SYSTEM AND METHOD FOR DETECTING BENDING OF AN ELECTROSURGICAL DEVICE

Abstract

A system for detecting bending of an electrosurgical device includes a strain relief configured to be coupled to a shaft of an electrosurgical device, a piezoelectric actuator disposed within the strain relief and configured to bend upon bending of the electrosurgical device, and a bending detection circuit in electrical communication with the piezoelectric actuator and configured to detect a bending of the piezoelectric actuator.

Claims

1-20. (canceled)

21. A system for detecting bending of an electrosurgical device, comprising: a strain relief configured to be coupled to a shaft of an electrosurgical device; a piezoelectric actuator disposed within the strain relief and configured to bend upon bending of the electrosurgical device; and a bending detection circuit in electrical communication with the piezoelectric actuator and configured to detect a bending of the piezoelectric actuator.

22. The system according to claim 21, wherein the piezoelectric actuator includes a first layer configured to stretch upon bending of the electrosurgical device and a second layer configured to compress upon bending of the electrosurgical device.

23. The system according to claim 21, wherein the bending detection circuit is configured to generate an alarm based on a detection of bending of the piezoelectric actuator.

24. The system according to claim 21, wherein the bending detection circuit is disposed within an electrosurgical energy source coupled to the electrosurgical device.

25. The system according to claim 21, wherein the strain relief is configured to be coupled to an outer surface of the shaft of the electrosurgical device.

26. The system according to claim 21, wherein the first and second layers of the piezoelectric actuator are configured to be coupled to an outer surface of the shaft of the electrosurgical device.

27. The system according to claim 21, wherein the strain relief is configured to couple to a hub of the electrosurgical device, the hub configured to couple the electrosurgical device to an electrosurgical energy source.

28. The system according to claim 21, wherein the electrosurgical device is a microwave antenna.

29. The system according to claim 21, wherein the strain relief is configured to be coaxially disposed around the shaft of the electrosurgical device.

30. A system for detecting bending of an electrosurgical device, comprising: a piezoelectric actuator configured to be coupled to a shaft of an electrosurgical device, the piezoelectric actuator including at least one layer configured to be disposed circumferentially around the shaft of the electrosurgical device and configured to bend upon bending of the electrosurgical device; and a bending detection circuit in electrical communication with the piezoelectric actuator and configured to detect a bending of the piezoelectric actuator.

31. The system according to claim 30, wherein the piezoelectric actuator includes two layers configured to be disposed circumferentially around the shaft of the electrosurgical device.

32. The system according to claim 30, further comprising a strain relief coupled to the piezoelectric actuator.

33. The system according to claim 32, wherein the strain relief is configured to be coupled to an outer surface of the shaft of the electrosurgical device.

34. The system according to claim 32, wherein the strain relief is configured to be coaxially disposed around the shaft of the electrosurgical device.

35. The system according to claim 32, wherein the strain relief is configured to couple to a hub of the electrosurgical device, the hub configured to couple the electrosurgical device to an electrosurgical energy source.

36. The system according to claim 30, wherein the electrosurgical device is a microwave antenna.

37. An antenna assembly having a bending detection system, comprising: an elongated shaft configured to deliver electrosurgical energy to tissue; a strain relief coupled to a proximal portion of the elongated shaft; and a bending detection circuit in electrical communication with the strain relief and configured to detect a bending of the strain relief.

38. The antenna assembly according to claim 37, further comprising a piezoelectric actuator disposed within the strain relief and configured to bend upon bending of the elongated shaft.

39. The antenna assembly according to claim 37, wherein the strain relief is coupled to a hub of the antenna assembly, the hub coupled to the proximal portion of the elongated shaft and configured to couple the elongated shaft to an electrosurgical energy source.

40. The antenna assembly according to claim 37, wherein the strain relief is coupled to an outer surface of the elongated shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Aspects and features of the presently-disclosed systems for electrosurgical tissue ablation systems capable of detecting excessive bending of a probe shaft and alerting a user will become apparent to those of ordinary skill in the art when descriptions thereof are read with reference to the accompanying drawings, of which:

[0038] FIG. 1 is a schematic diagram of an electrosurgical system including an energy-delivery device and circuitry for detecting bending, including excessive bending, of an ablation probe of the electrosurgical system in accordance with an embodiment of the present disclosure;

[0039] FIG. 2 is a perspective, phantom view of the ablation probe and a strain relief surrounding a portion of the ablation probe having one or more piezoelectric bending actuators or generators for detecting bending, including excessive bending, of the probe in accordance with an embodiment of the present disclosure;

[0040] FIG. 3 is a cross-sectional view of the ablation probe and the strain relief shown by FIG. 2 being bent in a first direction causing a two-layer piezoelectric bending actuator or generator within the strain relief to bend (one layer of the actuator is compressed and the other layer is stretched);

[0041] FIG. 4 is a perspective, cut-away view of an ablation probe of the electrosurgical system shown by FIG. 1 having one or more piezoelectric bending actuators or generators for detecting bending, including excessive bending, of the probe in accordance with another embodiment of the present disclosure;

[0042] FIG. 5 is a cross-sectional view of the ablation probe shown by FIG. 4 being bent in a first direction causing a two-layer piezoelectric bending actuator or generator within the ablation probe to bend (one layer of the actuator is compressed and the other layer is stretched);

[0043] FIG. 6 is a perspective view of an alternative embodiment of the ablation probe of the electrosurgical system shown by FIG. 1 having at least two electrical contacts on a shaft of the probe and at least two electrical contacts in proximity to the shaft for detecting bending, including excessive bending, of the probe in accordance with the present disclosure; and

[0044] FIG. 7 is perspective view of the ablation probe of FIG. 6 showing an electrical contact on the shaft of the probe making contact with an electrical contact in proximity to the shaft due to bending of the probe.

DETAILED DESCRIPTION

[0045] Hereinafter, embodiments of the presently-disclosed systems for thermal-feedback-controlled rate of fluid flow to a fluid-cooled antenna assembly and methods of directing energy to tissue using the same are described with reference to the accompanying drawings. Like reference numerals may refer to similar or identical elements throughout the description of the figures.

[0046] This description may use the phrases in an embodiment, in embodiments, in some embodiments, or in other embodiments, which may each refer to one or more of the same or different embodiments in accordance with the present disclosure. For the purposes of this description, a phrase in the form A/B means A or B. For the purposes of the description, a phrase in the form A and/or B means (A), (B), or (A and B). For the purposes of this description, a phrase in the form at least one of A, B, or C means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0047] Various embodiments of the present disclosure provide systems for detecting bending, including excessive bending, of an electrosurgical device, such as an ablation probe, of an electrosurgical system. The ablation probe, for exemplary purposes in describing the various embodiments of the present disclosure, is an ablation probe including a fluid-cooled antenna assembly. Additionally, the electrosurgical system includes a thermal-feedback-controlled rate of fluid flow to control the fluid flow to the ablation probe. It is contemplated that embodiments of the present disclosure for detecting bending, including excessive bending, of an ablation probe or other electrosurgical device can be implemented, integrated and/or otherwise incorporated in other systems and electrosurgical devices which are not described or mentioned herein. The description of the embodiments of the present disclosure to certain systems, especially electrosurgical systems, is for exemplary purposes only and shall not be construed as limiting the embodiments described herein to only these systems and variants thereof. That is, for example, embodiments may be implemented using electromagnetic radiation at microwave frequencies or at other frequencies.

[0048] An electrosurgical system including a detection system for detecting bending, including excessive bending, of an ablation probe, a coolant supply system and a feedback control system configured to provide a thermal-feedback-controlled rate of fluid flow to an energy applicator, according to various embodiments, is designed and configured to operate between about 300 MHz and about 10 GHz. Systems for detecting bending of the ablation probe and for thermal-feedback-controlled rate of fluid flow to electrosurgical devices, as described herein, may be used in conjunction with various types of devices, such as microwave antenna assemblies having either a straight or looped radiating antenna portion, etc., which may be inserted into or placed adjacent to tissue to be treated.

[0049] Various embodiments of the presently-disclosed electrosurgical systems including a detection system for detecting bending, including excessive bending, of an ablation probe and feedback control system configured to provide a thermal-feedback-controlled rate of fluid flow to an energy applicator disposed in fluid communication with a coolant supply system are suitable for microwave ablation and for use to pre-coagulate tissue for microwave ablation-assisted surgical resection. Although various methods described hereinbelow are targeted toward microwave ablation and the complete destruction of target tissue, it is to be understood that methods for directing electromagnetic radiation may be used with other therapies in which the target tissue is partially destroyed or damaged, such as, for example, to prevent the conduction of electrical impulses within heart tissue. In addition, although the following description describes the use of a dipole microwave antenna, the teachings of the present disclosure may also apply to a monopole, helical, or other suitable type of antenna assembly.

[0050] FIG. 1 shows an electrosurgical system 10 according to an embodiment of the present disclosure that includes an energy applicator or probe 100, an electrosurgical power generating source 28, e.g., a microwave or RF electrosurgical generator, detection circuitry 84 for detecting bending, including excessive bending of the probe 100 using at least one signal transmitted to the detection circuitry 84 via transmission line 15, and a feedback control system 14 operably associated with a coolant supply system 11. Probe 100 is operably-coupled to the electrosurgical power generating source 28, and disposed in fluid communication with the coolant supply system 11. In some embodiments, one or more components of the coolant supply system 11 may be integrated fully or partially into the electrosurgical power generating source 28. Coolant supply system 11, which is described in more detail later in this description, is configured to provide coolant fluid F to the probe 100. Probe 100, which is described in more detail later in this description, may be integrally associated with a hub 142 configured to provide electrical and/or coolant connections to the probe.

[0051] The probe 100 includes a strain relief 200. The strain relief 200 is fixed to a surface of the hub 142 to counter mechanical stress when the probe 100 bends during an electrosurgical procedure. The strain relief 200, as further described below with reference to FIG. 2, includes one or more piezoelectric bending actuators or generators for detecting bending, including excessive bending, of the probe 100. In some embodiments, the probe 100 may extend from a handle assembly (not shown).

[0052] With reference to FIG. 2, there is shown a perspective, phantom view of ablation probe 100 and strain relief 200 with the bending detection circuitry 84 having one or more bending detection members, such as one or more piezoelectric bending actuators or generators 202, within the strain relief 200 for use in detecting bending, including excessive bending, of the probe 100. FIG. 3 shows a cross-sectional view of the ablation probe 100 and strain relief 200 shown by FIG. 2 being bent in a first direction causing the two-layer piezoelectric bending actuator or generator 202 within the strain relief 200 to bend. That is, during bending of the outer jacket 139 of the probe 100, the strain relief 200 also bends. The bending of the strain relief 200 causes one layer 204 of the actuator 202 to be stretched and the other layer 206 to be compressed (see FIG. 3). The bending of the strain relief 200 and the actuator therein 202 is detected by the detection circuitry 84. If the bending is detected to be beyond a predetermined threshold, i.e., excessive bending is detected by the detection circuitry 84, the detection circuitry 84 generates a signal for activating an audible alarm, lighting one or more LEDs or other light sources, tactile feedback, or any other means for notifying the user of the excessive bending.

[0053] With reference to FIGS. 4 and 5, there is shown a perspective, cut-away view and a cross-sectional view, respectively, of an alternate embodiment. In this embodiment, one or more piezoelectric bending actuators or generators 202 are placed within the ablation probe 100, such as, for example, under the outer jacket 139 of the probe 100 instead of within the strain relief 200. As with the embodiment described above with reference to FIGS. 2 and 3, the bending detection circuitry 84 utilizes the one or more piezoelectric bending actuators or generators 202 within the probe 100 to detect bending, including excessive bending, of the probe 100.

[0054] FIG. 5 illustrates the ablation probe 100 shown by FIG. 4 being bent in a first direction causing the two-layer piezoelectric bending actuator or generator 202 within the probe 100 to bend. That is, during bending of the outer jacket 139 of the probe 100, one layer 204 of the actuator 202 is stretched and the other layer 206 is compressed. The bending of the outer jacket 139 and the actuator 202 therein is detected by the detection circuitry 84. If the bending is detected to be beyond a predetermined threshold, i.e., excessive bending is detected by the detection circuitry 84, the detection circuitry 84 generates a signal for activating an audible alarm, lighting one or more LEDs or other light sources, tactile feedback, or any other means for notifying the user of the excessive bending.

[0055] It is envisioned that the one or more piezoelectric bending actuators or generators 202 can be replaced or used in conjunction with any other device or apparatus capable of detecting bending of the probe 100. It is also envisioned in an alternate embodiment that a piezoelectric bending actuator or generator 202 may be placed within the strain relief 200 and within the probe 100.

[0056] The actuator 202 shown in the embodiments of FIGS. 2-5 can be a multilayer ceramic piezoelectric bending actuator available from Noliac A/S based in Denmark or piezoelectric bending actuators available from Piezo Systems, Inc., Woburn, Mass. Even though FIGS. 2 and 3, show a two-layer bending actuator 202, other types of bending actuators can be used, such as 2-layer circular bending disk actuators, 4-layer rectangular bending actuators, etc.

[0057] In another embodiment shown by FIGS. 6 and 7, two or more electrical contacts 402, 404 are positioned in opposing surfaces of two stationary fixtures, protrusions or extensions 406, 408 extending from the hub body 145. In this embodiment, the bending detection members include two or more electrical contacts 410, 412 positioned on the outer jacket 139 of the probe 100 and configured to contact a respective one of the two electrical contacts 402, 404 positioned on the two stationary fixtures 406, 408 when the probe 100 is bent a predetermined amount. A closed circuit is created by one of the contacts 410, 412 positioned on the probe 100 contacting one of the contacts 402, 404 positioned on the fixtures 406, 408 as shown by FIG. 7. The closed circuit alerts the user of the excessive bending of the probe 100 by activating an audible alarm, lighting one or more LEDs or other light sources, tactile feedback, or any other means.

[0058] In some embodiments, the electrosurgical system 10 includes one or more sensors capable of generating a signal indicative of a temperature of a medium in contact therewith (referred to herein as temperature sensors) and/or one or more sensors capable of generating a signal indicative of a rate of fluid flow (referred to herein as flow sensors). In such embodiments, the feedback control system 14 may be configured to provide a thermal-feedback-controlled rate of fluid flow to the probe 100 using one or more signals output from one or more temperature sensors and/or one or more flow sensors operably associated with the probe 100 and/or conduit fluidly-coupled to the probe 100.

[0059] An embodiment of a feedback control system, such as the feedback control system 14 of FIG. 1, in accordance with the present disclosure, is shown in more detail in FIG. 2. It is to be understood, however, that other feedback control system embodiments (e.g., feedback control systems 414 and 514 shown in FIGS. 4 and 5, respectively) may be used in conjunction with coolant supply systems in various configurations. In some embodiments, the feedback control system 14, or component(s) thereof, may be integrated fully or partially into the electrosurgical power generating source 28.

[0060] In the embodiment shown in FIG. 1, the feedback control system 14 is operably associated with a processor unit 82 disposed within or otherwise associated with the electrosurgical power generating source 28. Processor unit 82 may be communicatively-coupled to one or more components or modules of the electro surgical power generating source 28, e.g., a user interface 121 and a generator module 86. Processor unit 82 may additionally, or alternatively, be communicatively-coupled to one or more temperature sensors (e.g., two sensors TS1 and TS2 shown in FIG. 1) and/or one or more flow sensors (e.g., one sensor FS1 shown in FIG. 1) for receiving one or more signals indicative of a temperature (referred to herein as temperature data) and/or one or more signals indicative of a flow rate (referred to herein as flow data). Transmission lines may be provided to electrically couple the temperature sensors, flow sensors and/or other sensors, e.g., pressure sensors, to the processor unit 82.

[0061] Feedback control system embodiments may additionally, or alternatively, be operably associated with a processor unit deployed in a standalone configuration, and/or a processor unit disposed within the probe 100 or otherwise associated therewith. In some embodiments, where the probe 100 extends from a handle assembly (not shown), the feedback control system may be operably associated with a processor unit disposed within the handle assembly. Examples of handle assembly embodiments are disclosed in commonly assigned U.S. patent application Ser. No. 12/686,726 filed on Jan. 13, 2010, entitled ablation device with user interface at device handle, system including same, and method of ablating tissue using same.

[0062] Electrosurgical power generating source 28 may include any generator suitable for use with electrosurgical devices, and may be configured to provide various frequencies of electromagnetic energy. In some embodiments, the electrosurgical power generating source 28 is configured to provide microwave energy at an operational frequency from about 300 MHz to about 10 GHz. In some embodiments, the electrosurgical power generating source 28 is configured to provide electrosurgical energy at an operational frequency from about 400 KHz to about 500 KHz. An embodiment of an electrosurgical power generating source, such as the electrosurgical power generating source 28 of FIG. 1, in accordance with the present disclosure, is shown in more detail in FIG. 3.

[0063] Probe 100 may include one or more antennas of any suitable type, such as an antenna assembly (or antenna array) suitable for use in tissue ablation applications. For ease of explanation and understanding, the probe 100 is described as including a single antenna assembly 112. In some embodiments, the antenna assembly 112 is substantially disposed within a sheath 138. Probe 100 generally includes a coolant chamber 137 defined about the antenna assembly 112. In some embodiments, the coolant chamber 137, which is described in more detail later in this description, includes an interior lumen defined by the sheath 138.

[0064] Probe 100 may include a feedline 110 coupled to the antenna assembly 112. A transmission line 16 may be provided to electrically couple the feedline 110 to the electrosurgical power generating source 28. Feedline 110 may be coupled to a connection hub 142, which is described in more detail later in this description, to facilitate the flow of coolant and/or buffering fluid into, and out of, the probe 100.

[0065] In the embodiment shown in FIG. 1, the feedback control system 14 is operably associated with a flow-control device 50 disposed in fluid communication with a fluid-flow path of the coolant supply system 11 (e.g., first coolant path 19) fluidly-coupled to the probe 100. Flow-control device 50 may include any suitable device capable of regulating or controlling the rate of fluid flow passing though the flow-control device 50, e.g., a valve of any suitable type operable to selectively impede or restrict flow of fluid through passages in the valve. Processor unit 82 may be configured to control the flow-control device 50 based on determination of a desired fluid-flow rate using temperature data received from one or more temperature sensors (e.g., TS1, TS2 through TSN shown in FIG. 1).

[0066] In some embodiments, the flow-control device 50 includes a valve 52 including a valve body 54 and an electromechanical actuator 56 operatively-coupled to the valve body 54. Valve body 54 may be implemented as a ball valve, gate valve, butterfly valve, plug valve, or any other suitable type of valve. In the embodiment shown in FIG. 1, the actuator 56 is communicatively-coupled to with the processor unit 82 via a transmission line 32. Processor unit 82 may be configured to control the flow-control device 50 by activating the actuator 56 to selectively adjust the fluid-flow rate in a fluid-flow path (e.g., first coolant path 19 of the coolant supply system 11) fluidly-coupled to the connection hub 142 to achieve a desired fluid-flow rate. The desired fluid-flow rate may be determined by a computer program and/or logic circuitry associated with the processor unit 82. The desired fluid-flow rate may additionally, or alternatively, be selected from a look-up table TX,Y (shown in FIGS. 2 and 5) or determined by a computer algorithm stored within a memory device 8 (shown in FIGS. 2 and 5).

[0067] Embodiments including a suitable pressure-relief device 40 disposed in fluid communication with the diversion flow path 21 may allow the fluid-movement device 60 to run at a substantially constant speed and/or under a near-constant load (head pressure) regardless of the selective adjustment of the fluid-flow rate in the first coolant path 19. Utilizing a suitable pressure-relief device 40 disposed in fluid communication with the diversion flow path 21, in accordance with the present disclosure, may allow the fluid-movement device 60 to be implemented as a single speed device, e.g., a single speed pump.

[0068] Feedback control system 14 may utilize data D (e.g., data representative of a mapping of temperature data to settings for properly adjusting one or more operational parameters of the flow-control device 50 to achieve a desired temperature and/or a desired ablation) stored in a look-up table TX,Y (shown in FIGS. 2 and 5), where X denotes columns and Y denotes rows, or other data structure, to determine the desired fluid-flow rate. In the embodiment shown in FIG. 1, the electrosurgical system 10 includes a first temperature sensor TS1 capable of generating a signal indicative of a temperature of a medium in contact therewith and a second temperature sensor TS2 capable of generating a signal indicative of a temperature of a medium in contact therewith. Feedback control system 14 may be configured to utilize signals received from the first temperature sensor TS1 and/or the second temperature sensor TS2 to control the flow-control device 50.

[0069] In some embodiments, the electrosurgical system 10 includes a flow sensor FS1 communicatively-coupled to the processor unit 82, e.g., via a transmission line 36. In some embodiments, the flow sensor FS1 may be disposed in fluid communication with the first coolant path 19 or the second coolant path 20. Processor unit 82 may be configured to control the flow-control device 50 based on determination of a desired fluid-flow rate using one or more signals received from the flow sensor FS1. In some embodiments, the processor unit 82 may be configured to control the flow-control device 50 based on determination of a desired fluid-flow rate using one or more signals received from the flow sensor FS1 in conjunction with one or more signals received from the first temperature sensor TS1 and/or the second temperature sensor TS2. Although the electrosurgical system 10 shown in FIG. 1 includes one flow sensor FS1, alternative embodiments may be implemented with a plurality of flow sensors (e.g., FS1, FS2 through FSM shown in FIG. 1) adapted to provide a measurement of the rate of fluid flow into and/or out of the probe 100 and/or conduit fluidly-coupled to the probe 100.

[0070] Electrosurgical system 10 may additionally, or alternatively, include one or more pressure sensors configured to provide a measurement of the fluid pressure in the probe 100 and/or conduit fluidly-coupled the probe 100. In some embodiments, the electrosurgical system 10 includes one or more pressure sensors (e.g., pressure sensor 70) disposed in fluid communication with one or more fluid-flow paths (e.g., first coolant path 19) of the coolant supply system 11 as opposed to a pressure sensor disposed within the probe 100, reducing cost and complexity of the probe 100.

[0071] In the embodiment shown in FIG. 1, the processor unit 82 is operably associated with a pressure sensor 70 disposed in fluid communication with a fluid-flow path of the coolant supply system 11. Processor unit 82 may be communicatively-coupled to the pressure sensor 70 via a transmission line 30 or wireless link. Processor unit 82 may additionally, or alternatively, be operably associated with one or more pressure sensors disposed within the probe 100, e.g., disposed in fluid communication with the coolant chamber 137.

[0072] Pressure sensor 70 may include any suitable type of pressure sensor, pressure transducer, pressure transmitter, or pressure switch. Pressure sensor 70 (also referred to herein as pressure transducer) may include a variety of components, e.g., resistive elements, capacitive elements and/or piezo-resistive elements, and may be disposed at any suitable position in the coolant supply system 11. In some embodiments, the pressure transducer 70 is disposed in fluid communication with the first coolant path 19 located between the fluid-movement device 60 and the flow-control device 50, e.g., placed at or near the flow-control device 50.

[0073] In some embodiments, the processor unit 82 may be configured to control the flow-control device 50 based on determination of a desired fluid-flow rate using pressure data received from one or more pressure sensors. In some embodiments, the processor unit 82 may be configured to control the flow-control device 50 based on determination of a desired fluid-flow rate using one or more signals received from the first temperature sensor TS1 and/or the second temperature sensor TS2 and/or the flow sensor FS1 in conjunction with one or more signals received from the pressure transducer 70.

[0074] In some embodiments, the processor unit 82 may be configured to control the amount of power delivered to the antenna assembly 112 based on time and power settings provided by the user in conjunction with sensed temperature signals indicative of a temperature of a medium, e.g., coolant fluid F, in contact with one or one temperature sensors operably associated with the antenna assembly 112 and/or the connection hub 142. In some embodiments, the processor unit 82 may be configured to increase and/or decrease the amount of power delivered to the antenna assembly 112 when sensed temperature signals indicative of a temperature below/above a predetermined temperature threshold are received by processor unit 82, e.g., over a predetermined time interval.

[0075] Processor unit 82 may be configured to control one or more operating parameters associated with the electrosurgical power generating source 28 based on determination of whether the pressure level of fluid in the probe 100 and/or conduit fluidly-coupled to the probe 100 is above a predetermined threshold using pressure data received from one or more pressure sensors, e.g., pressure transducer 70. Examples of operating parameters associated with the electrosurgical power generating source 28 include without limitation temperature, impedance, power, current, voltage, mode of operation, and duration of application of electromagnetic energy.

[0076] In some embodiments, the output signal of the pressure transducer 70, representing a pressure value and possibly amplified and/or conditioned by means of suitable components (not shown), is received by the processor unit 82 and used for determination of whether the pressure level of fluid in the probe 100 and/or conduit fluidly-coupled to the probe 100 is above a predetermined threshold in order to control when power is delivered to the antenna assembly 112. In some embodiments, in response to a determination that the pressure level of fluid in the probe 100 and/or conduit fluidly-coupled to the probe 100 is below the predetermined threshold, the processor unit 82 may be configured to decrease the amount of power delivered to the antenna assembly 112 and/or to stop energy delivery between the electrosurgical power generating source 28 and the probe 100. In some embodiments, the processor unit 82 may be configured to enable energy delivery between the electrosurgical power generating source 28 and the probe 100 based on determination that the pressure level of fluid in the probe 100 and/or conduit fluidly-coupled to the probe 100 is above the predetermined threshold.

[0077] In some embodiments, the pressure transducer 70 is adapted to output a predetermined signal to indicate a sensed pressure below that of the burst pressure of the pressure-relief device 40. A computer program and/or logic circuitry associated with the processor unit 82 may be configured to enable the electrosurgical power generating source 28 and the flow-control device 50 in response to a signal from the pressure transducer 70. A computer program and/or logic circuitry associated with the processor unit 82 may be configured to output a signal indicative of an error code and/or to activate an indicator unit 129 if a certain amount of time elapses between the point at which energy delivery to the probe 100 is enabled and when the pressure signal is detected, e.g., to ensure that the fluid-movement device 60 is turned on and/or that the probe 100 is receiving flow of fluid before the antenna assembly 112 can be activated.

[0078] As shown in FIG. 1, a feedline 110 couples the antenna assembly 112 to a connection hub 142. Connection hub 142 may have a variety of suitable shapes, e.g., cylindrical, rectangular, etc. Connection hub 142 generally includes a hub body 145 defining an outlet fluid port 177 and an inlet fluid port 179. Hub body 145 may include one or more branches, e.g., three branches 164, 178 and 176, extending from one or more portions of the hub body 145. In some embodiments, one or more branches extending from the hub body 145 may be configured to house one or more connectors and/or ports, e.g., to facilitate the flow of coolant and/or buffering fluid into, and out of, the connection hub 142.

[0079] In the embodiment shown in FIG. 1, the hub body 145 includes a first branch 164 adapted to house a cable connector 165, a second branch 178 adapted to house the inlet fluid port 179, and a third branch 176 adapted to house the outlet fluid port 177. It is to be understood, however, that other connection hub embodiments may also be used. Examples of hub embodiments are disclosed in commonly assigned U.S. patent application Ser. No. 12/401,268 filed on Mar. 10, 2009, entitled COOLED DIELECTRICALLY BUFFERED MICROWAVE DIPOLE ANTENNA, and U.S. Pat. No. 7,311,703, entitled DEVICES AND METHODS FOR COOLING MICROWAVE ANTENNAS.

[0080] In some embodiments, the flow sensor FS1 is disposed in fluid communication with the first coolant path 19, e.g., disposed within the inlet fluid port 179 or otherwise associated with the second branch 178, and the second temperature sensor TS2 is disposed in fluid communication with the second coolant path 20, e.g., disposed within the outlet fluid port 177 or otherwise associated with the third branch 176. In other embodiments, the second temperature sensor TS2 may be disposed within the inlet fluid port 179 or otherwise associated with the second branch 178, and the flow sensor FS1 may be disposed within the outlet fluid port 177 or otherwise associated with the third branch 176.

[0081] Coolant supply system 11 generally includes a substantially closed loop having a first coolant path 19 leading to the probe 100 and a second coolant path 20 leading from the probe 100, a coolant source 90, and a fluid-movement device 60, e.g., disposed in fluid communication with the first coolant path 19. In some embodiments, the coolant supply system 11 includes a third coolant path 21 (also referred to herein as a diversion flow path) disposed in fluid communication with the first coolant path 19 and the second coolant path 20. The conduit layouts of the first coolant path 19, second coolant path 20 and third coolant path 21 may be varied from the configuration depicted in FIG. 1.

[0082] In some embodiments, a pressure-relief device 40 may be disposed in fluid communication with the diversion flow path 21. Pressure-relief device 40 may include any type of device, e.g., a spring-loaded pressure-relief valve, adapted to open at a predetermined set pressure and to flow a rated capacity at a specified over-pressure. In some embodiments, one or more flow-restrictor devices (not shown) suitable for preventing backflow of fluid into the first coolant path 19 may be disposed in fluid communication with the diversion flow path 21. Flow-restrictor devices may include a check valve or any other suitable type of unidirectional flow restrictor or backflow preventer, and may be disposed at any suitable position in the diversion flow path 21 to prevent backflow of fluid from the diversion flow path 21 into the first coolant path 19.

[0083] In some embodiments, the first coolant path 19 includes a first coolant supply line 66 leading from the coolant source 90 to the fluid-movement device 60, a second coolant supply line 67 leading from the fluid-movement device 60 to the flow-control device 50, and a third coolant supply line 68 leading from the flow-control device 50 to the inlet fluid port 179 defined in the second branch 178 of the connection hub body 145, and the second coolant path 20 includes a first coolant return line 95 leading from the outlet fluid port 177 defined in the third branch 176 of the hub body 145 to the coolant source 90. Embodiments including the diversion flow path 21 may include a second coolant return line 94 fluidly-coupled to the second coolant supply line 67 and the first coolant return line 95. Pressure-relief device 40 may be disposed at any suitable position in the second coolant return line 94. The spacing and relative dimensions of coolant supply lines and coolant return lines may be varied from the configuration depicted in FIG. 1.

[0084] Coolant source 90 may be any suitable housing containing a reservoir of coolant fluid F. Coolant fluid F may be any suitable fluid that can be used for cooling or buffering the probe 100, e.g., deionized water, or other suitable cooling medium. Coolant fluid F may have dielectric properties and may provide dielectric impedance buffering for the antenna assembly 112. Coolant fluid F may be a conductive fluid, such as a saline solution, which may be delivered to the target tissue, e.g., to decrease impedance and allow increased power to be delivered to the target tissue. A coolant fluid F composition may vary depending upon desired cooling rates and the desired tissue impedance matching properties. Various fluids may be used, e.g., liquids including, but not limited to, water, saline, perfluorocarbon, such as the commercially available Fluorinert perfluorocarbon liquid offered by Minnesota Mining and Manufacturing Company (3M), liquid chlorodifluoromethane, etc. In other variations, gases (such as nitrous oxide, nitrogen, carbon dioxide, etc.) may also be utilized as the cooling fluid. In yet another variation, a combination of liquids and/or gases, including, for example, those mentioned above, may be utilized as the coolant fluid F.

[0085] In the embodiment shown in FIG. 1, the fluid-movement device 60 is provided in the first coolant path 19 to move the coolant fluid F through the first coolant path 19 and into, and out of, the probe 100. Fluid-movement device 60 may include valves, pumps, power units, actuators, fittings, manifolds, etc. The position of the fluid-movement device 60, e.g., in relation to the coolant source 90, may be varied from the configuration depicted in FIG. 1. Although the coolant supply system 11 shown in FIG. 1 includes a single, fluid-movement device 60 located in the first coolant path 19, various combinations of different numbers of fluid-movement devices, variedly-sized and variedly-spaced apart from each other, may be provided in the first coolant path 19 and/or the second coolant path 20.

[0086] In some embodiments, the probe 100 includes a feedline 110 that couples the antenna assembly 112 to a hub, e.g., connection hub 142, that provides electrical and/or coolant connections to the probe 100. Feedline 110 may be formed from a suitable flexible, semi-rigid or rigid microwave conductive cable. Feedline 110 may be constructed of a variety of electrically-conductive materials, e.g., copper, gold, or other conductive metals with similar conductivity values. Feedline 110 may be made of stainless steel, which generally offers the strength required to puncture tissue and/or skin.

[0087] In some variations, the antenna assembly 112 includes a distal radiating portion 105 and a proximal radiating portion 140. In some embodiments, a junction member (not shown), which is generally made of a dielectric material, couples the proximal radiating section 140 and the distal radiating section 105. In some embodiments, the distal and proximal radiating sections 105, 140 align at the junction member and are also supported by an inner conductor (not shown) that extends at least partially through the distal radiating section 105.

[0088] Antenna assembly 112 may be provided with an end cap or tapered portion 120, which may terminate in a sharp tip 123 to allow for insertion into tissue with minimal resistance. One example of a straight probe with a sharp tip that may be suitable for use as the energy applicator 100 is commercially available under the trademark EVIDENT offered by Covidien. The end cap or tapered portion 120 may include other shapes, such as, for example, a tip 123 that is rounded, flat, square, hexagonal, or cylindroconical. End cap or tapered portion 120 may be formed of a material having a high dielectric constant, and may be a trocar.

[0089] Sheath 138 generally includes an outer jacket 139 defining a lumen into which the antenna assembly 112, or portion thereof, may be positioned. In some embodiments, the sheath 138 is disposed over and encloses the feedline 110, the proximal radiating portion 140 and the distal radiating portion 105, and may at least partially enclose the end cap or tapered portion 120. The outer jacket 139 may be formed of any suitable material, such as, for example, polymeric or ceramic materials. The outer jacket 139 may be a water-cooled catheter formed of a material having low electrical conductivity.

[0090] In accordance with the embodiment shown in FIG. 1, a coolant chamber 137 is defined by the outer jacket 139 and the end cap or tapered portion 120. Coolant chamber 137 is disposed in fluid communication with the inlet fluid port 179 and the outlet fluid port 177 and adapted to circulate coolant fluid F therethrough, and may include baffles, multiple lumens, flow restricting devices, or other structures that may redirect, concentrate, or disperse flow depending on their shape. Examples of coolant chamber embodiments are disclosed in commonly assigned U.S. patent application Ser. No. 12/350,292 filed on Jan. 8, 2009, entitled CHOKED DIELECTRIC LOADED TIP DIPOLE MICROWAVE ANTENNA, commonly assigned U.S. patent application Ser. No. 12/401,268 filed on Mar. 10, 2009, entitled COOLED DIELECTRICALLY BUFFERED MICROWAVE DIPOLE ANTENNA, and U.S. Pat. No. 7,311,703, entitled DEVICES AND METHODS FOR COOLING MICROWAVE ANTENNAS. The size and shape of the sheath 138 and the coolant chamber 137 extending therethrough may be varied from the configuration depicted in FIG. 1.

[0091] During microwave ablation, e.g., using the electrosurgical system 10, the probe 100 is inserted into or placed adjacent to tissue and microwave energy is supplied thereto. Ultrasound or computed tomography (CT) guidance may be used to accurately guide the probe 100 into the area of tissue to be treated. Probe 100 may be placed percutaneously or atop tissue, e.g., using conventional surgical techniques by surgical staff. A clinician may pre-determine the length of time that microwave energy is to be applied. Application duration may depend on many factors such as tumor size and location and whether the tumor was a secondary or primary cancer. The duration of microwave energy application using the probe 100 may depend on the progress of the heat distribution within the tissue area that is to be destroyed and/or the surrounding tissue. Single or multiple probes 100 may be used to provide ablations in short procedure times, e.g., a few seconds to minutes, to destroy cancerous cells in the target tissue region.

[0092] A plurality of probes 100 may be placed in variously arranged configurations to substantially simultaneously ablate a target tissue region, making faster procedures possible. Multiple probes 100 can be used to synergistically create a large ablation or to ablate separate sites simultaneously. Tissue ablation size and geometry is influenced by a variety of factors, such as the energy applicator design, number of energy applicators used simultaneously, time and wattage.

[0093] In operation, microwave energy having a wavelength, lambda (), is transmitted through the antenna assembly 112, e.g., along the proximal and distal radiating portions 140, 105, and radiated into the surrounding medium, e.g., tissue. The length of the antenna for efficient radiation may be dependent on the effective wavelength eff which is dependent upon the dielectric properties of the medium being radiated. Antenna assembly 112, through which microwave energy is transmitted at a wavelength , may have differing effective wavelengths eff depending upon the surrounding medium, e.g., liver tissue as opposed to breast tissue.

[0094] In some embodiments, the electrosurgical system 10 includes a first temperature sensor TS1 disposed within a distal radiating portion 105 of the antenna assembly 112. First temperature sensor TS1 may be disposed within or contacting the end cap or tapered portion 120. It is to be understood that the first temperature sensor TS1 may be disposed at any suitable position to allow for the sensing of temperature. Processor unit 82 may be electrically connected by a transmission line 34 to the first temperature sensor TS1. Sensed temperature signals indicative of a temperature of a medium in contact with the first temperature sensor TS1 may be utilized by the processor unit 82 to control the flow of electrosurgical energy and/or the flow rate of coolant to attain the desired ablation.

[0095] Electrosurgical system 10 may additionally, or alternatively, include a second temperature sensor TS2 disposed within the outlet fluid port 177 or otherwise associated with the third branch 176 of the hub body 145. Processor unit 82 may be electrically connected by a transmission line 38 to the second temperature sensor TS2. First temperature sensor TS1 and/or the second temperature sensor TS2 may be a thermocouple, thermistor, or other temperature sensing device. A plurality of sensors may be utilized including units extending outside the tip 123 to measure temperatures at various locations in the proximity of the tip 123.

[0096] As described in described in U.S. patent application Ser. No. 13/043,694, a memory device 8 in operable connection with the processor unit 82 can be provided. In some embodiments, the memory device 8 may be associated with the electrosurgical power generating source 28. In some embodiments, the memory device 8 may be implemented as a storage device integrated into the electrosurgical power generating source 28. In some embodiments, the memory device 8 may be implemented as an external device communicatively-coupled to the electrosurgical power generating source 28.

[0097] In some embodiments, the processor unit 82 is communicatively-coupled to the flow-control device 50, e.g., via a transmission line L5, and may be communicatively-coupled to the fluid-movement device 60, e.g., via a transmission line L6. In some embodiments, the processor unit 82 may be configured to control one or more operational parameters of the fluid-movement device 60 to selectively adjust the fluid-flow rate in a fluid-flow path (e.g., first coolant path 19) of the coolant supply system 11. In one non-limiting example, the fluid-movement device 60 is implemented as a multi-speed pump, and the processor unit 82 may be configured to vary the pump speed to selectively adjust the fluid-flow rate to attain a desired fluid-flow rate.

[0098] Processor unit 82 may be configured to execute a series of instructions to control one or more operational parameters of the flow-control device 50 based on determination of a desired fluid-flow rate using temperature data received from one or more temperature sensors, e.g., TS1, TS2 through TSN, where N is an integer. The temperature data may be transmitted via transmission lines L1, L2 through LN or wirelessly transmitted. One or more flow sensors, e.g., FS1, FS2 through FSM, where M is an integer, may additionally, or alternatively, be communicatively-coupled to the processor unit 82, e.g., via transmission lines L3, L4 through LM. In some embodiments, signals indicative of the rate of fluid flow into and/or out of the probe 100 and/or conduit fluidly-coupled the probe 100 received from one or more flow sensors FS1, FS2 through FSM may be used by the processor unit 82 to determine a desired fluid-flow rate. In such embodiments, flow data may be used by the processor unit 82 in conjunction with temperature data, or independently of temperature data, to determine a desired fluid-flow rate. The desired fluid-flow rate may be selected from a look-up table TX,Y or determined by a computer algorithm stored within the memory device 8.

[0099] In some embodiments, an analog signal that is proportional to the temperature detected by a temperature sensor, e.g., a thermocouple, may be taken as a voltage input that can be compared to a look-up table TX,Y for temperature and fluid-flow rate, and a computer program and/or logic circuitry associated with the processor unit 82 may be used to determine the needed duty cycle of the pulse width modulation (PWM) to control actuation of a valve (e.g., valve 52) to attain the desired fluid-flow rate. Processor unit 82 may be configured to execute a series of instructions such that the flow-control device 50 and the fluid-movement device 60 are cooperatively controlled by the processor unit 82, e.g., based on determination of a desired fluid-flow rate using temperature data and/or flow data, to selectively adjust the fluid-flow rate in a fluid-flow path (e.g., first coolant path 19) of the coolant supply system 11.

[0100] Feedback control system 14 may be adapted to control the flow-control device 50 to allow flow (e.g., valve 52 held open) for longer periods of time as the sensed temperature rises, and shorter periods of time as the sensed temperature falls. Electrosurgical system 10 may be adapted to override PWM control of the flow-control device 50 to hold the valve 52 open upon initial activation of the antenna assembly 112. For this purpose, a timer may be utilized to prevent the control device 50 from operating for a predetermined time interval (e.g., about one minute) after the antenna assembly 112 has been activated. In some embodiments, the predetermined time interval to override PWM control of the flow-control device 50 may be varied depending on setting, e.g., time and power settings, provided by the user. In some embodiments, the electrosurgical power generating source 28 may be adapted to perform a self-check routine that includes determination that the flow-control device 50 is open before enabling energy delivery between the electrosurgical power generating source 28 and the probe 100.

[0101] The above-described systems including circuitry for detecting excessive bending of a probe may be used in conjunction with a variety of electrosurgical devices adapted for treating tissue. Embodiments may be used in conjunction with electrosurgical devices adapted to direct energy to tissue, such as ablation probes, e.g., placed percutaneously or surgically, and/or ablation devices suitable for use in surface ablation applications.

[0102] The above-described systems including circuitry for detecting excessive bending of a probe may be suitable for a variety of uses and applications, including medical procedures, e.g., tissue ablation, resection, cautery, vascular thrombosis, treatment of cardiac arrhythmias and dysrhythmias, electrosurgery, etc.

[0103] It is envisioned that various aspects and features of the embodiments shown by the various figures and/or described herein can be combined to form additional embodiments of the electrosurgical system 10.

[0104] Although embodiments have been described in detail with reference to the accompanying drawings for the purpose of illustration and description, it is to be understood that the inventive processes and apparatus are not to be construed as limited thereby. It will be apparent to those of ordinary skill in the art that various modifications to the foregoing embodiments may be made without departing from the scope of the disclosure.