Pacing mapping of ventricular tachycardia (VT) using directional vector indication

Abstract

To evaluate electrical propagation within the heart. [Solution] The catheter is configured to apply pacing to a given tissue location inside the ventricle of the patient's heart. The ECG system is configured to acquire a set of ECG signals generated in response to pacing, and electrodes of the ECG system attached to the patient define their respective directions in space relative to an origin located in the heart. The processor is configured to calculate each set of signal differences between the acquired set of ECG signals and a reference set of ECG signals, and to calculate a corresponding set of deviation vectors along each direction in space, wherein the deviation vectors have amplitudes corresponding to each signal difference, and to use the deviation vectors to calculate a direction vector from a given location to a new ventricular location to which pacing will be applied, and to show the calculated direction vector to the user.

Description

Technical Field

[0001] The present invention generally relates to electrophysiological (EP) signals and, more particularly, to methods for the assessment of electrical propagation within the heart.

Background Art

[0002] The estimation of electrophysiological signals for determining the location of ventricular arrhythmias has been previously suggested in the patent literature. For example, U.S. Patent Application Publication No. 2024 / 0374199 describes a method that includes receiving cardiac signals from a plurality of locations within the ventricles of a patient's heart. The received signals are compared to a reference signal indicative of an arrhythmia. Based on this comparison, a direction towards a location that may show an increase in correlation between the received signal and the reference signal is calculated. The direction is presented to the user.

[0003] A more complete understanding of the present disclosure will be obtained by reading the following detailed description of the embodiments of the disclosure in conjunction with the drawings.

Brief Description of the Drawings

[0004] [Figure 1] Schematic drawing examples of a catheter-based electrophysiology (EP) pacing, mapping, and ablation system according to an embodiment of the present disclosure. [Figure 2A] Cross-sectional and sagittal views, respectively, of the orientation of the 12ECG electrodes of FIG. 1 with respect to locations inside the heart according to an embodiment of the present disclosure. [Figure 2B] Cross-sectional and sagittal views, respectively, of the orientation of the 12ECG electrodes of FIG. 1 with respect to locations inside the heart according to an embodiment of the present disclosure. [Figure 3] Graph of a set of reference and acquisition of EP signals from the 12ECG electrodes of FIG. 1 according to an embodiment of the present disclosure. [Figure 4]This is a schematic diagram illustrating the layout of deviation vectors derived from pacing data acquired by the system in Figure 1 to guide the user to the left ventricle (LV) arrhythmia-inducing region, according to an embodiment of the present disclosure. [Figure 5] This flowchart illustrates a method, according to the embodiments of this disclosure, for guiding a clinician to an LV arrhythmia-inducing location using data acquired by an ECG system. [Modes for carrying out the invention]

[0005] overview To characterize arrhythmias in cardiac chambers such as the left ventricle (LV), physicians may use a catheter to explore suspicious tissue pathways and circuits within the LV and to pace at multiple LV tissue locations (e.g., by applying a bipolar pacing signal between two adjacent catheter electrodes). If a transient arrhythmia-causing event, such as an ectopic contraction, premature contraction, or premature ventricle complex (PVC), is induced during pacing, the event may be recorded with a 12-lead ECG device showing an abnormal signal pattern.

[0006] Various methods can be used to recognize an arrhythmogenic event induced at a given ventricular location. For example, the processor may perform pattern matching (e.g., of a 12-read ECG waveform) between the acquired waveform and stored pattern waveform characteristics of arrhythmias (e.g., VT, PVC) to identify correlations. A high correlation indicates that the paced location is part of the arrhythmogenic tissue.

[0007] For physicians, determining the direction in which to move the catheter to obtain meaningful correlations is often challenging. Therefore, the traditional process of obtaining high-quality data and finding meaningful correlations involves pacing attempts at multiple tissue locations, a workflow that can be difficult to implement in real-world clinical scenarios.

[0008] Some embodiments of the present disclosure described below provide techniques for calculating and displaying directional arrows on a cardiac map (e.g., an EP map) after one or more pacing instances to direct an operator toward the best position and / or arrhythmia-inducing tissue area for the next pacing. The dimensions of the displayed arrows indicate the current paced position, as well as the distance from the next best pacing position and / or arrhythmia-inducing tissue area.

[0009] Directional arrows in 3D space are directly derived from scaled difference vectors in 3D space, extracted using mathematical calculations to correlate the acquired waveforms of a 12-lead ECG with the criterion 12-lead ECG waveform characteristics of the arrhythmia. The disclosed technique provides a simple workflow for clinicians to identify VT target locations with a minimum number of pacing steps during clinical procedures. This workflow significantly increases the efficiency and accuracy of VT pacing mapping.

[0010] In one embodiment, a method is provided that includes transmitting a pacing signal to a catheter and, in response, receiving an ECG signal from a 12-lead recorder. The correlation level between the received ECG signal and a reference ECG signal indicating arrhythmia is calculated. A set of amplitude deviation vectors in 3D space of a given amplitude (e.g., given in mV) is calculated between each received ECG signal and its respective reference ECG signal (e.g., at the peak of the received ECG signal). The direction of each amplitude deviation vector is set along the orientation of each respective ECG lead relative to its position within the heart.

[0011] (As shown in Figure 4) summing all amplitude deviation vectors gives a difference vector. The resulting difference vector points in the correct direction of the VT focus, or at least towards the next recommended ventricular position for pacing. The direction is represented on the cardiac map by an arrow that instructs the operator where to adjust the catheter position for the next pacing. The size of the displayed arrow depends on the magnitude of the difference vector (larger size indicates that a larger catheter movement is required in the specified direction).

[0012] The arrows are refreshed with additional pacing steps until they become small enough to conclude (e.g., graphically indicated on the map) that the target region has been reached and / or the calculated correlation is sufficiently high (e.g., above a predetermined threshold).

[0013] In another embodiment, the time difference (e.g., in milliseconds) is calculated between each current ECG signal and a reference ECG signal (e.g., between the peak of the current ECG signal and the peak of the reference signal). This time difference also functions as the magnitude of a directional 3D vector between a given origin position of the heart and the position of each ECG lead. The difference vector is determined by summing all the time difference vectors. The resulting difference vector also points in the correct direction of the VT focus.

[0014] In yet another embodiment, the difference vector is calculated by a weighted sum over all amplitude deviation vectors or time difference vectors. The weights are either estimated by a model or empirically to reflect the geometric shape of the 12 leads and the anatomical structure of the heart, improving the accuracy of the difference vector and, subsequently, the accuracy of the guide arrows presented to the clinician.

[0015] System Description Figure 1 is a schematic diagram illustrating a catheter-based electrophysiological (EP) pacing, mapping, and ablation system 10 according to an embodiment of the present disclosure.

[0016] System 10 includes a catheter 14 that is inserted percutaneously through a sheath by a physician 24 into the left ventricle (LV) 33 of the patient's heart 12, via the patient's vascular system. The catheter 14 illustrated herein is configured for unipolar or bipolar pacing. The physician 24 brings the tip distal end assembly 28 of the catheter 14 into contact with the heart wall to pace a location over a given area of ​​the LV 33.

[0017] As shown in inset 45, the distal end assembly 28 carries several electrodes 26 for pacing and, optionally, for electrically ablating LV33 wall tissue that has been found to be arrhythmia-causing.

[0018] The catheter 14 may further carry a magnetic position sensor that operates with a position pad 25, which includes a plurality of magnetic coils 32 configured to generate a magnetic field within a predetermined working range. The real-time position of the distal tip 28 of the catheter 14 can be tracked based on the magnetic field generated by the position pad 25 and sensed by the magnetic position sensor. Details of magnetic position sensing technology are described in U.S. Patents 5,5391,199, 5,443,489, 5,558,091, 6,172,499, 6,239,724, 6,332,089, 6,484,118, 6,618,612, 6,690,963, 6,788,967, and 6,892,091.

[0019] System 10 includes one or more electrode patches 38 positioned to be in skin contact with patient 23 to establish a position reference for position pad 25 and impedance-based tracking of electrodes 26. For impedance-based tracking, current is directed to electrodes 26 and sensed at electrode-skin patches 38, whereby the position of each electrode can be triangulated via electrode patches 38. Details of impedance-based position tracking techniques are described in U.S. Patent Nos. 7,536,218, 7,756,576, 7,848,787, 7,869,865, and 8,456,182.

[0020] Recorder 11 displays cardiac signal 21 (e.g., an electrogram from a 12-lead ECG device 35 obtained using body surface ECG electrodes 18). Recorder 11 may include pacing capabilities for pacing the rhythm of the heart and / or may be electrically connected to an independent pacer.

[0021] Patient interface unit (PIU) 30 is an interface configured to establish electrical communication between a catheter, electrophysiology equipment, a power source, and workstation 55 to control the operation of system 10 and to receive EP signals from the catheter or apply pacing signals. The electrophysiology equipment of system 10 may include, for example, a plurality of catheters, position pad 25, body surface ECG electrodes 18, electrode patches 38, ablation energy generator 50, and recorder 11. Optionally and preferably, PIU 30 additionally includes processing capabilities for implementing real-time calculation of catheter position and performing ECG calculations.

[0022] Workstation 55 includes a memory 57, a processor 56 unit with a memory or loaded with appropriate operating software, and a user interface function. The workstation 55 may optionally (i) render to model the endocardial anatomical structure in three dimensions (3D) and display a model or anatomical map 20 on a display device 27, (ii) display on the display device 27 a representative visual display or image in which an activation sequence (or other data) compiled from the recorded heart signals 21 is superimposed on the rendered anatomical map 20, (iii) display the real-time position and orientation of a plurality of catheters within the ventricle, and (iv) display on the display device 27 a site of interest such as a location where ablation energy has been applied, and may provide a plurality of functions including these. One commercially available product embodying the elements of system 10 is available as the CARTO (trademark) 3 system obtainable from Biosense Webster, Inc., 31A Technology Drive, Irvine, CA, 92618.

[0023] In FIG. 1, catheter 14 paces LV tissue location 66A. The resulting ECG signal correlation with a reference signal is found to be too low, which means that location 66A is not VT arrhythmogenic tissue, i.e., correlation alone is not sufficient for the physician to proceed with pacing. Using the disclosed technique, direction vector 128 is calculated from a set of ECG signals and reference signals obtained at location 66A (e.g., the signals of FIG. 3). The scaled direction vector 128 superimposed on map 20 guides clinician 24 (e.g., physician 24) to move catheter 14 in the correct direction. In the illustrated embodiment, vector 128 points towards LV tissue location 66B, which should be more arrhythmogenic (and thus result in a higher correlation indication (166)). It is also possible that location 66B is the actual target location, in which case physician 24 may ablate the area around location 66B.

[0024] In some embodiments, the processor 56 typically comprises a general-purpose computer programmed with software to perform the functions described herein. The software may, for example, be downloaded to the computer over a network in electronic form, or alternatively or additionally, be provided and / or stored on a non-temporary tangible medium such as magnetic memory, optical memory, or electronic memory.

[0025] System 10 may include an ablation energy generator 50 adapted to conduct ablation energy to one or more electrodes located at the distal tip of a catheter configured for ablation. The energy generated by the ablation energy generator 50 may include, but is not limited to, radiofrequency (RF) energy or pulsed-field ablation (PFA) energy, or a combination thereof, including unipolar or bipolar high-voltage DC pulses used to achieve irreversible electroporation (IRE).

[0026] For ablation, the physician 24 similarly brings the distal end of the ablation catheter to the target site. One or more additional catheters may be inserted through the sheath. These may include a catheter for sensing intracardiac electrogram signals, a catheter dedicated to ablation, and / or a catheter dedicated to both EP mapping and ablation.

[0027] This configuration of System 10 is shown as an example to illustrate certain problems addressed by the embodiments of this disclosure and to demonstrate the application of these embodiments in improving the performance of such systems. However, the embodiments of this disclosure are by no means limited to this specific type of exemplary system, and the principles described herein may be similarly applied to other types of medical systems. For example, other catheter types such as LASSO® catheters or basket catheters may be used.

[0028] VT pacing mapping using direction vector indication Figures 2A and 2B are cross-sectional view 202 and sagittal view 204, respectively, of the orientation 210 of the ECG electrode 18 of Figure 1 relative to a position 101 inside the heart 12, according to an embodiment of the present disclosure. The cross-sectional and sagittal views define the xy and xz planes of the XYZ system 102 (also shown in Figure 3) with mutually orthogonal axes, respectively. The orientation of the ECG electrode placed on the patient's torso is defined in the system 102 with respect to the position origin 101.

[0029] As seen in Figure 2, the 12 axes of the 12 ECG leads are not designed to extend across the entire 3D space, but are nevertheless useful for spreading in the direction of the ventricle, such as the direction of vector 128 in Figure 1. This spreading is derived by projecting the ECG signal difference onto direction 210, as explained in Figure 4. Thus, the technique obtains 12 deviation vectors 118 in Figure 4 to be derived from the aforementioned scaled difference vector 128, which are then presented as pacing lead arrows on the cardiac map 20 of the ventricle.

[0030] Figure 3 is a graph 302 of a set of reference 301 acquired during a VT event and a set of EP signals 303 acquired from the 12 ECG electrodes 18 in Figure 1, according to an embodiment of the present disclosure. Using the exact same set of electrodes 18 attached to the patient's skin, set 303 is acquired during the diagnostic stage (pacing) described in Figure 1. The difference in linear shape between set 301 and set 303 reflects the fact that set 303 was acquired when pacing was performed at a location removed from the arrhythmia-causing tissue area (e.g., normal tissue was paced).

[0031] The disclosed technique quantifies the difference between signals in the form of amplitudes 304 (e.g., given in mV). These amplitudes can be seen as a quantification of how much the acquired signal differs from each reference signal at a given electrode 18. As can be seen from the figure, some of the amplitudes 304 are small, and others are large. The amplitudes 304 are used in Figure 4 below to calculate each set of amplitude deviation vectors 118 in 3D space.

[0032] Figure 4 is a schematic diagram illustrating the layout of deviation vectors 118 derived from pacing data acquired by the system of Figure 1 to guide the user to the left ventricular (LV) arrhythmia-inducing region, according to an embodiment of the present disclosure. Figure 4 shows several ECG electrodes 18, electrodes 18A-18E located on the anterior side of the patient (e.g., chest 15), and electrodes 18F-18G located on the lateral or posterior side of the patient.

[0033] As described above, direction 210 can be defined in the system 102 of the XYZ axes from the origin 101 to each electrode 18. Using the amplitude 304 in Figure 3, the processor calculates the amplitude deviation vectors 118A to 118E (112) (shown as an example, here in reality all 12 vectors are calculated). The weighted sum (120) of the amplitude deviation vectors 118A to 118E gives the scaled direction vector V, 128.

[0034]

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[0035]

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[0036]

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[0037] A scaling factor C for vector 128 in units [cm / mV] allows vector 128 to be presented as an arrow on map 20 between the current pacing position 66A and the next recommended pacing position 66B. Typical dimensions of scaling factor C are in the range of 0.5–2 [cm / mV]. The arrow is presented on cardiac map 20 to guide the physician 24.

[0038] Method for pacing mapping of VT using direction vector indication Figure 5 is a flowchart illustrating how, according to an embodiment of the present disclosure, a clinician is guided to an LV arrhythmia-inducing location using data acquired by the ECG system 11. As described above, each electrode 18 of the ECG system 11 attached to the patient defines a spatial orientation 210 with respect to an origin 101 located within the heart.

[0039] According to the example provided, the algorithm performs a process that begins in catheter insertion step 502 with inserting the pacing catheter 14 into the ventricle 33 of the heart 12.

[0040] Next, in pacing step 504, the system 10 paces a given tissue location within the ventricle using the electrodes of the catheter 14.

[0041] In response to pacing, during the signal reception step 506, the system 10 receives the respective ECG signals from the body surface electrodes 18.

[0042] Next, in the amplitude calculation step 508, the processor 56 calculates each set of signal differences 304 between the acquired set of ECG signals 303 and the reference set of ECG signals 301. The processor substitutes the amplitudes (i.e., the measured signals minus each reference signal) into the algorithm's vector equations.

[0043] In the deviation vector calculation step 510, the processor 56 calculates a set of corresponding deviation vectors 118 along each direction 210 in space, where the deviation vectors have a calculated amplitude 304.

[0044] In the direction vector calculation step 512, the processor uses deviation vectors to calculate a scaled direction vector 128 from a given position 66A to a new ventricular position 66B to be paced.

[0045] In the arrow presentation step 514, the processor displays the calculated scaled direction vector 128 on the cardiac map 20 of at least a portion of the ventricle.

[0046] The flowchart in Figure 5 is an example. For example, a set of weights w is used when calculating the direction vector 128. iThis may include additional steps, such as uploading the scaling factor C from memory 57, but these have been omitted for simplicity. [Examples]

[0047] (Example 1) The system (10) includes a catheter (14), an electrocardiogram (ECG) system (35), and a processor (56). The catheter is configured to apply pacing to a given tissue location inside the ventricle of the patient's (23) heart (12). The ECG system is configured to acquire a set of ECG signals (303) generated in response to pacing, and the electrodes (18) of the ECG system (35) attached to the patient define their respective directions (210) in space with respect to an origin (101) located in the heart. The processor is configured to (i) calculate each set (304) of signal differences between the acquired set of ECG signals (303) and the reference set of ECG signals (301); (ii) calculate a set of corresponding deviation vectors (118) along each direction (210) in space, wherein the deviation vectors have amplitudes corresponding to each signal difference (304); (iii) use the deviation vectors (118) to calculate a direction vector (128) from a given position (66A) to a new ventricular position (66B) to which pacing is applied; and (iv) present the calculated direction vectors (128) to the user.

[0048] (Example 2) The system (10) according to claim 1, wherein the processor (56) is configured to calculate a direction vector (128) by performing a weighted sum on the deviation vector (118).

[0049] (Example 3) The system (10) according to claim 1, wherein the signal difference (304) is one of the amplitude difference and the time difference.

[0050] (Example 4) The ECG system (35) is a 12-read ECG system, according to claim 1, system (10).

[0051] (Example 5) The system (10) according to claim 1, wherein the origin (101) is one of (i) the sinoatrial node (SA) and (ii) a given tissue location (66A) to which pacing is applied.

[0052] (Example 6) The system (10) according to claim 1, wherein the acquired set of ECG signals (303) and the reference set of ECG signals (301) are obtained using the same electrodes (18) of the ECG system (35).

[0053] (Example 7) The system (10) according to claim 1, further configured to show the calculated direction vector (128) to the user by displaying the calculated direction vector (128) on a cardiac map (20) of at least a portion of the ventricle.

[0054] (Example 8) The system (10) according to claim 1, wherein the processor (56) is further configured to indicate a new ventricular position (66B) as an arrhythmia-inducing position when the dimension of the direction vector (128) is smaller than a predetermined dimension.

[0055] (Example 9) The method involves using a catheter (14) to apply pacing to a given tissue location within the ventricle of the patient's heart (12). A set of ECG signals (303) generated in response to the pacing is acquired using an electrocardiogram (ECG) system (35), and electrodes (18) of the ECG system attached to the patient define their respective directions (210) in space relative to an origin (101) located in the heart. A set of signal differences (304) is calculated between the acquired set of ECG signals (303) and a reference set of ECG signals (301). A set of corresponding deviation vectors (118) along each direction (210) in space is calculated, and the deviation vectors have amplitudes corresponding to their respective signal differences. A direction vector (128) is calculated using the deviation vectors from a given location (66A) to a new ventricular location (66B) to which pacing is applied. The calculated direction vectors (128) are shown to the user.

[0056] The embodiments described above are for illustrative purposes only, and it will be understood that this disclosure is not limited to those specifically illustrated and described above. Rather, the scope of this disclosure includes both combinations and partial combinations of the various features described above, as well as variations and modifications thereof not disclosed in the prior art, which will be conceived by those skilled in the art as they read the foregoing description.

[0057] [Implementation Method] (1) A system, A catheter configured to apply pacing to a given tissue location within the ventricle of a patient's heart, An electrocardiogram (ECG) system configured to acquire a set of ECG signals generated in response to the pacing, wherein the electrodes of the ECG system attached to the patient define their respective directions in space relative to an origin located at the heart, It is a processor, The process involves calculating each set of signal differences between the acquired set of ECG signals and the set of reference ECG signals, The calculation involves calculating a set of corresponding deviation vectors along each of the aforementioned directions in space, wherein the deviation vectors have amplitudes corresponding to each of the aforementioned signal differences. Using the aforementioned deviation vector, calculate the direction vector from the given position to the new ventricular position to which the pacing is applied, A system comprising a processor configured to display the calculated direction vector to the user. (2) The system according to Embodiment 1, wherein the processor is configured to calculate the direction vector by performing a weighted sum on the deviation vector. (3) The system according to Embodiment 1, wherein the signal difference is one of the amplitude difference and the time difference. (4) The system according to Embodiment 1, wherein the ECG system is a 12-read ECG system. (5) The system according to Embodiment 1, wherein the origin is (i) the sinoatrial node (SA) and (ii) one of the given tissue locations to which the pacing is applied.

[0058] (6) The system according to Embodiment 1, wherein the acquired set of ECG signals and the reference set of ECG signals are obtained using the same electrodes of the ECG system. (7) The system according to Embodiment 1, wherein the processor is further configured to show the calculated direction vector to the user by displaying the calculated direction vector on a cardiac map of at least a portion of the ventricle. (8) The system according to Embodiment 1, wherein the processor is further configured to indicate a new position of the ventricle as an arrhythmia-inducing position when the dimension of the direction vector is smaller than a predetermined dimension. (9) A method, Using a catheter, pacing is applied to a given tissue location within the ventricle of the patient's heart. The acquisition of a set of ECG signals generated in response to the pacing using an electrocardiogram (ECG) system, wherein the electrodes of the ECG system attached to the patient define their respective directions in space relative to an origin located at the heart. The process involves calculating each set of signal differences between the acquired set of ECG signals and the set of reference ECG signals, The calculation involves calculating a set of corresponding deviation vectors along each of the aforementioned directions in space, wherein the deviation vectors have amplitudes corresponding to each of the aforementioned signal differences. Using the aforementioned deviation vector, calculate the direction vector from the given position to the new ventricular position to which the pacing is applied, A method comprising showing the calculated direction vector to the user. (10) The method according to embodiment 9, wherein calculating the direction vector includes performing a weighted sum on the deviation vector.

[0059] (11) The method according to embodiment 9, wherein the signal difference is one of the amplitude difference and the time difference. (12) The method according to embodiment 9, wherein the ECG system is a 12-read ECG system. (13) The method according to Embodiment 9, wherein the origin is (i) the sinoatrial node (SA) and (ii) one of the given tissue locations to which the pacing is applied. (14) The method according to Embodiment 9, wherein the acquired set of ECG signals and the reference set of ECG signals are obtained using the same electrodes of the ECG system. (15) The method of Embodiment 9, which includes showing the calculated direction vector to the user by displaying the calculated direction vector on a cardiac map of at least a portion of the ventricle.

[0060] (16) The method according to Embodiment 9, which includes indicating the new position of the ventricle as an arrhythmia-inducing position when the dimension of the direction vector is smaller than a predetermined dimension.

Claims

1. It is a system, A catheter configured to apply pacing to a given tissue location within the ventricle of a patient's heart, An electrocardiogram (ECG) system configured to acquire a set of ECG signals generated in response to the pacing, wherein the electrodes of the ECG system attached to the patient define their respective directions in space relative to an origin located at the heart, It is a processor, The process involves calculating the signal difference between each set of the acquired ECG signals and the set of reference ECG signals, The calculation involves calculating a set of corresponding deviation vectors along each of the aforementioned directions in space, wherein the deviation vectors have amplitudes corresponding to each of the aforementioned signal differences. Using the aforementioned deviation vector, calculate the direction vector from the given position to the new ventricular position to which the pacing is applied, A system comprising a processor configured to display the calculated direction vector to the user.

2. The system according to claim 1, wherein the processor is configured to calculate the direction vector by performing a weighted sum on the deviation vector.

3. The system according to any one of claims 1 to 2, wherein the signal difference is one of an amplitude difference and a time difference.

4. The ECG system is a 12-read ECG system, according to any one of claims 1 to 2.

5. The system according to any one of claims 1 to 2, wherein the origin is (i) the sinoatrial node (SA) and (ii) one of the given tissue locations to which the pacing is applied.

6. The system according to any one of claims 1 to 2, wherein the acquired set of ECG signals and the reference set of ECG signals are obtained using the same electrodes of the ECG system.

7. The system according to any one of claims 1 to 2, wherein the processor is further configured to show the calculated direction vector to the user by displaying the calculated direction vector on a cardiac map of at least a portion of the ventricle.

8. The system according to any one of claims 1 to 2, wherein the processor is further configured to indicate a new position of the ventricle as an arrhythmia-inducing position when the dimension of the direction vector is smaller than a predetermined dimension.

9. It is a method, Using a catheter, pacing is applied to a given tissue location within the ventricle of the patient's heart. The acquisition of a set of ECG signals generated in response to the pacing using an electrocardiogram (ECG) system, wherein the electrodes of the ECG system attached to the patient define their respective directions in space relative to an origin located at the heart. The process involves calculating the signal difference between each set of the acquired ECG signals and the set of reference ECG signals, The calculation involves calculating a set of corresponding deviation vectors along each of the aforementioned directions in space, wherein the deviation vectors have amplitudes corresponding to each of the aforementioned signal differences. Using the aforementioned deviation vector, calculate the direction vector from the given position to the new ventricular position to which the pacing is applied, A method comprising showing the calculated direction vector to the user.

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