 |
Description  |
|
|
FIELD OF THE INVENTION
This invention relates to an electrosurgical apparatus. More particularly,
the invention relates to an electrosurgical knife for transurethral
incision of the prostate (TUIP), and to a method for performing TUIP using
RF electric energy.
BACKGROUND OF THE INVENTION
Various instruments for performing surgical cutting operations in body
lumens, for example, blood vessels, are known in the art.
For example, U.S. Pat. No. 4,909,781 discloses a flexible catheter for
opening obstructions in a blood vessel including an annular, rotatable
cutter having a flexible coil spring body positioned at one end of a thin,
flexible, cylindrical tube adapted for insertion in the vessel.
U.S. Pat. No. 5,030,201 discloses an expandable atherectomy catheter device
having an expandable cutting head consisting of deformable cutting members
to remove an atheroma or blood clot from a blood vessel.
U.S. Pat. No. 5,071,424 discloses a catheter atherotome comprising a
plurality of elongate cutting blades disposed within a catheter for
removing plaque from the interior wall of an artery.
U.S. Pat. No. 5,074,871 discloses another form of catheter atherotome
having an expansable cutter head at the distal end of a catheter.
All of the above instruments utilize mechanical cutters to remove
obstructions in blood vessels.
It is also known to remove obstructions by electrosurgery, i.e., by the use
of an electrode, which may or may not be in the form of a sharp blade,
which conducts RF electrical energy.
Thus, U.S. Pat. No. 5,057,107 discloses a RF ablation catheter for removing
athero-stenotic lesions in blood vessels including a pair of electrodes
which create an electric arc for effecting cutting upon application of RF
voltage.
U.S. Pat. No. 5,080,660 discloses an electrosurgical electrode having a
conductor from which a RF electrical signal is generated, which conductor
is surrounded by a sheath having a longitudinal slit to expose the
conductor over the region where a surgical procedure is desired.
U.S. Pat. No. 5,163,938 discloses a high-frequency electrosurgical treating
device comprising a wire for high-frequency incision in combination with
an endoscope. The device is typically used for papillo-sphincterotomy.
The present invention is predicated upon the concept of using an
electrosurgical device to perform an incision procedure on the prostate.
Transurethral incision of the prostate (TUIP) is a less traumatic procedure
than transurethral resection of the prostate (TURP), the most common
operation for benign prostate hyperplasia (BPH). For selected patients
TUIP has been found by some urologists to be as effective as TURP, with
the advantage that it permits a shorter hospital stay and is associated
with fewer complications and undesirable effects.
TUIP is typically performed with a cold (unpowered) knife. It has now been
found that the use of an electroctrosurgical (ES) knife, particularly a
monopolar electrosurgical knife, powered by radio-frequency (RF)
electrical energy from an electrosurgical unit (ESU) makes a cutting
operation easier, more direct, and thus less traumatic, than cutting with
an unpowered knife. Moreover, use of a RF powered knife permits the
convenient application of coagulating power for hemostasis.
However, conventional ES knives are not well adapted for TUIP. The urethra
is an elongated, narrow tube about one centimeter in diameter, and the
prostate extends radially outward from the urethra and needs to be incised
to a depth of up to four centimeters. Accordingly, the instrument should
have a configuration with a low profile for atraumatic passage through the
urethra, but be adapted to be redeployed into a configuration appropriate
for the TUIP procedure. An instrument which satisfies these requirements
and also has other advantages is provided by the present invention.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided an apparatus for
electrosurgical incision of a stricture within or adjacent to a body lumen
which apparatus is elongated, has a longitudinal axis and comprises an
electrically conducting deflectable wire associated with introducer means
for introducing the apparatus into the body lumen, means for deflecting a
proximal portion of the wire outwardly relative to said introducer means,
a source of RF electric current connected to the wire and means for
transmitting RF electric current through the wire when it is in the
deflected position.
As used herein the term "proximal" means the location at or near the site
of the surgical procedure and the term "distal" means the location at or
near the operator.
In a preferred embodiment of the invention the introducer means is sized to
be inserted in a urethra and the deflectable wire, when deflected, is
sized to perform transurethral incision of the prostate or urethral
strictures. Alternatively, the apparatus may be sized to be inserted in a
ureter to perform incision of a ureteral stricture.
The proximal portion of the apparatus has a low profile, which means that
it has a configuration which is elongated and narrow enough to pass
through a chosen body lumen without undue trauma or dilation. The
apparatus may be substantially rigid or flexible and preferably the
proximal end thereof is smooth and rounded to facilitate passage through
the body lumen, for example, the urethra or ureter.
Preferably, the introducer means comprises a nosepiece defining a conduit
embracing at least part of a proximal portion of the deflectable wire, the
wire being slidable within the conduit. The nosepiece preferably is made
from an electrically insulating material, for example a moulded
biologically compatible plastic, such as a polyurethane.
Preferably the portion of wire deflected outwardly is in the form of a loop
defining a monopolar electrosurgical knife, which loop terminates in two
distal ends extending beyond the distal end of the introducer means and
the means for deflecting the wire is by pulling one distal end and pushing
the other distal end. In one embodiment the distal ends of the wire are
attached to a reel and the pulling and pushing is effected by rotating the
wheel. Also, the wire may be springwound to achieve axial stability
(pushability).
In a particularly preferred embodiment the wire is flat so that when it is
deflected outwardly it bows in a predictable direction. This provides
better directional stability.
The wire is preferably made from a superelastic alloy, especially an alloy
of nickel and titanium. Preferably, the deflected position is attained by
deflecting the wire loop outwardly in a direction transverse to the
longitudinal axis of the apparatus, and the apparatus may include means
for controlling the degree of deflection of the wire loop.
Also the loop may include a pointed member, for example a needle, the
combination of loop and needle defining a monopolar electrosurgical knife.
In a particularly preferred embodiment of the invention the catheter is
accommodated within a cystourethroscope or a small flexible urethroscope
so that the apparatus may be used under endoscopic vision. The
urethroscope may be a conventional resectoscope.
When the apparatus is sized to perform incision of ureteral strictures it
may be accommodated within a ureteroscope.
The invention also provides a method for performing transurethral incision
of the prostate of a patient or incision of a ureteral stricture in a
patient which comprises inserting an apparatus as described above in the
urethra or ureter of the patient until the deflectable wire is located in
a position to perform the desired incision, deflecting the wire outwardly
to assume a cutting configuration, applying RF electric current through
the wire while moving the apparatus to perform the desired incision,
switching off the current when the incision procedure is completed,
retracting the wire within the apparatus and withdrawing the apparatus
from the urethra or ureter.
DETAILED DESCRIPTION OF THE INVENTION
The apparatus according to the invention has an initial low profile
configuration which enables it to be inserted into and passed along a body
lumen, for example a urethra or ureter, with the minimum discomfort and
trauma. This makes it particularly suitable for the performance of TUIP or
for the incision of strictures in the urethra or ureter. The invention
will be more particularly described with reference to the preferred use as
an electrosurgical knife for the performance of TUIP.
A problem associated with prior instruments for TUIP arises from the fact
that they are usually inserted through a channel of a rigid
cystourethroscope. The size and rigidity of such an instrument makes the
procedure painful. The apparatus of the present invention is sized to be
used advantageously with a small flexible urethroscope, thereby reducing
anesthesia requirements to topical or regional anesthetic agents and
consequently reducing the need for support facilities, lengthy hospital
confinement and cost. Of course, this does not mean that the greater
stability provided by a rigid cystourethroscope need be totally discarded,
and in one of the embodiments described herein a rigid resectoscope is
used.
The apparatus of the present invention is adapted to perform TUIP with
monopolar electrosurgical power. The wire which conveys RF electric
current and defines the active electrode or electrosurgical knife is
associated with introducer means so that the combination of active
electrode and introducer provides a flexible or rigid elongated instrument
sized to be inserted into a patient's urethra with minimum trauma or
discomfort. During insertion the wire is contained within an appropriate
low profile envelope, for example, a nosepiece as hereinafter described.
When the apparatus is inserted into a patient's urethra and the operator
is ready to perform the incision procedure a control mechanism is
activated to deflect the wire, i.e., to cause the cutting electrode to
assume its operating configuration. The activation may be accomplished in
any one of several ways, for example:(i)
(i) a control wire that is pulled to cause the deflectable wire (electrode)
to bow outward;
(ii) two control wires that, when one is pushed and the other pulled, cause
the electrode to deflect outwardly from the side of the nosepiece;
(iii) either of the above associated with a reel that, when rotated, pushes
and/or pulls the control wire or wires;
(iv) an elastic or superelastic electrode that is contained within a
tubular envelope for deployment and bends upward at the proximal end when
it is advanced out of the tube; and
(v) the electrode carried on an elastic or superelastic non-conducting
substrate contained within a tubular sheath for deployment which bends
upward at the proximal end when advanced out of the tube and the electrode
assumes the same shape as the bent substrate.
When the apparatus of the invention is used as a monopolar electrosurgical
knife, the deflectable wire acts as the active electrode when activated by
RF electrical current and the circuit is completed by a return electrode
attached to the patient's body in a manner known in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are illustrated in the accompanying
drawings, in which:
FIG. 1 is a side elevation of a simple embodiment of the invention;
FIG. 2 is a side elevation of the embodiment of FIG. 1 showing the wire in
the cutting configuration;
FIG. 2A is an enlarged perspective view (not to scale) of a small portion
of the wire at profile A--A of FIG. 2;
FIG. 3 is a schematic side elevation of another embodiment of the
invention;
FIG. 4 is a side elevation of the embodiment of FIG. 3 showing the wire in
the cutting configuration;
FIG. 5 is an enlarged perspective view of a reel mechanism for deflecting
the electrode wire of the embodiment of FIG. 3;
FIG. 6 is a side elevation of a preferred embodiment of the invention
showing the wire in the insertion-withdrawal configuration;
FIG. 6A is a cross section through line A--A of FIG. 6;
FIG. 6B is a cross section through line B--B of FIG. 6;
FIG. 7 is an enlarged side elevation of the proximal end portion of the
embodiment of FIG. 6 showing the wire in the operational (cutting)
configuration;
FIG. 8 is a side elevation of an apparatus according to the invention
mounted in a common type of resectoscope;
FIG. 9 is an enlarged view of a portion of the embodiment of FIG. 8 showing
the configuration where the wire is longitudinally movable;
FIG. 10 shows the configuration where the wire is secured;
FIG. 11 is a side elevation of an apparatus in the operational mode; and
FIG. 12 illustrates four positions:- A, B, C and D, of the apparatus of
FIG. 11 during the operational procedure.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 and FIG. 2 illustrate the proximal portion of an apparatus
comprising a deflectable electrically conducting wire 1 which defines a
loop 2 at the proximal end of the apparatus and two limbs 3,4 extending
toward the distal end of the apparatus. For most of its length the wire
has an electrically insulating coating or sheath 5, and only the portion
to be deflected and form the cutting electrode is exposed. The proximal
portion of the wire is enveloped in a sheath 6, preferably made of a
smooth, biocompatible plastic, preferably a polyurethane or polyethylene,
having a rounded smooth proximal end 7, which sheath acts as an introducer
when the wire is undeflected and contained therein (FIG. 1 ). The
introducer is elongated and has a longitudinal axis and a slot adjacent
the proximal end through which the wire may be deflected outwardly in a
direction transverse to the longitudinal axis to provide the cutting
configuration (FIG. 2).
As illustrated in FIG. 1, the introducer has a low profile which enables
the apparatus to be inserted in a body lumen, for example a urethra or
ureter, with minimum trauma. When the apparatus is properly positioned
within the urethra, the distal end 4 of the wire is pulled to deflect the
exposed proximal portion of the wire outwardly in a direction transverse
to the longitudinal axis of the apparatus as shown in FIG. 2. In this
embodiment the limb 3 remains fixed. In the preferred embodiment where the
wire is flat, as shown in FIG. 2A, the wire bows outwardly without kinking
or distortion.
FIG. 3 and FIG. 4 illustrate another embodiment, similar in many respects
to the embodiment of FIG. 1 but wherein the distal ends 3' and 4' are both
movable to deflect the electrode wire 1 and the desired deflection of the
wire is achieved by pushing the distal end 3' and pulling the distal end
4'. In a preferred embodiment, illustrated in FIG. 5, the distal ends of
the wire 3', 4' are attached to a reel 8. One of the ends 3' is wound
around the core of the reel in a counterclockwise direction and the other
end 4' is wound around the core in a clockwise direction. Thus, when the
reel is rotated in a clockwise direction, as indicated by the arrow, the
wire 4' is pulled and the wire 3' is pushed, whereby the proximal end of
the wire is deflected outwardly. When the reel is rotated counterclockwise
the wires are moved in the opposite direction and the wire is returned to
the withdrawal configuration.
In the apparatus illustrated in FIGS. 1, 2, 3, 4 and 5 the deflected wire
is the active electrode in a monopolar electrosurgical cutting knife. The
knife is activated by RF electrical current from a standard
electrosurgical unit (ESU) connected to the distal end of the wire in a
conventional way (connection not shown). The circuit is completed through
a return electrode attached to the body of the patient in a conventional
manner (not shown).
FIG. 6 and FIG. 7 illustrate a preferred embodiment, particularly suitable
for TUIP. FIG. 6 shows the instrument in the insertion-withdrawal
configuration and FIG. 7 shows the wire deflected in the cutting
configuration. The instrument is adapted to be held in the working element
of a resectoscope as described hereinafter with reference to FIG. 8.
The TUIP instrument illustrated in FIG. 6 comprises a conductor-carrying
tube 9 (identified herein for convenience only as the "hot tube"), which
tube contains a flat profile deflectable wire 15 capable of carrying RF
electrical current. RF current from an electrosurgical unit (ESU), not
shown, enters the hot tube through a contact 1 0, which is insulated from
the exterior of the tube. A notch 11 adjacent the distal end of the tube
enables the tube to be held in the working element of a resectoscope and
the tube is aligned to the axis of the resectoscope by guides 12 and 13.
The proximal end of the hot tube is associated with introducer means which
includes a nosepiece 14 defining a conduit 16 through which the hot tube
passes. The nosepiece is made from an electrically insulating polymer,
preferably a moulded polyurethane. The diameter of the conduit determines
the friction between the hot tube and the nosepiece and thus controls the
ease with which the hot tube may slide axially. The sliding motion is what
raises and lowers the cutting electrode. A small key 17 prevents rotation
of the hot tube within the nosepiece.
The hot tube extends proximally beyond the nosepiece about 0.7 Inch. The
insulated cutting electrode wire 18 emerges from the end of the hot tube
and makes a hairpin bend before passing through a backing tube 19. A
pointed member, preferably a needle 20, extends about 0.1 Inch from the
proximal end of the backing tube. The outside of the backing tube is
insulated, but the needle is uninsulated and forms part of the cutting
electrode. The uninsulated electrode wire 15 with the needle emerges from
the proximal end of the backing tube and continues, in a deflected
configuration (FIG. 7), to an anchoring point 21 on the nosepiece. The
wire is anchored by being passed around a screw 22 within the nosepiece,
as shown in FIG. 6A. When the desired length of wire has been taken up the
screw is heated to its softening point. As the screw cools it bonds to the
nosepiece and attachment of the wire is secured. FIG. 6A also shows hot
tube 9, electrode wire 15 with its insulation 23, and key 17. Preferably
the electrode wire is high temper 304 stainless steel ribbon wire,
insulated by polytetrafluoroethylene shrink tubing. Preferably, the hot
tube, cold rod 24, telescope guides 12, 13, backing tube 19, and needle 20
are made from 304 stainless steel.
The cold rod or push rod 24 is the means for holding the nosepiece immobile
when changing the configuration of the cutting assembly and it may be a
hollow tube or a solid rod. The proximal end of the cold rod is inserted
into a hole in the nosepiece and is rigidly attached by a transverse pin
25. Thus, motion of the hot tube 9 relative to the cold rod 24 changes the
configuration of the cutting assembly. If the cold rod and hot tube are
moved together, the entire instrument moves axially without changing its
configuration. The guides 12 and 13 are rigidly attached to the cold rod
by attachments 26, but slidably attached to the hot tube by attachments 27
(FIG. 6B).
A notch 39 adjacent the distal end of the cold rod is adapted to accept a
clip 41 (FIG. 10) to prevent movement of the cold rod in a proximal
direction. A collar 40 welded to the cold rod acts as a stop in the distal
direction (FIG. 9).
When the hot tube is pulled in a distal direction while the nosepiece is
held immobile the distance the hot tube extends out of the nosepiece is
decreased, leaving a shorter distance between the wire's emergence from
the tube and its anchoring point. The cutting assembly comprising
uninsulated portion 15 of the electrode wire and the part of the needle 20
that extends from the backing tube 19, therefore assumes the cutting
configuration as shown in FIG. 7. When the hot tube is pushed in a
proximal direction the electrode wire is stretched out and resumes the
insertion-withdrawal configuration shown in FIG. 6. A flange 28 near the
proximal end of the nosepiece is provided to keep the portion of the
instrument near the needle 20 away from the wall of a delivery sheath
described hereinafter with reference to FIG. 11.
The mounting of a TUIP instrument according to the invention in a common
type of resectoscope is illustrated in FIG. 8. The operation of the
working element of the resectoscope involves motion of a distal piece 29,
which slides along a tube 30 in response to a manual force exerted at
thumb loop 31. A proximal piece 32 of the working element is held
stationary by manual force exerted on a finger loop 33. The hot tube 9 of
the TUIP instrument is securely held within the distal piece 29 by a knife
edge 34 which engages the notch 11 and is supplied, through contact 10,
with RF electrical current from the ESU via cable 35. A telescope 36, used
for viewing the interior of the urethra and bladder through eyepiece 37 is
immobile with respect to proximal piece 32. The motion of the working
element is assisted by a spring loaded pivot 38.
FIG. 9 and FIG. 10 illustrate the operation of the system. The hot tube 9
and cold rod 24 slide freely through conduits in proximal piece 32. The
hot tube 9 is attached to the distal piece 29 by the knife edge 34 which
engages the notch 11, and receives RF current through contact 10. Motion
of the distal piece will cause corresponding motion of the hot tube. In
the situation shown in FIG. 9, this motion will cause axial motion of the
entire TUIP instrument, because friction between the hot tube and the
nosepiece is sufficient to prevent change in the configuration of the
instrument. However, in the situation shown in FIG. 10, a clip 41 is
placed in notch 39. Since the clip is too large to pass through the
conduit in proximal piece 32, the cold rod can not move in a proximal
direction. Since the collar 40, welded to the cold rod, prevents the cold
rod from moving in a distal direction, the cold rod is immobile with
respect to proximal piece 32. In this situation the nosepiece is similarly
immobile with respect to proximal piece 32. Accordingly, motion of distal
piece 29 in a proximal direction has the effect of moving the cutting
assembly to the insertion-withdrawal configuration, while motion of the
distal piece in a distal direction moves the cutting assembly to the
cutting configuration. Thus, with clip 41 in place, movement of the distal
piece changes the configuration of the TUIP instrument, while without the
clip, movement of the distal piece moves the entire instrument axially
without changing the configuration.
A preferred assembly containing the TUIP instrument for a surgical
procedure is illustrated in FIG. 11. The operating surgeon inserts a metal
sheath 42 in a patient's urethra. A spacer 43 may be attached to the
distal piece of the working element to limit its travel, which has the
effect, as described hereinafter, of allowing the surgeon to raise the
cutting assembly to any desired height less than or equal to the maximum.
The sheath 42 is a hollow tube with a lumen having a diameter large enough
to accommodate the viewing telescope and the TUIP instrument. Initially, a
viewing telescope is passed through the sheath to permit inspection of the
urethra, prostate and bladder. When the surgeon is ready, the proximal
piece 32 of the resectoscope's working element is attached to the sheath.
As shown in FIG. 9, both the cold rod 24 and the hot tube 9 are passed
through conduits in the proximal piece 32. Clip 41 is placed within the
notch 39 of the cold rod. The instrument is typically in the relaxed
position shown in FIG. 12A. This position minimizes strain on the
instrument during storage, but is not adapted either for
insertion-withdrawal or for surgery. In the next step the distal piece 29
is moved forward so that the knife edge 34 engages the notch 11 of the hot
tube 9. In this position, the hot tube can receive RF current through
contact 10. As shown in FIG. 12B, distal piece 29 is then moved as far as
possible in the proximal direction, thus moving the cutting assembly to
the insertion-withdrawal configuration. This is the configuration in which
the tuip instrument has the lowest profile and therefore passes most
easily through sheath 42. The instrument may be passed through the sheath
42 to the prostatic urethra.
To perform incision of the prostrate, the surgeon moves the cutting
assembly to the cutting configuration by drawing back the distal piece 29
by means of manual force at thumb loop 31. The cutting configuration is
shown in FIG. 12C. The surgeon then advances the elevated cutting assembly
to its most proximal position by pushing forward on thumb loop 31. A
commercially available ESU supplies RF current to the hot tube 9 through
cable 35 and contact 10. In a typical operation, the esu would provide
about 140 watts power at a potential of about 200 volts and a frequency of
about 750 kilohertz to drive a current of about 0.7 Ampere. To perform the
incision, the surgeon moves the electrode wire through tissue in a distal
direction by drawing back on thumb loop 31 while applying RF current from
the ESU. The needle 20, acts as a hook to facilitate attachment and
movement of the cutting edge through the tissue. Since the clip 41 has
been removed, the entire instrument moves as a unit as described above.
Typically the application of power is controlled by a footswitch operated
by the surgeon, and power is applied only when the instrument is being
moved in a distal direction.
In a preferred embodiment means is provided for controlling the degree of
deflection of the wire loop. Thus, use of the spacer 43, as shown in FIG.
11, decreases the distance by which the distal piece 29 may be drawn back,
with the result, shown in FIG. 12D, that the cutting assembly is elevated
to a height less than that achieved without the spacer. This is useful if
an incision of smaller depth is desired. The instrument will normally be
supplied with several marked spacers of different thicknesses for
achieving various heights as desired by the surgeon.
When the desired incision is made, the thumb loop is again drawn back as
far as possible, and the clip 41 is placed in the notch 39. The thumb loop
is then moved in the proximal direction as far as it will go, causing the
cutting assembly to assume the insertion-withdrawal configuration. The
instrument is then withdrawn from the sheath. The flange 28 pushes the
part of the instrument nearest the needle 20 away from the wall of the
sheath, thus avoiding the danger that the needle will snag the sheath and
prevent smooth withdrawal of the instrument.
The use of an apparatus according to the invention in a procedure as
described herein provides a safe and efficacious way of performing a TUIP
operation or incision of a ureteral stricture.
* * * * *
|
|
 |
|
 |
Description |
|
