Note: Descriptions are shown in the official language in which they were submitted.
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~OUSTIC IMPAC~ DE~IVERY CA~H~TER WI~H END CAP
FIELD OF THE INVENTION
The present invention relates to a method and
apparatus for fracturing hard formations in the body, and
more specifically, to a method and apparatus for
transferring ener~y to the end cap of a fle~ible guide
which imparts a high-velocity impulse to a target deposit
thereby fracturing it.
BACK~ROUND OF THE INVENTION
Calciferous and similar deposits occur in body fluid
passages of various type~. Of particular interest are
kidney and gall stones as well as arterial plaque.
Radiation in various forms has been used for
destroying or removing such deposits from the internal
passages of the ~ody. In one form of laser therapy,
radiation is directed onto a light-receiving surface of a
heat-generating element. The element is then placed in
contact with the target deposit, melting it. This
approach has several drawbacks which include:
l. thermal damage to surrou~ding tissue;
.- only fatty plaques readily melt;
3. more ad~anced fibrous and calcified plaques form
char and debris, and
4. the hot element adheres to the tissue rupturing
it when the elem~nt is removed.
In another approach, laser radiation is applied
directly to the target deposit to ablate it or produce
shock waves that induce fragmentation. Direct lasertripsy
has several disadvantages. Laser energy often damages
heal~hy tissue surrounding the target deposit by direct
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absorption or by acting as a general heat sink for the
high temperature plasma. Some deposits only weakly absorb
radiation thereby requiring greater radiation e~posure and
damage. A sharp laser delivery fiber can cause damage if
inadvertently jabbed into healthy tissue.
~MMARY OF THE INVENTION
The present invention contemplates a method and
apparatus for seleGtively fracturing hard deposits in
fluid containing body passages with the impact of small
jack hammer like blows from a capped fle~ible guide
inserted through the body passage to the location of a
deposit to be fractured.
In implementing the invention, a fle~ible wire guide
terminating with a hard mass or end cap is provided for
insertion through a fluid containing body passage. An
energy source and delivery system in the fle~ible guide
provide a pulse of energy in the vicinity of the cap to
produce a rapid vapor e~pansion that causes the end cap to
un~ergo a pulse like movement as the vapor e~pands against
the fluid medium of the passage to impart a high-velocity
impulse ~o the target deposit. A means for fluid exchange
between the interior and e~terior of the apparatus is
provided in the end cap region to insure the presence of
fluid for increasing the direct impulse against the cap.
In a firsl: embodiment of the invention, the energy
source is a pulsed laser and the delivery system is an
optical fiber pa~sin~ through the guide to terminate
adjacent to a metal end ~ap. The laser energy causes
vaporization of a ~mall portion of the end cap to create
the vapor e~pansion that drives the end cap forward
against the inertia of the fluid.
In a second embodiment, the energy source is a
pulsed voltage sourc~ and a pair of conductors, one of
which may be the wire guide, comprising the delivery
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system. The conductors terminate in a spark gap adjacent
to the end cap. A spark pulse causes fluid vaporization
adjacent to the end cap, thereby driving it forward as a
reaction.
An advantage of the invention includes the end cap's
protection of surrounding healthy tissue rom direct laser
radiation and thermal radiation from the laser-produced
plasma of the vapor e~pansion which forms against the
inside ~urface of the end cap. A further advantage of the
invention is the elimination of inad~ertent puncturing of
healthy tissue by a sharply pointed laser delivery fiber.
In the laser embodiment, the end cap is fabricated
to e~hibit good laser absorption providing a reliable,
reproducible vapor expansion independent of the absorption
characteristics of the target deposit.
DESCRIPTION OF THE DRAWINGS
The invention will be more fully understood from the
following solely esemplary detailed description taken in
conjunction with the accompanying drawing, in which;
Fig. 1 is a diaqram of one embodiment of the
invention which utilize~ a laser-produced vapor e~pansion
to dri~e a hard mass to contact and fragment a target
dePosit;
Fig. 2 is a diagram of a ~econd embodiment of the
invention which utilizes an electrically-produced ~park
discharge that produces a vapor e~pansion to drive a hard
mass, to contact and fragment a target deposit;
Fig. 3 is a diagram of a variant of the invention of
Fig. 2 which utilizes an electrically-produced plasma from
a central two wire conductor to drive an internally
confined spring-loaded end cap to fragment a target
deposit;
Fig. 4 is a diaqram of a further variant of the
invention of Fig. 2 which utilizes an
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electrically-produced plasma from a central two wire
conductor to drive an internally confined stainless steel
end cap with irrigation ports, to contact and fragment a
target deposit;
Fig. 5 is a diagram of the fragmentation system of
the invention inside a body passage with fragmented target
deposits at its distal end and a positioning fluoroscope;
and
Fig. 6 is a diagram of an end cap of the inven~ion
demonstrating the pulse-like advancement of the end cap
with subsequent fracturing of the target deposit.
DETAILED DESCRIPTION OF T~E INVENT~ON
The present invention contemplates a method and
apparatus for driving a small, hard mass into fracturing,
high velocity contact with hard deposits in
fluid-conta~ning body passages.
A first embodiment of th~ invention is illustrated
in Fiq . 1~ A flesible wire guide 10, which typically
comprises a commercially available, helically wound French
No. 3 guide (0.85 - 1.00m diameter3 has an end cap 12, the
cap and guide are typically of stainless steel or other
material which, in response to laser radiation, will
vaporize, in a rapid vapor e~pansion. An optical fiber 14
(typicall~ a 200 micron core) i~ fed through the wire
guide 10 and terminates at a point 16, a short distance
from the end cap 12. Laser radiation emanating from the
termination 16 ~trikes the end cap and is absorbed by the
metal of the end cap 12, ~au~ing vaporization of a small
portion of the metal. In ~ctual use, the helical winaings
of the gui~e 10 are ope~ed ~n a terminal portion lB, for
e~ample by stretching the last few coils, to facilitate
the entry of fluid from body passa~es, in which the guide
is inserted, into the region of the t~rmination 16. The
rapid vapor espansion, typically of shock wave nature,
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generates a forward pressure impulse on the cap 12, in the
nature of a miniature jack hammer.
Where the cap 12 has been inser~ed in a body
passage, typically the urethra to a kidney stone, it is
5 capable of fragmenting pieces of the kidney stone, such as
the stone 20, to which it comes into contact. The
presence of the body fluid creates a mass within the
region of the termination 16 where the vapor espansion
occurs which confines the espansion and permits a large
10 portion of the energy of the vapor espansion to be
directed against the end cap 12 producing a high-velocity,
short forward impulse.
The source of radiation applied to the fiber 14 is a
laser system 22. Laser system 22 is typically a tunable
15 dye laser. The laser is operated in the mode of producing
pulses of approsimately 1 microsecond duration and
approximately 50 millijoule energy level. Other pulsed
laser systems capable of promptly initiating a plasma
against the cap and compatible with optical fiber
transmission would also be acceptable enerqy sources.
This would include, for esample, solid state laser systems
such as Alesandrite. A pulsed output be-am 29 from the
laser 22 is applied to an optical coupling system 26 which
in turn applies the pulsed radiation in beam 24 onto
25 optical fiber 14. The fiber 14 pas~es through a clamp 28
connected to the guide 10 and operative to hold the fiber
termination 16 at a predetermined distance from the
cap 12. A potting compound near the termination may be
used to secure the fiber termination.
3n A second embodiment of the inventiGn is illustrated
in Fig~ 2. As shown there a wire guide ~0, which may be
similar to the guide 10 in Fig. 1 and typically of a size
corresponding to French No. 3, terminates in an end cap 42
at a distal end 44 of the wire guide 40. The wire guide
35 is typically helically wound as described before and the
termin~tion 4~ has helical wires of augmented spacing, for
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e~ample, by being stretched, to permit the flow of fluid
through an interior portion.
A wire conductor 46 is inserted through the wire
guide 40, spaced and insulated from the helically wound
5 wires of the guide 40. The inner conductor 46 terminates
at a point 48, ad~acent to the cap 42. The wire may be
held in place by a positioning clamp 50, or potted in
place with an adhesive as described ~bove with respect to
Fig. 1.
A spark generator 52, which can be a Wolfe 2137.50
or Northgate Research SDl, available in the art, has its
output applied on conductors 54 and 56, the conductors are
connected to the inner conductor 46 of the guide 40 and
the outer helical windings of the guide 40. The spark
15 generator 52 produces an output pulse of up to several
microseconds, at several KV and up to lKA current. The
spark generated between the termination 48 of the inner
conductor 46 and the e~d cap 42 causes a vapor e~pansion
of the fluid entering the tip portion 44 and/or the metal
20 Of the cap 42 creating a jack hammer like shock impulse
movement of the end cap 42, permitting it to fracture
calciferouæ deposit~ which it contacts.
A different ~ersion of the embodiment illustrated in
Fig. 2 is æhown with respect to Fig. 3. A wire guide 60,
typically of the type illustrated above, though not
nec~æsarily having a conducting outer shell, has a
termination 62 which may be an open helical portion of the
wire ~uide of the prior embo~iment~. An end cap 64 is
applie~ to the aistal end of the wire guide 60. A dual
30 conductor tranæmission line 66 pasæes centrally through
the wire guide 60 terminating ~t ~ point 68 adjacent to
the cap 64. The transm~ssion line 66 contains first and
æecond conductor~ 70 and 72 which terminate to provide a
spark gap at the termination 68. The gap is selected to
35 pro~ide, in response to energization from a spark
generator 7~, of the type illustrated above with respect
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to Fig. 2, a vaporization of the fluid within the terminal
portion 62 generating an impulse motion of the cap 64. A
transmission line of the type provided with the
above-identified supplier of the spark generator and
intended for independent insertion into body passages is
5 suitable for insertion within the guide 60.
Fig. 4 illustrates a further version of the
embodiment of Fig. 2. A spark generator 80 is provided,
and a two conductor transmission line 82 con~ucts the
output of the spark generator through a guide 84 into a
10 stainless steel end cap 86. The end cap 86 is typically
cemented to the distal end 88 of the wire guide 84.
Apertures 90 are provided in the end cap 86 ~o permit body
passage fluids to enter the interior of the end cap B6 to
a point 92 where the conductors in the transmission
lS cable 92 terminate in a spark gap. The terminal portions
of the end cap 86 wire guide 84, where it connects to the
end cap 86, are typically resilient enough to permit the
impulses gçnerated by the spark from the spark gap 92
termination to drive the e~d cap 86 forward in jack hammer
20 fashion to permit fracturing of hard deposits to which it
is directed.
In actual use, and as illustrated in Fig. 5, a wire
guide 100 according to the present invention is inserted
through a body pa'ssaqe 102 such as the urethra, for kidney
25 stone fracturing t the biliary duct for gall stone
fracturing and an artery for arterial plaque break-up.
The end tip 104 of the wire guide 100 is guided by
fluoroscopy. An X-ray source 106 and viewing display lOB
permit the end of the wire guide 100 to be positioned
30 adjacsnt to a hard deposit 110 to be fractured as
illustrated.
Fig. 6 is an illustration of the dynamics by whioh
an end cap 120 is jaek hammered or shock driven forward
into a hard deposit 122 by a spark generated by a
35 discharge in a ~park gap 126.
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Impulse delivery systems other than laser or spar~,
such as chemical reaction, trigger remotely by signals
supplied by a guide, may be used.
It will be understood that all matter herein
5 described or shown in the accompanying drawings is to be
interpreted as illustrative only and is not to limit the
invention defined in the following clai~s.
