U.S. patent number 5,242,437 [Application Number 07/460,843] was granted by the patent office on 1993-09-07 for medical device applying localized high intensity light and heat, particularly for destruction of the endometrium.
This patent grant is currently assigned to Trimedyne Laser Systems, Inc.. Invention is credited to George M. Acosta, Royice B. Everett, Hany M. G. Hussein.
United States Patent |
5,242,437 |
Everett , et al. |
September 7, 1993 |
Medical device applying localized high intensity light and heat,
particularly for destruction of the endometrium
Abstract
A medical device applies localized heat to a site in a patient's
body by irradiation with light and by conduction. The device
includes a radiant energy transmitting conduit, typically an optic
fiber, that carries radiant energy, typically high intensity light
such as laser, into a body cavity, typically the uterus, from an
energy source, typically a laser source, that is located exterior
to the body. At the operative head of the device within the body
cavity a portion of the transmitted radiant energy is absorbed and
converted to heat. This heat is radiated or conducted from the
device head substantially omnidirectionally in order to aid in
destruction of tissue. Meanwhile, another portion of the
transmitted radiant energy is emitted through an aperture in the
device head as light energy suitable for more localized and intense
heating and destruction of tissue or other organic matter. This
light emission is preferably directionally transverse to an
elongate body of the device head. The device is suitable for
selective destruction of tissue or other matter by highly localized
heating.
Inventors: |
Everett; Royice B. (Edmond,
OK), Acosta; George M. (Long Beach, CA), Hussein; Hany M.
G. (Costa Mesa, CA) |
Assignee: |
Trimedyne Laser Systems, Inc.
(Irvine, CA)
|
Family
ID: |
26900225 |
Appl.
No.: |
07/460,843 |
Filed: |
January 11, 1990 |
PCT
Filed: |
June 07, 1989 |
PCT No.: |
PCT/US89/02492 |
371
Date: |
January 11, 1990 |
102(e)
Date: |
January 11, 1990 |
PCT
Pub. No.: |
WO89/11834 |
PCT
Pub. Date: |
December 14, 1989 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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205218 |
Jun 10, 1988 |
|
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Current U.S.
Class: |
606/15;
607/89 |
Current CPC
Class: |
A61B
18/24 (20130101); A61B 18/28 (20130101); A61B
17/42 (20130101); A61B 2018/2272 (20130101); A61B
2017/00084 (20130101); A61B 2017/4216 (20130101); A61B
2017/0007 (20130101) |
Current International
Class: |
A61B
18/20 (20060101); A61B 18/28 (20060101); A61B
18/24 (20060101); A61B 17/42 (20060101); A61B
18/22 (20060101); A61B 17/00 (20060101); A61B
017/32 () |
Field of
Search: |
;606/7,13-17
;128/6,395-398 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hindenburg; Max
Attorney, Agent or Firm: Dressler, Goldsmith, Shore, Sutker
& Milnamow, Ltd.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of our copending U.S.
patent application Ser. No. 205,218, filed Jun. 10, 1988, now
abandoned.
Claims
What is claimed is:
1. A medical device for conducting laser energy from a region
outside the body to a cavity within the body and for applying the
laser energy to the body both as radiation and as heat, the device
comprising:
an elongated laser energy conduit having distal and proximal ends
for extending from a proximal end region outside the body to a
distal end region at the cavity within the body;
a source of laser energy optically coupled to the laser energy
conduit for transmitting laser energy from the proximal end region
to the distal end region of the conduit;
a beam splitter means, located at the distal end region of the
elongated laser energy conduit and receiving the laser energy
transmitted by the source of laser energy to the distal end region
of the conduit, for splitting the received laser energy into at
least a first and a second portion of laser energy;
an element receiving the first portion of laser energy from the
beam splitter means for converting the received first portion of
laser energy to heat; and
an aperture, defined by and positioned within the element,
receiving the second portion of laser energy from the beam splitter
means for radiatively communicating this received second portion of
laser energy substantially transversely to the axis of the
elongated conduit and externally to the medical device;
said beam splitter means comprising:
a notch within the laser energy conduit at its distal end region
for radiatively directing a portion of the laser energy that is
transmitted by the source of laser energy to the distal end region
of the conduit further to the aperture as the second portion of
laser energy; and
a light-receiving surface positioned oppositely to a distal end of
the laser energy conduit for receiving another portion of the laser
energy transmitted by the source of laser energy to the distal end
region of the conduit and for transmitting this portion to the
element as the first portion of laser energy.
2. The medical device according to claim 1 wherein the element's
aperture is located at a position proximate to the distal end of
the laser energy conduit and to the beam splitter means.
3. The medical device according to claim 2 wherein the element's
aperture is relatively narrower where it is proximate to the laser
energy conduit and to the beam splitter means and is relatively
wider where it exits the element.
4. The medical device according to claim 3 wherein an included
angle of the element's aperture is less than 90 degrees.
5. The medical device according to claim 1 wherein the element's
aperture is substantially in the shape of a frustum with base of
the frustum disposed to the exterior of the element and the
truncated apex of the frustum abutting the beam splitter means.
6. The medical device according to claim 5 wherein the element's
frustum-shaped aperture is substantially frustoconical.
Description
TECHNICAL FIELD OF THE INVENTION
The present invention relates to medical devices and procedures for
applying localized heat to a site in a patient's body, particularly
for purposes such as the excising of tissue or deposits, or the
cauterizing or destruction of tissue.
BACKGROUND OF THE INVENTION
Localized heat applied to a site in a patient's body has often been
used to cauterize a lesion in order to stop bleeding. Localized
heat can also be used to alter, remove, or destroy tissue in a
patient's body. One example of the medical use of localized heating
is in the treatment of a bleeding ulcer. An endoscope is inserted
through a patient's esophagus to view the bleeding site and to
guide an electric powered heating element to contact the site and
cauterize the bleeding. Another example is the use of localized
heating to remove neoplastic pulmonary tissue. Still another
example is the use of such heating to cauterize the
endometrium.
Unfortunately, electric heating elements can be both difficult to
manipulate and slow heating. The heating rate and maximum
sustainable temperature are limited by the electric current
available to the element. The available current in turn is limited
by the size of the wires leading to the element. Wire size limits
access to body sites for two reasons: larger wires cannot be
inserted into small areas, and increased wire size typically causes
a loss of flexibility.
The electric current passing through the wires also limits the
regions in the body in which such a device can be used. The current
presents a threat of an electric shock to the patient. The electric
field generated by flowing current can also have undesirable
effects. One region where such an electric field could possibly be
life threatening is in the heart.
One electrically heated medical device in which the end of an
endoscope is heated to avoid dew forming on a window is shown in
U.S. Pat. No. 4,279,246 to Chikama. That device heats the window to
about body temperature to prevent dew formation. However, due to
the design of the device, the heat generated on the window is
limited to about body temperature and therefore cannot be used to
alter or destroy tissue.
Another electrically heated medical device that becomes
sufficiently hot so as to cauterize tissue is shown in U.S. Pat.
No. 4,449,528 to Auth et al. A miniaturized, endoscopically
deliverable thermal cautery probe is used to cauterize internal
vessels. The probe is applied to tissues cold, and a large number
of electric heating pulses of equal energy are then applied to an
internal heating element within the probe. The probe's internal
heating element is in direct thermal contact with an active
heat-transfer portion that has a low heat capacity. The low heat
capacity of the heat-transfer portion insures quick heating and
subsequent cooling, thereby adequately coagulating tissue while
minimizing heat penetration and resulting tissue damage.
Because of the difficulties with electrical heating, medical
devices, systems and methods have been developed for applying
localized heat that is generated otherwise than by routing an
electric current to a site in a patient's body. The localized heat
so generated can be used for several purposes. For example, it may
be used to cauterize a lesion to stop bleeding, to remove a clot,
or to remove an arteriosclerotic deposit from a blood vessel. The
localized heat can also be used to create an open channel in a
previously occluded blood vessel.
One medical device not employing electrical current for heating is
described in U.S. Pat. No. 4,207,874 to Choy which discloses a
laser tunneling device used to locate, analyze, illuminate and
destroy obstructions in a lumen such as a blood vessel. The device
includes a fiberoptics bundle in a flexible conduit that is
insertable into the blood vessel. The conduit includes a connection
to a suction source at one of its ends, a valved means of
controlling the application of suction which also functions to
control the injection of locating material, and a connection to the
fiberoptics bundle. The fiberoptics bundle is divided into an
illuminating source bundle portion, a viewing bundle portion and a
laser bundle portion. The device functions to remove obstructions
in tube structures of both biological and non-biological types by
inserting of the conduit sheathed device into the tube structure in
a position distal to the obstruction.
Still a further prior medical device contemplates use of a single
fiberoptic light transmission path within a medical catheter device
to be either a viewing system, a laser light transmitting system,
or a combination of both. In U.S. Pat. No. 4,445,892 to Hussein et
al., a dual balloon catheter device is shown to have two spaced and
expandable balloons for occluding a segment of a blood vessel. An
optic system is used in the segment for viewing or for delivering
laser light. Both the viewing and the laser light delivery are
through a circumferential window within the tubular structure of
the catheter.
U.S. Pat. No. 4,646,737 to Hussein et al., describes a device that
includes a heat-generating element mounted on the distal end of an
elongated electromagnetic energy transmitting conduit or member. A
preferred conduit is a single flexible quartz optical fiber.
Electromagnetic energy in the form of visible light from an intense
light source, such as a laser, is transmitted through the conduit
and is emitted onto a light-receiving surface of the
heat-generating element. The light is converted by the element to
heat. The heated element is then placed in contact with material in
a patient's body such as a clot, deposit or tissue. The heated
elements alter the material by melting, removing or destroying it.
The heat-generating element preferably has a rounded exterior
surface end. It is typically retained on the conduit by a locking
means, such as by a ridge on the element that is received in a
complementary groove on the conduit.
Still other prior medical devices tunnel and cut bodily tissue and
other material within the body by direct application high
intensity, typically laser, light that is typically conducted
through fiberoptics. Laser devices -- the acronym "laser"
indicating light amplification by the stimulated emission of
radiation -- are well known. Briefly, a laser device operates by
using an intense source to cause ions to become inverted with
respect to their normal energy distribution. The tendency of such
ions is to relax to a so-called "ground state" (a normal
distribution), and in so doing to stimulate inversion of other ions
within the same wavelength. A synchronized output is promptly
achieved wherein the ion's relaxations from an inverted energy
state transpire in unison. A massive output of energy is thereby
obtained. The output wavelength is determined by the difference
between the energy level from which the ions relax and the ground
state energy level which the relaxed ions assume.
The medical device shown in U.S. Pat. No. 3,315,680 to Silbertrust
et al., describes a cauterizer using fiberoptic techniques to
conduct ordinary and laser light in a medical application. U.S.
Pat. No. 3,821,510 to Muncheryan shows the use of a laser system
which accommodates fluid flow to control the temperature of the
work area.
German Patent No. 2,826,383 to Eichler et al., shows a tubular
probe for laser surgery that is placed against or inserted in
tissue. In one embodiment, an end piece having an absorbent surface
is heated by the beam while it is in contact with the tissue,
thereby heating the tissue. Alternatively, in another embodiment,
the end is transparent and permits the laser beam to pass through
the end in order to radiatively heat the tissue.
These various types of prior medical devices do not permit that
tissue destruction using the lateral direction of high intensity
radiated light and using radiated and/or conducted heat should be
performed closely proximately, or simultaneously, in time. This can
be very useful when it is desired to destroy large surface areas of
tissue to a substantial depth.
For example, a surgical procedure referred to as "endometrial
ablation" has been recently developed as an alternative to
hysterectomy for treatment of excessive uterine bleeding. In this
procedure, an Nd:YAG laser is used to destroy the entire
endometrium lining the uterus. An optical fiber is inserted in the
uterus by means of a hysteroscope to conduct the laser energy to
the endometrium. With the aid of a parallel optical viewing fiber
of the hysteroscope, the end of the laser-transmitting fiber is
slowly moved across the surface of the endometrium so that the
laser energy penetrates and destroys the endometrium which is on
the order of three millimeters thick. Typical prior art procedures
have utilized a bare optical fiber for transmitting the laser
energy. Two techniques have been developed. By one technique, the
end of the bare optic fiber is actually touched to the endometrium.
By a second technique, generally referred to as "blanching", the
bare tip of the optic fiber is held several millimeters away from
the endometrium. These techniques are generally described in
Daniell et al., "Photodynamic Ablation of the Endometrium With the
Nd:YAG Laser Hysteroscopically as a Treatment of Menorrhagia",
Colposcopy & Gynecologic Laser Surgery, Vol. 2, No. 1, 1986;
Mackety, "Alternative to Hysterectomy: Endometrial Albation by
Laser Photovaporization", Today's OR Nurse, Vol. 8, No. 4; and
Goldrath et al., "Laser photovaporization of endometrium for the
treatment of menorrhagia", Am. J. Obstet. Gynecol., Vol. 140, No.
1, page 14, May 1, 1981.
Some surgeons prefer the "blanching" technique because it is
believed to create fewer complications. There is less danger of
mechanical perforation of the uterus. There is less actual
vaporization and cutting of the endometrial tissue and accordingly
less fluid absorption thereby.
It is difficult, however, to treat the side walls of the uterus by
"blanching" due to lack of room to maneuver the optic fiber so as
to direct it toward the side walls. Thus a touching or dragging
technique has necessarily been utilized during those portions of
the procedure. In addition to being unable to direct the laser
energy directly at the side wall of the endometrium, this touching
of the fiber tip to the endometrium is, as mentioned, considered
undesirable by some surgeons.
Furthermore, with the touching technique, and to a lesser extent
with the blanching technique, there is always the problem of
completely treating the entire endometrium without missing small
areas here and there.
Accordingly, it would be desirable if a medical device were
available which would permit more of the laser energy to be
directed transversely from the optical fiber toward the side wall
of the endometrium. It would further be desirable to maintain some
suitable spacing between the tip of the optic fiber and the
endometrium. Also, it is desirable that heat be conductively
applied to the endometrium while simultaneously directing the laser
energy to a more localized spot thus better insuring destruction of
the entire surface of the endometrium.
It would additionally be useful if the operative excising and
cauterizing head of the device were to somehow be directional, as
well as necessarily controllable, in one or both of its light
radiation and/or its conductive heating effects. A preferred
operational direction of the device, operative head for either the
lateral transmission of light or the conductive heating of tissue
would permit that one effect could be maximized over the other by
action of the surgeon's positioning and orientation of the device's
operative head within the body cavity. Furthermore, a device
exhibiting a preferred directionality would presumably exhibit some
safe orientation in which orientation the device's operative head
would not be prone to destroy and/or burn the lining of the body
cavity within which it was situated.
SUMMARY OF THE INVENTION
The present invention is embodied in a medical device for locally
applying plural forms of energy to a selected body site, and in a
method of so applying such energy. In accordance with the apparatus
and method aspects of the invention, laser energy transmitted along
a fiber optic may be apportioned so that a portion of the
transmitted energy exits the medical device as a laser beam while
the remainder is converted to heat energy. In this manner, both
laser energy and conductive heat energy may be applied
substantially simultaneously to the body site for performing a
medical procedure.
The apparatus aspect of this invention contemplates an elongated,
laser energy transmitting conduit that is provided with a
beam-splitting means at its distal end and is optically coupled at
its proximal end to a laser energy source. A hollow, apertured
bulbous element capable of converting laser energy into heat is
mounted on the distal end of the laser-transmitting conduit. The
bulbous element defines a cavity within which the distal end of the
conduit is received. The bulbous element also defines an aperture
that communicates with the cavity. The defined aperture is
positioned vis-a-vis the conduit so that it is to one side of the
laser energy path that enters the aforementioned cavity but is in
registry with a laser energy beam generated by the beam-splitting
means. In this manner, a portion of the laser energy transmitted by
the conduit is converted into heat while the remainder of the
transmitted laser energy exits from the bulbous element via the
aperture as a laser energy beam along a path that is different from
the laser energy path entering the cavity.
The cavity within the bulbous element is typically a simple bore.
The defined aperture is in the shape of a wedge, trough, cone,
paraboloid or other surface proceeding from a generally wider
opening at the surface of the bulbous element to a generally
narrower apex that intersects the bore. The beam-splitting means is
preferably a reflective surface situated within the cavity so as to
intersect some portion of a laser energy bean emitted from the
distal end of the laser-transmitting conduit, and so as to reflect
a portion of the intercepted beam through the aperture to exit the
bulbous element while a remaining portion penetrates the bulbous
element, producing heat. The beam-splitting means may alternatively
be realized by removing a portion of a light reflective cladding,
or surrounding reflector, to the light-transmitting conduit,
thereby allowing an escape of laser light energy from the bulbous
element via the aperture.
A method aspect of this invention contemplates the introduction of
the present apparatus or device into, for example, a body cavity or
lumen of a patient and thereafter irradiating a selected body site
with a laser energy beam while applying heat at a relatively lower
energy density to the body site by conduction utilizing the bulbous
element. In this manner coagulation, vaporization, as well as
cutting can be effectively performed at the body site.
The laser energy used by the medical device in accordance with the
present invention may be infrared (IR) and excimer laser light as
well as visible laser light. Various suitable energies are produced
by CO.sub.2, Argon, Nd:YAG, excimer and other types of lasers.
Particularly when the beam-splitting means of the device is
implemented as a reflective surface of gold (Au), the device is
very effective in providing both conductive and heat energy for a
range of laser radiation frequencies, types, and energies.
Numerous other advantages and features of the present invention
will be readily apparent to those skilled in the art from the
following detailed description of the preferred embodiment of the
invention, the drawings, and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a system including a medical device
embodying the present invention in use within a human uterus.
FIG. 2 is an enlarged side view, partly in section, of the distal
end portion of the medical device of FIG. 1.
FIG. 3 is an enlarged end view of the distal end portion of the
medical device of FIG. 1.
FIG. 4 is an enlarged cross-sectional view of the distal end
portion of the medical device, taken along PLANE 4--4 in FIG. 2,
with a portion broken away to show additional detail.
FIG. 5 is an enlarged cross-sectional detail view of the distal end
portion of the medical device of FIG. 1; and
FIGS. 6-12 are similar to FIG. 5 and illustrate alternative
embodiments of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
While the present invention can be embodied in many different
forms, there is shown in the drawings, and described in detail, a
preferred embodiment of the invention. The present disclosure is an
exemplification of the principles of the invention and is not
intended to limit the invention to the embodiment illustrated.
The present invention is a medical device for delivering and
applying localized heat as well as a laser beam to a site upon, or
more typically in, a patient's body. The applied energy can be used
to selectively stop bleeding, or to remove or alter a material such
as tissue or deposit in or on the body by vaporization, or to make
an incision. The material being altered can be any solid or
semi-solid substance found in or on the body including living
tissue (including cancerous tissue) or deposits such as clots, fat
or arteriosclerotic plaque. A particularly useful application of
the invention is the destruction of the endometrium lining the
uterus.
Referring to FIG. 1, medical device 10 embodying the present
invention is shown positioned within the uterus 100 of a human
female patient. Device 10 comprises hollow, apertured bulbous
element 18 positioned within uterine cavity 116 near endometrium
117. The endometrium 117 is a thin layer of tissue lining the
entire uterine cavity 116 which is defined by an upper fundus 119
and a somewhat cylindrical side wall 121. The side wall 121 can
generally be defined as extending from the tubal ostia 123 and 125
down to the internal cervical os 127.
Bulbous element 18 is mounted on the distal end of elongated, laser
energy transmitting conduit such as fiber optic 22 which, in turn,
is optically coupled at its proximal end 14 to laser energy source
50. Optionally, a pyrometer 60 is provided at the proximal end
region of device 10 for measuring the temperature of bulbous
element 18. To that end, a reflected beam from bulbous element 18
is conducted to pyrometer 60 utilizing a beam-splitting means 70
such as a partial mirror, a rotating mirror, or the like.
Device 10 is inserted as part of a hysteroscope (not shown) into
uterus 100 via vaginal canal 112 and through the internal cervical
os 127 of cervix uteri 111 using appropriate dilation procedures as
will be described in greater detail hereinbelow. The body or side
wall 121 of uterus 100 is supported by broad ligaments 114 and
115.
An enlarged view of the distal end portion of device 10 is shown in
FIG. 2. Bulbous element 18 defines an internal cavity 20 within
which is slidably received the distal end of fiber optic 22 which
serves as the laser energy transmitting conduit. A clearance is
provided between the distal end of fiber optic 22 and cavity 20 to
accommodate differences in thermal expansion that may be
encountered upon the heating of bulbous element 18. Bulbous element
18 also defines aperture 24 that communicates with cavity 20 and
provides an exit passageway for a laser energy beam diverted from
the laser energy path of the laser energy entering cavity 20 via
fiber optic 22. Diversion of the laser energy beam is achieved by
beam-splitter means 26 which in one embodiment is a concave side
portion of fiber optic 22 with laser light reflecting cladding
removed therefrom. The beam splitter means 26 can also be a rounded
end of fiber optic 22 without a reflective cladding, or a separate
lens, e.g., a sapphire lens, positioned at the terminus of fiber
optic 22, that reshapes and redirects the laser beam.
The beam splitter means may still further be a reflective surface,
or mirror, on the wall of cavity opposite to the distal end of
fiber optic. The reflective surface may be positioned so as to
intercept all or part of the laser energy beam emitted from the
distal end of fiber optic, and may be of varying reflective
efficiency so as to reflect substantially all or only part of the
intercepted laser energy beam. The reflective surface may be varied
in its position, size, and/or efficiency to adjust the relative
level of energy converted into heat versus that which exits from
the bulbous element 18 as a laser energy beam.
The operation of various embodiments of the beam-splitter means
will be described in greater detail hereinbelow.
The internal cavity 20 of bulbous element 18 exhibits features
32-34 that facilitate the reception and clenched retention of
bulbous element 18 upon fiber optic 22. The fiber optic 22
generally has a total exterior diameter or transverse dimension of
about one (1) millimeter or less. Nonetheless, it generally has
sufficient rigidity both to be pushed into a narrow, complementary
sized, bore region 30 of cavity 20. The fiber optic 22 is
facilitated in being guided into a tight fit within narrow bore
region 30 by guidance accorded the fiber optic 22 in large bore
region 32 to cavity 20.
When inserted to the indicated depth within bore regions 30, 32 of
cavity 20, and properly rotated so that beam-splitter means 26 is
properly aligned to aperture 24, the fiber optic 22 may be
inspected through holes 34 defined in the sidewall of stem 12
connected to bulbous element 18. Holes 34 also provide a vent means
that serves to relieve any pressure that may be generated within
the bulbous element 18 due to gas expansion or vaporization of
liquid as element 18 is heated. Additionally, holes 34 reduce the
cross-sectional area available for heat transmission along the
outer sheath 13 of hollow stem 12 unitary with bulbous element 18.
Outer sheath 13 is further provided with a thermal expander section
15 which is an enlarged cylindrical segment unitary with stem 12
that serves to accommodate thermal expansion of stem 12 as bulbous
element 18 is heated.
Fiber optic 22 is secured to stem 12 in the region 17 immediately
behind or abaft of thermal expander section 15, preferably by
crimping or like mechanical securement means. Alternatively, or in
addition, a heat resistant adhesive such as an epoxy glue may be
used.
An enlarged distal end view of the medical device 10 is shown in
FIG. 3. The aperture 24 shown in FIGS. 2 and 3 is preferably of a
sophisticated contour. It subtends an arcuate portion of the
circumference of bulbous element 18, and of the circumference of
fiber optic 22. This arcuate portion is typically less than one
quadrant of 90. The overall aperture 24 is substantially in the
shape of a frustum. The wide base of the frustum is disposed to the
exterior of the bulbous element 18. The truncated apex of the
frustum is abutting the distal end region of the light-transmitting
fiber optic 22 at the position of its beam-splitter means 26.
Because the cross section of aperture 24 is substantially circular,
it may be accurately described as being substantially frustoconical
in shape.
There is a spacing or standoff 35 defined between fiber optic 22
and an outer surface 37 of bulbous element 18 which will be
contacted with the endometrium. This distance 35 is on the order of
the diameter of fiber optic 22, i.e., 1 millimeter.
An enlarged cross-sectional view of the bulbous element taken along
plane 4--4 shown in FIG. 2 is shown in FIG. 4. The axial offset
between the distal head and the proximal shank regions of bulbous
element 18 facilitates maneuvering of the prominent distal head
region of the element 18 into proximity or contact with tissue
while, at a preferred angular orientation of use, the distal shank
region of the element 18 remains more remote from the tissue.
Tissue selective contact with only proximal or distal regions of
bulbous element 18 cannot be totally assured when the device 10 is
used in tight bodily cavities such as the uterus 100 (shown in FIG.
1), but the axial offset to bulbous element 18 promotes that its
distal head region may be selectively placed in contact with the
tissue.
Further, the spacing 35 maintained between the distal end of fiber
optic 22 and the tissue being treated minimizes the disadvantages
mentioned that often result from actual touching of the fiber optic
22 to the endometrium.
An enlarged cross-sectional view of the distal head region of
bulbous element 18 is shown in FIG. 5. The fiber optic 22 includes
a core 40 surrounded by cladding 42. The internal reflection caused
by the cladding 42 is such that the fiber optic 22 has a low
divergence as the light exits the distal end 16. The core 40 is
typically made of glass, e.g., silica quartz. The cladding 42 is
typically made of silicone, plastic or silica. The core 40 and its
cladding 42 have a combined diameter of less than about 0.5
millimeter to about 1.0 millimeter.
To protect the core 40 and its cladding 42, the fiber optic 22
normally also includes an external jacket 46 which surrounds the
cladding 42 and is held in place by a resin coating 44. The
external jacket 46 is usually made of a flexible plastic material
such as poly(ethylene) or poly(tetrafluoroethylene). It provides a
flexible and smooth surface allowing easy manipulation of the
medical device. Fiber optic bundles are not preferred since the
adhesive between individual fibers limits the amount of light which
can be transmitted without melting of the bundle.
The fiber optic 22 should be flexible yet sufficiently resilient so
that it is possible to push the fiber optic along a lumen. One such
suitable fiber optic having a core diameter of 0.4 millimeters is
marketed under the designation Med 400 by Quartz Products
Corporation of Plainfield, N.J. Another suitable fiber optic is a
0.6 millimeter fiber optic commercially available under the
designation HCT 600 from Ensign Bickford Co., Conn. The power that
can be transmitted along fiber optic 22 varies with the size of the
fiber. Utilizing the HCT 600 fiber optic a medical device embodying
this invention can transmit as much as about 60 watts continuous
power from a Nd:YAG laser source.
The bulbous element 18 irradiates both heat and light energy. Part
of the light energy transmitted by fiber optic 22 is partially
absorbed and converted by the element 18 into heat, and part of the
light energy is emitted by the element 18 through aperture 24 as
light. The relative proportions of the light energy that is
radiated as light, or that is radiated and/or conducted as heat,
are determined by the beam-splitter means 26.
The cross-sectional area of core 40 to fiber optic 22 is divided by
the beam-splitter 26 -- essentially a concave notch extending into
the core 40 of the fiber optic 22 at the position of aperture 24 --
into a part that is perpendicular to the axis of fiber optic 22 and
another part that forms an acute angle to such axis. Substantially
all of the light exiting the perpendicular part of fiber optic 22
at its beam-splitter means 26, i.e., exiting axially from fiber
optic 22, is directed forward to be absorbed by the opposed
light-receiving surface of bulbous element 18. The light-receiving
surface of bulbous element 18 that is opposed to the distal end of
fiber optic 22 is preferably treated, e.g., oxidized, in order to
increase its coefficient of emissivity to about 0.95 or greater.
This treatment further increases the absorption of light by the
element 18. Alternatively, the light-receiving surface can be
treated by being coated by a material such as lamp or carbon black
having a high coefficient of emissivity.
The bulbous element 18 is preferably made of metal such as surgical
stainless steel, but could also be made of a combination of
thermally conductive and thermally insulating materials such as
metal(s) and ceramic(s). The exterior surface of the bulbous
element 18 is preferably coated with a non-stick or release surface
such as poly(tetrafluoroethylene) to provide easy release from the
tissue. Poly(tetrafluoroethylene) usually is used for operating
temperatures below about 300 degrees C. The majority of the heat is
generated by absorption of the laser light at the distal end of the
bulbous element 18 where it is typically needed. Meanwhile, heat
generation is minimized at the proximal portions of the element 18
where it could be detrimental to the fiber optic 22.
The bulbous element 18 has sufficient mass to avoid burn-through
during use. However, the mass is not so great as to materially slow
its heating rate. For this reason, it is advantageous to place the
thickest portion of material in the forward portion of the element
18 where the radiant energy, e.g., light, impinges. The space
between the distal end of the fiber optic 22 and the radiant energy
receiving surface of the element 18 may fill with matter such as
air or liquid during use. However, this matter is readily vented
through aperture 24 due to expansion as a result of the heat
generated.
The distal end portion of the bulbous element 18 is preferably
generally rounded on its exterior surface (as illustrated) in order
to facilitate pressing the element into and through softened body
material while minimizing the risk of mechanical perforation. The
bulbous element 18 can alternatively have other shapes as desired,
including oblong or eccentric with respect to the axis of the fiber
optic 22 or even generally crescent shaped. Such an eccentric or
oblong shape can be rotated to generate an even larger channel
through an obstruction. A crescent-shaped element also allows for
viewing past the element.
The distal end of the fiber optic 22 is preferably spaced no more
than two diameters of its core 40 away from the light-receiving
surface of the bulbous element 18. Where the core 40 is about 0.5
millimeters, this spacing should be no more than about 1
millimeter. This relatively close spacing insures that
substantially all of the light emitted from the flat end surface of
fiber optic 22 is received on the forward light-receiving surface
of the bulbous element 18, and is not dispersed on the inside side
walls of the cavity 20 between the distal end surface and the
receiving surface.
Meanwhile, some light is diverted from optic fiber 22 by
beam-splitter means 26 to be directly radiated from bulbous element
18. This radiation is in a direction substantially transverse to
the axis of optic fiber 22. The beam-splitter means 26 is
essentially an indentation or recess upon the fiber optic 22. The
recess extends sufficiently deeply into the fiber core 40, as may
be best observed in FIG. 5, so as to intercept a substantial
portion of the light, and the light energy, which is transmitted
along fiber optic 22 between laser light source 50 (shown in FIG.
1) and the fiber's distal end. The beam-splitter means 26 can be
considered to create a lossy region, or region at which light is
emitted, to the fiber optic 22.
The depth, and lineal extent, of the beam-splitter means 26
influences the total amount of the light energy that is radiated
thereat. Typically, a variably predetermined portion of the light
energy carried within fiber optic 22 may be radiated as light at
the location of the beam-splitter means 26. The remaining light,
and light energy, is transmitted to distal end of the optic fiber
22, radiated at that end, and absorbed by a light absorbent
treatment or coating at the opposed surface of bulbous element 18.
In this manner, the energy balance between localized heating
performed by the element 18 due to emission of light versus local
heating by thermally radiative and/or conductive paths may be
predetermined in a controlled manner.
Alternative embodiments of the present invention, each having a
different beam splitter means are illustrated in FIGS. 6-8. In
particular, FIG. 6 shows a fiber optic 52 positioned within cavity
50 defined by bulbous element 58 and provided with a leveled or
slanted end surface 56 that directs a portion of the transmitted
laser energy outwardly through aperture 54 and at an acute angle to
the major longitudinal axis of fiber optic 52.
Similarly, FIG. 7 shows fiber optic 62 terminating in a unitary
spherical lens 66 that is positioned within bulbous element 68 and
directs a portion of the transmitted laser energy outwardly via
aperture 64.
FIG. 8 illustrates an embodiment where a separate spherical lens 76
is positioned at the very end of fiber optic 72 in cavity 70 of
bulbous element 78 and directs a predetermined portion of the
transmitted energy outwardly through aperture 74 while the
remainder is absorbed by element 78 as heat.
FIGS. 9-11 illustrate embodiments where the beam splitter means is
a fully or partially reflective surface, or mirror, that is
positioned and sized so as to reflect a portion of the energy
emitted from the end of the fiber optic outwardly through the
aperture while the remainder is absorbed as heat. Within FIGS. 9-11
structural elements performing a similar function to elements
previously shown in FIG. 5 generally have the same last two digits
in their reference numerals.
FIG. 9 illustrates an embodiment where the aperture 224 to bulbous
element 228 is substantially in the shape of a trough having an
included angle that is typically a right angle and major surfaces
that intersect at the bottom of cavity 220. The aperture 224 can
alternatively be configured in the shape of a wedge, cone, pyramid,
paraboloid or other surface or body that is relatively wider at the
exterior surface of bulbous element 218 and relatively narrower at
its regions intersecting cavity 220 and fiber optic 240. At least
the wall, or surface, of aperture 224 opposite to the end of fiber
optic 240, and typically the entire surface of aperture 224, is
reflective. The reflective surface 226 is preferably gold (Au),
normally applied by plating. The preferred gold plating is that
commercially available under the designation LASER GOLD (trademark
of Epner Technology, Inc.). This is an ultra-high infrared
reflectance gold coating provided by Epner Technology Incorporated,
25 Division Place, Brooklyn, N.Y. 11222. The preferred gold plating
is reported by its manufacturer to exhibit an absolute spectral
reflectance of better than 40% at 0.5 microns wavelength radiation,
and better than 98% from 1.0 to 12.0 microns wavelength radiation.
The ratio of laser energy radiation R reflected by surface 226 and
directed outwardly from aperture 224 versus the laser energy heat H
absorbed within the bulbous body 218 may accordingly be made high,
which is sometimes especially desired when the radiation energy R
is not focused. The reflective surface 226 may alternatively be
made of silver (Ag), mercury (Hg), or other energy-reflective
materials, and may alternatively be created by gaseous deposition
and other processes as well as by the process of plating.
FIG. 10 illustrates an embodiment where the reflective surface 226
of aperture 324 to bulbous element 318 is not coextensive with the
beam of laser radiation emitted from the end of fiber optic 340.
Instead, the reflective surface intercepts only a portion of the
laser energy radiation emitted from the end of fiber optic 340, and
substantially reflects this intercepted portion through aperture
324 to the exterior of bulbous element 318. A remaining portion of
the laser energy radiation emitted from the end of fiber optic 340
impinges upon a portion of the wall of cavity 324 that is
substantially non-reflective, and is absorbed within the bulbous
element 218 as laser energy generated heat H. The size, location,
and reflectivities of each of the reflective and non-reflective
surfaces of aperture 324 may be adjusted to vary the relative
proportion of laser energy radiation that is reflected through
aperture 324 and that is absorbed as heat within bulbous element
318. The extent of the reflective surface 326, in particular may be
adjusted by selectively masked plating, or by removal of a portion
of the reflective surface, however applied, by mechanical means
such as drilling or grinding. In this context of the selective
adjustment of the extent of reflective surface 326, it should be
understood that FIG. 10 is exemplary only, and that the exact
contours of aperture 324 and the exact patterning and location of
the reflective surface 326 could be subject to considerable
variation depending upon exactly where, how, and to what extent
energy is to be both thermally and radially delivered by medical
devices in accordance with the present invention.
As an example of the considerable adjustment that may be made to
the contours of the aperture, and to a reflective surface within
such aperture that is employed as the beam splitter means, FIG. 11
illustrates an aperture 424 to a bulbous element 418 where a
partially reflective surface 426 within the aperture 424 directs
some of the laser energy radiation received from fiber optic 440 in
a direction outwardly from the tip of bulbous element 418, while
permitting some of this laser energy radiation to be absorbed by
the bulbous element 418 as heat. The direction of laser energy in
an outwardly direction is provided by a reflective surface 426,
normally made of gold. Reflective surface 426 is concavely curved,
typically as a spheroidal, ellipsoidal, or parabolic surface. The
reflective surface can but need not cover the entire aperture 424
defining wall. The concave curvature, and spatial orientation, of
reflective surface 426 around aperture 424 not only causes that the
laser energy is reflected to the exterior of the tip of bulbous
body 418, but that it may be focused to a desired degree as ell.
Both the outwardly direction and the focus, or partial focus, of
laser energy radiation R can be particularly useful when the
medical device in accordance with the invention is moved in a
progression to heat and irradiate material within, or regions of, a
patient's body.
FIG. 12 illustrates still another embodiment of the beam splitter
means. The aperture 524 to bulbous element 518, and its reflective
surface 526 is not coextensive with the entire end of fiber optic
540. The reflective surface 526 is instead oppositely disposed to
but a portion of the area of the end of fiber optic 540, and
intercepts but a portion of the laser energy radiation emitted
therefrom (similarly to the embodiment of FIG. 10). Only this
intercepted portion of the laser energy radiation emitted from the
end of fiber optic 540 impinges on reflective surface 526 and thus
is substantially reflected through aperture 524 to the exterior of
bulbous element 518. A remaining portion impinges directly onto the
bulbous element 518 where it is converted into heat H.
The device in accordance with the present invention permits the
destruction of tissue or matter, such as the endometrium. When the
bulbous element 18 is positioned relatively further or relatively
closer to the tissue surface then the light beam emitted from
aperture 24 will fall upon the tissue surface relatively more or
less diffusely. Since the light beam produced by the bulbous
element 18 is not directed into the tissue surface as a narrow,
collimated beam, any destruction by high-temperature localized
heating with intense light will not continue to transpire as the
bulbous member 18 is retracted ever further away from the work
surface.
In accordance with the present invention, a medical device is used
for radiant heating of material within a patient's body, including
the patient's own tissue, by irradiation with high intensity light.
The light is sufficiently localized and sufficiently intense so as
to cause sufficiently localized sufficiently high radiant heating
of the material upon which the light selectively impinges so as to
destroy such material. In accordance with the preceding discussion,
this destruction will be understood not to transpire uncontrollably
in all regions whereat the aperture distal end of the device is
deployed, but to transpire only selectively along an arc in a
direction that is substantially transverse to the long axis of the
distal end of the device.
Further in accordance with the present invention, a medical device
is used for conductively heating tissue of the patient's body,
typically in regions local to the region(s) of tissue or material
destruction by the high intensity light. This conductive heating
typically occurs by direct thermal contact with an apertured distal
end of the device while this end is heated sufficiently hot so as
to cause localized cauterizing of the patient's bodily tissue with
which it comes into contact. The heated device generally does not,
however, produce heat that is either so localized or so high as
that heat that is produced by the high intensity light radiation
also emitted transversely from the device's distal end.
When the device of the present invention is utilized in an
endometrial ablation procedure as previously discussed, it is
especially useful for treating the portions of the endometrium 117
lining the side wall 121 of the uterus. Although not shown in the
drawings, the optic fiber 22 and bulbous element 18 are inserted
into the uterus by means of a hysteroscope as will be understood by
those skilled in the art. Use of the element 18 will be under
direct visual observation through the hysteroscope. The bulbous
element 18 will be placed in contact with the endometrium 117 with
the aperture 24 directed against the wall of the endometrium 117 as
indicated in FIG. 1. The bulbous element 18 will then be slowly
moved in a continuous motion so as to direct the heat energy
therefrom across the entire portion of the endometrium lining the
side wall 121.
The endometrium, when suitably prepared for this procedure, will
have a thickness of approximately three millimeters. The laser
energy exiting the aperture 24 and directed immediately against the
endometrium has the ability to penetrate approximately five
millimeters, thus penetrating the entire thickness of the
endometrium through to the underlying muscle layers. Additionally,
the somewhat greater area of less intense heating provided by
conductive heating from the bulbous element 18 due to its contact
with the endometrium 117 surrounds the localized area of heating
provided through the aperture 24. It is the combined heating effect
of both the laser energy exiting aperture 24 and the heat conducted
from the heated mass of bulbous element 18 which destroys the
endometrium.
Typically, the tissue of the endometrium is not vaporized, but
instead is heated to an extent that it is completely penetrated by
the high temperatures and is thus entirely destroyed or killed.
After treatment, the endometrial tissue typically is reduced to a
scar tissue on the myometrial or muscle layer of the uterine
cavity.
Also, it is noted that on occasion an actively bleeding vessel will
be encountered in this procedure. In such instances, it is
sometimes preferable to rotate bulbous element 18 and contact the
bleeding vessel with a back surface thereof to cauterize the vessel
without applying direct laser energy.
The terms "laser energy" and "laser radiation" and "laser light" as
used in this specification disclosure will be understood to
encompass a broad range of radiation frequencies, characteristics,
and energy densities. In particular, the device in accordance with
the present invention will function satisfactorily with laser
radiation of a broad frequency range of infrared (IR) and visible
light. The laser radiation may be suitably produced by CO.sub.2,
Argon, Nd:YAG, and other types of lasers. Use of a beam splitter
having a reflective surface plated with gold, as is preferred, is
effective to accomplish the heating and radiating purposes of the
invention over a great range of energy frequencies,
characteristics, densities, and levels. For example, the device in
accordance with the present invention is suitable for use with
excimer laser radiation having a wavelength in the order 290-400 nm
and power densities, pulse rates, and application times sufficient
to cause multiphoton absorption and band breaking by coulomb
repulsion rather than thermal destruction.
In accordance with the preceding discussion, further adaptations
and variations of the present invention will be readily perceived
by a practitioner of the medical instrumentation arts. The size,
aspect ratio, and contours of the bulbous element 18 can be
adjusted as besuit the bodily cavity within which such member is
employed. The focus of the emitted light can be varied in a
sophisticated manner by incorporation of one or more lenses of
standard design into aperture 24. Heat conduction within the
bulbous element 18 may be varied by making the element out of both
thermally conductive and thermally insulative material. The
operation of that embodiment of the invention which has been taught
in order to (i) produce a single, substantially directionally
transverse, light beam and (ii) heat substantially
omnidirectionally should be understood to be illustrative only, and
not delimiting of the potential combinations of heating by
irradiating with both light and heat that are subsumed within the
present invention.
Therefore, the present invention should be interpreted in
accordance with the language of the following claims, only, and not
solely in accordance with that particular embodiment within which
the invention has been taught.
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