U.S. patent application number 10/896749 was filed with the patent office on 2005-03-10 for cryosurgical probe with bellows shaft.
Invention is credited to Bui, Dennis M., Damasco, Sanford D., Yu, Xiaoyu.
Application Number | 20050055017 10/896749 |
Document ID | / |
Family ID | 27609366 |
Filed Date | 2005-03-10 |
United States Patent
Application |
20050055017 |
Kind Code |
A1 |
Damasco, Sanford D. ; et
al. |
March 10, 2005 |
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) |
Correspondence
Address: |
LAWRENCE N. GINSBERG
ENDOCARE, INC.
201 TECHNOLOGY DRIVE
IRVINE
CA
92618
US
|
Family ID: |
27609366 |
Appl. No.: |
10/896749 |
Filed: |
July 21, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10896749 |
Jul 21, 2004 |
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10057033 |
Jan 23, 2002 |
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6767346 |
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10057033 |
Jan 23, 2002 |
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09957337 |
Sep 20, 2001 |
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Current U.S.
Class: |
606/21 |
Current CPC
Class: |
A61B 2017/00092
20130101; A61B 2018/0262 20130101; A61B 2018/00041 20130101; A61B
2017/00243 20130101; A61B 2018/00101 20130101; A61B 2017/00084
20130101; A61B 2018/0212 20130101; A61B 18/02 20130101 |
Class at
Publication: |
606/021 |
International
Class: |
A61B 018/18; F25B
019/02 |
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; and, a malleable shaft secured
to and in heat transfer relationship with said cryoassembly, said
shaft having a 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, wherein said bellows portion is
bendable as desired by the operator.
2. The malleable cryosurgical probe of claim 1, wherein 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.
3. 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 in a range of 0.030 inches, peak-to-peak.
4. 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.
5. The malleable cryosurgical probe of claim 1, wherein each
convolution has a wall thickness in a range of 0.0015 to 0.0122
inches.
6. 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.
7. The malleable cryosurgical probe of claim 1, wherein said
cryoassembly comprises a plurality of longitudinally spaced
Joule-Thomson nozzles.
8. 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.
9. 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.
10. The malleable cryosurgical probe of claim 7 wherein said
cryogenic fluid is introduced to said Joule-Thomson nozzles at a
rate of between about 2000 psi to about 4500 psi.
11. A malleable shaft for utilization with a cryosurgical probe,
comprising: a 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 0.140-0.160 inches, inner diameters in a range of 0.065-0.100
inches, said bellows portion having a minimum bend radius of about
0.195 inches, wherein said bellows portion is bendable as desired
by the operator.
12. The malleable shaft of claim 11, wherein 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.
13. The malleable shaft of claim 11, wherein said convolutions each
comprise alternating peak sections and valley sections, said peak
sections each having peaks, said convolutions being spaced in a
range of 0.030 inches, peak-to-peak.
14. The malleable shaft of claim 11, 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.
15. A malleable cryosurgical probe, comprising: a) a cryostat
assembly, comprising: i) an elongated shaft assembly having at
least one malleable 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.
16. The malleable cryosurgical probe of claim 15, wherein said
bellows portion is formed of a thermally conductive metal, said
bellows portion having a plurality of convolutions.
17. The malleable cryosurgical probe of claim 16, wherein 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.
18. The malleable cryosurgical probe of claim 16, wherein said
convolutions each comprise alternating peak sections and valley
sections, said peak sections each having peaks, said convolutions
being spaced in a range of 0.030 inches, peak-to-peak.
19. The malleable cryosurgical probe of claim 16, 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.
20. The malleable cryosurgical probe of claim 16, wherein said at
least one Joule-Thomson nozzles comprises a plurality of
longitudinally spaced Joule-Thomson nozzles.
21. The malleable cryosurgical probe of claim 16, 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.
22. The malleable cryosurgical probe of claim 15, wherein said
handle assembly defines a volume formed therein, said heat
exchanger being positioned within said volume.
23. The malleable cryosurgical probe of claim 15, wherein said
thermally insulating element is adjustably positionable to control
the location, size and shape of said freezing portion.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. Ser. No.
10/057,033 filed Jan. 13, 2002, which is a continuation-in-part of
U.S. Ser. No. 09/957,337 filed Sep. 20, 2001.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] 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.
[0004] 2. Description of the Related Art
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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.
[0011] 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.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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
[0022] 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.
[0023] 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).
[0024] 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.
[0025] 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
[0026] FIG. 1 is a crossectional view of a preferred embodiment of
the cryosurgical probe of the present invention.
[0027] FIG. 2 is a crossectional view of the bellows shaft of the
cryosurgical probe of the present invention.
[0028] FIG. 3 is an enlarged crossectional view of a portion of the
bellows shaft of the present invention to show the
convolutions.
[0029] FIG. 4 is an enlarged crossectional view of the tip of the
bellows shaft.
[0030] 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.
[0031] 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.
[0032] FIG. 7 is a schematic illustration of an embodiment of the
cryosurgical probe having a movable, thermally insulated main
portion.
[0033] The same parts or elements throughout the drawings are
designated by the same reference characters.
DETAILED DESCRIPTION OF THE INVENTION
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] 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.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] 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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