Note: Descriptions are shown in the official language in which they were submitted.
CA 02274270 1999-06-08
Vessel Isolating Retractor Canauia and Method
Inventors:
John P. Lunsford
Charles Gresl. Jr.
Albert K. Chin
John W. Davis
Teeny Chang
Jeffrey W. Baxter
field of the Invention
This invention relates to a cannula used for vein retraction. and more
particularly
to a cannula and method that includes a vein retractor having a tirst portion
that is
approximately parallel to the axis of the cannula and a second portion that is
positioned at
an angle with respect to the axis of the cannula.
Backeround of the Invention
Certain cannulas have surgical tools located within the cannula for performing
surgical operations on a vessel of interest. The cannula is inserted into a
surgical site
with the distal end of the cannula positioned near the vessel of interest. An
endoscope
positioned within the cannula allows the surgeon to view the target area. and
allows the
surgeon to position the surgical tool correctly.
However. the surgical tool may be inadequate to safely and effectively perform
its '
operation. For example. if the target vessel is a side branch or tributary of
a vein such as
a saphenous vein. the surgical tool may sever or damage the vein while being
used to cut
the side branch. Thus. there is needed a cannula which is able to isolate the
target vessel
of interest to ailow the surgical tool to perform safely and effectively.
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Summary of the Invention
In accordance with the present invention. a retractor is positioned within a
cannula
with a dissection cradle end of the retractor positioned at the distal end of
the cannula.
The retractor includes a first portion that has an a.~cis approximately
parallel to a central
axis of the cannula. and a second portion that has an a~cis which is at an
angle with respect
to the central axis of the cannula. The dissection cradle is located at the
distal end of the
second portion of the retractor. In another embodiment, the retractor includes
two legs
having a substantially parallel axis that selectively protrude from the distal
end of the
cannula to support the dissection cradle formed in the shape of a loop that is
positioned in
a plane skewed relative to the axis of the legs, with a bottom of the loop
directed away
from the cannula. Thus, in operation, when the surgeon locates a vein and side
branch of
interest. the surgeon extends the retractor to cradle the vein in the
dissection cradle. Once
cradled, the retractor may be fully extended. pulling the vein away from the
axis of the
cannula. causing the side branch to be isolated and exposed to a surgical
tool. The
surgical tool may then be extended from within the cannula to operate on the
isolated and
exposed side branch.
In another embodiment. the top of the loop of the dissection cradle is flat
and thin,
allowing atraumatic support of the vein. and minimizing contact between the
retractor
and the surgical tool. In yet a further embodiment, the retractor includes a
single leg with
the loop formed by the one lee of the retractor, and with a stopper coupled to
the distal
end of the retractor. In still another embodiment. the cannula comprises a
sliding tube
which encases the retractor. and in a tirst position is extended out to encase
the second
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portion of the retractor. and in a second position is extended to encase only
the first
portion of the retractor. In response to being in the first position, the
second and first
portions of the retractor are both approximately parallel to the axis of the
cannula. In the
second position. the second portion of the retractor is at an angle to the
axis of the
cannula.
Brief Description of the Drawings
Figure 1 is a perspective view of a preferred embodiment of cannuia 100
showing
retractor l 12 in an extended position.
Figure 2a is a cut-away side view of retractor 112 and cannula 100.
Figure 2b is a top view of retractor 112.
Figure 3a is a perspective side view of cannula 100 with a saphenous vein
positioned within the cradle 116.
Figure 3b is a perspective side view of the distal end 122 of cannula 100 in
an
embodiment in which an endoscope 126 and a surgical tool 120 are present and
partially
extended.
Figure 3c is a front view of the distal end 122 of cannula 100 in which the
surgical
tool 120 and the retractor 116 are partially extended, and an endoscope 126 is
present. -
Figure ~a is a cut-awav top view of cannula 100.
Figure 4b is a cut-away side view of cannula 100.
Figure ~a is a cut-away view of a sliding tube embodiment of cannula 100 in a
first position.
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Figure ~b is a cut-away view of the sliding tube embodiment of Figure ~a in a
second position.
Figure 6a is a cut-away view of an embodiment of cannula 100 having an angling
device 140.
Figure 6b is a cut-away side view of the apparatus illustrated in Figure 6a in
which the retractor 112 is extended and the angling device 140 is actuated.
Figure 6c is a cut-awav side view of the angling device embodiment in which
the
angling device 140 is in a separate lumen from the retractor 112.
Figure 7a is a cut-awav side view of a twistable retractor 112 in a straight
position.
Figure 7b is a side view of the retractor 112 of Figure 7a.
Figure 7c is a cut-away side view of twistable retractor 112 in a crossed
position.
Figure 7d is a side view of the retractor 112 of Figure 7c.
Figure 8a is a cut-away side view of the handle 104.
Figure 8b is a cut-away side view of an alternate embodiment of handle 104.
Figure 9a is a side view of cradle 116.
Figure 96 illustrates a t3rst alternate embodiment of cradle 116.
Figure 9c illustrates multiple views of a second alternate embodiment of
cradle '
116.
Figure 9d illustrates multiple views of a third alternate embodiment of cradle
116.
Figure 9e illustrates multiple views of a fourth alternate embodiment of
cradle
1 I 6.
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Figure 9f illustrates multiple views of a fifth alternate embodiment of cradle
116.
Figure 9g illustrates multiple views of an embodiment of cradle 116 having a
spur.
Figure l0a illustrates a top view of an embodiment of the cradle 116 of Figure
9c
without a "C" ring.
Figure l Ob illustrates a side view of the cradle 116 of Figure 10a.
Figure l Oc illustrates a top view of the cradle 116 of Figure 9c with the "C"
ring
attached.
Figure l Od illustrates a side view of the cradle 116 of Fisure l Oc.
Detailed Description of the Preferred Embodiments
Figure 1 illustrates a perspective view of a preferred embodiment of cannula
100
showing retractor 112 in an extended position. Cannula 100 includes an outer
housing
l02 of bioinert material such as polymed UD that may be approximately 12" to
18" in
lensth. The proximal end of the cannula 100 is disposed in handle 104 that
includes a
button 106 which is coupled to retractor 112 for controlling the translational
movement of
retractor 112, as described in more detail below.
The distal end of the cannula houses a retractor 112, and optionally an
endoscope '
126 and a surgical tool 1?0. described below. Figure 2a illustrates the
retractor 112 in
more detail. In one embodiment. retractor l 12 is formed of resilient wire
which has a
smooth bend intermediate to a first portion 1 10 and a second portion 1 14 of
the retractor.
The retractor 1 12 is described as having two portions for ease of
description. although the
retractor 1 12 may be turmed as an integrated structure. However. retractor l
12 may also
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be manufactured from two separate portions 110. 114 that are coupled together.
The first
portion 110 of the retractor 112 is positioned within the cannula 100 with the
axis 111 of
the first portion 110 approximately parallel to the axis 101 of the cannula
100. The
second portion 114 is positioned to bend away from the central axis 101 of the
cannula.
The angle 117 of displacement between the axis 11 S of the second portion and
the central
axis 101 of cannula 100 may be any angle from zero to 180 degrees. The second
portion
114 includes a dissection cradle 116 at the distal end of the second portion
114. The
retractor 112 may be formed of bioinert material such as stainless steel, or a
polymer such
as nylon or polyetherimide. or other appropriately strong and springy plastic.
In one
embodiment, the retractor 112 includes a coating for lubrication, insulation,
and low
visual glare using, for example, parylene or nylon 11.
Figure 2b illustrates the retractor 112 formed with two legs. The legs 141,
142 of
the retractor 112 at the distal end form the dissection cradle 116 in a loop
or "U" shape,
as shown in Figure 2a. The top portion 144 of the U-shaped bend is preferably
flattened
to provide additional surface area for atraumatically supporting a vein 118 or
vessel of
interest. The side arches 128 of the dissection cradle 116 are used for
skeletonizing or
dissecting the vein from the surrounding tissues, as well as acting as walls
to keep the
vessel captured within the arch. T'he several embodiments of dissection cradle
116 are
described in more detail below.
Figure 3a illustrates a perspective view of the cannula 100 in accordance with
the
present invention with the retractor fully extended. holding a saphenous vein
l 18, and
also illustrates an external surgical tool l20 disposed adjacent the cannula
100 for
performing a surgical operation. for example. severing a tributary or side
branch of the
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vein 118. The vein is positioned within the side arches 128 of the cradle 116.
The
dissection cradle 116 may be used to cradle a vein, vessel. tissue or organ of
interest, and
surgical tool 120 may be any surgical tool suitable for performing a surgical
procedure
near the dissection cradle 116.
Figure 3b illustrates a perspective view of cannula 100 in an embodiment in
which the surgical tool 120 is positioned within the cannula 100, and an
endoscope 126 is
present. In this embodiment. cradle 116 preferably overlays the endoscope 126
with
sufficient clearance to facilitate relative movements thereof. However, the
endoscope
may also be located adjacent the surgical toot 120. In one embodiment,
endoscope 126 is
positioned with canrtula 100 to allow a clear field of view upon extension of
the retractor
l 12. Surgical tool 120 is illustrated as scissors, used to sever a tributary
or side branch of
a saphenous vein 118. In this embodiment, surgical tool 120 is maximally
displaced from
the cradle 116 at the cannula end 122. ;tore specifically, as shown in Figure
3c, the "U"-
shaped loop 129 of the cradle 116 is closest to the surgical tool 120. This
ensures that a
vein I 18 or other tissue of interest is retracted away from the surgical tool
120 to
facilitate manipulating the surgical tool 1?0 relative to the side branch or
other tissue.
Figure 4a is a cut-away top view of cannula 100. The retractor 112 is slidably
positioned within minor lumens 113 along the length of the cannula 100 within
close -
tolerances in order to position the retractor 112 stably within the cannula
100. For
example, in one embodiment retractor legs 141, 142 are approximately .045
inches in
diameter and the lumens 1 13 encasing the legs 141, 142 are approximately .080
inches in
diameter, as friction between the legs of the retractor I 12 and the lumens 1
13 holds the
retractor stably within the cannuia. This contiguration restricts rotational
movement of
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the retractor to provide more stable retraction as compared with conventional
retractors.
The legs 141. 142 of the retractor 112 are formed of flexible, resilient
material and are
retained within the lumen 113 in substantially straight or flat orientation,
but may return
to a material bend or curve. as illustrated in Figure ~a, as the retractor 112
is extended
from the distal end of the cannula 100.
The leg 141 of the retractor 112 passes through a sliding gas or fluid seal
130 at
the proximal end of the lumen 113. The leg 141 of the retractor 112 passes out
of the
cannula l00 and into handle 104 for attachment to a slider button 106 for
facilitating
translational movement of the retractor l 12 from the proximal or handle end
of the
cannula 100. However, other types of control devices such as knobs. grips,
finger pads,
and the like may be linked in conventional ways to the retractor 112 in order
to manually
control the translationai movement of retractor 112. In one configuration, the
proximal
end of leg 141 is bent relative to the axis of the cannula, and the button 106
is attached to
the bent position of the leg 141 to facilitate moving the button 106 and the
retractor 112
translationally under manual control. The button 106 preferably includes
lateral grooves
to prevent finger or thumb slippage during sliding manipulation of the
retractor 112.
Thus. in the operation of a preferred embodiment, a user actuates the slider
button
106 to extend retractor 112 out of the lumen 113 at the distal end of the
cannula 100. In
one embodiment. the resilient retractor 1 I2 is formed in a smooth bend. as
shown in
Figure 2a. and gradually deflects away from the central axis 101 of the
cannula 100 as the
retractor is extended. Upon encountering the target vessel or tissue of
interest, the vessel
is restrained in the cradle l 16. and a lateral resilient force is exerted on
the target vessel in
a direction awav tcom the cannula. The vessel is thus pushed away from the
axis of the
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cannula 100. isolating it from surrounding tissue or adjacent vessels such as
tributaries or
side branches. As a tributary is thus isolated, a surgical tool 120 such as
cauterizing
scissors may be safely employed to operate on the tributary without harming
the
saphenous vein 118. When retracted into the cannula 100, the retractor 112 is
again
resiliently straightened or flattened.
In an alternate embodiment as illustrated in Figures ~a and Sb, a sliding tube
132
is added to provide operational versatility to cannula 100. In a first
position. the sliding
tube 132 is retracted and the retractor 112 protrudes from the distal end at
an angle with
respect to the central axis 101 of the cannula 100. In a second position. the
sliding tube
132 is extended out. temporarily straightening the retractor 112. As
illustrated in Figure
Sa, a sliding tube 132, in a first position encases the retractor 112 up to
the point at which
the retractor 112 curves away from the central axis 101 of the cannula thus
allowing the
retractor 112 to displace and isolate a target vessel. The proximal end of the
sliding tube
132 is linked to button 107 for translationallv moving retractor I 12 as well
as actuating
the sliding tube 132. In one embodiment. as illustrated in Figure ~a. the
sliding tube 132
is in a first position with the hutton l07 in an upright position. A spring 13-
1 is coupled
between a support structure l 3~ and the proximal end 137 of the sliding tube
132. In the
first position of sliding tube I 32, the spring 134 is extended fully and
exerts little or no '
force on the slidin~~ tube 13'_'. Ufcourse. sliding tube 13'' may be manually
manipulated
without linkage to a button 107.
To extend the slidin<.: tube 100, button 107 is pushed down. As illustrated in
Figure ~b. the button 107 has a cam surface l36 which pushes on the proximal
end 137 of
the sliding tube 13'? as thu hutton 107 is pressed. The: sliding tube 132 is
pushed forward.
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overcoming the resilient torce of spring 134, to encase the retractor I 12 and
decrease
angle I 17 between the distal end of the retractor 112 and the central axis
101 of the
cannula 100. Upon releasing the button 107, the spring force urges the
proximal end l37
of the sliding tube I 32 back toward the tirst position against button 107.
The sliding tube
132 is formed of material having sufficient strength to force the retractor
112 to straighten
out the angle 117, and the retractor 112 is formed of resilient material
having a sufficient
flexibility to straighten out the angle 117 in response to a tube 132 being
slid over the
retractor I 12. but having sufficient rigidity to cradle and dissect a target
vessel.
Resiliency of the retractor 1 I? ensures return to the downwardly-curved shape
after being
released from tube 132. Thus. in accordance with this embodiment. a user may
employ
the curved retractor for certain applications and employ the straightened form
for other
applications. A manual actuator may be configured in other ways than button
107 to
extend the sliding tube 132 in response. for example, to being pulled up
instead of pushed
down.
Another embodiment employs a retractor 112 which has a naturally straight
shape.
As illustrated in Figures 6a and 66, an angling device 1.~0 is disposed
between the distal
end of the retractor I 12 and the proximal end of the cannula. The angling
device 140
may be positioned within the same lumens 113 as the retractor 112 and
preferably may '
comprise two wires coupled to points below the cradle 1 16 of the retractor 1
12
substantially in parallel positions on each of the legs 1-11. 142.
Upon extending the retractor 1 12 using button 106. the angling device 140 is
extended with the retractor I 1 "_'. The angling device 1-10 is coupled to a
handle 14S at the
proximal end ot~the cannula 100 to facilitate establishing an angle in the
retractor 112 by
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CA 02274270 1999-06-08
pulling with a backward force on the angling device 140. As illustrated in
Figure 6b,
after the retractor 112 is extended. the angling device 140 is actuated and a
bend is
created in the retractor 112 as the backward force exerted on the distal end
of the retractor
is exerted against the relatively fixed position of the retractor legs 141,
142 disposed
within the lumens 113. As shown in Figure 6c, the angling device 140 may also
be
located in a separate lumen 202 from the retractor 112 with part of the
angling device 140
positioned outside of the cannula l00 when the retractor 112 is in the
retracted position.
Figure 7a illustrates another embodiment of cannula 100 in which the retractor
112 is pre-formed with one leg 141 of the retractor I 12 bent at an angle at
its proximal
end skewed to the axis of the distal end of the other leg 142. The bent
portion of the leg
141 may be linked to a sliding knob 147 for convenient manual manipulation of
this
embodiment of the invention. Upon sliding the knob 147, the leg 142 coupled to
knob
147 is twisted rotationally. The two legs 141, 142 of retractor 112 are
coupled together
via cradle 116. The axis of the second portion of the retractor 112 in the
first position is
at a first angle 1 17 to the axis of the cannula 100, as shown in Figure 7b.
As knob 147 is
moved. leg 141 is rotated and crosses under leg 142. as shown in Figure 7c.
This causes
cradle 116 to flip 180 degrees and bends the retractor 112 at a second angle
119, as
shown in Figure 7d. Thus, if a vessel is disposed on one side of cradle 116 or
cannula
100 while the retractor I 12 is in the first position. then upon rotating the
knob 147, the
vessel is transported to the other side of the cannula 100. This allows the
user to isolate
the vessel by simpy actuating knob 147.
Figure 8a illustrates a cut-away side view of button 106 on the handle 104 of
cannula 100. with an endoscope 126 positioned within cannula 100. :\s
mentioned
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above. button 106 is coupled to one leg 141 of the proximal end of retractor
112. Sliding
the button 106 in groove 146 translationally moves the retractor 112. Groove
146 is
preferably minimally wider than the shaft of button 106 to minimize excessive
horizontal
movement of button 106 while still allowing smooth translational movement of
button
106. As illustrated in Figure 8b. the button 106 may include locking or
ratcheting teeth
152 to give tactile feedback of its location. and to positively retain the
button and the
associated leg 141 in an extended or retracted position. Several mating teeth
148 are
located underneath groove 146. and a spring member 150 is attached to button
106 to
oxen pressure against the base of groove I-16, to engage mating teeth 148,
152. When a
force is applied on the top of button 106, the interlocking sets of teeth are
disengaged and
button 106 can move freely. Upon achieving the desired extension or retraction
of the leg
141, button 106 is released and is retained place by the engaged teeth 148,
152.
Figure 9a illustrates a top view of cradle 1 16 in an embodiment in which the
cradle I 16 is formed by two legs 1-I1, 142 of retractor 112. The distal end
of the legs
form "U"-shaped side guides. The top 144 of the distal portion of the "U" is
preferably
tlattened. This provides atraumatic support for the target vessel retained
within cradle
I 16. Additionally, by minimizing the thickness of distal portion 144, contact
with other
devices in close proximity with retractor 112 is minimized.
The cradle 1 16 may have other effective shapes. for example. as illustrated
in
Figure 9b in which a "C" rinc element is attached to lees of the cradle 116.
The ''C" ring
may have a small hole ?00 in one side with an axis approximately parallel to
the axis of
the retractor l 1 ~. This hole ?00 is used to hold suture or other ligating
materials. and
may also be used as a knot pusher. .~s shown in Fi~.~ures I Oa and I Ob. in an
alternate
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_ CA 02274270 1999-06-08
embodiment of the embodiment of Figure 9b. the retractor I 12 is formed and
flattened
and a "C"-shaped ring is coupled to the retractor 112 by, for example. gluing
or molding
the "C" ring to the distal end of the retractor 112, as shown in Figure l Oc
and lOd.
Referring back to Figures 9c, 9d. and 9e, the side guides of the cradle may
include
a loop 129 in a "V" shape, an arced "U" shape, or a semi-circular shape. In
one
embodiment. as illustrated in Figure 9f, the retractor I 12 has only one leg
141, and the
cradle 116 is formed by the leg 141. A stopper 160 is coupled to the end of
the leg 141 to
serve as a guide to retain the target vessel. and add a blunt surface to the
end of the wire,
for example. for pushing and probing tissue. Figure 9g illustrates a retractor
112 having
a spur 204 formed in one or both legs 141. 142 for allowing the retractor 112
to be used
for dissection. Sinusoidal. half sinusoidal, and other geometric
configurations may be
used equally effectively as the shape of loop 129 in accordance with the
present
invention.
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