A cutting head for attachment to the end of the wire probe of an ultrasonic kidney stone disintegration instrument is described. The cutting head has a plurality of circumferentially arranged teeth formed at one end thereof to provide a cup shaped receptacle for kidney stones encountered during the disintegration procedure. An integral reduced diameter collar diminishes stress points in the wire and reduce breakage thereof

Anguluo, E. D.

Goodfriend, R.

English

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NOTICE
The invention disclosed in this document resulted from
research in aeronautical and space activities performed under
programs of the National Aeronautics and Space Administration.
The invention is owned by NASA and is, therefore, available
for licensing in accordance with the NASA Patent Licensing
Regulation (14 Code of Federal Regulations 1245.2).
To encourage commercial utilization of NASA-owned inven-
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when such a license will provide the necessary incentive to
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invention.
Address inquiries and all applications for license for
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NASA forms for applications for nonexclusive or exclusive
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.NASA-Case-GSC-129UU- 1) C01TING HEAD FOR N86-19885
LTBASONIC LITBCTEIPSY Patent Application
NASA) 10 p HC A02/HF AO1 CSC1 06E
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NASA Case No. GSC 12,944-1
CUTTING HEAD FOR ULTRASONIC LTTHOTRIPSY
This invention relates to surgical apparatus for disintegrating
urinary calculi, and, more particularly, to a cutting head and to an
ultrasonic device for fragmenting or drilling through urinary calculi in
situ.
Figure 3 shows a cutting head 44 having two integrally formed
coaxial cylindrical sections, a cutting tip section 48 and an elongate
collar section 46, and a central circular opening therethrough. The
cutting tip 48 a plurality of cutting teeth 50, 52, 54, 56 circumferen-
tially arranged at the end thereof. The collar 46 has a reduced ex-
ternal diameter. The cutting head is slipped over the wire probe 24 and
swaged thereto. In operation, the wire probe is inserted through a
catheter 16 into the ureter 12 and brought into contact with the stone
22 to be disintegrated and vibrated by energization of an ultrasonic
transducer 32 coupled thereto.
Novelty is believed to reside in circumferentially arranged cutting
members arranged at the end of the cutting tip to assure seating of the
kidney stone therebetween, and the swaging of the cutting head to the
ultrasonic probe so as to prevent breakage thereof.
Inventors: Earl D. Angulo
Roger Goodfriend
Employer: Angulo - GSFC
Goodfriend - Self-employed
Evaluator: Donald S. Friedman
PttlOR ART-
CUTTING HEAD FOR ULTRASONIC LITHOTRIPSY
Origin of the Invention
The invention described herein was made by an employee of the U. S.
Government and another and may be manufactured and used by or for
governmental purposes without the payment thereon or therefor.
Technical Field
This invention relates to surgical apparatus for disintegrating
urinary calculi, and, more particularly, to a cutting head and to an
ultrasonic device for fragmenting or drilling through urinary calculi in
5 situ.
Background Art
The incidence of hospitalization for the removal of urinary
calculi, commonly referred to as kidney stones, has been estimated to be
as high as 200,000 cases per year. Stones which are quite small may in
10 some cases be passed without hospitalization. However, in the
. remainder, the kidney stones become impacted in the ureter, a muscle
tube joining the kidney to the bladder. An impacted kidney stone is a
source of intense pain and bleeding, a source of infection, and, if the
stone completely blocks the flow of urine for any extended length of
15 time, can cause the loss of a kidney. Small stones which are lodged in
the lower third of the ureter can be removed non-surgically by using a
technique employing the well known Dormia stone basket. However, basket
removal of a kidney stone usually fails if the stone is lodged in the
upper ureter, is impacted, or is larger than one centimeter in diameter.
20 In these cases, the only procedure by which the stone could heretofore
be removed was through a serious surgical operation called a
ureterolithotomy.
More recently, however, a non-surgical method for removing kidney
stones has been developed. In this technique, the kidney stones are
25 subject to a vibratory action, such as that provided by an
ultrasonically vibrated wire probe. In one such apparatus, a catheter
is placed cystoscopically at the site of the stone in the urinary tract,
after which a long wire probe is passed through a lumen of the catheter
and is brought into contact with the stone. The wire probe is attached
to the ultrasonic transducer which, when energized, sets the wire probe
into lateral and longitudinal vibrations. The vibrational energy is
5 transmitted by the wire probe to the stone, causing it to fracture into
small fragments which the patient can then pass spontaneously after
withdrawal of the catheter.
While such apparatus can perform its intended function, a severe
limitation has been found to exist due to slippage of the thin wire
10 probe off the kidney stone and its lodgement between the stone and
urinary tract. Attempts to ameliorate this situation by providing a
wider tip cutting surface has resulted in premature breakage of the wire
probe at the tip exiting the catheter near the kidney stone. This
occurs because the vibrational energy, typically 20 KHz in frequency, in
15 conjunction with the added cantilevered mass of the larger cutting area,
causes the wire probe to snap off due to metal fatigue after 10-20
seconds of operation. This has been found to be insufficient time
to complete the disintegration procedure, as well as dangerous because
it leaves metal fragments in the urinary tract. A clear need,
20 therefore, exists to prolong the operational life of the wire probe for
- a length of tine adequate for completion of the procedure. A desirable
time frame is typically one minute, which is substantially greater than
that provided by known prior art apparatus.
Statement of the Invention
25 Accordingly, it is an object of the invention to provide a cutting
head for surgical use.
Another object of the present invention is to provide a cutting
head member for an ultrasonically vibrated wire probe.
A further object of the instant invention is to provide a safer and
30 more efficient cutting head for ultrasonically disintegrating kidney
stones.
Still another object of the invention is to provide an improved
system for prolonging the operational life of an instrument for
disintegrating kidney stones.
Another further object of the present invention is to provide a
device for seating of kidney stones within a cutting head in an
ultrasonic lithotripsy procedure.
Yet another object of the present invention is to greatly enhance
5 the fragmentation of kidney stones when using ultrasonic lithotripsy.
These and other objects of the present invention are provided by a
cutting head which is attachable to the end of the ultrasonically
vibrated wire probe. The cutting head includes a large diameter cutting
section provided with a plurality of teeth formed on the periphency of
10 one end thereof to present a cup-shaped receptacle to seat a kidney
stone therein. The member also includes a collar integrally formed with
the cutting tip section to reduce stress points along the probe.
Brief Description of the Drawings
The foregoing, as well as other objects, features, and advantages
15 of the invention will become apparent from the following detailed
description when taken in conjunction with the appended drawings in
which like numbers represent the same or similar components throughout
the several drawings, and wherein:
Figure 1 is a side elevational view of state-of-the-art apparatus
20 - for fragmenting kidney stones;
Figure 2 is a side elevational view of the cutting head of this
invention; and
Figure 3 is a longitudinal view, partly in section, of the
cutting head in contact with a kidney stone.
25 Description of the Preferred Embodiment
Referring to the drawings, and, more particularly, to Figure 1,
there is illustrated an ultrasonic kidney stone disintegration
instrument in accordance with the prior art. The purpose of this Figure
is to provide a better understanding of the invention to be described in
30 detail in conjunction with Figures 2 and 3.
Figure 1 shows a cystoscope 10 inserted through a patient's urethra
12 into a bladder 14. A catheter 16 is inserted through the cystoscope
10, the baddder 14, and into a ureter 18 until its far end 20 comes into
proximity to a piece of urinary calculi, hereinafter referred to as a
kidney stone, 22. A wire probe 24 is inserted through the catheter 16
until its far end 26 contacts the stone 22. The diameter of the wire
probe 24 is substantially smaller than the lumen diameter of the
catheter 16 so that any movement of the wire probe is not restricted by
5 the catheter material.- The opposite, or near end, 28 of the wire probe
24 is connected to the tip 30 of a movable ultrasonic transducer
assembly 32 which is mounted on a base 34. The base 34 includes a
handle 36 having a trigger 37 which is connected to the transducer 32
for adjusting the position of the wire probe 24 against the stone 22 by
10 a linear translation of the transducer assembly 32 on the base 34. Base
34 additionally includes an outward angular support member 38 which
includes a connector element in the form of a catheter joint 40 for
engaging and holding the near end of the catheter 16. The terminal
portion of the wire probe is clamped to tip 30 of the transducer 32 by
15 a set screw 42.
With the catheter 16 and wire probe 24 inserted into the ureter 18,
end 26 of the probe is optically guided to make contact against kidney
stone 22. Thereafter, the transducer assembly 32 is energized to
provide lateral motion to the wire probe 24 and the probe is gently
20 pushed against the stone.
This apparatus does not operate as desired when tip 26 of the wire
probe slips off the surface of the stone 22 and slides past it as
illustrated in the dotted line position of tip 26'. In this
circumstance tip 26' does not perform its intended function. Increasing
25 the surface area of the cutting tip causes it to break off from the
probe 24 at end 20 of catheter 16, at the point of greatest stress where
it emerges from the catheter.
With the foregoing in mind, a cutting tip 44 shown in Figures 2 and
3 is attached to end 26 of the wire probe to overcome the problem of
30 wire slippage and to greatly increase the cutting surface area. Tip
member 44 provides two structural features, one of which prevents
premature breakage of the wire probe at the point of its exiting the
catheter 16, while the other assures seating of the kidney stone within
the tip member 44.
35 Member 44 is of stainless steel construction and comprises two
integrally formed coaxial cylindrical sections, an elongate collar
section 46 which relieves stress, and a cutting tip section 48.
Member 44 is also provided with a central circular opening (not
shown) which extends completely through collar section 46 and through
most of cutting tip section 48. The opening has a diameter sufficiently
wide so that it is just capable of being slid over wire tip 26. By
5 inserting wire tip 26 through the opening as far as possible into the
cutting tip section 48, the end of the cutting tip section is arranged
to initially abut the kidney stone encountered. Member 44 is thereafter
compressed and swaged to the wire probe 24, such as at points 58 and 60
of the cutting tip section 48, thereby ensuring its permanent retention
10 thereon. Additionally, tip 26 can be undercut so as to present a
recessed surface, further enhancing the swaging procedure.
Collar section 46, has an external diameter larger than that of
probe 24, but less than the inner diameter of catheter 16 and is of
sufficient length to insure that it only partially extends out of the
15 catheter when it is in the operational mode, best illustrated in Figure 3.
Cutting tip section 48 has a slightly larger external diameter than
the external diameter of collar section 46 but less than the inner
diameter of ureter 18. It is provided with a plurality of cutting
teeth, preferably between three and six. The cutting tip section 48 is
20 illustrated in Figure 2 as having four teeth 50, 52, 54, and 56. Teeth
50, 52, 54, and 56 are formed on the periphery of one end of the cutting
tip section to provide a cup-shaped receptacle for seating a kidney
stone 22. Teeth 50, 52, 54, and 56 are machined directly into the end
of cutting tip section 48 and are desirably provided with flat ends so
25 as to preclude the possibility of a pointed tooth surface frcm scraping
the urethra. While no specific configuration for the teeth is
necessary, it has been found that a suitable arrangement is one where
the teeth are equidistantly-spaoed, three-sided with one corner forming
the cup-shaped receptacle, and with a tapering cross section.
30 While not intended to be limiting, the following approximate
dimensions of the cutting head 44 are presented by way of example only:
Diameter of cutting tip section 48—0.063 inches
Length of cutting tip section 48—0.16 inches
Diameter of collar section 46—0.045 inches
35 Length of collar section 46—0.233 inches
In such a configuration, the member 44 attached to the wire probe 24
transmits maximum acoustic vibrational energy from the probe to the
stone 22. The relatively large diameter of cutting tip section 48
increases the cutting surface area by a factor of three or more and
5 insures maximum contact between wire and stone 22 as well as prevents
slippage of the wire past the stone. The cup-shaped end of the tip 48
induces seating of the stone 22 on the cutting tip.
The four teeth 50, 52, 54, and 56 assure maximum fragmentation of
the stone 22. Even if the stone 22 is highly irregular in shape and
10 centering of the tip 48 upon the stone is far from perfect, the stone
will fragment when contacted by any portion of the cutting tip.
The lifetime of the wire probe 24 is substantially increased by the
provision of an elongate collar 46 which partially stays within the
catheter 16 while the cutting tip section 48 is extended against the
15 stone 22. The collar 46 greatly lessens the mechanical bending loads
and stress points imposed on the wire 24 by the vibrating mass of the
cutting tip 48, because the root of the mass is within the catheter 16
and not cantilevered away from it. Further, by joining the cutting tip
48 to the wire 24 by a swaged joint 58, 60 rather than by soldering,
20 - mechanical stresses and fatigue fractures are greatly lessened. The
life of the assembly has been found to exceed four minutes when
vibrating at 20 KHz, thus providing ample time to complete the kidney
stone disintegration procedure.
Having thus shown and described the invention in specific detail,
25 the same has been provided by way of explanation and not limitation and
accordingly all modifications, alterations and changes coming within the
spirit and scope of the invention are herein meant to be included.
CUTTING HEAD FOR ULTRASONIC LITHOTRIPSY
ABSTRACT
A cutting head for attachment to the end of the wire probe of an
ultrasonic kidney stone disintegration instrument. The cutting head has
a plurality of circumferentially arranged teeth formed at one end
thereof to provide a cup-shaped receptacle for kidney stones encountered
during the disintegration procedure. An integral reduced diameter
collar diminishes stress points in the wire and reduces breakage
thereof.


Cutting head for ultrasonic lithotripsy

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