U.S. patent application number 09/816586 was filed with the patent office on 2001-09-13 for method and apparatus for intravascular two-dimensional ultrasonography.
This patent application is currently assigned to Cardiovascular Imaging Systems, Inc. Invention is credited to Yock, Paul G..
Application Number | 20010021811 09/816586 |
Document ID | / |
Family ID | 26966238 |
Filed Date | 2001-09-13 |
United States Patent
Application |
20010021811 |
Kind Code |
A1 |
Yock, Paul G. |
September 13, 2001 |
Method and apparatus for intravascular two-dimensional
ultrasonography
Abstract
A catheter is provided for insertion in the he blood vessel of a
patient for ultrasonically imaging the vessel wall. The catheter
includes a tubular element and an internally housed drive cable for
effective circumferential scan about the catheter of an ultrasonic
generating means. Both the tubular element and the drive cable are
of a size and flexibility sufficient to permit their introduction
into the vessel and subsequent advancement through the vessel to
the location of the vessel wall where imaging is desired.
Inventors: |
Yock, Paul G.;
(Hillsborough, CA) |
Correspondence
Address: |
LYON & LYON LLP
SUITE 4700
633 WEST FIFTH STREET
LOS ANGELES
CA
90071-2066
US
|
Assignee: |
Cardiovascular Imaging Systems,
Inc
1327 Orleans Drive
Sunnyvale
CA
|
Family ID: |
26966238 |
Appl. No.: |
09/816586 |
Filed: |
March 23, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09816586 |
Mar 23, 2001 |
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09300168 |
Apr 27, 1999 |
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6221015 |
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09300168 |
Apr 27, 1999 |
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08911635 |
Aug 15, 1997 |
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5902245 |
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08911635 |
Aug 15, 1997 |
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08467178 |
Jun 6, 1995 |
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5865178 |
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08467178 |
Jun 6, 1995 |
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08162412 |
Dec 3, 1993 |
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5676151 |
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08162412 |
Dec 3, 1993 |
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08014906 |
Feb 1, 1993 |
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5313949 |
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08014906 |
Feb 1, 1993 |
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07826260 |
Jan 24, 1992 |
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07826260 |
Jan 24, 1992 |
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07649048 |
Feb 1, 1991 |
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07649048 |
Feb 1, 1991 |
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07290533 |
Dec 23, 1988 |
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5000185 |
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07290533 |
Dec 23, 1988 |
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06834893 |
Feb 28, 1986 |
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4794931 |
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Current U.S.
Class: |
600/466 ;
600/467 |
Current CPC
Class: |
A61B 2090/3784 20160201;
A61B 5/02007 20130101; A61B 8/4461 20130101; A61B 2017/22045
20130101; A61B 2017/22074 20130101; A61B 8/12 20130101; A61B
2017/22038 20130101; A61B 2017/22052 20130101; A61B 2090/376
20160201; A61B 8/445 20130101; A61B 2017/00924 20130101; A61B
17/320783 20130101; A61B 17/22012 20130101; A61B 2017/22078
20130101 |
Class at
Publication: |
600/466 ;
600/467 |
International
Class: |
A61B 008/14 |
Claims
What is claimed is:
1. A catheter apparatus suitable for imaging the wall of a vessel
in the vascular system of a patient, said catheter apparatus
comprising: an elongate tubular element exhibiting a size and
flexibility sufficient to permit both introduction of said tubular
element into the vessel and subsequent advancement of said tubular
element through the vessel to the location of the vessel wall where
imaging is desired, said tubular element including a proximal
extremity, said tubular element also including a distal extremity,
at least a portion of which is substantially transparent to
ultrasonic energy; ultrasonic energy generating means disposed
within said distal extremity of said tubular element for generating
ultrasonic energy and for propagating the ultrasonic energy so
generated through said energy transparent portion of said distal
extremity toward the wall of the vessel; electrical circuit means
carried by said tubular element and connected to said ultrasonic
generating means for supplying power thereto; and drive means
disposed within said tubular element and connected to said
ultrasonic generating means for rotating said ultrasonic generating
means such that ultrasonic energy therefrom is directed around the
circumference of the vessel wall, said drive means including an
elongate flexible drive cable structure which is fabricated at
least in part from stainless steel, said drive cable structure also
exhibiting a size and flexibility sufficient to permit both
introduction of said tubular element into the vessel and subsequent
advancement of said tubular element through the vessel to the
location of the vessel wall where imaging is desired.
Description
[0001] This is a continuation of copending U.S. application Ser.
No. 09/300,168 filed Apr. 27, 1999, which is a continuation of Ser.
No. 08/911,635 filed Aug. 15, 1997 (now U.S. Pat. No. 5,902,245),
which is a continuation of Ser. No. 08/467,178 filed Jun. 6, 1995
(now U.S. Pat. No. 5,865,178), which is a continuation of U.S.
application Ser. No. 08/162,412, filed Dec. 3, 1993 (now U.S. Pat.
No. 5,676,151), which is a divisional of U.S. application Ser. No.
08/014,906 filed Feb. 1, 1993 (now U.S. Pat. No. 5,313,949), which
is a continuation of U.S. application Ser. No. 07/826,260 filed
Jan. 24, 1992 (now abandoned), which is a continuation of U.S.
application Ser. No. 07/649,048 filed on Feb. 1, 1991 (now
abandoned) which is a continuation of U.S. application Ser. No.
07/290,533, filed on Dec. 23, 1988 (now U.S. Pat. No. 5,000,185),
which is a continuation-in-part of U.S. application Ser. No.
06/834,893, filed Feb. 28, 1986 (now U.S. Pat. No. 4,794,931). The
entire disclosures of all of the aforementioned applications are
incorporated herein by reference. The present application is
related to application Ser. No. 07/290,217, filed on Dec. 23, 1988,
commonly assigned herewith, the disclosure of which is incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] This invention relates to a catheter apparatus, system, and
method for intravascular two-dimensional ultrasonographic imaging,
and more particularly to such an apparatus, system, and method for
guiding and monitoring interventional therapy to reduce vascular
stenosis.
[0003] Ultrasonic two-dimensional imaging apparatus and systems
have heretofore been provided for use in endoscopy for examining
the gastrointestinal tract. Such a device is disclosed in U.S. Pat.
No. 4,494,549. Such devices, however, have been relatively large
and inflexible and are completely unsuitable for use within the
vascular system of the human body. In addition, there is no
provision for guiding such devices into specific branches of blood
vessels.
[0004] There is, therefore, a need for a new and improved catheter
apparatus, systems, and methods which can be utilized for
performing intravascular two-dimensional ultrasonographic imaging.
It would be particularly desirable if such imaging apparatus and
methods could be combined with a variety of intravascular
therapeutic modalities, such as angioplasty atherectomy, laser
ablation, and the like, in order to provide simultaneous imaging
and recanalization procedures.
SUMMARY OF THE INVENTION
[0005] According to the present invention, a method for imaging the
interior of a blood vessel comprises scanning an ultrasonic signal
in a preselected pattern about said interior. By receiving
ultrasonic energy reflected from the interior surface of the
vessel, including any stenosis or occlusion present, an image or
profile of the blood vessel may be produced. Conveniently, the
ultrasonic signal is generated by a transducer located at the
distal end of a vascular catheter comprising a flexible tubular
member. The transducer may be manipulated directly to weep the
ultrasonic signal in a desired pattern, including radial, planar,
and conical. Alternatively, the transducer may be fixed within the
catheter and a reflective surface manipulated to sweep the
ultrasonic signal in a desired pattern. The imaging method of the
present invention is advantageously combined with interventional
therapeutic techniques to reduce vascular stenosis, where the
stenosis may be imagined prior to, during, and after intervention
to help direct the interventional activity to where it will be most
effective.
[0006] In general, it is an object of the present invention to
provide a catheter apparatus, system, and method for intravascular
two-dimensional ultrasonography.
[0007] Another object of the invention is to provide an apparatus,
system, and method of the above character which has a high
resolution capability.
[0008] Another object of the invention is to provide an apparatus,
system, and method of the above character which can be utilized for
assessing endovascular lesions.
[0009] Another object of the invention is to provide an apparatus,
system, and method of the above character which can be utilized for
monitoring the results of interventional therapy.
[0010] Another object of the invention is to provide an apparatus,
system, and method of the above character which can be used with
angioplasty, atherectomy, laser ablation, drug deliver, and similar
vascular interventional methods and devices.
[0011] Another object is to provide an apparatus, system, and
method capable of selective cannulation of branch vessels.
[0012] Additional objects and features of the invention will appear
from the following description in which the preferred embodiments
are set forth in detail in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a side elevational view partially in cross-section
of a catheter apparatus incorporating the present invention.
[0014] FIG. 2 is an enlarged cross-sectional view of the distal
extremity of the apparatus shown in FIG. 1.
[0015] FIG. 2A is a detail view illustrating an alternate mounting
of a crystal transducer to provide a conical sweep pattern.
[0016] FIG. 2B is an alternate embodiment of the distal extremity
of the apparatus shown in FIG. 1, modified to be inserted over a
movable guidewire and with the cutting direction reversed.
[0017] FIG. 3 is an enlarged cross-sectional view of an
intermediate portion of the apparatus shown in FIG. 1.
[0018] FIG. 4 is an enlarged cross-sectional view taken along the
line of 4-4 of FIG. 1.
[0019] FIG. 5 is an isometric view of the crystal assembly which
forms a part of the apparatus shown in FIG. 1.
[0020] FIG. 6 is a schematic block diagram of the electrical and
electronic apparatus utilized in the system.
[0021] FIG. 7 is a two-dimensional display of an ultrasonogram
which can be obtained with the apparatus and system shown in FIGS.
1-6.
[0022] FIG. 8 is an enlarged cross-sectional view of another
embodiment of a catheter apparatus incorporating the present
invention.
[0023] FIG. 9 is a cross-sectional view taken along the liens of
9-9 of FIG. 8.
[0024] FIG. 10 is an enlarged cross-sectional view of still another
embodiment of a catheter apparatus incorporating the present
invention.
[0025] FIG. 10A is a detail view illustrating an alternate
configuration of a reflective surface to provide a conical sweep
pattern.
[0026] FIG. 10B is an alternate embodiment of the distal extremity
of the catheter apparatus of FIG. 10, modified to provide a fixed
ultrasonic transducer located proximally of a reflective surface on
a cutter.
[0027] FIG. 11 is an enlarged cross-sectional view of another
embodiment of the catheter apparatus incorporating the present
invention.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
[0028] In general, the catheter apparatus of the present invention
includes a flexible tubular element which is adapted to be inserted
into a blood vessel in the vascular system and a flexible rotatable
elongate element which is disposed in the tubular element. In a
first embodiment, an ultrasonic transducer is carried at the distal
end of the flexible rotatable elongate element, and electrical
circuitry carried at the distal end of the flexible tubular element
is connected to the ultrasonic transducer for supplying signals to
and receiving signals from the transducer. In a second embodiment,
a reflective surface is carried by the distal end of the flexible
rotatable elongate element, and the ultrasonic transducer is
mounted in the distal tip of the flexible tubular element so that
signals generated by the transducer will be reflected by the
reflective surface. In both embodiments, a transmitter is provided
for supplying signals to the ultrasonic transducer and a receiver
is provided for receiving signals from the ultrasonic transducer. A
motor drive is usually provided for rotating the flexible elongate
element along manual rotation may also be employed. By rotating the
flexible elongate element, the transducer signal can be swept in a
desired pattern, either directly by the transducer in the first
embodiment, or indirectly by the reflective surface in the second
embodiment. Timing and control circuitry is provided for
controlling the operation of the transmitter and receiver and
optionally the motor drive. A display is provided which is operated
under the control of the timing and control circuitry for
displaying he image information that is received by the
receiver.
[0029] The catheters of the present invention may further include
interventional capability for recanalization of occluded regions
within the imaged blood vessel. Recanalization is intended to refer
to both the opening of total occlusions, as well as broadening of
the vessel lumen in partial occlusions. Catheters combining
ultrasonic imaging capability with atherectomy devices for severing
of stenotic material are described in detail hereinafter. The
methods of the present invention, however, are not limited to
atherectomy and include a wide variety of other interventional
techniques that may be performed with vascular catheters. Suitable
interventional techniques include balloon angioplasty, laser
ablation angioplasty, balloon embolectomy, aspiration embolectomy,
heat probe ablation, abrasion, drilling, therapeutic ultrasound,
and the like. Also, the catheters may be adapted for introducing
clot-dissolving drugs, such as tissue plasminogen activator,
streptokinase, urokinase, and the like, in order to reduce the
stenosis, as well as platelet receptor blockers and drugs which
limit cell multiplication in order to inhibit restenosis.
Conveniently, perfusion lumens and ports may be provided in the
catheter to provide for the administration of such drugs.
[0030] A first exemplary construction of a catheter apparatus 11
constructed in accordance with the principles of the present
invention comprises an elongate tubular assembly 12 includes an
elongate flexible tubular element 13 which is provided with four
lumens 14, 16, 17, and 18 with the lumen 14 serving as a torque
tube, lumen 16 serving as a balloon tube, and lumens 17 and 18
serving as infusion tubes or lumens as hereinafter described. The
tubular element 13 may conveniently be formed as a single extrusion
which provides the four lumens, with the lumens 14 and 16 being
substantially circular in cross-section, and the lumens 17 and 18
being arcuate in shape with the configuration of each being
determined by three arcs with one of the arcs being concentric with
the outer diameter of the tubular element 13 and with the two
smaller arcs being concentric with lumens 14 and 16,
respectively.
[0031] A braided shield 21 is provided on the exterior of the
tubular element 13 and takes the form of one or more layers of
braided strands 22 formed of suitable magnetic material, such as an
electrical shield. A cover tube 23 covers the braided shield 21 and
extends the length of the tubular element 13. The cover tube 23 can
be formed of a suitable material such as a heat shrinkable plastic
which is shrunk tightly onto the braided shield 21 and provides a
smooth outer surface so the tubular assembly 12 can readily enter a
vessel of the vascular system of a patient.
[0032] A work performing device such as an atherectomy or cutting
device of the type described in European patent application 163 502
may be provided in the distal extremity of the tubular assembly 12.
A suitable cutting device is described in said European application
and consists of a housing 27 that is provided with a cutout 28. A
rotary cutter 29 is rotatably disposed within the housing 27 and is
provided with a hub 31 that is secured to a flexible rotatable
torque cable 32. The cable 32 is disposed in and extends through
the torque tube lumen 14. The torque cable 32 is formed of a
suitable material such as stainless steel. The housing 27 is
provided with a rounded tip 33 having a recess 34 which is adapted
to receive material which is removed by the rotary cutter 29 as the
cutter 29 is advanced as hereinafter described. A spring tip guide
or guidewire 36 capable of being shaped is secured to the rounded
tip 33 and extends forwardly therefrom and serves to guide or steer
the housing 27 as the tubular assembly 12 with the cutting device
26 secured thereto is introduced into the vessel of the vascular
system of the patient. As shown, the spring tip guide 36 can be
secured to the rounded tip 33 by suitable means, such as solder 37.
It thus can be seen that the guidewire 36 is associated with the
housing 27. Alternatively, a movable guidewire 38 (FIG. 2B) can be
utilized to facilitate steering of the catheter 11 into the desired
vessel of the patient.
[0033] A balloon 41 of an expandable type is optionally secured to
the housing in a region opposite the cutout 28 and has its distal
extremity bonded around the tip 33 by suitable means, such as an
adhesive 42. As shown in FIG. 2, the balloon 41 underlies
substantially the entire length of the housing 27. The balloon 41
is in communication with a balloon tube 43 that extends through the
balloon tube lumen 16 in the tubular element 13. The balloon tube
43 is provided with a lumen 44 through which a medium can be
introduced for inflating the balloon 41 and removed for deflating
the balloon 41. The proximal extremity of the balloon 41 and the
proximal extremity of the housing 27 are secured to the distal
extremity of the tubular assembly 12 by suitable means, such as
heat shrinkable tubing 46.
[0034] A system 49 is provided at the distal end 49 of catheter 11
for imaging the region in which the work performing device is
located, said system usually being a two-dimensional ultrasound
image system. The system 49 includes an ultrasonic transducer, such
as a single crystal 51 (see FIG. 5), which is mounted on the hub 31
and is secured thereto by suitable mans such as an adhesive. The
crystal 51 is part of an assembly 52. The crystal 51 should be
capable of operating at a frequency range of 5 to 50 megahertz and
typically can be formed of a suitable material such as barium
titanate or cinnabar. As can be seen from FIG. 5, the crystal 51
has a rectangular block-like configuration and has two opposed
surfaces covered by metallic conducting films 53 and 54 formed of a
suitable material such as chrome or gold. The material of the films
can be formed of a foil or can be in the form of films evaporated
or sputtered onto the opposite surfaces of the crystal 51. The
films 53 and 54 serve as electrodes and are connected to connecting
wires 56 and 57 by suitable means, such as solder. Means is
provided for damping out the oscillations from the backside of the
crystal 51 and takes the form of a rectangular block 58 formed of a
suitable backing material. The baking material can be formed in a
conventional manner so as to cancel out oscillations from the side
of a crystal in which the backing material is disposed.
[0035] The present invention, however, is not limited to the use of
piezoelectric crystal oscillators as the ultrasonic transducer, and
organic electrets such as polyvinylidene difluoride (PVDF) and
vinylidene fluoride-trifluoroethylene copolymers may also find use.
PVDF is particularly suitable as a transducer at higher
frequencies, typically at or above 40 MHz.
[0036] The wires 56 and 57 are braided onto the torque cable 32 and
rotate with the torque cable. The wires 56 and 57 extend towards
the proximal extremity of the tubular assembly 12 and extend into a
fitting 61 (see FIG. 3) formed of a suitable material such as
plastic. A pair of spaced-apart slip rings 62 and 63 formed of a
conducting material such as copper are secured to the torque cable
32. The wire 56 is bonded to the slip ring 62, and the wire 57 is
bonded to the slip ring 63. A fitting 66 is provided which has a
threaded bore 67. The tubular assembly 12 extends through the
fitting 66 and a reinforcing sleeve 68 extends over the portion of
the tubular assembly 12 extending therethrough. A pair of spring
urged contacts 71 and 72 are carried by the fitting 66 and are
adapted to slidably engage the slip rings 62 and 63. The contacts
71 and 72 are connected to conductors 73 and 74. A grounding lug 76
is provided on the fitting 66 and makes electrical contact with the
braided shield 21. A conductor 77 is connected to the grounding lug
76.
[0037] A male fitting 78 (see FIG. 1) is threaded into the threaded
bore 67. A single arm adapter 81 is mounted in the male fitting 78
and carries an arm 82 having thereon a balloon inflation port 83
that is in communication with the lumen 44 in the balloon tube 43
disposed in the tubular assembly 12. The single arm adapter 81 is
secured to a rotating adapter 86 of a conventional type and through
which the tubular assembly 12 extends. Another single arm adapter
87 is mounted in the rotating adapter and is provided with a side
arm 88 having an infusion port 89 disposed therein which is in
communication with the infusion lumens 17 and 18 provided in the
tubular assembly 12. A tapered fitting 91 is mounted in the single
arm adapter 87 and is provided with a threaded bore 92 which
carries an O-ring 93 that is adapted to be engaged by a male type
fitting 94 to form a liquid-tight seal between the tubular assembly
12 and the torque cable 32 which extends therethrough. The torque
cable 32 is secured to a suitable drive member such as a clutch
member 98 of the type described in European application 163 502 and
U.S. Pat. No. 4,771,774, the disclosures of which are incorporated
herein by reference. The clutch member 98 is adapted to be secured
to a motor drive means of the type described in U.S. Pat. No.
4,771,774 consisting of a motor drive unit which in the present
application is identified as a motor 99 (see FIG. 6). The motor 99
is driven by and is under the control of electronic circuitry
forming a part of system 49. The part of the system 49 shown in
block diagram form is substantially conventional and can be of a
suitable type such as certain equipment identified as Model 851 B
manufactured by Advanced Technology Laboratories, Inc., of Bothel,
Wash. As shown in FIG. 6, such apparatus includes a timing and
control block 102 that supplies pulses to a transmitter 103. The
output of the transmitter 103 is supplied through a transmit
receive switch 104 which supplies the signals on the conductors 73
and 74 through the slip rings 62 and 63 onto the conductors 56 and
57 connected to the crystal 51. During the time that the
transmitter 103 is supplying high frequency energy to the crystal,
the crystal 52 is being rotated by the motor driving the torque
cable 32 with the motor 99 being under the control of the timing
and control block 102. The motor 99 is of a type such as an open
loop stepping motor or a closed loop servo controlled motor which
can be driven by the timing and control block 102.
[0038] As an alternative to the use of an external motor 99
connected to the cutter 29 by torque cable 32, it would be possible
to construct catheters according to the present invention utilizing
micromotors within the distal extremity of the catheter. The
micromotors could be attached to directly rotate the cutter and
transducer (or reflective surface as described hereinafter)
typically by mounting at the end of a nonrotating cable analogous
to torque cable 32.
[0039] The transmitter generates a voltage pulse, typically in the
10 to 50 volt range, for excitation of the transducer crystal 51.
Supplying such voltage pulses to the crystal causes the transducer
to produce sonic waves which emanate therefrom into the surrounding
tissue structure. Portions of the sonic energy wave are reflected
by the tissue structure back to the transducer and the transducer
51 acts as a receiver and picks up the sonic vibrations and
converts them into electrical signals which are supplied by the
conducting wires 56 and 57 back to the slip rings 62 and 63 through
the conductors 73 and 74 and through the transmit receive switch
104 to a receiver 106. These signals are amplified and supplied to
a display unit 107 which includes a CRT screen 108 under the
control of the timing and control block 102 to supply an image 109
on the display 108 which can be of the type shown in FIG. 7. As can
be seen from FIG. 7, as viewed through 360.degree., the vessel wall
111 of the image 109 is shown as indicated, having different cross
sections depending upon the buildup of plaque therein. A central
region 112 of the image is eclipsed because of the imaging
catheter. Alternatively, if desired, only a sector of a lesser
angle than 360.degree. can be viewed.
[0040] The catheter apparatus of the present invention can be
constructed in various sizes. For example, in a 9 French size, the
balloon can have a length of approximately 3 centimeters. Sizes
down to 3 French and below can be accomplished with the
construction of the present invention. These particular dimensions
are exemplary only and not intended to limit the scope of the
present invention in any way.
[0041] Operation and use of the catheter apparatus, system and
method during intravascular ultrasonography can now be briefly
described as follows. Let it be assumed that it is desired to
utilize the apparatus, system and method of the present invention
to remove the atheroma in a blood vessel of a patient. The catheter
of the catheter apparatus of the present invention is introduced
into a vessel of the patient as, for example, into the femoral
artery and introducing the catheter into the artery by the use of
the guidewire 36. The progress of the catheter into the vessel of
the patient can be observed under x-ray fluoroscopy. As soon as the
cutting device has entered into a region which is desired to remove
certain material from the vessel and before a cutting operation is
commenced, the atheroma itself can be viewed by operation of the
ultrasonic imaging system 49. This can be accomplished by operating
the timing control block 102 to cause operation of the motor 99
which in turn causes rotation of the torque cable 32 and the
crystal assembly 52 to scan the interior of the vessel in which the
crystal 51 is disposed, usually at a rotation rate in the range
from about 100 to 20,000 rpm, more usually from about 500 to 2,000
rpm. An image of what is being scanned will appear on the screen
108 of the display device 107. Alternatively, the torque cable 32
may be manually rotated (or aimed without rotation) to provide a
desired image. Generally, however, motorized rotation will provide
a higher definition image. During the time this rotary scanning is
taking place, the cable 32 can be advanced to advance the cutter so
that the entire region in which the material is to be removed can
be scanned. Usually, the cable 32 is advanced incrementally so that
distinct cross-sectional images will be successively produced,
allowing the operator to determine the length and topography of the
region. Alternatively, the entire catheter apparatus 11 may be
axially advanced or retracted within the blood vessel lumen to
provide a plurality of cross-sectional images to allow assessment
of the entire length of the atheroma.
[0042] After the scan, the cable 32 can be retracted slightly (or
the catheter 11 repositioned) so that the proximal extremity of the
cutout 28 lies at the proximal extremity of the atheroma In order
to stabilize the cutting device, the balloon 41 can be inflated so
as to urge the cutout 28 of the housing 27 towards the portion of
the atheroma it is desired to remove. The motor 99 can then be
energized to rotate the cutter 29. As the cutter 29 is rotated, it
can be advanced to progressively remove the material which is
disposed within the cutout 28 of the housing 27. As this material
is removed it is pushed forwardly and eventually moves into the
recess 34. The balloon 41 can then be deflated and the catheter
apparatus removed from the vessel after which the material which
has been deposited in the recess 34 can be removed and the cutting
device cleaned for reinsertion into the vessel of the patient for
removal of additional material from the vessel if required.
[0043] During the time that the cutting operation is taking place,
the cutting operation can be viewed ultrasonically by the rotating
crystal 51 that places an image on the screen 108. From this image
it can be ascertained how well the cutter is performing in removing
the material and whether or not an additional pass of the cutter is
required. It should be appreciated that, if necessary, several
passes of the cutter can be made and, if necessary, the catheter
assembly can be removed from the vessel of the patient to clean out
material which has been removed and deposited in a recess 34.
[0044] As illustrated in FIG. 2, the ultrasonic transducer 51 is
oriented to direct the ultrasonic signal in a direction
substantially radially outward relative to the axis of the flexible
tubular element 13. It will sometimes be desirable, however, to
incline the ultrasonic transducer relative to the tubular axis, as
illustrated at 51' in FIG. 2A. By inclining the transducer 51', the
ultrasonic signal is directed at a forward angle .alpha. relative
to the tubular axis. By rotating the inclined transducer 51', the
ultrasonic signal will sweep a conical pattern directed forward of
said transducer. The angle .alpha. may be in the range from about
10.degree. to 85.degree., usually being in the range from
20.degree. to 60.degree.. Scanning with a conical sweep is
desirable because it can provide forward viewing at or in front of
the location where the cut is being made.
[0045] An alternate embodiment 11' of catheter 11 is illustrated in
FIG. 2B. The catheter 11' is similar to that of catheter 11, except
that it is modified to permit insertion of the catheter 11' over a
movable guidewire 38 and the cutter 29' is reversed to provide
cutting when the cutter is translated in the proximal (rearward)
direction. The modifications include providing a penetration 39 in
the distal tip of housing 27 and an axially aligned penetration 40
in the cutter 29'. The ultrasonic transducer 52' is mounted on the
distal end of cutter 29', and torque cable 32' includes an axial
lumen. In this way, the catheter 11' is inserted by conventional
techniques over guidewire 38, with the guidewire passing through
penetrations 39 and 40 and the lumen of torque cable 32'.
[0046] Another embodiment of the catheter apparatus of the present
invention is shown in FIGS. 8 and 9. Many of the parts are very
similar to the parts utilized in the embodiment of the invention
shown in FIG. 1 and have been given the corresponding numerals. The
ultrasonic transducer 52 is mounted in a cavity 53 formed to the
rear of the rotary cutter 29. The distal extremity of the catheter
apparatus shown in FIG. 8, (i.e., to the left) differs from the
apparatus shown in FIG. 1 in that the conducting wires or leads
connected to the ultrasonic crystal 52 are connected to the outside
world at a point which is proximal of an adapter 122 whereas in the
embodiment shown in FIG. 1, the connectors are connected at a point
which is distal of the adapters 82 and 88. Thus, there is shown an
adapter 122 which is provided with an arm 123 through which dye
injection and pressure measurements can be made and another fitting
124 which can be utilized in inflating and deflating the balloon
41. Another adapter 126 is provided which is threaded into the
proximal end of the adapter 122 and forms a sealing engagement with
an O-ring 127 carried by the adapter 122. The torque cable 32
extends through the adapter 126 and is connected to a clutch member
128. The clutch member 128 which carries a finger operated member
129 is adapted to be secured to motorized drive means of the type
hereinbefore described for causing rotation of the torque cable
32.
[0047] As hereinbefore explained, the conducting wires connected to
the ultrasonic transducer 52 are braided into the guidewire 32.
Means is carried by the adapter 126 which is adapted to make
contact with the conducting wires connected to the crystal 52 and
consists of brushes 131 and 132 which are yieldably urged by
springs 133 towards the torque cable 32 so as to make contact with
the conducting wires or leads carried by guidewire 32. The springs
133 are held in place by pins 134 which are frictionally seated
within the adapter 126. Conducting wires 136 and 137 are connected
to the pins 134. These wires 136 and 137 are connected into the
system in a manner hereinbefore described with the previous
embodiments. The operation of this embodiment is very similar to
that described in conjunction with the operation of the embodiment
shown in FIG. 1.
[0048] Operation of this embodiment of the invention is very
similar to that hereinbefore described with the principal advantage
being that leads which are connected to the crystal and for
receiving signals from the crystal are disposed proximally of the
two arm adapter 122.
[0049] As a modification of catheter 121, cutter 29 could be
provided with an abrasive external surface, either in place of or
in addition to the forward cutting edge. Such an abrasive surface
would be useful to remove atheroma and plaque by contact
abrasion.
[0050] Still another embodiment 151 of the catheter apparatus of
the present invention is shown in FIG. 10. Certain parts of this
catheter apparatus 151 are very similar to those hereinbefore
described and are identified by the same numbers. Thus there has
been provided a housing 27 which has an outwardly facing cutout 28.
A coil spring guide wire 36 is secured to the distal extremity of
the housing 27 as shown (although the catheter 151 could easily be
adapted to receive a movable guidewire as described above in
connection with the embodiment of FIGS. 1-4). The balloon 41 is
carried by the housing and has its distal extremity secured to the
housing by a band 92. The balloon 41 is disposed outside of the
housing 27 on the side opposite the cutout 28. A flexible tubular
assembly 154 is secured to the proximal end of the housing 27. A
three-arm adapter 152 is mounted on the proximal extremity of the
tubular assembly 154. The tubular assembly 154 comprises a flexible
tubular element formed of a suitable material, such as plastic
which is provided with a balloon inflation lumen 155 that is in
communication with the interior of the balloon 41 and extends into
a balloon inflation port 156 provided as a part of the three-arm
adapter 152.
[0051] A crystal 157 is carried by the housing 27 in a stationary
position. As shown, the crystal 157 is mounted vertically or in a
direction that is at right angles to the longitudinal axis of the
housing 27. It can be mounted in the distal extremity of the
housing 27 in a suitable manner such as by an adhesive. A suitable
sound absorbing material 158 is provided behind the ultrasonic
crystal 157 and fills the space between the crystal 157 and the
distal extremity of the housing 27. A pair of conducting wires 161
are connected to the ultrasonic crystal 157 and extend rearwardly
through the housing 27 and are connected into sockets 162 provided
in a side arm 163 forming a part of the adapter 152.
[0052] The flexible tubular element 154 is provided with a large
lumen 164 extending the length thereof and which has a rotatable
flexible drive cable 166 disposed therein. The flexible torque
cable 166 is formed in the manner hereinbefore described and is
secured to a generally cylindrical member 167 which as hereinafter
described, serves as a reflector mount and also serves to carry a
rear-facing rotary cutter 169. Thus, as shown, the member 167 is
provided with a reflective surface 168 which is inclined at an
angle of approximately 45.degree. and faces the transducer 157 in
such a manner so that sound waves propagated by the transducer
impinge upon the surface 168 and are propagated outwardly in a
direction substantially transverse, i.e., at right angles, to the
longitudinal axis of the housing 27. A circular cutting edge 169 is
provided on the member 167 at the proximal extremity thereof. A
truncated conical recess 171 is provided in the proximal extremity
of the member 167. The conical recess 171 can be used as a
reservoir for collecting material as it is severed by the circular
cutting edge 169.
[0053] The angle of inclination of the reflective surface 168
relative to the axis of housing 27 may be varied, particularly
being increased, as illustrated in FIG. 10A, where angle .beta. may
be in the range from 10.degree. to 85.degree., usually being in the
range from 10.degree. to 40.degree.. By inclining the reflective
surface by an angle .beta. less than 45.degree., the reflected
ultrasonic signal will sweep in a rearward conical pattern which
allows viewing at or in front of, (i.e., to the right in FIG. 10),
the cutting edge 169 of member 167.
[0054] The three-arm adapter 152 is provided with another arm 173
which serves as an infusion port and which is in communication with
the lumen 164 through which the drive cable 166 extends. This lumen
164 opens into the interior of the housing 27 and is in
communication with the cutout 28. Another adapter 176 is threaded
into the proximal extremity of the adapter 162 and engages an
O-ring 177. The drive cable 166 extends through the adapter 176 and
has its distal extremity secured to the clutch member 128. As
hereinbefore explained, the clutch member 128 can be secured to a
motorized drive means (or may be manually rotated) for causing
rotational movement of the cutter and mirror member 167.
[0055] An alternate embodiment 151' of catheter 151 is illustrated
in FIG. 10B. The catheter employs a fixed ultrasonic transducer
157', but cutter 169' is reversed to provide for forward cutting.
Forward cutting is often advantageous in that severed stenotic
material is less likely to become entangled with the torque cable
166'. Ultrasonic transducer 157' will be provided with a central
penetration to allow passage of the torque cable 166', and said
transducer will be located at the proximal end of housing 27', but
otherwise the construction of catheter 151' will be the same as
catheter 151.
[0056] In a further modification, it is possible to secure the
ultrasonic transducer 157' onto the torque cable 166'. Wires
connecting the transducer 157' to the external receiver and
transmitter would then be attached to the torque cable 166' and
coupled to the outside in a manner similar to that illustrated in
FIGS. 1-4. The transducer 157' would then translate axially in
tandem with the cutter 169' and the mirror 168'. By maintaining a
fixed distance between the cutter 169' and transducer 157', signal
processing to produce an image is simplified.
[0057] Operation of the catheter apparatus 151 shown in FIG. 10 may
now be described as follows. The operation of this device in many
respects is very similar to that hereinbefore described with
respect to the placement of the catheter in the vessel. The housing
27 can be positioned in the stenosis hereinbefore described and
ultrasonic imaging can be carried out by supplying pulses of
electrical energy to the ultrasonic transducer 157 which emanates
ultrasonic energy and directs the same onto the reflector 168 which
reflects the ultrasonic energy up into the tissue surrounding the
housing. Rotation of the mirror 168 causes an image to be formed
that can be viewed in the manner hereinbefore described. This
imaging can be carried out by rotating the cable 166 and at the
same time advancing the drive cable 166 throughout the length of
the cutout 28 to view the stenosis. After the viewing operation has
been accomplished and it is ascertained that it is desirable to
remove the material creating the stenosis by use of the work
performing device in the form of the cutter member 167, the cutter
member 167 can be advanced to the distal extremity of the cutout
28. With the cutout 28 in the proper location, the balloon 41 can
then be inflated through the balloon inflation port 156 to urge the
housing 27 in a direction so that the stenosis enters the cutout.
As soon as this has been accomplished, the cutter member 157 can be
rotated at a high rate of speed and gradually retracted, (i.e.,
translated to the right in FIG. 10), to cause the material forming
the stenosis to be severed by the blade 169 on cutter member 167
and collected within the recess 1 71. This cutting and collecting
operation can be continued until the cutter member 167 has been
advanced to the extreme proximal position. At this time, the
catheter apparatus 151 can be removed and the tissue collected
within the recess 171 can be removed. Thereafter, additional
insertions of the catheter apparatus can be made and the same
cutting operations performed until desired amount of material has
been removed from the area of the stenosis to provide for increased
blood flow through the vessel.
[0058] Another embodiment of a catheter apparatus 180 incorporating
the present invention is shown in FIG. 11. The catheter apparatus
180 is utilized solely for imaging purposes and employs a fixed
ultrasonic transducer 182 which transmits its signal against a
rotating reflective surface 204. The catheter apparatus 180 is
constructed very similar to the catheter apparatus 151 shown in
FIG. 10 with the exception that the cutting mechanism has been
eliminated. The use of such a catheter apparatus 180 is desirable
where it is unnecessary to provide a cutting function (or other
interventional treatment modality). The catheter apparatus 180 also
has many parts that are similar to the catheter apparatuses
heretofore described. Thus there is provided a housing 27 which
carries on its distal extremity a coil spring guide 36. As before,
however, the catheter 180 can also be adapted to be inserted over a
movable guidewire within the scope of the present invention. The
ultrasonic transducer 182 is provided in the distal extremity of
the housing 27 and is disposed vertically or in a direction that is
perpendicular to the longitudinal axis of the housing. A sound
absorbing backing material 183 is provided in the distal extremity
of the housing behind the transducer 182. Conducting wires or leads
184 are connected to the transducer 182. The proximal extremity of
the housing 27 is connected to the distal extremity of flexible
elongate tubular element 186 that is connected to a two-arm adapter
187. The leads 184 extend through the tubular element 186 and are
connected to sockets 188 provided in the arm 189 of the two-arm
adapter 187. The tubular element 186 is provided with a large lumen
191 that carries the drive cable 192. The drive cable 192 is
connected to a clutch member 193 of the type hereinbefore described
which is adapted to be driven by motive means in the manner
hereinbefore described. The clutch member 193 is provided with a
flange 194 that cooperates with a flange 196 on the adapter 187.
The adapter 187 carries an O-ring 197 seated against another flange
198 forming a part of the adapter 187. The O-ring 197 forms a
liquid-tight seal with respect to the drive cable 192. The clutch
member 193 is thus held in a fixed longitudinal position while
still permitting rotation of the same. The adapter 187 is provided
with a tapered surface 199 adapted to fit into a motor drive means.
Alternatively, the clutch member 193 can be adapted for manual
rotation. Alternatively, the clutch member 193 can be adapted for
manual rotation.
[0059] The drive cable 192 has its distal extremity secured to a
rotating member 203 which is provided with an inclined reflective
surface 204 which serves as a reflector for reflecting ultrasonic
energy generated by the transducer 182 in a transverse direction
relative to the longitudinal axis of the housing 27. The angle of
inclination of surface 204 may vary, typically between 45.degree.
and 85.degree. provide for forward viewing as described above,
depending on the sweep geometry desired. As illustrated, the torque
cable 192 is unable to axially translate within the lumen 191.
Thus, the reflective surface 204 on rotating member 203 remains in
a fixed longitudinal position relative to the housing 27 and cannot
be advanced or retracted with respect to the ultrasonic transducer
182. The reflective surface 204 can, of course, be axially
translated within a blood vessel by movement of the catheter 180 as
a whole. Also, the catheter 180 could be modified to permit axial
translation of the rotating member 203 within the housing 27 (in a
manner similar to the previous catheter embodiments), but generally
this will be unnecessary.
[0060] The large lumen 191 in flexible elongate tubular element 186
is in communication with a side arm port 206 that forms a part of
the two-arm adapter 187. The housing 27 should be formed of a
material that causes minimal attenuation of the ultrasonic signal
which is transmitted and received by transducer 182. Suitable
materials include polyethylene, silicone rubber, polyvinyl
chloride, polyurethanes, polyesters, natural rubbers, and the like.
Alternatively, the housing may be formed of acoustically opaque
materials if a cutout 207 (shown by the dashed lines) is provided
through which the ultrasonic energy can pass.
[0061] The operation of the catheter apparatus 180 shown in FIG. 11
is very similar to that hereinbefore described with the exception
that the cutting operation is omitted. With this catheter
apparatus, the device can be inserted in the same manner as with
respect to the other devices hereinbefore described. When the
device is in the desired location, as for example, in the stenosis,
the stenosis can be imaged ultrasonically by causing the rotating
member 203 to be rotated with respect to the crystal 182 to cause
ultrasonic energy to be directed upwardly and outwardly through the
housing 181 to impinge upon the sidewalls of the vessel in which
the catheter apparatus 180 is positioned. If a different
longitudinal position is desired to be scanned, the entire catheter
apparatus 181 can be shifted longitudinally in the vessel to the
desired location. After the ultrasonic imaging has been completed,
the catheter apparatus 180 can be removed and other operations
performed if desired with other instruments.
[0062] It should be appreciated that if desired, another embodiment
of catheter apparatus used solely for imaging can be provided by
mounting the crystal at the end of the torque cable as illustrated
in FIG. 8 so that the crystal is rotated about an axis parallel to
the longitudinal axis of the housing.
[0063] From the foregoing, it can be seen that a two-dimensional
ultrasound image is generated by rotating a crystal or a mirror
that is located at the tip of the catheter. Good resolution is
obtained because of the relatively high frequency, i.e., 5 to 50
megahertz, that is used. The image that is created is generally
perpendicular to the longitudinal axis of the catheter, but may
also be in a forward conical pattern, depending on the precise
geometry of the transducer and/or mirror. The motor or manual drive
means that is utilized for rotating the transducer is external to
the patient. Rotation, of the transducer is made possible because
of the electrical connection made with the brush contacts. The use
of the balloon stabilizes the housing so that the cutting operation
can be readily accomplished.
[0064] The apparatus and system of the present invention makes it
possible to obtain images in very small vessels and has made it
possible to accomplish the same by utilizing the precision driving
of a very flexible cable. The catheter apparatus in addition to
being capable of imaging is also capable of being steered by the
flexible guidewire secured to the tip.
[0065] It is apparent from the foregoing that there has been
provided a catheter apparatus, system, and method which is
particularly useful for intravascular two-dimensional
ultrasonography and which can be utilized with many different types
of operations, as for example, in performing atherectomies.
* * * * *