U.S. patent application number 11/923606 was filed with the patent office on 2008-08-07 for steerable device for introducing diagnostic and therapeutic apparatus into the body.
Invention is credited to Robert F. Bencini, Russell B. Thompson.
Application Number | 20080188800 11/923606 |
Document ID | / |
Family ID | 24188953 |
Filed Date | 2008-08-07 |
United States Patent
Application |
20080188800 |
Kind Code |
A1 |
Bencini; Robert F. ; et
al. |
August 7, 2008 |
Steerable Device For Introducing Diagnostic And Therapeutic
Apparatus Into The Body
Abstract
An apparatus including an elongate body having a lumen extending
therethrough and a steering wire associated with the distal portion
of the elongate body.
Inventors: |
Bencini; Robert F.;
(Sunnyvale, CA) ; Thompson; Russell B.; (Los
Altos, CA) |
Correspondence
Address: |
HENRICKS SLAVIN AND HOLMES LLP;SUITE 200
840 APOLLO STREET
EL SEGUNDO
CA
90245
US
|
Family ID: |
24188953 |
Appl. No.: |
11/923606 |
Filed: |
October 24, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09548465 |
Apr 13, 2000 |
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11923606 |
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09165652 |
Oct 2, 1998 |
6544215 |
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09548465 |
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Current U.S.
Class: |
604/95.01 ;
600/585; 604/95.04 |
Current CPC
Class: |
A61M 25/0141 20130101;
A61M 25/0144 20130101; A61B 2017/00243 20130101; A61M 25/0051
20130101; A61M 25/005 20130101; A61M 25/0147 20130101; A61M
2025/015 20130101; A61M 25/0138 20130101; A61M 25/0136
20130101 |
Class at
Publication: |
604/95.01 ;
600/585; 604/95.04 |
International
Class: |
A61M 37/00 20060101
A61M037/00 |
Claims
1. An apparatus, comprising: an elongate body defining a proximal
portion and a distal portion and including a wall defining an inner
surface, an outer surface and a central lumen extending from the
proximal portion to an aperture in the distal portion; a steering
wire having a distal portion; and a tubular member, with a
plurality of slots, located between the inner surface and the outer
surface of the distal portion of the elongate body and secured to
the distal portion of the steering wire.
2-17. (canceled)
18. An apparatus as claimed in claim 1, further comprising: a
steering wire lumen offset from the central lumen in which at least
a portion of the steering wire is located.
19. An apparatus as claimed in claim 1, wherein the proximal
portion of the elongate body is relatively stiff and the distal
portion of the elongate body is relatively flexible.
20-25. (canceled)
26. An apparatus as claimed in claim 1, further comprising: a
catheter supporting at least one of a diagnostic element and a
therapeutic element located within the central lumen and slidable
relative thereto.
27. An apparatus, comprising: an elongate body proximal portion
defining a lumen extending therethrough, a distal end and a
proximal portion stiffness; an elongate body distal portion
associated with the distal end of the elongate body proximal
portion, the elongate body distal portion defining a distal end, a
proximal end, a lumen extending therethrough, a length from the
distal end to the proximal end, and a perimeter, and including at
least first and second distal members that together form the
elongate body distal portion, the first distal member defining a
first distal member stiffness and the second distal member defining
a second distal member stiffness less than the first distal member
stiffness; and a steering wire having a distal portion operably
connected to the elongate body distal portion.
28. An apparatus as claimed in claim 27, wherein the first distal
member stiffness and the second distal member stiffness are both
less than the elongate body proximal portion stiffness.
29. An apparatus as claimed in claim 27, wherein the second distal
member defines a second lumen and the steering wire is located
within the second lumen.
30. An apparatus as claimed in claim 27, wherein the first and
second distal members are substantially semi-circular in
cross-sectional shape.
31. An apparatus as claimed in claim 27, wherein the first and
second distal members occupy substantially equal segments of the
elongate body distal portion perimeter over the elongate body
distal portion length.
32. An apparatus as claimed in claim 27, wherein the first and
second distal members occupy respective segments of the elongate
body distal portion perimeter that vary in size over the length of
the distal portion.
33. An apparatus as claimed in claim 27, wherein the first distal
member occupies a segment of the elongate body distal portion
perimeter that varies in size over the elongate body distal portion
length such that the first distal member occupies substantially all
of the perimeter at one end of the elongate body distal portion and
occupies substantially none of the perimeter at the other end of
the elongate body distal portion.
34. An apparatus as claimed in claim 27, wherein the first distal
member occupies a segment of the elongate body distal portion
perimeter that increases in size over a first portion of the
elongate body distal portion length and decreases in size over a
second portion of the elongate body distal portion length.
35. An apparatus as claimed in claim 27, wherein the elongate body
distal portion includes a third distal member and the third distal
member defines a stiffness less than the first distal member
stiffness and greater than the second distal member stiffness.
36. An apparatus as claimed in claim 35, wherein the first distal
member is located distally of the second and third distal members
and the third distal member is located distally of the second
distal member.
37. An apparatus as claimed in claim 35, the first, second and
third distal members occupy respective segments of the elongate
body distal portion perimeter and the segments vary in size over
the elongate body distal portion length.
38. An apparatus as claimed in claim 35, wherein the first, second
and third distal members define respective lengths and occupy
respective segments of the elongate body distal portion perimeter
and the respective sizes of the segments remain substantially
constant over the respective lengths distal members.
39. An apparatus as claimed in claim 27, wherein the first distal
member comprises a pair of first distal members respectively
located on opposite sides of the second distal member.
40. An apparatus as claimed in claim 27, wherein the second distal
member comprises a wall defining the elongate body distal portion
lumen and the first distal member is located within the wall.
41. An apparatus as claimed in claim 40, wherein the first distal
member extends substantially from the proximal end of the elongate
body distal portion to the distal end of the elongate body distal
portion.
42. An apparatus as claimed in claim 40, wherein the wall includes
an inner surface and an outer surface and the first distal member
is located in spaced relation to the inner surface.
43. An apparatus as claimed in claim 1, wherein the tubular member
defines a longitudinal axis and the plurality of slots are
substantially perpendicular to the longitudinal axis.
44. An apparatus as claimed in claim 1, wherein the plurality of
slots are arranged such that the tubular member defines an elongate
stiffening member.
45. An apparatus as claimed in claim 44, wherein the steering wire
is secured to a portion of the tubular member that is diametrically
opposed from the stiffening member.
46. An apparatus as claimed in claim 44, wherein the tubular member
defines a circumference and the elongate stiffening member extends
over less than one-half of the circumference.
47. An apparatus as claimed in claim 44, wherein the tubular member
includes a plurality of rings with the slots therebetween, and a
portion of each ring defines a portion of the elongate stiffening
member.
48. An apparatus as claimed in claim 1, wherein the tubular member
comprises a hypotube.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of co-pending
U.S. application Ser. No. 09/165,652, filed Oct. 2, 1998, which is
incorporated herein by reference.
BACKGROUND OF THE INVENTIONS
[0002] 1. Field of Inventions
[0003] The present inventions relate generally to devices that are
used to introduce diagnostic and therapeutic apparatus into the
body.
[0004] 2. Description of the Related Art
[0005] There are many instances where physicians must introduce
diagnostic and therapeutic apparatus, such as diagnostic and
therapeutic electrodes, ultrasound transducers, biopsy devices and
other surgical tools, into the body. The diagnostic and therapeutic
apparatus are often carried by catheters, which allow physicians to
gain access to the body in a minimally invasive manner by way of
bodily lumens. In cardiac treatment, for example, a catheter is
advanced through a main vein or artery into the region of the heart
that is to be treated.
[0006] One method of introducing diagnostic and therapeutic
apparatus into the body is to introduce a tubular member (typically
a "sheath") into the vicinity of the targeted region. A diagnostic
or therapeutic apparatus is then passed through the tubular member
to the targeted region. If necessary, the diagnostic or therapeutic
apparatus may be removed after its function is performed, but the
tubular member left in place, so that other apparatus may be
advanced to the targeted region to complete the diagnostic and/or
therapeutic procedure.
[0007] Precise placement of the diagnostic or therapeutic apparatus
is very important, especially in those procedures concerning the
heart. To that end, some conventional sheaths are guided to the
targeted region with a steerable catheter that is located within
the sheath lumen. Once the sheath reaches the targeted region, the
steerable catheter is removed from the sheath and a catheter
carrying the diagnostic or therapeutic apparatus is advanced
through the lumen. This type of sheath lacks any onboard steering
mechanism. As a result, redeployment of the distal portion of
sheath, even to a region in close proximity to the initially
targeted region, requires the withdrawal of the diagnostic or
therapeutic apparatus and the reintroduction of the steering
catheter.
[0008] Other conventional sheaths include a steering mechanism that
allows the physician to deflect the distal portion of the sheath.
The steering mechanism consists primarily of one or more steering
wires. One end of each steering wire is secured to the distal end
of the sheath, while the other end is secured to a steering control
device, such as the rotating cam and steering control knob
arrangement commonly found in steerable catheters. Rotation of the
control knob causes one of the wires to impart a pulling force on
the distal portion of the sheath, thereby causing the distal
portion to deflect. To promote steerability, the distal portion of
the sheath (which is relatively short) is typically formed from
relatively soft, flexible material. Conversely, the proximal
portion (which is relatively long) is formed from relatively hard,
less flexible material that provides better torque transmission
properties.
[0009] The inventors herein have determined that there are a number
of shortcomings associated with conventional steerable apparatus,
such as steerable sheaths, that are used to introduce diagnostic
and therapeutic apparatus into the body. For example, it is
desirable to provide a sheath or other tubular member having a
small outer diameter (OD) in order to limit the size of the entry
hole that must be made in the patient's vein or artery and to
compensate for the effects of arteriosclerosis. Because the
diameter of the lumen, or inner diameter (ID), tends to be a
function of the size of the diagnostic and therapeutic apparatus to
be introduced into the body, the primary method of reducing the OD
is reducing the wall thickness of the tubular member.
[0010] Heretofore, efforts to reduce wall thickness have been
hampered by the fact that the wall strength of the tubular member
distal portion must be sufficient to prevent the steering wire from
tearing through the distal portion during deflection. Proposed
solutions to the strength problem included the use of harder
materials and/or the addition of mechanical devices, such as coils,
to the distal portion of the tubular member. The inventors herein
have determined that such solutions are less than optimal because
they limit the flexibility and, therefore, the steerability of the
distal portion of the sheath or other tubular member.
[0011] The inventors herein have also determined that the distal
portion of the tubular member in conventional steerable apparatus
will sometimes buckle during steering operations and do not always
return to the neutral position after the steering operation is
complete. Moreover, it can be difficult to produce a distal portion
that will bend to a specific radius of curvature using conventional
structures and manufacturing techniques.
SUMMARY OF THE INVENTIONS
[0012] Accordingly, the general object of the present inventions is
to provide apparatus that avoids, for practical purposes, the
aforementioned problems. In particular, one object of the present
inventions is to provide a steerable apparatus for introducing
diagnostic and therapeutic apparatus into the body, such as a
steerable sheath, having a thinner wall than conventional apparatus
without sacrificing steerability.
[0013] In order to accomplish some of these and other objectives,
an apparatus in accordance with one embodiment of a present
invention includes an elongate body having a lumen extending
therethrough and a steering wire, having a distal portion defining
a non-circular cross-section, associated with the distal portion of
the elongate body. In one preferred implementation, the elongate
body is a sheath and the distal portion of the steering wire is
substantially flat.
[0014] The present apparatus provides a number of advantages over
conventional steerable apparatus for introducing diagnostic and
therapeutic apparatus into the body. For example, the non-circular
steering wire distal portion distributes the forces generated
during deflection over a greater surface area than a steering wire
having a circular cross-section. The redistribution of forces over
a greater area reduces the amount strength required to prevent the
steering wire from tearing through the distal portion of the
tubular members, sheaths or other elongate bodies during
deflection. As a result, the present elongate body may be made
thinner than the tubular members, sheaths or other elongate bodies
in conventional steerable apparatus formed from the same
material.
[0015] Use of the present non-circular steering wire also prevents
out of plane bending. The non-circular portion of the steering wire
also provides a larger surface area for attaching the steering wire
to the distal portion of the elongate body or an element within the
elongate body, thereby making manufacturing easier and, due to the
larger bonding area, decreasing the likelihood that the steering
wire and elongate body will become disconnected.
[0016] In order to accomplish some of these and other objectives,
an apparatus in accordance with one embodiment of a present
invention includes an elongate body having a lumen extending
therethrough, a steering wire associated with the distal portion of
the elongate body, and a stiffening member associated with the
distal portion of the elongate body. The present apparatus provides
a number of advantages over conventional steerable apparatus for
introducing diagnostic and therapeutic apparatus into the body. For
example, the stiffening member will prevent buckling of the
elongate body distal portion during bending. The stiffening member
may also be configured such that it will return the elongate body
distal portion to a neutral position after a steering operation,
influence the curvature of the elongate body during steering,
provide a pre-bend in a direction other than the direction in which
the distal portion is bent during steering, and increase the torque
transmission properties of the distal portion.
[0017] In order to accomplish some of these and other objectives,
an apparatus in accordance with one embodiment of a present
invention includes an elongate body proximal portion, an elongate
body distal portion, and a steering wire having a distal portion
operably connected to the elongate body distal portion. The
elongate body distal portion is formed from distal members with
different stiffnesses. Such apparatus provides a number of
advantages over conventional steerable apparatus for introducing
diagnostic and therapeutic apparatus into the body. For example,
the stiffer distal member will prevent buckling of the elongate
body distal portion during bending.
[0018] The above described and many other features and attendant
advantages of the present inventions will become apparent as the
inventions become better understood by reference to the following
detailed description when considered in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Detailed description of preferred embodiments of the
inventions will be made with reference to the accompanying
drawings.
[0020] FIG. 1 is a plan view of a steerable apparatus in accordance
with a preferred embodiment of a present invention.
[0021] FIG. 2 is a partial section view showing a steerable
apparatus in accordance with a preferred embodiment of a present
invention, in combination with a catheter carrying a diagnostic or
therapeutic element, deployed within the heart.
[0022] FIG. 3 is a perspective, partial section view of an elongate
body distal portion in accordance with a preferred embodiment of a
present invention.
[0023] FIGS. 4a and 4b are side views of the elongate body distal
portion illustrated in FIG. 3.
[0024] FIG. 5 is a perspective view of a steering wire and steering
wire anchoring member assembly in accordance with a preferred
embodiment of a present invention.
[0025] FIG. 6a is side view of an elongate body distal portion in
accordance with another preferred embodiment of a present
invention.
[0026] FIG. 6b is a top view of the elongate body distal portion
illustrated in FIG. 6a.
[0027] FIG. 6c is a perspective view of a stiffening member,
steering wire and anchoring member assembly in accordance with a
preferred embodiment of a present invention.
[0028] FIG. 7a is a side view of an elongate body distal portion in
accordance with still another preferred embodiment of a present
invention.
[0029] FIG. 7b is a top view of the elongate body distal portion
illustrated in FIG. 7a.
[0030] FIGS. 8a, 8b, 8c and 8d are front elevation views of
stiffening members in accordance with preferred embodiments of a
present invention.
[0031] FIG. 8e is a section view of an elongate distal body
including the stiffening member illustrated in FIG. 8a.
[0032] FIG. 8f is a perspective view of the stiffening member
illustrated in FIG. 8c with a prebend.
[0033] FIGS. 8g and 8h are front elevation and side views of a
stiffening member in accordance with a preferred embodiment of a
present invention.
[0034] FIGS. 8i and 8j are front elevation and side views of a
stiffening member in accordance with a preferred embodiment of a
present invention.
[0035] FIGS. 8k and 8l are front elevation and side views of a
stiffening member in accordance with a preferred embodiment of a
present invention.
[0036] FIG. 9 is partial side section view of an elongate body
distal portion in accordance with yet another preferred embodiment
of a present invention.
[0037] FIG. 10a is a perspective view of another stiffening member
in accordance with a preferred embodiment of a present
invention.
[0038] FIG. 10b is a perspective view of still another stiffening
member in accordance with a preferred embodiment of a present
invention.
[0039] FIG. 11a is a side view of an elongate body distal portion
in accordance with a preferred embodiment of a present invention in
a bent orientation.
[0040] FIG. 11b is a side view of the elongate body distal portion
illustrated in FIG. 11a in a straight orientation.
[0041] FIG. 11c is a section view take along line 11c-11c in FIG.
11a.
[0042] FIGS. 12, 13 and 14 are side views of elongate body distal
portions in accordance with preferred embodiments of a present
invention.
[0043] FIG. 15a is a side view of an elongate body distal portion
in accordance with a preferred embodiment of a present
invention.
[0044] FIG. 15b is a section view take along line 15b-15b in FIG.
15a.
[0045] FIG. 16 is a side view of an elongate body distal portion in
accordance with a preferred embodiment of a present invention.
[0046] FIG. 17 is a section view taken along line 17-17 in FIG.
1.
[0047] FIG. 18 is a partial cutaway view of the exemplary handle
illustrated in FIG. 1.
[0048] FIG. 19 is a perspective view of a portion of the exemplary
handle illustrated in FIGS. 1 and 18.
[0049] FIG. 20 is side partial section view of another portion of
the exemplary handle illustrated in FIGS. 1 and 18.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0050] The following is a detailed description of the best
presently known modes of carrying out the inventions. This
description is not to be taken in a limiting sense, but is made
merely for the purpose of illustrating the general principles of
the inventions.
[0051] The detailed description of the preferred embodiments is
organized as follows:
[0052] I. Overview
[0053] II. Elongate Body Distal Portion
[0054] III. Elongate Body Proximal Portion
[0055] IV. Handle
The section titles and overall organization of the present detailed
description are for the purpose of convenience only and are not
intended to limit the present inventions.
I. Overview
[0056] The present inventions may be used within body lumens,
chambers or cavities for diagnostic or therapeutic purposes in
those instance where access to interior bodily regions is obtained
through, for example, the vascular system or alimentary canal and
without complex invasive surgical procedures. For example, the
inventions herein have application in the diagnosis and treatment
of conditions within the heart. The inventions herein also have
application in the diagnosis or treatment of ailments of the
gastrointestinal tract, prostrate, brain, gall bladder, uterus, and
other regions of the body.
[0057] As illustrated for example in FIG. 1, a preferred
implementation of a present invention is a steerable device 10
having a handle 12 and an elongate, hollow body 14. In the
preferred implementation, the elongate body 14 is a sheath having a
lumen through which a catheter having diagnostic and/or therapeutic
element(s) may be advanced.
[0058] The exemplary handle 12 consists partially of a handle body
16 and a piston 18. The piston 18, which is slidably mounted in a
longitudinally extending aperture in the handle body 16, includes a
thumb rest 20. The handle body 16, piston 18 and thumb rest 20 are
preferably formed from machined or molded plastic. Other features
of the exemplary handle 12 are discussed below in Section IV. In
the exemplary embodiment, one end of a steering wire 22 is secured
to the distal portion 24 of the elongate body 14. The steering wire
22 passes through the proximal portion 26 of the elongate body 14
to the handle body 16, where the other end is secured. As discussed
in Section III below, the elongate body distal portion 24 and
proximal portion 26 are joined to one another at a joint 25.
[0059] In the illustrated embodiment, the elongate body is secured
to, and travels with, the piston 18. As such, when the exemplary
piston 18 is moved distally from the position shown in FIG. 1, the
steering wire 22 exerts a pulling force on the distal portion 24 of
the elongate body 14, thereby causing the distal portion of the
elongate body to deflect into a curved orientation.
[0060] Other types of steering apparatus may be used in place of
the exemplary piston-based configuration. For example, a handle may
be provided that includes a rotating cam, to which the steering
wire is connected, and a steering lever connected to the rotating
cam. Manipulation of the steering lever causes the steering wire to
deflect the distal portion of the elongate body. This type of
steering apparatus is disclosed in U.S. Pat. No. 5,636,634.
[0061] One exemplary use of the present steerable device is
illustrated in FIG. 2. Here, the distal portion 24 of the elongate
body 14 has been inserted into the heart and steered into the
vicinity of targeted tissue within the left ventricle LV. It should
be noted that the heart shown in FIG. 2 is not exactly anatomically
correct, and is shown in diagrammatic form to demonstrate the
features of the exemplary device. A catheter 23 is extending from
the distal portion 24 so that an element 25 (such as a diagnostic
and/or therapeutic element) may be positioned adjacent myocardial
tissue.
II. Elongate Body Distal Portion
[0062] In accordance with a preferred embodiment of a present
invention, and as illustrated for example in FIG. 3, the portion of
the steering wire 22 that is secured to the distal portion 24 of
the elongate body 14 has a non-circular cross-section. Although
other shapes may be employed, the distal portion 28 of the
exemplary steering wire 22 (also referred to as the "non-circular
portion") is substantially flat and preferably free of sharp edges
that could damage the distal portion 24 of the elongate body 14. A
substantially flat steering wire distal portion 28 having a width
to thickness ratio between about 1.5 to 1 and about 10 to 1 is
preferred. The remainder of the steering wire (referred to herein
as the proximal portion 30) has a circular cross-section.
[0063] The exemplary elongate body distal portion 24 illustrated in
FIG. 3 includes two lumens, a central lumen 32 through which
diagnostic and therapeutic apparatus may be advanced and a steering
wire lumen 34 in which the steering wire 22 is located. The central
lumen 32 preferably terminates at the distal end 38 of the distal
portion 24, thereby defining a distal end aperture through which
diagnostic or therapeutic elements may exit the elongate body 14.
However, the central lumen may also terminate in the side wall of
the distal portion 24, thereby defining a side exit aperture. In
the illustrated embodiment, the cross-sectional shape of the
steering wire lumen 34 corresponds to that of the substantially
flat steering wire distal portion 28. This prevents unwanted
rotation of the steering wire 22. However, the steering wire lumen
34 may have other cross-sectional shapes, such as an elliptical
shape, which will also prevent rotation of a non-circular steering
wire or portion thereof.
[0064] As shown by way of example in FIG. 3, the steering wire 22
may be secured to an anchoring member 36 that is located within
elongate body distal portion 24. The steering wire 22 may be
secured to the anchoring member 36 by, for example, welding or
adhesive. The exemplary anchoring member 36 is in the form of a
cylinder. However, other shapes, such as an annular disk shape,
could be used should they be required by a particular application.
The anchoring member 36 provides a relatively long attachment
surface, thereby decreasing the likelihood that the steering wire
22 will become disconnected from the elongate body distal portion
24. In addition, the anchoring member 36 may be formed from
radiopaque material such as platinum or gold plated stainless
steel. The radiopacity allows the distal portion of the elongate
body to be observed by the physician using conventional
fluoroscopic techniques. Other materials include rigid polymer and
ceramic materials that are compounded with radiopaque material.
[0065] There are a number of advantages associated with the
preferred embodiment illustrated in FIGS. 1-3. For example, when
the distal portion 24 of the elongate body 14 is deflected from the
orientation shown in FIG. 4a to the orientation shown in FIG. 4b,
the steering wire will exert a force F along the elongate body
distal portion. In conventional devices employing pull wires having
a circular cross-section, the distal portion wall must be
relatively thick in order to prevent the steering wire from tearing
through the wall of the sheath or other elongate body. The wall in
preferred embodiment illustrated in FIGS. 1-3 may be made thinner
than conventional devices formed from the same material because the
exemplary substantially flat (or otherwise non-circular) steering
wire distal portion 28 distributes the force F over a greater
surface area than does a steering wire having a circular
cross-section.
[0066] The use of the present non-circular steering wire also
prevents out of plane bending. In other words, when bending force
is applied to the elongate body distal portion 24, it will bend
about an axis that is both perpendicular to the longitudinal axis
of the elongate body and parallel to the width dimension of the
steering wire non-circular portion 28. The steering wire
non-circular portion 28 also provides a larger surface area for
attaching the steering wire to the exemplary anchoring member 36
(or other portion of the elongate body) than does a circular
wire.
[0067] One utilization of the present invention is a steerable
sheath that may be used in cardiac treatments such as percutaneous
myocardial revascularization (PMR). In a preferred embodiment, the
outer diameter of the elongate body 14 is about 0.118 inch and the
diameter of the central lumen 32 is about 0.075 inch. The distal
portion 24 of the elongate body is about 1.4 inches in length and
should be flexible enough to bend approximately 135.degree. (note
that a 90.degree. bend is shown in FIG. 4b), yet have sufficient
memory to return to its original orientation when bending forces
are removed. To provide the necessary flexibility, the distal
portion 24 of the elongate body may be formed from a relatively
flexible material through a dual lumen extrusion process. Preferred
relatively flexible materials include, for example, fluoropolymers
such as THV 200, a commercially available combination of
tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride,
and Pellethane 80A. Radiopaque material, such as barium, bismuth,
and tungsten may be combined with the flexible material for
visualization purposes.
[0068] In the exemplary steerable sheath that may be used in PMR
and other cardiac care procedures, the anchoring member 36 is
preferably about 0.100 inch in length and has a wall thickness of
about 0.002 inch. The diameter of the circular proximal portion 30
of the steering wire 22 is about 0.009 inch, while the width of the
non-circular portion 28 ranges from about 0.012 inch to about 0.017
inch and the thickness ranges from about 0.003 inch to about 0.005
inch. To accommodate the non-circular portion 28, the steering wire
lumen 34 has a shape corresponding to that of the non-circular
portion and cross-sectional dimensions which are about 0.001 inch
to about 0.003 inch larger than those of the circular portion. The
length of the steering wire non-circular portion 28 is preferably
slightly less than that of the elongate body distal portion 24. As
a result, only the circular proximal portion 30 of the steering
wire 22 will pass through the circular steering wire lumen in the
elongate body proximal portion 26 (discussed in Section III), even
when the distal portion 24 is being bent. Alternatively, the
non-circular portion 28 will extend the entire length of the
elongate body distal portion 24 and the steering wire lumen in the
elongate body proximal portion 26 will be modified accordingly.
[0069] Turning to FIG. 5, the steering wire 22 may be secured to
the anchoring member 36 prior to the insertion of both into the
elongate body distal portion 24. The combined steering
wire/anchoring member assembly may be inserted into the elongate
body distal portion 24 as follows. The elongate body distal portion
24 is heated to its softening temperature. The proximal end of the
steering wire 22 is then inserted into the steering wire lumen 34.
The anchoring member 36 is moved toward the elongate body distal
portion 24 until it reaches the distal end 38 of the distal
portion. The anchoring member 36 is then forced through the distal
end 38 of the softened distal portion 24 to the position shown in
FIG. 3. The distal end of the steering wire lumen 34 will not be
present after the softened distal portion 24 hardens. Additionally,
in order to insure that the anchoring member 36 will not tear
through the distal end 38, a relatively thin annular piece of
distal portion material can be molded onto the distal end.
[0070] A stiffening member (or "spine") may be provided in order to
prevent compression (or "buckling") of the elongate body distal
portion 24 during bending, which can sometimes happen in those
instances where the distal portion is formed with very thin walls
or from very flexible material. The stiffening member may also be
used to return the elongate body distal portion 24 to a neutral
position after a steering operation, influence the curvature during
steering, provide a pre-bend in a direction other than the
direction in which the distal portion is bent during steering, and
to increase the torque transmission properties of the distal
portion. A variety of stiffening members are illustrated in FIGS.
6a-10b. They may be used in combination with steerable devices
including steering wires having cross-sections that are circular,
non-circular or some combination thereof.
[0071] As shown by way of example in FIGS. 6a and 6b, an elongate
body distal portion 24a includes a stiffening member 40 located in
a stiffening member lumen 42. The stiffening member lumen 42 is
itself located on the side of the elongate body distal portion 24a
opposite the steering wire 22 (and steering wire lumen 34). The
stiffening member 40, which may be circular in cross-section (as
shown in FIGS. 6a and 6b) or non-circular in cross-section, is
bonded or otherwise secured in place.
[0072] Alternatively, the stiffening member may be secured to the
anchoring member 36. Referring to FIG. 6c, the distal end of a
stiffening member, such as stiffening member 44 (described below),
may be secured to the anchoring member 36 and an anti-tear device
41 may be secured to the proximal end of the stiffening member. The
anti-tear device 41, which is located within the elongate body
distal portion 24a and which includes a slot 43 through which the
steering wire distal portion 28 passes, spreads the forces
associated with the bending of the stiffening member 44 over a
greater surface area, thereby preventing the bending member from
tearing through the elongate body distal portion. A suitable
anti-tear device may be constructed by forming the slot 43 in a
hypotube.
[0073] In another alternative arrangement, the stiffening member 44
and anti-tear device 41 may be replaced by a second steering wire
22 located on the opposite side as the first steering wire. While
one of the steering wires is used for steering purposes, the other
steering wire will act as a stiffening member.
[0074] Referring to FIGS. 7a and 7b, another elongate body distal
portion (here identified by reference numeral 24b) includes a pair
of stiffening members 40 respectively located in a pair of
stiffening member lumens 42. Although other configurations may be
employed, the stiffening member lumens 42 in this embodiment are
located 90.degree. from the steering wire lumen 34 and 180.degree.
from one another.
[0075] A number of exemplary stiffening members with rectangular
cross-sections are illustrated in FIGS. 8a-8d and arranged such
that the proximal end is the bottom end in the FIGURES. Referring
first to FIG. 8a, stiffening member 44 has a constant width from
one longitudinal end to the other. The stiffening member
illustrated in FIG. 8b, which is generally represented by reference
numeral 46, includes a relatively wide proximal portion 48, a
narrowing transition portion 50 and a relatively narrow distal
portion 52. Stiffening member 46 will produce a bend in the
elongate body distal portion 24c (FIG. 8e) with a smaller radius
curve than the stiffening member 44 illustrated in FIG. 8a.
Stiffening member 54 (FIG. 8c) includes a relatively wide proximal
portion 56, a relatively narrow notch portion 58, a relatively wide
distal portion 60 and a tapered portion 62. As compared to the bend
produced by the stiffening member 44 illustrated in FIG. 8a, the
bend produced by the stiffening member 54 will be localized in the
area of notch portion 58. Turning to FIG. 8d, stiffening member 64
includes a relatively wide proximal portion 66, a relatively narrow
notch portion 68, a relatively wide middle portion 70 and a
relatively narrow distal portion 72. Stiffening member 64 will
produce a bend in the elongate body distal portion that has a
smaller radius in the area of distal portion 72 and the same radius
in the area of proximal portion 66, as compared to the stiffening
member 44 illustrated in FIG. 8a.
[0076] The stiffening members illustrated in FIGS. 8a-8d may be
employed in steerable devices having stiffening member lumens with
generally rectangular shapes. As illustrated for example in FIG.
8e, elongate body distal portion 24c includes a stiffening member
lumen 25 and a circular steering wire lumen 27 for a steering wire
29 with a circular cross-section. Of course, a steering wire with a
non-circular cross-section may also be employed. The stiffening
members may be bonded or otherwise secured in place or secured to
the anchoring member 36.
[0077] The stiffening members illustrated in FIGS. 8a-d are about
0.5 inch to about 6.0 inches in length. The width of the relatively
wide portions is about 0.010 inch to about 0.050 inch and the width
of the relatively narrow portions is about 0.003 inch to about
0.030 inch. The thickness of the exemplary stiffening members is
constant and about 0.003 inch to about 0.009 inch.
[0078] The stiffening members may also be prebent in one or more
locations by heat setting or other metal or plastic forming
techniques. As illustrated for example in FIG. 8f, stiffening
member 54 may be formed with a single approximately 90.degree.
bend. The prebent stiffening member may be arranged such that it
causes the elongate body distal portion 24c to bend in a direction
opposite to the steering direction, thereby providing the elongate
body with two-directional steering capabilities.
[0079] As shown by way of example in FIGS. 8g-l, the width of a
stiffening member may be constant, and the thickness of a
particular region, or a plurality of regions, may be increased or
decreased as desired to alter the bending characteristics of the
stiffening member. Turning first to FIGS. 8g and 8h, a stiffening
member 45 has a thickness that decreases from the proximal end to
the distal end, which results in a bending radius that decreases
from the proximal end to the distal end. In an exemplary
implementation, the width of the stiffening member 45 is about
0.017 inch and the thickness decreases from about 0.012 inch to
about 0.004 inch. The exemplary stiffening member 47 illustrated in
FIGS. 8i and 8j includes a central member 49 with a constant
thickness and a base member having a relatively thin portion 51 and
a relatively thick portion 53. Such a stiffening member will have
two distinct bending radii, with the distal bending radius being
smaller than the proximal bending radius. In an exemplary
implementation, the width of the stiffening member 47 is about
0.017 inch, the width of the central member 49 is about 0.005 inch,
the thickness of the central member is about 0.009 inch, the
thickness of the relatively thin portion is about 0.004 inch and
the thickness of the relatively thick portion is about 0.007 inch.
Turning to FIGS. 8k and 8l, an exemplary stiffening member 55
includes a base member 57 with a relatively constant thickness and
a central member 59 having relatively thick portions 61 and 63 and
a relatively thin portion 65 therebetween. The stiffening member 55
has a variable bending radius that transitions slowly from
relatively large to relatively small to relatively large. In an
exemplary implementation, the width of the stiffening member 55 is
about 0.017 inch, the width of the central member 59 is about 0.005
inch, the thickness of the base member is about 0.004 inch, and the
thickness of the central member varies from about 0.009 inch to
about 0.005 inch.
[0080] A coil-type stiffening member may also be used to maintain
the cross-sectional shape of the elongate body distal portion 24,
which is circular in the illustrated embodiments, and to bring the
distal portion back to the neutral position after a steering
operation. As illustrated for example in FIG. 9, an elongate body
distal portion 24d includes a coil 74 embedded therein to help
maintain the circular shape of the distal portion. Of course, the
coil 74 and steering wire lumen 34 (not visible in FIG. 9) must be
radially offset from one another within the distal portion 24d. In
an alternate configuration (not shown), the anchoring member 36 is
removed, the coil 74 is extended into the region occupied by the
anchoring member, and the steering wire is secured to the distal
end of the coil.
[0081] Another coil-type stiffening member, which is generally
represented by reference numeral 76, is illustrated in FIG. 10a.
Stiffening member 76 includes a generally rectangular portion 78
and a coil portion 80 which are preferably spot welded, soldered or
otherwise connected to one another. Both portions are preferably
rectangular in cross-section, but may also be circular. A steering
wire 82 is secured to the distal end of the coil portion 80.
Although a steering wire with a circular cross-section is shown in
FIG. 10a, a steering wire with a non-circular portion may also be
used. Turning to FIG. 10b, a stiffening member similar to that
illustrated in FIG. 10a may be formed from a hypotube 84 having a
plurality of slots 86 formed therein by laser cutting,
electrostatic discharge machining, and chemical etching.
[0082] The various stiffening members described above may be formed
from a variety of metals and plastics such as Nitinol material,
17-7 steel, a nickel/cobalt/chromium allow sold under the trade
name Elgiloy.RTM., resilient plastics, and metal/plastic
composites.
[0083] Elongate body distal portions may also be constructed in
such a manner that they bend as if they included a stiffening
member despite the fact that no stiffening member is included. Such
an arrangement allows for a reduction in wall thickness, thereby
enabling a greater ID for a given OD. Referring first to FIGS.
11a-11c, an exemplary distal portion 24e includes a relatively
soft, flexible front member 67 and a relatively hard, less flexible
rear member 69. The steering wire 28 is located within the front
member 67. The rear member 69, which should be more flexible than
the proximal portion 26, acts as a spine to prevent compression of
the area of the elongate body distal portion 24e opposite the
steering wire 28. The elongate body distal portions illustrated in
FIGS. 12-14 also include steering wires located in their respective
relatively soft, flexible areas and relatively hard, less flexible
areas opposite the steering wire that act as spines. The
differences in hardness and flexibility may be accomplished by
forming the respective areas (or members) from the same type of
material (e.g. Pellethane), albeit with different durometer values,
or by using a different type of material for each area.
[0084] The front and rear members 67 and 69 are semicircular in
cross-section and each occupies a portion (or segment) of the
perimeter that is of constant size (about 180.degree. each) from
one longitudinal end of the elongate body distal portion to the
other. Such a shape produces the bending characteristics
illustrated in FIG. 11a. The bending characteristic may be changed,
however, by varying the sizes of the perimeter segments occupied by
the front and rear members over the length of the distal
portion.
[0085] As illustrated for example in FIG. 12, the respective
segments of the perimeter occupied by the relatively soft, flexible
front member 71 and the relatively hard, less flexible rear member
73 in the distal portion 24f vary in size from essentially none
(about 0.degree.) to essentially all (about 360.degree.). At the
distal end, the front member 71 occupies essentially all of the
perimeter and the rear member 73 occupies essentially none of the
perimeter. Moving proximally, the size of the segment occupied by
the front member 71 gradually decreases, while the size of the
segment occupied by the rear member 73 gradually increases, until
the front member occupies essentially none of the perimeter and the
rear member occupies essentially all of the perimeter, and so on
back and forth in the manner illustrated in FIG. 12. Such an
arrangement results in a relatively elliptical bend.
[0086] Turning to FIG. 13, the size of the segment of the perimeter
occupied by the relatively soft, flexible front member 75 in the
distal portion 24g varies from essentially all at the distal end of
the distal portion to essentially none at the proximal end.
Conversely, the size of the segment of the perimeter occupied by
the relatively hard, less flexible rear member 77 increases from
essentially none at the distal end of the distal portion 24g to
essentially all at the proximal end. Such an arrangement results in
a bending radius that decreases from the proximal end to the distal
end.
[0087] The number of members with different flexibilities may also
be varied. As illustrated in FIG. 14, distal portion 24h includes a
relatively soft, flexible front member 79, a relatively hard, less
flexible rear member 81 and an intermediate member 83 therebetween.
The hardness and flexibility of the intermediate member 83 is
between that of the front and rear members 79 and 81. Here, the
steering wire 28 will be located on right side (as shown in FIG.
14), which is more flexible than the opposite side at any point
along its length.
[0088] It should also be noted that the relatively hard, less
flexible rear members described above may be pre-bent in a
direction opposite to the steering direction, thereby providing the
elongate body with two-directional steering capabilities in a
manner similar to that described above with reference to FIG.
8f.
[0089] Turning to the exemplary embodiment illustrated in FIGS. 15a
and 15b, elongate body distal portion 24i includes a relatively
soft, flexible member 85 and one or more relatively hard, less
flexible members 87. The relatively hard, less flexible members 87
keep the bending of the distal portion in plane and prevent the
distal portion from compressing during steering in a manner similar
to the stiffening members illustrated in FIGS. 6a-7b. Here too, the
differences in hardness and flexibility may be accomplished by
forming the respective areas (or members) from the same type of
material, albeit with different durometer values, or from different
types of material.
[0090] Finally, the bending characteristics of an elongate body
distal portion may also be adjusted by having two or more sections
with different flexibilities. As illustrated for example in FIG.
16, an elongate body distal portion 24j includes sections 89, 91
and 93 that progressively decrease in hardness and flexibility,
thereby producing a distal portion with a bending radius that
progressively decreases from the proximal end to the distal end.
Such an arrangement will not, however, produce the stiffening
member-like effects similar to the embodiments illustrated in FIGS.
11a-15b. Each of the sections 89, 91 and 93 should be more flexible
than the proximal portion 26 and the relative positions of the
sections (as well as the number thereof) may be varied as desired
to create the desired bending characteristics.
III. Elongate Body Proximal Portion
[0091] As illustrated for example in FIG. 17, the exemplary
elongate body proximal portion 26 includes an inner portion 88
through which a central lumen 90 extends, a reinforcing element 92,
and an outer portion 94. The reinforcing element 92 increases the
torque transmission properties of the proximal portion 26 and also
increases its stiffness. The outer portion 94 includes a steering
wire lumen 96 (note steering wire 22) which may be coated with a
lubricious material 98 such as Teflon.RTM.. Although other material
and structures may be used, the preferred reinforcing element is
braided stainless steel having a braid pattern and pick number
suitable for the intended application. Exemplary alternative
reinforcing elements include double helix structures and
three-dimensional braids. Reinforcing elements, braided or not, may
also be formed, for example, from Nylon.RTM. and other polymer
materials.
[0092] The steering wire lumen 96 in the proximal portion 26 of the
elongate body 14 is aligned with the steering wire lumen 34 in the
distal portion 24. However, in contrast to the steering wire lumen
34, the steering wire lumen 96 is preferably circular in
cross-section. In those embodiments where the length of the
non-circular portion 28 of the steering wire 22 is less than the
length of the elongate body distal portion 24, the steering wire
lumen 96 in the proximal member may be circular in cross-section
all the way to the distal end thereof. In other embodiments, where
the steering wire non-circular portion 28 extends to the proximal
end of the elongate body distal portion 24, the steering wire lumen
96 may be either non-circular in its entirety, or simply have a
distal end that is chamfered into a funnel shape to accommodate the
non-circular portion.
[0093] As noted in Section II, one implementation of the present
invention is a steerable sheath that may be used in cardiac
treatments such as PMR. Here, like the elongate body distal portion
24, the proximal portion 26 has an outer diameter of about 0.118
inch and the central lumen 90 (which is aligned with the central
lumen 32 in the distal portion) has a diameter of 0.075 inch. The
length of the proximal portion 26 in this implementation may be
about 7 inches to about 70 inches. Also, a strain relief element
(not shown) may be located over the proximal portion 26 near the
thumb rest 20.
[0094] The proximal portion 26 may be formed by first extruding the
inner portion 88 over a mandrel. The reinforcing element 92 is then
placed over the inner portion 88. Next, the outer portion 94,
including the steering wire lumen 96, is formed in a second
extrusion. In those instances where the surface of the steering
wire lumen 96 includes the coating of lubricious material 98, that
coating is also formed during the second extrusion.
[0095] The distal and proximal portions 24 and 26 of the elongate
body 14 are secured to one another at the joint 25. The joint may
be formed in a variety of ways. For example, an adhesive or thermal
butt bonding technique may be used. However, the preferred method
is an overlapping thermal bond. Specifically, the distal and
proximal portions 24 and 26 are arranged such that a small length
of the distal portion overlaps the proximal portion (or vice
versa). Heat is then applied to the overlapping region, which
causes the overlapping portions to bond to one another.
[0096] The inner and outer portions 88 and 96 are both preferably
formed from THV 200, which is fairly lubricious. Here, the
lubricious coating 98 is not required. In other embodiments, the
inner portion 88 is formed from a polyether block amide such as
PEBAX.RTM., which bonds well with an elongate body distal portion
24 that is formed from Pellethane, and the outer portion 94 is
formed from a fluoropolymer such as THV 200. In still other
embodiments, the inner portion 88 is formed from a fluoropolymer
such as THV 200 and the outer portion 94 is formed from a polyether
block emide such as PEBAX.RTM.. The lubricious coating 98 is
especially useful here.
IV. Handle
[0097] An exemplary handle that may be used in conjunction with the
elongate body 14 is the handle 12 illustrated in FIGS. 1 and 18-20.
Similar handles are commonly found in steerable catheters
manufactured by EP Technologies, Inc. under the trade name
Polaris.RTM., with one important exception. The piston 18 in the
present handle 12 includes a lumen that connects the central lumen
in the elongate body 14 to an input port 100 and a homeostasis
valve 102. In the illustrated embodiment, the input port 100 and
hemostasis valve 102 are part of a Y-adapter 104 that is capable of
rotating 360.degree..
[0098] The exemplary piston 18 is a two-part assembly composed of a
forward piston member 106 and a rear piston member 108. The forward
piston member 106 includes a main body 110 which supports a portion
of the thumb rest 20 at its distal end. The main body 110 extends
into the handle body 16 through a piston supporting cylinder 112.
The piston supporting cylinder 112 has o-rings at its longitudinal
ends that center the main body 110. As shown by way of example in
FIG. 13, a lumen 114 extends through the main body 110 and
terminates at a frusto-conical surface 116. The proximal portion 26
of the elongate member 14 extends through the lumen 114 and outer
surface of the proximal end of the elongate body is bonded to the
conical surface 116. A key way 117, which mates with a protrusion
on the inner surface of the handle, prevents the piston from
rotating.
[0099] The exemplary rear piston member 108 includes a conical tip
118 that mates with the conical surface 116 (and distal end of the
elongate body 14) and a cap 120 that fits over the forward member
main body 110. The rear piston member 108 also includes a lumen 122
which feeds into the Y-adapter 104. To that end, the end 134 of the
rear piston member 108 is inserted into the cylindrical portion 136
of the Y-adapter 104 and the two are sealed in a rear sealing
assembly 138. The adapter stem 140 rotates relative to the
cylindrical portion 136 and an o-ring 142 is provided to create a
seal.
[0100] The level of friction between the piston 18 and handle body
16 may be controlled in part by a set screw 124 (FIG. 1) that
imparts a force onto a tab 126 on the piston supporting cylinder
112.
[0101] Turning to the steering wire 22 and the manner in which it
may be secured within the handle 12, the main body 110 of the
exemplary forward piston member 108 includes a slot 128. The rear
piston member cap 120 includes a corresponding slot 130. The
steering wire 22 passes through the slots 128 and 130 and bends
away from the central axis of the handle body 16. The distal end of
the steering wire 22 is secured to an anchor 132 that is itself
secured to the handle by a hollow nut and bolt assembly located on
the half of the handle body 16 that is not shown in FIG. 18.
Steering wire tension is set by rotating the bolt relative to the
nut.
[0102] Although the present inventions have been described in terms
of the preferred embodiments above, numerous modifications and/or
additions to the above-described preferred embodiments would be
readily apparent to one skilled in the art. It is intended that the
scope of the present inventions extends to all such modifications
and/or additions.
* * * * *