter configuration. Section B is considered the mid-strut,
middle, filtration portion, debris capture portion, or thrombus
collection or lysing portion depending upon specific filter
configuration. Section C is considered the rear portion, proximal
portion, proximal terminal portion, anchor, fixation or perforation
portion depending upon a specific filter configuration. It is to be
appreciated as well that the echogenic features, tags, markers or
modifications illustrated for sections A, B and/or C may be of the
same type or different types depending upon the echogenic signature
or attribute intended for that section, group or sections or
filter. As such, the echogenic features, tags, markers or
modifications for a particular section may be selected from any of
the various alternatives described herein.
[0090] Echogenic characteristics may be added to each of the
sections based on the type of function being measured or
characterized. For example, echogenic markers, features or tags may
be added to Section A in order to provide, for example:
identification of the terminal end, end portion or retrieval
portion of a filter. Echogenic characteristics of Section A may
also be used for determinations related to Section A specifically
or the filter generally of filter position, positioning, attitude
within the lumen, localization of the filter within the vasculature
and other traits common to the characterization of intravascular
devices. For example, echogenic markers, features or tags may be
added to Section B in order to provide, for example: identification
of the mid strut portion, middle or capture region. Echogenic
characteristics of Section B may also be used for determinations
related to Section B such as for sizing, centering, symmetry of
implantation, placement, apposition of implant to vessel walls,
clot burden, deployment status or completion, gauge of filter
capacity and/or filter contents as well as filter position,
positioning, attitude within the lumen, localization of the filter
within the vasculature and other traits common to the
characterization of intravascular devices. For example, echogenic
markers, features or tags may be added to Section C in order to
provide, for example: identification of the rear portion, terminal
end, retrieval feature, anchor location or depth of insertion,
perforation indication or other aspects of the rear or proximal
portion of a filter. Echogenic characteristics of Section C may
also be used for determinations related to Section C such as for
sizing, centering, symmetry of implantation or placement of legs
struts and the like, as well as for determination of wall
apposition, anchor penetration or perforation. Still further, the
markers or tags may be added to aid in determining or evaluating
filter position, positioning, attitude within the lumen,
localization of the filter within the vasculature and other traits
common to the characterization of intravascular devices.
[0091] A filter having enhanced echogenic properties is illustrated
in FIG. 9 as it appears when it is in operative position within the
vasculature. In one specific aspect the filter is in use in a large
blood vessel. One exemplary vessel is the vena cava. Still further,
a modified filter may be employed in a different vein or even an
artery. The filter is designated generally by reference numeral 10,
and the wall of the blood vessel in which it is located is
designated by reference numeral 12. The filter 10 includes an
apical hub 14 of overall egg-shaped or tear drop configuration and
which has a generally hemispherically shaped end portion 14a.
[0092] The filter 10 includes a plurality of elongated legs 16
which are of equal length and are identically configured to each
other. The legs 16 are collectively arrayed in a conical geometric
configuration so that the legs converge to the apical hub 14, and
are symmetrically spaced about a central axis extending through the
hub. Each of the legs is of equal diameter over its entire length
and is made of a relatively resilient material, such as tempered
stainless steel wire or the like. In addition to the echogenic
attributes described herein, the legs may be coated with a
polymeric, synthetic resin material having anti-thrombogenic
properties. FIG. 9 illustrates an echogenic marker at the tip 14.
Exemplary continuous echogenic layers, features or modifications
are also illustrated along one or more legs of the filter. In
addition, FIG. 9 illustrates the use of echogenic tags, features or
markers at, along or near inflection points in a filter element or
component. In addition, FIG. 9 illustrates to application of
echogenic markers, tags or features near the fixation elements of
the filter.
[0093] FIG. 9 is a view of an IVC filter having an improved
echogenic characteristic. A filter constructed in accordance with
the invention is illustrated in FIG. 9 as it appears when it is in
operative position within a large blood vessel, such as the vena
cava. The filter is designated generally by reference numeral 10,
and the wall of the blood vessel in which it is located is
designated by reference numeral 12. FIG. 10 is an end view of the
filter in FIG. 9.
[0094] The filter 10 includes an apical hub 14 of overall
egg-shaped or tear drop configuration and which has a generally
hemispherically shaped end portion 14a. This construction avoids
impalement of the filter on the blood vessel walls during
emplacement, and also avoids irritation or scratching of the blood
vessel during insertion of the filter. The apical hub 14 is drilled
for the reception of the end portions of a plurality of legs as
hereinafter described.
[0095] The filter 10 includes a plurality of elongated legs 16
which are, in some embodiments, of equal length and are identically
configured to each other. In one aspect, the legs 16 are
collectively arrayed in a conical geometric configuration so that
the legs converge to the apical hub 14, and are symmetrically
spaced about a central axis extending through the hub. Each of the
legs is of equal diameter over its entire length and is made of a
relatively resilient material, such as tempered stainless steel
wire or the like. The legs may be coated with a polymeric,
synthetic resin material having anti-thrombogenic properties. In
the embodiment of the filter illustrated, six of the legs 16 are
provided, and since each of these legs is identical to every other
leg, only one of the legs will be described in greater detail.
[0096] At its outer end, or end which is distally located with
respect to the apical hub 14, each leg is reversely bent through an
angle of more than 90.degree., and is tapered or sharpened to a
point 16a. The reverse bend is outwardly in a direction away from
the central axis of the conical figure. As depicted in FIG. 11, the
end portions of the several legs 16 project into bores formed
through the apical hub 14, and are secured in the hub by suitable
techniques.
[0097] It will be seen in FIG. 9 that when the filter 10 is
positioned in the blood vessel, the points 16a at the divergent
ends of the legs 16 hook into or impale the wall 12 of the blood
vessel, but the hooks are not of sufficient size to penetrate or
pass through the wall of the blood vessel. It will further be noted
by reference to the arrow within the blood vessel in FIG. 9 that
when the blood flows in the direction indicated by the arrow, the
pressure exerted by the blood on the filter 10, and any embolus
which may be entrapped thereby, tends to set the hooks at the
divergent ends of the legs 16 into the wall 12 of the blood vessel
so that dislodgment of the filter is resisted.
[0098] FIG. 12 is a view of a breakaway anchor portion of an IVC
filter having an improved echogenic characteristic. Referring to
FIG. 12, an embodiment of the blood clot filtration device 10 of
the invention consists of six legs 12 protruding from a head or
nosebead 14. The legs 12, e.g., wire of diameter D.sub.W, about
0.018 inch (0.5 mm), each have: a first linear leg portion 13 lying
parallel to axis E of the filter, for distance H.sub.N, e.g., about
1 mm, a nose bend 15, a second multi angled leg portion 16 of
relatively greater length than the first linear leg portion,
angling outwardly from the distal end of the first leg portion away
from axis E, to define, with other second leg portions, an
imaginary cone with base 20, shown as dotted lines; and outwardly
directed hooks 22. The second leg portions 16 consist of a series
of discrete linear segments arrayed generally tangent to the
surface of the imaginary cone in a manner to increase the
efficiency of the filtering effect. The diameter of the base of the
filter is D.sub.B, about 38 mm, and the overall length of the
filter is L, about 50 mm. The linear leg portions 13 of all of the
legs are closely arranged in a hexagonal pattern about central leg
stub or segment 24 and the ends of all of these legs are joined at
the apex in proximal head or nose bead 14, formed by fusing the
ends of legs 12 and central leg stub 24 together.
[0099] The wires forming legs 12 are formed into first linear
portion 13, second multi angled portion 16 and hook 22 against a
steel guide in such a way that there is an alternating bend
circumferentially oriented to produce a characteristic conical
structure. Hook 22 has length L.sub.H, about 1.8 mm, and is angled
at angle .theta..sub.H, about 34.degree.. The bends 38 in leg wires
12 are formed by bending the wires at an angle of
130.degree.-150.degree.. Hook 22 is formed mechanically by bending
the distal end of wire 12 over a mandrel. Hook 22 is then sharpened
on three sides against an abrasive wheel. Nose bend 15 is made to
form first linear portion 13 near to bead 14, parallel to axis E of
filter 10. The leg 12 then bends slightly outwardly on the major
angle of the cone and passes through a series of bends as described
above.
[0100] The embodiment of the filter described above with regard to
FIG. 12 may be modified to be a filter having enhanced echogenic
properties characteristics or features. This filter embodiment may
be modified with enhanced echogenic characteristics including one
or more than one of: (a) a modification to one or more components
of the filter to enhance the echogenic characteristics of the
component; (b) formation of dimples into a component surface of
sufficient number and scaled to a suitable size, shape, orientation
and pattern for use with intravascular ultrasound systems; (c)
protrusions formed in, placed on or joined to a filter surface; (d)
roughening one or more surfaces of a filter, for example using a
chemical process, a laser or bead blasting technique; and (e)
altering one or more steps of a filter manufacturing technique to
introduce cavities, voids or pockets to locally modify or adapt one
or more acoustic reflection characteristics to improve echogenicity
in one or more specific regions of a filter. In other aspects, the
filter illustrated and described in FIG. 12 may be modified
according to FIGS. 1-9 above.
[0101] FIGS. 13 and 14 are of an IVC filters having an improved
echogenic characteristic. Referring now to FIG. 13, there is shown
a first embodiment of a vena cava filter 10 having an apical hub or
head 14 of generally cylindrical shape.
[0102] The filter 10 includes a plurality of elongated legs 16
which are of equal length, and are preferably identically
configured to each other. The legs 16 are collectively arranged in
a generally conical geometric configuration so that the legs 16
converge in the apical head 14, and are symmetrically spaced about
a central longitudinally disposed axis "L", which is shown
extending through the head 14, in FIG. 13. The legs are of
equivalent diameter, being about 0.018 inches in diameter
fabricated from stainless steel or titanium wire, and are of about
2.02 inches in final length. In the embodiment of the present
invention, six legs are provided, however only one will be
described in detail.
[0103] At its outermost end 18 which is distal with respect to the
apical head 14, each leg 16 has a main portion 20 and a reversely
bent portion 22 which is bent through an angle of about 180.degree.
in the plane which is tangential to the conical configuration of
the legs, and is disposed parallel and contiguous to the main
portion 20. A pointed tip portion 24 of the leg which comprises a
hook, extends generally radially outwardly, away from the main
portion 20 at an angle of from 70.degree. to about 90.degree.,
which tip portion 24 is shown piercing a cava wall 26.
[0104] A further embodiment of a vena cava filter 60 is shown in
FIG. 14 having an apical head 62. The filter 60 includes a
plurality of elongated legs 64 which are of equal length, and are
configured identical to each other. The legs 64 are collectively
arranged in a slightly outswept but generally conical configuration
so that the legs 64 converge in the head 62, and are symmetrically
spaced about a central longitudinally disposed axis "L", which is
shown extending through the head 62 in FIG. 13. The legs are about
0.018 inches in diameter fabricated preferably from stainless
steel, only one of the legs being described in detail. Each leg has
an outermost or distal end 66 with a hook configuration disposed
thereon.
[0105] A typical leg 64 is each mounted in a bore 68 in the apical
head 62, which bore may be parallel to the center line of the
filter 60. Each bore 68 receives only about 0.19 inches of the
proximalmost end of each leg 64. When all the legs 64 are filling
their proper respective bores 68, they are preferably welded
therein. Each leg 64, in addition to having a plurality of U-shaped
bends 70, disposed in the plane tangential to the cone defined by
the legs 64, and intermediate their proximal and distal ends, as
recited in the aforementioned incorporated patent, has a first
slight bend 72 having a radius of curvature R1 of about 1.4 inches
arranged immediately adjacent the apical head 62, to cause the
leg(s) 64 to flare radially outwardly about 18 degrees, thus
defining their cone shaped configuration. This flare permits the
filter 60 to have enough elastic recoil to assume its general
conical configuration, which is desirable to permit the filtration
of blood clots while still allowing blood to flow around the
captured clots, thus promoting dissolution of any clot and
maintenance of vessel patency. The filter 60 with this flare can be
passed through small delivery carriers without exceeding the
elastic limit of the stainless steel filter legs 64.
[0106] The apical head 62 on the filter 60 has a central
cylindrically shaped bore 80 which is adapted to receive inself
aligning engagement, a guidewire (not shown). The bore 80
critically has its cylindrical portion which is in axial alignment
with the longitudinal center line "L" of the filter 60. Each end of
the bore 80 has a tapered counterbore 82 to permit access of a
guidewire into the bore 82. This permits the filter 60 to be
aligned and centered along the axis of a guidewire in a vessel
during (and after) filter emplacement therein.
[0107] The embodiment of the filter described above with regard to
FIGS. 13 and 14 may be modified to be a filter having enhanced
echogenic properties characteristics or features. This filter
embodiment may be modified with enhanced echogenic characteristics
including one or more than one of: (a) a modification to one or
more components of the filter to enhance the echogenic
characteristics of the component; (b) formation of dimples into a
component surface of sufficient number and scaled to a suitable
size, shape, orientation and pattern for use with intravascular
ultrasound systems; (c) protrusions formed in, placed on or joined
to a filter surface; (d) roughening one or more surfaces of a
filter, for example using a chemical process, a laser or bead
blasting technique; and (e) altering one or more steps of a filter
manufacturing technique to introduce cavities, voids or pockets to
locally modify or adapt one or more acoustic reflection
characteristics to improve echogenicity in one or more specific
regions of a filter. In other aspects, the filter illustrated and
described in FIGS. 13 and 14 may be modified according to FIGS. 1-9
above.
[0108] FIG. 15 is a view of an IVC filter having an improved
echogenic characteristic. FIG. 15 is a perspective view of a
thrombus filter 20. Thrombus filter 20 includes a body member 22
and a plurality of elongated struts 24. Struts 24 each have a
joined end 26 and a free end 28. Joined end 26 of each strut 24 is
fixedly attached to body member 22.
[0109] Struts 24 may be fabricated from wire with a circular or
rectangular cross section. For example, struts 24 may be comprised
of 2 inch lengths of 0.018'' diameter wire. Stainless steel,
titanium, and nickel-titanium alloys have all been found to be
acceptable materials for struts 24. In the embodiment of FIG. 15, a
plurality of bends 25 are disposed between free end 28 and fixed
end 26 of each strut 24. It should understood that struts 24 may
also be straight, or include bends different than those illustrated
in FIG. 15, without departing from the spirit of scope of the
present invention.
[0110] In the embodiment of FIG. 15, body member 22 is generally
cylindrical in shape, and includes a bore 23. It should be under
stood that other embodiments of body member 22 are possible without
departing from the spirit or scope of the present invention.
[0111] Struts 24 radiate outwardly from body member 22 such that
thrombus filter 20 is generally conical in shape. When thrombus
filter 20 is deployed inside a blood vessel, free ends 28 engage
the blood vessel wall. Body member 22 is held in a position
proximate the center of the blood vessel by the plurality of struts
24 which engage the blood vessel walls with opposing force
vectors.
[0112] When thrombus filter 20 is disposed in a blood vessel, the
conical formation of struts 24 acts to trap, or capture blood
clots. The generally conical shape of the formation of struts 24
serves to urge captured blood clots toward the center of the blood
flow. The flow of blood around the captured blood clots allows the
body's natural lysing process to dissolve the clots.
[0113] To assure firm attachment of thrombus filter 20 to the blood
vessel walls, anchor portions 30 may be formed at free ends 28 of
struts 24. FIG. 16 illustrates one embodiment of an anchor portion
30 embedded in a vessel wall 32. Anchor portion 30 includes a sharp
point 34 and a bend 36. Strut 24 includes a weakened portion 40
disposed proximate free end 28. In the particular embodiment of
FIG. 16 weakened portion 40 includes a plurality of divets 42.
Divets 42 substantially reduce the cross sectional area of strut 24
at weakened portion 40. Divets 42 may be fabricated by removing
material from strut 24 with a removal process such as machining or
grinding. Divets 42 may also be fabricated by displacing material
with a process such as metal forming or crimping.
[0114] Blood vessel wall 32 is lined with a thin inner membrane or
intima 44. When anchor portion 30 is embedded in wall 32 it
punctures inner membrane 44. The body responds to a puncture of
inner membrane 44 with a process known in the art as neointimal
hyperplasia. The punctured area of inner membrane 44 is overgrown
with a number of new cells. Referring again to FIG. 16, it can be
seen that anchor portion 30 of strut 24 is covered with
encapsulating cell growth 46.
[0115] It is desirable that the thrombus filter of the present
invention can be removed using minimally invasive methods without
complications due to neointimal hyperplasia encapsulation of anchor
portions 30 of struts 24. A process which may be utilized to remove
thrombus filter 20 from a blood vessel 90 is schematically
represented in FIG. 17.
[0116] FIG. 17 schematically illustrates a blood vessel 90
including a lumen 92 and walls 32. Thrombus filter 20 is disposed
in lumen 92 of blood vessel 90. Anchor portions 30 of struts 24 are
embedded in walls 32 of blood vessel 90. Neointimal hyperplasia has
resulted in encapsulating cell growth 46 proximate anchor portions
30 of struts 24.
[0117] A removal catheter 100 with a lumen 102 and a distal end 104
is also disposed in lumen 92 of blood vessel 90. Removal catheter
100 enters the patient's vascular system at a point which is
readily accessible to the physician. Once in the vascular system,
catheter 100 is urged forward until distal end 104 is proximate
thrombus filter 20. For example, if thrombus filter 20 is located
in the inferior vena cava of a patient's vascular system, removal
catheter 100 may enter the vascular system at the femoral vein.
Alternately, if thrombus filter 20 is located in the superior vena
cava of a patient's vascular system, removal catheter 100 may enter
the vascular system at the jugular vein. In either case, the filter
removal procedure can be minimally invasive, and not require
general anesthesia.
[0118] Distal end 104 of removal catheter 100 is urged forward so
that body member 22 of thrombus filter 20 is disposed inside lumen
102 of removal catheter 100. A force F is applied to thrombus
filter 20 urging body member 22 further into lumen 102 of removal
catheter 100. The magnitude of force F is of sufficient magnitude
to break struts 24 at weakened portions 40. When struts 24 are
broken at weakened portions 40 thrombus filter 20 including struts
24 may be pulled into lumen 102 of removal catheter 100. Removal
catheter 100 may then be removed from the body of the patient by
withdrawing removal catheter 100 from blood vessel 90. Thus,
thrombus filter 20 is removed from blood vessel 100 but anchor
members 30 remain attached to walls 32 by encapsulating cell growth
46.
[0119] FIG. 18 is a schematic representation of thrombus filter 20
after it has been pulled into lumen 112 of retrieval catheter 110.
As may be seen in FIG. 18, pulling thrombus filter 20 into lumen
112 of retrieval catheter 110 causes struts 24 to collapse. When
struts 24 are collapsed, retrieval catheter 110 may be withdrawn
from blood vessel 100. As can also be seen in FIG. 18, anchor
members 30 remain fixed in the walls of blood vessel 100, retained
by encapsulating cell growth 46.
[0120] Force F may be applied to thrombus filter 20 using a variety
of methods. For example, the pulling of thrombus filter 20 into
lumen 112 of retrieval catheter 110 may be accomplished with a
retrieval wire including a hook. The retrieval wire may pass
through bore 23 of body member 22. With the retrieval wire disposed
in bore 23 of body member 22, the hook may engage body member 22 so
that a pull force can be applied to thrombus filter 20.
[0121] Struts 24 may also be intentionally broken at weakened
portions 40 by repeatedly deflecting struts 24 to induce fatigue
cracking at weakened portions 40. The magnitude of the force
required for this removal method is less than the magnitude of
force required to break struts 24 without fatigue cracking.
[0122] A number of methods may be used to deflect struts 24. First,
a pull force may be applied to thrombus filter 10 as shown in FIG.
17. Applying a pull force to thrombus filter 20 deflects blood
vessel walls 32 and struts 24. When the pull force is released,
blood vessel walls 32 and struts 24 deflect a second time in
returning to an unstressed position. Pulling force F may be applied
and released repeatedly to induce fatigue cracking at weakened
areas 40. It should be noted that the pull force applied when using
this removal method is not sufficient to break struts 24 at the
outset. However, multiple applications of force F cause fatigue
cracks to grow at weakened areas 40. As described above the
cross-sectional area of struts 24 is reduced at weakened areas 40
by slots, holes, and the like. The cross-sectional area of struts
24 is further reduced by fatigue cracking due to repeated
applications of force F. After multiple applications of force F,
the cross-sectional area of struts 24 at weakened areas 40 will be
small enough that force F alone is sufficient to break struts 24 at
weakened areas 40.
[0123] The embodiment of the filters described above with regard to
FIGS. 15-18 may be modified to be a filter having enhanced
echogenic properties characteristics or features. This filter
embodiment may be modified with enhanced echogenic characteristics
including one or more than one of: (a) a modification to one or
more components of the filter to enhance the echogenic
characteristics of the component; (b) formation of dimples into a
component surface of sufficient number and scaled to a suitable
size, shape, orientation and pattern for use with intravascular
ultrasound systems; (c) protrusions formed in, placed on or joined
to a filter surface; (d) roughening one or more surfaces of a
filter, for example using a chemical process, a laser or bead
blasting technique; and (e) altering one or more steps of a filter
manufacturing technique to introduce cavities, voids or pockets to
locally modify or adapt one or more acoustic reflection
characteristics to improve echogenicity in one or more specific
regions of a filter. In other aspects, the filter illustrated and
described in FIGS. 15-18 may be modified according to FIGS. 1-9
above.
[0124] FIG. 19 is a view of an IVC filter having an improved
echogenic characteristic. FIGS. 19 and 20 show a blood clot filter
of the clot filter assembly designated at 10. Filter 10 is shown in
a totally straightened position in FIG. 19 with its wire strands
slightly spaced apart so that the construction of filter 10 may be
more clearly seen. FIG. 20 shows filter 10 in a partially
straightened but also somewhat curled position. It should be
understood that filter 10 would normally assume the shape of a
curly wire mesh unless external forces are employed to straighten
the wire strands. It is also to be understood that filter 10 would
be provided to the physician in a prepackaged assembly additionally
including a cartridge catheter and a wire guide handle, both of
which will be more fully described herein.
[0125] Filter 10 includes six strands of stainless steel wire which
are connected to each other in the following manner. Innermost
strands 11 and 12 are mutually attached at both ends by crimps 13
and 14. Innermost strands 11 and 12 are approximately 25
centimeters in length and are made from 0.007 inch diameter coil
wire. Outermost strands 15 and 16 are located oppositely of
innermost strands 11 and 12 and are each connected thereto at both
ends by wire strands 17 and 18. Outermost strands 15 and 16 are
approximately 38 centimeters in length and are made from 0.007 inch
diameter coil wire. Wire strand 17 serves to connect outermost
strands 15 and 16 with innermost strands 11 and 12 at the distal
end of filter 10. In a similar manner, wire strand 18 connects
outermost strands 15 and 16 with innermost strands 11 and 12 at the
proximal end of filter 10. Wire strand 17 is secured to outermost
strands 15 and 16 by crimps 21 and 22, respectively and to
innermost strands 11 and 12 by crimp 13. In a similar fashion, wire
strand 18 is secured to outermost strands 15 and 16 by crimps 19
and 20, respectively, and to innermost strands 11 and 12 by crimp
14. Wire strands 17 and 18 are approximately 10 centimeters in
length and are made from 0.010 inch diameter stainless steel coil
wire. Crimps 19-22 are made from 3 mm. of 22 GTW cannula while
crimps 13 and 14 are made from 3 mm. lengths of 19.5 GTW cannula.
Innermost strands 11 and 12, and outermost strands 15 and 16 are
made from a shape memory material, such as spring temper stainless
steel.
[0126] During manufacture, wire strands 11, 12, 15 and 16 are
curled in different directions and wadded together to form a curly
wire mesh. Because of their shaped memory construction, innermost
strands 11 and 12 and outermost strands 15 and 16 may be
straightened out at their ends substantially as shown in FIG. 19
for loading into the lumen of a Teflon angiography catheter
cartridge. It may be noted that once loaded within the catheter,
the spring bias inherent within the wire strands will cause some
curling thereof. Further curling is, of course, restrained by the
intimal wall of the catheter cartridge. Thus, it is the spring bias
inherent in the shape memory construction which allows filter 10 to
expand radially outward as innermost wire strands 11 and 12 and
outermost wire strands 15 and 16 contract along their lengths upon
insertion in a body blood vessel, as will be more fully explained
herein.
[0127] Anchoring filter 10 within a body blood vessel, such as the
inferior vena cava, is generally provided by fixation elements at
24 and 25, the details of their construction being more clearly
understood by reference to FIG. 20. It is to be understood that
anchor 24 is located at the rearward end of both wire strands 15
and 16, while anchor 25 is located at the forward end of both wire
strands 15 and 16. Anchor 24 differs from anchor 25 due to the
presence of a barb 30 whose purpose will become fully apparent
hereinafter. The anchor 24 and 25 at the ends of outermost wire
strand 15 are longitudinally staggered from the corresponding
anchor 24 and 25 at the ends of outermost wire strand 16. This
permits the easy loading of filter 10 within the lumen of a
catheter cartridge such as will be more fully described herein.
[0128] Referring particularly to FIG. 20, the details of
construction of the rearward anchoring means 24 will now be
described. It is to be understood that while only the rearward
anchor 24 at the end of outermost wire strand 15 is described, the
rearward anchor means 24 at the end of outermost wire strand 16 is
of a similar construction. It is seen that rearward anchor means 24
includes a length 26 of outermost wire strand 15 located at the
rearward end thereof. Length 26 is approximately one centimeter in
length and has a sharp end point 27 which is meant to enter the
wall of a blood vessel. In order to prevent too deep penetration of
anchor 24 through the blood vessel, a loop 28 of wire formed from
wire strand 18 is positioned adjacent length 26. Loop 28 extends
approximately 7 mm along length 26, crimp 19 serving to secure the
end of loop 28.
[0129] It is to be understood that there are two forward anchor 25
at the forward end of filter 10. As previously mentioned, forward
anchor 25 is of a similar construction to anchor 24 except that a
barb 30 is received over the end length of wire corresponding to
length 26 of anchor 24. The purpose of barb 30 is to provide a more
secure anchor at the downstream end of filter 10 and thereby ensure
long term patency of the filter. Barbs 30 are secured to the
forward ends of the outer most wire strands 15 and 16 by soldering.
Each of the barbs 30 have a lancet beveled portion 31 which faces
outwards of filter 10 and a hooked portion 32 at the inwards facing
end. Hooked portion 32 serves to prevent barb 30 from becoming
dislodged from the body blood vessel once penetration thereof has
been made. Each of the barbs 30 is constructed from 6 mm. to 0.028
inch diameter cannula.
[0130] FIG. 21 show filter 10 in its longitudinally contracted and
radially expanded position within the inferior vena cava of a human
body. It is to be noted that in this position filter 10 is in the
shape of a curly wire mesh with spaces therethrough no larger than
3-4 mm. Also, due to the relatively small diameters of the wire
strands, filter 10 occupies only a minimal portion of the
cross-sectional area of the blood vessel passageway. Thus, filter
10 does not substantially occlude the blood vessel passageway.
Also, barbs 30 extend into the intimal wall of the inferior vena
cava in such fashion so as to firmly anchor filter 10, thereby
ensuring long term patency.
[0131] In addition to the anchoring points at barbs 30, FIG. 21
also shows filter 10 in urging contact with the intimal wall 70 of
the inferior vena cava 65 at innumerable other points along the
lengths of various portions of the wire strands of filter 10.
Initially, these points of urging contact do not provide sufficient
anchoring to ensure patency of filter 10, thus requiring the
anchoring provided by barbs 30. However, after several weeks
endothelization and fibrotic encasement occurs at the points where
the wire mesh of filter 10 abuts the intimal wall of the inferior
vena cava, and the likelihood of permanent patency is thereafter
greatly increased.
[0132] FIG. 22 is an alternative embodiment similar to FIG. 20.
FIG. 22 includes 2 V-shaped struts supporting the fine wires as
described above.
[0133] The embodiment of the filter described above with regard to
FIGS. 19-22 may be modified to be a filter having enhanced
echogenic properties characteristics or features. This filter
embodiment may be modified with enhanced echogenic characteristics
including one or more than one of: (a) a modification to one or
more components of the filter to enhance the echogenic
characteristics of the component; (b) formation of dimples into a
component surface of sufficient number and scaled to a suitable
size, shape, orientation and pattern for use with intravascular
ultrasound systems; (c) protrusions formed in, placed on or joined
to a filter surface; (d) roughening one or more surfaces of a
filter, for example using a chemical process, a laser or bead
blasting technique; and (e) altering one or more steps of a filter
manufacturing technique to introduce cavities, voids or pockets to
locally modify or adapt one or more acoustic reflection
characteristics to improve echogenicity in one or more specific
regions of a filter. In other aspects, the filter illustrated and
described in FIGS. 19-22 may be modified according to FIGS. 1-9
above.
[0134] FIG. 23 is a view of an IVC filter having an improved
echogenic characteristic. The filter 10 in FIG. 23 is made up of a
set of seven wires. Six of these are approximately three inches in
length when fully extended. The seventh is approximately two inches
in length when fully extended. The wires are held together by two
small sleeves or coils 12 and 14 of the same material, each coil
being spot welded to hold it in place and approximately one-quarter
of an inch in length; coil 12 is adjacent the tip 13 of the seven
wires, and coil 14 is approximately two inches from tip 13 when the
wires are fully extended. In the low temperature phase of the
material the set of wires can be straightened and held in a
straight form that can pass through a length of fine plastic tubing
with an internal diameter of approximately 2 mm (#8 French
catheter).
[0135] In its normal expanded configuration or performed filtering
shape, filter 10 is a double filter, having a first filter basket
16 and a second filter basket 18. The two filter baskets provide
peripheral portions which engage the inner wall of the vein at two
longitudinally spaced locations. The two filter baskets are
generally symmetrical about a longitudinal axis passing through
filter tip 13.
[0136] The mesh of first filter basket 16 is formed from the
sections of wires between the two quarter-inch coils 12 and 14. The
mesh is made up of a series of seven overlapping loops 20 arranged
to form a rosette approximately 25 mm in diameter. The loops are
angled slightly relative to the long axis of filter 10 and this
angle can be varied to accommodate somewhat smaller diameters if
the device is to be constrained in a tube of less than 25 mm in
caliber. The loops 20 effectively divide the cross-sectional area
to be filtered. The rosette formed by loops 20 can expand or be
compressed to fit various sizes of vein. The peripheral portions or
tips of the loops 20 press outwardly against the inner wall of the
vein, although without becoming imbedded in the vein; loops 20
thereby help to keep filter 10 in place. First filter basket 16 is
convex relative to filter tip 13.
[0137] The mesh of second filter basket 18 is formed by the six
circumferentially spaced free wire ends or legs 22, which tilt and
bow outwardly of the long axis of filter 10. The seventh wire
terminates within sleeve 14 for use in inserting filter 20. The six
free ends or legs 22 that extend beyond the second quarter inch
coil 14 diverge so that their tips form a circle 24 of
approximately 40 mm in diameter at their maximum divergence. Each
leg is also bowed outwardly slightly. The legs serve to orient the
device relative to the long axis of the vena cava. Second filter
basket 18 is convex relative to filter tip 13.
[0138] In another alternative embodiment the legs are tilted
outwardly but are not formed with a bow. In such an embodiment,
second filter basket 18 opens away from filter tip 13 without being
strictly convex.
[0139] Each free end of leg 22 is bent sharply outward at about a
right angle to form a hook 26 of approximately 1.5 mm in length.
The hooks are intended to engage the wall of the vena cava to
prevent migration proximally or distally.
[0140] The six legs 22 are of slightly different lengths to permit
good packing within the delivery device, as will be described; if
legs 22 are all of a single length, the hooks may interfere with
one another, so that the filter does not expand properly when
delivered into the vein.
[0141] FIG. 24 is a view of an IVC filter having an improved
echogenic characteristic. In FIG. 16, a blood clot filter of the
type intended for percutaneous introduction and delivery using a
transfemoral approach is shown and is designated generally by
reference numeral 20. Within FIG. 16, dashed lines 22 and 24
indicate the outline of an interior wall of a blood vessel, such as
the inferior vena cava. Blood clot filter 20 consists essentially
of a central core wire 26 which extends generally along the central
longitudinal axis of blood clot filter 20, as well as six
peripheral wires 28, 30, 32, 34, 36 and 38 spaced equiangularly
about central core wire 26. Peripheral wires 36 and 38 are hidden
from view in FIG. 16 by peripheral wires 30 and 32,
respectively.
[0142] In FIG. 24, a first connector 40 is shown forming a nose of
blood clot filter 20. Connector 40 serves to connect together a
first end of each of peripheral wires 28-38, and attaches such
peripheral wires about the first end of central core wire 26 at a
first connection point. Connector 40 is welded, crimped or
otherwise attached to the first end of central core wire 26 and to
the first ends of peripheral wires 28-38 so that a fixed connection
is achieved between the central core wire and the six peripheral
wires.
[0143] Still referring to FIG. 24, the six peripheral wires 28-38
are again joined along their central portions by a second connector
42. Connector 42 is in the form of a tubular collar having a
central opening defining an interior wall 44. Each of the
peripheral wires 28-38 passes through tubular collar 42 and is
secured to interior wall 44 thereof, as by welding or by other
means of attachment. Thus, second connector 42 serves to connect
together peripheral wires 28-38 at a second connection point spaced
apart from the first connection point at first connector 40. it
will be noted that central core wire 26 passes freely through the
interior space defined by tubular collar 42 and the peripheral wire
secured therein, thereby allowing second connector 42 to slide
along central core wire 26.
[0144] The embodiment of the filter described above with regard to
FIGS. 23 and 24 may be modified to be a filter having enhanced
echogenic properties characteristics or features. This filter
embodiment may be modified with enhanced echogenic characteristics
including one or more than one of: (a) a modification to one or
more components of the filter to enhance the echogenic
characteristics of the component; (b) formation of dimples into a
component surface of sufficient number and scaled to a suitable
size, shape, orientation and pattern for use with intravascular
ultrasound systems; (c) protrusions formed in, placed on or joined
to a filter surface; (d) roughening one or more surfaces of a
filter, for example using a chemical process, a laser or bead
blasting technique; and (e) altering one or more steps of a filter
manufacturing technique to introduce cavities, voids or pockets to
locally modify or adapt one or more acoustic reflection
characteristics to improve echogenicity in one or more specific
regions of a filter. In other aspects, the filter illustrated and
described in FIGS. 23 and 24 may be modified according to FIGS. 1-9
above.
[0145] FIG. 25 is a view of an IVC filter having an improved
echogenic characteristic. The filter in FIG. 25 comprises four legs
1, 2, 3 and 4 diverging from an apical hub 5 at which the legs 1 to
4 are held together by an end ferrule 6 of the kind e.g. disclosed
in U.S. Pat. No. 4,619,246, incorporated herein by reference.
[0146] Each leg comprises a central element 1a, 2a, 3a, and 4a bent
into a smooth quasi-halfsinusoidal form and having a reversely
turned anchoring hook 1b, 2b, 3b and 4b at its distal end with
respect to hub 5 as well as two symmetrical curved side elements
1c, 2c, 3c and 4c, and 1d, 2d, 3d and 4d extending on either side
of the central element.
[0147] In the embodiment shown the two side elements of each leg 1
to 4 are formed from one piece of wire the ends of which are held
together in hub 5, whereas at the middle of its length the wire
piece forms an eyelet 7, 8, 9 and 10 surrounding the central leg
element to be freely slidable along a part of the length
thereof.
[0148] From the unfolded tulip-like configuration illustrated in
FIG. 25 the filter may be collapsed into a slender and very narrow
bundle of filter elements the cross-sectional dimension of which is
approximately equal to the sum of the thicknesses of the central
and side elements of all four legs.
[0149] The side elements of each leg have a length and curvature
such that in the unfolded tulip-like configuration of the filter
the maximum distance between the side elements is of the same order
as the distance between neighboring side elements of two adjacent
legs. Moreover, the length and curvature is preferably chosen such
that after insertion into the vena cava inferior the eyelets 7-10
will be positioned substantially at the inner side of the wall of
the blood vessel.
[0150] As best seen in FIG. 25 the filter according to the
invention has in its unfolded state a relatively short axial length
of the same order as the diameter of the filter whereby proper
arrangements of the filter into the inferior vena cava is
facilitated.
[0151] The embodiment of the filter described above with regard to
FIG. 25 may be modified to be a filter having enhanced echogenic
properties characteristics or features. This filter embodiment may
be modified with enhanced echogenic characteristics including one
or more than one of: (a) a modification to one or more components
of the filter to enhance the echogenic characteristics of the
component; (b) formation of dimples into a component surface of
sufficient number and scaled to a suitable size, shape, orientation
and pattern for use with intravascular ultrasound systems; (c)
protrusions formed in, placed on or joined to a filter surface; (d)
roughening one or more surfaces of a filter, for example using a
chemical process, a laser or bead blasting technique; and (e)
altering one or more steps of a filter manufacturing technique to
introduce cavities, voids or pockets to locally modify or adapt one
or more acoustic reflection characteristics to improve echogenicity
in one or more specific regions of a filter. In other aspects, the
filter illustrated and described in FIG. 25 may be modified
according to FIGS. 1-9 above.
[0152] FIG. 26 shows a filter generally designated by the numeral
12, and in FIG. 27 it is seen to comprise a generally dome-shaped
body 14 of open work construction composed of skeletal members such
as 16, 18, 20, 22, 24 and 26 which are arranged in a manner
somewhat similar to the struts of an open umbrella canopy, and when
in the open position shown in FIG. 27, span a distance d greater
than that which characterizes the range of diameters commonly
encountered in the inferior vena cava. In the preferred embodiment,
the six radiating spokes are of collapsible, resilient, alloy
material. The inward or converging proximal ends of the spokes or
frame members con-verge to a hub 28 and are there united forming
the skeletal frame. The distal ends of the struts or spokes all
extend somewhat beyond the outer lip or margin of the canopy now to
be described, and these ends are preferably sharpened to comprise a
holding and gripping means, as will be apparent hereinafter. The
canopy portion 30 comprises a suitable filter media of generally
sheet form overlaying and being supported on the framework.
Preferably, the filtering media includes a plurality of holes in
the preferred embodiment, one hole being disposed in the generally
triangular portion of the canopy between each of the spokes, and
these holes or openings, one of which is designated by the numeral
32 for purposes of clarity, are on the order of about 3 millimeters
in diameter and are circular in cross section. The pointed distal
ends of the spokes appear as circumferential teeth which extend
outwardly of the canopy. The hood or canopy is preferably of a
flexible, smooth surfaced material, such as a plastic material, and
which provides a smooth surface. For purposes-which will be
apparent hereinafter, there is an axial recess 50 in the hub which
is threaded.
[0153] The embodiment of the filter described above with regard to
FIGS. 26 and 27 may be modified to be a filter having enhanced
echogenic properties characteristics or features. This filter
embodiment may be modified with enhanced echogenic characteristics
including one or more than one of: (a) a modification to one or
more components of the filter to enhance the echogenic
characteristics of the component; (b) formation of dimples into a
component surface of sufficient number and scaled to a suitable
size, shape, orientation and pattern for use with intravascular
ultrasound systems; (c) protrusions formed in, placed on or joined
to a filter surface; (d) roughening one or more surfaces of a
filter, for example using a chemical process, a laser or bead
blasting technique; and (e) altering one or more steps of a filter
manufacturing technique to introduce cavities, voids or pockets to
locally modify or adapt one or more acoustic reflection
characteristics to improve echogenicity in one or more specific
regions of a filter. In other aspects, the filter illustrated and
described in FIGS. 26 and 27 may be modified according to FIGS. 1-9
above.
[0154] With reference firstly to FIG. 28, there is thus illustrated
a filter 1 in the unfolded position consisting of fingers 2, of
which there are ten for example, which emerge from a head 3 and
which can be unfolded substantially in a generally conical shape of
which the opening is marked in dashed lines at 4. Each finger is
provided at its free end with a centering and bearing runner 5
which turns substantially behind the head 3; that is, this runner 5
is directed from the end 2a of the fingers towards the closure side
of the cone forming the filter. More precisely, if we designate as
6 the cylinder generated by a generating line that is parallel with
the axis 7 of the conical shape formed by the filter 1 and moved
such that it describes the line 4, the runners 5 are directed such
that they are substantially parallel with the wall of the cylinder
6.
[0155] In accordance with the invention, the filter fingers consist
of flexible wires 8. They may in particular consist of metal wires,
for example of a suitable grade of stainless steel. The diameter of
the wires may be between 2 and 4 tenths of a millimeter for example
3 or 3.5 tenths of a millimeter.
[0156] These fingers are combined in groups of two adjacent fingers
by a wire part which is folded in the manner of a hairpin 9 and
forms said runners. As a result, the fingers are in the general
shape of a clip 10. Advantageously, the filter preferably comprises
at least six of the above fingers connected to three wire portions
folded in the manner of a pin and distributed in an angular manner
so as to ensure that the filter has good axial stability.
[0157] Referring to FIG. 29, it will be noted that the filter,
which is generally indicated 1, comprises a series of elongated
branches or legs 3 each of which is substantially "V"-shaped. One
of the free ends of each "V" comprises fixation means such as a
hook 5 for anchoring the filter to the vessel wall. The other end
is connected to a metal thread, which has a succession of
corrugations or undulations (such as zig-zags) forming a resilient
annular structure 7 of which the central opening has a diameter
which can be more or less "constricted" and which is adapted to
permit the passage of the temporary filter. The various branches 3
can be produced in the form of fine metal threads and are secured
around the annular structure or ring 7 However, the whole of the
filter could also be produced in a single metal piece, its
structure being obtained by cutting.
[0158] In order to be introduced into the vessel, the filter 1 can
adopt a constrained state in which the elongated branches or legs 3
are moved close up to the axis 18 of the central opening of the
filter until they are substantially parallel thereto. When it is in
place in the vessel, the filter adopts a radially expanded state,
the branches 3 then moving away from the axis 18 and the hooks 5
anchoring themselves in the vessel wall.
[0159] The embodiment of the filter described above with regard to
FIGS. 28 and 29 may be modified to be a filter having enhanced
echogenic properties characteristics or features. This filter
embodiment may be modified with enhanced echogenic characteristics
including one or more than one of: (a) a modification to one or
more components of the filter to enhance the echogenic
characteristics of the component; (b) formation of dimples into a
component surface of sufficient number and scaled to a suitable
size, shape, orientation and pattern for use with intravascular
ultrasound systems; (c) protrusions formed in, placed on or joined
to a filter surface; (d) roughening one or more surfaces of a
filter, for example using a chemical process, a laser or bead
blasting technique; and (e) altering one or more steps of a filter
manufacturing technique to introduce cavities, voids or pockets to
locally modify or adapt one or more acoustic reflection
characteristics to improve echogenicity in one or more specific
regions of a filter. In other aspects, the filter illustrated and
described in FIGS. 28 and 29 may be modified according to FIGS. 1-9
above.
[0160] In FIG. 30 there is illustrated a vena cava filter
comprising a filter basket generally designated by 1 and consisting
of a plurality of thin resilient wires 2 of a suitable material,
preferably a stainless steel alloy. As illustrated in FIG. 30,
basket 1 is generally shaped as an elongate, apertured solid of
revolution resulting from the rotation of a sinusoid curve about an
axis of rotation indicated in FIG. 30 by a dot-and-dash-line 3,
which is tangent to the generatrix at the ends thereof. At each end
of the basket proper, the wires are interconnected by means of a
short ferrule 4 secured to the wires by any appropriate means, such
as brazing.
[0161] As shown in FIG. 30 the ratio of the basket length to its
maximum diameter is approximately 2. It should be understood that
the exact value of this ratio is not critical for the function of
the filter basket and in practice it may assume a value between 1.5
and 3, or even higher, although probably the improvement at higher
values may be marginal.
[0162] As appears from FIG. 30, between the end ferrules 4 each
wire 2 follows a helix-like curve, all curves being similar and
having the same "hand", in the example right-handed. From one end
to the other, each wire 2 is "twisted" approximately 90.degree.
about the axis 3.
[0163] In FIG. 30 a small, oblong eyelet 5 of wire similar to wires
2 is secured in each ferrule 4 so as to protrude axially from
basket 1. By means of either eyelet 5 and a mating hook or other
gripping device at the end of an insertion wire, the collapsed
filter basket may be pushed or pulled through an inserting
catheter, as briefly discussed above.
[0164] A plurality of anchoring legs 6, in the example five, are
secured in the right-hand ferrule 4 of FIG. 30, from which they
extend axially away from basket 1 and outwardly relative to axis 3.
The free end of each leg 6 is bent outwardly to form a hook 7
which, when the filter basket has been positioned in a blood
vessel, penetrates slightly into the wall of the vessel so as to
hold the filter basket in position. Legs 6 will normally be made of
the same or a similar material as wires 2 so that they can be
readily collapsed to fit within the lumen of the insertion
catheter, and spring back to engage the wall of the blood vessel
when released from the catheter. The pronounced S-shape of legs 6
in the region immediately inwardly of hooks 7 ensures that when the
filter basket moves through the catheter it will be the smooth
curved portions of the legs rather than the hooks 7 which contact
the catheter wall.
[0165] The embodiment of the filter described above with regard to
FIG. 30 may be modified to be a filter having enhanced echogenic
properties characteristics or features. This filter embodiment may
be modified with enhanced echogenic characteristics including one
or more than one of: (a) a modification to one or more components
of the filter to enhance the echogenic characteristics of the
component; (b) formation of dimples into a component surface of
sufficient number and scaled to a suitable size, shape, orientation
and pattern for use with intravascular ultrasound systems; (c)
protrusions formed in, placed on or joined to a filter surface; (d)
roughening one or more surfaces of a filter, for example using a
chemical process, a laser or bead blasting technique; and (e)
altering one or more steps of a filter manufacturing technique to
introduce cavities, voids or pockets to locally modify or adapt one
or more acoustic reflection characteristics to improve echogenicity
in one or more specific regions of a filter. In other aspects, the
filter illustrated and described in FIG. 30 may be modified
according to FIGS. 1-9 above.
[0166] Referring now to the drawings, FIG. 31 shows the filter 1 of
the present invention which firstly comprises filtering section 2
adapted to open out in the blood vessel 3, particularly the
inferior vena cava, when the filter is correctly positioned in the
patient.
[0167] These filtering section 2 are advantageously constituted by
an assembly of flexible filiform elements 4 joined together by one
of their ends to form substantially the envelope of a cone, ogive
or the like.
[0168] In this way, this assembly of filiform filtering elements 4
will be permeable to the blood flow, indicated by arrows 5, but
adapted to retain the clots. To that end, it will be disposed in
the direction of the blood flow, i.e. the apex of the cone or the
like will be directed substantially in the same direction as the
blood flow.
[0169] By way of example, the flexible rods 4 will be six in number
and made of a bio-compatible material, such as a suitable metal
alloy or plastics material. However, these materials will be chosen
for their aptitude to elasticity and to deformation.
[0170] In fact, the rods 4 will represent a good flexibility in
order, on the one hand, to be folded in a catheter of small
dimensions and, on the other hand, to open out correctly in the
blood vessel to form a barrage at the latter's dimensions.
[0171] Furthermore, the filiform filtering elements 4 will be such
that they are non-aggressive with respect to the inner walls of the
vessel.
[0172] More precisely, as shown in FIG. 31, the rods 4 present at
least a slight angle or curve 6, so that their terminal part 7 is
in non-aggressive contact with the vessel, when the filtering means
are opened out, but so that there is no penetration of the ends of
the rods 4 in the wall of the vessel proper.
[0173] The embodiment of the filter described above with regard to
FIG. 23 may be modified to be a filter having enhanced echogenic
properties characteristics or features. This filter embodiment may
be modified with enhanced echogenic characteristics including one
or more than one of: (a) a modification to one or more components
of the filter to enhance the echogenic characteristics of the
component; (b) formation of dimples into a component surface of
sufficient number and scaled to a suitable size, shape, orientation
and pattern for use with intravascular ultrasound systems; (c)
protrusions formed in, placed on or joined to a filter surface; (d)
roughening one or more surfaces of a filter, for example using a
chemical process, a laser or bead blasting technique; and (e)
altering one or more steps of a filter manufacturing technique to
introduce cavities, voids or pockets to locally modify or adapt one
or more acoustic reflection characteristics to improve echogenicity
in one or more specific regions of a filter. In other aspects, the
filter illustrated and described in FIG. 23 may be modified
according to FIGS. 1-9 above.
[0174] Referring now to the drawings, and firstly to FIG. 32, a
filter device (hereinafter referred to as "filter") according to
the present invention is essentially constituted by an assembly of
identical, curved, elastic legs 1, for example six in number,
disposed in two's successively in opposite direction, and joined
together at their ends 2, 3, particularly by fixing them, for
example by electrical spot welding, on two connecting pieces 4,
5.
[0175] Each connecting piece is constituted by a substantially
cylindrical, hollow piece, the connecting pieces 4 and 5 presenting
different internal diameters.
[0176] Legs 1, in the out-spread state for use, are angularly
distributed in substantially regular manner, for example spaced
apart successively in two's by about 60.degree..
[0177] Each leg 1 comprises a convex portion, whose apex 6 is
adapted to abut against the inner wall of the vein 7 when the legs
are in out-spread state for use.
[0178] This convex portion, which may for example be made by
burnishing, is closer to one end of leg 1 than the other, with the
result that, the legs being identical and mounted successively in
two's in opposite direction, said filter abuts on the vein, at the
level of apices 6, via two series of points spaced apart
longitudinally by a predetermined distance.
[0179] The embodiment of the filter described above with regard to
FIG. 32 may be modified to be a filter having enhanced echogenic
properties characteristics or features. This filter embodiment may
be modified with enhanced echogenic characteristics including one
or more than one of: (a) a modification to one or more components
of the filter to enhance the echogenic characteristics of the
component; (b) formation of dimples into a component surface of
sufficient number and scaled to a suitable size, shape, orientation
and pattern for use with intravascular ultrasound systems; (c)
protrusions formed in, placed on or joined to a filter surface; (d)
roughening one or more surfaces of a filter, for example using a
chemical process, a laser or bead blasting technique; and (e)
altering one or more steps of a filter manufacturing technique to
introduce cavities, voids or pockets to locally modify or adapt one
or more acoustic reflection characteristics to improve echogenicity
in one or more specific regions of a filter. In other aspects, the
filter illustrated and described in FIG. 32 may be modified
according to FIGS. 1-9 above.
[0180] As shown in FIG. 33, the embolus trap comprises a central
cylindrical column 11 to which is attached a plurality of upper
elongated loops 12 of filaments 13 and 14, such as metal wire, and
a plurality of like lower loops 15. Loops 12 and 15 are assembled
in two tiers spaced from one another on column 11. The loops 12 in
the upper tier are circumferentially spaced from each other in
symmetrical fashion, as are the loops 15 in the lower tier. The
loops of adjacent tiers are displaced from each other
circumferentially, preferably centrally, so that a loop 12 of the
upper tier is centrally located between two loops 15 of the lower
tier, and vice versa. The inner ends of adjoining filaments, such
as 13 and 14, are anchored in central column 11 and the outer ends
of those filaments are joined or abutted to form a closed elongated
loop. The outer ends of filaments 13 and 14 are bent toward each
other to form short circumferentially extending portions 18 and 19
respectively, and then 180.degree. in the same plane to form
oppositely extending circumferential portions 20 and 21
respectively. The extreme ends of portions 20 and 21 are bent
radially outwardly into hooks 22. The wires of each loop may be
joined at the crowns of the open loops formed by bent portions 18
and 20 of wire 13 and 19 and 21 of wire 14, as by tying the wires
over the loops. Those circumferentially bent portions 20 and 21
form a stop or barrier which prevents hooks 22 from penetrating the
wall 24 of the passageway 10 sufficient to puncture it.
[0181] As shown in FIG. 33, The filaments in each tier are
positioned in pairs at the desired spacing around column 11,
enclosed in a metal sleeve 50, and are welded thereto at an end of
the sleeve. The sleeve 50 with filaments attached is then crimped
on column 11. Column 11 is hollow, and preferably rigid, having a
central cavity 51 running therethrough.
[0182] The embodiment of the filter described above with regard to
FIG. 33 may be modified to be a filter having enhanced echogenic
properties characteristics or features. This filter embodiment may
be modified with enhanced echogenic characteristics including one
or more than one of: (a) a modification to one or more components
of the filter to enhance the echogenic characteristics of the
component; (b) formation of dimples into a component surface of
sufficient number and scaled to a suitable size, shape, orientation
and pattern for use with intravascular ultrasound systems; (c)
protrusions formed in, placed on or joined to a filter surface; (d)
roughening one or more surfaces of a filter, for example using a
chemical process, a laser or bead blasting technique; and (e)
altering one or more steps of a filter manufacturing technique to
introduce cavities, voids or pockets to locally modify or adapt one
or more acoustic reflection characteristics to improve echogenicity
in one or more specific regions of a filter. In other aspects, the
filter illustrated and described in FIG. 33 may be modified
according to FIGS. 1-9 above.
[0183] In some aspects, any of the above described filters may be
modified to include hybrid or dual mode features. One example of a
dual mode feature is one that is both radio opaque and also
echogenic. In still another aspect, the above described filters may
also include a material capture structure as described below, with
or without one or more imaging modes as described herein.
[0184] In still other alternative embodiments, there is provided a
material capture structure having one or more echogenic
enhancements alone or in combination with radiopaque enhancements.
In one aspect, the filter structure used in a filter includes both
echogenic and radio opaque enhancements.
[0185] An one aspect, the filter includes material capture
structure in the IVC filter will be viewable under fluoroscopic and
ultrasound imaging modalities, including appropriate echogenic
characteristics to enhance the view of the status or condition of
the material capture structure while using IVUS. Enabling the
material capture structure to be viewed will allow the physician to
appropriately center and verify placement of a filter.
[0186] In one aspect, the filter elements or structures are doped
to incorporate one or more of echogenic or radio opaque materials
or treatments. In one aspect, the filaments or strands or other
structures used to form the filter structure or webbing of the
filter includes a radiopaque material having high echogenic
properties, such as tungsten or gold, but not limited to
either.
[0187] In other embodiments, one or more filaments or portions of a
filament within a material capture structure includes one or more
non-metallic echogenic features, such as those described elsewhere
in this specification. For example, a filament or portion thereof
may include air pockets either added to the material or by the use
of materials with entrained air or gas that are used. In one
embodiment, an ePTFE suture has echogenic properties due to air
content of the ePTFE material. In other aspects, a suture material
or a filament or polymer strand may also include
dimpled/roughened/matrix/sponge materials, additives, or
modifications to provide or enhance the overall echogenic nature of
the suture, filament, material or material capture structure, in
whole or in part.
[0188] In one aspect, these additional materials may assist the
physician in centering or placing a filter within a vessel. In
another aspect, this improvement is used in conjunction with IVUS
will enable the adequate viewing of the filter portion of the
filter and will allow for co-registration of filter placement along
with an accurate entry/removal of the catheter through the webbing
of the filter.
[0189] The advantages of this inventive aspect of a filter include,
for example and not limitation, filter placement, accurate
representation of filter location, ease of introducing/retracting
catheter, more viewable space for more accurate assessments,
ability to co-register filter location with IVUS and/or ability to
better place filter in desired location.
[0190] Still other aspects of the use of the innovative filter
include, for example, deployment of filters, positioning of
filters, sizing of filters, and estimated treatment lengths as well
as suture and/or material capture structure visibility. In still
other aspects of the use of the innovative filter include, for
example, deployment of a vena cava filter, positioning of an IVC
filter, sizing of an IVC filter, and estimated treatment lengths as
well as enhanced suture visibility.
[0191] In one embodiment, there is an IVC filter delivery system
with an enclosed IVC filter. This filter would have a mesh, suture,
web or other material capture structure suited to the anticipated
filter use. The mesh, suture, web or other material capture
structure has one or more components that is doped with a highly
radiopaque material for better visibility under flouro and good
echogenicity for better viewing under IVUS guidance. In still
further alternative embodiments, the techniques described above may
be applied to one or more material capture structure described in
U.S. Patent Application Publication No. US 2008/0147111 entitled
"Endoluminal Filter with Fixation" filed Jun. 4, 2008 as U.S.
patent application Ser. No. 11/969,827, (the "'7111 publication")
incorporated herein by reference in its entirety for all purposes.
More particularly, the aspects of modifying a material capture
structure to exhibit radio opaque, echogenic of combinations of
radio opaque and echogenic characteristics may be applied to the
various embodiments illustrated and described in FIGS. 30-34B,
38A-38B, 39-67, and 83-87. In one particular aspect, the
filament/strand/suture 461 shown in FIG. 58 of the '7111
publication may be coated or doped as described above alone or in
combination with the illustrated pharmacological coating 466.
[0192] In still another alternative aspect, any of the material
capture structures in the '7111 publication may be combined with
any of the filters illustrated and described in FIGS. 9-33. The
material capture structures may be joined to the wires or other
supports in the filters described herein to provide additional
kinds of filtering capabilities in addition to or in place of the
filtering capabilities of the filter so described.
[0193] In some embodiments, a pressure sensor and/or an
intravascular ultrasound (IVUS) transducer can be added to or
incorporated into a delivery system and method for use with any of
the filters described herein. The pressure sensor can be used to
measure the pressure at various positions within the vasculature,
which can be used to determine blood flow, while the intravascular
ultrasound (IVUS) transducer can be used to measure fluid flow
and/or provide imaging within the vessel. These activities can be
performed in cooperation with any of the filter embodiments
described herein. In some embodiments, the pressure sensor and/or
IVUS transducer can be incorporated into the guidewire at one or
more locations, such as the distal end or distal portion of a
guidewire, as described in U.S. Pat. No. 8,277,386, U.S. Pat. No.
6,106,476 and U.S. Pat. No. 6,780,157 which are hereby incorporated
by reference in their entireties for all purposes, as well as being
incorporated into intermediate and proximal portions of the
guidewire. The guidewire with the pressure sensor and/or the IVUS
transducer can be used much like a normal guidewire to help
navigate the delivery device through the vasculature, with the
added benefit of providing pressure measurements and ultrasound
imaging to help in the navigation, to visualize the device
placement site, and to monitor and ensure proper device deployment.
In some embodiments, the IVUS transducer generates image slices as
it is advanced and retracted which can then be assembled together
to form a three dimensional reconstruction of the vasculature
and/or the evice within the vasculature. In some embodiments, the
guidewire with the pressure sensor and/or IVUS transducer can be
fastened to a catheter in a similar manner to that described below
for a catheter having a pressure sensor and/or IVUS transducer that
is fastened to another catheter.
[0194] FIGS. 34A-34C illustrate an example of a guidewire X100
having both a pressure sensor X102 and an IVUS transducer X104
located at the distal portion of the guidewire X100. In some
embodiments, the pressure sensor X102 can be made from a
semiconductor material, such as silicon, that is formed into a
diaphragm and can be located proximally of the distal tip, while
the IVUS transducer X104 can be located at the distal tip of the
guidewire X104.
[0195] In some embodiments, the pressure sensor and/or IVUS
transducer can be located on a catheter in a similar configuration
to the guidewire. For example, the IVUS transducer can be located
on the distal tip of the catheter while the pressure sensor(s) can
be located proximally of the IVUS transducer at one or more
locations along the catheter body, from the distal portion of the
catheter to an intermediate portion of the catheter to the proximal
portion of the catheter. The pressure and/or imaging catheter can
be used in parallel with the delivery or retrieval device or any
other catheter that is inserted into the vasculature. In some
embodiments, the pressure and/or imaging catheter can be fastened
to the delivery or retrieval device or other catheter by, for
example, enclosing both catheters in a sheath or larger catheter or
by fusing the two catheters together. For example, U.S. Pat. No.
6,645,152 and U.S. Pat. No. 6,440,077, both to Jung et al. and
hereby incorporated by reference in their entireties for all
purposes, discloses an intravascular ultrasound catheter joined
together in parallel with a vena cava filter delivery device to
guide placement of the filter in the vena cava. The pressure and/or
imaging catheter can be used for the same purposes as the pressure
and/or imaging guidewire.
[0196] FIGS. 35A-35D illustrate two embodiments of an intravascular
ultrasound catheter X200 joined together in parallel with a
catheter X202 that can be used, for example, to deliver a device to
a location with the vasculature, such as a vena cava filter to the
vena cava. The intravascular ultrasound catheter X200 can have an
IVUS transducer X204 located on the distal portion of the IVUS
catheter X200. The IVUS transducer X204 can be a solid state
transducer that is disk shaped or cylindrically shaped with a hole
to allow passage of a guidewire X206 or other device through the
IVUS catheter X200. As shown in FIGS. 35A and 35B, the IVUS
catheter X200 and the delivery catheter X202 can be joined together
in parallel without a sheath by adhering or fusing the two
catheters together. FIGS. 35C and 35D illustrate the same IVUS
catheter X200 and delivery catheter X202 fastened together using a
sheath X208.
[0197] In some embodiments as illustrated in FIGS. 36A and 36B, the
pressure sensor and/or IVUS transducer can be integrated into the
delivery or retrieval catheter X300 or device itself. In one
aspect, the device is any of the filters having enhanced
capabilities described herein. For example, the IVUS transducer
X302 can be integrated into the distal tip or end of the catheter
X300 or device. The pressure sensor X304 can be located on a distal
portion of the catheter shaft proximally of the IVUS transducer
X302. A wire can extend from the IVUS transducer X302 and/or
pressure sensor X304 to one or more connectors X306 located at the
proximal end of the catheter X300. The connector(s) X306 can be
used to connect the IVUS transducer X302 and/or pressure sensor
X304 to an imaging system and/or processing system. In the
illustrated embodiment, the catheter X300 can be used to deliver a
vena cava filter X308 to the vena cava. The catheter X300 can
additionally have a telescoping sleeve or pusher rod to deploy the
vena cava filter X308, or alternatively, the outer catheter sheath
can be retracted to deployed the filter. The IVUS transducer can
provide positioning guidance and determine the relative location of
the filter by advancing and retracting the IVUS transducer X302 on
the catheter X300 to generate a plurality of image slices that can
be assembled to reconstruct a three dimensional image.
[0198] Use of the ultrasound imaging system allows the operator to
deliver the device without fluoroscopy or using less fluoroscopy,
thereby reducing the radiation exposure to the patient, while
allowing more accurate evaluation of the vasculature, aiding
placement of the device and allowing confirmation that device
placement was proper. The imaging can be used to aid in the
deployment of the filters or other devices. The vasculature and
implant location can be imaged prior to deployment, after
deployment and/or during deployment. The imaging can be used to aid
in positioning of the filter or device within the vasculature. The
imaging can be used to image the deployment location and determine
the appropriate sizing of the filter or other device. The imaging
can be used to help estimate treatment duration.
[0199] Although an imaging systems described above have been
ultrasound based, other imaging systems can be used instead or in
addition. For example, the imaging system can be based on
intravascular ultrasound (IVUS), Forward-Looking IVUS (FLIVUS),
optical coherence tomography (OCT), piezoelectric micro-machined
ultrasound traducer (PMUT), and FACT.
[0200] Additional aspects of the formation and use of echogenic
materials is made with reference to the following US patents and
patent Publications, each of which is incorporated herein by
reference in its entirety: US 2010/0130963; U.S. Pat. Nos.
5,921,933; 4,276,885; 4,572,203; 4,718,433; 4,442,843; 5,327,891;
U.S. Pat. No. 4,401,124; U.S. Pat. Nos. 4,265,251; 4,466,442;
4,718,433; 5,081,997; 5,289,831; and 5,201,314. Additional details
of various filter designs described herein may be obtained with
reference to the following U.S. Pat. Nos. 3,952,747; 4,817,600;
5,059,205; 5,242,462; U.S. Pat. No. 6,620,183; U.S. Pat. No.
6,217,600; U.S. Pat. Nos. 8,273,099; 4,494,531; 4,425,908;
4,832,055; 5,133,733; 3,540,431; 5,344,427; 5,725,550; 4,619,246;
4,990,156; 5,234,458; and 4,643,184, each of which is incorporated
herein by reference in its entirety.
* * * * *