Patent Description:
The location of the medical tool in three-dimensional (<NUM>-D) space within patient anatomy is determined using electromagnetic navigation, which includes electromagnetic emitters and electromagnetic sensors on the tool to determine the tool's location. Based on the determined location, anatomical information of the patient is displayed to medical personnel. Dynamic maps of the patient anatomy (e.g., organs) are created to facilitate accurate determination of regions for ablation. Target ablation sites (i.e., regions of interest (ROI)) of an organ are identified by viewing the maps. Based on the identified ablation sites, an ablation procedure, which includes one or more ablations, is performed on the organ. <CIT> describes a system and method for multi-pole phase-shifted radio frequency application in which an electrosurgical generator is disclosed. The generator includes a power supply operable to generate a DC voltage and a multi-pole, phase-shifted, pulse-width and/or frequency modulated RF output stage coupled to the power supply. The RF output stage includes a plurality of dual-pole circuits, each of the plurality of dual-pole circuits including first and second pairs of switching components. The generator also includes a controller configured to drive the first and second pairs of switching components of each of the plurality of dual-pole circuits at a predetermined phase-shifted frequency. <CIT> discloses a signal generator, control circuitry, a plurality of non-linear amplifiers, and a processor. The signal generator is configured to generate an RF signal having a given frequency. The control circuitry is configured to set phases and amplitudes of a plurality of replicas of the RF signal generated by the signal generator. The plurality of non-linear amplifiers is configured to amplify the plurality of replicas of the RF signal, and to drive a respective plurality of ablation electrodes in a patient body with the amplified replicas. The processor is configured to receive a return signal, including a superposition of the replicas sensed by a patch electrode attached to the patient body, and to adaptively adjust the phases and amplitudes of the replicas in response to the return signal, by controlling the control circuitry.

The methods and systems conventionally used to identify ablation sites and perform the ablation procedure are time consuming (e.g., several hours) and rely on medical personnel with specific expertise and experience (typically requiring many hours of training). Successful treatment depends on accurate identification of ablation sites as well as an accurate assessment of the ablations performed on the organ.

Typically, ablation is performed by applying RF energy to an organ via multiple electrodes of a medical tool, such as a catheter. Radiofrequency (RF) generators are used to supply power to the electrodes of the medical tool for the ablation.

Conventional RF generators include linear power supplies which apply AC voltage to a transformer to change (e.g., step down) the voltage before being applied to a regulator to regulate the voltage. The components (e.g., transformer and regulator circuitry) of these conventional linear power supplies used to regulate the voltage are relatively large and generate more heat, resulting in lower energy efficiency. For example, conventional linear power supply generators have limited power yield (e.g., <NUM> watts of RF energy) and require high amounts of power to ablate.

In addition, for multi-catheter ablation, conventional RF generators control the power supplied to each electrode by driving the electrodes with signals having distinct frequencies, resulting in the presence of intermodulation distortion (IMD). IMD occurs when multiple signals of different frequencies are mixed together and additional signals are formed at frequencies that are not, in general, at harmonic frequencies of either signal. Accordingly, the IMD can cause the ablation signals to interfere with other signals, such as electrocardiogram (ECG) signals.

The invention provides a power generator according to claim <NUM>. Embodiment of the invention are defined in the dependent claims. The present application further provides a medical tool, such as a catheter, which includes a switched-mode power supply generator that operates on a single frequency. The power generator includes a plurality of switched-mode type amplifiers, each electrically connected to one of a plurality of ablation electrodes of a medical tool, such as a catheter. In contrast to conventional linear power supply RF generators, the switched-mode power supply RF generator converts the AC power directly into a DC voltage without the use of a transformer. Accordingly, the switched-mode power supply generator is smaller and more efficient (e.g., higher power conversion ratio) than conventional linear power supply generators used for RF ablation.

In addition, the switched-mode power supply generators disclosed herein control the supply power to the electrodes by an applied voltage and phase shift. That is, the amplitude is controlled for the signals output to each of the electrodes at the same frequency but with different phase shifts to control the power yielded by each electrode. Because the power is controlled using a single frequency, IMD is not present and the ablation signals do not interfere with other signals.

The present application discloses a system used to perform a medical ablation procedure. The system comprises a medical tool comprising a plurality of electrodes used to apply radio frequency (RF) energy for ablating tissue and a power generator a power supply configured to generate a DC voltage. The power generator comprises a power supply configured to generate a DC voltage, a phase shifter configured to shift signal transmission phase angles and a plurality of switched-mode amplifiers each electrically connected to a corresponding one of the electrodes and each configured to convert the DC voltage received from the power supply to an AC voltage signal provided to the corresponding electrode. The power generator also comprises a processor configured to control the power yielded by each electrode by controlling a phase shift of each AC voltage signal converted by the switched-mode amplifiers and controlling amplitude of each AC voltage signal convert by the switched-mode amplifiers.

The present application discloses a method of controlling power supplied for a medical ablation procedure. The method comprises supplying a DC voltage, converting, by each one of a plurality of switched-mode amplifiers, the DC voltage to a corresponding AC voltage signal, controlling a phase shift of each AC voltage signal converted by the switched-mode amplifiers and controlling an amplitude of each AC voltage signal convert by the switched-mode amplifiers. Although the method is not claimed, it may be used with the power generator of the present invention, and is considered useful for understanding the invention.

Referring now to <FIG>, an illustration of an example medical system <NUM> is shown that may be used to generate and display information <NUM> (e.g., a chart, anatomical models of a portion of a patient and signal information). Tools (i.e., medical tools), such as tool <NUM>, can be any tool which includes a catheter and a sheath (e.g., steerable and deflectable sheath) used for diagnostic or therapeutic treatment, such as for mapping electrical potentials in a heart <NUM> of a patient <NUM>. Alternatively, tools may be used, mutatis mutandis, for other therapeutic and/or diagnostic purposes of different portions of anatomy, such as in the heart, lungs or other body organs, such as the ear, nose, and throat (ENT). Tools may include, for example, probes, catheters, cutting tools and suction devices.

An operator <NUM> may insert the tool <NUM> into a portion of patient anatomy, such as the vascular system of the patient <NUM> so that a tip <NUM> of the tool <NUM> enters a chamber of the heart <NUM>. The control console <NUM> may use magnetic position sensing to determine position coordinates of the tool (e.g., coordinates of the tip <NUM>) in <NUM>-D space inside the heart <NUM>. As described in more detail below, magnetic position sensing is used to determine the location of both a catheter and a sheath of the tool <NUM> in <NUM>-D space. To determine the position coordinates, a driver circuit <NUM> in the control console <NUM> may drive, via connector, <NUM>, field generators <NUM> to generate magnetic fields within the anatomy of the patient <NUM>.

The field generators <NUM> include one or more emitter coils (not shown in <FIG>), placed at known positions external to the patient <NUM>, which are configured to generate magnetic fields in a predefined working volume that contains a portion of interest of the patient anatomy. Each of the emitting coils is driven by a different frequency to emit a constant magnetic field in <NUM>-D space. For example, in the example medical system <NUM> shown in <FIG>, one or more emitter coils can be placed below the torso of the patient <NUM> and each configured to generate magnetic fields in a predefined working volume that contains the heart <NUM> of the patient.

One or more electromagnetic sensors (i.e., magnetic field location sensors) <NUM> are disposed on a catheter of the tool <NUM> which generate electrical signals based on the amplitude and phase of the magnetic fields to determine the position of the catheter in <NUM>-D space. As described in more detail below, three separate electromagnetic sensors <NUM> are also disposed on a sheath of the tool <NUM> to accurately determine the location of the sheath using electromagnetic based navigation.

The signals are wirelessly communicated to the control console <NUM> via a wireless communication interface (e.g., interface <NUM> shown at <FIG>) at the tool <NUM> that may communicate with a corresponding input/output (I/O) interface <NUM> in the control console <NUM>. The wireless communication interface <NUM> and the I/O interface <NUM> may operate in accordance with any suitable wireless communication standard that is known in the art, such as for example, infrared (IR), radio frequency (RF), Bluetooth, one of the IEEE <NUM> family of standards (e.g., Wi-Fi), or the HiperLAN standard. The body surface electrodes <NUM> may include one or more wireless sensor nodes integrated on a flexible substrate. The one or more wireless sensor nodes may include a wireless transmit/receive unit (WTRU) enabling local digital signal processing, a radio link, and a miniaturized rechargeable battery, as described in more detail below.

The I/O interface <NUM> may enable the control console <NUM> to interact with the tool <NUM>, the body surface electrodes <NUM> and the position sensors (not shown). Based on the electrical impulses received from the body surface electrodes <NUM> and the electrical signals received from the tool <NUM> via the I/O interface <NUM> and other components of medical system <NUM>, the signal processor <NUM> may determine the locations of the catheter and sheath of the tool <NUM> in <NUM>-D space and generate the display information <NUM>, which may be shown on a display <NUM>.

The signal processor <NUM> is configured to process the signals to determine the position coordinates of both the catheter and sheath of the tool <NUM> in <NUM>-D space, including both location and orientation coordinates. Each of the magnetic field location sensors <NUM> transmit a signal to the control console <NUM> which indicates location coordinates of the tool <NUM> (e.g., location coordinates of the catheter and sheath of the tool <NUM>) in <NUM>-D space.

The signal processor <NUM> may be included in a general-purpose computer, with a suitable front end and interface circuits for receiving signals from the tool <NUM> and controlling the other components of the control console <NUM>. The signal processor <NUM> may be programmed, using software, to perform the functions that are described herein. The software may be downloaded to the control console <NUM> in electronic form, over a network, for example, or it may be provided on non-transitory tangible media, such as optical, magnetic or electronic memory media. Alternatively, some or all of the functions of the signal processor <NUM> may be performed by dedicated or programmable digital hardware components.

In the example shown at <FIG>, the control console <NUM> is connected, via cable <NUM>, to body surface electrodes <NUM>, each of which are attached to patient <NUM> using patches (e.g., indicated in <FIG> as circles around the electrodes <NUM>) that adhere to the skin of the patient. In addition or alternative to the patches, body surface electrodes <NUM> may also be positioned on the patient using articles worn by patient <NUM> which include the body surface electrodes <NUM> and may also include one or more position sensors (not shown) indicating the location of the worn article. For example, body surface electrodes <NUM> can be embedded in a vest that is configured to be worn by the patient <NUM>. During operation, the body surface electrodes <NUM> assist in providing a location of the tool (e.g., catheter) in <NUM>-D space by detecting electrical impulses generated by the polarization and depolarization of cardiac tissue and transmitting information to the control console <NUM>, via the cable <NUM>. The body surface electrodes <NUM> can be equipped with magnetic location tracking and can help identify and track the respiration cycle of the patient <NUM>.

Additionally or alternatively, the tool <NUM>, the body surface electrodes <NUM> and other sensors (not shown) may communicate with the control console <NUM> and one another via a wireless interface. For example, a wireless catheter, which is not physically connected to signal processing and/or computing apparatus, can communicate with the control console <NUM>. For example, a transmitter/receiver is attached to the catheter which communicates with a signal processing and/or computer apparatus using wireless communication methods, such as IR, RF, Bluetooth, or acoustic transmissions.

During the diagnostic treatment, the signal processor <NUM> may present the display information <NUM> and may store data representing the information <NUM> in a memory <NUM>. The memory <NUM> may include any suitable volatile and/or non-volatile memory, such as random access memory or a hard disk drive. The operator <NUM> may be able to manipulate the display information <NUM> using one or more input devices <NUM>. Alternatively, the medical system <NUM> may include a second operator that manipulates the control console <NUM> while the operator <NUM> manipulates the tool <NUM>. It should be noted that the configuration shown in <FIG> is exemplary. Any suitable configuration of the medical system <NUM> may be used and implemented.

<FIG> is a block diagram illustrating example components of a medical system <NUM> for use with embodiments described herein. As shown in <FIG>, the system <NUM> includes a medical tool <NUM>, a processing device <NUM>, a display device <NUM> and memory <NUM>. The medical tool <NUM> includes a catheter <NUM> and a sheath <NUM>. The catheter <NUM> is, for example, an ablation catheter used to ablate portions (e.g., tissue) in patient anatomy. The sheath <NUM> is, for example, steerable and deflectable to facilitate, for example, catheter access, stability, and tissue contact in target sites within patient anatomy. For example, during operation the catheter <NUM> is guided within patient anatomy (e.g., via a blood vessel) through the steerable and deflectable sheath <NUM> to a target location (e.g., a heart).

As shown in <FIG>, the processing device <NUM>, display device <NUM> and memory <NUM> are a part of an example computing device <NUM>. In some embodiments, the display device <NUM> may be separate from computing device <NUM>. Computing device <NUM> may also include an I/O interface, such as I/O interface <NUM> shown in <FIG>.

As shown in <FIG>, the example catheter <NUM> includes one or more sensors <NUM>, which include, for example, a magnetic field location sensor (e.g., sensor <NUM> in <FIG>) for providing location signals to indicate the <NUM>-D position coordinates of the catheter <NUM>. Likewise, the example sheath <NUM> includes one or more sensors <NUM>, which include, for example, a magnetic field location sensor for providing location signals to indicate the <NUM>-D position coordinates of the sheath <NUM>. In some procedures, one or more additional sensors <NUM> that are separate from the catheter <NUM>, as shown in example system <NUM>, are also used to provide location signals. In some embodiments, the catheter <NUM> also includes catheter electrodes <NUM> for mapping electrical potentials of a heart.

Sensors <NUM> (and <NUM>) may also include, for example, position sensors, pressure or force sensors, temperature sensors, impedance sensors or other sensors which provide ablation parameter signals indicating ablation parameters during the ablation of tissue of an organ. During the ablation procedure, RF generator <NUM> supplies high-frequency electrical energy, via catheter <NUM>, for ablating tissue at locations engaged by the catheter <NUM>. Sensors <NUM>, <NUM> sense ablation parameters (e.g., catheter <NUM> or sheath <NUM> position stability, temperature, ablation time, ablation power and ablation impedance) during the ablation procedure. Catheter <NUM> or sheath <NUM> may be in wired or wireless communication with processing device <NUM> to communicate the information acquired by sensors <NUM>, <NUM>.

The location signals are processed as location data and stored, for example, in memory <NUM>. The processing device <NUM> receives (e.g., reads from memory) location data corresponding to the location signals and generates mapping information, from the location data, for displaying one or more maps of an organ being ablated. The ablation parameter signals are processed as ablation parameter data and stored, for example, in memory <NUM>.

The processing device <NUM> receives the ablation parameter data corresponding to the ablation parameter signals and generates, from the ablation parameter data, first object information for displaying a first geometrical object having a first size which represents an estimated depth of the ablation of the organ. Processing device <NUM> also receives, from the ablation parameter data, second object information for displaying, concurrently with the first geometrical object, a second geometrical object having a second size which represents an estimated width of the ablation of the organ.

That is, the processing device <NUM> receives the ablation parameter data corresponding to ablation parameter signals acquired (e.g., via one or more sensors <NUM>) during the ablation procedure, determines from the ablation parameter data, estimated depth and width of an ablation, and generates, from the ablation parameter data, object information for displaying geometric objects to visually represent the estimated ablation depth and width. For example, using the ablation parameter data, processing device <NUM> executes a plurality of programmed instructions (e.g., lesion estimation and assessment algorithms) to determine an estimated depth and width of an ablation. The processing device <NUM> then generates first object information for displaying a first geometrical object having a first size which represents the estimated depth for an ablation of the heart. The processing device <NUM> also generates second object information for displaying, concurrently with the first geometrical object, a second geometrical object having a second size which represents the estimated width for the ablation of the heart.

The processing device <NUM> may also use the ablation parameter data to execute the programmed instructions to generate in-blood information for displaying an indicator on the map of an organ to visually represent a portion of the organ tissue which was not contacted during the ablation procedure. For example, during the ablation procedure, ablation parameter signals may be acquired, via sensors <NUM>, indicating whether the catheter <NUM> contacts the organ tissue at a portion of the heart. The ablation parameter signals may include, for example, information identifying the location of the catheter in <NUM>-D space at a particular time, information identifying a force applied by the catheter, impedance information and other information indicating whether the catheter <NUM> contacts the organ tissue at the portion of the organ.

The processing device <NUM> processes the ablation parameter signals as ablation parameter data and uses the ablation parameter data to determine whether the catheter <NUM> contacted the organ tissue at the portion of the organ. If no contact is determined between the ablation device and the heart tissue at the portion of the organ, the processing device <NUM> generates in-blood indicator information, indicating an in-blood ablation (as opposed to an ablation of the organ tissue).

Processing device <NUM> drives display device <NUM>, using the mapping information, to display the map of the organ on display device <NUM>. Processing device <NUM> also drives display device <NUM>, using the first object information and the second object information, to display the first and second geometrical objects at the display device <NUM> as well as any determined in-blood indicators.

Display device <NUM> may include one or more displays each configured to display one or more maps of the organ. For example, display device <NUM> is configured to display maps representing a spatio-temporal manifestation of an organ (e.g., a heart) as well as geometrical objects which represent estimated ablation depths and widths. Display device <NUM> may be in wired or wireless communication with processing device <NUM>. In some embodiments, display device may be separate from computing device <NUM>.

Memory <NUM> includes, for example, volatile and non-volatile memory, such as random access memory (RAM), dynamic RAM, or a cache. Memory <NUM> also includes, for example, storage, such as, fixed storage (e.g., a hard disk drive and a solid state drive) and removable storage (e.g., an optical disk and a flash drive).

As shown in <FIG>, the system <NUM> also includes switch mode power supply generator <NUM>. The generator <NUM> is for example, in communication (e.g., wired or wireless communication) with computing device <NUM> (e.g., processing device <NUM> of computing device <NUM>). Generator <NUM> is configured to supply power to each of electrodes <NUM> for performing ablation. Generator <NUM> is described in more detail below with regard to <FIG>.

<FIG> is a diagram of components of an example medical system <NUM> for use during an ablation procedure. As shown in <FIG>, the medical system <NUM> includes switch mode power supply generator <NUM> and catheter <NUM>. The switch mode power supply generator <NUM> includes power supply (e.g., battery) <NUM>, processor <NUM>, phase shifter <NUM>, which can be implemented as hardware (e.g., voltage control phase shifter), software or a combination of hardware and software to shift transmission phase angles of signals, and amplifiers <NUM>. Each one of amplifiers <NUM> is electrically connected to one of the electrodes <NUM> of catheter <NUM>.

Processor <NUM> is configured to control the amount of power yielded by each electrode <NUM> via the phase shifter <NUM> and amplifiers <NUM>. Processor <NUM> communicates with each amplifier <NUM> to control the amplitude of the output signal and the phase in which the signal is provided to each electrode <NUM>. The signals for each electrode <NUM> are sent using the same frequency, but at different phases. That is, processor <NUM> controls the phase shift of the different signals such that each signal to one of the electrodes is identified via its corresponding phase. For example, if the catheter <NUM> includes <NUM> electrodes, then <NUM> different signals are sent using the same frequency (e.g., <NUM>) but at different phases. Because power is controlled using a single frequency, intermodulation is not present and the ablation signals do not interfere with the ECG signals.

<FIG> is a diagram illustrating example components of an amplifier <NUM> shown in <FIG>. As shown in <FIG>, the amplifier <NUM> includes a Buck Boost converter <NUM>, two pairs of N-channel metal-oxide-semiconductor field-effect (MOSFET) transistors <NUM> and filter <NUM>.

The Buck Boost converter <NUM> is a DC-to-DC power converter, which is controlled by processor <NUM> to step up and step down an input DC voltage and facilitate power control. The Buck Boost converter <NUM> receives a DC voltage signal from power supply <NUM> and regulates the DC voltage provided to the MOSFET transistors <NUM>.

The N-channel MOSFET transistors <NUM> are controlled, by processor <NUM>, to switch between different states to convert the DC signal into amplitude pulses. These pulses are amplified via transformer <NUM> to provide the digital AC voltage signal <NUM> in the form of square wave (e.g., at a frequency of <NUM>).

Although the transistors <NUM> shown in <FIG> include <NUM> pairs of N-channel MOSFET transistors, the number and type of transistors shown in <FIG> is merely an example. Amplifiers can also include other types of semiconductors or switching components to implement features of the present disclosure. The transformer <NUM> shown in <FIG> includes a turn ratio (number of primary windings Np/number of secondary windings Ns) equal to <NUM>. The turn ratio is merely an example. Amplifiers can include transformers having different turn ratios to implement the features disclosed herein. Additionally, although MOSFET transistors are set forth in the example of <FIG>, IGBT transistors may be utilized in accordance with the present teachings.

The filter <NUM> is, for example, a low pass filter which is configured to convert the AC voltage signal <NUM> to an analog AC voltage signal <NUM> delivered to one of the electrodes <NUM> shown in <FIG>. As shown in <FIG>, the square wave AC voltage signal <NUM>, having a frequency of <NUM>, is converted to the analog sinusoidal AC voltage signal <NUM>, having the frequency of <NUM>, which is delivered to one of the electrodes <NUM>. The filter <NUM> is, for example, a low pass filter such as a Butterworth filter and may include an inductor, a capacitor or other electrical components which can be used to attenuate the high frequency switching components and pass the frequency band (e.g., band which includes <NUM>).

Because the switched-mode power supply RF generator <NUM> includes a plurality of switched-mode type amplifiers <NUM>, the switched-mode power supply generator <NUM> is smaller and more efficient (e.g., higher power conversion ratio) than conventional linear power supply generators used for RF ablation.

In addition, because the switched-mode power supply RF generator <NUM> controls the supply power to the electrodes by an applied voltage and phase shift, the power supplied to each of the electrodes <NUM> is controlled using a single frequency. Accordingly, the power supply signals provided to each of the electrodes <NUM> do not interfere with other signals (e.g., ECG signals) because the IMD that is present with conventional power supply generators is avoided.

It should be noted that although switched-mode amplifiers <NUM> are set in <FIG>, one or more linear power amplifiers can be utilized in an alternative embodiment. Such operational amplifiers are well known to those of skill in the art.

<FIG> is a flow diagram illustrating an example method <NUM> of controlling power supplied for a medical ablation procedure.

As shown at block <NUM>, the method <NUM> includes supplying a DC voltage. For example, the DC voltage is supplied via a battery of a RF switched mode power supply generator.

As shown at block <NUM>, the method <NUM> includes converting, via each of a plurality of switched-mode amplifiers, the DC voltage to a corresponding AC voltage signal.

As shown at block <NUM>, the method <NUM> includes controlling a phase shift and amplitude of each AC voltage signal converted by the switched-mode amplifiers.

The methods provided herein may be implemented in a general purpose computer, a processor, or a processor core. Suitable processors include, by way of example, a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), and/or a state machine. Such processors can be manufactured by configuring a manufacturing process using the results of processed hardware description language (HDL) instructions and other intermediary data including netlists (such instructions capable of being stored on a computer readable media). The results of such processing can be maskworks that are then used in a semiconductor manufacturing process to manufacture a processor which implements features of the disclosure.

The methods or flow charts provided herein can be implemented in a computer program, software, or firmware incorporated in a non-transitory computer-readable storage medium for execution by a general purpose computer or a processor. Examples of non-transitory computer-readable storage mediums include a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs).

Claim 1:
A power generator (<NUM>) for use with a medical tool (<NUM>) used to perform a medical ablation procedure comprising:
a power supply (<NUM>) configured to generate a DC voltage;
a phase shifter (<NUM>) configured to shift signal transmission phase angles;
a plurality of switched-mode amplifiers (<NUM>) each comprising N-channel metal-oxide-semiconductor field-effect (MOSFET) transistors (<NUM>), and each configured to convert the DC voltage received from the power supply to an AC voltage signal; and
a processor (<NUM>) configured to control:
the phase shifter (<NUM>) to control a phase shift of each AC voltage signal converted by the switched-mode amplifiers;
an amplitude of each AC voltage signal converted by the switched-mode amplifiers; and
the MOSFET transistors to switch between different states to convert the DC voltage into amplitude pulses.