U.S. patent application number 11/081410 was filed with the patent office on 2005-09-15 for slideable vascular filter.
Invention is credited to Finander, Brian V., Kusleika, Richard S..
Application Number | 20050203569 11/081410 |
Document ID | / |
Family ID | 22273499 |
Filed Date | 2005-09-15 |
United States Patent
Application |
20050203569 |
Kind Code |
A1 |
Kusleika, Richard S. ; et
al. |
September 15, 2005 |
Slideable vascular filter
Abstract
A collapsible medical device for use, e.g., as a vascular
filter. The device includes a mandrel having a distal end and a
stop spaced proximally of the distal end. A proximal length of the
mandrel extends proximally of the stop and a distal length of the
mandrel extends distally of the stop. A functional element (e.g., a
vascular filter) has a radially expandable body and includes a
proximal slider and a distal slider. The proximal and distal
sliders are slidable along the mandrel independently of one another
such that the distance between the proximal slider and distal
slider can be varied to effect different configurations of the
functional element. In one method of using such a device, the
functional element is urged distally to a treatment site by urging
the mandrel distally. This causes the stop to exert a distal
biasing force on the distal slider, which acts against a
restorative force of the functional element to axially elongate the
functional element and reduce friction between the functional
element and a wall of the vessel.
Inventors: |
Kusleika, Richard S.; (Eden
Prairie, MN) ; Finander, Brian V.; (Vadnais Heights,
MN) |
Correspondence
Address: |
POPOVICH, WILES & O'CONNELL, PA
650 THIRD AVENUE SOUTH
SUITE 600
MINNEAPOLIS
MN
55402
US
|
Family ID: |
22273499 |
Appl. No.: |
11/081410 |
Filed: |
March 16, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11081410 |
Mar 16, 2005 |
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10060271 |
Jan 30, 2002 |
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10060271 |
Jan 30, 2002 |
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PCT/US99/19942 |
Aug 27, 1999 |
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Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61F 2230/0006 20130101;
A61F 2/0108 20200501; A61F 2250/0098 20130101; A61F 2/011 20200501;
A61F 2002/016 20130101 |
Class at
Publication: |
606/200 |
International
Class: |
A61F 002/06 |
Claims
What is claimed is:
1. A collapsible medical device comprising: a) a mandrel having a
distal end and a stop spaced proximally of the distal end, a
proximal length of the mandrel extending proximally of the stop and
a distal length of the mandrel extending distally of the stop; and
b) a functional element comprising a radially expandable body
having a proximal slider and a distal slider, the proximal slider
being slidably carried along the proximal length of the mandrel and
the distal slider being slidably carried along the distal length of
the mandrel, the proximal and distal sliders being slidable along
the mandrel independently of one another such that the distance
between the proximal slider and distal slider can be varied to
effect different configurations of the functional element.
2. The medical device of claim 1 wherein the functional element has
an expanded configuration and is capable of being collapsed for
passage along a lumen, the functional element being adapted to
resiliently return toward the expanded configuration in the absence
of any biasing force.
3. The medical device of claim 1 wherein the body of the functional
element assumes a radially reduced configuration when the distance
between the proximal slider and the distal slider is increased.
4. The medical device of claim 3 wherein the stop abuts the
proximal slider and exerts a proximal biasing force thereon, such
proximal biasing force acting against a restorative force of the
body to axially elongate and radially reduce the body.
5. The medical device of claim 3 wherein the stop abuts the distal
slider and exerts a distal biasing force thereon, such distal
biasing force acting against a restorative force of the body to
axially elongate and radially reduce the body.
6. The medical device of claim 1 further comprising a control
sheath, the body being collapsed within the sheath with the
proximal and distal sliders spaced from one another.
7. The medical device of claim 5 wherein a wall of the control
sheath exerts a biasing force against a radially restorative force
of the body, such biasing force maintaining a space between the
proximal and distal sliders.
8. A collapsible medical device comprising: a) a mandrel having a
distal end and a stop spaced proximally of the distal end, a
proximal length of the mandrel extending proximally of the stop and
a distal length of the mandrel extending distally of the stop; and
b) a functional element comprising a radially expandable body
having a radially expanded configuration and adapted to resiliently
assume the radially expanded configuration in the absence of a
countervailing biasing force, the body being attached to the
mandrel by a proximal slider and a distal slider, the proximal
slider being slidably carried along the proximal length of the
mandrel and the distal slider being slidably carried along the
distal length of the mandrel, the proximal and distal sliders being
slidable along the mandrel independently of one another such that
the distance between the proximal slider and distal slider can be
varied to effect different configurations of the body.
9. A collapsible medical device comprising: a) a mandrel having a
distal end and a stop spaced proximally of the distal end, a
proximal length of the mandrel extending proximally of the stop and
a distal length of the mandrel extending distally of the stop; and
b) a functional element formed of a resilient tubular braid which
has a preferred radially expanded configuration but will assume a
radially reduced profile upon axial elongation, proximal and distal
sliders being attached to the tubular braid with a length of the
braid extending therebetween, the proximal slider being slidably
carried along the proximal length of the mandrel and the distal
slider being slidably carried along the distal length of the
mandrel, the proximal and distal sliders being slidable along the
mandrel independently of one another.
10. The medical device of claim 9 wherein the stop has an external
diameter larger than an internal diameter of either the proximal
slider or the distal slider.
11. The medical device of claim 9 wherein the stop is sized to urge
distally against the distal slider upon distal urging of the
mandrel, such distal urging thereby axially elongating the
functional element to facilitate its advancement along a lumen.
12. A filter system for temporary deployment in a channel of a
patient's body, comprising: a) a mandrel having a distal end and an
enlarged diameter stop spaced proximally of the distal end; and b)
a filter formed of a resilient tubular braid and including proximal
and distal sliders, the proximal slider being slidably carried
along the mandrel proximally of the stop and the distal slider
being carried along the mandrel between the stop and the distal end
of the mandrel, the filter having a collapsed configuration wherein
the sliders are spaced from one another a first distance along the
mandrel and the filter has a first diameter, and an expanded
configuration wherein the sliders are spaced a second, shorter
distance along the mandrel and the filter has a second diameter,
the first diameter being less than the second diameter.
13. The filter of claim 12 wherein each of the proximal and distal
sliders comprises an annular collar having an inner diameter larger
than an outer diameter of the mandrel but smaller than an outer
diameter of the stop, the stop thereby serving to limit movement of
the sliders.
14. The filter of claim 12 wherein the proximal and distal sliders
are slidable along the mandrel independently of one another.
15. The filter of claim 12 wherein the stop abuts the proximal
slider and exerts a proximal biasing force thereon, such proximal
biasing force acting against a restorative force of the filter to
axially elongate and radially reduce the filter.
16. The filter of claim 12 wherein the stop abuts the distal slider
and exerts a distal biasing force thereon, such distal biasing
force acting against a restorative force of the filter to axially
elongate and radially reduce the filter.
17. A method of employing a medical device in a lumen of a vessel,
comprising: a) providing a collapsible medical device comprising a
mandrel having a distal end and a stop spaced proximally of the
distal end; and a functional element formed of a resilient tubular
braid and including proximal and distal sliders, the proximal
slider being slidably carried along the mandrel proximally of the
stop and the distal slider being carried along the mandrel between
the stop and the distal end of the mandrel; b) inserting the distal
end of the mandrel in the lumen and urging the functional element
distally along the lumen to a treatment site by urging the mandrel
distally such that the stop engages the distal slider and exerts a
distal biasing force thereon, such distal biasing force acting
against a restorative force of the functional element to axially
elongate the functional element and reduce friction between the
functional element and a wall of the vessel.
18. The method of claim 17 wherein the proximal slider and distal
slider are permitted to slide along the mandrel independently of
one another.
19. The method of claim 17 further comprising allowing the
functional element to resiliently self-expand radially and
self-contract axially by ceasing the distal urging of the mandrel
when the functional element reaches the treatment site.
20. The method of claim 17 or claim 19 further comprising moving
the functional element proximally along the lumen by withdrawing
the mandrel proximally such that the stop engages the proximal
slider and exerts a proximal biasing force thereon, such proximal
biasing force acting against a restorative force of the filter to
axially elongate the filter and reduce friction between the
functional element and the wall of the vessel.
Description
FIELD OF THE INVENTION
[0001] The present invention provides a medical device which can
employed in a minimally invasive medical procedure, e.g., by
deploying it in a blood vessel through a catheter. While a variety
of such medical devices can be made in accordance with the
invention, the invention is particularly useful as a filter for use
in a blood vessel or other channel in a patient's body.
BACKGROUND OF THE INVENTION
[0002] Filters can be deployed in channels or vessels in patient's
bodies in a variety of medical procedures or in treating certain
conditions. For example, rotating burrs are used in removing
atheroma from the lumen of patients' blood vessels. These burrs can
effectively dislodge the atheroma, but the dislodged material will
simply float downstream with the flow of blood through the vessel.
Filters can be used to capture such dislodged material before it is
allowed to drift too far downstream, possibly occluding blood flow
through a more narrow vessel.
[0003] Some researchers have proposed various traps or filters for
capturing the particulate matter released or created in such
procedures. However, most such filters generally have not proven to
be exceptionally effective in actual use. These filters tend to be
cumbersome to use and accurate deployment is problematic because if
they are not properly seated in the vessel they can drift to a more
distal site where they are likely to do more harm than good. In
addition, these filters are generally capable of only trapping
relatively large thrombi and are not effective for removing smaller
embolic particles from the blood stream.
[0004] The problems with most temporary filters, which are intended
to be used only during a particular procedure then retracted with
the thrombi trapped therein, are more pronounced. Even if the trap
does effectively capture the dislodged material, it has proven to
be relatively difficult or complex to retract the trap back into
the catheter through which it was delivered without simply dumping
the trapped thrombi back into the blood stream, defeating the
purpose of the temporary filter device. For this reason, most
atherectomy devices and the like tend to aspirate the patient's
blood during the procedure to remove the dislodged material
entrained therein.
[0005] One promising filter design which overcomes many of these
difficulties is shown in International Publication No. WO
96/01591(the publication of PCT International Application No.
PCT/US95/08613), the teachings of which are incorporated herein by
reference. Generally, this reference teaches a trap which can be
used to filter particles from blood or other fluid moving through a
body vessel. In one illustrated embodiment, this trap includes a
basket 270 which can be deployed and retracted through a catheter
or the like, making it particularly suitable for use in minimally
invasive procedures such as angioplasty or atherectomy procedures.
The fact that this trap is optimally carried on a mandrel 260
further enhances its utility as most common angioplasty balloons
and atherectomy devices are used in conjunction with such mandrels.
While this trap is very useful and shows great promise in many
common procedures, it may be possible to improve the ease with
which it may be deployed and/or retracted.
[0006] Some medical devices are also permanently deployed in a
patient's vessel, but properly positioning these devices at the
desired treatment site using minimally invasive techniques can be
cumbersome. For example, occlusion devices can be used to occlude
an arterial vessel or a septal defect. Some of these occlusion
devices may radially expand into an enlarged configuration wherein
they substantially fill the lumen of the vessel or extend over the
margins on either side of a septal defect. When deploying these
occlusion devices through a delivery catheter, though, the friction
between the occlusion device and the wall of the catheter can make
it difficult to deploy the device at a precisely selected location.
These problems are even more pronounced in longer catheters
tracking through more tortuous paths.
SUMMARY OF THE INVENTION
[0007] The present invention provides a medical device which can
easily be deployed and retracted during a minimally invasive
medical procedure. In one preferred embodiment, the medical device
may take the form of a filter useful in any channel of a patient's
body, be it in a blood vessel, urinary tract, or other type of
vessel.
[0008] One embodiment of the invention provides a collapsible
medical device including a mandrel and a functional element of any
desired shape to achieve a particular end. The mandrel has a distal
end and a stop spaced proximally of the distal end. A proximal
length of the mandrel extends proximally of the stop and a distal
length of the mandrel extends distally of the stop. The functional
element includes a radially expandable body having a proximal
slider and a distal slider. The proximal slider is slidably carried
along the proximal length of the mandrel and the distal slider is
slidably carried along the distal length of the mandrel. The
proximal and distal sliders are slidable along the mandrel
independently of one another such that the distance between the
proximal slider and the distal slider can be varied to effect
different configurations of the functional element.
[0009] A medical device in accordance with another embodiment of
the invention includes a mandrel and a suitably shaped functional
element. Like the prior embodiment, this mandrel has a distal end
and a stop spaced proximally of the distal end. A proximal length
of the mandrel extends proximally of the stop and a distal length
of the mandrel extends distally of the stop. The functional element
of this embodiment has a radially expandable body having a radially
expanded configuration and adapted to resiliently assume the
radially expanded configuration in the absence of a countervailing
biasing force. The radially expandable body is attached to the
mandrel by a proximal slider and a distal slider. The proximal
slider is slidably carried along the proximal length of the mandrel
and the distal slider is slidably carried along the distal length
of the mandrel. The proximal and distal sliders are slidable along
the mandrel independently of one another such that the distance
between the proximal and distal sliders can be varied to effect
different configurations of the body.
[0010] In one particular adaptation of the invention, the medical
device has a mandrel generally as described above and also includes
a functional element. The functional element of this embodiment is
formed of a resilient tubular braid which has a preferred radially
expanded configuration but will assume a radially reduced profile
upon axial elongation. Proximal and distal sliders are attached to
the tubular braid with a length of the braid extending
therebetween. The proximal slider is slidably carried along the
proximal length of the mandrel and the distal slider is slidably
carried along the distal length of the mandrel. The proximal and
distal sliders are slidable along the mandrel independently of one
another.
[0011] Yet another embodiment of the invention provides a filter
system which may be temporarily deployed in a channel of a
patient's body. This device includes a mandrel having a distal end
and an enlarged diameter stop carried proximally of the distal end.
A filter is formed of a resilient tubular braid and includes
proximal and distal sliders. The proximal slider is slidably
carried along the mandrel proximally of the stop and the distal
slider is carried along the mandrel between the stop and the distal
end of the mandrel. The filter has a collapsed configuration
wherein the sliders are spaced from one another a first distance
along the mandrel and the filter has a first diameter. The filter
also has an expanded configuration wherein the sliders are spaced a
second, shorter distance along the mandrel and the filter has a
second diameter. The filter's first diameter is less than its
second diameter.
[0012] The present invention also contemplates a method of
employing a medical device in a lumen vessel. This medical device
desirably comprises a mandrel having a distal end and a stop spaced
proximally of the distal end. It also includes a functional
element, which may be formed of a resilient tubular braid and
include proximal and distal sliders, with the proximal slider being
slidably carried along the mandrel proximally of the stop and the
distal slider being carried along the mandrel between the stop and
the distal end of the mandrel. The distal end of the mandrel is
inserted in the lumen of the vessel. The functional element is
urged distally along the lumen to a treatment site by urging the
mandrel distally such that the stop engages the distal slider and
exerts a distal biasing force thereon. This distal biasing force
acts against a restorative force of the functional element to
axially elongate the functional element and reduce friction between
the functional element and a wall of the vessel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a schematic perspective view of one medical device
in accordance with the invention in its deployed state;
[0014] FIG. 2 is a schematic side view of the medical device of
FIG. 1, also in its deployed state;
[0015] FIG. 3 is a schematic side view in partial cross section of
the medical device of FIGS. 1 and 2;
[0016] FIG. 4 is a schematic side view in partial cross section of
the medical device of FIGS. 1 and 2, but in a partially collapsed
configuration induced by urging the mandrel distally;
[0017] FIG. 5 is a schematic side view in partial cross section of
the medical device of FIGS. 1 and 2, but in a partially collapsed
configuration induced by proximal withdrawal of the mandrel;
[0018] FIG. 6 is a schematic isolation view in partial cross
section of the medical device of FIGS. 1 and 2, showing the
relationship between the mandrel, the stop and the distal
slider;
[0019] FIG. 7 is a schematic side view of an alternative medical
device of the invention in its deployed state;
[0020] FIG. 8 is a schematic side view in partial cross section of
the medical device of FIG. 7, but in a partially collapsed
configuration induced by withdrawing the mandrel proximally within
a vessel;
[0021] FIG. 9 is a schematic side view in partial cross section of
the medical device of FIG. 1, but in a partially collapsed
configuration induced by urging the mandrel distally within a
catheter;
[0022] FIG. 10 is a schematic side view in partial cross section of
the medical device of FIG. 1, but illustrating how the medical
device may be withdrawn using a retrieval catheter;
[0023] FIG. 11 is a schematic side view in partial cross section of
a medical device in accordance with another embodiment of the
invention in its deployed state; and
[0024] FIG. 12 is a schematic perspective view of a stop of the
invention which may be used to facilitate withdrawal of the mandrel
for permanent deployment of a medical device.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] FIGS. 1 and 2 are schematic illustrations of one medical
device in accordance with the present invention. This medical
device comprises a filter system 10 which can be deployed in a
channel in a patient's body. As noted above, this filter can be
used in any channel in a patient's body, including blood vessels,
the urinary tract or biliary tract and airways. This filter system
10 is optimally designed to be deployed in a patient's vessel in a
minimally invasive procedure, such as by introducing the filter
system into a blood vessel through an introducing catheter (not
shown in FIGS. 1 and 2).
[0026] The filter system 10 of the invention generally includes a
mandrel 20 and a filter 50. Conceptually, the mandrel 20 can be
thought of as having a primary function of positioning and
controlling the deployment of the filter 50 while the filter can be
considered the primary therapeutic or functional element of the
system 10.
[0027] The mandrel 20 should be fairly flexible to allow the device
to be deployed in a curving body passageway without kinking or
otherwise inhibiting suitable deployment of the filter 50. While
the mandrel can be formed of any material having any dimension
suitable for the task for which the filter system 10 is to be
employed, in most circumstances, the mandrel 20 will comprise an
elongate metal wire. In one particularly preferred embodiment, the
mandrel 20 is formed of nitinol, a roughly stoichiometric alloy of
nickel and titanium having excellent "superelastic" properties. The
use of nitinol in medical guidewires and related applications is
well known in the art and need not be discussed in detail here. If
so desired, the distal-most length of the mandrel may include a
flexible helically wound coil 22 extending thereover. The use of
such helical coils to enhance flexibility of the distal tip is well
known in the guidewire art.
[0028] The mandrel 20 has an enlarged diameter stop 40 attached
thereto. The stop 40 is spaced proximally from the distal tip 25 of
the mandrel 20. Desirably, the stop 40 is spaced proximally of the
proximal end of the helical coil 22 of the mandrel. This permits
the distal slider 60 of the filter 50 to slide relatively freely
and unencumbered along the length of the mandrel distally of the
stop.
[0029] The stop 40 can be formed of any desired material and can be
attached to the mandrel 20 in any desired fashion. The stop should
be attached to the mandrel relatively securely, though, as the stop
will be used to urge the filter 50 within the lumen of the vessel
in which the system 10 is to be deployed. As an example, the stop
40 may comprise a standard radiopaque marker band which has been
securely crimped on the mandrel 20 and/or attached to the mandrel
using an adhesive or solder. The precise length and shape of the
stop 40 is not critical. The drawings illustrate the stop 40 as a
relatively short cylindrical body attached about the circumference
of the mandrel. However, the stop 40 may have a more bulbous shape
and could, in theory, even be formed integrally with the
mandrel.
[0030] The stop 40 effectively divides the mandrel into distal and
proximal lengths. The distal length 30 of the mandrel can be
thought of as that length which extends distally from the stop 40
to the distal tip 25 of the mandrel. Likewise, the proximal portion
35 of the mandrel 20 can be thought of as comprising the length of
the mandrel extending proximally from the stop 40 to the proximal
end of the mandrel.
[0031] The filter 50 shown in FIGS. 1-5 has an elongate, generally
tubular body 52 which extends from a distal slider 60 proximally to
a proximal slider 65. The body 52 of the filter can be formed of
any material suitable for the application at hand. In many
applications, e.g., filtering blood within a patient's vasculature,
the filter body 52 typically comprises a length of a braided
tubular fabric. The use of a tubular braid of nitinol to make
medical devices is described in some detail in International
Publication No. WO 96/01591, the teachings of which were
incorporated above by reference. Briefly speaking though, this
process can employ a tubular braid of a fabric comprising two sets
of nitinol wires wrapped helically about a mandrel, with one set of
wires being wrapped spirally about the mandrel in one direction and
the other set being wrapped in the other direction. This braid is
then placed in contact with a molding surface of a molding element
which defines the shape of the desired functional element. By heat
treating the fabric in contact with the molding surface of the
molding element, one can create a functional element having
virtually any desired shape.
[0032] The body 52 of the filter 50 desirably is made of a fairly
flexible, resilient material. In particular, the filter 52
desirably has a radially expanded configuration, e.g., the shape
shown in FIGS. 1-3, which the device will tend to resiliently
assume in the absence of any countervailing biasing force. A body
52 formed of a nitinol tubular braid which has been heat set into
the desired shape should suit this purpose well.
[0033] In the filter system 10 shown in FIGS. 1-5, the body 52 of
the filter 50 assumes a generally tubular shape having tapered
proximal and distal ends. The outer diameter of the generally
cylindrical middle length of the body 52 should be sized to
substantially fill the lumen of a vessel to ensure that the filter
will effectively trap any emboli which may be entrained in the
patient's bloodstream. As will be discussed in more detail below,
an alternative configuration of a filter body 152 is illustrated in
FIGS. 7 and 8 and medical devices intended to achieve different
clinical objectives are shown in FIGS. 11 and 13. A variety of
other filter shapes, as well as shapes of other types of medical
devices should be readily apparent to one of ordinary skill in the
art in light of the present teachings.
[0034] The filter 50 is attached to or carried by the mandrel 20 by
means of a proximal slider 65 attached to the body 52 adjacent its
proximal end and a distal slider 60 attached adjacent the distal
end of the body 52. The distal slider 60 should be free to slide
along at least a proximal portion of the distal length 30 of the
mandrel while the proximal slider 65 should be free to slide along
at least a distal portion of the proximal length 35 of the mandrel.
For reasons discussed more fully below in connection with FIGS.
3-5, the stop 40 of the mandrel effectively defines a limit on the
range of motion of these sliders 60, 65.
[0035] While each of the sliders 60, 65 should be slidable along
its respective length of the mandrel, the sliders can take any
desired shape. In the illustrated embodiments, each slider
comprises a relatively thin ring which is carried about the
mandrel. The thin ring can be attached to the body 52 in any
desired fashion, such as by crimping or swaging the fabric of the
body between two layers of the ring or soldering, welding or
otherwise adhering the fabric to the ring. The structure of one
suitable distal slider is schematically illustrated in a more
detailed cross section in FIG. 6. The proximal slider may have
substantially the same configuration, but is not shown in this view
simply for purposes of clarity.
[0036] In the embodiment illustrated in FIG. 6, the distal slider
60 comprises a relatively rigid annular ring 61 having an inner
component 61a and an outer component 61b. One or both components of
the ring 61 is preferably formed of a radiopaque material to enable
a physician to better visualize the position of the slider 60
during a procedure. The inner component 61a of the ring is received
within the outer component 61b and defines an annular space
therebetween. The inner diameter of the inner component is larger
than the outer diameter of the mandrel 20 to facilitate sliding of
the ring 61 with respect thereto. Movement of the slider 60 with
respect to the mandrel can be further facilitated by coating one or
both of the inner surface of the inner component 61a and the outer
surface of the mandrel 20 with a friction-reducing coating, such as
Teflon or a lubricious hydrophilic coating.
[0037] A distal length of the fabric of the body 52 is received in
the annular space between the interior and exterior components 61a
and 61b of the ring. The fabric is held in place in this space in
any suitable manner, e.g. by means of a suitable solder or adhesive
or by crimping the fabric between the inner and outer components.
FIG. 6 schematically illustrates both approaches, with the fabric
being frictionally grasped between the two components of the ring
61 and held in place by a weldment or adhesive connection 62 at the
distal end of the ring.
[0038] FIGS. 3-5 schematically illustrate the filter system 10 of
FIGS. 1 and 2 in partial cross section. In particular, the filter
50 is shown in cross section while the mandrel 20 and its
components are shown in side view. This is intended to better
illustrate the interaction of the stop 40 of the mandrel and the
sliders 60, 65 of the filter 50.
[0039] In FIG. 3, the filter 50 is shown in its radially expanded
configuration, which it will tend to assume in the absence of any
countervailing biasing force. The stop 40 of the mandrel is
positioned within the body 52 of the filter and is not exerting any
biasing force on either of the sliders 60, 65.
[0040] In this configuration, the mandrel 20 can be moved
proximally and distally with respect to the filter 50 without
substantially affecting the shape or position of the filter. The
limits of this range of free movement of the mandrel with respect
to the filter are generally defined by the relationship between the
stop 40 and the sliders 60, 65. In particular, the mandrel can be
moved from a distal position wherein the stop 40 abuts but does not
exert any force on the distal slider 60 and a proximal position
wherein the stop 40 abuts, but does not exert any significant force
on, the proximal slider 65. This allows the filter 50 (or any other
functional element which is carried by the mandrel) to be fairly
precisely positioned within a patient's vessel and retain that
position even if the guidewire is moved slightly during use. This
can be advantageous in circumstances where other devices are
exchanged over the guidewire (e.g., during angioplasty and
atherectomy procedures).
[0041] The inner diameter of the generally annular collars defining
the sliders 60, 65 is desirably larger than the outer diameter of
the mandrel, as mentioned above. However, the inner diameter of
these sliders should be smaller than the outer diameter of the stop
40. In this fashion, the stop serves to limit movement of the
sliders. As a consequence, the stop 40 serves as an effective limit
on proximal movement of the distal slider 60 and distal movement of
the proximal slider 65. Apart from this relationship with the
slider 40 and the fact that both sliders are indirectly linked to
one another by the body 52 of the filter, the proximal and distal
sliders are slidable along the mandrel essentially independently of
one another.
[0042] The advantage of this arrangement is illustrated in FIGS. 4
and 5. In FIG. 4, the mandrel 20 is being urged distally (to the
left in this view, as illustrated by the arrow) and urges distally
against the distal slider 60. This exerts a distal biasing force
against the distal end of the body 52 of the filter. In theory, if
the filter were used in a frictionless environment, the filter
would travel with the mandrel without any appreciable alteration in
the shape of the body 52. In most clinical applications, though,
this is not the case. Instead, there is typically some force
restraining completely free movement of the filter within the
channel of the patient's body. As schematically shown in FIG. 3,
the body 52 of the filter may resiliently expand into physical
contact with the interior surface of the vessel V. This contact
with the vessel wall will tend to hold the filter 50 in place as
the stop of the mandrel slides proximally and distally between the
two sliders 60, 65. When the mandrel is urged distally until it
exerts a distal force against the distal slider 60 (as shown in
FIG. 4), this force will tend to axially elongate the body 52.
[0043] Resilient tubular braids tend to assume a radially reduced
profile upon axial elongation. (This property and some of its
implications are discussed in International Publication No. WO
96/01591, mentioned previously. As a consequence, when the mandrel
20 is urged distally to push distally against the distal slider 60,
this distal force acts against the restorative force of the
resilient braid, which would otherwise bias the braid into its
expanded configuration (FIG. 3). By overcoming this restorative
force with a countervailing distal force, the body 52 will tend to
both axially elongate and assume a radially reduced profile. This,
in turn, reduces the force with which the body engages the wall of
the vessel V and reduces friction between the filter 50 and the
vessel. Hence, urging the mandrel distally to move the filter 50
distally will, at the same time, reduce friction between the filter
and the vessel wall to further facilitate advancement of the filter
along the vessel's lumen. This requires less force to push the
filter distally, enabling the mandrel to be smaller and reducing
the outer diameter of the collapsed device, making deployment in
smaller vessels feasible. In addition, the reduced friction between
the filter and the vessel wall limits damage to the intima of the
vessel, permitting the filter to be deployed and moved with a
minimum of trauma.
[0044] FIG. 5 is similar to FIG. 4, but schematically illustrates
what happens upon proximal retraction of the mandrel. In this
drawing, the stop 40 of the mandrel abuts against and exerts a
proximal biasing force on, the proximal slider 65 of the filter 50.
As discussed above in connection with FIG. 4, this proximal biasing
force will act against the restorative force of the body 52 to
axially elongate and radially reduce that body. This permits the
device to be withdrawn proximally along the lumen of the vessel
either for repositioning at a more proximal location or for
withdrawal from the patient's body at the end of the procedure.
[0045] As can be seen by comparing FIG. 3 with FIGS. 4 and 5, the
proximal and distal sliders 60, 65 are free to move relatively
independently of one another, limited primarily by their indirect
link to one another through the body 52 of the filter. For example,
when the mandrel 20 is urged distally against the distal slider 60
(FIG. 4), the proximal slider will slide proximally along the
proximal length 35 of the mandrel. Similarly, when the mandrel is
withdrawn proximally to urge proximally against the proximal slider
65, the distal slider will be free to drift distally along the
distal length 30 of the mandrel. Ideally, there should be a
sufficient distance between the distal shoulder of the stop 40 and
the proximal end of the helical coil 22 at the distal end of the
mandrel.
[0046] Another salient aspect of the device highlighted in FIGS.
3-5 is that the spacing between the sliders 60 and 65 changes in
response to the mandrel acting against one of the sliders. Looking
first at FIG. 3, the proximal and distal sliders are spaced a first
distance from one another, with the body 52 engaging the wall of
the vessel. When the stop 40 of the mandrel urges against one of
the sliders, though, the body 52 will tend to axially elongate and
the distance between the two sliders will increase.
[0047] It should be understood that the change in shape between the
radially expanded configuration shown in FIG. 3 and the radially
reduced configurations in FIGS. 4 and 5 has been exaggerated to
highlight this change. For example, in FIGS. 4 and 5, the body 52
of the filter is shown as being spaced completely away from the
wall of the vessel. In most clinical circumstances, though, the
body of the filter will still tend to at least lightly engage the
intima of the vessel and the change in shape of the body likely
will be less dramatic.
[0048] FIGS. 9 and 10 schematically illustrate certain advantages
of the present invention when deploying and retrieving the device
in a body channel using a catheter. FIG. 9 schematically shows the
device of FIGS. 1-5 being deployed through a catheter C. In
particular, a length of the mandrel 20 and the entirety of the
filter 50 is received within the lumen of the catheter C. The
mandrel 20 is being urged distally to exit the distal end of the
catheter C. The stop 40 is exerting a distal biasing force against
the distal slider 60 within the relatively close confines of the
catheter C. The body 52 of the filter 50 will exert an outward
force against the interior surface of the catheter C, increasing
friction between the filter and the catheter C. The distal biasing
force of the stop 40 acting against the slider 60 will tend to
axially elongate and radially reduce the body 52 of the filter,
thereby reducing friction between the filter and the catheter C.
This can significantly ease the deployment of the device through
the catheter C. FIG. 10 schematically illustrates retrieval of the
device of FIGS. 1-5 and 9 which has already been deployed in a
patient's vessel. In particular, the filter 50 is being withdrawn
proximally into the lumen of the catheter C. This can be initiated
by positioning the distal end of the catheter C just proximal of
the proximal slider 65 and then moving the catheter C with respect
to the stop 40. This can be accomplished either by urging the
catheter C distally or withdrawing the mandrel 20 proximally, as
the operator sees fit at the time.
[0049] The catheter C will frictionally engage and will tend to
radially compress the body 52 of the filter. As a consequence, the
slider 65 will be brought in contact with the stop 40. Further
movement of the catheter C with respect to the mandrel will urge
more of the length of the body 52 into the lumen of the catheter C.
At the same time, the distal slider 60 may slide distally along the
distal length 30 of the mandrel, permitting the body 52 to axially
elongate in response to the radial compression induced by the
catheter C.
[0050] These two figures highlight some of the advantages of this
embodiment of the invention. In particular, the body 52 of the
filter will axially elongate and radially reduce in response to
movement of the mandrel 20 with respect to the catheter C. In
deploying the device (FIG. 9), the stop 40 urges distally against
the distal slider 60, effectively pushing the filter 50 distally
along the catheter C. In retrieving the device (either for
repositioning or for removal from the patient's body), the stop 40
can be seen as pushing proximally on the proximal slider 65. Again,
this biasing force will tend to axially elongate and radially
reduce the body 52 of the filter. This axial elongation and radial
reduction of the body 52 in FIGS. 9 and 10 reduces friction with
the lumen. In addition, the radial reduction of the body during
retrieval into the catheter C (FIG. 10) facilitates collapse of the
filter into the lumen of the catheter C, making it easier to
introduce the filter into the catheter. This same ability can also
be used advantageously in initially deploying the filter, as
explained below.
[0051] As noted above, FIGS. 7 and 8 illustrate an alternative
embodiment of the invention. There are numerous similarities
between the device shown in FIGS. 1-6 and that shown in FIGS. 7 and
8. In order to simplify discussion, elements in FIGS. 7 and 8
performing a function analogous to an element in FIGS. 1-6 bear the
same reference numeral, but incremented by 100. Hence, FIGS. 1-6
refer to a filter system 10 having a mandrel 20; FIGS. 7 and 8 show
a filter system 110 having a mandrel 120.
[0052] The primary difference between the filter 150 of FIGS. 7 and
8 and the filter 50 of FIGS. 1-6 is the shape of the filter in its
fully radially expanded configuration. The filter 50 has a
generally tubular body with spaced-apart tapered ends. In contrast,
the filter 150 of FIGS. 7 and 8 has a generally umbrella-shaped
body 152, with a proximal length of the fabric defining the body
being inverted and received within the interior of the distal
portion of the fabric. As a consequence, the distal slider 160 and
proximal slider 165 are positioned much more closely to one another
in the fully deployed filter 150, shown in FIG. 7, than are the
spacers 60, 65 in the fully deployed filter 50, shown in FIGS.
1-3.
[0053] FIG. 8 illustrates the filter 150 in an axially elongated,
radially reduced state induced by withdrawing the mandrel 120
proximally. When the mandrel 120 is withdrawn proximally within the
patient's vessel, the stop 140 will abut and urge proximally
against the proximal slider 165. In the embodiment of FIGS. 1-5, 9
and 10, this tends to axially elongate the body 52 of that filter
50 without any substantial change in the shape of the filter. The
filter 150 of FIGS. 7 and 8 is more complex in its fully deployed,
expanded state (shown in FIG. 7). Rather than simply axially
elongating and radially reducing the shape shown in FIG. 7, the
proximal length of the fabric which is received within the interior
of the distal portion of the fabric will tend to evert. The distal
portion of the fabric (i.e., the outer portion of the fabric shown
in FIG. 7) will tend to remain in place in frictional engagement
with the wall of the vessel during this process. As a consequence,
the shape of the interior surface of the umbrella will change first
without any significant change in the external shape.
[0054] As the mandrel continues to be withdrawn and the proximal
and distal sliders 165, 160 are moved farther apart, the body 152
will take on a shape which looks more like the shape of the filter
50 of the previous embodiment. Continuing to urge proximally
against the proximal slider 165 will further elongate the body
until it reaches a shape such as that schematically illustrated in
FIG. 8. This makes withdrawal of the trap easier, but care should
be taken to ensure that any particular material retained within the
interior of the umbrella-like body 152 is not inadvertently dumped
back into the patient's bloodstream. This can be done, for example,
by breaking down trapped thrombus using clot-busting drugs or by
aspirating the particulate material through a catheter before
proximally withdrawing the mandrel 120.
[0055] In one particularly useful process for withdrawing the
deployed filter 150 from a patient's bloodstream, a catheter C is
urged distally along the proximal length 135 of the mandrel until
the distal tip of the catheter (not shown in FIGS. 7 and 8) is
positioned in the interior of the umbrella-like filter body 152. If
necessary, any particulate material within that interior can be
aspirated through the catheter C and out of the patient's body.
Thereafter, the mandrel can be withdrawn proximally, drawing the
proximal slider 165 into the interior of the catheter C. As
discussed above in connection with FIG. 10, this will help collapse
the body 152 of the filter into the lumen of the catheter C. If so
desired, the catheter C can be held in the same position while the
rest of the filter 150 is drawn inside. Alternatively, the catheter
C and the mandrel can be withdrawn together as a unit a short
distance so that the distal tip of the catheter C is positioned
slightly proximal of the proximal edge of the deployed filter shown
in FIG. 7. This will further facilitate drawing the body 152 down
into the lumen of the catheter C. Once at least the majority of the
filter 150 is received within the lumen of the catheter C, the
catheter, the filter and the mandrel 120 can be withdrawn together
as a unit from the patient's body.
[0056] FIG. 11 shows a medical device which is similar to the
embodiment shown in FIGS. 1-5, 9 and 10. However, the shape of the
body 52' of the plug 50' has a significantly different shape from
the body 52 of the filter 50 discussed above. Whereas the majority
of the length of the filter 50 would assume a relatively constant
diameter if left unconstrained, the body 52' of the plug 50' has a
more complex shape. While this device can also be used to filter
fluid which is passing through a vessel, its design is particularly
well-suited to occlude a vessel either temporarily or
permanently.
[0057] A method for making and using a vascular occlusion device
having a shape similar to that of the body 52' of FIG. 11 is
disclosed in International Publication No. WO 96/01591, the
teachings of which were incorporated above. Briefly, though, this
body 52' includes a pair of spaced-apart enlarged diameter sections
separated by a central section having a reduced diameter. If so
desired, the surface of this device may be coated with a
thrombogenic agent or nylon fibers or the like can be attached to
the body 52'. Conversely, if the plug 50' or the filter 50 are to
be used solely for purposes of filtering fluids passing
therethrough and it is preferred that any blood passing through the
functional element not clot thereon, the body can be coated with an
anti-thrombogenic agent.
[0058] One of the difficulties encountered in using the vascular
occlusion device disclosed in International Publication No. WO
96/01591 is the friction between the body of the vascular occlusion
device and the catheter through which it is deployed. The stop 40
urging against the distal slider 60 of FIG. 11 will tend to axially
elongate and radially reduce the body 52' of the plug 50' as it is
urged along the catheter C. This will reduce friction between the
plug 50' and the catheter C, making it significantly easier to
deploy the device at the desired treatment site. The present design
also facilitates repositioning of the plug 50' if its initial
deployment is not precisely at the desired location. In particular,
withdrawing the mandrel 20 proximally will exert a proximal biasing
force on the proximal slider 65, facilitating withdrawal of the
device into the deployment catheter, much as discussed above in
connection with FIG. 10. Once the plug is sufficiently retracted
into the catheter, the catheter can be repositioned and the plug
can be deployed distally out of the catheter again at the new
location.
[0059] The plug 50' of FIG. 11 can be used as a temporary occlusion
device and withdrawn at the end of a procedure or treatment course.
In other circumstances, though, it may be preferred to more
permanently occlude the channel in which the plug 50' is deployed.
While the stop 40 abutting against the sliders 60, 65 facilitates
deployment and repositioning, the attachment of the stop 40 to the
mandrel 20 could effectively prevent one from removing the mandrel
from the plug.
[0060] The mandrel 20 can be withdrawn either partially or entirely
from the plug in a variety of different manners. For example, the
proximal portion 35 of the mandrel can be releasably attached to
the stop 40, e.g., by means of a threaded engagement therebetween.
Without somehow locking the distal section 30 against rotation
(e.g., by a splined connection between the distal section 30 and
the distal slider 60), though, it can be difficult to disconnect
these parts from one another.
[0061] FIG. 12 illustrates one preferred embodiment of a stop 40'
which may be used to withdraw the mandrel 20 while leaving the
filter 50 or plug 50`in place in the patient`s body. In the prior
embodiments, the stop 40 and the proximal slider 65 were both
essentially annular in shape, with the relatively constant outer
diameter of the stop being greater than the relatively constant
inner diameter of the slider. As a consequence, one cannot readily
withdraw the stop 40 from within the enclosure of the body 52 of
the filter 50.
[0062] The stop 40' of FIG. 12, however, can be withdrawn from the
interior of a filter 50, plug 50' or other device having a suitably
adapted proximal slider. The stop 40' includes an external thread
42' which extends spirally outwardly from the main body 44' of the
stop. The proximal slider (not shown in this view) has a threaded
internal surface which is sized and shaped to mate with the outer
thread 42' on the stop 40'. Aside from the spiral slot or keyway
shaped to receive the thread 42' of the stop, the inner diameter of
the proximal slider should be slightly greater than the outer
diameter of the body 44' of the stop but less than the maximum
diameter of the stop including the thread 42'. During normal
operation, this will ensure that the stop 40' will abut against the
proximal slider so the device will operate as described above.
[0063] If an operator decides to leave the filter 50 or plug 50' in
place, though, the mandrel can be withdrawn from the filter or plug
by pulling the mandrel proximally until the stop 40 lightly abuts
the proximal slider. Rotating the mandrel about its axis will
permit the thread 42' to travel along the slot in the proximal
slider. In this manner, the stop can be withdrawn through the
proximal slider and the mandrel can be completely removed from the
patient's body, leaving the medical device in place within the
vessel.
[0064] The present invention also contemplates a method of
employing a medical device in a channel in a patient's body. For
the sake of convenience, the following discussion will make
reference to FIG. 1-5 and the reference numbers used therein. It
should be understood, though, that this method can be used with any
of a wide variety of medical devices having different functional
elements (including the plug 50' and the drainage catheter 250
illustrated in other drawings) and need not be limited to a filter
system 10 having a filter 50 as its functional element.
[0065] In accordance with this method, the medical device is
introduced into a vessel in a patient's body. In the medical device
10 shown in FIGS. 1-5, this would comprise inserting the distal end
25 of the mandrel 20 into the lumen of the patient's vessel V. This
may be done either directly or, more commonly, by using an
introducer sheath. Such introducer sheaths are commonly used in
introducing medical devices for minimally invasive procedures. Once
the mandrel is introduced into the vessel, the mandrel can be urged
distally to introduce the functional element, i.e., filter 50 in
FIGS. 1-5, and to the vessel, as well. Using the filter system 10
of FIGS. 1-5, this can be accomplished simply by urging the mandrel
distally and allowing both the action of the stop 40 against the
distal slider 60 and the contact with the wall of the introducer
sheath to collapse the filter body 50 into a radially reduced
configuration. The same tendency of the filter body 52 to axially
elongate and radially reduce discussed above in connection with
FIG. 4 will also reduce friction between the filter body 52 and the
interior surface of the introducer sheath as the filter is advanced
therealong.
[0066] The filter 50 may be urged distally along the lumen of the
vessel V to a predetermined treatment site. The treatment site may,
for example, simply be a convenient location in a patient's
vasculature positioned distally of an obstruction which will be
treated with an angioplasty balloon or an atherectomy device. As
explained above, the filter 50 can be advanced along the vessel by
urging the mandrel distally such that the stop 40 engages the
distal slider 60. This exerts a distal biasing force on the distal
slider which, in turn, acts against a restorative force of the body
52 of the filter. As a result, the body 52 will tend to axially
elongate and take on a radially reduced profile. This reduces
friction between the filter 50 and the wall of the vessel,
facilitating advancement therealong.
[0067] Once the filter has reached the desired treatment site, the
axial force against the mandrel can simply be released. This will
permit the body 52 to expand radially and axially contract, drawing
the two sliders 60, 65 toward one another along the mandrel. If it
is determined that the filter is not precisely positioned in the
desired treatment site, it can be readily repositioned by pushing
the mandrel distally or withdrawing it proximally and again
allowing the filter to self-expand radially and self-contract
axially once the mandrel stops acting against the sliders. When it
comes time to remove the filter 50 from the patient's vessel or
move it proximally to a new treatment site, the operator can simply
pull proximally on the mandrel to radially contract the device and
facilitate proximal movement within the vessel, as shown in FIG.
5.
[0068] In some circumstances, one may wish to limit the trauma to
the intima of the vessel walls which may otherwise occur as the
filter 50 is dragged along the vessel to the desired treatment
site. This can be accomplished using a catheter to position the
device adjacent the desired treatment site and/or to withdraw the
device from the vessel after it has been deployed.
[0069] In accordance with one such method, a catheter may be
positioned adjacent a treatment site in a patient's body. This can
be done in any desired fashion. For example, the mandrel 20 and the
catheter can be advanced simultaneously through the patient's
vessel. In a particularly preferred embodiment, though, the
catheter will be positioned at the desired treatment site before
the mandrel 20 is inserted into the catheter. This permits the
operator to steer the catheter into place without hindrance from
the mandrel or to track the catheter over a guidewire if the
desired treatment site is positioned in a narrower or more tortuous
vessel, after which the guidewire can be removed.
[0070] Once the distal tip of the catheter is positioned adjacent
the treatment site, the distal tip 25 of the mandrel can be
inserted into the proximal end (not shown) of the catheter outside
the patient's body. Once the distal slider 60 of the filter 50
enters the proximal end of the catheter, the catheter will
frictionally engage the body 52 of the filter. Further distal
urging of the mandrel will cause the stop 40 to exert a distal
biasing force on the distal slider 60. Much like the process shown
in FIG. 10, this distal biasing force will tend to axially elongate
and radially reduce the body 52, further facilitating entry of the
body into the lumen of the catheter.
[0071] Once the filter 50 is received within the catheter, it may
continue to be urged distally along the length of the catheter. As
explained above in connection with FIG. 9, the distal urging of the
stop 40 against the distal slider 60 will axially elongate and
radially reduce the body, reducing friction between the body and
the catheter during such advancement. If the distal tip of the
catheter is positioned just proximally of the desired treatment
site, the mandrel can be urged distally until the device exits the
distal end of the catheter. Preferably, the body will then tend to
radially self-expand until it reaches a radially-expanded shape
wherein it may engage the walls of the vessel (B in FIG. 9).
Alternatively, the distal tip of the catheter may be positioned
distally of the desired treatment site. In such a circumstance,
advancement of the mandrel can be stopped when the operator
determines by means of the radiopaque sliders 60, 65 that the
filter is in the desired treatment site. Thereafter, the catheter
can be withdrawn proximally while holding the mandrel 20 in place.
As the distal tip of the catheter is withdrawn proximally from the
body 52 of the device, the body will tend to radially self-expand
with the distal slider 60 remaining in substantially the same place
due to its abutment against the stop 40.
[0072] In many circumstances, one may wish to deploy the filter 50
in a temporary fashion so that it may be readily withdrawn in the
manner discussed below. In other circumstances, though, it may be
desirable to leave the device in place in the patient's body for an
extended period of time or even permanently. This is the most
likely scenario for a plug 50 deployed in a patient's vascular
system as a vascular occlusion device, for example.
[0073] It is preferred that the mandrel be withdrawn from the
patient's body either in part or in its entirety. By establishing a
selectively disengageable connection between one length of the
mandrel and another length, the distal most of those lengths can be
detached from one another, leaving the filter 50 and the
distal-most length in the patient's body while withdrawing the
proximal-most length. These lengths can be connected in any fashion
known in the art, such as by means of a threaded engagement or by
means of a solder which can be melted or softened by application of
electrical resistance heating of the mandrel.
[0074] More preferably, though, the entire mandrel 20 is withdrawn
from the patient's body. This can be done by withdrawing the stop
40 through the proximal slider 65 of the filter. One suitable stop
40' is shown in FIG. 12. This stop 40', used in conjunction with a
specially adapted proximal slider (not shown, but described above)
can be used to withdraw the stop through the proximal slider for
removal of the mandrel. As explained previously, this can be
accomplished by bringing the stop 40' into abutting engagement with
the proximal slider then rotating the mandrel 20 about its axis.
This will cause the thread 42' extending radially outwardly from
the body 44' of the stop to pass along a mating slot in the
proximal slider. After the mandrel has been rotated sufficiently to
completely withdraw the stop through the proximal slider, the
mandrel can easily be withdrawn from the body by withdrawing the
distal portion 30 of the mandrel proximally through the center of
the filter body 52 and out of the patient's body entirely.
[0075] If the device is not to be permanently left in its original
position, one can withdraw the filter 50 from the body by
withdrawing it into the lumen of the catheter C. This can be done
either to withdraw the filter 50 from the patient's body at the end
of a procedure or simply for purposes of repositioning the filter
at a new location. As discussed above in more detail in connection
with FIG. 10, the filter 50 can be withdrawn into the lumen of the
catheter C either by holding the mandrel stationary and advancing
the catheter distally over the filter 50 or by holding the catheter
in a fixed position and withdrawing the mandrel 20 proximally.
Either way, the proximal urging of the stop 40 against the proximal
slider 65 tends to axially elongate and radially reduce the body
52, both facilitating entry of the body 52 into the lumen of the
catheter and reducing friction between the catheter and the length
of the body 52 which is already received therein. Once the filter
50 is received within the catheter, the catheter may be held in
place and the mandrel 20 and filter 50 can be completely removed
from the catheter. Alternatively, the catheter, mandrel and filter
50 can all be removed simultaneously as a unit from the patient's
body.
[0076] While a preferred embodiment of the present invention has
been described, it should be understood that various changes,
adaptations and modifications may be made therein without departing
from the spirit of the invention and the scope of the appended
claims.
* * * * *