U.S. patent application number 11/255785 was filed with the patent office on 2006-06-08 for ultrasound enhanced central venous catheter.
Invention is credited to Curtis Genstler, Douglas R. Hansmann, Thomas O. McNamara, Peter R. Rule, Dominic D. Vogt.
Application Number | 20060122507 11/255785 |
Document ID | / |
Family ID | 33310932 |
Filed Date | 2006-06-08 |
United States Patent
Application |
20060122507 |
Kind Code |
A1 |
Rule; Peter R. ; et
al. |
June 8, 2006 |
Ultrasound enhanced central venous catheter
Abstract
A central venous catheter comprises an ultrasound assembly. In
one arrangement, the radiating member is used to remove a blockage
from the central venous catheter. In another arrangement, inserting
an ultrasound assembly into a central venous catheter. The
ultrasound assembly comprises an ultrasound radiating member
mounted on an elongate support structure. The method further
comprises positioning the ultrasound assembly within the central
venous catheter such that the ultrasound radiating member is
adjacent to a deposited material formed on a portion of the central
venous catheter. The method further comprises supplying an
electrical current to the ultrasound radiating member to expose the
deposited material to ultrasonic energy. The method further
comprises passing a therapeutic compound through the central venous
catheter to expose the deposited material to the therapeutic
compound simultaneously with ultrasonic energy.
Inventors: |
Rule; Peter R.; (Los Altos,
CA) ; Hansmann; Douglas R.; (Bainbridge Island,
WA) ; Vogt; Dominic D.; (Redmond, WA) ;
Genstler; Curtis; (Snohomish, WA) ; McNamara; Thomas
O.; (Los Angeles, CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET
FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
33310932 |
Appl. No.: |
11/255785 |
Filed: |
October 20, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/US04/12362 |
Apr 22, 2004 |
|
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11255785 |
Oct 20, 2005 |
|
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60464673 |
Apr 22, 2003 |
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Current U.S.
Class: |
600/438 |
Current CPC
Class: |
B08B 9/00 20130101; A61B
17/2202 20130101; A61M 2025/0019 20130101; B08B 2209/005 20130101;
A61B 2090/701 20160201; A61B 90/70 20160201; B08B 9/043
20130101 |
Class at
Publication: |
600/438 |
International
Class: |
A61B 8/00 20060101
A61B008/00 |
Claims
1. An apparatus comprising: an elongate central venous catheter
having a distal region configured for insertion into a patient's
vasculature, and a fluid delivery lumen configured to allow a fluid
to be delivered through the central venous catheter to the
patient's vasculature; an ultrasound assembly configured to be
positioned adjacent to the central venous catheter distal region;
and a temperature sensor configured to measure a temperature in a
region adjacent to the ultrasound assembly.
2. The apparatus of claim 1, wherein the ultrasound assembly
comprises an ultrasound radiating member mounted on an elongate
support structure configured to be passed through the central
venous catheter.
3. The apparatus of claim 1, wherein the ultrasound assembly
comprises an ultrasound radiating member mounted on the central
venous catheter.
4. The apparatus of claim 1, wherein the ultrasound assembly
comprises a plurality of ultrasound radiating members.
5. The apparatus of claim 1, wherein the temperature sensor is a
thermocouple.
6. The apparatus of claim 1, wherein central venous catheter has an
outer diameter between approximately 6 French and approximately 14
French.
7. A method for removing a blockage from a central venous catheter
comprising: inserting an ultrasound assembly into a central venous
catheter, the ultrasound assembly comprising an ultrasound
radiating member mounted on an elongate support structure;
positioning the ultrasound assembly within the central venous
catheter such that the ultrasound radiating member is adjacent to a
deposited material formed on a portion of the central venous
catheter; supplying an electrical current to the ultrasound
radiating member to expose the deposited material to ultrasonic
energy; and passing a blockage removal compound through the central
venous catheter to expose the deposited material to the blockage
removal compound simultaneously with ultrasonic energy.
8. The method of claim 7, wherein the ultrasound assembly comprises
a plurality of ultrasound radiating members.
9. The method of claim 7, wherein the ultrasound assembly comprises
a plurality of ultrasound radiating members, and wherein the
plurality of ultrasound radiating members are individually
controllable.
10. The method of claim 7, further comprising measuring a
temperature in a region adjacent to the ultrasound radiating
member.
11. The method of claim 7, further comprising: measuring a
temperature in a region adjacent to the ultrasound radiating
member; and adjusting the electrical current supplied to the
ultrasound radiating member based on the measured temperature.
12. The method of claim 7, wherein the blockage removal compound is
also passed through the central venous catheter before ultrasonic
energy is supplied to the deposited material.
13. A method comprising exposing a deposited material formed on a
central venous catheter to ultrasonic energy while the central
venous catheter is positioned in a patient and exposing the
deposited material formed on the central venous catheter to a
blockage removal compound while the central venous catheter is
positioned in a patient.
14. The method of claim 13, wherein the blockage removal compound
comprises an antibacterial solution.
15. The method of claim 13, wherein the ultrasonic energy has a
frequency between about 20 kHz and about 20 MHz.
16. The method of claim 13, the blockage removal compound comprises
a thrombus removing agent.
17. The method of claim 13, wherein the blockage removal compound
is also delivered to the deposited material before ultrasonic
energy is supplied to the deposited material.
18. The method of claim 13, wherein the ultrasonic energy is also
delivered to the deposited material after termination of the
delivery of blockage removal compound to the deposited
material.
19. The method of claim 13, wherein the ultrasonic energy is
delivered from an ultrasound assembly positioned within a central
lumen of the central venous catheter.
20. The method of claim 13, wherein the ultrasonic energy is
delivered from an ultrasound assembly positioned within a central
lumen of the central venous catheter, and wherein the ultrasound
assembly comprises an ultrasound radiating member mounted on an
elongate support structure.
21. The method of claim 13, wherein the ultrasonic energy is
delivered from an ultrasound assembly positioned within a central
lumen of the central venous catheter, and wherein the ultrasound
assembly comprises a plurality of ultrasound radiating members
mounted on an elongate support structure.
22. The method of claim 13, further comprising measuring a
temperature adjacent to the deposited material.
23. The method of claim 13, further comprising: measuring a
temperature adjacent to the deposited material; and adjusting the
amount of ultrasonic energy delivered to the deposited material
based on the measured temperature.
24. The method of claim 13, wherein the ultrasonic energy is
delivered from an ultrasound radiating member embedded in an
elongate body of the central venous catheter.
25. The method of claim 13, wherein the blockage removal compound
is delivered to the deposited material through the central venous
catheter.
26. The method of claim 13, wherein the blockage removal compound
is delivered to the deposited material through a delivery lumen
formed integrally with the central venous catheter.
27. A method for removing a deposited material from a catheter
comprising: supplying a therapeutic compound to the deposited
material; exposing the deposited material to ultrasonic energy
generated by an ultrasound radiating member positioned within the
catheter; and measuring a temperature on the catheter to provide an
indication of progression of the removal of the deposited material
from the catheter.
28. The method of claim 27, wherein the therapeutic compound
comprises an antibacterial solution.
29. The method of claim 27, wherein the deposited material is
exposed to ultrasonic energy and therapeutic compound
simultaneously.
30. The method of claim 27, wherein the catheter comprises a
central venous catheter.
31. The method of claim 27, wherein the ultrasound radiating member
is positioned within a central lumen of the catheter.
32. The method of claim 27, wherein the ultrasound radiating member
is embedded within an elongate body of the catheter.
33. The method of claim 27, further comprising adjusting the amount
of ultrasonic energy delivered to the deposited material based on
the measured temperature.
Description
PRIORITY CLAIM
[0001] This is a continuation of International Application
PCT/US2004/012362 (filed 22 Apr. 2004), which claims the benefit of
U.S. Provisional Application No. 60/464,673 (filed 22 Apr. 2003),
the entire disclosure of which is hereby incorporated in its
entirety by reference herein.
FIELD OF THE INVENTION
[0002] The present invention relates generally to use of an
ultrasound assembly with a central venous catheter, and more
specifically to using ultrasonic energy to enhance the efficacy of
a central venous catheter.
BACKGROUND OF THE INVENTION
[0003] The term "central venous catheter" or "CVC," refers
generally, in addition to its ordinary meaning, to a catheter that
has been inserted into a vein of the vascular system. Although CVCs
have many varied applications, CVCs are frequently used when a
patent requires frequent or continuous injections of medications or
fluids for nutritional support. Common CVC applications include,
but are not limited to, chemotherapy, long-term intravenous
antibiotics, long-term pain medications, long-term intravenous
nutrition, frequent blood draws, dialysis, and plasmapheresis.
Therefore, a CVC can be used to deliver fluids to, or extract
fluids from, the cardiovascular system.
[0004] In a wide variety of medical applications, the tip of a CVC
is advanced into the superior vena cava ("SVC") from an upper
extremity jugular vein or subclavian vein. Other approaches and
deployment locations can be used in other applications. CVCs are
used in a wide variety of applications; one common application is
in the provision of a therapeutic compound into a patient's
vascular system.
[0005] When a CVC is used for an extended period, blockages can
form within the CVC, or can form outside the CVC in the vein
between the CVC and the blood vessel wall. For example, a blockage
inside the CVC can be caused by drug precipitate or thrombus.
Additionally, platelet aggregation or fibrin deposition can
completely encase the surface of the CVC, or can form a sac around
the distal end of the CVC. Conventionally, such blockages were
removed, if at all, either by removing and replacing/cleaning the
CVC or while the CVC is in place passing a clot-dissolving compound
through the CVC to dissolve the blockage. However, removing the CVC
catheter is generally not desirable and introducing a large
quantity of clot-dissolving compounds into the vascular system can
have negative side effects.
SUMMARY OF THE INVENTION
[0006] Therefore, a device capable of removing blockages or other
materials from within or around a CVC, without removing the CVC
and/or causing the negative side effects associated with the
introduction of large quantities of clot-dissolving compounds into
the vascular system, has been developed. In addition, an improved
CVC that is capable of being outfitted with an ultrasound assembly
is also provided.
[0007] Accordingly, one embodiment of the present invention
comprises an elongate central venous catheter. The elongate central
venous catheter having a distal region configured for insertion
into a patient's vasculature. The elongate central venous catheter
also has a fluid delivery lumen configured to allow a fluid to be
delivered through the central venous catheter to the patient's
vasculature. The apparatus further comprises an ultrasound assembly
configured to be positioned adjacent to the central venous catheter
distal region. The apparatus further comprises a temperature sensor
configured to measure a temperature in a region adjacent to the
ultrasound assembly.
[0008] According to one embodiment of the present invention, a
method for removing a blockage from a central venous catheter
comprises inserting an ultrasound assembly into a central venous
catheter. The ultrasound assembly comprises an ultrasound radiating
member mounted on an elongate support structure. The method further
comprises positioning the ultrasound assembly within the central
venous catheter such that the ultrasound radiating member is
adjacent to a deposited material formed on a portion of the central
venous catheter. The method further comprises supplying an
electrical current to the ultrasound radiating member to expose the
deposited material to ultrasonic energy. The method further
comprises passing a blockage removal compound through the central
venous catheter to expose the deposited material to the blockage
removal compound simultaneously with ultrasonic energy.
[0009] According to another embodiment of the present invention, a
method comprises exposing a deposited material formed on a central
venous catheter to ultrasonic energy while the central venous
catheter is positioned in a patient and exposing the deposited
material to a blockage removal compound while the central venous
catheter is positioned in a patient.
[0010] According to another embodiment of the present invention, a
method for removing a deposited material from a catheter comprises
supplying a blockage removal compound to the deposited material.
The method further comprises exposing the deposited material to
ultrasonic energy generated by an ultrasound radiating member
positioned within the catheter. The method further comprises
measuring a temperature on the catheter to provide an indication of
progression of the removal of the deposited material from the
catheter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Exemplary embodiments of the CVCs disclosed herein, and
exemplary methods for using said CVCs 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.
[0012] FIG. 1 is a perspective view of an exemplary embodiment of a
distal end of a CVC structure having a fibrin sleeve formed
thereover.
[0013] FIG. 2 is a perspective view of an exemplary embodiment of a
distal end of a CVC structure having a intraluminal thrombus or
clot formed therein.
[0014] FIG. 3 is a cross-sectional view of a CVC disposed within a
patient's vasculature, wherein an ultrasound assembly is positioned
within the CVC.
[0015] FIG. 4 is a side view of the ultrasound assembly positioned
within the CVC of FIG. 3.
[0016] FIG. 5A is a cross-sectional view of a CVC having an
embedded ultrasound radiating member.
[0017] FIG. 5B is a cross-sectional view of the CVC of FIG. 5A,
taken along line 5B-5B.
[0018] FIG. 6 is a perspective illustration of a CVC elongate body
having a suture wing in the catheter proximal region.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] As described above, material can be deposited in and around
a CVC during extended use. Such deposition can adversely affect
operation of the CVC, making it difficult or impossible to deliver
therapeutic compounds or other materials through the CVC to the
patient's vasculature. Therefore, improvements have been developed
to mitigate the adverse affects associated with material deposition
in or around a CVC. Exemplary embodiments of these improvements are
disclosed herein.
[0020] A wide variety of CVC structures exist, and the improvements
described herein are not intended to be limited to a particular CVC
structure. Rather, the improvements are described in connection
with a generic CVC structure, with the understanding that these
improvements are not limited to use with that particular CVC
structure. For example, CVCs can be configured with multiple
lumens, rather than a single central lumen. For example, in one
embodiment, a CVC catheter has been one lumen and five lumens.
Multiple lumens can be used for introducing and withdrawing fluids
and devices, such as a guidewire. Likewise, the improvements
disclosed herein can be used with catheters other than CVC
catheters, such as with catheters configured to be inserted into
other regions of the vascular system.
[0021] Accordingly, the term "central venous catheter" refers
generally, in addition to its ordinary meaning, to a catheter that
has been inserted into a vein of the vascular system. In a wide
variety of medical applications, the tip of a CVC is advanced into
the superior vena cava ("SVC") from an upper extremity jugular vein
or subclavian vein. Other approaches and deployment locations can
be used in other applications. CVCs are used in a wide variety of
applications; one common application is in the provision of a
therapeutic compound into a patient's vascular system.
[0022] As used herein, the term "therapeutic compound" refers
broadly, without limitation, to a drug, medicament, dissolution
compound, genetic material or any other substance capable of
effecting physiological functions. Additionally, any mixture
comprising any such substances is encompassed within this
definition of "therapeutic compound", as well as any substance
falling within the ordinary meaning of these terms.
[0023] As used herein, the term "ultrasound energy" is a broad term
and is used in its ordinary sense and means, without limitation,
mechanical energy transferred through pressure or compression waves
with a frequency greater than about 20 kHz. In one embodiment, the
waves of the ultrasound energy have a frequency between about 500
kHz and 20 MHz and in another embodiment between about 1 MHz and 3
MHz. In yet another embodiment, the waves of the ultrasound energy
have a frequency of about 3 MHz.
[0024] As used herein, the term "catheter" is a broad term and is
used in its ordinary sense and means, without limitation, an
elongate flexible tube configured to be inserted into the body of a
patient, such as, for example, a body cavity, duct or vessel.
[0025] A distal region of a generic CVC structure is illustrated in
FIGS. 1 and 2. As illustrated, a generic CVC comprises a flexible,
elongate body 100 that forms a central lumen 110. The elongate body
100 has an outer surface 120, and is dimensioned to facilitate its
passage through the peripheral vascular system. Generally, suitable
materials and dimensions for the CVC can be selected readily based
on the natural and anatomical dimensions of the particular
treatment site and percutaneous access site. Examples of suitable
CVC materials include, but are not limited to, extruded
polytetrafluoroethylene ("PTFE"), polyethylenes ("PE"), polyamides
and other similar materials. In CVCs configured for long term
implantation, soft materials such as urethanes and silicones can be
used to form the catheter body. Additionally, a CVC optionally
includes a coating, such as a silver coating, to reduce the
likelihood of infection.
[0026] In certain embodiments, the proximal region of the CVC is
reinforced by braiding, mesh or other internal or external
structures to provide increased kink resistance and pushability,
thereby facilitating passage of the CVC through the patient's
vasculature. In other embodiments, the CVC body can be reinforced
by including a stylet in the CVC body, which serves to maintain
rigidity of the CVC during passage through the patient's
vasculature. In such embodiments, a thin, elongate wire can be used
as a stylet.
[0027] In one embodiment, a CVC has an outer diameter between
approximately 6 French and approximately 14 French.
[0028] A CVC optionally includes a suture wing or cuff in the
catheter proximal region, which can be used to attach the proximal
end of the CVC to the patient. For example, FIG. 6 illustrates a
CVC elongate body 100 having a suture wing 190 in the catheter
proximal region. The suture wing 190 can be constructed of a
material suitable for attachment to a patient's body. In other
embodiments, a cuff that may be made out of a material such as
Dacron can be used. As illustrated, the CVC optionally includes a
proximal hub 195 that can be used to supply fluid, such as a
therapeutic compound, through a CVC lumen.
[0029] As described above, material often deposits in and around a
CVC that has been positioned within a patent's vasculature for an
extended period of time. Such blockages can be caused by
therapeutic compound precipitate, platelet aggregation, or fibrin
deposition. For example, FIG. 1 illustrates the formation of a
fibrin sleeve 130 at the distal region of the CVC, and FIG. 2
illustrates the formation of a thrombus or clot 140 within the CVC
central lumen 110. Either of these conditions can adversely affect
the operation of the CVC, making it difficult or impossible to pass
therapeutic compounds or other materials through the CVC and into
the patient's vasculature.
[0030] The blockages described above, whether formed inside or
outside the CVC, often become coated with a protein substance that
provides a shield for bacteria. This protein "shield" makes it
difficult to treat bacterial growth within the blockage using
antibiotics. Therefore, because of the bacteria-resistant shield,
bacterial growth within the blockage can proliferate, increase the
size of the blockage, and cause infection. This process is a
significant contributing factor to upper extremity deep vein
thrombosis ("DVT").
[0031] An obstruction within a CVC can be cleaned while in the
patient by using a brush and a small amount of a therapeutic
compound, such as a lytic solution. However, it is difficult or
impossible to clean the outer surface of a CVC using a brush. In an
exemplary embodiment, ultrasonic energy is used to clean one or
more portions of a CVC, such as the central lumen 110, the elongate
body outer surface 120, or both. Preferably, the ultrasonic energy
is used in combination with a blockage removal compound to clean
the one or more portions of the CVC. In such embodiments, the
ultrasonic energy is preferably configured to enhance the
therapeutic effects and/or delivery of the blockage removal
compound. For example, the ultrasonic energy can be used to
penetrate the protein shield that often covers an occlusion,
thereby allowing a blockage removal compound, such as a solution
containing an antibacterial agent and/or a thrombus removing
compound (e.g., Heparin, Uronkinase, Streptokinase, TPA and other
thrombolytics or anti-thrombus agents) to be delivered directly to
the occlusion. The ultrasonic energy can be delivered independent
of, or simultaneously with, the blockage removal compound. In
another use of the system disclosed herein, a CVC is exposed to
ultrasonic energy periodically to reduce or prevent accumulation of
protein thereon. Preferably, in these embodiments, the ultrasound
and/or the blockage removal compound applied while the central
venous catheter is positioned in a patient.
[0032] One system for using ultrasonic energy to clean a CVC is
illustrated in FIG. 3. FIG. 3 is a cross-sectional illustration of
the elongate body 100 of a CVC that has been positioned within a
patient's vasculature 150. As illustrated, this system can be used
to clean deposited material from within the CVC outer surface 120
(such as a fibrin sleeve 130), or from the CVC inner lumen 110
(such as a thrombus or clot 140), or both. Similarly, this system
can be used to clean deposited material from the distal end of the
CVC, or from an intermediate position on the CVC.
[0033] Still referring to FIG. 3, to expose the deposited material
to ultrasonic energy, an ultrasound assembly 160 is inserted into,
and passed through the elongate body 100. The ultrasound assembly
160, a side view of which is illustrated in FIG. 4, comprises an
ultrasound radiating member 165 positioned at the distal end of an
elongate support member 167. In an exemplary embodiment, the
ultrasound radiating member comprises lead zirconate titanate
("PZT"), although other materials capable of generating mechanical
vibrations when exposed to electronic signals can also be used.
Although the ultrasound assembly 160 illustrated in FIG. 4
comprises one ultrasound radiating member 165, in a modified
embodiment, multiple ultrasound radiating members are positioned
along the elongate support member 167. The multiple ultrasound
radiating members can be controlled independently of each other. In
another modified embodiment, the ultrasound radiating member is
mechanically connected to an ultrasound oscillator positioned at
the proximal end of the CVC, outside the patient's body; additional
information regarding this configuration is provided U.S. Pat. No.
6,524,251, issued on 25 Feb. 2003, and entitled "Ultrasonic Device
for Tissue Ablation and Sheath for Use Therewith."
[0034] Additional information regarding controlling a plurality of
ultrasound radiating members are provided in U.S. Patent
Application Publication US 2004/0024347 A1, published on 5 Feb.
2004 and entitled "Catheter with Multiple Ultrasound Radiating
Members," the entire disclosure of which is hereby incorporated
herein by reference herein. Additional information regarding
mounting one or more ultrasound radiating members on an elongate
support structure are provided in U.S. patent application Ser. No.
10/751,843, filed on 5 Jan. 2004 and entitled "Ultrasonic Catheter
with Axial Energy Field," the entire disclosure of which is hereby
incorporated by reference herein.
[0035] A temperature sensor 169 is optionally positioned in a
distal region of the elongate support member 169. In other
embodiments, the temperature sensor 169 is positioned directly on
the ultrasound radiating member 165. In such embodiments, the
ultrasound radiating member 165, and optionally the temperature
sensor 169, are electrically connected to control circuitry at a
proximal end of the ultrasound assembly 160. The temperature sensor
can be used to monitor and control the progression of the cleaning
procedure. In particular, when removing a blockage from within or
around a CVC, a decrease in the temperature at the treatment site
can indicate that the blockage has been at least partially removed
or dissolved, and that flow has been at least partially
reestablished at the treatment site. In addition, the temperature
sensor may be used to determine that the radiating member is
positioned 165 within the blockage. Additional information
regarding using temperature measurements to monitor the progression
of an ultrasound-enhanced treatment are provided in U.S. Patent
Application Publication 2003/0220568 A1, published on 27 Nov. 2003
and entitled "Blood Flow Reestablishment Determination," as well as
in U.S. Provisional Pat. Applications Nos. 60/540,900 (filed 29
Jan. 2004) and 60/540,703 (filed 30 Jan. 2004); the entire
disclosure of these three applications is hereby incorporated by
reference herein.
[0036] As described above, the ultrasound assembly 160 is passed
through the CVC to a point that the ultrasound radiating member 165
is positioned adjacent to a blockage. The blockage is located
either within the CVC elongate body 100, or outside the CVC
elongate body 100. When the ultrasound radiating member 165 is
activated via the control circuitry, ultrasonic vibrations are
generated, thereby exposing the blockage to ultrasonic energy 170.
The blockage can also optionally be exposed to a blockage removal
compound to assist in breaking down or dissolving the blockage,
such as a thrombolytic solution or an antibacterial solution. The
blockage removal compound can be delivered through the CVC itself,
or can be independently supplied to the treatment site by, for
example, a secondary delivery catheter or a delivery lumen formed
integrally with the central venous catheter. In an exemplary
embodiment, the ultrasonic energy enhances the effect of the
blockage removal compound, as described previously.
[0037] In a modified embodiment, the CVC is configured to
facilitate the delivery of ultrasonic energy to blockages that form
on or within the elongate body. For example, in one embodiment, the
elongate body, or optionally only a distal region of the elongate
body, is formed from a material that is substantially transparent
to ultrasonic energy. This configuration advantageously allows
ultrasonic energy generated by an ultrasound radiating member
positioned within the central lumen 110 to pass through the
elongate body 100 and be absorbed by a blockage outside the
CVC.
[0038] The ultrasound radiating member 165 need not be positioned
within the CVC central lumen 110. For example, the ultrasound
assembly can be passed along the outer surface 120 of the CVC in a
region 180 (see FIG. 3) between the patient's vasculature 150 and
the CVC. In another embodiment, the ultrasound radiating member 150
is embedded within the walls of the CVC, as illustrated in FIG. 5A
and 5B.
[0039] As shown in FIGS. 5A and 5B, a modified ultrasound catheter
1100, such as a CVC, generally comprises a multi-component tubular
body 1102 having a proximal region (not shown) and a distal region
1106. Suitable materials and dimensions for the ultrasound catheter
1100 can be selected based on the natural and anatomical dimensions
of the treatment site and of the percutaneous access site.
[0040] The elongate, flexible tubular body 1102 comprises an outer
sheath 1130 that is positioned upon an inner core 1110. In an
exemplary embodiment, the outer sheath 1130 comprises extruded
PEBAX, PTFE, PEEK, PE, polymides, braided polymides and/or other
similar materials that are substantially transparent to ultrasonic
energy. In an exemplary embodiment, the inner core 1110 comprises
polymide or a similar material which, in some embodiments, can be
braided to increase the flexibility of the tubular body 1102. The
inner core 1110 at least partially defines a delivery lumen 1112
that extends longitudinally along the catheter 1100. The delivery
lumen 1112 includes a distal exit port 1114. At a proximal end of
the catheter 1100, the delivery lumen 1112 optionally includes a
Luer fitting to facilitate the passage of a fluid therethrough.
[0041] Still referring to the exemplary embodiment illustrated in
FIGS. 5A and 5B, the tubular body distal region 1106 includes the
ultrasound radiating member 1124. In a modified embodiment, the
ultrasonic energy can be generated by an ultrasound radiating
member that is remote from the treatment site; in such embodiments
the ultrasonic energy can be transmitted via, for example, a wire
to the treatment site, as described above.
[0042] As illustrated in FIGS. 5A and 5B, the ultrasound radiating
member 1124 is configured as a hollow cylinder. As such, the inner
core 1110 extends through the ultrasound radiating member 1124. The
ultrasound radiating member 1124 is secured to the inner core 1110
in a suitable manner, such as with an adhesive. A potting material
is optionally used to further secure the mounting of the ultrasound
radiating member 1124 along the inner core 1110.
[0043] In other embodiments, the ultrasound radiating member 1124
is configured with a different shape. For example, the ultrasound
radiating member can be configured as a solid rod, a disk, a solid
rectangle, a curved element (such as a split cylinder or a curved
rectangular element), or a thin block. In such embodiments. the
ultrasound radiating members are configured with dimensions that
allow them to be embedded within the walls of the CVC, as the
ultrasound radiating member 1124 illustrated in FIGS. 5A and 5B is
embedded in the CVC wall. In other embodiments, wherein the CVC
includes a plurality of lumens formed within the catheter, the
ultrasound radiating members can be embedded in the catheter walls
between the lumens. Because relatively soft materials are often
used to form the CVC body, as described above, the catheter walls
can be configured with a relatively large thickness, thereby
providing ample space to support one or more embedded ultrasound
radiating members. Particular characteristics of the ultrasound
radiating member can be optimized with routine experimentation
based on the particular physical configuration of the CVC body,
including the CVC body materials, dimensions, and shape.
[0044] Still further, the ultrasound radiating member can comprise
a plurality of smaller ultrasound radiating members. However, the
illustrated arrangement advantageously provides for enhanced
cooling of the ultrasound radiating member 1124. For example, in
embodiments wherein a therapeutic compound is delivered through the
delivery lumen 1112, the therapeutic compound advantageously serves
as a heat sink for removing heat generated by the ultrasound
radiating member 1124. In another embodiment, a return path can be
formed in the region 1138 between the outer sheath 1130 and the
inner core 1110, such that coolant from a coolant system can be
directed through the region 1138.
[0045] In a modified embodiment, the CVC is configured to caused
the ultrasonic energy generated by the ultrasound radiating member
to radiate outward from the CVC or inward toward the central lumen.
This can be accomplished, for example, by positioning a chamber of
high ultrasonic impedance material on the opposite side of the
ultrasound radiating member from where the ultrasonic energy is to
be directed. This modification can be made with a variety of
different ultrasound radiating member configurations, including
hollow cylindrical configurations and rectangular configurations.
Additional information regarding the use of a backing to direct
ultrasonic energy is provided is U.S. Pat. No. 6,676,626, issued on
13 Jan. 2004, and entitled "Ultrasound Assembly with Increased
Efficacy," and in U.S. Pat. No. 6,582,392, issued on 24 Jun. 2003,
and entitled "Ultrasound Assembly for Use with a Catheter", which
are hereby incorporated by reference herein in their entirety.
[0046] In an exemplary embodiment, the ultrasound radiating member
1124 is selected to produce ultrasonic energy in a frequency range
that is well suited for removal of deposited material from the
catheter 1100. Suitable frequencies of ultrasonic energy include,
but are not limited to, from about 20 kHz to about 20 MHz. In one
embodiment, the frequency is between about 500 kHz and 20 MHz, and
in another embodiment the frequency is between about 1 MHz and
about 3 MHz. In yet another embodiment, the ultrasonic energy has a
frequency of about 3 MHz.
[0047] As described above, ultrasonic energy is generated from
electrical power supplied to the ultrasound radiating member 1124.
The electrical power can be supplied through a pair wires 1126,
1128 that extend through the tubular body 1102. In an exemplary
embodiment, the electrical wires 1126, 1128 are secured to the
inner core 1110, lay along the inner core 1110, and/or extend
freely in the region 1138 between the inner core 1110 and the outer
sheath 1130. In the illustrated arrangement, the first wire 1126 is
connected to the hollow center of the ultrasound radiating member
1124, while the second wire 1128 is connected to the outer
periphery of the ultrasound radiating member 1124.
[0048] With continued reference to the exemplary embodiment
illustrated in FIG. 5B, the catheter 1100 includes at least one
temperature sensor 1136 along the tubular body distal region 1106.
The temperature sensor 1136 is located on or near the ultrasound
radiating element 1124. Suitable temperature sensors include but
are not limited to, diodes, thermistors, thermocouples, resistance
temperature detectors ("RTDs"), and fiber optic temperature sensors
that used thermalchromic liquid crystals. In such embodiments, the
temperature sensor is operatively connected to control circuitry
through a control wire that extends through the tubular body
1102.
[0049] In other embodiments, a vibrational element is embedded in
the wall of a CVC. In such embodiments, the vibrational element
comprises a metallic compound that can be vibrated by application
of an oscillating electromagnetic field from outside the body. For
example, an externally-applied electromagnetic field can be used to
vibrate a ferro-metallic ring or cylinder embedded in the wall of
the catheter 1100. In such embodiments, wires and electrodes used
to supply power to an ultrasound radiating member can be
eliminated. In certain embodiments, the vibrational element
embedded is configured to vibrate upon application of an
externally-applied oscillating electric field, or magnetic field,
or upon application of externally-applied ultrasonic energy.
Scope of the Invention
[0050] For purposes of describing the invention and the advantages
achieved over the prior art, certain features, objects and
advantages of the invention have been set forth herein. Not
necessarily all such features, objects or advantages may be used or
achieved in accordance with a particular embodiment of the
invention. Thus, for example, the invention may be embodied or
carried out in a manner that achieves or optimizes one advantage or
group of advantages as taught herein without necessarily achieving
other objects or advantages as may be taught or suggested herein.
In addition, various methods and procedures have been described
above. It should be understood that those methods and procedures
should not be limited to the sequence described but may be
performed in different orders and that not necessarily all of the
steps of a method or procedure needs to be performed. Furthermore,
the present invention is not limited to any particular disclosed
embodiment, but is limited only by the claims set forth below.
* * * * *