Reducing IEGM Hazards in Time-Division Multiplexed Systems.

Abstract

In one embodiment, a medical system includes a catheter interface having electrode wires configured to be electrically connected to respective electrodes of a catheter, and a signal generator configured to generate signal pulses, each of the signal pulses including a carrier frequency and having a non-rectangular signal envelope, and the signal generator configured to time-multiplex the signal pulses among the electrode wires.

Description

[Technical Field]

[0001] TECHNICAL FIELD The present disclosure relates to medical systems, and in particular, but not exclusively, to signal generation. [Background technology]

[0002] A wide variety of medical procedures involve the placement of probes, such as catheters, inside a patient's body. One medical procedure in which these types of probes or catheters have proven extremely useful is in the treatment of cardiac arrhythmias. Cardiac arrhythmias and atrial fibrillation in particular remain common and dangerous medical conditions, especially in the elderly population.

[0003] Diagnosis and treatment of cardiac arrhythmias include mapping the electrical properties of cardiac tissue, particularly the endocardium and cardiac volumes, and selectively ablating cardiac tissue through the application of energy. Catheters are inserted into and optionally around cardiac chambers during such procedures. In most procedures, multiple catheters are inserted into the patient. Catheters may include mapping catheters, ablation catheters, temperature-sensing catheters, and image-sensing catheters. Some catheters are dedicated to placement in specific parts of the anatomy, such as the coronary sinus, esophagus, atria, and ventricles. Catheters have multiple electrical channels, with some having more channels than others depending on the number of sensors and electrodes included in each catheter. The number and type of catheters depend on the procedure and the physician's preferred workflow. [Brief explanation of the drawings]

[0004] The present disclosure will be understood from the following detailed description taken in conjunction with the accompanying drawings. [Figure 1] 1 is a pictorial illustration of a catheter-based electrophysiological mapping and ablation system constructed and operative in accordance with an exemplary mode of the present disclosure; [Figure 2]FIG. 2 is a block diagram of a patient interface unit in the system of FIG. 1. [Figure 3] 2 is a flow chart including steps in a method of operation of the system of FIG. 1; [Figure 4] 2 is an exemplary signal pulse for use in the system of FIG. 1; DETAILED DESCRIPTION OF THE INVENTION

[0005] overview One method of tracking catheter position is based on catheter electrodes transmitting position signals at different natural frequencies, which can be detected by body surface patches and processed by a processor to calculate the position of the catheter and / or electrodes based, for example, on the distribution of current or impedance across the body surface patches.

[0006] In current-generation catheters, the number of electrodes is rapidly increasing. This increase leads to an increase in the number of different frequency position signals, an increase in the frequency band to accommodate all the unique frequencies, and an increase in the number of frequency generators to generate these signals. To solve this problem, signals may be transmitted using time division multiplexing (TDM), whereby the same signal frequency may be used for several electrodes, but the signal is directed to different electrodes during different periods of time (e.g., transmitting from electrode 1 during period A, transmitting from electrode 2 during period B, etc.). In this way, electrodes may be divided into groups transmitting at the same group frequency, with one electrode per group transmitting at any one time. In this way, the number of different frequencies and frequency generators is reduced. Each TDM signal per period is typically a signal pulse with a rectangular envelope.

[0007] The same electrodes that transmit the position signal also detect the intracardiac electrogram (IEGM). The transmitted TDM signal pulse induces artifacts (e.g., signal spikes) in the detected IEGM corresponding to the beginning and end of the TDM burst due to the nonlinear surface impedance between the metal electrode and the blood pool. A direct current (DC) signal component is also imposed on the IEGM signal throughout the TDM signal pulse.

[0008] Thus, according to an exemplary mode of the present disclosure, TDM signal pulses are generated with a non-rectangular signal envelope, thereby reducing or eliminating signal spikes in the detected IEGMs. The signal pulses are time multiplexed among electrode wires to different catheter electrodes.

[0009] The non-rectangular signal envelope may be generated by gradually increasing the peak-to-peak amplitude of the envelope over time to a maximum peak-to-peak amplitude and then gradually decreasing the envelope over time to zero (or other minimum) peak-to-peak amplitude after a given period of time. The gradual increase in the peak-to-peak amplitude of the envelope may be based on an error function (ERF) or other suitable function. The gradual decrease in the peak-to-peak amplitude of the envelope may be based on a complimentary error function (ERFC) or other suitable function.

[0010] In some exemplary modes, the digital signal pulse representation is retrieved from memory by a processor, such as a field-programmable gate array (FPGA), which provides the retrieved digital signal pulse representation to a digital-to-analog converter (DAC), which converts the digital signal pulse representation to an analog signal including signal pulses with non-rectangular envelopes.

[0011] The direct current (DC) signal component imposed on the IEGM signal can be reduced or eliminated by generating signal pulses such that the maximum current density on the catheter electrode is less than a threshold current density. The threshold current density can be determined by adjusting the amplitude of the signal pulse and examining the IEGM signal until the DC signal component is eliminated or sufficiently reduced. For iridium-platinum electrodes, the threshold current density is approximately 0.44 mA / mm 2 It is estimated that.

[0012] System Description Reference is made to FIG. 1 , which is a pictorial illustration of a catheter-based electrophysiological mapping and ablation system 10 constructed and operative in accordance with an exemplary mode of the present disclosure. The system 10 includes multiple catheters that are percutaneously inserted by a physician 24 through a patient's vascular system and into a chamber or vasculature of the heart 12. Typically, a delivery sheath catheter is inserted into the left or right atrium near a desired location in the heart 12. One or more catheters can then be inserted into the delivery sheath catheter to reach a desired location within the heart 12. The multiple catheters may include catheters dedicated to sensing intracardiac electrogram (IEGM) signals, catheters dedicated to ablation, and / or catheters dedicated to both sensing and ablation. An exemplary catheter 14 configured for sensing IEGMs is illustrated herein. To sense a target site in the heart 12, the physician 24 can place a distal tip 28 of the catheter 14 in contact with the heart wall. For ablation, the physician 24 can similarly place a distal end of an ablation catheter in contact with a target site for tissue ablation.

[0013] Catheter 14 is an exemplary catheter that includes one, and preferably multiple, electrodes 26 optionally distributed across multiple splines 22 at distal tip 28 and configured to sense IEGM signals. Catheter 14 may additionally include a position sensor 29 embedded in or near distal tip 28 to track the position and orientation of distal tip 28. Position sensor 29 may be a magnetic-based position sensor including three magnetic coils that sense three-dimensional (3D) position and orientation (including roll).

[0014] The magnetic-based position sensor 29 may be operated in conjunction with a location pad 25 that includes a plurality of magnetic coils 32 configured to generate a magnetic field within a predetermined working volume. The real-time position of the distal tip 28 of the catheter 14 may be tracked based on the magnetic fields generated by the location pad 25 and sensed by the magnetic-based position sensor 29. Details of magnetic-based position sensing technology are described in U.S. Patent Nos. 5,5391,199; 5,443,489; 5,558,091; 6,172,499; 6,239,724; 6,332,089; 6,484,118; 6,618,612; 6,690,963; 6,788,967; and 6,892,091.

[0015] System 10 includes one or more electrode (body surface) patches 38 positioned in skin contact with patient 23 to establish a position reference for location pads 25 and impedance-based tracking of electrodes 26. For impedance-based tracking, current is directed to electrodes 26 and sensed at electrode body surface patches 38, thereby allowing the position of each electrode to be triangulated (or otherwise calculated) via electrode patches 38. Details of impedance-based position tracking techniques are described in U.S. Patent Nos. 7,536,218; 7,756,576; 7,848,787; 7,869,865; and 8,456,182.

[0016] Recorder 11 records and displays electrograms 21 captured by body surface ECG electrodes 18 and intracardiac electrograms (IEGMs) captured by electrodes 26 on catheter 14. Recorder 11 may include pacing capability for pacing the cardiac rhythm and / or may be electrically connected to a stand-alone pacer.

[0017] The system 10 may include an ablation energy generator 50 adapted to conduct ablation energy to one or more electrodes at the distal tip of a catheter configured for ablation. The energy generated by the ablation energy generator 50 may include, but is not limited to, radiofrequency (RF) energy, or pulsed-field ablation (PFA) energy, including unipolar or bipolar high-voltage DC pulses, such as may be used to perform irreversible electroporation (IRE), or a combination thereof.

[0018] The Patient Interface Unit (PIU) 30 is an interface configured to establish electrical communication between the catheters, other electrophysiology equipment, a power source, and a workstation 55 for controlling the operation of the system 10. The electrophysiology equipment of the system 10 may include, for example, multiple catheters, location pads 25, body surface ECG electrodes 18, electrode patches 38, an ablation energy generator 50, and a recorder 11. Optionally and preferably, the PIU 30 additionally includes processing capabilities for implementing real-time calculations of catheter position and performing ECG calculations.

[0019] The workstation 55 includes a processor unit having memory, a memory or storage device having appropriate operating software stored therein, and user interface functionality. The workstation 55 may optionally provide multiple functions, including (1) modeling the endocardial anatomical structure in three dimensions (3D) and rendering the model or anatomical map 20 for display on the display device 27, (2) displaying activation sequences (or other data) compiled from recorded electrograms 21 with representative visual indicators or images superimposed on the rendered anatomical map 20 on the display device 27, (3) displaying the real-time position and orientation of multiple catheters within the cardiac chambers, and (4) displaying sites of interest, such as locations where ablation energy has been applied, on the display device 27. One commercially available product embodying elements of the system 10 is available as the CARTO™ 3 system, commercially available from Biosense Webster, Inc., 31A Technology Drive, Irvine, CA 92618.

[0020] Reference is now made to Figure 2, which is a block diagram of the patient interface unit 30 in the system 10 of Figure 1. The PIU 30 includes a signal generator 40, a position tracking system 42, a signal processor 44, and a catheter interface 46. The catheter interface 46 includes electrode wires 58 configured to be electrically connected to respective electrodes 26 of the catheter 14 via one or more suitable connectors.

[0021] Signal generator 40 includes memory 48, processing circuitry 52 (such as an FPGA or suitable application-specific integrated circuit (ASIC) or microprocessor programmed with suitable software), digital-to-analog converter 54, and switching circuitry 56. Signal generator 40 is configured to generate time-multiplexed signal pulses to electrodes 26 of catheter 14 via electrode wires 58 of catheter interface 46, as described in more detail below with reference to FIG.

[0022] 2 shows a catheter 14 configured to be inserted into a body part (e.g., heart 12) of a living body (e.g., patient 23, shown as a block in FIG. 2 for simplicity). Electrodes 26 of catheter 14 are configured to emit position signals in response to time-multiplexed signal pulses generated by a signal generating device 40.

[0023] 1 , electrode patches 38 (or body surface electrodes) are applied to a body surface (e.g., the chest and / or back) of a living body (e.g., patient 23) and are configured to detect location signals emitted by electrodes 26 of catheter 14. Position tracking system 42 is configured to calculate the location of catheter 14 (and / or electrodes 26 of catheter 14) in response to the detected location signals, e.g., in response to the distribution of current and / or impedance across electrode patches 38. Position tracking system 42 identifies the electrodes 26 transmitting one of the location signals based on the frequency of transmission of the detected location signals and the period during which the location signals are detected according to the time schedule of the TDM used in system 10.

[0024] The signal processing unit 44 is configured to receive electroanatomical signals from the electrodes 26 via the electrode wires 58 and from the body surface ECG electrodes 18, and to process the received electroanatomical signals (e.g., by filtering the signals and / or calculating annotation times).

[0025] Referring now to FIG. 3, which is a flowchart 60 including steps in a method of operating the system 10 of FIG. 1 , the signal generator 40 is configured to generate signal pulses (block 62). Each of the signal pulses includes a carrier frequency and has a non-rectangular signal envelope, which will be described in more detail with reference to FIG. 4 . The carrier frequency may have any suitable value, for example, within the range of 50-250 kHz or within the range of 100-110 kHz. The signal generator 40 is configured to time-multiplex the signal pulses between the electrode lines 58 (block 64), for example, using a switching circuit 56 that switches the output of the digital-to-analog converter 54 to different electrode lines 58 according to a time-division multiplexing schedule. For example, during period A, the output of the digital-to-analog converter 54 is connected to electrode line X, and during period B, the output of the digital-to-analog converter 54 is connected to electrode line Y, with an entire signal pulse being generated by the digital-to-analog converter 54 during each period.

[0026] Referring now to Figure 4, this is an exemplary signal pulse 80 for use in the system 10 of Figure 1. The signal pulse 80 includes a non-rectangular signal envelope 82 and a carrier frequency 84.

[0027] The signal generating device 40 is configured to generate a non-rectangular signal envelope 82 in which the peak-to-peak amplitude of the envelope 82 gradually increases 86 over time (t) to a maximum peak-to-peak amplitude (P), and then, after a given period of time, the envelope 82 gradually decreases 88 over time (t) to a peak-to-peak amplitude of zero (or a given peak-to-peak amplitude). As used herein and in the claims, the terms "increase" and "decrease" are defined as an increase or decrease of the non-rectangular signal envelope 82 that occurs over time. In other words, the non-rectangular signal envelope 82 increases over time from a peak-to-peak value of zero to a maximum peak-to-peak value P, and then decreases over time to a peak-to-peak value of zero, as the non-rectangular signal envelope 82 reaches a plateau. The non-rectangular signal envelope 82 may have any suitable width W fFor example, the non-rectangular signal envelope 82 may have a width in the range of 10 to 100 milliseconds, or in the range of 40 to 50 milliseconds. i and gradually decreasing width W of 88 r may have any suitable width. For example, W i and / or W r may have a width in the range of 50 to 500 microseconds, or in the range of 150 to 250 microseconds.

[0028] The increase 86 in the peak-to-peak amplitude of the envelope 82 may be based on an error function (ERF) or any suitable function or shape. The decrease 88 in the envelope 82 may be based on a complementary error function (ERFC) or any suitable function or shape.

[0029] The ERF function is defined as follows:

[0030]

number

[0031] Referring again to FIG. 3 , memory 48 is configured to store a digital signal pulse representation, e.g., a point-by-point representation of signal pulse 80 of FIG. 4 . 52 is configured to retrieve the digital signal pulse representation from memory 48 (block 66) and provide the digital signal pulse representation to digital-to-analog converter 54 (block 68), which is configured to convert the digital signal pulse representation to an analog signal including one of signal pulses 80 (block 70). The steps of blocks 68 and 70 are repeated to generate a series of signal pulses 80 for output to catheter 14. The output of digital-to-analog converter 54 is connected to switching circuitry 56, which is controlled to connect the output of digital-to-analog converter 54 to a selected one of electrode wires 58 in any TDM period according to the TDM schedule described above. Switching circuitry 56 may be controlled by processing circuitry 52 or any suitable processor. Processing circuitry 52 also coordinates the timing of the generation of signal pulses 80 according to a TDM schedule, so that an entire signal pulse 80 is transmitted by each electrode 26 in each TDM period.

[0032] In some exemplary modes, the signal generator 40 is configured to generate a signal pulse 80 having a maximum peak-to-peak amplitude P such that the signal pulse 80 results in a maximum current density on the electrode 26 that is less than a given current density. By way of example, for an iridium-platinum electrode, the current density is 0.44 mA / mm 2 It can be set to be less than

[0033] In practice, some or all of the functionality of processing circuitry 52 may be combined within a single physical component, or alternatively, may be implemented using multiple physical components. These physical components may include hardwired or programmable devices, or a combination of the two. In some examples, at least some of the functionality of processing circuitry 52 may be performed by a programmable processor under the control of suitable software. This software may be downloaded to the device in electronic form, for example, over a network. Alternatively or additionally, this software may be stored on a tangible, non-transitory, computer-readable storage medium, such as optical, magnetic, or electronic memory.

[0034] As used herein, the terms "about" or "approximately" in connection with any numerical value or range of values ​​indicates a suitable dimensional tolerance that enables a portion of a component or a collection of components to function for its intended purpose as described herein. More specifically, "about" or "approximately" may refer to a range of values ​​of ±20% of the recited value; for example, "about 90%" may refer to a range of values ​​of 72% to 108%. [Example]

[0035] Example 1: A medical system comprising: a catheter interface comprising electrode wires configured to be electrically connected to respective electrodes of a catheter; and a signal generator configured to generate signal pulses, each of the signal pulses including a carrier frequency and having a non-rectangular signal envelope, the signal generator configured to time multiplex the signal pulses between the electrode wires.

[0036] Example 2: The system of Example 1, further comprising: a catheter configured to be inserted into a body part of a living organism, the electrodes configured to emit position signals in response to the time-multiplexed signal pulses; body surface electrodes applied to a body surface of the living organism and configured to detect the position signals; and a position tracking system configured to calculate the position of the catheter in response to the detected position signals.

[0037] Example 3: The system of Example 1, further comprising a signal processing device configured to receive electroanatomical signals from the electrodes via the electrode wires and process the received electroanatomical signals.

[0038] Example 4: The system of example 1, wherein the signal generator is configured to generate a non-rectangular signal envelope with a peak-to-peak amplitude of the envelope gradually increasing over time to a maximum peak-to-peak amplitude.

[0039] Example 5: The system of Example 1, wherein the signal generator is configured to generate a non-rectangular signal envelope in which the peak-to-peak amplitude of the envelope gradually increases over time to a maximum peak-to-peak amplitude, and then, after a given period of time, the envelope gradually decreases over time to a peak-to-peak amplitude of zero.

[0040] Example 6: The system of Example 5, wherein the gradual increase in peak-to-peak amplitude of the envelope is based on an error function (ERF).

[0041] Example 7: The system of example 6, wherein the tapering in the envelope is based on a complementary error function (ERFC).

[0042] Example 8: The system of Example 1, further comprising a memory configured to store a digital signal pulse representation, wherein the signal generating device comprises a processing circuit and a digital-to-analog converter, wherein the processing circuit is configured to retrieve the digital signal pulse representation from the memory and provide the digital signal pulse representation to the digital-to-analog converter, and wherein the digital-to-analog converter is configured to convert the digital signal pulse representation into an analog signal including one of the signal pulses.

[0043] Example 9: The system of Example 1, wherein the signal generating device is configured to generate signal pulses having a maximum peak-to-peak amplitude such that the maximum current density on the electrodes is less than a given current density.

[0044] Example 10: A medical system comprising: a catheter interface having electrode wires configured to be electrically connected to respective electrodes of a catheter; and a signal generator configured to generate signal pulses and time-multiplex the signal pulses among the electrode wires, wherein the signal generator is configured to generate signal pulses having a maximum peak-to-peak amplitude such that a maximum current density on the electrodes is less than a given current density.

[0045] Example 11: A computer-implemented method, comprising: generating signal pulses, each of the signal pulses including a carrier frequency and having a non-rectangular signal envelope; and time-multiplexing the signal pulses among electrode wires configured to be electrically connected to respective electrodes of a catheter.

[0046] Example 12: The method of Example 11, further comprising: electrodes emitting position signals in response to the time-multiplexed signal pulses; body surface electrodes applied to the body surface of the living body detecting the position signals; and calculating the position of the catheter in response to the detected position signals.

[0047] Example 13: The method of Example 11, further comprising receiving electroanatomical signals from the electrodes via electrode wires and processing the received electroanatomical signals.

[0048] Example 14: The method of example 11, further comprising generating a non-rectangular signal envelope in which the peak-to-peak amplitude of the envelope gradually increases over time to a maximum peak-to-peak amplitude.

[0049] Example 15: The method of Example 11, further comprising generating a non-rectangular signal envelope in which the peak-to-peak amplitude of the envelope gradually increases over time to a maximum peak-to-peak amplitude, and then, after a given period of time, the envelope gradually decreases over time to a peak-to-peak amplitude of zero.

[0050] Example 16: The method described in Example 15, wherein the increase in peak-to-peak amplitude of the envelope is based on an error function (ERF).

[0051] Example 17: The method of Example 16, wherein the tapering in the envelope is based on a complementary error function (ERFC).

[0052] Example 18: The method of Example 11, further comprising: storing a digital signal pulse representation; retrieving the stored digital signal pulse representation; and converting the digital signal pulse representation into an analog signal including one of the signal pulses.

[0053] Example 19: The method of example 11, wherein generating includes generating a signal pulse having a maximum peak-to-peak amplitude such that a maximum current density on the electrode is less than a given current density.

[0054] Example 20: A computer-implemented method comprising: generating signal pulses; and time-multiplexing the signal pulses between electrode wires configured to be electrically connected to respective electrodes of a catheter, wherein the generating comprises generating signal pulses having a maximum peak-to-peak amplitude such that a maximum current density on the electrodes is less than a given current density.

[0055] Various features of the present disclosure that are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the present disclosure that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

[0056] The above-described embodiments are cited by way of example, and the present disclosure is not limited to what has been particularly shown and described above. Rather, the scope of the present disclosure includes both combinations and subcombinations of the various features described above, as well as variations and modifications thereof not disclosed in the prior art that would occur to one skilled in the art upon reading the above description.

[0057] [Embodiment] (1) A health care system: a catheter interface including electrode wires configured to be electrically connected to respective electrodes of the catheter; a signal generator configured to generate signal pulses, each of the signal pulses including a carrier frequency and having a non-rectangular signal envelope, the signal generator configured to time-multiplex the signal pulses among the electrode wires. (2) the catheter configured to be inserted into a body part of a living organism, the electrodes configured to emit position signals in response to the time-multiplexed signal pulses; a body surface electrode applied to a body surface of the living body and configured to detect the position signal; 2. The system of claim 1, further comprising: a position tracking system configured to calculate the position of the catheter in response to the detected position signal. (3) The signal processing device further includes: receiving electroanatomical signals from the electrodes via the electrode wires; 2. The system of claim 1, configured to: (4) The system of embodiment 1, wherein the signal generator is configured to generate the non-rectangular signal envelope such that the peak-to-peak amplitude of the envelope gradually increases over time to a maximum peak-to-peak amplitude. (5) The system of embodiment 1, wherein the signal generator is configured to generate the non-rectangular signal envelope such that the peak-to-peak amplitude of the envelope gradually increases over time to a maximum peak-to-peak amplitude and then, after a given period of time, the envelope gradually decreases over time to a peak-to-peak amplitude of zero.

[0058] (6) The system of embodiment 5, wherein the gradual increase in the peak-to-peak amplitude of the envelope is based on an error function (ERF). (7) The system of embodiment 6, wherein the gradual decrease in the envelope is based on a complementary error function (ERFC). (8) The system of embodiment 1, further comprising a memory configured to store a digital signal pulse representation, wherein the signal generating device comprises a processing circuit and a digital-to-analog converter, the processing circuit configured to retrieve the digital signal pulse representation from the memory and provide the digital signal pulse representation to the digital-to-analog converter, and the digital-to-analog converter configured to convert the digital signal pulse representation into an analog signal including one of the signal pulses. (9) The system of embodiment 1, wherein the signal generating device is configured to generate the signal pulses having a maximum peak-to-peak amplitude such that the maximum current density on the electrodes is less than a given current density. (10) A health care system, a catheter interface including electrode wires configured to be electrically connected to respective electrodes of the catheter; a signal generator configured to generate signal pulses and time-multiplex the signal pulses among the electrode wires, the signal generator configured to generate the signal pulses having a maximum peak-to-peak amplitude such that a maximum current density on the electrodes is less than a given current density.

[0059] (11) A computer-implemented method comprising: generating signal pulses, each of the signal pulses including a carrier frequency and having a non-rectangular signal envelope; and time multiplexing the signal pulses among electrode wires configured to be electrically connected to respective electrodes of the catheter. (12) the electrodes emit position signals in response to the time-multiplexed signal pulses; detecting the position signal using body surface electrodes applied to a body surface of the living body; 12. The method of claim 11, further comprising: calculating a position of the catheter in response to the detected position signal. (13) receiving an electroanatomical signal from the electrode via the electrode wire; 12. The method of claim 11, further comprising processing the received electroanatomical signals. (14) The method of claim 11, further comprising generating the non-rectangular signal envelope such that the peak-to-peak amplitude of the envelope gradually increases over time to a maximum peak-to-peak amplitude. (15) The method of claim 11, further comprising generating the non-rectangular signal envelope such that the peak-to-peak amplitude of the envelope gradually increases over time to a maximum peak-to-peak amplitude, and then, after a given period of time, the envelope gradually decreases over time to a peak-to-peak amplitude of zero.

[0060] (16) The method of claim 15, wherein the gradual increase in the peak-to-peak amplitude of the envelope is based on an error function (ERF). (17) The method of claim 16, wherein the tapering in the envelope is based on a complementary error function (ERFC). (18) storing the digital signal pulse representation; Retrieving the stored digital signal pulse representation; and 12. The method of claim 11, further comprising converting the digital signal pulse representation to an analog signal including one of the signal pulses. 19. The method of claim 11, wherein the generating includes generating the signal pulses having a maximum peak-to-peak amplitude such that a maximum current density on the electrodes is less than a given current density. (20) A computer-implemented method comprising: generating a signal pulse; and time-multiplexing the signal pulses between electrode wires configured to be electrically connected to respective electrodes of a catheter, wherein the generating includes generating the signal pulses having a maximum peak-to-peak amplitude such that a maximum current density on the electrodes is less than a given current density.

Claims

1. 1. A healthcare system comprising: a catheter interface including electrode wires configured to be electrically connected to respective electrodes of the catheter; a signal generator configured to generate signal pulses, each of the signal pulses including a carrier frequency and having a non-rectangular signal envelope, the signal generator configured to time-multiplex the signal pulses among the electrode wires.

2. the catheter configured to be inserted into a body part of a living organism, the electrodes configured to emit position signals in response to the time-multiplexed signal pulses; a body surface electrode applied to a body surface of the living body and configured to detect the position signal; The system of claim 1 , further comprising: a position tracking system configured to calculate a position of the catheter in response to the detected position signals.

3. The signal processing device further includes: receiving electroanatomical signals from the electrodes via the electrode wires; and processing the received electroanatomical signals.

4. 2. The system of claim 1, wherein the signal generator is configured to generate the non-rectangular signal envelope such that the peak-to-peak amplitude of the envelope gradually increases over time up to a maximum peak-to-peak amplitude.

5. 2. The system of claim 1, wherein the signal generator is configured to generate the non-rectangular signal envelope such that the peak-to-peak amplitude of the envelope gradually increases over time to a maximum peak-to-peak amplitude and then, after a given period of time, the envelope gradually decreases over time to a peak-to-peak amplitude of zero.

6. The system of claim 5 , wherein the gradual increase in the peak-to-peak amplitude of the envelope is based on an error function (ERF).

7. The system of claim 6 , wherein the tapering in the envelope is based on a complementary error function (ERFC).

8. 10. The system of claim 1, further comprising a memory configured to store a digital signal pulse representation, wherein the signal generator comprises a processing circuit and a digital-to-analog converter, the processing circuit configured to retrieve the digital signal pulse representation from the memory and provide the digital signal pulse representation to the digital-to-analog converter, the digital-to-analog converter configured to convert the digital signal pulse representation to an analog signal including one of the signal pulses.

9. 2. The system of claim 1, wherein the signal generator is configured to generate the signal pulses having a maximum peak-to-peak amplitude such that a maximum current density on the electrodes is less than a given current density.

10. 1. A healthcare system comprising: a catheter interface including electrode wires configured to be electrically connected to respective electrodes of the catheter; a signal generator configured to generate signal pulses and time-multiplex the signal pulses among the electrode wires, the signal generator configured to generate the signal pulses having a maximum peak-to-peak amplitude such that a maximum current density on the electrodes is less than a given current density.

11. 1. A computer-implemented method comprising: generating signal pulses, each of the signal pulses including a carrier frequency and having a non-rectangular signal envelope; and time multiplexing the signal pulses among electrode wires configured to be electrically connected to respective electrodes of the catheter.

12. the electrodes emitting position signals in response to the time-multiplexed signal pulses; detecting the position signal using body surface electrodes applied to a body surface of the living body; The method of claim 11 , further comprising: calculating a position of the catheter in response to the detected position signal.

13. receiving electroanatomical signals from the electrodes via the electrode wires; The method of claim 11 , further comprising: processing the received electroanatomical signals.

14. The method of claim 11 , further comprising generating the non-rectangular signal envelope such that the peak-to-peak amplitude of the envelope gradually increases over time to a maximum peak-to-peak amplitude.

15. 12. The method of claim 11, further comprising generating the non-rectangular signal envelope such that the peak-to-peak amplitude of the envelope gradually increases over time to a maximum peak-to-peak amplitude and then, after a given period of time, the envelope gradually decreases over time to a peak-to-peak amplitude of zero.

16. The method of claim 15 , wherein the gradual increase in the peak-to-peak amplitude of the envelope is based on an error function (ERF).

17. The method of claim 16 , wherein the tapering in the envelope is based on a complementary error function (ERFC).

18. storing the digital signal pulse representation; Retrieving the stored digital signal pulse representation; and The method of claim 11 , further comprising converting the digital signal pulse representation to an analog signal including one of the signal pulses.

19. 12. The method of claim 11, wherein the generating comprises generating the signal pulses having a maximum peak-to-peak amplitude such that a maximum current density on the electrode is less than a given current density.

20. 1. A computer-implemented method comprising: generating a signal pulse; and time-multiplexing the signal pulses between electrode wires configured to be electrically connected to respective electrodes of a catheter, wherein the generating includes generating the signal pulses having a maximum peak-to-peak amplitude such that a maximum current density on the electrodes is less than a given current density.

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