U.S. patent application number 14/301500 was filed with the patent office on 2014-10-30 for medical systems and related methods.
The applicant listed for this patent is Cybersonics, Inc.. Invention is credited to Bradley A. Hare, Robert Rabiner.
Application Number | 20140324066 14/301500 |
Document ID | / |
Family ID | 34435330 |
Filed Date | 2014-10-30 |
United States Patent
Application |
20140324066 |
Kind Code |
A1 |
Rabiner; Robert ; et
al. |
October 30, 2014 |
MEDICAL SYSTEMS AND RELATED METHODS
Abstract
A medical system includes a sheath and an acoustic reflective
element that is capable of amplifying acoustic energy. Methods of
using a medical system are also provided herein.
Inventors: |
Rabiner; Robert; (North
Reading, MA) ; Hare; Bradley A.; (Chelmsford,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cybersonics, Inc. |
Erie |
PA |
US |
|
|
Family ID: |
34435330 |
Appl. No.: |
14/301500 |
Filed: |
June 11, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11750829 |
May 18, 2007 |
8790359 |
|
|
14301500 |
|
|
|
|
10665445 |
Sep 19, 2003 |
|
|
|
11750829 |
|
|
|
|
09776015 |
Feb 2, 2001 |
6652547 |
|
|
10665445 |
|
|
|
|
09618352 |
Jul 19, 2000 |
6551337 |
|
|
09776015 |
|
|
|
|
60178901 |
Jan 28, 2000 |
|
|
|
60157824 |
Oct 5, 1999 |
|
|
|
Current U.S.
Class: |
606/128 |
Current CPC
Class: |
A61N 7/022 20130101;
A61B 2017/00274 20130101; A61B 2017/22051 20130101; A61B 2017/32007
20170801; A61B 17/22012 20130101; A61B 2017/320084 20130101; A61B
2217/007 20130101; A61B 2017/00778 20130101; A61B 2017/00137
20130101; A61B 2017/22018 20130101; A61B 2217/005 20130101; A61M
1/0084 20130101; A61B 2017/22007 20130101; A61B 2018/00982
20130101; A61B 2018/00547 20130101; A61B 2017/22081 20130101; A61B
2017/22028 20130101; A61B 2017/22015 20130101; A61B 2017/22008
20130101; A61B 2017/320089 20170801; A61B 17/22004 20130101 |
Class at
Publication: |
606/128 |
International
Class: |
A61B 17/22 20060101
A61B017/22 |
Claims
1. A medical system for removal of occlusions in blood vessels, the
medical system comprising: a sheath substantially surrounding an
ultrasonic probe, the sheath defining a lumen; an ultrasonic probe
having a proximal probe end and a distal probe end, the ultrasonic
probe having a plurality of nodes and a plurality of anti-nodes of
transverse motion configured to provide transverse vibration; and
an acoustic reflective element at least partially disposed within
and secured to the lumen, the acoustic reflective element being
configured to facilitate amplification of acoustic energy emitted
by the ultrasonic probe.
2. The medical system of claim 1, wherein the acoustic reflective
element comprises a planar surface.
3. The medical system of claim 4, wherein: the sheath defines a
fenestration; and the planar surface of the acoustic reflective
element is configured to redirect acoustic energy emitted by the
ultrasonic probe through the fenestration.
4. The medical system of claim 1, wherein: the sheath defines a
fenestration; and the acoustic reflective element comprises a
plurality of planar surfaces configured to redirect acoustic energy
emitted by the ultrasonic probe through the fenestration.
5. The medical system of claim 1, wherein the sheath comprises a
distal end that comprises a surface configured to retain tissue
proximate to the ultrasonic probe.
6. A medical system for removal of occlusions in blood vessels, the
medical system comprising: an ultrasonic probe having a proximal
probe end and a distal probe end, the ultrasonic probe having a
plurality of nodes and a plurality of anti-nodes of transverse
motion configured to provide transverse vibration; a sheath
defining a lumen configured to receive and substantially surround
the ultrasonic probe therein; and an acoustic reflective element
secured to and disposed at least partially within the lumen of the
sheath, the acoustic reflective element being configured to amplify
acoustic energy emitted by the ultrasonic probe.
7. The medical system of claim 6, wherein the acoustic reflective
element comprises a planar surface.
8. The medical system of claim 7, wherein: the sheath defines a
fenestration; and the planar surface of the acoustic reflective
element is configured to redirect acoustic energy emitted by the
ultrasonic probe through the fenestration.
9. The medical system of claim 6, wherein: the sheath defines a
fenestration; and the acoustic reflective element comprises a
plurality of planar surfaces configured to redirect acoustic energy
emitted by the ultrasonic probe through the fenestration.
10. A method comprising: emitting acoustic energy within a sheath
disposed within a body vessel of a subject; and after emitting the
acoustic energy within the sheath, amplifying the emitted acoustic
energy and redirecting the emitted acoustic energy through a
fenestration defined by the sheath.
11. The method of claim 10, wherein amplifying the emitted acoustic
energy comprises reflecting the emitted acoustic energy with an
acoustic reflective element.
12. The method of claim 10, wherein redirecting the emitted
acoustic energy through the fenestration comprises reflecting the
emitted acoustic energy with an acoustic reflective element.
13. The method of claim 10, wherein emitting acoustic energy within
the sheath comprises vibrating an ultrasonic probe disposed within
a lumen of the sheath.
14. The method of claim 13, wherein the ultrasonic probe is
vibrated in a transverse direction.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
11/750,829, filed is a continuation of application Ser. No.
10/665,445, now abandoned, filed Sep. 19, 2003, which is a
continuation of application Ser. No. 09/776,015, filed Feb. 2,
2001, now U.S. Pat. No. 6,652,547, which is a continuation-in-part
of application Ser. No. 09/618,352, filed Jul. 19, 2000, now U.S.
Pat. No. 6,551,337, which claims the benefit of Provisional
Application Ser. No. 60/178,901, filed Jan. 28, 2000, and claims
the benefit of Provisional Application Ser. No. 60/157,824, filed
Oct. 5, 1999, the entirety of all these applications are hereby
incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates generally to medical systems
and related methods.
BACKGROUND
[0003] Vascular occlusions (clots or thrombi and occlusional
deposits, such as calcium, fatty deposits, or plaque), result in
the restriction or blockage of blood flow in the vessels in which
they occur. Occlusions result in oxygen deprivation ("ischemia") of
tissues supplied by these blood vessels. Prolonged ischemia results
in permanent damage of tissues which can lead to myocardial
infarction, stroke, or death. Targets for occlusion include
coronary arteries, peripheral arteries and other blood vessels. The
disruption of an occlusion or thrombolysis can be effected by
pharmacological agents and/or or mechanical means. However, many
thrombolytic drugs are associated with side effects such as severe
bleeding which can result in cerebral hemorrhage. Mechanical
methods of thrombolysis include balloon angioplasty, which can
result in ruptures in a blood vessel, and is generally limited to
larger blood vessels. Scarring of vessels is common, which may lead
to the formation of a secondary occlusion (a process known as
restenosis). Another common problem is secondary vasoconstriction
(classic recoil), a process by which spasms or abrupt closure of
the vessel occurs. These problems are common in treatments
employing interventional devices. In traditional angioplasty, for
instance, a balloon catheter is inserted into the occlusion, and
through the application of hydraulic forces in the range of ten to
fourteen atmospheres of pressure, the balloon is inflated. The
non-compressible balloon applies this significant force to compress
and flatten the occlusion, thereby operating the vessel for blood
flow. However, these extreme forces result in the application of
extreme stresses to the vessel, potentially rupturing the vessel,
or weakening it thereby increasing the chance of post-operative
aneurysm, or creating vasoconstrictive or restenotic conditions. In
addition, the particulate matter isn't removed, rather it is just
compressed. Other mechanical devices that drill through and attempt
to remove an occlusion have also been used, and create the same
danger of physical damage to blood vessels.
[0004] Ultrasonic probes are devices which use ultrasonic energy to
fragment body tissue (see, e.g., U.S. Pat. No. 5,112,300; U.S. Pat.
No. 5,180,363; U.S. Pat. No. 4,989,583; U.S. Pat. No. 4,931,047;
U.S. Pat. No. 4,922,902; and U.S. Pat. No. 3,805,787) and have been
used in many surgical procedures. The use of ultrasonic energy has
been proposed both to mechanically disrupt clots, and to enhance
the intravascular delivery of drugs to clot formations (see, e.g.,
U.S. Pat. No. 5,725,494; U.S. Pat. No. 5,728,062; and U.S. Pat. No.
5,735,811). Ultrasonic devices used for vascular treatments
typically comprise an extracorporeal transducer coupled to a solid
metal wire which is then threaded through the blood vessel and
placed in contact with the occlusion (see, U.S. Pat. No.
5,269,297). In some cases, the transducer is delivered to the site
of the clot, the transducer comprising a bendable plate (see, U.S.
Pat. No. 5,931,805).
[0005] The ultrasonic energy produced by an ultrasonic probe is in
the form of very intense, high frequency sound vibrations which
result in powerful chemical and physical reactions in the water
molecules within a body tissue or surrounding fluids in proximity
to the probe. These reactions ultimately result in a process called
"cavitation," which can be thought of as a form of cold (i.e.,
non-thermal) boiling of the water in the body tissue, such that
microscopic bubbles are rapidly created and destroyed in the water
creating cavities in their wake. As surrounding water molecules
rush in to fill the cavity created by collapsed bubbles, they
collide with each other with great force. This process is called
cavitation and results in shock waves running outward from the
collapsed bubbles which can wear away or destroy material such as
surrounding tissue in the vicinity of the probe.
[0006] Some ultrasonic probes include a mechanism for irrigating an
area where the ultrasonic treatment is being performed (e.g., a
body cavity or lumen) to wash tissue debris from the area.
Mechanisms used for irrigation or aspiration described in the art
are generally structured such that they increase the overall
cross-sectional profile of the probe, by including inner and outer
concentric lumens within the probe to provide irrigation and
aspiration channels. In addition to making the probe more invasive,
prior art probes also maintain a strict orientation of the
aspiration and the irrigation mechanism, such that the inner and
outer lumens for irrigation and aspiration remain in a fixed
position relative to one another, which is generally closely
adjacent the area of treatment. Thus, the irrigation lumen does not
extend beyond the suction lumen (i.e., there is no movement of the
lumens relative to one another) and any aspiration is limited to
picking up fluid and/or tissue remnants within the defined distance
between the two lumens.
[0007] Another drawback of existing ultrasonic medical probes is
that they typically remove tissue slowly in comparison to
instruments which excise tissue by mechanical cutting. Part of the
reason for this is that most existing ultrasonic devices rely on a
longitudinal vibration of the tip of the probe for their
tissue-disrupting effects. Because the tip of the probe is vibrated
in a direction in line with the longitudinal axis of the probe, a
tissue-destroying effect is only generated at the tip of the probe.
One solution that has been proposed is to vibrate the tip of the
probe in a transverse direction--i.e. perpendicular to the
longitudinal axis of the probe, in addition to vibrating the tip in
the longitudinal direction. For example, U.S. Pat. No. 4,961,424 to
Kubota, et al. discloses an ultrasonic treatment device which
produces both a longitudinal and transverse motion at the tip of
the probe. The Kubota, et al. device, however, still relies solely
on the tip of the probe to act as a working surface. Thus, while
destruction of tissue in proximity to the tip of the probe is more
efficient, tissue destruction is still predominantly limited to the
area in the immediate vicinity at the tip of the probe. U.S. Pat.
No. 4,504,264 to Kelman discloses an ultrasonic treatment device
which improves the speed of ultrasonic tissue removal by
oscillating the tip of the probe in addition to relying on
longitudinal vibrations. Although tissue destruction at the tip of
the device is more efficient, the tissue destroying effect of the
probe is still limited to the tip of the probe.
[0008] There is a need in the art for improved devices, systems,
and methods, for treating vascular diseases, particularly stenotic
diseases which occlude the coronary and other arteries. In
particular, there is a need for methods and devices for enhancing
the performance of angioplasty procedures, where the ability to
introduce an angioplasty catheter through a wholly or partly
obstructed blood vessel lumen can be improved. There is also a need
for mechanisms and methods that decrease the likelihood of
subsequent clot formation and restenosis.
SUMMARY
[0009] The invention is directed to a method and an apparatus for
removing occlusions in a blood vessel. The invention has particular
application in removal of occlusions in saphenous vein grafts used
in coronary bypass procedures, restoring these grafts to patency
without damaging anastomosing blood vessels. The method according
to the invention comprises inserting a probe member comprising a
longitudinal axis into a vessel, positioning the member in
proximity to the occlusion, and providing ultrasonic energy to the
member. The device is designed to have a small cross-sectional
profile, which also allows the probe to flex along its length,
thereby allowing it to be used in a minimally-invasive manner. The
probe, because it vibrates transversely, generates a plurality of
cavitation anti-nodes along the longitudinal axis of the member,
thereby efficiently destroying the occlusion. A significant feature
of the invention is the retrograde movement of debris, e.g., away
from the tip of the probe, resulting from the transversely
generated energy. Probes of the present invention are described in
the Applicant's co-pending provisional applications U.S. Ser. No.
60/178,901 and 60/225,060 which further describe the design
parameters from an ultrasonic probe operating in a transverse mode
and the use of such a probe to remodel tissues. The entirety of
these applications are herein incorporated by reference.
[0010] In one aspect, the invention relates to one or more sheaths
which can be adapted to the probe tip, thereby providing a means of
containing, focusing, and transmitting energy generated along the
length of the probe to one or more defined locations. Sheaths for
use with an ultrasonic medical device are described in the
Applicant's co-pending utility application U.S. Ser. No.
09/618,352, now U.S. Pat. No. 6,551,337, the entirety of which is
hereby incorporated by reference. The sheaths of the present
invention also provide the user with a means of protecting regions
of tissue from physical contact with the probe tip. In one
embodiment of the invention the sheaths also comprise a means for
aspiration and irrigation of the region of probe activity. In
another embodiment of the invention, a plurality of sheaths are
used in combination to provide another level of precision control
over the direction of cavitation energy to a tissue in the vicinity
of the probe. In one embodiment of the invention, the sheath
encloses a means of introducing fluid into the site of the
procedure, and a means of aspirating fluid and tissue debris from
the site of the procedure. In a further embodiment, the probe tip
can be moved within the sheath. In yet another embodiment, the
irrigation and aspiration means, and the probe tip, can all be
manipulated and repositioned relative to one another within the
sheath. In another embodiment, the sheath is shaped in such a way
that it may capture or grasp sections of tissue which can be
ablated with the probe. In yet another embodiment, the sheath
provides a guide for the probe tip, protecting tissues from
accidental puncture by the sharp, narrow diameter tip or from
destruction by energy emitted radially from the probe during
introduction of the probe to the site. The sheath may be applied to
the probe tip prior to insertion of the probe into the patient, or
the sheath can be inserted into the patient prior to the insertion
of the probe. The sheath of the present invention can be used to
fix the location of one or more shapes relative to the nodes or
anti-nodes of a probe acting in transverse action. The location of
the reflective shapes can amplify the acoustical wave thereby
magnifying the energy. This allows for the use of very small
diameter probes which themselves would not have the requisite
structural integrity to apply and translate acoustical energy into
sufficient mechanical energy to enable ablation of tissues. The
reflective shapes can also focus or redirect the energy,
effectively converting a transverse probe emitting cavitation
energy along its length, to a directed, side fire ultrasonic
device.
[0011] In another embodiment, the probe, which may or may not
contain a probe sheath, is used in conjunction with an expandable
balloon dilatation catheter, providing a means of resolving the
occlusion without imparting stress, or inflicting stress injury to
a vessel. The balloon catheter acts as a carrier means for guiding
the probe wire to the desired site, and acts as a means to position
the wire within the lumen of the vessel. With the balloon inserted
within the confines of an occlusion, inflation of the balloon
provides a means of continuous contact with the potentially
irregularly shaped vessel lumen. Introduction of ultrasonic energy
into the balloon by the transversely vibrating probe wire thereby
results in uniform communication of energy to the regions of the
occluded vessel in contact with the balloon. Since the balloon is
inflated too much lower pressures than in traditional balloon
angioplasty procedure, neither the occlusion nor the vessel is
compressed, thereby eliminating the problems of stress injury to
the vessel. Likewise, as the ultrasound energy fragments the
occlusion, the vessel is cleared of the problematic material,
rather than simply compressing it into the vessel.
[0012] In one embodiment of the invention, a light transmitting
element in inserted into the blood vessel along with, or after, the
probe (with or without probe sheath) and balloon catheter. The
light transmitting element is transmits optical data about the
occlusion. In another embodiment of the invention, the probe/sheath
and balloon catheter is used with such medical devices, such as a
stent, stent graft, trocar, or other such intravascular devices.
The invention is particularly useful in clearing occlusions within
stents or other such devices where compression is undesirable or
not warranted.
[0013] In another aspect of the invention, the probe, with or
without a probe sheath, and with or without the balloon catheter,
may be provided in a sharps container, in the form of a kit. A
sharps container of the present invention is the subject of the
Applicant's co-pending utility application U.S. Ser. No.
09/775,908, now U.S. Pat. No. 6,527,115, the entirety of which is
hereby incorporated by reference. In yet another embodiment, the
kit provides instructions, for example, instructions for assembling
and tuning the probe, and the appropriate frequency range for the
medical procedure. The kit may further comprise packaging whereby
the probe, sheath, and balloon catheter are pre-sterilized, and
sealed against environmental contaminants. In another embodiment,
the container complies with regulations governing the storage,
handling, and disposal of sharp medical devices, and used medical
devices such as a sheath or balloon catheter.
DESCRIPTION OF THE DRAWINGS
[0014] In the drawings, like reference characters generally refer
to the same parts throughout the different views. Also, the
drawings are not necessarily to scale, emphasis instead generally
being placed upon illustrating the principles of the invention.
[0015] In one embodiment, as shown in FIG. 1, the transverse mode
ultrasonic medical device 1 comprises an elongated probe 6 which is
coupled to a device providing a source or generation means for the
production of ultrasonic energy (shown in phantom in the Figure as
66). The probe 6 transmits ultrasonic energy received from the
generator along its length. The probe is capable of engaging the
ultrasonic generator at one terminus with sufficient restraint to
form an acoustical mass, that can propagate the ultrasonic energy
provided by the generator. The other terminus of the probe
comprises a tip 22, which has a small diameter enabling the tip to
flex along its longitude. In one embodiment of the invention, the
probe diameter decreases at defined intervals 14, 18, 20, and 22.
Energy from the generator is transmitted along the length of the
probe, causing the probe to vibrate. In this embodiment, one of the
probe intervals 18 has at least one groove 45.
[0016] FIG. 2 shows an embodiment of the invention wherein the
probe 6 is substantially contained within a cylindrical sheath 121
capable of modulating the energy omitted by an active probe, and
shielding tissues from puncture from a sharp probe tip. The sheath
121 shown in this illustration has been modified such that one of
the terminal ends of the sheath is substantially open, defining a
fenestration or aperture 111, which exposes the probe tip 22 and
23. The terminus of the sheath 129 is shaped to provide a means for
manipulating tissue to bring it into proximity with the probe 22
and 23. Also shown in this embodiment is a second cylindrical
sheath 108 which surrounds a portion of the first sheath 121, and
can be manipulated longitudinally along the first sheath to provide
a means for modulating the exposure of the probe tip 22 and 23, and
thereby modulating the cavitation energy emitted by the probe to
which the tissues will be exposed. The container of the present
invention is capable of receiving and containing the probe or probe
and sheath assembly.
[0017] FIGS. 3a-f show dampening sheaths for an ultrasonic probe
according to embodiments of the invention. FIG. 3a shows a
transverse mode probe according to one embodiment of the invention
comprising the semi-cylindrical sheath 107 and a second sheath 108.
In this embodiment, the second sheath is cylindrical, and is
capable of containing the first sheath 107, as well as the probe
6.
[0018] FIG. 3b shows another embodiment of the invention wherein
the sheath 121 comprises a cylindrical structure of a sufficient
diameter to contain the probe 6, visible for the purpose of
illustration. The sheath 121 comprises at least one fenestration
111, which allows the cavitation energy emitted from the probe tip
to be communicated to an area outside the sheath, otherwise the
energy is contained by the sheath.
[0019] FIG. 3c shows an embodiment of the present invention wherein
the hollow cylindrical sheath 121 has a plurality of arcuate
fenestrations 111.
[0020] FIG. 3d shows an embodiment of the present invention wherein
the probe 6 is contained within a sheath 121 which comprises a
plurality of arcuate fenestrations 111, and at least one acoustic
reflective element 122, which is adapted to the interior surface of
the sheath.
[0021] FIG. 3e shows an embodiment of the present invention
comprising a sheath 121 further comprising two semi-cylindrical
halves 109, each half connected to the other by one or more
connecting means 113. The probe 6 is capable of being substantially
contained within the sheath. The cavitation energy generated by the
probe tip 22 is contained by the semi-cylindrical halves 109,
wherein they occlude the probe tip.
[0022] FIG. 3f shows an embodiment of the present invention wherein
the sheath further comprises at least two cylinders 104, each
cylinder connected to the other by at least one connecting means
113. The probe 6 is capable of being substantially contained within
the sheath. The cavitation energy generated by the probe tip 22 is
contained by the cylinders 104, where they occlude the probe
tip.
[0023] FIG. 4 shows a longitudinal cross-section of a portion of an
ultrasonic probe tip 22 and 23 according to one embodiment of the
invention, comprising a central irrigation passage 17 and lateral
irrigation lumens 19, as well as external aspiration channels
60.
[0024] FIG. 5 shows a transverse cross-section of a portion of the
ultrasonic probe shown in FIG. 4. In this embodiment, the probe 6
comprises a plurality of arcuate channels 60 that extend over the
longitudinal length of the probe tip, providing a space for
irrigation and or aspiration of tissue debris and fluid.
[0025] FIG. 6a shows an embodiment of the invention wherein the
probe tip 22 and 23 are substantially contained within a sheath.
The sheath comprises a fenestration 111 allowing communication of
the cavitation energy emitted by the probe to the outside of the
sheath. The interior of the sheath further comprises reflective
elements 118, shown as a plurality of planar surfaces that extend
from the interior wall of the sheath into the lumen, thereby
providing a means for focusing and redirecting cavitation energy
omitted by the probe tip. In this embodiment, the terminus of the
sheath 129 is shaped to provide a tissue manipulation means also
illustrated in FIG. 5. FIG. 6b shows a similar embodiment, wherein
the reflective elements 118 are arcuate, and the sheath further
comprises a plurality of fenestrations 111.
[0026] FIGS. 7a, 7b, and 7c show the ultrasonic medical device
comprising an ultrasonic probe for removal of an occlusion "0" from
a blood vessel "By". FIG. 7a shows a portion of the probe 22 guided
to the site of, and through the occlusion, using ultrasonic energy
to fragment occlusion materials and clear a path through the
occlusion. FIG. 7b shows the occlusion within the blood vessel
partially removed by action of the probe. FIG. 7c shows complete
removal of the occlusion as occlusion materials are degraded by the
energy transmitted by the probe 22 of the ultrasonic medical
device.
[0027] FIGS. 8a, 8b, and 8c show the ultrasonic medical device
comprising an ultrasonic probe and a sheath assembly for
selectively ablating an occlusion "0" from a blood vessel "BV".
FIG. 8a shows a sheath assembly consisting of a sheath 108 adapted
to a portion of the probe 22. The probe is positioned proximally to
the site of, and through the occlusion, using ultrasonic energy to
fragment occlusion materials and clear a path through the
occlusion, while the sheath protects non-occluded areas of the
blood vessel by partially shielding the probe. FIG. 8b shows the
occlusion within the blood vessel partially removed by action of
the probe, while the sheath is retracted to maintain exposure of
the probe at occlusion site as it is moved through the site. FIG.
8c shows complete removal of the occlusion, as occlusion materials
are degraded by the energy transmitted by the probe 22 of the
device, while non-occluded areas of the blood vessel remain
protected from the action of the probe.
[0028] FIGS. 9a, 9b, and 9c show the ultrasonic medical device used
in conjunction with a balloon catheter for removal of an occlusion
"0" from a blood vessel "By". FIG. 9a shows a deflated balloon
catheter 91 adapted to a portion of a probe 22. The probe guides
the catheter to the site of, and through the occlusion, using
ultrasonic energy to clear path through the occlusion if necessary.
FIG. 9b shows the deflated balloon catheter 91 positioned within
the vessel lumen at the site of the occlusion. FIG. 9c shows an
activated ultrasonic medical device wherein the expanded balloon
catheter engages the occlusion, maintaining contact with the
occlusion as it is degraded by the energy transmitted through the
balloon.
[0029] FIGS. 10a and 10b show the ultrasonic medical device used in
conjunction with a series of sheaths and a balloon catheter 91. In
FIG. 10a, the invention of the present embodiment comprises a probe
22 with a terminal end 23, substantially contained within a first
sheath 107 of which the end distal to the probe tip 23, is shown
cut away from illustrative purposes. The balloon catheter is
adapted to an inflation means (not shown), which may also comprise
a means for monitoring and compensating for pressure fluctuation in
the interior of the balloon. The probe and first sheath is
substantially contained within a second sheath 121, further
comprising a series of fenestrations 111 along its longitude. The
balloon catheter 91, shown substantially deflated, surrounds the
second sheath along part of its length. In this embodiment, the
probe tip 23 is exposed to the vessel lumen and can provide a means
for clearing a path through an occlusion for the introduction of a
balloon catheter. In FIG. 10b, the probe 22 and 23 is withdrawn
such that the tip 23 is contained within the sheath 121. The first
sheath 107 is retracted, by for example, articulation wires,
thereby exposing the probe 22 to the lumen of the second sheath
121. Activation of the probe results in the transverse generation
of cavitation energy along the probe at multiple anti-nodes. The
energy is communicated from the probe to the lumen of the balloon
catheter through the fenestrations 111 in the second sheath 121.
The energy can penetrate the walls of the balloon for direct
communication to the occlusion.
DETAILED DESCRIPTION
[0030] The following terms and definitions are used herein:
[0031] "Anti-node" as used herein refers to a region of maximum
energy emitted by an ultrasonic probe on or proximal to a position
along the probe.
[0032] "Cavitation" as used herein refers to shock waves produced
by ultrasonic vibration, wherein the vibration creates a plurality
of microscopic bubbles which rapidly collapse, resulting in
molecular collision by water molecules which collide with force
thereby producing the shock waves.
[0033] "Fenestration" as used herein refers to an aperture, window,
opening, hole, or space.
[0034] "Node" as used herein refers to a region of minimum energy
emitted by an ultrasonic probe on or proximal to a position along
the probe.
[0035] "Probe" as used herein refers to a device capable of being
adapted to an ultrasonic generator means, which is capable of
propagating the energy emitted by the ultrasonic generator means
along its length, and is capable of acoustic impedance
transformation of ultrasound energy to mechanical energy.
[0036] "Sharps" as used herein refers to an elongated medical
instrument with a small diameter, for example, less than 2 mm. A
"Sharps Container" as used herein is a container capable of
retaining a sharp medical device or the sharp portion thereof, such
that a handler is not exposed to the sharp portion of the
device.
[0037] "Sheath" as used herein refers to a device for covering,
encasing, or shielding in whole or in part, a probe or portion
thereof connected to an ultrasonic generation means.
[0038] "Tissue" as used herein refers to an aggregation of cells
that is substantially similar in terms of morphology and
functionality.
[0039] "Transverse" as used herein refers to vibration of a probe
at right angles to the axis of a probe. A "transverse wave" as used
herein is a wave propagated along an ultrasonic probe in which the
direction of the disturbance at each point of the medium is
perpendicular to the wave vector.
[0040] "Tuning" as used herein refers to a process of adjusting the
frequency of the ultrasonic generator means to select a frequency
that establishes a standing wave along the length of the probe.
[0041] "Ultrasonic" as used herein refers to a frequency range of
the electromagnetic spectrum above the range of human hearing,
i.e., greater than about 20,000 Hertz up to about 80,000 Hertz.
[0042] The present invention provides an ultrasonic medical device
operating in a transverse mode for removing a vascular occlusion.
Because the device is minimally invasive and articulable, it can be
inserted into narrow, tortuous blood vessels without risking damage
to those vessels. Transverse vibration of the probe in such a
device generates multiple anti-nodes of cavitation energy along the
longitudinal axis of the probe, emanating radially from these
anti-nodes. The occlusion is fragmented to debris approximately of
sub-micron sizes, and the transverse vibration generates a
retrograde flow of debris that carries the debris away from the
probe tip.
[0043] The mode of vibration of the ultrasound probe according to
the invention differs from the axial mode of vibration which is
conventional in the prior art. Rather than vibrating exclusively in
the axial direction, the probe vibrates in a direction transverse
to the axial direction. As a consequence of the transverse
vibration of the probe, the tissue-destroying effects of the device
are not limited to those regions of a tissue coming into contact
with the tip of the probe. Rather, as the probe is positioned in
proximity to an occlusion or other blockage of a blood vessel, the
tissue is removed in all areas adjacent to the multiplicity of
energetic anti-nodes being produced along the entire length of the
probe typically in a region having a radius of up to about 2 min
around the probe. In this way, actual treatment time using the
transverse mode ultrasonic medical device according to the
invention is greatly reduced as compared to methods using prior art
probes.
[0044] The number of anti-nodes occurring along the axial length of
the probe is modulated by changing the frequency of energy supplied
by the ultrasonic generator. The exact frequency, however, is not
critical and an ultrasonic generator run at, for example, 20 kHz is
generally sufficient to create an effective number of tissue
destroying anti-nodes along the axial length of the probe. In
addition, as will be appreciated by those skilled in the art, it is
possible to adjust the dimensions of the probe, including diameter,
length, and distance to the ultrasonic energy generator, in order
to affect the number and spacing of anti-nodes along the probe. The
present invention allows the use of ultrasonic energy to be applied
to tissue selectively, because the probe conducts energy across a
frequency range of from about 20 kHz through about 80 kHz. The
amount of ultrasonic energy to be applied to a particular treatment
site is a function of the amplitude and frequency of vibration of
the probe. In general, the amplitude or throw rate of the energy is
in the range of 150 microns to 250 microns, and the frequency in
the range of 20-80 kHz. In the currently preferred embodiment, the
frequency of ultrasonic energy is from 20,000 Hertz to 35,000
Hertz. Frequencies in this range are specifically destructive of
hydrated (water-laden) tissues and vascular occlusive material,
while substantially ineffective toward high-collagen connective
tissue, or other fibrous tissues such as, for example, vascular
tissues, or skin, or muscle tissues.
[0045] The amount of cavitation energy to be applied to a
particular site requiring treatment is a function of the amplitude
and frequency of vibration of the probe, as well as the
longitudinal length of the probe tip, the proximity of the tip to a
tissue, and the degree to which the probe tip is exposed to the
tissues. Control over this last variable can be effectuated through
the sheaths of the present invention.
[0046] Sheath materials useful for the present invention include
may material with acoustical or vibrational dampening properties
capable of absorbing, containing, or dissipating the cavitation
energy emitted by the probe tip. Such materials must be capable of
being sterilized by, for example, gamma irradiation or ethylene
oxide gas (ETO), without losing their structural integrity. Such
materials include but are not limited to, plastics such as
polytetrafluoroethylene (PTFE), polyethylene, polypropylene,
silicon, ultem, or other such plastics that can be used for medical
procedures. Ceramic materials can also be used, and have the added
benefit that they may be sterilized by autoclaving. Combinations of
the aforementioned materials can be used depending on the
procedure, for example as in the sheath of FIG. 5, a ceramic sheath
121 can be used in combination with a moveable PTFE outer sheath
108. Alternatively a single sheath may employ two or more materials
to give the desired combination of strength and flexibility, for
example, the sheath may comprise a rigid ceramic section distal to
the probe tip 23 and a more flexible plastic section proximal to
the tip, capable of flexing with the probe 22. In the currently
preferred embodiment of the invention, PTFE is used to fabricate a
strong, flexible, disposable sheath that is easily sterilized by
irradiation or ETO gas.
[0047] The length and diameter of the sheath used in a particular
operation will depend on the selection of the probe, the degree to
which the probe length will be inserted into the subject, and the
degree of shielding that is required. For example, in an
application whereby vascular occlusive material is removed with the
ultrasonic probe of the present invention, from a vessel deep
inside the body of a patient, the sheath must be of a sufficient
length to protect the vascular tissue from the surgical insertion
point to the site of the operation, of a sufficient outside
diameter to facilitate insertion of the sheath into the vessel, and
a sufficient inside diameter capable of accepting the probe. By
contrast, for clearing occlusions from, for example, a hemodialysis
graft, the probe useful for such a procedure would be significantly
shorter and as such, so would the sheath. The exact length and
diameter of the sheath will be determined by the requirements of
the medical procedure. Similarly, the position and size of the
sheath aperture 111, or number and positions of the fenestrations
111, or the addition of a bevel on the sheath terminus 129, will
likewise be determined by the type of procedure, and the
requirements of the particular patient.
[0048] A particular advantage of the ultrasonic probe operating in
transverse mode is that the efficient cavitation energy produced by
the probe disintegrates target tissue to small particles of
approximately sub-micron diameter. Because of the operation of the
probe, tissue debris created at the probe tip 23 is propelled in a
retrograde direction from the probe tip. Accordingly, another
embodiment of the invention provides at least one aspiration
channel which can be adapted to a vacuum or suction device, to
remove the tissue debris created by the action of the probe. The
aspiration channel can be manufactured out of the same material as
the sheath provided it is of a sufficient rigidity to maintain its
structural integrity under the negative pressure produced by the
aspiration means. Such an aspiration channel could be provided
inside the lumen of the sheath, or along the exterior surface of
the sheath, or the sheath itself may provide the aspiration
channel. One embodiment of this is shown in FIGS. 6 and 7, whereby
the probe 22 comprises at least one aspiration channel 60, and
aspiration of tissue debris is effectuated along the probe length
between the interior surface of the sheath and the exterior surface
of the probe, as directed by the aspiration channels.
[0049] In another embodiment, the present invention comprises an
irrigation channel. The sheath is adapted to an irrigation means,
and the sheath directs fluid to the location of the probe 22. The
irrigation channel can be manufactured out of the same material as
the sheath provided it is of a sufficient rigidity to maintain its
structural integrity under the positive pressure produced by the
flow of fluid produced by the irrigation means. Such an irrigation
channel could be provided inside the lumen of the sheath, or along
the exterior surface of the sheath, or the sheath itself may
provide the aspiration channel. Using the sheath itself to provide
the irrigation, there is an added benefit that the probe 22 is
cooled by the fluid.
[0050] In yet another embodiment, the sheath of the present
invention further comprises both an irrigation and an aspiration
channel. As in the above embodiment, the channels may be located
within the sheath lumen, or exterior to the sheath, or a
combination of the two. Likewise, the sheath lumen itself may
provide either an irrigation or aspiration channel, with the
corresponding irrigation or aspiration channel either contained
within or external to the sheath. In another aspect of the
invention, the sheath comprises a means for directing, controlling,
regulating, and focusing the cavitation energy emitted by the
probe, an aspiration means, an irrigation means, or any combination
of the above.
[0051] Another embodiment of the invention comprises a means of
viewing the site of probe action. This may include an illumination
means and a viewing means. In one embodiment, the sheath of the
present invention comprises a means for containing or introducing
(if external to the sheath) an endoscope, or similar optical
imaging means. In another embodiment of the invention, the
ultrasound medical device is used in conjunction with an imaging
system, for example, the non-ferrous probes are compatible with
MRI, or ultrasound imaging--in particular color ultrasound. In this
embodiment, the action of the probe echogenically produces a
pronounced and bright image on the display. The sheath in this
embodiment shields the probe, thereby reducing the intensity of the
probe image and enhancing the resolution of the surrounding
tissues. In another embodiment of the invention (not shown), the
probe is used with an optical system. In one embodiment, the probe
is inserted into a body cavity or lumen along with a light
transmitting element for transmitting light from a light source and
for receiving light and transmitting received light to a detector.
Light from a light source (e.g., a laser) is transmitted through
the light transmitting element, illuminating the area surrounding
the probe 6, and light transmitted back through the light
transmitting element (e.g., from tissue in the vicinity of the
probe) is detected by the detector. In one embodiment of the
invention, the light transmitting element is an optical fiber,
while in another embodiment, the light transmitting element is a
plurality of optical fibers. The light transmitting element can be
a part of the probe or can be inserted into a body cavity
independently of the probe. In one embodiment of the invention, a
sleeve is attached to the probe and the light transmitting element
is held within the sleeve. In one embodiment, the detector is a
human being (e.g., a physician or lab technician) and light is
monitored using a viewing element, such as an eyepiece (e.g., as in
a microscope coupled to the light transmitting element). It is
preferred that the viewing element is not connected to a part of
the ultrasonic medical device which is subject to vibration, to
reduce manipulation of the viewing system to a minimum. In another
embodiment of the invention, the detector is in communication with
a processor and converts optical signals from the light
transmitting element to data relating to the tissue in the vicinity
of the probe.
[0052] In one embodiment, as shown in FIGS. 8a, 8b, and 8c, the
sheath comprises a surface that is capable of manipulating tissues
near the site of the probe. In this aspect, the terminus of the
sheath may be closed, such that the sheath insulates tissues from
the destructive energy emitted by the probe and can be used to push
tissues away from the aperture 111, thereby allowing proximal
tissues to be exposed to the probe 22 and 23. Alternatively, the
sheath comprises a beveled or arcuate surface at the sheath
terminus 129, capable of providing a means for hooking, grasping,
or otherwise holding a tissue in proximity to the probe 22 and 23.
In another embodiment, the sheath provides a means for introducing
a surgical device, for example, flexible biopsy forceps, capable of
manipulating tissues into a tissue space, such that the surgical
device can hold the tissue in proximity with the probe.
[0053] In one aspect of the invention, as shown in FIG. 5, the
sheath comprises an inner sheath 121 and an outer sheath 108. The
outer sheath may be connected to a retraction trigger (not shown),
by one or more articulation means, such as wires, which is capable
of moving the outer sheath with respect to the inner sheath. Each
wire comprises a first end and second end. The first end is affixed
to the outer sheath 108, while the second end is affixed to a
retraction trigger. When the outer sheath 108 is slid back away
from the terminus of the inner sheath 121 the tissues are exposed
to cavitation energy emitted by the probe. Another aspect of this
is referred to in FIGS. 10a and 10b, where the first sheath 107, is
adapted to articulation wires (not shown in the illustration). In
this embodiment, moving the sheath exposes the probe to the lumen
of a second sheath 121, comprising fenestrations which allow
communication of the energy emitted from the probe to the lumen of
a balloon catheter 91. In this aspect, a probe can be operational
without inflating the balloon catheter until movement of the first
sheath exposes the probe, thereby allowing the probe to penetrate
occlusions that would otherwise prevent placement of the balloon
catheter without first clearing a site for placement within the
occlusion, and thereby reducing the number of steps in a surgical
procedure.
[0054] In another embodiment, the probe and sheath are flexible.
Articulation wires (not shown) comprising a first end and second
end, are connected to the sheath and to an articulation handle.
When the articulation handle is manipulated, for example, pulled
axially inward, the flexible sheath will bend or articulate in a
bending or articulation direction A, thereby causing the ultrasonic
probe to bend or articulate in articulation direction A. In this
way, the ultrasonic probe can be used to reach locations which are
not axially aligned with the lumen or vessel through which the
sheath and probe are inserted. One aspect of the invention uses
such an articulable sheath to direct placement of a probe and a
balloon catheter to a surgical site.
[0055] In yet another embodiment, the sheaths of the present
invention may be provided along with an ultrasonic probe in the
form of a kit. In this aspect, the probe for a particular surgical
procedure is provided along with the correct sheath, as well as
instructions for assembling and tuning the probe, and the
appropriate frequency range for the procedure. The probe and sheath
may be packaged preassembled, such that the probe is already
contained within the sheath and the respective position of the
probe within the sheath is optimized such that any reflective
elements in the sheath would be correctly aligned with the
prospective position of the anti-nodes for a given frequency, the
kit further comprising instructions for the appropriate frequency.
The kit may further comprise packaging whereby the probe and sheath
are pre-sterilized, and sealed against contaminants. In another
embodiment, the probe and sheath is provided in a container that
complies with regulations governing the storage, handling, and
disposal of sharp medical devices. Such a container is capable of
receiving and securing the probe and sheath before and after use.
In one aspect, the sharps container provides a means of affixing
the probe and sheath assembly to an ultrasonic medical device
without direct manipulation of the probe and sheath assembly, and a
means for removing the assembly from the ultrasonic medical device
after use. In one aspect, the kit comprises a probe and sheath
assembly contained within a sterile sharps container that further
comprises a single use locking means, whereby the probe and sheath
assembly is affixed to the ultrasonic medical device solely through
the sharps container, are removed from the device solely through
the container, and once removed can not be re-extracted from the
sharps container.
EXAMPLES
Example 1
Removing Occlusions Using an Ultrasonic Medical Device and a
Balloon Catheter
[0056] In one embodiment of the invention, the transverse mode
ultrasonic medical device, is used in a procedure to remove an
occlusion from a small diameter vessel (e.g., a native vessel, or a
grafted vessel). In one embodiment, device is used in a method to
reduce or eliminate an occlusion of a saphenous vein graft (e.g.,
such as used in a coronary bypass procedure).
[0057] A transverse mode ultrasonic probe is selected by the
surgeon who will perform the procedure. The probe of the present
invention further comprises a plurality of sheaths adapted to the
probe, and a balloon catheter operably attached to one of the
sheaths, all incorporated within a sharps container, and the
container further sealed inside a sterile package, for example, a
plastic bag. The user removes the container from the package and
attaches the probe to the ultrasonic medical device by applying the
threaded end of the probe to the transducer portion of an
ultrasonic medical device. The probe, sheaths, and balloon catheter
are securely held within the container, and the user rotates the
container to affix the probe, sheaths, and catheter to the
ultrasonic medical device. The user engages a lever which
articulates the side. A first locking assembly, thereby disengaging
the probe from the first locking assembly. The probe, sheaths, and
catheter can now be withdrawn from the container. The first locking
assembly, once articulated, is engaged and held stationary by a
second locking means, thereby preventing further use of the first
locking assembly on this side A of the container with a probe.
Articulation wires attached to one of the sheaths are connected to
a trigger assembly so the first sheath can be moved relative to the
second sheath and the probe. One terminus of the balloon catheter
is connected to an inflation means that may further comprise a
means of monitoring and adjusting for pressure changes in the
balloon lumen.
[0058] A small incision is made into the chest of a patient, and
the vein graft is visualized using routine imaging technology. The
probe, sheaths, and balloon catheter assembly is introduced into a
vessel near the site of the occlusion, by way of, for example, a
trocar or other vascular introducer. The probe assembly is guided
to the site of the occlusion. The probe may be operably emitting
energy, but the position of the first sheath relative to the probe
and second sheath prevents cavitation energy from the probe from
entering the balloon catheter, and the exposed probe terminus
allows for introduction of the assembly, specifically the balloon
catheter into the interior of the occlusion, as the occlusion is
fragmented around the probe. The balloon catheter is inflated to
greater than ambient pressure, such as for example, 1.5
atmospheres, so that the balloon is in contact with the occlusion
but does not exert a high degree of compressive force on the
occlusion or the vessel wall. The transversely vibrating probe is
exposed to the lumen of the balloon by articulation of the first
sheath. Cavitation energy from the probe is transmitted to the
occlusion through the polymer walls of the balloon, thereby
fragmenting the occlusion. As the occlusion is destroyed, allowing
expansion of the balloon, the pressure drop is sensed and
compensated for, by the inflation means, thereby the balloon
re-engages the surface of the occlusion. The process continues for
an appropriate length of time determined by the surgeon. When the
procedure is completed, the balloon catheter is deflated, and the
catheter, sheaths, and probe are withdrawn from the patient. The
insertion device is removed, and the vascular tear and surgical
incision are sutured.
[0059] When the user completes the surgical procedure, and the
probe apparatus is no longer required, the user inserts the probe,
sheaths, and balloon catheter into side B of the container. The
user engages a lever which articulates the side B first locking
assembly, which, once articulated, is engaged and held stationary
by a second locking means, thereby preventing further articulation
of the side B first locking assembly. This first locking assembly
engages the probe, thereby securing it. The user removes the probe
assembly from the transducer of the medical device by applying
counter-rotational torque to the container, thereby unscrewing the
probe from the device. The used probe and assembly is permanently
engaged by and contained within the container, and can be disposed
of in compliance with the provisions governing the disposal of
medical waste. Because the probe assembly is contained by the
invention, the sharp probe tip does not present a safety hazard,
and can be safely handled and disposed of as medical trash.
Example 2
Clearing Occlusions from a Hemodialysis Graft
[0060] In another embodiment, the invention can be used to clear
occlusions from and restore the patency of a hemodialysis graft.
The graft will not require shielding from ultrasonic energy, or the
use of a balloon catheter as in example 1. A probe is selected and
affixed to the ultrasonic transducer in the manner previously
described, through the use of the container. The probe is withdrawn
from the container, and inserted into the lumen of the hemodialysis
graft. In one embodiment, the probe is directly introduced into the
hemodialysis graft. In another embodiment, the probe is inserted
using a trocar or other vascular insertion device, such as for
example, the insertion device of Applicant's utility application
Ser. No. 09/618,352, now U.S. Pat. No. 6,551,337. Application of
ultrasonic energy causes the probe to vibrate transversely along
its longitude. Occlusive materials, such as for example a thrombus,
are fragmented by the action of the probe. When the graft has been
returned to patency, the probe is withdrawn. The probe is removed
from the device with the sharps container.
[0061] Variations, modifications, and other implementations of what
is described herein will occur to those of ordinary skill in the
art without departing from the spirit and scope of the invention as
claimed. Accordingly, the invention is to be defined not by the
preceding illustrative description but instead by the spirit and
scope of the following claims. The following references provided
include additional information, the entirety of which is
incorporated herein by reference.
* * * * *