METHOD FOR DETERMINING A PLURALITY OF ACTION POTENTIALS IN THE HEART

Abstract

The disclosure relates to a method for determining a plurality of action potentials in the heart having the following steps:

a) Recording a surface ECG signal synchronously with at least 64 channels,

b) Recording at least one IEGM signal,

c) Processing the surface ECG signal by means of ICA analysis and determining the sum and position of a plurality of action potentials in the heart based on the ICA analysis, and,

d) Comparing the at least one IEGM signal to the plurality of action potentials and correcting the sum and/or position of at least one of the plurality of action potentials in the heart based on this comparison.

The disclosure further relates to a corresponding device, a corresponding computer program product, and a corresponding system.

Claims

1. A method for determining a plurality of action potentials in the heart having the following steps: a) Recording surface ECG signals synchronously with a plurality of channels, b) Recording at least one IEGM signal, c) Processing the surface ECG signal by means of ICA analysis and determining the sum and position of a plurality of action potentials in the heart based on the ICA analysis, d) Comparing the at least one IEGM signal to the plurality of action potentials and correcting the sum and/or the position of at least one of the plurality of action potentials in the heart based on this comparison.

2. The method according to claim 1, wherein the surface ECG is recorded synchronously with a plurality of channels, preferably 32 or 64 channels.

3. The method according to claim 1, wherein the comparison in step d) is performed by means of correlation calculation.

4. The method according to claim 1, wherein the sum and the position of the plurality of action potentials determined according to steps a) through d) are preferably illustrated by means of a two-dimensional or three-dimensional model of the heart in a two-dimensional or three-dimensional map.

5. The method according to claim 1, wherein a rotor and/or an ectopic action potential is identified based on the plurality of action potentials determined according to steps a) through d).

6. The method according to claim 1, wherein the sum and the position of a plurality of action potentials in the heart are determined with steps a) through d), each in a first time period and in a second time period, the second time period being different from the first time period, and in that the change in the sum and/or position of the plurality of action potentials of the second time period is determined relative to the first time period.

7. The method according to claim 6, wherein when there is a change in the sum of an action potential by more than a prespecified threshold between the first time period and the second time period, there is a corresponding acoustic and/or visual and/or tactile indication.

8. A computer program product for determining a plurality of action potentials in the heart with program code means for executing a computer program following its implementation in a data processing device, characterized in that the program code means are provided for executing the method according to claim 1 following implementation in the data processing device.

9. A device for determining a plurality of action potentials in the heart, comprising a receiving device for receiving a data set from a surface ECG signal that was recorded synchronously with a plurality of channels, preferably with 32 or 64 channels, and data from at least one IEGM signal of the associated heart recorded during the same time period, and, a data processing device that is designed to process the data set of the surface ECG signal by means of ICA analysis and to determine the sum and position of a plurality of action potentials in the heart based on the ICA analysis, and to compare the data from the at least one IEGM signal to the plurality of action potentials and to correct the sum and/or position of at least one action potential of the plurality of action potentials in the heart based on this comparison.

10. The device according to claim 9, wherein the data processing device is designed for performing the comparison by means of correlation calculation.

11. The device according to claim 9, wherein the device furthermore has a display device that is designed to represent the sum and position of the determined plurality of action potentials preferably by means of a two-dimensional or three-dimensional model of the heart in a two-dimensional or three-dimensional map.

12. The device according to claim 9, wherein the data processing device is designed to identify automatically a rotor and/or an ectopic action potential based on the determined plurality of action potentials.

13. The device according to claim 9, wherein the data processing device is designed to determine the sum and position of a plurality of action potentials in the heart, both in a first time period and in a second time period, the second time period being different from the first time period, and to determine the change in the sum and/or position in the plurality of action potentials in the second time period relative to those in the first time period.

14. The device according to claim 13, wherein the data processing device is designed to produce an indication signal that outputs an acoustic and/or visual and/or tactile indication on a display device when there is a change in the sum of an action potential between the first time period and the second time period by more than a predetermined threshold.

15. A system comprising a device according to claim 9 and a recording device for a surface ECG signal synchronously with a plurality of channels, preferably with 32 or 64 channels, and/or a recording device for at least one IEGM signal, device and recording device for a surface ECG signal and/or the recording device for at least one IEGM signal being connected such that the recording device for a surface ECG signal transmits the determined surface ECG signal to the device and the recording device for at least one IEGM signal transmits the at least one determined IEGM signal to the device.

Description

DESCRIPTION OF EMBODIMENTS

[0052] The present invention is explained in the following using exemplary embodiments and referencing the figures. All described and/or graphically depicted features, alone or in any combination, form the subject matter of the present invention, regardless of their inclusion in the claims and regardless of references back to them.

[0053] FIG. 1 illustrates the arrangement of the electrodes for the recording device on the body of the patient;

[0054] FIG. 2 is an enlarged schematic representation of an 8 electrode;

[0055] FIG. 3 illustrates one exemplary embodiment of a method; and

[0056] FIG. 4 is a schematic arrangement of the system for measuring ablation success.

DETAILED DESCRIPTION

[0057] The system comprises a data processing device (for example, a processor of a computer), a catheter having an electrode or a plurality of electrodes at the distal catheter tip, and a device for taking a surface ECG. The surface ECG is detected in a unipolar manner against a reference electrode by means of special electrodes via a plurality of channels (see step 31 in FIG. 3). One example for the arrangement of 8 electrodes 11 and reference electrodes 12 on the body of the patient 13 is illustrated in FIG. 1. The reference electrodes for surface ECG and for unipolar IEGM are attached, e.g. frontally on the legs (as shown in FIG. 1). In one preferred embodiment, 8 patch electrodes are used, each having 8 individual electrodes, so that overall the ECG is measured via 64 channels. The channels for surface ECG and IEGM channels are sampled synchronously, e.g. with 24 bit resolution.

[0058] FIG. 2 is an enlarged illustration of the 8 electrode 11 from FIG. 1. Individual electrodes 21 that are arranged on a surface 20 may be seen, the electrodes being connected to the ECG measurement system via lead 22. The 8 electrode is preferably a patch electrode for recording ECGs that is adhesively applied to the patient's chest. A smaller or greater number of electrodes is also possible. The electrodes 21 are arranged offset to one another so that the largest possible surface area 20 is provided with electrodes. In this way, an electrical map of the surface potentials, with high spatial resolution, may be generated in the ECG measurement. However, other arrangements of the electrodes 21 are also suitable provided they are arranged such that via them cardiac signals can be recorded in a suitable manner.

[0059] The surface ECG data set thus found is then forwarded to the data processing device and processed there by means of ICA analysis (see step 32 in FIG. 3). ICA algorithms such as infomax, fastICA, Molgedy-Schuster ICA, or JADE are used for this, for example (see also A. Hyvrinen, J. Karhunen, and E. Oja, Independent Component Analysis, John Wiley & Sons, Inc., 2001, for a number of fastICA variants and for infomax-based ICA; Jean-Francois Cardoso High-Order Contrasts for Independent Component Analysis, Neural Computation 11, 157-192 (1999) for JADE; Molgedey L, Schuster H. Separation of independent signals using time-delayed correlations, Phys Rev Lett. 1994; 72:3634-3637 for Molgedey-Schuster ICA). The sum and position of a plurality of action potentials in the heart are determined by means of ICA analysis of the data set from the surface ECG signal. The maximum number of action potentials in this exemplary embodiment is 64.

[0060] Preferably at the same time the surface ECGs are taken, an IEGM signal is recorded by means of a catheter previously arranged in the heart, in particular by means of its electrode or electrodes (step 30 in FIG. 3). When a plurality of electrodes are used, the IEGM signal may be a multi-channel signal. Now the IEGM signal is preferably compared, by means of cross correlation, to the plurality of signal components, representing different signal sources, that were determined by the surface ECG and the subsequent ICA analysis (step 33 in FIG. 3). There may then be a correction of the action potentials, in terms of their sum and position, determined by means of the surface ECG (step 34 in FIG. 3.) If there is a temporal offset between the surface ECG signal and the IEGM signal, it may be ignored. A cross-correlation factor is preferably determined during the cross-correlation.

[0061] In order to observe the progress of the treatment during an ablation, the method explained in the foregoing is conducted in a first time period prior to an ablation (e.g. a few seconds to a few minutes prior to an ablation, depending on the cardiac cycle and the repetition period of the sought atypical cardiac signal) and a plurality of action potentials, including sum and position, are determined and, where necessary, corrected based on the IEGM signal. In addition, following the ablation, a second plurality of action potentials, including sum and position, are determined by means of the above method. The plurality of the determined action potentials prior to the ablation is then compared to the plurality of the determined action potentials following the ablation. Following the ablation, if there is still an action potential that corresponds to the ablation site, the lesion created by the ablation very probably did not completely reach the signal path or the ectopic source did not completely reach the depth of the myocardium. If this is the case, the ablation must be continued.

[0062] In addition, using the ICA analysis it is possible to undertake non-invasive reconstruction of the local action potentials of rotor, ectopic regions, sinus nodes, atrial muscle, AF nodes, HIS bundle, bundle branches, and ventricular muscle. In doing so the regular cardiac signals are recognized by registration algorithms. A data base having regular cardiac signals is required for this. The components may provide information about potential pathological changes in cardiac activity. Such an analysis may also take place without the use of a catheter (e.g., without being combined with an IEGM signal).

[0063] FIG. 4 depicts a schematic arrangement 40 of the essential components of the system for measuring the ablation outcome during an ablation in the left ventricle. The surface and intracardiac electrodes on the patient 41, including the reference electrodes, permit measurement of the surface ECG and the IEGM and are connected to multiple unipolar measurement channels 42; data are detected synchronously and signal processing is performed. The detected data are forwarded to data processing device 43, where they are evaluated and assessed by means of ICA and the correlation calculation, the assessment outcome in the context of this disclosure providing information on the outcome of the AF ablation. For this, at least one data set of the surface ECG signal is processed by the data processing unit by means of ICA analysis, the sum and position of a plurality of action potentials in the heart being determined based on the ICA analysis. Moreover, the data of the at least one IEGM signal is compared to a plurality of action potentials. Based on the comparison, the sum and/or position of at least one action potential from the plurality of action potentials in the heart is corrected. The data processing device 43 is connected to a display device 44 on which the assessment result regarding the outcome of the AF ablation may be displayed for a user. Graphic concepts, such as the display of a color scale or percentage scale, are suitable as means for indicating the ablation outcome on the display device 44. In addition, a calculated structure of the chambers of the heart (map) may be depicted on the display, together with the position of the catheter and the indication of ablation outcome at the specific site undergoing ablation.

[0064] It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teachings of the disclosure. The disclosed examples and embodiments may include some or all of the features disclosed herein. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention, which is to be given the full breadth thereof. Additionally, the disclosure of a range of values is a disclosure of every numerical value within that range, including the end points.