System and method of synchronization of biopotential signals

Abstract

To synchronize biopotential signals.SOLUTION: The invention provides synchronization between first and second pluralities of digitized ECG signals that are sampled from a plurality of medical devices by first and second non-synchronized utilities. One of analog ECG signals, preferably a far-field ECG, is selected for reference and sampled by both the non-synchronized utilities thereby yielding respective first and second digitized reference ECG signals. The reference ECG signals are compared and the results of the comparison are used for synchronization between the first and second pluralities of digitized ECG signals. Accordingly, the techniques of the invention facilitate concurrent synchronized streaming to a display, of a plurality of digitized ECG signals from a plurality of non-synchronized medical devices.SELECTED DRAWING: Figure 3A

Description

[Technical field]

[0001] The present invention relates to the field of signal processing of physiological signals, and in particular to the synchronization of biopotential signals, such as electrocardiogram (ECG) electrograms (EGMs) and intracardiac electrograms (IEGMs) used for electrocardiographic monitoring in medical devices. [Background technology]

[0002] A wide range of medical devices involve the placement of a probe, such as a catheter, inside the body of a patient. One medical device in which these types of probes, or catheters, have proven extremely useful is in the treatment of cardiac arrhythmias. Cardiac arrhythmias and atrial fibrillation remain particularly prevalent and dangerous medical conditions, especially in the elderly population.

[0003] Diagnosis and treatment of cardiac arrhythmias includes mapping the electrical properties of cardiac tissue, particularly the endocardium and cardiac volumes, and selectively ablating cardiac tissue by electrical application. Catheters are inserted into and optionally around the cardiac chambers during such procedures. In most procedures, multiple catheters are inserted into the patient. The catheters may include mapping catheters, ablation catheters, temperature sensing catheters, and image sensing catheters. Some catheters are dedicated for placement in specific parts of the anatomy, e.g., coronary sinus, esophagus, atrium, ventricle. Catheters have multiple electrical channels, some with more than others, depending on the number of sensors and electrodes included in each catheter. The number and type of catheters vary depending on the procedure and the physician's preferred workflow. During the procedure, the cardiac electrical activity is monitored from catheter electrodes and sensors, as well as from 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 it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 is a schematic diagram illustrating a catheter-based electrophysiological mapping system 10, in accordance with one embodiment of the present invention. [Diagram 2] 1 is a schematic diagram of a catheter adapted to provide a reference signal suitable for use with synchronization systems and methods, according to some embodiments of the present invention. [Figure 3A] FIG. 1 is a block diagram illustrating a configuration of an ECG signal synchronization system 100 according to an embodiment of the present invention. [Figure 3B] 1 is a flow diagram illustrating a method 180 for synchronization between digitized ECG signals, according to an embodiment of the present invention. [Figure 4A] FIG. 1 is a block diagram showing a configuration of an ECG signal synchronization system 100 according to another embodiment of the present invention; [Figure 4B] 1 is a flow diagram illustrating a method 190 for synchronization between digitized ECG signals, according to another embodiment of the present invention.

[0005] In the drawings of the present invention, like reference numerals are used to indicate like modules / elements of the present invention, or elements / modules having like functionality. Thus, unless otherwise stated, a description of a module / element with respect to a particular embodiment of the present invention should be understood to apply to all embodiments of the present invention in which such module / element is incorporated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] Recent technological advances have significantly increased the number of sensors and electrodes that can be included on a catheter. 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. The large number of electrodes allows a physician to simultaneously capture electrical activity from multiple locations within the heart chamber. Position sensors on the catheter record the location where the electrical activity is sampled. The electrodes on the distal end include electrodes configured to engage the tissue wall of the heart and sense near-field biopotential signals, and may also include a reference electrode immersed in the blood pool and configured to sense the far-field biopotential signal(s). The far-field signals may be used to remove any far-field components that may be captured by the electrodes configured to engage the tissue wall of the heart and sense the near-field signals.

[0007] There is a need in the art for novel systems and methods (e.g., medical devices) that allow for signal collection from high density catheters. Conventional medical devices already deployed in medical operating facilities typically have limited channels for collecting and simultaneously sampling sensory signals from high density (HD) catheters with, for example, 50 or more biopotential sensors (e.g., ECG electrodes), but cannot accommodate all sensory channels of such HD catheters. During a medical procedure (diagnosis and / or treatment), there is a need to stream the output from all sensors (ECG sensors) of multiple medical devices for synchronous display to a physician. However, existing / deployed hardware that is typically adapted to collect, sample, and communicate biopotential signals (electrocardiogram, ECG) from body surface electrodes and other catheters is typically not suitable for further collecting, sampling, and communicating additional sensory signals obtained from high density catheter(s). Simply adding conventional hardware for acquiring, sampling, and / or communicating signals from an HD catheter (e.g., separate from already deployed hardware used for other electrophysiological device signals, such as body surface electrodes) does not facilitate synchronized sampling and / or communication of signals from the HD catheter along with signals from other electrophysiological devices. One reason is that such added hardware typically does not share the same sampling clock, and already deployed medical devices do not facilitate direct synchronization of their sampling clocks with the sampling clock of the added hardware. Another reason is that the added hardware and the existing hardware communicate the signals acquired / sampled thereby (e.g., for streaming to a display) over separate communication data links, which may result in different latency for the communication.

[0008] The present invention therefore provides novel systems and methods for solving these problems and enabling synchronous streaming of biopotential signals derived from HD catheters with biopotential signals derived from other electrophysiological devices, such as body surface electrodes and other catheters. In particular, in certain aspects, the present invention facilitates achieving such synchronous streaming without the need to replace existing medical devices (e.g., already in place), thus enabling the incorporation of the use of HD catheters into existing medical facilities in a cost-effective manner.

[0009] According to certain aspects of the invention, sample synchronization between the signals sampled by the existing hardware and the added hardware may be achieved by utilizing an output from one of the sensors of the HD catheter (hereinafter also referred to as a "reference analog signal") to synchronize between the sensory signals obtained from the HD catheter and the sensory signals obtained from the other electrophysiological device. The reference analog signal is split and provided for sampling by both the existing hardware and the added hardware, thereby resulting in two digital reference signals representing the sampling of the reference analog signal according to the sampling clocks of the respective existing hardware and the added hardware. In practice, these samplings may not be synchronized, so that extra sample(s) may be included in either one of the two digital reference signals for a given period due to differences in the sampling clocks at which they are sampled. However, since the two digital reference signals are sampled from a common reference analog signal, such extra sample(s) may be identified by a comparison of the two digital reference signals. The identified redundant sample(s) are then removed from the respective digital signals in which they are present, thus synchronizing the samples of the digital signals sampled by the two sampling utilities and enabling their synchronous streaming to the display. The comparison between the digital reference signals may be performed frequently enough to identify and remove a single redundant sample or just a few redundant samples (e.g., up to three) each time so as to maintain continuous synchronization between the digital signals while avoiding apparent information gaps in the displayed signal.

[0010] In order to facilitate the above procedure of sample synchronization by accurate and unambiguous identification of redundant samples, the signal selected for use as the reference analog signal for synchronization must satisfy certain prerequisites, such as: the signal must be continuously non-stationary (e.g., have values ​​that are not continuously constant); the signal must be non-periodic over the respective duration of the time interval in which the comparison is performed, at least in order to identify redundant sample(s) between the first digital reference signal and the second digital reference signal.

[0011] The inventors have found that far-field biopotential signals, e.g., far-field IEGMs acquired from an HD catheter, meet these prerequisites for synchronization and are suitable for use as a reference signal for synchronization. This is for the following reasons: 1. Far-field biopotential signals are always present during a medical procedure, in contrast to near-field signals, which, e.g., would only be captured based on contact or proximity of an electrode to tissue (e.g., skin / heart wall). 2. Far-field biopotential signals are biosignals and therefore not periodic. Therefore, in certain embodiments of the present invention, far-field biopotential signals, e.g., those acquired from the far-field (IEGM sensors of HD catheters), are specifically selected as the reference analog signal used for the synchronization process described above and in more detail below.

[0012] Please refer to FIG. 1, which illustrates a representative catheter-based electrophysiology mapping and ablation system 10. The system 10 includes multiple catheters that are percutaneously inserted by a physician 24 through a patient's vascular system into a chamber or vasculature of the heart 12. Typically, a delivery sheath catheter is inserted into the left or right atrium near a desired location of the heart 12. One or more catheters may then be inserted into the delivery sheath catheter to reach a desired location within the heart 12. The multiple catheters may include catheters dedicated to sensing Intracardiac Electrogram (IEGM) signals, catheters dedicated to ablation, and / or catheters dedicated to both sensing and ablation. An exemplary catheter 14 configured for sensing IEGMs is illustrated herein. The physician 24 may place a distal tip 28 of the catheter 14 in contact with the heart wall to sense a target site in the heart 12. For ablation, the physician 24 may similarly place a distal end of an ablation catheter in contact with a target site for tissue ablation.

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

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

[0015] The system 10 includes one or more electrode patches 38 positioned for skin contact on the patient 23 to establish a positional reference for the location pads 25 and impedance-based tracking of the electrodes 26. For impedance-based tracking, a current may be directed to the electrodes 26 and sensed at the electrode skin patch 38, thereby triangulating the location of each electrode through the electrode patch 38. Details of impedance-based position tracking techniques are described in U.S. Patent Nos. 7,536,218, 7,756,576, 7,848,787, 7,869,865, and 8,456,182.

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

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

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

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

[0020] In this embodiment, the catheter 14 is a high density (HD) catheter 14 having, for example, 50 or more biopotential sensors (ECG electrodes). One embodiment of such a high density catheter 14 is shown diagrammatically in FIG. 2. The HD catheter 14 includes a shaft 14H having a position sensor 29 typically embedded in or near a distal end 28 of the shaft 14H for tracking the position and orientation of the distal tip 28. The HD catheter 14 in this particular non-limiting embodiment includes a pusher rod 14P passing through the shaft 14H and a number of splines 22 on which a number of near field intracardiac electrogram sensors / electrodes 26 are disposed. The splines 22 are disposed near the distal end to form an expandable distal tip assembly that may be deflectable outwardly from the catheter by moving the pusher rod 14P, thereby engaging the near field intracardiac electrogram sensors / electrodes 26 into contact with the tissue wall of the heart for sensing near field signals IEGM signals (e.g., activation biopotential signals) when the catheter is located within the heart. The catheter 14 also includes a far-field intracardiac electrogram sensor / electrode 14F (located on the pusher rod 14P in this example). The far-field IEGM sensor / electrode 14F is configured to be maintained at a distance from the endocardial tissue during operation of the catheter while immersed in the blood pool to measure / sense far-field biopotential signals (far-field IEGMs). To this end, the far-field IEGM sensor / electrode 14F is generally configured to be larger than the near-field electrode 26 and to have sufficient sensitivity to sense the far-field IEGM signals. The far-field signals may be used, for example, to filter out far-field components that may be captured by the near-field electrode 26.

[0021] It should be understood that the term "biopotential signal / biopotential sensor" is used herein to denote electrophysiological signals or sensors thereof, such as, but not limited to, electrocardiograms (ECGs), electrograms (EGMs), and intracardiac electrograms (IEGMs). It should also be noted that, without loss of generality, the terms "electrocardiograms and ECGs" are used interchangeably herein to generally designate 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 denote biopotential signals, such as ECGs, EGMs, and IEGMs, that are measured by suitable far-field sensors / electrodes without contacting the patient's body tissue (e.g., maintained spaced / separated from tissue during measurement, but potentially immersed in body fluids such as a blood pool). Conversely, the term "near-field" is used herein with respect to biopotential signals that are measured by sensors / electrodes designed to contact the patient's body tissue (e.g., skin tissue or intracardiac tissue) to make the measurement.

[0022] 1 , as mentioned above, electrophysiological devices including multiple ECG patches attached externally to the patient's body / skin, e.g., surface ECG device 38, 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 a workstation 55. The PIU 30 may be adapted, for example, to apply analog-to-digital conversion (sampling) to signals received from the electrophysiological devices connected to it, and / or to pack these signals into data packets and communicate them to the workstation 55.

[0023] However, in system 10, e.g., a system already deployed in a medical surgical facility, the PIU 30 may have limited channels for collecting and simultaneously sampling / packing sensory signals and may not be able to accommodate the multiple sensory channels provided by the multiple electrodes 26 of the HD catheter 14 as illustrated in FIG. 2.

[0024] Thus, in some implementations, the system 10 includes an additional signal processing unit (SPU) 31 configured and operable to complement / extend the functionality of the PIU 30 to enable connection of additional medical devices, such as the HD catheter 14, to the system 10. The SPU 31 is configured and operable to have one or more functionalities similar to the PIU 30 described above (but not necessarily all of the PIS functionalities) to support the connection of additional medical devices to the system 10. For example, the SPU 31 provides an interface for collecting and sampling / packing signals from the HD catheter 14 or other electrophysiological devices, and possibly for connecting such electrophysiological devices to the ablation energy generator 50 and / or recorder 11. Additionally, 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.

[0025] Reference is now made to Figure 3A, a block diagram illustrating the configuration of a synchronization subsystem 100 of system 10 according to some embodiments of the present invention. In this embodiment, each of SPU 31 and PIU 30 includes a respective sampling utility 120A and 120B. Each of sampling utilities 120A and 120B is configured and operable to sample analog biopotential signals sensed by a respective medical device connected thereto, convert them to digitized biopotential signals 151 and 152, and communicate them to workstation 55. Workstation 55 then processes at least some of these biopotential signals 151 and 152 for display on display 27 (while optionally also utilizing these signals to perform other processing, such as ECG calculation, mapping, recording, etc.).

[0026] Because the sampling clocks CLK1 and CLK2 of the respective sampling utilities 120A and 120B of SPU 31 and PIU 30 are not inherently synchronized (e.g., SPU 31 and PIU 30 may not include direct synchronization means for synchronizing their sampling clocks), the workstation 55 is configured to synchronize the signals obtained therefrom, thereby compensating for this lack of synchronization.

[0027] To accomplish that, one selected sensor channel 121R of the HD catheter 14 is split by a splitter 33 and directed for connection to both the SPU 31 (to which the remaining sensor channels 121 of the HD catheter 14 are connected) and to an available port in the PIU 30 for sampling thereby. The splitter 33 may 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) that, in this particular embodiment, is obtained from a sensory channel of the HD catheter 14 (e.g., from its far-field IEGM sensor). Digitized reference signals 151R and 152R obtained from the sampling of that common analog biopotential signal 121R by the SPU 31 and the PIU 30, respectively, are then provided to a synchronization system 100 of the workstation 55 and used to identify and correct for lack of synchronization between the sampling utilities of the SPU 31 and the PIU 30, as described below.

[0028] To this end, the synchronization system 100 is configured and operable to synchronize between digital biopotential signals 151 and 152 sampled by two or more asynchronous sampling utilities 120A and 120B from a plurality of analog biopotential signals sensed by biopotential sensors (such as ECG and / or IEGM electrodes) 111A, 111B of a plurality of medical devices connected thereto, e.g., 110A and 110B. More specifically, in this embodiment, the system 100 includes a synchronizer (peripheral controller) 150 adapted to synchronize samples of a first plurality of digitized signals 151 and a second plurality of digitized signals 152 sampled by a first asynchronous sampling utility 120A and a second asynchronous sampling utility 120B, respectively. To achieve this, the synchronizer 150 receives a first plurality of digitized signals 151 obtained by a first sampling utility 120A and including a first digitized reference signal 151R obtained from sampling of the reference analog signal 121R by the first sampling utility, and also receives a second plurality of digitized signals 152 obtained by a second sampling utility 120B and including a second digitized reference signal 152R obtained from sampling of the reference analog signal 121R by the second sampling utility.

[0029] The synchronizer 150 includes a comparator 154 adapted to compare the first digitized reference signal 121R and the second digitized reference signal 151R to identify discrepancies between their samples due to differences in sampling rates between the first sampling utility 120A and the second sampling utility 120B (based on the fact that the first reference signal and the second reference signal are sampled from a copy of the same underlying analog reference signal 152R). In particular, the comparator 154 is adapted to identify when the shift between the two digitized reference signals is more than one full digitized sample, in which case there is one (or optionally several samples, e.g. three) extra samples that should be removed to synchronize the signals from the first sampling utility 120A and the second sampling utility 120B. It should be noted that if a shift smaller than one sample is identified, the redundant samples do not need to be removed and the signals from the first sampling utility 120A and the second sampling utility 120B may be considered synchronized until the shift grows to a duration of one or more samples. Furthermore, the synchronizer 150 also includes a sample processor 156 adapted to synchronize the samples of the first digitized signals 151 with the samples of the second digitized signals 152 based on the results / discrepancies identified by the comparator 154. More specifically, based on the redundant samples identified by the comparison, the sample processor 156 modifies a sequence of samples in each digitized signal of one of the first and second plurality of digitized signals to be streamed to the display such that the sequence of samples in each such digitized signal corresponds to a sequence of samples of the other of the first and second plurality of digitized signals for the same time frame. The sample processor 156 thereby provides synchronization signals 151S and 152S for the first and second plurality of digitized signals 151 and 152, respectively.

[0030] Accordingly, the system 100 may include a streamer 170 (e.g., and / or a display adapter) 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.

[0031] It should be understood that in various implementations 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 thereof, or for a patient's medical condition. For example, the biopotential / ECG signals synchronized by the system 100 may be stored for further analysis, and / or used for activation sequences i that represent the markings in relation to a computational anatomical map and / or display their relationship to a site of interest, such as the location where ablation energy was applied.

[0032] The operation of the above-described system 100 will now be described in more detail with reference to FIG. 3B, which shows a flow diagram illustrating a method 180 for synchronizing between digitized biopotential signals sampled by an asynchronous sampling utility, in accordance with an embodiment of the present invention.

[0033] At 181, a selected analog reference signal 121R is provided for sampling by each of the asynchronous sampling utilities 120A and 120B. Preferably, in various embodiments of the present 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 / configured to serve as the reference analog signal 121R that is sampled by both / each sampling utility.

[0034] An analog biopotential signal 121 from medical device 110A, and possibly from additional medical devices such as 111A, is sampled by a first sampling utility 120A simultaneously with the sampling of an analog reference signal 121R. Sampling by the first sampling utility 120B thus results in a first plurality of digitized signals 151 provided at 182. As shown at 183, the first plurality of digitized signals 151 thus provided includes a first reference digitized signal 151R obtained by simultaneous sampling of the analog reference signal 121R by the first sampling utility 120A along with the sampling of signal 121.

[0035] Similarly, the analog signal 122 from medical device 110B, and possibly analog signals from additional medical device(s), such as 111B, are sampled by the second sampling utility 120B contemporaneously with the sampling of the analog reference signal 121R by the second sampling utility 120B. Thus, provided at 184 is a second plurality of digitized signals 152 sampled by the second sampling utility 120B. As shown at 185, the second plurality of digitized signals 152 includes a second reference digitized signal 152R obtained by the contemporaneous sampling of the analog reference signal 121R by the second sampling utility 120B along with the sampling of signal 122.

[0036] The sampling clocks CLK1 and CLK2 of each sampling utility 120A and 120B operate at frequencies such that they operate at similar nominal sampling rates, although they may be designed to operate at similar nominal sampling rates. This may be due, for example, to manufacturing variations or any number of environmental or power conditions that affect the operating frequency of the clocks (e.g., affecting frequency drift). The frequency of the sampling clocks may be, for example, on the order of 20 kHz, although the difference between these frequencies may in practice be substantially lower (e.g., one of the clocks may operate for a nominal frequency of 20,000 Hz and the other may drift by 1 Hz or more and operate at, for example, 19,999 Hz). In general, it should be noted that the frequency difference between the sampling utilities 120A and 120B may not necessarily be constant or fixed, and may in some embodiments vary due to various conditions (e.g., power supply or temperature variations). Thus, the techniques of the present invention for synchronizing samples of these signals are also adapted for use where the different frequencies between the different sampling clocks are not constant.

[0037] Thus, taking into account such variations in sampling frequency, if one attempts to display the signals obtained from the different sampling utilities 120A and 120B consecutively (e.g., based on the sequential samples obtained from these sampling utilities without recognizing or taking into account their frequency differences) under the assumption that their sampling clocks are synchronized, the shifts between the displayed signals of the different sampling utilities will accumulate over time.

[0038] Thus, method actions 186 and 187 of method 180 are implemented by the comparator 154 and the sample processor 156, respectively, to synchronize the signal samples sampled by the two sampling utilities 120A and 120B, thereby preventing / mitigating the above-mentioned signal shifts and providing a coherent and timely aligned presentation of the signals to the physician.

[0039] At 186, the comparator 154 compares (e.g., by cross-correlation) the first digitized reference signal 151R and the second digitized reference signal 152R to identify corresponding sections of samples therebetween. Thus, the comparison performed at 186 identifies redundant sample(s) when one of the first and second sampling utilities (e.g., 120B) operates at a higher sampling rate. In such a case, the comparison performed at 186 provides an indication of redundant sample(s) in the section of samples of the two digitized reference signals 152R sampled by the faster sampling utility (e.g., 120B) as compared to the corresponding section of the digitized reference signal 151R sampled by the other sampling utility (e.g., 120A). In order to synchronize the signals from the first and second sampling utilities, in operation 187, excess samples are removed from the corresponding time frames of all signals that are to be displayed on the display 27 and that are sampled by the sampling utility operating at the higher sampling rate (e.g., 120B).

[0040] To this end, operation 186 as well as subsequent operation 187 may be performed iteratively to process and synchronize the time frame portions of the signals of the first and second sampling utilities to be displayed on the display 27. In this regard, it should be understood that successive iterations are necessarily performed to compare successive signal portions of the reference signal, and generally, in some embodiments, the iterations are performed at intervals small enough to allow for the capture and removal of up to a predetermined maximum number of redundant samples in each iteration (while preferably not much more frequently than that so as not to impose overhead on the processing system of the workstation 55 with unnecessary iterations).

[0041] In various embodiments of the invention, a predefined threshold associated with the maximum number of redundant samples to be identified in each iteration may select one or less redundant samples (e.g., a threshold of up to three redundant samples to be identified in each iteration). Preferably, the iterations are performed with a sufficiently small time interval to facilitate the identification of only a maximum of one redundant sample in each iteration (threshold of one). Operating with such a small threshold (preferably one and not more than three) may be important to prevent the presentation of significant information gaps in the signal displayed to the physician (gaps that may be formed if a larger number of redundant samples are removed at once / from a single frame). Thus, the maximum time interval ΔT between successive iterations may be selected. max is the maximum excess sample number threshold ΔS max and the expected absolute maximum difference ΔF between the sampling speed F1 at which the first sampling utility can operate and the sampling speed F2 at which the second sampling utility can operate. max For example, in some embodiments, the maximum time interval may be calculated based on ΔT max = ΔS max / ΔF max and the maximum difference between the sampling rates ΔF max is 10Hz, and the additional sample threshold ΔS max If ΔT is 1, successive iterations are performed at least once for each 100 ms time frame of the signal. In practice, in some embodiments, the iterations are performed at least once for each signal frame to be displayed on the display 27, or for the maximum time interval ΔT mentioned above. max More may be performed if required by

[0042] To this end, in operation 187, the sample processor 156 operates to remove from the corresponding section of the signal obtained from the sampling utility, the redundant samples sampled at the faster sampling rate (e.g., 120B) by the sampling utility operation. The removal of the redundant samples is performed from the signal of the faster sampling utility and presented on the display 27. In this regard, it should be appreciated that what is actually identified in operation 186 are the sections / time frames of the signal obtained from the faster operating sampling utility (e.g., 120B) in which there is one or more redundant sample(s) when compared to the corresponding sections / time frames of the signal obtained from the other sampling utility (e.g., 120A). In general, the particular redundant sample(s) to be removed from within each such section / time frame may generally be arbitrary. Nonetheless, in some embodiments of the present invention, some criteria may optionally be applied to the selection of the particular indexes at which the additional samples are removed from these sections to ensure that substantial information is not lost from the display of the signal by the removal of the additional samples. One such criterion that may be applied in some embodiments of the present invention is that the excess samples to be removed are not removed from consecutive sampling indexes such that their removal does not create obvious gaps / jumps in the displayed signal (e.g., the removed excess samples will be sparsely distributed). Another such criterion that may be applied in some embodiments is that the excess samples to be removed from the signal are not selected for removal from extreme points of the signal (i.e., selected at sampling indexes that do not fall on extreme points) so that picks / valleys in the signal are properly displayed.

[0043] Thus, in operation 187, the sample processor synchronizes (156) the first and second sampling utility signals (at least those intended to be displayed) based on the results of the comparison made by the comparator 154 in operation 186 by removing the redundant samples identified by said comparison from the respective sections / time frames of the signals in which the redundant samples are identified. Thus, in operation 188, the synchronization signals obtained in operation 187 may be packed / compiled into a display frame (e.g., showing multiple synchronization signals from both sampling utilities aligned with each other) and streamed for presentation on the display. The streaming may be performed at the frame rate of the display, whereby each displayed frame presents a corresponding / aligned time section of the multiple synchronization signals. Thus, the operations of method 180 may be performed iteratively to prepare a set of synchronization signals for each displayed frame.

[0044] It should further be noted that typically in various embodiments of the present invention, the sampling resolution of the synchronized signals in acts 186 and 187 is set to be greater than the display resolution in each time frame of the displayed frame (e.g., such that for each displayed time frame, the number of samples / display dots of the signal actually displayed on the display is less than the actual number of samples in the synchronized signals). Thus, in preparation for the display frame in act 188, the synchronized biopotential signals 151S and 152S obtained from acts 186 and 187 may be downsampled to match the display resolution. This downsampling facilitates avoiding noticeable gaps appearing in the display frame due to the omission of excess samples from the display frame (the process of omission of sparse excess samples from the high resolution signal as obtained from 187 is followed by downsampling of the signal to a lower display resolution to smooth / blur any information gaps if formed by such omission).

[0045] In this regard, the inventors of the present invention have recognized that a far-field biopotential signal (such as a far-field intracardiac electrogram (far-field IEGM)) is particularly suitable for use as the reference analog signal 121 for the above-mentioned signal synchronization. In this regard, a reliable and accurate implementation of the method 180 for synchronizing biopotential signals, particularly biopotential signals acquired during a medical procedure, requires the proper selection of an appropriate biopotential analog signal to be used as the reference signal 121 for synchronization. A biopotential analog signal suitable for serving as the reference signal 121 for the purposes of the above-mentioned signal synchronization should be consistently non-stationary throughout the medical procedure (e.g., not a flat signal) and non-periodic at least within the duration of each display signal frame suitable for serving as a reference signal (typically on the order of 50 ms for a display of about 20 frames per second (FPS)). The inventors have found that, for example, a far-field intracardiac electrogram (far-field IEGM) signal acquired by a far-field sensor of the HD catheter 14 is suitable for serving as the reference signal 121. Indeed, since the sensor 14F configured for such measurements is sensitive to enable the signal to be measured without contacting tissue, resulting in a non-stationary signal being acquired throughout operation regardless of tissue contact, and also because its relatively high sensitivity picks up substantial noise that is incorporated into the far-field signal, thus rendering the far-field signal essentially non-periodic (e.g., at least within the relevant duration of each display signal frame), the far-field biopotential signal generally meets the above requirements for synchronization. Thus, the problem of synchronously connecting HD catheters 14 even to already deployed systems 10 where the PIU does not support sampling of signals from multiple sensors of such HD catheters 14 is made easier by the techniques of the present invention, preferably by utilizing the far-field IEGM signals acquired from such catheters.

[0046] Thus, in some embodiments of the present invention, a far-field biopotential signal (e.g., a far-field IEGM acquired from the catheter 14) is preferably used as the reference analog signal 121 for the above-mentioned synchronization. In this regard, it will be understood that in general, it is also possible to utilize one of the above-mentioned near-field signals as a reference signal for the synchronization of the present invention. However, this may provide less reliable / consistent results since those signals may be less noisy and therefore periodic (e.g., in line with the periodicity of cardiac activity) and also because acquiring a near-field signal depends on contact being maintained between the sensor / electrode sensing it and the body / cardiac tissue, and therefore, in the event of detachment of the sensor / electrode from the tissue, a flat / stationary signal may be acquired, which may prevent the implementation of the synchronization described above.

[0047] Thus, returning to 181 of the operating 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 utilities 120A and 120B is preferably a far-field biopotential signal, such as a far-field IEGM obtained from the catheter 14.

[0048] 3A, as shown, system 100 may optionally further include designated modules / utilities as illustrated by reference numerals 130, 140, and 160. The configuration and operation of these optional modules / utilities are described in more detail with reference to Figures 4A and 4B below, which show an example of a synchronization system 100 and method 190 according to some embodiments of the present invention.

[0049] As mentioned above, another discrepancy that may be introduced by adding hardware for collecting and communicating signals from an HD catheter separately from existing hardware used to collect and communicate signals of other electrophysiological devices is that the added hardware and the existing hardware typically communicate signals acquired thereby through separate communication data links, which may introduce different latency times into the communication and therefore may introduce discrepancies / time lags between the displayed signals of the added hardware and the existing hardware when they are displayed directly together.

[0050] Reference is now made jointly to Figures 4A and 4B, which illustrate the configuration and operation of a synchronization system 100 according to another embodiment of the present invention, adapted to apply communication / packet synchronization to synchronize between biopotential signals measured and collected by different medical devices and communicated to the system through different hardware. Figure 4A is a block diagram illustrating the configuration of the synchronization system 100 according to an embodiment of the present invention and its connections with other modules / utilities of the system 10. Figure 4B is a flow diagram illustrating a method 190 for synchronization between biosignals sensed by sensors of multiple medical devices, such as 110A and 110B of the system 10, and acquired by their associated respective PIU 30 and SPU 31 utilities.

[0051] The utilities 30 and 31 may be connected to medical devices 110A and 110B, respectively, and optionally to additional medical devices such as 111A and 111B, to receive the sensed analog biopotential signals 121 and 122 or digital biopotential signals 151 and 152. If the biopotential signals are received in analog form 121 and 122, the corresponding utility, i.e., utility 31 and / or 30, may include a respective sampling utility 120A or 120B adapted to sample the respective signal to obtain its digitized form 151 and 152. The TSPU 31 and PIU 30 utilities also include respective network adapters 124A and 124B configured and operable to establish respective communications data links 145A and 145B between the respective utilities associated therewith and the workstation 55 over a data communications network NET, for communicating the respective digital biopotential signals 151 and 152 acquired thereby to the workstation 55.

[0052] The network NET may be any suitable data communication network, such as, for example, a LAN or WIFI, or any other suitable data communication network to be implemented for communicating medical signals to the workstation 55 during a medical procedure. The communication data links 145A and 145B between the utilities 31 and 30 and the workstation 55 may be established, for example, based on the TCP / IP protocol or a similar protocol providing a reliable (e.g., verified) communication of data packets through the network. For this purpose, the network adapters 124A and 124B pack and transmit the respective biosignals 151 and 152 acquired by the respective utilities 31 and 30 in respective series of transmission data packets 141T and 142T, which are transmitted to the workstation 55 through the corresponding data links 145A and 145B established between the utilities 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 series of transmission data packets 141T and 142T are typically packed and transmitted by the utilities 31 and 30 at substantially constant time intervals Δt1 and Δt2 over time t, as shown in FIG. 4A.

[0053] The synchronization system 100 in this embodiment is adapted to monitor communication latency with different medical hardware (e.g., utilities 31 and 30) that collects biopotential signals measured by different medical devices, and accordingly adjust the display timing of the signals to mitigate across these communication latency, enabling their joint presentation in a timely and synchronized manner.

[0054] The synchronization system 100 includes a data communications utility 130 (e.g., a network adapter) configured and operable to establish a first communications data link 145A and a second communications data link 145B with the respective utilities 31 and 30, and to receive therethrough respective first receive sequences 141R and second receive sequences 142R of data packets in response to sequences 141T and 142T transmitted by the utilities 31 and 30. For this purpose, the first sequence of received data packets 141R includes a plurality of first digitized physiological / biopotential signals 151 sampled from a sensor of at least one first medical device 110A and packed and transmitted by the first utility 31 via the first communications link 145A, and the second sequence of received data packets 142R includes a plurality of second digitized physiological / biopotential signals 152 sampled from a sensor of at least one second medical device 110B and packed and transmitted by the second utility 30 via the second communications link 145B.

[0055] As mentioned above, the first sequence 141R and the second sequence 142R of data packets are preferably communicated utilizing a reliable / verified communications protocol such as TCP to ensure their consistent reception by the workstation 55, so that the signal portions packed by each data packet may be consistently / reliably displayed on the display 27 without loss of signal information due to miscommunication of the data packets.

[0056] However, typically verified / reliable transmission protocols are not well suited for real-time / quasi-real-time operation and may introduce variable time lags / latency in the communication. As a result of the variable latency in the communication, the time intervals between the reception of data packets in each of the first receive sequence 141R and the second receive sequence 142R, and possibly the order of their reception, may vary relative to the time intervals and order of their transmissions 141T and 142T. As a result, if the portions of the signals 151 and 152 provided by each of these data packets were actually presented on the display 27 in full real-time (i.e., as soon as the data packets are received), a variable time delay between the presentation of different biopotential signal portions would be introduced in their presentation to the physician, which may result in an inconsistent and possibly misleading presentation of the biopotential signal to the physician.

[0057] System 100 may therefore operate in pseudo-real-time, introducing some moderate time delay in the presentation, not exceeding some time delay threshold (e.g., up to 150 ms) between sensing of the biopotential signals and their presentation. Such pseudo-real-time operation facilitates consistent and ordered presentation of biopotential signals 151 and 152 to the physician (reducing network latency), but the introduced time lag is small enough to be unnoticeable / meaningless to the medical procedure, while on the other hand is sufficient to establish a consistent presentation of the biopotential signals on display 27, so that the actual presentation of the biopotential signals to the physician with such moderate delay does not impair the medical procedure.

[0058] To achieve that, the system 100 includes a packet synchronizer 140 including a data link monitor 142 and a buffering utility 145. The communication link monitor 142 is connected to the data communication utility 130 and adapted to monitor the timing of receipt of data packets of the data packet sequences 141R and 142R received over the first data link 145A and the second data link 145B, respectively. The communication link monitor 142 thereby determines latency statistics of the communication of the data packets over the first data link 145A and the second data link 145B, respectively. The buffering utility 145 is configured and operable to utilize the latency statistics of the data links 145A and 145B to determine a buffering period ΔT for delaying streaming of the biopotential signal provided in the data packets of the data packet sequences 141R and 142R to the display 27. The buffering utility 145 is associated with a data store / buffer 147 and configured and operable to buffer portions of the first digitized biopotential signal 151 and the second digitized biopotential signal 152 provided in the data packet sequences 141R and 142R in said buffer 147. The system 100 further includes a frame packager 160 configured and operable to successively retrieve data packets of the data packet sequences 141R and 142R from the buffer (e.g., after a wrap of a buffering period), repackage successive sets of samples of the portions of the biopotential signals 151 and 152 retrieved from the buffer 147 according to their sampling order, and utilize them to form a sequence of successive signal frames that are streamed for display by the display 27. Thus, the system 100 may include or be associated with a streamer 170 (which may be implemented, for example, by a display adapter or a network streamer) adapted to operate upon wraparound of the buffering period to stream the signal frames to the display 27 at a predetermined / set frame rate.

[0059] As mentioned above, the various implementations of the biopotential / ECG signals synchronized by the system 100 of the present embodiment may not necessarily be used for display, or may be used not only for display but also, optionally, to perform additional processing. For example, the biopotential / ECG signals synchronized by the system 100 may be stored for further analysis and / or used for calculation of an activation sequence i representing the markings in relation to an anatomical map, and / or other processing that may be required.

[0060] The operation of system 100 will now be more particularly described with reference to a flow chart of method 190 shown in FIG. 4B.

[0061] In operations 191 and 192, which may be performed in parallel by the data communications utility 130, the data communications utility 130 generally receives a first sequence and a second sequence of data packets in which a first digitized biopotential signal and a second digitized biopotential signal, or portions thereof, are received over respective data links.

[0062] Statistics of communication latency on each of the data links 145A and 145B are determined by the data link monitor 142 in operation 193. To this end, the data link monitor applies a statistical process to the timing of receipt of data packets from the respective first utility 31 and second utility 30, thereby determining a standard deviation σ A , σ B, or a latency variance in the transmission of data packets over each data link 145A and 145B, respectively. It is noted that in some embodiments, data link monitor 142 may not obtain information regarding the transmission time of each data packet, and the statistical calculation may be performed taking into account an operating scheme in which data packets transmitted over each data link 145A and 145B are transmitted at substantially regular / equal time intervals. Such an operating scheme in which data packets are actually transmitted over each data link 145A or 145B at substantially regular / equal time intervals may be implemented in some embodiments of the present invention in which the data packets carry similar sized portions (e.g., of similar duration / number of samples) of the biopotential signal communicated thereby. Alternatively or additionally (e.g., if the data packets carry biopotential signal portions of variable duration and are not transmitted at fixed intervals), data link monitor 142 may utilize information about both the transmission times of the data packets (which may be indicated in each data packet itself) and the timing of their receipt by network communications utility 130 to determine latency statistics for each data link 145A and 145B. It will be appreciated that one skilled in the art can readily understand how to determine latency statistics for a data link in any of the above techniques.

[0063] Thus, given the latency statistics, in operation 194, the buffering utility 145 determines a buffering period ΔT for delaying synchronous streaming to the display of the biopotential signal / portion thereof received through data packets. Typically, the buffering period ΔT is set to a value that is equal to or greater than a predetermined maximum buffering threshold ΔT for each data link 145A and 145B to facilitate pseudo real-time presentation of the biopotential signal on the display 27. MAX The standard deviation σ of call time statistics A , σ BFor example, the buffering period ΔT may be set as follows: ΔT=Min(n * Max(σ A ,σ B ,ΔT MAX ), where the predetermined multiple n may be set within a range of 2.5 to 4 standard deviations (e.g., 3), and the maximum buffering threshold ΔT MAX may be set to tens of milliseconds, for example up to 150 ms or 200 ms. Thus, by delaying the streaming of the biopotential signal to the display 27 in this manner, the signal may be displayed on the display in pseudo real time, while eliminating the possibility that a signal packet will not be received in time for the display.

[0064] In operation 195, upon initialization of the synchronous streaming of the biopotential signals 151 and 152 to the display, the packet synchronizer 140 delays the synchronous streaming by a buffering period ΔT, and in operation 196, the buffering utility 145 operates to buffer / store in the buffer 147 the first biopotential signal 151 and the second biopotential signal 152 received through data packets via the first data link and the second data link.

[0065] Next, in operation 197, frame packager 160 operates to generate a series of consecutive signal frames (e.g., stored in buffer 147), all of whose counterparts represent portions of biopotential signals 151 and 152 received over data communications links 145A and 145B. This may include packaging and formatting consecutive sets of signal samples of the first and second plurality of biopotential signals from the buffer according to their sampling order to form a sequence of consecutive signal frames to be displayed on display 27. In this regard, it should be appreciated that in some implementations, overlapping sets of signal samples may be packaged within consecutive signal frames such that the display displays a video presenting a continuous / smooth change in 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 an embodiment, frame packager 160 may include a resampler 165 that is configured and operable to resample a set of samples of a signal to be presented in a signal frame to reduce their resolution to facilitate their presentation in the signal frame.

[0066] Next, in operation 198, once the buffering periods have overlapped (from the time of initialization of synchronous streaming in operation 195), the series of consecutive signal frames formed in operation 197 are streamed by the streamer / display adapter 170 and displayed on the display 27.

[0067] The system 100 and method 190 of Figures 4A and 4B thereby provide packet synchronization for synchronizing between data packets carrying biphasic signals of different medical devices communicated over different data links of variable latency, enabling synchronized simultaneous presentation of the biphasic signals sensed by the different medical devices in pseudo real time.

[0068] In some embodiments, the system 100, e.g., its frame packager 160, also optionally includes the synchronizer 150 described above with reference to Figures 3A-3B. The synchronizer 150 may, for example, operate according to the method 180 described above for synchronizing between samples of sets of signal samples of a biopotential signal packaged in each signal frame. More specifically, the synchronizer processes the sets of signal samples to identify and remove redundant samples acquired in one or more of the sets as a result of differences between the sampling rates of the first utility and the second utility, thereby mitigating any asynchrony between sample sets sampled by asynchronous sampling utilities of different medical devices. In such embodiments, the system 100 applies both packet synchronization and sample synchronization to signals received from multiple medical devices.

[0069] It should be noted that the present invention has been described above with particular reference to biopotential signals, such as electrocardiograms (ECGs), electrograms (EGMs), and intracardiac electrograms (IEGNs). In this regard, it will be readily appreciated by those skilled in the art that 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. EXAMPLES

[0070] Example 1. A method for synchronous streaming to a display of electrocardiogram (ECG) signals acquired from a plurality of medical devices, the method comprising: providing a plurality of first digitized signals including a first reference digitized signal, the plurality of first digitized signals being sampled by a first sampling utility from a plurality of first analog signals sensed by a plurality of first ECG sensors of a first medical device, one of the plurality of first analog signals being selected as a reference analog signal, the first reference digitized signal corresponding to the sampling of the reference analog signal by the first sampling utility; providing a plurality of second digitized signals including a second reference digitized signal, the plurality of second digitized signals including one or more second digitized signals sampled by a second sampling utility from one or more second analog signals sensed by one or more second ECG sensors of a second medical device concurrently with the sensing of the plurality of first analog signals, the second reference digitized signal being sampled by the second sampling utility concurrently from a reference analog signal sensed by the first medical device; comparing the first digitized reference signal to a second digitized reference signal; synchronizing between the plurality of first digitized signals and the one or more second digitized signals based on the comparing; and simultaneously streaming the plurality of first digitized signals to a display in synchronization with the one or more second digitized signals.

[0071] Example 2. sensing a plurality of first analog signals by a plurality of first ECG sensors of a first medical device; simultaneously sensing one or more second analog signals by one or more second ECG sensors of a second medical device; Sampling the plurality of first analog signals with a first sampling utility to obtain a plurality of first digitized signals including a first reference digitized signal; 2. The method of claim 1, further comprising sampling the one or more second analog signals and the reference analog signal with a second sampling utility to obtain one or more second digitized signals and a second digitized reference signal.

[0072] Example 3. Synchronization identifying, based on the comparing, excess samples taken in each of the first digitized signal or the second digitized signal, respectively, taken from one of the first sampling utility or the second sampling utility, the excess samples resulting from a difference between sampling rates of the first sampling utility and the second sampling utility; 4. The method of any one of claims 2 to 3, further comprising removing redundant samples from each of the first digitized signal or the second digitized signal prior to streaming to a display.

[0073] Example 4. The method of any one of Examples 1-3, wherein the sampling clocks of the first sampling utility and the second sampling utility operate at sampling rates close to similar nominal sampling rates.

[0074] Example 5. A method according to any one of Examples 1 to 4, wherein each frame displayed by an ECG signal on the display presents a time interval of the ECG signal not exceeding a certain maximum duration, and the reference analog signal is selected as one of the first analog signals that is non-periodic and non-stationary within an interval of a certain maximum duration.

[0075] Example 6. The method of example 5, wherein the reference analog signal is a far-field ECG signal.

[0076] Example 7. The method of any one of Examples 1-6, wherein the first medical device and the second medical device comprise a plurality of ECG sensors adapted to sense ECG signals in situ during cardiac surgery.

[0077] Example 8. The following: At least one of the first and second medical devices is a catheter adapted to be inserted into the body for at least one of cardiac exploration and treatment, and at least one of the first and second sampling utilities is connected to a plurality of ECG sensors of the catheter adapted to measure cardiac activity in situ during cardiac surgery; - The method of example 7, wherein at least one of the first medical device and the second medical device is a surface ECG device comprising a plurality of ECG sensors adapted to be placed on or outside the body to probe the heart, and at least one of the first sampling utility and the second sampling utility is connected to the plurality of ECG sensors.

[0078] Example 9. The method of any one of Examples 1-8, wherein the first medical device is a catheter adapted to be placed in the heart during surgery to sense an intracardiac electrogram (IEGM) signal, and the reference analog signal is an ECG signal obtained from at least one ECG sensor in the catheter.

[0079] Example 10. The method of any one of Examples 1 to 9, wherein a catheter is adapted to be inserted into the heart, and the multiple ECG sensors of the catheter include multiple ECG sensors disposed within the catheter for contacting cardiac tissue during catheter operation, and at least one ECG sensor disposed within the catheter so as to be spaced apart from the cardiac tissue during catheter operation, thereby enabling sensing of a cardiac far-field ECG signal via the at least one ECG sensor, and utilizing the far-field ECG signal as a reference analog signal.

[0080] Example 11. The method of any one of Examples 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 characteristics associated with the electrocardiogram.

[0081] Example 12. A method for synchronous streaming to a display of electrocardiogram (ECG) signals acquired from a plurality of medical devices, the method comprising: receiving, via a first data link associated with a first utility of a first medical device, a first sequence of data packets including a plurality of first digitized ECG signals regularly packaged by the first utility and transmitted over the first data link; receiving, via a second data link associated with a second utility of a second medical device, a second sequence of data packets including one or more second digitized ECG signals regularly packaged by the second utility and transmitted over the second data link; monitoring receipt timing of data packets regularly transmitted over each of the first and second data links to determine communication latency statistics on each of the data links; determining a buffering period for delaying synchronous streaming of the ECG signal to the display based on communication latency statistics; upon initiation of synchronous streaming of the ECG signal to the display, delaying the synchronous streaming by a buffering period; buffering in a buffer the first and second digitized ECG signals of the first and second sequences of data packets received over the first and second data links; Successively packaging successive sets of signal samples of the first digitized ECG signal and the second digitized ECG signal retrieved from the buffer according to their sampling order to form a sequence of successive signal frames that are streamed for display; streaming the signal frames to the display at the frame rate when the buffering mechanism wraps; and thereby reducing communication latency and enabling pseudo real-time synchronous streaming to a display of ECG signals acquired over data links associated with multiple medical devices.

[0082] Example 13. The method of Example 12, wherein the repackaging includes performing the method of Example 1 for synchronization between signal samples of the first digitized ECG signal and the second digitized ECG signal, and for identification and removal of redundant samples acquired in each of the first digitized signal or the second digitized signal as a result of differences between the sampling rates of the first utility and the second utility.

[0083] Example 14. The method of example 12 or 13, wherein the repackaging includes downsampling signal samples of the set of the first digitized ECG signal and the second digitized ECG signal to form a signal frame having a resolution suitable for presentation on a display.

[0084] Example 15. The method of any one of Examples 12-14, wherein consecutive sets of the signal samples used to form the signal frame include overlapping signal samples.

[0085] Example 16. The method of any one of Examples 12 to 15, comprising: determining a standard deviation of a communication call time for each of the first data link and the second data link; and setting a buffering period to correspond to a predetermined multiple of a maximum standard deviation among the standard deviations of the communication call times.

[0086] Example 17. A method according to any one of Examples 12 to 16, wherein the buffering period does not exceed a predetermined maximum buffering period allowed for streaming and is set to a multiple of at least three times the maximum standard deviation of latency.

[0087] Example 18. A system for synchronous streaming to a display of electrocardiogram (ECG) signals acquired from a plurality of medical devices, the system comprising: a synchronizer adapted to receive a first plurality of digitized signals and a second plurality of digitized signals sampled by a first sampling utility and a second sampling utility, respectively, from corresponding first plurality of analog signals and second plurality of analog signals sensed by ECG sensors of at least one first medical device and at least one second medical device, a synchronizer, wherein the first plurality of digitized signals includes a first reference digitized signal sampled by a first sampling utility from an analog signal of the first plurality of analog signals selected as a reference analog signal and sensed by an ECG sensor of a first medical device selected as a reference ECG sensor, and the second plurality of digitized signals includes a second reference digitized signal sampled by a second sampling utility from the reference analog signals and sensed by a reference ECG sensor of the first medical device; The synchronizer a comparator adapted to compare the first digitized reference signal with the second digitized reference signal; a sample processor adapted to synchronize the first and second digitized signals based on a result of the comparison between the first and second reference signals performed by the comparator, thereby obtaining a synchronization signal of the first and second digitized signals; The system, wherein the synchronizer is associated with a streamer adapted to simultaneously stream a synchronized signal of the first plurality of digitized signals and the second plurality of digitized signals for display on a display.

[0088] Example 19. A sample processor comprising: - identifying excess samples acquired in each digitized signal of the first plurality of digitized signals or one of the second plurality of digitized signals acquired from one of the first sampling utility or the second sampling utility, respectively, based on a result of the comparison, the excess samples resulting from a difference between the sampling rates of the first sampling utility and the second sampling utility; - removing redundant samples from each digitized signal of the first digitized signal or the second digitized signal, the system of Example 18 being configured and operable to synchronize between a plurality of first digitized signals and a plurality of second digitized signals.

[0089] Example 20. A system as described in Example 18 or 19, wherein the first plurality of digitized signals and the second plurality of digitized signals are ECG signals, each frame displaying the ECG signal on the display presents a time interval of the ECG signal not exceeding a certain maximum duration, and the reference analog signal is selected as one of the first analog signals that is non-periodic and non-stationary within an interval of a certain maximum duration.

[0090] Example 21. The system described in Example 20, wherein at least one first medical device includes a catheter adapted to be placed within the heart during surgery to sense an intracardiac electrogram (IEGM) signal, and the reference ECG sensor is an ECG sensor positioned within the catheter during surgery so as to be spaced from cardiac tissue and adapted to obtain a reference analog signal as a far-field ECG signal.

[0091] Example 22. the system further comprising at least one of at least one first medical device, at least one second medical device, a first sampling utility, a second sampling utility, and a display; at least one first medical device and at least one second medical device comprise a plurality of ECG sensors adapted to sense ECG signals in situ during cardiac surgery; At least one of the first and second medical devices is a catheter adapted to be inserted into the body for at least one of cardiac exploration and treatment, and at least one of the first and second sampling utilities is connected to a plurality of ECG sensors of the catheter; -The system described in any one of Examples 18 to 21, wherein at least one of the first medical device and the second medical device is a surface ECG device including a plurality of ECG sensors adapted to be placed on or outside the body to explore the heart, and at least one of the first sampling utility and the second sampling utility is connected to the plurality of ECG sensors.

[0092] Example 23. A system for synchronous streaming to a display of electrocardiogram (ECG) signals acquired from a plurality of medical devices, the system comprising: a data communications utility configured and operable to receive respective first and second sequences of data packets over a first and second communications link associated with the first and second utilities, respectively, wherein the first sequence of data packets includes 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, packaged in a regular format by the first utility and transmitted over the first communications link, and a second sequence of data packets includes a plurality of second digitized ECG signals, the plurality of second digitized ECG signals being sampled from an ECG sensor of at least one second medical device, packaged in a regular format by the second utility and transmitted over the second communications link; 1. A packet synchronizer comprising: a communications link monitor connected to the data communications utility and adapted to monitor the timing of receipt of data packets transmitted over each of the first and second communications links, thereby determining communications latency statistics for each of the first and second communications links; a buffering utility including a buffer configured and operable to utilize communication latency statistics to determine a buffering period for buffering the first and second digitized ECG signals of data packets and delaying streaming of the ECG signals to the display to enable synchronous streaming of the first and second digitized ECG signals to the display, wherein upon initialization of the synchronous streaming of the ECG signals to the display, the buffering utility is adapted to delay the synchronous streaming by the buffering period and buffer the first and second digitized ECG signals of the first and second sequences of data packets received over the first and second communications links in the buffer; a frame packager configured and operable to successively retrieve and package successive sets of signal samples of the first digitized ECG signal and the second digitized ECG signal stored in the buffer according to their sampling order to form a sequence of successive signal frames that are streamed for display; and a packet synchronizer adapted to operate upon wrapping of a buffering period to stream signal frames to a display at a frame rate.

[0093] Example 24. The system described in Example 23, wherein the communication link monitor is adapted to process the timing of receipt of data packets thereby determining a standard deviation of a communication latency of each of the first and second communication links, respectively, and the buffering utility is adapted to set a buffering period to correspond to a predetermined multiple of a maximum standard deviation of the standard deviation of the communication latency.

[0094] Example 25. The system described in any one of Examples 23 to 24, wherein the frame packager includes a synchronizer described in any one of Examples 18 to 22, and is configured and operable to synchronize between signal samples of the first plurality of digitized signals and the second plurality of digitized signals, and to identify and remove redundant samples acquired within each digitized signal of the first digitized signal or the second digitized signal as a result of differences between the sampling rates of the first utility and the second utility.

[0095] Example 26. A system described in any one of Examples 23 to 25, wherein the frame packager includes a resampler adapted to downsample the first digitized ECG signal and the second digitized ECG signal to form a signal frame having a resolution suitable for presentation on a display.

[0096] It should be understood that the term electrocardiogram (ECG) is used in the above examples 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.

[0097] It should also be understood that the above-described embodiments are given by way of example, and that the present disclosure is not limited to what is particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described above, as well as variations and modifications thereof not disclosed in the prior art that would occur to one skilled in the art upon reading the foregoing description.

[0098] [Embodiment] (1) A method for synchronous streaming to a display of electrocardiogram (ECG) signals acquired from a plurality of medical devices, the method comprising: providing a plurality of first digitized signals including a first reference digitized signal, the plurality of first digitized signals being sampled by a first sampling utility from a plurality of first analog signals sensed by a plurality of first ECG sensors of a first medical device, one of the plurality of first analog signals being selected as a reference analog signal, the first reference digitized signal corresponding to the sampling of the reference analog signal by the first sampling utility; providing a plurality of second digitized signals including a second reference digitized signal, the plurality of second digitized signals including one or more second digitized signals sampled by a second sampling utility from one or more second analog signals sensed by one or more second ECG sensors of a second medical device contemporaneously with the sensing of the plurality of first analog signals, the second reference digitized signal being sampled by the second sampling utility from the reference analog signals sensed by the first medical device; comparing the first digitized reference signal to the second digitized reference signal; synchronizing between the plurality of first digitized signals and the one or more second digitized signals based on the comparing; and simultaneously streaming the plurality of first digitized signals to the display in synchronization with the one or more second digitized signals. (2) sensing the plurality of first analog signals by the plurality of first ECG sensors of the first medical device; simultaneously 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 with the first sampling utility to obtain the plurality of first digitized signals including the first reference digitized signal; 2. The method of claim 1, further comprising sampling the one or more second analog signals and the reference analog signal with the second sampling utility to obtain the one or more second digitized signals and the second digitized reference signal. (3) The synchronization is identifying excess samples taken in each of the first digitized signal or the second digitized signal, taken from one of the first sampling utility or the second sampling utility, respectively, based on the comparing, the excess samples resulting from a difference between sampling rates of the first sampling utility and the second sampling utility; 2. The method of claim 1, further comprising removing the redundant samples from each of the first digitized signal or the second digitized signal prior to the streaming to the display. (4) The method of embodiment 1, wherein the sampling clocks of the first sampling utility and the second sampling utility operate at sampling rates close to similar nominal sampling rates. (5) A method as described in embodiment 1, wherein each frame displayed by the ECG signal on the display represents a time interval of the ECG signal not exceeding a certain maximum duration, and the reference analog signal is selected as one of the first analog signals that is non-periodic and non-stationary within the interval of the certain maximum duration.

[0099] (6) The method of embodiment 5, wherein the reference analog signal is a far-field ECG signal. (7) The method of embodiment 1, wherein the first medical device and the second medical device comprise a plurality of ECG sensors adapted to sense the ECG signals in situ during the cardiac surgery. (8) The following: At least one of the first and second medical devices is a catheter adapted to be inserted into a body for at least one of cardiac exploration and treatment, and at least one of the first and second sampling utilities is connected to a plurality of ECG sensors of the catheter adapted to measure the cardiac activity in situ during the cardiac procedure. -The method of embodiment 7, wherein at least one of the first medical device and the second medical device is a surface ECG device comprising a plurality of ECG sensors adapted to be placed on or outside the body to probe the heart, and at least one of the first sampling utility and the second sampling utility is connected to the plurality of ECG sensors. (9) The method of embodiment 1, wherein the first medical device is a catheter adapted to be placed in the heart during surgery to sense an intracardiac electrogram (IEGM) signal, and the reference analog signal is an ECG signal obtained from at least one ECG sensor in the catheter. (10) The method of embodiment 9, wherein the catheter is adapted to be inserted into the heart, and the multiple ECG sensors of the catheter include multiple ECG sensors disposed within the catheter for contacting tissue of the heart during movement of the catheter, and at least one ECG sensor, the at least one ECG sensor disposed within the catheter so as to be spaced from the tissue of the heart during the movement of the catheter, thereby enabling sensing of a far-field ECG signal of the heart via the at least one ECG sensor, and utilizing the far-field ECG signal as the reference analog signal.

[0100] (11) The method of embodiment 1, comprising applying further processing to the synchronized first digitized signal and second digitized signal to analyze or calculate one or more characteristics associated with the electrocardiogram. (12) A method for synchronous streaming to a display of electrogram (ECG) signals acquired from a plurality of medical devices, the method comprising: receiving, via a first data link associated with a first utility of a first medical device, a first sequence of data packets including a plurality of first digitized ECG signals regularly packaged by the first utility and transmitted over the first data link; receiving, via a second data link associated with a second utility of a second medical device, a second sequence of data packets including one or more second digitized ECG signals regularly packaged by the second utility and transmitted over the second data link; monitoring receipt timing of data packets regularly transmitted over each of the first data link and the second data link to determine communication latency statistics over each of the data links; determining a buffering period for delaying the synchronous streaming of the ECG signal to the display based on the communication latency statistics; upon initiation of synchronous streaming of ECG signals to said display, delaying said synchronous streaming by said buffering period; buffering the first and second digitized ECG signals of the first and second sequences of data packets received over the first and second data links in a buffer; sequentially packaging successive sets of signal samples of the first digitized ECG signal and the second digitized ECG signal retrieved from the buffer according to their sampling order to form a sequence of consecutive signal frames that are streamed for display; streaming the signal frames to the display at a frame rate when the buffering period wraps; and thereby reducing the communication latency and enabling pseudo real-time synchronous streaming of ECG signals acquired via data links associated with multiple medical devices to the display. (13) The method of embodiment 12, wherein the repackaging includes performing the method of embodiment 1 for synchronization between the signal samples of the first digitized ECG signal and the second digitized ECG signal, and for identification and removal of redundant samples acquired in each of the first digitized signal or the second digitized signal as a result of differences between sampling rates of the first utility and the second utility. (14) The method of embodiment 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 having a resolution suitable for presentation on the display. (15) The method of embodiment 12, wherein the contiguous sets of signal samples used to form the signal frame include overlapping signal samples.

[0101] (16) The method of embodiment 12, further comprising: determining a standard deviation of the communication latency for each of the first data link and the second data link, respectively; and setting the buffering period to correspond to a predetermined multiple of a maximum standard deviation of the standard deviations of the communication latency. (17) The method of embodiment 12, wherein the buffering period does not exceed a predetermined maximum buffering period allowed for the streaming and is set to a multiple of at least three times the maximum standard deviation of the latency. (18) A system for synchronous streaming to a display of electrocardiogram (ECG) signals acquired from a plurality of medical devices, the system comprising: a synchronizer adapted to receive a first plurality of digitized signals and a second plurality of digitized signals sampled by a first sampling utility and a second sampling utility, respectively, from corresponding first plurality of analog signals and second plurality of analog signals sensed by ECG sensors of at least one first medical device and at least one second medical device, a synchronizer, wherein the first plurality of digitized signals includes a first reference digitized signal sampled by the first sampling utility from an analog signal of the first plurality of analog signals selected as a reference analog signal and sensed by an ECG sensor of the first medical device selected as a reference ECG sensor, and the second plurality of digitized signals includes a second reference digitized signal sampled by the second sampling utility from the reference analog signal and sensed by the reference ECG sensor of the first medical device; The synchronizer is a comparator adapted to compare the first digitized reference signal with the second digitized reference signal; a sample processor adapted to synchronize the plurality of first digitized signals and the plurality of second digitized signals based on a 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; the synchronizer is associated with a streamer adapted to simultaneously stream the synchronized signal of the first plurality of digitized signals and the second plurality of digitized signals for display on the display. (19) The sample processor, - identifying excess samples acquired in each digitized signal of the first plurality of digitized signals or one of the second plurality of digitized signals acquired from one of the first sampling utility or the second sampling utility, respectively, based on the result of the comparison, the excess samples resulting from a difference between sampling rates of the first sampling utility and the second sampling utility; - removing the redundant samples from each of the first digitized signals or the second digitized signals. (20) The system of embodiment 18, wherein the first plurality of digitized signals and the second plurality of digitized signals are ECG signals, each frame displaying the ECG signal on the display presents a time interval of the ECG signal not exceeding a maximum duration, and the reference analog signal is selected as one of the first analog signals that is non-periodic and non-stationary within the interval of the maximum duration.

[0102] (21) The system of embodiment 20, wherein the at least one first medical device includes a catheter adapted to be placed within the heart during the procedure to sense an intracardiac electrogram (IEGM) signal, and the reference ECG sensor is an ECG sensor positioned within the catheter during the procedure so as to be spaced from tissue of the heart and adapted to obtain the reference analog signal as a far-field ECG signal. (22) The following: the system further comprising at least one of the at least one first medical device, the at least one second medical device, the first sampling utility, the second sampling utility, 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 to sense ECG signals in situ during cardiac surgery; At least one of the first and second medical devices is a catheter adapted to be inserted into a body for at least one of cardiac exploration and treatment, and at least one of the first and second sampling utilities is connected to a plurality of ECG sensors of the catheter; -The system of embodiment 18, wherein at least one of the first medical device and the second medical device is a surface ECG device comprising a plurality of ECG sensors adapted to be placed on or outside the body to probe the heart, and at least one of the first sampling utility and the second sampling utility is connected to the plurality of ECG sensors. (23) A system for synchronous streaming to a display of electrocardiogram (ECG) signals acquired from a plurality of medical devices, the system comprising: a data communications utility configured and operable to receive respective first and second sequences of data packets over a first and second communications link associated with a first and second utility, respectively, wherein the first sequence of data packets includes 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, packaged in an orderly manner by the first utility and transmitted over the first communications link, and the second sequence of data packets includes a plurality of second digitized ECG signals, the plurality of second digitized ECG signals being sampled from an ECG sensor of at least one second medical device, packaged in an orderly manner by the second utility and transmitted over the second communications link; 1. A packet synchronizer comprising: a communications link monitor connected to said data communications utility and adapted to monitor the timing of receipt of data packets transmitted over each of said first communications link and said second communications link, thereby determining communications latency statistics for each of said first communications link and said second communications link; a buffering utility including a buffer configured and operable to utilize the statistics of communication latency to determine a buffering period for buffering the first and second digitized ECG signals of the data packets and delaying streaming of the ECG signals to the display to enable synchronous streaming of the first and second digitized ECG signals to the display, wherein upon initialization of synchronous streaming of ECG signals to the display, the buffering utility is adapted to delay the synchronous streaming by the buffering period and buffer the first and second digitized ECG signals of the first and second sequences of data packets received over the first and second communications links in the buffer; a frame packager configured and operable to successively retrieve and package successive sets of signal samples of the first digitized ECG signal and the second digitized ECG signal stored in the buffer according to their sampling order to form a sequence of consecutive signal frames that are streamed for display; a streamer adapted to operate upon a wrap of the buffering period to stream the signal frames to the display at a frame rate. (24) The system of embodiment 23, wherein the communication link monitor is adapted to process the timing of receipt of the data packets thereby determining a standard deviation of the communication latency of each of the first communication link and the second communication link, respectively, and the buffering utility is adapted to set the buffering period to correspond to a predetermined multiple of a maximum standard deviation of the standard deviation of the communication latency. (25) The system of embodiment 23, wherein the frame packager comprises a synchronizer as described in embodiment 18 and is configured and operable to synchronize between the signal samples of the first plurality of digitized signals and the second plurality of digitized signals and to identify and remove excess samples acquired within each digitized signal of the first digitized signal or the second digitized signal as a result of differences between the sampling rates of the first utility and the second utility.

[0103] (26) The system of embodiment 23, wherein the frame packager comprises a resampler adapted to downsample the first digitized ECG signal and the second digitized ECG signal to form the signal frame having a resolution suitable for presentation on the display.

Claims

1. 1. A system for synchronous streaming to a display of electrocardiogram (ECG) signals acquired from a plurality of medical devices, the system comprising: a synchronizer adapted to receive a first plurality of digitized signals and a second plurality of digitized signals sampled by a first sampling utility and a second sampling utility, respectively, from corresponding first plurality of analog signals and second plurality of analog signals sensed by ECG sensors of at least one first medical device and at least one second medical device, a synchronizer, wherein the first plurality of digitized signals includes a first reference digitized signal sampled by the first sampling utility from an analog signal of the first plurality of analog signals selected as a reference analog signal and sensed by an ECG sensor of the first medical device selected as a reference ECG sensor, and the second plurality of digitized signals includes a second reference digitized signal sampled by the second sampling utility from the reference analog signal and sensed by the reference ECG sensor of the first medical device; The synchronizer is a comparator adapted to compare the first digitized reference signal with the second digitized reference signal; a sample processor adapted to synchronize the first and second digitized signals based on a result of the comparison between the first and second reference signals performed by the comparator, thereby obtaining a synchronization signal of the first and second digitized signals; the synchronizer is associated with a streamer adapted to simultaneously stream the synchronized signal of the first plurality of digitized signals and the second plurality of digitized signals for display on the display.

2. The sample processor, - identifying, based on the result of the comparison, extra samples acquired in each digitized signal of the first plurality of digitized signals or one of the second plurality of digitized signals acquired from one of the first sampling utility or the second sampling utility, respectively, where the extra samples result from a difference between the sampling rates of the first sampling utility and the second sampling utility; - removing the redundant samples from each of the first digitized signal or the second digitized signal.

3. 2. The system of claim 1, wherein the first plurality of digitized signals and the second plurality of digitized signals are ECG signals, each frame displaying the ECG signal on the display presents a time interval of the ECG signal not exceeding a maximum duration, and the reference analog signal is selected as one of the first analog signals that is non-periodic and non-stationary within the interval of the maximum duration.

4. 4. The system of claim 3, wherein the at least one first medical device includes a catheter adapted to be placed within a heart during a procedure to sense an intracardiac electrogram (IEGM) signal, and the reference ECG sensor is an ECG sensor positioned within the catheter during the procedure to be spaced from tissue of the heart and adapted to obtain the reference analog signal as a far-field ECG signal.

5. below: 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 utility, the second sampling utility, and the display; said at least one first medical device and said at least one second medical device comprise a plurality of ECG sensors adapted to sense ECG signals in situ during cardiac surgery; at least one of the first and second medical devices is a catheter adapted to be inserted into a body for at least one of cardiac exploration and treatment, and at least one of the first and second sampling utilities is connected to a plurality of ECG sensors of the catheter; The system of claim 1, wherein at least one of the first medical device and the second medical device is a surface ECG device comprising a plurality of ECG sensors adapted to be placed on and external to the body to probe the heart, and at least one of the first sampling utility and the second sampling utility is connected to the plurality of ECG sensors.

6. 1. A system for synchronous streaming to a display of electrocardiogram (ECG) signals acquired from a plurality of medical devices, the system comprising: a data communications utility configured and operable to receive respective first and second sequences of data packets over a first and second communications link associated with a first and second utility, respectively, wherein the first sequence of data packets includes 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, packaged in a regular order by the first utility and transmitted over the first communications link, and the second sequence of data packets includes a plurality of second digitized ECG signals, the plurality of second digitized ECG signals being sampled from an ECG sensor of at least one second medical device, packaged in a regular order by the second utility and transmitted over the second communications link; 1. A packet synchronizer comprising: a communications link monitor connected to said data communications utility and adapted to monitor the timing of receipt of data packets transmitted over each of said first communications link and said second communications link, thereby determining communications latency statistics for each of said first communications link and said second communications link; a buffering utility including a buffer, the buffering utility being configured and operable to utilize the statistics of the communication latency to determine a buffering period for buffering the first and second digitized ECG signals of the data packets and delaying the streaming of the ECG signals to the display to enable synchronous streaming of the first and second digitized ECG signals to the display, wherein upon initialization of synchronous streaming of ECG signals to the display, the buffering utility is adapted to delay the synchronous streaming by the buffering period and buffer the first and second digitized ECG signals of the first and second sequences of data packets received over the first and second communications links in the buffer; a frame packager configured and operable to successively retrieve and package successive sets of signal samples of the first digitized ECG signal and the second digitized ECG signal stored in the buffer according to their sampling order to form a sequence of consecutive signal frames that are streamed for display; a streamer adapted to operate upon a wrap of the buffering period to stream the signal frames to the display at a frame rate.

7. 7. The system of claim 6, wherein the communication link monitor is adapted to process the timing of receipt of the data packets to thereby determine a standard deviation of the communication latency of each of the first and second communication links, respectively, and the buffering utility is adapted to set the buffering period to correspond to a predetermined multiple of a maximum standard deviation of the standard deviation of the communication latency.

8. 7. The system of claim 6, wherein the frame packager comprises the synchronizer of claim 1 and is configured and operable to synchronize between the signal samples of the first plurality of digitized signals and the second plurality of digitized signals and to identify and remove redundant samples acquired within each digitized signal of the first digitized signal or the second digitized signal as a result of differences between the sampling rates of the first utility and the second utility.

9. 7. The system of claim 6, wherein the frame packager comprises a resampler adapted to downsample the first digitized ECG signal and the second digitized ECG signal to form the signal frames having a resolution suitable for presentation on the display.

10. 1. A method for synchronous streaming to a display of electrocardiogram (ECG) signals acquired from a plurality of medical devices, the method comprising: providing a plurality of first digitized signals including a first reference digitized signal, the plurality of first digitized signals being sampled by a first sampling utility from a plurality of first analog signals sensed by a plurality of first ECG sensors of a first medical device, one of the plurality of first analog signals being selected as a reference analog signal, the first reference digitized signal corresponding to the sampling of the reference analog signal by the first sampling utility; providing a plurality of second digitized signals including a second reference digitized signal, the plurality of second digitized signals including one or more second digitized signals sampled by a second sampling utility from one or more second analog signals sensed by one or more second ECG sensors of a second medical device contemporaneously with the sensing of the plurality of first analog signals, the second reference digitized signal being sampled by the second sampling utility from the reference analog signals sensed by the first medical device; comparing the first digitized reference signal to the second digitized reference signal; synchronizing between the plurality of first digitized signals and the one or more second digitized signals based on the comparing; and simultaneously streaming the plurality of first digitized signals to the display in synchronization with the one or more second digitized signals.

11. sensing the plurality of first analog signals by the plurality of first ECG sensors of the first medical device; simultaneously 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 with the first sampling utility to obtain the plurality of first digitized signals including the first reference digitized signal; and sampling the one or more second analog signals and the reference analog signal with the second sampling utility to obtain the one or more second digitized signals and the second digitized reference signal.

12. The synchronizing step comprises: identifying excess samples acquired in each of the first digitized signal or the second digitized signal acquired from one of the first sampling utility or the second sampling utility, respectively, based on the comparing, the excess samples resulting from a difference between sampling rates of the first sampling utility and the second sampling utility; and removing the redundant samples from each of the first digitized signal or the second digitized signal prior to the streaming to the display.

13. The method of claim 10 , wherein the sampling clocks of the first sampling utility and the second sampling utility operate at sampling rates close to a similar nominal sampling rate.

14. 11. The method of claim 10, wherein each frame displayed by the ECG signal on the display represents a time interval of the ECG signal not exceeding a certain maximum duration, and the reference analog signal is selected as one of the first analog signals that is non-periodic and non-stationary within the certain maximum duration interval.

15. The method of claim 14 , wherein the reference analog signal is a far-field ECG signal.

16. The method of claim 10 , wherein the first medical device and the second medical device comprise a plurality of ECG sensors adapted to sense the ECG signals in situ during the cardiac procedure.

17. below: at least one of the first and second medical devices is a catheter adapted to be inserted into a body for at least one of cardiac exploration and treatment, and at least one of the first and second sampling utilities is connected to a plurality of ECG sensors of the catheter adapted to measure the cardiac activity in situ during the cardiac procedure; The method of claim 16, wherein at least one of the first and second medical devices is a surface ECG device comprising a plurality of ECG sensors adapted to be placed on and external to the body to probe the heart, and at least one of the first and second sampling utilities is connected to the plurality of ECG sensors.

18. 11. The method of claim 10, wherein the first medical device is a catheter adapted to be placed in the heart during surgery to sense an intracardiac electrogram (IEGM) signal, and the reference analog signal is an ECG signal obtained from at least one ECG sensor in the catheter.

19. 20. The method of claim 18, wherein the catheter is adapted to be inserted into the heart, and the multiple ECG sensors of the catheter include multiple ECG sensors disposed within the catheter for contacting tissue of the heart during movement of the catheter, and at least one ECG sensor disposed within the catheter to be spaced from the tissue of the heart during the movement of the catheter, thereby enabling sensing of a far-field ECG signal of the heart via the at least one ECG sensor, and utilizing the far-field ECG signal as the reference analog signal.

20. 11. The method of claim 10, comprising applying further processing to the synchronized first and second digitized signals to analyze or calculate one or more characteristics associated with the electrocardiogram.

21. 1. A method for synchronous streaming to a display of electrogram (ECG) signals acquired from a plurality of medical devices, the method comprising: receiving, via a first data link associated with a first utility of a first medical device, a first sequence of data packets including a plurality of first digitized ECG signals regularly packaged by the first utility and transmitted over the first data link; receiving, via a second data link associated with a second utility of a second medical device, a second sequence of data packets including one or more second digitized ECG signals regularly packaged by the second utility and transmitted over the second data link; monitoring receipt timing of data packets regularly transmitted over each of said first data link and said second data link to determine communication latency statistics over each of said data links; determining a buffering period for delaying the synchronous streaming of the ECG signal to the display based on the communication latency statistics; upon initiation of synchronous streaming of ECG signals to said display, delaying said synchronous streaming by said buffering period; buffering the first and second digitized ECG signals of the first and second sequences of data packets received over the first and second data links in a buffer; sequentially packaging successive sets of signal samples of the first digitized ECG signal and the second digitized ECG signal retrieved from the buffer according to their sampling order to form a sequence of consecutive signal frames that are streamed for display; streaming the signal frames to the display at a frame rate when the buffering period wraps; and thereby reducing the communication latency and enabling pseudo real-time synchronous streaming of ECG signals acquired over data links associated with multiple medical devices to the display.

22. 22. The method of claim 21, wherein the repackaging includes performing the method of claim 10 for synchronization between the signal samples of the first digitized ECG signal and the second digitized ECG signal and for identification and removal of redundant samples acquired in each of the first digitized signal or the second digitized signal as a result of differences between sampling rates of the first utility and the second utility.

23. 22. The method of claim 21 , 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 frames having a resolution suitable for presentation on the display.

24. 22. The method of claim 21, wherein the consecutive sets of the consecutive sets of signal samples used to form the signal frame include overlapping signal samples.

25. 22. The method of claim 21, comprising: determining a standard deviation of the communication latency for each of the first data link and the second data link, respectively; and setting the buffering period to correspond to a predetermined multiple of a maximum standard deviation of the standard deviations of the communication latency.

26. 22. The method of claim 21, wherein the buffering period does not exceed a predetermined maximum buffering period allowed for the streaming and is set to a multiple of at least three times the maximum standard deviation of the latency.

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