Title: Shape lockable apparatus and method for advancing an instrument through unsupported anatomy
Abstract: Apparatus and methods are provided for placing and advancing a diagnostic or therapeutic instrument in a hollow body organ of a tortuous or unsupported anatomy, comprising a handle, an overtube, a distal region having an atraumatic tip. The overtube may be removable from the handle, and have a longitudinal axis disposed at an angle relative to the handle. The overtube may be selectively stiffened to reduce distension of the organ caused by advancement of the diagnostic or therapeutic instrument. The distal region permits passive steering of the overtube caused by deflection of the diagnostic or therapeutic instrument while the atraumatic tip prevents the wall of the organ from becoming caught or pinched during manipulation of the diagnostic or therapeutic instrument.
Patent Number: 6,837,847 Issued on 01/04/2005 to Ewers, et al.
| Inventors:
|
Ewers; Richard C. (Fullerton, CA);
Saadat; Vahid (Saratoga, CA);
Chen; Eugene G. (Carlsbad, CA)
|
| Assignee:
|
USGI Medical, Inc. (San Clemente, CA)
|
| Appl. No.:
|
173238 |
| Filed:
|
June 13, 2002 |
| Current U.S. Class: |
600/114; 600/121; 600/127 |
| Intern'l Class: |
A61B 001/04 |
| Field of Search: |
600/114,115,117,110,121,127,129,139,140,141,142,143,144,146,150,151
|
References Cited [Referenced By]
U.S. Patent Documents
| 4176662 | Dec., 1979 | Frazer.
| |
| 4577621 | Mar., 1986 | Patel | 600/114.
|
| 4601283 | Jul., 1986 | Chikama.
| |
| 4624243 | Nov., 1986 | Lowery et al. | 600/136.
|
| 4646722 | Mar., 1987 | Silverstein et al.
| |
| 4815450 | Mar., 1989 | Patel.
| |
| 5092901 | Mar., 1992 | Hunter et al.
| |
| 5174276 | Dec., 1992 | Crockard.
| |
| 5217001 | Jun., 1993 | Nakao et al.
| |
| 5251611 | Oct., 1993 | Zehel et al. | 600/141.
|
| 5325845 | Jul., 1994 | Adair | 600/114.
|
| 5337733 | Aug., 1994 | Bauerfeind et al.
| |
| 5402768 | Apr., 1995 | Adair | 600/106.
|
| 5429118 | Jul., 1995 | Cole et al. | 600/121.
|
| 5620408 | Apr., 1997 | Vennes et al. | 600/114.
|
| 5759151 | Jun., 1998 | Sturges | 600/146.
|
| 5779624 | Jul., 1998 | Chang.
| |
| 5807241 | Sep., 1998 | Heimberger | 600/142.
|
| 5842973 | Dec., 1998 | Bullard | 600/194.
|
| 6099464 | Aug., 2000 | Shimizu et al. | 600/104.
|
| 6174280 | Jan., 2001 | Oneda et al. | 600/121.
|
| 6179776 | Jan., 2001 | Adams et al.
| |
| 6306081 | Oct., 2001 | Ishikawa et al. | 600/127.
|
| 6315714 | Nov., 2001 | Akiba.
| |
| 2002/0022765 | Feb., 2002 | Belson.
| |
| 2002/0062062 | May., 2002 | Belson et al.
| |
| 2002/0120178 | Aug., 2002 | Tartaglia et al.
| |
| 2002/0147385 | Oct., 2002 | Butler et al.
| |
| 2002/0161281 | Oct., 2002 | Jaffe et al.
| |
| Foreign Patent Documents |
| 28 23 025 | Dec., 1979 | DE.
| |
Primary Examiner: Flanagan; Beverly M.
Attorney, Agent or Firm: Townsend and Townsend and Crew LLP
Claims
What is claimed is:
1. Apparatus for advancing a first diagnostic or therapeutic instrument
having a steerable distal tip into a hollow body organ of unsupported
anatomy, the apparatus comprising:
a handle having a working axis;
an overtube coupled to the handle, the overtube having an elongated
portion, a distal region and a lumen extending therethrough to permit
passage of the first diagnostic or therapeutic instrument, the lumen
having a longitudinal axis; and
an atraumatic tip disposed on the distal region,
wherein the longitudinal axis of the lumen is angled relative to the
working axis of the handle where the overtube is coupled to the handle.
2. The apparatus of claim 1 wherein the overtube includes means for locking
the overtube in a bent configuration.
3. The apparatus of claim 2 wherein the means for locking the overtube in a
bent configuration comprises:
a plurality of nestable elements;
a plurality of tension wires that thread the nested elements together; and
a tensioning mechanism that may be releasably coupled to the plurality of
tension wires and to selectively apply a clamping load to the plurality of
nestable elements.
4. The apparatus of claim 3 wherein the tensioning mechanism is a
ratchet-type tensioning mechanism.
5. The apparatus of claim 2 wherein the means for locking the overtube in a
bent configuration comprises:
a plurality of links, each link having a bore that defines the lumen of the
overtube; and
means for applying a clamping load to the plurality of links.
6. The apparatus of claim 5 wherein the plurality of links comprise:
a plurality of spool links, each one of the spool links having rounded
distal and proximal ends; and
a plurality of clamp links, each one of the clamp links interposed between
adjacent ones of the plurality of spool links, each one of the clamp links
having an interior surface having grooves adapted to engage a distal end
of a first adjacent spool link and a proximal end of a second adjacent
spool link.
7. The apparatus of claim 5 wherein the plurality of links comprise a
multiplicity of helical links formed from a material having variable
durometer, each helical link having a rigid portion and a soft portion.
8. The apparatus of claim 5 wherein the means for applying a clamping load
comprises an elongate inflatable sleeve disposed to surround the plurality
of links.
9. The apparatus of claim 8 wherein the elongate inflatable sleeve
comprises a plurality of interconnected annular bladders.
10. The apparatus of claim 8 wherein the elongate inflatable sleeve has a
helical shape.
11. The apparatus of claim 5 wherein the means for applying a clamping load
comprises:
a plurality of discontinuous, circular hoops made of a shape memory alloy;
and
a plurality of insulated wires that connect the plurality of hoops to an
electrical source.
12. The apparatus of claim 2 wherein the means for locking the overtube in
a bent configuration comprises a heat-softenable layer having an embedded
wire, wherein an electric current passing through the embedded wire
softens the heat-softenable layer.
13. The apparatus of claim 2 wherein the means for locking the overtube in
a bent configuration comprises a soft layer having an embedded shape
memory alloy wire.
14. The apparatus of claim 1 wherein the atraumatic tip comprises an
inflatable donut-shaped balloon.
15. The apparatus of claim 1 wherein the atraumatic tip comprises a wire
petal having an elastomeric covering.
16. The apparatus of claim 1 wherein the atraumatic tip comprises a foam or
soft elastomer bumper.
17. The apparatus of claim 1 wherein the overtube includes means for
facilitating passage of the first diagnostic or therapeutic instrument
through the lumen of the overtube.
18. The apparatus of claim 1 wherein the lumen is dimensioned to permit
passage of a second diagnostic or therapeutic instrument alongside the
first diagnostic or therapeutic instrument.
19. The apparatus of claim 1 wherein the handle is reusable, and the
overtube is removably coupled to the handle.
20. A method for advancing a first diagnostic or therapeutic instrument
having a steerable distal tip into an unsupported, hollow body organ, the
method comprising:
providing an apparatus having a handle having a working axis, an overtube
coupled to the handle, the overtube comprising an elongated portion, a
lumen extending therethrough to permit passage of the first diagnostic or
therapeutic instrument and a distal region, the lumen having a
longitudinal axis, and an atraumatic tip disposed on the distal region;
inserting the apparatus and the first diagnostic or therapeutic instrument
into the unsupported, hollow body organ; and
advancing the first diagnostic or therapeutic instrument through the lumen
at an angle relative to the working axis of the handle where the overtube
is coupled to the handle.
21. The method of claim 20 wherein providing an apparatus comprises
providing an apparatus wherein the handle is reusable, and the overtube is
releasably coupled to the handle, the method further comprising releasing
the overtube from the handle and reusing the handle.
22. The method of claim 20 further comprising:
locking the overtube in a bent configuration; and
advancing the first diagnostic or therapeutic instrument through the lumen
of the overtube in the bent configuration.
23. The method of claim 22 wherein providing an apparatus comprises
providing an apparatus wherein the overtube comprises a plurality of
nestable elements, and a tensioning mechanism that selectively applies a
clamping load to the plurality of nestable elements; and locking the
overtube in a bent configuration comprises actuating the tensioning
mechanism.
24. The method of claim 22 wherein providing an apparatus comprises
providing an apparatus wherein the overtube comprises a plurality of
links, each link having a bore that defines the lumen of the overtube, and
locking the overtube in a bent configuration comprises applying a clamping
load to the plurality of links.
25. The method of claim 24 wherein the overtube further comprises an
elongate inflatable sleeve disposed to surround the plurality of links,
and applying a clamping load to the plurality of links comprises inflating
the elongate inflatable sleeve.
26. The method of claim 24 wherein the overtube further comprises a
plurality of discontinuous, circular hoops made of a shape memory alloy,
and applying a clamping load to the plurality of links comprises inducing
the plurality of discontinuous, circular hoops to undergo a phase
transition.
27. The method of claim 22 wherein providing an apparatus comprises
providing an apparatus wherein the overtube comprises a heat-softenable
layer having an embedded wire, and locking the overtube in a bent
configuration comprises terminating a supply of electrical energy to the
embedded wire.
28. The method of claim 22 wherein providing an apparatus comprises
providing an apparatus wherein the overtube comprises a soft layer having
an embedded shape memory alloy wire, and locking the overtube in a bent
configuration comprises heating the embedded shape memory alloy wire.
29. The method of claim 20 wherein providing an apparatus comprises
providing an apparatus wherein the atraumatic tip comprises an inflatable
donut shaped balloon, the method further comprising:
deflecting the unsupported, hollow body organ by inflating the inflatable
donut shaped balloon.
30. The method of claim 20 wherein providing an apparatus comprises
providing an apparatus wherein the atraumatic tip comprises a wire petal
having an elastomeric covering, the method further comprising:
deflecting the unsupported, hollow body organ by extending the wire petal
in a radially-outwardly direction.
31. The method of claim 20 wherein providing an apparatus comprises
providing an apparatus wherein the atraumatic tip comprises a foam or soft
elastomer bumper, the method further comprising:
deflecting the unsupported, hollow body organ by contacting the foam or
soft elastomer bumper against the unsupported, hollow body organ.
32. The method of claim 20 wherein providing an apparatus comprises
providing an apparatus wherein the lumen is dimensioned to permit passage
of a second diagnostic or therapeutic instrument alongside the first
diagnostic or therapeutic instrument, the method further comprising:
advancing the second diagnostic or therapeutic instrument alongside the
first diagnostic or therapeutic instrument.
Description
FIELD OF THE INVENTION
The present invention relates to apparatus and methods for placing and
advancing a diagnostic or therapeutic instrument in a hollow body organ of
unsupported anatomy, while reducing patient discomfort and risk of injury.
BACKGROUND OF THE INVENTION
The use of the colonoscope for examining the interior of the large
intestine or colon is well-known. In general, a physician performing an
examination or treatment of the colon inserts a colonoscope into the anus
and then advances the colonoscope into the colon. A complete examination
requires the physician to advance the colonoscope into the colon,
negotiate the sigmoid colon, and left and right colic flexures up to the
cecum. Advancement of the colonoscope is generally accomplished by
manipulation of a steerable tip of the colonoscope, which is controlled at
the proximal end of the device by the physician, in addition to torquing
and pushing the scope forward or pulling it backward.
Problems regularly occur, however, when negotiating the colonoscope through
the bends of the colon, such as at the sigmoid and left and right colic
flexures. These problems arise because the colon is soft and has
unpredictable fixation points to the viscera of the abdomen, and it is
easily distensible. Consequently, after the steerable tip of the
colonoscope is deflected to enter a new region of the colon, the principal
direction of the force applied by the physician urging the proximal end of
the device into the patient's colon is not in the direction of the
steerable tip. Instead, the force is directed along the axis of the
colonoscope towards the preceding bend(s), and causes yielding or
displacement of the colon wall.
The loads imposed by the colonoscope on the colon wall can have a myriad of
possible effects, ranging from patient discomfort to spastic cramp-like
contractions of the colon and even possible perforation or dissection of
the colon. Consequently, the colonoscope cannot be advanced as far as the
cecum in up to one-sixth of all cases.
To address some of these difficulties, it is known to employ a guide tube
that permits a colonoscope to be advanced through the rectum. One such
device is described in U.S. Pat. No. 5,779,624 to Chang. An alternative
approach calls for inserting the colonoscope through a curved region, and
then mechanically actuating the portion of the device in the curved region
to cause it to straighten, as described in U.S. Pat. No. 4,601,283 to
Chikama.
Many patients find the operation of such previously-known devices
unpleasant because the sigmoid portion of the colon is forced into an
almost rectilinear shape by the guide tube. Due to the stiffness of the
guide tube, careless handling of the guide tube presents a risk of injury
to the colon.
Other previously-known apparatus and methods use an overtube having
variable rigidity, so that the overtube may be inserted through curved
anatomy in a flexible state, and then selectively stiffened to resist
bending forces generated by passing a colonoscope through the overtube.
One example of such a device is described in U.S. Pat. No. 5,337,733 to
Bauerfiend. The device described in that patent comprises inner and outer
walls having opposing ribs spaced apart across an air-filled annulus. The
ribs are selectively drawn together to intermesh, and form a rigid
structure by evacuating the annulus.
Another previously-known endoscopic device for delivering aneurysm clips
within a hollow organ or vessel is described in U.S. Pat. No. 5,174,276 to
Crockard. The device described in that patent includes a conduit formed
from a multiplicity of elements that are capable of angulation relative to
one another, and which becomes rigid when subjected to a tensile force.
The device is described as being particularly useful in neurosurgery,
where the variable rigidity of the device is useful for providing a stable
platform for neurosurgical interventions, such as clipping an aneurysm.
While previously-known apparatus and methods provide some suggestions for
solving the difficulties encountered in advancing diagnostic or
therapeutic instruments through easily distensible body organs, few
devices are commercially available. Although the precise reasons for this
lack of success are uncertain, previously-known devices appear to pose
several problems.
For example, the devices described in the Bauerfiend and Crockard patents
appear to pose a risk of capturing or pinching tissue between the
endoscope/colonoscope and the distal end of the overtube or conduit when
the scope is translated. Also, neither device provides any degree of
steerability, and must be advanced along the pre-positioned scope. In
addition, the bulk of the proximal tensioning system described in Crockard
is expected to interfere with manipulation of the endoscope. Other
drawbacks of previously-known devices may be related to the complexity or
cost of such devices or the lack of suitable materials. In any event,
there exists an un-met need for devices to solve this long-felt problem in
the field of endoscopy and colonoscopy.
In view of the foregoing, it would be desirable to provide apparatus and
methods for facilitating placement of diagnostic or therapeutic
instruments within easily distensible hollow body organs, such as the
esophagus or colon.
It further would be desirable to provide apparatus and methods that permit
a diagnostic or therapeutic device to be advanced into a hollow body
organ, and which facilitates passage of the device through tortuous
anatomy without requiring straightening of organ passageways already
traversed.
It also would be desirable to provide apparatus and methods for
facilitating placement of diagnostic or therapeutic instruments within
easily distensible hollow body organs that include means for reducing the
risk that tissue will become inadvertently pinched between the sheath
apparatus and the advancing or withdrawing instrument, or caught as the
diagnostic or therapeutic instrument is maneuvered through the hollow body
organ.
It still further would be desirable to provide apparatus and methods that
provide a low-cost, single use, easily manufacturable guide for inserting
a diagnostic or therapeutic instrument in a hollow body organ.
It yet further would be desirable to provide apparatus and methods that
provide a low-cost, easily manufacturable guide for inserting a diagnostic
or therapeutic instrument in a hollow body organ, wherein a portion of the
apparatus is disposable after a single use and a remaining portion of the
device is re-usable.
Still further, it would be desirable to provide a device having a
selectively locking shape for inserting a diagnostic or therapeutic
instrument in a hollow body organ, but which facilitates manipulation of a
proximal end of the diagnostic or therapeutic instrument.
It additionally would be desirable to permit multiple diagnostic or
therapeutic devices to be positioned in a hollow, unsupported organ, so
that at least one of the devices may be withdrawn and repositioned while
the other devices are retained in place.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to
provide apparatus and methods for facilitating placement of diagnostic or
therapeutic instruments within easily distensible or unpredictably
supported hollow body organs, such as the esophagus or colon.
It is a further object of the present invention to provide apparatus and
methods that permit a diagnostic or therapeutic device to be advanced into
a hollow body organ, and which facilitates passage of the device through
tortuous anatomy without requiring straightening of organ passageways
already traversed.
It also is an object of the present invention to provide apparatus and
methods for facilitating placement of diagnostic or therapeutic
instruments within easily distensible hollow body organs that include
means for reducing the risk that tissue will become inadvertently pinched
or caught as the diagnostic or therapeutic instrument is maneuvered
through the hollow body organ.
It is a still further object of the present invention to provide apparatus
and methods that provide a low-cost, single use, easily manufacturable
guide for inserting a diagnostic or therapeutic instrument in a hollow
body organ.
It is another object of this invention to provide apparatus and methods
that provide a low-cost, easily manufacturable guide for inserting a
diagnostic or therapeutic instrument in a hollow body organ wherein a
portion of the apparatus is disposable after a single use and a remaining
portion of the device is re-usable.
Still further, it is an object of the present invention to provide a device
having a selectively locking shape for inserting a diagnostic or
therapeutic instrument in a hollow body organ, but which facilitates
manipulation of a proximal end of the diagnostic or therapeutic
instrument.
It is yet another object of the present invention to permit multiple
diagnostic or therapeutic devices to be positioned in a hollow,
unsupported organ, so that at least one of the devices may be withdrawn
and repositioned while the other devices are retained in place.
These and other objects of the present invention are attained by providing
apparatus comprising a proximal handle, an overtube coupled to the
proximal handle and having a distal region, and an atraumatic tip disposed
on the distal region. The apparatus includes a main lumen extending
between the handle, overtube and atraumatic tip, through which a
diagnostic or therapeutic instrument, such as an endoscope or colonoscope,
may be translated.
The handle extends from the patient, e.g., through the mouth or anus, where
it can be manipulated by the physician. The handle preferably comprises
means for selectively locking the shape of the overtube. In this manner
the overtube may be shape locked to assist one or more diagnostic or
therapeutic instruments to negotiate the tortuous or unsupported anatomy
of a hollow body organ, rather than distending the wall of the organ. The
proximal handle may form part of a single use, disposable apparatus, or
may be separable from the overtube and reusable. The overtube preferably
is angled relative to a working axis of the handle, so that the handle
does not interfere with manipulation of the diagnostic or therapeutic
instrument inserted through the overtube.
An overtube constructed in accordance with the principles of the present
invention may comprise a multiplicity of selectively-tensionable nested
elements, a series of interconnected links surrounded by a selectively
actuable clamping mechanism, a tubular member comprising a multiplicity of
helical links formed from a material having variable durometer and
surrounded by a clamping mechanism, or a thermo-responsive polymer or
alloy. The overtube may include any of a number of aids for facilitating
passage of the diagnostic or therapeutic instrument through the main
lumen, including a lubricious liner, rails or rollers.
The atraumatic tip of the present invention preferably is configured to
reduce the risk of capturing or pinching tissue between the overtube and a
diagnostic or therapeutic instrument that is selectively translated
through the overtube. This is preferably accomplished by the atraumatic
tip applying a radially-outwardly directed load to the wall of the hollow
body organ in the vicinity of the distal region where the diagnostic or
therapeutic instrument exits the apparatus.
In addition, the distal region of the overtube preferably includes a
flexible portion that permits a steerable tip of a diagnostic or
therapeutic device disposed within the distal region to deflect the distal
region of the overtube in a desired direction. This permits the overtube
to be readily advanced together with the steerable tip of the diagnostic
or therapeutic device.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features of the invention, its nature and various advantages will
be more apparent from the accompanying drawings and the following detailed
description of the preferred embodiments, in which:
FIG. 1 is a schematic view of a human colon illustrating a common
difficulty encountered in advancing a colonoscope beyond the sigmoid
colon;
FIG. 2 is a side view of illustrative apparatus of the present invention;
FIG. 3 is a side-sectional exploded view of nestable elements of a first
embodiment of an overtube suitable for use in the apparatus of FIG. 2;
FIG. 4 is a side-sectional view of a distal region of the apparatus of FIG.
2 constructed in accordance with principles of the present invention;
FIG. 5 is a side-sectional view of an illustrative arrangement of a
mechanism suitable for use in the handle of the apparatus of FIG. 2;
FIG. 6 is a side-sectional view of the detail of a wire clamping system
suitable for use in the handle of FIG. 5;
FIGS. 7A-7C are schematic views of a method of using the apparatus of the
present invention;
FIG. 8 is a schematic view of an alternative step in the method of using
the apparatus of the present invention;
FIG. 9 is a side view of an alternative embodiment of the apparatus of the
present invention;
FIGS. 10A and 10B, are a side-section view of an alternative element
suitable for use in the overtube of FIG. 2 and a roller element suitable
for use with the element of FIG. 10A, respectively;
FIGS. 11A and 11B depict the use of lubricious rails in the overtube of the
apparatus of FIG. 2 or 9 to facilitate passage of a diagnostic or
therapeutic device through the main lumen;
FIG. 12 is a schematic view of the lumen of the overtube of the present
invention depicting the use of multiple devices;
FIGS. 13-18 depict side-sectional views of various alternative embodiments
of an atraumatic tip constructed in accordance with the present invention;
FIGS. 19A-19C are, respectively, a side-sectional view of an alternative
embodiment of an overtube suitable for use in the present invention having
a multiplicity of interconnected links surrounded by a clamping sleeve,
and cross-sectional views of portions of the sleeve;
FIG. 20 is a side-sectional view of a further alternative embodiment of an
overtube constructed in accordance with the present invention having a
spiral bladder to actuate the clamping links;
FIG. 21 is a side-sectional view of another alternative embodiment of an
overtube of the present invention having thermally-actuable bands;
FIGS. 22A and 22B are side-sectional views of a yet further alternative
embodiment of an overtube of the present invention comprising a series of
helical links having regions of different durometer; and
FIG. 23 is a side-sectional view of yet another alternative embodiment of
an overtube having thermally regulated stiffness.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, problems associated with previously-known apparatus
and methods for inserting and advancing a diagnostic or therapeutic
instrument into a hollow body organ having tortuous or unsupported
anatomy, illustratively, patient's colon C, are described. Colon C
includes sphincter muscle SM disposed between anus A and rectum R. Rectum
R is coupled via the rectosigmoid junction RJ to sigmoid colon SC. Sigmoid
colon SC joins descending colon DC, which in turn is coupled to transverse
colon TC via left colic flexure LCF. Transverse colon TC also is coupled
by right colic flexure RCF to ascending colon AC and cecum CE, which
receives waste products from the small intestine.
As illustrated in FIG. 1, colonoscope 10 having steerable distal tip 11 is
typically inserted through anus A into rectum R, and then steered through
rectosigmoid junction RJ into sigmoid colon SC. As depicted in FIG. 1,
distal tip 11 of colonoscope 10 is advanced through sigmoid colon SC and
deflected into descending colon DC. Further urging of the colonoscope by
the physician can cause region 12 of the colonoscope to bear against and
cause displacement of the rectosigmoid junction RJ, as illustrated by
dotted lines 12' and RJ' in FIG. 1.
Such distension may result in patient discomfort or spasm, and if
unnoticed, could result in injury to the colon. The potential for movement
of colonoscope to cause distension, discomfort or spasm is also great
where the colonoscope must negotiate left colic flexure LCF and right
colic flexure RCF, and results in a large portion of such examinations
terminating before the physician can advance distal tip 11 to cecum CE.
The present invention provides apparatus and methods for placing a
diagnostic or therapeutic instrument through the tortuous or unpredictably
supported anatomy of a hollow body organ, such as the esophagus or colon,
while reducing the risk of distending or injuring the organ. Apparatus
constructed in accordance with the present invention permits an endoscope
or colonoscope to be readily advanced into a patient's tortuous or
unsupported anatomy by selectively shape-fixing an overtube portion of the
apparatus, while also preventing tissue from being captured or pinched
between the overtube and scope.
Referring now to FIG. 2, apparatus 20 of the present invention is
described. Apparatus 20 comprises handle 21, overtube 22, and distal
region 23 having atraumatic tip 24. Handle 21 includes lumen 25 that
extends from Toughy-Borst valve 26 through overtube 22, distal region 23
and atraumatic tip 24. Lumen 25 is configured to facilitate passage of a
standard commercially available colonoscope, such as colonoscope 10,
therethrough. Toughy-Borst valve 26 may be actuated to releasably lock
colonoscope 10 to apparatus 20 when colonoscope 10 is inserted within
lumen 25. As described hereinafter, overtube 22 is configured so that it
can be selectively transitioned between a flexible state and a rigid,
shape-fixed state by actuator 27 disposed on handle 21.
In FIG. 3, illustrative embodiment of overtube 22 comprises a multiplicity
of nestable elements 30. For purposes of illustration, nestable elements
30 are shown spaced-apart, but it should be understood that elements 30
are disposed so that their adjacent surfaces 31 and 32 coact. Each of
nestable elements 30 has central bore 33 to accommodate colonoscope 10,
and preferably three or more tension wire bores 35. When assembled as
shown in FIG. 2, nestable elements 30 are fastened with adjacent surfaces
31 and 32 disposed in a coacting fashion by a plurality of tension wires
36 that extend through tension wire bores 35.
In a preferred embodiment, adjacent surfaces 31 and 32 of each nestable
element 30 are contoured to mate with the next adjacent element, so that
when tension wires 33 are relaxed, surfaces 31 and 32 can rotate relative
to one another. Tension wires 36 are fixedly connected to the distal end
of overtube 22 at the distal ends and to a tensioning mechanism disposed
within handle 21 at the proximal ends. When actuated by actuator 27,
tension wires 36 impose a load that clamps adjacent surfaces 31 and 32 of
nestable elements 30 together at the current relative orientation, thereby
fixing the shape of overtube 22.
When the load in tension wires 36 is released, tension wires 36 provides
for relative angular movement between nestable elements 30. This in turn
renders overtube 22 sufficiently flexible to negotiate a tortuous path
through the colon. When the tensioning mechanism is actuated, however,
tension wires 36 are retracted proximally to apply a clamping load to the
nestable elements. This load prevents further relative movement between
adjacent elements 30, and stiffens overtube 22 so that any distally
directed force applied to colonoscope 10 causes distal tip 11 to advance
further into the colon, rather than cause overtube 22 to bear against the
wall of the colon. The shape-fixed overtube absorbs and distributes vector
forces, shielding the colon wall.
Referring now to FIG. 4, an illustrative embodiment of distal region 23 and
atraumatic tip 24 is described. Distal region 23 comprises flexible,
kink-resistant coil 41 encapsulated in flexible layer 42. Layer 42
preferably comprises a soft elastomeric and hydrophilic coated material,
such as silicon or synthetic rubber, and extends through bores 33 of
nestable elements 30 to form liner 43 for lumen 25. Layer 42 extends to
handle 21 at the proximal end, and at the distal end terminates in
enlarged section 44 that forms atraumatic tip 24.
Layer 42 preferably joins with or is integrally formed with flexible
elastomeric cover 45 which encapsulates nestable elements 30 in annular
chamber 46. Cover 45 provides a relatively smooth outer surface for
overtube 22, and prevents tissue from being captured or pinched during
relative rotation of adjacent nestable elements 30.
In accordance with one aspect of the present invention, colonoscope 10 may
be positioned with its distal tip 11 disposed in distal region 23, so that
deflection of steerable distal tip 11 imparts an angular deflection to
distal region 23 and atraumatic tip 24. To ensure that there is no gross
relative motion between colonoscope 10 and apparatus 20, Toughy-Borst
valve 26 is tightened to engage apparatus 20 to the colonoscope. In this
manner, colonoscope 10 and distal region 23 may be simultaneously advanced
through the colon, with the distal tip of the colonoscope providing a
steering capability to apparatus 20. Apparatus 20 therefore may be
advantageously advanced together with colonoscope 10 when overtube 22 is
in the flexible state, reducing relative motion between apparatus 20 and
colonoscope 10 to those instances where overtube 22 must be shape-locked
to prevent distension of the colon.
Still referring to FIG. 4, terminations 47 of tension wires are described.
Terminations 47 illustratively comprise balls welded or molded onto the
ends of tension wires 36 that ensure the tension wires cannot be pulled
through tension wire bores 35 of the distalmost nestable element 30. This
ensures that the nestable elements cannot come loose when overtube 22 is
disposed within a patient.
Alternatively, terminations 47 may comprise knots formed in the ends of
tension wires 36, or any suitable fastener that prevents the tension wires
from being drawn through the tension wire bores of the distalmost nestable
element. Advantageously, cover 45 provides additional assurance that all
of nestable elements 30 can be safely retrieved from a patient's colon in
the unlikely event of a tension wire failure.
Referring now to FIGS. 2 and 5, tension wires 36 within overtube 22, liner
43 and lumen 25 extend from distal region 23, through overtube 22, and to
handle 21. Within handle 21, each tension wire 36 passes through wire lock
release 51 fixedly attached to handle 21, and wire lock 52 disposed on
slide block 53. Each tension wire 36 terminates at wire tension spring 54,
which maintains tension wires 36 in light tension even when overtube 22 is
in the flexible state. The degree of tension provided by wire tension
springs 54 is not sufficient to clamp adjacent nestable elements 30
together, but on the other hand does not let gaps form between adjacent
nestable elements, and helps to manage the tension wire take up or slack
as overtube 22 makes various bends.
Slide block 53 is keyed to slide along rail 55 disposed between limit
blocks 56 and 57, and comprises a rigid block having a bore through which
rail 55 extends and an additional number of bores as required for the
number of tension wires 36 employed. Rack gear 58 is fixedly coupled to
slide block 53. Rack 58 mates with pinion gear 59, which is in turn driven
by bi-directional pawl 60 coupled to actuator 27. Pinion gear 59 may be
selectively engaged by either prong 61 or 62 of bidirectional pawl 60,
depending upon the position of selector switch 63.
If prong 61 is selected to be engaged with pinion gear 59, a squeezing
action applied to actuator 27, illustratively hand grip 64, causes rack 53
to move in the D direction in FIG. 5, thereby applying tension to tension
wires 36. Repeated actuation of hand grip 64 causes slide block 53 to move
progressively further in direction D, thereby applying an increasing
clamping load on nestable elements 30. Any slack lengths of tension wires
36 extending below slide block 53 are taken up by wire tension springs 54.
As discussed in greater detail below with respect to FIG. 6, wire locks
52, which are affixed to slide block 53, engage and retract tension wires
36 concurrently with movement of slide block 53 in the D direction.
If prong 62 is instead chosen by selector switch 63 to engage pinion gear
59, repeated actuation of hand grip 64 causes slide block 53 to translate
in direction U, thereby relaxing the tensile load applied by tension wires
36 to nestable elements 30. Repeated actuation of hand grip 64 causes
slide block 53 to advance in direction U until wire lock releases 51
engage wire locks 52, releasing all tension from tension wires 36 except
that provided by wire tension springs 54. This action permits the clamping
forces imposed on nestable elements 30 to be progressively reduced and
render overtube 22 progressively move flexible, until when wire lock
releases 51 engage wire locks 52, the overtube is returned to its most
flexible state.
Referring to FIG. 6, wire lock 52 and lock release 51 are described in
greater detail. Wire lock 52 includes jaws 65 disposed within collet 66.
Collet 66 includes a tapered conical bore 67. Jaws 65 have ramped exterior
surfaces 68 and teeth 69, and are biased against the surface formed by the
tapered conical bore by springs 70. Teeth 69 are configured to engage
tension wire 36 under the bias force of springs 70. When slide block 53 is
moved in direction D (see FIG. 5), jaws 65 engage and grasp tension wire
36 and retract the tension wire in direction D.
To disengage teeth 69 from tension wire 36, e.g., when it is desired to
allow overtube 22 to return to a flexible state, slide block 53 is
actuated as described previously to move in direction U. Further actuation
of slide block 53 towards limit block 56 and wire lock release 51 causes
wire lock release 51 to extend into tapered conical bore 67 and push jaws
65 backward against the bias of springs 70. Once tension wires 36 are
freed from jaws 65, overtube 22 returns to its most flexible state.
Referring to FIGS. 7A-7C, a method of using apparatus 20 is described.
Colonoscope 10 and overtube 22 may be inserted into the patient either
simultaneously or by first backloading the overtube onto the colonoscope.
To perform simultaneous insertion, colonoscope 10 is introduced into lumen
25 of handle 21 until distal tip 11 of the colonoscope is disposed in
distal region 23. Toughy-Borst valve 26 is actuated to lock apparatus 20
to colonoscope 10. As one unit, colonoscope 10 and overtube 22 are
inserted into rectum R of the patient, and navigated about rectosigmoid
junction RJ. As discussed previously, steerable distal tip 11 may be used
to impart angular deflection to flexible tip 24 to steer tip 24 about
tortuous curves, such as rectosigmoid junction RJ. Once distal tip 11 and
tip 24 have been negotiated past rectosigmoid junction RJ, the current
shape of overtube 22 is locked in the manner discussed above to provide a
rigid channel through which colonoscope 10 may be further advanced into
the colon without distending rectosigmoid junction RJ. Once distal tip 11
of colonoscope 10 is negotiated past sigmoid colon SC, overtube 22 is
released from its rigid state and advanced along colonoscope 10 until it
too traverses sigmoid colon SC. Again, the current shape of overtube 22 is
locked to provide a rigid channel for advancement of colonoscope 10. To
negotiate the remainder of the colon, such as left colic flexure LCF and
right colic flexure RCF, the preceding steps may be repeated. In this
manner, colonoscope 10 and overtube 22 may be navigated through the
tortuous curves of the colon without distending the colon, and thereby
causing discomfort, spasm or injury.
Alternatively, rather than simultaneously inserting both colonoscope 10 and
overtube 22 into the patient, apparatus 20 first may be backloaded onto
the colonoscope. First, overtube 22 is threaded onto colonoscope 10 and
positioned proximal distal tip 11, as shown in FIG. 8. Colonoscope 10 then
is inserted into rectum R of the patient and advanced around rectosigmoid
junction RJ. Overtube 22 is advanced along colonoscope 10 into rectum R of
the patient, using colonoscope 10 as a guide rail to negotiate
rectosigmoid junction RJ. Once overtube 22 traverses rectosigmoid junction
RJ to the position shown in FIG. 7A, the shape of overtube 22 is locked to
provide a rigid channel through which colonoscope 10 may be further
advanced into the colon. To negotiate the remainder of the colon, the
steps discussed in reference to FIGS. 7B-7C may be performed.
With respect to FIG. 9, an alternative embodiment of handle 21 is
described. Like handle 21 of FIG. 5, handle 71 also embodies a
ratchet-type tension mechanism, but in this embodiment overtube 22 may be
separated from handle 71, thereby permitting handle 71 to be sterilized
for repeated use. Handle 71 comprises housing 72 having actuator 73 that
engages teeth 74 disposed along the length of rod 75, which defines
working axis W of handle 71. Push knob 76 is affixed to the proximal end
of rod 75 so that when pawl 77 is released, rod 75 may be pushed in a
distal direction. Pawl 77 engages teeth 74 of rod 75 to prevent
distally-directed motion of rod 75. Spring 78 biases pawl 77 against teeth
74 of rod 75, to provide a one-way ratchet effect when actuator 73 is
squeezed.
As in the embodiment of FIG. 5, tension wires 36 extend through wire lock
releases 79, wire locks 80, and are coupled to wire tension springs 81.
Wire locks 80 are affixed to block 82, which translates within housing 72
responsive to movement of rod 75. Wire locks 80 and wire lock releases 79
operate in the same manner as described with reference to FIG. 6.
In operation, squeezing actuator 73, illustratively a hand grip, causes
fork 83 to move rod 75 in a proximal direction so that pawl 77 captures
the next distalmost tooth 74. This movement also causes wire locks 80 to
engage and grasp tension wires 36 and retract the tension wires
proximally. Further actuation of actuator 73 causes overtube 22 to stiffen
in the manner previously described. Spring 78 retains pawl 77 in
continuous engagement with teeth 74, thereby preventing rod 75 from moving
in the distal direction.
When it is desired to make overtube 22 more flexible, pawl 77 is released
and knob 76 pushed in the distal direction so that wire locks 80 engage
wire lock releases 79. As described above, this releases tension wires 36
from wire locks 80 and permits overtube to assume its most flexible state.
In accordance with one aspect of the present invention, overtube 22 of the
embodiment of FIG. 9 may be replaceably removed from yoke 84 of handle 71.
In addition tension wires 36 further may comprise connectors 85 that
permit the tension wires to be disconnected. Such a configuration permits
the overtube to be removed and discarded after a single use, while the
handle may be sterilized and reused.
Yoke 84 is also configured to position overtube 22 so that longitudinal
axis L of the overtube is angularly displaced from working axis W by a
predetermined angle .beta.. This arrangement prevents handle 71 from
interfering with advancement of colonoscope 10 into lumen 25.
In accordance with yet another aspect of the present invention, overtube 22
includes atraumatic tip 86 that comprises a soft foam-like material.
Atraumatic tip 86 not only facilitates advancement of overtube 22 in
traversing tortuous anatomy, but also serves to retain the organ wall a
safe distance away from the opening through which the colonoscope is
reciprocated by radially expanding the organ wall in the vicinity of the
tip, as described hereinbelow with respect to FIG. 14A. Accordingly,
atraumatic tip 86 reduces the potential for tissue to be caught or pinched
in lumen 25 when the colonoscope is manipulated.
With respect to FIGS. 10A and 10B, an alternative structure is described to
facilitate movement of a colonoscope within lumen 25 of overtube 22. In
particular, instead of using inner lining 43 as depicted in FIG. 4, some
or all of nestable elements 30 may include roller bearings 87 that are
received in insets 89 formed in nestable elements 30. Bearings 87 may be
disposed on ring 88 to facilitate assembly of the device.
FIGS. 11A and 11B depict a further alternative embodiment, in which
lubricious flexible rails 90 are disposed within bore 33 of nestable
elements 30. Rails 90 span the length of lumen 25, and reduce contact
between the colonoscope and the interior of the overtube, thereby
facilitating movement of the colonoscope through overtube 22.
In accordance with another aspect of the present invention, the diameter of
lumen 25 preferably is configured to facilitate simultaneous passage of
more than one diagnostic or therapeutic instrument therethrough. As shown
in FIG. 12, lumen 25 may be dimensioned to permit auxiliary devices AD,
such as for aspiration, biopsy, or additional lighting, to be advanced
alongside colonoscope 10. For example, if lumen 25 has a diameter of 13 mm
and colonoscope 10 has an outer diameter of 10 mm, auxiliary device AD,
such as a catheter, having a diameter of between 3 F to 9 F may be
advanced through the remaining space within lumen 25. Advantageously, this
permits auxiliary devices AD to be successively placed within the
patient's colon to perform additional diagnostic or therapeutic procedures
without the need to remove colonoscope 10 and overtube 22 therefrom.
Referring to FIG. 13, an alternative embodiment of a distal region suitable
for use in the overtube of the present invention is described. Distal
region 100 is similar in construction to distal region 23 of the
embodiment of FIG. 4, but has flexible coil 101 embedded in only the
proximal portion of elastomeric layer 102. Atraumatic tip 102 at the
distal end of distal region 24 may further enhance the steerability of the
overtube 22 when the steerable tip of the colonoscope is disposed therein.
FIGS. 14-18 illustrate additional configurations of atraumatic tips
suitable for causing "tenting" of the wall of the hollow body organ. As
used herein, tenting refers to the tendency of the atraumatic tip to be
deflected radially outward in the vicinity of the tip of the overtube.
This reduces the risk that the wall of the organ will become pinched or
caught between the colonoscope and the entry to overtube 22 when the
colonoscope is retracted within the overtube.
FIG. 14A shows atraumatic tip 24 in the form of an inflatable donut-shaped
balloon 110 affixed to distal region 23 of overtube 22. Inflation lumen
111 extends from the handle through overtube 22 to provide fluid
communication between balloon 110 and an inflation source, such as a
syringe (not shown). As illustrated in FIG. 14B, when balloon 110 is
inflated, the wall of the colon radially deflects around balloon 110.
Thus, when colonoscope 10 is retracted into lumen 25, it is less likely
that the wall of the colon will be pinched or potentially dissected
between overtube 22 and colonoscope 10.
FIG. 15 depicts a further alternative embodiment of atraumatic tip 24,
comprising soft membrane 120 covering shape memory alloy petals 121.
Petals 121 preferably comprise loops of shape memory alloy wire, e.g.,
nickel titanium alloy, and extend radially outward in the proximal
direction near the distal opening into lumen 25, so that the proximal end
of membrane-covered petals causes the "tenting" effect described
hereinabove. The shape memory alloy may be activated to adopt a pre-formed
shape when exposed to body temperature, and returned to a contracted state
by flushing overtube 22 with cold water or air. Alternatively, petals 121
may be mechanically extended or retracted, or self-expanding.
FIG. 16 depicts a further alternative embodiment of atraumatic tip 24. In
the embodiment of FIG. 16, petals 130 covered by soft elastomeric membrane
131 extend distally from distal region 23 to form funnel-shaped element
132. Atraumatic tip 24 provides a similar tenting effect to that described
for the preceding embodiments.
FIGS. 17-18 provide further alternative configurations for atraumatic tip
86 of the embodiment of FIG. 9. Tip 140 preferably comprises a foam or
soft elastomer, and may be affixed to distal region 23 of overtube 22
using a suitable biocompatible adhesive. FIG. 18 depicts an alternative
shape for a foam or soft elastomer bumper 150, which includes a
proximally-extending flange 151. Of course, one of ordinary skill in the
art will recognize that other configurations may be used in accordance
with the principles of the present invention to form atraumatic tips that
cause localized tenting of the colon wall, and these atraumatic tips may
be used with the passively-steerable distal regions of the embodiments of
FIGS. 4 and 13.
With respect to FIGS. 19-23, alternative embodiments of overtube 22 are
described. Unlike overtube 22 of the above-described embodiments, which
comprised a multiplicity of nestable elements that are clamped with a
plurality of tension wires, the embodiments of FIGS. 19-23 use alternative
clamping mechanisms. In particular, the following embodiments comprise a
plurality of links that may be stiffened by the use of compressive sleeves
that compress individual links disposed along the length of the overtube.
Referring now to FIGS. 19A-19C, a first alternative embodiment of the
overtube of the present invention is described. Overtube 160 comprises a
multiplicity of alternating spool links 161 and clamp links 162. Each
spool link 161 and clamp link 162 has a bore disposed therethrough to
accommodate a standard colonoscope. Spool link 161 comprises rounded edges
163 disposed on its distal and proximal ends that are contoured to permit
limited rotatable engagement with one of two contoured grooves 164
disposed within the bore of clamp link 162. Accordingly, clamp link 162
comprises a greater outer diameter than spool link 161. Each clamp link
162 also has through-wall split 168 longitudinally disposed to permit a
reduction in the diameter of clamp link 162 when the clamp link is
compressed, as discussed hereinafter.
Still referring to FIGS. 19A-19C, a first embodiment of a compressive
sleeve comprising inflatable sleeve 165 having first compressive portions
166 and second compressive portions 167. Sleeve 165 is configured so that
the inner diameters of second compressive portions 167 are smaller than
those of first compre
