U.S. patent number 6,767,346 [Application Number 10/057,033] was granted by the patent office on 2004-07-27 for cryosurgical probe with bellows shaft.
This patent grant is currently assigned to Endocare, Inc.. Invention is credited to Dennis M. Bui, Sanford D. Damasco, Xiaoyu Yu.
United States Patent |
6,767,346 |
Damasco , et al. |
July 27, 2004 |
Cryosurgical probe with bellows shaft
Abstract
The malleable cryosurgical probe includes a cryostat assembly
and a cryoprobe assembly. The cryostat assembly includes an
elongated shaft assembly having a bellows portion thereof and a
closed distal end. The shaft assembly includes at least one
freezing portion comprising the bellows portion, at least one
thermally insulated portion and a thermally insulating element
positioned about the thermally insulated portion. A cryostat is
operably associated with the elongated shaft assembly. It includes
a cryostat inlet for receiving gas entering the cryostat, a
cryostat outlet and a heat exchanger positioned between the
cryostat outlet and the cryostat inlet. The heat exchanger receives
gas from the cryostat inlet and provides heat transfer between gas
flowing within the cryostat and fluid exterior thereto. At least
one Joule-Thomson nozzle is in fluid communication with the
cryostat outlet. The at least one Joule-Thomson nozzle expands gas
expelled therefrom. The expanded cold fluid communicates with the
freezing portion to provide cooling thereof. The cryoprobe assembly
includes a handle assembly for supporting the cryostat assembly and
a fluid supply line assembly connectable to a fluid source at one
end and to the cryostat inlet at a second end. The heat exchanger
is positioned at a location longitudinally spaced from the freezing
portion(s).
Inventors: |
Damasco; Sanford D. (Irvine,
CA), Bui; Dennis M. (Orange, CA), Yu; Xiaoyu (San
Diego, CA) |
Assignee: |
Endocare, Inc. (Irvine,
CA)
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Family
ID: |
27609366 |
Appl.
No.: |
10/057,033 |
Filed: |
January 23, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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957337 |
Sep 20, 2001 |
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Current U.S.
Class: |
606/21; 606/20;
606/22; 607/105; 607/113 |
Current CPC
Class: |
A61B
18/02 (20130101); A61B 2017/00084 (20130101); A61B
2017/00092 (20130101); A61B 2017/00243 (20130101); A61B
2018/00041 (20130101); A61B 2018/00101 (20130101); A61B
2018/0212 (20130101); A61B 2018/0262 (20130101) |
Current International
Class: |
A61B
18/02 (20060101); A61B 18/00 (20060101); A61B
17/00 (20060101); A61B 017/36 () |
Field of
Search: |
;606/20-26
;607/96,105,113 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Walker & Gingham, Low Capacity Cryogenic Refrigeration, pp. 67
ET SEQ (1994)..
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Primary Examiner: Rollins; Rosiland K.
Attorney, Agent or Firm: Ginsberg; Lawrence N.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. Ser. No.
09/957,337 filed Sep. 20, 2001.
Claims
What is claimed and desired to be secured by Letters Patent of the
United States is:
1. A malleable cryosurgical probe, comprising: a cryoassembly for
providing a flow of cryogenic fluid, said cryoassembly comprising a
plurality of longitudinally spaced Joule-Thomson nozzles; and, a
malleable shaft secured to and in heat transfer relationship with
said cryoassembly, said shaft having a hydroformed bellows portion
located thereon formed of a thermally conductive metal, said
bellows portion having a plurality of convolutions, said
convolutions having outer diameters in a range of 0.140-0.180
inches and inner diameters in a range of 0.065-0.100 inches, said
bellows portion having a minimum bend radius of about 0.195 inches,
said convolutions each comprise peak sections and valley sections,
said peak sections each having peaks, said convolutions being
spaced in a range of 0.020-0.100 inches, peak-to-peak, wherein each
convolution has a wall thickness in a range of 0.0015 to 0.0122
inches and wherein said bellows portion is bendable and will hold
form as desired by the operator.
2. The malleable cryosurgical probe of claim 1, wherein said
convolutions each comprise alternating peak sections and valley
sections, said peak sections each having peaks, said convolutions
being spaced by a distance of approximately 0.030 inches,
peak-to-peak.
3. The malleable cryosurgical probe of claim 1, wherein said
convolutions each comprise alternating peak sections and valley
sections, each valley section defining a valley radius and each
peak section defining a peak radius, the summation of said valley
radius and said peak radius being one-half the peak-to-peak
distance between convolutions.
4. The malleable cryosurgical probe of claim 1, wherein said shaft
comprises a tip portion at a distal end thereof wherein the
distance between a tip of said tip portion and said bellows portion
is no more than 11/2 times the outer diameters of said
convolutions.
5. The malleable cryosurgical probe of claim 1, wherein said
cryoassembly comprises a sliding assembly including a sliding
element attached to a thermal insulating element for selectively
effecting the location of the freezing zone.
6. The malleable cryosurgical probe of claim 1 wherein said bellows
portion has a length in a range of 1.4 inches to about 4.0
inches.
7. The malleable cryosurgical probe of claim 1 wherein said
cryogenic fluid is introduced to said Joule-Thomson nozzles at a
rate of between about 2000 psi to about 4500 psi.
8. A malleable cryosurgical probe, comprising: a) a cryostat
assembly, comprising: i) an elongated shaft assembly having at
least one malleable hydroformed bellows portion thereof and a
closed distal end, said shaft assembly, including: at least one
freezing portion comprising said at least one bellows portion; at
least one thermally insulated portion: and, a thermally insulating
element positioned about said thermally insulated portion; ii) a
cryostat operably associated with said elongated shaft assembly,
comprising: a cryostat inlet for receiving gas entering said
cryostat; a cryostat outlet; and, a heat exchanger positioned
between said cryostat outlet and said cryostat inlet, said heat
exchanger for receiving gas from said cryostat inlet and providing
heat transfer between gas flowing within said cryostat and fluid
exterior thereto; and, iii) a plurality of longitudinally spaced
Joule-Thomson nozzles in fluid communication with said cryostat
outlet, said plurality of Joule-Thomson nozzles for expanding gas
expelled therefrom, the expanded cold fluid communicating with said
at least one freezing portion to provide cooling thereof; and, b) a
cryoprobe assembly, comprising: a handle assembly for supporting
said cryostat assembly; and, a fluid supply line assembly
connectable to a fluid source at one end and to said cryostat inlet
at a second end, wherein said heat exchanger is positioned at a
location longitudinally spaced from said at least one freezing
portion wherein said bellows portion is formed of a thermally
conductive metal, said bellows portion having a plurality of
convolutions, said convolutions having outer diameters in a range
of 0.140-0.180 inches and inner diameters in a range of 0.065-0.100
inches, said bellows portion having a minimum bend radius of about
0.195 inches, said convolutions each comprise peak sections and
valley sections, said peak sections each having peaks, said
convolutions being spaced in a range of 0.020-0.100 inches,
peak-to-peak, wherein each convolution has a wall thickness in a
range of 0.0015 to 0.0122 inches and wherein said bellows portion
is bendable and will hold form as desired by the operator.
9. The malleable cryosurgical probe of claim 8, wherein said
convolutions each comprise alternating peak sections and valley
sections, said peak sections each having peaks, said convolutions
being spaced by a distance of approximately 0.030 inches,
peak-to-peak.
10. The malleable cryosurgical probe of claim 8, wherein said
convolutions each comprise alternating peak sections and valley
sections, each valley section defining a valley radius and each
peak section defining a peak radius, the summation of said valley
radius and said peak radius being one-half the peak-to-peak
distance between convolutions.
11. The malleable cryosurgical probe of claim 8, wherein said
cryostat assembly comprises a sliding assembly including a sliding
element attached to said thermally insulating element for
selectively effecting the location of the freezing zone.
12. The malleable cryosurgical probe of claim 8, wherein said
handle assembly defines a volume formed therein, said heat
exchanger being positioned within said volume.
13. The malleable cryosurgical probe of claim 8, wherein said
thermally insulating element is adjustably positionable to control
the location, size and shape of said freezing portion.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to cryosurgical probes and more particularly
to a cryosurgical probe that includes an improved malleable shaft
for use with applications in which a desired angle of entry and
contact with the patient's organ is required.
2. Description of the Related Art
Cryosurgical probes are used to treat a variety of diseases. The
cryosurgical probes quickly freeze diseased body tissue, causing
the tissue to die after which it will be absorbed by the body,
expelled by the body, sloughed off or replaced by scar tissue.
Cryothermal treatment is currently used to treat prostate cancer
and benign prostate disease, breast tumors including breast cancer,
liver tumors including cancer, glaucoma and other eye diseases.
Cryosurgery may also be used for the treatment of a number of other
diseases and conditions including the treatment of cardiac
arrhythmias, such as atrial fibrillation.
A variety of cryosurgical instruments variously referred to as
cryoprobes, cryosurgical probes, cryosurgical ablation devices, and
cryostats and cryocoolers, have been available for cryosurgery.
These devices typically use the principle of Joule-Thomson
expansion to generate cooling. They take advantage of the fact that
most fluids, when rapidly expanded, become extremely cold. In these
devices, a high pressure gas such as argon or nitrogen is expanded
through a nozzle inside a small cylindrical shaft or sheath
typically made of steel, and the Joule-Thomson expansion cools the
steel sheath to a cold temperature very rapidly.
An exemplary device is illustrated in Sollami, Cryogenic Surgical
Instrument, U.S. Pat. No. 3,800,552 (Apr. 2, 1974). Sollami shows a
basic Joule-Thomson probe with a sheath made of metal, a fin-tube
helical gas supply line leading into a Joule Thomson nozzle which
directs expanding gas into the probe. Expanded gas is exhausted
over the fin-tube helical gas supply line, and pre-cools incoming
high pressure gas. For this reason, the coiled supply line is
referred to as a heat exchanger, and is beneficial because, by
pre-cooling incoming gas, it allows the probe to obtain lower
temperatures.
Ben-Zion, Fast Changing Heating and Cooling Device and Method, U.S.
Pat. No. 5,522,870 (Jun. 4, 1996) applies the general concepts of
Joule-Thomson devices to a device that is used first to freeze
tissue and then to thaw the tissue with a heating cycle. Nitrogen
is supplied to a Joule-Thomson nozzle for the cooling cycle, and
helium is supplied to the same Joule-Thomson nozzle for the warming
cycle. Preheating of the helium is presented as an essential part
of the invention, necessary to provide warming to a sufficiently
high temperature.
A Joule-Thomson cryostat for use as a gas tester is illustrated in
Glinka, System for a Cooler and Gas Purity Tester, U.S. Pat. No.
5,388,415 (Feb. 14, 1995). Glinka also discloses use of the by-pass
from the Joule-Thomson Nozzle to allow for cleaning the supply
line, and also mentions that the high flow of gas in the by-pass
mode will warm the probe. This is referred to as mass flow warming,
because the warming effect is accomplished purely by conduction and
convection of heat to the fluid mass flowing through the probe.
Various cryocoolers use mass flow warming, flushed backwards
through the probe, to warm the probe after a cooling cycle. Lamb,
Refrigerated Surgical Probe, U.S. Pat. No. 3,913,581 (Aug. 27,
1968) is one such probe, and includes a supply line for high
pressure gas to a Joule-Thomson expansion nozzle and a second
supply line for the same gas to be supplied without passing through
a Joule-Thomson nozzle, thus warming the catheter with mass flow.
Longsworth, Cryoprobe, U.S. Pat. No. 5,452,582 (Sep. 26, 1995)
discloses a cryoprobe which uses the typical fin-tube helical coil
heat exchanger in the high pressure gas supply line to the
Joule-Thomson nozzle. The Longsworth cryoprobe has a second inlet
in the probe for a warming fluid, and accomplishes warming with
mass flow of gas supplied at about 100 psi. The heat exchanger,
capillary tube and second inlet tube appear to be identical to the
cryostats previously sold by Carleton Technologies, Inc. of Orchard
Park, N.Y.
Each of the above mentioned cryosurgical probes builds upon prior
art which clearly establishes the use of Joule-Thomson cryocoolers,
heat exchangers, thermocouples, and other elements of cryocoolers.
Walker, Miniature Refrigerators for Cryogenic Sensor and Cold
Electronics (1989) (Chapter 2) and Walker & Gingham, Low
Capacity Cryogenic Refrigeration, pp. 67 et seq. (1994) show the
basic construction of Joule-Thomson cryocoolers including all of
these elements. The Giaque-Hampson heat exchanger, characterized by
coiled finned-tube, transverse flow recuperative heat exchanger is
typical of cryocoolers. The open mandrel around which the finned
tube coil is placed is also typical of cryocoolers.
U.S. Pat. Nos. 5,800,487 and 6,074,412, both entitled Cryoprobe,
issued to Mikus et and assigned to the present assignee disclose
cryoprobes using Joule-Thomson nozzles and finned tube helical coil
heat exchangers.
Cryosurgical probes may be used, as mentioned above, to treat
diseases of the prostate, liver, and breast, and they have
gynecological applications as well. The cryosurgical probes form
iceballs which freeze disease tissue. Each application has a
preferred shape of iceball, which, if capable of production, would
allow cryoablation of the diseases tissue without undue destruction
of surrounding healthy tissue. For example, prostate cryoablation
optimally destroys the lobes of the prostate, while leaving the
surrounding neurovascular bundles, bladder neck sphincter and
external sphincter undamaged. The prostate is wider at the base and
narrow at the apex. A pear or fig shaped ice ball is best for this
application. Breast tumors tend to be small and spherical, and
spherical iceballs will be optimal to destroy the tumors without
destroying surrounding breast tissue. Liver tumors may be larger
and of a variety of shapes, including spherical, olive shaped, hot
dog shaped or irregularly shaped, and may require more elongated
iceballs, larger iceballs, and iceballs of various shapes.
During open chest surgery transmural cryo-lesions can be created on
or in the heart to treat cardiac arrhythmia (including atrial
fibrillation). A suitable cryoprobe would be useful for this
application. Due to the nature of the procedure and anatomical
locations that lesions must be placed, the cryoprobe must be
sufficiently malleable by the surgeon to be placed on the heart
surface but stiff enough such that pressure can be applied without
flexing the shaft.
The prior art includes references to malleable and flexible
cryoprobes. For example, U.S. Pat. No. 6,161,543, issued to Cox et
al discloses the use of a malleable probe. The probe has a
malleable shaft. A malleable metal rod is coextruded with a polymer
to form the shaft. The rod permits the user to shape the shaft as
necessary so that a tip can reach the tissue to be ablated.
U.S. Pat. No. 5,108,390, issued to Potocky et al discloses a highly
flexible cryoprobe that can be passed through a blood vessel and
into the heart without external guidance other than the blood
vessel itself.
Several patents disclose the use of bellows-type assemblies for use
with cryosurgical systems. For example, U.S. Pat. No. 6,241,722,
issued to Dobak et al, discloses a cryogenic catheter with a
bellows and which utilizes a longitudinally movable Joule-Thomson
nozzle of expansion. The Dobak '722 device preferably uses closed
media-flow pathways for efficient recycling of the media
employed.
Dobak, in his U.S. Pat. No. 5,957,963, disclose the used of a
flexible catheter inserted through the vascular system of a patient
to place the distal tip of the catheter in an artery feeding a
selected organ of the patient. The '963 patent discloses a heat
transfer bellows for cooling the blood flowing through the
artery.
U.S. Pat. No. 6,235,019, issued to J. W. Lehmann et al, discloses a
cryosurgical catheter having a bellows. The cryogenic catheter has
an elongate outer member and a plurality of inner members disposed
with the elongate outer member. The inner members define at least
one cryogenic path through the outer member. At least one of the
inner members has at least one controllable opening formed thereon
to selectively release cryogenic fluid. The inner members also
include an overtube and an injection tube slideably disposed to one
another.
U.S. Pat. No. 6,106,518, issued to Wittenberger et al, discloses a
medical device that includes a flexible member having a variable
geometry tip with a thermally-transmissive region. A smooth fluid
path is provided through the flexible member to and from a variable
geometry, thermally-transmissive region. The thermally-transmissive
region may be a bellows-like structure.
U.S. Pat. No. 6,224,624, issued to Lasheras et al, discloses a
bellows structure used for a selective organ heat transfer device
having a flexible coaxial catheter capable of insertion into a
selected feeding artery in the vascular system of a patient.
SUMMARY
In a broad aspect, the present invention is a malleable
cryosurgical probe comprising a cryoassembly for providing a flow
of cryogenic fluid and a malleable shaft secured to and in heat
transfer relationship with the cryoassembly. The shaft has a
bellows portion located thereon formed of a thermally conductive
metal. The bellows portion has a plurality of convolutions, the
convolutions having outer diameters in a range of 0.140-0.180
inches, and inner diameters in a range of 0.065-0.100 inches. The
bellows portion has a minimum bend radius of about 0.195 inches,
thus being bendable as desired by the operator.
In another broad aspect, the cryosurgical probe includes a cryostat
assembly and a cryoprobe assembly. The cryostat assembly includes
an elongated shaft assembly having a bellows portion thereof and a
closed distal end. The shaft assembly includes at least one
freezing portion comprising said bellows portion, at least one
thermally insulated portion and a thermally insulating element
positioned about the thermally insulated portion. A cryostat is
operably associated with the elongated shaft assembly. It includes
a cryostat inlet for receiving gas entering the cryostat, a
cryostat outlet and a heat exchanger positioned between the
cryostat outlet and the cryostat inlet. The heat exchanger receives
gas from the cryostat inlet and provides heat transfer between gas
flowing within the cryostat and fluid exterior thereto. At least
one Joule-Thomson nozzle is in fluid communication with the
cryostat outlet. The at least one Joule-Thomson nozzle expands gas
expelled therefrom. The expanded cold fluid communicates with the
freezing portion to provide cooling thereof. The cryoprobe assembly
includes a handle assembly for supporting the cryostat assembly and
a fluid supply line assembly connectable to a fluid source at one
end and to the cryostat inlet at a second end. The heat exchanger
is positioned at a location longitudinally spaced from the freezing
portion(s).
Positioning of the heat exchanger in a position longitudinally
spaced from the freezing portion(s) provides the capability of
providing malleable segments. The heat exchanger can be made
relatively large and powerful providing enhanced operation while
concomitantly providing for a freezing portion and/or thermally
insulated portion of the elongated shaft assembly that has a small
diameter. The bellows portion formed of material that permits
reshaping and bending of the elongated shaft assembly as a unit to
reposition the ablating surface for greater ablation precision.
Moreover, enhancements are disclosed for assuring that there can be
bending and reshaping without kinking or collapsing. Such
properties are especially imperative for such devices employed in
the formation of transmural lesions in anatomical locations that
are particularly difficult to access. The malleable segment is
sufficiently malleable to be fashioned to the desired shape while
rigid enough to retain the shape during clinical use.
Other objects, advantages, and novel features will become apparent
from the following detailed description of the invention when
considered in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a crossectional view of a preferred embodiment of the
cryosurgical probe of the present invention.
FIG. 2 is a crossectional view of the bellows shaft of the
cryosurgical probe of the present invention.
FIG. 3 is an enlarged crossectional view of a portion of the
bellows shaft of the present invention to show the
convolutions.
FIG. 4 is an enlarged crossectional view of the tip of the bellows
shaft.
FIG. 5 is an enlarged view of the cryostat assembly of the
cryosurgical probe of FIG. 1 with the handle removed for the
purposes of clarity.
FIG. 6 is a schematic view of the heart with the cryosurgical probe
of the present invention shown positioned thereagainst for the
treatment of arrhythmias.
FIG. 7 is a schematic illustration of an embodiment of the
cryosurgical probe having a movable, thermally insulated main
portion.
The same parts or elements throughout the drawings are designated
by the same reference characters.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings and the characters of reference marked
thereon FIG. 1 illustrates a preferred embodiment of the present
invention, designated generally as 10. The malleable cryosurgical
probe 10 includes a cryoassembly, designated generally as 11, for
providing a flow of cryogenic fluid and a malleable shaft assembly,
designated generally as 12. The malleable shaft assembly 12 is in
heat transfer relationship with the cryoassembly 11. The shaft
includes a bellows portion 13 formed of thermally conductive metal.
The cryoassembly 11 will be discussed in detail below.
Referring now to FIGS. 2 and 3 the shaft assembly 12 is
illustrated. As best seen in FIG. 3 the bellows portion 13 of the
shaft assembly 12 includes a plurality of convolutions 15. These
convolutions 15 have outer diameters (OD's) preferably in a range
of 0.140-0.180 inches and inner diameters (ID's) preferably in a
range of 0.065-0.100 inches. The bellows portion 13 has a minimum
bend radius of about 0.195 so that the bellows portion is bendable
as desired by the operator. It is preferably formed by hydroforming
techniques.
Each convolution 15 comprises a peak section 17 and a valley
section 19. The peck sections each have peaks such that the
convolutions, containing these alternating peak sections 17 and
valley sections 19, are preferably spaced in a range of 0.020-0.100
inches, peak-to-peak (P--P). Preferably, the convolutions 15 are
spaced in a range of 0.030 inches, peak-to-peak. The wall thickness
is preferably in a range of 0.0015 to 0.0122 inches.
As can be seen most clearly in FIG. 4 a tip portion 21 is located
at the distal end of the shaft assembly wherein the distance
between the tip of the tip portion and the bellows portion is
preferably no more than 11/2 of the OD's of the convolutions
15.
Referring again to FIG. 1 and also now to FIG. 5 it can be seen
that the cryosurgical probe 10 may be deemed to include a cryostat
assembly and a cryoprobe assembly. The cryostat assembly includes
the elongated shaft assembly 12, a cryostat designated generally as
14, and Joule-Thomson nozzles 16. The cryoprobe assembly includes a
handle assembly, designated generally as 18 and a fluid supply line
assembly 20.
The elongated shaft assembly 12 includes a main body portion 22 and
a distal portion 24 welded thereto with a spacer 26. The main body
portion 22 includes a thermally protected segment 28 and an adapter
segment 30, these two segments being welded together with a spacer
32. The thermally protected segment 28 is positioned between the
adapter segment 30 and the distal portion 24. The distal portion 24
comprises the malleable bellows portion 13. Both the main body
portion 22 and the distal portion 24 are generally tubular
elements. They may be formed of, for example, annealed metals such
as annealed stainless steel, annealed nickel or annealed copper.
The elongated shaft assembly may have a wide range of lengths
depending on the desired purpose, i.e. it might be one to perhaps
twenty inches long.
A shaft enhancement element such as a spring coil member 36 may be
positioned about the tube of the thermally protected segment 28.
The spring coil member 36 enhances the capability of the thermally
protected segment 28 of bending and reshaping without kinking or
collapsing.
The elongated shaft assembly includes a thermally insulating
element 38 positioned over the main body portion 22 to define a
thermally insulated portion. The portion of the distal portion 24
that remains uncovered and includes the bellows portion 13 defines
a freezing portion. The freezing portion is preferably made of a
thermally conductive material, such as stainless steel, as noted
above. The elongated shaft assembly 12 has been shown with three
different parts, i.e. segment 28, adapter segment 30 and distal
portion 24. This is to accommodate various desired sizes of distal
portions 24. However, use of these three parts has been shown by
way of illustration and not limitation. For example, a one-piece
shaft can be utilized. The thermally insulated portion typically
has an outer diameter in a range of between about 0.04 inches and
about 0.50 inches, preferably in a range of about 0.10 inches and
about 0.15 inches.
The cryostat 14 comprises a coiled heat exchanger 40. A cryostat
inlet 42 receives gas entering the cryostat while a cryostat outlet
44 provides the gas to the Joule-Thomson nozzles 16. The coiled
heat exchanger 40 is coiled around a mandrel 46. In between each
winding of the heat exchanger, gaps are formed between the coil and
the main body portion 22, and gaps are formed between the coil and
the mandrel 46. This construction is known as a Giaque-Hampson heat
exchanger. The heat exchanger, which is an integral part of the
high pressure gas pathway, is made with finned tubing, with
numerous fins throughout its length.
The handle assembly 18 includes an anchor 48 securely connected to
the cryostat assembly by welding or other conventional means. An
o-ring 50 prevents fluid from escaping through the handle assembly
18. A handle, designated generally as 52, includes two elongated
opposing handle body elements 54 with radially inward extensions 56
for engaging the space between radially outward extensions 58 of
the anchor 48. A handle nozzle 60 fits over and secures the handle
body elements 54 together at first ends thereof via a friction fit.
A handle barb 62 secures the handle body elements 54 together at
second ends thereof.
The fluid supply line assembly 20 includes a housing 64 that
supports a fluid supply line 66. A temperature measurement device,
i.e. a thermocouple 68, is positioned within the elongated shaft
assembly, extends through the fluid supply line assembly 20 and is
connectable to a data acquisition system. The thermocouple 68 is
used to measure and monitor the temperature inside the cryosurgical
probe.
Fluid flow through the cryosurgical probe is as follows. High
pressure fluid, preferably gaseous argon, and generally at a
pressure in a range of about 2000 psi to about 4500 psi, typically
about 3000 psi, is supplied to the assembly through high pressure
fitting 70, flows through gas supply line 66, through cryostat
inlet 42, into heat exchanger 40, through cryostat outlet 44 and
Joule-Thomson nozzles 16. (In a preferred embodiment, for the
treatment of arrythmia, five Joule-Thomson nozzles are utilized.)
The high pressure gas expands within the expansion chamber and
cools to cryogenic temperatures. The temperature at the
Joule-Thomson nozzles 16 is generally at a first temperature of
about 20.degree. C. and expands to a temperature of about
-150.degree. C. Condensation of the gas is preferably avoided but
can be tolerated. After expanding, the gas is at lower pressure and
exhausts over the exhaust gas pathway that includes flow over
outside of the coils of the heat exchanger 40. Because it is now
cold, it cools the gas flowing inside the coils. This makes cooling
more efficient and achieves colder temperatures. After passing
through the heat exchanger, the exhaust gas flows through the
remainder of the exhaust gas pathway, as indicated by numeral
designation 70. The exhaust gas is eventually vented to the
atmosphere.
Prior art warming methods such as exhaust blocking, reverse flow
heat transfer, and electrical heating can be employed. The
preferred method of warming is to supply high pressure helium gas
through the supply line, heat exchanger and Joule-Thomson nozzle.
Helium gas heats up when expanded through the gas outlet. Thus, the
supply of gas to the probe can be switched from high pressure
nitrogen or argon to high pressure helium to effect rapid
re-warming of the cryosurgical probe.
Referring now to FIG. 6, the utilization of the present
cryosurgical probe 10, positioned against the heart 72, for
treating arrhythmias, is illustrated. This creates transmural
lesions that have the effect of channeling, limiting or blocking
electrical transmissions. Its malleable characteristics allow the
cryosurgical probe 10 to create elongated homogenous lesions
(either curved or straight) at desired locations that are often
difficult to access with a straight surgical implement.
For such treatment of arrhythmia the bellows portion 13 should may
be in a range of about 1.5-4.0 inches long, preferably in a range
of about 2.6-3.2 inches long. The preferred length is about 2.7
inches.
Use of the longitudinally spaced Joule-Thomson nozzles 16 provides
the ability to create elongated iceballs as desired along the
length of the bellows portion 13. Although the embodiment
illustrated shows four Joule-Thomson nozzles 16, more or less can
be provided depending on the particular requirements. Use of this
plurality of Joule-Thomson nozzles 16 is made possible, in part,
because of the spacing of the heat exchanger from them.
Referring now to FIG. 7 another embodiment of the cryosurgical
probe is illustrated, designated generally as 74. In this
embodiment a sliding assembly including a sliding element 76
attached to a thermal insulating element 78 is utilized to cover
the bellows portion as desired to control ice formation. The
sliding element includes a button 80 to provide ease in such
adjustments.
Obviously, many modifications and variations of the present
invention are possible in light of the above teachings. It is,
therefore, to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described.
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