U.S. patent application number 10/383292 was filed with the patent office on 2003-09-04 for ultrasound catheter for providing a therapeutic effect to a vessel of a body.
Invention is credited to Bennett, Frederick J., Lichttenegger, Gary, Rodriguey, James E., Tachibana, Katsuro, Zhang, John.
Application Number | 20030167023 10/383292 |
Document ID | / |
Family ID | 27371853 |
Filed Date | 2003-09-04 |
United States Patent
Application |
20030167023 |
Kind Code |
A1 |
Bennett, Frederick J. ; et
al. |
September 4, 2003 |
Ultrasound catheter for providing a therapeutic effect to a vessel
of a body
Abstract
The invention relates to a catheter system. The system comprises
a catheter body having a chamber containing a low acoustic
impedance medium. The catheter body includes an elongated body with
an external surface and an ultrasound transducer having an external
side between a first end and a second end. The ultrasound
transducer is positioned over the external surface of the elongated
body such that the first end is adjacent to the chamber.
Inventors: |
Bennett, Frederick J.;
(Issaquah, WA) ; Zhang, John; (Bothell, WA)
; Lichttenegger, Gary; (Woodinville, WA) ;
Rodriguey, James E.; (Seattle, WA) ; Tachibana,
Katsuro; (Fukuoka, JP) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET
FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
27371853 |
Appl. No.: |
10/383292 |
Filed: |
March 6, 2003 |
Related U.S. Patent Documents
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Application
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Filing Date |
Patent Number |
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10383292 |
Mar 6, 2003 |
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09375162 |
Aug 16, 1999 |
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6582392 |
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09375162 |
Aug 16, 1999 |
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09129980 |
Aug 5, 1998 |
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6210356 |
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09375162 |
Aug 16, 1999 |
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09107078 |
Jun 29, 1998 |
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09375162 |
Aug 16, 1999 |
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09071285 |
May 1, 1998 |
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6001069 |
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60045268 |
May 1, 1997 |
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Current U.S.
Class: |
601/2 ; 600/439;
604/22 |
Current CPC
Class: |
A61M 2025/0057 20130101;
B06B 1/0674 20130101; B06B 1/0677 20130101; A61B 2017/22062
20130101; A61B 2017/22082 20130101; A61M 37/0092 20130101; A61B
2017/22084 20130101; G10K 11/02 20130101; B06B 2201/76 20130101;
G10K 11/004 20130101; A61B 2017/22021 20130101; A61B 2017/22042
20130101; A61B 17/22012 20130101; A61B 2017/22088 20130101; A61B
17/2202 20130101; A61M 2205/058 20130101; A61B 2018/00011 20130101;
A61M 25/007 20130101; A61M 25/0009 20130101; G10K 11/162 20130101;
A61B 2017/320084 20130101; A61K 41/0047 20130101; A61B 2017/00526
20130101; Y10T 156/10 20150115 |
Class at
Publication: |
601/2 ; 600/439;
604/22 |
International
Class: |
A61H 001/00 |
Claims
What is claimed is:
1. An catheter system, comprising: a catheter body having a chamber
containing a low acoustic impedance medium, the catheter body
including an elongated body with an external surface and an
ultrasound transducer having an external side between a first end
and a second end, the ultrasound transducer positioned over the
external surface of the elongated body such that the first end is
adjacent to the chamber.
2. The system of claim 1 wherein the ultrasound transducer
surrounds the elongated body.
3. The system of claim 1 wherein the chamber surrounds the
elongated body.
4. The system of claim 1 the catheter body includes a collar
positioned over the elongated body so as to at least partially
define the chamber.
5. The system of claim 4, wherein the catheter body includes a
transducer sheath positioned over the ultrasound transducer and the
collar so as to at least partially define the chamber.
6. The system of claim 4 wherein the catheter body at least
partially defines a second chamber adjacent to the second end of
the ultrasound transducer, the second chamber containing a low
acoustic impedance medium.
7. The system of claim 6, wherein the second chamber surrounds the
elongated body.
8. The system of claim 7, wherein the catheter body includes a
collar positioned over the elongated body so as to at least
partially define the second chamber.
9. The system of claim 8, wherein the catheter body includes a
transducer sheath positioned over the ultrasound transducer and the
collar so as to at least partially define the second chamber.
10. The system of claim 9, wherein the catheter body includes an
assembly sheath positioned over the transducer sheath.
11. The system of claim 10 wherein a binding medium occupies a
volume between the assembly sheath and the transducer sheath.
12. The system of claim 1 wherein the catheter body at least
partially defines a third chamber between the ultrasound transducer
and the external surface of the elongated body, the third chamber
containing a low acoustic impedance medium.
13. The system of claim 12, wherein the third chamber surrounds the
elongated body.
14. The catheter of claim 12, wherein the catheter body includes a
member positioned between the ultrasound transducer and the
external surface of the elongated body such that the third chamber
is positioned between the member and the external surface of the
elongated body.
15. The system of claim 13 wherein the catheter body includes
spacers positioned between the member and the external surface of
the elongated body.
16. The system of claim 12 wherein the catheter body includes an
extension body which gives the catheter length coupled with the
elongated body.
17. The system of claim 16 wherein the catheter body includes a
sheath over at least a portion of the extension body and over at
least a portion of the elongated body.
18. The system of claim 3, wherein the chamber and the third
chamber are open to one another.
19. The system of claim 1, further comprising: a sheath having a
utility lumen sized to receive the catheter body.
20. The system of claim 19, wherein the utility lumen is sized such
that the catheter body can slide within the utility lumen.
21. The system of claim 1 wherein the sheath includes a drug
delivery lumen.
22. The system of claim 21 wherein the drug delivery lumen spirals
around the utility lumen.
23. The system of claim 21 wherein the drug delivery lumen includes
a plurality of ports which permit a drug to flow through the ports
when a target pressure is achieved within the drug delivery
lumen.
24. The system of claim 21 wherein the drug delivery lumen includes
a plurality of ports which increase in size toward a distal end of
the sheath.
25. The system of claim 1, a lumen sized to receive a guidewire
extends longitudinally through the catheter body.
26. The system of claim 1, wherein the catheter body includes a
second ultrasound transducer having a side between a first end and
a second end.
27. The system of claim 26, wherein the catheter body includes a
second chamber adjacent an end of the second ultrasound
transducer.
28. The system of claim 26, wherein the catheter body includes a
third chamber between the ultrasound transducer and the external
surface of the elongated body and between the second ultrasound
transducer and the external surface of the elongated body.
29. The system of claim 1, wherein the low acoustic impedance
medium has an acoustic impedance of about 0-1.7 Megarayls.
30. The system of claim 1, wherein the low acoustic impedance
medium has an acoustic impedance of about 0-0.7 Megarayls.
31. The system of claim 1, wherein a binding medium having an
acoustic impedance of about 1.3-10 Megarayls is positioned adjacent
to the external surface of the ultrasound transducer.
32. The system of claim 1, wherein a binding medium having an
acoustic impedance of about 4-8 Megarayls is positioned adjacent to
the external surface of the ultrasound transducer.
33. The system of claim 1, wherein a binding medium is positioned
adjacent to the external surface of the ultrasound transducer and a
ratio of acoustic impedances for the binding medium adjacent to the
external side relative to the low acoustic impedance medium is
about 1.5 o 10,000:1.
34. The system of claim 1, wherein a binding medium is positioned
adjacent to the external surface of the ultrasound transducer and a
ratio of acoustic impedances for the binding medium adjacent to the
external side relative to the low acoustic impedance medium is
about 1.5 to 4:1.
35. A method for forming a catheter, comprising: positioning an
ultrasound transducer over an external surface of an elongated
body; positioning a collar over the exterior surface of the
elongated body such that at least a portion of the collar is spaced
apart from the ultrasound transducer; and positioning a transducer
sheath over at least a portion of the ultrasound transducer and
over at least a portion of the collar to form a chamber between the
ultrasound transducer and the collar.
36. The method of claim 35, further comprising: positioning a
spacer over the elongated body before positioning the ultrasound
transducer over the external surface of the elongated body.
37. The method of claim 36, further comprising: positioning a
member over at least a portion of the spacer before positioning the
ultrasound transducer over the external surface of the elongated
body.
38. The method of claim 37, wherein the ultrasound transducer is
positioned over the member.
39. The method of claim 35, further comprising: positioning spacers
over the external surface of the elongated body; positioning a
member over at least a portion of the spacers such that a chamber
is defined between the member and the external surface of the
elongated body; and positioning the ultrasound transducer over the
member.
40. The method of claim 35, wherein the collar is integral with a
spacer such that the collar has a spacer region and a collar
region.
41. The method of claim 40, further comprising: positioning a
member over the spacer region of the collar after positioning the
collar over the external surface of the elongated body; positioning
the ultrasound transducer over the member; and positioning the
transducer sheath over the collar region of the collar.
42. The method of claim 35, further comprising: positioning a
second collar over the external surface of the elongated body such
that a portion of the second collar is spaced apart from the
ultrasound transducer.
43. The method of claim 42, wherein positioning the transducer
sheath includes positioning the sheath over at least a portion of
the second collar to form a second chamber between the ultrasound
transducer and the second collar.
44. The method of claim 35, further comprising: positioning an
assembly sheath over the transducer sheath.
45. The method of claim 44, further comprising: delivering a
binding medium into a volume between the assembly sheath and the
transducer sheath.
46. The method of claim 35, further comprising: positioning a
catheter sheath over the elongated body and at least a portion of
an extension body.
47. The method of claim 46, further comprising: delivering a
binding medium into a volume between the ultrasound transducer and
the catheter sheath.
48. The method of claim 46, further comprising: delivering a
binding medium into a volume between the ultrasound transducer and
the extension body.
49. A method for forming a catheter, comprising: positioning a
first spacer over an external surface of an elongated body;
positioning a member over at least a portion of the first spacer;
and positioning an ultrasound transducer over the member.
50. The method of claim 49, further comprising: positioning a
second spacer over the external surface of the elongated body
before positioning the member over at least a portion of the first
spacer.
51. The method of claim 50, wherein positioning the member over at
least a portion of the first spacer includes positioning the member
over at least a portion of the second spacer to form a chamber
between the member and the external surface of the elongated
body.
52. The method of claim 49, further comprising: positioning a
second spacer such at least a portion of the second spacer is
between the member and the external surface of the elongated
body.
53. The method of claim 49, further comprising: positioning a
collar over the exterior surface of the elongated body such that at
least a portion of the collar is spaced apart from the ultrasound
transducer.
54. The method of claim 53, further comprising: positioning a
transducer sheath over at least a portion of the ultrasound
transducer and over at least a portion of the collar to form a
chamber between the ultrasound transducer and the collar.
55. The method of claim 49, wherein the first spacer is integral
with a collar such that the spacer has a spacer region and a collar
region.
56. The method of claim 55, wherein positioning the member over at
least a portion of the first spacer includes positioning the member
over at least a portion of the spacer region of the first
spacer.
57. The method of claim 56, further comprising positioning a
transducer sheath over at least a portion of the ultrasound
transducer and over at least a portion of the collar region of the
first spacer to form a chamber between the ultrasound transducer
and the collar.
58. The method of claim 57, further comprising: positioning a
second collar over the external surface of the elongated body such
that a portion of the second collar is spaced apart from the
ultrasound transducer.
59. The method of claim 57, wherein positioning the transducer
sheath includes positioning the sheath over at least a portion of
the second collar to form a second chamber between the ultrasound
transducer and the second collar.
60. The method of claim 59, further comprising: positioning an
assembly sheath over the transducer sheath.
61. The method of claim 60, further comprising: delivering a
binding medium into a volume between the assembly sheath and the
transducer sheath.
62. The method of claim 49, further comprising: positioning a
catheter sheath over the elongated body and at least a portion of
an extension body.
63. The method of claim 62, further comprising: delivering a
binding medium into a volume between the ultrasound transducer and
the catheter sheath.
Description
RELATIONSHIP TO CO-PENDING APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application No. 09/129,980, filed Aug. 5, 1998 and entitled
Ultrasound Assembly for Use With a Catheter which is incorporated
herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a catheter, and more
particularly, to a catheter having an ultrasound assembly.
[0004] 2. Description of Related Art
[0005] Many medical treatments can be performed using catheters
with an ultrasound transducer. These ultrasound transducers deliver
ultrasound energy to a target site within a patient. The ultrasound
energy can provide a therapeutic effect by itself or can enhance
the effects of other therapeutic media exposed to the ultrasound
energy. Inefficient ultrasound transducer arrangements can generate
excessive heat during a medical treatment.
SUMMARY OF THE INVENTION
[0006] The invention relates to a catheter system. The system
comprises a catheter body having a chamber containing a low
acoustic impedance medium. The catheter body includes an elongated
body with an external surface and an ultrasound transducer having
an external side between a first end and a second end. The
ultrasound transducer is positioned over the external surface of
the elongated body such that the first end of the ultrasound
transducer is adjacent to the chamber.
[0007] Another embodiment of the system comprises a catheter body
having an external surface. The catheter body includes an
ultrasound transducer having a side between a first end and a
second end. A first medium is positioned adjacent to the first end
of the ultrasound transducer and a second medium is positioned
adjacent to the external side of the ultrasound transducer. The
second medium is harder than the first medium to encourage
flexibility of the catheter body adjacent to the first end of the
ultrasound transducer and efficient transmission of ultrasound
energy from the external side of the ultrasound transducer.
[0008] The catheter system can also include a sheath for receiving
the catheter.
[0009] The invention also relates to a method for forming a
catheter. The method includes positioning an ultrasound transducer
over an external surface of an elongated body and positioning a
collar over the external surface of the elongated body such that at
least a portion of the collar is spaced apart from the ultrasound
transducer. The method also includes positioning a transducer
sheath over at least a portion of the ultrasound transducer and
over at least a portion of the collar to form a chamber between the
ultrasound transducer and the collar.
[0010] Another embodiment of the method includes positioning a
first spacer over an external surface of an elongated body and
positioning a member over at least a portion of the first spacer so
as to form a chamber between the member and the external surface of
the elongated body. The method also includes positioning an
ultrasound transducer over the member.
[0011] Yet another embodiment of the method includes providing an
ultrasound transducer having a side between a first end and a
second end. The ultrasound transducer is positioned over an
external surface of an elongated body. The method includes forming
a first medium adjacent to the first end of the ultrasound
transducer and forming a second medium adjacent to the side of the
ultrasound transducer. The second medium is harder than the first
medium to encourage flexibility of the catheter body adjacent to
the first end of the ultrasound transducer and efficient
transmission of ultrasound energy from the external side of the
ultrasound transducer.
BRIEF DESCRIPTION OF THE FIGURES
[0012] FIGS. 1A-1H illustrate a plurality of ultrasound assembles
for use with catheters according to the present invention.
[0013] FIG. 1A is a cross section of an ultrasound assembly having
a chamber between an ultrasound transducer and an external surface
of an elongated body.
[0014] FIG. 1B illustrates the relationship between spacers and the
elongated body for the embodiment of the ultrasound assembly
illustrated in FIG. 1A.
[0015] FIG. 1C illustrates the relationship between the ultrasound
transducer and the elongated body for the embodiment of the
ultrasound assembly illustrated in FIG. 1A.
[0016] FIG. 1D illustrates an ultrasound assembly having a chamber
adjacent to an end of the ultrasound transducer and a chamber
between the ultrasound transducer and the external surface of the
elongated body.
[0017] FIG. 1E illustrates an ultrasound assembly having chambers
adjacent to both ends of the ultrasound transducer and a chamber
between the ultrasound transducer and the external surface of the
elongated body
[0018] FIG. 1F illustrates an ultrasound assembly having a chamber
adjacent to an end of the ultrasound transducer.
[0019] FIG. 1G illustrates an ultrasound assembly having chambers
adjacent to both ends of the ultrasound transducer.
[0020] FIG. 1H illustrates an ultrasound assembly without
chambers.
[0021] FIGS. 2A-2D illustrate embodiments of ultrasound assemblies
for use with a catheter according to the present invention. The
ultrasound assemblies include a transducer sheath defining a
reservoir at the end of the ultrasound assembly. The reservoir
contains a binding medium.
[0022] FIGS. 3A-3D illustrate embodiments of ultrasound assemblies
for use with a catheter according to the present invention. The
ultrasound assemblies include an assembly sheath positioned over an
ultrasound transducer. A volume between the ultrasound transducer
and the assembly sheath contains a binding medium.
[0023] FIGS. 4A-4F illustrate ultrasound assemblies having a spacer
for creating a chamber between a side of an ultrasound transducer
and an external surface of an elongated body. The ultrasound
assemblies also include a collar for creating a chamber adjacent to
the ends of the ultrasound transducer.
[0024] FIG. 4A illustrates the collar abutting the spacer.
[0025] FIG. 4B illustrates the collar in a spaced apart
relationship to the spacer.
[0026] FIGS. 4C and 4D illustrate the collar positioned over the
spacer.
[0027] FIGS. 4E and 4F illustrate the collar integral with the
spacer.
[0028] FIG. 5A illustrates a catheter incorporating an ultrasound
assembly.
[0029] FIG. 5B illustrates catheter having a binding medium
adjacent to the ends of the ultrasound transducer.
[0030] FIG. 5C illustrates a catheter having a binding medium
adjacent to the external side of the ultrasound transducer.
[0031] FIG. 5D illustrates a catheter having a binding medium
adjacent to the ends of the ultrasound transducer and another
binding medium adjacent to the external side of the ultrasound
transducer.
[0032] FIG. 5E illustrates a catheter having a binding medium
adjacent to the ends of the ultrasound transducer and a second
binding medium adjacent to the external surface of the catheter
ultrasound transducer and a third binding medium adjacent to the
ultrasound transducer.
[0033] FIG. 5F illustrates a catheter having a binding medium
adjacent to the ends of the ultrasound transducer, a second binding
medium adjacent to the external side of the ultrasound transducer
and a third binding medium positioned in reservoirs at the ends of
the ultrasound assembly.
[0034] FIGS. 6A-6C illustrate embodiments of a catheter having a
plurality of ultrasound assemblies according to the present
invention.
[0035] FIG. 6A illustrates a catheter having ultrasound assemblies
spaced apart from a catheter sheath.
[0036] FIG. 6B illustrates a catheter having ultrasound assemblies
in contact with a catheter sheath.
[0037] FIG. 6C illustrates a catheter having ultrasound assemblies
which share a member.
[0038] FIGS. 7A-7E illustrate a method for forming ultrasound
assemblies according to the present invention.
[0039] FIGS. 8A-8D illustrate a method for forming an ultrasound
assembly when a collar for forming a chamber adjacent to the
ultrasound transducer is integral with a spacer for forming a
chamber between the ultrasound transducer and an external surface
of an elongated body.
[0040] FIG. 9A illustrates a method for forming an ultrasound
assembly having a transducer sheath extending beyond the ultrasound
transducer and beyond a collar so as to form reservoirs adjacent to
the ends of the ultrasound transducer.
[0041] FIG. 9B illustrates delivery of a binding medium into a
reservoir at an end of the ultrasound assembly.
[0042] FIGS. 10A-10D illustrate a method for forming a catheter
according to the present invention.
[0043] FIG. 10A illustrates a catheter sheath positioned over an
extension region, an assembly region and a terminal region of a
catheter body.
[0044] FIG. 10B illustrates a binding medium delivered adjacent to
an end of the ultrasound transducer.
[0045] FIG. 10C illustrates a binding medium delivered adjacent to
an external side of the ultrasound transducer.
[0046] FIG. 10D illustrates a first binding medium delivered
adjacent to an external side of the ultrasound transducer and a
second binding medium delivered adjacent to an end of the
ultrasound transducer.
[0047] FIG. 11 illustrates the proximal portion of a catheter
according to the present invention.
[0048] FIGS. 12A-12D illustrate a sheath for use with a catheter
according to the present invention.
[0049] FIG. 12A is a sideview of the sheath.
[0050] FIG. 12B illustrates a catheter according to the present
invention positioned within the sheath.
[0051] FIG. 12C is a sideview of a sheath having a drug delivery
lumen which spirals around a sheath distal end.
[0052] FIG. 12D is a cross section of a sheath having a drug
delivery lumen which spirals around a sheath distal end.
[0053] FIGS. 13A-13G illustrate a method for using a catheter
according to the present invention in conjunction with a
sheath.
DETAILED DESCRIPTION
[0054] The invention relates to a catheter having a chamber
containing a low acoustic impedance medium. The catheter can also
include an elongated body with an external surface. An ultrasound
transducer having an external side between a first end and a second
end can be positioned over the external surface of the elongated
body such that the first side of the ultrasound transducer is
adjacent to the chamber.
[0055] The low acoustic impedance material within the chamber
reduces the portion of ultrasound energy which is transmitted
through the chamber. This reduction causes an increased portion of
ultrasound energy to be delivered from the second end of the
ultrasound transducer and/or from the external side of the
ultrasound transducer. As a result, the ultrasound energy produced
from these sections of the ultrasound transducer is delivered with
a greater efficiency.
[0056] The ultrasound transducer can be positioned distally
relative to the chamber in order to increase the efficiency of the
ultrasound energy transmitted in the distal direction.
Alternatively, the ultrasound transducer can be positioned
proximally relative to the chamber in order to increase the
efficiency of the ultrasound energy transmitted in the proximal
direction.
[0057] Another embodiment of the catheter includes a chamber
between the elongated body and an internal side of the ultrasound
transducer. The chamber can include a low acoustic impedance medium
to reduce the portion of ultrasound energy transmitted into the
elongated body. As a result, the ultrasound energy produced from
the ends and the external side of the ultrasound transducer is
delivered with a greater efficiency than could be achieved without
the chamber.
[0058] A catheter according to the present invention can include
various combinations of the above chambers. Each of the chambers
can be independent of one another or they can be in communication
with one another. The chambers can contain a low acoustic impedance
medium. For instance, a catheter can include a first chamber
adjacent to the first end of the ultrasound transducer, a second
chamber adjacent to the second end of the ultrasound transducer and
a third chamber between the internal side of the ultrasound
transducer and the elongated body. As a result, the ultrasound
energy produced from the external surface of the catheter is
delivered at an increased efficiency. Such a catheter efficiently
delivers ultrasound energy from the side of the catheter.
[0059] As another example, a catheter can include the first chamber
adjacent to the first end of the ultrasound transducer and the
third chamber between the internal side of the ultrasound
transducer and the elongated body. Further, the ultrasound
transducer can be positioned distally relative to the first
chamber. The chambers can contain a low acoustic impedance medium.
As a result, the ultrasound energy produced from the second end and
the external surface of the catheter is delivered at an increased
efficiency. Such a catheter efficiently delivers ultrasound energy
both distally and from the side of the catheter.
[0060] A catheter according to the present invention can also
include a plurality of ultrasound transducers. Each ultrasound
transducer can be associated with one or more chambers. As a
result, each ultrasound transducer can have an increased
efficiency.
[0061] An embodiment of a catheter having a plurality of ultrasound
transducers includes ultrasound transducers with matched resonant
frequencies. For instance, the catheter can include ultrasound
transducers selected such that any one has a resonant frequency
within about 1% of the resonant frequency of any other ultrasound
transducer in the plurality of ultrasound transducers. The matching
of the ultrasound transducers allows the ultrasound transducers to
be concurrently driven at a single frequency while reducing the
inefficiencies associated with driving ultrasound transducers at a
frequency which is significantly different than their resonant
frequency.
[0062] Another embodiment of the catheter includes a first binding
medium adjacent to the first end of the ultrasound transducer and a
second binding medium adjacent to the external side of the
ultrasound transducer. The first and second media are selected to
provide the catheter with flexibility and a high level of
ultrasound transmission efficiency. Since a softer media is
typically more flexible and harder media typically transit
ultrasound energy more efficiently, the second medium is preferably
harder than the first medium. The advantages of the first and
second media are emphasized in multiple ultrasound transducer
catheters which tend to lose flexibility with the increased number
of ultrasound transducers.
[0063] Catheters according to the present invention can also
include an autotransformer in the proximal portion of the catheter.
The autotransformer can serve to adjust the characteristic
impedance of the catheter to match the impedance of components used
to drive the one or more ultrasound transducers included on the
catheter. The matched impedance serves to increase the efficiency
of the catheter system.
[0064] Catheters according to the present invention can also
include a catheter identification electronics. The catheter
identification electronics indicate to a catheter control system
the frequency that ultrasound transducers should be driven.
[0065] FIGS. 1A-1C illustrate an embodiment of an ultrasound
assembly 10 according to the present invention for use with a
catheter according to the present invention. FIG. 1A is a
longitudinal cross sectional view of the ultrasound assembly 10.
FIG. 1B is a lateral cross section of the ultrasound assembly 10
taken at the point labeled A in FIG. 1A. FIG. 1C is a lateral cross
section of the ultrasound assembly 10 taken at the point labeled B
in FIG. 1A.
[0066] The ultrasound assembly 10 includes an elongated body 12
with an external surface 14. A plurality of spacers 16 are
positioned over the external surface 14 of an elongated body 12 and
a member 18 is positioned over at least a portion of the spacers
16. The ultrasound assembly 10 also includes an ultrasound
transducer 20 with an external side 22 and an internal side 24
between a first end 26 and a second end 28. The ultrasound
transducer 20 is positioned over the member 18 and can surround the
member 18. Suitable materials for the member 18 include, but are
not limited to, polyimide, polyester and nylon. A suitable
ultrasound transducer 20 includes, but is not limited to, PZT-4D,
PZT-4, PZT-8 and various piezoceramics.
[0067] The internal side 24 of the ultrasound transducer 20, the
spacers 16 and the member 18 each define a portion of a chamber 30
between the internal side 24 of the ultrasound transducer 20 and
the external surface 14 of the elongated body 12. The chamber 30
preferably has a height from 0.25-10 .mu.m, more preferably from
0.50-5 .mu.m and most preferably from 0.0-1.5 .mu.m.
[0068] The member 18 can extend beyond the first end 26 and/or the
second end 28 of the ultrasound transducer 20. Additionally, the
spacers 16 can be positioned beyond the ends of the ultrasound
transducer 20. As a result, the chamber 30 can extend along the
longitudinal length of the ultrasound transducer 20 to increase the
portion of the ultrasound transducer 20 which is adjacent to the
chamber 30.
[0069] The chamber 30 can contain a low acoustic impedance medium.
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 30 can also be evacuated.
Suitable pressures for an evacuated chamber 30 include, but are not
limited to, negative pressures to -760 mm Hg.
[0070] As illustrated in FIG. 1D, the internal side 24 of the
ultrasound transducer 20 can also be positioned adjacent to a
chamber 30. The ultrasound assembly 10 includes a collar 32 over
external surface 14 of the elongated body 12. The collar 32 can
surround the elongated body 12. The collar 32 has a spaced apart
relationship to the ultrasound transducer 20.
[0071] A transducer sheath 34 is positioned over at least a portion
of the ultrasound transducer 20 and the collar 32 to form a chamber
30 adjacent to a side of the ultrasound transducer 20. An inner
side of the collar 32, the ultrasound transducer 20 and the
transducer sheath 34 each partially define the chamber 30. The
chamber 30 preferably has a width, W, from 12-2500 .mu.m, more
preferably from 25-250 .mu.m and most preferably from 25-125 .mu.m.
The chamber 30 can contain a low acoustic impedance medium.
Suitable materials for the transducer sheath 34 include, but are
not limited to air, N.sup.2, O.sup.2, and vacuum. The transducer
sheath 34 preferably has a thickness from 10-100 .mu.m and more
preferably from 25-50 .mu.m.
[0072] The ultrasound assembly 10 can also include a chamber 30
adjacent to the second end 28 of the ultrasound transducer 20 as
illustrated in FIG. 1E. A second collar 36 is positioned over the
elongated body 12 and can surround the external surface 14 of the
elongated body 12. The second collar 36 has a spaced apart
relationship from the ultrasound transducer 20 so as to provide a
second chamber 30 adjacent to the ultrasound transducer 20. An
inner side of the second collar 36, the ultrasound transducer 20
and the transducer sheath 34 each partially define the chamber 30.
The chamber 30 preferably has a width, W, from 12-2500 .mu.m, more
preferably from 25-250 .mu.m and most preferably from 25-125 .mu.m.
The chamber 30 adjacent to the second end 28 of the ultrasound
transducer 20 can also contain a low acoustic impedance medium.
[0073] Each of the chambers can be isolated from one another.
However, when the ultrasound assembly 10 includes a chamber 30
between the ultrasound transducer 20 and the elongated body 12, one
or more of the spacers 16 can be formed of a porous material to
provide communication between the chambers 30. This communication
can permit the pressures in each of the chambers 30 to reach an
equilibrium. Alternatively, one or more of the spacers 16 can
include channels, lumens 38 and/or a ridged external surface to
permit the communication between chambers 30.
[0074] An embodiment of the ultrasound assembly 10 does not include
a chamber 30 between the elongated body 12 and the internal side 24
of the ultrasound transducer 20 as illustrated in FIG. 1F. The
ultrasound transducer 20 is positioned adjacent to the external
surface 14 of the elongated body 12 such that a chamber 30 is not
formed between the elongated body 12 and the ultrasound transducer
20. The ultrasound assembly 10 includes a collar 32 around the
elongated body 12 in a spaced apart relationship from the
ultrasound transducer 20 so as to form a chamber 30 adjacent to the
first side of the ultrasound transducer 20.
[0075] The ultrasound assembly 10 of FIG. 1F can also include a
second chamber 30 adjacent to the second end 28 of the ultrasound
transducer 20 as illustrated in FIG. 1G. The ultrasound assembly 10
includes a second collar 36 over the elongated body 12 in a spaced
apart relationship from the ultrasound transducer 20. Accordingly a
second chamber 30 is formed adjacent to the second side of the
ultrasound transducer 20. As illustrated in FIG. 1H, an embodiment
of the ultrasound assembly 10 does not include any chambers 30.
[0076] A utility lumen 38 extends through the elongated body 12.
The utility lumen 38 can be sized to receive a guidewire, to
deliver therapeutic media including drugs, medication, microbubbles
and other compounds which provide a therapeutic effect. Although,
the elongated body 12 is illustrated as having a single utility
lumen 38, the elongated body 12 can include a plurality of lumens
38 or can be solid.
[0077] Each of the ultrasound assemblies 10 illustrated in FIGS.
1A-1H can have a transducer sheath 34 which extends past the first
collar 32, the second collar 36 and/or past the ultrasound
transducer 20. FIGS. 2A-2D illustrate such a transducer sheath 34
with a selection of the ultrasound assemblies 10 illustrated in
FIGS. 1A-1H. The extension of the transducer sheath 34 past the
collar 32 and/or past the ultrasound transducer 20 provides a
reservoir 40 at the ends of the ultrasound assembly 10. The
reservoir 40 can optionally contain a binding medium 42 such as an
epoxy or adhesive. The binding medium 42 can serve to keep the
ultrasound transducer 20 intact during the handling of the
ultrasound assembly 10. Although FIGS. 2A-2D illustrate the
transducer sheath 34 extending past the first collar 32, the second
collar 36 and/or the ultrasound transducer 20 at both ends of the
ultrasound assembly 10, the transducer sheath 34 can extending past
a collar 32 and/or ultrasound transducer 20 at only one end of the
ultrasound assembly 10.
[0078] Each ultrasound assembly 10 discussed and/or suggested above
can include an assembly 10 sheath. FIGS. 3A-3D illustrate a
selection of the above ultrasound assemblies 10 including an
assembly sheath 44 positioned over the ultrasound transducer 20.
Suitable materials for the assembly sheath 44 include, but are not
limited to polyimide, PTFE, and polyurethane. The assembly sheath
44 preferably has a thickness from 12-75 .mu.m and more preferably
from 25-50 .mu.m.
[0079] A volume between the assembly sheath 44 and the ultrasound
transducer 20 can contain a binding medium 42 as illustrated in
FIG. 3A. Further, when the ultrasound assembly 10 includes a
transducer sheath 34, the volume between the ultrasound assembly 10
sheath and the transducer sheath 34 can contain the binding medium
42 as illustrated in FIGS. 3B-3D. The binding medium 42 can be a
binding medium 42 which serves to keep the ultrasound transducer 20
intact during the handling of the ultrasound assembly 10.
[0080] Each of the ultrasound assemblies 10 illustrated above show
the elongated body 12 extending outward from the ultrasound
assembly 10. However, the elongated body 12 can be trimmed to
provide an elongated body 12 which is flush with one or more sides
of the elongated body 12. Additionally, a sensor such as a
temperature sensor can be positioned in the binding medium 42
associated with any of the above ultrasound assemblies 10.
[0081] FIGS. 4A-4F illustrate various arrangements between the
collars 32 and spacers 16 for use with the ultrasound assemblies 10
discussed above. FIG. 4A illustrates the collar 32 abutting the
spacers 16. The collar 32 can be spaced apart from the spacers 16
as illustrated in FIG. 4B. In another embodiment, the collar 32 is
sized to be positioned around the spacer 16 as illustrated in FIG.
4C. In yet another embodiment, the collar 32 is sized to be
positioned around the member 18 as illustrated in FIG. 4D.
[0082] The collar 32 can be integral with the spacers 16 as
illustrated in FIG. 4E. The spacer 16 has an L-shaped profile with
a spacer region 46 positioned adjacent to the member 18 and a
collar region 48 positioned adjacent to the transducer sheath 34.
Accordingly, the raised edge serves to define a side of the chamber
30. When the collar 32 is integral with the spacer, the spacer 16
can include a seat 50 sized to receive an edge of the member 18 as
illustrated in FIG. 4F.
[0083] FIGS. 5A and 5B illustrate a catheter according to the
present invention. The catheter can include any of the ultrasound
assemblies 10 discussed or suggested above. As a result, the
catheter is illustrated with a generalized representation of an
ultrasound assembly 10. Specifically, an ultrasound assembly 10 is
illustrated as an ultrasound transducer 20 over an elongated body
12. A box 51 over the ultrasound transducer 20 represents the
remaining portions of each ultrasound assembly 10. For instance,
the box 51 can represent the collars 32, spacers, members,
chambers, binding media, etc. associated with an ultrasound
assembly 10.
[0084] The catheter includes a catheter body 52 having an external
surface 53, a distal portion 54 and a proximal portion 56. The
catheter body 52 can include an extension region 58, an assembly
region 60 and a terminal region 62. Lumens 38 within the extension
region 58, assembly region 60 and terminal region 62 are aligned
with one another to provide one or more lumens 38 extending through
the entire catheter. These lumens 38 can be sized to receive a
guidewire or for the delivery of a therapeutic agent such as a
drug.
[0085] The extension region 58 includes an extension body 64 having
one or more lumens 38. The one or more lumens 38 included in the
extension body 64 have cross sectional dimensions approximating the
cross section dimensions of the one or more utility lumens 38 of
the elongated body 12. The extension body 64 can be used to add
length to the catheter. Specifically, the extension body 64 can
provide additional length beyond the length provided by the
assembly region 60. Accordingly, the extension body 64 can be short
or can be eliminated from the catheter body 52. Suitable materials
for the extension body 64 include, but are not limited to,
polyimide, silicone, and polyurethane.
[0086] The terminal region 62 is positioned at the distal tip of
the catheter. The terminal region 62 includes a terminal body 66.
The terminal body 66 can be solid or include one or more lumens 38
with cross sectional dimensions approximating the cross section
dimensions of the one or more utility lumens 38 of the elongated
body 12. Suitable materials for the terminal region 62 include, but
are not limited to, polyimide, silicone, and polyurethane. The
assembly region 60 is the region of the catheter body 52 including
any of the ultrasound assemblies 10 discussed and/or suggested
above.
[0087] A catheter sheath 68 is positioned over the extension region
58, the assembly region 60 and the terminal region 62 so as to
define a portion of the external surface 53 of the catheter body
52. The catheter sheath 68 can serve to immobilize the extension
region 58, the assembly region 60 and the terminal region 62
relative to one another. The catheter sheath 68 is optional and can
be removed from the catheter body 52.
[0088] The volume between the ultrasound assembly 10 and the
extension body 64 can contain a binding medium 42. Such binding
media can serve to couple the extension region 58, the assembly
region 60 and the terminal region 62 together. Suitable materials
for the catheter sheath 68 include, but are not limited to
polyethelyne, polyurethane, and polyimide. The thickness of the
catheter sheath 68 material is preferably 0.001" to 0.020", more
preferably 0.004" to 0.010" and most preferably 0.006" to
0.008".
[0089] As illustrated in FIG. 5B, a first binding medium 42A can be
positioned adjacent to the ends of the ultrasound transducer 20.
Specifically, a volume between the extension body 64 and the
ultrasound transducer 20 can contain the first binding medium 42A.
Further, the volume between the terminal body 66 and the ultrasound
transducer 20 can contain the first binding medium 42A.
[0090] The first binding medium 42A can also be positioned adjacent
to the external side 22 of the ultrasound transducer 20 as
illustrated in FIG. 5C. Specifically, the first binding medium 42A
can be contained in a volume between the external side 22 of the
ultrasound transducer 20 and the externals surface of the catheter
body 52.
[0091] As illustrated in FIG. 5D, a catheter can include a first
binding medium 42A and a second binding medium 42B. The first
binding medium 42A is adjacent to the ends of the ultrasound
transducer 20 and the second binding medium 42B is adjacent to the
external side 22 of the ultrasound transducer 20. Specifically, the
second binding medium 42B can be contained in a volume between the
external side 22 of the ultrasound transducer 20 and the external
surface 53 of the catheter body 52. A portion of the second binding
medium 42B is also illustrated as being adjacent to the ends of the
ultrasound assembly 10 although the second binding medium 42B can
be restricted to the volume adjacent to the external side 22 of the
ultrasound transducer 20.
[0092] The first binding medium 42A and the second binding medium
42B can be the same or different. When the second binding medium
42B is different than the first binding medium 42A, the second
binding medium 42B is preferably harder than the first binding
medium 42A. A harder binding medium 42 typically transmits
ultrasound energy more efficiently than a softer binding medium 42.
As a result, the hardness of the second binding medium 42B can
preserve the ultrasound transmitting efficiency of the catheter.
Additionally, the softness of the first binding medium 42A provides
the catheter with additional flexibility. As a result, the choices
of the first and second binding media effect both the flexibility
and the ultrasound transmission efficiency of the catheter.
[0093] The second binding medium 42B is preferably at least 2 times
harder than the first binding medium 42A and more preferably from
about 3 to about 5 times harder than the first binding medium 42A.
The first binding medium 42A preferably has a hardness of at least
about 10 Shore D, more preferably from about 15 to about 80 Shore D
and most preferably from about 20 to about 40 Shore D. The second
binding medium 42B preferably has a hardness of at least about 60
Shore D, more preferably from about 65 to about 120 Shore D and
most preferably from about 80 to about 100 Shore D.
[0094] As described above, any of the ultrasound assemblies 10
described and/or suggested above can be included in a catheter
according to the present invention. FIG. 5E illustrates a
particular example of a catheter including an assembly sheath 44
over the ultrasound transducer 20. Specifically, FIG. 5B
illustrates the catheter including the ultrasound assembly 10 of
FIG. 2B. The ultrasound assembly 10 includes a chamber 30 adjacent
to a first end 26 of the ultrasound transducer 20. The chamber 30
is positioned proximally relative to the ultrasound transducer 20.
The ultrasound assembly 10 includes another chamber 30 between the
ultrasound transducer 20 and the external surface 14 of the
elongated body 12. Each chamber 30 contains a low acoustic
impedance medium. As a result, this embodiment of the catheter
efficiently transmits ultrasound energy in the distal
direction.
[0095] The catheter of FIG. 5E includes a first binding medium 42A,
a second binding medium 42B and a third binding medium 42C. The
first binding medium 42A is adjacent to the ends of the ultrasound
transducer 20 and the second binding medium 42B is contained in a
volume between the assembly sheath 44 and the external surface 53
of the catheter body 52. The third binding medium 42C is adjacent
to the external side 22 of the ultrasound transducer 20.
Specifically, a volume between the ultrasound transducer 20 and the
assembly sheath 44 includes the third binding medium 42C.
[0096] Two or more of the first, second and third binding media can
be the same or they can all be different. In a preferred
embodiment, the first and second binding media are the same while
the third binding medium 42C transmits is harder than the first and
second binding media. Accordingly, when the first and second
binding media are the same, the third binding media is preferably
harder than the first binding medium 42A. Preferably, the first
binding medium 42A is also more flexible than the third binding
medium 42C. Further, the third binding medium 42C is preferably at
least 2 times harder than the first binding medium 42A and more
preferably from about 3 to about 5 times harder than the first
binding medium 42A. Additionally, the first binding medium 42C
preferably has a hardness of at least about 10 Shore D, more
preferably from about 15 to about 80 Shore D and most preferably
from about 20 to about 40 Shore D. The third binding medium 42B
preferably has a hardness of at least about 60 Shore D, more
preferably from about 65 to about 120 Shore D and most preferably
from about 80 to about 100 Shore D. In another preferred
embodiment, the second and third binding media are each harder than
the first binding medium 42A. In another preferred embodiment, the
second and third binding media are the same and are harder than the
first binding medium 42A.
[0097] FIG. 5F illustrates a particular example of a catheter
having a transducer sheath 34 extending beyond the collar 32 and
the ultrasound transducer 20 to form reservoirs 40 at the end of
the ultrasound assembly 10. The catheter includes a first binding
medium 42A, a second binding medium 42B and a third binding medium
42C. The first binding medium 42A is adjacent to the ends of the
ultrasound transducer 20 and the second binding medium 42B is
adjacent to the external side 22 of the ultrasound transducer 20.
Reservoirs 40 formed adjacent to the ends of the ultrasound
transducer 20 contain the third binding medium 42C.
[0098] Two or more of the first, second and third binding media can
be the same or they can all be different. The second binding medium
42B preferably transmits ultrasound energy more efficiently than
the first binding medium 42A. Further, the first binding medium 42A
is preferably more flexible than the second binding medium 42B. The
first and second binding media preferably have the hardness
relationships and levels described with respect to the first and
second binding media of FIG. 5D. In a preferred embodiment, the
first and third binding media are the same.
[0099] The catheter can include two or more ultrasound assemblies
10 as illustrated in FIGS. 6A and 6B. FIG. 6A illustrates the
ultrasound assembly 10 in contact with the catheter sheath 68 while
FIG. 6B illustrates the ultrasound assemblies 10 spaced apart from
the catheter sheath 68. The ultrasound assemblies 10 can share the
same elongated body 12 and/or different ultrasound assemblies 10
can include different elongated bodies 12. When the ultrasound
assemblies 10 are formed with different elongated bodies 12, the
different elongated bodies 12 can be aligned with one another
during assembly of the catheter.
[0100] Two or more ultrasound assemblies 10 can share a member 18
as illustrated in FIG. 6C. Each of the ultrasound assemblies 10 is
positioned over the same member 18. As a result, the member 18
partially defines a chamber 30 between each of the ultrasound
transducers 20 and the elongated body 12. When different ultrasound
transducers 20 share a member 18, spacers 16 can be optionally
positioned between the ultrasound assemblies 10. As a result, a
single member 18 can be positioned over at least a portion of three
or more spacers 16.
[0101] As illustrated in FIGS. 6A and 6B, when the catheter
includes a plurality of ultrasound transducers 20, a first binding
medium 42A can be positioned adjacent to the ends of the ultrasound
transducers 20. Specifically, the first binding medium 42A can be
contained in a volume between an ultrasound transducer 20 and an
extension body 64, a volume between adjacent ultrasound transducer
20, and/or a volume between an ultrasound transducer 20 and a
terminal body 66.
[0102] As illustrated in FIG. 6C, a catheter including a plurality
of ultrasound assemblies 10 can also include a second binding
medium 42B adjacent to the external side 22 of the ultrasound
transducers 20. Specifically, the second binding medium 42B can be
contained in a volume between the external side 22 of the
ultrasound transducer 20 and the external surface 53 of the
catheter body 52. As described with respect to FIG. 5D, the first
and second binding media can be the same or different and the
second binding medium 42B is preferably harder than the first
binding medium 42A. As described with respect to FIGS. 5E-5F, the
inclusion of specific ultrasound assembly 10 embodiments can result
in the catheter including additional binding media. When the
catheter includes an additional binding media adjacent to the
external side 22 of the ultrasound transducers 20 (i.e. FIG. 5E),
that binding media is preferably at least as hard as the first and
second binding media.
[0103] FIGS. 7A-7E illustrate a method for fabricating ultrasound
assemblies 10 according to the present invention. In FIG. 7A,
spacers 16 are positioned over an elongated body 12. The spacers 16
can optionally be adhesively attached to the elongated body 12 with
compounds such as epoxy. FIG. 7B illustrates a member 18 positioned
over the spacers 16. The positioning of the member 18 forms a
chamber 30 between the member 18 and the elongated body 12. The
member 18 can optionally be adhesively attached to the spacers 16
with compounds such as epoxy.
[0104] In FIG. 7C an ultrasound transducer 20 is positioned over
the member 18 to form the ultrasound assembly 10 of FIG. 1A. The
ultrasound transducer 20 can optionally be adhesively attached to
the member 18 with compounds such as epoxy. A collar 32 is also
positioned over the elongated body 12 and can be attached to the
elongated body 12 with compounds such as epoxy. FIG. 7D illustrates
a transducer sheath 34 positioned over the collar 32 to form the
ultrasound assembly 10 of FIG. 2B. The transducer sheath 34 forms a
chamber 30 adjacent to the ultrasound transducer 20.
[0105] In FIG. 7E an assembly sheath 44 is positioned over the
transducer sheath 34 of the ultrasound assembly 10 illustrated in
FIG. 7D. A binding medium 42 precursor is delivered adjacent to the
external side 22 of the ultrasound transducer 20. Specifically, the
binding medium 42 precursor is delivered into a volume between the
transducer sheath 34 and the assembly sheath 44. The binding medium
42 can be delivered into the volume using an injection device such
as a hypodermic needle 70. The binding medium 42 can solidify to
provide the ultrasound assembly 10 of FIG. 3B. Suitable mechanisms
for solidification include, but are not limited to, setting,
cooling and curing.
[0106] FIGS. 8A-8D illustrate method for forming ultrasound
assemblies 10 when the collar 32 is integral with the spacers 16.
FIG. 8A illustrates a spacer 16 positioned over an elongated body
12. In FIG. 8B a member 18 is positioned over the spacer 16 and an
ultrasound transducer 20 is positioned over the member 18. In FIG.
8C a second spacer 16 is positioned over the elongated body 12 and
moved toward the original spacer 16 until a portion of the spacer
16 is positioned between the member 18 and the elongated body 12.
As a result, a chamber 30 is formed between the member 18 and the
elongated body 12. In FIG. 8D a transducer sheath 34 is positioned
over the spacers 16 and the ultrasound transducer 20 to form the
ultrasound assembly 10 of FIG. 3C having collars 32 which are
integral with the spacers 16.
[0107] FIGS. 9A-9B illustrate an adaptation of the method
illustrated in FIGS. 7A-7E to form an ultrasound assembly 10 having
a transducer sheath 34 which extends past a first collar 32, a
second collar 36 and/or past the ultrasound transducer 20 as
discussed with respect to FIGS. 2A-2D. FIG. 9A illustrates a
transducer sheath 34 positioned over the collar 32 and ultrasound
transducer 20 of FIG. 7C. The ultrasound transducer 20 extends past
the collar 32 and the ultrasound transducer 20 to form reservoirs
40 adjacent to the ends of the ultrasound transducer 20. FIG. 9B
illustrates a binding medium 42 precursor being delivered into the
reservoirs 40 to provide the ultrasound assembly 10 illustrated in
FIG. 2B.
[0108] The methods described in FIGS. 7A-9B can be used to provide
an elongated body 12 having a plurality of ultrasound assemblies
10. Each ultrasound assembly 10 can be concurrently formed on the
elongated body 12 or they can be sequentially formed on the
elongated body 12. Alternatively, a portion of each ultrasound
assembly 10 can be formed concurrently while the remaining portions
of the ultrasound assemblies 10 are formed sequentially. For
instance, in FIG. 6C, the chamber 30 between each ultrasound
transducer 20 and the external surface 14 of the elongated body 12
can be formed concurrently while the remaining portions of the
ultrasound assemblies 10 are formed sequentially.
[0109] FIGS. 10A-10D illustrate methods for forming a catheter
according to the present invention. FIG. 10A illustrates a catheter
sheath 68 positioned over an extension body 64 as illustrated by
the arrow labeled A. The ultrasound assembly 10 is then positioned
within the catheter sheath 68 as illustrated by the arrow labeled
B. A terminal body 66 is then positioned within the catheter sheath
68 as indicated by the arrow labeled C.
[0110] As illustrated in FIG. 10B, a binding medium 42 precursor is
delivered adjacent to an end of the ultrasound transducer 20.
Specifically, the binding medium 42 precursor is delivered into a
volume between the ultrasound assembly 10 and the terminal body 66.
FIG. 10B illustrates the binding medium 42 precursor delivered
adjacent to an end of the ultrasound assembly 10 using an injection
instrument such as a hypodermic needle 70. The binding medium 42
precursor can be sequentially delivered adjacent to one end of the
ultrasound transducer 20 and then adjacent to the opposing end of
the ultrasound transducer 20. The binding medium 42 precursor
preferably solidifies to form a binding media adjacent to the ends
of the ultrasound transducer 20.
[0111] As illustrated in FIG. 10C, a binding medium 42 precursor
can also be delivered into a volume between the external side 22 of
the ultrasound transducer 20 and the external surface 53 of the
catheter body 52. As illustrated, the quantity of binding medium 42
precursor delivered can be enough to fill the volume adjacent to
the external side 22 of the ultrasound transducer 20. The binding
medium 42 precursor preferably solidifies to form a binding medium
42 adjacent to the external side 22 of the ultrasound transducer
20. Alternatively, sufficient binding medium 42 precursor can be
delivered to fill the volume adjacent to the ends of the ultrasound
transducer 20.
[0112] When the quantity of binding medium 42 precursor delivered
fills the volume adjacent to the external side 22 of the ultrasound
transducer 20, a second binding medium 42B precursor can be
delivered into the volumes adjacent to the ends of the ultrasound
transducer 20 as illustrated in FIG. 10D. The second binding medium
42B precursor preferably solidifies to form a second binding medium
42B adjacent to the ends of the ultrasound transducer 20.
[0113] Once the binding media delivered above have solidified, the
catheter sheath 68 can be removed from the catheter body 52.
Additionally, once a chamber 30 is formed, a fluid low acoustic
impedance medium can be delivered into the chamber 30. A low
acoustic impedance medium preferably has an acoustic impedance less
than about 1.7 Megarayls, more preferably of about 0-0.7 Megarayls
and most preferably from 0-0.4 Megarayls. As described above,
suitable low acoustic impedance media include, but are not limited
to, helium, argon, air and nitrogen. These media can be delivered
into the chamber 30 during or after the media solidification
process using an injection device such as a hypodermic needle 70.
Similar techniques can be used to draw a vacuum within the chamber
30. Solid low acoustic impedance media such as silicones and
rubbers can be positioned within the chamber 30 during the
formation of the ultrasound assembly 10.
[0114] The methods for forming a catheter described with respect to
FIGS. 10A-10D can be used to form a catheter having multiple
ultrasound assemblies 10. For instance, the elongated body 12
illustrated in FIG. 10A can be replaced with an elongated body 12
having a plurality of ultrasound assemblies 10. Alternatively,
several independent elongated bodies 12 having ultrasound
assemblies 10 can be sequentially positioned within the catheter
sheath 68. The one or more lumens 38 in adjacent elongated bodies
12 are aligned before binding medium 42 precursor is delivered into
the volume defined by the catheter sheath 68. Additional catheters
having a plurality of ultrasound transducers are described in U.S.
patent application No. 09/071,285, filed May 1, 1998 and entitled
Ultrasound Catheter for Providing a Therapeutic Effect to a Vessel
of a Body which is incorporated herein in its entirety.
[0115] When the ultrasound assembly 10 or catheter includes
multiple ultrasound transducers 20, the methods for forming the
ultrasound assembly 10 or catheter can include matching the
resonant frequencies of the ultrasound transducers 20. For
instance, the ultrasound transducers 20 can be selected such that
any member of the plurality of ultrasound transducers 20 has a
resonant frequency within about 10% of the resonant frequency of
any other ultrasound transducer 20. More preferably, the ultrasound
transducers 20 are selected such that any one has a resonant
frequency within about 3%, even more preferably within about 1% and
most preferably within about 0.5% of any other ultrasound
transducer 20 in the plurality of ultrasound transducers 20. The
selected ultrasound transducers 20 are then used to form an
ultrasound assembly 10 or catheter.
[0116] The matching of the ultrasound transducers 20 allows the
ultrasound transducers to be concurrently driven at a single
frequency while reducing the inefficiencies associated with driving
ultrasound transducers 20 at a frequency which is significantly
different than their resonant frequency. Since the ultrasound
transducers 20 can be driven at a single frequency, the matching
the resonant frequencies of the ultrasound transducers 20 is
preferred when the plurality of ultrasound transducers 20 are
connected in parallel or in series.
[0117] The electrical connections for driving the one or more
ultrasound transducers 20 can be done at various stages during the
assembly of the catheter and/or ultrasound assembly 10. For
instance, electrical wires can be coupled with the ultrasound
transducers 20 before the ultrasound transducers 20 are positioned
over the elongated body. Additionally, the electrical wires can be
coupled with the ultrasound transducers 20 after the ultrasound
transducers 20 are in position over the elongated body. Further,
electrical connections can be made alternating with positioning the
ultrasound transducers 20 over the elongated body.
[0118] Alternatively, one or more electrical wires can be
positioned along the elongated body before the ultrasound
transducers 20 are positioned over the elongated body. One or more
ultrasound transducers 20 can then be slid over the elongated body
such that the one or more electrical wires contact the inner side
of the ultrasound transducers 20. The contact between the
ultrasound transducers 20 and the electrical wire can serve as the
electrical connection to the one or more ultrasound transducers 20.
When a catheter or ultrasound assembly 10 includes more than one
ultrasound transducer 20, the ultrasound transducers 20 can be
connected in parallel, in series or independently connected. Wires
extending from the one or more ultrasound transducers 20 can be
threaded up through one or more lumens 38 in the extension body
64.
[0119] During the formation of the catheter and/or formation of the
ultrasound assemblies 10, one or more sensors can be included in
any of the media described above. The sensor can be positioned
within a volume before a medium is delivered into the volume.
Alternatively, the sensor can be delivered into a binding medium 42
precursor while the binding medium 42 precursor is in a flowable
state. Wires extending from the one or more sensors can be threaded
up through one or more lumens 38 in the extension body 64. Suitable
sensors for use with the catheter include, but are not limited to,
a temperature sensor. When a catheter includes one or more
temperature sensors, the temperature sensor is preferably
positioned adjacent to the external side 22 of an ultrasound
transducer 20. Specifically, the one or more temperature sensors
are preferably positioned in a volume between the external side 22
of the ultrasound transducer 20 and the external surface 53 of the
catheter body 52.
[0120] The solidification of the binding medium 42 precursors can
occur concurrently or independently of one another. As discussed
with respect to FIGS. 5A-5F, the binding medium 42 precursor and
the second binding medium 42B precursor preferably solidify to
different degrees of hardness.
[0121] Binding medium 42 precursors for use with the catheters and
ultrasound assemblies 10 discussed above are preferably flowable to
optimize delivery into a desired volume. These precursors
preferably solidify to a binding medium 42 having a reduced
flowability. These precursors more preferably solidify to a binding
medium 42 having a reduced flowability and an increased degree of
adhesiveness. This solidification can occur through mechanisms
including, but not limited to, cooling, setting and curing.
Suitable binding media precursors and/or binding media include, but
are not limited to, adhesives, epoxies, polymers, plastics,
rubbers. Examples of suitable binding media with different degrees
of hardness are EPOTEK 310 having a hardness of about 22 Shore D
and HYSOL 3561 and 2939 having a hardness of about 85 Shore D. The
binding media to be used can be selected for its particular
hardness. Alternatively, binding media, such as epoxies, cure to a
different hardness based on the component ratio in the binding
media. The component ratio can be adjusted to achieve the desired
hardness.
[0122] The binding media adjacent to the external side 22 of the
ultrasound transducer 20 and/or adjacent to the ends of the
ultrasound transducer 20 preferably has an acoustic impedance of
about 1-20 Megarayls, more preferably about 1.3-10 Megarayls and
most preferably about 4-8 Megarayls. As described above, the low
acoustic impedance medium contained within the chambers preferably
has an acoustic impedance less than about 1.7 Megarayls, more
preferably of about 0-0.7 Megarayls and most preferably from 0-0.4
Megarayls. Further, the ratio of the acoustic impedances for the
binding medium adjacent to the external side and/or adjacent ends
the of the ultrasound transducer 20 measured relative to the
acoustic impedance of the low acoustic impedance medium contained
within the chambers is preferably at least 1.5:1, more preferably
at least 2:1 and most preferably at least 4:1. Additionally the
ratio is preferably 1.5:1 to 10,000:1, more preferably about 1.5:1
to 100:1 and most preferably 1.5:1 to 4:1.
[0123] FIG. 11 illustrates the proximal portion 72 of a catheter
according to the present invention. An electrical coupling 74
extends from the proximal portion 72 of the catheter. The
electrical coupling 74 can be coupled with a catheter control
system (not shown) for adjusting the frequency and power of
ultrasound energy delivered from the catheter. These adjustments
can be made in response to signals from one or more sensors
included with the catheter. For instance, these adjustments can be
made in response to signals form a temperature sensor in order to
maintain the temperature at a treatment site within a particular
range.
[0124] The electrical coupling 74 includes an autotransformer 76
for adjusting the characteristic impedance of the catheter to match
the impedance of an amplifier included in the catheter control
system. For instance, if the amplifier has an input impedance of 50
ohms and the catheter has a characteristic impedance of 40 ohms,
the addition of the autotransformer can provide the catheter with a
characteristic impedance of about 50 ohms. The matched impedance
serves to increase the efficiency of the catheter system.
[0125] Because each catheter can have a different characteristic
impedance, the windings on the autotransformer can be adjusted to
match the particular catheter of interest. As a result, a method of
assembling a catheter can include the step of providing an
autotransformer which matches the characteristic impedance of the
catheter to the characteristic impedance of a component in a
catheter control system.
[0126] The electrical coupling also includes catheter
identification electronics 78. The catheter identification
electronics 78 indicate to the catheter control system what
frequency the catheter should be driven. For instance, the catheter
identification electronics 78 can be one or more resistors. The
catheter control system can include logic for identifying the
resistance. This resistance can be associated with a catheter of a
particular frequency. The logic can identify the particular
frequency of the catheter and can then cause the catheter to be
driven at the indicated frequency. A computer chip is another
example of suitable catheter identification electronics 78. The
computer chip can produce signals indicating the frequency of the
catheter to the catheter control system. In response, the catheter
control system can drive the catheter at the appropriate
frequency.
[0127] A catheter according to the present invention can be used by
itself or can be used in conjunction with a sheath 82 as
illustrated in FIGS. 12A-12D. Additional sheath and catheter
embodiments are provided in U.S. patent application No. 09/107,078,
filed Jun. 29, 1998 and entitled Sheath for Use with an Ultrasound
Element which is incorporated herein in its entirety. FIG. 12A
illustrates a sheath 82 configured to receive the catheter. The
sheath 82 includes a sheath proximal end 84 and a sheath distal end
86. A catheter receiving lumen 88 extends through the sheath 82 and
is sized to receive the catheter as illustrated in FIG. 12B. The
sheath distal end 86 preferably includes an energy delivery portion
which is constructed from a material which efficiently transmits
ultrasound energy. Suitable materials for both the sheath 82 and
the energy delivery section 90 include, but are not limited to,
polyethylene.
[0128] The catheter can be rotated or moved within the sheath 82 as
illustrated by the arrow labeled A. The movement of the catheter
within the sheath 82 can be caused by manipulating the proximal
portion of the catheter body 52 while holding the sheath proximal
end 84 stationary. Although not illustrated, the sheath distal end
86 can include on or more temperature sensors.
[0129] As illustrated in FIGS. 12C-12D, the sheath 82 can also
optionally include a drug delivery lumen 92. The drug delivery
lumen 92 can include one or more drug delivery ports 94 through
which a drug can be delivered. The drug delivery lumen 92 can be
straight but is preferably curved and more preferably spirals
around the catheter receiving lumen 88 as illustrated in FIGS. 12C
and 12D. The drug delivery lumen 92 preferably has a diameter/width
of about 0.0005"-0.005" and more preferably about
0.001"-0.003".
[0130] The drug delivery ports 94 are positioned close enough to
achieve a substantially even flow of drug solution around the
circumference of the sheath 82. The proximity of adjacent drug
delivery ports 94 can be changed by changing the density of drug
delivery ports 94 along the drug delivery lumen 92 or by changing
the number of windings of the drug delivery lumen 92 around the
energy delivery section 90. Suitable displacement between adjacent
drug delivery ports 94 includes, but is not limited to, from 0.1"
to 1.0", preferable 0.2" to 0.6".
[0131] The size of the drug delivery ports 94 can be the same or
change along the length of the drug delivery lumen 92. For
instance, the size of the drug delivery ports 94 distally
positioned on the drug delivery section can be larger than the size
of the drug delivery ports 94 which are proximally positioned on
the drug delivery section. The increase in sizes of the drug
delivery ports 94 can be designed to produce similar flowrates of
drug solution through each drug delivery port 94. This similar
flowrate increases the uniformity of drug solution flowrate along
the length of the sheath 82. When the drug delivery ports 94 have
similar sizes along the length of the drug delivery lumen 92, a
suitable size for a drug delivery port includes, but is not limited
to 0.0005" to 0.0050". When the size of the drug delivery ports 94
changes along the length of the drug delivery lumen 92, suitable
sizes for proximally positioned drug delivery ports 94 includes,
but is not limited to from 0.0001" to 0.005" and suitable sizes for
distally positioned drug delivery ports 94 includes, but is not
limited to, 0.0005" to 0.0020". The increase in size between
adjacent drug delivery ports 94 can be substantially uniform
between or along the drug delivery lumen 92. The dimensional
increase of the drug delivery ports 94 is dependent upon material
and diameter of the drug delivery lumen 92. The drug delivery ports
94 can be formed by burnt into the sheath 82 with a laser.
[0132] Uniformity of the drug solution flow along the length of the
sheath 82 can also be increased by increasing the density of the
drug delivery ports 94 toward the distal end of the drug delivery
lumen 92.
[0133] The drug delivery ports 94 can optionally be closed slits in
the sheath 82. The slits can have a straight or arcuate shape. When
the dug delivery lumen 92 contains drug solution, the slits remain
closed until the pressure within the drug delivery lumen 92 exceeds
a threshold pressure. As the pressure within the drug delivery
lumen 92 builds the pressure on each of the slits will be
approximately uniform. Once, the threshold pressure is reached, the
uniform pressure will result in the slits opening almost
simultaneously and cause a nearly uniform flow of drug solution out
of all the slits. When the pressure within the drug delivery lumen
92 falls below the threshold pressure, the slits close and prevent
delivery of additional drug solution. The stiffer the material used
to construct the drug deliver lumen 38, the higher the threshold
pressure required to open the slit shaped drug delivery ports 94.
The slit shape can also prevent the drug delivery ports 94 from
opening when exposed to low pressures from outside the sheath 82.
As a result, slit shaped drug delivery ports 94 can maximize
control of drug delivery.
[0134] FIGS. 13A-13G illustrate a method for using the catheter
with a sheath 82. In FIG. 13A, a guidewire is directed through
vessels toward a treatment site which includes a clot. The
guidewire is directed through the clot. Suitable vessels include,
but are not limited to, cardiovascular vessels, the pancreas,
sinuses, esophagus, rectum, gastrointestinal vessels and urological
vessels.
[0135] In FIG. 13B, the catheter receiving lumen 88 of the sheath
82 is slid over the guidewire and the sheath 82 is advanced along
the guidewire using traditional over-the-guidewire techniques. The
sheath 82 is advanced until the sheath distal end 86 is positioned
at the clot. Radio opaque markers may be positioned at the sheath
distal end 86 to aid in the positioning of the sheath 82 within the
treatment site.
[0136] In FIG. 13C, the guidewire is withdrawn from the utility
lumen 38 by pulling the guidewire proximally while holding the
sheath 82 stationary. In FIG. 13D, a drug solution source is
coupled with the drug inlet port. The drug solution source can be a
syringe with a Luer fitting which is complementary with the drug
inlet port. Pressure can be applied to a plunger on the drug
solution source to drive the drug solution through the drug
delivery lumen 92. The drug solution is delivered from the drug
delivery lumen 92 through the drug delivery ports 94 as illustrated
by the arrows in FIG. 13E. Suitable drug solutions include, but are
not limited to, an aqueous solution containing Heparin, Uronkinase,
Streptokinase, or tissue Plasminogen Activator (TPA).
[0137] In FIG. 13F, the catheter is inserted into the catheter
receiving lumen 88 until the ultrasound assembly 10 is positioned
at the sheath distal end 86. To aid in placement of the catheter
within the sheath 82, radiopaque markers may be positioned on the
catheter adjacent to each of the ultrasound transducers 20.
Alternatively, the ultrasound transducers 20 themselves can be
radiopaque. Once the catheter is properly positioned, the
ultrasound transducer 20 is activated to deliver ultrasound energy
through the sheath 82 to the treatment site. Suitable ultrasound
energy is delivered with a frequency from 5 KHz to 100 MHz, more
preferably from 10 KHz to 25 MHz and most preferably from 20 KHz to
5 MHz. While the ultrasound energy is being delivered, the
ultrasound transducer 20 can be moved within the energy delivery
section 90 as illustrated by the arrows labeled A. The movement of
the ultrasound transducer 20 within the energy delivery section 90
can be caused by manipulating the body proximal section while
holding the sheath proximal end 84 stationary.
[0138] While the present invention is disclosed by reference to the
preferred embodiments and examples detailed above, it is to be
understood that these examples are intended in an illustrative
rather than limiting sense, as it is contemplated that
modifications and combinations will readily occur to those skilled
in the art, which modifications and combinations will be within the
spirit of the invention and the scope of the appended claims.
* * * * *