U.S. patent application number 10/609053 was filed with the patent office on 2004-05-06 for catheter positioning systems.
This patent application is currently assigned to C. R. Bard, Inc.. Invention is credited to Forcucci, Stephen J., Forde, Sean, Gambale, Richard A., Shah, Chirag B., Weiser, Michael F..
Application Number | 20040087996 10/609053 |
Document ID | / |
Family ID | 23434869 |
Filed Date | 2004-05-06 |
United States Patent
Application |
20040087996 |
Kind Code |
A1 |
Gambale, Richard A. ; et
al. |
May 6, 2004 |
Catheter positioning systems
Abstract
The present invention provides a catheter positioning system
which serves to control and stabilize a distal end of a catheter at
a treatment site within a patient so that a medical procedure can
be performed with accuracy. Generally, the positioning system
operates by providing a deformable mechanical members at the distal
end of the catheter which can be operated from the proximal end of
the catheter to extend radially outward to engage surrounding
tissue adjacent to treatment site. In one embodiment of the
invention a flexible superstructure comprising the plurality of
flexible veins extending longitudinally along the distal end of the
catheter can be deformed to bow radially outward to engage
surrounding tissue. The distal tip of the catheter joined to one of
the veins was correspondingly displaced or rotated angularly as the
veins bow outward. In another embodiment radially projecting
fingers are joined to the distal end of the catheter, which remain
retracted during navigation of the catheter to the treatment site
then are extended outward to penetrate the tissue and secure the
catheter at the treatment site upon being actuated from the
proximal end of the catheter by a physician. Methods of positioning
a catheter are also disclosed. The inventive device and method are
particularly useful in catheter based procedures carried out in
large body lumens or in cavities of body organs. In particular, the
invention may be useful in delivering implants percutaneously
through the left ventricle into the myocardium of the heart.
Inventors: |
Gambale, Richard A.;
(Tyngsboro, MA) ; Forcucci, Stephen J.; (Medford,
MA) ; Shah, Chirag B.; (Nashua, NH) ; Weiser,
Michael F.; (Groton, MA) ; Forde, Sean;
(Watertown, MA) |
Correspondence
Address: |
KIRKPATRICK & LOCKHART LLP
75 STATE STREET
BOSTON
MA
02109-1808
US
|
Assignee: |
C. R. Bard, Inc.
Murray Hill
NY
|
Family ID: |
23434869 |
Appl. No.: |
10/609053 |
Filed: |
June 27, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10609053 |
Jun 27, 2003 |
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09364520 |
Jul 30, 1999 |
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6629987 |
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Current U.S.
Class: |
606/194 |
Current CPC
Class: |
A61M 2025/0087 20130101;
A61B 2017/3488 20130101; A61M 25/04 20130101; A61M 25/0084
20130101 |
Class at
Publication: |
606/194 |
International
Class: |
A61M 029/00 |
Claims
It should be understood however, that the foregoing description of
the invention is intended merely to be illustrative thereof and
that other modifications, embodiments and equivalents may be
apparent to those who are skilled in the art without departing from
its spirit. Having thus described the invention what we desire to
claim and secure by Letters Patent is:
1. A catheter positioning system comprising: an elongate catheter
having proximal and distal ends and at least one lumen extending
there through, and it having a defined length; at least one
resilient member adjacent to distal end of the catheter configured
to be selectively radially extended outward from the catheter; and
a control mechanism operatively associated with the resilient
member and extending to the proximal end of the catheter where it
is configured to be manipulated by a user to actuate the resilient
member from a retracted to an extended position.
2. A catheter positioning system as defined in claim 1 further
comprising: a plurality of resilient members each having proximal
and distal ends, all distal ends joined together and joined to the
catheter at its distal end or adjacent its distal end and all
proximal ends joined together and to the catheter at a position
proximal to the distal end such that the resilient members lie
parallel to the longitudinal axis of the catheter shaft when
unloaded and such that the resilient members bow radially outward
when a compressive load is applied to their distal ends.
3. A catheter positioning system as defined in claim 2 wherein the
distal ends of the resilient members are joined to the catheter
such that the distal end of the catheter is rotated through an
angular displacement when the resilient members are bowed radially
outward to an extended position.
4. A catheter positioning system as defined in claim 2 wherein the
compressive force is applied by proximal movement of the control
mechanism joined to the junction of the resilient member distal
ends and the catheter.
5. A catheter positioning system as defined in claim 1 further
comprising: a plurality of resilient members each having proximal
and distal ends, the proximal ends being an operative association
with the control mechanism and the distal end being free such that
movement of the control mechanism in the distal direction causes
the distal ends of the members to advance radially outward away
from the catheter to an extended position.
6. A catheter positioning system as defined in claim 5 wherein
movement of the control mechanism and the distal are in the
proximal direction causes the members to move radially inward to a
retracted position such that the distal ends of the members do not
protrude from the catheter.
7. A catheter positioning system as defined in claim 5 wherein each
member is operatively associated with an independent control
mechanism.
8. A catheter positioning system as defined in claim 5 wherein at
least one of the resilient members is a tube having a lumen in
fluid communication with a therapeutic agent that is pressurized
from the proximal end of the catheter.
9. A catheter positioning as defined in claim 1 wherein at least
one resilient member has a proximal end joined to a side wall of
the catheter and a distal end that is free, the resilient member
being naturally biased and arranged relative to the catheter such
that the member distal end does not protrude from the catheter
until elastically deformed by movement of an object through the
lumen of the catheter.
10. A catheter positioning system as defined in claim 9 wherein the
object moved through the catheter lumen is an ischemia treatment
device.
11. A catheter positioning system as defined in claim 10 wherein
the ischemia treatment device comprises a tissue implant and
associated delivery device.
12. A method of performing a catheter-based procedure to a
particular treatment site within a patient comprising: providing a
catheter having a proximal end and a distal end and a radially
extendible tissue engagement mechanism at its distal end;
navigating the catheter so that the distal end is adjacent to the
intended tissue location; causing the tissue engagement mechanism
to extend into engagement with the tissue adjacent to treatment
site; and performing the medical procedure while maintaining the
tissue engagement mechanism in its extended position.
13. A method of performing a catheter-based procedure as defined in
claim 12 wherein the treatment site is the myocardium of the heart
and the treatment is relieving the systems of ischemia.
14. A method of performing a catheter-based procedure as defined in
claim 13 wherein the treatment of ischemia comprises advancing a
tissue implant through the catheter and into the tissue at the
treatment site.
15. A method of performing a catheter-based procedure as defined in
claim 13 wherein the treatment for ischemia comprises delivering a
therapeutic agent or cellular composition through the catheter to
the treatment site.
16. A method of performing a catheter-based procedure as defined in
claim 12 wherein the treatment site is the myocardium of the heart
and the treatment is relieving the systems of ischemia.
17. A method for forming a catheter-based procedure wherein the
tissue engagement mechanism comprises a tube in communication with
a therapeutic agent pressurized from the proximal end of the
catheter when~the tissue engagement mechanism contacts the tissue
to deliver the agent to the tissue.
18. A method for delivering a tissue implant into myocardial tissue
of the heart comprising: providing a catheter having at least one
lumen and proximal and distal ends and a radially extendible tissue
engagement mechanism at its distal end configured to be extended by
the presence of a device in the lumen at the distal end of the
catheter; navigating the catheter to the intended implant location
in the myocardium; inserting a delivery device carrying the implant
through the lumen of the catheter while applying a distal force in
a distal direction upon both the catheter and the delivery device
such that the distal end of the catheter abuts the implant site;
and driving the implant through the distal end of the catheter to
extend the catheter positioning mechanism to locate the distal end
of the catheter so that the implant can be delivered to the
intended tissue location.
Description
FIELD OF THE INVENTION
[0001] This invention relates to devices and methods for accurately
and securely positioning the distal end of a catheter during a
medical procedure. Specifically, devices and methods are provided
for controlling the movement of the distal end of the catheter
procedure while being used in a body lumen or organ cavity.
BACKGROUND OF THE INVENTION
[0002] In many procedures utilizing catheters, one of the most
difficult challenges is effectively navigating the catheter to its
intended location and maintaining the distal end, or operating end
of the catheter at the intended locations throughout the medical
procedure. In cases where the catheter is placed through a narrow
body lumen such as a blood vessel, maintaining the orientation of
the distal end of the catheter within the lumen may be somewhat
manageable. However, in applications where the body lumen is
relatively large in comparison to the diameter of the catheter, or
the catheter is delivered to a cavity of a body organ such as the
left ventricle of the heart, the distal end of the catheter will
likely have a greater range of movement and, thus, may be more
difficult to position accurately.
[0003] Several procedures utilizing catheters percutaneously
delivered to the ventricle of the heart have been disclosed. For
example, various methods of treating ischemic myocardial tissue
involve introducing a catheter into the ventricle of the heart.
Creating channels in the heart tissue with a laser catheter is
disclosed in U.S. Pat. No. 5,769,843 (Abella et al.) and U.S. Pat.
Nos. 5,380,316 and 5,389,096 (Aita). The patents disclose utilizing
laser energy discharged from the distal end of a catheter to ablate
tissue from the heart wall to create a channel. U.S. Pat. No.
5,429,144 (Wilk) and International patent application publication
no. WO 98.backslash.49964 disclose delivering an implantable stent
device into the heart wall from a catheter that has been
percutaneously introduced into the ventricle of the heart.
Stabilizing the distal end of such catheters during the given
treatment procedure would appear to be critical.
[0004] It would be advantageous to provide a systemication of a
compressive force delivered through a pull wire that extends
through the catheter. The expansion of the flexible vanes increases
the profile of the catheter at its distal end such that the vanes
will contact interior wall surfaces of the body lumen or organ in
which the catheter is placed thereby preventing unwanted movement
of the catheter.
SUMMARY OF THE INVENTION
[0005] The present invention provides various mechanisms for
positioning the distal end of a catheter at its intended treatment
site within a patient. Two approaches to positioning the distal end
of the catheter are disclosed. In a first embodiment, the distal
end of the catheter employs a collapsible superstructure which
causes the distal tip of the catheter mounted thereto to change
direction so that the distal opening of the catheter can be
directed to the intended tissue site. The superstructure is
comprised of two flexible veins mounted along the side wall of the
distal end of the catheter parallel to the longitudinal axis of the
catheter that are biased to bow radially outward upon an
application of a compressive force delivered through a pull wire
that extends through the catheter. The expansion of the flexible
veins increases the profile of the catheter at its distal end such
that the veins will contact interior wall surfaces of the body
lumen or organ in which the catheter is placed thereby preventing
unwanted lateral movement of the catheter. The distal tip of the
catheter is mounted to the distal end of one of the vanes so that
the vane lies along the longitudinal axis of the catheter when the
vanes are unstressed. Therefore, when the vanes are bowed radially
outward the angular displacement of the vane at the connection
point with the distal tip of the catheter, away from the
longitudinal axis of the catheter, causes the distal tip to have a
corresponding angular displacement. The variable angular
displacement of the tip during displacement of the vanes provides a
steering mechanism for the tip of the catheter so that it may be
navigated to a particular tissue location.
[0006] In another aspect of the invention, the catheter positioning
system comprises radially extending fingers at the distal end of
the catheter which extend outward into surrounding tissue at the
intended location to secure the catheter. The radially extending
fingers remain retracted within the catheter during navigation to
the intended treatment site and are extended to engage tissue upon
reaching the treatment site. The number of radially extending
fingers may vary depending on the retention force of the catheter
necessary to perform the intended procedure. At least one of the
fingers may be tubular, such as a hypotube. The tubular finger may,
be used to deliver a therapeutic agent to the tissue engaged by the
finger. Additionally, the stiffness of the catheter shaft may be
varied to help provide the desired directional stability of the
catheter when restrained by the positioning system.
[0007] Various mechanisms for actuating the radially extending
fingers may be employed. The fingers may be resiliently biased
radially inward in the recessed position and forced into the
extended position by another device advanced through the central
lumen of the catheter. Alternatively, the fingers may be actuated
by control cables extending along the length of the catheter either
through a central lumen or through smaller independent lumens in
the side wall of the catheter. The proximal ends of such cables can
be joined to a handle mechanism joined to the proximal end of the
catheter to facilitate actuation by a physician.
[0008] It is an object of the present invention to provide a system
for effectively controlling the position of the distal end of a
catheter that has been navigated to a treatment site in a
patient.
[0009] It is another object of the invention to provide a catheter
positioning system that operates to locate the distal end of the
catheter and control the orientation of its distal tip by deforming
an external superstructure joined to the distal end of the
catheter.
[0010] It is another object of the invention to provide a catheter
positioning system that operates to locate the distal end of a
catheter by providing radially extending fingers that penetrate
into adjacent tissue.
[0011] It is another object of the invention to provide a method
for positioning the distal end of a catheter that comprises
actuating a mechanical component at the distal end of the catheter
to engage surrounding tissue.
[0012] It is another object of the invention to provide a catheter
positioning system that is easy to use and economical to
incorporate into a catheter design.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The foregoing and other objects and advantages of the
invention will be appreciated more fully from the following further
description thereof, with reference to the accompanying diagramatic
drawings wherein:
[0014] FIG. 1 is a side view of an embodiment of the catheter
positioning system extended in a body lumen;
[0015] FIG. 2A is an end view of an embodiment of the catheter
positioning system;
[0016] FIG. 2B is a side view of an embodiment of the catheter
positioning system retracted and rotated 90.degree. from the FIG. 1
diagram;
[0017] FIG. 3A is a side cut-away view of an embodiment of the
catheter positioning system having radially extending fingers
contained in individual catheter lumens and extending from the
distal end of the catheter;
[0018] FIG. 3B is an end view of the embodiment shown in FIG.
3A;
[0019] FIG. 3C is a side cut-away view of an embodiment of the
catheter positioning system having radially extending fingers
containing individual lumens extending from side ports in the
catheter;
[0020] FIG. 4A is a cut-away side view of an embodiment of the
catheter positioning system having radially projecting fingers
contained in a common catheter lumen and extending through side
ports;
[0021] FIG. 4B is a cut-away side view of an embodiment of the
catheter positioning system in the retracted position having
radially extending fingers contained in a common lumen of the
catheter;
[0022] FIG. 4C is a cut-away side view of an embodiment of the
catheter positioning system having radially projecting fingers
contained in a common catheter lumen and extending through the
distal end of the catheter;
[0023] FIG. 5A is a side view of an embodiment of the catheter
positioning system having radially extended fingers actuated by an
external band, shown in the retracted position;
[0024] FIG. 5B is the embodiment shown in FIG. 5A in the extended
position;
[0025] FIG. 6A is an embodiment of the catheter positioning system
having radially extended fingers actuated by an external band,
shown in the retracted position;
[0026] FIG. 6B is a side view of the embodiment shown in FIG. 6A in
the extended position;
[0027] FIG. 7A is a cut-away side view of an embodiment of the
catheter positioning system having radially extending fingers
actuated by movement of a device through a central lumen of the
catheter;
[0028] FIG. 7B is a cut-away side view of the embodiment shown in
FIG. 7A having a device in the center lumen of the catheter to
extend the radially projecting fingers; and
[0029] FIG. 8 is a diagrammatic side view of a catheter equipped
with an embodiment of the catheter positioning system and control
handle.
DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS
[0030] FIG. 1 shows a side view of a distal end 12 of a catheter 10
equipped with an embodiment of the catheter positioning system. The
catheter comprises an elongate shaft 11 of conventional
construction, extruded from polymeric material and having at least
one lumen. A superstructure positioning system 14 at the distal end
of the catheter is comprised of several elongate resilient vanes 16
each having proximal and distal ends 18 and 20, respectively. The
distal ends 20 of each vane are joined at a distal joint 22 by such
a means as soldering or welding at a point that is proximal to the
distal tip 28 of the catheter. Distal connector band 30 located
adjacent the distal tip 28 of the catheter joins a portion of a
single vane fixedly to the catheter shaft 11 at a point along the
vane that is slightly proximal from the distal connection 22.
Connector bands 26 and 30 may be formed of a polymer or any
suitable material capable of joining both the catheter shaft 11 and
a vane 16. The bands may even comprise only adhesive without a
specific band structure. The purpose of the bands is to form a
joint, preferably fixed, between the vane and the catheter shaft at
their given location and to maintain the captured portion of the
vane parallel with the longitudinal axis 32 of the catheter 10. The
proximal ends 18 of the vanes are joined at a proximal joint 24 at
proximal connector band 26 which fixes the joint 24 and thus the
proximal ends 18 of the vanes to the catheter shaft 11.
[0031] FIG. 2A shows an end view of the catheter 10 and FIG. 2B
shows a side view of the catheter and positioning system retracted
and rotated 90.degree. from the view shown in FIG. 1. A control
mechanism comprises a pull wire 36 that is joined to the distal
connection 22 at one end and extends proximally to the proximal end
(not shown) of the catheter. The control mechanism or pull wire
extends along the exterior of the catheter shaft 11 through the
range encompassed by the length of the vanes 16. However, from
proximal connection 24 and band 26, the control mechanism or pull
wire 36 may pass through the side wall of a catheter and extend
through the lumen 38, or may continue proximally along the exterior
of the catheter.
[0032] Placing the pull wire in tension applies a compressive force
on the vanes 16 causing it to buckle radially outward so that vane
midpoints 40 engage the surface 42 of surrounding tissue 44 to
locate the catheter as is shown in FIG. 1. Sensing bands 46 may be
placed at the midpoints 40 of vanes 16 for the purpose of
contacting and sensing properties of the tissue near the treatment
area to which the catheter is delivered. Sensing bands 46 may be
configured to perform a variety of useful functions such as mapping
the surface of the tissue, detecting electrical or thermal data of
the tissue, or for other purposes.
[0033] The vanes 16 may be formed from a filament of any material
providing resilient behavior and body temperature. The vanes may be
formed from a metal such as stainless steel or nitinol or may be
formed from a polymer material. The vanes can be any
cross-sectional shape such as a round wire or a rectangular
ribbon., but preferably should having a shape and configuration
that encourages the vanes to bow radially outward in opposite
directions when they buckle under compressive loading. The pull
wire 36 may be made from any material having sufficient strength to
place tension on the vanes. Materials such as metallic wire or a
polymer would be suitable. The control mechanism or pull wire may
be joined to the distal connection 22 by any suitable means such as
soldering, welding or adhesive.
[0034] When there is no force on control mechanism or pull wire 36,
vane 16 and distal end 12 of catheter shaft 11 are in a retracted,
straight position due to the natural resiliency of the catheter
shaft 11 and the vanes. Upon application of tension to control
mechanism or pull wire 36, the distal connection 22 is pulled
proximally relative to the catheter causing vanes 16 and distal end
of catheter shaft 12 to buckle and bow radially outward. Vanes 16
eventually come into contact with tissue surfaces 42 as their
profile increases within body cavity 8. With vane midpoints 40
wedged against tissue surfaces,42, the distal end 12 of the
catheter is stabilized because its side-to-side movement is
prevented. In this condition, the procedures may be performed
through the catheter and the intended treatment site may reliably
be reached by instruments passed through the catheter lumen 38.
When tension is released on the control mechanism or pull wire 36,
the vanes and catheter resiliently return to their straight
configuration and the catheter may be removed from the treatment
location.
[0035] Another control feature of the superstructure positioning
system is the angular displacement of the distal tip 28 of the
catheter 10 corresponding to the extension of vanes 16. Due to the
parallel arrangement of the vane 16 and distal end of the catheter
12 at distal connector band 30, a longitudinal axis of the catheter
32 at the distal tip 28 rotates an amount of angular displacement
corresponding to the magnitude angular displacement of the vane
away from its original unstressed position. As greater tension is
applied to the pull wire 36 to cause further buckling of the vane
16, angular displacement of the distal tip 28 of the catheter will
continue to increase. Therefore, the angular displacement can be
variably controlled by the operators manipulation of the control
mechanism or pull wire. This angular displacement control provides
a steering mechanism to pinpoint treatment sites on the tissue
surface 42 of the body conduit or cavity. Although two vanes are
shown in the drawings discussed herein in the present embodiment,
more resilient vanes can be used to construct a catheter
positioning device in accordance with the present invention.
[0036] FIG. 3A shows a cut-away side view of another embodiment of
the catheter positioning system that utilizes radially projecting
fingers 50 to engage and penetrate tissue 44. Embodiments of the
catheter positioning system employing radially projecting fingers
can have various configurations; however, generally, the fingers
should be formed from a resilient filament material of any
cross-sectional shape and of metallic or polymeric material. The
resiliently projecting fingers penetrate or extend to penetrate
tissue that has come to surround their extension path due to distal
pressure applied on the catheter 10 causing tissue 44 to herniate
around the distal tip 28 and side surface 13 of the catheter.
[0037] At least one of the projecting fingers may be a tubular
member capable of delivering a therapeutic agent to the tissue
engaged by the distal end of the finger. A stainless steel
hypodermic tube may be use. The proximal end of the tubular finger
should be joined to a pressurizable source of a therapeutic agent.
Once the distal end of the finger is extended radially outward into
contact with the tissue the agent may be delivered under pressure
to the tissue site. Various therapeutic agents may be used
depending on the treatment involved. In delivering angiogenic
implants to the myocardium agents such as growth factors cellular
compositions or gene therapies may be delivered in liquid or gel
form.
[0038] FIG. 3B shows an embodiment wherein the projecting fingers
50 are slidably received within auxiliary lumens 54, which are much
smaller then and run parallel to main lumen 38. For frame of
reference, auxiliary lumens may measure on the order of 0.012 inch
inside diameter while main lumen 38 may measure on the order of
0.068 inch inside diameter. The outside diameter of catheters
discussed in connection with this invention may be on the order of
0.105 inch. Distal ends 56 of projecting fingers are precurved and
arranged within the lumens to project radially outward away from
the catheter when not confined by the lumens 54 and reach their
unstressed condition. During advancement of the catheter 10 to the
intended treatment site, projecting fingers 50 are maintained
retracted, pulled back proximally within the lumens 54 to restrain
distal portions 56 in a straight configuration and maintain them
within the lumens. Upon reaching the intended tissue location, the
projecting fingers 50 may be advanced distally so that the distal
portions 56 of the fingers are extended through distal ports 58 and
become free to return to their natural curved orientation as is
shown in FIGS. 3A and the end view of the catheter shown in FIG.
3B. Preferably, sufficient distal forces applied to the catheter to
cause distal tip 28 to indent a tissue surface 42 so that it
herniates around the side surfaces 13 of the catheter providing
sufficient tissue depth into which the fingers may project and take
hold to restrain the catheter in position during the planned
medical procedure. Distal tip 60 of the projecting fingers
preferably have a sharpened point suitable for easily penetrating
tissue. Longitudinal movement of fingers 50 through the auxiliary
lumens 54 is controlled by a control mechanism, which simply
comprises a shaft extending from the fingers 50 to the proximal end
of the catheter where it may be grasped and manipulated by the
physician. The control mechanism need not be a separate component
from the finger component but may comprise the proximal portion of
a continuous shaft that terminates in the radial finger 50 at its
distal end.
[0039] FIG. 3C shows an alternate embodiment of that shown in FIG.
3A employing side ports 64. The projecting FIGS. 50 pass through
the side ports rather than the distal ports 58, as shown in FIG.
3A. The distal edge of the side port may have a ramp surface 66 to
facilitate passage of projecting finger 50 as it is advanced
distally and curves resiliently outward through the side port 64.
Additionally, ramp-surface inserts 68 may be inserted in the far
distal end of the auxiliary lumens 54 to prevent straight distal
progress of the projecting fingers 50 when advanced to achieve
radial extension.
[0040] FIGS. 4A-4C show an alternative embodiment of the projecting
fingers catheter positioning system in which the control mechanism
62 of the fingers passes through the central lumen 38 of the
catheter shaft rather than through auxiliary lumens 54 or
independent auxiliary lumens 54.
[0041] FIG. 4A shows an embodiment having side ports similar to
that as shown in FIG. 3C through which the projecting fingers 50
may pass as they extend into surrounding tissue. The distal edge of
the side port 64 may have a ramp surface 66 to facilitate the
radially extending curvature of the projecting finger 50 at its
distal end 56. FIGS. 4B and 4C shown an embodiment of the single
lumen catheter 10 in which the projecting fingers exit the lumen at
the distal tip 28 of the catheter 28. FIGS. 4B and 4C also show a
variation of the projecting finger curvature incorporating a
foot-shaped design where each finger has a foot portion 70 that
extends substantially perpendicular to the longitudinal axis of the
control mechanism 62. Also, the foot configuration comprises a heel
portion 72 forming a curved transition between the foot 70 and
relatively straight control mechanism portion 62 of the projecting
finger 50. The overall effect of the foot configuration is to
provide a greater radial extent of the projecting finger 50 into
surrounding tissue due to the exaggerated length of foot portion
70.
[0042] FIGS. 5A-5B show yet another embodiment of the projecting
finger catheter positioning system utilizing a band 72, axially
slidable along the shaft 11 of the catheter 10 in order to effect
extensionary traction of the fingers 50. A slidable band may be
formed from any material having relatively low friction properties
in comparison to the catheter shaft material. The axial movement of
the band may be controlled via a control mechanism such as a cable
or shaft extending the length of the catheter through main lumen 38
or an auxiliary lumen or on the exterior of the shaft 11.
Alternatively, the band may be considered to represent the distal
portion of a full length sheath slid over the catheter shaft 11 and
being slidably controllable from the proximal end of the catheter
to serve as the control mechanism.
[0043] In the embodiment shown in FIGS. 5A and 5B, the filament
that forms the projecting fingers 50 is mounted in the band 72 and
moves with movement of the band. In this embodiment, the projecting
fingers extend distally from the band only a relatively small
distance proximally equivalent to the desired maximum radial extent
when the fingers are extended. Distal movement of the band and
fingers 50 into the ramp surface 76 of outwardly flared flange
shaped distal end 78 of the catheter causes the fingers to be
pushed radially outward so that they can engage and pierce tissue
that will surround the distal tip 78 when a distal force is applied
to the catheter. FIG. 5B shows the positioning system in the
extended position, with the band 72 being fully advanced distally
and fingers extending radially outward after having been driven
into the ramp surface 76.
[0044] The embodiment of the radially extending fingers catheter
positioning system as shown in FIGS. 6A and 6B also employs a
axially slidable band 74 to effect extension and retraction of the
fingers; however, the fingers are joined to the catheter shaft 11
rather than to the band 74 as shown in FIGS. 5A and 5B. The effect
of this is that the fingers are instead retracted when the band is
advanced distally and the fingers are extended when the band is
pulled back proximally. Because the fingers are naturally biased to
be curved radially outward, the band 74 operates to confine the
fingers close to the catheter shaft 11 when extended distally to
cover their distal ends 56, as shown in FIG. 6A. As shown in FIG.
6B, proximal withdrawal of the band 74 from the precurved distal
area 56 of the fingers permits the fingers to resiliently extend in
a radially outward direction from the catheter shaft 11 to
penetrate tissue herneating around the distal tip of the catheter.
Also, another difference in the embodiment of FIGS. 6A and 6B is
that the fingers 50 extend under the force of their inherent
resiliency when the band is withdrawn proximally. The fingers 50 in
the embodiment shown in FIGS. 5A and 5B are elastically deformed in
the extended position because they are driven radially outward as
they come into contact with the ramp surfaces 76 of the flanged
distal end 78. The forced extension of the fingers in the 5A and 5B
embodiments may provide a stronger penetration force if the tissue
is needed to secure the catheter in the area of interest.
[0045] FIGS. 7A and 7B show yet another embodiment of the
projecting fingers, which utilizes elastic deformation caused by a
device being passed through the central lumen 38 of the catheter 10
to extend the fingers. In the absence of a device in the lumen, the
fingers resiliently return to their retracted position within the
catheter. As shown in FIG. 7A, a cut-away view of the catheter 10
revealing the positioning system, short resilient fingers 80 are
mounted inside the catheter shaft, having proximal ends 82 mounted
in auxiliary lumens 84 by means such as adhesive 86. Distally from
the proximal ends 82 the fingers 80 taper radially inward to form a
ramp portion 88, reducing the clearance between the fingers to a
distance that is less than the profile of the device to be inserted
through the lumen 38 of the catheter. Engagement portions 90 of the
fingers 80; therefore, when in contact with the device will cause
the distal ends 92 of the fingers, which extend perpendicular to
the engagement portions 90, to protrude through side ports 94 as is
shown in FIG. 7B. After the device 104 such as an angiogenic
implant passes out of the distal end 98 of the catheter and out of
engagement with engagement portions 90 of the fingers, the fingers
return to their naturally biased retracted position and the
catheter distal tip 12 may be pulled away from the tissue.
[0046] The device 104 is advanced through the lumen 38 over a shaft
106 having an obturator 108 at its distal end configured to
penetrate tissue so that the device 104 can be implanted in the
tissue. The shaft 106 extends proximally to the proximal end of the
catheter so that it may be manipulated by the physician for
delivery of the implant device. The device 104 and shaft 106 are
maintained properly square within lumen 38 yet still engage fingers
80 sufficiently to cause them to deform and extend by virtue of
slits formed through the inside diameter thickness of the catheter
to provide a travel space 100 through which the fingers may have a
range of motion as the device passes through. The device is
supported around all other areas of the circumference of the lumen
38 except for the areas of the slits. Flexible implant devices may
be configured to promote angiogenesis through a variety of
mechanisms examples of which are described in detail in pending
U.S. patent application Ser. Nos. 09/164,173, 09/211,332 and
09/299,795, which are incorporated by reference herein in their
entirety.
[0047] In use, the catheter positioning system may be used to
deliver an angiogenic implant into myocardial tissue by the steps
detailed below. First, the catheter 10 configured as shown in FIGS.
7A and 7B is introduced and navigated to the area of treatment
within the left ventricle of the heart, guided by either a guide
catheter or a guidewire by conventional techniques. After reaching
the general area of treatment, the guidewire, if used, is then
removed and the shaft 106 with obturator at 108 and angiogenic
device 104 preloaded onto its distal end is then navigated through
the lumen of the catheter. The catheter is positioned at the tissue
location of interest. A distal force is applied by the physician on
both the catheter and the delivery device shaft 106 to not only
maintain the distal tip 98 of the catheter against the tissue to be
treated, but also to simultaneously advance the device 104 through
the lumen 38 and into contact with engagement portions 90 of the
fingers 88. This simultaneous motion causes the distal ends 92 of
the fingers 88 to penetrate into surrounding tissue to locate the
distal tip 98 of the device at a specific location just prior to
the devices advancement into the tissue. Depending on the amount of
maneuverability needed to reach the intended location with the
catheter 10, the stiffness of the material selected for the
catheter can be varied to make the catheter more flexible or more
rigid.
[0048] FIG. 8 shows a variation of the embodiment as shown in FIGS.
7A and 7B, including a handle 110 joined to control mechanisms 112
which are joined to radially extending fingers 88 to provide
independent control of the extension or retraction of the fingers
rather than an automatic deployment of the fingers illustrated in
the last embodiment. Axial movement of the handle 110 causes
control mechanism 112 to also move and cause fingers 88 to move in
an axial direction. When distal ends 92 of the fingers reach the
side ports or exit port at the distal end 98 of the catheter, the
fingers will be free to be extended radially outward.
[0049] By the foregoing description, it will be appreciated that
the invention provides a novel and useful method and device for
locating and stabilizing the distal end of a catheter so that a
medical procedure can be carried out at a specific treatment site
within a patient. The device is easy to use and simple to
manufacture.
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