Patent Description:
Lower back injuries and chronic joint pain are major health problems resulting not only in debilitating conditions for the patient, but also in the consumption of a large proportion of funds allocated for health care, social assistance and disability programs. In the lower back, disc abnormalities and pain may result from trauma, repetitive use in the workplace, metabolic disorders, inherited proclivity, and/or aging. The existence of adjacent nerve structures and innervation of the disc are very important issues with respect to patient treatment for back pain. In joints, osteoarthritis is the most common form of arthritis pain and occurs when the protective cartilage on the ends of bones wears down over time.

A minimally invasive technique of delivering high-frequency electrical current has been shown to relieve localized pain in many patients. Generally, the high-frequency current used for such procedures is in the radiofrequency (RF) range, i.e. between <NUM> and <NUM> and more specifically between <NUM>-<NUM>. The RF electrical current is typically delivered from a generator via connected electrodes that are placed in a patient's body, in a region of tissue that contains a neural structure suspected of transmitting pain signals to the brain. The electrodes generally include an insulated shaft with an exposed conductive tip to deliver the radiofrequency electrical current. Tissue resistance to the current causes heating of tissue adjacent resulting in the coagulation of cells (at a temperature of approximately <NUM> for small unmyelinated nerve structures) and the formation of a lesion that effectively denervates the neural structure in question. Denervation refers to a procedure whereby the ability of a neural structure to transmit signals is affected in some way and usually results in the complete inability of a neural structure to transmit signals, thus removing the pain sensations.

To extend the size of a lesion, radiofrequency treatment may be applied in conjunction with a cooling mechanism, whereby a cooling means is used to reduce the temperature of the electrode-tissue interface. By cooling the probe, the tissue temperature near the probe is moderately controlled. In turn, more power can be applied to the target tissue without causing an unwanted increase in local tissue temperature that can result in tissue desiccation, charring, or steam formation. The application of a higher power allows regions of tissue further away from the energy delivery device to reach a temperature at which a lesion can form, thus increasing the size/volume of the lesion.

Existing cooled radiofrequency ablation systems circulate cooled fluid in a closed loop flow path by a peristaltic pump or pumps. For example, the cooled radiofrequency ablation pump system <NUM> of the prior art, illustrated in <FIG>, implements two pumps <NUM> that can be used to apply coolant fluid, supplied by an attached burette (not shown), to up to four cooled RF ablation probes controlled by a single generator (not shown). However, if more than two probes are used with the prior art pump system <NUM> of <FIG>, the coolant lines of the additional probe(s) must be connected in series ("daisy-chained") to the first or second probe. In this configuration, the daisy-chained probes must have an identical coolant flow rate because they are connected to a same pump <NUM>. As a result, independent control of the coolant flow rate, and thus the amount or rate of cooling, of more than two probes is impossible. Moreover, the existing cooled RF pump system <NUM> is incapable of determining which cooled RF ablation probe is connected to each respective one of the pumps <NUM> of the pump system <NUM>. As a result, if an issue is encountered during a procedure in which the probe must be replaced, the clinician must trace electrical and fluid cables and/or tubes to their respective origins, i.e., RF channel and pump head, a cumbersome process which interrupts the procedure on the patient.

Consequently, a need currently exists for a cooled radiofrequency ablation pump system and method that can map active RF channels to their respective pump assemblies. In particular, a cooled radiofrequency ablation pump system and method that can further detect the presence of daisy-chained cooled radiofrequency probes connected in series to a single pump assembly would be useful.

<CIT> discloses systems and methods for controlling energy delivery by mapping one or more devices capable of delivering energy, for example energy capable of modulating one or more properties of a tissue, to one or more sources of the energy or to one or more measuring devices. Associations between these components may be determined by delivering energy through the energy sources and measuring a response using the measuring devices.

The present invention provides a method to map active radiofrequency channels to respective pump assemblies for cooled radiofrequency ablation according to claim <NUM>.

In one particular embodiment, the step of activating each pump assembly of the plurality of pump assemblies individually in sequence can include activating each pump assembly individually in sequence with a pump activation time delay between the activation of each pump assembly. Further, the pump activation time delay can be from about <NUM> seconds to about <NUM> seconds.

In another embodiment, each radiofrequency probe can include a thermocouple at the tip of the probe configured to measure the temperature at the tip of the probe, the method further comprising a step of measuring the temperature at the tip of the probe. Moreover, the method can further include a step of measuring the temperature drop delay time between the time of activation of the first pump assembly and the time cooling fluid reaches the tip of the first radiofrequency ablation probe exhibiting a temperature decrease of at least <NUM> degrees.

In an additional embodiment, the step of mapping each cooled radiofrequency probe to a respective pump assembly connected thereto includes measuring the temperature drop delay for each cooled radiofrequency ablation probe and comparing the temperature drop delay time for each cooled radiofrequency ablation probe with the activation time of each of the pump assemblies. Further, each pump assembly can be mapped to the radiofrequency ablation probe that measures a temperature drop delay time soonest after the activation time of each pump assembly.

In yet another embodiment, the plurality of pump assemblies can include from two to four pump assemblies, further wherein the plurality of cooled radiofrequency probes can include from two to four cooled radiofrequency ablation probes.

In a further embodiment, the step of mapping each cooled radiofrequency probe to a respective pump assembly connected thereto further can include detecting the presence or absence of daisy-chained cooled radiofrequency probes, wherein daisy-chained cooled radiofrequency probes comprise two or more cooled radiofrequency probes associated with one pump assembly of the plurality of pump assemblies.

Also described but not claimed is a method of providing cooled radiofrequency ablation treatment to a patient. The method includes steps of: providing a pump system having a plurality of pump assemblies, a radiofrequency generator unit, and a plurality of cooled radiofrequency probes, wherein each cooled radiofrequency probe comprises a cable-tubing assembly having a radiofrequency cable and fluid tubing; connecting the cable of each cable-tubing assembly to an RF channel of the radiofrequency generator unit; connecting the fluid tubing of each cable-tubing assembly to a cooling fluid source; activating each pump assembly of the plurality of pump assemblies individually in sequence; mapping each cooled radiofrequency probe to a respective pump assembly connected thereto using a temperature drop delay time, wherein the temperature drop delay time is the amount of time for cooling fluid to reach a tip of the cooled radiofrequency ablation probe and initiate a temperature decrease at the tip of the cooled radiofrequency ablation probe after activation of a first pump assembly of the plurality of pump assemblies; inserting each cooled radiofrequency ablation probe into a target tissue area of the patient; and independently controlling each cooled radiofrequency probe to deliver cooled radiofrequency ablation treatment.

In one particular method, the step of activating each pump assembly of the plurality of pump assemblies individually in sequence includes activating each pump assembly individually in sequence with a pump activation time delay between the activation of each pump assembly. Further, the pump activation time delay can be from about <NUM> seconds to about <NUM> seconds.

In another method, each radiofrequency probe includes a thermocouple at the tip of the probe configured to measure the temperature at the tip of the probe, the method further comprising a step of measuring the temperature at the tip of the probe.

In an additional method, the step of mapping each cooled radiofrequency probe to a respective pump assembly connected thereto further includes detecting the presence or absence of daisy-chained cooled radiofrequency probes, wherein daisy-chained cooled radiofrequency probes comprise two or more cooled radiofrequency probes associated with one pump assembly of the plurality of pump assemblies.

In one more method, the step of independently controlling each cooled radiofrequency probe to deliver cooled radiofrequency ablation treatment includes independently controlling one or more of the respective pump assembly mapped to each cooled radiofrequency probe and the RF channel mapped to each cooled radiofrequency probe.

The present invention also provides a cooled radiofrequency ablation system according to claim <NUM>.

In one embodiment, each radiofrequency probe includes a thermocouple at the tip of the probe configured to measure the temperature at the tip of the probe.

In another embodiment, the plurality of pump assemblies includes from two to four pump assemblies, further wherein the plurality of cooled radiofrequency probes comprises from two to four cooled radiofrequency ablation probes.

In a further embodiment, the plurality of cooled radiofrequency ablation probes includes at least two radiofrequency ablation probes daisy-chained to a single pump assembly.

In an additional embodiment, the memory device stores further instructions which, when executed, cause the controller to detect the presence of two or more cooled radiofrequency ablation probes daisy-chained to a single pump assembly.

These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims.

As used herein, the terms "about," "approximately," or "generally," when used to modify a value, indicates that the value can be raised or lowered by <NUM>% and remain within the disclosed embodiment.

Generally speaking, the present invention is directed to a cooled radiofrequency ablation system and method, and in particular, a method to map active radiofrequency channels to respective pump assemblies for cooled radiofrequency ablation. The system includes a pump system having a plurality of pump assemblies, a radiofrequency generator unit, and a plurality of cooled radiofrequency probes, wherein each cooled radiofrequency probe comprises a cable-tubing assembly having a radiofrequency cable connected to the radiofrequency generator unit and a dual-lumen fluid tubing in communication with a pump assembly and connected to a cooling fluid source. Each pump assembly of the plurality of pump assemblies is activated individually in sequence. The system and method map each cooled radiofrequency probe to a respective pump assembly connected thereto by measuring a temperature drop delay time at the tip of each probe. The system and method can further detect the presence of multiple probes daisy-chained to a single pump assembly. The present inventor has found that the particular components of the radiofrequency ablation system and method of the present invention enable automated mapping between the plurality of pump assemblies and cooled radiofrequency ablation probes. Thus, the cooled radiofrequency ablation system can provide fully independent power control to each of the cooled radiofrequency ablation probes by independently controlling the individual pump assembly and RF channel associated with each probe. Moreover, the mapping generated by the present invention reduces the set-up time for the cooled radiofrequency ablation system prior to initiating a patient treatment procedure. In addition, if an issue is encountered during a cooled radiofrequency ablation procedure in which an individual probe must be replaced, the mapping of the present invention saves time in determining precisely which fluid conduit(s) and/or RF channel(s) are associated with the probe to be replaced. The specific features of the cooled radiofrequency ablation system and method of the present invention may be better understood with reference to <FIG>.

Referring now to the drawings, <FIG> illustrate the components of one embodiment of the cooled radiofrequency ablation system <NUM> of the present invention. In particular, <FIG> illustrates a perspective view of a radiofrequency generator <NUM> and pump system <NUM> for the cooled radiofrequency ablation system <NUM> of the present invention. As shown, the generator <NUM> includes a housing <NUM> and a display <NUM>, for example, a screen, a touch screen, or other graphic user interface. The generator housing <NUM> further includes a plurality of electrical connectors (not shown) through which the generator <NUM> is configured to be operably coupled to at least one radiofrequency ablation probe <NUM> to provide RF energy to the probe <NUM>. The pump system <NUM> is configured to sit on the top surface <NUM> of the housing <NUM> of the generator <NUM>. The pump system <NUM> includes a plurality, e.g., four (<NUM>), of peristaltic pump assemblies 250a, 250b, 250c and 250d. For ease of identification, the pump assemblies will be identified as first pump assembly 250a, second pump assembly 250b, third pump assembly 250c, and fourth pump assembly 250d. In some aspects of the invention, each of the pump assemblies 250a-d can be interchangeably removed from the pump system <NUM>. The pump system <NUM> can further include tubes <NUM> configured to be associated with each respective pump assembly 250a-d such that the pump assemblies 250a-d each pump cooling fluid through the tubes <NUM>. The tubes <NUM> can be held in place in the pump system <NUM> with clips <NUM> or any other suitable retaining means.

<FIG> illustrates an individual radiofrequency ablation probe <NUM> configured to be used with the pump system <NUM> and RF generator <NUM>. The probe <NUM> includes a handle <NUM> and an elongate member <NUM> in the form of a shaft extending from one end of the handle <NUM>. A cable-tubing assembly <NUM> extends from the opposite side of the handle <NUM> and includes an electrical cable <NUM> and a dual-lumen fluid tubing <NUM>. The electrical cable <NUM> can include an insulating jacket <NUM> constructed from, for example, polyvinyl chloride (PVC) or any other suitable material. The electrical cable <NUM> can terminate at a proximal end at an electrical connector <NUM>. The electrical connector <NUM> can be, for example, a circular electrical connector as shown in <FIG>. The dual-lumen fluid tubing <NUM> can be constructed from two lumens <NUM> and <NUM> having walls constructed from clear polyvinyl chloride (PVC). The walls of the two lumens <NUM> and <NUM> can be thermally bonded together. The dual-lumen fluid tubing <NUM> can terminate at a proximal end at Luer connector <NUM> of lumen <NUM> and Luer connector <NUM> of lumen <NUM>. Luer connector <NUM> can be positioned at the proximal end of lumen <NUM> and Luer connector <NUM> can be positioned at the proximal end of lumen <NUM>. For example, lumen <NUM> can be an inlet fluid lumen with Luer connector <NUM> functioning as an inlet fluid connector, and lumen <NUM> can be an outlet fluid lumen with Luer connector <NUM> functioning as an outlet fluid connector. In one embodiment, Luer connector <NUM> can be a male Luer connector and Luer connector <NUM> can be a female Luer connector. The cable-tubing assembly <NUM> can be bonded between an insulating jacket of the electrical cable <NUM> and the wall of at least one of the lumens of the dual-lumen fluid tubing <NUM> along the length of the assembly <NUM>. The bonding can be done, for example, by heat welding, UV adhesive, or any other suitable form of welding or bonding plastic or polymeric materials together. For example, the electrical cable <NUM> can be disposed in a recess <NUM> between the walls of the two lumens <NUM> and <NUM>, as illustrated in <FIG>. The cable-tubing assembly <NUM> can include at least one unbonded region on the proximal connector end of the cable-tubing assembly <NUM> in which the electrical cable <NUM> and the dual-lumen fluid tubing <NUM> are not bonded together such that the electrical cable <NUM> can be connected to the generator <NUM> and the dual-lumen fluid tubing <NUM> can be connected with tubing <NUM> of the pump system <NUM>.

<FIG> illustrate details of the elongate member <NUM> of the probe <NUM>. The elongate member <NUM> of each probe <NUM> forms an electrocap assembly that is thermally and electrically conductive for delivering electrical or radiofrequency energy to the patient's tissue. A distal end <NUM> of the elongate member <NUM> opposite the probe handle <NUM> forms an active tip <NUM> for delivering the cooled radiofrequency treatment to the patient's tissue. The electrocap assembly may include at least one fluid conduit <NUM> within the elongate member <NUM>, such as an inlet fluid conduit 126a and an outlet fluid conduit 126b, for delivering cooling fluid to and from the active tip <NUM>. The electrocap assembly may additionally include a thermocouple hypotube <NUM> extending the length of the elongated member <NUM> and protruding from the distal end of the elongated member. The thermocouple hypotube <NUM> may include a wire <NUM> made from an electrically conductive material such as constantan. The wire <NUM> can be insulated along the entire length of the elongate member <NUM> and welded to the hypotube <NUM> at a distal end <NUM> of the electrocap assembly to form a thermocouple <NUM>. The cooling fluid may be circulated in a volume <NUM> within the distal end <NUM> of the electrocap assembly adjacent the thermocouple <NUM> to control the temperature of the active tip <NUM>. Thus, RF energy can be transmitted to the active tip <NUM> via the wire <NUM>, which generates thermal energy, and the cooling fluid circulating in the volume <NUM> from the inlet fluid conduit 126a to the outlet fluid conduit 126b can cool the active tip <NUM> to control the temperature increase at the active tip <NUM>. Thus, the amount of tissue damage or ablation caused by RF energy delivered by the probe <NUM> in use can be modified by the circulation of cooling fluid through the elongate member <NUM>.

<FIG> shows a diagrammatic representation of the cooled radiofrequency ablation system <NUM> of the present invention, including pump system <NUM> having pumps 250a, 250b, 250c and 250d, controllers for the pumps 220a, 220b, 220c and 220d housed in the generator <NUM>, and cooled radiofrequency treatment probes <NUM> for delivering treatment to patient tissue. The pump system <NUM>, including a source of coolant fluid pumped through the tubing <NUM> to the probes 100a-d, works to reduce a temperature of material located at and proximate to one or more of the probe assemblies 100a-d. For example, as shown in <FIG>, the pump system <NUM> may include a plurality of pump assemblies 250a-d each having a peristaltic pump (via pump rotors) operable to circulate a fluid from the pump system <NUM> through one or more proximal cooling supply tubes (e.g., tubing <NUM> of <FIG>), the probe assemblies 100a-d, one or more proximal cooling return tubes <NUM> (see <FIG>) and back to the coolant fluid source of the pump system <NUM>. The peristaltic pump assemblies 250a-d are coupled to a power supply <NUM>. The power supply <NUM> can be housed within or provided by the generator <NUM>. In such embodiments, each of the plurality of pumps 250a-d may be in separate fluid communication with a respective one of the probe assemblies 100a-d. The fluid may be water, saline, or any other suitable fluid or gas. In alternate embodiments, the pump system <NUM> may include only one peristaltic pump or greater than four pumps. In addition, as shown in <FIG>, each of the pumps 250a-d may have independent speed (i.e. rotations per minute or RPM) controllers 220a, 220b, 220c, and 220d that are configured to independently adjust the speed of each respective pump 250a-d.

<FIG> additionally shows a plurality of RF channels 230a, 230b, 230c and 230d within the generator <NUM>. For ease of identification, the RF channels 230a-d will be identified as RF channel A 230a, RF channel B 230b, RF channel C 230c, and RF channel D 230d. The RF channels 230a-d are configured to be electrically connected with a respective one of the probes 100a-d to deliver RF energy to the probes 100a-d. For example, the electrical cable <NUM> (see <FIG>) of each respective probe 100a-d can be in operative communication with one of the RF channels 230a-d, e.g., by plugging in the electrical connector <NUM> into a respective one of the RF channel connections on the generator housing <NUM>.

Still referring to <FIG>, the system <NUM> may include a controller <NUM> for facilitating communication between the pump system <NUM> and the generator <NUM>, including the RF channels 230a-d. In this way, feedback control is established between the pump system <NUM> and the RF channels 230a-d of the generator <NUM>. The feedback control may include the generator <NUM>, the probe assemblies 100a-d and the pump system <NUM>. The feedback control may be implemented, for example, in a controller or control module <NUM> which may be a component of the generator <NUM>. In such embodiments, the generator <NUM> is operable to communicate bi-directionally with the probe assemblies 100a-d, e.g., via electrical connections (not shown) as well as with the pump system <NUM>. In the context of this invention, bi-directional communication refers to the capability of a device to both receive a signal from and send a signal to another device. The controller <NUM> includes a processor, microprocessor, or any other computing device, optionally further including a memory device storing one or more control algorithms. The one or more control algorithms can include the feedback control between the pump system <NUM> and the generator <NUM>, e.g., for independently controlling each of the probes 100a-d to deliver cooled RF ablation treatment.

However, as shown in <FIG> and <FIG>, the connections between each probe <NUM> and a respective pump assembly and RF channel are distinct. Stated another way, the cooling fluid tubing <NUM> of each probe <NUM> is separate from the electrical cable <NUM> of each probe <NUM>, and so the probe <NUM> connected to first pump assembly 250a may not necessarily be connected to RF channel A 230a. Thus, it is necessary to map each RF channel to a respective pump assembly associated with each probe <NUM> in order to independently control each probe <NUM>.

The system <NUM> of the present invention uses a sequential pump activation routine to map each RF channel to a respective pump assembly associated with each probe <NUM>. In particular, the sequential pump activation routine is implemented to prime the system <NUM>, i.e., prime the cooling fluid tubes <NUM> and prepare the probes <NUM> for delivering cooled RF treatment, before activating any treatment of patient tissue using the cooled RF ablation probes <NUM>. Each probe <NUM> is connected via its cable-tubing assembly <NUM> to the generator <NUM> via electrical connector <NUM> and to the cooling fluid tubing <NUM> via the inlet connector <NUM> and outlet connector <NUM>. For example, each of the probes 100a-d as shown in <FIG> are connected to one of the pump assemblies 250a-d and one of the RF channels 230a-d. To prime the system <NUM>, rather than initiating all of the pump assemblies 250a-d simultaneously, each of the pump assemblies 250a-d are activated individually in a predetermined sequence. For instance, first pump assembly 250a is activated first, second pump assembly 250b is activated second, third pump assembly 250c is activated third, and fourth pump assembly 250d is activated last. The predetermined sequence includes a pump activation time delay N. The pump activation time delay N is equal in between activation of each of the respective pump assemblies 250a-d. For instance, first pump assembly 250a is activated at time T= <NUM> seconds, second pump assembly 250b is activated at time T= N seconds, third pump assembly 250c is activated at time T = N+N seconds (stated alternatively, T = <NUM>*N seconds), and fourth pump assembly 250d is activated at time T = N+N+N seconds (stated alternatively, T = <NUM>*N seconds), as illustrated in <FIG>. The pump activation time delay can be from about <NUM> seconds to about <NUM> seconds, or any value therebetween.

As the pump assemblies 250a-d are activated in the predetermined sequence as described above, cooling fluid is transported through the tubing <NUM>, inlet fluid lumen <NUM> of the cable-tubing assembly <NUM> and the inlet fluid conduit 126a of each respective one of the probes 100a-d to the active tip <NUM> of the elongate member <NUM> of each of the respective probes 100a-d. When the cooling fluid reaches the thermocouple of the active tip <NUM>, a temperature drop is registered by the thermocouple <NUM>. For instance, the temperature at the active tip <NUM> of each of the respective probes 100a-d drops from an initial temperature IT to a cooled temperature CT. Each of the probes 100a-d has a temperature drop delay M. The temperature drop delay M is equal to the amount of time that passes between the initiation of a respective pump assembly and the time that the cooling fluid reaches the thermocouple of the active tip <NUM> of the probe <NUM> associated with the respective pump assembly to register a temperature drop of at least <NUM> degrees Celsius, such as from <NUM> degrees Celsius to about <NUM> degrees Celsius. In some particular embodiments, the temperature drop can be in a range from about <NUM> degree Celsius to about <NUM> degrees Celsius, such as from about <NUM> degrees Celsius to about <NUM> degrees Celsius, e.g., about <NUM> degrees Celsius. The temperature at the active tip <NUM> then cools from the initial temperature IT to the desired cooled temperature CT after the cooling fluid reached the active tip <NUM>. Assuming that the volumetric flow rate, path length of the tubing <NUM> and cross-sectional area of tubing <NUM> associated with each of the respective probes 100a-d and pump assemblies 250a-d are equal for all four probes 100a-d, the time it takes for the cooling fluid to reach the active tip <NUM> of each of the probes 100a-d, i.e., the temperature drop delay M, is equal.

In order to map the respective RF channels 230a-d to each of the pump assemblies 250a-d associated with each of the probes 100a-d, the above described sequential pump activation routine is implemented. For the sake of simplicity, it will be assumed that the probe 100a is electrically connected to RF channel A 230a, probe 100b is electrically connected to RF channel B 230b, probe 100c is electrically connected to RF channel C 230c, and probe 100d is electrically connected to RF channel D 230d. The pump assemblies 250a-d are activated individually in sequence with the pump activation time delay N between activation of each respective pump assembly, for example, in the order of first pump assembly 250a at time T = <NUM>, second pump assembly 250b at time T = N, third pump assembly 250c at time T = N+N, then fourth pump assembly 250d and time T = N+N+N. The generator <NUM> receives information from the active tip thermocouple <NUM> of each of the respective probes 100a-d via the respective RF channels 230a-d and records the time at which the active tip thermocouple <NUM> of each of the probes 100a-d registers a temperature drop M. The controller <NUM> compares the temperature drop delay, i.e., the time at which the active tip thermocouple <NUM> of each of the probes 100a-d registers a temperature drop, with the known sequence of activation of the pump assemblies 250a-d. The probe 100a-d associated with the RF channel 230a-d that has a total temperature drop delay soonest after each one of the respective pump assemblies 250a-d is activated is then mapped to that pump assembly. As shown in <FIG>, RF channel C 230c (associated with probe 100c) registered a temperature drop to the cooled temperature CT soonest after the first pump assembly 250a was activated, thus RF channel C 230c (and associated probe 100c) is mapped to the first pump assembly 250a. Next, RF channel A 230a (associated with probe 100a) registered a temperature drop to the cooled temperature CT, thus RF channel A 230a is mapped to the second pump assembly 250b. The RF channel D 250d (and associated probe 100d) next registered a temperature drop to the cooled temperature CT, so RF channel D 230d is mapped to the third pump assembly 250c. Finally, RF channel B 230b (and associated probe 100b) registered a temperature drop to the cooled temperature CT last, so RF channel B 230b is mapped to the fourth pump assembly 250d.

The controller <NUM> may further confirm the mapping of the RF channels to the pump assemblies by calculating the actual temperature drop delay times measured by each RF channel and comparing them to the theoretical temperature drop delay time based on the known values of pump activation time delay N and temperature drop delay M, where M is the time it takes the cooling fluid to reach the active tip <NUM> as evidenced by a decrease in the active tip temperature measured by the thermocouple. For instance, the temperature drop delay of RF channel C 230c (probe 100c) mapped to the first pump assembly 250a should be equal to M, as first pump assembly 250a has no pump activation time delay (because first pump assembly 250a is activated at time T=<NUM>). The temperature drop delay of RF channel A 230a (probe 100a) mapped to the second pump assembly 250b should be equal to N+M, as second pump assembly 250b has a pump activation time delay equal to N. The temperature drop delay of RF channel D 230d (probe 100d) mapped to the third pump assembly 250c should be equal to N+N+M, as third pump assembly 250c has a pump activation time delay equal to N+N. The temperature drop delay of RF channel B 230b (probe 100b) mapped to the fourth pump assembly 250d should be equal to N+N+N+M, as fourth pump assembly 250d has a pump activation time delay equal to N+N+N.

As shown in <FIG>, the time and temperature measurements of each of the RF channels 230a-d during the sequential pump activation routine can be graphically represented on the display <NUM>. The graphical representation can be in the form of a temperature versus time graph, shown in <FIG>, or any other suitable graphic or image displayed to indicate the mapping of the RF channels 230a-d to the pump assemblies 250a-d. Thus, the clinician(s) administering the cooled RF ablation treatment will be able to see which pump assemblies 250a-d are associated with which RF channels 230a-d to be able to independently control each of the probes 100a-d. Moreover, if an issue is encountered during the cooled RF ablation treatment and a probe needs to be replaced, the graphic on the display <NUM> will make it easy for the clinician to determine which pump assembly and which RF channel are associated with the affected probe.

As shown in <FIG>, in some aspects of the invention, a daisy-chained probe assembly <NUM> includes two probes <NUM> and <NUM> daisy-chained together, i.e., arranged in series, with the second probe <NUM> being positioned downstream of the first probe <NUM>. In an alternate embodiment, the probe assembly can include more than two probes. The probe assembly <NUM> further includes an electrical cable <NUM> for supplying energy to the probes <NUM> and <NUM>, and cooling fluid tubing <NUM> for carrying cooling fluid to and from the probes <NUM> and <NUM>. The electrical cable <NUM> and the cooling fluid tubing <NUM> communicate with each of the probes <NUM>, <NUM> at a probe handle <NUM> of each probe.

The electrical cable <NUM> may be formed as a Y-shaped electrical cable. Alternately, the electrical cable <NUM> may be T-shaped. The electrical cable <NUM> includes an electrical connector <NUM> located at an end of the cable <NUM> opposite from the probes <NUM>, <NUM>. The connector <NUM> is connected to a single electrical cable <NUM>. The single electrical cable <NUM> splits at a grommet <NUM> into two discrete cables with three conductors each, forming a first probe electrical cable <NUM> which connects to the first probe <NUM> and a second probe electrical cable <NUM> which connects to the second probe <NUM>. As shown in <FIG>, the probes <NUM>, <NUM> can be connected to the electrical cable <NUM> in parallel via the first probe electrical cable <NUM> and the second probe electrical cable <NUM>.

Still referring to <FIG>, the cooling fluid tubing <NUM> can include an inlet connector <NUM>, for example a female Luer connector, for connecting to a cooling fluid source (not shown). The cooling fluid tubing <NUM> inlet portion <NUM> may extend from the inlet connector <NUM> to the first probe <NUM>. A connecting tubing portion <NUM> of cooling fluid tubing <NUM> extends between the first probe <NUM> and the second probe <NUM>, which is downstream of the first probe <NUM> along the fluid tubing <NUM>. An outlet tubing portion <NUM> can extend from the second probe <NUM> to an outlet connector <NUM>, for example a male Luer connector. In one embodiment, the outlet connector <NUM> may connect to the cooling fluid source (not shown) to form a closed-loop cooling fluid system. In an alternative embodiment, the outlet connector <NUM> may connect to a waste bag (not shown) for disposal of the cooling fluid.

The connecting tubing portion <NUM> can connect between the first probe <NUM> and the second probe <NUM> so that cooling fluid flows from the first probe <NUM> to the second probe <NUM> before flowing through outlet tubing portion <NUM> to the fluid source or waste bag (not shown). The connecting tubing portion <NUM> may cool the cooling fluid based on the temperature of ambient air. For example, if cooling fluid is heated as it flows through the first probe <NUM>, the heat captured by the cooling fluid can be dissipated into the atmosphere by the ambient air temperature as the cooling fluid flows through connecting tubing portion <NUM> before reaching the second probe <NUM>. The connecting tubing portion <NUM> can have a length sufficient to dissipate any heat captured by cooling fluid in the first probe into the atmosphere prior the cooling fluid flowing into the second probe <NUM>. However, the path length for cooling fluid to reach the active tip of the first probe <NUM> is unequal to the path length for cooling fluid to reach the active tip of the second probe <NUM> because cooling fluid must pass through the first probe <NUM> and the connecting tubing portion <NUM> to reach the active tip of the second probe <NUM>. Thus, the temperature drop delay of the second probe <NUM> will differ from any of the known pump activation delay times (i.e., <NUM>, N, N+N, N+N+N) or temperature drop delay times (i.e., <NUM>+M, N+M, N+N+M, N+N+N+M) because a single cooling fluid tubing <NUM> is used for both probes <NUM> and <NUM>. Moreover, although probes <NUM> and <NUM> are electrically connected in parallel and receive RF energy at the same time, the temperature drop delay will differ for probes <NUM> and <NUM> due to the additional delay in receiving cooling fluid at the active tip of the second probe <NUM>.

Thus, the sequential pump activation routine of the present invention can be used to determine whether there are daisy-chained probes associated with any of the RF channels 230a-d and/or pump assemblies 250a-d. Because the pump activation time delays are known (i.e., <NUM>, N, N+N, N+N+N) and the cooling time delay M of individual (i.e., non daisy-chained) probes 100a-d is known, the controller <NUM> can compare the temperature drop delay of each RF channel to determine if the temperature drop delay does not match any of the known values in sequence following the activation of one or more of the pump assemblies 250a-d. For instance, when probes <NUM> and <NUM> are daisy-chained together, probe <NUM> will register a temperature drop delay slightly longer than the temperature drop delay of the probe <NUM> after its associated pump assembly is activated, but may be before or after any subsequent pump assembly is activated and unequal to any known temperature drop delay times (i.e., <NUM>+M, N+M, N+N+M, N+N+N+M), thus indicating to the controller <NUM> that the probes <NUM> and <NUM> are daisy-chained together.

After the sequential pump activation routine is performed, the system <NUM> is prepared and ready to deliver cooled RF ablation treatment to patient tissue. A clinician, e.g., a surgeon, inserts the probes 100a-d into the patient's tissue if they have not already done so, such that the probes 100a-d each target one or more specific nerves. Then, using the mapping between the RF channels 230a-d connected to the probes 100a-d and the pump assemblies 250a-d, each of the probes 100a-d may be independently controlled to deliver cooled RF ablation treatment. For instance, the pump assembly associated with each respective one of the probes 100a-d can be controlled to have different volumetric flow rates of cooling fluid, thereby altering the degree of cooling in the active tip <NUM> of each of the probes 100a-d. Similarly, the generator <NUM> can independently control the amount of RF energy delivered through each of the RF channels 230a-d to the probes 100a-d.

A method <NUM> of cooled RF ablation treatment including the sequential pump activation routine is shown in <FIG>. In step <NUM>, each of the probes 100a-d are connected to a respective one of the RF channels 230a-d using the electrical cable <NUM> and electrical connector <NUM> of the cable-tubing assembly <NUM> of each respective probe. In step <NUM>, each of the probes 100a-d are connected to a cooling fluid tube <NUM>, e.g., via the inlet fluid connector <NUM> of the fluid lumen <NUM> of the cable-tubing assembly <NUM> of each respective probe. Then, in step <NUM>, each cooling fluid tube <NUM> is inserted into a respective one of the pump assemblies 250a-d.

Next, the sequential pump activation routine is performed. In step <NUM>, each one of the pump assemblies 250a-d is activated individually in sequence, with an activation time delay N between the activation of each pump assembly. The temperature drop time delay of each of the RF channels 230a-d is measured in step <NUM>, where the temperature drop delay time is the time it takes for cooling fluid to reach the active tip as evidenced by a temperature drop measured by the thermocouple at the active tip. Then, in step <NUM>, the temperature drop time delay of each of the RF channels 230a-d is compared with the known pump assembly activation times. Using the comparison of step <NUM>, in step <NUM>, each of the RF channels 230a-d are mapped to their respective pump assemblies 250a-d based on which RF channel registered a temperature drop delay time soonest after the activation time of each respective one of the pump assemblies 250a-d. The mapping of the RF channels 230a-d and pump assemblies 250a-d is then displayed on the display <NUM>, e.g., as a graph.

After the sequential pump activation routine has been performed and the probes 100a-d have been mapped with their RF channels 230a-d and pump assemblies 250a-d, the system <NUM> is ready to deliver cooled RF ablation treatment to a patient. In step <NUM>, each of the probes 100a-d is inserted into the patient's target tissue for treatment. Then, in step <NUM>, each of the probes 100a-d are independently controlled by the generator <NUM> to deliver cooled RF ablation treatment by using the mapping generated in step <NUM> to individually control each one of the RF channels 230a-d and the pump assemblies 250a-d.

It should be understood that, although the embodiment illustrated in <FIG> and <FIG> illustrate a system <NUM> having four pump assemblies 250a-d, RF channels 230a-d and probes 100a-d, respectively, the present invention contemplates any number of pump assemblies, RF channels and probes for cooled RF ablation treatment. In particular, the present invention can include two or more pump assemblies, RF channels and probes for cooled RF ablation treatment. Moreover, as demonstrated by the daisy-chained probes <NUM> and <NUM> illustrated in <FIG> and described above, the present invention contemplates implementing multiple treatment probes per individual pump assembly and/or RF channel.

Claim 1:
A method to map active radiofrequency channels to respective pump assemblies for cooled radiofrequency ablation, the method comprising steps of:
providing a pump system (<NUM>) having a plurality of pump assemblies (250a-d), a radiofrequency generator unit (<NUM>), and a plurality of cooled radiofrequency probes (100a-d, <NUM>, <NUM>), wherein each cooled radiofrequency probe comprises a cable-tubing assembly (<NUM>) having a radiofrequency cable (<NUM>) and fluid tubing (<NUM>);
connecting the cable (<NUM>) of each cable-tubing assembly to an RF channel (230a-d) of the radiofrequency generator (<NUM>);
connecting the fluid tubing (<NUM>) of each cable-tubing assembly to a cooling fluid source;
activating each pump assembly of the plurality of pump assemblies individually in sequence;
mapping each cooled radiofrequency probe to a respective pump assembly connected thereto by measuring a temperature drop delay time for each cooled radio frequency probe, wherein the temperature drop delay time is the amount of time for cooling fluid to reach a tip of a respective one of the plurality of cooled radiofrequency ablation probes and initiate a temperature decrease at the tip of the respective one of the plurality of cooled radiofrequency ablation probes after activation of a first pump assembly of the plurality of pump assemblies; and
confirming the mapping of each cooled radiofrequency probe to the respective pump assembly by comparing the measured temperature drop delay time to an expected temperature drop delay time for each cooled radiofrequency probe, wherein expected temperature drop delay time is calculated using a recorded activation time of each cooled radiofrequency probe.