Endoscope articulation system to reduce effort during articulation of an endoscope

An endoscope having an articulation system that provides a mechanical advantage and facilitates articulation of the distal section of the endoscope insertion tube. The endoscope includes a handle held by a user during an endoscopic procedure and an insertion tube attached at its proximal section to the handle. A plurality of control cables extending the length of the insertion tube are securely attached to the insertion tube's distal section and are axially movable to articulate the distal section. Control wheels are rotatably attached to the handle and positioned to be manipulated by the user during the endoscopic procedure. The articulation system is connected at one end to the control cables and at the other end to the control wheels. The articulation system transmits movement of the control wheels to the control cables. The articulation system is partially linearly movable between the control wheels and the control cables upon movement of at least one control wheel so as to provide a mechanical advantage in converting force from the control wheel to the control cable. The articulation system is configured with approximately a two-to-one mechanical advantage, such that a force exerted on the control wheel is approximately one-half of the force that is transmitted to the control cable to move the control cable axially, thereby articulating the insertion tube's distal section.

TECHNICAL FIELD 
The present invention relates to the field of endoscopy, and more 
particularly, to a system for articulation of an endoscope. 
BACKGROUND OF THE INVENTION 
The use of endoscopes for diagnostic and therapeutic indications is rapidly 
expanding. To improve performance, specialized endoscopes have been 
developed for specific uses. For example, there are upper endoscopes for 
examination of the esophagus, stomach, and duodenum, colonoscopes for 
examining the colon, angioscopes for examining blood vessels, 
bronchoscopes for examining the bronchia, laparoscopes for examining the 
peritoneal cavity, and arthroscopes for examining joint spaces. The 
discussion which follows applies to all of these types of endoscopes and 
any modifications thereof. 
There has been a large increase in the use of endoscopes for screening 
symptomatic and asymptomatic patients. These endoscopes are expensive and 
are used in contaminated and sensitive environments. Conventional 
endoscopes typically have an elongated insertion tube that is inserted 
into a patient at a point of entry and extended to a selected body cavity. 
The insertion tube is connected at its proximal end to a handle portion. 
The distal end of the insertion tube is controlled and steered by control 
cables that are attached to the insertion tube's distal end and extend the 
length of the insertion tube. The control cables are directly connected to 
control wheels mounted to the handle portion. The control wheels are used 
to control articulation of the insertion tube by rotating the control 
wheels relative to the handle, thereby pulling directly on the control 
cables and causing the distal section of the insertion tube to bend. 
Accordingly, the insertion tube can be steered by a physician to follow 
the contours of a pathway through the patient's body to desired body 
cavity. The tip of the insertion tube must be accurately steerable in the 
up/down and left/right directions to permit the physician to place the tip 
at a selected location once the distal end of the insertion tube is within 
the selected body cavity. 
The insertion tube of a conventional, non-sheathed endoscope includes a 
biopsy channel, suction channels, and air and water channels that extend 
along the length of the insertion tube. The insertion tube is axially 
rigid, yet sufficiently flexible to allow it to follow the curves and 
bends along the pathway in the patient; however, it must be sufficiently 
stiff in order to prevent the biopsy channel, the suction channel, or the 
air and water channels from collapsing when the insertion tube is 
articulated. 
Improved endoscopes are used with an endoscopic sheath, as is described in 
U.S. Pat. No. 4,646,722, to Silverstein et al. The sheath covers and 
isolates the insertion tube from the contaminated environment. The sheath 
typically includes a plurality of integral channels, including a biopsy 
channel, a suction channel, and air and water channels. The endoscope 
sheath is sufficiently flexible to bend with the insertion tube while 
being stiff enough to prevent the channels from kinking or collapsing 
during articulation of the insertion tube. 
It is especially important that the biopsy channel of the insertion tube or 
sheath not collapse or excessively narrow because an endoscopic accessory, 
such as a forceps or the like may be required to travel along the biopsy 
channel during an endoscopic procedure, or alternatively, it may be 
necessary to remove particulate matter from the tip of the endoscope 
through the biopsy channel. In addition, the endoscopic accessories 
further add to the overall stiffness of the sheathed or unsheathed 
insertion tube. 
The necessary stiffness of the unsheathed or sheathed insertion tube 
results in a significant resistance to articulation of the insertion 
tube's distal end that is felt by the physician during manipulation of the 
control wheels. The resistance to articulation is overcome by exerting a 
significant amount of axial force on the selected control cables. 
Accordingly, a significant amount of force must be exerted by the 
physician on the conventional control wheels so as to sufficiently pull on 
one or more of the control cables to overcome the inherent resistance to 
bending. 
During a clinical procedure the handle portion of the instrument is 
typically held in the physician's left hand. The right hand is usually 
placed on the endoscope's shaft to advance the instrument into the patient 
and to retract the instrument out of the patient. Preferably, the 
physician's right hand is not used to manipulate the control wheels in 
order to avoid contamination of the endoscope. Accordingly, the control 
wheels are adjusted with only one hand. The physical effort required to 
rotate the control wheels with one hand to overcome the stiffness of the 
insertion tube, sheath, and accessory can result in excessive fatigue of 
the physician's left hand, particularly during a long endoscopic 
procedure. The excessive effort required to articulate the insertion tube 
also greatly increases the duration of a procedure, thereby reducing the 
cost efficiency of the endoscopic procedure. 
Conventional endoscopes have been designed to reduce the amount of effort 
required to move the control wheels by rigidly connecting a small diameter 
drum located within the handle portion to a large diameter control wheel 
that is rotated by the physician's thumb. The control cables extend around 
the small diameter drum so as to move axially when the drum is rotated. 
Although the combination of the large control wheel and smaller drum 
facilitates articulation of the insertion tube's distal end, the optimum 
size combination of control wheel and drum still requires a substantially 
large force to be exerted by the physician on the control wheels to 
achieve the necessary torque on the drum to steer or otherwise control the 
insertion tube's distal end. 
There are other endoscopic devices which require the generation of a force 
at the distal tip of the device. A lithotripter is a basket device which 
is used to crush kidney or bile stones for removal. A conventional 
lithotripsy device uses a screw mechanism that is rotated at its proximal 
end in order to provide sufficient force at the distal end to crush the 
stones and facilitate their removal. The force required to turn the screw 
to generate the sufficient force to crush the kidney or bile stones is 
typically high enough that it is very difficult for the physician to 
maintain during the endoscopic procedure without mechanical advantage. 
SUMMARY OF THE INVENTION 
The present invention is directed toward an endoscope articulation system 
that reduces the amount of effort and force necessary for use of the 
control mechanism to articulate the distal end of an endoscopic device. In 
a preferred embodiment of the invention, an endoscopic device includes a 
handle and an insertion tube attached to the handle. The insertion tube 
has a distal section that is articulatable relative to a proximal section 
that engages the handle. At least one control cable is securely attached 
to the insertion tube's distal section, and the control cable extends 
proximally toward the handle. The control cable is axially movable 
relative to the insertion tube to cause the distal section of the 
insertion tube to articulate. A control member is movably attached to the 
handle and positioned for ease of manipulation by a user to control 
articulation of the distal section of the insertion tube. The control 
member is movable upon a first force being applied thereto by the user. 
The articulation system is connected to the control member and to the 
control cable. The articulation system includes a component that is 
substantially linearly movable relative to the control member so as to 
convert the first force, which is applied to the control member, into a 
second force that is exerted on the control cable, thereby causing the 
axial movement of the control cable and articulation of the distal 
section. The second force is greater than the first force, such that the 
articulation system provides a mechanical advantage between movement of 
the control member and axial movement of the control cable. 
In the preferred embodiment, the control member includes a control wheel 
and drum assembly. The articulation system includes a movable pulley and 
connecting cable. The connecting cable extends around the movable pulley 
and around the drum. The movable pulley is securely connected to an end of 
the control cable, and the pulley is substantially linearly movable 
relative to the drum and control wheel upon rotation of the control wheel 
and drum. This configuration provides increased mechanical advantage 
between movement of the control member and axial movement of the control 
cables, with the result that a reduced force exerted by the physician or 
other user is needed at the control wheel in order to articulate and steer 
the distal end of the insertion tube. 
In an alternate embodiment of the invention, the articulation system 
includes a lever that is pivotally mounted at a pivot point to the handle. 
The control cable is attached to a first portion of the lever at a first 
distance from the pivot point, such that pivotal movement of the lever 
results in substantially linear movement of the lever's first portion and 
axial movement of the control cable. A connecting member connects the 
lever to the drum and control wheel, such that rotation of the control 
wheel causes the lever to pivot relative to the handle, thereby causing 
the control cable to move axially. The connecting member is connected to 
the lever at a second distance from the pivot point that is different than 
the first distance, so the lever provides a mechanical advantage in 
transferring force from the control wheel to the control cable.

DETAILED DESCRIPTION OF THE INVENTION 
As shown in FIG. 1, an articulation system 10 in accordance with a 
preferred embodiment of the invention is positioned within a handle 12 of 
a sheathed endoscope 14 that is used by a physician to perform endoscopic 
procedures. The endoscope 14 has an elongated insertion tube 16 connected 
at its proximal section 18 to the handle 12. A distal section 22 of the 
insertion tube 16, opposite the proximal section is shaped and sized to 
extend into a selected body cavity of a patient. As is well known in the 
art, the insertion tube 16 includes a device for conveying an image from 
the insertion tube's distal section 22 to an eyepiece 24 connected to the 
proximal end of the handle 12. A number of devices can be used to perform 
this function, including, for example, a lens that is optically coupled to 
the eyepiece through an optical waveguide, or a miniature camera that is 
electronically coupled to a monitor. The imaging device enables the 
physician to see portions of the patient's body cavity and to see objects 
located just beyond the distal section 22 of the insertion tube 16 during 
the endoscopic procedure. 
The insertion tube 16 in the illustrated embodiment is removably positioned 
within an endoscopic sheath 26 to isolate the insertion tube from the 
contaminated environment during the endoscopic procedure. The sheath 26 
has a plurality of channels extending along its length, including an 
endoscope channel that receives and isolates the insertion tube 16, air 
and water channels that direct air and water to the distal end of the 
insertion tube, a suction channel that provides a suction force at the 
insertion tube's distal end 22, and a biopsy channel 28 that slidably 
receives an endoscopic accessory 30 therein. The endoscopic accessory 30 
typically includes an elongated, axially rigid shaft, such as a 
kink-resistant catheter, with a tool on the distal end that is passed 
through the biopsy channel 28 and beyond the open distal end of the biopsy 
channel to perform a selected endoscopic procedure that is viewed through 
the insertion tube 16 via the eyepiece 24. 
The biopsy channel 28, the air and water channels, and the suction channel 
are flexible enough to bend when the insertion tube 16 articulates, but 
are sufficiently stiff to prevent kinking of the channels during the most 
extreme articulation. The stiffness of the channels of the sheath 26, the 
endoscopic accessory 30, and the insertion tube 16 combine to 
significantly resist articulation of the insertion tube's distal section 
22. 
The insertion tube 16 includes a plurality of control cables 32 that are 
securely attached to the distal section 22 of the insertion tube and 
extend proximally along the length of the insertion tube to the handle 12. 
The control cables 32 are axially movable within the insertion tube 16 
except at their distal ends, such that the control cables cause the distal 
section 22 of the insertion tube to articulate in the up/down or 
left/right directions when a selected cable is moved axially. 
A control mechanism 34 that includes two control wheels 36 and 38 is 
rotatably mounted on the handle 12 in a position that allows a physician 
to rotate the control wheels with his or her thumb while holding the 
handle with the same hand. The control wheels 36 and 38 are coupled to the 
control cables 32 by the articulation system 10, as discussed in detail 
below, such that rotation of one of the control wheels results in axial 
movement of at least one control cable, thereby articulating the distal 
section 22 of the insertion tube 16. The articulation system 10 provides a 
mechanical advantage between the control wheels 36 and 38 and the control 
cables 32 to reduce the amount of force needed to be exerted by the 
physician on the control wheels in order to articulate the insertion 
tube's distal section 22. Accordingly, the physician can easily control 
the position and degree of articulation of the distal section 22 and 
precisely position the distal end of the insertion tube for performing a 
selected diagnostic or therapeutic procedure without excess fatigue. 
As best seen in FIG. 2, the articulation system 10 is positioned within an 
interior chamber 40 defined by sidewalls 42 of the handle 12. The 
articulation system 10 is attached to the proximal ends of the control 
cables 32, which extend into the distal portion of the handle 12. The 
articulation system 10 extends between the proximal ends of the control 
cables 32 and the control mechanism 34 located at the proximal portion of 
the handle 12. 
As best seen in FIG. 3, the control mechanism 34 includes an inner control 
wheel 36 rigidly connected to an exterior shaft 44 that extends through a 
sidewall 42 of the handle 12 and rigidly connects to a first coaxially 
aligned drum 46 within the interior chamber 40. The control mechanism 34 
also includes an outer control wheel 38 rigidly connected to an interior 
shaft 48 that is positioned partially within the exterior shaft 44 and 
coaxially aligned with the inner control wheel 36 and the first drum 46. 
The interior shaft 48 extends through the inner control wheel 36, the 
exterior shaft 44, and the first drum 46, and rigidly connects to a second 
drum 50 adjacent to the first drum. Accordingly, the inner and outer 
control wheels 36 and 38 are independently rotatable relative to each 
other and relative to the handle 12 so as to independently rotate the 
first and second drums 46 and 50. The first and second drums 46 and 50 
each have a diameter that is smaller than the diameter of their respective 
control wheels 36 and 38 in order to provide a first degree of mechanical 
advantage between the force exerted on the control wheel and the force 
transmitted by the drum. 
The first and second drums 46 and 50 each have an annular groove 52 
therearound that securely receives a control wire 54 of the articulation 
system 10, such that rotation of the first and second drums move their 
respective control wires around the drum without slippage. Accordingly, 
rotation of, for example, the inner control wheel 36 by a physician or 
other user causes the exterior shaft 44 to rotate which, in tin-n, causes 
the first drum 46 to rotate, thereby moving the control wire 54 around the 
first drum. 
As best seen in FIG. 2, the control wire 54 has an upper section 56 that 
extends distally away from the top of the respective drum toward the 
control cables 32 and a lower section 58 that extends distally away from 
the bottom of the drum. The upper and lower sections 56 and 58 are 
integrally connected by the portion of the control wire 54 wrapped around 
the respective drum. The control wire 54 has a fixed length, such that 
when the control wheel 36 or 38 is rotated, the upper and lower sections 
56 and 58 move axially in the opposite directions. In the preferred 
embodiment, the control wire 48 is a stainless steel cable, although other 
suitable materials can be used, and the drum and control wheel can be 
modified in order to maintain secure engagement with the control wire 
without slippage of the control wire over the drum. 
Each control wire 54 is coupled to two of the control cables 32 by flexible 
connecting cable portions 60 and 62 and movable pulleys 64 and 66 of the 
articulation system 10. For purposes of simplicity, only one control wire 
54 is illustrated in FIG. 2 being coupled to first and second control 
cables 68 and 70. The first control cable 68 controls upward articulation 
of the insertion tube's distal section 22, and the second control cable 70 
controls downward articulation of the insertion tube's distal section. It 
is to be understood that, in the preferred embodiment, a second control 
wire 72, illustrated in FIG. 3, is coupled in the same manner to two 
similar control cables that control left and right articulation of the 
insertion tube's distal section. 
The upper section 56 of the control wire 54 is securely connected at its 
distal end to a first end of the upper flexible cable portion 60 by a 
cable coupling device 74, so axial movement of the upper section causes 
axial movement in the upper flexible cable portion without any stretching 
of the flexible cable. The upper flexible cable portion 60 extends around 
an upper movable pulley 64 and is securely anchored at its second end to 
the sidewall 42 of the handle 12. The upper section 56 of the control wire 
54 and the upper flexible cable portion 60 are pulled axially toward the 
first drum 46 when the control wheel 36 and first drum are rotated 
counterclockwise. Thus, the upper flexible cable portion 60 is pulled over 
the upper movable pulley and the upper movable pulley 64 is pulled 
substantially linearly and proximally away from the insertion tube 16. The 
proximal movement of the upper movable pulley 64 causes the first control 
cable 68 to move axially within the insertion tube 16 and to articulate 
the insertion tube's distal section upwardly. 
Accordingly, the articulation system 10 transmits the rotational movement 
of the control wheels 36 and 38 to the axial movement of the control 
cables 32. The upper movable pulley 64 moves in a substantially linear 
direction relative to the control wheels 36 and the first drum 46, and 
provides a two-to-one mechanical advantage between the first control cable 
68 and the control mechanism 34. As a result, the force exerted on the 
control wire 54 at the first drum 46 is approximately one-half of the 
axial force exerted by the upper movable pulley 64 on the first control 
cable 68. Thus, the articulation system 10 converts the first force 
exerted by a physician on a control wheel to the increased second force on 
the selected control cable to cause axial movement of the control cable 
and the articulation of the insertion tube's distal section. The 
articulation system 10 also allows for substantially reduced physical 
exertion by a physician in order to articulate and steer the distal 
section of the endoscope. 
Similar to the control wife's upper section 56, the lower section 58 is 
rigidly connected to the first end of a lower flexible cable portion 62 
that extends around the lower movable pulley 66 and is anchored at its 
second end to the handle's sidewall 42. The lower movable pulley 66 is 
securely connected to the second control cable 70. The lower movable 
pulley 66 moves in a substantially linear direction relative to the 
control mechanism 34, and provides a two-to-one mechanical advantage 
between the second control cable 70 and the control mechanism 34. 
Accordingly, the force exerted on the control wire 54 at the second drum 
50 (FIG. 3) is approximately one-half of the axial force exerted on the 
second control cable. 
The control wire 54 and the upper and lower cable portions 60 and 62 form a 
connecting cable 63 that extends around the movable pulleys 64 and 66 and 
that connects to the control mechanism 34. Accordingly, as shown in FIG. 
2, the control cables 68 and 70 do not wrap around the movable pulleys 64 
and 66. 
In one embodiment of the invention, the upper and lower flexible cable 
portions 60 and 62 are constructed of a non-stretchable, fine, 
multi-strand metallic cable or, in the alternative, a non-metallic 
flexible material, such as oriented ultra-high molecular weight 
polyethylene. As indicated above, the upper and lower section 56 and 58 of 
the control wire 48 are integrally connected by the portion extending 
around the drum 46, such that the upper and lower sections, the upper and 
lower flexible cable portions 60 and 62, the upper and lower movable 
pulleys 64 and 66, and the respective first and second control cables 68 
and 70 move simultaneously in opposite directions relative to the handle 
12 when the inner control wheel 36 is rotated. A similar configuration is 
provided for the control cables that control left and right motion, such 
that rotation of the outer control wheel 38 and second drum 50 causes one 
movable pulley to move distally relative to the second drum as the other 
movable pulley moves proximally, thereby causing the distal section of the 
insertion tube to articulate either left or right. 
As best seen in FIG. 4, the upper movable pulley 64 includes a pulley wheel 
76 that is rotatably mounted on an axle 78 extending between two 
sideplates 80 that protect the pulley wheel. The pulley wheel 76 has an 
outer sheave 82 extending about its outer circumference. The outer sheave 
82 has a groove 84 formed therein that is shaped to securely receive and 
grip the upper flexible cable portion 60 therein to prevent slippage as 
the flexible cable moves around the pulley wheel 76. The outer sheaf 82 
also maintains the upper flexible cable portion 60 in a centered position 
around the pulley wheel 76. The movable pulley 64 further includes a pin 
86 that extends between leg portions 88, shown in FIGS. 2 and 4, and the 
pin extends through a connection member 90 that is rigidly attached to the 
first control cable 70. The connection member 90 is allowed to move along 
the pin 86 between the leg portions 88 so the angular orientation of the 
first control cable 68 relative to the upper movable pulley 64 can change 
as the upper movable pulley and the first control cable move between 
distal and proximal positions within the handle 12. The pin 86 and 
connection member 90 arrangement effectively reduces the bending forces 
exerted on the proximal end of the first control cable 68 when the movable 
pulley and the control cable are in the distal-most position. The lower 
movable pulley 66 has configuration identical to the upper pulley 68, and 
the lower movable pulley is connected to the lower control cable with the 
same type of connection member 90. 
Although the illustrated embodiment obtains a two-to-one mechanical 
advantage with a single movable pulley connected to each control cable, 
greater mechanical advantage can be achieved between the control wheel and 
each control cable by use of more than one pulley as in, for example, a 
block-and-tackle arrangement. The movable pulleys 66 and 68 of the 
illustrated articulation system 10 allow for the increased mechanical 
advantage with movable pulleys that are small enough to be contained and 
isolated within the confines of the handle's interior chamber 40. However, 
the movable pulleys do not have to be completely contained within the 
interior chamber. 
While the arrangement can be used to improve mechanical advantage of a 
conventional, unsheathed endoscope design, it is especially important for 
non-conventional endoscope design, such as the flexible endoscope 14 
illustrated in FIG. 1 that is used with the disposable sheath 26. In these 
non-conventional, non-symmetrical designs, the force required to 
articulate the distal section of the insertion tube is greater than the 
conventional endoscopes, because the stiffness of the disposable sheath is 
combined with the inherent stiffness of the endoscope, as discussed above. 
As best seen in FIG. 5, an alternate embodiment of the articulation system 
10 is illustrated having a system utilizing a movable pulley 92, a lower 
flexible cable portion 62, and control cable 54 that are similar to the 
embodiment discussed above. The movable pulley 92 is securely connected to 
a left control cable 94 that controls articulation of the insertion tube's 
16 distal section in the left direction. The upper section 56 of the 
control wire 54 extends distally away from the second drum 66 and connects 
at its distal end to an upper end 96 of a lever 98. The lever 98 is 
pivotally connected to the handle 12 within the interior chamber 40, and 
the lever pivots about a pivot point 100 that is at a first distance from 
the distal end of the control wire's upper section 56. When the outer 
control wheel 38 is rotated counterclockwise, the control wife's upper 
section 56 pulls the lever's upper end 96 substantially linearly and 
proximally through an arc, causing the lever to pivot about the pivot 
point 100. Conversely, when the outer control wheel 38 is rotated 
clockwise, the lever 98 pivots, such that the upper end 96 moves 
substantially linearly and distally through an arc. 
The proximal end of the right control cable 102, which controls 
articulation of the insertion tube's distal section in the right 
direction, is securely connected to the lever 98 at a mid-point 104 
between the lever's upper end 96 and the pivot point 100. In the 
illustrated embodiment, the distance from the pivot point 100 to the 
mid-point 104 is approximately half the distance between the distal end of 
the control wire's upper section 56 and the pivot point 100. When the 
outer control wheel 38 is rotated counterclockwise and the lever 98 pivots 
about the pivot point 100, the mid-point 104 moves proximally in a 
generally linear direction toward the control wheel, thereby pulling the 
right control cable 102 axially in the proximal direction. The lever 98 
provides approximately a two-to-one mechanical advantage over a 
configuration with the control wire 54 directly attached to the right 
control cable 102. Accordingly, a first amount of force exerted on the 
control wire via the outer control wheel 38 results in a second force that 
is twice the first force and that is exerted axially on the right control 
cable 102. Thus, the lever 98 and control wire 54 work together to 
transmit the rotational movement of the outer control wheel 38 to the 
axial movement of the control cable 102. The lever 98 and control wire 54 
also work together to convert the first force exerted by the physician on 
the control wheel 38 to the increased second force exerted on the right 
control cable 102 to cause axial movement of the control cable and 
articulation of the insertion tube's distal section. 
This increased mechanical advantage allows the physician to easily 
articulate the distal section of the insertion tube with a reduced effort, 
as discussed above. Although the illustrated alternate embodiment shows 
the lever providing a two-to-one mechanical advantage, other alternate 
embodiments can have the connection point of the control cable at a 
position along the length of the lever other than the mid-point to 
increase or decrease the mechanical advantage as desired. In addition, the 
illustrated alternate embodiment has the lever 98 used in conjunction with 
a lower movable pulley 66, although the lower movable pulley may also be 
replaced by a similar lever mechanism to provide the increased mechanical 
advantage between the control mechanism and control cable. Further, it is 
to be understood that either a lever assembly, a movable pulley, or other 
mechanical advantage coupler in accordance with the present invention can 
be connected to the upper, lower, left, or right control cables to provide 
the increased mechanical advantage. 
Numerous modifications and variations of the endoscope articulation system 
to reduce effort during articulation of an endoscope invention disclosed 
herein will occur to those skilled in the art in view of this disclosure. 
Other types of devices that provide mechanical advantage between the 
control wheel and the control cable can be used while remaining within the 
spirit and scope of the present invention. Therefore, it is to be 
understood that these modifications and variations, and equivalents 
thereof, may be practiced while remaining within the spirit and the scope 
of the invention as defined in the following claims.