System and method for synchronization of biopotential signals

Abstract

The subject of the invention is a system and method of synchronization of biopotential signals. Disclosed herein are novel systems and methods for synchronous streaming of electrocardiogram (ECG) signals to a display. One aspect of the invention provides synchronization between a first plurality of digitized ECG signals and a second plurality of digitized ECG signals, the first plurality of digitized ECG signals and the second plurality of digitized ECG signals sampled from a plurality of medical devices by a first asynchronous tool and a second asynchronous tool. One of the plurality of analog ECG signals, preferably a far-field ECG, is selected for reference and sampled by the two non-synchronous tools, resulting in respective first and second digitized reference ECG signals. The reference ECG signals are compared, and the results of the comparison are used to synchronize between the first plurality of digitized ECG signals and the second plurality of digitized ECG signals. Thus, the techniques of the present invention facilitate simultaneous parallel streaming of a plurality of digitized ECG signals from a plurality of asynchronous medical devices to a display. Other aspects and features of the invention are further disclosed herein.

Description

Technical Field

[0001] The present invention relates to in-situ signal processing of physiological signals, and in particular to synchronization of biopotential signals, such as electrocardiogram (ECG) electrograms (EGMs) and intracardiac electrograms (IEGMs) used in electrocardiogram monitoring during medical procedures. Background Art

[0002] A wide range of medical procedures involve placing a probe, such as a catheter, within a patient's body. One medical procedure where these types of probes or catheters have proven to be very useful is the treatment of cardiac arrhythmias. Cardiac arrhythmias, particularly atrial fibrillation, remain common and dangerous medical conditions, especially in the elderly population.

[0003] Diagnosis and treatment of arrhythmias include mapping the electrical properties of cardiac tissue (especially the endocardium and cardiac volume), and selectively ablating cardiac tissue by applying energy. In such surgeries, a catheter is inserted into and optionally around the cardiac chamber. In most surgeries, multiple catheters are inserted into the patient's body. The catheter may include a mapping catheter, an ablation catheter, a temperature sensing catheter, and an image sensing catheter. Some catheters are specifically designed to be placed in specific parts of the anatomical structure, such as the coronary sinus, esophagus, atrium, and ventricle. The catheter has multiple electrical channels, some of which have more channels than other catheters, depending on the number of sensors and electrodes included in each catheter. The number and type of catheters depends on the operation and the doctor's preferred workflow. During the operation, the electrical activity of the heart is monitored from the catheter electrodes and sensors and from the body surface electrodes attached to the patient's skin. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] In order to better understand the subject matter disclosed herein and to illustrate how the same may be implemented in practice, various embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:

[0005] Figure 1 is a schematic diagram showing a catheter-based electrophysiological mapping system 10 according to an embodiment of the present invention;

[0006] Figure 2 is a schematic diagram of a catheter suitable for providing a reference signal suitable for use in synchronization systems and methods according to some embodiments of the present invention;

[0007] Figure 3A is a block diagram showing a configuration of an ECG signal synchronization system 100 according to an embodiment of the present invention;

[0008] Figure 3B is a flow chart illustrating a method 180 for synchronizing between digitized ECG signals according to an embodiment of the present invention;

[0009] Figure 4A is a block diagram showing a configuration of an ECG signal synchronization system 100 according to another embodiment of the present invention; and

[0010] Figure 4B is a flow chart illustrating a method 190 for synchronizing between digitized ECG signals according to another embodiment of the present invention.

[0011] The same reference numerals are used in the drawings of the present invention to represent similar modules / elements of the present invention or elements / modules with similar functions. Therefore, unless otherwise specified, the description of the modules / elements with reference to a specific embodiment of the present invention should be understood to be applicable to all embodiments of the present invention in which such modules / elements are combined. DETAILED DESCRIPTION

[0012] Due to recent technological advances, the number of sensors and electrodes that can be included in a catheter has increased significantly. For example, some diagnostic catheters include a distal end with 50 or more biopotential sensors (e.g., electrodes) for sensing electrical activity within the heart chamber. A large number of electrodes enables a physician to capture electrical activity from multiple locations in the heart chamber simultaneously. Position sensors on the catheter record the locations where the electrical activity is sampled. The electrodes on the distal end include electrodes configured to engage with the tissue wall of the heart and sense near-field biopotential signals, and may also include a reference electrode configured to be immersed in a blood pool and sense far-field biopotential signals. The far-field signals can be used to remove any far-field components that may be captured by the electrodes, which are configured to engage with the tissue wall of the heart and sense the near-field signals.

[0013] There is a need in the art for novel systems and methods (e.g., medical devices) capable of collecting signals from high-density catheters. Conventional medical devices already deployed in medical operating facilities typically have limited channels for collecting and simultaneously sampling sensing signals from high-density (HD) catheters having, for example, 50 or more biopotential sensors (e.g., ECG electrodes), and cannot accommodate all sensing channels of such HD catheters. During a medical procedure (diagnosis and / or treatment), it is necessary to stream the outputs of all sensors (ECG sensors) from multiple medical devices to a physician for display in a synchronized manner. However, existing / deployed hardware that is typically adapted to collect, sample, and further transmit biopotential signals (ECG) from body surface electrodes and other catheters is typically not adapted to additionally collect, sample, and transmit additional sensing signals obtained from high-density catheters. Simply adding conventional hardware for collecting, sampling, and / or transmitting signals from HD catheters (e.g., separate from hardware already deployed for signals from other electrophysiological devices, such as body surface electrodes) does not facilitate synchronous sampling and / or transmission of signals from HD catheters along with signals from other electrophysiological devices. One reason is that such added hardware typically does not share the same sampling clock, and the already deployed medical devices do not facilitate direct synchronization of their sampling clocks with that of the added hardware. Another reason is that the added and existing hardware transmit signals obtained / sampled by them (e.g., for streaming to a display) via separate communication data links, which may introduce different delays to the communication.

[0014] Thus, the present invention provides novel systems and methods for addressing these issues, such that biopotential signals obtained from an HD catheter can be streamed synchronously with biopotential signals obtained from other electrophysiological devices, such as body surface electrodes and other catheters. Specifically, in certain aspects, the present invention facilitates such synchronous streaming while not requiring replacement of existing medical devices (e.g., already deployed medical devices), thereby enabling the use of HD catheters to be incorporated into existing medical facilities in a cost-effective manner.

[0015] According to certain aspects of the present invention, sample synchronization between signals sampled by existing and added hardware can be achieved by utilizing the output of one of the sensors of the HD catheter (hereinafter also referred to as a reference analog signal) for synchronization between the sensed signals obtained from the HD catheter and the sensed signals obtained from another electrophysiological device. The reference analog signal is separated and provided for sampling by both the existing and added hardware, thereby generating two digital reference signals that present samples of the reference analog signal according to the sampling clocks of the corresponding existing and added hardware. In practice, since these samples may not be synchronized, additional samples may be included in either of the two digital reference signals within a given time period due to the difference in the sampling clocks that sampled them. However, since the two digital reference signals are sampled from a common reference analog signal, such additional samples can be identified by comparing the two digital reference signals. The identified additional samples are then removed from the corresponding digital signals where they exist, thereby synchronizing the samples of the digital signals sampled by the two sampling tools and enabling them to be synchronously streamed to a display. Comparisons between the digital reference signals may be performed frequently enough to identify and remove a single extra sample or only a few extra samples (eg, up to 3) at a time in order to maintain continuous synchronization between the digital signals while avoiding noticeable information gaps in the displayed signals.

[0016] In order to facilitate the above-mentioned synchronization process of accurate and clear identification of samples and additional samples, the signal selected for use as a reference analog signal for synchronization should meet certain prerequisites as follows: it should be continuously non-stationary (for example, continuously have non-constant values); and should be non-periodic at least for the duration of each time interval in which comparison is performed to identify additional samples between the first digital reference signal and the second digital reference signal.

[0017] The inventors have discovered that far-field biopotential signals (e.g., far-field IEGM obtained from an HD catheter) meet these prerequisites and are suitable for use as reference signals for synchronization. This is because: 1. In contrast to near-field signals, which are captured based solely on contact or proximity of electrodes to tissue (e.g., skin / heart wall), far-field biopotential signals are always present during a medical procedure. 2. Far-field biopotential signals are biological signals and are therefore not periodic. Therefore, in certain embodiments of the present invention, far-field biopotential signals (e.g., obtained from an IEGM sensor of a far-field HD catheter) are specifically selected as reference analog signals for the synchronization process, which is described above and in more detail below.

[0018] refer to Figure 1, which shows an exemplary catheter-based electrophysiological mapping and ablation system 10. The system 10 includes a plurality of catheters that are inserted percutaneously through the patient's vascular system into a chamber or vascular structure of a heart 12 by a physician 24. Typically, a delivery sheath catheter is inserted into the left atrium or right atrium near a desired location in the heart 12. One or more catheters may then be inserted into the delivery sheath catheter to reach a desired location in the heart 12. The plurality of catheters may include a catheter dedicated to sensing intracardiac electrogram (IEGM) signals, a catheter dedicated to ablation, and / or a catheter dedicated to both sensing and ablation. An exemplary catheter 14 constructed for sensing IEGM is shown herein. The physician 24 may place the distal end 28 of the catheter 14 in contact with the heart wall for sensing a target site in the heart 12. For ablation, the physician 24 may similarly place the distal end of the ablation catheter in contact with the target site for ablating tissue.

[0019] The catheter 14 is an exemplary catheter that includes one (preferably multiple) electrodes 26, optionally distributed on a plurality of strips 22 at a distal tip 28 and configured to sense IEGM signals. The catheter 14 may further include a position sensor 29 embedded in or near the distal tip 28 for tracking the position and orientation of the distal tip 28. Optionally and preferably, the position sensor 29 is a magnetically based positioning sensor that includes three magnetic coils for sensing three-dimensional (3D) position and orientation.

[0020] The magnetic-based position sensor 29 can operate with the positioning pad 25, which includes a plurality of magnetic coils 32 configured to generate a magnetic field in a predetermined working space. The real-time position of the distal tip 28 of the catheter 14 can be tracked based on the magnetic field generated by the positioning pad 25 and sensed by the magnetic-based position sensor 29. Details of magnetic-based position sensing technology are described in U.S. Patents 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.

[0021] The system 10 includes one or more electrode patches 38 positioned in contact with the skin of the patient 23 to establish a position reference for impedance-based tracking of the positioning pad 25 and the electrodes 26. For impedance-based tracking, current is directed toward the electrodes 26 and sensed at the electrode skin patches 38 so that the position of each electrode can be triangulated via the electrode patches 38. Details of impedance-based position tracking techniques are described in U.S. Patents 7,536,218, 7,756,576, 7,848,787, 7,869,865, and 8,456,182.

[0022] Recorder 11 records and displays electrograms 21 captured using body surface electrocardiogram (ECG) electrodes 18 and intracardiac electrograms (IEGMs) captured using electrodes 26 of catheter 14. Recorder 11 may include pacing capabilities for pacing the cardiac rhythm and / or may be electrically connected to a separate pacemaker.

[0023] The system 10 may include an ablation energy generator 50 adapted to conduct ablation energy to one or more electrodes at the distal end of a catheter configured for ablation. The energy generated by the ablation energy generator 50 may include, but is not limited to, radio frequency (RF) energy or pulsed field ablation (PFA) energy (including monopolar or bipolar high voltage DC pulses that may be used to achieve irreversible electroporation (IRE)), or a combination thereof.

[0024] The patient interface unit (PIU) 30 is an interface configured to establish electrical communication between medical devices, such as catheters and / or electrophysiology equipment, and a workstation 55 for controlling the operation of the system 10. The medical devices of the system 10 may include, for example, electrophysiology equipment, such as one or more catheters, a positioning pad 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 enabling real-time calculation of the position of the catheter and for performing ECG calculations.

[0025] Workstation 55 includes memory, a processor unit having memory or storage storing appropriate operating software, and user interface capabilities. Workstation 55 can provide multiple functions, optionally including: (1) three-dimensional (3D) modeling of endocardial anatomy and rendering the model or anatomical map for display on display device 27; (2) displaying the activation sequence 20 (or other data) compiled from the recorded electrograms 21 on display device 27 as representative visual markers or images superimposed on the rendered anatomical map; (3) displaying the real-time position and orientation of multiple catheters within the heart chamber; and (4) displaying sites of interest on display device 27, such as where ablation energy has been applied. A commercial product embodying elements of system 10 can be CARTO TM The 3 system was purchased from Biosense Webster, Inc., 31A Technology Drive, Irvine, CA 92618.

[0026] In this example, the catheter 14 is a high density (HD) catheter 14 having, for example, 50 or more biopotential sensors (ECG electrodes). An example of such a high density catheter 14 is schematically shown in Figure 2 The HD catheter 14 includes a shaft 14H, wherein a position sensor 29 is typically embedded in or near the distal end 28 of the shaft 14H for tracking the position and orientation of the distal tip 28. In this particular non-limiting example, the HD catheter 14 includes a push rod 14P passing through the shaft 14H and a plurality of strips 22 on which a large number of near-field intracardiac electrogram sensors / electrodes 26 are arranged. The strips 22 are arranged near the distal end and form an expandable distal end assembly that can be deflected outward from the catheter by moving the push rod 14P to engage the near-field intracardiac electrogram sensors / electrodes 26 to contact the tissue wall of the heart for sensing near-field signals IEGM signals (e.g., activation biopotential signals) when the catheter is positioned within the heart. The catheter 14 also includes a far-field intracardiac electrogram sensor / electrode 14F (arranged on the push rod 14P in this example). The far-field IEGM sensor / electrode 14F is configured to remain spaced apart from the intracardiac tissue during operation of the catheter while immersed in the blood pool to measure / sense far-field biopotential signals (far-field IEGM). To this end, the far-field IEGM sensor / electrode 14F is typically larger than the near-field electrode 26 and is configured to have sufficient sensitivity for sensing the far-field IEGM signal. The far-field signal can be used, for example, to remove the far-field component that can be captured by the near-field electrode 26.

[0027] It should be understood that the term biopotential signal / sensor is used herein to refer to an electrophysiological signal or a sensor thereof, such as, but not limited to, an electrocardiogram (ECG), an electrogram (EGM), and an intracardiac electrogram (IEGM). It should also be noted that, without loss of generality, the terms electrocardiogram and ECG are used interchangeably herein to generally specify any type of biopotential signal. In this regard, it should be noted that the term far-field with respect to biopotential signals is used herein to specify biopotential signals, such as ECG, EGM, and IEGM, which are measured by suitable far-field sensors / electrodes without contacting a patient's body tissue (e.g., maintained spaced / separated from the tissue during measurement while potentially immersed in a pool of body fluids such as blood). In contrast, as used herein, the term near-field refers to a biopotential signal that is measured by a sensor / electrode designed to contact a patient's body tissue (e.g., skin tissue or intracardiac tissue) for measurement.

[0028] Back to Figure 1 , as described above, electrophysiological devices, such as a surface ECG device 38, which includes a plurality of ECG electrode patches externally attached to the patient's body / skin, and other electrophysiological devices, such as additional catheters (not specifically shown) are connected to the PIU 30, which facilitates electrical communication between these electrophysiological devices and the workstation 55. The PIU 30 may, for example, be adapted to apply analog-to-digital conversion (sampling) to signals received from the electrophysiological devices connected thereto, and / or to encapsulate these signals in data packets and transmit them to the workstation 55.

[0029] However, in some implementations of system 10 (e.g., systems that have been deployed in medical operating facilities), PIU 30 may have limited channels for collecting and simultaneously sampling / packaging sensor signals and may not accommodate the use of sensors such as those in Figure 2 The multiple electrodes 26 of the HD catheter 14 illustrated in FIG. 1 provide multiple sensing channels.

[0030] Thus, in some implementations, the system 10 includes an additional signal processing unit (SPU) 31 that is configured and operable to supplement / expand the functionality of the PIU 30 to enable connection of additional medical devices such as an HD catheter 14 to the system 10. The SPU 31 is configured and operable to have one or more functionalities (not necessarily all of the PIS functionalities) similar to the functionality of the PIU 30 described above, so as to supplement the PIU 30 and support connection of additional medical devices to the system 10. For example, the SPU 31 provides an interface for collecting and sampling / packaging signals from the HD catheter 14 or other electrophysiological devices, and may also be used to connect such electrophysiological devices to the ablation energy generator 50 and / or recorder 11. In addition, the SPU 31 may optionally implement processing capabilities for implementing real-time calculations of the position of a catheter connected thereto or for performing ECG calculations.

[0031] Reference now Figure 3A , which is a block diagram depicting the configuration of the synchronization subsystem 100 of the system 10 according to some embodiments of the present invention. In this embodiment, each of the SPU 31 and the PIU 30 includes a respective sampling tool 120A and 120B. The sampling tools 120A and 120B are respectively configured and operable to sample analog biopotential signals sensed by the respective medical devices connected thereto, convert them into digitized biopotential signals 151 and 152, and further transmit them to the workstation 55. The workstation 55 then processes at least some of these biopotential signals 151 and 152 for display on the display 27 (while optionally also utilizing these signals to perform other processing, such as ECG calculation, mapping, recording, etc.).

[0032] Since the sampling clocks CLK1 and CLK2 of the respective sampling tools 120A and 120B of the SPU 31 and PIU 30 are not inherently synchronized (e.g., the SPU 31 and PIU 30 may not include direct synchronization means for synchronizing their sampling clocks), the workstation 55 thereof is configured to synchronize the signals obtained therefrom and thereby compensate for this lack of synchronization.

[0033] To accomplish this, a selected sensing channel 121R of the HD catheter 14 is split by a splitter 33 and directed for connection to the SPU 31 (to which the remainder of the sensing channels 121 of the HD catheter 14 are connected) and to an available port in the PIU 30 for sampling therefrom. The splitter 33 may, for example, be any suitable signal splitter 33, such as, for example, a cable-integrated signal splitter or a signal switch. In this manner, both the SPU and the PIU sample a common analog biopotential signal 121R (referred to herein as a reference analog signal) obtained from the sensing channels of the HD catheter 14 (e.g., from its far-field IEGM sensor) in this particular example. The digitized reference signals 151R and 152R obtained from the sampling of the common analog biopotential signal 121R by the SPU 31 and the PIU 30, respectively, are then provided to the synchronization system 100 of the workstation 55 and are used to identify and compensate for a lack of synchronization between the sampling tools of the SPU 31 and the PIU 30, as described below.

[0034] To this end, the synchronization system 100 is configured and operable to synchronize between digital biopotential signals 151 and 152, which are sampled by two or more asynchronous sampling tools 120A and 120B from a plurality of analog biopotential signals sensed by biopotential sensors (such as ECG and / or IWM electrodes) of a plurality of medical devices (e.g., 110A and 110B111A, 111B) connected thereto. More specifically, in this embodiment, the system 100 includes a synchronizer 150, which is adapted to synchronize samples of the first and second plurality of digitized signals 151 and 152 sampled by the first and second asynchronous sampling tools 120A and 120B, respectively. To achieve this, the synchronizer 150 receives a first plurality of digitized signals 151, which are obtained by the first sampling tool 120A and include a first digitized reference signal 121R obtained from sampling of a reference analog signal 151R by the first sampling tool, and also receives a second plurality of digitized signals 152, which are obtained by the second sampling tool 120B and include a second digitized reference signal 121R obtained from sampling of a reference analog signal 152R by the second sampling tool.

[0035] The synchronizer 150 includes a comparator 154 adapted to perform a comparison between the first and second digitized reference signals 151R and 152R to identify differences between their samples due to differences in the sampling rates between the first and second sampling means 120A and 120B (this is based on the fact that the first and second reference signals are sampled from copies of the same underlying analog reference signal 121R). Specifically, the comparator 154 is adapted to identify when the offset between the two digitized reference signals is equal to or greater than one complete digitized sample, in which case there is one (or optionally several samples, e.g., 3) additional sample that should be removed in order to synchronize the signals from the first and second sampling means 120A and 120B. It is noted that in the event that an offset of less than one sample is identified, no additional samples need be removed, and the signals from the first and second sampling means 120A and 120B can be considered synchronized until the offset grows to a duration of one sample or greater. In addition, the synchronizer 150 further comprises a sample processor 156 adapted to synchronize the samples in the plurality of first digitized signals 151 with the samples in the plurality of second digitized signals 152 based on the results / differences identified by the comparator 154. More specifically, based on the additional samples identified by the comparison, the sample processor 156 modifies the sequence of samples in each digitized signal in one of the first and second digitized signals that should be streamed to the display, such that the sequence of samples in each such digitized signal corresponds to the sequence of samples in the signal in the other of the first and second digitized signals of the same time frame. The sampling processor 156 thereby provides synchronization signals 151S and 152S of the first and second digitized signals 151 and 152, respectively.

[0036] Accordingly, the system 100 may include a streamer 170 (e.g., and / or a display adapter) that is configured and operable to simultaneously stream / provide signal frames formed based on the synchronized biopotential signals 151S and 152S for presenting those biopotential signals 151S and 152S on the display 27.

[0037] It should be understood that in various embodiments of the system 10, the biopotential / ECG signals synchronized by the system 100 are not necessarily used for display, or are used not only for display but also for application of additional processing that may be required for a medical procedure, or for further analysis of the biopotential / ECG signals or the medical condition of the patient. For example, the biopotential / ECG signals synchronized by the system 100 may be stored for further analysis and / or used to calculate an activation sequence to represent its markings with respect to an anatomical map, and / or to display its relationship with respect to a site of interest, such as a location where ablation energy has been applied.

[0038] Now refer to Figure 3B Describing the operation of the above-described system 100 in greater detail, a flow chart illustrating a method 180 for synchronizing between digitized biopotential signals sampled by asynchronous sampling tools is presented in accordance with an embodiment of the present invention.

[0039] At 181, a selected analog reference signal 121R is provided for sampling by each of the asynchronous sampling means 120A and 120B. Preferably, in various embodiments of the invention, a far-field biopotential signal (e.g., far-field ECG / IEGM) sensed by one of the medical devices, in this example 110A, is selected / set to be used as a reference analog signal 121R to be sampled by both / each of the sampling means.

[0040] The analog biopotential signal 121 from the medical device 110A and possibly from an additional medical device such as 111A is sampled by the first sampling means 120A simultaneously with the sampling of the analog reference signal 121R. Thus, the sampling by the first sampling means 120B produces the first plurality of digitized signals 151 provided in 182. As shown at 183, the first plurality of digitized signals 151 provided thereby include a first reference digitized signal 151R obtained by the simultaneous sampling of the analog reference signal 121R and the sampling of the signal 121 by the first sampling means 120A.

[0041] In a similar manner, analog signals 122 from medical device 110B and possibly from additional medical devices such as 111B are sampled by second sampling tool 120B, while analog reference signal 121R is sampled by second sampling tool 120B. Accordingly, a second plurality of digitized signals 152 sampled by second sampling tool 120B is provided in 184. As shown in 185, second plurality of digitized signals 152 includes second reference digitized signal 152R obtained by simultaneously sampling analog reference signal 121R and sampling signal 122 by second sampling tool 120B.

[0042] The sampling clocks CLK1 and CLK2 of the respective sampling tools 120A and 120B typically operate at slightly different frequencies in practice, even though they may have been specified to operate at similar nominal sampling rates. This may be due, for example, to manufacturing variability or any number of environmental or power supply conditions that affect the operating frequency of the clocks (e.g., affect frequency drift). The frequency of the sampling clocks is, for example, approximately 20 KHz, and the difference between these frequencies may in practice be substantially lower (e.g., for a nominal frequency of 20,000 Hz, one of the clocks may operate at that nominal frequency, while the other may drift one or more Hz and operate, for example, at 19,999 Hz). Note that, in general, the frequency difference between the sampling tools 120A and 120B may not necessarily be constant or fixed and may vary in some embodiments due to various conditions (e.g., power supply or temperature variations). Therefore, the techniques of the present invention for synchronizing the sampling of those signals are also applicable to situations where the frequencies that differ between the different sampling clocks are not constant.

[0043] Therefore, taking into account the described changes in sampling frequency, if one were to continuously display the signals obtained from different sampling tools 120A and 120B under the assumption that their sampling clocks are synchronized (e.g., based on the sampling order obtained from these sampling tools without knowing or taking into account their frequency difference), then the offset between the displayed signals of the different sampling tools would accumulate over time.

[0044] Therefore, method operations 186 and 187 of method 180 are implemented by comparator 154 and sample processor 156, respectively, to synchronize the signal samples sampled by the two sampling tools 120A and 120B, thereby preventing / mitigating the above-mentioned signal offset and providing a consistent and time-aligned presentation of the signals to the physician,

[0045] In 186, the comparator 154 compares the first digitized reference signal 151R with the second digitized reference signal 152R (e.g., by cross-correlation) in order to identify corresponding segments of samples therebetween. Thus, by the comparison performed in 186, additional samples are identified in the event that one of the first and second sampling tools (e.g., 120B) operates at a higher sampling rate. In this case, the comparison performed in 186 produces an indication of additional samples in the segment of samples of the two digitized reference signals 152R that were sampled by a faster sampling tool (e.g., 120B) than the corresponding segment of the digitized reference signal 151R sampled by the other sampling tool (e.g., 120A). In order to synchronize the signals from the first and second sampling tools, the additional samples are removed in operation 187 from the corresponding time frames of all signals to be displayed on the display 27 and sampled by the sampling tool (e.g., 120B) operating at the higher sampling rate.

[0046] To this end, operation 186 and subsequently operation 187 may be iteratively performed to process and synchronize time frame portions of the signals of the first and second sampling tools to be displayed on the display 27. In this regard, it should be understood that in order to compare continuous signal portions of the reference signal, continuous iterations must be performed, and typically, in some embodiments, iterations are performed at sufficiently small intervals to allow no more than a predetermined maximum number of additional sample thresholds to be captured and removed at each iteration (while preferably not much more frequently than that so as not to cause overhead to the processing system of the workstation 55 with unnecessary iterations).

[0047] In various embodiments of the invention, the predetermined threshold associated with the maximum number of additional samples to be identified in each iteration may be selected to be approximately one or no more than a few additional samples (e.g., a threshold of up to 3 additional samples to be identified in each iteration). Preferably, iterations are performed at sufficiently small time intervals to facilitate identification of only up to a single additional sample at each iteration (threshold of 1). Operating with such a small threshold (preferably one and no more than 3) may be important in order to prevent noticeable information gaps from appearing in the signal displayed to the physician (gaps that may form if a large number of additional samples are removed at once / from a single frame). Thus, the maximum time interval ΔT between consecutive iterations is max The maximum additional sample number threshold ΔS can be used max and the expected absolute maximum difference ΔF between the sampling rate F1 at which the first sampling tool can operate and the sampling rate F2 at which the second sampling tool can operate max For example, in some embodiments, the maximum time interval can be set to ΔT max =ΔS max / ΔF max , so that if the maximum difference between the sampling rates ΔF max is 10Hz and the extra sample threshold ΔS max is 1, then the continuous iteration is performed at least once for each 100 ms time frame of the signal. In fact, in some embodiments, for each signal frame to be displayed on the display 27, the iteration may be performed at least once, or within the above-mentioned maximum time interval ΔT max Iterations may be performed more than once if required.

[0048] To this end, in operation 187, the sampling processor 156 operates to remove additional samples sampled by the sampling tool operating at a faster sampling rate (e.g., 120B) from the corresponding segments of the signal obtained from the sampling tool. The additional samples are removed from the signal of the faster sampling tool and presented on the display 27. In this regard, it should be understood that what is actually identified in operation 186 is a segment / time frame of the signal obtained from the faster operating sampling tool (e.g., 120B) where one or more additional samples are present compared to the corresponding segment / time frame in the signal obtained from another sampling tool (e.g., 120A). In general, the specific additional samples to be removed from each such segment / time frame can generally be arbitrary. In addition, in some embodiments of the present invention, some criteria can be optionally applied to the selection of specific indices for removing additional samples from these segments to ensure that a large amount of information is not lost from the display of the signal by removing the additional samples. One such criterion that may be applied in some embodiments of the present invention is that multiple additional samples to be removed will not be removed from consecutive sampling indices (e.g., the removed additional samples will be sparsely distributed) so that no obvious gaps / jumps are formed in the displayed signal due to their removal. Another such criterion that may be applied in some embodiments is that the additional samples to be removed from the signal will not be selected for removal from extreme points of the signal (i.e., sampling indices that do not fall on extreme points are selected) so that peaks / valleys in the signal are properly displayed.

[0049] Thus, in operation 187, the sample processor 156 synchronizes the signals of the first and second sampling tools (at least those signals intended to be displayed) based on the results of the comparison performed by the comparator 154 in operation 186 by removing the additional samples identified by the comparison from the corresponding segments / time frames of the signals identifying the additional samples. Thus, in operation 188, the synchronization signals obtained in operation 187 can be packaged / compiled in a display frame (e.g., showing the multiple synchronization signals from the two sampling tools aligned with each other) and streamed for presentation on a display. The streaming can be performed at the frame rate of the display, whereby each displayed frame presents corresponding / aligned time segments of the multiple synchronization signals. Thus, the operations of method 180 can be performed iteratively to prepare the set of synchronization signals for each displayed frame.

[0050] Furthermore, it should be noted that typically in various embodiments of the invention, the sampling resolution of the signal synchronized in operations 186 and 187 is set to be greater than the display resolution in each time frame of the displayed frame (e.g., such that the number of samples / display points of the signal actually displayed on the display in each displayed time frame is less than the actual number of samples in the synchronization signal). Thus, in preparation for displaying the frame in operation 188, the synchronized biopotential signals 151S and 152S obtained from operations 186 and 187 may be downsampled to match the display resolution. This downsampling helps avoid noticeable gaps in the displayed frame due to the omission of extra samples therefrom (because any information gaps formed by such omissions are smoothed / blurred by the process of omitting sparse extra samples from a high resolution signal such as obtained from 187 and then downsampling the signal to a lower display resolution).

[0051] In this regard, the inventors of the present invention have recognized that far-field biopotential signals, such as far-field intracardiac electrograms (far-field IEGMs), are particularly suitable for use as reference analog signals 121 for the above-mentioned signal synchronization. In this regard, reliable and accurate implementation of the method 180 for synchronizing biopotential signals, particularly biopotential signals obtained during a medical procedure, requires appropriate selection of a suitable biopotential analog signal for use as the reference signal 121 for synchronization. A biopotential analog signal suitable for use as a reference signal 121 for the above-mentioned signal synchronization purpose should be non-stationary (e.g., not a flat signal) throughout the medical procedure and non-periodic for at least the duration of each displayed signal frame suitable for use as a reference signal (which is typically approximately 50 ms, displayed at approximately 20 frames per second (FPS)). The inventors have discovered that, for example, a far-field intracardiac electrogram (far-field IEGM) signal obtained by a far-field sensor of an HD catheter 14 is suitable for use as a reference signal 121. In practice, the far-field biopotential signal generally meets the above-mentioned precise requirements for synchronization because the sensor 14F configured for its measurement is highly sensitive to allow it to measure the signal without contact with tissue and thus operates to obtain a signal that is non-stationary regardless of contact with tissue; and also because, due to its relatively high sensitivity, it picks up a large amount of noise that is incorporated into the far-field signal, making the far-field signal substantially non-periodic (e.g., at least within the relevant duration of each displayed signal frame). Thus, the problem of connecting an HD catheter 14 in a synchronized manner is facilitated by the techniques of the present invention and preferably by utilizing the far-field IEGM signals obtained from such catheters, even to an already deployed system 10 whose PIU does not support sampling of signals from a large number of sensors from such HD catheters 14.

[0052] Therefore, in some embodiments of the present invention, preferably, a far-field biopotential signal (e.g., a far-field IEGM obtained from the catheter 14) is used as a reference analog signal 121 for the above-mentioned synchronization. In this regard, it should be understood that one of the above-mentioned near-field signals can be used as a reference signal for the synchronization of the present invention. However, this may provide less reliable / consistent results because those signals are less noisy and therefore may be periodic (e.g., consistent with the periodicity of cardiac activity), and also because the acquisition of near-field signals depends on the contact maintained between the sensor / electrode sensing the near-field signal and the body / heart tissue, and therefore in the case of separation of the sensor / electrode from the tissue, a flat / smooth signal may be obtained, thereby preventing the implementation of the above-mentioned synchronization.

[0053] Therefore, returning to operation 181 of method 180 , in some embodiments of the present invention, the analog reference signal 121R used for synchronization and provided for sampling by each of the asynchronous sampling tools 120A and 120B is preferably a far-field biopotential signal, such as a far-field IEGM obtained from the catheter 14 .

[0054] refer to Figure 3A As shown, the system 100 may optionally further include modules / tools represented by reference numerals 130, 140 and 160. Figure 4A and Figure 4B The configuration and operation of these optional modules / tools are described in more detail, wherein examples of synchronization systems 100 and methods 190 according to some embodiments of the present invention are shown.

[0055] As described above, another difference may be introduced by the addition of hardware for collecting and transmitting signals from the HD catheter, which is separate from the existing hardware for collecting and transmitting signals from other electrophysiology devices, and the added and existing hardware typically transmit the signals obtained thereby via independent communication data links, which may introduce different delays to the communication and thus introduce differences / time lags between the displayed signals of the added and existing hardware if they are displayed directly together.

[0056] Now let’s refer to Figure 4A and Figure 4B , shows the configuration and operation of a synchronization system 100 according to another embodiment of the present invention, which is suitable for applying communication / packet synchronization to synchronize between biopotential signals that are measured by different medical devices and collected and transmitted to the system via different hardware. Figure 4A is a block diagram depicting the configuration of synchronization system 100 and its connection with other modules / tools of system 10 according to an embodiment of the present invention. Figure 4Bis a flow chart illustrating a method 190 for synchronizing between bio-signals sensed by sensors of several medical devices (such as 110A and 110B of system 10) and acquired by respective PIU 30 and SPU 31 tools associated therewith.

[0057] The tools 30 and 31 can be connected to the medical devices 110A and 110B, respectively (and optionally to additional medical devices such as 111A and 111B) to receive analog biopotential signals 121 and 122 sensed therefrom, or digital biopotential signals 151 and 152. In the case where the biopotential signals are received in analog form 121 and 122, the corresponding tools (i.e., tools 31 and / or 30) can include corresponding sampling tools 120A or 120B, which are suitable for sampling the corresponding signals to obtain their digitized forms 151 and 152. The SPU 31 and PIU 30 tools also include corresponding network adapters 124A and 124B, which are configured and operated to establish corresponding communication data links 145A and 145B between the corresponding tools associated therewith and the workstation 55 through the data communication network NET, for transmitting the corresponding digital biopotential signals 151 and 152 obtained therefrom to the workstation 55.

[0058] The network NET may be, for example, any suitable data communication network, such as a LAN or WIFI or any other data communication network suitable for transmitting medical signals to the workstation 55 during a medical procedure. The communication data links 145A and 145B between the tools 31 and 30 and the workstation 55 may be established, for example, based on the TCP / IP protocol or a similar protocol that provides reliable (e.g., authenticated) communication of data packets through the network. To this end, the network adapters 124A and 124B encapsulate the respective biological signals 151 and 152 obtained by their respective tools 31 and 30 and send them to the workstation 55 in respective transmission data packet sequences 141T and 142T via the corresponding data links 145A and 145B established between the tools 31 and 30 and the workstation 55. The biological signals 151 and 152 are typically sampled at a constant rate, and therefore the data packets of the transmission data packet sequences 141T and 142T are typically encapsulated and transmitted by the tools 31 and 30 over time t at substantially regular time intervals Δt1 and Δt2, such as Figure 4A shown.

[0059] The synchronization system 100 in this embodiment is suitable for monitoring communication delays with different medical hardware (e.g., tools 31 and 30) that collect biopotential signals measured by different medical devices, and adjusting the display timing of the signals accordingly to mitigate these communication delays, thereby enabling them to be presented together in a timely and synchronized manner.

[0060] The synchronization system 100 includes a data communication tool 130 (e.g., a network adapter) configured and operable to establish first and second communication data links 145A and 145B with respective tools 31 and 30 and receive therethrough respective first and second received data packet sequences 141R and 142R in response to sequences 141T and 142T transmitted by tools 31 and 30. To this end, the received first data packet sequence 141R includes a plurality of first digitized physiological / biopotential signals 151 sampled from sensors of at least one first medical device 110A and packaged and transmitted by the first tool 31 on the first communication link 145A; and the received second data packet sequence 142R includes a plurality of second digitized physiological / biopotential signals 152 sampled from sensors of at least one second medical device 110B and packaged and transmitted by the second tool 30 on the second communication link 145B.

[0061] As described above, the first and second data packet sequences 141R and 142R preferably communicate using a reliable / efficient communication protocol such as TCP to ensure that they are consistently received by the workstation 55 so that the signal portion encapsulated by each data packet can be consistently / reliably displayed on the display 27 without loss of signal information due to erroneous communication of data packets.

[0062] However, typically authenticated / reliable transmission protocols are not well suited to real-time / pseudo-real-time operation and may introduce variable time lags / delays in their communications. Due to the variable delays in the communications, the time intervals between the reception of the data packets in each of the first and second reception sequences 141R and 142R and possibly the order of their reception may vary relative to the time intervals and order of their transmissions 141T and 142T. Therefore, if the portions of the signals 151 and 152 provided by respective ones of these data packets were to be presented in the display 27 in actual full real-time (i.e., as soon as the data packets are received), variable time delays between the presentation of different biopotential signal portions will be introduced in their presentation to the physician, which may result in inconsistent and possibly misleading presentation of the biopotential signals to the physician.

[0063] Thus, the system 100 can operate in pseudo real-time with some modest time delay introduced into the presentation, which does not exceed some time delay threshold (e.g., up to 150 ms) between the sensing of the biopotential signals and their presentation. Such pseudo real-time operation facilitates consistent and time-ordered presentation of the biopotential signals 151 and 152 to the physician (mitigating network latency), while the actual presentation of the biopotential signals to the physician with such modest latency does not impair the medical procedure, since the introduced time delay is small enough to be unnoticeable / significant to the medical procedure on the one hand, and sufficient to establish consistent presentation of the biopotential signals on the display 27 on the other hand.

[0064] To achieve this, the system 100 includes a packet synchronizer 140, which includes a data link monitor 142 and a buffering tool 145. The communication link monitor 142 is connected to the data communication tool 130 and is adapted to monitor the reception timing of data packets of the data packet sequence 141R and 142R received through each of the first and second data links 145A and 145B. The communication link monitor 142 thereby determines a statistical value of the communication delay of the data packets through each of the first and second data links 145A and 145B. The buffering tool 145 is configured and operable to determine a buffering duration ΔT of the biopotential signal provided in the data packets of the data packet sequence 141R and 142R using the statistical value of the delay of the data links 145A and 145B, and postpone the streaming to the display 27 by this buffering duration. The buffering means 145 is associated with the memory / buffer 147 and is configured and operative to buffer the portions of the first and second digitized biopotential signals 151 and 152 provided in the data packet sequences 141R and 142R in said buffer 147. The system 100 further comprises a frame encapsulator 160 configured and operative to continuously retrieve data packets of the data packet sequences 141R and 142R from the buffer (e.g. after the buffering duration has elapsed) and to re-encapsulate a continuous set of samples of the portions of the biopotential signals 151 and 152 retrieved from the buffer 147 according to their sampling order and to utilize them to form a continuous sequence of signal frames to be streamed for display by the display 27. Thus, the system 100 may comprise or be associated with a streamer 170 (e.g. which may be implemented, for example, by a display adapter or a network streamer) adapted to operate after the buffering duration has elapsed for streaming said signal frames to the display 27 at a predetermined / set frame rate.

[0065] As described above, in various specific implementations of the biopotential / ECG signal synchronized by the system 100 of this embodiment, it may not necessarily be used for display, or may not only be used for display, but may also optionally be subjected to additional processing. For example, the biopotential / ECG signal synchronized by the system 100 may be stored for further analysis and / or for calculating activation sequences, thereby representing its labeling with respect to an anatomical map, and / or other processing as may be required.

[0066] Now refer to Figure 4B The flow chart of method 190 shown in describes the operation of system 100 in more detail.

[0067] Operations 191 and 192 may be performed in parallel by the data communication tool 130 which receives the first and second data packet sequences, wherein typically the first and second digitized biopotential signals or portions thereof are received via corresponding data links.

[0068] In operation 193, the statistical value of the communication delay in each data link 145A and 145B is determined by the data link monitor 142. To this end, the data link monitor may be adapted to apply statistical processing to the reception timing of the data packets from the respective first and second tools 31 and 30, thereby determining the standard deviation σ, respectively. A , σ B or the variance of delays in the transmission of data packets through each data link 145A and 145B. It should be noted that in some embodiments, the data link controller 142 may not obtain information about the transmission time of the corresponding data packets, and the statistical calculation may be performed with consideration of an operating scheme in which the data packets transmitted through each of the data links 145A and 145B are transmitted at substantially regular / equal time intervals. Such an operating scheme in which data packets are actually transmitted through each data link 145A or 145B at substantially regular / equal time intervals may be implemented in some embodiments of the present invention, wherein the data packets carry similar sized portions of the biopotential signal transmitted therefrom (e.g., similar duration / number of samples). Alternatively or additionally (e.g., in the case where the data packets may carry biopotential signal portions of variable duration and are not transmitted at fixed intervals), the data link monitor 142 may utilize information about the transmission time of the data packets (which may be indicated in the corresponding data packets themselves) and their reception timing by the network communication tool 130 in order to determine the delay statistics of the corresponding data links 145A and 145B. It should be understood that those skilled in the art will easily understand how to determine the delay statistics of the data link in the above-mentioned technology.

[0069] Thus, given the delay statistics, in operation 194, the buffering tool 145 determines a buffer duration ΔT by which to postpone the synchronous streaming of the biopotential signal / part thereof received via the data packets to the display. Typically, the buffer duration ΔT is set to match the standard deviation σ in the delay statistics of the respective data links 145A and 145B. A , σ B The maximum standard deviation of the predetermined multiple n, while not exceeding the predetermined maximum buffer threshold ΔT MAX , in order to facilitate pseudo real-time presentation of the biopotential signal on the display 27. For example, the buffer duration ΔT may be set as follows: ΔT=Min(n*Max(σ A ,σ B ),ΔT MAX ), whereby the predetermined multiple n can be set in the range of 2.5 to 4 standard deviations (eg, 3), and the maximum buffer threshold ΔT MAX It may be set to tens of milliseconds, for example up to 150ms or 200ms. Thus, deferring the streaming of the biopotential signal to the display 27 in this manner produces a pseudo real-time presentation of the signal on the display, with the potential for disappearance of signal packets not being received in time for their display.

[0070] In operation 195 , upon initializing synchronized streaming of the biopotential signals 151 and 152 to the display, the packet synchronizer 140 delays the synchronized streaming by a buffering duration ΔT, and in operation 196 , the buffering tool 145 operates to buffer / store in the buffer 147 the first and second biopotential signals 151 and 152 received via data packets via the first and second data links.

[0071] Then, in operation 197, the frame packer 160 operates to generate a sequence of continuous signal frames that present portions of the biopotential signals 151 and 152, all corresponding portions of which are received via the data communication links 145A and 145B (e.g., stored in the buffer 147). This may include packing and formatting the continuous sets of signal samples of the first and second pluralities of biopotential signals from the buffer according to their sampling order to form a sequence of continuous signal frames to be displayed on the display 27. In this regard, it should be understood that in some implementations, overlapping sets of signal samples may be packed into continuous signal frames so that the display displays a video presenting continuous / smooth changes of the biopotential signals over time. It should be noted that in some embodiments, the sampling resolution of the sets of signal samples of the biopotential signals is higher than the display / frame resolution of the signal frames presenting the biopotential signals on the display. In such embodiments, the frame packer 160 may include a resampler 165 that is configured and operable to resample the sets of samples of the signal to be presented in the signal frames so as to reduce their resolution and facilitate their presentation in the signal frames.

[0072] Then, in operation 198 , after the buffering duration has elapsed (from the time when the synchronous streaming was initialized in operation 195 ), the sequence of continuous signal frames formed in operation 197 is streamed by the streamer / display adapter 170 for display on the display 27 .

[0073] Figure 4A and Figure 4B The system 100 and method 190 thus provide packet synchronization for synchronizing between data packets carrying biopotential signals of different medical devices transmitted on different data links with variable delays, and enable pseudo real-time synchronized simultaneous presentation of biopotential signals sensed by different medical devices.

[0074] In some embodiments, the system 100, such as the frame packer 160 thereof, optionally further includes the above reference FIG. 3A to FIG. 3B The synchronizer 150 described herein. The synchronizer 150 may be operated, for example, according to the method 180 described above, for synchronizing between samples of a set of signal samples of a biopotential signal encapsulated in each signal frame. More specifically, the synchronizer processes the signal sample groups to identify and remove extra samples obtained in one or more sets due to the difference between the sampling rates of the first and second tools, and thereby mitigates any asynchrony between the sample sets sampled by the non-synchronized sampling tools of the different medical devices. In such embodiments, the system 100 applies both group synchronization as well as sample synchronization to the signals received from the plurality of medical devices.

[0075] It should be noted that the present invention is described above with particular reference to biopotential signals, such as electrocardiograms (ECGs), electrograms (EGMs), and intracardiac electrograms (IEGNs). In this regard, as will be readily appreciated by those skilled in the art, the methods and systems of the present invention are not limited to these particular biopotential signals, and may be adapted for use with other biopotential signals and / or other physiological signals without departing from the scope of the present invention.

[0076] Example

[0077] Embodiment 1. A method for synchronously streaming electrocardiogram (ECG) signals obtained from a plurality of medical devices to a display, the method comprising:

[0078] providing a plurality of first digitized signals including a first reference digitized signal, whereby the plurality of first digitized signals are sampled by a first sampling tool from a plurality of first analog signals sensed by a plurality of first ECG sensors of a first medical device, and wherein one first analog signal among the plurality of first analog signals is selected as a reference analog signal, and the first reference digitized signal corresponds to sampling of the reference analog signal by the first sampling tool;

[0079] providing a plurality of second digitized signals including a second reference digitized signal, whereby the plurality of second digitized signals include one or more second digitized signals sampled by a second sampling means from one or more second analog signals sensed by one or more second ECG sensors of a second medical device simultaneously with sensing of the plurality of first analog signals, and the second reference digitized signal is simultaneously sampled by the second sampling means from the reference analog signal sensed by the first medical device;

[0080] comparing the first digitized reference signal with the second digitized reference signal;

[0081] Based on the comparing, synchronizing between the plurality of first digitized signals and the one or more second digitized signals; and

[0082] The plurality of first digitized signals are streamed in parallel to the display in synchronization with the one or more second digitized signals.

[0083] Embodiment 2. The method according to embodiment 1, comprising:

[0084] sensing the plurality of first analog signals by the plurality of first ECG sensors of the first medical device;

[0085] in parallel, sensing the one or more second analog signals by the one or more second ECG sensors of the second medical device;

[0086] Using the first sampling tool to sample the plurality of first analog signals to obtain the plurality of first digitized signals including the first reference digitized signal; and

[0087] Sampling the one or more second analog signals and the reference analog signal using the second sampling tool to obtain the one or more second digitized signals and the second digitized reference signal;

[0088] Embodiment 3. The method according to embodiment 1 or 2, wherein the synchronization comprises:

[0089] identifying, based on the comparing, additional samples obtained in each of the first digitized signal or the second digitized signal obtained from one of the first sampling tool or the second sampling tool, respectively, wherein the additional samples are generated by a difference between sampling rates of the first sampling tool and the second sampling tool; and

[0090] The additional samples are removed from each of the first digitized signal or the second digitized signal prior to the streaming to the display.

[0091] Embodiment 4. The method according to any one of embodiments 1 to 3, wherein sampling clocks of the first sampling tool and the second sampling tool operate at sampling rates around a similar nominal sampling rate.

[0092] Embodiment 5. A method according to any one of embodiments 1 to 4, wherein each frame displayed by the ECG signal on the display presents a time interval of the ECG signal that does not exceed a specific maximum duration, and wherein the reference analog signal is selected to be one of the first analog signals that is non-periodic and non-stationary within the interval of the specific maximum duration.

[0093] Embodiment 6. The method according to embodiment 5, wherein the reference analog signal is a far-field ECG signal.

[0094] Embodiment 7. A method according to any one of embodiments 1 to 6, wherein the first medical device and the second medical device include a plurality of ECG sensors suitable for sensing the ECG signal in situ during cardiac operation.

[0095] Embodiment 8. The method according to embodiment 7, wherein one or more of the following:

[0096] - at least one of the first medical device and the second medical device is a catheter adapted to be inserted into the body for at least one of probing and treating the heart; and at least one of the first sampling tool and the second sampling tool is connected to a plurality of ECG sensors of the catheter adapted to measure the heart activity in situ during the cardiac operation;

[0097] - At least one of the first medical device and the second medical device is a surface ECG device comprising a plurality of ECG sensors suitable for being placed on the body, outside the body, for detecting the heart; and at least one of the first sampling tool and the second sampling tool is connected to the plurality of ECG sensors.

[0098] Example 9. A method according to any one of Examples 1 to 8, wherein the first medical device is a catheter suitable for being positioned within the heart during operation to sense intracardiac electrogram (IEGM) signals, and the reference analog signal is an ECG signal obtained from at least one ECG sensor of the catheter.

[0099] Embodiment 10. A method according to any one of Embodiments 1 to 9, wherein the catheter is suitable for being inserted into the heart, and the multiple ECG sensors of the catheter include multiple ECG sensors arranged in the catheter for contacting tissue of the heart during operation of the catheter, and at least one ECG sensor arranged in the catheter so that it is spaced apart from the tissue of the heart during the operation of the catheter, thereby enabling a far-field ECG signal of the heart to be sensed via the at least one ECG sensor and utilizing the far-field ECG signal as the reference analog signal.

[0100] Embodiment 11. The method according to any one of embodiments 1 to 10, comprising applying further processing to the synchronized first digitized signal and the second digitized signal to analyze or calculate one or more properties associated with the electrocardiogram.

[0101] Embodiment 12. A method for synchronously streaming electrogram (ECG) signals obtained from a plurality of medical devices to a display, the method comprising:

[0102] receiving, via a first data link associated with a first tool of a first medical device, a first sequence of data packets including a plurality of first digitized ECG signals periodically packaged and transmitted by the first tool over the first data link;

[0103] receiving, via a second data link associated with a second tool of a second medical device, a second sequence of data packets including one or more second digitized ECG signals periodically packaged and transmitted by the second tool over the second data link;

[0104] monitoring the reception timing of data packets periodically transmitted on each of the first data link and the second data link to determine a statistical value of communication delay in each of the data links;

[0105] determining a buffer duration based on the statistical value of the communication delay, and delaying the synchronous streaming of the ECG signal to the display by the buffer duration;

[0106] as well as

[0107] upon initiating synchronized streaming of ECG signals to the display, deferring the synchronized streaming for the buffering duration;

[0108] buffering in a buffer the first digitized ECG signal and the second digitized ECG signal of the first sequence of data packets and the second sequence of data packets received on the first data link and the second data link;

[0109] continuously packing the consecutive sets of signal samples of the first digitized ECG signal and the second digitized ECG signal according to their sampling order retrieved from the buffer to form a consecutive sequence of signal frames to be streamed for display;

[0110] as well as

[0111] streaming the signal frames to the display at a frame rate after the buffering duration has elapsed;

[0112] The communication delays are thereby mitigated and pseudo real-time synchronous streaming of ECG signals obtained via data links associated with multiple medical devices to the display is enabled.

[0113] Example 13. A method according to Example 12, wherein the repackaging includes implementing the method according to claim 1, which is used to synchronize between the signal samples of the first digitized ECG signal and the second digitized ECG signal, and identify and remove extra samples obtained in each of the first digitized signal or the second digitized signal due to the difference between the sampling rates of the first tool and the second tool.

[0114] Embodiment 14. A method according to Embodiment 12 or 13, wherein the repackaging includes downsampling the signal samples of the first digitized ECG signal and the second digitized ECG signal of the set to form the signal frame at a resolution suitable for presentation on the display.

[0115] Embodiment 15. The method of any one of Embodiments 12 to 14, wherein the continuous set of the continuous sets of signal samples used to form the frame includes overlapping signal samples.

[0116] Embodiment 16. A method according to any one of embodiments 12 to 15, the method comprising respectively determining the standard deviation of the communication delay of each data link in the first data link and the second data link, and setting the buffer duration to match a predetermined multiple of the maximum standard deviation of the standard deviations of the communication delay.

[0117] Embodiment 17. A method according to any one of Embodiments 12 to 16, wherein the buffering duration is set to a multiple of at least three times the maximum standard deviation of the delay while not exceeding a predetermined maximum buffering duration allowed for the streaming transmission.

[0118] Embodiment 18. A system for synchronously streaming electrocardiogram (ECG) signals obtained from a plurality of medical devices to a display, the system comprising:

[0119] a synchronizer adapted to receive first and second pluralities of digitized signals sampled by the first and second sampling tools, respectively, from corresponding first and second pluralities of analog signals sensed by ECG sensors of the at least one first medical device and the at least one second medical device, respectively;

[0120] wherein the first plurality of digitized signals comprises a first reference digitized signal, the first reference digitized signal being sampled by the first sampling means from an analog signal selected as a reference analog signal from among the first plurality of analog signals, and being sensed by an ECG sensor of the first medical device selected as a reference ECG sensor; and wherein the second plurality of digitized signals comprises a second reference digitized signal, the second reference digitized signal being sampled by the second sampling means from the reference analog signal, and being sensed by the reference ECG sensor of the first medical device;

[0121] The synchronizer comprises:

[0122] - a comparator adapted to perform a comparison between the first digitized reference signal and the second digitized reference signal; and

[0123] a sampling processor adapted to synchronize the plurality of first digitized signals with the plurality of second digitized signals based on the result of the comparison between the first reference signal and the second reference signal performed by the comparator; thereby obtaining a synchronization signal of the first plurality of digitized signals and the second plurality of digitized signals; and

[0124] The synchronizer is associated with a streamer adapted to stream the synchronization signal of the first plurality of digitized signals and the second plurality of digitized signals in parallel for display on the display.

[0125] Embodiment 19. The system of embodiment 18, wherein the sampling processor is configured and operable to synchronize between the plurality of first digitized signals and the plurality of second digitized signals by:

[0126] - based on the result of the comparing, identifying additional samples obtained in each of the first plurality of digitized signals or one of the second plurality of digitized signals obtained from one of the first sampling tool or the second sampling tool, respectively; and wherein the additional samples are generated by a difference between sampling rates of the first sampling tool and the second sampling tool; and

[0127] - removing said additional samples from each of said digitised signals, said first digitised signal or said second digitised signal.

[0128] Embodiment 20. A system according to embodiment 18 or 19, wherein the first plurality of digitized signals and the second plurality of digitized signals are ECG signals; and wherein each frame of the ECG signal displayed on the display presents a time interval of the ECG signal that does not exceed a specific maximum duration; and wherein the reference analog signal is selected to be a first analog signal among the first analog signals that is non-periodic and non-stationary within the interval of the specific maximum duration.

[0129] Example 21. A system according to Example 20, wherein the at least one first medical device includes a catheter adapted to be positioned within the heart during its operation to sense an intracardiac electrogram (IEGM) signal; and wherein the reference ECG sensor is an ECG sensor arranged in the catheter so that it is separated from the tissue of the heart during the operation and is adapted to obtain the reference analog signal as a far-field ECG signal.

[0130] Embodiment 22. The system of any one of embodiments 18 to 21, wherein one or more of the following:

[0131] - the system further comprises at least one of: the at least one first medical device; the at least one second medical device; the first sampling tool; the second sampling tool; and the display;

[0132] - the at least one first medical device and the at least one second medical device comprise a plurality of ECG sensors adapted for sensing ECG signals in situ during cardiac operation;

[0133] - at least one of the first medical device and the second medical device is a catheter adapted to be inserted into a body for at least one of probing and treating a heart; and at least one of the first sampling tool and the second sampling tool is connected to a plurality of ECG sensors of the catheter;

[0134] - At least one of the first medical device and the second medical device is a surface ECG device comprising a plurality of ECG sensors suitable for being placed on the body, outside the body, for detecting the heart; and at least one of the first sampling tool and the second sampling tool is connected to the plurality of ECG sensors.

[0135] Embodiment 23. A system for synchronously streaming electrocardiogram (ECG) signals obtained from a plurality of medical devices to a display, the system comprising:

[0136] A data communication tool, the data communication tool being configured and operable to receive corresponding first and second data packet sequences via first and second communication links respectively associated with the first tool and the second tool; whereby the first data packet sequence comprises a plurality of first digitized ECG signals, the plurality of first digitized ECG signals being sampled from an ECG sensor of at least one first medical device and periodically packaged and transmitted by the first tool on the first communication link; and the second data packet sequence comprises a plurality of second digitized ECG signals, the second digitized ECG signals being sampled from an ECG sensor of at least one second medical device and periodically packaged and transmitted by the second tool on the second communication link;

[0137] A packet synchronizer, the packet synchronizer comprising:

[0138] a communication link monitor connected to the data communication tool and adapted to monitor the reception timing of data packets transmitted on each of the first communication link and the second communication link, thereby determining a statistical value of the communication delay of each of the first communication link and the second communication link; and

[0139] - a buffering tool comprising a buffer and configured and operable to determine a buffering duration using the statistical value of the communication delay, buffer the first digitized ECG signal and the second digitized ECG signal of the data packet by the buffering duration and postpone the streaming of the ECG signal to the display by the buffering duration so as to enable the first digitized ECG signal and the second digitized ECG signal to be synchronously streamed to the display; and

[0140] and wherein, upon initializing synchronized streaming of ECG signals to said display, said buffering means is adapted to defer said synchronized streaming for said buffering duration and to buffer in said buffer said first digitized ECG signal and said second digitized ECG signal of said first data packet sequence and said second data packet sequence received on said first communication link and said second communication link;

[0141] a frame packer configured and operable to successively retrieve and pack consecutive sets of signal samples of the first and second digitized ECG signals stored in the buffer according to their sampling order to form a sequence of consecutive signal frames to be streamed for display; and

[0142] A streamer is adapted to operate after the buffering duration has elapsed for streaming frames of the signal to the display at a frame rate.

[0143] Embodiment 24. A system according to embodiment 23, wherein the communication link monitor is suitable for processing the reception timing of the data packets to determine the standard deviation of the communication delay of each of the first communication link and the second communication link respectively; and wherein the buffering tool is suitable for setting the buffering duration to match a predetermined multiple of the maximum standard deviation among the standard deviations of the communication delays.

[0144] Embodiment 25. A system according to embodiment 23 or 24, wherein the frame encapsulator includes a synchronizer according to any one of embodiments 18 to 22, and is configured and operated to synchronize between signal samples of the first plurality of digitized signals and signal samples of the second plurality of digitized signals, and to identify and remove additional samples obtained in each of the first digitized signal or the second digitized signal due to the difference between the sampling rate of the first tool and the sampling rate of the second tool.

[0145] Embodiment 26. A system according to any one of Embodiments 23 to 25, wherein the frame encapsulator includes a resampler suitable for downsampling the first digitized ECG signal and the second digitized ECG signal to form the signal frame at a resolution suitable for presentation on the display.

[0146] It should be understood that the term electrocardiogram (ECG) is used in the above-described embodiments and in this disclosure to generally designate any type of biopotential signal to which the systems and methods of the present invention may be applied.

[0147] It should be understood that the above embodiments are cited by way of example, and the present disclosure is not limited to what is specifically shown and described above. On the contrary, the scope of the present disclosure includes combinations and sub-combinations of the various features described above, as well as variations and modifications thereof, which will occur to those skilled in the art upon reading the above description, and which are not disclosed in the prior art.

Claims

1. A method for synchronously streaming electrocardiogram (ECG) signals obtained from a plurality of medical devices to a display, the method comprising: providing a plurality of first digitized signals including a first reference digitized signal, whereby the plurality of first digitized signals are sampled by a first sampling tool from a plurality of first analog signals sensed by a plurality of first ECG sensors of a first medical device, and wherein one first analog signal among the plurality of first analog signals is selected as a reference analog signal, and the first reference digitized signal corresponds to the sampling of the reference analog signal by the first sampling tool; providing a plurality of second digitized signals including a second reference digitized signal, whereby the plurality of second digitized signals include one or more second digitized signals sampled by a second sampling means from one or more second analog signals sensed by one or more second ECG sensors of a second medical device simultaneously with sensing of the plurality of first analog signals, and the second reference digitized signal is simultaneously sampled by the second sampling means from the reference analog signal sensed by the first medical device; comparing the first digitized reference signal with the second digitized reference signal; Based on the comparing, synchronizing between the plurality of first digitized signals and the one or more second digitized signals; and The plurality of first digitized signals are streamed in parallel to the display in synchronization with the one or more second digitized signals.

2. The method according to claim 1, comprising: sensing the plurality of first analog signals by the plurality of first ECG sensors of the first medical device; in parallel, sensing the one or more second analog signals by the one or more second ECG sensors of the second medical device; Sampling the plurality of first analog signals using the first sampling tool to obtain the plurality of first digitized signals including the first reference digitized signal; as well as The one or more second analog signals and the reference analog signal are sampled by the second sampling tool to obtain the one or more second digitized signals and the second digitized reference signal.

3. The method according to claim 1, wherein: The synchronization includes: identifying, based on the comparing, additional samples obtained in each of the first digitized signal or the second digitized signal obtained from one of the first sampling tool or the second sampling tool, respectively, wherein the additional samples are generated by a difference between sampling rates of the first sampling tool and the second sampling tool; and The additional samples are removed from each of the first digitized signal or the second digitized signal prior to the streaming to the display.

4. The method according to claim 1, wherein: The sampling clocks of the first sampling means and the second sampling means operate at sampling rates close to a similar nominal sampling rate.

5. The method according to claim 1, wherein: Each frame displayed by the ECG signal on the display presents a time interval of the ECG signal that does not exceed a certain maximum duration, and wherein the reference analog signal is selected to be a first analog signal among the first analog signals that is non-periodic and non-stationary within the interval of the certain maximum duration.

6. The method according to claim 5, wherein: The reference analog signal is a far-field ECG signal.

7. The method according to claim 1, wherein: The first medical device and the second medical device include a plurality of ECG sensors adapted to sense the ECG signals in situ during cardiac operation.

8. The method according to claim 7, wherein: One or more of the following: - at least one of the first medical device and the second medical device is a catheter adapted to be inserted into a body for at least one of probing and treating a heart; and at least one of the first sampling means and the second sampling means is connected to a plurality of ECG sensors of the catheter adapted to measure the heart activity in situ during the cardiac operation; - At least one of the first medical device and the second medical device is a surface ECG device comprising a plurality of ECG sensors suitable for being placed on, outside the body, for detecting the heart; and at least one of the first sampling tool and the second sampling tool is connected to the plurality of ECG sensors.

9. The method according to claim 1, wherein: The first medical device is a catheter adapted to be positioned within the heart during operation to sense intracardiac electrogram (IEGM) signals, and the reference analog signal is an ECG signal obtained from at least one ECG sensor of the catheter.

10. The method according to claim 9, wherein: The catheter is suitable for being inserted into the heart, and the multiple ECG sensors of the catheter include multiple ECG sensors arranged in the catheter for contacting tissue of the heart during operation of the catheter, and at least one ECG sensor arranged in the catheter so that it is spaced apart from the tissue of the heart during the operation of the catheter, thereby enabling the far-field ECG signal of the heart to be sensed via the at least one ECG sensor and utilizing the far-field ECG signal as the reference analog signal.

11. The method of claim 1, comprising applying further processing to the synchronized first and second digitized signals to analyze or calculate one or more properties associated with the electrocardiogram.

12. A method for synchronously streaming electrogram (ECG) signals obtained from a plurality of medical devices to a display, the method comprising: receiving, via a first data link associated with a first tool of a first medical device, a first sequence of data packets including a plurality of first digitized ECG signals periodically packaged and transmitted by the first tool over the first data link; receiving, via a second data link associated with a second tool of a second medical device, a second sequence of data packets including one or more second digitized ECG signals periodically packaged and transmitted by the second tool over the second data link; monitoring the reception timing of data packets periodically transmitted on each of the first data link and the second data link to determine a statistical value of communication delay in each of the data links; determining a buffer duration based on the statistical value of the communication delay, and delaying the synchronous streaming of the ECG signal to the display by the buffer duration; as well as upon initiating synchronized streaming of ECG signals to the display, deferring the synchronized streaming for the buffering duration; buffering the first digitized ECG signal and the second digitized ECG signal of the first data packet sequence and the second data packet sequence received on the first data link and the second data link in a buffer; successively packing the consecutive sets of signal samples of the first digitized ECG signal and the second digitized ECG signal retrieved from the buffer according to a sampling order of the consecutive sets of signal samples of the first digitized ECG signal and the second digitized ECG signal retrieved from the buffer to form a consecutive sequence of signal frames to be streamed for display; as well as streaming the signal frames to the display at a frame rate as the buffer duration elapses; The communication delays are thereby mitigated and pseudo real-time synchronous streaming of ECG signals obtained via data links associated with multiple medical devices is enabled to the display.

13. The method according to claim 12, wherein: The repackaging includes performing the method according to claim 1, which is used to synchronize between the signal samples of the first digitized ECG signal and the second digitized ECG signal, and identify and remove extra samples obtained in each of the first digitized signal or the second digitized signal due to the difference between the sampling rates of the first tool and the second tool.

14. The method according to claim 12, wherein: The repackaging includes downsampling the signal samples of the first digitized ECG signal and the second digitized ECG signal of the set to form the signal frame at a resolution suitable for presentation on the display.

15. The method according to claim 12, wherein: The consecutive sets of signal samples used to form the signal frame include overlapping signal samples.

16. The method of claim 12, comprising determining a standard deviation of the communication delay for each of the first data link and the second data link, respectively, and setting the buffer duration to match a predetermined multiple of a maximum standard deviation of the standard deviations of the communication delays.

17. The method according to claim 12, wherein: The buffering duration is set to a multiple of at least three times the maximum standard deviation of the delays while not exceeding a predetermined maximum buffering duration allowed for the streaming.

18. A system for synchronously streaming electrocardiogram (ECG) signals obtained from a plurality of medical devices to a display, the system comprising: a synchronizer adapted to receive first and second pluralities of digitized signals sampled by the first and second sampling tools, respectively, from corresponding first and second pluralities of analog signals sensed by ECG sensors of the at least one first medical device and the at least one second medical device, respectively; wherein the first plurality of digitized signals comprises a first reference digitized signal, the first reference digitized signal is sampled by the first sampling means from an analog signal selected as a reference analog signal of the first plurality of analog signals, and the first reference digitized signal is sensed by an ECG sensor selected as a reference ECG sensor of the first medical device; and wherein the second plurality of digitized signals comprises a second reference digitized signal, the second reference digitized signal is sampled by the second sampling means from the reference analog signal, and the second reference digitized signal is sensed by the reference ECG sensor of the first medical device; The synchronizer comprises: - a comparator adapted to perform a comparison between the first digitized reference signal and the second digitized reference signal; and a sampling processor adapted to synchronize the plurality of first digitized signals with the plurality of second digitized signals based on the result of the comparison between the first reference signal and the second reference signal performed by the comparator; thereby obtaining a synchronization signal of the first plurality of digitized signals and the second plurality of digitized signals; and The synchronizer is associated with a streamer adapted to stream the synchronization signal of the first plurality of digitized signals and the second plurality of digitized signals in parallel for display on the display.

19. The system of claim 18, wherein: The sampling processor is configured and operable to synchronize between the plurality of first digitized signals and the plurality of second digitized signals by: - based on the result of the comparing, identifying additional samples obtained in each of the first plurality of digitized signals or one of the second plurality of digitized signals obtained from one of the first sampling tool or the second sampling tool, respectively; and wherein the additional samples are generated by a difference between sampling rates of the first sampling tool and the second sampling tool; and - removing said additional samples from each of said digitized signals, said first digitized signal or said second digitized signal.

20. The system according to claim 18, wherein: The first plurality of digitized signals and the second plurality of digitized signals are ECG signals; and wherein each frame of the ECG signal displayed on the display presents a time interval of the ECG signal that does not exceed a certain maximum duration; and the reference analog signal is selected to be a first analog signal among the first analog signals that is non-periodic and non-stationary within the interval of the certain maximum duration.

21. The system of claim 20, wherein: The at least one first medical device comprises a catheter adapted to be positioned within the heart during operation thereof to sense an intracardiac electrogram (IEGM) signal; and wherein the reference ECG sensor is an ECG sensor arranged in the catheter so that it is spaced apart from tissue of the heart during the operation and adapted to obtain the reference analog signal as a far-field ECG signal.

22. The system of claim 18, wherein: One or more of the following: - the system further comprises at least one of: the at least one first medical device; the at least one second medical device; the first sampling tool; the second sampling tool; and the display; - the at least one first medical device and the at least one second medical device comprise a plurality of ECG sensors adapted for sensing ECG signals in situ during cardiac operation; - at least one of the first medical device and the second medical device is a catheter adapted to be inserted into a body for at least one of probing and treating a heart; and at least one of the first sampling tool and the second sampling tool is connected to a plurality of ECG sensors of the catheter; - At least one of the first medical device and the second medical device is a surface ECG device comprising a plurality of ECG sensors suitable for being placed on, outside the body, for detecting the heart; and at least one of the first sampling tool and the second sampling tool is connected to the plurality of ECG sensors.

23. A system for synchronously streaming electrocardiogram (ECG) signals obtained from a plurality of medical devices to a display, the system comprising: A data communication tool, which is configured and operable to receive corresponding first and second data packet sequences via first and second communication links associated with the first and second tools, respectively; whereby the first data packet sequence includes a plurality of first digitized ECG signals, which are sampled from an ECG sensor of at least one first medical device and periodically packaged and transmitted by the first tool on the first communication link; and the second data packet sequence includes a plurality of second digitized ECG signals, which are sampled from an ECG sensor of at least one second medical device and periodically packaged and transmitted by the second tool on the second communication link; A packet synchronizer, the packet synchronizer comprising: a communication link monitor connected to the data communication tool and adapted to monitor the reception timing of data packets transmitted on each of the first communication link and the second communication link and thereby determine a statistical value of a communication delay for each of the first communication link and the second communication link; and - a buffering tool, the buffering tool comprising a buffer and being configured and operable to determine a buffering duration using the statistical value of the communication delay, by which the first digitized ECG signal and the second digitized ECG signal of the data packet are buffered and the streaming of the ECG signal to the display is postponed by the buffering duration so that the first digitized ECG signal and the second digitized ECG signal can be synchronously streamed to the display; and wherein, upon initializing synchronous streaming of the ECG signal to the display, the buffering tool is adapted to postpone the synchronous streaming by the buffering duration and to buffer in the buffer the first digitized ECG signal and the second digitized ECG signal of the first data packet sequence and the second data packet sequence received on the first communication link and the second communication link; a frame packer configured and operable to successively retrieve and pack the consecutive sets of signal samples of the first digitized ECG signal and the second digitized ECG signal stored in the buffer according to a sampling order of the consecutive sets of signal samples of the first digitized ECG signal and the second digitized ECG signal stored in the buffer to form a consecutive sequence of signal frames to be streamed for display; and A streamer is adapted to operate when the buffering duration elapses for streaming frames of the signal to the display at a frame rate.

24. The system of claim 23, wherein: The communication link monitor is adapted to process the reception timing of the data packets and thereby determine the standard deviation of the communication delay for each of the first communication link and the second communication link, respectively; and wherein the buffering tool is adapted to set the buffering duration to match a predetermined multiple of the maximum standard deviation of the standard deviations of the communication delays.

25. The system of claim 23, wherein: The frame encapsulator includes a synchronizer according to claim 18, and is configured and operated to synchronize between signal samples of the first plurality of digitized signals and signal samples of the second plurality of digitized signals, and to identify and remove extra samples obtained in each of the first digitized signal or the second digitized signal due to a difference between a sampling rate of the first tool and a sampling rate of the second tool.

26. The system of claim 23, wherein: The frame packer includes a resampler adapted to downsample the first digitized ECG signal and the second digitized ECG signal to form the signal frame at a resolution suitable for presentation on the display.

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