WO2024141730A1 - Device for processing spatiotemporal dispersion signals of cardiac electrograms - Google Patents

Abstract

A device for processing spatiotemporal dispersion signals of cardiac electrograms comprises a memory (4) designed to receive spatiotemporal dispersion signals of cardiac electrograms, cardiac cycle length values and voltage histogram uniformity values each associated, on the one hand, with a time marker and, on the other hand, with a cardiac electrogram trace identifier. The device comprises a monitor (6) which detects the presence of a relevant spatiotemporal dispersion signal on a trace and which, in response thereto, calls a computer (8) which calculates a first priority value from the spatiotemporal dispersion signal, a second priority value from the associated cardiac cycle length value or values, and a third priority value from the associated voltage histogram uniformity values and then draws a trace priority value from these three priority values.

Description

Description

Title of the invention: Device for processing spatiotemporal dispersion signals of cardiac electrograms

Technical area

[0001] The invention relates to the field of analysis of signals taken from cardiac electrograms.

Technology background

[0002] The field of treatment of atrial fibrillations has seen significant progress in the last decade. To treat atrial fibrillations, practitioners operate by introducing catheters equipped with a plurality of electrodes. These electrodes are moved within the heart in order to measure the electrical signal which propagates within it. The signals obtained are called cardiac electrograms. These cardiac electrograms are processed to help practitioners detect the area(s) of the heart that are causing atrial fibrillation. Each electrode thus defines a “track” which corresponds to F electrogram obtained from this electrode. Once these areas have been identified, the practitioner burns them in order to make them inactive, which has the effect of restoring the normal functioning of the heart and eliminating atrial fibrillations.

[0003] Most existing solutions are based on the analysis of CFAEs for “Complex Fractionated Atrial Electrograms” (or “Électrograms atriaux fractionés complexes” in French). The principle is to try to find locations of the atria where the electrograms lose their continuity, that is to say, become fragmented.

[0004] The Applicant has developed a treatment of electrograms which has piqued the interest of the scientific community since the publication of very positive clinical studies. These led to the publication of several articles including that of Seitz et al. “AF Ablation Guided by Spatiotemporal Electrogram Dispersion Without Pulmonary Vein Isolation: A Wholly Patient-Tailored Approach”, Journal of the American College of Cardiology, Volume 69, Issue 3, 24 January 2017, pages 303-321.

[0005] This processing is based on the detection of a quantity of cardiac electrogram signals called dispersion by the Applicant. More precisely, the Applicant has discovered that the measurement of the spatiotemporal dispersion of cardiac electrograms, that is to say based both on the temporal evolution of the cardiac electrogram signals from each electrode, but also taking into account cardiac electrogram signals from neighboring electrodes, is particularly effective in determining the areas of the heart which are at the origin of the fi- atrial brilliance. The measurement of this quantity has been the subject of a patent granted in numerous countries, and published in Europe under the number EP 3 236 843.

[0006] By extending its work, the Applicant has integrated dispersion into a machine learning tool, in order to determine in near real time the presence of dispersion within cardiac electrograms during a procedure, which makes it possible to alert the practitioner, accelerate the ablation procedure as well as the quality of the results obtained while reducing operational risks. In addition, the reliability of the procedure is increased and makes it possible to limit the number of patients having to undergo another procedure for the same causes. The patent published under number FR 3 119 537 describes an example of a machine learning tool making it possible to determine in near real time the presence of dispersion within cardiac electrograms during a procedure.

[0007] This work was integrated into software called VX1 which received approval from the FDA ("Food and Drug Administration") and CE marking. The VX1 software, without offering a diagnosis, assists the practitioner in carrying out the diagnosis: based on the dispersion measurements presented in the software, the practitioner can choose to mark areas of the heart to be ablated by catheter.

[0008] In its current version, the VX1 software uses a database of annotated cardiac electrograms to train a machine learning engine which returns a value indicating the chance that an area for which a cardiac electrogram signal has been analyzed or the subject of atrial fibrillation. It is therefore not a measurement of dispersion strictly speaking, nor information constituting a medical diagnosis, but an indication that there is a more or less significant chance that a cardiac electrogram will demonstrate the occurrence of atrial fibrillation. Thus, the value returned by the VX1 software is a value between 0 and 1 (0 indicating that there is almost zero probability that the area being measured participates in fibrillation, and 1 that this probability is a virtual certainty). The software is configured such that a value of 0.5 is used as the threshold at which the practitioner's attention is drawn to the potential presence of dispersion.

[0009] During the development of the VX1 software, the Applicant noted that, in certain cases, many zones of the heart return a value greater than 0.5, which complicates the work of the practitioner, since the latter must proceed at least possible ablations. Furthermore, when too large a number of areas causing dispersion are identified, the practitioner tends to lose confidence in the measurement quality of the software, since it returns highly noisy information. Accordingly, devices and methods that can process dispersion signals spatiotemporal analysis of cardiac electrograms in a way that makes it possible to define a priority of cardiac zones for their treatment by ablation would be useful. Summary

[0010] The devices and methods for processing the spatio-temporal dispersion signals of cardiac electrograms described here can help determine the priority of areas of the heart to be ablated in various ways. For example, the devices and methods may determine priority based on one or more of signal stability, cardiac activation cycle length, and a voltage map. Next, at least one of the identified priority areas may be ablated using a device (e.g., an RF electrode device) to treat a cardiac arrhythmia, e.g., atrial fibrillation.

The spatiotemporal dispersion signal processing devices described here can generally include a monitor, a memory and a calculator. For example, in some variants, the device may include a monitor configured to receive spatiotemporal dispersion signals from one or more cardiac electrograms and identify a relevant dispersion signal, a calculator configured to, in response to the identification of a relevant dispersion signal by the monitor: receiving the relevant dispersion signal, extracting a data set from the received dispersion signal, analyzing the extracted data set, determining a flatness value based on the extracted data set, determining a duration value based on the extracted data set, and calculating a track priority value based on the determined flatness and duration values, and memory configured to store a set of instructions for operation of the monitor and the computer.

[0012] Methods for processing spatiotemporal dispersion signals are also described in this document. With respect to signal stability, the methods may include receiving spatio-temporal dispersion data of cardiac electrograms, extracting a data set from the dispersion data, determining a value of flatness based on the extracted data set, determining a duration value based on the extracted data set, and calculating a track priority value based on the flatness values and of fixed duration. In this way, the priority value of the track can provide information that allows the practitioner to classify cardiac areas for ablation.

[0013] Thus, the invention proposes a device for processing spatiotemporal dispersion signals of cardiac electrograms comprising a memory arranged to receive spatiotemporal dispersion signals of cardiac electrograms associated on the one hand with a time marker and on the other hand to a track identifier of cardiac electrogram, a calculator arranged to receive as input an electrogram track identifier and a time marker, to analyze the spatiotemporal dispersion signal of cardiac electrograms associated with this electrogram track identifier, analyze an extract of signal between the time marker and the first preceding time marker whose spatiotemporal dispersion signal value of cardiac electrograms indicates an absence of dispersion, extract from this signal extract on the one hand a flatness value of the signal, and on the other hand a duration value taken from the duration of the signal extract, and return a track priority value calculated from the flatness value and the duration value, and a monitor arranged to receive the signals spatiotemporal dispersion of cardiac electrograms associated with each cardiac electrogram track, and, when the value of a spatiotemporal dispersion signal of cardiac electrograms indicates a relevant dispersion, to call the calculator with the time marker and the identifier corresponding electrogram track.

[0014] The invention also relates to a device for processing spatiotemporal dispersion signals of cardiac electrograms comprising a memory arranged to receive spatiotemporal dispersion signals of cardiac electrograms, cardiac cycle length values and uniformity values voltage histogram each time associated on the one hand with a time marker and on the other hand with a cardiac electrogram track identifier, a calculator arranged to receive as input an electrogram track identifier and a marker of time, to analyze the spatiotemporal dispersion signal of cardiac electrograms associated with this electrogram track identifier and this time marker, analyze an extract of this signal included between the time marker and the first previous time marker whose spatiotemporal dispersion signal value of cardiac electrograms indicates an absence of dispersion to derive on the one hand a flatness value of the signal, and on the other hand a duration value taken from the duration of the signal extract, and calculate a first priority value calculated from the flatness value and the duration value, the calculator being further arranged to calculate a second priority value from the cardiac cycle length value(s) associated with the electrogram track identifier and time marker received as input, a third priority value from the voltage histogram uniformity value associated with the electrogram track identifier and time marker received as input input and to calculate and return a track priority value for the electrogram track identifier received as input determined from the first priority value, the second priority value and the third priority value, and a monitor arranged to receive the spatiotemporal dispersion signals of cardiac electrograms associated with each cardiac electrogram track, and, when the value of a spatiotemporal dispersion signal of cardiac electrograms indicates a relevant dispersion, to call the calculator with the corresponding time marker and electrogram track identifier.

[0015] In both variants, the device is particularly advantageous because it makes it possible to offer additional information about the dispersion value which makes it possible to indicate to the practitioner a degree of priority of participation in the fibrillation of the zone of the heart at the origin of the returned dispersion value. Thus, the track priority value is information that allows the practitioner to classify cardiac zones for ablation.

[0016] In addition, the track priority value will tend to increase when a practitioner stops in a given area and this is the location of dispersion. Thus, the track priority value allows the practitioner to carry out his gesture more efficiently: when a dispersion is detected, he knows that it is desirable to stop on the area concerned, and to wait to see if the value track priority increases. If this is not the case, he can have confidence that it is desirable to continue his exploration.

[0017] According to various embodiments, the invention may have one or more of the following characteristics:

- the spatiotemporal dispersion signals of cardiac electrograms are sequences of values taken from electrogram signals each indicating a degree of confidence in the fact that dispersion takes place for the electrogram track and the time marker concerned, and in which the monitor and/or the calculator are arranged to determine whether a spatiotemporal dispersion signal of cardiac electrograms indicates a relevant dispersion by comparing the value of the spatiotemporal dispersion signal of cardiac electrograms to a threshold value,

- the calculator is arranged to calculate the flatness value from at least one value among the standard deviation of the signal extract, the total variation of the signal extract, the entropy of the signal extract or a value taken from one or more derivatives of order greater than or equal to one of the signal extract,

- the calculator is arranged to calculate the duration value by comparing the duration of the signal extract to a minimum value and/or to a maximum value, and by returning the value 0 if the duration of the signal extract is less to the minimum value, returning the value 1 if the duration of the signal extract is greater than the maximum value, and returning a value between 0 and 1 otherwise,

- the calculator is arranged to determine the value between 0 and 1 by applying to the duration of the signal extract a function of projection of the interval between the minimum value and the maximum value towards the interval between 0 and 1, which projection function being chosen from the group comprising the affine functions, exponential functions, polynomials and threshold functions,

- the calculator is arranged to calculate the first priority value by producing a weighted harmonic, harmonic, weighted or arithmetic average of the flatness value and the duration value,

- the memory receives cardiac cycle length values which include cardiac activation cycle length values and global cycle length values, and the calculator is arranged to calculate the second priority value by comparing the length value of cardiac activation cycle associated with the electrogram track identifier and the time marker received as input at a threshold and/or by comparing between them the cardiac activation cycle length value and the length value of global cycle associated with the electrogram track identifier and the time marker received as input,

- the memory is arranged to receive voltage histogram uniformity values which are obtained by performing a G test or chi-square test between a uniform histogram and a histogram of the voltage values associated with a track identifier cardiac electrogram and at a period of 6 to 10 seconds including the time marker with which each voltage histogram uniformity value is associated, and the calculator is arranged to calculate the third priority value from the value d 'voltage histogram uniformity associated with the electrogram track identifier and the time marker received as input and a threshold value, and

- the calculator, when the first priority value, the second priority value and the third priority value are Boolean values, is arranged to determine a track priority value according to the following hierarchy:

1) the first priority value, the second priority value and the third priority value are 1

2) the first priority value and the second priority value are 1

3) the first priority value and the third priority value are 1

4) the second priority value and the third priority value are 1

5) the first priority value is 1

6) the second priority value is 1 and

7) the third priority value is 1.

[0018] The invention also relates to a method comprising the following operations: a) receiving spatiotemporal dispersion signals from cardiac electrograms associated on the one hand with a time marker and on the other hand with a cardiac electrogram track, b) determining whether a value of a spatiotemporal dispersion signal of cardiac electrograms indicates dispersion, c) if operation b) is negative, repeat it with a dispersion value presenting a subsequent time marker, d) if operation b) is positive, analyze the spatiotemporal dispersion signal of cardiac electrograms associated with the corresponding electrogram track identifier by analyzing a signal extract between the time marker and the first previous time marker whose spatio-temporal dispersion signal value of cardiac electrograms indicates an absence of dispersion, and by drawing from this signal extract on the one hand a flatness value of the signal, and on the other hand a duration value taken from the duration of the signal extract, and e) return a track priority value calculated from the flatness value and the duration value of the operation d).

[0019] The invention relates to yet another method for determining a track priority value of spatiotemporal dispersion signals of cardiac electrograms comprising the following operations: a) receiving spatiotemporal dispersion signals of cardiac electrograms, values of cardiac cycle length and voltage histogram uniformity values each time associated on the one hand with a time marker and on the other hand with a cardiac electrogram track identifier, b) determining whether a value of a spatiotemporal dispersion signal of cardiac electrograms indicates dispersion, c) if operation b) is negative, repeat it with a dispersion value having a later time marker, d) if operation b) is positive , dl) analyze the spatiotemporal dispersion signal of cardiac electrograms associated with the corresponding electrogram track identifier by analyzing a signal extract between the time marker and the first preceding time marker whose spatiotemporal dispersion signal value of cardiac electrograms indicates an absence of dispersion, and by drawing from this signal extract on the one hand a flatness value of the signal, and on the other hand a duration value taken from the duration of the signal extract, and calculate a first priority value from the flatness value and the duration value, d2) calculate a second priority value from the cardiac cycle length value(s) associated with the electrogram track identifier and to the time marker received as input, d3) calculate a third priority value from the voltage histogram uniformity value associated with the electrogram track identifier and the time marker received as input, and d4) calculate a track priority value for the track identifier electrogram received as input determined from the first priority value, the second priority value and the third priority value e) return the track priority value of operation d).

[0020] According to various variants, the process may have one or more of the following characteristics:

- the spatiotemporal dispersion signals of cardiac electrograms are sequences of values taken from electrogram signals each indicating a degree of confidence in the fact that dispersion takes place for the electrogram track and the time marker concerned, and in which operation b) comprises the comparison of a value of the spatiotemporal dispersion signal of cardiac electrograms to a threshold value,

- operation d) comprises calculating the flatness value from at least one value among the standard deviation of the signal extract, the total variation of the signal extract, the entropy of the 'signal extract or a value taken from one or more derivatives of order greater than or equal to one of the signal extract,

- the operation dl) comprises calculating the duration value by comparing the duration of the signal extract to a minimum value and/or to a maximum value, and by returning the value 0 if the duration of the signal extract is less than the minimum value, returning the value 1 if the duration of the signal extract is greater than the maximum value, and returning a value between 0 and 1 otherwise,

- operation dl) includes determining the value between 0 and 1 by applying to the duration of the signal extract a projection function from the interval between the minimum value and the maximum value towards the interval between 0 and 1, which projection function being chosen from the group comprising affine functions, exponential functions, polynomials and threshold functions, and

- operation e) includes calculating the track priority value by producing a weighted harmonic, harmonic, weighted or arithmetic average of the flatness value and the duration value.

[0021] The invention also relates to a computer program comprising instructions for executing the method according to the invention, a data storage medium on which such a computer program is recorded and a computer system comprising a processor coupled to a memory, the memory having recorded such a computer program.

Brief description of the drawings

Other characteristics and advantages of the invention will appear better on reading the description which follows, taken from examples given by way of illustration and not limitation, taken from the drawings in which: - [Fig.l] represents a block diagram of a device processing spatiotemporal dispersion signals to allow the detection of priority ablation cardiac zones,

- [Fig.2] represents an example of implementation of an operating loop of the device of [Fig.l],

- [Fig.3] represents an example of a dispersion signal processed by the device of [Fig.l], with 10 distinct tracks, and

[0023] - [Fig.4] represents an example of implementation of an interface making it possible to report to a practitioner whether or not a priority track has been detected by the device of [Fig.l].

[0024] The drawings and the description below contain, for the most part, elements of a certain nature. They can therefore not only be used to better understand the present invention, but also contribute to its definition, if necessary.

detailed description

[0025] [Fig.l] represents a schematic example of a device 2 according to the invention. As noted in the introduction, the signals that are used by the device are based on cardiac electrograms measured by pairs of electrodes from a catheter in a patient's heart.

However, in the particular case of the invention, it is not these signals which are processed, but the dispersion measurement which is derived from them. As indicated in the introduction, the article by Seitz et al. “AF Ablation Guided by Spatiotemporal Electrogram Dispersion Without Pulmonary Vein Isolation: A Wholly Patient-Tailored Approach”, Journal of the American College of Cardiology, Volume 69, Issue 3, 24 January 2017, pages 303-321 and the patent published under number EP 3 236 843 allow us to better understand what dispersion is, both in terms of the commonalities and the differences with CFAEs. Generally speaking, spatiotemporal dispersion is defined as a group of electrograms, fractionated or unfractionated, which exhibit inter-electrode temporal and spatial dispersion at the level of at least three adjacent bipoles, such that activation s extends over the entire duration of the atrial fibrillation cycle.

[0027] Taking into account the field considered and the fact that dispersion and CFAEs represent quite distinct phenomena to the extent that CFAEs ignore any spatial aspect, the latter do not present any major interest in the context of the invention. Indeed, as will be seen below, the invention generally aims to qualify the stability of the signal formed by the dispersion values. This same analysis would have little or no meaning in the case of CFAEs.

Device 2 includes a memory 4, a monitor 6 and a computer 8. The devices described here can provide additional information from a spatiotemporal dispersion value (also called “dispersion value”) which can be useful for determining the degree of priority of areas of the heart exhibiting arrhythmic activity, for example example atrial fibrillation, at the origin of a measured dispersion value. In other words, the devices can qualify a measured dispersion value to help a doctor determine whether or not the area where it originated should be ablated. As noted previously, the devices may typically include a monitor, memory, and calculator, and may determine priority based on one or more of signal stability, cardiac cycle length, and histogram uniformity. Of voltage.

The devices described here may or may not be coupled to a cardiac mapping catheter 10. For example, in certain variants, the devices may be separated from a cardiac mapping catheter 10 but communicatively coupled to it. In other variations, the software used in the devices may be integrated into the cardiac mapping system. A screen 12 and a user interface 14 can also be coupled to the device and/or the mapping catheter 10.

[0031] An ablation catheter could also be coupled to the device 2 in order to offer a method of treating cardiac arrhythmia using the device 2 to map the areas to be ablated, and by carrying out the ablation of these areas, by example by means of the ablation catheter.

Memory

Memory 4 is arranged to receive all the data from device 2, whether input or output, of a global or local nature. Memory 4 can be any type of data storage suitable for receiving digital data: hard disk, hard disk with flash memory, flash memory in any form, random access memory, magnetic disk, storage distributed locally or in the cloud, etc.

[0033] In the example described here, the memory 4 receives all the data which concerns the device 2, that is to say the programs and software instantiating the monitor 6 and the computer 8, the parameters and possible hyperparameters of the possible neural networks, the weights of any neural networks, the outputs and intermediate data of any neural networks, the spatiotemporal dispersion signal data of cardiac electrograms received as input (if applicable), the flatness values of the signal and duration, cardiac cycle length values, voltage histogram uniformity values, buffered data, and output track priority value data. The data calculated by the device can be stored on any type of memory similar to memory 4, or on it. This data may be deleted after the device 2 has carried out its tasks or retained them.

As will be seen below, the flatness value of the signal and the duration value are two values used to qualify whether the dispersion value signal is associated with a cardiac zone whose ablation has priority. These values are combined to produce a priority value for the stability criterion which indicates whether the dispersion value that is determined is associated with dispersion which has significant potential to be associated with an area which is the source of a atrial fibrillation. Similarly, the cardiac cycle length data and/or the voltage histogram uniformity data may also be used to determine a priority value for respectively the cardiac cycle length criterion and the uniformity criterion d voltage histogram. These priority values can be combined to produce a track priority value when they relate to the same track.

[0035] As in the other patent applications filed by the Applicant, the track priority value does not constitute a medical diagnosis but an indication which allows a doctor to make a decision, as blood pressure would be in another context. .

The monitor 6 and the calculator 8 directly or indirectly access the memory 4. They can be produced in the form of an appropriate computer code executed on one or more processors. By processors, we must understand any processor adapted to the calculations described below. Such a processor can be produced in any known manner, in the form of a microprocessor for a personal computer, laptop, tablet or smartphone, of a dedicated chip of the FPGA or SoC type, of a calculation resource on a grid or in the cloud, a cluster of graphics processors (GPUs in English), a microcontroller, or any other form capable of providing the computing power necessary for the achievement described below. One or more of these elements can also be produced in the form of specialized electronic circuits such as an ASIC. A combination of processor and electronic circuits can also be considered. Processors dedicated to machine learning and the implementation of neural networks could also be considered.

Monitor

The function of the monitor 6 is to analyze the data stream of spatiotemporal dispersion signals of cardiac electrograms received as input, and to detect the fact that a dispersion value indicates that treatment is necessary. In a particular implementation, for example when VX1 software is used, a dispersion value greater than or equal to 0.5 is significant. Of course, the detection of this value will depend on the values taken by the dispersion signal received as input. By for example, this could be generated in the opposite way to the VX1 software (for example 1 - Value from VX1), in which case, it would rather be a value less than or equal to 0.5 which would be significant. This determination could also be made differently, based on a value taken from the derivative of the dispersion value signal, or in any other relevant way.

[0038] Due to the continuous nature of the processing by the device 2 which will appear better lower down, once a dispersion value has been detected by the monitor 6, the detection for the following values (but concerning the same track although sure) may be different or simplified. Thus, in the case described above, rather than comparing the current dispersion value to a threshold, the monitor 6 could for example measure the derivative of the input dispersion value signal and consider that a detection is positive if the derivative is positive, etc. Generally speaking, monitor 6 could rely on several tests in order to qualify the detection of a relevant dispersion value.

The role of monitor 6 is therefore of an “interruptive” nature. Indeed, in the absence of a relevant dispersion value, it is useless to calculate a track priority value, since dispersion is not detected. On the other hand, as soon as a relevant dispersion value is detected, monitor 6 calls computer 8 to calculate the track priority value. Thus, the operation of device 2 could appear as a loop of detections by monitor 6 for each track, with the execution of calculator 8 each time a relevant dispersion value is detected. Of course other implementations could be considered.

Calculator

The role of the calculator 8 is to calculate the track priority value for a track whose dispersion value has been considered relevant by the monitor 6. As a reminder, the dispersion signal is a signal which associates a dispersion marker time to a dispersion value. This dispersion value is itself taken from an analysis of several cardiac electrogram signal values. The dispersion values are updated approximately every 300ms, based on extracts of cardiac electrogram signals lasting approximately 1.5s. Alternatively, this update can take place every 100ms, every 500ms or other.

As will be seen below, the determination of a track priority value is based on an extract of dispersion values which can have a continuous duration of 1.5s, or approximately 5 dispersion values, up to several tens of seconds, or around a hundred dispersion values.

[0042] More precisely, at each operating loop, the computer 8 analyzes a signal extract of dispersion values which ends with a dispersion value which has just been determined by the monitor 6 as relevant, and which contains exclusively sive dispersion values whose time markers are successive, associated with the same track, and which have been considered relevant.

[0043] It will appear that this extract can be obtained in numerous ways:

- the monitor 6 can generate extracts during its operation, by adding a current dispersion value detected as relevant to a current extract if the immediately preceding dispersion value has also been detected as relevant, or create a new extract in the case opposite,

- the calculator 8, upon receipt of a dispersion value associated with a given time marker, can analyze a buffer of past dispersion values, and stop at the oldest value considered relevant by the monitor 6, or Again,

- the calculator 8 can recover a buffer of past dispersion values from the time marker associated with a dispersion value received as input, and properly determine an extract from this buffer which it considers relevant.

Signal stability

The Applicant's work has demonstrated that the temporal continuity of relevant dispersion values is all the more useful as the dispersion value signal is precise. Indeed, with a dispersion considered “noisy”, one could be tempted to ignore an irrelevant dispersion value to have more data allowing the calculation of the track priority value. The Applicant's work has demonstrated that the combination of the signal flatness value and the duration value makes it possible to avoid artificially enlarging the size of the extracts and to obtain better results.

The calculator 8 operates by carrying out two measurements on the extract defined above, a measurement of the flatness value of the signal, and a measurement of the duration value. In both cases, the aim is to determine whether the dispersion value presents a form of stability over time. Indeed, the Applicant's work revealed that the signals of stable dispersion values were associated with priority zones in terms of ablation with a view to suppressing atrial fibrillation.

[0046] In the example described here, the flatness value of the signal is taken from the standard deviation of the extract data. During the Applicant's work, the standard deviation is the measurement which offered the best results. However, the Applicant has determined and tested other types of measures which can also be used, such as variance, the total variation of the extract, the entropy of the extract, a value taken from one or more derivatives of order greater than or equal to one of the extract, the range, the interquartile range or another similar measure.

[0047] In parallel, the calculator 8 also determines a duration value which makes it possible to indicate the extent to which the current extract is long in relation to a time interval which is considered to indicate that the cardiac zone associated with this dispersion is a priority in terms of ablation. In the example described here, the calculator 8 projects the duration of the extract onto a standard interval comprised between a minimum duration and a maximum duration. These two values, estimated empirically by the Applicant, indicate respectively the minimum duration that an extract must have to designate a priority cardiac zone, and the maximum duration taking into account the fact that the practitioner cannot afford to stay too long on each area if he wants to carry out his procedure within reasonable time limits and minimize the surgical risk.

[0048] In the example described here, the calculator 8 determines the duration of the extract and projects its value onto the interval [minimum duration; maximum duration] in order to determine a value between 0 and 1. The projection can be of any type: linear, polynomial, exponential, threshold, etc. This involves indicating, for a given extract duration, whether this duration is characteristic of a priority cardiac zone or not.

[0049] The minimum duration has an obvious usefulness as a floor value. The maximum duration has an important operational utility: when the first dispersion value of an extract longer than the maximum duration is detected, the output priority value will necessarily be low because the duration value will be low. As the clip grows, the associated priority value and therefore the track priority value will increase with the duration value. When an operator sees that the track priority value is no longer moving, they can determine that it is because the duration value cannot increase any further, and that it is time to move the catheter.

[0050] Alternatively, the calculator 8 could determine the duration value differently, independently of the range [minimum duration; maximum duration]. Still alternatively, the minimum duration and the maximum duration could be variable during the procedure or be personalized for each patient.

[0051] The flatness value of the signal and the duration value can be determined in parallel with each other. Alternatively, one can be calculated before the other.

[0052] The duration value and the flatness value are constructed to be between 0 and 1. This is due to the way in which the calculator 8 determines the priority value from the signal flatness value and the value of duration. Indeed, in the case of signal stability, the computer 8 determines the priority value in the example described by operating a weighted harmonic average. Alternatively, this average can be harmonic, weighted or arithmetic of the flatness value and the duration value.

[0053] In the case where the flatness value of the signal and the duration value are not included in identical value ranges, a relative rectification can be carried out, or another formula can be used to calculate the priority value.

[0054] A Boolean value can also be determined from the priority value, for example by defining that the value is 1 if the weighted harmonic average is greater than 0.5 and 0 otherwise.

Cardiac cycle length

[0055] The local cycle length (or “LCL”) or cardiac activation cycle length is the time interval between successive activations of electrical signals at a specific location during cardiac mapping procedures. The overall cycle length (or “GCL”) is calculated from the coronary sinus and corresponds to the time interval between two successive cardiac cycles. It represents the average duration of complete atrial activity.

Several ways are known to determine the LCL. The Applicant has also proposed an invention in application FR 2206690 to optimally estimate this quantity.

The Applicant's work has revealed that an LCL of less than 100 ms and/or an LCL of 20% less than the GCL is characteristic of a cardiac region of interest.

The priority value for the cardiac cycle length criterion can be determined in two ways by the calculator 8. According to a first variant, it is a Boolean value (yes/no or 0/1), in which case the priority value is the result of the two tests mentioned above. According to a second variant, it is a value between 0 and 1. In this case, the calculator 8 can calculate the track priority value according to the following formula: if LCL<20%GCL, the value is V = scale constant * (GCL-LCL)/GCL, otherwise V=0. The scaling constant then makes it possible to define a threshold from which the track priority value is considered to indicate a priority area. So, with a constant of 2.5, any priority value greater than 0.5 indicates a priority area. Other formulas may appear to those skilled in the art, such as an inverse exponential for example (exp~ ^(GLC ~ ^LCLY ) or other.

Voltage histogram uniformity

[0059] Retrospective analysis of the regions responsible for atrial fibrillation shows that some of these present a patchy pattern in voltage on the voltage map.

By studying these regions in more detail, the Applicant has discovered that these patterns can be quantified by the uniformity of the voltage histograms of the mapping catheter calculated over a time window. Uniformity is tested statistically using likelihood ratio tests such as the G test or chi-square test. The first test is proportional to the Kullback-Leibler divergence (a dissimilarity metric) between a uniform histogram and the analyzed histogram. The second test calculates the Pearson chi-square, that is to say the sum of the squared differences between a uniform histogram and the histogram analyzed. In practice, the values are very relatives. In a first variant, only the G test is used. In a second variant, only the chi-square test is used. In a third variation, a combination of the G test value and the chi square test is used. In this case, this combination can be chosen from the group comprising the minimum between these values, the maximum between these values, a harmonic, weighted, weighted harmonic or arithmetic average of these values.

[0061] In all cases, it is the voltage histogram uniformity value resulting from one of these variants which is used. The Applicant's work revealed that regions presenting a voltage histogram uniformity value less than 0.05 calculated over 10 seconds are considered responsible for atrial fibrillation. Generally speaking, the threshold can be up to 0.06 or less than 0.05, and the calculation time can be between 6 and 15 seconds.

The priority value for the voltage histogram uniformity criterion can be determined in two ways by the calculator 8.

[0063] According to a first variant, it is a Boolean value (yes/no or 0/1), in which case the priority value is the result of the test mentioned above (value 1 if uniformity value voltage histogram less than 0.05 and value 0 otherwise).

ce qui garantit que toute valeur d’uniformité d’histogramme de tension inférieure à 0,05 induira une valeur de priorité supérieure à 0,5. [0064] According to a second variant, it is a value between 0 and 1. In this case, the calculator 8 can calculate the priority value according to an inverse exponential, for example the constant being for example chosen equal to 0 .05/ln(2),

which guarantees that any voltage histogram uniformity value less than 0.05 will induce a priority value greater than 0.5.

Calculation of track priority value

When several criteria are used, the calculator 8 can determine a track priority value which depends on the priority value calculated for each criterion.

[0066] In the case where the priority values are Boolean, a track priority value is determined based on the Boolean value of each criterion. The Applicant's work revealed the following hierarchy of track priorities:

1) 3 criteria to 1

2) signal stability criterion and cardiac activation cycle length at 1

3) signal stability criterion and voltage map at 1

4) criterion length of cardiac activation cycle and voltage map at 1

5) signal stability criterion at 1

6) cardiac activation cycle length criterion at 1, and

7) voltage map criterion at 1.

[0067] In the case where the priority values are between 0 and 1, the computer 8 must combine the priority values into a single track priority value. A One possible approach is to use a weighted average, where the weights reflect the relative importance of the three criteria. Weightings should be determined based on the importance of each criterion in the overall prioritization process. For example, 0.5 x priority value (signal stability) + 0.33 x priority value (cardiac activation cycle length) + 0.17 x priority value (voltage map).

[0068] Besides the use of a weighted average, there are other approaches for combining priority values:

- Maximum score: Select the maximum value among the individual criteria as the overall score for prioritization

- Decision tree: Use a decision tree (for example, a set of if/else conditions) to determine priority based on the scores of the different criteria. The value of each criterion can be used as a branching condition to navigate the decision tree and arrive at the final track priority value.

Process

An example of an operating loop of device 2 will now be described.

In an operation 200, monitor 6 is called with the current dispersion value for a given track. When the monitor 6 determines that a dispersion value is relevant, an operation 210 is triggered in which the extract is determined from the time marker of the dispersion value of the operation 200, the associated track identifier , as well as dispersion value signals already received for this track identifier. Once the extract has been determined, the calculator 8 can determine the flatness value and the duration value to derive the track priority value in an operation 220, and return this in an operation 230.

[0070] In an alternative embodiment, operation 220 also includes the calculation of the LCL and GCL value, and/or the voltage histogram uniformity value. In another embodiment, the LCL value and the GCL value and/or the voltage histogram uniformity value are continuously calculated during operation 200, and operation 220 accesses these values based on the moment determined as relevant by operation 200.

[0071] It therefore appears that the track priority value can be linked to two criteria in addition to the stability of the signal: the length of the cardiac cycle and the uniformity of the voltage histogram. When these additional criteria are used, operation 220 is arranged to return a priority value for each criterion, that is to say a signal stability priority value, a cardiac cycle length priority value and a voltage histogram uniformity priority value.

[0072] As described above in the “Calculation of the track priority value” section, the operation 230 can return, depending on the variants, the most important priority value, or a value combining the three track priority values, for example a harmonic, weighted, weighted harmonic or arithmetic average of these values. Still as a variant, the track priority value returned by operation 230 can also be binary information, of the “relevant track” or “irrelevant track” type, or the same information indicating a degree of importance.

[0073] Based on the track priority value feedback and other clinical elements, a practitioner can then decide on a map of areas to ablate in the heart, and treat the heart with an ablation catheter to ablate these areas.

[0074] [Fig.3] represents an example of spatiotemporal dispersion signals received in the context of a 10-track device. [Fig.4] represents an image displayed on the user interface 14 allowing the calculated track priority value to be returned to the practitioner. As can be seen in this figure, electrodes 7-8 and 13-14 are subject to priority track detection which is indicated by an electric spark symbol, while electrodes 1-2 have done so. subject to relevant dispersion detection, but without this leading to priority track detection.

[0075] It appears that, where appropriate, the device 2 will determine a track priority value for each track for which a dispersion value signal is received as input. This makes it possible to enrich the information transmitted to the practitioner to allow him to carry out the diagnosis determining whether an area associated with a given track must be the subject of an ablation or not.

Claims

Claims [Claim 1] Device for processing spatiotemporal dispersion signals of cardiac electrograms comprising a memory (4) arranged to receive spatiotemporal dispersion signals of cardiac electrograms, cardiac cycle length values and uniformity values of voltage histogram each time associated on the one hand with a time marker and on the other hand with a cardiac electrogram track identifier, a calculator (8) arranged to receive as input an electrogram track identifier and a time marker, to analyze the spatiotemporal dispersion signal of cardiac electrograms associated with this electrogram track identifier and this time marker, analyze an extract of this signal included between the time marker and the first previous time marker of which the spatiotemporal dispersion signal value of cardiac electrograms indicates an absence of dispersion to derive on the one hand a flatness value of the signal, and on the other hand a duration value taken from the duration of the signal extract, and calculate a first priority value calculated from the flatness value and the duration value, the calculator (8) being further arranged to calculate a second priority value from the cardiac cycle length value(s) associated with the electrogram track identifier and the time marker received as input, a third priority value from the voltage histogram uniformity value associated with the electrogram track identifier and the marker of times received as input and to calculate and return a track priority value for the electrogram track identifier received as input determined from the first priority value, the second priority value and the third value of priority, and a monitor (6) arranged to receive the spatio-temporal dispersion signals of cardiac electrograms associated with each cardiac electrogram track, and, when the value of a spatio-temporal dispersion signal of cardiac electrograms indicates dispersion relevant, to call the calculator (8) with the corresponding time marker and electrogram track identifier. [Claim 2] Device according to claim 1, in which the spatiotemporal dispersion signals of cardiac electrograms are sequences of values taken from electrogram signals each indicating a degree of confidence in the fact that dispersion takes place for the electrogram track and time marker concerned, and in which the monitor (6) and/or the calculator (8) are arranged to determine whether a spatiotemporal dispersion signal d cardiac electrograms indicates relevant dispersion by comparing the value of the spatiotemporal dispersion signal of cardiac electrograms to a threshold value. [Claim 3] Device according to claim 1 or 2, in which the calculator (8) is arranged to calculate the flatness value from at least one value among F standard deviation of the signal extract, of the variation total of the signal extract, the entropy of the signal extract or a value taken from one or more derivatives of order greater than or equal to one of the signal extract. [Claim 4] Device according to one of the preceding claims, in which the calculator (8) is arranged to calculate the duration value by comparing the duration of the signal extract to a minimum value and/or to a maximum value, and returning the value 0 if the duration of the signal extract is less than the minimum value, returning the value 1 if the duration of the signal extract is greater than the maximum value, and returning a value between 0 and 1 otherwise. [Claim 5] Device according to claim 4, in which the calculator (8) is arranged to determine the value between 0 and 1 by applying to the duration of the signal extract a projection function of the interval between the minimum value and the maximum value towards the interval between 0 and 1, which projection function being chosen from the group comprising affine functions, exponential functions, polynomials and threshold functions. [Claim 6] Device according to one of the preceding claims, in which the calculator (8) is arranged to calculate the first priority value by producing a weighted harmonic, harmonic, weighted or arithmetic average of the flatness value and the value of duration. [Claim 7] Device according to one of the preceding claims, in which the memory (4) receives cardiac cycle length values which include cardiac activation cycle length values and global cycle length values, and the calculator is arranged to calculate the second priority value by comparing the cardiac activation cycle length value associated with the electrogram track identifier and the time marker received as input to a threshold and/or or by comparing with each other the cardiac activation cycle length value and the overall cycle length value associated with the electrogram track identifier and the time marker received as input. [Claim 8] Device according to one of the preceding claims, in which the memory (4) is arranged to receive voltage histogram uniformity values which are obtained by carrying out a G test type test or chi square test between a uniform histogram and a histogram of voltage values associated with a cardiac electrogram track identifier and a period of 6 to 10 seconds including the time marker with which each voltage histogram uniformity value is associated, and the calculator (8) is arranged to calculate the third priority value from the voltage histogram uniformity values associated with the electrogram track identifier and the time marker received as input and a value threshold. [Claim 9] Device according to one of the preceding claims, in which the calculator (8), when the first priority value, the second priority value and the third priority value are Boolean values, to determine a priority value track according to the following hierarchy: 1) the first priority value, the second priority value and the third priority value are 1 2) the first priority value and the second priority value are 1 3) the first priority value and the third priority value are at 1 4) the second priority value and the third priority value are 1 5) the first priority value is 1 6) the second priority value is 1 and 7) the third priority value is 1. [Claim 10] Method for determining a track priority value of cardiac electrogram spatiotemporal dispersion signals comprising the following operations: a) receiving cardiac electrogram spatiotemporal dispersion signals, cardiac cycle length values and voltage histogram uniformity values each time associated on the one hand with a time marker and on the other hand with a cardiac electrogram track identifier, b) determining whether a value of a spatiotemporal dispersion signal of cardiac electrograms indicates dispersion, c) if operation b) is negative, repeating it with a dispersion value having a subsequent time marker, d) if operation b) is positive, dl) analyze the spatiotemporal dispersion signal of cardiac electrograms associated with the corresponding electrogram track identifier by analyzing a signal extract between the time marker and the first previous time marker whose spatiotemporal dispersion signal value of cardiac electrograms indicates an absence of dispersion, and drawing from this signal extract on the one hand a flatness value of the signal, and on the other hand a duration value taken from the duration of the signal extract, and calculate a first priority value from the flatness value and the duration value, d2) calculate a second priority value from the value(s) of cardiac cycle length associated with the electrogram track identifier and the time marker received as input, d3) calculating a third priority value from the voltage histogram uniformity value associated with the identifier electrogram track identifier and time marker received as input, and d4) calculate a track priority value for the electrogram track identifier received as input determined from the first priority value, the second value priority and the third priority value e) return the track priority value of operation d). [Claim 11] The method of claim 10, wherein the spatiotemporal dispersion signals of cardiac electrograms are sequences of values taken from electrogram signals each indicating a degree of confidence that dispersion is occurring for the track electrogram and the time marker concerned, and in which operation b) comprises the comparison of a value of the spatiotemporal dispersion signal of cardiac electrograms to a threshold value. [Claim 12] Method according to claim 10 or 11, in which the operation dl) comprises calculating the flatness value from at least one value among the standard deviation of the signal extract, of the total variation of the signal extract, the entropy of the signal extract or a value taken from a or several derivatives of order greater than or equal to one of the signal extract. [Claim 13] Method according to one of claims 10 to 12, in which the operation dl) comprises calculating the duration value by comparing the duration of the signal extract to a minimum value and/or to a maximum value, and returning the value 0 if the duration of the signal extract is less than the minimum value, returning the value 1 if the duration of the signal extract is greater than the maximum value, and returning a value between 0 and 1 otherwise. [Claim 14] Computer program comprising instructions for executing the method according to one of claims 10 to 13 when executed by computer. [Claim 15] Data storage medium on which the computer program according to claim 14 is recorded.