Malleable cryosurgical probe

Malleable Cryosurgical Probe

Background of the invention

1. Field of the Invention

The present invention relates to cryosurgical probes and in particular to a cryosurgical probe that is malleable for use with applications where a desired entry angle and contact with an organ of the patient is required.

two. Description of Related Technique

Cryosurgical probes are used to treat various diseases. 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, peeling or replaced by scar tissue. Cryothermal treatment is currently used to treat prostate cancer and benign prostate diseases, breast tumors including breast cancer, liver tumors including cancer, glaucoma and other eye diseases. Cryosurgery can also be used to treat numerous other diseases and conditions that include the treatment of cardiac arrhythmias, such as atrial fibrillation.

Various cryosurgical instruments, variously referred to as cryoprobes, cryosurgical probes, cryosurgical excision devices, and cryostats and biorefrigerators, have been available in cryosurgery. These devices typically use the Joule-Thompson expansion principle to generate cold. They take advantage of the fact that most of the 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 cylindrical rod or sleeve typically made of steel, and the Joule-Thompson expansion cools the steel sheath to a Low temperature very quickly.

An exemplary device is shown in US Patent No. 3,800,552 (April 2, 1974), Cryogenic Surgical Instrument of Sollami. Sollami shows a basic Joule-Thompson probe with a sheath made of metal, a gas supply line with a helical fin tube that leads to a Joule-Thompson nozzle that directs the expanding gas towards the probe. The expanded gas is expelled through the gas supply line with helical finned tube, and will pre-refrigerate the incoming high pressure gas. For this reason, the helical line is called a heat exchanger, and it is beneficial because, by pre-cooling the incoming gas, it allows the probe to obtain low temperatures.

US Patent No. 5,522,870 (June 4, 1974), Fast Changing Heating and Cooling Device and Method, by Ben-Zion, applies the general concepts of Joule-Thompson devices to a device that is first used to freeze a tissue and then to defrost the tissue with a heating cycle. Nitrogen is supplied to a Joule-Thompson nozzle for the refrigeration cycle, and helium is supplied to the same Joule-Thompson nozzle for the heating cycle. Helium preheating is presented as an essential part of the invention, necessary to provide heating at a sufficiently high temperature.

A Joule-Thompson cryostat for use as a gas tester is illustrated in US Patent No. 5,388,415 (February 14, 1995), System for a Cooler and Gas Purity Tester, of Glinka. Glinka also reports the use of the bypass on the Joule-Thompson nozzle to allow cleaning of the supply line, and also mentions that the high gas flow in the bypass mode will heat the probe. This is called mass flow heating, because the heating effect is achieved purely by conduction and convection of heat to the mass of the fluid flowing through the probe.

Various cryo refrigerators use mass flow heating, backed through the probe, to heat the probe after a refrigeration cycle. U.S. Patent No. 3,913,581, Refrigerated Surgical Probe, (August 27, 1968), to Lamb, presents one such probe, and includes a high pressure gas supply line for a Joule-Thomson expansion nozzle and a second supply line of the same gas that is supplied without passing through the Joule-Thomson nozzle, thus heating the catheter with mass flow. US Patent No. 5,452,582, Cryoprobe, (September 26, 1995), of Longsworth, discloses a cryoprobe using the typical helical finned tube heat exchanger in the high pressure gas supply line for the nozzle of Joule-Thompson. The Longsworth cryoprobe has a second entry into the probe for a hot fluid, and achieves heating with the mass flow of a gas supplied at 689,476 kPa. The heat exchanger, the capillary tube and the second inlet tube appear to be identical to those of cryostats previously sold by Carleton Technologies, Inc., of Orchard Park, NY.

Each of the aforementioned cryosurgical probes are constructed on the prior art that clearly establishes the use of Joule-Thompson cryo refrigerators, heat exchangers, thermocouples, and other cryo refrigerators elements. The Miniature Refrigerators for Cryogenic Sensor and Cold Electronics (1989) (Chapter 2), Walker, and Low Capacity Cryogenic Refrigeration, pags. 67 and following (1994), by Walker & Gingham, show the basic construction of Joule-Thompson cryo refrigerators including all these elements. The Giaque-Hampson heat exchanger, characterized by being a transverse flow recuperative heat exchanger, with a helical finned tube, is typical of the chiller. The open mandrel around which the helical finned tube is located is also typical of the chiller.

US Patents No. 5,800,487 and 6,074,412, being the holder of both Criosonda, granted to Mikus and others and assigned to the present assignee, disclose cryoprobes using Joule-Thompson nozzles and tube heat exchangers with helical fins.

Cryosurgical probes can be used, as mentioned above, to treat diseases of the prostate, liver, and breast, and also have gynecological applications. Cryosurgical probes form ice balls that freeze diseased tissue. Each application has a preferred form of ice ball, which, if it could be produced, would allow the cryoextirpation of diseased tissues without undue destruction of the surrounding healthy tissue. For example, prostate cryoprestruction optimally destroys the lobes of the prostate while not damaging the adjacent neurovascular bundles, the sphincter of the bladder neck and the external sphincter. The prostate is wider at the base and narrow at the vertex. For this application a pear or fig shaped ice ball is better. Breast tumors tend to be smaller and spherical, and spherical ice balls will be optimal for destroying tumors without damaging adjacent breast tissue. Liver tumors can be larger and with various shapes, including a spherical shape, an olive shape, a sausage shape.

or an irregular shape, and may require more elongated ice balls, larger ice balls, and ice balls of various shapes.

During open chest surgery, transmural cryolinesions may be created in or within the heart to treat cardiac arrhythmia (including ventricular fibrillation). A suitable cryoprobe would be useful for this application. Due to the nature of the procedure and the anatomical locations in which the lesions should be performed, the cryoprobe must be sufficiently malleable for the surgeon to place on the surface of the heart but rigid enough so that pressure can be applied without flexing the stem.

The prior art includes references to malleable and flexible cryoprobes. For example, U.S. Patent No. 6,161,543, issued to Cox et al., Discloses the use of a malleable probe. The probe has a malleable stem. To form the rod a malleable metal rod is coextruded with a polymer. The rod allows the user to shape the rod as necessary so that a tip can reach the tissue to be removed.

US Patent 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 other external guidance than the blood vessel itself. WO 98/17187 discloses the preamble of independent claim 1.

Summary

The present invention is a malleable cryosurgical probe. It includes a cryostat set and a cryoprobe set. The cryoprobe assembly includes an elongated rod assembly with at least one malleable segment thereof and a closed distal end. The stem assembly includes at least one freezing portion, at least one thermally insulated portion and a thermal insulation element positioned on the thermally insulated portion. A cryostat is operatively associated with the elongated rod assembly. It includes a cryostat inlet to receive a gas entering the cryostat, a cryostat outlet and a heat exchanger located between the cryostat outlet and the cryostat inlet. The heat exchanger receives gas from the cryostat inlet and provides a heat transfer between the gas flowing inside the cryostat and the fluid external to it. At least one Joule-Thompson nozzle is in fluid communication with the cryostat outlet. The at least one Joule-Thompson nozzle expands a gas expelled by it. The expanded cold fluid communicates with the freezing portion to provide cooling thereof. The cryoprobe assembly includes a handle assembly to support the cryostat assembly and a fluid supply line that can be connected to a fluid source at one end and the cryostat inlet at a second end. The heat exchanger is located in a longitudinally separated location of the freezing portion (s).

The placement of the heat exchanger in a longitudinally separated position of the freezing portion / s offers the ability to provide malleable segments. The heat exchanger can be relatively large and powerful, providing improved operation while correspondingly providing a freezing portion and / or a thermally insulated portion in an elongated rod assembly having a small diameter. The malleable segments are formed with a material that allows the elongated rod assembly to be reconstituted and folded as a unit for repositioning the removal surface for greater removal accuracy. Additionally, improvements are disclosed to ensure that folding and reconformation can occur without the risk of twisting or collapse. Such properties are especially imperative in those devices used for the formation of transmural lesions in anatomical locations that are particularly difficult to access. The malleable segment is malleable enough to be adapted to the desired shape, while being rigid enough to retain the shape during clinical use.

Brief Description of the Drawings

Figure 1 is a cross-sectional view of a preferred embodiment of the malleable cryosurgical probe of the present invention.

Figure 2 is an enlarged view of the cryostat assembly of the malleable cryosurgical probe of Figure 1, without the handle for reasons of clarity.

Figure 3 is a schematic view of the heart where the malleable cryosurgical probe of the present invention is shown positioned against it for the treatment of arrhythmias.

Figure 4 is a schematic illustration of an embodiment of the cryosurgical probe with a rigid, thermally insulated main portion, and a malleable tip portion.

Figure 5 is a schematic illustration of an embodiment of the cryosurgical probe with a malleable, thermally insulated main portion, and a rigid tip portion.

Figure 6 is a schematic illustration of an embodiment of the cryosurgical probe with a malleable, thermally insulated main portion, and a malleable tip portion.

Figure 7 is a schematic illustration of an embodiment of the cryosurgical probe with a malleable, thermally insulated main portion, with a freezing portion exposed therein.

Figure 8 illustrates the use of multiple freezing portions.

Figure 9 illustrates the use of adjustable freezing portions.

Figure 10 illustrates the use of longitudinally adjustable freezing portions.

Figure 11 is a schematic illustration of the use of multiple layers of thermal insulation to control the freezing zone.

Figure 12 is a schematic illustration of an embodiment in which a portion of the cryogenic probe is rotatable.

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.

Detailed description of the invention

With reference to the drawings and the reference characters marked therein, Figs 1 and 2 illustrate a preferred embodiment of the present invention, generally designated with the number 10. The malleable cryosurgical probe 10 includes a cryostat set and a set of cryoprobe The cryostat assembly includes an elongated rod assembly generally designated number 12, a cryostat generally designated number 14, and Joule-Thompson nozzles 16. The cryoprobe assembly includes a handle assembly, generally designated with the number 18 and a fluid supply line assembly 20.

The elongated rod assembly 12 includes a main body portion 22 and a tip portion 24 welded thereto with a spacer 26. The main body portion 22 includes a thermally protected malleable segment 28 and an adapter segment 30, being mutually welded these two segments with a separator

32 The thermally protected malleable segment 28 is located between the adapter segment 30 and the other malleable segment, ie the tip portion 24. The tip portion 24 has a closed distal end 34 and is also malleable. Both the main body portion 22 and the tip portion 24 are tubular elements. They may be formed, for example, by annealed metals such as annealed stainless steel, annealed nickel or annealed copper. The elongated rod assembly may have a wide range of lengths depending on the desired purpose, that is, some could be perhaps 50.8 cm long. The outer diameter can be in the range of 0.10 cm to approximately 1.27 cm.

A rod enhancement element, such as a helical spring element 36, is located around the thermally protected malleable segment tube 28. The helical spring element 36 improves the ability of the thermally protected malleable segment 28 to bend and reshape without twisting or collapsing.

The elongated rod assembly includes a thermal insulation element 38, located on the portion 22 of the main body, to define a thermally insulated portion. The portion of the tip portion 24 that remains uncovered defines a freezing portion. The freezing portion is preferably made of a thermally conductive material, such as stainless steel, as mentioned above. The elongated rod assembly 12 is shown with three different parts, that is, a malleable segment 28, an adapter segment 30 and a tip portion 24. This serves to accommodate various desired sizes of tip portions 24. However, the use of these three parts is shown by way of illustration only and not by way of limitation. For example, a single piece rod can be used. The malleable segment preferably has a minimum radius of curvature of approximately 0.635 cm. The freezing portion typically has an outside diameter in the range of approximately 0.10 cm to 1.27 cm. The thermally insulated portion typically has an outside diameter in the range of approximately 0.10 cm to 1.27 cm, preferably in the range of approximately 0.254 cm to 0.381 cm.

The cryostat 14 comprises a helical heat exchanger 40. An inlet 42 of the cryostat receives gas entering the cryostat while an outlet 44 of the cryostat provides the gas to the nozzles 16 of Joule-Thompson. The helical heat exchanger 40 is wound around a mandrel 46. Between each winding of the heat exchanger there are holes formed between the helicoid and the main body portion 22, and holes are formed between the helicoid 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 route, is manufactured with a finned tube, with numerous fins all along.

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, generally designated number 52, includes two opposing handle body elements 54, with extensions 56 radially inwardly to fit in the spaces between extensions 58 radially outwardly of the anchor 48. A handle nozzle 60 fits over the handle body elements 54, at a first end thereof, and secures them together by friction adjustment. A piece 62 of the handle secures the handle body elements 54 from each other by a second end thereof.

The fluid supply line assembly 20 includes a housing 64 that supports a fluid supply line 66. A temperature measuring device, that is to say a thermocouple 68, is located within the elongated rod assembly, extends through the fluid supply line assembly 20 and can be connected to a data acquisition system. Thermocouple 68 is used to measure and monitor the temperature inside the cryosurgical probe.

The flow of the fluid through the cryosurgical probe is as follows. A high-pressure fluid, preferably gaseous argon, and preferably at a pressure of approximately 20684.277 kPa, is supplied to the assembly, through a high-pressure fitting 70, flows through a gas supply line 66, through from the entrance 42 of the cryostat, into the heat exchanger 40, through the outlet 44 of the cryostat and the nozzles 16 of Joule-Thompson. The high pressure gas expands inside the expansion chamber and cools at cryogenic temperatures. Preferably condensation of the gas is avoided, although it is tolerable. After the expansion, the gas is at a low pressure and exits the gas escape route, which includes flowing outside the turns of the heat exchanger 40. As it is cold now, it cools the gas flowing inside the turns. This makes cooling more efficient and achieves cooler temperatures. After passing through the heat exchanger, the exhaust gas flows through the rest of the gas escape route, as indicated by number 70. Eventually, the exhaust gas is expelled into the atmosphere.

Prior art heating procedures such as exhaust blocking, reverse heat transfer, and electric heating may be employed. The preferred method of heating is to supply high pressure helium through the supply line, the heat exchanger and the Joule-Thompson nozzle. Helium is heated when it is expanded through the gas outlet. Therefore, the gas supply to the probe can be switched from high pressure nitrogen or argon to high pressure helium to effect rapid reheating of the cryosurgical probe.

Now with reference to Figure 3, the use of the present cryosurgical probe 10, positioned against the heart, 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 homogeneous elongated lesions (both curved and straight) in desired locations that are often difficult to access with a straight surgical implementation.

Now with reference to Figure 4, another embodiment of the present invention is illustrated, generally referred to as No. 80. The cryosurgical probe 80 includes an elongated rod assembly with a rigid main portion 82 thermally insulated, the malleable segment being a portion 84 on end. This embodiment is generally useful when the surgeon requires a rigid stem.

Now with reference to Figure 5, another embodiment of the present invention is illustrated, generally designated as number 86. The cryosurgical probe 86 includes an elongated rod assembly with a thermally insulated malleable main portion 88, the tip portion 90 being rigid .

Now with reference to Figure 6, another embodiment of the present invention is illustrated, generally designated as No. 92, which includes an elongated rod assembly with a malleable main portion 94 thermally insulated, the tip portion 96 also being malleable as in the embodiment of Figure 1. This shows how both the freezing tip portion 96 and the thermally insulated main portion 94 can be malleable. However, for certain applications they can be malleable to varying degrees.

Now, with reference to Figure 7, another embodiment of the present invention is illustrated, generally designated number 98. The cryosurgical probe 98 includes an elongated rod assembly with a malleable and thermally insulated portion 100. However, a desired freezing portion 102 is exposed therein. This embodiment is useful for directing the cryogenic effect in a specific direction while preventing damage to adjacent structures.

The embodiment of Figure 8, generally designated number 104, is similar to that of Figure 7; however, multiple freezing portions 106 are provided.

In the embodiment illustrated in Figure 9, generally designated with the number 108, the location of the freezing portion can be changed by providing a cut 112 in the thermal insulation, thus providing rotation of the tip portion 114, as indicated by the arrow 116.

With reference to Figure 10, another embodiment of the present invention, generally designated No. 118, is illustrated in which the thermal insulation 119 is provided with the longitudinal movement capability along the tube 120, as indicated by arrow 122, thus allowing the desired freezing positions.

Obviously, many modifications and variations of the present invention are possible in view of the above teachings. For example, Figure 11 schematically shows how multiple layers of thermal insulation can be used to control the freezing zone. In this embodiment, generally designated with the number 124, an inner insulation layer 126 located around the steel rod 128, directs the freezing in one direction while a moving outer layer 130 controls the length of the freezing zone. Figure 12 illustrates an embodiment of the present invention, generally designated number 132, in which rotation of the elongated rod assembly, or of a portion of the elongated rod assembly, can be provided on its axis. It should therefore be understood that the invention can be practiced in other ways than those specifically described without departing from the scope of the appended claims.

What is claimed and desired by the United States Patent Letters is: