U.S. patent application number 10/490114 was filed with the patent office on 2004-12-23 for cryoplasty apparatus and method.
Invention is credited to Amir, Uri, Blisweis, Mordechai, McGlone, James, Schechter, Doris, Zvuloni, Roni.
Application Number | 20040260328 10/490114 |
Document ID | / |
Family ID | 26984693 |
Filed Date | 2004-12-23 |
United States Patent
Application |
20040260328 |
Kind Code |
A1 |
Zvuloni, Roni ; et
al. |
December 23, 2004 |
Cryoplasty apparatus and method
Abstract
The present invention relates to apparatus, systems, and methods
utilizing cryogenic cooling in an angioplasty balloon catheter for
treatment of arterial stenosis and prevention of restenosis. More
particularly, the present invention relates to an angioplasty
balloon catheter utilizing expansion of compressed gas to effect
Joule-Thomson cooling of an angioplasty balloon, and optionally
further incorporating external temperature sensors utilizable to
identify a locus for treatment of arterial stenosis. The present
invention further relates to angioplasty treatment systems
incorporating such a catheter, and to cryogenic angioplasty methods
for treating arterial stenosis and discouraging restenosis.
Inventors: |
Zvuloni, Roni; (Haifa,
IL) ; Blisweis, Mordechai; (Haifa, IL) ;
Schechter, Doris; (Zikhron Yakov, IL) ; Amir,
Uri; (Or Yehuda, IL) ; McGlone, James; (Garden
City, NY) |
Correspondence
Address: |
Anthony Castorina
G E Ehrlich
Suite 207
2001 Jefferson Davis Highway
Arlington
VA
22202
US
|
Family ID: |
26984693 |
Appl. No.: |
10/490114 |
Filed: |
August 16, 2004 |
PCT Filed: |
September 26, 2002 |
PCT NO: |
PCT/IL02/00791 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60324937 |
Sep 27, 2001 |
|
|
|
60357653 |
Feb 20, 2002 |
|
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Current U.S.
Class: |
606/194 |
Current CPC
Class: |
A61B 2018/0212 20130101;
A61B 18/02 20130101; A61B 2018/00041 20130101; A61B 2017/22002
20130101; A61B 2017/22051 20130101; A61B 2017/00084 20130101; A61B
2018/0262 20130101; A61B 2017/00101 20130101; F25B 9/02 20130101;
A61B 2018/0022 20130101 |
Class at
Publication: |
606/194 |
International
Class: |
A61M 029/00 |
Claims
What is claimed is:
1. An angioplasty balloon catheter useable to treat arterial
stenosis, comprising a gas input lumen for supplying a pressurized
gas, a first inflatable balloon containing a first variable volume,
and a Joule-Thomson orifice for passing said pressurized gas from
said gas input lumen into said first variable volume so as to cool
and inflate said first inflatable balloon.
2. The catheter of claim 1, further comprising a first gas exhaust
lumen for exhausting gas from said first variable volume of said
first inflatable balloon.
3. The catheter of claim 2, further comprising an exhaust control
valve for controlling exit of exhaust gasses from said first gas
exhaust lumen.
4. The catheter of claim 3, wherein said exhaust control valve is
operable to regulate pressure within said first variable
volume.
5. The catheter of claim 2, further comprising a heat exchanging
configuration designed and constructed to facilitate transference
of heat energy between said gas input lumen and said first gas
exhaust lumen.
6. The catheter of claim 2, wherein at least a portion of said
first gas exhaust lumen is positioned contiguous to at least a
portion of said gas input lumen, thereby constituting a heat
exchanging configuration.
7. The catheter of claim 5, wherein said heat exchanging
configuration comprises a section wherein said gas input lumen is
positioned within said first gas exhaust lumen.
8. The catheter of claim 7, wherein a section of said gas input
lumen, positioned within said first gas exhaust lumen, comprises
fins for facilitating heat exchange.
9. The catheter of claim 5, wherein said heat exchanging
configuration comprises a section wherein said first gas exhaust
lumen is positioned within said gas input lumen.
10. The catheter of claim 9, wherein a section of said first gas
exhaust lumen, positioned within said gas input lumen, comprises
fins for facilitating heat exchange.
11. The catheter of claim 5, wherein said heat exchanging
configuration comprises a section wherein said gas input lumen is
spirally wrapped around said first gas exhaust lumen.
12. The catheter of claim 5, wherein said heat exchanging
configuration comprises a section wherein said first gas exhaust
lumen is spirally wrapped around said gas input lumen.
13. The catheter of claim 5, wherein said heat exchanging
configuration comprises a secondary Joule-Thomson orifice connected
to a source of compressed gas.
14. The catheter of claim 1, wherein said Joule-Thomson orifice is
shaped and oriented so as to induce in gasses passing therethrough
into said first variable volume a motion selected from a group
consisting of circular motion, swirling motion, and turbulent
motion.
15. The catheter of claim 1, further comprising a plurality of
Joule-Thomson orifices.
16. The catheter of claim 14, further comprising a plurality of
Joule-Thomson orifices shaped and oriented so as to induce in
gasses passing therethrough into said first variable volume a
motion selected from a group consisting of circular motion,
swirling motion, and turbulent motion.
17. The catheter of claim 14, wherein said first variable volume of
said first inflatable balloon further comprises a flow control
structure designed and constructed to influence circulation of
moving gasses within said first variable volume.
18. The catheter of claim 17, wherein said flow control structure
comprises at least one of a group consisting of flow directors for
enhancing circular flow, multiple internal channels for subdividing
flow, and spoilers for increasing turbulence.
19. The catheter of claim 1, further comprising a second inflatable
balloon hermetically containing said first inflatable balloon and
defining a second variable volume interior to said second
inflatable balloon and exterior to said first inflatable
balloon.
20. The catheter of claim 19, further comprising a
heat-transmitting material contained within said second volume.
21. The catheter of claim 20, wherein said heat-transmitting
material is selected from a group consisting of a liquid material
and a gel material.
22. The catheter of claim 19, further comprising a second gas
exhaust lumen for exhausting gas from said second volume.
23. The catheter of claim 1, further comprising a guide-wire lumen
enabling passage of a guide wire through said catheter.
24. The catheter of claim 1, further comprising an injection lumen
suitable for injecting a contrast medium near a distal portion of
said catheter.
25. The catheter of claim 1, further comprising a moveable thermal
sensor operable to report external temperatures at selected
positions along a selected length of said catheter, thereby
enabling said catheter to report a temperature gradient along a
selected segment of a body conduit when said catheter is inserted
into said body conduit and said moveable thermal sensor is moved
along said catheter.
26. The catheter of claim 25, wherein said moveable sensor is a
fiber optic element moveable along said catheter and connectable to
a thermographic camera external to said catheter.
27. The catheter of claim 1, further comprising a plurality of
thermal sensors operable to report external temperatures along a
selected length of said catheter, thereby enabling said catheter to
report a temperature gradient along a selected segment of a body
conduit when said catheter is inserted into said body conduit.
28. The catheter of claim 27, wherein said thermal sensors are
selected from a group comprising a thermocouple sensor, a
thermographic camera sensor, and a fiber-optic element connectable
to a thermographic camera sensor external to said catheter.
29. The catheter of claim 27, wherein said thermal sensors are
spirally configured around and along a section of said
catheter.
30. The catheter of claim 27, further including a data
communication element for communicating data generated by said
thermal sensors to a data receiver outside of said catheter.
31. The catheter of claim 30, wherein said data communication
element comprises a wire.
32. The catheter of claim 30, wherein said data communication
element comprises a wireless communicator.
33. The catheter of claim 27, wherein at least one of said
plurality of thermal sensors comprises a hair-like fiber for
enhancing transmission of heat between said at least one sensor and
a body tissue adjacent to said sensor.
34. The catheter of claim 27, wherein said plurality of thermal
sensors are distributed along an expandable spiral sensing loop
having a distal end anchored to a distal portion of said catheter,
said sensing loop being spirally wound around a section of shaft of
said catheter and being operable to expand away from said shaft,
thereby enhancing thermal communication between said sensors
distributed along said sensing loop and body tissues adjacent to
said catheter.
35. The catheter of claim 34, wherein said spiral sensing loop is
designed and constructed to expand away from said shaft of said
catheter when a proximal end of said sensing loop is pushed toward
said anchored distal end of said sensing loop.
36. The catheter of claim 34, wherein said spiral sensing loop is
designed and constructed to contract toward said shaft of said
catheter when a proximal end of said sensing loop is pulled away
from said anchored distal end of said sensing loop.
37. A thermal sensing device designed and constructed to be
spirally wrapped around a catheter insertable into a body conduit,
said thermal sensing device having a distal end designed and
constructed to be anchored to a distal portion of said catheter,
said thermal sensing device comprising a plurality of thermal
sensors mounted on a spring-like spiral base operable to expand
away from said catheter, said expansion enhancing thermal contact
between said thermal sensors and tissue of said body conduit,
thereby enabling said thermal sensing device to report tissue
temperatures along a selected length of said body conduit.
38. The thermal sensing device of claim 37, designed and
constructed to expand away from said catheter when a proximal end
of said sensing device is pushed toward said anchored distal end of
said sensing device.
39. The thermal sensing device of claim 37, designed and
constructed to contract towards said catheter when a proximal end
of said sensing device is pulled away from said anchored distal end
of said sensing device.
40. An angioplasty balloon catheter comprising a moveable thermal
sensor operable to report external temperatures along a selected
length of said catheter, and thereby operable to report a
temperature gradient along a selected segment of a body conduit
when said catheter is inserted into said conduit and said sensor is
moved along said catheter.
41. The catheter of claim 40, wherein said moveable sensor is a
fiber optic element moveable along said catheter and connectable to
a thermographic camera external to said catheter.
42. An angioplasty balloon catheter comprising a plurality of
thermal sensors operable to report external temperatures along a
selected length of said catheter, said catheter being operable to
report a temperature gradient along a selected segment of a body
conduit when said catheter is inserted into said body conduit.
43. The catheter of claim 42, wherein said thermal sensors are
selected from a group comprising a thermocouple sensor, a
thermographic camera sensor, and a fiber-optic element connectable
to a thermographic camera sensor external to said catheter.
44. The catheter of claim 42, wherein said thermal sensors are
arranged in a spiral configuration around and along a section of
said catheter.
45. The catheter of claim 42, further including a data
communication element for communicating data generated by said
thermal sensors to a data receiver outside of said catheter.
46. The catheter of claim 45, wherein said data communication
element comprises a wire.
47. The catheter of claim 45, wherein said data communication
element comprises a wireless communicator.
48. The catheter of claim 42, wherein at least one of said
plurality of thermal sensors comprises a hair-like fiber for
enhancing transmission of heat between said at least one sensor and
a body tissue adjacent to said sensor.
49. The catheter of claim 42, wherein said plurality of thermal
sensors are distributed along an expandable spiral sensing loop
having a distal end anchored to a distal portion of said catheter,
said sensing loop being spirally wound around a section of shaft of
said catheter and being operable to expand away from said shaft,
thereby enhancing thermal communication between said sensors
distributed along said sensing loop and body tissues adjacent to
said catheter.
50. The catheter of claim 49, wherein said spiral sensing loop is
designed and constructed to expand away from said shaft of said
catheter when a proximal end of said sensing loop is pushed toward
said anchored distal end of said sensing loop.
51. The catheter of claim 49, wherein said spiral sensing loop is
designed and constructed to contract toward said shaft of said
catheter when a proximal end of said sensing loop is pulled away
from said anchored distal end of said sensing loop.
52. A system for angioplastic treatment of arterial stenosis and
for reducing restenosis, comprising: a) An angioplasty balloon
catheter useable to treat arterial stenosis, having a gas input
lumen for supplying a pressurized gas, a first inflatable balloon
containing a first variable volume, and a Joule-Thomson orifice for
passing said pressurized gas from said gas input lumen into said
first variable volume of said first inflatable balloon so as to
cool and inflate said first inflatable balloon; b) a supply of
compressed cooling gas operable to supply cooling gas to said gas
input lumen; and c) a cooling gas input valve controlling delivery
of compressed cooling gas from said supply of compressed cooling
gas to said gas input lumen.
53. The system of claim 52, wherein said angioplasty balloon
catheter further comprises a first gas exhaust lumen for exhausting
gas from said first variable volume of said first inflatable
balloon.
54. The system of claim 53, further comprising a gas exhaust valve
for controlling passage of gas out of said gas exhaust lumen.
55. The system of claim 53, wherein said angioplasty balloon
catheter further comprises a heat exchanging configuration designed
and constructed to facilitate transference of heat energy between
said gas input lumen and said first gas exhaust lumen.
56. The system of claim 53, wherein at least a portion of said
first gas exhaust lumen is positioned contiguous to at least a
portion of said gas input lumen, thereby constituting a heat
exchanging configuration.
57. The system of claim 55, wherein said heat exchanging
configuration comprises a section wherein said gas input lumen is
positioned within said first gas exhaust lumen.
58. The system of claim 57, wherein a section of said gas input
lumen, positioned within said first gas exhaust lumen, comprises
fins for facilitating heat exchange.
59. The system of claim 55, wherein said heat exchanging
configuration comprises a section wherein said first gas exhaust
lumen is positioned within said gas input lumen.
60. The system of claim 59, wherein a section of said first gas
exhaust lumen, positioned within said gas input lumen, comprises
fins for facilitating heat exchange.
61. The system of claim 55, wherein said heat exchanging
configuration comprises a section wherein said gas input lumen is
spirally wrapped around said first gas exhaust lumen.
62. The system of claim 55, wherein said heat exchanging
configuration comprises a section wherein said first gas exhaust
lumen is spirally wrapped around said gas input lumen.
63. The system of claim 55, wherein said heat exchanging
configuration comprises a secondary Joule-Thomson orifice connected
to a source of compressed gas.
64. The system of claim 52, wherein said Joule-Thomson orifice is
shaped and oriented so as to induce in gasses passing therethrough
into said first variable volume a motion selected from a group
consisting of circular motion, swirling motion, and turbulent
motion.
65. The system of claim 52, wherein said first inflatable balloon
further comprises a plurality of Joule-Thomson orifices.
66. The system of claim 64, wherein said first inflatable balloon
further comprises a plurality of Joule-Thomson orifices shaped and
oriented so as to induce in gasses passing therethrough into said
first variable volume a motion selected from a group consisting of
circular motion, swirling motion, and turbulent motion.
67. The system of claim 52, wherein said first variable volume of
said first inflatable balloon further comprises a flow control
structure designed and constructed to influence circulation of
moving gasses within said first variable volume.
68. The system of claim 67, wherein said flow control structure
comprises at least one of a group consisting of flow directors for
enhancing circular flow, multiple internal channels for subdividing
flow, and spoilers for increasing turbulence.
69. The system of claim 52, wherein said catheter further comprises
a second inflatable balloon hermetically containing said first
inflatable balloon and defining a second variable volume interior
to said second inflatable balloon and exterior to said first
inflatable balloon.
70. The system of claim 69, further comprising a heat-transmitting
material contained within said second variable volume.
71. The system of claim 70, wherein said heat-transmitting material
is selected from a group consisting of a liquid material and a gel
material.
72. The system of claim 52, wherein said angioplasty balloon
catheter further comprises a guide-wire lumen enabling passage of a
guide wire through said catheter.
73. The system of claim 52, further comprising an injection lumen
suitable for injecting a contrast medium near a distal portion of
said catheter.
74. The system of claim 52, further comprising a second gas exhaust
lumen for exhausting gas from said second internal volume.
75. The system of claim 74, further comprising a helium detector
operable to detect presence of helium in said second gas exhaust
lumen.
76. The system of claim 53, further comprising a supply of
compressed heating gas operable to supply heating gas to said gas
input lumen.
77. The system of claim 76, further comprising a heating gas input
valve controlling delivery of compressed heating gas from said
supply of compressed heating gas to said gas input lumen.
78. The system of claim 52, further comprising a supply of a gas
mixture comprising compressed cooling gas and compressed heating
gas.
79. The system of claim 78, further comprising a mixed-gas input
valve controlling delivery of mixed gas from said supply of a gas
mixture to said gas input lumen.
80. The system of claim 78, further comprising a gas-proportion
input valve controlling a ratio of cooling gas to heating gas in
said supplied mixture of compressed cooling gas and compressed
heating gas.
81. The system of claim 78, further comprising a gas-proportion
input valve system controlling a ratio of cooling gas to heating
gas in said supplied mixture of compressed cooling gas and
compressed heating gas.
82. The system of claim 78, wherein said supply of a gas mixture
comprising compressed cooling gas and compressed heating gas is
operable to supply a gas which produces no significant thermal
effect when passed from a region of high pressure to a region of
low pressure through a Joule-Thomson orifice.
83. The system of claim 82, wherein said supply of a gas mixture is
operable in a first time to supply a gas which produces no
significant thermal effect when passed from a region of high
pressure to a region of low pressure through a Joule-Thomson
orifice, and further operable in a second time to supply a cooling
gas.
84. The system of claim 52, further comprising a vacuum pump for
rapidly withdrawing gas from said first variable volume of said
first inflatable balloon through said first gas exhaust lumen.
85. The system of claim 74, further comprising a vacuum pump for
rapidly withdrawing gas from said second internal volume through
said second gas exhaust lumen.
86. The system of claim 52, further comprising a control unit for
controlling functioning of said catheter, said control unit
comprising: a) a data collection unit for receiving data generated
by at least one sensor positioned in or near a distal portion of
said catheter; b) a processing unit for evaluating data received by
said data collection unit according to a stored algorithm; and c) a
command module for sending commands to at least one remotely
controlled gas flow valve.
87. The system of claim 86, where said at least one sensor is a
thermal sensor.
88. The system of claim 86, wherein said processing unit comprises
a processor and a memory, said memory is operable to record at
least a portion of said received data.
89. The system of claim 88, wherein said processing unit comprises
a display operable to display functional data received by said data
collection unit.
90. The system of claim 88, wherein said processing unit is
designed and constructed to respond to said received data by
evaluating said data under algorithmic control and to generate
commands to be sent to at least one remotely controlled gas flow
valve based on said evaluation.
91. The system of claim 90, wherein said control unit is operable
to substantially maintain a portion of said catheter near a
selected temperature by sending appropriate commands to at least
one selected gas flow control valve, said sent commands being
chosen according to an algorithm in response to data received from
said at least one sensor.
92. The system of claim 90, where said at least one selected gas
flow control valve is selected from a group comprising a cooling
gas input valve, a heating gas input valve, a mixed-gas input
valve, and a gas exhaust valve.
93. The system of claim 53, wherein said cooling gas supply further
comprises a pre-cooling heat exchanging configuration for
pre-cooling supplied cooling gas by exchanging heat between said
supplied cooling gas and said gas exhaust lumen.
94. The system of claim 76, wherein said cooling gas supply further
comprises a pre-cooling heat exchanging configuration for
pre-cooling supplied cooling gas by exchanging heat between said
supplied cooling gas and said gas exhaust lumen, and said heating
gas supply further comprises a pre-heating heat exchanging
configuration, distinct from said pre-cooling heat exchanging
configuration, for pre-heating supplied heating gas by exchanging
heat between said supplied heating gas and said gas exhaust
lumen.
95. The system of claim 52, further comprising a direct venting
valve enabling venting of gasses from said gas input lumen.
96. The system of claim 86, further comprising a direct venting
valve enabling venting of gasses from said gas input lumen, said
direct venting valve being controllable by commands from said
command module of said control unit.
97. The system of claim 52, wherein said angioplasty balloon
catheter further comprises a moveable thermal sensor operable to
report external temperatures at selected positions along a selected
length of said catheter, thereby enabling said catheter to report a
temperature gradient along a selected segment of a body conduit
when said catheter is inserted into said body conduit and said
moveable thermal sensor is moved along said catheter.
98. The system of claim 97, wherein said moveable sensor is a fiber
optic element moveable along said catheter and connectable to a
thermographic camera external to said catheter.
99. The system of claim 52, wherein said angioplasty balloon
catheter further comprises a plurality of thermal sensors operable
to report external temperatures along a selected length of said
catheter, thereby enabling said catheter to report a temperature
gradient along a selected segment of a body conduit when said
catheter is inserted into said body conduit.
100. The system of claim 99, wherein said thermal sensors are
selected from a group comprising a thermocouple sensor, a
thermographic camera sensor, and a fiber-optic element connectable
to a thermographic camera sensor external to said catheter.
101. The system of claim 99, wherein said thermal sensors are
spirally configured around and along a section of said
catheter.
102. The system of claim 99, further including a data communication
element for communicating data generated by said thermal sensors to
a data receiver outside of said catheter.
103. The system of claim 102, wherein said data communication
element comprises a wire.
104. The system of claim 102, wherein said data communication
element comprises a wireless communicator.
105. The system of claim 99, wherein at least one of said plurality
of thermal sensors comprises a hair-like fiber for enhancing
transmission of heat between said at least one sensor and a body
tissue adjacent to said sensor.
106. The system of claim 99, wherein said plurality of thermal
sensors are distributed along an expandable spiral sensing loop
having a distal end anchored to a distal portion of said catheter,
said sensing loop being spirally wound around a section of shaft of
said catheter and being operable to expand away from said shaft,
thereby enhancing thermal communication between said sensors
distributed along said sensing loop and body tissues adjacent to
said catheter.
107. The system of claim 106, wherein said spiral sensing loop is
designed and constructed to expand away from said shaft of said
catheter when a proximal end of said sensing loop is pushed toward
said anchored distal end of said sensing loop.
108. The system of claim 106, wherein said spiral sensing loop is
designed and constructed to contract toward said shaft of said
catheter when a proximal end of said sensing loop is pulled away
from said anchored distal end of said sensing loop.
109. A method of controlling temperature of gasses passing through
a Joule-Thomson orifice, comprising: a) supplying to said
Joule-Thomson orifice a gas mixture comprising a pressurized
cooling gas and a pressurized heating gas in selected proportion;
b) controlling temperature of gasses passing through said
Joule-Thomson orifice by: i) decreasing temperature of gasses
passing through said Joule-Thomson orifice by proportionally
increasing a ratio of cooling gas to heating gas in said gas
mixture; and/or ii) increasing temperature of gasses passing
through said Joule-Thomson orifice by proportionally decreasing a
ratio of cooling gas to heating gas in said gas mixture,
110. The method of claim 109, further comprising pre-mixing said
gas mixture, utilizing pressurized heating gas and pressurized
cooling gas in a selected proportion.
111. The method of claim 109, further comprising utilizing an
automated control unit to select a ratio of cooling gas to heating
gas in said gas mixture by d) receiving temperature data from a
thermal sensor in a vicinity of said Joule-Thomson orifice; and e)
sending control signals to at least one remotely controllable gas
flow valve in response to an algorithmic evaluation of said
received temperature data, thereby modifying said selected ratio of
cooling gas to heating gas in said gas mixture.
112. A method of reducing restenosis after angioplasty, comprising
inflating an inflatable angioplasty balloon with cooling gas
supplied by a high-pressure source of cooling gas passed through a
Joule-Thomson orifice, thereby cooling and inflating said
angioplasty balloon, thereby cooling arterial tissues adjacent to
said balloon during angioplasty, thereby reducing restenosis.
113. A method of reducing restenosis after angioplasty, comprising:
a) performing angioplasty by inflating an inflatable angioplasty
balloon a gas which neither substantially cools nor substantially
heats said during inflation, balloon; and b) cooling said inflated
angioplasty balloon by circulating therein a gas cooled by passage
through a Joule-Thomson orifice, thereby cooling arterial tissues
adjacent to said balloon subsequent to angioplasty, thereby
reducing restenosis.
114. A method providing for safety testing of an angioplasty
balloon catheter having a first inflatable balloon containing a
first variable volume, a gas input lumen operable to introduce gas
into said first variable volume, a second inflatable balloon
hermetically containing said first inflatable balloon and defining
a second variable volume interior to said second inflatable balloon
and exterior to said first inflatable balloon, and a gas exhaust
lumen providing free exit to gas within said second variable
volume, comprising a) introducing a gas into said first variable
volume through said gas input lumen; and b) utilizing a gas
detector to detect presence of said introduced gas in said gas
exhaust lumen, thereby determining whether said introduced gas has
leaked, through a failure of said first inflatable balloon, from
said first variable volume into said second variable volume.
115. The method of claim 114, wherein said introduced gas is helium
gas, and said gas detector is a detector of helium gas.
116. The method of claim 114, further comprising executing steps
(a) and (b) prior to an angioplasty operation, thereby verifying
integrity of said first inflatable balloon prior to using said
angioplasty balloon catheter in a surgical procedure, thereby
contributing to safety of said surgical procedure.
117. A method providing for safe use of an angioplasty balloon
catheter having a first inflatable balloon having a first variable
volume, a gas input lumen operable to introduce gas into said first
variable volume, a Joule-Thomson orifice useable to cool gasses
introduced into said first inflatable balloon, a second inflatable
balloon hermetically containing said first inflatable balloon and
defining a second variable volume interior to said second
inflatable balloon and exterior to said first inflatable balloon,
and a gas exhaust lumen providing free exit to gas within said
second variable volume, comprising the steps of a) utilizing a gas
mixture of pressurized cooling gas and a relatively smaller amount
of an additional gas to cool said first inflatable balloon during
an angioplasty procedure; b) utilizing a gas detector to monitor
gas in said gas exhaust lumen to detect a presence of said
additional gas in said gas exhaust lumen; and c) ceasing all supply
of pressurized gas to said gas supply lumen if presence of said
additional gas is detected in said gas exhaust lumen, thereby
providing for safe use of said angioplasty balloon catheter by
reducing danger of leakage of gas from said catheter into
surrounding tissues.
118. The method of claim 117, wherein said additional gas is
helium, and said gas detector is a detector of helium gas.
119. The method of claim 117, further comprising utilizing a vacuum
pump to rapidly exhaust all gasses from said angioplasty balloon
catheter if a helium leak is detected.
120. A method of accurately positioning an angioplasty balloon
catheter for an angioplasty procedure, the method comprising: a)
introducing into an artery the angioplasty balloon catheter, the
angioplasty balloon catheter having an inflatable balloon operable
to perform angioplasty and a plurality of temperature sensors
arranged along a selected section of said catheter; b) manipulating
said catheter into a selected segment of said artery suspected of
having an aflicted portion; c) operating said temperature sensors
to determine temperatures at a plurality of sites along said
selected segment of said artery; d) comparing said temperature
readings to determine a locus, within said section of said artery,
having a temperatures high than those measured within other
portions of said artery; and e) further manipulating said catheter
so as to position said balloon in a vicinity of said determined
locus, thereby accurately positioning said angioplasty balloon
catheter for said angioplasty procedure.
121. A method of treating a stenotic inflammation of an artery,
comprising: a) introducing into an artery an angioplasty balloon
catheter having an inflatable balloon operable to perform
angioplasty and a plurality of temperature sensors arranged along a
selected section of said catheter; b) manipulating said catheter
into a selected segment of said artery suspected of having an
inflamed portion; c) operating said temperature sensors to
determine temperatures at a plurality of sites along said selected
segment of said artery; d) comparing said temperature readings to
determine a locus, within said section of said artery, having a
temperatures high than those measured within other portions of said
artery; e) further manipulating said catheter so as to position
said balloon in a vicinity of said determined locus; and f)
inflating said balloon so as to compress tissues around said
balloon at said locus, thereby performing angioplasty; thereby
treating said stenotic inflammation of said artery.
Description
FIELD AND BACKGROUND OF THE INVENTION
[0001] The present invention relates to apparatus, systems, and
methods utilizing cryogenic cooling in an angioplasty balloon
catheter for treatment of arterial stenosis and prevention of
restenosis. More particularly, the present invention relates to an
angioplasty balloon catheter utilizing expansion of compressed gas
to effect Joule-Thomson cooling of an angioplasty balloon, and
optionally further incorporating external temperature sensors
utilizable to identify a locus for treatment of arterial stenosis.
The present invention further relates to angioplasty treatment
systems incorporating such a catheter, and to cryogenic angioplasty
methods for treating arterial stenosis and discouraging
restenosis.
[0002] It is a well-known problem of angioplastic surgery that
blood vessels having been subjected to angioplastic treatment have
a marked tendency to undergo restenosis. Blood vessels having
displayed improved vascular flow as result of an angioplasty
intervention are often observed to suffer a subsequent re-narrowing
of the vessel, again impeding vascular flow, in the weeks and
months following the angioplasty intervention. Such restenosis is
currently understood to be a reaction of vascular tissues to the
angioplastic procedure, or to the ongoing endovascular insult.
[0003] Cooling of the site during or immediately following
angioplasty has been found to impede or prevent restenosis. A
number of patents have been issued relating to devices for
cryogenic cooling of tissues during or after angioplasty, and to
angioplasty methods using cooling devices.
[0004] U.S. Pat. No. 5,868,735 to Daniel M. Lafontaine, and U.S.
Pat. No. 6,290,686, also to Lafontaine, both refer to cryogenic
cooling of an angioplasty apparatus, as does U.S. Patent
Application 20020032438 by Lafontaine.
[0005] Lafontaine teaches a method whereby a balloon catheter is
advanced to a target site, the balloon is inflated, and coolant is
delivered into the inflated balloon to freeze a portion of a lesion
adjacent to the balloon, to kill cells within the lesion.
[0006] It is, however, a limitation of the above-mentioned
Lafontaine patents and patent application that the implementations
described are limited to cryogenic cooling by evaporation of a
liquid.
[0007] As is well known, evaporation from a liquid cools that
liquid. If a liquid, such as for example liquid nitrogen, is
maintained under pressure to prevent boiling, and then is passed
into an area where it is free to expand, released pressure allows
boiling or rapid evaporation of the liquid, cooling both the liquid
and the resultant gas.
[0008] Cooling by evaporation is described by Lafontaine as the
method of choice for cryogenic cooling of a cryoplasty balloon
catheter to effect cooling of tissues at an angioplasty site. We
note that although claim 13 of U.S. Pat. No. 6,290,686 op. cit. is
couched in general terms, in that Lafontaine refers to delivering
coolant into the balloon and allowing the coolant to undergo a
phase change within the balloon, the phase change actually
described within Lafontaine's disclosure is a phase change from
liquid to gas, that is, cooling by evaporation.
[0009] U.S. Patent Application 20020010460, submitted by James Joye
et. al. similarly refers to a cryosurgery probe usable to perform
angioplasty, which probe enables cryogenic cooling of tissues at an
angioplasty site. Joye refers to an apparatus in which a single
balloon may function for both cryogenic cooling and for
dilation.
[0010] Joye's application similarly contemplates cooling by
evaporation. Throughout his disclosure, Joye presents and discusses
cooling by evaporation from supplied cooling liquids or liquid/gas
mixtures such as carbon dioxide (CO.sub.2), nitrous oxide
(N.sub.2O), liquid nitrogen (N.sub.2), a fluorocarbon such as
Az-50.TM. (sold by Genetron of Morristown, N.J.), or the like.
Similar systems are presented U.S. Pat. No. 6,355,029 to Joye et.
al. and in U.S. Pat. No. 5,971,979, also to Joye et. al.
[0011] It is to be noted that in each of the above-mentioned
documents Joye refers in passing to the possibility of use of a
Joule-Thomson orifice in the delivery of a cryogenic cooling fluid
into an angioplasty balloon, yet in each of the documents, all of
the implementation details refer to delivery of a liquid rather
than a gas into a balloon or other volume to be cryogenically
cooled. In this sense, the embodiments described in detail by Joye
are similar to those described by Lafontaine in the patents cited
hereinabove, in that evaporation of a liquid, a phase transition
from a liquid to a gaseous state, is the cooling mechanism
described. Thus, for example, Joye states in one context "the
cryogenic fluid will flow through the tube 22 as a liquid at an
elevated pressure and (thus inhibiting flow restrictive film
boiling) will expand across the orifice 23 to a gaseous state at a
lower pressure within the balloon." And similarly: "The methods of
the present invention may be performed with cryosurgical catheters
comprising a catheter body having a proximal end, a distal end, and
a primary lumen therethrough. The primary lumen terminates in a
Joule-Thomson orifice at or near its distal end, and a balloon is
disposed over the orifice on the catheter body to contain a
cryogenic fluid delivered through the primary lumen. Suitable
cryogenic fluids will be non-toxic and include liquid nitrogen,
liquid nitrous oxide, liquid carbon dioxide, and the like. By
delivering the cryogenic fluid through the catheter body, the
balloon can be expanded and cooled in order to effect treatments
according to the present invention."
[0012] Thus, it is to be noted that although Joye employs the term
"Joule-Thomson orifice", he uses it to describe a system wherein a
pressurized liquid passes into a region where it is enabled to
evaporate, thereby to effect cooling. This is to be contrasted to
the embodiments to be described hereinbelow, wherein the cryogenic
fluid delivered to an expandable balloon is a pressurized gas, not
a liquid nor a liquid/gas mixture, and wherein expansion of a
pressurized gas, and not evaporation of a liquid, is the cooling
mechanism. Although the two methods are similar in that both allow
for expansion of a compressed fluid, they are also, in a sense,
almost opposite, in that the phase change initiated by delivery of
a pressurized liquid into the balloon volume is a phase change from
liquid to gas, whereas in a true Joule-Thomson delivery system a
gas is allowed to expand, and by expansion to cool, and the result
of that cooling process may even be, in some cases, a phase
transition in the opposite direction, whereby the expanded gas is
cooled to such an extent that a portion of the expanded gas
actually condenses back into liquid phase.
[0013] Various other patents similarly refer to cooling by
evaporation as a method of cryogenic cooling of an angioplasty
balloon catheter. U.S. Patent Application 20020045892 by Hans W.
Kramer is an additional example of a system utilizing evaporation
of a liquid such as perfluorocarbon to achieve cryogenic cooling in
a balloon catheter. U.S. Pat. No. 5,147,355 to Peter Friedman is
yet another example of a system utilizing evaporation of a liquid
to achieve cryogenic cooling.
[0014] Cooling by evaporation, however, presents a variety of
disadvantages.
[0015] Cooling by evaporation is relatively slow when compared, for
example, to true Joule-Thomson cooling, that is, when cooling by
evaporation is compared to cooling by allowing rapid expansion of a
compressed gas.
[0016] Further, evaporative cooling is not amenable to exact
control of the cooling process, because evaporation is not
instantaneous. Introducing into an angioplasty balloon a liquid
which cools by evaporation inevitably introduces an intrinsic lag
in any possible control of the cooling process, because halting the
supply of cooling fluid does not immediately halt cooling. Liquid
previously introduced into a balloon and not yet evaporated will
continue to cool even after supply of additional cooling liquid has
been halted. In the surgical context of angioplasty interventions,
where treatment typically necessitates blocking of arteries during
a procedure, speed of operation and fine control of temperatures
are of great importance.
[0017] Thus, there is a widely felt need for, and it would be
highly advantageous to have, an apparatus and method of cooling an
angioplasty balloon which provide for rapid cooling and optional
rapid heating of an angioplasty balloon, and which enable accurate,
rapid, and exact control of temperatures within the angioplasty
balloon and/or in the treated body tissues.
[0018] Joye's discussion of uses of his invention, in the documents
cited above, points up several additional problematic aspects of
cryogenic cooling by evaporation. Joye describes the difficulty of
achieving an optimal cooling temperature at a target region, and
further describes the difficulty of achieving an even cooling
distribution throughout a target region.
[0019] With respect to maintenance of a desired temperature within
the cooling apparatus, Joye points out that it is in many cases
desirable to invoke apoptosis and/or programmed cell death so as to
inhibit hyperplasia and/or neoplasia of a blood vessel related to
angioplasty, stenting, rotational or directional artherectomy, or
the like, and he further points out that in order to invole
apoptosis (rather than simply destroying tissues by radical deep
freezing) it will often be desirable to provide more moderate
cryogenic treatment temperatures than those automatically provided
by an uncontrolled evaporation process. Joye does not, however,
provide a method of achieving exact control of cooling within the
target regions. Indeed, he points out that cooling is generally
enhanced by minimizing pressure within the angioplasty balloon.
This link, between pressure of gas within an inflated balloon and
the amount of cooling of that balloon, is one of the disadvantages
of using an evaporation process to achieve cryogenic cooling of an
angioplasty balloon.
[0020] Thus, there is a widely recognized need for, and it would be
highly advantageous to have, an apparatus and method of cryogenic
cooling in an angioplasty balloon catheter which provides for exact
control of temperature within a balloon in a manner relatively
independent of the dilation pressure maintained in that
balloon.
[0021] With respect to the well-known difficulty of achieving an
even cooling distribution throughout a target region, Joye
discusses the fact that evaporative cooling tends to cool an
apparatus unevenly, parts of the apparatus adjacent to a lumen
through which cooling fluid is supplied being significantly colder
than more distant parts of the apparatus. In an attempt to deal
with the problem, Joye proposes a method distribution of a
cryogenic liquid from a supply lumen into a cryogenic balloon,
utilizing a diffuser that causes the cooling fluid to be
distributed both radially and axially. The contemplated diffuser
comprises a tubular structure with radially oriented openings. Joye
points out that as the openings are radially oriented, the diffuser
will direct the cooling fluid roughly perpendicularly toward the
wall of the cryogenic balloon, thereby encouraging even heat
transfer between the cooling vapor and balloon wall. Joye teaches
that distribution of ports circumferentially and axially along the
balloon provides a substantially uniform cooling over a significant
portion of (often over the majority of) the surface of the balloon.
A similar system is also described by Joye in U.S. Pat. No.
6,355,029. We note however that according to Joye's own
description, the desired uniformity is not expected to extend over
the entire surface of the balloon, and in many cases will not
extend even to the majority of the balloon surface.
[0022] Thus, there is a widely recognized need for, and it would be
highly advantageous to have, apparatus and method of cryogenic
cooling of the balloon of an angioplasty balloon catheter, which
method and apparatus provide for accurate control of temperature of
the balloon during cooling, and further provide a highly evenly
distribution of cold throughout that balloon catheter.
[0023] With respect to another aspect of cryogenic balloon
angioplasty, U.S. Patent Application 20020045894 by James Joye et.
al. presents an additional system for cryogenic cooling by
evaporation, this system comprising a double balloon catheter, a
first balloon being inflated by a pressurized gas, and a second
balloon containing the first balloon, with a vacuum between the
two. In U.S. Patent Application 20020045894 Joye presents a safety
interlock system, whereby a rise in pressure in the outer balloon
is interpreted to signal a leak in the inner balloon, and detection
of such a rise in pressure causes his system to cut off supply of
pressurized fluid to the inner balloon, thereby avoiding an
irruption of pressurized fluid into the tissues of a patient
undergoing a surgical intervention. We note, however, a
disadvantage of the described safety interlock system, in that it
is designed to detect such a leak only after a significant rise in
pressure has occurred within the outer balloon.
[0024] Thus, there is a widely recognized need for, and it would be
highly advantageous to have, a system for detecting a leak in such
a balloon angioplasty system, which detection is highly sensitive
to even very small leaks in an inner angioplasty balloon, thereby
enabling to immediately cease supply of input fluids, and to
undertake other or additional corrective measures, as soon as such
a very small leak is detected, and without necessitating waiting
for a leak large enough to significantly raise pressure in an outer
balloon volume.
[0025] Referring now to other aspects of prior art, it is noted
that one of the basic problems inherent in angioplasty and similar
surgical interventions is the need to effect correct placement of
an angioplasty balloon catheter prior to performance of
angioplasty. There is thus a widely recognized need for, and it
would be highly advantageous to have, apparatus and method enabling
accurate placement of an angioplasty balloon catheter based
information garnered at a potential intervention site, by an
angioplasty balloon catheter, in real time.
SUMMARY OF THE INVENTION
[0026] According to one aspect of the present invention there is
provided an angioplasty balloon catheter useable to treat arterial
stenosis, comprising a gas input lumen for supplying a pressurized
gas, a first inflatable balloon containing a first variable volume,
and a Joule-Thomson orifice for passing the pressurized gas from
the gas input lumen into the first variable volume so as to cool
and inflate the first inflatable balloon.
[0027] According to further features in preferred embodiments of
the invention described below, the catheter further comprises a
first gas exhaust lumen for exhausting gas from the first variable
volume of the first inflatable balloon. The catheter may comprise
an exhaust control valve for controlling exit of exhaust gasses
from the first gas exhaust lumen, and the exhaust control valve may
be operable to regulate pressure within the first variable
volume.
[0028] According to still further features in preferred embodiments
of the invention described below, the catheter further comprises a
heat exchanging configuration designed and constructed to
facilitate transference of heat energy between the gas input lumen
and the first gas exhaust lumen. The first gas exhaust lumen may be
positioned contiguous to at least a portion of the gas input lumen,
thereby constituting a heat exchanging configuration. The heat
exchanging configuration may comprise a section wherein the gas
input lumen is positioned within the first gas exhaust lumen and
may have fins for facilitating heat exchange. Alternatively, first
gas exhaust lumen may be positioned within the gas input lumen, and
may have fins for facilitating heat exchange. Alternatively, the
heat exchanging configuration comprises a section wherein the gas
input lumen is spirally wrapped around the first gas exhaust lumen.
Alternatively, the heat exchanging configuration comprises a
section wherein the first gas exhaust lumen is spirally wrapped
around the gas input lumen. The heat exchanging configuration may
comprise a secondary Joule-Thomson orifice connected to a source of
compressed gas.
[0029] According to further features in preferred embodiments of
the invention described below, the Joule-Thomson orifice is shaped
and oriented so as to induce in gasses passing therethrough into
the first variable volume a motion selected from a group consisting
of circular motion, swirling motion, and turbulent motion. The
catheter may further comprising a plurality of Joule-Thomson
orifices, which may be shaped and oriented so as to induce in
gasses passing therethrough into the first variable volume a motion
selected from a group consisting of circular motion, swirling
motion, and turbulent motion.
[0030] According to further features in preferred embodiments of
the invention described below, the first variable volume of the
first inflatable balloon further comprises a flow control structure
designed and constructed to influence circulation of moving gasses
within the first variable volume. Preferably, the flow control
structure comprises at least one of a group consisting of flow
directors for enhancing circular flow, multiple internal channels
for subdividing flow, and spoilers for increasing turbulence.
[0031] According to further features in preferred embodiments of
the invention described below, the catheter further comprises a
second inflatable balloon hermetically containing the first
inflatable balloon and defining a second variable volume interior
to the second inflatable balloon and exterior to the first
inflatable balloon, and may comprise a heat-transmitting material
contained within the second volume, prefereably selected from a
group consisting of a liquid material and a gel material.
[0032] According to further features in preferred embodiments of
the invention described below, the catheter further comprises a
second gas exhaust lumen for exhausting gas from the second
volume.
[0033] According to further features in preferred embodiments of
the invention described below, the catheter further comprises a
guide-wire lumen enabling passage of a guide wire through the
catheter and an injection lumen suitable for injecting a contrast
medium near a distal portion of the catheter.
[0034] According to further features in preferred embodiments of
the invention described below, the catheter further comprises a
moveable thermal sensor operable to report external temperatures at
selected positions along a selected length of the catheter, thereby
enabling the catheter to report a temperature gradient along a
selected segment of a body conduit when the catheter is inserted
into the body conduit and the moveable thermal sensor is moved
along the catheter. The moveable sensor may be a fiber optic
element moveable along the catheter and connectable to a
thermographic camera external to the catheter. Alternatively, the
catheter further comprises a plurality of thermal sensors operable
to report external temperatures along a selected length of the
catheter, thereby enabling the catheter to report a temperature
gradient along a selected segment of a body conduit when the
catheter is inserted into the body conduit. The thermal sensors are
preferably selected from a group comprising a thermocouple sensor,
a thermographic camera sensor, and a fiber-optic element
connectable to a thermographic camera sensor external to the
catheter.
[0035] According to further features in preferred embodiments of
the invention described below, the thermal sensors are spirally
configured around and along a section of the catheter, and the
catheter further includes a data communication element for
communicating data generated by the thermal sensors to a data
receiver outside of the catheter. The data communication element
may comprise a wire or a wireless communicator.
[0036] According to further features in preferred embodiments of
the invention described below, at least one of the plurality of
thermal sensors comprises a hair-like fiber for enhancing
transmission of heat between the at least one sensor and a body
tissue adjacent to the sensor.
[0037] According to further features in preferred embodiments of
the invention described below, the plurality of thermal sensors are
distributed along an expandable spiral sensing loop having a distal
end anchored to a distal portion of the catheter, the sensing loop
being spirally wound around a section of shaft of the catheter and
being operable to expand away from the shaft, thereby enhancing
thermal communication between the sensors distributed along the
sensing loop and body tissues adjacent to the catheter.
[0038] The spiral sensing loop may be designed and constructed to
expand away from the shaft of the catheter when a proximal end of
the sensing loop is pushed toward the anchored distal end of the
sensing loop, or be designed and constructed to contract toward the
shaft of the catheter when a proximal end of the sensing loop is
pulled away from the anchored distal end of the sensing loop.
[0039] According to yet another aspect of the present invention
there is provided a thermal sensing device designed and constructed
to be spirally wrapped around a catheter insertable into a body
conduit, the thermal sensing device having a distal end designed
and constructed to be anchored to a distal portion of the catheter,
the thermal sensing device comprising a plurality of thermal
sensors mounted on a spring-like spiral base operable to expand
away from the catheter, the expansion enhancing thermal contact
between the thermal sensors and tissue of the body conduit, thereby
enabling the thermal sensing device to report tissue temperatures
along a selected length of the body conduit.
[0040] The thermal sensing device of may be designed and
constructed to expand away from the catheter when a proximal end of
the sensing device is pushed toward the anchored distal end of the
sensing device, or designed and constructed to contract towards the
catheter when a proximal end of the sensing device is pulled away
from the anchored distal end of the sensing device.
[0041] According to a further aspect of the present invention there
is provided an angioplasty balloon catheter comprising a moveable
thermal sensor operable to report external temperatures along a
selected length of the catheter, and thereby operable to report a
temperature gradient along a selected segment of a body conduit
when the catheter is inserted into the conduit and the sensor is
moved along the catheter. The moveable sensor may be a fiber optic
element moveable along the catheter and connectable to a
thermographic camera external to the catheter.
[0042] According to yet another aspect of the present invention
there is provided an angioplasty balloon catheter comprising a
plurality of thermal sensors operable to report external
temperatures along a selected length of the catheter, the catheter
being operable to report a temperature gradient along a selected
segment of a body conduit when the catheter is inserted into the
body conduit. The thermal sensors are preferably selected from a
group comprising a thermocouple sensor, a thermographic camera
sensor, and a fiber-optic element connectable to a thermographic
camera sensor external to the catheter, and may be arranged in a
spiral configuration around and along a section of the catheter.
The catheter may further include a data communication element for
communicating data generated by the thermal sensors to a data
receiver outside of the catheter. The data communication element
may comprise a wire or a wireless communicator.
[0043] According to further features in the described preferred
embodiments, at least one of the plurality of thermal sensors
comprises a hair-like fiber for enhancing transmission of heat
between the at least one sensor and a body tissue adjacent to the
sensor.
[0044] According to still further features in the described
preferred embodiments, the plurality of thermal sensors are
distributed along an expandable spiral sensing loop having a distal
end anchored to a distal portion of the catheter, the sensing loop
being spirally wound around a section of shaft of the catheter and
being operable to expand away from the shaft, thereby enhancing
thermal communication between the sensors distributed along the
sensing loop and body tissues adjacent to the catheter.
[0045] The spiral sensing loop may be designed and constructed to
expand away from the shaft of the catheter when a proximal end of
the sensing loop is pushed toward the anchored distal end of the
sensing loop. Alternatively, the spiral sensing loop is designed
and constructed to contract toward the shaft of the catheter when a
proximal end of the sensing loop is pulled away from the anchored
distal end of the sensing loop.
[0046] According to yet another aspect of the present invention
there is provided a system for angioplastic treatment of arterial
stenosis and for reducing restenosis, comprising: an angioplasty
balloon catheter useable to treat arterial stenosis, having a gas
input lumen for supplying a pressurized gas, a first inflatable
balloon containing a first variable volume, and a Joule-Thomson
orifice for passing the pressurized gas from the gas input lumen
into the first variable volume of the first inflatable balloon so
as to cool and inflate the first inflatable balloon; a supply of
compressed cooling gas operable to supply cooling gas to the gas
input lumen; and a cooling gas input valve controlling delivery of
compressed cooling gas from the supply of compressed cooling gas to
the gas input lumen.
[0047] Preferably, the angioplasty balloon catheter further
comprises a first gas exhaust lumen for exhausting gas from the
first variable volume of the first inflatable balloon, a gas
exhaust valve for controlling passage of gas out of the gas exhaust
lumen, and a heat exchanging configuration designed and constructed
to facilitate transference of heat energy between the gas input
lumen and the first gas exhaust lumen.
[0048] Preferably, at least a portion of the first gas exhaust
lumen is positioned contiguous to at least a portion of the gas
input lumen, thereby constituting a heat exchanging configuration.
Alternatively, the heat exchanging configuration comprises a
section wherein the gas input lumen is positioned within the first
gas exhaust lumen, and the gas input lumen, positioned within the
first gas exhaust lumen, comprises fins for facilitating heat
exchange. Further alternatively, the heat exchanging configuration
comprises a section wherein the first gas exhaust lumen is
positioned within the gas input lumen and comprises fins for
facilitating heat exchange. Further alternatively, the heat
exchanging configuration comprises a section wherein the gas input
lumen is spirally wrapped around the first gas exhaust lumen, or a
section wherein the first gas exhaust lumen is spirally wrapped
around the gas input lumen. Further alternatively, the heat
exchanging configuration comprises a secondary Joule-Thomson
orifice connected to a source of compressed gas.
[0049] According to still further features in the described
preferred embodiments, the Joule-Thomson orifice is shaped and
oriented so as to induce in gasses passing therethrough into the
first variable volume a motion selected from a group consisting of
circular motion, swirling motion, and turbulent motion.
[0050] According to still further features in the described
preferred embodiments, the first inflatable balloon further
comprises a plurality of Joule-Thomson orifices.
[0051] According to still further features in the described
preferred embodiments, the first inflatable balloon further
comprises a plurality of Joule-Thomson orifices shaped and oriented
so as to induce in gasses passing therethrough into the first
variable volume a motion selected from a group consisting of
circular motion, swirling motion, and turbulent motion.
[0052] According to still further features in the described
preferred embodiments, the first variable volume of the first
inflatable balloon further comprises a flow control structure
designed and constructed to influence circulation of moving gasses
within the first variable volume.
[0053] According to still further features in the described
preferred embodiments, the flow control structure comprises at
least one of a group consisting of flow directors for enhancing
circular flow, multiple internal channels for subdividing flow, and
spoilers for increasing turbulence.
[0054] According to still further features in the described
preferred embodiments, the catheter further comprises a second
inflatable balloon hermetically containing the first inflatable
balloon and defining a second variable volume interior to the
second inflatable balloon and exterior to the first inflatable
balloon.
[0055] According to still further features in the described
preferred embodiments, a heat-transmitting material is contained
within the second variable volume, the material selected from a
group consisting of a liquid material and a gel material.
[0056] According to still further features in the described
preferred embodiments, the angioplasty balloon catheter further
comprises a guide-wire lumen enabling passage of a guide wire
through the catheter.
[0057] According to still further features in the described
preferred embodiments, the catheter comprises an injection lumen
suitable for injecting a contrast medium near a distal portion of
the catheter.
[0058] This system preferably comprises a second gas exhaust lumen
for exhausting gas from the second internal volume, and a helium
detector operable to detect presence of helium in the second gas
exhaust lumen.
[0059] According to still further features in the described
preferred embodiments, the system comprises a supply of compressed
heating gas operable to supply heating gas to the gas input lumen,
and has a heating gas input valve controlling delivery of
compressed heating gas from the supply of compressed heating gas to
the gas input lumen.
[0060] According to still further features in the described
preferred embodiments, the system further comprises a supply of a
gas mixture comprising compressed cooling gas and compressed
heating gas, and has a mixed-gas input valve controlling delivery
of mixed gas from the supply of a gas mixture to the gas input
lumen. Alternatively, the system has a gas-proportion input valve
controlling a ratio of cooling gas to heating gas in the supplied
mixture of compressed cooling gas and compressed heating gas.
[0061] Preferably, the supply of a gas mixture comprising
compressed cooling gas and compressed heating gas is operable to
supply a gas which produces no significant thermal effect when
passed from a region of high pressure to a region of low pressure
through a Joule-Thomson orifice. Preferably, the supply of a gas
mixture is operable in a first time to supply a gas which produces
no significant thermal effect when passed from a region of high
pressure to a region of low pressure through a Joule-Thomson
orifice, and further operable in a second time to supply a cooling
gas.
[0062] According to still further features in the described
preferred embodiments, the system further comprises a vacuum pump
for rapidly withdrawing gas from the first variable volume of the
first inflatable balloon through the first gas exhaust lumen,
and/or a vacuum pump for rapidly withdrawing gas from the second
internal volume through the second gas exhaust lumen.
[0063] According to still further features in the described
preferred embodiments, the system further comprises a control unit
for controlling functioning of the catheter, the control unit
comprising a data collection unit for receiving data generated by
at least one sensor positioned in or near a distal portion of the
catheter, a processing unit for evaluating data received by the
data collection unit according to a stored algorithm, and a command
module for sending commands to at least one remotely controlled gas
flow valve.
[0064] Preferably, the at least one sensor is a thermal sensor.
[0065] Preferably, the processing unit comprises a processor and a
memory, the memory is operable to record at least a portion of the
received data.
[0066] Preferably, the processing unit comprises a display operable
to display functional data received by the data collection
unit.
[0067] Preferably, the processing unit is designed and constructed
to respond to the received data by evaluating the data under
algorithmic control and to generate commands to be sent to at least
one remotely controlled gas flow valve based on the evaluation.
[0068] Preferably, the control unit is operable to substantially
maintain a portion of the catheter near a selected temperature by
sending appropriate commands to at least one selected gas flow
control valve, the sent commands being chosen according to an
algorithm in response to data received from the at least one
sensor. Preferably, the at least one selected gas flow control
valve is selected from a group comprising a cooling gas input
valve, a heating gas input valve, a mixed-gas input valve, and a
gas exhaust valve.
[0069] According to still further features in the described
preferred embodiments, the cooling gas supply further comprises a
pre-cooling heat exchanging configuration for pre-cooling supplied
cooling gas by exchanging heat between the supplied cooling gas and
the gas exhaust lumen.
[0070] According to still further features in the described
preferred embodiments, the cooling gas supply further comprises a
pre-cooling heat exchanging configuration for pre-cooling supplied
cooling gas by exchanging heat between the supplied cooling gas and
the gas exhaust lumen, and the heating gas supply further comprises
a pre-heating heat exchanging configuration, distinct from the
pre-cooling heat exchanging configuration, for pre-heating supplied
heating gas by exchanging heat between the supplied heating gas and
the gas exhaust lumen.
[0071] According to still further features in the described
preferred embodiments, the system further comprising a direct
venting valve enabling venting of gasses from the gas input lumen.
Preferably, the direct venting valve being controllable by commands
from the command module of the control unit.
[0072] According to still further features in the described
preferred embodiments, the angioplasty balloon catheter further
comprises a moveable thermal sensor operable to report external
temperatures at selected positions along a selected length of the
catheter, thereby enabling the catheter to report a temperature
gradient along a selected segment of a body conduit when the
catheter is inserted into the body conduit and the moveable thermal
sensor is moved along the catheter.
[0073] Preferably, the moveable sensor is a fiber optic element
moveable along the catheter and connectable to a thermographic
camera external to the catheter.
[0074] According to still further features in the described
preferred embodiments, the angioplasty balloon catheter further
comprises a plurality of thermal sensors operable to report
external temperatures along a selected length of the catheter,
thereby enabling the catheter to report a temperature gradient
along a selected segment of a body conduit when the catheter is
inserted into the body conduit. Preferably, the thermal sensors are
selected from a group comprising a thermocouple sensor, a
thermographic camera sensor, and a fiber-optic element connectable
to a thermographic camera sensor external to the catheter.
Preferably, the thermal sensors are spirally configured around and
along a section of the catheter.
[0075] According to still further features in the described
preferred embodiments, the system further includes a data
communication element for communicating data generated by the
thermal sensors to a data receiver outside of the catheter, which
data communication element may comprise a wire or a wireless
communicator.
[0076] According to still further features in the described
preferred embodiments, at least one of the plurality of thermal
sensors comprises a hair-like fiber for enhancing transmission of
heat between the at least one sensor and a body tissue adjacent to
the sensor.
[0077] According to still further features in the described
preferred embodiments, the plurality of thermal sensors are
distributed along an expandable spiral sensing loop having a distal
end anchored to a distal portion of the catheter, the sensing loop
being spirally wound around a section of shaft of the catheter and
being operable to expand away from the shaft, thereby enhancing
thermal communication between the sensors distributed along the
sensing loop and body tissues adjacent to the catheter.
[0078] The spiral sensing loop may be designed and constructed to
expand away from the shaft of the catheter when a proximal end of
the sensing loop is pushed toward the anchored distal end of the
sensing loop, or alternatively the spiral sensing loop is designed
and constructed to contract toward the shaft of the catheter when a
proximal end of the sensing loop is pulled away from the anchored
distal end of the sensing loop.
[0079] According to still another aspect of the present invention
there is provided a method of controlling temperature of gasses
passing through a Joule-Thomson orifice, comprising supplying to
the Joule-Thomson orifice a gas mixture comprising a pressurized
cooling gas and a pressurized heating gas in selected proportion,
controlling temperature of gasses passing through the Joule-Thomson
orifice by decreasing temperature of gasses passing through the
Joule-Thomson orifice by proportionally increasing a ratio of
cooling gas to heating gas in the gas mixture, and/or increasing
temperature of gasses passing through the Joule-Thomson orifice by
proportionally decreasing a ratio of cooling gas to heating gas in
the gas mixture. Alternatively, the method comprises pre-mixing the
gas mixture, utilizing pressurized heating gas and pressurized
cooling gas in a selected proportion.
[0080] Preferably, the method further comprises utilizing an
automated control unit to select a ratio of cooling gas to heating
gas in the gas mixture by receiving temperature data from a thermal
sensor in a vicinity of the Joule-Thomson orifice, and sending
control signals to at least one remotely controllable gas flow
valve in response to an algorithmic evaluation of the received
temperature data, thereby modifying the selected ratio of cooling
gas to heating gas in the gas mixture.
[0081] According to still another aspect of the present invention
there is provided a method of reducing restenosis after
angioplasty, comprising inflating an inflatable angioplasty balloon
with cooling gas supplied by a high-pressure source of cooling gas
passed through a Joule-Thomson orifice, thereby cooling and
inflating the angioplasty balloon, thereby cooling arterial tissues
adjacent to the balloon during angioplasty, thereby reducing
restenosis.
[0082] According to yet another aspect of the present invention
there is provided a method of reducing restenosis after
angioplasty, comprising performing angioplasty by inflating an
inflatable angioplasty balloon a gas which neither substantially
cools nor substantially heats the during inflation, balloon, and
cooling the inflated angioplasty balloon by circulating therein a
gas cooled by passage through a Joule-Thomson orifice, thereby
cooling arterial tissues adjacent to the balloon subsequent to
angioplasty, thereby reducing restenosis.
[0083] According to still another aspect of the present invention
there is provided a method providing for safety testing of an
angioplasty balloon catheter having a first inflatable balloon
containing a first variable volume, a gas input lumen operable to
introduce gas into the first variable volume, a second inflatable
balloon hermetically containing the first inflatable balloon and
defining a second variable volume interior to the second inflatable
balloon and exterior to the first inflatable balloon, and a gas
exhaust lumen providing free exit to gas within the second variable
volume, comprising introducing a gas into the first variable volume
through the gas input lumen, and utilizing a gas detector to detect
presence of the introduced gas in the gas exhaust lumen, thereby
determining whether the introduced gas has leaked, through a
failure of the first inflatable balloon, from the first variable
volume into the second variable volume. Preferably, the introduced
gas is helium gas, and the gas detector is a detector of helium
gas. Preferably, the method further comprises testing of the first
inflatable balloon prior to an angioplasty operation, thereby
verifying integrity of the first inflatable balloon prior to using
the angioplasty balloon catheter in a surgical procedure, thereby
contributing to safety of the surgical procedure.
[0084] According to still another aspect of the present invention
there is provided a method providing for safe use of an angioplasty
balloon catheter having a first inflatable balloon having a first
variable volume, a gas input lumen operable to introduce gas into
the first variable volume, a Joule-Thomson orifice useable to cool
gasses introduced into the first inflatable balloon, a second
inflatable balloon hermetically containing the first inflatable
balloon and defining a second variable volume interior to the
second inflatable balloon and exterior to the first inflatable
balloon, and a gas exhaust lumen providing free exit to gas within
the second variable volume, comprising the steps of a) utilizing a
gas mixture of pressurized cooling gas and a relatively smaller
amount of an additional gas to cool the first inflatable balloon
during an angioplasty procedure, and b) utilizing a gas detector to
monitor gas in the gas exhaust lumen to detect a presence of the
additional gas in the gas exhaust lumen, and c) ceasing all supply
of pressurized gas to the gas supply lumen if presence of the
additional gas is detected in the gas exhaust lumen, thereby
providing for safe use of the angioplasty balloon catheter by
reducing danger of leakage of gas from the catheter into
surrounding tissues. Preferably, the additional gas is helium, and
the gas detector is a detector of helium gas. Preferably, the
method further comprises utilizing a vacuum pump to rapidly exhaust
all gasses from the angioplasty balloon catheter if a gas leak is
detected.
[0085] According to still another aspect of the present invention
there is provided a method of accurately positioning an angioplasty
balloon catheter for an angioplasty procedure, the method
comprising a) introducing into an artery the angioplasty balloon
catheter, the angioplasty balloon catheter having an inflatable
balloon operable to perform angioplasty and a plurality of
temperature sensors arranged along a selected section of the
catheter, b) manipulating the catheter into a selected segment of
the artery suspected of having an aflicted portion, c) operating
the temperature sensors to determine temperatures at a plurality of
sites along the selected segment of the artery, d) comparing the
temperature readings to determine a locus, within the section of
the artery, having a temperatures high than those measured within
other portions of the artery, and e) further manipulating the
catheter so as to position the balloon in a vicinity of the
determined locus, thereby accurately positioning the angioplasty
balloon catheter for the angioplasty procedure.
[0086] According to still another aspect of the present invention
there is provided a method of treating a stenotic inflammation of
an artery, comprising: a) introducing into an artery an angioplasty
balloon catheter having an inflatable balloon operable to perform
angioplasty and a plurality of temperature sensors arranged along a
selected section of the catheter, b) manipulating the catheter into
a selected segment of the artery suspected of having an inflamed
portion, c) operating the temperature sensors to determine
temperatures at a plurality of sites along the selected segment of
the artery, d) comparing the temperature readings to determine a
locus, within the section of the artery, having a temperatures high
than those measured within other portions of the artery, e) further
manipulating the catheter so as to position the balloon in a
vicinity of the determined locus, and f) inflating the balloon so
as to compress tissues around the balloon at the locus, thereby
performing angioplasty, thereby treating the stenotic inflammation
of the artery.
[0087] The present invention successfully addresses the
shortcomings of the presently known configurations by providing an
apparatus and method of cooling an angioplasty balloon enabling
rapid cooling and optional rapid heating of an angioplasty balloon,
and further enabling accurate, rapid, and exact control of
temperatures within that balloon and/or within the treated body
tissues.
[0088] The present invention further successfully addresses the
shortcomings of the presently known configurations by providing an
apparatus and method of cryogenic cooling in an angioplasty balloon
catheter that provides for exact control of temperature within a
balloon in a manner relatively independent of the dilation pressure
maintained within that balloon.
[0089] The present invention further successfully addresses the
shortcomings of the presently known configurations by providing
apparatus and method of cryogenic cooling of the balloon of an
angioplasty balloon catheter, which method and apparatus provide
for accurate control of temperature of the balloon during cooling,
and further provide a highly evenly distribution of cold throughout
that balloon catheter.
[0090] The present invention further successfully addresses the
shortcomings of the presently known configurations by providing a
system for detecting a leak in a balloon angioplasty system, which
detection is highly sensitive to even very small leaks in an inner
angioplasty balloon, thereby enabling to immediately cease supply
of input fluids, and to undertake other or additional corrective
measures, as soon as such a very small leak is detected, and
without necessitating waiting for a leak large enough to
significantly raise pressure in an outer balloon volume.
[0091] The present invention further successfully addresses the
shortcomings of the presently known configurations by providing
apparatus and method enabling accurate placement of an angioplasty
balloon catheter based information garnered at a potential
intervention site by an angioplasty balloon catheter, in real
time.
[0092] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, suitable methods and materials are described below. In
case of conflict, the patent specification, including definitions,
will control. In addition, the materials, methods, and examples are
illustrative only and not intended to be limiting.
[0093] Implementation of the method and system of the present
invention involves performing or completing selected tasks or steps
manually, automatically, or a combination thereof. Moreover,
according to actual instrumentation and equipment of preferred
embodiments of the method and system of the present invention,
several selected steps could be implemented by hardware or by
software on any operating system of any firmware or a combination
thereof. For example, as hardware, selected steps of the invention
could be implemented as a chip or a circuit. As software, selected
steps of the invention could be implemented as a plurality of
software instructions being executed by a computer using any
suitable operating system. In any case, selected steps of the
method and system of the invention could be described as being
performed by a data processor, such as a computing platform for
executing a plurality of instructions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0094] The invention is herein described, by way of example only,
with reference to the accompanying drawings. With specific
reference now to the drawings in detail, it is stressed that the
particulars shown are by way of example and for purposes of
illustrative discussion of the preferred embodiments of the present
invention only, and are presented in the cause of providing what is
believed to be the most useful and readily understood description
of the principles and conceptual aspects of the invention. In this
regard, no attempt is made to show structural details of the
invention in more detail than is necessary for a fundamental
understanding of the invention, the description taken with the
drawings making apparent to those skilled in the art how the
several forms of the invention may be embodied in practice.
[0095] In the drawings:
[0096] FIGS. 1A and 1B are simplified schematics illustrating
alternate basic schemes for constructing an angioplasty balloon
catheter useable to treat arterial stenosis, utilizing
Joule-Thomson cooling, according to an embodiment of the present
invention;
[0097] FIGS. 2A, 2B, and 2C, are simplified schematics presenting
additional optional features of the angioplasty balloon catheter
presented in FIG. 1A., according to an embodiment of the present
invention;
[0098] FIGS. 3A and 3B are simplified schematics illustrating
alternate constructions for heat exchanging configurations useable
within a angioplasty balloon catheter, according to an embodiment
of the present invention;
[0099] FIGS. 4A and 4B are simplified schematics illustrating use
of stents with a cryocatheter, according to an embodiment of the
present invention;
[0100] FIG. 5 is a simplified schematic of a cryocatheter having a
Joule-Thomson orifice so shaped and oriented as to induce selected
patterns of motion in gasses passing therethrough, according to an
embodiment of the present invention;
[0101] FIG. 6 is a simplified schematic of a cryocatheter
comprising a plurality of Joule-Thomson orifices, according to an
embodiment of the present invention;
[0102] FIG. 7 is a simplified schematic of a cryocatheter
comprising flow control structures for directing a flow of gas
within an angioplasty balloon, according to an embodiment of the
present invention;
[0103] FIG. 8 is a simplified schematic of a cryocatheter
comprising two inflatable balloons, according to an embodiment of
the present invention;
[0104] FIG. 9 is a simplified schematic of a system comprising a
cryocatheter and apparatus for controlling operating temperatures
thereof, according to an embodiment of the present invention;
[0105] FIG. 10 is a simplified schematic presenting a system
comprising an apparatus for detecting and for responding to gas
leaks in an inner balloon of a double-balloon catheter, according
to an embodiment of the present invention;
[0106] FIG. 11 is a simplified schematic presenting an optional
alternate construction for a cryocatheter system including several
heat exchanging configurations, according to an embodiment of the
present invention;
[0107] FIG. 12 is a simplified schematic presenting an alternate
configuration for a cryocatheter system, including separate heat
exchanging configurations for cooling gas and for heating gas,
according to an embodiment of the present invention;
[0108] FIG. 13 is a simplified schematic presenting a cryocatheter
comprising an injection lumen and a guide-wire lumen, according to
an embodiment of the present invention;
[0109] FIG. 14 is a simplified schematic presenting an alternate
positioning for a guide wire lumen within a cryocatheter, according
to an embodiment of the present invention;
[0110] FIGS. 15A, 15B, and 15C illustrate, in simplified form,
clinical findings pertaining to a relationship between temperature
of tissues lining a coronary artery and stenotic narrowing of that
artery due to plaque;
[0111] FIG. 16 is a simplified schematic of an angioplasty balloon
catheter comprising a plurality of external temperature sensors,
according to an embodiment of the present invention;
[0112] FIG. 17 presents an expanded view of a section of the
catheter presented in FIG. 16, according to an embodiment of the
present invention;
[0113] FIG. 18 presents recommended dimensions for various parts of
an angioplasty balloon catheter comprising a plurality of external
thermal sensors, according to a preferred embodiment of the present
invention;
[0114] FIG. 19 a simplified schematic presenting an alternate
scheme of placement for thermal sensors along a section of an
angioplasty balloon catheter, according to an embodiment of the
present invention;
[0115] FIG. 20 is a simplified schematic presenting an alternate
design for thermal sensors along a section of an angioplasty
balloon catheter, according to an embodiment of the present
invention.
[0116] FIG. 21 is a simplified schematic presenting a further
alternate design for thermal sensors along a section of an
angioplasty balloon catheter, comprising an internal shaft and an
external multi-sensor thermal sensing device, according to an
embodiment of the present invention;
[0117] FIG. 22 is a simplified schematic of the apparatus of FIG.
21, shown in expanded position, according to an embodiment of the
present invention;
[0118] FIG. 23 is a simplified schematic of an alternative
construction of a multi-sensor thermal sensing device, according to
an embodiment of the present invention;
[0119] FIG. 24 shows the multi-sensor thermal sensing device of
FIG. 23 in expanded position, according to an embodiment of the
present invention; and
[0120] FIG. 25 is a simplified schematic of another alternative
construction for a section of an angioplasty balloon catheter
enabling multiple temperature measurements along a selected section
of an artery, according to an embodiment of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0121] The present invention is of an angioplasty balloon catheter
operable to utilize compressed gas for direct Joule-Thomson cooling
of an angioplasty balloon with a high degree of temperature
control, and having a plurality of temperature sensors operable to
measure temperatures at a variety of locations within an artery,
thereby providing information permitting to identify a locus for
placement of an angioplasty balloon for treatment of arterial
stenosis.
[0122] Specifically, the present invention can be used to
accurately place an angioplasty balloon in a position appropriate
for balloon angioplasty treatment of stenosis, and to directly cool
an angioplasty balloon during use in treatment of stenosis, thereby
discouraging or preventing restenosis.
[0123] The principles and operation of a cryogenic angioplasty
balloon catheter according to the present invention may be better
understood with reference to the drawings and accompanying
descriptions.
[0124] Before explaining at least one embodiment of the invention
in detail, it is to be understood that the invention is not limited
in its application to the details of construction and the
arrangement of the components set forth in the following
description or illustrated in the drawings. The invention is
capable of other embodiments or of being practiced or carried out
in various ways. Also, it is to be understood that the phraseology
and terminology employed herein is for the purpose of description
and should not be regarded as limiting.
[0125] To enhance clarity of the following descriptions, the
following terms and phrases will first be defined:
[0126] The phrase "heat-exchanging configuration" is used herein to
refer to component configurations traditionally known as "heat
exchangers", namely configurations of components situated in such a
manner as to facilitate the passage of heat from one component to
another. Examples of "heat-exchanging configurations" of components
include a porous matrix used to facilitate heat exchange between
components, a structure integrating a tunnel within a porous
matrix, a structure including a coiled conduit within a porous
matrix, a structure including a first conduit coiled around a
second conduit, a structure including one conduit within another
conduit, or any similar structure.
[0127] The phrase "Joule-Thomson heat exchanger" as used herein
refers, in general, to any device used for cryogenic cooling or for
heating, in which a gas is passed from a first region of the
device, wherein it is held under higher pressure, to a second
region of the device, wherein it is enabled to expand to lower
pressure. A Joule-Thomson heat exchanger may be a simple conduit,
or it may include an orifice through which gas passes from the
first, higher pressure, region of the device to the second, lower
pressure, region of the device. A Joule-Thomson heat exchanger may
further include a heat-exchanging configuration, for example a
heat-exchanging configuration used to cool gasses within a first
region of the device, prior to their expansion into a second region
of the device.
[0128] The phrase "cooling gasses" is used herein to refer to
gasses which have the property of becoming colder when passed
through a Joule-Thomson heat exchanger. As is well known in the
art, when gasses such as argon, nitrogen, air, krypton, CO.sub.2,
CF.sub.4, xenon, and N.sub.2O, and various other gasses pass from a
region of higher pressure to a region of lower pressure in a
Joule-Thomson heat exchanger, these gasses cool and may to some
extent liquefy, creating a cryogenic pool of liquefied gas. This
process cools the Joule-Thomson heat exchanger itself, and also
cools any thermally conductive materials in contact therewith. A
gas having the property of becoming colder when passing through a
Joule-Thomson heat exchanger is referred to as a "cooling gas" in
the following.
[0129] Other gasses have the property of becoming hotter when
passed through a Joule-Thomson heat exchanger. Helium is an example
of a gas having this property. When helium passes from a region of
higher pressure to a region of lower pressure, it is heated as a
result. Thus, passing helium through a Joule-Thomson heat exchanger
has the effect of causing the helium to heat, thereby heating the
Joule-Thomson heat exchanger itself and also heating any thermally
conductive materials in contact therewith. Helium and other gasses
having this property are referred to as "heating gasses" in the
following.
[0130] As used herein, a "Joule Thomson cooler" is a Joule Thomson
heat exchanger used for cooling. As used herein, a "Joule Thomson
heater" is a Joule Thomson heat exchanger used for heating.
[0131] As used herein, the term "angioplasty" is used to refer in
particular to balloon angioplasty.
[0132] As used herein, the term "cryoplasty" is used to refer to
angioplasty in which standard angioplasty procedures are
supplemented by cooling of treated tissues, either during
angioplasty or subsequent to angioplasty.
[0133] In discussion of the various figures described hereinbelow,
like numbers refer to like parts.
[0134] Referring now to the drawings, FIG. 1A is a simplified
schematic illustrating a basic schemes for constructing an
angioplasty balloon catheter useable to treat arterial stenosis,
utilizing Joule-Thomson cooling, according to an embodiment of the
present invention. Such a catheter is sometimes referred to as a
"cryocatheter" in the following.
[0135] Elements common to FIGS. 1A and 1B include an angioplasty
balloon catheter 100, of which distal portion 102 is shown, a gas
input lumen 104 for providing pressurized gas from a pressurized
gas source to distal portion 102, and a balloon 110 having a
variable volume 112 capable of holding a gas under pressure. In
typical use, catheter 100 is introduced into an artery or other
body conduit or body cavity with balloon 110 in compressed or
compacted form, the reduced diameter of balloon 110 facilitating
its insertion into the blood vessel or other cavity or conduit.
Subsequently, balloon 110 is expanded by introduction of
pressurized gas into variable volume 112, thereby directly or
indirectly transferring pressure to surrounding tissues.
[0136] Referring now to the configuration presented by FIG. 1A,
pressurized gas supplied through gas input lumen 104 into volume
112 of balloon 110 causes balloon 110 to expand. Expansion of
balloon 110 brings wall 114 of balloon 110 into contact with
surrounding tissues.
[0137] In typical use, catheter 100 is placed in an artery having a
region requiring angioplasty therapy, and then pressurized gas is
supplied to volume 112, causing balloon 110 to expand and forcing
external walls of balloon 110 into contact with tissues 116
surrounding catheter 100, and exerting pressure on those tissues.
Pressure thus induced by balloon 110 on tissues 116 surrounding
balloon 110 constitutes an angioplasty intervention.
[0138] In a preferred embodiment, gas input lumen 104 terminates in
a Joule-Thomson orifice 108. When gas supplied though gas input
lumen 104 is a cooling gas as defined hereinabove, there results a
combined effect in which gas entering volume 112 is both
pressurized, thereby expanding balloon 110, and cold, thereby
cooling balloon 110. Thus, the combination of elements consisting
of gas input lumen 104 supplying pressurized gas through orifice
108 into lower-pressure volume 112 constitutes a Joule-Thomson heat
exchanger 109 as defined hereinabove.
[0139] Balloon 110 is preferably constructed of a thermally
conductive material, hence cooling an inner face of wall 114 of
balloon 110 has the effect of cooling an outer face of wall 114,
thereby cooling body tissues 116 external to, but in close
proximity to, or in contact with, balloon 110.
[0140] Balloon 110 is preferably constructed of one or more
(preferably two) layers of thin plastic material such as PVC or PET
(polyester), or polyethylene tetphthalate or nylon, or similar
material. Thus, balloon 110 may be constructed of material similar
or identical to the materials composing commercially available in
PTA (percutaneous translumenal angioplasty) and PTCA (percutaneous
translumenal coronary angioplasty) systems, such as those sold, for
example, by Cordis Inc., Guidant Inc., Advanced Polymers Inc., and
others. Thickness of balloon wall 114 is preferably between 1 and
100 microns, and most preferably between 5 and 50 microns.
[0141] Gas input lumen 104, designed to contain and transport
high-pressure gas, is preferably constructed of high strength
flexible metal such as stainless steel or Cupro-Nickel, or of high
strength plastic tubing.
[0142] All parts of catheter 100 are constructed of non-toxic
biocompatible materials.
[0143] FIG. 1A presents a presently preferred construction, in
which cooling gas from input lumen 104, having expanded and cooled,
directly cools balloon 110. FIG. 1B presents an alternative
construction, in which volume 112 is further contained within a
tube 120, preferably constructed of plastic or metal, and tube 120
is further contained in a heat-transmission layer 122, preferably
containing a liquid or a gel.
[0144] The construction presented by FIG. 1A has the advantage of
enabling greater miniaturization of catheter 110, a more rapid
cooling process, better cooling power per unit area, and a more
rapid balloon response time during inflation and deflation.
[0145] An advantage of the construction presented by FIG. 1B is
that it is more easily implemented than the construction presented
in FIG. 1A, and can more easily be demonstrated to be safe to
use.
[0146] Attention is now drawn to FIGS. 2A and 2B and 2C, which are
simplified schematics presenting additional optional features the
an angioplasty balloon catheter presented in FIG. 1A, according to
an embodiment of the present invention.
[0147] Common to FIGS. 2A, 2B, and 2C is a flexible tube 160
containing contains gas supply lumen 104 and gas exhaust lumen 130.
Flexible tube 160 flexibly connects distal portion 102 of catheter
100, containing balloon 110, to a supply of compressed gasses and
to various control mechanisms for controlling supply of compressed
gas. Tube 160 is sufficiently flexible to be insertable into a body
conduit such as an artery, and to be operable to follow the natural
path of that conduit during insertion.
[0148] FIG. 2A presents a gas exhaust lumen 130, for voiding gas
from volume 112. In a preferred embodiment, passage of gas from gas
exhaust lumen 130 is controlled by a gas exhaust control valve 132,
which may be a manual valve or a remotely-controlled valve
controllable by commands from an electronic control module 150.
[0149] In a preferred construction, gas exhaust lumen 130 is in
close physical contact with gas input lumen 104, so as to
facilitate exchange of heat between input gas contained in gas
input lumen 104 and exhaust gas contained in gas exhaust lumen 130.
In a particularly preferred construction shown in FIG. 2A, gas
input lumen 104 is largely contained within gas exhaust lumen 130,
thereby constituting a heat exchanging configuration as defined
hereinabove, facilitating heat exchange between the two lumens.
Thus, during a cooling process, cold exhaust gas in gas exhaust
lumen 130 pre-cools input gas in gas input lumen 104, thereby
enhancing the cooling effect of Joule-Thomson heat exchanger
109.
[0150] In an alternate preferred construction, a portion of gas
exhaust lumen 130 may be contained within a portion of gas input
lumen 104, similarly constituting a heat exchanging configuration
for enhancing heat exchange between lumens 104 and 130.
[0151] In a further alternate construction, lumens 104 and 130 are
contiguous and touching over a portion of their length. Such a
construction also constitutes a heat exchanging configuration
serving to enhance heat exchange between lumens 104 and 130.
[0152] Further alternate constructions providing heat exchanging
configurations for pre-cooling and/or pre-heating input gasses are
presented hereinbelow.
[0153] FIG. 2B presents at least one internal heat sensor 140
within catheter 100. In a preferred embodiment, catheter 100
comprises a plurality of heat sensors 140 distributed throughout
catheter 100. Sensor 140 may be a thermocouple 142 or other
heat-sensing device, such as a thermographic camera, or a
fiber-optic fiber operable to transfer infrared radiation to a
thermographic camera or other heat sensor external to catheter 100.
Heat sensor 140 may be connected by wire to an external control
module 150, or may alternatively be connected through a wireless
data link, such as a radio link, to control module 150. Control
module 150 may have a variety of monitoring, reporting, and control
functions, as will be explained in further detail hereinbelow.
[0154] FIG. 2C presents heat exchanging configurations 170
optionally installed in one or more sections of catheter 100, to
facilitate and enhance heat exchange between input gas lumen 104
and exhaust gas lumen 130. The functionality and desirability of
such a transfer of heat has been explained hereinabove. Various
methods for constructing heat exchanging configurations 170 are
well known in the art. One popular example is a spiral
configuration, which might be implemented in catheter 100 by having
gas input lumen 104 spirally wrapped around gas exhaust lumen 130,
or by having gas exhaust lumen 130 spirally wrapped around gas
input lumen 104, or by having both lumens spirally wrapped around
each other, these constructions each serving to increase a surface
of contact between the two lumens so as to facilitate exchange of
heat between them, thereby pre-cooling cooling gas prior to its
arrival at Joule-Thomson orifice 108, or alternatively pre-heating
heating gas prior to its arrival at Joule-Thomson orifice 108.
[0155] Heat exchanging configurations 170 may be optionally
installed at various positions along flexible tube 160, or at the
interface between flexible tube 160 and distal portion 102, or yet
in various positions within a system supplying high-pressure gas to
catheter 100 (not shown). Use of dedicated heat exchanging
configurations 170 is optional. A construction such as that
presented in FIG. 2A, in which input gas lumen 104 is positioned
within exhaust gas lumen 130 over some portion of its length, is in
itself a heat exchanging configuration, and may in some
implementations provide sufficient heat exchanging activity so that
no further dedicated heat exchanging configurations 170 are
required.
[0156] Attention is now drawn to FIGS. 3A and 3B, which are
simplified schematics illustrating additional alternate
constructions for heat exchanging configurations 170. FIG. 3A
presents a heat exchanging configuration wherein a first gas lumen
163 is positioned within a second gas lumen 165, and the first gas
lumen presents fins 176 to enhance heat exchange between the gasses
contained in lumens 163 and 165. As indicated in the figure, such a
heat exchanging configuration can be implemented with gas input
lumen 104 as inner lumen 163 and exhaust gas lumen 130 as outer
lumen 165. As further indicated in the figure, such a heat
exchanging configuration can alternatively be implemented with
exhaust gas lumen 130 as inner lumen 163 and input gas lumen 104 as
outer lumen 165.
[0157] FIG. 3B presents yet another heat exchanging configuration,
in which, secondary gas input lumen 177 and a secondary
Joule-Thomson orifice 178 have been added to a configuration
otherwise similar to that presented in FIG. 3A. The configuration
presented by FIG. 3B might be used, for example, to further enhance
pre-cooling of cooling gas in gas input lumen 104, by combining
pre-cooling power of cold exhaust gasses from gas exhaust lumen 130
with additional pre-cooling power of additional pressurized cooling
gas supplied through secondary gas input lumen 177 and expanded on
passing through Joule-Thomson orifice 178. Supply of gas to
secondary gas input lumen 177, if used, is preferably controlled
through a remotely controlled valve under control of control module
150, described in detail hereinbelow.
[0158] Heat exchanging configurations as illustrated in FIGS. 3A
and 3B may optionally be used as heat exchanging configurations 170
presented in FIG. 2C, or at other locations within catheter 100 or
within a gas supply module supplying pressurized gas to catheter
100.
[0159] In operation of catheter 100, high pressure incoming gas is
supplied to catheter 100 from a gas supply module operable to
supply cooling gas and preferably also operable to supply heating
gas. Incoming gas is preferably initially supplied at or near room
temperature, and is preferably supplied at a pressure between 2000
to 6000 psi, and most preferably at a pressure between 3000 to 4500
psi. Incoming gas flows through input gas lumen 104 and expands
through the orifice 108 inside the balloon 110.
[0160] If the incoming gas is a cooling gas, temperate of this
input gas is reduced drastically through the Joule-Thomson effect
as it passes into balloon 110, reaching a temperature preferably
between 0 C and -186 C, and more preferably between -90 C and -140
C. Attainable temperatures on the surface of balloon 110, in
contact with body tissue, are between -10 C and -80 C. Attainable
temperature gradients for freezing and thawing are up to 100 C per
second.
[0161] Cold gas having served to cool balloon 110 flows out of
balloon 110 and into gas exhaust lumen 130, where it is preferably
used to cool incoming gas in input gas lumen 104, as described
above.
[0162] As shown in FIG. 2A, gas exhaust control valve 132 is
operable to control pressure of exhaust gasses flowing out of
balloon 110. Appropriate manipulation of valve 132 enables to
maintain a desired pressure within balloon 110, preferably between
3 and 50 atmospheres of pressure, and more preferably between 6 and
27 atmospheres.
[0163] Valve 132 may be implemented as a manual valve, yet valve
132 is preferably implemented as a remotely controlled valve under
control of control system 150. Control system 150 is preferably
operable to control flow of exhaust gas through valve 132. Control
system 150 is further operable to control flow of input gasses to
balloon 110, as will be shown hereinbelow. Combined control of
input of gas into balloon 110 and output of exhaust gas from
balloon 110 enables control module 150 to establish and maintain a
desired pressure within balloon 110, or indeed to establish an
maintain a desired pressure profile over time, according to a
pre-planned treatment profile or to real-time preferences of an
operator responding to real-time requirements of a therapeutic
procedure.
[0164] Attention is now drawn to FIGS. 4A and 4B, which are
simplified schematics illustrating the use of stents with
cryocatheter 100, according to an embodiment of the present
invention.
[0165] FIG. 4A shows a catheter 100 whose balloon 110 is deflated
and is covered by a stent 174 in collapsed configuration. In a
preferred embodiment, diameter of distal portion 102 of catheter
100, including deflated balloon and collapsed stent 174, is not
substantially greater than that of flexible tube 160, enabling
distal portion 102 to pass easily along an artery or other body
conduit. As shown in FIG. 4B, when distal portion 102 has been
appropriately positioned in proximity to tissues to be treated,
cooling gasses or other gasses may be used to inflate balloon 110,
thereby performing angioplasty, optionally positioning stent 174 in
expanded configuration within an artery or other body conduit, and
optionally cooling surrounding tissues to discourage restenosis.
Balloon 110 is preferably inflated with cooling gasses so as to
cool treated tissues as they are compressed by the angioplasty
balloon, yet alternatively balloon 110 may be inflated with
non-cooling gasses or with a liquid. Similarly, if it is desired to
heat balloon 110, for example to facilitate disengagement of
catheter 110, such heating is preferably accomplished by supplying
compressed heating gas through input gas lumen 104 through orifice
108 into balloon 110, yet heating may alternatively be accomplished
by supplying low-pressure pre-heated gasses other than heating
gasses, or further alternatively, heating may be accomplished by
supplying a heated liquid through input lumen 104.
[0166] Attention is now drawn to FIG. 5, which is a simplified
schematic of a cryocatheter having a Joule-Thomson orifice shaped
and oriented so as to induce selected patterns of motion in gasses
passing therethrough, according to an embodiment of the present
invention.
[0167] As shown in FIG. 5, high-pressure gas from gas input lumen
104 passes through Joule-Thomson orifice 108 into balloon 110.
Orifice 108 is formed as a shaped nozzle 180 designed and
constructed to induce a selected form of motion in gas passing
therethrough, as indicated by arrows 182. Shaped nozzle 180 may be
oriented in a manner which directs gasses passing therethrough to
circulate within balloon in a circular motion pattern, or
alternately in a manner which directs gasses passing therethrough
to circulate within balloon 110 in a swirling or spiral pattern.
Shaped nozzle 180 may, for example, be placed near an interior wall
of balloon 110 and be oriented tangentially to that wall. Further
alternately, shaped nozzle 180 may be formed in a shape that
deflects gas flow, or nozzle 180 may comprise obstructive shapes
which induce turbulence in gasses passing therethrough into balloon
110.
[0168] As discussed in the background section hereinabove, one
disadvantage of certain prior art systems is the uneven cooling
produced, wherein parts of an angioplasty balloon which are
proximate to the delivery site of evaporative cooling fluid tend to
be much colder than other areas of that angioplasty balloon. The
configuration illustrated by FIG. 5 can be used to reduce or
eliminate uneven cooling, by directing gas cooled by expansion upon
exit from Joule-Thomson orifice 108 to circulate effectively within
balloon 110, thereby enhancing heat transfer between cold gas and
interior walls of balloon 110, thereby contributing to relatively
even cooling throughout all of balloon 110.
[0169] Alternatively, the configuration illustrated by FIG. 5 can
be used to produce intentionally uneven cooling by concentrating
cooling within a selected area of balloon 110. Shaped nozzle 180
can be formed and oriented in a manner which directs a concentrated
flow of cold gas into a selected portion of balloon 110, thereby
enhancing cooling in that selected portion, leaving higher
temperatures in other areas of balloon 110.
[0170] Attention is now drawn to FIG. 6, which is a simplified
schematic of a cryocatheter comprising a plurality of Joule-Thomson
orifices, according to an embodiment of the present invention. As
illustrated in FIG. 6, a catheter 100 comprises a plurality of
Joule-Thomson orifices 108, some or all of which may be formed and
oriented as shaped nozzles 180 designed and constructed to induce a
selected form of motion in gas passing therethrough. The
configuration presented in FIG. 6 may be used to ensure good
circulation of cool gas within balloon 110 so as to enhance even
distribution of cooling throughout balloon 110. Alternatively, a
configuration similar to that presented in FIG. 6, but wherein a
plurality of orifices 108 are concentrated in a selected area of
balloon 110 and distanced from other parts of balloon 110, may be
utilized to concentrate cooling in a selected portion of balloon
110, and to lessen the degree of cooling in non-selected portions
of balloon 110.
[0171] Attention is now drawn to FIG. 7, which is a simplified
schematic of a cryocatheter comprising flow control structures for
directing a flow of gas within an angioplasty balloon, according to
an embodiment of the present invention. As was shown above with
respect to FIGS. 5 and 6, selected number, placement, shape, and
orientation of gas delivery orifices 108 can produce a
configuration which enhances even distribution of cooling gas
throughout balloon 110, or alternatively can be used to produce a
configuration which concentrates cooling in a selected portion of
balloon 110. FIG. 7 presents an alternative (or complementary)
configuration useable to enhance evenly distributed cooling or,
alternatively, to achieve selectively concentrated cooling.
[0172] FIG. 7 presents a catheter 100 wherein interior volume 112
of balloon 110 comprises flow control structures 183 designed and
constructed to influence circulation of moving gasses within volume
112. Several forms of flow control structures are presented.
[0173] Flow directors 184 guide gasses into a desired pattern of
motion. For example, flow directors 184 may be used to enhance
circular flow of gas, or spiral flow of gas.
[0174] Multiple internal channels 186 serve to subdivide gas
flow.
[0175] Spoilers 188 serve to increasing turbulence of circulating
gas.
[0176] Flow control structures 183 are preferably constructed of
material identical to, or similar to, materials of which balloon
110 is constructed.
[0177] Attention is now drawn to FIG. 8, which is a simplified
schematic of a cryocatheter 100 comprising two inflatable balloons,
according to an embodiment of the present invention. FIG. 8
presents a preferred embodiment, in which a first inflatable
balloon 110 defining a first variable volume 112 is hermetically
contained within a second inflatable balloon 210 defining a second
variable volume 212 interior to second inflatable balloon 210 and
exterior to first inflatable balloon 110.
[0178] One possible use of the configuration presented in FIG. 8 is
to fill or partially fill second variable volume 212 with a
heat-transmitting material, such as a liquid, semi-liquid, or gel
material, thus producing a configuration similar to that described
hereinabove with reference to FIG. 1B.
[0179] In a currently preferred embodiment, volume 212 is not
filling with heat-transmitting material, but rather is left
unfilled. A second gas exhaust lumen 230 in fluid communication
with second variable volume 212 is operable to exhaust gas from
volume 212.
[0180] A gas detector 214 is operable to detected presence of gas
in volume 212. In use, volume 212 is initially free of gas, and no
gas is intentionally input therein, consequently if gas detector
214 detects presence of gas from volume 212, such detection may be
taken as an indication that pressurized gas from volume 112 has
leaked into volume 212 through a hole or fault in balloon 110. In a
preferred implementation, detection of gas under such circumstances
is reported to a control unit 150, which may then undertake such
measures as to command gas exhaust valve 132 to release pressure
from balloon 110, command a first emergency gas exhaust pump 216 to
pump all gas from balloon 110, command a gas input valve 218 to
cease supplying gas to gas input lumen 104, and command a second
emergency gas exhaust pump 217 to pump all gas from balloon 210.
Optionally, first and second emergency gas exhaust pumps 216 and
217 can be implemented as a single common pump.
[0181] Gas detector 214 may be a detector of gas pressure, as used
in prior art devices. Yet in a particularly preferred embodiment of
the present invention, gas detector 214 is a helium gas detector,
operable to detect presence of helium gas. Helium detectors are
available having extreme sensitivity to presence of even very small
quantities of helium gas, even to quantities on the order of only a
few PPM. Varian Inc., for example, manufactures such a helium
detector. Consequently, use of a helium detector 220 as gas
detector 214 has significant advantages, in that it allows
detection of even very tiny leaks in balloon 110, when balloon 110
contains any concentration of helium gas. Thus, if gas detector 214
is implemented as helium detector 220, and balloon 110 contains at
least a small concentration of helium gas, the system illustrated
by FIG. 8 is able to detect and respond to extremely small gas
leaks in balloon 110, and in particular is able to respond to leaks
which would likely go undetected if gas detector 214 were merely a
detector of rising gas pressure in volume 212. Thus, use of helium
detector 220 in the configuration presented in FIG. 8 contributes
significantly to enhancing safety of use of catheter 100. The
configuration presented in FIG. 8 may similarly be utilized as a
leak detection and response system for angioplasty balloon systems
incorporating catheters of other types.
[0182] The leak detection system illustrated by FIG. 8 may be used
in a variety of ways. One preferred method of use is to test
catheter 100 prior to use for angioplasty or cryogenic cooling, by
introducing a small amount of helium gas into balloon 110 prior to
inflating balloon 110 with cooling gas or any other fluid. As
stated, the extreme sensitivity of available helium detectors 220
ensures that, if even a small amount of low-pressure helium is
introduced into balloon 110, a fault or leak in balloon 110 will be
detectable by detector 220.
[0183] A currently preferred method of maintaining operational
safety of catheter 100 is to mix a selected portion of helium gas
with cooling gas, or with any other fluid used to inflate balloon
110, not only prior to inflating balloon 110, but also during
normal inflation and cooling operations of catheter 100 as well.
According to this preferred method, at least a small amount of
helium gas is added to whatever cooling gas or other fluid is used
to inflate balloon 110. The extreme sensitivity of available helium
detectors 220 ensures that even a small leak of helium will permit
leak detection, even when the amount of helium added to a fluid
(e.g., a cooling gas) supplied to balloon 110 is sufficiently small
to have little or no substantial effect on the gas temperature
obtained when such a gas mixture passes from a high pressure area
to a low pressure area through Joule-Thomson orifice 108. Thus,
utilizing a cooling gas containing at least a small portion of
helium gas, and utilizing a helium gas detector 220 as illustrated,
enables to detect leaks or faults in balloon 110 with a high degree
of precision and during the entire course of an angioplasty and/or
cryoplasty procedure, thus greatly enhancing the safety of such a
procedure.
[0184] Attention is now drawn to FIG. 9, which is a simplified
schematic of a system comprising a cryocatheter and apparatus for
controlling operating temperatures thereof, according to an
embodiment of the present invention.
[0185] FIG. 9 presents a system 90 for angioplastic treatment of
arterial stenosis and for reducing restenosis.
[0186] System 90 comprises an angioplasty balloon catheter 100
useable to treat arterial stenosis, catheter 100 having a gas input
lumen 104 for supplying a pressurized gas, a first inflatable
balloon 110 containing a first variable volume 112, and a
Joule-Thomson orifice 108 for passing pressurized gas from gas
input lumen 104 into first variable volume 112 of first inflatable
balloon 110 so as to cool and inflate balloon 110.
[0187] System 90 further comprises a supply of compressed cooling
gas 232 operable to supply cooling gas to gas input lumen 104, and
a cooling gas input valve 234 controlling delivery of compressed
cooling gas from compressed cooling gas supply 232 to gas input
lumen 104.
[0188] System 90 further comprises a first gas exhaust lumen 130
for exhausting gas from first variable volume 112 of balloon 110,
and a gas exhaust valve 132 for controlling passage of gas out of
gas exhaust lumen 130.
[0189] System 90 further comprises a supply of compressed heating
gas 236 operable to supply heating gas to gas input lumen 104, and
a heating gas input valve 238 controlling delivery of compressed
heating gas from compressed heating gas supply 236 to gas input
lumen 104.
[0190] Gas supplies 232 and 236, input valves 234 and 238, and
one-way valves 240 and 242, together constitute a gas supply module
230. Gas supply module 230 is operable to supply compressed cooling
gas, to supply compressed heating gas, and to supply a mixture
containing both compressed cooling gas and compressed heating gas.
Valves 234 and 238 together constitute a mixed-gas input valve
system operable to control delivery of mixed gas from gas supply
module 230 to gas input lumen 104, and further operable to control
the ratio of cooling gas to heating gas in a mixed gas supplied to
gas input lumen 104. In an alternative construction, valves 234 and
238 may be combined into a proportional valve governing the
proportion of cooling gas to heating gas delivered to gas input
lumen 104.
[0191] In an alternative construction, a pre-mixed compressed gas
supply 246, flow from which is controlled by a pre-mixed gas input
valve 248, may also supply gas, through a one-way valve 250, to gas
input lumen 104. Pre-mixed compressed gas supply 246 contains a
mixture of cooling gas and heating gas in selected proportion.
Mixed gas supply 246 may be used instead of, or in conjunction
with, cooling gas supply 232 and heating gas supply 236.
[0192] Mixing a heating gas, such as helium, with a cooling gas can
provide a useful service, over an above the gas-leak detection
service described hereinabove with reference to FIG. 8. As
mentioned in the background section hereinabove, in various
surgical procedures, and particularly in treatment of arterial
stenosis, optimal temperature for treatment of afflicted tissues
can be somewhat less cold than the maximum cooling temperature
which can be achieved by a cryocatheter cooled by Joule-Thomson
cooling. In practice, it is desirable that a surgeon be enabled to
exercise control over the operating temperature of catheter 100, so
that he or she can select an appropriate temperature for each
therapeutic situation. Indeed, it is further desirable to enable a
surgeon to specify a temperature profile defined over time,
permitting him or her to specify, for example, an initial
temperature to be maintained during a first selected period,
followed by a second temperature to be maintained during a second
selected period, perhaps followed by a heating cycle used during
disengagement of catheter 100.
[0193] It is noted that gas supply module 230, operable to supply a
mixture of heating and cooling gas, is operable to supply a gas
having a mixture of heating and cooling gasses selected in such
proportion that little or no substantial heating or cooling effect
results when a compressed gas mixture so selected passes through a
Joule-Thomson orifice. Gas supply module 230 can thus be used to
provide a gas operable to inflate balloon 110 without significantly
heating it nor cooling it. According to a preferred embodiment of
the present invention, system 90 is operable to supply such a
non-heating non-cooling mixture to balloon 110 during a first time,
so as to perform angioplasty without cooling, and then subsequently
to supply a cooling gas mixture to balloon 110 during a second
time, so as to cool treated tissues subsequent to, rather than
simultaneously with, compression of those tissues by angioplasty.
Of course, in alternate preferred embodiments, cooling and
angioplasty may be practiced simultaneously, as variously described
herein.
[0194] It is to be noted that various valves illustrated in FIG. 9
as controlling gas flow into and out of balloon 110 are preferably
remotely controllable by commands from control module 150. Gas
exhaust valve 132, useable to control gas flow through gas exhaust
lumen 130, is preferably controllable by control module 150.
Cooling gas input valve 234 controlling flow of cooling gas from
gas supply module 230, and heating gas input valve 238 controlling
gas flow from heating gas source 236, are preferably controllable
by control module 150. Thus, flow of gas passed by cooling gas
input valve 234 and one-way valve 240, through gas input lumen 104
and thence through orifice 108 into balloon 110, and flow of gas
passed by heating gas input valve 236 and one-way valve 242,
through gas input lumen 104 and thence through orifice 108 into
balloon 110, are both controllable by control module 150.
[0195] Control module 150 is preferably operable to control input
valves 234 and 238 according to operator commands, or alternatively
according to programmed commands stored in a memory, or further
alternatively according to algorithmic calculations made according
to programmed commands and applied to data received from sensors
such as sensors 140.
[0196] Thus, gas supply module 230 is operable to supply cooling
gas to gas input lumen 104 when so desired, and to supply heating
gas to gas input lumen 104 when so desired. A gas input module so
configured is well known in cryosurgery practice, where it has
typically been used to provide alternating cooling and heating to
cryoprobes in cryoablation systems, where it accepted practice to
cool a probe to effect cryoablation, and subsequently to heat that
probe after cryoablation to free it from tissues to which a
freezing process has caused it to adhere.
[0197] The configuration presented in FIG. 9 enables, however, a
new and different use of gas supply module 230. According to a
preferred method of operation of the configuration here presented,
cooling gas input valve 234 and heating gas input valve 238 are
operable to provide both cooling gas and heating gas to input gas
lumen 104 simultaneously or nearly simultaneously, so as to obtain
in input gas lumen 104 a mixture 244, which mixture is comprised of
cooling and heating gasses in selected proportion. The effect of
passing such pressurized mixture 244 of heating and cooling gasses
through orifice 108 is to produce a cooling or heating effect in
which the degree of cooling or of heating obtained is finely
controllable. Increasing the proportion of cooling gas in mixture
244 will increase the cooling effect. Decreasing the proportion of
cooling gas in mixture 244 will decrease the cooling effect.
[0198] Management of mixture 244 is preferably controlled by
control module 150, issuing commands to valves 234, 238, and
optionally 248, which commands are determined under algorithmic
control based on calculations made on a basis of data in form of
real-time temperature information received from one or more heat
sensors 140 positioned within balloon 110, or positioned in other
portions of the body of catheter 100, or positioned in tissue areas
proximate to catheter 100, and optionally further based on data
from pressure sensors 141 placed in various positions within system
90.
[0199] Control module 150 can thus operate a feedback control
cycle, in which temperature changes registered by sensors 140 and
reported to control module 150 cause control module 150 to command
changes in relative amounts of gas passed by cooling gas valve 234
and heating gas valve 238, thereby enabling control module 150 to
establish fine control of temperatures in and around catheter 100
during operation.
[0200] It is to be noted that system 90 enables fine control of
temperature, which control is relatively independent of quantities
of gas passing orifice 108, in that a desired cooling effect can be
created by using a relatively small gas flow composed
preponderantly of cooling gas, or by using a relatively large flow
of gas composed of relatively less cooling gas and somewhat more
heating gas.
[0201] This relative independence of the cooling effect from the
absolute amount of gas flow is particularly useful in the context
of angioplastic therapy, since it enables a surgeon, preferably
through use of control services provided by control module 150, to
independently manipulate pressure maintained in balloon 110 on the
one hand, and temperature maintained in balloon 110 on the other
hand.
[0202] Control module 150 provides various control and monitoring
functions for the system presented in FIG. 9. Control module 150
preferably comprises a data collection unit 260 for receiving data
generated by at least one sensor positioned in or near a distal
portion of catheter 100, such as thermal sensors 140 and pressure
sensors 141. Control module 1 S0 preferably further comprises a
processing unit 262 for evaluating data received by data collection
unit 260 according to a stored algorithm 264, and a command module
265 for sending commands to one or more remotely controlled gas
flow valves, such as valves 234, 248,238, and 132.
[0203] Processing unit 262 preferably comprises a processor 266 and
a memory 268, memory 268 being operable to record at least a
portion of data received by data collection unit 260. Processing
unit 262 optionally comprises a display 270 operable to display
functional data received by data collection unit 260.
[0204] Processing unit 262 is preferably designed and constructed
to respond to received data, to evaluate it under algorithmic
control, to generate commands based on these algorithmically
controlled evaluations, and to send commands so generated to valves
234, 248, 238, 132, and to other valves and remotely controllable
units within system 90.
[0205] As described hereinabove, in a preferred embodiment control
unit 150 is operable to substantially maintain a portion of
catheter 100 near a selected temperature, by sending appropriate
commands to at least one, and preferably more than one, gas flow
control valve, using commands chosen according to an algorithm in
response to data received from sensor 140, and preferably from a
plurality of sensors, including thermal sensors and pressure
sensors.
[0206] In an optional preferred embodiment, system 90 may be
implemented utilizing as catheter 100 a double-balloon catheter
such as that discussed hereinabove with reference to FIG. 8. In
such an embodiment, gas detector 214 (preferably helium detector
220), integrated into system 90, is operable to report detection of
gas (preferably detection of helium) to control module 150. Command
module 150, upon receipt of a report of gas detection by detector
214, is operable to command actions by emergency vacuum pumps 216
and 217 and gas input valve 218, according to a programmed response
pattern.
[0207] In an additional optional preferred embodiment, system 90
may also be implemented utilizing, in place of cryocatheter 100, a
cryoablation probe designed and constructed for cryoablation of
tumors. A system so constructed, utilizing mixed gas 244 to provide
fine control of degree of cooling as explained hereinabove, may be
used to advantage in cryoablation applications in which
less-than-maximal cooling of a cryoprobe is desired for clinical
reasons.
[0208] Attention is now drawn to FIG. 10, which is a simplified
schematic presenting an embodiment of system 90 comprising a
double-balloon catheter 100, and apparatus for detecting and for
responding to gas leaks in inner balloon 110. The system presented
in FIG. 10 may be seen to include the various characteristics of
system 90 as described hereinabove with respect to FIG. 9, and to
further included the double-balloon catheter, gas leak detection
mechanism, and gas leak response apparatus described hereinabove
with respect to FIG. 8.
[0209] Attention is now drawn to FIG. 11, which is a simplified
schematic presenting an optional alternate construction for system
90, according to an embodiment of the present invention. The system
illustrated in FIG. 11 is distinguished by the presence of heat
exchanging configurations 170 in a plurality of functional
positions within the system.
[0210] In FIG. 11, system 90 has been conceptually subdivided into
one external and three internal units.
[0211] Gas supply module 230, containing mechanisms for gas supply
and gas input control, for helium detection and leak control, and
for emergency vacuum pumping, is external to the patient's
body.
[0212] Catheter 100, designed for insertion into the body, is
conceptually divided into three sections. Endovascular-precoronary
section 280 comprises flexible tube 160, designed to be flexibly
inserted into a blood vessel or other bodily conduit of a patient.
Coronary section 282, preferably about 25 cm in length, is designed
to enter the coronary region of the body during an angioplasty
procedure. Distal portion 102 consists primarily of inflatable
balloon 110, and optional second inflatable balloon 210.
[0213] As shown in FIG. 10, heat exchanging configurations 170 may
be utilized in various areas, to enhance the efficiency with which
cryogenic cooling is accomplished. Heat exchanging configuration
170A is placed at a point of transition between coronary section
282 and distal portion 102. Heat exchanging configuration 170B is
placed at a point of transition between coronary section 282 and
endovascular-precoronary section 280. Other emplacements for heat
exchanging configurations 170, within sections 280, 282 and 102,
may also be used.
[0214] Another optional placement for a heat exchanging
configuration 170 is shown in FIG. 11 as heat exchanging
configuration 170C. Heat exchanging configuration 170C is an
integrated component of gas supply module 230, and thus is
positioned outside the body during operation.
[0215] Each of the heat exchanging configurations 170A, 170B, and
170C is operable to exchange heat between exhaust gas from exhaust
gas lumen 130 and input gas within, or flowing towards, input gas
lumen 104. Additional heating and cooling systems may be utilized
in addition to, or in place of, one or more heat exchanging
configurations 170. In particular, a pre-cooling system 171 may be
used in addition to, or in place of, heat exchanging configuration
170C, within gas supply module 230, utilizing electrical cooling, a
closed refrigeration cycle, a liquid nitrogen bath, liquid nitrogen
secondary flow, or other similar methods.
[0216] Alternate gas heating methods may also be used to provide
heat to catheter 100. An electrically heated low-pressure gas
supply 173 may be so used. Units 171 and 173, if used, are
preferably controlled by control unit 150.
[0217] Optional high-pressure vent 286 is provided, preferably near
a coupling between gas supply module 230 and cryocatheter 100, for
selectively venting gas from input lumen 104. Use of vent 286 may
be useful in a variety of circumstances. During an emergency such
as detection of a gas leak in balloon 110, it may be desirable to
immediately reduce pressure in balloon 110. Additionally, a desired
rapid change of operating temperature within balloon 110, for
example a change from a cooling phase of operation to a heating
phase of operation, is best accomplished by venting pressurized gas
of one type (e.g., cooling gas) in input lumen 104, before starting
to supply gas of a second type (e.g., heating gas) to input lumen
104. High-pressure vent 286 is preferably controlled by control
module 150.
[0218] Each heat exchanging configuration 170 is preferably
equipped with a thermal sensor 140 operable to report operating
temperatures to control module 150. Additional thermal sensors 140
may be positioned at other sites within catheter 100, or indeed at
additional sites external to catheter 100, such as within gas
supply module 230, or within body tissues of a patient in proximity
to catheter 100.
[0219] Attention is now drawn to FIG. 12, which presents an
additional alternate configuration for system 90. FIG. 12 features
separate heat exchanging configurations 170D and 170E in place of
heat exchanging configuration 170C of FIG. 11. Heat exchanging
configuration 170D is operable to pre-cool cooling gas from cooling
gas supply 232 on its way to input gas lumen 104, preferably using
exhausted cold gas from gas exhaust lumen 130. Heat exchanging
configuration 170E is operable to pre-heat heating gas from heating
gas supply 236 on its way to input gas lumen 104, using exhausted
hot gas from gas exhaust lumen 130. Heat exchanging configurations
170D and 170E may optionally be constructed according to
configurations described hereinabove with reference to FIGS. 3A and
3B.
[0220] Input valves controlling input of cooling gas may be placed
at position 234A or at position 234B, or in both positions. Input
valves controlling input of heating gas may be placed at position
238A or at position 238B, or in both positions.
[0221] The configuration presented by FIG. 12 is useful because
efficient heat exchange, in heat exchanging configurations 170C,
170D, and 170E, requires a relatively large internal volume of gas
within those heat exchanging configurations. Using a common heat
exchanging configuration 170C both to pre-cool cooling gas and to
pre-heat heating gas, as is done in the configuration presented by
FIG. 11, has an effect of reducing speed of response of system 90
to a change from a first gas input (e.g., cooling gas) to a second
gas input (e.g., heating gas), since a relatively large volume of a
first gas must be flushed from heat exchanging configuration 170C
before heat exchanging configuration 170C can be entirely filled
with, and dedicated to the pre-cooling or pre-heating of, an
intended second gas.
[0222] A more rapid response to a change from cooling to heating,
or from heating to cooling, maybe obtained from the configuration
presented in FIG. 12, wherein each gas source has a dedicated heat
exchanging configuration, 170D dedicated to pre-cooling cooling
gas, and 170E dedicated to pre-heating heating gas. Input valves
234A and/or 234B and 238A and/or 238B need merely be closed and
opened appropriately, to produce an almost immediate response from
gas supply module 230, with no delay required for flushing the
system of inappropriate gas.
[0223] Attention is now drawn to FIG. 13, which is a simplified
schematic presenting additional features of a cryocatheter
according to an embodiment of the present invention.
[0224] FIG. 13 presents a catheter 100 comprising an optional
injection lumen 290 suitable for injecting a material near distal
portion 102 of catheter 100. Injection lumen 290 is useful for
injecting, for example, a contrast imaging material into are area
near a treatment site, to facilitate imaging of that site, thereby
facilitating correct placement of catheter 100 for treatment, or
thereby facilitating evaluation of an ongoing or completed
angioplasty procedure.
[0225] FIG. 13 further presents a guide-wire lumen 292 for enabling
and guiding passage of a guide wire through a length of catheter
100. According to a common surgical practice, a guide wire is often
used to guide insertion of an angioplasty catheter during an
angioplasty procedure. Guide wire lumen 292 serves to permit
passage of a guide wire 294 along an internal length of catheter
100, providing compatibility with standard wire-guided angioplasty
procedures.
[0226] Attention is now drawn to FIG. 14, which is a simplified
schematic presenting an alternate positioning for a guide wire
lumen within a cryocatheter, according to an embodiment of the
present invention. Whereas guide wire lumen 292 presented in FIG.
13 is centered within catheter 100 and particularly within balloon
110, circumferential guide wire lumen 296 presented in FIG. 14 has
a circumferential positioning within balloon 110. Such
circumferential positioning permits guide wire lumen 296, and
within it guide wire 294, to be embedded within wall 114 of balloon
110, for example between adjacent layers of material forming wall
114.
[0227] Attention is now drawn to FIGS. 15A, 15B, and 15C, which
illustrate in simplified form clinical findings of a relationship
often found to obtain between temperature of tissues lining a
coronary artery and stenotic narrowing of arteries due to
plaque.
[0228] FIG. 15A schematically illustrates a section of coronary
artery 308 in which blood flow is impeded by a narrowing, caused by
plaque 312.
[0229] FIG. 15B presents a temperature graph 314 of coronary artery
section 308, where temperature is plotted on a vertical axis
against position plotted on a horizontal axis, the horizontal axis
being common to FIGS. 15A, 15B, and 15C. FIG. 15B presents a
well-known clinical finding, that areas narrowed by plaque tend to
have a higher temperature than other, healthier, areas within a
same arterial section. This temperature differential, apparently
resulting from an inflamed state of tissues at the site of the
restriction, may be used to localize that restriction for
treatment. FIG. 15C shows a balloon catheter (e.g., catheter 100)
appropriately positioned for treating the condition seen in FIG.
15A and localized by temperature chart 15B.
[0230] Attention is now drawn to FIG. 16, which is a simplified
schematic of an angioplasty balloon catheter comprising a plurality
of external temperature sensors located along a selected section
thereof, according to an embodiment of the present invention.
[0231] In FIG. 16, angioplasty balloon catheter 300 comprises an
inflatable balloon 310 operable to perform angioplasty, and a
plurality of temperature sensors 320 (also called "thermal sensors"
and "heat sensors" in the following) arranged along a selected
section of catheter 300. Catheter 300 may have the characteristics
of catheter 100 described hereinabove, or alternatively may be a
cryogenic balloon catheter coolable using methods of prior art, or
further alternatively may be a cryogenic balloon catheter coolable
using other methods of cooling, or yet further alternatively
catheter 300 may be an angioplastic balloon catheter not comprising
mechanisms for cooling balloon 310.
[0232] Temperature sensors 320 may be thermocouples 322, or
thermographic camera sensors 324, or fiber-optic fibers 326
operable to transmit infra-red light from a tissue site to a
thermographic camera sensor 324 external to catheter 300, or any
other sensor operable to report temperatures in a vicinity of body
tissues in proximity to catheter 300, when catheter 300 is inserted
in an artery or other body conduit.
[0233] Attention is now drawn to FIG. 17, which presents an
expanded view of a section of the catheter presented in FIG. 16,
showing in greater detail a plurality of heat sensors placed along
an external length of that catheter, according to an embodiment of
the present invention. In an optional embodiment shown in FIG. 17,
heat sensors 320 are shown to be linked by a data link 328, which
may be a wire or bundle of wires operable to connect thermocouples
322 to an outside data receiver such as control module 150
described hereinabove. Data link 328 may also be a bundle of
fiber-optic fibers 326, or any other sort of data communicator.
Sensors may also be linked to an outside data collector such as
control module 150 using a wireless communicator 329.
[0234] Attention is now drawn to FIG. 18, which presents
recommended dimensions for various parts of an angioplasty balloon
catheter comprising a plurality of external thermal sensors along a
selected section thereof, according to a preferred embodiment of
the present invention. The dimensions provided in FIG. 18 are
presently recommended dimensions for a catheter combining the
characteristics of catheter 100 and catheter 300, both defined and
described hereinabove.
[0235] Attention is now drawn to FIG. 19, which is a simplified
schematic presenting an alternate scheme of placement for thermal
sensors along a section of an angioplasty balloon catheter,
according to an embodiment of the present invention. FIG. 19
presents a section of catheter similar to that presented in FIG.
17, with the difference that in an alternative construction
presented in FIG. 19, thermal sensors 320 are spirally positioned
around and along a selected segment of catheter 300, thus enabling
temperature readings an all sides of catheter 300 along that
selected length of catheter 300.
[0236] Attention is now draw to FIG. 20, which is a simplified
schematic presenting an alternate design for thermal sensors along
a section of an angioplasty balloon catheter, according to an
embodiment of the present invention. FIG. 20 presents a section of
catheter similar to that presented in FIG. 19, with the difference
that in an alternative construction presented in FIG. 20, thermal
sensors 320 comprise a hair-like fiber 330 designed and constructed
to facilitate transfer of heat between thermal sensors 320 and body
tissues surrounding catheter 300 and adjacent to thermal sensors
320. Hair-like fibers 330 extend slightly outward from catheter
300, and thus are able to make physical contact with surrounding
tissues, such as with portions of an arterial wall, when catheter
300 is inserted in an artery. Such contact enhances accuracy of
temperature readings from sensors 320, in that such contact
enhances ability of sensors 320 to report temperature of arterial
wall tissues, as opposed, say, to temperature of blood flowing in
an artery in which catheter 300 has been inserted.
[0237] Attention is now drawn to FIG. 21, which is a simplified
schematic presenting a further alternate design for thermal sensors
along a section of an angioplasty balloon catheter, according to an
embodiment of the present invention. FIG. 21 presents a section 340
of angioplasty balloon catheter 300, section 340 comprising an
internal shaft 342 and an external multi-sensor thermal sensing
device 350.
[0238] Shaft 342 is preferably a flexible tube. If catheter 300 is
formed as catheter 100 described hereinabove, then shaft 342 will
contain input gas lumen 104, exhaust gas lumen 130, and may contain
various other optional features heretofore described.
[0239] Multi-sensor thermal sensing device 350 comprises a
laterally contracting spring-like structure 344, preferably of
spiral form, wrapped around shaft 342. Sensing device 350,
preferably formed as a spiral sensing loop, further comprises a
plurality of individually readable heat sensors. 320, sensors 320
being substantially similar to heat sensors 320 previously
described with reference to FIGS. 16, 17, 19, and 20.
[0240] Laterally contracting spring-like structure 344 is
preferably anchored at its distal end to a fixed position 346 on
shaft 342, whereas a proximal end of structure 344 is free to move
longitudinally along shaft 342. In its relaxed position, laterally
contracting spring-like structure 344 is designed and constructed
to lie closely adjacent to shaft 342, as is shown in FIG. 21. Thus
positioned, sensing device 350 does not add substantially to the
diameter of catheter 300, and thus leaves catheter 300 free to move
forward and backwards within an artery or other body conduit. With
structure 344 positioned as depicted in FIG. 21, catheter 300,
together with multi-sensor thermal sensing device 350, is free to
move within arterial walls 348.
[0241] Attention is now drawn to FIG. 22, which is a simplified
schematic of the apparatus of FIG. 21, shown in expanded position.
Structure 344 is so designed that when longitudinal pressure is
applied to the proximal end of structure 344, towards fixed
position 346, structure 344 is forced to expand, in spring-like
manner, away from shaft 342. A movement of expansion thus
engendered forces structure 344 into contact with arterial walls
348 surrounding catheter 300, as is shown in FIG. 22. Sensors 320
positioned along the length of structure 344 are thus forced into
contact, or into close proximity, with body tissues lining arterial
walls 348. Such contact or proximity enhances transfer of heat from
those body tissues to sensors 320, thereby enhancing accuracy of
thermal sensing by sensors 320.
[0242] Attention is now drawn to FIGS. 23 and 24, which show a
slightly altered construction for multi-sensor thermal sensing
device 350, according to a preferred embodiment of the present
invention.
[0243] Design and construction of sensing device 350 as shown in
FIGS. 23 and 24 is identical to that shown in FIGS. 21 and 22, with
the exception that a spiral sensing loop formed as a laterally
expanding spring-like structure 354 is substituted, in FIGS. 23 and
24, for a spiral sensing loop formed as laterally contracting
spring-like structure 344 of FIGS. 21 and 22. Laterally expanding
spring-like structure 354 is so constructed that in its relaxed
state structure 354 tends to expand away from shaft 342, as shown
in FIG. 24. A pulling attachment 352 is provided for pulling a
proximal end of structure 354 away from a distal end of structure
354 anchored at position 346.
[0244] As shown in FIG. 23, during introduction of catheter 300
into an artery or other body conduit, pulling attachment 352 is
pulled away from anchored position 346, thereby stretching
structure 344 along shaft 342, thereby minimizing distance between
device 350 and shaft 342, thereby facilitating movement of catheter
300 along an artery or other body cavity and minimizing friction or
other interference between catheter 300 and arterial walls 348.
[0245] When catheter 300 is thought by an operator to be positioned
in the vicinity of a lesion, pulling attachment 352 is released,
allowing laterally expanding spring-like structure 354 to expand to
its relaxed position, as shown in FIG. 24. As may be seen in the
figure, structure 354 in its relaxed state tends to bring sensors
320 into close proximity to, or into contact with, body tissues
surrounding catheter 300, such as arterial walls 348. Transfer of
heat between arterial walls 348 and sensors 320 is thereby
enhanced, thereby enabling device 350 to accurately sense and
report temperatures at or near those body tissues.
[0246] Thus, to summarize FIGS. 21, 22, 23, and 24, each of the
figures represents a catheter 300 having a plurality of thermal
sensors distributed along an expandable spiral sensing loop having
a distal end anchored to a distal portion of catheter 300. This
expandable spiral sensing loop is spirally wound around a section
of shaft of catheter 300, and is operable to expand away from that
shaft, thereby enhancing thermal communication between sensors
distributed along that sensing loop and body tissues adjacent to
catheter 300. In the configuration presented by FIGS. 21 and 22,
spiral sensing loop 344 is designed and constructed to expand away
from said shaft of catheter 300 when a proximal end of that sensing
loop is pushed toward an anchored distal end of that sensing loop.
In the configuration presented by FIGS. 23 and 24, a spiral sensing
loop is designed and constructed to contract toward a shaft of
catheter 300 when a proximal end of that sensing loop is pulled
away from an anchored distal end of that sensing loop.
[0247] Attention is now drawn to FIG. 25, which presents yet
another alternative construction for a section of an angioplasty
balloon catheter enabling multiple temperature measurements along a
selected section of an artery, such temperature measurements being
useable to assist in locating a site for angioplasty. In FIG. 25, a
catheter 360 comprises a thermal sensor 320A attached to a moveable
base 362, said moveable base being movably mounted on (and
preferably mounted around) a shaft 342. A flexible yet semi-rigid
push-pull connector 364 extends along a length of shaft 362, and
may pass within a plurality of optional guides 366 which serve to
maintain connector 364 adjacent to shaft 342. In use, an operator,
either manually or utilizing a servomotor, causes 364 to push or
pull base 362, causing base 362, and with it sensor 320, to slide
along shaft 342. In use, heat sensor 320A is used to register
temperature of tissues at a plurality of positions along a selected
length of catheter 360, thus achieving a plurality of temperature
measurements utilizing a single moveable heat sensor 320A (or
alternatively, a small number of sensors 320) in place of a
plurality of heat sensors 320 as was described above with reference
to FIGS. 16-24. Thus, catheter 360 may be used in much the same way
as catheter 300. In a preferred embodiment, sensor 320A is a fiber
optic element moveable along catheter 360 and connectable to a
thermographic camera 370 external to catheter 360.
[0248] Temperature-sensing apparatus described hereinabove with
reference to FIGS. 16-17 and FIGS. 19-25 is particularly useful in
positioning an angioplasty balloon catheter for an angioplasty
procedure. A recommended procedure comprises
[0249] a) introducing into an artery the angioplasty balloon
catheter, the angioplasty balloon catheter having an inflatable
balloon operable to perform angioplasty and a plurality of
temperature sensors arranged along a selected section of the
catheter,
[0250] b) manipulating the catheter into a selected segment of the
artery suspected of having an afflicted portion,
[0251] c) operating the temperature sensors to determine
temperatures at a plurality of sites along a selected segment of
the artery,
[0252] d) comparing the resultant temperature readings to determine
a locus, within the inspected section of the artery, having
temperatures high than those measured within other portions of the
artery, and
[0253] e) further manipulating the catheter so as to position the
angioplasty balloon in a vicinity of that determined locus.
[0254] The procedure here described may be used to accurately
positioning the angioplasty balloon of an angioplasty balloon
catheter for an angioplasty procedure.
[0255] Similarly, use of temperature-sensing apparatus described
hereinabove with reference to FIGS. 16-17 and FIGS. 19-24 enables a
recommended method of treating a stenotic inflammation of an
artery, the method comprising:
[0256] a) introducing into an artery an angioplasty balloon
catheter such as catheter 300 described hereinabove, having an
inflatable balloon 310 operable to perform angioplasty and a
plurality of temperature sensors 320 arranged along a selected
section of catheter 310,
[0257] b) manipulating catheter 310 into a selected segment of an
artery suspected of having an inflamed portion,
[0258] c) operating temperature sensors 320 to determine
temperatures at a plurality of sites along a selected segment of
the artery,
[0259] d) comparing temperature readings to determine a locus,
within the selection section of the artery, having a temperatures
high than those measured within other portions of the artery,
[0260] e) further manipulating catheter 300 so as to position
balloon 310 in a vicinity of the locus determined in step (d),
and
[0261] f) inflating balloon 310 so as to compress tissues around
balloon 310 at the determined locus, thereby performing
angioplasty, thereby treating said stenotic inflammation of said
body conduit.
[0262] In a particularly recommended procedure, the above method of
treating a stenotic inflammation of an artery comprises an
additional step, namely utilizing a balloon catheter 300 equipped
for cryogenic cooling of balloon 310 to cool balloon 310, and
tissues surrounding balloon 310, during or immediately after
angioplasty.
[0263] In a further recommended procedure, catheter 300 is
implemented as catheter 100 described hereinabove, and cooling of
inflated balloon 310 (also identifiable as balloon 110 described
hereinabove) is accomplished using Joule-Thomson cooling of cooling
gas introduced under pressure to a Joule-Thomson orifice (orifice
108) within balloon 310.
[0264] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention, which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable
subcombination.
[0265] Although the invention has been described in conjunction
with specific embodiments thereof, it is evident that many
alternatives, modifications and variations will be apparent to
those skilled in the art. Accordingly, it is intended to embrace
all such alternatives, modifications and variations that fall
within the spirit and broad scope of the appended claims. All
publications, patents and patent applications mentioned in this
specification are herein incorporated in their entirety by
reference into the specification, to the same extent as if each
individual publication, patent or patent application was
specifically and individually indicated to be incorporated herein
by reference. In addition, citation or identification of any
reference in this application shall not be construed as an
admission that such reference is available as prior art to the
present invention.
* * * * *