U.S. patent application number 14/774103 was filed with the patent office on 2016-02-04 for method and apparatus for treatment of intracranial hemorrhages.
The applicant listed for this patent is EKOS CORPORATION. Invention is credited to Curtis Gentsler, Douglas R. Hansmann, Jocelyn Kersten, Raymond M. Wolniewicz, III.
Application Number | 20160030725 14/774103 |
Document ID | / |
Family ID | 50588804 |
Filed Date | 2016-02-04 |
United States Patent
Application |
20160030725 |
Kind Code |
A1 |
Kersten; Jocelyn ; et
al. |
February 4, 2016 |
METHOD AND APPARATUS FOR TREATMENT OF INTRACRANIAL HEMORRHAGES
Abstract
An ultrasound catheter with a lumen for fluid delivery and/or
fluid evacuation, and ultrasound radiating elements is used for the
delivery of therapeutic compounds to a target location. After the
catheter is inserted into a cavity, a therapeutic compound can be
delivered to the target location via selective activation of the
ultrasound radiating elements. Selective activation of the
ultrasound radiating elements can be used to cause fluid flow in a
direction proximal and/or distal the catheter. Moreover, selective
activating can be used to maintain fluid between certain of the
ultrasound radiating elements.
Inventors: |
Kersten; Jocelyn; (Kirkland,
WA) ; Gentsler; Curtis; (Snohomish, WA) ;
Wolniewicz, III; Raymond M.; (Redmond, WA) ;
Hansmann; Douglas R.; (Bainbridge Island, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EKOS CORPORATION |
Bothell |
WA |
US |
|
|
Family ID: |
50588804 |
Appl. No.: |
14/774103 |
Filed: |
March 10, 2014 |
PCT Filed: |
March 10, 2014 |
PCT NO: |
PCT/US2014/022797 |
371 Date: |
September 9, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61781750 |
Mar 14, 2013 |
|
|
|
Current U.S.
Class: |
604/22 |
Current CPC
Class: |
A61M 25/0043 20130101;
A61B 2017/22088 20130101; A61M 25/007 20130101; A61M 25/0021
20130101; A61M 2210/0693 20130101; A61M 25/0071 20130101; A61M
37/0092 20130101; A61M 2025/0078 20130101; A61M 2205/50 20130101;
A61M 27/006 20130101; A61M 5/142 20130101; A61M 25/0026 20130101;
A61M 2025/0002 20130101; A61M 27/00 20130101; A61M 2205/3334
20130101 |
International
Class: |
A61M 37/00 20060101
A61M037/00; A61M 25/00 20060101 A61M025/00 |
Claims
1. A method of delivering compounds to a target region, comprising
the steps of: advancing an ultrasound catheter to the target
region, the ultrasound catheter comprising two or more ultrasound
radiating elements and a first passage, wherein the two or more
ultrasound radiating elements are spaced apart longitudinally along
the ultrasound catheter; introducing a first therapeutic compound
to the target location via the first passage; and sequentially
activating the two or more ultrasound radiating elements such that
the first therapeutic compound is directed to a first target
area.
2. The method of claim 1, wherein the step of sequentially
activating the two or more ultrasound radiating elements comprises
alternately activating adjacent ultrasound radiating elements such
that at least a portion of the fluid proximate a proximal-most
ultrasound radiating element flows distal the activated ultrasound
radiating elements.
3. The method of claim 1, wherein the step of sequentially
activating the two or more ultrasound radiating elements comprises
alternately activating adjacent ultrasound radiating elements such
that at least a portion of the fluid proximate a distal-most
radiating element flows proximal the activated ultrasound radiating
elements.
4. The method according to claim 1, wherein the step of
sequentially activating the two or more ultrasound radiating
elements comprises simultaneously activating two or more ultrasound
radiating elements such that at least a portion of the fluid
remains between the activated ultrasound radiating elements.
5. The method according to claim 1, wherein step of introducing a
first therapeutic compound into the target region comprises
activating a first pump in fluid communication with the first
passage.
6. The method according to claim 1, further comprising
synchronizing the activation of the two or more ultrasound
radiating elements with the activation of the first pump such that
the first therapeutic compound is directed to the first target
area
7. The method according to claim 1, wherein the ultrasound catheter
further comprises a second passage.
8. The method of claim 7, further comprising draining fluid from
the cavity through the second passage.
9. The method according to claim 7, further comprising introducing
a second therapeutic compound into the cavity via the second
passage and sequentially activating the two or more ultrasound
radiating elements such that the second therapeutic compound is
directed to a second target area.
10. The method according to claim 1, further comprising increasing
the permeability of the target region using at least one of the
first and second ultrasound radiating elements.
11. An apparatus for delivering drugs to a target region, the
apparatus comprising: an ultrasound catheter comprising: a tubular
body comprising a first lumen; two or more ultrasound radiating
elements spaced apart longitudinally along the tubular body; and a
first passage in fluid communication with the lumen; and a
processing unit, the processing unit configured to selectively
activate ultrasound radiating elements to control the flow of a
fluid surrounding the ultrasound catheter.
12. The apparatus of claim 11, further comprising a pump in fluid
communication with the lumen, the pump configured to pump a first
therapeutic compound through the lumen and out of the first
passage.
13. The apparatus of claim 11, further comprising a second passage
in fluid communication with a second lumen.
14. The apparatus of claim 13, further comprising a second pump in
fluid communication with the second lumen.
15. The apparatus of claim 11, wherein the processing unit is
configured to alternately activate adjacent ultrasound radiating
elements such that at least a portion of the fluid proximate a
proximal-most ultrasound radiating element flows distal the
activated ultrasound radiating elements.
16. The apparatus of claim 11, wherein the processing unit is
configured to alternately activate adjacent ultrasound radiating
elements such that at least a portion of the fluid proximate a
distal-most radiating element flows proximal the activated
ultrasound radiating elements.
17. The apparatus of claim 11, wherein the processing unit is
configured to simultaneously activate two or more ultrasound
radiating elements such that at least a portion of the fluid
remains between the activated ultrasound radiating elements.
Description
PRIORITY INFORMATION
[0001] The present application claims priority to U.S. Provisional
Application No. 61/781,750 filed Mar. 14, 2013, the entire contents
of which is hereby expressly incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to methods and apparatuses for
increasing the efficacy of therapeutic compounds delivered to
tissues affected by disease, and more specifically, to methods and
apparatuses for increasing the efficacy of therapeutic compounds
delivered to targeted tissue, such as brain tissue, using
ultrasound.
[0004] 2. Background of the Invention
[0005] A large number of Americans each year suffer from diseases
affecting the brain and other parts of the body. Such diseases
include cancer, Alzheimer's, Parkinson's Syndrome, as well as other
illnesses. However, the efficacy of such treatments is
significantly reduced as a result of physiological barriers. One
such example of a physiological barrier is the blood-brain barrier
which serves as a boundary between blood and fluid from the central
nervous system. Such physiological barriers significantly reduce
the ability of therapeutic compounds placed within the bloodstream
to cross the barrier and effectively act upon targeted tissue. This
is especially true for therapeutic compounds consisting of larger
molecules. As a result, the physiological barrier significantly
reduces the ability of therapeutic compounds delivered into the
bloodstream to reach targeted tissue across the barrier thereby
significantly reducing the possibility of effective treatment of
the disease. As such, there is an interest in developing of
targeted therapeutic compound delivery systems which can enhance
the ability of these compounds to cross such physiological
barriers.
[0006] In order to treat diseases affecting the brain and other
parts of the body, some current methods deliver therapeutic
compounds directly to areas affected by the disease. For example,
with respect to the brain, some current methods deliver therapeutic
compounds directly to affected tissue to bypass any complications
arising as a result of the blood-brain barrier. It is particularly
important, especially in sensitive areas such as the brain, to
increase efficacy of such compounds placed in the bloodstream by
more directly targeting the affected tissue with the delivered
drugs. This can reduce the need for higher concentrations of the
compounds and reduce the amount any adverse effects on neighboring
healthy tissue.
[0007] With respect to treatment of diseases affecting the brain,
current methods and devices use various fluid infusion techniques
under pressure, sometimes termed convection-enhanced delivery
(CED), to conduct targeted therapeutic compound delivery to
targeted brain tissue. These methods involve connecting a pump to a
catheter to drive fluid containing a therapeutic compound into the
targeted tissue. However, since these techniques require volumetric
infusion into a closed vessel (i.e., the cranium), pressures within
the closed vessel increase. In highly sensitive areas, such as the
brain, there is a limit to the amount of pressure increase, and
therefore the amount of infusion possible, before injuries are
sustained as a result of stresses and strains caused by the
increased pressures. As such, limits are placed on the amount of
enhancement that can be achieved using current CED techniques.
Additionally, current CED techniques have been shown to oftentimes
not reach the targeted location. Furthermore, other complications
arise which further reduce the efficacy of this treatment method
such as fluid traveling back along the catheter and away from the
targeted area (i.e., backflow).
[0008] As such, while CED therapies have shown promise, there is a
general desire to continue to improve the methods and apparatuses
involved with such therapy.
SUMMARY OF THE INVENTIONS
[0009] Methods of activating and sequencing ultrasound radiating
elements are provided which increase the efficacy of therapeutic
compounds delivered to targeted tissue. In accordance with these
methods, embodiments of ultrasound catheters configured to
implement the above methods are also included.
[0010] An embodiment of an ultrasound catheter for increasing the
efficacy of therapeutic compounds delivered to targeted tissue
comprises an elongate tubular body having a distal portion, a
proximal portion, and a central lumen. The catheter further
comprises a plurality of ultrasound radiating elements positioned
within the tubular body. A plurality of ports are located on the
distal portion of the elongate tubular body, and are configured to
allow a fluid to flow through the ports.
[0011] In another embodiment an ultrasound catheter assembly
includes an elongate tubular body having a distal portion and a
proximal portion. The elongate tubular body has material properties
similar to that of standard external ventricular drainage (EVD)
catheter. A lumen is formed within the elongate tubular body. The
lumen includes a plurality of ports on the distal portion of the
elongate tubular body configured to allow fluid to flow
therethrough. An ultrasonic core is configured to be received
within the lumen of the catheter. The ultrasonic core comprises a
plurality of ultrasound radiating elements.
[0012] In another embodiment, an ultrasound catheter comprises an
elongate tubular body having a distal portion and a proximal
portion. A first drainage lumen is formed within the elongate
tubular body. The drainage lumen includes a plurality of drainage
ports on the distal portion of the elongate tubular body configured
to allow fluid to flow therethrough. A delivery lumen is formed
within the elongate tubular body. The delivery lumen includes a
plurality of delivery ports on the distal portion of the elongate
tubular body configured to allow fluid to flow therethrough. A
plurality of ultrasound radiating elements are positioned within
the elongate tubular body.
[0013] In one method of activating ultrasound radiating elements of
the ultrasound catheters, activation of one or more ultrasound
radiating elements is configured to increase permeability in
targeted tissues thereby increasing the efficacy of a therapeutic
compound. Additionally, such activation is configured to enhance
mixing of the therapeutic compound via pressure waves and/or via
cavitation.
[0014] In another method of activating and sequencing ultrasound
radiating elements of the ultrasound catheters, activation of one
or more ultrasound radiating elements is sequenced or synchronized
with the timing of delivery of a therapeutic compound. This
sequencing or synchronization is configured to create a flow
pattern at the delivery site which can be controlled by modifying
activation timing of certain ultrasound radiating elements. The
flow pattern can be chosen to delivery therapeutic compounds
directly to targeted tissue.
[0015] In yet another method of activating and sequencing
ultrasound radiating elements of an ultrasound catheter, activation
of one or more ultrasound radiating elements is sequenced or
synchronized with the timing of delivery of multiple therapeutic
compounds through multiple drainage or delivery ports of an
ultrasound catheter. This sequencing or synchronization is
configured create multiple flow patterns at the delivery site
thereby allowing the multiple therapeutic compounds to be delivered
to different targeted tissue.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Exemplary embodiments of the method and apparatus for
increasing the efficacy of therapeutic compounds delivered to
targeted tissue are illustrated in the accompanying drawings, which
are for illustrative purposes only. The drawings comprise the
following figures, in which like numerals indicate like parts.
[0017] FIG. 1A is a schematic illustration of an ultrasonic
catheter configured for insertion within the cranial cavity.
[0018] FIG. 1B is an enlarged detail view of the distal end of the
ultrasonic catheter shown in FIG. 1A.
[0019] FIG. 1C is an enlarged detail view of the proximal end of
the ultrasonic catheter shown in FIG. 1A.
[0020] FIG. 1D is a schematic illustration of a stylet that can
inserted into the ultrasonic catheter shown in FIG. 1A.
[0021] FIG. 1E is a schematic illustration of ultrasonic core that
can inserted into the ultrasonic catheter shown in FIG. 1A.
[0022] FIG. 1F is cross-sectional view taken through line IF-IF of
FIG. 1A.
[0023] FIG. 1G is a cross-sectional view of an ultrasonic catheter,
according to an embodiment.
[0024] FIG. 1H is a cross-sectional view of an ultrasonic catheter,
according to another embodiment.
[0025] FIG. 2A is a schematic illustration of an ultrasonic
catheter with embedded wires.
[0026] FIG. 2B is an enlarged detail view of the distal end of the
ultrasonic catheter shown in FIG. 2A.
[0027] FIG. 2C is an enlarged detail view of a medial portion of
the ultrasonic catheter shown in FIG. 2A.
[0028] FIG. 2D is an enlarged detail view of the proximal end of
the ultrasonic catheter shown in FIG. 2A.
[0029] FIG. 3 is a schematic illustration of an ultrasonic catheter
partially inserted into the brain.
[0030] FIG. 4A is a schematic illustration of an ultrasonic
catheter configured for insertion within the cranial cavity.
[0031] FIG. 4B is a cross-sectional view taken through line J-J of
FIG. 4A.
[0032] FIG. 5A is a schematic illustration of an ultrasonic
catheter configured for insertion within the cranial cavity,
according to yet another embodiment
[0033] FIG. 5B is a cross-sectional view taken through line H-H of
FIG. 5A.
[0034] FIG. 6A is a perspective view of a feature for receiving an
ultrasonic element.
[0035] FIG. 6B is a perspective view of another embodiment of a
feature for receiving an ultrasonic element.
[0036] FIG. 7A is a schematic illustration of an ultrasonic
catheter with a coaxial drain port.
[0037] FIG. 7B is an axial view of the ultrasonic catheter shown in
FIG. 7A.
[0038] FIG. 7C is a perspective view of the ultrasonic catheter of
FIG. 7A.
[0039] FIG. 8A is a schematic illustration of an ultrasonic
catheter with drain ports proximal to the connector.
[0040] FIG. 8B is a perspective view of the ultrasonic catheter of
FIG. 8A.
[0041] FIG. 9A is an exploded view of an ultrasonic catheter,
according to an embodiment.
[0042] FIG. 9B is a schematic illustration of the ultrasonic
catheter shown in FIG. 9A.
[0043] FIG. 9C is a cross-sectional view taken through line N-N of
FIG. 9B.
[0044] FIG. 9D is an enlarged detail view of the distal end of the
ultrasonic catheter shown in FIG. 9B.
[0045] FIG. 9E is a cross-sectional view taken through line M-M of
FIG. 9B.
[0046] FIG. 9F is a perspective view of the ultrasonic catheter
shown in FIG. 9B
[0047] FIG. 10A is an exploded view of an ultrasonic catheter,
according to another embodiment.
[0048] FIG. 10B is a schematic illustration of the ultrasonic
catheter shown in FIG. 10A.
[0049] FIG. 10C is a cross-sectional view taken through line P-P of
FIG. 10B.
[0050] FIG. 10D is a perspective view of the spiral extrusion shown
in FIG. 10A.
[0051] FIG. 11A is a schematic view of a drain, according to one
embodiment.
[0052] FIG. 11B is a cross-sectional view taken through line Q-Q of
FIG. 11A.
[0053] FIG. 11C is a perspective view of the drain shown in FIG.
11A.
[0054] FIG. 11D is a schematic view of an ultrasonic core,
according to one embodiment.
[0055] FIG. 11E is a perspective view of the ultrasonic core shown
in FIG. 11D.
[0056] FIG. 11F is a perspective view of a catheter assembly,
according to one embodiment.
[0057] FIG. 11G is a schematic view of the catheter assembly shown
in FIG. 11F.
[0058] FIG. 11H is an enlarged detail view of the distal end of the
drain shown in FIG. 11A.
[0059] FIG. 11I is an enlarged detail view of the distal end of the
ultrasonic core shown in FIG. 11D.
[0060] FIG. 12A is a schematic view of an ultrasonic core wire,
according to one embodiment.
[0061] FIG. 12B is a perspective view of an ultrasonic core wire
with ultrasonic transducers affixed thereto.
[0062] FIG. 12C is a perspective view of an ultrasonic core wire
with a polyimide shell surrounding ultrasonic transducers.
[0063] FIG. 13 is a schematic illustration of an ultrasonic element
within a fluid-filled chamber, according to one embodiment.
[0064] FIG. 14 is a block diagram of a feedback control system for
use with an ultrasonic catheter.
[0065] FIG. 15 is a table listing certain features of various
embodiments of an ultrasonic catheter.
[0066] FIG. 16A is a perspective view of an ultrasonic catheter,
according to another embodiment.
[0067] FIGS. 16B-D are enlarged detail views of the distal portion
of the ultrasonic catheter shown in FIG. 16A. is a schematic
illustration of the ultrasonic catheter shown in FIG. 10A.
[0068] FIG. 16E is a schematic illustration of wires and ultrasonic
radiating members embedded within the ultrasonic catheter shown in
FIG. 16A.
[0069] FIG. 17A-D illustrates potential sequencing and
synchronization of activation of ultrasonic radiating elements
within an ultrasound catheter.
[0070] FIG. 18A illustrates a cross section of an ultrasound
assembly having a chamber between an ultrasound transducer and an
external surface of an elongated body.
[0071] FIG. 18B illustrates a cross section along line "18B" of
FIG. 18A.
[0072] FIG. 18C illustrates a cross section along line "18C" of
FIG. 18C.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0073] As set forth above, methods and apparatuses have been
developed that increase the efficacy of therapeutic compounds or
physician specified fluids delivered to targeted tissue using
ultrasonic energy in conjunction with the therapeutic compound.
Disclosed herein are several exemplary embodiments of ultrasonic
catheters that can be used to enhance the efficacy of therapeutic
compounds at a treatment site within a patient's body. Also
disclosed are exemplary methods for using such catheters. For
example, as discussed in greater detail below, the ultrasonic
catheters disclosed herein can be used to deliver a therapeutic
compound to a blood clot in the brain or other part of the body,
allowing at least a portion of the blood clot to be dissolved
and/or removed, thereby reducing damage to brain or other bodily
tissue. As an additional example, the ultrasonic catheters
disclosed herein can be used to deliver therapeutic compounds, such
as cancer drugs and treatments, alkylating agents, antimetabolites,
and anti-tumor antibiotics, to tumors and/or other drugs used to
treat conditions in the brain or other portions of the body.
Although the embodiments described herein are described primarily
in connection with intracranial use, it should be understood that
the embodiments disclosed herein are also suitable for
intraventricular use or use in other parts of the body in other
applications. Accordingly, the term "intracranial use" can also
include intraventricular use.
[0074] As used herein, the term "therapeutic compound" refers
broadly, without limitation, and in addition to its ordinary
meaning, to a drug, medicament, dissolution compound, genetic
material or any other substance capable of effecting physiological
functions. Additionally, a mixture including substances such as
these is also encompassed within this definition of "therapeutic
compound". Examples of therapeutic compounds include thrombolytic
compounds, anti-thrombosis compounds, and other compounds used in
the treatment of vascular occlusions and/or blood clots, including
compounds intended to prevent or reduce clot formation,
neuroprotective agents, anti-apoptotic agents, and neurotoxin
scavenging agents. Exemplary therapeutic compounds include, but are
not limited to, heparin, urokinase, streptokinase, tPA, rtPA,
BB-10153 (manufactured by British Biotech, Oxford, UK), plasmin,
IIbIIa inhibitors, desmoteplase, caffeinol, deferoxamine, and
factor VIIa. Other examples of therapeutic compounds include cancer
drugs and treatments, alkylating agents, antimetabolites, and
anti-tumor antibiotics and any other drug used to treat any ailment
or disease such as for example, cancer (e.g., brain cancer, lung
cancer, skin cancer, etc.), Parkinson's Syndrome, Alzheimer, and
other such ailments or diseases. Other examples include cancer
and/or oncological drugs, e.g., sonodynamic drugs, used to treat to
tumors and gliomas in the brain or other parts of the body. The
methods and apparatus described above can be used to treat tumors
and gliomas.
[0075] As used herein, the terms "ultrasonic energy", "ultrasound"
and "ultrasonic" refer broadly, without limitation, and in addition
to their ordinary meaning, to mechanical energy transferred through
longitudinal pressure or compression waves. Ultrasonic energy can
be emitted as continuous or pulsed waves, depending on the
parameters of a particular application. Additionally, ultrasonic
energy can be emitted in waveforms having various shapes, such as
sinusoidal waves, triangle waves, square waves, or other wave
forms. Ultrasonic energy includes sound waves. In certain
embodiments, the ultrasonic energy referred to herein has a
frequency between about 20 kHz and about 20 MHz. For example, in
one embodiment, the ultrasonic energy has a frequency between about
500 kHz and about 20 MHz. In another embodiment, the ultrasonic
energy has a frequency between about 1 MHz and about 3 MHz. In yet
another embodiment, the ultrasonic energy has a frequency of about
2 MHz. In certain embodiments described herein, the average
acoustic power of the ultrasonic energy is between about 0.01 watts
and 300 watts. In one embodiment, the average acoustic power is
about 15 watts.
[0076] As used herein, the term "ultrasound radiating element" or
"ultrasound or ultrasonic element" refers broadly, without
limitation, and in addition to its ordinary meaning, to any
apparatus capable of producing ultrasonic energy. An ultrasonic
transducer, which converts electrical energy into ultrasonic
energy, is an example of an ultrasound radiating element. An
exemplary ultrasonic transducer capable of generating ultrasonic
energy from electrical energy is a piezoelectric ceramic
oscillator. Piezoelectric ceramics typically comprise a crystalline
material, such as quartz, that changes shape when an electrical
current is applied to the material. This change in shape, made
oscillatory by an oscillating driving signal, creates ultrasonic
sound waves. In other embodiments, ultrasonic energy can be
generated by an ultrasonic transducer that is remote from the
ultrasound radiating element, and the ultrasonic energy can be
transmitted, via, for example, a wire that is coupled to the
ultrasound radiating element.
[0077] In such embodiments, a "transverse wave" can be generated
along the wire. As used herein is a wave propagated along the wire
in which the direction of the disturbance at each point of the
medium is perpendicular to the wave vector. Some embodiments, such
as embodiments incorporating a wire coupled to an ultrasound
radiating element for example, are capable of generating transverse
waves. See e.g., U.S. Pat. Nos. 6,866,670, 6,660,013 and 6,652,547,
the entirety of which are hereby incorporated by reference herein.
Other embodiments without the wire can also generate transverse
waves along the body of the catheter.
[0078] In certain applications, the ultrasonic energy itself
provides a therapeutic effect to the patient. Examples of such
therapeutic effects include blood clot disruption; promoting
temporary or permanent physiological changes in intracellular or
intercellular structures; rupturing micro-balloons or micro-bubbles
for therapeutic compound delivery; and increasing the permeability
of the targeted cells. Increasing the permeability of the targeted
cells can thereby enhance the efficacy of therapeutic compounds on
those targeted cells. Further information about such methods can be
found in U.S. Pat. Nos. 5,261,291 and 5,431,663.
[0079] FIGS. 1A to 1C and FIG. 1F schematically illustrate one
arrangement of an ultrasonic catheter 10 that can be used to
increase the efficacy of therapeutic compounds delivered to
targeted tissue. FIG. 1B shows an enlarged detail view of a distal
portion 12 of the catheter 10 and FIG. 1C illustrates an enlarged
detail view of a proximal portion 14 of the catheter 10. In the
illustrated arrangement, the ultrasonic catheter 10 generally
includes a multi-component, elongate flexible tubular body 16
having a proximal region 14 and a distal region 12. The tubular
body 16 includes a flexible energy delivery section 18 located in
the distal region 12. Within the distal region 12 are located a
plurality of holes 20, through which fluid may flow into or out of
a central lumen 22 (FIG. 1F) that extends though the catheter 10.
Although the drainage holes 20 are shown as circular, the shape of
the holes may be varied. For instance, the drainage holes may be
oval, polygonal, or irregular. FIGS. 1G and 1H illustrate modified
embodiments of the catheter which include separate lumens for fluid
delivery and for fluid evacuation.
[0080] The catheter 10 defines the hollow lumen 22 which allows for
the free flow of liquids between the drainage holes 20 and the
proximal port 24. For instance, blood may flow from an area
external to the ultrasonic catheter through the drainage holes 20
and into the lumen 22. The blood may then flow proximally in the
lumen 22 towards the proximal region 14 of the ultrasonic catheter,
where it may be collected via the drainage kit. In certain
embodiments, any number of therapeutic compounds may be introduced
into the ultrasonic catheter through the proximal end 14. The
compounds, which may be dissolved or suspended within a liquid
carrier, may flow through the lumen 22 and towards the distal end
12 of the ultrasonic catheter, ultimately exiting the catheter
through drainage holes 20 and entering a treatment site.
[0081] In certain embodiments, negative pressure may be applied to
the lumen 22 of the catheter to facilitate the flow of blood from
the drainage holes 20 towards the proximal end 14. In other
embodiments, no external pressure is applied, and the conditions
present at the treatment site are sufficient to cause the blood to
flow proximally through the lumen 22. In some embodiments, a
positive pressure may be applied to the lumen 22 of the catheter 10
in order for therapeutic compounds or other liquids to pass
distally through the lumen 22 towards the drainage holes 20. In
other embodiments, no external pressure is applied, and the liquid
is permitted to independently flow distally and exit the drainage
ports 20.
[0082] The tubular body 16 and other components of the catheter 10
can be manufactured in accordance with a variety of techniques
known to an ordinarily skilled artisan. Suitable materials and
dimensions can be readily selected based on the natural and
anatomical dimensions of the treatment site and on the desired
access site. In addition, the surface of the catheter 10 can be
coated with an antimicrobial material, such as silver or a silver
based compound. In certain embodiments, the catheter may be
biocompatible for use in the brain or other organs and tissue for
up to 7 days, for up to 15 days, up to 29 days, or for up to 30
days. In one arrangement, the catheter can be coated with a
hydrophilic material.
[0083] In some embodiments, the tubular body 16 can be between
about 23 and 29 centimeters in length. In certain arrangements, the
lumen 22 has a minimum inner diameter of about 2 millimeters and
the catheter body has a maximum outer diameter of about 6 mm.
[0084] In one particular embodiment, the tubular body 16 has
material properties similar to that of standard external
ventricular drainage (EVD) catheters. For example, the tubular body
can be formed of radiopaque polyurethane or silicone, which can be
provided with antimicrobial features. In such embodiments, the
catheter 10 by itself may not have sufficient flexibility, hoop
strength, kink resistance, rigidity and structural support to push
the energy delivery section 18 through an opening in the skull,
organ, or other tissue and then, in turn, to a treatment site
(e.g., one of the ventricles). Accordingly, the catheter 10 can be
used in combination with a stylet 26 (FIG. 1D), which can be
positioned within the tubular body 10. In one embodiment for use in
brain tissue, the device is configured to be compatible with
Neuronavigation systems by easily accommodating the Neuronavigation
system stylet. The stylet 26 can provide additional kink
resistance, rigidity and structural support to the catheter 10 such
that it can be advanced through the patients' brain tissue to the
target site. In certain embodiments, the stylet 26 can be
configured to be used in combination with a standard image guided
EVD placement system. As described below, after placement, the
stylet 26 can then be removed to allow drainage through the tubular
body 16. In a modified arrangement, the tubular body 16 can be
reinforced by braiding, mesh or other constructions to provide
increased kink resistance and ability to be pushed with or without
a stylet. In other embodiments, the device can be configured to be
compatible with other navigation systems for use in other parts of
the body.
[0085] In one embodiment, the tubular body energy delivery section
18 can comprise a material that is thinner than the material
comprising the tubular body proximal region 14. In another
exemplary embodiment, the tubular body energy delivery section 18
comprises a material that has a greater acoustic transparency than
the material comprising the tubular body proximal region 14. In
certain embodiments, the energy delivery section 18 comprises the
same material or a material of the same thickness as the proximal
region 14.
[0086] FIG. 1C shows an enlarged detail view of the proximal
portion 14 of the ultrasonic catheter 10. The proximal portion 14
includes a connector 28. In the embodiment shown, the connector 28
comprises a series of annular rings 30 aligned in parallel. The
connector 28 permits the catheter 10 to be joined to a drainage
kit. For example, in one arrangement, the connector 28 is
configured to connect to a standard EVD drainage kit that can
include an attachment fitting that slides over the connector 28 or
can include a buckle or joint that is fastened around connector 28.
Specific length and configuration of the connector 28 can vary
according to the needs of the particular application, and to
facilitate connection with various drainage kits. Additionally, the
number of annular rings 30 may vary in certain embodiments.
[0087] In the illustrated arrangement of FIGS. 1A-D and IF, the
catheter 10 can be use in combination with an inner core 32 (FIG.
1E) which can be inserted into the lumen 22 after the stylet 26 has
been removed to deliver ultrasound energy to the target site. The
core 32 can include proximal hub 34 fitted on one end of the inner
core 32 proximal region. One or more ultrasound radiating members
36 are positioned within a distal region of the core and are
coupled by wires 38 to the proximal hub 34. In some embodiments,
the inner core 32 can be inserted into the lumen 22 and/or along a
side of the catheter 10. In yet another arrangement, the core 32
can be inserted into the lumen 22 with the distal end including the
ultrasound radiating members extending outside one of the holes
positioned on the distal region of the catheter 10.
[0088] In other embodiments, the catheter 10 can include separate
lumens for drainage and for drug delivery. FIGS. 1G and 1H show
cross-sectional views of two embodiments of a catheter with
multiple lumens. With reference to FIG. 1G, a fluid-delivery lumen
23 is located within the wall of the catheter 10, between the outer
surface and the inner lumen 22, which may be used for fluid
evacuation. In other embodiments, a plurality of fluid-delivery
lumens 23 may be arranged within the catheter 10. Although shown as
substantially circular in cross-section, any number of shapes may
be employed to provide for optimal fluid flow through the
fluid-delivery lumen 23. With reference to FIG. 1H, a separate
fluid-delivery lumen 23 is located within a separate tube running
longitudinally within the inner lumen 22. In certain embodiments, a
plurality of fluid-delivery lumens 23 may be arranged within inner
lumen 22. The size of fluid-delivery lumen 23 may be small enough
so as to not interfere with the function of inner lumen 23 in
evacuating fluid from the treatment site.
[0089] These separate lumens connect drainage and drug delivery
holes positioned generally at the distal end of the catheter with
drug delivery and drainage ports positioned at the proximal end of
the catheter. In one embodiment, the device can include separate
lumens for the drug and drain delivery such that the holes and
ports for drug delivery and drainage are separated from each other.
In some embodiments, the device can include multiple lumens for
delivery of multiple drug types and/or multiple drug
concentrations. The multiple drug lumens can also be used to target
drug delivery along different lengths of the catheter. In some
embodiments, the treatment zone (defined as the distance between
the distal most and proximal most ultrasound transducer) can be
about 1 to 4 cm. In other embodiments, the treatment zone may
extend as far as 10 cm. The drug and drain ports can include luer
type fittings. The ultrasound transducers can be positioned near or
between the drain and drug delivery holes.
[0090] FIGS. 2A-D are schematic illustrations of an ultrasonic
catheter according to another embodiment. The catheter 10 contains
components similar to that shown in FIGS. 1A-C and FIG. 1F-H.
However, in this embodiment, includes wires 38 embedded within the
wall of the tube. As will be explained below, the wires can
activate and control ultrasonic radiating elements located within
the distal region 12 of the catheter 10. Additionally, the catheter
10 may include thermocouples for monitoring temperature of the
treatment zone, the catheter, or surrounding areas. In some
embodiments, each ultrasound radiating element is associated with a
temperature sensor that monitors the temperature of the ultrasound
radiating element. In other embodiments, the ultrasound radiating
element itself is also a temperature sensor and can provide
temperature feedback. In certain embodiments, one or more pressure
sensors are also positioned to monitor pressure of the treatment
site or of the liquid within the lumen of the catheter.
[0091] In the embodiment shown, the wires 38 are bundled and
embedded within the wall of the tubular body 16. In other
embodiments, the wires may not be bundled, but may, for example,
each be spaced apart from one another. Additionally, in certain
embodiments the wires may not be embedded within the wall of the
tubular body 16, but may rather run within the lumen 22. The wires
38 may include protective and/or insulative coating.
[0092] The wires may be advantageously configured such that they
can withstand tension applied to the catheter. For example, the
wires may be able to withstand at least 3 pounds of tension. In
other embodiments, the wires may be able to withstand at least 3.6
pounds, at least 4 pounds, or at least 4.5 pounds of tension.
[0093] The wires may also be configured such that they increase the
stiffness of the tubular body 16 as little as possible. The
flexibility of the tubular body 16 facilitates the introduction of
the catheter 10 into body cavities such as the cranial cavity. It
may therefore be advantageous to select wires that only minimally
contribute to the stiffness of the catheter. The wires chosen may
be between 30 and 48 gauge. In other embodiments, the wires may be
between 33 and 45 gauge, between 36 and 42 gauge, or between 38 and
40 gauge. The number of wires within the catheter is determined by
the number of elements and thermocouples in a particular
device.
[0094] In certain embodiments, the drainage holes 20 include radii
on the outside of the holes, as can be seen in FIG. 2B. Applying a
larger external radius to each drainage hole may improve the flow
of blood into the drainage holes 20 and through the lumen of the
catheter and may reduce damage to brain tissue or other tissue
during insertion and withdrawal. Although the drainage holes 20 are
depicted as arranged in regular rows, the pattern may vary
considerably. The length of the region in which the holes are
located may be between 2 and 4 cm. In certain embodiments, the
length may be between 2.5 and 3.5 cm, or the length may be about 3
cm.
[0095] In the embodiment shown, the annular rings 30 located within
in the proximal region 14 of the catheter 10 may be connected to
the wires 38. In certain embodiments, a wire may be soldered to
each annular ring 30. An electrical contact may then be exposed on
the outer diameter of the annular ring 30 to provide for an
electrical connection to an individual wire. By virtue of this
design, each wire, and therefore each thermocouple or element, may
be addressed independently. In alternative embodiments, two or more
wires may be soldered to an annular ring, thereby creating a single
electrical connection. In other embodiments, the wires may meet
electrical contacts at other points within the catheter 10.
Alternatively, the wires may pass through the wall of the tubular
body 16 and connect directly to external apparatuses.
[0096] FIG. 3 is a schematic illustration of an ultrasonic catheter
partially inserted into the brain. The catheter 10 may be
positioned against the external surface of the skull, with the
distal portion inserted through bore 40. The bore 40 creates an
access path through the skull 42, dura 44, and into the brain
tissue 46. Once in the brain tissue 46, excess blood resulting from
hemorrhaging may be accepted into the drainage holes 20 located on
the distal region of the catheter. Due to the angle of entry into
the brain, the tubular body 16 of the catheter 10 is advantageously
kink resistant, in particular around a bend. Kink resistance is
advantageous at the distal region 12 of the catheter 10. As the
catheter 10 is withdrawn from the brain tissue 46 and begins to
straighten, excess stiffness of the catheter can result in the
distal tip migrating into the brain tissue 46. The presence of the
drainage holes 20 contributes to the flexibility at the distal
region 12 of the catheter 10.
[0097] In one embodiment, the device can be placed using a
tunneling technique which involves pulling the device under the
scalp away from the point of entry in the brain to reduce the
probability of catheter-initiated infections. In one embodiment,
the catheter is made (at least partially) of a soft and pliant
silicone material (and/or similar material) which will move with
the brain matter during therapy without causing injury.
[0098] Dimensions of an ultrasonic catheter may vary according to
different embodiments. For example, the Wall Factor is defined as
the ratio of the outer diameter of the tube to the wall thickness.
The inventors have discovered that a Wall Factor of 4 is useful in
preventing kinking of the catheter. In particular, a Wall Factor of
4 may prevent kinking of the catheter around a 10 mm diameter bend,
with the bend measured through the centerline of the catheter. The
area of the tubular body 16 in which kink resistance is most
advantageous is between 5 and 12 cm from the distal end of the
device.
[0099] Various methods may be employed to impart kink resistance to
the catheter 10. For instance, the tubular body 16 may be
reinforced with coil to prevent kinking of the catheter around
bends. In other embodiments, the tubular body has a wall thickness
that is chosen (in light of the material) sufficient to prevent
kinking as the catheter is placed through a bend.
[0100] FIGS. 4A-B illustrates one arrangement of the ultrasonic
radiating elements 36. FIG. 4B is an enlarged detailed view of a
cross-section along line J-J in FIG. 4A. As shown, in one
arrangement, the ultrasonic radiating elements 36 can be disposed
in the distal region 12 of the ultrasonic catheter 10. In other
embodiments, thermocouples, pressure sensors, or other elements may
also be disposed within the distal region 12. The distal region 12
may be composed of silicone or other suitable material, designed
with drainage holes 20 as discussed above. Ultrasonic radiating
elements 36 may be embedded within the wall of the distal region
12, surrounded by the silicone or other material. In addition to
the ultrasonic radiating elements 36, the catheter may include
wiring embedded within the wall of the flexible tubular body, as
discussed in more detail above with reference to FIGS. 2A-2D. The
ultrasonic radiating elements 36 can include connective wiring,
discussed in greater detail below. In various embodiments, there
may be as few as one and as many as 10 ultrasonic radiating
elements 36 can be embedded with the distal region 12 of the
device. The elements 36 can be equally spaced in the treatment
zone. In other embodiments, the elements 36 can be grouped such
that the spacing is not uniform between them. Spacing and location
of the ultrasonic radiating elements can be based on multiple
factors such as, but not limited to, the desired control over flow
characteristics and the number of drug delivery lumen. In an
exemplary embodiment, the catheter 10 includes two ultrasonic
radiating elements 36. In this two-element configuration, the
elements can be spaced apart approximately 1 cm axially, and
approximately 180 degrees circumferentially. In another embodiment,
the catheter 10 includes three ultrasonic radiating elements 36. In
this three-element configuration, the elements 36 can be spaced
approximately 1 cm apart axially, and approximately 120 degrees
apart circumferentially. As will be apparent to the skilled
artisan, various other combinations of ultrasonic radiating
elements are possible.
[0101] FIGS. 5A-B illustrates another arrangement of the distal
region of an ultrasonic catheter 10. FIG. 5B is an enlarged detail
view of a cross-section along line H-H in FIG. 5A. In the
configuration shown, two elements are spaced approximately 180
degrees apart circumferentially, and are equidistant from the
distal tip of the catheter 10. The catheter can include only two
ultrasonic radiating elements 36 in the distal region 12, or
alternatively it may include four, six, eight, or more, with each
pair arranged in the configuration shown. In embodiments containing
more than one pair, the pairs may be aligned axially.
Alternatively, each pair may be rotated slightly with respect to
another pair of elements. In certain embodiments, each pair of
radiating elements 36 are spaced apart axially approximately 1 cm.
As will be described in greater detail below, the circumferential
spacing of multiple ultrasonic radiating elements can
advantageously enhance the degree of control over flow patterns and
the uniformity of these flow patterns.
[0102] Still referring to FIG. 5B, an epoxy housing 48 is shown,
surrounded by an external layer of silicone 50. In the embodiment
shown, the ultrasonic radiating elements 36 are potted in the epoxy
housing 48. The epoxy may be flush with the outer diameter of
silicone 50. The epoxy housing 48 may have an axial length less
than the length of the distal region 12. In embodiments including
multiple pairs of ultrasonic radiating elements 36, each pair of
elements may be confined to a separate epoxy housing 48. In one
embodiment, the epoxy housing 48 may have an axial length of
between 0.75 and 0.2 inches. In other embodiments, the epoxy
housing 48 may have an axial length of between 0.1 and 0.15 inches,
between 0.11 and 0.12 inches, or approximately 0.115 inches.
[0103] FIGS. 6A-B show two embodiments of epoxy housings 48 in
which an ultrasonic radiating element 36 may be housed. Although
the housing depicted is made from epoxy, any suitable material may
be used. For instance, the housing may be made from rubber,
polyurethane, or any polymer of suitable flexibility and stiffness.
In embodiments employing epoxy, the housing may be formed by
filling a polyimide sleeve with epoxy followed by curing.
[0104] In some embodiments, epoxy housings 48 may be embedded in
the silicone layer with the assistance of chemical adhesives. In
other embodiments, the housings 48 may additionally contain
structural designs to improve the stability of the housing within
the silicone. For instance, the housing 48 shown in FIG. 6A
contains a notch 52 which, when fitted with a complementary
structure of a silicone layer, may improve the stability of the
housing 48 within the silicone layer. Such structural designs may
be used in conjunction with or independently of chemical adhesives.
FIG. 6B shows another embodiment of an epoxy housing 48. In this
embodiment, the raised ridge 54 is designed such that the top
surface may lie flush with a silicone layer that surrounds the
epoxy housing 48. The presence of ridge 54, when positioned with a
complementary silicone layer structure, may help to maintain the
position of the housing, and therefore of the ultrasonic radiating
element, with respect to the ultrasonic catheter.
[0105] FIGS. 7A-C show an ultrasonic catheter with a modified
connector 28 that can be used in combination with the arrangements
and embodiments described above. The catheter 10 includes flexible
tubular body. Distal to the connector 28 is the proximal port 24,
which is in communication with the lumen of the tubular body 16. In
the embodiment shown, the proximal port 24 is coaxial with the
lumen of the tubular body 16. In use, blood from the treatment site
may enter the lumen through the drainage holes 20 located on the
distal region 12 of the catheter 10. Blood may then flow through
the lumen and exit through proximal port 24 into a drainage kit. In
some embodiments, a negative pressure is applied to the lumen of
the catheter 10 to facilitate movement of the blood or other
liquids at the treatment site proximally along the lumen and out
the proximal port 24. In other embodiments, no external pressure is
applied, and the blood or other liquid is permitted to flow from
the treatment site to the proximal port 24, unaided by external
pressure. In certain types of treatment, the treatment site will
possess relatively high pressure such that the natural pressure of
the treatment site may cause blood or other liquids to flow from
the treatment site proximally along the lumen, and out the proximal
port 24.
[0106] Blood or other liquids may be drained at defined time
intervals or continuously throughout the treatment. Additionally,
in treatments involving intracranial hemorrhaging, by continuously
draining fluid, the clot, under compression, may move towards the
ultrasonic transducers for optimum ultrasound enhancement. In
treatment of other diseases, continuous drainage can remove
potentially toxic or other unwanted fluids from the treatment site.
Additionally, such drainage can also be used to reduce pressure at
the treatment site. Such reduction in pressure can be particularly
important in highly sensitive areas such as the brain.
Additionally, therapeutic agents may pass in the opposite
direction. Such agents may enter the proximal port 24, pass
distally through the lumen, and exit the catheter 10 through the
drainage holes 20. In some embodiments, a positive pressure is
applied to facilitate movement of the therapeutic agent or other
liquid distally through the lumen and out the drainage holes 20. In
other embodiments, no external pressure is applied, and the liquid
is permitted to flow independently through the lumen. Therapeutic
agents may be delivered in the form of a bolus within defined time
intervals or continuously throughout the treatment. In order to
allow for an exit path through the proximal port 24, the connector
28 is oriented at an angle with respect to the tubular body 16. In
some embodiments, the connector lies at an angle between 10 and 90
degrees. In other embodiments, the connector 28 lies at an angle
between 10 and 60 degrees, between 12 and 45 degrees, between 20
and 30 degrees, or approximately 22.5 degrees.
[0107] As described above with respect to other embodiments, the
connector 28 may be configured to provide electrical connections to
the ultrasound radiating elements. In the embodiments shown,
however, the connector 28 may lie at an angle with respect to the
tubular body 16. In certain embodiments, a wire may be soldered to
a contact point on the inner portion of connector 28. An electrical
contact may then be exposed on the outer surface of the connector
28 to provide for an electrical connection to an individual wire.
By virtue of this design, each wire, and therefore each
thermocouple or element, may be addressed independently. In
alternative embodiments, two or more wires may be soldered to a
single contact, thereby creating a single electrical connection. In
other embodiments, the wires may meet electrical contacts at other
points within the catheter 10. Alternatively, the wires may pass
through the wall of the tubular body 16 and connect directly to
external apparatuses.
[0108] The catheter 10 may be advanced until distal region 12
reaches the desired treatment site. For instance, the catheter 10
may be advanced through the cranial cavity until it is proximate to
a treatment site near the target tissue. Therapeutic agents may
then be delivered to the treatment site by the path described
above. For instance, thrombolytic agents may be delivered to the
treatment site, in order to dissolve the blood clot. In other
instances, alkylating agents, antimetabolites, and anti-tumor drugs
and/or antibiotics, may be delivered to the treatment site in order
to penetrate into tumors. In other instances, other types of
therapeutic compounds can be used and delivered to a treatment site
to treat diseased tissue at the treatment site. In certain
embodiments, ultrasonic energy may then be applied to the treatment
site, as discussed above. Ultrasonic energy, alone or in
combination with therapeutic compounds, may advantageously expedite
penetration into the target area. The ultrasonic energy may be
applied continuously, periodically, sporadically, or otherwise.
[0109] A modified embodiment of an ultrasonic catheter with a
proximal port is shown in FIGS. 8A-B. In the embodiment shown, the
proximal port 24 is located on the flexible tubular body 16 and is
in communication with the lumen of the tubular body 16. In this
configuration, the proximal port 24 is perpendicular to the axis of
the tubular body 16, as opposed to the configuration depicted in
FIGS. 7A-C, in which the proximal port 24 is coaxial with the
tubular body 16. Positioning the proximal port 24 on the wall of
the tubular body 16 removes the need for the connector to lie at an
angle with respect to the tubular body 16.
[0110] As discussed above, therapeutic agents may flow through
proximal port 24, distally through the lumen, and may exit the
catheter 10 through the drainage holes 20 in distal region 12.
Additionally, blood or other liquid may flow in the opposite
direction, entering the catheter through drainage holes 20, flowing
proximally through the lumen, and exiting the catheter 10 through
proximal port 24 and into a drainage kit or other disposal means.
Ultrasonic energy may also be applied periodically, continuously,
sporadically, or otherwise throughout the process as desired. In
certain embodiments, external pressure, negative or positive, may
be applied in order to facilitate movement of liquids from the
proximal port 24 through the lumen and out drainage holes 20, or in
the opposite direction. In other embodiments, liquids are permitted
to flow through the lumen, unaided by external pressure.
[0111] FIGS. 9A-F illustrate another arrangement for arranging the
wires of an ultrasonic catheter. This arrangement can be used with
the embodiments and arrangements described above. In this
arrangement, a spiral groove extrusion 56 provides structural
support to the tubular body 16. In certain embodiments, the groove
extrusion 56 may be replaced by a similar structure formed by
molding or any other method. The spiral groove design can provide
improved kink resistance compared to a solid structure. The spiral
groove extrusion 56 may be formed of a variety of different
materials. For example, in one arrangement, metallic ribbons can be
used because of their strength-to-weight ratios, fibrous materials
(both synthetic and natural). In certain embodiments, stainless
steel or tungsten alloys may be used to form the spiral groove
extrusion 56. In certain embodiments, more malleable metals and
alloys, e.g. gold, platinum, palladium, rhodium, etc. may be used.
A platinum alloy with a small percentage of tungsten may be
preferred due to its radiopacity. A sleeve 58 is arranged to slide
over the spiral groove extrusion 56. The material for sleeve 58 may
be formed of almost any biocompatible material, such as polyvinyl
acetate or any biocompatible plastic or metal alloy. Distal
extrusion 60 can house ultrasonic elements as well as drainage
holes 20. The distal extrusion 60 can be formed of materials such
as those described above with respect to spiral groove extrusion
56. Wires 38 are affixed to the distal extrusion 60 and connected
to thermocouple or ultrasound radiating elements. A distal tip 62
is fitted to the end of distal extrusion 60.
[0112] FIG. 9C shows a cross-sectional view of the tubular body 16
taken along line N-N of FIG. 9B. Outer diameter 64 may be
approximately 0.2 inches. In other embodiments, the outer diameter
64 may be approximately 0.213 inches. The inner diameter 66 may be
approximately 0.1 inches. In other embodiments, the inner diameter
may be approximately 0.106 inches. As will be apparent, the
dimensions of the inner and outer diameters will be selected
according to the application intended based on, e.g., the diameter
of the access path through the skull, the treatment site, the
volume of therapeutic agent delivered, and anticipated volume of
blood to be drained.
[0113] In the embodiment shown, the distal extrusion 60 may contain
a window 68 in which an ultrasound radiating element may be
affixed. In other embodiments, multiple ultrasonic radiating
elements, each with a corresponding window 68, may be employed. As
discussed above, the number, orientation, and relation of the
ultrasonic radiating elements 36 may vary widely.
[0114] FIG. 9E shows a cross-sectional view of distal extrusion 60
taken along line M-M of FIG. 9D. The drainage holes 20 are, in the
embodiment shown, longitudinal gaps in the external surface of the
distal extrusion 60. As can be seen in FIG. 9E, the distal
extrusion 60 contains four drainage holes 20, each positioned
approximately 90 degrees apart circumferentially. In other
embodiments, two or three longitudinal drainage holes may be
employed. In exemplary embodiments, five or more longitudinal
drainage holes may be used.
[0115] FIGS. 10A-D show another embodiment of an ultrasonic
catheter. As with FIGS. 9A-F, a spiral groove extrusion 56 provides
the structural support to the flexible tubular body 16. Sleeve 58
is dimensioned to fit over the spiral extrusion 56. In the
embodiment shown, the distal extrusion 60 has been excluded.
Instead, the spiral extrusion 56 includes at its distal end
drainage holes 20. Additionally, sleeve 58 also contains holes 70
designed to align with the drainage holes 20 of the spiral groove
extrusion 56. In some embodiments, the spiral extrusion 56 and
sleeve 58 may be joined before drainage holes 20 are drilled
through both layers. Wires 38 are connected to ultrasound radiating
elements 36. In the embodiment shown, the ultrasound radiating
elements 36 and wires 38 are arranged to lie between the spiral
extrusion 56 and the sleeve 58. As discussed above, the wires may
be arranged in various other configurations. In certain
embodiments, the wires may be arranged to lie within the spiral
groove.
[0116] FIG. 10C shows a cross-sectional view of the proximal region
of the ultrasonic catheter taken along line P-P of FIG. 10B. The
outer diameter 64 of the flexible tubular body 16 may be
approximately 0.2 inches. In certain embodiments, the outer
diameter 64 may be approximately 0.197 inches. The inner diameter
66 of the flexible tubular body 16 may be approximately 0.01
inches. In certain embodiments, the inner diameter 66 may be
approximately 0.098 inches. As described above, the dimensions of
the inner and outer diameters may vary based on the intended
application.
[0117] As can be seen in FIG. 10D, in certain embodiments the
spiral groove may become straight at the distal region 12 of the
catheter. In this arrangement, the straightened region permits
drainage holes 20 to be drilled in an arrangement of rows.
Additionally, ultrasonic radiating elements 36 and wires 38 may be
arranged to lie within the straight portion of the groove.
[0118] FIG. 11A-I show an ultrasonic catheter assembly according to
one embodiment, in which a coaxial ultrasonic core is introduced
into a separate external drain.
[0119] FIGS. 11A-C illustrate one embodiment of a drain 96. The
distal portion 98 of the drain 96 includes drainage holes 100. In a
preferred embodiment, the drainage holes 100 may span approximately
3 cm along the distal portion 98. In other embodiments, the
drainage holes 100 may span shorter or longer distances, as
desired. The drain 96 comprises an elongate tubular body 102, and
may include distance markers 104. Distance markers 104 may be, for
instance, colored stripes that surround the drain. In other
embodiments, the distance markers 104 may be notches, grooves,
radiopaque material, or any other material or structure that allows
the regions to be visualized. The distance markers 104 may be
spaced apart at regular intervals, for instance, every 2 cm, 5 cm,
or other distance. In other embodiments they may be spaced in
gradually increasing intervals, gradually decreasing intervals,
irregularly, or in any other manner. In some embodiments, the
distance between each marker will be written onto external surface
of the drain. The presence of distance markers 104 may
advantageously facilitate careful placement of the drain at a
treatment site. In modified embodiments, a suture wing may be
positioned at about 6 inches along the length of the catheter.
Allowing a physician to visually observe the distance that the
drain is advanced may improve control and placement precision.
[0120] The drain 96 includes a central lumen 106 which allows for
the free flow of liquids from the drainage holes 100 towards the
proximal portion 108 of the drain. As will be discussed in more
detail below, in certain embodiments, any number of therapeutic
compounds may be passed through the lumen 106 and out the drainage
holes 100, where they then enter a treatment site. The diameter of
the lumen may be approximately 2.2 mm, with an approximate outer
diameter of 4.4 mm. In other embodiments, these diameters may be
larger or smaller, as desired. As will be apparent to one of skill
in the art, the inner and outer diameters of the drain 96 will be
chosen based on desired treatment site, fluid flow rate through the
lumen, the material used to construct the drain, and the size of
the ultrasonic core or any other element intended to pass
therethrough. In one arrangement, the drain may operate at a flow
rate of approximately 20 ml per hour, at a pressure of 10 mmHg.
[0121] FIGS. 11D-E show one embodiment of an ultrasonic core 110.
The ultrasonic core 110 comprises an elongate shaft 112 and hub
114. Ultrasonic elements 36 are positioned coaxially with the
elongate shaft 112. In certain embodiments, the ultrasonic core
includes between one and four ultrasonic elements 36. In other
embodiments, five or more ultrasonic elements 36 may be included.
The elongate shaft 112 is dimensioned so as to be removably
received within drain 96. Accordingly, in certain embodiments, the
outer diameter of the elongate shaft is approximately 0.8 mm, and
the length of the elongate shaft is approximately 31 cm.
[0122] The hub 114 is attached to elongate shaft 112 through a
tapered collar 116. A proximal fluid port 118 is in fluid
communication with the hub. Fluids, such as therapeutic drugs, may
be injected down the core through proximal fluid port 118 towards
the treatment zone. Introducing fluids in this manner may permit
the use of a smaller bolus of therapeutic drug as compared to
introducing fluids through the drain as discussed above.
Alternatively, fluids may be injected into the lumen 106 of drain
96 through use of a Tuohy-Borst adapter attached thereto. Injecting
fluids through the lumen 106 of the drain 96 may require lower
injection pressure, although a larger bolus of therapeutic drug may
be necessary. In either configuration, the therapeutic drug
ultimately flows out of drainage holes 100 located in the distal
region 98 of drain 96.
[0123] FIGS. 11F-I illustrate the catheter assembly 120 in which
ultrasonic core 110 is inserted within lumen 106 of drain 96. In
certain embodiments, the drain 96 may be advanced to the treatment
site, followed by insertion of the ultrasonic core 110 within the
drain. For instance, the drain may be tunneled under the scalp,
through a bore in the skull, and into the brain. Then the
ultrasonic core 110 may be inserted into the drain 96, and advanced
until the elongate shaft 112 reaches the distal region 98 of drain
96.
[0124] Upon insertion, ultrasonic elements 36 may be positioned
near the drainage holes 100, allowing for the application of
ultrasonic energy to the treatment site. As can be seen in FIGS.
11H and 11I, the distal end of the elongate shaft 112 of ultrasonic
core 110 may include one or more ultrasonic elements 36. When
advanced into the distal region 98 of drain 96, the ultrasonic
radiating element 36 would be located within the region containing
drainage holes 100. As discussed in more detail above, application
of ultrasonic energy to a treatment site may aid in dissolution of
a blood clot or in penetration of therapeutic compounds to a tumor
or other targeted tissue.
[0125] With reference now to FIGS. 12A and 12B, in alternative
embodiments two separate lumens may be included, one for fluid
evacuation and one for fluid delivery. In certain embodiments,
continuous fluid flow may be possible. For example, application of
positive pressure at the drug delivery port and simultaneous
application of vacuum at the drainage port may provide for
continuous removal of toxic blood components. Alternatively, influx
and efflux could be accomplished separately and intermittently to
allow drugs to have a working dwell time. In certain embodiments,
the catheter design could spatially separate drainage holes from
drug delivery holes and inlet ports, with the ultrasound
transducers in between. The ultrasound radiating radially may
prevent influx from going directly to efflux.
[0126] FIG. 12A-C illustrate one embodiment of an ultrasonic
element and core wire. The ultrasonic core wire 114 comprises
locking apertures 116 and pad 118. When integrated within a
completed ultrasonic core or ultrasonic catheter, the ultrasonic
core wire 114 may be embedded in silicone. The two locking
apertures 116 allow for silicone to flow through the opening,
thereby providing for a mechanical lock that secures the element
into the silicone. The locking apertures need not be circular, but
may be any shape that permits silicone to flow therethrough to
create a mechanical lock. Additionally, in certain embodiments
there may be one locking aperture 116. In other embodiments, there
may be two, three, four, or more locking apertures 116, as desired.
Ultrasonic transducers 120 are affixed to either side of pad 118.
RF wires 122 are then mounted to be in communication with
ultrasonic transducers 120. A polyimide shell 124 may be formed
around the assembly of the pad 118, ultrasonic transducers 120, and
RF wires 122, as shown in FIG. 12C. The polyimide shell may be
oval-shape to aid in correct orientation of the ultrasonic element,
and to minimize the use of epoxy in manufacturing.
[0127] FIG. 13 illustrates an ultrasonic element suspended in a
fluid-filled chamber. The fluid-filled chamber 126 is bounded
circumferentially by a polyimide shell 124, with plugs 128 defining
the ends of the fluid filled chamber. Ultrasonic core wire 114 and
RF wires 122 penetrate one of the plugs 128 to enter the
fluid-filled chamber 126. A fluid-tight seal is provided at the
point of penetration to ensure that the chamber retains its fluid.
Within the fluid-filled chamber 126 are the ultrasonic transducers
120 affixed to the ultrasonic core wire 114 and in communication
with RF wires 122. This design may provide for several advantages
over other configurations. For instance, potting ultrasonic
elements in epoxy may lead to absorption of water by the epoxy,
potentially causing delamination of an ultrasonic element from the
potting material. Delamination of an element reduces the ability of
the ultrasonic energy to be transferred from the ultrasonic element
to the surrounding tissue. Suspending an ultrasonic element within
a fluid-filled chamber may advantageously avoid this problem. The
ultrasonic energy emitted by the ultrasonic elements transfers
easily in fluid, and there is no risk of delamination. In addition,
suspending ultrasonic elements within a fluid-filled chamber may
advantageously reduce the number of components needed for an
ultrasonic core, as well as potentially reducing assembly time.
[0128] FIG. 14 schematically illustrates one embodiment of a
feedback control system 72 that can be used with the catheter 10.
The feedback control system 72 allows the temperature at each
temperature sensor 76 to be monitored and allows the output power
of the energy source 78 to be adjusted accordingly. In some
embodiments, each ultrasound radiating element 36 is associated
with a temperature sensor 76 that monitors the temperature of the
ultrasound radiating element 36 and allows the feedback control
system 72 to control the power delivered to each ultrasound
radiating element 36. In some embodiments, the ultrasound radiating
element 36 itself is also a temperature sensor 76 and can provide
temperature feedback to the feedback control system 72. In
addition, the feedback control system 72 allows the pressure at
each pressure sensor 80 to be monitored and allows the output power
of the energy source 78 to be adjusted accordingly. A physician
can, if desired, override the closed or open loop system.
[0129] In an exemplary embodiment, the feedback control system 72
includes an energy source 78, power circuits 82 and a power
calculation device 84 that is coupled to the ultrasound radiating
elements 36 and a pump 86. A temperature measurement device 88 is
coupled to the temperature sensors 76 in the tubular body 16. A
pressure measurement device 90 is coupled to the pressure sensors
80. A processing unit 94 is coupled to the power calculation device
84, the power circuits 82 and a user interface and display 92.
[0130] In an exemplary method of operation, the temperature at each
temperature sensor 76 is determined by the temperature measurement
device 88. The processing unit 94 receives each determined
temperature from the temperature measurement device 88. The
determined temperature can then be displayed to the user at the
user interface and display 92.
[0131] In an exemplary embodiment, the processing unit 94 includes
logic for generating a temperature control signal. The temperature
control signal is proportional to the difference between the
measured temperature and a desired temperature. The desired
temperature can be determined by the user (as set at the user
interface and display 92) or can be preset within the processing
unit 94.
[0132] In such embodiments, the temperature control signal is
received by the power circuits 82. The power circuits 82 are
configured to adjust the power level, voltage, phase and/or current
of the electrical energy supplied to the ultrasound radiating
elements 36 from the energy source 78. For example, when the
temperature control signal is above a particular level, the power
supplied to a particular group of ultrasound radiating elements 36
is reduced in response to that temperature control signal.
Similarly, when the temperature control signal is below a
particular level, the power supplied to a particular group of
ultrasound radiating elements 36 is increased in response to that
temperature control signal. After each power adjustment, the
processing unit 94 monitors the temperature sensors 76 and produces
another temperature control signal which is received by the power
circuits 82.
[0133] In an exemplary method of operation, the pressure at each
pressure sensor 80 is determined by the pressure measurement device
90. The processing unit 94 receives each determined pressure from
the pressure measurement device 90. The determined pressure can
then be displayed to the user at the user interface and display
92.
[0134] In an exemplary embodiment, the processing unit 94 includes
logic for generating a pressure control signal. The pressure
control signal is proportional to the difference between the
measured pressure and a desired pressure. The desired pressure can
be determined by the user (as set at the user interface and display
92) or can be preset within the processing unit 94.
[0135] As noted above, it is generally desirable to provide low
negative pressure to the lumen in order to reduce the risk of
sucking solid material, such as brain matter or other tissue
surrounding the lumen, into the lumen. Furthermore, because
reduction of intracranial pressure is often desirable in highly
sensitive areas such as the brain, it is often desirable to deliver
fluids with little pressure differential between the delivery
pressure and the intracranial pressure around the catheter to
prevent any injury to sensitive tissue as a result of shear and
strain caused by this pressure differential. Accordingly, the
processing unit 94 can be configured to monitor the pressure and
modify or cease the delivery of fluid and/or increase evacuation of
fluid to the treatment site if intracranial pressure increases
beyond a specified limit.
[0136] In other embodiments, the pressure control signal is
received by the power circuits 82. The power circuits 82 are
configured to adjust the power level, voltage, phase and/or current
of the electrical energy supplied to the pump 86 from the energy
source 78. For example, when the pressure control signal is above a
particular level, the power supplied to a particular pump 86 is
reduced in response to that pressure control signal. Similarly,
when the pressure control signal is below a particular level, the
power supplied to a particular pump 86 is increased in response to
that pressure control signal. After each power adjustment, the
processing unit 94 monitors the pressure sensors 80 and produces
another pressure control signal which is received by the power
circuits 82.
[0137] In an exemplary embodiment, the processing unit 94
optionally includes safety control logic. The safety control logic
detects when the temperature at a temperature sensor 76 and/or the
pressure at a pressure sensor 80 exceeds a safety threshold. In
this case, the processing unit 94 can be configured to provide a
temperature control signal and/or pressure control signal which
causes the power circuits 82 to stop the delivery of energy from
the energy source 78 to that particular group of ultrasound
radiating elements 36 and/or that particular pump 86.
[0138] Consequently, each group of ultrasound radiating elements 36
can be identically adjusted in certain embodiments. For example, in
a modified embodiment, the power, voltage, phase, and/or current
supplied to each group of ultrasound radiating elements 36 is
adjusted in response to the temperature sensor 76 which indicates
the highest temperature. Making voltage, phase and/or current
adjustments in response to the temperature sensed by the
temperature sensor 76 indicating the highest temperature can reduce
overheating of the treatment site.
[0139] The processing unit 94 can also be configured to receive a
power signal from the power calculation device 84. The power signal
can be used to determine the power being received by each group of
ultrasound radiating elements 36 and/or pump 86. The determined
power can then be displayed to the user on the user interface and
display 92.
[0140] As described above, the feedback control system 72 can be
configured to maintain tissue adjacent to the energy delivery
section 18 below a desired temperature. For example, in certain
applications, tissue at the treatment site is to have a temperature
increase of less than or equal to approximately 6 degrees C. As
described above, the ultrasound radiating elements 36 can be
electrically connected such that each group of ultrasound radiating
elements 36 generates an independent output. In certain
embodiments, the output from the power circuit maintains a selected
energy for each group of ultrasound radiating elements 36 for a
selected length of time.
[0141] The processing unit 94 can comprise a digital or analog
controller, such as a computer with software. In embodiments
wherein the processing unit 94 is a computer, the computer can
include a central processing unit ("CPU") coupled through a system
bus. In such embodiments, the user interface and display 92 can
include a mouse, a keyboard, a disk drive, a display monitor, a
nonvolatile memory system, and/or other computer components. In an
exemplary embodiment, program memory and/or data memory is also
coupled to the bus.
[0142] In another embodiment, in lieu of the series of power
adjustments described above, a profile of the power to be delivered
to each group of ultrasound radiating elements 36 can be
incorporated into the processing unit 94, such that a preset amount
of ultrasonic energy to be delivered is pre-profiled. In such
embodiments, the power delivered to each group of ultrasound
radiating elements 36 is provided according to the preset
profiles.
[0143] In an exemplary embodiment, the ultrasound radiating
elements are operated in a pulsed mode. For example, in one
embodiment, the time average power supplied to the ultrasound
radiating elements is between about 0.1 watts and about 2 watts. In
another embodiment, the time average power supplied to the
ultrasound radiating elements is between about 0.5 watts and about
1.5 watts. In yet another embodiment, the time average power
supplied to the ultrasound radiating elements is approximately 0.6
watts or approximately 1.2 watts. In an exemplary embodiment, the
duty cycle is between about 1% and about 50%. In another
embodiment, the duty cycle is between about 5% and about 25%. In
yet another embodiment, the duty cycles is approximately 7.5% or
approximately 15%. In an exemplary embodiment, the pulse averaged
power is between about 0.1 watts and about 20 watts. In another
embodiment, the pulse averaged power is between approximately 5
watts and approximately 20 watts. In yet another embodiment, the
pulse averaged power is approximately 8 watts or approximately 16
watts. The amplitude during each pulse can be constant or
varied.
[0144] In an exemplary embodiment, the pulse repetition rate is
between about 5 Hz and about 150 Hz. In another embodiment, the
pulse repetition rate is between about 10 Hz and about 50 Hz. In
yet another embodiment, the pulse repetition rate is approximately
30 Hz. In an exemplary embodiment, the pulse duration is between
about 1 millisecond and about 50 milliseconds. In another
embodiment, the pulse duration is between about 1 millisecond and
about 25 milliseconds. In yet another embodiment, the pulse
duration is approximately 2.5 milliseconds or approximately 5
milliseconds.
[0145] For example, in one particular embodiment, the ultrasound
radiating elements are operated at an average power of
approximately 0.6 watts, a duty cycle of approximately 7.5%, a
pulse repetition rate of approximately 30 Hz, a pulse average
electrical power of approximately 8 watts and a pulse duration of
approximately 2.5 milliseconds.
[0146] In an exemplary embodiment, the ultrasound radiating element
used with the electrical parameters described herein has an
acoustic efficiency greater than approximately 50%. In another
embodiment, the ultrasound radiating element used with the
electrical parameters described herein has an acoustic efficiency
greater than approximately 75%. As described herein, the ultrasound
radiating elements can be formed in a variety of shapes, such as,
cylindrical (solid or hollow), flat, bar, triangular, and the like.
In an exemplary embodiment, the length of the ultrasound radiating
element is between about 0.1 cm and about 0.5 cm, and the thickness
or diameter of the ultrasound radiating element is between about
0.02 cm and about 0.2 cm.
[0147] With reference now to FIG. 15, in one embodiment of a
treatment protocol, patients can be taken to an operating room and
placed under general anesthesia for ultrasound and drainage
catheter insertion. Patients can be registered using
electromagnetic (EM) stealth, based on CT parameters for
stereotactic placement of catheters using the Medtronic EM Stealth
navigation system. However, as described above, in modified
embodiments, other navigation techniques and tools could be used.
Using such navigation systems, an entry point for the burr hole and
hemorrhage target location for the catheter tips can be chosen. It
should be appreciated that the location of the burr-hole or drill
hole can be selected to reduce the path length between the target
tissue and the hole in the patient's skull. In addition, it may be
desirable in some cases to approach the targeted tissue from an
angle that avoids certain portions of the brain.
[0148] In the illustrated embodiment, a Stealth guidance system (or
other guidance system or technique) can used to place a 12 French
peel-away introducer through the burr hole into the desired
location in the hemorrhage, to accommodate placement of the
ultrasonic catheter 10. In modified arrangements, a different size
and/or type of introducer could be used and/or the ultrasonic
catheter can be inserted without an introducer.
[0149] As shown in FIG. 15, the catheter 10 can be with the peel
away introducer and the position confirmed by neuro navigation or
other navigation technique. In one embodiment, the two catheters
can then be tunneled out through a separate stab wound in the skin
and secured to the patient. A portable CT scan can be done at the
completion of the procedure to confirm acceptable catheter
placement. In one embodiment, the distal tip of the ultrasonic
catheter 10 is generally positioned long the longitudinal center
(measured along the axis of the catheter) of the hemorrhage. As
described above, in other embodiments, an ultrasonic core can be
place through a lumen in the catheter (see e.g., FIGS. 1A-F). In
other embodiments, the ultrasonic catheter can be placed along side
the catheter.
[0150] Ultrasound energy can be delivered for a duration sufficient
to enable adequate drug distribution in and/or around the target
tissue. This can be accomplished by either intermittent or
continuous delivery of ultrasound energy. For example, ultrasound
energy can be delivered for a set time period to adequately
distribute the drug to the target tissue, and then turned off to
allow the drug to act on the target tissue. Alternatively,
ultrasound energy can be delivered substantially continuously after
the drug has been delivered to the target tissue to continuously
redistribute the drug into the target tissue and continuously
enhance the drug penetration into such tissue. In addition,
ultrasound energy can be delivered intermittently to reduce
heating. Also, as described in U.S. application Ser. No.
11/971,172, filed Jan. 8, 2008, which is hereby incorporated by
reference herein in its entirety, the power parameters controlling
the delivery of ultrasound energy can be randomized or varied
according to complex non-linear algorithms in order to enhance the
efficacy of the ultrasound treatment.
[0151] Drug delivery can be controlled by monitoring, for example,
byproducts of the metabolized drug. For example, in the treatment
of blood clots with lytic compounds, lysis byproducts such as
D-dimer in the effluent evacuated from the blood clot can be
monitored. A high and/or increasing concentration of D-dimer in the
effluent can indicate that lysis of the blood clot is proceeding
adequately, and therefore drug delivery can be maintained, reduced
or stopped. A low or decreasing concentration of D-dimer in the
effluent can indicate that lysis of the blood clot is inadequate or
slowing or that the clot is nearly dissolved, and therefore drug
delivery can be increased if the clot is not nearly dissolved, and
reduced or stopped if lysis is almost complete. Alternatively, the
concentration of the drug can be monitored to determine whether
more drug should be delivered and whether treatment is complete. In
some embodiments involving treatment of blood clots, as lysis of
the blood clot proceeds, lytic is freed from the lysed clot,
thereby increasing the concentration of lytic in the effluent.
Therefore, increased lytic concentration can correlate to lysis
completion. One way of determining the concentration of lytic
and/or D-dimer in the effluent is to measure the color of the
effluent that is evacuated from the blood clot. The redder the
effluent, the greater the concentration of lytic and/or D-dimer in
the effluent.
[0152] In some embodiments, neuroprotective drugs or agents that
assist in the functional recovery and/or the reduction of cell and
tissue damage in the brain can also be delivered to the brain and
blood clot with the methods and apparatus described above. These
neuroprotective drugs or agents can be delivered before, with, or
after the delivery of the thrombolytic drugs. Delivery of these
drugs using the methods and apparatus described above is
particularly useful where the drug delivery through the blood brain
barrier is enhanced with ultrasound treatment, or where ultrasound
enhances cell penetration by the drug, or where the drug is
sonodynamic.
[0153] Another embodiment of an ultrasonic catheter is shown in
FIGS. 16A-E. Similar to the embodiments described above with
respect to FIGS. 2A-D, the catheter includes wires 38 embedded
within the wall of the tubular body 16. The wires 38 are connected
to and may control ultrasonic radiating elements 36 located within
the distal region 12 of the catheter 10. The wires extend from the
proximal end of the tubular body 16. In certain embodiments, the
wires extend more than six inches from the proximal end, so as to
facilitate electrical connection with external devices. Drainage
holes 20 are positioned in the distal region 12 of the catheter 10,
near the ultrasonic radiating elements 36. In other embodiments,
thermocouples, pressure sensors, or other elements may also be
disposed within the distal region 12. The distal region 12 may be
composed of silicone or other suitable material, designed with
drainage holes 20 as discussed above. Ultrasonic radiating elements
36 may be embedded within the wall of the distal region 12,
surrounded by the silicone or other material. In various
embodiments, there may be as few as one and as many as 10
ultrasonic radiating elements 36 can be embedded with the distal
region 12 of the device. The elements 36 can be equally spaced in
the treatment zone. In other embodiments, the elements 36 can be
grouped such that the spacing is not uniform between them. In an
exemplary embodiment illustrated in FIGS. 16B-D, the catheter 10
includes four ultrasonic radiating elements 36. In this
four-element configuration, the elements can be spaced apart as
pairs, with each pair located at a similar longitudinal position,
but separated by 180 degrees circumferentially. The pairs of offset
from one another both by 90 degrees circumferentially and by a
longitudinal distance along the length of the catheter 10. As will
be apparent to the skilled artisan, various other combinations of
ultrasonic radiating elements are possible.
[0154] In some embodiments, the ultrasound radiating elements can
be used to generate a steady current in a fluid around the
ultrasound radiating elements. In embodiments where the ultrasound
radiating elements are placed on or in a catheter, this can allow
the generation of a current through fluid surrounding the catheter.
By generating a current through fluid surrounding the catheter, it
is possible to advantageously direct the flow of a therapeutic
compound introduced into the fluid towards a target area, such as
diseased tissue. This can advantageously enhance the effect of the
therapeutic compound by more directly targeting only those areas on
which the therapeutic compound should act. Accordingly, this can
reduce the dosage of therapeutic compound thereby reducing
side-effects.
[0155] Without limiting the scope of this disclosure to a
particular theory of operation, this steady current in the fluid,
known as "acoustic streaming," can be driven by absorption of
acoustic oscillations created by the acoustic waves emitted by the
ultrasound radiating elements. Based on the sequence of activation,
it is possible to create fluid flow in desired directions around
the catheter.
[0156] FIGS. 17A-D illustrates potential sequencing and
synchronization of activation of ultrasonic radiating elements
within an ultrasound catheter 1700 placed within a target site 1701
of the body including, but not limited to, a cavity (e.g., the
cranial cavity, a blood vessel, or a self-created cavity e.g., a
surgical incision) or in other a tissue (e.g., a tumor, brain
tissue etc.). The methods and apparatuses described below can be
used in combination with the embodiments described above with
reference to FIGS. 1A-16E. In particular, the sequencing and
synchronization of the ultrasonic radiating elements can be used in
in the embodiments described above to direct flow of a therapeutic
compound. In an exemplary embodiment, the sequencing and
synchronization can be performed by the processing unit 94 (as
shown in FIG. 14) which may additionally include logic configured
to allow the processing unit 94 to selectively activate ultrasonic
radiating elements in an embodiment of the ultrasound catheter
(e.g., the embodiments described above). In the illustrated
embodiment, the ultrasound catheter 1700 includes ultrasound
radiating elements 1702, 1704, 1706, 1708, 1710, and 1712 and
passages 1714, 1718, 1722, and 1726. Passages 1714, 1718, 1722, and
1726 are in fluid communication with lumen 1716, 1720, 1724, and
1728 respectively with each lumen being in fluid communication with
a separate port at a proximal end of the catheter. Ultrasound
radiating elements 1702, 1704, 1706, 1708, 1710 and 1712 can be
separate ultrasound radiating units or separate portions of a
single ultrasound radiating unit. Some or all of the passages 1714,
1718, 1722, and 1726 can be configured to allow therapeutic
compounds, input into ports at the proximal end of the device, to
pass through and out of these holes. Such therapeutic compounds can
be used to treat diseases or ailments in any part of the body such
as vascular occlusions, blood clots, cancer, and any other type of
disease or ailment. Alternatively, some or all of the passages
1714, 1718, 1722, and 1726 can be configured to remove fluid from
the implantation location, through the corresponding lumen, and out
of the ports at a proximal end of the catheter. As such, some
passages 1714, 1718, 1722, and 1726 can be used to deliver
therapeutic compounds to the target location while others can be
used to remove fluids from the target location. In other
embodiments, fewer or greater numbers of radiating elements and/or
drainage holes can be used (see e.g., the embodiments described
above with respect to FIGS. 1A-16E). Furthermore, in other
embodiments, the radiating elements 1702, 1704, 1706, 1708, 1710,
and 1712 may be placed closer to or at the center of the ultrasound
catheter 1700. In some embodiments, the passages can be coupled to
a common or single lumen.
[0157] In one embodiment, the ultrasound radiating elements 1702,
1704, 1706, 1708, 1710, and 1712 are activated in sequence such
that the pattern of pressure waves created by activation of
individual elements creates a flow throughout the target area. For
example, in one embodiment as shown in FIG. 17B, a first pair of
ultrasound radiating elements 1702 and 1704 are activated for a
first interval at a first point in time which create a first
pressure wave 1730b. This pressure wave causes fluid to flow in the
directions shown by arrows 1732b and 1734b. Fluid to the left of
element 1702 and 1704 moves in the direction of arrow 1732b while
fluid to the right of element 1702 and 1704 moves in the direction
of arrow 1734b. Subsequently, as shown in FIG. 17C, a second pair
of ultrasound radiating elements 1706 and 1708 are activated for a
second interval at a second point in time creating a second
pressure wave 1730c. This causes fluid to flow in the direction of
arrows 1732c and 1734c. Finally, as shown in FIG. 17D, a third pair
of ultrasound radiating elements 1710 and 1712 are activated for a
third interval at a third point in time creating third pressure
wave 1730d. This causes fluid to flow in the direction of arrows
1732d and 1734d. So long as the elements are activated for a
sufficient interval, fluid containing the therapeutic compounds can
flow distal the subsequent pair of elements. Therefore, activation
of a subsequent pair of elements causes the fluid containing the
therapeutic compounds to flow even further distal the second pair
of elements.
[0158] It should be apparent to one of skill in the art that the
length of the intervals and the delay between the points in time
can be configured based on the desired flow rate and the
characteristics of the fluid. Therefore, in some embodiments, the
intervals are such that there is no overlap in activation between
subsequent pairs of ultrasound radiating elements. In other
embodiments, the intervals are such that there is some overlap in
activation between subsequent pairs of ultrasound radiating
elements such that, at least during one point in time, two pairs
are simultaneously activated. By activating the ultrasound
radiating elements in this sequence, pressure waves can cause fluid
to flow from the location of the first pair of ultrasound radiating
elements 1702 and 1704 to a distal end of the ultrasound catheter
1700. This flow path can potentially reduce the likelihood of fluid
containing the therapeutic compounds to travel against the desired
flow path (i.e., backflow) thereby delivering a more substantial
amount of the therapeutic compounds to the target area and reducing
the amount of therapeutic compounds entering areas not targeted for
treatment. It should be appreciated by one of skill in the art that
increasing the number of ultrasound radiating elements around the
circumference of the ultrasound catheter 1700 can likely provide a
more advantageous safeguard against backflow.
[0159] In another embodiment, the activation of ultrasound
radiating elements 1702, 1704, 1706, 1708, 1710, and 1712 may be
differed to change flow patterns around the ultrasound catheter.
For example, the ultrasound radiating elements may be activated in
sequence in the following order--1702, 1706, 1710, 1712, 1708, and
1704--to create a flow path in which fluid along the top of the
ultrasound catheter 1700 flows in a direction from the proximal end
to the distal end whereas fluid along the bottom of the ultrasound
catheter 1700 flows in a direction from the distal end to the
proximal end. Such a flow pattern can be advantageous, for example,
when the top passages 1714 and 1722 are configured to deliver
therapeutic compounds to the target area and bottom passages 1718
and 1726 are configured to remove fluid, such as toxic product,
from the target area. Fluid flow across the top passages 1714 and
1722 can cause therapeutic compounds to pass through and out of the
top passages 1714 and 1722. Other activation sequences are
contemplated which can alter the flow characteristics around the
ultrasound catheter 1700. As such, the amount of positive pressure
used at the top passages 1714 and 1722 can be advantageously
reduced while still being delivered fully to the target area and
the amount of negative pressure used at the bottom passages 1718
and 1726 can also be advantageously reduced while still removing
the same amount of fluid. This can reduce the likelihood of
injuries being sustained by tissue proximate the ultrasound
catheter 1700 caused either by positive pressure or by negative
pressure.
[0160] In yet another embodiment, the activation of ultrasound
radiating elements 1702, 1704, 1706, 1708, 1710, and 1712 can be
synchronized with delivery of therapeutic compounds through
passages 1714, 1718, 1722, and 1726. In one embodiment, no pumps
are attached to the separate lumen 1716, 1720, 1724, and 1728.
Rather, activation of the ultrasound radiating elements can be used
to generate a flow pattern which could subsequently cause
therapeutic compounds to pass through the lumen and out of the
corresponding passages. In another embodiment, pumps are attached
to the separate lumen and are used to eject therapeutic compounds
out of the passages. Activation of ultrasound radiating elements
can be synchronized with the activation of pumps such that
therapeutic compounds delivered through different passages can be
delivered to different target locations. In one non-limiting
embodiment, a pump can cause a first therapeutic compound to pass
out of passages 1714. Subsequent to this, ultrasound radiating
element 1702 can then be activated. In sequence, element 1706 can
then be activated followed by element 1710 such that the first
therapeutic compound is delivered to a location that is distal of
element 1710. In this embodiment, a pump can also cause a second
therapeutic compounds to pass out of passage 1722. In this
embodiment, only element 1706 is activated such that the second
therapeutic compound is delivered to a location proximal the
delivery location of the first therapeutic compound. As should be
apparent to one of skill in the art, a greater number of radiating
elements along the length of the ultrasound catheter can be used to
provide greater control over the final location of the therapeutic
compounds.
[0161] Devices and techniques can be used with the ultrasound
radiating elements as herein described to control the transmission
of ultrasound energy. Such devices and techniques can be used, for
example, to reduce the efficiency of ultrasound energy in certain
directions. Moreover, such devices and techniques can be used to
focus the output of ultrasound in a desired direction.
[0162] FIGS. 18A-18C illustrate an embodiment of an ultrasound
assembly 1810 having a cavity 1830 which when used with the
embodiments described above can reduce the portion of ultrasound
energy transmitted in a direction towards the cavity 1830 while
increasing the portion of ultrasound energy transmitted in a
direction away from the cavity 1830. This can increase the
efficiency in delivering ultrasound energy produced from these
sections in desired areas. Moreover, this can reduce the flow
effects of the ultrasound energy on fluid contained within the
catheter such as fluid flow through lumens of the catheter. It
should be understood that the cavity 1830 as herein described can
be used for any of the ultrasound catheters and assemblies as
herein described.
[0163] The ultrasound assembly 1810 can include an elongated body
1812 having a lumen 1813 and external surface 1814. A plurality of
spacers 1816 can be positioned over the external surface 1814 of an
elongated body 1812 and a member 1818 can be positioned over at
least a portion of the spacers 1816. The ultrasound assembly 1810
can also include an ultrasound transducer 1820 with an external
side 1822 and an internal side 1824 between a first end 1826 and a
second end 1828. In some embodiments, the ultrasound transducer
1820 can be positioned over the member 1818 and can surround the
member 1818. In some embodiments, the ultrasound transducer 1820
can also only partially surround the member 1818. Suitable
materials for the member 1818 include, but are not limited to,
polyimide, polyester and nylon. A suitable ultrasound transducer
1820 includes, but is not limited to, PZT-4D, PZT-4, PZT-8 and
various piezoceramics.
[0164] The internal side 1824 of the ultrasound transducer 1820,
the spacers 1816 and the member 1818 each define a portion of a
chamber 1830 between the internal side 1824 of the ultrasound
transducer 1820 and the external surface 1814 of the elongated body
1812. The chamber 1830 can preferably have a height between about
0.25 .mu.m to about 10 .mu.m, more preferably between about 0.50
.mu.m to about 5 .mu.m, and most preferably between about 1 .mu.m
to about 1.5 .mu.m. The chamber 1830 can preferably have a width
between about 12 .mu.m to about 2500 .mu.m, more preferably between
about 25 .mu.m to about 250 .mu.m, and most preferably between
about 25 .mu.m to about 125 .mu.m. Of course, other heights and
widths for chamber 1830 can also be used. The member 1818 can
extend beyond the first end 1826 and/or the second end 1828 of the
ultrasound transducer 1820. Additionally, the spacers 1816 can be
positioned beyond the ends of the ultrasound transducer 1820. As a
result, the chamber 1830 can extend along the longitudinal length
of the ultrasound transducer 1820 to increase the portion of the
ultrasound transducer 1820 which is adjacent to the chamber
1830.
[0165] The chamber 1830 can contain a low acoustic impedance
medium. The low acoustic impedance material within the chamber can
reduce the portion of ultrasound energy which is transmitted
through the chamber 1830. Suitable low acoustic impedance media
include, but are not limited to, fluids such as helium, argon, air
and nitrogen and/or solids such as silicone and rubber. The chamber
1830 can also be evacuated. Suitable pressures for an evacuated
chamber 1830 include, but are not limited to, negative pressures to
-760 mm Hg. Generally, a low acoustic impedance medium has an
acoustic impedance less than about 1.7 Megarayls, preferably
between about 0 Megarayls to about 0.7 Megarayls, and more
preferably between about 0 Megarayls to about 0.4 Megarayls. Of
course, acoustic impedance mediums having acoustic impedances
outsides of these ranges can also be used. It should be understood
that other methods of creating a chamber 1830 are contemplated
including manufacturing a monolithic catheter having a chamber 1830
formed therein. Additional embodiments of such cavities as well as
catheters and ultrasound assemblies can be found in U.S. Pat. No.
6,676,626, issued Jan. 13, 2004, which is hereby expressly
incorporated by reference.
[0166] While the chamber 1830 which can be filled with a low
acoustic impedance medium to reduce transmission of ultrasound
energy through the chamber 1830, it should be understood that
chamber 1830 need not be filled with a specific material. Moreover,
while the chamber 1830 has been described as having spacers 1816 at
each end of the chamber 1830, spacers 1816 need not be attached at
each end. For example, the chamber 1830 can be formed between the
elongated body 1812 and the member 1818 with the member 1818
directly attached to the elongate body 1812.
[0167] Transmission of ultrasound energy can be affected
introducing other types of gaps, including microscopic gaps,
between separate components of the ultrasound catheter. For
example, in some embodiments, one or more gaps can be created by
delaminating one or more material layers of a component of the
ultrasound catheter. In some embodiments, the gap is not filled
with any material after delamination of these layers. In other
embodiments, the gaps can be filled with an additional material
after delamination. Such delamination can result in one or more
gaps having heights lesser than those described above with respect
to the chamber 1830.
[0168] The gap can function similar to chamber 1830 and cause
inefficient transmission of ultrasound through the portions of the
ultrasound catheter having such gaps. In some embodiments, the gap
can be formed on portions of the ultrasound catheter between the
ultrasound radiating element and the central portion of the
ultrasound catheter. Accordingly, the amount of ultrasound energy
transmitted towards the interior of the ultrasound catheter can be
reduced and the amount of ultrasound energy transmitted away from
the interior of the ultrasound catheter can be enhanced. Of course,
other configurations of one or more gaps can also be chosen to
alter the characteristics of ultrasound energy and enhance the
directionality of this energy. This can be particularly beneficial
to create an ultrasound catheter having more precise targeting
and/or a more efficient device.
[0169] While the foregoing detailed description has set forth
several exemplary embodiments of the apparatus and methods of the
present invention, it should be understood that the above
description is illustrative only and is not limiting of the
disclosed invention. It will be appreciated that the specific
dimensions and configurations disclosed can differ from those
described above, and that the methods described can be used within
any biological conduit within the body.
Listing of Embodiments
[0170] 1. A method of increasing the efficacy of drugs delivered to
a target location, comprising the steps of:
[0171] providing an ultrasound catheter having one or more
ultrasound radiating elements and one or more drainage holes
configured to allow one or more therapeutic compounds to pass
through and out of the one or more drainage holes;
[0172] passing a therapeutic compound out of the drainage hole at
the target location; and activating the one or more ultrasound
radiating elements;
[0173] wherein activating the one or more ultrasound radiating
elements is configured to increase the efficacy of the therapeutic
compound.
[0174] 2. The method of Embodiment 1, wherein the ultrasound
radiating element is configured to increase the permeability of the
targeted area.
[0175] 3. The method of Embodiment 1, wherein the step of
activating the one or more ultrasound radiating elements
additionally comprises activating the one or more ultrasound
radiating elements in a sequence configured to cause fluid to flow
in a desired direction.
[0176] 4. The method of Embodiment 3, wherein the fluid flows
towards the target area.
[0177] 5. The method of Embodiment 3, wherein the fluid flows away
from the target area.
[0178] 6. The method of Embodiment 4, wherein the ultrasound
catheter further comprises one or more pumps in fluid communication
with the one or more drainage holes and wherein the step of
activating the one or more ultrasound radiating elements
additionally comprises synchronizing the activation of the one or
more ultrasound radiating elements with the one or more pumps.
[0179] 7. The method of Embodiment 6, wherein synchronization of
the activation of the one or more ultrasound radiating elements is
configured to transport drugs to different target areas.
[0180] 8. The method of Embodiment 6, wherein synchronization of
the activation of the one or more ultrasound radiating elements is
configured to at least partially causing the one or more
therapeutic compounds to pass through and out of the one or more
drainage holes.
[0181] 9. The method of Embodiment 3, wherein synchronization of
the activation of the one or more ultrasound radiating elements is
configured to at least partially causing the one or more
therapeutic compounds to pass through and out of the one or more
drainage holes.
* * * * *