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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a device for diagnosing and
removing obstructions within the lumens of hollow, substantially tubular
structures and more particularly to such a device adapted for use in
diagnosing and removing obstructions in blood vessels.
2. Description of the Prior Art
The debilitating effects of obstructions to the flow of blood in the
cardiovascular system of humans and animals have long been recognized.
Such obstructions can take many forms and arise in many different manners.
For instance, accretion of inorganic and organic materials on the walls of
blood vessels have long been known as a cause of an overall reduction in
the cross-sectional area of the lumen of the vessel with a consequent
diminishing effect on the rate of blood flow therethrough. Further, a
number of pathologies have been identified as the cause of intravascular
occlusions and partial obstructions, such as atheromas and the like.
While some such obstructions respond favorably to medicinal or chemical
treatment, either to effect a dilation of the vessel or a chemically
induced erosion or to induce the breaking up or dissolution of the
material obstructing the blood vessel, it has long been known that such
chemical applications have limited utility and are restricted to use in a
rather insubstantial portion of pathological environments, particularly
those involving tissue growth across the lumen or bore of a blood vessel.
Various apparatuses have been proposed which are adapted for use in
physically intervening within the vascular cavity to remove the
obstruction. For example, it has been proposed to employ laser generating
or similar apparatuses to cause a disintegration of the obstruction of the
blood vessel. While some such apparatuses are useful for their intended
purposes, it has long been known that associated devices and methods for
permitting the visualization of the pathological tissue during and prior
to the attempted removal thereof have been largely deficient and
unsatisfactory in one or more respects, such as the inability accurately
to gauge the dimensions of the obstruction before and during the
performance of the removal technique for which the therapeutic apparatus
is intended to be used. The use of the various visualization methods and
devices heretofore proposed often necessitates the interruption of blood
flow through the vessel being treated, or require interruption of the
treatment period for substantial periods of time, in order that the
remaining portions of the obstruction can be visualized. Thus, it has been
known that conventional visualization techniques and devices used in
conjunction with known therapeutic tools and apparatuses for the removal
of obstructions often do not permit accurate determinations of obstruction
dimensions during treatment for precise imaging of the progressive
reduction of the obstruction during the treatment, whereby the treatment
can be minimized substantially to that necessary without exceeding safe
levels of treatment.
Therefore, it has long been known that it would be desirable to have an
improved device for visualizing obstructions in the lumens of
cardiovascular vessels and the like and for removing such obstructions.
Further, it has long been known that it would be desirable to have such a
device which can be constructed in a variety of dimensions for use in
removing pathological growths, inorganic accumulations, and other
obstructions to free blood flow in blood vessels of varying sizes with a
precision of imagery and therapeutic application heretofore unattainable.
OBJECTS AND SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved
device for intervening in substantially tubular structures and more
particularly in blood vessels for the removal of obstructions therefrom.
Another object is to provide such a device which is adapted for use in
visualizing the dimensions and contours of obstructions in blood vessels
before, during and after the removal thereof.
Another object is to provide such a device which is adapted to be
selectively operated to image obstructions in blood vessels and to remove
or destroy such obstructions.
Another object is to provide such a device which permits the visualization
of the configuration and dimensions of obstructions in blood vessels
simultaneously with the destruction of such obstructions.
Another object is to provide such a device which is adapted to be used in
visualizing and removing obstructions from blood vessels with minimal or
no interruption of blood flow therethrough.
Another object is to provide such a device which is adapted to be
dimensioned and constructed in a wide variety of sizes and flexibilities
for insertion in blood vessels of differing sizes.
Another object is to provide such a device which is adapted to be
constructed inexpensively to permit the economical disposal of the device
after use thereof to prevent the possible transmission of diseases from
one therapeutic subject to another.
Further objects and advantages are to provide improved elements and
arrangements thereof in an apparatus for the purposes described which is
dependable, economical, durable and fully effective in accomplishing its
intended purposes.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a first form of the device of the present
invention.
FIG. 2 is an enlarged transverse section taken on line 2--2 in FIG. 1.
FIG. 3 is a somewhat enlarged, fragmentary view of the device of FIG. 1
with portions removed to illustrate the arrangement of portions internally
thereof.
FIG. 4 is a somewhat enlarged longitudinal section taken on line 4--4 in
FIG. 1.
FIG. 5 is a somewhat enlarged, fragmentary perspective view of a second
form of the device of the present invention.
FIG. 6 is a fragmentary side elevation of a third form of the device of the
present invention shown schematically linked to sources of ultrasonic and
laser energy.
FIG. 7 is a perspective view of a portion of the device of FIG. 1 shown
deployed in a typical operative environment with the distal end portion
thereof disposed within the lumen of a blood vessel.
FIG. 8 is a schematic depiction of an ultrasound generated image obtained
by the operation of the device of FIG. 1 deployed in an attitude
illustrated in FIG. 7.
FIG. 9 is a perspective, fragmentary view of the device of FIG. 1 shown
deployed in a typical operative environment with the end portion thereof
disposed in proximity to an obstruction within the lumen of a blood
vessel.
FIG. 10 is a schematic depiction of an ultrasonically generated image of
the blood vessel and the obstruction therein obtained by the operation of
the device of FIG. 1 in the operative attitude illustrated in FIG. 9.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring more particularly to the drawings, the device embodying the
principles of the present invention is designated generally by the numeral
10 in FIGS. 1 and 3. As shown therein, the device 10 generally provides a
catheter or housing 12 having a first or proximal end portion 15; an
opposite, second or distal end portion 18 having an endmost edge or tip
19; and an elongated, intermediate portion 20 extending between the distal
end portion and proximal end portion. As shown in FIG. 3, portions of the
distal end portion 18 and the intermediate portion 20 have been removed
for purposes of illustration. While the device finds application in a wide
variety of operative environments, it has particular utility for
intravascular intervention and, accordingly, reference is made herein to
such use of the device, although it is understood that neither the device
nor its operation are to be limited to such environments.
The housing 12 provides a wall 24 having an exterior surface 26 and an
interior surface 28. Preferably, the wall 24 is constructed of a
substantially flexible, electrically-insulating material. As can best be
seen in FIG. 2, the wall 24 preferably has a substantially circular,
cross-sectional configuration of predetermined diameter whereby the distal
end portion 18 and intermediate portion 20 of the housing 12 have
predetermined dimensions. If necessary for use in a particular operative
environment, the distal end portion and intermediate portion can be
tapered distally to provide a progressively lesser outside diameter from
the proximal end portion to the distal end portion. It will be recognized
that the diameters of the portions of the wall 24 will largely depend upon
the particular application for which the device is intended to be used.
For instance, it will be understood that if the device 10 is to be used
for removing obstructions in a large artery, the diameter of the wall 24
can be greater than that of the wall of a device 10 intended for use in a
smaller branch artery or vein.
The housing 12 can also be constructed having virtually any desired length
for use in various particular biological environments. Thus, it will be
recognized that the diameter of the wall 24 of the housing 12 of the
device 10 illustrated in FIG. 1, in relation to the length of the housing
as determined by the separation between the proximal end portion 15 and
the distal end portion 18, is a result of illustrative restrictions and it
is understood that the length of the housing 12 in relation to the
diameter of the wall 24, will, in many constructed embodiments of the
present invention, be substantially greater than that illustrated.
The interior surface 28 of the wall 24 bounds a passage or chamber 30
extending substantially completely from the proximal end portion 15 to the
distal end portion 18.
A sleeve 34 is disposed within the chamber 30 and extends from the proximal
end portion 15 incompletely to the distal end portion 18. The sleeve is
dimensioned closely to conform to the interior surface of the wall 24
incompletely circumferentially thereabout. The sleeve is preferably
constructed of electrically-insulating, substantially flexible material.
As can best be seen by reference to FIGS. 1, 2 and 3, the housing 12
provides an elongated, substantially cylindrical conduit or tube 40
extending incompletely longitudinally the length of the housing and
contained in the chamber 30 between the interior surface 28 of the wall 24
and the sleeve 34. Preferably, the tube 40 is constructed of any suitable
substantially flexible material. The tube can be constructed separately
from the materials comprising the wall 24 or, alternatively, can be formed
unitarily with the wall at the time of fabrication thereof. The tube 40
provides an internal passage 42 extending longitudinally therethrough. The
housing 12 provides a port or aperture 44 in the distal end portion 18
thereof communicating through the wall 24 with the passage 42 of the tube
40. The housing 12 further provides a tubular connection member 48
extending from the proximal end portion 15 having a terminous or end 50.
The tubular connection member is disposed in fluid-flow relation to the
tube 40 and the passage 42 thereof. Preferably, the tubular connection
member is constructed of substantially flexible material and is
dimensioned for the insertion of guide wires and the like therein, and,
further, is of sufficient dimensions to permit the flow of blood and other
fluids therethrough. The end 50 of the tubular connection member 48 is
preferably constructed to permit connection thereof to devices or
apparatuses suitable for the measurement of the hemodynamic
characteristics of a vascular system into which the device 10 is inserted.
Further, a guide wire or the like can be inserted through the end 50 and
the tubular connection 48 for introduction into the passage 42 of the tube
40, if desired, to assist the manipulation of the device 10 within a
tubular structure, such as a blood vessel or the like.
As can best be seen in FIGS. 2, 3 and 4, the chamber 30 of the housing 12
contains a fiberoptic bundle 60 comprising a plurality of elongated,
fiberoptic fibers 62 disposed in substantially axially parallel relation
and extending longitudinally within the chamber from the proximal end
portion 15 to the distal end portion 18. The fibers 62 can be constructed
of any suitable conductive material adapted to conduct light from a light
source axially through the fiber and, preferably, the fibers are
constructed of such material which is particularly adapted to conduct
light from a laser-generating source axially therethrough and to emit such
light from the tip 19. Preferably, although not necessarily, the fibers
are round in cross-sectional configuration, as shown in FIG. 2, although
other forms, such as "strip"-type fibers can be used. As can best be seen
in FIGS. 1 and 3, the proximal end portion 15 of the housing 12 provides a
fiberoptic connector portion 65 extending longitudinally therefrom and
having a substantially tubular construction continuous with the housing 12
and the chamber 30 thereof. The fiberoptic bundle has a proximal end
portion 68 disposed within the proximal end portion 15 of the housing 12
and the fiberoptic connector portion 65, and a distal end portion 70
remote therefrom and disposed within the distal end portion 18 of the
housing 12. Each fiber 62 provides a distal terminus 72, as can best be
seen in FIG. 4. As will be described hereinafter, the selective
application of light from a laser source to one or more of the fibers 62
at the proximal end portion 68 of the fiberoptic bundle 60 will generate a
beam of a predetermined energy level which will be discharged
substantially axially of the terminus 72 of each fiber 62 to which such
laser light is applied. Preferably, although not necessarily, the proximal
end portion 68 of the fiberoptic bundle and the fiberoptic connector
portion 65 are adapted to be connected to an appropriate laser source
which is capable of either simultaneously or sequentially generating laser
energy through one or more fibers 62 to permit the discharge of a
predetermined amount of laser light or energy from the termini of such
fibers for impingement of such laser energy upon a target object of known
size, such as an obstruction within a blood vessel, for the precise
destruction thereof.
As can best be seen in FIGS. 1, 2, 3 and 4, the housing 12 mounts an end
cap or acousto-optic lens 75 on the distal end portion 18 thereof. The
acousto-optic lens is disposed to permit the passage of laser beams
emitted from the termini 72 of the fibers 62 therethrough and operates to
focus the beams at a predetermined focal point distally external of the
housing a predetermined distance. Preferably, the focused beam will have
predetermined transverse dimensions depending upon the number and spacing
of the optic fibers utilized to transmit the beam. Preferably, the lens 75
is constructed of a material suitable to permit both laser beams and
ultrasonic waves to pass therethrough. Optionally, if an acousto-optic
lens is not used, the termini 72 of the fibers 62 can be arranged or
shaped in a suitable manner or configuration to permit efficient focusing
of the laser beam in order to maximize the efficiency and precise
application of the beam in an operative environment. Focusing and steering
can also be achieved, or further optimized, by utilizing the equipment
used to generate the laser beams in a "phase array" manner.
As is discussed more fully below, the fibers 62 in the distal end portion
70 of the fiberoptic bundle 60 are preferably spaced a predetermined
distance from adjacent fibers. It is understood that arrangement of the
fibers shown in FIG. 2 is illustrative only and can be varied
substantially within the scope of the present invention, although it will
be appreciated that the spacing of the fibers is critical if steering of
the laser beams is desired.
Upon reference to FIGS. 3 and 4, it will be seen that the housing 12
provides a block of sound-absorbing material or lossy backing 80 within
the chamber 30 in the distal end portion 18 thereof. The lossy backing
should have an acoustic impedance substantially similar to that of the
piezoelectric material described hereafter effectively to dissipate the
ultrasonic waves and to prevent the production of an image of the lossy
backing when the waves echoed therefrom inpinge upon the piezoelectric
material. The optical fibers 62 are extended through the lossy backing and
are individually substantially completely circumscribed by the portions
thereof. Preferably, the lossy backing is constructed of a sound-absorbent
material to permit the travel of ultrasonic waves toward the distal end
portion 18 within the chamber 30, as is described in greater detail below,
and to reduce the travel of waves toward the proximal end portion 15. The
lossy backing further serves the purpose of dissipating any ultrasonic
waves generated which travel toward the proximal end portion, thus
reducing interference. The lossy backing also provides a dampening effect
on the excited piezoelectric material to prevent continued generation of
waves thereby which might otherwise create artifacts. Such dampening is
essential in order to permit the piezoelectric material to attain a ready
state for the reception of echoed ultrasonic waves. Preferably, the lossy
backing 80 is dimensioned substantially completely to occlude the chamber
30 at its point of deployment. Alternatively, or additionally, each fiber
62 can be coated with a sound-absorbing material along its length from the
proximal end portion 68 incompletely longitudinally toward the distal end
portion 70, leaving a portion of the distal end portion uncoated.
A selected number of fibers 62 of the fiberoptic bundle 60 are coated
substantially completely from the lossy backing 80 to the terminus 72
thereof with a suitable material having high piezoelectric properties
whereby, upon the application of electrical energy thereto, ultrasonic
waves of a predetermined range of wavelengths will be generated by
activation or excitation of the piezoelectric material and whereby, upon
impingement of ultrasonic waves or energy upon the piezoelectric material,
electrical impulses will be generated. For instance, polyvinylidine
difluoride is exemplary of the materials from which the piezoelectric
material can be selected. Of course, any other suitable material having
high piezoelectric properties can be employed for this purpose. Further,
preferably the coated fibers are spaced from each other a distance equal
to or less than one half the anticipated wavelength of the ultrasonic
waves generated by the excitation thereof, whereby artifacts in the
resultant ultrasonic image are minimized. An alternative to coating the
fibers would be the use of optic fibers constructed of material having
high piezoelectric properties. Optionally, the fibers can be coated
substantially over their entire lengths with the material.
As can best be seen in FIGS. 2, 3, and 4, the housing 12 further provides
an electrode bundle 85 having a plurality of electrical conductors or
electrodes 87 extending longitudinally within the chamber 30 from the
proximal end portion 15 toward the distal end portion 18. The electrodes
87 are elongated, electrically-conductive strands disposed in close
proximity to each other within an electrically-insulating sheath 90
disposed intermediate the sleeve 34 and interior surface 28 of the wall 24
substantially diametrically opposite the tube 40. Preferably, each
electrode 87 is individually electrically insulated from adjacent
electrodes. Each electrode provides a distal end portion 93 connected on
the piezoelectric coating of an individual fiber 62 intermediate the lossy
backing 80 and the terminus 72 of the fiber, whereby application of
electrical energy to the electrode will conduct an electrical charge to
the piezoelectric material. The electrically-stimulated piezoelectric
material then emits ultrasonic waves which travel axially of the housing,
preferably providing a scanning angle in the range of from about 30 to 45
degrees. Each electrode 87 further provides a proximal end portion
extended from the proximal end portion 15 of the housing 12 bundled with
the proximal end portions of the other electrodes 87 within an electrode
connection member 97 of substantially tubular configuration, constructed
preferably of an electrically-insulating material. The electrode
connection member 97 provides a terminus 99 adapted to be connected to
means for generating electrical impulses and for receiving electrical
impulses conducted through the proximal end portions of the electrodes 87
for analysis thereof, as is described in greater detail below.
The distal end portion 18 of the housing 12 mounts an annular marker
element 101 of metal or other suitable construction capable of
visualization by fluoroscopy or similar means whereby the approximate
location of the distal end portion within a blood vessel can be determined
during the operation of the device 10.
The proximal end portion 15 of the housing 12 mounts a substantially
cylindrical protective ring 103 disposed in circumferentially
close-fitting relation thereon. Preferably, the ring 103 is of rigid metal
or plastic construction to permit manual manipulation thereof during the
operation of the device 10 and to prevent damage to the housing 12,
fiberoptic bundle 60, or electrode bundle 85 by compression or squeezing
thereof.
An alternative construction of the device 10 of the present invention is
illustrated in FIG. 5 in a fragmentary, partially cut-away view. The
alternative form of the device illustrated therein is substantially
identical in all respects to the device 10 illustrated in FIGS. 1, 2, 3
and 4, excepting that the lossy backing 80 is disposed in the proximal end
portion 15 of the housing in close circumscribing relation to the fibers
62 on the proximal end portions 68 thereof. Thus, a greater length of each
fiber 62 having piezoelectric material coated thereon is coated with such
material. The device 10 shown in FIG. 5 is adapted to be constructed
having a gradually tapering outside diameter with a minimum diameter at
the distal end portion 18 for use in smaller blood vessels. Preferably,
the inner surface of the sleeve 34 is coated with an appropriate
sound-absorbent material to minimize any possible "ringing" effect.
A second alternative construction of the device 10 of the present invention
is illustrated in FIG. 6 and is similarly adapted for operative deployment
in small vessels. As shown therein, the fiberoptic connector portion 65
and the electrode connection member 97 are detached from the housing 12
and are incorporated in an acousto-optic coupling member 105. The
acousto-optic coupling member houses a transducer element comprising a
plurality of electrodes and a region of piezoelectric material adapted to
be excited by the application of electrical energy thereto by the
electrodes. The acousto-optic coupling member is adapted to be connected
on the proximal end portion 15 of the housing 12 to serve as a link
between a source of electrical energy 109 and the transducer element
therein, and between a source of laser energy 112 and the fibers 62 of the
fiberoptic bundle 60. When so connected, excitation of the piezoelectric
material in the acousto-optic coupling member will generate ultrasonic
waves directed axially within the housing.
The forms of the device 10 of the present invention illustrated in FIGS. 1
through 6 are each adapted for operation in similar operative
environments, such as those illustrated in FIGS. 7 and 9. As shown in FIG.
7, the distal end portion 18 is inserted within the lumen 115 of a blood
vessel 117 having a branched vessel 119 intersecting therewith, the
branched vessel having a lumen 121 communicating with the lumen 115. The
range of transmission of ultrasonic waves from the device 10 is
illustrated in FIG. 7 in dashed lines 125.
In FIG. 9, the device 10 is shown deployed in a typical operative
environment in a blood vessel 130, such as an artery or the like having a
lumen 132 partially occluded by an obstruction 134 attached to or
protruding from the vessel 130 transversely into the lumen 132.
FIG. 8 is a substantially schematic illustration of an ultrasonic image 140
generated by the operation of the device 10 in the typical operative
environment illustrated in FIG. 7. The checked or cross-hatched portions
142 represent substantially solid matter, such as the vessel 117 and
surrounding tissues. The dashed lines 145 illustrate the boundaries of the
image generated. The ultrasonic image 140, illustrated in FIG. 8,
indicates a lack of obstructions within the vessel 117.
In FIG. 10, an ultrasonic image 140 is schematically depicted to represent
the image generated by the operation of the device 10 in the operative
environment illustrated in FIG. 9. The checked or cross-hatched portion
142 again represents substantially solid material with the remainder of
the image bounded by the dashed lines 145 indicating unobstructed,
substantially non-solid material or areas. The obstruction 134 is depicted
as a lobed image 148.
OPERATION
The operation of the described embodiment of the subject invention is
believed apparent and is briefly summarized at this point. Although the
device 10 of the present invention is useful in a wide variety of
operative environments, it finds particular utility in the removal of
obstructions in blood vessels and the like and, therefore, the description
of the operation of the device herein is made with particular reference to
such application.
In preparing the device 10 for the imaging and removal of an obstruction
from a blood vessel, such as is illustrated in FIG. 9, the device must
first be connected to a source or sources of laser energy and electrical
energy. Preferably, the source of electrical energy utilized is
incorporated within an apparatus (not shown) having the capability of
generating electrical impulses and converting and analyzing electrical
impulses received thereby to produce an image, such as that schematically
depicted in FIG. 10. Preferably, such a source of electrical energy, or
analysis unit, is adapted to be connected in electrically-conductive
relationship to the electrodes 87 to energize a selected number of such
electrodes for exciting the piezoelectric material on a desired number of
fibers 62 and further to apply electrical impulses to such fibers in a
variety of manners, such as by a "phase array" method or simultaneously,
as required by the particular operative environment. It is preferable that
the electrical source be adapted to be applied to the electrodes to
activate the piezoelectric material to cause the material to emit
ultrasound having a frequency in the range of from about 5 MHz to 10 MHz.
A lower frequency will not permit optimum resolution, and a higher
frequency might result in undesirable or excessive heat generation in
tissues impacted by the ultrasonic waves. Additionally, the analysis unit
should be capable of interpreting electrical impulses generated by the
piezoelectric material upon contact of the material by ultrasonic waves
echoed from solid structures within the vessel lumen and transmitted to
the analysis unit by the electrodes, in any well known manner utilizing
conventional analysis apparati, or utilizing processing equipment designed
especially for use with the device of the present invention.
The fiberoptic bundle 60 must also be connected to a source of laser energy
adapted to conduct laser beams individually into and axially through the
fibers 62. For this purpose, a laser source should be selected having the
capacity to be connected to the fiberoptic connector portion 65
selectively and individually to transmit a laser beam through the
fiberoptic connector portion and into a selected number of fibers. The
fibers can be activated individually or simultaneously in a group of a
selected number of such fibers. Further, the fibers can be activated
sequentially, if so desired. Of course, the ability to pump the laser and,
hence, the fibers sequentially would depend on the efficiency of the laser
source. Preferably, the laser source has a variable power output capacity
to each unit for adjustment thereof to meet the desired | | |
