Patent Description:
Cardiac arrhythmia, such as atrial fibrillation, is a heart rhythm that produces irregular heartbeats. Arrhythmias typically occur when regions of cardiac tissue abnormally conduct electric signals to adjacent tissue, thereby disrupting the normal cardiac cycle and causing asynchronous rhythm.

Mapping of electrical potentials in the heart is a commonly used tool for diagnosing and treating cardiac arrhythmias. Typically, time-varying electrical potentials in the endocardium are sensed and recorded as a function of position inside the heart, and then used to map a local electrogram or local activation time. Activation time differs from point to point in the endocardium due to the time required for conduction of electrical impulses through the heart muscle. The direction of this electrical conduction at any point in the heart is conventionally represented by an activation vector, which is normal to an isoelectric activation front, both of which may be derived from a map of activation time. The rate of propagation of the activation front through any point in the endocardium may be represented as a velocity vector.

Mapping the activation front and conduction fields aids the physician in identifying and diagnosing abnormalities, such as ventricular and atrial tachycardia and ventricular and atrial fibrillation, which result from areas of impaired electrical propagation in the heart tissue.

<CIT>, describes a method for manually mapping premature ventricular contractions (PVCs). The method includes recording a series of electrocardiogram (ECG) signals from a patient suffering from PVCs, and then selecting, by a physician, beats which show a sinus rhythm, and beats which show a PVC. The sinus beats are used for producing a physical map of the heart. Electrophysiological readings of local activation times (LATs), acquired during the PVC beats, are then overlaid on the sinus map, producing a so-called LAT hybrid map.

<CIT>, describes a method for ECG signal analysis and cardiac arrhythmia detection. The method includes identifying a normal QRS complex and labeling QRS complexes acquired after identification the normal QRS complex based on multiple rules and their respective locations.

<CIT>, describes a method for arrhythmia analysis of ECG recordings. The method includes receiving and comparing ECG signals to known templates that are based on classifications of previously-identified complexes. Based on the comparisons, each of the received signals can be designated as normal, ventricular ectopic, supraventricular ectopic, or unknown (ectopy of unknown origin).

<CIT>, describes a method for non-captured intrinsic discrimination in cardiac pacing response classification. The method includes discriminating non-captured intrinsic beats during evoked response detection and classification by comparing the features of a post-pace cardiac signal with expected features associated with a non-captured response with intrinsic activation. In some embodiments, the detection of a non-captured response with intrinsic activation may be based on the peak amplitude and timing of the cardiac signal.

<CIT>, describes a method for the automated processing of electrophysiological data. The method includes determining temporal locations by defining one or more reference channels containing a reference beat and comparing beats of the recorded electrogram data against the defined one or more reference channels. An index of the temporal locations and other information of the beats within the recorded electrogram data is created, and the index of temporal locations can be used to analyze recorded electrogram data in order to locate electrophysiological features suggestive of an abnormality.

There is provided, in accordance with an embodiment of the present invention, an apparatus including a display, and a processor configured to receive sets of signals during multiple cardiac cycles, each set of the signals indicating, for a medical probe inserted into a cardiac chamber, a three-dimensional (3D) location of a distal end of the probe, electrical potentials measured at the 3D location, and respective times during a given cardiac cycle when the electrical potentials were measured, to compare the received electrical potential measurements and the respective times to a first template for a sinus rhythm cardiac cycle and a second template for a non-sinus rhythm cardiac cycle so as to identify a sequence of cardiac cycles including consecutive first, second, and third cardiac cycles wherein the first and second cardiac cycles are in accordance with the first template and the third cardiac cycle is in accordance with the second template, to generate a physical map of the cardiac chamber, based on the 3D locations indicated by the sets of signals received during the first and second cardiac cycles, and to render to a display, based on the received 3D locations and corresponding measured electrical potentials, an electroanatomic map including the local activation times for the non-sinus rhythm cardiac cycle overlaid on the physical map.

In some embodiments, the probe includes an intracardiac catheter having multiple electrodes that simultaneously generate respective sets of the signals.

In additional embodiments, the non-sinus rhythm cardiac cycle includes a premature ventricular contraction.

In one embodiment, generating the physical map includes generating a first physical map based on the 3D locations indicated by the sets of signals received during the first cardiac cycle and a second physical map based on the 3D locations indicated by the sets of signals received during the second cardiac cycle, and selecting either the first or the second physical map. In another embodiment, the second physical map is in accordance with the first physical map.

In supplemental embodiments, rendering the electroanatomic map including the local activation times for the non-sinus rhythm cardiac cycle overlaid on the physical map includes overlaying the local activation time of the non-sinus rhythm cardiac cycle indicated by each given signal at a map location corresponding to the 3D location indicated by the given signal.

In some embodiments, comparing the received electrical potential measurements and the respective times to a given template includes comparing a given signal indicating the received electrical potential measurements and the respective times to the given template.

In additional embodiments, the processor may be configured to identify a region of the map having earliest local activation times, and to flag, on the display, the identified region for ablation. In one embodiment, identifying the region of the map having earliest local activation times includes segmenting the map into multiple regions based on their respective local activation times, and identifying the region having the earliest local activation times.

There is further provided, in accordance with an embodiment of the present invention, a computer software product, operated in conjunction with a medical probe for insertion into a body cavity, the product including a non-transitory computer-readable medium, in which program instructions are stored, which instructions, when read by a computer, cause the computer to receive sets of signals during multiple cardiac cycles, each set of the signals indicating, for a medical probe inserted into a cardiac chamber, a three-dimensional (3D) location of a distal end of the probe, electrical potentials measured at the 3D location, and respective times during a given cardiac cycle when the electrical potentials were measured, to compare the received electrical potential measurements and the respective times to a first template for a sinus rhythm cardiac cycle and a second template for a non-sinus rhythm cardiac cycle so as to identify a sequence of cardiac cycles including consecutive first, second, and third cardiac cycles wherein the first and second cardiac cycles are in accordance with the first template and the third cardiac cycle is in accordance with the second template, to generate a physical map of the cardiac chamber, based on the 3D locations indicated by the sets of signals received during the first and second cardiac cycles, and to render to a display, based on the received 3D locations and corresponding measured electrical potentials, an electroanatomic map including the activation times for the non-sinus rhythm cardiac cycle overlaid on the physical map.

The disclosure is herein described, by way of example only, with reference to the accompanying drawings, wherein:.

Generating a local activation time (LAT) map of a heart with an arrhythmia is typically a difficult and time-consuming process. The LAT map is generated from information collected during sinus and non-sinus cardiac cycles, and the selection of the different types of cardiac cycles (also known as beats) by a medical professional (e.g., a physician) can be time consuming.

Embodiments of the present invention provide methods and systems for automatically generating an electroanatomic LAT hybrid map that maps premature ventricular contractions (PVCs) for an arrhythmic heart. As described hereinbelow, an intra-cardiac probe is inserted into a cardiac chamber, and sets of signals are received during multiple cardiac cycles, each set of the signals indicating a three-dimensional (3D) location of a distal end of the probe, electrical potentials measured at the 3D location, and respective times during a given cardiac cycle when the electrical potentials were measured.

The received electrical potential measurements and the respective times are compared to a first template for a normal sinus rhythm (also referred to herein simply as sinus rhythm) cardiac cycle and a second template for a non-sinus rhythm cardiac cycle so as to identify a sequence of cardiac cycles comprising consecutive first, second, and third cardiac cycles, wherein the first and second cardiac cycles are in accordance with the first template and the third cardiac cycle is in accordance with the second template. A physical map of the cardiac chamber is generated based on the received 3D locations, and based on the received 3D locations and corresponding measured electrical potentials, an electroanatomic map comprising the local activation times for the non-sinus rhythm cardiac cycle overlaid on the physical map is rendered to a display. The resultant map may then typically be used to select a region for ablation, since it indicates an origin of the PVC. Using templates to identify sinus and non-sinus cardiac cycles enables systems implementing embodiments of the present invention to rapidly generate electroanatomic LAT maps for an arrhythmic heart without requiring any user input to identify the sinus and non-sinus cardiac cycles. In some embodiments, the physical map may be generated solely based on the 3D coordinates received during the first and second cardiac cycles (i.e., the sinus rhythm cardiac cycles). By only using 3D location coordinates collected from the sinus rhythm cardiac cycles, embodiments of the present invention can produce a more stable physical map having fewer errors due to the unstable or "jumpy" nature of adjacent non-sinus cardiac cycles such as PVCs.

<FIG> and <FIG> are schematic, pictorial illustrations of a medical system <NUM> comprising a medical probe <NUM> and a control console <NUM>, and <FIG> is a schematic pictorial illustration of a distal end <NUM> of the medical probe <NUM>, in accordance with an embodiment of the present invention. Medical system <NUM> may be based, for example, on the CARTO® system, produced by Biosense Webster Inc. of <NUM> Technology Drive, Irvine, CA <NUM> USA. In embodiments described hereinbelow, medical probe <NUM> can be used for diagnostic or therapeutic treatment, such as for such as mapping electrical potentials of a heart <NUM> of a patient <NUM>. In embodiments described herein, medical probe <NUM> may also be referred to as a mapping catheter. Alternatively, medical probe <NUM> may be used, mutatis mutandis, for other therapeutic and/or diagnostic purposes in the heart or in other body organs.

During a medical procedure, a medical professional <NUM> inserts medical probe <NUM> into a biocompatible sheath <NUM> (<FIG>) that has been pre-positioned in a body cavity (e.g., a chamber of heart <NUM>) of the patient so that distal end <NUM> of the medical probe enters the body cavity. By way of example, as shown in <FIG>, distal end <NUM> of probe <NUM> comprises flexible splines <NUM> that are formed at the end of a tubular shaft <NUM>. During a medical procedure, medical professional <NUM> can deploy splines <NUM> by extending tubular shaft from sheath <NUM>.

Control console <NUM> is connected, by a cable <NUM>, to body surface electrodes, which typically comprise adhesive skin patches <NUM> that are affixed to patient <NUM>. Control console <NUM> comprises a processor <NUM> that, in conjunction with a current tracking module <NUM>, determines position coordinates of the distal end <NUM> inside the heart <NUM> based on impedances measured between adhesive skin patches <NUM> and electrodes <NUM> that are affixed to splines <NUM> as shown in <FIG>. In embodiments described herein, electrodes <NUM> can also be configured to apply a signal to tissue in heart <NUM>, and/or to measure a certain physiological property (e.g., the local surface electrical potential) at a location in the heart. Electrodes <NUM> are connected to control console <NUM> by wires (not shown) running through medical probe <NUM>.

While embodiments herein show probe <NUM> comprising a multi-spline intracardiac catheter such as the Pentaray® NAV catheter, using other multi-electrode intracardiac catheters such as the Navistar® Thermocool® catheters is possible.

The Pentaray® NAV and Navistar® Thermocool® catheters are both produced by Biosense Webster Inc.

Processor <NUM> may comprise real-time noise reduction circuitry <NUM> typically configured as a field programmable gate array (FPGA), followed by an analog-to-digital (A/D) ECG (electrocardiograph) signal conversion integrated circuit <NUM>. The processor can pass the signal from A/D ECG circuit <NUM> to another processor and/or can be programmed to perform one or more algorithms disclosed herein, each of the one or more algorithms comprising steps described hereinbelow. The processor uses circuitry <NUM> and circuit <NUM>, as well as features of modules which are described in more detail below, in order to perform the one or more algorithms.

The medical system shown in <FIG>, <FIG>, and <FIG> uses impedance-based sensing to measure a location of distal end <NUM>, but other position tracking techniques may be used (e.g., techniques using magnetic-based sensors). Impedance-based position tracking techniques are described, for example, in <CIT>, <CIT> and <CIT>. Magnetic position tracking techniques are described, for example, in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>. The methods of position sensing described hereinabove are implemented in the above-mentioned CARTO® system and are described in detail in the patents cited above.

Control console <NUM> also comprises an input/output (I/O) communications interface <NUM> that enables the control console to transfer signals from, and/or transfer signals to electrodes <NUM> and adhesive skin patches <NUM>. Based on signals received from electrodes <NUM> and/or adhesive skin patches <NUM>, processor <NUM> can generate an electroanatomic local activation time (LAT) map <NUM> that presents measurements of cardiac conduction velocity, as described in the description referencing <FIG> hereinbelow.

During a procedure, processor <NUM> can present electroanatomic LAT map <NUM> to medical professional <NUM> on a display <NUM>, and store data representing the electroanatomic LAT map in a memory <NUM>. Memory <NUM> may comprise any suitable volatile and/or non-volatile memory, such as random access memory or a hard disk drive. In some embodiments, medical professional <NUM> can manipulate map <NUM> using one or more input devices <NUM>. In alternative embodiments, display <NUM> may comprise a touchscreen that can be configured to accept inputs from medical professional <NUM>, in addition to presenting map <NUM>.

As shown in <FIG>, memory <NUM> stores signals <NUM> received by processor <NUM>, each given signal <NUM> comprising an ordered pair of a sampling time <NUM> indicating when the given signal was received, and an electrical potential <NUM> measured by adhesive skin patches <NUM> or a given electrode <NUM>, as described hereinbelow. In <FIG>, signals <NUM> and their respective sampling times <NUM> and electrical potentials <NUM> are differentiated by appending a letter to the identifying numeral, so that the signals comprise signals 60A-60C, the sampling times comprise sampling times 61A-61C, and the electrical potentials comprise electrical potentials 62A-62C. In embodiments described herein, signals 60A comprise body-surface ECG signals received from patches <NUM>, signals 60B comprise location signals received from patches <NUM> and indicating respective locations <NUM> of electrodes <NUM>, and signals 60C comprise intracardiac ECG signals received from electrodes <NUM>.

In the configuration shown in <FIG>, memory <NUM> also stores a set of electrode location records <NUM>, a set of intracardiac ECG records <NUM>, and a set of ECG templates <NUM>. Each electrode location record <NUM> comprises an electrode identifier (ID) <NUM> indicating a given electrode <NUM>, a set of location signals 60B received from adhesive skin patches <NUM> for the given electrode, and a set of locations <NUM> having a one-to-one correspondence with electrodes <NUM>. Each given location <NUM> typically comprises a set of 3D coordinates generated from its corresponding electrical potentials 62B.

In some embodiments, electrode location records <NUM> have a one-to-one correspondence with electrodes <NUM>, and processor <NUM> can initialize the set of electrode location records <NUM> by storing, to each electrode ID <NUM>, a unique numeric value or text string indicating the corresponding electrode <NUM>.

Each intracardiac ECG record <NUM> comprises an electrode ID <NUM> indicating a given electrode <NUM>, and a set of intracardiac ECG signals 60C received from the indicated electrode. In some embodiments, intracardiac ECG records <NUM> have a one-to-one correspondence with electrodes <NUM>, and processor <NUM> can initialize the set of intracardiac ECG records <NUM> by storing, to each electrode ID <NUM>, a unique numeric value or text string indicating the corresponding electrode <NUM>.

Each ECG template <NUM> comprises a cardiac cycle type <NUM> and a corresponding set of template ECG signals <NUM>, each of the template ECG signals comprising a time <NUM> and an electrical potential <NUM>. Examples of cardiac cycle types <NUM> include, but are not limited to, a normal sinus rhythm, and a non-sinus rhythm such as a premature ventricular contraction (PVC).

In operation, processor <NUM> can receive signals <NUM>, and store the received signals to memory <NUM> using the following embodiments:.

Control console <NUM> may also comprise an electrocardiogram (ECG) module <NUM> that can be configured to generate an ECG chart <NUM> from body surface ECG signals 60A. In some embodiments, processor <NUM> presents ECG chart <NUM> on display <NUM> (i.e., along with LAT map <NUM>). In addition to presenting ECG chart <NUM> on display <NUM>, processor <NUM> can store the ECG chart to memory <NUM>. Further details of ECG chart <NUM> are described in the description referencing <FIG> hereinbelow.

<FIG> is a flow diagram that schematically illustrates a method for mapping a chamber of heart <NUM>, and <FIG> is a schematic detail view of splines <NUM> engaging intracardiac tissue <NUM> in the chamber, in accordance with an embodiment of the present invention. In a load step <NUM>, processor <NUM> loads, to memory <NUM>, a plurality of templates <NUM> comprising at least one template <NUM> for a sinus rhythm cardiac cycles and at least one template <NUM> for a non-cardiac cardiac cycle.

In an insertion step <NUM>, medical professional <NUM> inserts distal end <NUM> into the chamber so that splines <NUM> engage intracardiac tissue <NUM>, and in a maneuvering step <NUM>, medical professional <NUM> moves the splines at the distal end along intracardiac tissue <NUM> during multiple cardiac cycles. As medical professional <NUM> moves the splines along the intracardiac tissue during the multiple cardiac cycles, processor <NUM> receives, in a receiving step <NUM>, body-surface ECG signals 60A, location signals 60B and intracardiac ECG signals 60C.

In identification step <NUM>, processor <NUM> identifies, by comparing the received body-surface ECG signals 60A to ECG templates <NUM>, three consecutive cardiac cycles comprising two sinus cardiac rhythm cycles followed by a non-sinus rhythm cardiac cycle. In some embodiments, comparing body-surface ECG signals 60A to templates <NUM> comprises comparing sampling times 61A and the electrical potentials 62A in the body-surface ECG signals to times <NUM> and electrical potentials <NUM> in the templates.

As described supra, a first given template <NUM> can be defined for a sinus rhythm cardiac cycle, and a second given template <NUM> can be defined for a non-sinus rhythm cardiac cycle such as a premature ventricular contraction. In embodiments of the present invention, processor <NUM> can identify the three cardiac cycles by comparing body-surface ECG signals 60A to templates <NUM> and detecting that the body-surface ECG signals during the first two cardiac cycles match a first given template <NUM> for a sinus rhythm cardiac cycle, and detecting that the body-surface ECG signals during the subsequent third cardiac cycle match a second given template <NUM> for a non-sinus rhythm cardiac cycle. Therefore, processor <NUM> can identify a first set sampling times <NUM> for the first two cardiac cycles and a second set of sampling times <NUM> for the third cardiac cycle.

To match, during a given cardiac cycle, body-surface ECG signals 60A to a given template <NUM>, processor <NUM> can perform a correlation between the body-surface ECG signals and the given template, and detect a match by comparing the correlation to predefined thresholds, and determining there is a high correlation (i.e., within a defined threshold) between the body-surface ECG signals and the given template. For example, processor <NUM> can use a correlation threshold of <NUM> when comparing body-surface ECG signals 60A to a given template <NUM> for a non-sinus rhythm cardiac cycle, and can use a correlation threshold of <NUM> when comparing the body-surface ECG signals to a given template <NUM> for a sinus rhythm cardiac cycle.

<FIG> is a schematic pictorial illustration of ECG chart <NUM>, in accordance with an embodiment of the present invention. ECG chart <NUM> comprises a trace comprising a line <NUM> that plots electrical potentials 61A in a given set of body-surface ECG signal 60A along a vertical axis <NUM> against time along a horizontal axis <NUM>, wherein electrical potentials 61A are measured as voltages V and the time is measured in seconds S. In the example shown in <FIG>, line <NUM> shows electrical potentials 61A in a given set of body-surface ECG signals 60A measured during a sequence of consecutive cardiac cycles <NUM>, <NUM> and <NUM>, wherein cardiac cycles <NUM> and <NUM> are sinus rhythm, and wherein cardiac cycle <NUM> comprises a premature ventricular contraction (i.e., an example of a non-sinus rhythm cardiac cycle).

Returning to the flow chart, in a first generation step <NUM>, processor <NUM> generates, based on 3D coordinates indicated by locations <NUM>, a physical map of the cardiac chamber. The physical map is described in the description referencing <FIG>, hereinbelow. In some embodiments, processor <NUM> uses 3D coordinates indicated by locations <NUM> from location signals 60B whose respective sampling times 61B were during the two sinus rhythm cardiac cycles in order to create a more stable physical map (i.e., ignoring 3D coordinates indicated by locations <NUM> from location signals 60B whose respective sampling times 61B were during the non-sinus rhythm cardiac cycle), as described supra.

Using a physical map comprising 3D coordinates indicated by locations <NUM> from location signals 60B whose respective sampling times 61B were during normal sinus-rhythm cardiac cycles can help create a more useful physical map since heart <NUM> is typically in sinus rhythm most of the time. For example, during an ablation procedure using an ablation catheter (not shown), if the non-sinus cardiac cycles comprise PVCs, heart <NUM> will typically be in sinus rhythm, with intermittent short PVC bursts. Therefore if processor <NUM> creates the physical map with 3D coordinates indicated by locations <NUM> from location signals 60B whose respective sampling times 61B were during a PVC cardiac cycle, a discrepancy likely exists between the locations of the map's points (PVC geometry) and distal end <NUM>, as the ablation catheter location is displayed mostly in sinus rhythm. As a result, any ablated area may not be optimum to correct the patient's arrhythmia. It is believed that the geometry of the heart differs during sinus rhythm, compared to its geometry during non-sinus cardiac cycles such as PVCs.

In additional embodiments, processor <NUM> can generate the physical map by creating a first physical map for the 3D coordinates indicated by locations <NUM> from location signals 60B whose respective sampling times 61B were during the first (i.e., sinus rhythm) cardiac cycle, creating a second physical map for the 3D coordinates indicated by locations <NUM> from location signals 60B whose respective sampling times 61B were during the second (i.e., sinus rhythm) cardiac cycle, and selecting either the first of the second physical map as physical map. The physical map is described in the description referencing <FIG> hereinbelow.

In some embodiments, processor <NUM> can generate the physical map only if body-surface ECG signals 60A whose respective sampling times 61A were during the first and second sinus rhythm cardiac cycles match (i.e., within a specified threshold) a given template <NUM> for a sinus rhythm cardiac cycle. In other words, processor <NUM> can generate the physical map only if the first and the second maps are substantially the same (i.e., in accordance with one another).

In a second generation step <NUM>, processor <NUM> generates, based on locations <NUM> (i.e., as indicated in the location signals) and the corresponding electrical potentials 62C measured by electrodes <NUM> (i.e., as indicated in the intracardiac ECG signals), map <NUM> comprising local activation times for the non-sinus rhythm cardiac cycle overlaid on the physical map. (<CIT> describes overlaying PVC electrical data on a sinus rhythm physical map. ) In other words, map <NUM> reflects the geometry of heart <NUM> during sinus rhythm, but has the local activation times of the heart while experiencing PVCs.

Finally, in a rendering step <NUM>, processor <NUM> renders map <NUM> to display <NUM>, and the method ends. To render map <NUM>, processor <NUM> can render physical map <NUM> on display <NUM>, and overlay, on the physical map rendered on the display, the local activation time of the non-sinus rhythm cardiac cycle indicated by each given intracardiac ECG signal 60C at a map location corresponding to the location indicated by the corresponding location signal (i.e., where sampling times 61B and 61C match). An example of overlaying the local activation times on the physical map is described in the description referencing <FIG> hereinbelow.

<FIG> is a schematic pictorial illustration showing a section of LAT map <NUM> that comprises a physical map <NUM> of a chamber of heart <NUM>, in accordance with an embodiment of the present invention. In <FIG>, local activation time information for map <NUM> is incorporated into physical map <NUM> and coded using patterns in accordance with a key <NUM>. These patterns simulate the pseudocolors of an actual functional map. The patterns in key <NUM> correspond, from left to right, to a range of early to late LAT times (i.e., with regard to a reference time for a given cardiac cycle).

Therefore, in map <NUM>, a first region <NUM> has a relatively early LAT, and is circumscribed by an area <NUM> that has a relatively later local activation time. In embodiments described herein, regions <NUM> and <NUM> comprise map locations that correspond to the 3D locations indicated by the received signals. In operation, since region <NUM> processor <NUM> can identify and flag region <NUM> (i.e., the region with the earliest LAT in map <NUM>) as the region for ablation. Alternatively, medical professional can use input devices <NUM> to select and flag regions <NUM> and/or <NUM>.

Claim 1:
An apparatus for mapping local activation times for sinus and non-sinus cardiac cycles, the apparatus comprising:
a display (<NUM>); and
a processor (<NUM>) configured:
to receive sets of signals during multiple cardiac cycles, each set of the signals indicating, for a medical probe (<NUM>) inserted into a cardiac chamber, a three-dimensional (3D) location of a distal end of the probe, electrical potentials (<NUM>) measured at the 3D location, and respective times during a given cardiac cycle when the electrical potentials were measured,
to compare the received electrical potential measurements and the respective times to a first template (<NUM>) for a sinus rhythm cardiac cycle and a second template (<NUM>) for a non-sinus rhythm cardiac cycle so as to identify a sequence of cardiac cycles comprising consecutive first, second, and third cardiac cycles wherein the first and second cardiac cycles are in accordance with the first template and the third cardiac cycle is in accordance with the second template,
to generate a physical map of the cardiac chamber, based on the 3D locations indicated by the sets of signals received during the first and second cardiac cycles, and
to render to the display (<NUM>), based on the received 3D locations and corresponding measured electrical potentials, an electroanatomic map (<NUM>) comprising the local activation times for the non-sinus rhythm cardiac cycle overlaid on the physical map.