Analysis of ectopic electrophysiological signals

Abstract

In a described example, a method includes selecting a first time interval that includes first electrophysiological signals with ectopic activity, in which the electrophysiological signals represent electrophysiological signals measured at respective measurement locations distributed across a patient's body. The method also includes aligning the first electrophysiological signals with respective template signals to provide aligned pairs of signals for at least some measurement locations, in which the template signals electrophysiological signals without the ectopic activity for at least some of the respective measurement locations. The method also includes subtracting the template signal from the first electrophysiological signal in each aligned pair of signals to provide ectopic data representative of the ectopic activity in the first time interval for the respective locations. The method also includes reconstructing the electrogram on the cardiac surface and generating an output to identify a location for the ectopic activity based on the ectopic data.

Description

ANALYSIS OF ECTOPIC ELECTROPHYSIOLOGICAL SIGNALSFIELD

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 558,398, filed February 27, 2024, the entire content of which is incorporated herein by reference.FIELD

[0002] The present technology is generally related to analysis of ectopic physiological signals.BACKGROUND

[0003] Atrial ectopic beat is a central mechanism in initiating atrial fibrillation (AF). Therefore, research has focused on ways to identify and localize atrial ectopics. While a traditional electrocardiogram (ECG) system can monitor electrical activity of a heart of a patient, identification and localization of ectopic beats tends to be difficult for several reasons. For example, atrial ectopic signals can be obfuscated by other signal components (e.g., T wave). The interpretation of such signals also remains challenging. Additionally, the atrial ectopic beat can be infrequent and thus localization should be done using a single beat.SUMMARY

[0004] The techniques of this disclosure generally relate to analysis of ectopic physiological signals.

[0005] In an aspect, the disclosure provides a system that includes non-transitory memory to store data and machine-readable instructions, and a processor to access the non- transitory memory and execute the machine-readable instructions. The data can include electrophysiological data representing electrophysiological signals at respective measurement locations distributed across an outer surface of a patient’s body over at least one measurement time interval. The instructions executable by the processor can include interval selection code, alignment code, subtraction code, and mapping code, wherein the machine-readable instructions, when executed by the processor, cause the processor to execute various actions. For example, these actions include selecting a first time interval including electrophysiological signals with ectopic activity and a second time intervalincluding electrophysiological signals without the ectopic activity. These actions also include aligning the electrophysiological signals in the first time interval with respective electrophysiological signals in the second time interval and provide aligned pairs of signal intervals for at least some of the respective measurement locations. These actions also include subtracting the electrophysiological signals in each aligned pair of signal intervals and provide ectopic data representative of the ectopic activity in the first time interval for at least some of the respective measurement locations. These actions also include generating an output identifying an anatomical location for the ectopic activity based on the ectopic data.

[0006] In another aspect, the present disclosure provides a method that includes selecting a first time interval that includes first electrophysiological signals with ectopic activity, in which the electrophysiological signals represent electrophysiological signals measured at respective measurement locations distributed across an outer surface of a patient’ s body. The method also includes aligning the first electrophysiological signals with respective template signals to provide aligned pairs of signals for at least some of the respective measurement locations, in which the template signals electrophysiological signals without the ectopic activity for at least some of the respective measurement locations. The method also includes subtracting the template signal from the first electrophysiological signal in each aligned pair of signals to provide ectopic data representative of the ectopic activity in the first time interval for the respective locations. The method also includes reconstructing electrophysiological signals on a surface of interest based on the ectopic data and geometry data, in which the geometry data describes a spatial relationship between the measurement locations and the surface of interest. The method can also include generating a graphical output to identify a location for the ectopic activity based on these constructed electrophysiological signals. In yet another aspect, one or more non- transitory machine-readable media can include instructions, which when executed by one or more processors, perform the method.

[0007] In another aspect, a system includes one or more non-transitory machine readable media having instructions, which when executed by one or more processors are programmed to reconstruct electrophysiological signals on a surface of interest to localize ectopic activity based on geometry data and ectopic data. The geometry data describes a spatial relationship between a plurality of measurement locations on an outer surface of apatient’s body surface and the surface of interest. The ectopic data represents the ectopic activity identified in a respective time interval of respective electrophysiological signals for at least some of the measurement locations.

[0008] In another aspect, a method includes storing, in non-transitory machine readable media, geometry data describing a spatial relationship between a plurality of measurement locations on an outer surface of a patient’s body surface and the surface of interest. The method also includes identifying, by a processor, ectopic activity in a respective time interval of electrophysiological signals for at least some of the respective measurement locations and providing ectopic data that represents the identified ectopic activity. The method also includes reconstructing, by the processor, electrophysiological signals on a surface of interest to localize the identified ectopic activity based on the geometry data and the ectopic data.

[0009] The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF DRAWINGS

[0010] FIG. 1 is a block diagram of an example system to analyze ectopic signals.

[0011] FIG. 2 is an example GUI representing a set of body surface electrodes.

[0012] FIG. 3 is a signal diagram illustrating example signal intervals that have been selected.

[0013] FIG. 4 is a signal diagram illustrating examples of signal alignment and subtraction.

[0014] FIG. 5 illustrates example activation maps across a surface of interest based on ectopic data.

[0015] FIG. 6 is a signal diagram illustrating an example signal interval with ectopic activity that has been selected.

[0016] FIG. 7 is a signal diagram illustrating examples of signal alignment and subtraction.

[0017] FIG. 8 illustrates an example activation map across a surface of interest based on ectopic data.

[0018] FIG. 9 is a flow diagram illustrating an example method for analyzing and mapping ectopic signals.

[0019] FIG. 10 is a block diagram of a system illustrating an example operating environment.DETAILED DESCRIPTION

[0020] This disclosure relates to analysis and / or localization of ectopic physiological activity, such as to identify and localize atrial ectopic signals.

[0021] The systems and methods herein can uncover one or more ectopic atrial signals and use noninvasive electrocardiographic imaging (ECGI) to localize the anatomical origin of such uncovered ectopic atrial signals. As an example, the systems and methods analyze electrophysiological (EP) data representing EP signals measured at respective electrode locations distributed across an outer surface of a patient’s body. For example, there can be twelve or more electrodes (e.g., ranging from 12 to 300 electrodes), such as described herein. The systems and methods can determine whether atrial ectopic activity in a given beat is obscured by (e.g., overlaps with or is fused with) another signal component (e.g., T wave) in the given beat. If the atrial ectopic activity is not obscured, which may occur in a small percentage of cases, the systems and methods can directly proceed to perform ECGI and related analysis based on the EP data representing the beat containing atrial ectopic activity. If the atrial ectopic activity is obscured, the system and methods are configured to extract the ectopic activity, as described herein.

[0022] In cases where the ectopic activity is obscured, the systems and methods perform QRST subtraction to remove the signal contamination and provide unobscured (e.g., clean) ectopic signals. For example, one or more intervals of EP signals containing the determined ectopic activity can be selected for respective electrode locations distributed across the patient’s body. Each of the selected EP signals are aligned with respective templates to provide aligned pairs of signals for the respective electrode locations. The templates can include QRST template signals that do not contain the ectopic activity. For instance, the QRST template contains only ventricular signals for a given beat. The template signal is subtracted from the ectopic EP signal for each aligned pair of signals to reveal and provide ectopic signals (e.g., clean P waves) for the respective electrode locations. Ectopicdata can be provided representing the unobscured ectopic activity in the given beat (or beats).

[0023] The systems and methods can generate an output to identify an anatomical location (e.g., origin location) for the ectopic activity based on the ectopic data. The output can be in the form of a graphical electroanatomic map, spatial coordinates, spatial distance relative to one or more anatomical landmarks, or other helpful information to guide a user to the anatomical location for the ectopic activity. As described herein, ECGI mapping can be used to facilitate the interpretation of the electrophysiological signals of the ectopic activity. For example, the systems and methods herein can use ECGI mapping to reconstruct a visual representation of the ectopic activity on a surface of interest (e.g., a cardiac surface) based on the ectopic data (representing unobscured ectopic signals) and geometry data representing cardiac and torso geometries from the same patient from which the EP signals are measured.

[0024] The systems and methods described herein thus enable ectopic activity, which can be hidden or obscured in measured signals, to be identified clearly and efficiently. The systems and methods can also be used to accurately localize ectopic activity and its origin in real time (or near real time), such as by generating electroanatomic maps of the ectopic activity (e.g., P waves). For example, the systems and methods provide practical and effective solutions to localize arrhythmia sources or premature atrial contractions (PACs) inside or outside pulmonary veins.

[0025] In many of the following examples, the ectopic activity is described as atrial ectopic activity. However, the systems and methods described herein are not limited to identifying atrial ectopics, as other ectopic (e.g., obscured) electrophysiological activity can also be identified in a human or other animal.

[0026] FIG. 1 is a block diagram of an example system 100 to analyze and / or identify ectopic activity. The system 100 includes memory 102, which can include one or more non-transitory machine-readable media. The system 100 also includes a processor 104, which can include one or more processing cores, to access the memory and execute corresponding instructions demonstrated within the processor block 104.

[0027] In the example of FIG. 1, the memory 102 stores electrophysiological (EP) data 106 and geometry data 108. In some examples, the electrophysiological data 106 corresponds to raw (e.g., unfiltered and pre-processed) ECG signals that are measurednoninvasively from a patient’s body over one or more time intervals. In other examples, the EP data 106 can include measured ECG signals that are filtered (e.g., to remove noise). As an example, an arrangement of sensor electrodes (e.g., about two hundred fifty sensors) are placed at respective measurement locations on an outer surface of the patient’s body, such as distributed approximately evenly across the patient’s thorax or a portion thereof. Various EP measurement systems (not shown in FIG. 1, but see, e.g., measurement system 566 in FIG. 13) can be used to acquire the body surface electrical measurements that can be utilized to provide the electrophysiological data 106. The electrode at each measurement location can thus define a respective input channel of the EP measurement system. The EP data 106 can either correspond to live data that is acquired at the time of implementing this method, or the electrophysiological data 106 can correspond to data that has been acquired a priori, such as part of a previous EP procedure or acquired during another intervention. The EP signals thus can be measured and recorded from all respective electrode locations simultaneously.

[0028] The geometry data 108 can describe a spatial relationship between the measurement locations (e.g., electrode locations where respective signals are measured) and patient anatomical geometry (e.g., the heart or other surface of interest within the body) in a three-dimensional spatial coordinate system. For example, the geometry data 108 represents spatial locations in three-dimensional space for each location where the electrophysiological signals, which are represented in the EP data 106, are measured or derived. As described herein, the geometry data 108 thus can represent spatial locations (e.g., locations of noninvasive electrodes) distributed across the outer surface of a patient’s body and / or anatomical locations within the patient’s body. The geometry data 108 can include electrode location data and anatomical geometry data. While the EP data 106 and geometry data 108 are shown as separate blocks, such data can be stored in memory in a common data structure integrating spatial information and electrical signals across one or more surfaces of interest.

[0029] As an example, the geometry data 108 can be derived from imaging data acquired by a three-dimensional medical imaging modality, such as multi-plane x-ray, computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, positron emission tomography (PET), single-photon emission computed tomography (SPECT) and the like. In one example, an anatomical model can be constructed based on imaging dataobtained (e.g., by a medical imaging modality) for the patient to provide spatial coordinates for points across the patient’s heart and, in examples when the electrodes are positioned on the patient’s body when the medical image is acquired, for the locations of the body surface electrodes positioned on the outer surface of the patient’s body. The electrode locations and locations of the surface (or surfaces) of interest within a patient’s body can be identified in a respective coordinate system of the acquired images through appropriate image processing, including extraction and segmentation. For instance, segmented image data can be converted into a two-dimensional or three-dimensional graphical representation that includes the volume of interest for the patient. Appropriate anatomical or other landmarks can be identified in the geometry data 108 to facilitate spatial registration of the EP data 106. The identification of such landmarks can be done manually (e.g., by a person via image editing software) and / or automatically (e.g., via image processing techniques). In another example, the location of the body surface electrodes can be acquired by a digitizer, manual measurements or another non-imaging based technique (e.g., a navigation system, range camera, etc.). The anatomical geometry may be implemented as a mathematical model (e.g., a spline or mesh or point cloud) that defines locations of anatomy and / or anatomical features in a spatial coordinate system. The electrode geometry can also be implemented as a model that defines spatial coordinates of the electrodes in the same common coordinate system with the anatomical geometry such that geometry data 108 can describe the spatial relationship between the measurement locations and patient anatomical geometry.

[0030] The processor 104 executes machine readable instructions that include ectopic identification code 110 and mapping code 112. While FIG. 1 is depicted and discussed with the ectopic identification code 110 as a discrete section of code in relation to the mapping code 112 to facilitate discussion of aspects of this disclosure, it is to be understood that in other examples the ectopic identification code 110 and the mapping code 112 may have overlapping code / logic (e.g., where the ectopic identification code 110 is a module of the mapping code 112). Similarly, unless specifically discussed otherwise herein, it is to be understood that one of ordinary skill in the art would understand that some or all of each individual portion of code as discussed herein (e.g., ectopic signal identification code 110, interval selection code 114, upsampling code 116, template generator code 118, signal alignment code 120, signal subtraction code 122, channel integrity code 124, mapping code 112, reconstruction code 126, output generator code 128) may be integrated into and / oroverlap with any other individual portion of code as aspects of this disclosure are reduced to practice.

[0031] As described herein, when executing the ectopic identification code 110, the processor 104 will identify (e.g., isolate or extract) ectopic activity in EP signals of the EP data 106. The ectopic activity might not be obscured by other signal components in a given beat interval, in which case the EP data for the given beat interval can be stored as ectopic data. Typically, however, the ectopic activity is concealed or obscured by other signal content (e.g., EP signal components, such as a T wave, and / or noise). Executing the ectopic identification code 110 thus can provide ectopic data representative of the identified ectopic activity in the EP signals. When executing the mapping code 112, the processor 104 will provide an output based on the ectopic data. As described herein, the output can include a graphical map and / or other data (e.g., spatial coordinates, anatomical landmarks or the like) describing a location of the identified ectopic activity on a surface of interest. For example, executing the mapping code 112 can cause the processor 104 to generate a graphical map that specifies a site of origin of an atrial ectopic (e.g., PAC) on a graphical map of a heart.

[0032] In the example of FIG. 1, the ectopic identification code 110 includes interval selection code 114, upsampling code 116, template generator code 118, signal alignment code 120, signal subtraction code 122, and signal integrity code 124. The mapping code 112 includes reconstruction code 126 and output generator code 128. It is to be understood that the systems and methods described herein can be implemented without a particular arrangement of code blocks, and that the functions of some code blocks can be omitted altogether, or be combined with or implemented by other code blocks without departing from the approach described herein.

[0033] Executing the interval selection code 114 causes the processor 104 to select one or more time intervals for the EP signals in the EP data 106. For example, executing the interval selection code 114 can cause the processor 104 to select the interval (e.g., a given single beat) in response to a user input instruction provided by a user input device 130 (e.g., mouse, keyboard, touchscreen interface, gesture interface, or the like), which can specify start and stop times for the interval. Also, or as an alternative, executing the interval selection code 114 can cause the processor 104 to select the one or more intervals automatically, such as based on signal morphology. As an example, the interval selection code 114, when executed, causes the processor 104 to select a time interval (also referred toas an ectopic interval) for EP signals that include ectopic activity. In some examples, executing the interval selection code 114 causes the processor 104 to select the ectopic interval as a given beat containing a P wave concealed within a T wave of a QRST waveform, in which the P wave exhibits abnormal timing and / or morphology. The selected ectopic interval can be stored in the memory 102 for each respective measurement location, such as time values specifying the start and stop times for the interval.

[0034] The template generator code 118 is programmed to generate one or more template signals representative of an interval of an EP signal that does not contain the ectopic activity but have the same or substantially the same non-ectopic (e.g., ventricular) activity as in the ectopic interval. The template generator code 118 can provide a respective template signal for each of the respective input channels (e.g., measurement locations where the EP signals are acquired).

[0035] As an example, the template generator 118 uses the interval selection code 114 to select one or more template intervals of the EP signal without the ectopic activity for each of the measurement locations. The template generator code 118 can be programmed to derive the template signal for each input channel from a single beat or by combining (e.g., averaging) multiple beats for each respective input channel into a single beat. For example, each template signal can be a QRST waveform without the ectopic activity for each of the respective measurement locations (or input channels). In one example, the interval selection code 114 is programmed to select the template interval for the EP signals to include a QRST waveform for a given cardiac cycle that occurs immediately before or immediately after the ectopic interval that has been selected. In another example, the interval selection code 114 is programmed to calculate an averaged QRST template based on an average of QRST waveforms in multiple template intervals that have been selected. The multiple intervals can include one or more cardiac cycles before and / or after the selected ectopic interval. The multiple template intervals used to calculate the averaged QRST template can include QRST waveforms before and / or after the selected ectopic interval for each of the respective input channels. The cycles can be selected manually (e.g., in response to a user input selecting the cycles) and / or automatically. The template generator code 118 can thus generate a template signal for each respective measurement location based on the template interval that is selected (e.g., by the interval selection code 114). The resulting template signal (e.g., a QRST waveform) for each channel thus can be a single beat extracted from an actual EPsignal or be derived from one or more intervals of the EP signal for each respective channel, as described herein.

[0036] In some examples, the ectopic signal identification code 110 includes upsampling code 116 programmed to upsample the EP signals to a higher resolution, which can facilitate a better alignment in the subsequent processing steps. For example, the upsampling code can be applied to the EP signals in each of the selected intervals and to the template signal after the interval has been selected and the template has been generated. Alternatively, the upsampling can be applied to the EP signal prior to interval selection. For example, the upsampling code can be programmed to compute an approximation of the sequence that would have been obtained by sampling the signal at a higher rate. The upsampling of the EP signals can be by an integer factor (e.g., 5x, lOx or higher upsampling) through a digital interpolation filter (e.g., a finite impulse response filter).

[0037] Each of the alignment code 120 and the subtraction code 122 further can process signals based on the upsampled versions of the EP signals in each of the respective ectopic signal intervals and corresponding template signals. It is expected that such upsampling of the EP signals in this way can achieve an improvement in the quality of the ectopic signals that are identified, which can result in further improved accuracy locating the anatomical origin of the ectopic activity.

[0038] Also, or as an alternative, in some examples, the ectopic signal identification code 110 includes channel integrity code 124 programmed to exclude the EP signals for one or more input channels based on channel integrity. That is, the identification of ectopic activity can be implemented for only a set of input channels determined by the channel integrity code 124 to be good channels. In an example, the channel integrity code 124 is programmed to analyze the EP signal in the ectopic interval and the template signal provided for each input channel and compute an integrity score. The channel integrity code 124 can also identify channels as bad channels for known disconnected channels, or channels exhibiting impedance too high to deliver useful data. In response to the channel integrity code 124 determining that either of the EP signal in the ectopic interval for a given channel or the template signal for the given channel has an integrity score below a threshold value, the given channel can be excluded as a bad channel. By way of example, the channel integrity code 124 can be programmed to determine channel integrity for respective inputchannels for electrodes at the respective locations according to any of the approaches described in U.S. Patent No. 9,977,060 and / or U.S. Patent No. 10,874,318.

[0039] The signal alignment code 120 is programmed to align the EP signals in the ectopic interval temporally with respective template signals and provide aligned signal pairs for some or all of the respective input channels. Each aligned signal pair includes a template signal and an associated EP signal in an ectopic interval for a respective input channel. In an example, the alignment code 120 is programmed to temporally align the respective signals based on a cross correlation of the QRS complexes in the respective signals being aligned for each channel. The cross correlation can compute a measure of similarity between one signal (e.g., the template signal) and shifted copies of the other signal (e.g., the ectopic containing signal), which can be used to determine a corresponding shift (e.g., a time shift) between the template and ectopic intervals. The signal alignment code 120 can compute the shift based on analysis of signals for a plurality of the input channels (e.g., all the input channels). In an example, signal alignment code 120 can compute the shift as an average shift derived from signals from a plurality of channels (e.g., up to and including all channels) that results in a best alignment for the channels. The signal alignment code 120 can be programmed to apply the computed shift to align the respective QRS signals in the ectopic interval and template for each respective channel.

[0040] In some examples, the alignment code 120 (or another function of the identification code 110) further can be programmed to crop the signals in each of the aligned pairs of signal intervals to the same length to facilitate subsequent processing. Also, if any channels have been identified as bad (e.g., by the channel integrity function), such bad channels can be excluded from the alignment process.

[0041] The signal subtraction code 122 is programmed to subtract the electrophysiological signals in each aligned pair of signals and provide ectopic data representative of the ectopic activity in the ectopic time interval (e.g., a given beat) for signals measured at respective measurement locations. The signal subtraction code can subtract the template signal from the EP signal of the selected ectopic interval for each aligned pair of signals to provide respective signals that reveal the ectopic activity. For example, the ectopic activity includes an identified P wave without being obscured by the QRST waveform components that have been removed based on the subtraction. As described, the ectopic data can be stored in the memory 102 to represent the ectopicactivity at respective measurement locations on the body surface, excluding any locations removed by the channel integrity code 124.

[0042] The mapping code 112 includes output generator code 128 programmed to generate one or more outputs to identify an anatomical location for the ectopic activity based on the ectopic data. For example, the output generator code 128 provides output data to an output interface to visualize a corresponding output 132 on a display 134. The graphical output 132 can include a graphical map that represents or is derived from the ectopic data to visualize the ectopic activity on a surface of interest. The surface of interest can be a three-dimensional surface within the patient’s body, such as a cardiac surface or envelope (e.g., epicardial or endocardial surface) that is described by the geometry data 108. The mapping code 112 includes reconstruction code 126 programmed to reconstruct the electrophysiological signals onto points (e.g., nodes) across a surface of interest based on the geometry data 108 and the ectopic data provided by the identification code 110. For example, reconstruction code 126 performs ECGI mapping using the ectopic data as a boundary condition to inverse calculate the potentials (e.g., unipolar potentials) reconstructed on the surface of interest (e.g., atrial surface geometry). The reconstruction code 126 can also reconstruct EP signals on a surface of interest based on the geometry data 108 and other EP data 106. Examples of inverse algorithms that can be implemented by the reconstruction code 126 include those disclosed in U.S. patent Nos. 7,983,743 and 6,772,004. The reconstruction code 126 thus can reconstruct the ectopic signals onto a multitude of points on the surface of interest (e.g., greater than 1,000 locations).

[0043] The mapping code can further process the resultant reconstructed signals to generate a visual representation to identify an anatomical location for the ectopic activity (e.g., the anatomical origin of the ectopic activity). For example, the mapping code 112 can also compute activation time for respective points (e.g., nodes) on the surface of interest and provide an activation map based on analyzing the ectopic data that has been reconstructed onto such surface. A point or region having the earliest activation time in the activation map thus identifies a location of origin of the ectopic activity (e.g., atrial ectopic activity). The output data representing the activation map for the ectopic activity can be stored as ectopic activation map data in the memory 102. Similar activation maps can be computed for a number of ectopic intervals, which can be viewed separately (e.g.,in respective windows of a display) and / or combined into a composite average activation map.

[0044] In some examples, the origin of ectopic activity (e.g., a PAC) can be determined or validated based on comparing the ectopic activation map with one or more other activation maps where the earliest activation time is at a known location (e.g., the pacing location from a navigation system). This can be particularly useful when the earliest activation may occur in space (such as septum) that may not be visualized by the mapping code. The instructions executable by the processor can include code programmed to localize the origin of the ectopic activity (e.g., PAC) based on a comparison of the ectopic activation map and the one or more pacing activation maps. For example, the location of the pacing catheter when pacing generated a same or similar activation map ectopic activation map can provide an accurate localization (e.g., 3D coordinates) of where the PAC originates, including along the inner septum, which might not be directly visualized on the map.

[0045] FIGS. 2 through 8 provides examples of various GUIs and diagrams that can be implemented by the system 100 of FIG. 1, such as part of an EP workflow. Accordingly, the description of FIGS. 2 through 8 also refer to the FIG. 1.

[0046] FIG. 2 is an example of a GUI 200 showing a graphical representation for an arrangement of body surface electrodes. GUI can be implemented as part of the program instructions executed by the processor 104 in FIG. 1. In the example of FIG. 2, the GUI represents two panels 202 and 204, such as for the right front panel of electrodes and the left front panel of electrodes. Panel 202 includes electrode GUI elements numbered 1 to 63 and panel 204 includes GUI elements numbered 64-125. Other configurations of panels and number of electrodes can be used. A similar type of GUI can be provided for electrodes positioned on other body parts. In FIG. 2, electrode GUI elements 21, 34, 50, 52, 68, 71, and 78 have been selected in response to a user input (e.g., using user input device 130).

[0047] FIG. 3 is a signal diagram 250 illustrating example signal intervals for a set of electrodes, such as electrodes that have been selected through electrode GUI elements 21, 34, 50, 52, 68, 71 in the GUI of FIG. 2. FIG. 3 shows a first interval 252 that includes ectopic activity indicative of a PAC, shown at 254. Another interval 256 represents a template signal that immediately precedes the interval 252. As described herein the intervals252 and 256 can be selected by interval selection code 114, automatically, or in response to a user input (e.g., selected using user input device 130).

[0048] FIG. 4 is a signal diagram 280 illustrating examples of signal alignment and subtraction. As shown in FIG. 4, signal 282 represents a portion of a signal waveform with ectopic activity (e.g., PAC) for an ectopic interval and the signal 284 represents a template waveform for a respective input channel (e.g., for a respective measurement location on the body surface). For example, a portion of the interval exhibiting ectopic activity (e.g., PAC) is shown at 286. The signals 282 and 284 are shown for respective beats that have been temporally aligned for a single channel (e.g., by the signal alignment code 120). Similar alignments can be implemented by the signal alignment code 120 for template signals and ectopic signal intervals provided (e.g., by interval selection code 114 and template generator code 118) for each respective input channel, as described herein.

[0049] The signal 290 shows an example signal waveform based on subtraction of the signals 282 and 284 (e.g., by signal subtraction code). The signal subtraction code can subtract respective templates from the EP signals for each ectopic interval for each respective input channel, as described herein, to produce respective recovered ectopic signals (e.g., P waves) for each input channel, such as the compilation of signals shown at 292. The resulting signals 292 can omit channels that have been removed (e.g., by channel integrity code 124) after removing bad channels, and be stored as ectopic data for a given cardiac cycle.

[0050] FIG. 5 illustrates example activation maps 300, 302, and 304 across a cardiac surface (e.g., an epicardial surface) for an ectopic time interval. Each of the maps 300, 302, and 304 in FIG. 5 correspond to different viewing angles of the heart representing ectopic activity based on the same activation data. For example, the reconstruction code 126 can generate each of the maps 300, 302, and 304 based on the ectopic data (representing recovered P wave signals 292) and geometry data 108, as described herein. An earliest activation time that identifies a location of ectopic origin on the heart is shown at 306 in the different views shown by maps 300, 302, and 304.

[0051] FIGS. 6 through 8 demonstrate another example that can be used to identify and localize a PAC. FIG. 6 is a signal diagram 350 illustrating EP signals for a multi -cycle time interval for a set of electrodes, which have been selected (e.g., in response to user inputs selecting electrode GUI elements in the GUI of FIG. 2). An ectopic first interval 352includes ectopic activity indicative of a PAC, shown at 354. The interval 352 can be selected by interval selection code 114, automatically, or in response to a user input (e.g., selected using user input device 130). The template signal can be selected or derived from the EP signals, such as according to any of the approaches described herein.

[0052] FIG. 7 is a signal diagram 400 illustrating examples of signal alignment and subtraction used to produce ectopic data. As shown in FIG. 7, a signal 404 represents a portion of a signal with ectopic activity (e.g., PAC) for an ectopic interval and the signal 402 represents a template signal for a given input channel (e.g., for a corresponding measurement location on the body surface). The ectopic activity in the interval is shown at 406. The signals 402 and 404 are shown for respective beats that have been temporally aligned (e.g., by the signal alignment code 120) for the given input channel. Similar alignments can be implemented by the signal alignment code 120 for respective template signals and EP signals in ectopic intervals (e.g., by interval selection code 114 and template generator code 118) for each respective input channel, as described herein.

[0053] The signal 410 shows an example signal waveform based on subtraction of the signals 402 and 404 (e.g., by signal subtraction code 122). The signal subtraction code 122 can subtract respective templates from the EP signals for each other ectopic interval, as described herein, to produce respective recovered ectopic signals (e.g., P waves) for each input channel, exclusive of omitted channels, such as shown at 412.

[0054] FIG. 8 illustrates an example graphical output 450 that includes an activation map 452 superimposed on a cardiac surface (e.g., an epicardial surface) for an ectopic time interval. For example, the reconstruction code 126 can generate the map 452 based on the ectopic data (representing recovered P wave signals 292) and geometry data 108, as described herein. The output 450 includes scale 454 (e.g., a color scale) describing the range of activation times shown in the map 452. An earliest activation time that identifies a location of ectopic origin on the heart is shown at 460 in the map, which is readily visible with reference to the scale 454. Also, or as an alternative, the earliest activation time can be identified in the output 450 using other indicators, such as by 3D spatial coordinates or text describing the location.

[0055] FIG. 9 is a flow diagram illustrating an example method 500 for analyzing and mapping ectopic signals, such as to identify ectopic activity. For example, the method 500 can be implemented by the processor 104 executing the ectopic signal identificationcode 110 and mapping code 112. Accordingly, the description of the method of FIG. 9 also refers to FIG. 1.

[0056] At 502, the method includes selecting (e.g., by interval selection code 114) one or more signal intervals with ectopic activity. For example, the selected signal interval includes a P wave that is obscured in the T-wave of a QRST waveform, such as corresponding to a PAC. At 504, a QRST template signal is generated. For example, the QRST template can be provided by the template generator code 118 and / or interval selection code 114, which can be automatically provided or provided in response to a user input.

[0057] At 506, the method includes aligning the EP signals selected at 502 with respective template signals provided at 504. For example, signal alignment code 120 provides aligned pairs of EP signals for at least some of the respective measurement locations. Each aligned pair of signals includes a template signal and an EP signal for an ectopic interval. As described herein, the template signals include respective electrophysiological signals without the ectopic activity for respective measurement locations. In some examples, channels with unacceptable channel integrity for either the ectopic interval or the interval (s) of EP signals used to provide the template signals can be excluded by channel integrity code 124. Upsampling can also be performed (e.g., by upsampling code 116) to increase the resolution of the signals being subtracted.

[0058] At 508, the method includes subtracting the template signal from the EP signal in each aligned pair of signals to provide ectopic signals representative of the ectopic activity in the first time interval for the respective locations. At 510, the ectopic signals can be identified to provide ectopic data. As described herein, in cases where the ectopic activity is not obscured, the method 500 can identify the ectopic beat at 510 based on the selected interval at 502 and provide corresponding ectopic data without the need for performing alignment and QRST subtraction at 506 and 508.

[0059] At 512, the method includes generating an output based on the ectopic data. In an example, the output can include a graphical representation of the identified ectopic signals (e.g., for a single beat) can be rendered on a display (e.g., display 134 - see signals 292 and 412 in FIGS. 4 and 7, respectively). Also or as an alternative, mapping code can generate the output to include reconstructed ectopic signals that are reconstructed (e.g., by reconstruction code 126) on a surface of interest based on geometry data and the ectopic data provided at 510. For example, an activation map is computed (e.g., by mapping code112) based on the reconstructed ectopic signals, which can be used to localize the site of origin for the ectopic activity (e.g., PAC or other activity). As described herein, the method 500 can be repeated to localize ectopic signals for additional ectopic beats.

[0060] FIG. 10 depicts an example of a system 550 that can be utilized for generating an output to process body surface signals to characterize ectopic activity of a patient, such as to localize its origin. The system 550 can also be used to provide a therapy (e.g., pacing and / or ablation) based on the identified ectopic activity. The system can also provide information in other formats to provide guidance to the user based on the ectopic activity as well as information derived therefrom.

[0061] By way of example, the system 550 has applications throughout various phases of patient care. As an example, the system 550 can be used as part of a patient screening process (e.g., as part of a diagnostic and / or treatment planning procedure) or to perform post-treatment evaluation. Additionally, the system 550 can be utilized as part of a treatment procedure, such as to determine parameters for delivering a therapy to the patient (e.g., delivery location, amount and type of therapy). For example, a catheter, having one or more therapy delivery devices 556 affixed thereto can be inserted into the body 554 as to contact the patient’s heart 552, endocardially or epicardially. Those skilled in the art will understand and appreciate various types and configurations of therapy delivery devices 556 that can be utilized, which can vary depending on the type of treatment and the procedure. For instance, the therapy device 556 can be configured to deliver pulsed field ablation, radio frequency ablation, pacing, chemical therapy, sound wave therapy, thermal therapy or any combination thereof.

[0062] By way of further example, the therapy delivery device 556 can include one or more electrodes located at a tip of an ablation catheter configured to perform a pulsed field ablation intervention. For the example of a pulsed field ablation (PF A) intervention, a therapy system 558 includes control circuitry configured to control parameters, which can specify a number of electrodes, energy level (e.g., current and voltage), waveform composition, pulse as well as pulse train number and duration. The parameters can control whether the PFA intervention is permanent or reversible.

[0063] In another example, the therapy delivery device 556 includes one or more electrodes located at a tip of an ablation catheter configured to generate heat for ablating tissue in response to electrical signals (e.g., radiofrequency energy) supplied by a therapysystem 558. In other examples, the therapy delivery device 556 can be configured to deliver cooling to perform ablation (e.g., cryogenic ablation), to deliver chemicals (e.g., drugs), to deliver ultrasound ablation, to deliver high-frequency radio frequency ablation, or a combination thereof. In still other examples, the therapy delivery device 556 can include one or more electrodes located at a tip of a pacing catheter to deliver electrical stimulation, such as for pacing the heart, in response to electrical signals (e.g., pacing current pulses) supplied by a therapy system 558. In other examples, the therapy system 558 can be configured to deliver noninvasive treatment, such as noninvasive cardiac ablation via radiation (e.g., stereotactic ablative radiotherapy (SBRT)). The therapy system 558 can deliver other types of therapy invasively or noninvasively to the patient’s body.

[0064] As a further example, the therapy system 558 can be located external to the patient’s body 554 and be configured to control the therapy or treatment that is being delivered by the device 556. For instance, the therapy system 558 includes a control system (e.g., hardware and / or software) 560 that can communicate (e.g., supply) electrical signals via a conductive link electrically connected between the delivery device (e.g., one or more electrodes) 556 and the therapy system 558. The control system 560 can control parameters of the signals supplied to the device 556 (e.g., current, voltage, repetition rate, trigger delay, sensing trigger amplitude) for delivering therapy (e.g., ablation or stimulation) via the electrode(s) 554 to one or more location of the heart 552. The control system 560 can set the therapy parameters and apply stimulation based on automatic, manual (e.g., user input) or a combination of automatic and manual (e.g., semi-automatic controls). One or more sensors (not shown) can also communicate sensor information back to the therapy system 558. The position of the device 556 relative to the heart 552 can be determined and tracked intraoperatively via an imaging modality (e.g., fluoroscopy, X ray), a mapping system 562, direct vision or the like. The location of the device 556 and the therapy parameters thus can be combined to determine one or more corresponding therapy delivery parameters.

[0065] Before, during and / or after providing a therapy via the therapy system 558, another system or subsystem can be utilized to acquire electrophysiology information for the patient. In the example of FIG. 10, a sensor array 564 includes one or more body surface electrodes that can be utilized for measuring patient electrical activity. As oneexample, the sensor array 564 can correspond to a high-density arrangement of body surface sensors (e.g., greater than approximately one hundred electrodes, greater than approximately two hundred electrodes, two hundred fifty -two electrodes) that are distributed over a portion of the patient’s torso (e.g., thorax) for measuring electrical activity associated with the patient’s heart (e.g., as part of an electrocardiographic mapping procedure). Examples of a high-density body surface noninvasive apparatus that can be used as the sensor array 564 are shown and described in U.S. Patent No. 9,655,561 and International publication No. WO 2010 / 054352. Other arrangements and numbers of sensing electrodes can be used as the sensor array 564. For example, the array can be a reduced set of electrodes, which does not cover the patient’s entire torso and is designed for measuring electrical activity for a particular purpose (e.g., an array of electrodes specially designed for analyzing atrial fibrillation and / or ventricular fibrillation) and / or for monitoring a predetermined spatial region of the heart. In other examples, an array having a traditional or modified 12-lead ECG or a single electrode can be implemented as the sensor array 564 to provide body surface electrical signals.

[0066] In some examples, one or more sensors may also be located on the device 556 that is inserted into the patient’s body. Such sensors can be utilized separately or in conjunction with the noninvasive sensor array 564 for mapping electrical activity for an endocardial surface, such as the wall of a heart chamber, as well as for an epicardial surface. Additionally, such sensors can also be utilized to help localize the device 556 within the heart 552, which can be registered into an image or map that is generated by the system 550. Alternatively, localization can be implemented in the absence of emitting a signal - either from an electrode within or on the heart 552 or from outside the patient’s body 554.

[0067] In each of such example approaches for acquiring patient electrical information, including invasively, noninvasively, or a combination of invasive and noninvasive sensing, the sensor array(s) 564 provides the sensed electrical information to a corresponding measurement system 566. The measurement system 566 can include corresponding controls 568 configured to provide EP measurement data 570 that describes electrical activity (e.g., ECG signals) detected by the sensors in the sensor array 564. For example, signal processing circuitry of the measurement system 566 can convert the measured analog signal(s) to corresponding digital information. The measurement system566 can further process the digital information corresponding to one or more electrophysiological signals from sensor array 564 and remove non-arrhythmogenic characteristics from each such signal channel and to provide preprocessed data that is stored in memory as the EP measurement data 570 (e.g., corresponding to the EP data 106).

[0068] The control 568 can also be configured to control the data acquisition process for measuring electrical activity and providing the measurement data 570 (e.g., at a predefined sample rate). In some examples, the control 568 can control acquisition of measurement data 570 separately from operation of the therapy system 558 (if implemented), such as in response to a user input. In other examples, the measurement data 570 can be acquired concurrently with and in synchronization with delivering therapy (e.g., pacing, ablation, or another therapy) by the therapy system 558, such as to detect electrical activity of the heart 552 that occurs in response to applying a given therapy (e.g., according to therapy parameters). For instance, appropriate time stamps can be utilized for indexing the temporal relationship between the respective measurement data 570 and therapy parameters used to deliver therapy as to facilitate the evaluation and analysis thereof.

[0069] The mapping system 562 can include code that is executed by a processor to combine the measurement data 570, corresponding to sensed body surface electrical activity of the heart 552, and provide output data 574. The output data 574 can represent or characterize detected ECG signals on the body surface and / or within the heart. The output data can also represent information derived from the measured signals, such as disclosed herein.

[0070] As one example, the mapping system 562 includes an ectopic identification function 578, such as corresponding to ectopic signal identification code 110 or related parts of the method 500, as disclosed herein (see, e.g., FIGS 1-9). The ectopic identification function 578 thus can be executed by the processor to provide ectopic data, such as described herein. The mapping system 562 can also include an activation time calculator 582, which can be executed by the processor to compute activation times across a surface of interest based on the ectopic data provided by the ectopic identification function 578. The activation time and / or other ectopic data can be used to determine a site of origin (e.g., a point or region) of the ectopic activity. The processor thus can apply eachof the functions 578 and 582 to EP data, demonstrated as electrical measurement data 570, to provide ectopic data, such as described herein.

[0071] The mapping system 562 includes an output generator 586, which can be executed by the processor to provide the output data 574 to visualize on a display 592 an output based on the ectopic data. In an example where the sensor array 564 includes a plurality of electrodes, the output data 574 can include a selected set of channels for ECG signals measured via sensors 564 on a surface of patient’s body 554. Executing the output generator 586 thus causes the processor to generate the output data to display a graphical representation of time-domain signal waveforms for one or more input channels.

[0072] In some examples, ectopic data can be mapped to a geometric surface of a heart model or other surface of interest. As disclosed herein, the maps can be computed based on EP data that is acquired noninvasively via one or more electrodes in the sensor array 564 distributed on the surface of the patient’s body 554. The system 550 also includes an electrogram reconstruction function 580 (e.g., corresponding to reconstruction code 126), which causes the processor to compute an inverse solution and provide corresponding reconstructed electrograms based on the process signals and the geometry data 572. For example, the geometry data 572 can correspond to a mathematical model, such as a generic model or a model that has been constructed based on image data obtained for the patient (e.g., via an imaging modality, such as CT, MRI, bi-plane X ray or the like) that provides spatial coordinates for the patient’s heart 552 and electrodes on the sensor array. The reconstructed electrograms thus can correspond to electrocardiographic activity across a cardiac envelope, and can include static (three-dimensional at a given instant in time) and / or dynamic (e.g., four-dimensional map that varies over time) information. For example, the EGM reconstruction function 580 can compute reconstructed electrograms to provide panoramic view across the entire heart (or other surface of interest) for a single beat based on the ectopic and geometry data. In other examples, the mapping system 562 can compute electrical activity over a sub-region of the heart (or other surface of interest) based on electrical activity measured invasively, such as via a basket catheter or other form of measurement probe (e.g., on or attached to device 556).

[0073] Parameters associated with the graphical representation, corresponding to an output visualization of the computed map, such as including selecting a time interval, atype of information that is to be presented in the visualization and the like can be selected in response to a user input via a corresponding visualization GUI 590.

[0074] Additionally, the output data 574 can be utilized by the therapy system 558, if included in the system 550. The control that is implemented can be fully automated control, semi-automated control (partially automated and responsive to a user input) or manual control based on the output data 574. In some examples, the control system 560 for the therapy system 558 can utilize the output data to control one or more therapy parameters. As an example, the control 560 can control delivery of ablation or other therapy to a site of the heart (e.g., epicardial or endocardial wall) based on the ectopic data that has been determined by the function 578. In other examples, an individual user can view the map generated in the display 592 to manually control the therapy system 558 based on information that is visualized. Other types of therapy and devices can also be controlled based on the output data.EXAMPLE EMBODIMENTS:

[0075] Several aspects of the present technology are set forth in the following numbered examples.1. A system comprising: a processor; and non-transitory memory coupled to the processor and storing data and machine-readable instructions, the data including electrophysiological data representing electrophysiological signals at respective measurement locations distributed across an outer surface of a patient’s body over at least one measurement time interval, wherein the machine-readable instructions, when executed by the processor, cause the processor to: select a first time interval including electrophysiological signals with ectopic activity and a second time interval including electrophysiological signals without the ectopic activity; align the electrophysiological signals in the first time interval with respective electrophysiological signals in the second time interval and provide aligned pairs of signal intervals for at least some of the respective measurement locations;subtract the electrophysiological signals in each aligned pair of signal intervals and provide ectopic data representative of the ectopic activity in the first time interval for the at least some of the respective measurement locations; and generate a graphical output to identify a location for the ectopic activity based on the ectopic data.2. The system of example 1, wherein the graphical output includes a graphical map on a surface of interest.3. The system of example 2, wherein the graphical map includes an activation map representing activation times across the surface of interest based on the ectopic data, in which the activation map identifies an origin of the ectopic activity.4. The system according to example 2 or 3, wherein the surface of interest is within the body, the data further includes geometry data describing a spatial relationship between the measurement locations and the surface of interest, and wherein the machine-readable instructions include mapping code that, when executed by the processor, cause the processor to reconstruct electrophysiological signals as unipolar electrograms on the surface of interest based on the geometry data and the ectopic data.5. The system according to any preceding example, wherein the ectopic activity includes a P wave that is identified based on the subtraction.6. The system according to any preceding example, wherein instructions further comprise code that, when executed by the processor, cause the processor to upsample the electrophysiological signals in each of the first and second intervals, and each of the aligning the electrophysiological signals in the first time interval and the subtracting the electrophysiological signals is based on the upsampled electrophysiological signals in each of the first and second intervals.7. The system according to any preceding example, wherein instructions further comprise channel integrity code that, when executed by the processor, cause the processor to exclude the electrophysiological signals for a given measurement location in response to determining that the electrophysiological signals in either of the first or second interval has an integrity below a threshold value for the given measurement location.8. The system according to any preceding example, wherein the electrophysiological signals in the second time interval define respective QRST templates for each of the respective measurement locations, and the instructions further comprise template generator code that, when executed by the processor, cause the processor to generate each of the respective QRST templates.9. The system of example 8, wherein the instructions further comprise interval selection code that, when executed by the processor, cause the processor to select the electrophysiological signals in the second interval to include QRS-T waveforms for a given cardiac cycle immediately after the first interval.10. The system of example 8, wherein the electrophysiological signals in the second intervals include QRS-T waveforms for a given cardiac cycle immediately preceding the first interval.11. The system of example 1, wherein the graphical output is an activation map representative of activation times across a cardiac surface, and the ectopic activity is a premature atrial contraction.12. A method, comprising: including electrophysiological data representing electrophysiological signals at respective measurement locations distributed across an outer surface of a patient’s body over at least one time interval; and selecting a first time interval that includes first electrophysiological signals with ectopic activity, in which the electrophysiological signals represent electrophysiological signals measured at respective measurement locations distributed across an outer surface of a patient’s body; aligning the first electrophysiological signals with respective template signals to provide aligned pairs of signals for at least some of the respective measurement locations, in which the template signals electrophysiological signals without the ectopic activity for at least some of the respective measurement locations; subtracting the template signal from the first electrophysiological signal in each aligned pair of signals to provide ectopic data representative ofthe ectopic activity in the first time interval for the respective locations; reconstructing electrophysiological signals on a surface of interest based on the ectopic data and geometry data, in which the geometry data describes a spatial relationship between the measurement locations and the surface of interest; and generating a graphical output to identify a location for the ectopic activity based on the reconstructed electrophysiological signals.13. The method of example 12, further comprising selecting a second time interval that includes electrophysiological signals for each of the measurement locations without the ectopic activity, wherein the template signals are provided based on the electrophysiological signals in the second time interval.14. The method according to example 12 or 13, wherein the graphical output includes a graphical map on the surface of interest.15. The method of example 14, wherein the graphical map includes an activation map representing activation times across the surface of interest based on the ectopic data, in which the activation map identifies an origin of the ectopic activity.16. The method according to any of examples 14 or 15, wherein the surface of interest is within the patient’s body, and the reconstructed electrophysiological signals are unipolar electrograms on the surface of interest.17. The method according to any of examples 12 through 16, wherein the ectopic activity includes a P wave.18. The method according to any of examples 12 through 17, further comprising upsampling the electrophysiological signals to provide the first electrophysiological signals and the template signals, and each of the aligning and the subtracting is performed using the upsampled electrophysiological signals.19. The method according to any of examples 12 through 18, further comprising excluding the electrophysiological signals for a given measurement location in response to determining that the electrophysiological signals in the first time interval or the template signals has an integrity below a threshold value for the given measurement location.20. The method according to example 13, wherein the template signals define respective QRS-T template waveforms for each of the respective measurement locations, and each of the respective QRS-T template waveforms is generated based on the electrophysiological signals in the second time interval.21. The method according to example 13 or 20, further comprising selecting the electrophysiological signals in the second interval to include QRS-T waveforms for a given cardiac cycle immediately after the first interval.22. The method according to example 13 or 20, further comprising selecting the electrophysiological signals in the second interval to include QRS-T waveforms for a given cardiac cycle immediately preceding the first interval.23. The method of example 12, wherein the graphical output is a first activation map representative of activation times across a cardiac surface, the ectopic activity is a premature atrial contraction, and the method further comprises: analyzing the first graphical map to determine a relative breakout timing at cardiac locations adjacent to or on the septum; generating a second activation map across at least a portion of the cardiac surface that includes the cardiac locations based on pacing electrophysiological signals measured at the respective measurement locations over another time interval during which pacing is performed at or adjacent to the cardiac locations; and localizing the premature atrial contraction based on the first and second activation maps.24. One or more non-transitory machine readable media having instructions, which when executed by one or more processors perform a method according to any of examples 12 through 23.25. A system comprising one or more non-transitory machine readable media having instructions, which when executed by a processor cause the processor to reconstruct electrophysiological signals on a surface of interest to localize ectopic activity based on geometry data and ectopic data, in which the geometry data describes a spatial relationship between a plurality of measurement locations on an outer surface of a patient’s body surface and the surface of interest, and the ectopic data represents the ectopic activity identified in a respective time interval ofrespective electrophysiological signals for at least some of the measurement locations.26. A method comprising: storing, in one or more non-transitory machine readable media, geometry data describing a spatial relationship between a plurality of measurement locations on an outer surface of a patient’s body surface and the surface of interest; identifying, by a processor, ectopic activity in a respective time interval of electrophysiological signals for the at least some of the respective measurement locations and providing ectopic data that represents the identified ectopic activity; and reconstructing, by the processor, electrophysiological signals on a surface of interest to localize the identified ectopic activity based on the geometry data and the ectopic data.

[0076] It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). In addition, while certain aspects of this disclosure are described as being performed by a single module or unit for purposes of clarity, it should be understood that the techniques of this disclosure may be performed by a combination of units or modules associated with, for example, a medical device.

[0077] In one or more examples, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include non-transitory computer-readable media, which corresponds to a tangible medium such as data storage media (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer).

[0078] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term “processor” as used herein may refer to any of the foregoing structure or any other physical structure suitable for implementation of the described techniques. Also, the techniques could be fully implemented in one or more circuits or logic elements.

[0079] It will be understood that, although the terms “first,” “second,” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Thus, a “first” element discussed below could also be termed a “second” element without departing from the teachings of the present disclosure. The sequence of operations (or steps) is not limited to the order presented in the claims or figures unless specifically indicated otherwise.

[0080] Unless otherwise stated, “about,” “approximately,” or “substantially” preceding a value means + / - 10 percent of the stated value, or, if the value is zero, a reasonable range of values around zero.

[0081] In this description, the term “couple” may cover connections, communications, or signal paths that enable a functional relationship consistent with this description. For example, if device A generates a signal to control device B to perform an action: (a) in a first example, device A is coupled to device B by direct connection; or (b) in a second example, device A is coupled to device B through intervening component C if intervening component C does not alter the functional relationship between device A and device B, such that device B is controlled by device A via the control signal generated by device A.

[0082] Additionally, in an effort to maintain clarity in the Figures, certain ones of duplicative components shown have not been specifically numbered, but one of ordinary skill in the art will realize, based upon the components that were numbered, the element numbers which should be associated with the unnumbered components; no differentiation between similar components is intended or implied solely by the presence or absence of an element number in the Figures. Any of the described structures and components could be integrally formed as a single unitary or monolithic piece or made up of separate subcomponents, with either of these formations involving any suitable stock or bespokecomponents and / or any suitable material or combinations of materials; however, the chosen material(s) should be biocompatible for many applications. Any of the described structures and components could be disposable or reusable as desired for a particular use environment.

[0083] Modifications are possible in the described embodiments, and other embodiments are possible, within the scope of the claims.

Claims

WHAT IS CLAIMED IS:

1. A system comprising: a processor; and non-transitory memory coupled to the processor and storing data and machine- readable instructions, the data including electrophysiological data representing electrophysiological signals at respective measurement locations distributed across an outer surface of a patient’s body over at least one measurement time interval, wherein the machine-readable instructions, when executed by the processor, cause the processor to: select a first time interval including electrophysiological signals with ectopic activity and a second time interval including electrophysiological signals without the ectopic activity; align the electrophysiological signals in the first time interval with respective electrophysiological signals in the second time interval and provide aligned pairs of signal intervals for at least some of the respective measurement locations; subtract the electrophysiological signals in each aligned pair of signal intervals and provide ectopic data representative of the ectopic activity in the first time interval for the at least some of the respective measurement locations; and generate a graphical output to identify a location for the ectopic activity based on the ectopic data.

2. The system of claim 1, wherein the graphical output includes a graphical map on a surface of interest.

3. The system of claim 2, wherein the graphical map includes an activation map representing activation times across the surface of interest based on the ectopic data, in which the activation map identifies an origin of the ectopic activity.

4. The system of claim 1, wherein the surface of interest is within the body, the data further includes geometry data describing a spatial relationship between the measurement locations and the surface of interest, and wherein the machine-readable instructionsinclude mapping code that, when executed by the processor, cause the processor to reconstruct electrophysiological signals as unipolar electrograms on the surface of interest based on the geometry data and the ectopic data.

5. The system of claim 1, wherein the ectopic activity includes a P wave that is identified based on the subtraction.

6. The system of claim 1, wherein instructions further comprise code that, when executed by the processor, cause the processor to upsample the electrophysiological signals in each of the first and second intervals, and each of the aligning the electrophysiological signals in the first time interval and the subtracting the electrophysiological signals is based on the upsampled electrophysiological signals in each of the first and second intervals.

7. The system of claim 1, wherein instructions further comprise channel integrity code that, when executed by the processor, cause the processor to exclude the electrophysiological signals for a given measurement location in response to determining that the electrophysiological signals in either of the first or second interval has an integrity below a threshold value for the given measurement location.

8. The system of claim 1, wherein the electrophysiological signals in the second time interval define respective QRST templates for each of the respective measurement locations, and the instructions further comprise template generator code that, when executed by the processor, cause the processor to generate each of the respective QRST templates.

9. The system of claim 8, wherein the instructions further comprise interval selection code that, when executed by the processor, cause the processor to select the electrophysiological signals in the second interval to include QRS-T waveforms for a given cardiac cycle immediately after the first interval.

10. The system of claim 8, wherein the electrophysiological signals in the second intervals include QRS-T waveforms for a given cardiac cycle immediately preceding the first interval.

11. The system of claim 1, wherein the graphical output is an activation map representative of activation times across a cardiac surface, and the ectopic activity is a premature atrial contraction.

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