Method and electronic device for identification and reversion of an out-of-control biological signal

Abstract

The present disclosure relates to a method determining a waveform form reversion of an out-of-control biological signal, the method comprising, - acquiring a at least one measurement that is indicative of an action potential activity of the organ; - determining whether the at least one measurement is indicative of an erratic biological signal; - in reaction to the at least one measurement being indicative of an erratic biological signal, determining a waveform for an electric stimulation of the organ, wherein the waveform is indicative of a pacing frequency and a pacing voltage amplitude over time, and wherein determining the waveform comprises determining a starting pacing frequency and decreasing the pacing frequency over time.

Description

[0001] METHOD AND ELECTRONIC DEVICE FOR IDENTIFICATION AND REVERSION OF AN OUT-OF-CONTROL BIOLOGICAL SIGNAL

[0002] The present disclosure refers to a method for identifying an out-of-control biological system and / or determining a waveform form reversion of the out-of-control biological signal. Most organs and anatomical systems in, for example, the human body, are controlled by means of electrical impulses of nerves. These impulses are known as biological signals, also called neurological signals and operate some organs in an alternating and / or rhythmic fashion. The beating of the heart, the respiratory motion of the respiration system, and the peristaltic motions of the esophagus and of the colon, are examples of alternating and / or rhythmic operation of organs.

[0003] Some anatomical systems operate independently using an internal electrical pattern generation and electrical conduction system to control an organ. In some cases, periodic events occur in an anatomical system during which the biological signals go awry (out of control) and are sent out in excessively high, incoherent and / or irregular frequency patterns. These high and irregular frequency patterns generally result in a failure of the respective organ or at least lie outside the healthy functioning of said organ. A well-known example of an out-of-control biological signal is a cardiac dysrhythmia (also referred to as arrhythmia), such as fibrillation of the heart, which reduces the blood pumping efficacy of the heart to nil and which, when untreated, often result in death due to heart failure.

[0004] Electronic devices, such as an implantable cardioverter defibrillator, ICD, are configured to detect an abnormality in the heart rate of a patient and to deliver a defibrillation shock in response to the detection of said abnormality. Although often lifesaving, the delivery of said defibrillation shock has several negative effects on the patient, such as psychological morbidity, a reduced quality of life, an experience of pain during and after the delivery of said shock, and a reduction in physical and / or mental wellbeing. The severity of these negative effects further increases when multiple numbers of defibrillation shocks are delivered to a patient. Furthermore, defibrillation shocks also result in a reduction of the longevity of the ICD, which may result in the need for another expensive and invasive operation to replace the ICD.

[0005] It is a goal of the present disclosure, next to other goals, to provide a method, a system, and an electronic device for determining a waveform for electronic stimulation of an organ that obviates or at least reduces the abovementioned negative effects.

[0006] To that end, the present disclosure provides a computer implemented method for determining a waveform for an electric stimulation for restoring an erratic biological signal of an organ of a patient, wherein the method comprises:

[0007] - acquiring at least one measurement that is indicative of an action potential activity over time of the organ; - determining whether the at least one measurement is indicative of an erratic biological signal;

[0008] - in reaction to the at least one measurement being indicative of an erratic biological signal, determining a waveform for an electric stimulation of the organ, wherein the waveform is indicative of a pacing frequency and a pacing voltage amplitude over time, and wherein determining the waveform comprises determining a starting pacing frequency and decreasing the pacing frequency over time.

[0009] An advantage of the method according to the present disclosure is that by starting at the determined starting pacing frequency, the change of capture is increased. It is noted that a capture refers to a synchronized depolarization of the organ in response to an electric stimulation.

[0010] An additional advantage of the method according to the present disclosure is that the determined waveform is suitable for bringing the respective organ to a range of operations where the organ can be self-sustaining and / or function within an acceptable range customary for the boundary conditions of this organ.

[0011] In an example, the method comprises repeatedly decreasing the pacing frequency will be (e.g. lowered) over time to a fraction of an original measured frequency pattern in the at least one measurement, preferably until a stable action potential activity is established for that patient for that moment in the pathology of that patient applicable life-style conditions. For example, when the at least one measurement is indicative of a cardiac dysrhythmia, such as a ventricular fibrillation (e.g. an irregular heart rhythm), the haemodynamic situation of the patient may become unstable as the heart is no longer capable of pumping blood trough the body of the patient, the waveform is determined by over time repeatedly decreasing the pacing frequency until a stable haemodynamic situation is established (e.g. until the blood flow in the circulatory system of the patient is restored).

[0012] It will be clear that an erratic biological signal refers to an activity pattern associated with the organ, wherein the activity pattern may be considered abnormal, irregular, debilitating, indicative of a pathological condition and / or otherwise indicative of deviating from healthy operation conditions associated with the organ. For example, an activity pattern associated with the brain may be indicative of a debilitating epileptic seizure (also referred to as seizure) of the brain and may thus considered an erratic biological signal. It will further be clear that a normal biological signal refers to an activity pattern associated with the organ, wherein the activity pattern may be considered to be a healthy, normal, sustainable, and / or at least in a range of operations that is not considered life threatening.

[0013] It will be clear that the action potential activity is measured over time and that measurements may be represented as time-series. It will also be clear that action potential activity may refer to action potential as a result of cellular polarization and / or depolarization of muscle cells. It will further be clear that measurements may be taken in a perpetuity and / or continuously fashion, that earlier measurements may precede the at least one measurement, and / or that future measurements may follow the at least one measurement. It will also be clear that consecutive measurements may be obtained via a sliding window approach and / or may partially overlap, or that consecutive measurements may be distinct. It will further be clear that measurement may have a predetermined length (time window) and / or predetermined overlap. In an example, at least a part of the determined waveform may be used for continuously pacing of the patient (e.g. (permanent or temporary) transcutaneous or transvenous pacing). For example, when it is determined that the at least one measurement is not indicative of an erratic biological signal, the waveform may be determined such that it is indicative for one or more pulses for an electric stimulation for temporary or permanent pacing, such as, transvenous pacing transcutaneous pacing, epicardial pacing, direct contact pacing and other suitable pacing methods. It will be clear that the pacing frequency may also be referred to as a pacing rate. It will also be clear that a measurement may refer to one or more measurement obtained from a single sensor or may refer to one or more measurements that are obtained from multiple sensors and / or that are constructed from a combination of measurements from multiple sensors. It will further be clear that a pacing frequency may refer to a single frequency or to a combination of frequencies and / or a frequency spectrum. The waveform may be generated using one or more frequencies. It will be understood that the waveform provides one or more characteristics for electric stimulation pulses, wherein the characteristics may comprise one or more of: a number of pulses, a pulse frequency, a pacing voltage amplitude, a pulse duration, a pulse cycle length, a pulse shape, an application time of the pulses. It will be understood that, depending on the pulse shape, a corresponding voltage may not be constant during a pulse. For example, while when the waveform is similar to a square wave, a corresponding voltage of a pulse may be considered constant, while when the waveform has a sinusoidal form, a sawtooth form, or a more complex form, the voltage is not constant, in case of a varying voltage, the pacing voltage amplitude may refer to a peak voltage.

[0014] It will be understood that the waveform may be indicative of a voltage amplitude modulation frequency spectrum and / or a frequency modulated pattern indicative of pulse patterns for electric stimulation. It will be understood that the step of determining the waveform may comprise updating at least a part of the waveform, adding a new part to the waveform, and / or removing a part of the waveform. It will be understood that the step of determining the waveform may be a continuous and / or a perpetuate process, wherein the waveform is constantly determined and / or updated to match current conditions. It is noted that the pacing voltage amplitude and the pacing frequency partly determine a pacing energy expressed in Joule. I.e. the pacing energy is a cumulative function of the energy in Joule associated with the electric stimulation that corresponds to the waveform. It is further noted that the electric stimulation may have a constant or variable current (amperage). It will be understood that the current associated with the electric stimulation depends on the voltage (amplitude) of the electric stimulation and a total resistance. It will be understood that the total resistance may depends on various factors, such as, a resistance in a system used to deliver the electric stimulation, a resistance in one or more leads used to deliver the electric stimulation, a resistance in one or more electrodes used to deliver the electric stimulation, a resistance of in one or more leads used to deliver the electric stimulation, a resistance of the body of the patient, a distance between pacing leads etc. Some of said factors may have a variable resistance. For example, when an electric stimulation pulse is delivered to a patient corresponding to a pulse in the waveform with a pacing voltage amplitude (VpuiSe) and a duration of (tpuise), the total resistance (Rtotai) during the electric stimulation may be expressed as a sum of resistance of tissue of the organ to which said pulse is applied (Rtissue), resistance of one or more electrodes used (Reiectrode), resistance of one or more wiring used a contact efficacy between said one or more electrodes and said tissue and additional related factors (Rmisc). Thus, the total resistance may be expressed as follows.

[0015] ^total Rtissue T Reiectrode T Rwiring T Rtransition T Rmisc

[0016] Given the total resistance Rtotai, a current (Ipuise) of the electric stimulation pulse may be expressed as follows:

[0017] . _ pulse

[0018] Ipuise total

[0019] The pacing energy of said pulse (Epuise) in Joule, may be expressed as follows.

[0020] V2,

[0021] Fpulse = i Ipuise -’ V "pulse ■’ t '-pulse = npulse.’ t ipuise

[0022] E total

[0023] It is noted that the above formula of the pacing energy assumes that the voltage of the pulse is constant over the duration of the pulse and most therefore considered an approximation in cases the voltage varies over time. In such situations, an average pacing energy may be determined, which would require integration over the duration of the pulse. It will be clear that the pacing energy corresponding to the waveform is a function of the pacing frequency of the pulses and the pacing frequency (assuming a constant pacing voltage amplitude between the pulses).

[0024] In an embodiment, determining whether the at least one measurement is indicative of an erratic biological signal comprises determining a frequency pattern corresponding to the at least one measurement and determining that the frequency pattern is at least partly associated with a nonfunctional working of the organ and / or body of the organ. In a further embodiment, determining that the frequency pattern associated with a nonfunctional working of the organ and / or body of the organ comprises determining one or more frequency components of the frequency pattern and determining that at least frequency component is above a predetermined critical frequency. In an additional or alternative embodiment, determining whether the at least one measurement is indicative of an erratic biological signal comprises comparing the at least one measurement with a set of reference signals, wherein each of the reference signals has a known association with either a normal biological signal or an erratic biological signal, wherein the comparing comprises comparing one or more pulse characteristics of pulses in the at least one measurement with pulses of the set of reference signals, wherein the characteristics comprise one or more of: a pulse shape, a pulse voltage amplitude, a repetition rate of the pulse. In a further example, the set of reference signals (templates) are adjusted in dependence on one or more historic measurements from the patient, for example one or more historic measurements that correspond to action potential activity that is considered to be normal for the patient and / or one or more historic measurements that correspond to action potential activity that is considered abnormal (e.g. erratic) for the patient.

[0025] In an example, determining whether the at least one measurement is indicative of an erratic biological signal may comprise inputting the at least one measurement to a machine learning model trained to produce an output that is indicative of whether the at least one measurement is indicative of an erratic biological signal. In a further example, the machine learning model is configured to be updated and / or adjusted based on one or more patient specific data elements, such as health information and / or historic measurements.

[0026] In an example, the action potential activity corresponds to a depolarization rate of a muscle of organ, for example the heart or brain tissue. In a further example, determining that the at least one measurement is indicative of an erratic biological signal comprises determining that the depolarization rate of the organ muscle exceeds a predetermined critical depolarization rate threshold. In a further example, the predetermined critical depolarization rate threshold will be a function of several factors relating to characteristics of a patient, including but not limited to: one or more congenital predisposition (i.e. genetic risk-factors), an age, one or more physical health information elements (respective other diseases; viral infections etc.), a treatment database, a gender, one or more known mental and / or physical constraints and limitations, a known exercise routines, a known sporting background, a known chemical abuse history, one or more historic pacing information, one or more historic capture success information, a mammal species type

[0027] In an embodiment, the at least one measurement comprises an action potential signal of a heart. For example, the at least one measurement may be an electrocardiogram, ECG, measurement of the heart.

[0028] In an embodiment, determining the waveform further comprises adjusting the pacing voltage amplitude in dependency of at least the pacing frequency in order to not exceed a predetermined maximum pacing energy.

[0029] An advantage of this is that potential damage to the organ and / or pain experienced by the patient that may occur due to electric stimulation is prevented or at least reduced. In an embodiment determining the starting pacing frequency comprises determining a repetition rate in the frequency pattern, and wherein the starting pacing frequency is in a predetermined range from the repetition rate. In an example, the repetition rate is indicative of a polarization rate and / or a depolarization rate. In an example, the predetermined range is between 90% and 110% of the repetition rate, preferably between 90% and 100% of the repetition rate, more preferably between 95% and 99% of the repetition rate.

[0030] An advantage of this embodiment is that by having the starting pacing frequency to be in a predetermined range from the repetition rate, the changes of a successful capture are increased, while the pacing voltage amplitude may be kept relatively low such that tissue of the organ is not or at least less damaged by electric stimulation.

[0031] In an embodiment determining whether the at least one measurement is indicative of an erratic biological signal and / or determining the repetition rate comprises applying one or more compression functions, one or more transformation functions and / or one or more filter functions. The one or more compression functions, the one or more transformation and / or the one or more filter functions may comprise: a compressive sensing function, a wavelet transform, a discrete wavelet transform, a Butterworth filter, a discrete path transform, a Fourier transform, a fast Fourier transform, a shortterm Fourier transform, a Laplace transform, a matched filter (also known as matching filter), a compressed matched filter, a correlation filter, and / or a full matched filter.

[0032] In a further or alternative embodiment, determining the repetition rate comprises identifying a plurality of peaks in the at least one measurement, wherein the repetition rate is a function of a count of the identified peaks and a duration of the at least one measurement. For example, when the repetition rate is a heart rate, the repetition rate may be determined by detecting a plurality of R peaks in the at least one measurement, wherein the heart rate is a function of a respective duration between sequential R peaks.

[0033] In an embodiment, the method further comprises applying one or more pre-processing steps to the at least one measurement prior to performing the step of determining whether the at least one measurement is indicative of an erratic biological signal. In a further embodiment, the one-or more pre-processing steps comprise reducing a noise component from the at least one measurement. For example, the at least one measurement may include a noise component that has been introduced due to a transition resistance between a skin surface and one or more electrodes that are attached to the skin surface to acquire the at least one measurement, wherein the pre-processing step comprises reducing the noise component. For example, when the at least one measurement comprises an ECG measurement of the heart obtained using one or more surface electrodes, a transition resistance between the skin and one or more electrode(s) may introduce a noise component to a QRS complex present in the at least one measurement, such that the QRS complex in the at least one measurement differs from a true QRS complex. Likewise, a noise component may be reduced that has been introduced to a P wave or a T wave comprised in the at least one measurement.

[0034] In an embodiment, applying one or more pre-processing steps comprises measuring a respiration motion, determining an electrical interference caused by the respiration motion and filtering out the electrical interference from the at least one measurement.

[0035] In an embodiment, applying the matched filter may comprise analysing the at least one measurement by applying the matched filter forwards in time, by applying the matched filter backwards in time (e.g. backwards matched filter also known as reverse matched filter), or by applying the matched filter both forwards and backwards in time.

[0036] An advantage of applying a matched filter is that the repetition rate may be obtained in a computational cost effective manner. Another advantage is that a relatively short measurement is needed to accurately determine whether the measurement is indicative for an erratic biological signal which means erratic signals are quicker detected.

[0037] Another advantage of applying a matched filter is that it does not rely on a baseline reference while most other alternative peak-detection algorithms do, which means less preprocessing is needed before the matched filter is applied compared to conventional methods.

[0038] In an embodiment, applying the matched filter comprises correlating the at least one measurements with one or more templates, wherein the one or more templates may be indicative of one or more of: an action potential event associated with the organ, a depolarization event associated with the organ, a repolarisation event associated with the organ, a pulse associated with the organ, an action potential event associated with a healthy functioning of the organ, an action potential event associated with non-healthy functioning of the organ, a cardiac pattern. It is noted that the one or more templates may be predetermined.

[0039] In an example, correlating the at least one measurement with one or more templates may be implemented by performing a convolution operation for each of the one or more templates and the at least one measurement, wherein an output of each convolution operation provides a function of a correlation between the measurement and the corresponding template and wherein the correlation being above a certain threshold at a certain point indicates that template is present in the measurement at that point.

[0040] For example, determining a heart rate may be determined by detecting a plurality of R peaks in the at least one measurement by applying the matched filter using a template indicative of an expected R peak, wherein all local maxima of an output of the matched filter above a certain correlation threshold indicate a presence of an R peak, and wherein the heart rate is a function of a respective duration between sequential maxima above a predetermined threshold.

[0041] It will be understood that applying the matched filter forwards in time may comprise correlating the one or more templates with the at least one measurement. It will be further understood that applying the matched filter backwards in time may comprise correlating a time-reversed version of the one or more templates with the at least one measurement or correlating the one or more templates with a time-revered version of the at least one measurement.

[0042] The one or more templates may be derived from a database comprising a plurality of baseline signals that are associated with a certain functioning of the respective organ. Preferably, each of the plurality of baseline signals are obtained from mammal from which the at least one measurement is also obtained. In other words, it is preferred that when the at least one measurement is obtained from a certain person, the one or more templates are derived from a database comprising a plurality of historic measurements from said person, wherein the plurality of historic measurements have been obtained during a period of healthy functioning of the organ. In one example, the method may further comprise, in reaction to the at least one measurement not being indicative of an erratic biological signal, adding the at least one measurement to the database. Alternatively, or additionally, the database may comprise a plurality of historic measurements from a plurality of other persons. In an example, the one or more templates may be derived by computing an average from the plurality of baseline signals in the database. In other words, the database may comprise a broad data set from a cohort of healthy mammals (e.g. people) which are, preferably, within the same boundary conditions (e.g. age, relative health, gender, genetic background), as the mammal under investigation (e.g. the person from which the at least one measurement is obtained). Preferably, the one or more templates are adapted in accordance with one or more boundary conditions. An advantage is that the more matches in boundary conditions correspond, the better a determined template to be used in the matched filter represents the characteristics of a healthy functioning of the organ of the person from which the at least one measurement is obtained.

[0043] In an example, the one or more templates are obtained by applying a Convolutional Neural Networks processing (CNN) to obtain one or more templates.

[0044] In an example, the at least one measurement comprises an electrocardiogram that is indicative of an electrical activity of a heart of a person and each of the one or more templates is representative of a section or all of a full PQRST wave (i.e. the full PQRST wave comprises a P wave representing atria depolarization, a QRS complex representing ventricles depolarization and a T wave representing ventricles repolarization), and determining whether the at least one measurement is indicative of an erratic biological signal comprises determining that a deviation between the at least one measurement and the one or more templates exceeds a predetermined threshold. (E.g., that a correlation between the at least one measurement and the one or more templates representative of a section or all of a full PQRST wave is below a predetermined threshold.

[0045] It may be further noted that the one or more template may be adjusted in dependence on one or more patients characteristics, including but not limited to: one or more congenital predisposition (i.e. genetic risk-factors), an age, one or more physical health information elements (respective other diseases; viral infections etc.), a treatment database, a gender, one or more known mental and / or physical constraints and limitations, a known exercise routines, a known sporting background, a known chemical abuse history, one or more historic measurements, one or more historic pacing information, one or more historic capture success information, a mammal species type.

[0046] In an example, the method may further comprise, in reaction to the at least one measurement not being indicative of an erratic biological signal, adjusting the one or more templates in accordance with the at least one measurement.

[0047] In an example, when a plurality of templates is used and / or when a forwards and backwards matched filter is used, a plurality of distinct matched filters may be applied in parallel using digital twins (e.g. using digital replica) for each of the one or more measurements, wherein a distinct matched filter comprises a distinct combination of the one or more templates and / or a forwards or backwards matched filters.

[0048] In an example, determining whether the at least one measurement is indicative of an erratic biological signal, comprises converting the at least one measurement (signal) to at least one set of individual components in a compressed domain and correlating the at least one set of individual components with at least one template represented in the compressed domain, wherein the at least one template is known to be indicative for an erratic biological signal (e.g., a signal indicating a pathological condition) or a non-erratic biological signal (e.g. a signal indicating a healthy functioning). In an example, determining whether the at least one measurement is indicative of an erratic biological signal, comprises converting the at least one signal to at least one set of individual components in a compressed domain and identifying a plurality of peaks in the at least one measurement by correlating the at least one set of individual components with at least one template represented in the compressed domain using a matched filter (also known as matching filter), wherein preferably the at least one template is indicative of an ventricular depolarization. In a further example, no (further) preprocessing steps are applied to the at least one measurement.In an example, the method may further comprise adjusting the at least one template used in the matching filter may be adjusted based on one or more previous measurements, wherein the at one or more previous measurements comprise one or more depolarization events, for example, between 1 - 10 (or more) depolarisation events, for example 2 or 5 depolarization events, and wherein adjusting the at least one template comprises obtaining at least one predetermined template and adjusting a shape of the at least one template when said shape deviates from a shape of the one and more depolarization events and wherein adjusting the shape of the at least one template comprises adjusting the shape of the at least one template towards the shape of the one or more depolarization events. In an example, updating a template comprises increasing or decreasing a relative voltage of at least one of the plurality of points. It will be clear that the steps of acquiring the at least one measurement and determining whether the at least one measurement is indicative of an erratic biological signal may also be performed independently from the steps of determining the waveform for electrical stimulation (pacing).

[0049] In an embodiment, determining the waveform comprises changing the pacing voltage amplitude in reaction to a change in the pacing frequency to maintain a target pacing energy.

[0050] An advantage is that a target pacing energy is maintained when the frequency is changed, this ensures that conditions for capture are still met after the change in frequency, improving the changes of successful capture.

[0051] In an embodiment, decreasing the pacing frequency over time comprises decreasing the pacing frequency towards a target pacing frequency.

[0052] An advantage of this embodiment is that the waveform is indicative of pulses for electric stimulation that are highly likely to continuously achieve capture while bringing the erratic biological signal towards a frequency pattern that is closer to an activity pattern associated with normal operation of the organ.

[0053] In a further embodiment, the method including decreasing the target frequency to a new target frequency in reaction to the pacing frequency meeting the target frequency and wherein determining the waveform comprises decreasing the pacing frequency towards the new target frequency. This process may be repeated until the target frequency is at a physiologically compatible pacing frequency, or even until the target frequency is at a baseline depolarization frequency (e.g. a “normal” depolarization frequency of the organ, such as a resting heart rate). The physiologically compatible pacing frequency refers to the highest level of pacing frequency at which the organ of the patient can operate under acceptable conditions. For example, a physiologically compatible pacing frequency of a heart may be a pacing frequency at which the heart constitutes a haemodynamic sustainable compressing flow condition. In an example, the decreasing of the pacing frequency induced by, for example continuous and / or incremental decreasing of the pacing frequency, may be starting out at a measured maximum fibrillation depolarization rate (e.g. the repetition rate) and may be lowered to a target pacing frequency that represents a “waiting level” (e.g. a temporary resting rate, an intermediate pacing frequency that may be at least temporally maintained and allows for progression to a next lower target pacing frequency and that is associated with a stable “waiting” depolarization rate of the organ), before progressing to a next lower stable pacing frequency (e.g. depolarization rate) that may be a predetermined fraction of the earlier pacing frequency (e.g. half of the earlier pacing frequency). Subsequently the following waiting level of stable fixed pacing frequency will again be at a predetermined fraction the frequency of the previous pacing frequency. This process in reduction is incrementally repeated until the highest level of pacing frequency rate is achieved at which the organ of the patient can operate under acceptable physiological conditions and the risk of organfailure is eliminated, or until the pacing frequency rate is achieved that is at or near a baseline depolarization frequency of the organ. E.g. the pacing frequency is decreased until the heart is at an acceptable haemodynamic condition where the heart and vascular system can pump and transport blood at a safe and efficient rate at that moment in the life of the patient or the pacing the pacing frequency is decreased until the heart is at or near its resting heart rate. It will be clear that other predetermined fractions (e.g. percentages) as the described halving of the pacing frequency may be used. The target pacing frequency at which acceptable haemodynamic conditions are achieved may also be referred to as a haemodynamic pacing frequency. It will be clear that the physiologically compatible pacing frequency and / or the baseline depolarization frequency may differ between patients and that the physiologically compatible pacing frequency and / or the baseline depolarization frequency are a function of one or more patient’s pathological conditions and / or one or more life-style history indicators and / or may differ between different types of mammals. For example, for some patients the haemodynamic pacing frequency for pacing of their heart may be as high as 240 beats per minute, or as low as 100 beats per minute, or somewhere in between. Levels above 240 beats per minute may even be acceptable to achieve stable haemodynamic conditions for some patients, for example, for a young and energetic patient. In another example, the resting heartbeat (i.e., the baseline depolarization frequency of the heart) of a patient may be at 60 beats per minute (e.g. 1 HZ), while some people may have an even lower baseline depolarization frequency.

[0054] In another example, an older patient suffering from cardiovascular related problems for an extended period of time may have a stable haemodynamic heartbeat (and corresponding target pacing frequency) that is lower than 100 beats per minute (e.g., 1.67 hertz, e.g. 100 cycles or repetitions per minute). When it is detected that the heartbeat of the patient is above the stable haemodynamic heartbeat, the patient will be paced at a continuous and gradually reducing pacing frequency in order to bring the patient’s heartrate down to a “relaxed” rate which is near, at or below the stable haemodynamic heartbeat, such that the patient can safely and effectively perform all normal functions without any discomforts.

[0055] Alternatively, the step-down process may follow a pattern of discrete steps, for example, centennial steps, decreasing the pacing frequency in steps of 1.5 hertz (e.g. approximately 100 electric stimulation per minute) and associated accomplished resting stable depolarization rate at 100 pulses per minute below the last highest depolarization rate. In another example, the step-down process incrementally lowers the pacing frequency by, when the patient’s health allows this, can be a reduction in pacing rate from the highest measured fibrillation rate to one-third of this fibrillation rate, followed by another step-down process which may be one-half of the last stable secondary depolarization rate or one-third of the last stable secondary depolarization rate; or one-fourth of the last stable secondary depolarization rate, or any other incremental step-wise reductions that are measured as being acceptable and received in good and efficient capture for the respective patient. The highest level of defibrillation pacing may be in the range of 300 - 700 pulses per minute (e.g. a range of 5.00 - 11.67 Hz), and may thus for example be as high as 400 or 600 pulses per minute or any random level in between or above or below this range.

[0056] In an embodiment, the target pacing frequency is set to and / or incrementally lowered towards a predetermined frequency range that is associated with a functional operating of the organ.

[0057] In an embodiment, the at least one measurement is obtained over a predetermined timeinterval. In an embodiment, the method further comprises acquiring one or more succeeding measurements. In a further embodiment, the at least one measurement and the one and more succeeding measurements may partially overlap. E.g. the measurements partly span the same period in time. In an alternative further embodiment, the at least one measurement and the one and more succeeding measurements are distinct. In an example, the at least one measurement and the one and more succeeding distinct measurements may continuously span a time period. In another example, the at least one measurement and the one and more succeeding distinct measurements may not continuously span a time period, e.g. gaps exist between one or more measurements during which no measurements have been taken. Preferably, the gaps are of a predetermined size (time).

[0058] In an embodiment, the pacing frequency over time comprises decreasing the pacing frequency incrementally in one or more discrete steps.

[0059] An advantage of this embodiment is that the pacing frequency may be lowered relatively quickly towards the target frequency, meaning that if capture is achieved, the erratic signal may be restored to a normal signal more quickly.

[0060] In a further embodiment, the one or more discrete steps have a predetermined step size. The step size may be a fixed step size, for example, 1.67 hertz (e.g. 100 pulses per minute) or may be a determined based on a percentage of a current pacing frequency. In example, the percentage and / or the fixed step size are predetermined in dependence on one or more patients characteristics, including but not limited to: one or more congenital predisposition (i.e. genetic risk-factors), an age, one or more physical health information elements (respective other diseases; viral infections etc.), a treatment database, a gender, one or more known mental and / or physical constraints and limitations, a known exercise routines, a known sporting background, a known chemical abuse history, one or more historic pacing information, one or more historic capture success information, a mammal species type.

[0061] In an embodiment, decreasing the pacing frequency over time comprises gradually decreasing the pacing frequency from the starting pacing frequency to the target pacing frequency over a predetermined time period. In a further embodiment, the pacing frequency is gradually decreased in a continuous fashion or in a partial continuous fashion, wherein preferably the partial continuous fashion comprises alternating a period in which the pacing frequency is gradually decreased with a period in which the pacing frequency is not decreased.

[0062] In an embodiment, decreasing the pacing frequency over time comprises decreasing the pacing frequency at a linear or a nonlinear rate.

[0063] In an embodiment, the method further comprising acquiring one or more succeeding measurement after the organ is stimulated with an electric pulse that corresponds to at least a part of the waveform and determining whether capture is achieved by the electric pulse.

[0064] In an embodiment, decreasing the pacing frequency comprises decreasing the pacing frequency in reaction to the determination that capture is achieved by the electric pulse.

[0065] In an embodiment, the method further comprises determining an effectiveness of the electric stimulation to the organ with the electric pulse that correspond to at least a part of the waveform by determining a change in a frequency pattern corresponding to one of the one or more succeeding measurement.

[0066] In an embodiment, the method further comprises applying an electric stimulation to the organ that corresponds to at least a part of the waveform.

[0067] In an embodiment, a target pacing energy is determined in dependence on one or more patients characteristic, such as, but not limited to: one or more congenital predisposition (i.e. genetic riskfactors), an age, one or more physical health information elements (respective other diseases; viral infections etc.), a treatment database, a gender, one or more known mental and / or physical constraints and limitations, a known exercise routines, a known sporting background, a known chemical abuse history, one or more historic pacing information, one or more historic capture success information, a mammal species type.

[0068] An advantage of this is that the target pacing energy may be personalized to the patient in dependence on one or more characteristics. It will be understood that the one or more characteristics of the patient may be represented in a numerical and / or a categorical manner. For example, physical health information may be represented by a health score and / or a health category.

[0069] In an embodiment, the patient is a mammal and is preferably one of the following mammal types: a Primate, a Human, an Equidae, an Equus, a Canine, a Bovine, a Rodent, a Feline, a Peccary.

[0070] In an embodiment, determining the waveform comprises using a predetermined pacing voltage amplitude as starting pacing voltage amplitude, wherein preferably the starting pacing voltage amplitude is in the range of 20.0V to 30.0V.

[0071] An advantage of using a starting pacing voltage amplitude in the range of 20.0V - 30.0V, is that pain and / or damage to tissue of the organ are reduced relative to existing pacing methods.

[0072] In a further embodiment, determining the waveform further comprises decreasing the voltage amplitude in reaction to the determination that capture is achieved by the electric pulse and / or increasing the voltage amplitude in reaction to the determination that capture is not achieved by the electric pulse. In an example, the pacing voltage amplitude may be first set to be at a predetermined starting voltage amplitude in a range of 20.0V (Volts) to 30.0V and may be reduced to be in the range of 1.0V to 5.0V, preferably in the range of 1.0 to 2.0V, in reaction to the determination that capture is achieved. In a further embodiment, the pacing voltage amplitude is decreased before the pacing frequency is decreased.

[0073] In an even further or alternative further embodiment, the pacing voltage amplitude is reduced from the starting pacing voltage amplitude of 20.0V to 30.0V to a pacing voltage amplitude in the range of 1.0V to 2.0V, wherein preferably the pacing voltage amplitude is reduced to an amplitude in a range of 1 to 5 pulses from the first pulse and / or wherein preferably the pacing voltage amplitude is reduced within 0.1 to 5 seconds from the first pulse, more preferably in 1 or 2 pulses from the first pulse (e.g. only the first one or two pulses of the waveform have an amplitude of 20.0V to 30.0V, while the remaining pulses of the waveform have an amplitude of 5.0V or lower.

[0074] An advantage of the above embodiments is that the pacing energy is drastically reduced by drastically lowering the pacing voltage amplitude as early as possible. For example, under normal operating conditions of good electrical contact between the tissue of the organ in question and the electrode(s) of a device used to apply the electric stimulation, the current applied may be as low as 20 pA. Assuming a starting voltage amplitude of 20V and a pulse duration of 25 milliseconds, the average energy per pulse will be:

[0075] EPuise = 20F • 20 X 10“6A • 25 X 10“3S = 0.0001 /

[0076] In comparison, a conventional ICD delivers between 200J and 65J for the first defibrillation shock per guidelines of the American Heart Association, depending on the design and intended treatment modality.

[0077] The present disclosure further relates to a system for determining an electric stimulation pattern for restoring an erratic biological signal, wherein the system comprises a pacing module configured to execute the method according to the present disclosure.

[0078] The system has the same advantages and / or effects as the method according to the present disclosure.

[0079] The present disclosure further relates to an electronic device comprising a power module, one or more electrodes configured to measure a biological signal corresponding to an organ, a processing unit operatively connected to the one or more electrodes and the power module, wherein the processing unit comprises a pacing module configured to acquire measurements from the one or more electrodes and wherein the pacing module is configured to determine a waveform according to any one of the methods according to the present disclosure.

[0080] The electronic device has the same advantages and / or effects as described in relation to any method according to the present disclosure. In an embodiment, the electric device further comprises a stimulation module configured to apply an electric stimulation to the organ, wherein the electric stimulation comprises a pulse pattern that is at least partly determined in dependence on at least a part of the waveform. In an example, the stimulation module and / or the detection module is configured to determine the pulse pattern in dependence on at least a part of the waveform. In an example, the stimulation module is comprised in the processing unit. In an example, the power module is configured to supply energy (i.e. electricity) for the electric stimulation. In an example, the power module comprises a power source, such as a battery, and / or may comprise a power connection to connect to an outside power source such as a standard wall socket, a power adapter and / or a USB adapter. They battery may be any suitable battery, such as a rechargeable battery or a non- rechargeable battery such as a lithiumiodide battery, a lithium-silver-oxovanadium (SVO) battery, a lithium vanadium silver pentoxide battery, and / or a lithium-manganese-dioxide (MDX) battery. A rechargeable battery may be connected to a non-contact inductive charging module configured to receive power via induction and further configured to recharge the rechargeable battery. The battery may have one or more battery cells. Additionally, or alternatively, the battery may also comprise one or more of: a bio-battery, a bio-fuel-cell, a self-sustaining bio-electric chemical power supply. It is noted that the power source may comprise multiple batteries of the same kind or multiple batteries of different kind, for example, the power source may have a lithium-iodide battery configured to power different components of the device and a lithium vanadium silver pentoxide battery configured to deliver energy for electric stimulation to the patient. In an example, the power module comprises one or more capacitors that are configured to supply energy for the electric stimulation. Preferably, the power module is configured to receive an indication from the detection module and / or the stimulation module that an electric stimulation is to be applied and to further charge at least one of the one or more capacitors in reaction to receiving said indication. In an example, the power module is configured to supply the electrical energy at a current (amperage) that does not exceed a maximum current, wherein preferably the maximum current is 20mA.

[0081] In an embodiment, the stimulation module is configured to apply the electric stimulation using the one or more electrodes. In an example, the electrodes are configured to allow the flow of energy in both directions, both from the organ and to the organ. An advantage of this is that this allows for continuous monitoring of the efficiency of electric stimulation, while electric stimulations are applied.

[0082] In an embodiment, the electric device further comprises one or more pacing wires configured to directly contact tissue of the organ, wherein the stimulation module is further configured to apply the electric stimulation using the one or more pacing wires, and optionally, to further apply the electric stimulation using the one or more electrodes. An advantage of this is that the stimulation can be applied more effectively by pacing wires that directly contact tissue of the organ, which means that a lower voltage amplitude may be used, resulting in less (or even no) pain experienced by the patient and / or less damage to the tissue of the organ. Another advantage is that electric stimulation can be applied to areas of the organ that are more receptable for electric stimulation relative to areas of the body where the electrodes are placed. In an example, the electronic device comprises a plurality of electrodes and / or pacing wires that are configured to be positioned in a plurality of locations on or in proximity of the organ. An advantage of this is that a relatively larger area of tissue of the organ may be captured by having a plurality of locations to which the electric stimulation is applied.

[0083] In an embodiment, the electronic device comprises one or more reference electrodes.

[0084] In an embodiment, the electronic device is configured to be implantable. An advantage of this is that electric stimulation can be applied directly to tissue of the organ and / or to tissue relatively close to the organ, without the need of making a permanent incision in the skin of the user to lead the electrodes and / or pacing wires in the body of the patient, while the electronic device is positioned outside the body.

[0085] In a further or alternative example, the one or more of electrodes and / or one or more pacing wires are configured to be positioned on one or more locations on or near the organ, wherein the locations may depend on accessibility, electronic receptiveness, anatomical pathology, and other electrophysiological and anatomical conditions with respect to an organ.

[0086] In an embodiment, the one or more electrodes and / or the one or more pacing wires are configured to be positioned on or near at least one of the following locations: the His bundle of the heart, the Left Bundle Branch of the heart, the cardiac Purkinje fibers of the heart and / or any other position on or near the heart that is suitable for measuring the depolarization rhythm of the heart and / or any other position on or near the heart that is suitable for applying the electric stimulation to the heart.

[0087] In an embodiment, the device further comprises a stimulation module configured to apply an electric stimulation to the organ wherein preferably the electric stimulation corresponds to at least a part of the at least one waveform.

[0088] An advantage of this embodiment is that the device is capable of determining a waveform and applying an electric stimulation to an organ in response to the organ having an erratic rhythm, wherein the damage and / or pain experienced by the patient is limited as much as possible.

[0089] In an embodiment, the stimulation module is further configured for defibrillation and / or pacing of the organ and the power module is electronically connected to the stimulation module and configured to deliver power to stimulation module for the electric stimulation.

[0090] In an embodiment, the electronic device is a cardioverter defibrillator, preferably an implantable cardioverter defibrillator, and the organ is the heart of the patient. In an example, the action potential activity of the organ is indicative of the beating of the heart. In an example, determining whether a frequency pattern corresponding to the at least one measurement is indicative of an erratic biological signal may comprise determining that a pattern in the at least one measurement is indicative of an arrhythmia.

[0091] An advantage of this embodiment is that the device may apply potential lifesaving electric stimulations to the heart, while limiting damage to the heart tissue and / or pain experienced by the patient. In an example, the electronic device is an implantable subcutaneous cardioverter defibrillator.

[0092] In an embodiment, the electronic device is a cardiac pacing device, wherein the cardiac pacing device is configured to deliver one or more pacing pulses (e.g. pulses for (permanent or temporary) transcutaneous pacing or transvenous pacing) when it is determined that the frequency pattern is not indicative of an erratic biological signal. It will be understood that the cardiac pacing device may have all components of a standard pacing device.

[0093] An advantage of this embodiment is that the cardiac pacing device has a dual functionality, being able to provide cardiac pacing during normal operation of the organ as well as being able to deliver (lifesaving) electric stimulation in case an erratic biological signal is detected.

[0094] In an example, the device is configured to provide electric stimulation and / or pacing to at least one of: the His bundle of the heart, the Left Bundle Branch of the heart, the cardiac Purkinje fibers of the heart.

[0095] In an embodiment, the processing unit comprises one or more programmable chips, preferably an ASIC or FPGA programmable chip and / or any other suitable digital or analog mathematical processing unit. In an example, the processing unit may comprise one or more of: an integrated circuit, a central processing unit with or without internal memory with input / output capabilities, a stand-alone operational microprocessor, preferably a high level microprocessor.

[0096] In a further embodiment, the electronic device comprises a plurality of programmable chips or one or more multicore processors or multiple microprocessor units, wherein each core or chip is configured to apply a distinct matched filter to a digital twin of the at least one measurement in parallel to the other chips or cores. It will be clear that the electronic device may further comprise other programmable chips and / or other processing units. In other words, the device may comprise a plurality of microprocessor units that are configured to, when a plurality of templates is used and / or when a forwards and backwards matched filter is used, apply the plurality of distinct matched filters in parallel to each other using digital twins (e.g. using digital replica) for each of the one or more measurements, wherein a distinct matched filter comprises a distinct combination of the one or more templates and / or a forwards or backwards matched filters.

[0097] The detection device has either full microprocessor capabilities, including one or more intel processors or equivalent. Alternatively, the signal processing and diagnostic device is operating with an FPGA or ASIC unit and the programming software is specifically designed to accommodate the signal processing capabilities of the commercially available data acquisition device in use. In other embodiments the signal acquisition and data processing device use a combination of microprocessors and FPGA and / or ASIC processing units in parallel or in series to maximize the computational efficiency and provide calculated diagnostic results in microseconds or less.

[0098] The present disclosure further relates to a computer program comprising instructions which, when executed by a computer, carry out the method according to the present disclosure.

[0099] In a further embodiment the instructions are programmed on one or more ASIC or FPGA programmable chips, for example using a compatible programming language such as machine language, assembly language, C, C++, Rust, ADA, Java, Matlab, Python, or any other language.

[0100] The present disclosure further relates to a computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method according to the present disclosure.

[0101] The present disclosure further relates to a computer implemented method for evaluating a cardiac rhythm of a heart, the method comprising: acquiring at least one measurement that is indicative of electrical activity of the heart over time; acquiring one or more templates, wherein each template is indicative of a predetermined cardiac pattern; determining, for each of the one or more templates, a correlation between the at least one measurement and the template; and determining, for each of the one or more templates, whether the correlation is above or below a predetermined threshold associated with the template.

[0102] An advantage of the method is that it makes it possible to identify whether a certain type of pattern associated is present in the measurement, as the correlation is indicative of whether said cardiac pattern is present in the at least one measurement. This is important, as certain patterns in a cardiac cycle are indicative of onset pathological conditions that may lead to the development of serious health issues like Ventricular Fibrillation. The method in accordance with the present invention makes it possible to determine whether predetermined cardiac patterns are present in the measurement, therewith enabling early identification and early preclusive detection, therewith making the planning and execution of life -recovering protocols possible.

[0103] It will be clear that any one of the embodiments, examples and variants disclosed in the present disclosure in relation to acquiring the at least one measurement and / or determining whether the at least one measurement is indicative of an erratic biological signal, are also applicable to the method for evaluating the cardiac rhythm. Likewise, will it further be clear that the method for evaluating a cardiac rhythm may be included in the method for determining a waveform for an electric stimulation for restoring an erratic biological signal, wherein the step of determining whether the at least one measurement is indicative of an erratic biological signal comprises the method for evaluating a cardiac rhythm of a heart.

[0104] In an embodiment, at least one of the templates is indicative of a healthy pattern associated with a healthy type of cardiac cycle. In an example, the template indicative of a healthy pattern comprises at least a part of an expected QRS complex or a PQRST wave. In a further embodiment, the method comprises generating an output indicative of whether a healthy type of cardiac cycle is present in the at least one measurement. In a preferred embodiment, the method comprises, identifying whether the at least one measurement comprises a fragment of at least a predetermined length of time in which the healthy pattern is not present, and in response, determining that the at least one measurement is a suspected signal. In a further embodiment, the method comprises generating an output marking the at least one measurement as a suspected signal, wherein the output preferably comprises the identified fragment.

[0105] In an embodiment, at least one of the one or more templates is indicative of a pathological cardiac pattern associated with a pathological condition and the method comprises determining whether the correlation between the at least one measurement and the at least one template indicative of the pathological cardiac pattern is below a predetermined threshold. For example, a template may represent a pathological pattern that occurs when a pathological condition is present. E.g. cardiac pattern that is associated with a cardiac cycle that shows an onset pattern indicating that the heart of a patient is developing Ventricular Fibrillation.

[0106] In a further embodiment, the method comprises generating an output marking the at least one measurement as being indicative of an onset pathological condition in reaction to the correlation between the at least one measurement and the at least one template indicative of the pathological cardiac pattern being below the predetermined threshold, wherein the output preferably comprises a section of the at least one measurement in which the pathological cardiac pattern and / or the pathological condition associated with the template.

[0107] An advantage of this embodiment is that it makes it possible to perform single or multiple pulse analysis of any ECG signal to analyze the changes in an electronic signal emitted by a depolarization of a cardiac muscle that is indicative of the cardiac muscle not performing in a life sustaining and regular manner that, under normal conditions, would results in a regular repetition of cardiac contraction resulting in high efficiency blood perfusion of the mammalian body.

[0108] For example, a depolarization waveform slope in a cardiac cycle under onset ventricular fibrillation has a much smaller amplitude and much broader time -base with respect to a standard healthy QRS, or respectively R-wave only pattern and the one or more template may include a template indicative for said depolarization waveform slope. Depending on the detection mechanism- of action the slope of the R-wave ranges from whereas the onset Ventricular Fibrillation (VF) and predisposition to Ventricular fibrillation will display a broadening of the R-wave, in addition to a decreasing of the amplitude resulting in a statistically significant decreasing slope of the depolarization signal, with under full-fledged pathological “leaky cell” highly likely a full absence of a recognizable R-wave depolarization. Other pathological depolarization patterns that may be represented by the one or more templates may be primarily located in the frequency domain, or may be represented by respectively multiple sequential absences of a R-wave or missing QRS complex, such as under Sinus-Pause. The maturation of a condition such as Ventricular Fibrillation, or other arrhythmias may be linked to the patient’s personal medical history and personalized behavioral patterns.

[0109] In an embodiment, determining a correlation between at least one pulse in the at least one measurement and at least one of the one or more templates comprises determining a correlation between the one or more templates and the at least one measurement that is shift invariant using a least square minimization to optimize the correlation. In an embodiment, determining a correlation between at least one pulse in the at least one measurement and at least one of the one or more templates comprises applying a filter to the at least one measurement for each of the one or more templates. In a further embodiment, the filter comprises a matched filter or wavelet filter.

[0110] An advantage of applying the template using a filter, such as the matched filter, is that the filter can be used to determine an optimal estimate of a match between the measurement and the template for an unknow time shift f with respect to reference time f0and unknown scaling factor: ?? with respect to a base r)0. This makes it possible to find a match between a generalized template and a specific measurement (e.g. signal), wherein the match is found invariant to time-shifts or scalarshifts.

[0111] In an example, applying the filter comprises calculating a degree of cross-correlation agreement between each of the one or more template and the at least one measurement such that one or more amplitude maxima in the degree of cross-correlation are indicative of a match between the template and the at least one measurement.

[0112] In an example, applying the filter comprises applying one or more compression functions, one or more transformation functions and / or one or more filter functions. The one or more compression functions, the one or more transformation and / or the one or more filter functions may comprise: a compressive sensing function, a wavelet transform, a discrete wavelet transform, a Butterworth filter, a discrete path transform, a Fourier transform, a fast Fourier transform, a short-term Fourier transform, a Laplace transform, a matched filter (also known as matching filter), a compressed matched filter, a correlation filter, and / or a full matched filter. It will be clear that any details, effects, advantages, and variants already disclosed above in relation to the filters are also applicable to various embodiments of the current method.

[0113] In a preferred embodiment, applying the filter comprises applying a matched filter using the one or more templates. An advantage of applying a matched filter is that a small pattern indicative of an onset pathological condition can be identified in the measurement in a computational cost- effective manner.

[0114] Another advantage of applying a matched filter is that it does not rely on a baseline reference while most other alternative peak-detection algorithms do, which means less preprocessing is needed before the matched filter is applied compared to conventional methods.

[0115] In an example, correlating the at least one measurement with one or more templates may be implemented by performing a convolution operation for each of the one or more templates and the at least one measurement, wherein an output of each convolution operation provides a function of a correlation between the measurement and the corresponding template and wherein the correlation being above a certain threshold at a certain point indicates that template is present in the measurement at that point.

[0116] In an example, when a plurality of templates is used and / or when a forwards and backwards matched filter is used, a plurality of distinct matched filters may be applied in parallel using digital twins (e.g. using digital replica) for each of the one or more measurements, wherein a distinct matched filter comprises a distinct combination of the one or more templates and / or a forwards or backwards matched filters.

[0117] In an embodiment the one or more templates comprises at least one template represented in a compressed domain and correlating the at least one measurement with one or more templates comprises converting the at least one measurement to at least one set of individual components in a compressed domain and correlating the at least one set of individual components with each of at least one template represented in the compressed domain. By doing so, an estimation is introduced as correlation between the compressed measurement of a cardiac cellular depolarization and a compressed template (e.g., an average depolarization pattern complex in the compressed domain associated with the pathological signal) to apply the matched filter. This process relies on the so- called impulse response such that an amplitude of the output is a direct indication of the degree of cross-correlation agreement between the template and the measured signal. The amplitude maxima are located where the match is the highest.

[0118] Determining a correlation between the at least one measurement at the one or more templates may comprises applying pulse compressing to the at least one measurement and / or the one or more templates.

[0119] In an embodiment, determining a correlation between the at least one measurement and the one or more templates may comprises adapting a temporal variability of the at least one measurement and determining the correlation between the a plurality of temporal variable measurements and the one or more templates. By doing so, the at least one measurement is “sped up” or “slowed down” using temporal contraction or expansion, which allows to find a temporal variability correlation in the measurement with respect to the template with fixed time-frame. It will be clear that the temporal variation of the at least one measurement may be performed in augmented and expedited manner and may provide a time-saving over changing a time scale of the selected template for the purpose of matching the template against, for example, a deviations in the cardiac (or other organ) electronic data-stream while investigating the change-over in the patient-signal towards a range of pathological conditions that are documented by a plurality of specific depolarization patterns, each represented by specific representative templates. Since the frequency content of the patient’s electronic datastream is subject to a broad range influences, it may be difficult to match the selected analytical template exactly on the same time-scale. In order to account for the temporal variability in the patient data-stream changing the time-scale with respect to the data acquisition in a computational manner will allow for temporal expansion and contraction and will sanction analytical variability to find potential matched with known depolarization pathology profiles in an expedited manner.

[0120] In an embodiment, the method comprises outputting a probability distribution outlining one or more respective matches between the at least one measurement and the one or more templates based on the correlation associated with the one or more templates.

[0121] In an embodiment, each template may be a discrete template comprises a plurality of subsequent points that are indicative of a relative change in voltage over time. E.g. a template comprises a plurality of voltages relative to a reference voltage and that are sequential over time. In an example, each point is provided as a voltage difference relative to a reference point. An advantage is that by doing so, the template is not centered nor defined around a baseline (e.g. around 0 Volt) but describes an expected signal in terms of relative change over time, which allows comparing the template with measurements that have variable offset and drift. In a preferred embodiment, the plurality of points comprises between 3 to 200 points, preferably between 8 to 60 points. In an embodiment, the one or more templates comprise a plurality of templates with various number of points. A template may be ill-defined by a limited number of points (data-points), while still resulting in a sufficient accuracy. The total number of data-points defining a template may be as small as nine (9) points for a complex multiple peak pattern, or less, but preferably no less than three (3) data- points for a single peak. In case a single slope of an ECG pattern (i.e. one side of a peak) is the only aspect under investigation, a number of points defining the template may be a little as two (2). This may be referred to as a “one -plus-some” filter or ill-defined Matched Filter. The actual number of points may relate to a selected complexity of the template (e.g. number of peaks, referencing on- curve data-points instead of against baseline offset, etc.) and may become increasingly more complex on follow-on analysis of the isolated suspected pathological episode in the depolarization pattern. E.g. the method may first be applied to at least one measurement using one or more templates with a first number of peaks to select one or more suspicious fragments from the at least one measurement, after which the method is again applied to the suspected fragments using templates with a second number of peaks higher than the first number of peaks. In each respective iteration of the method, the number of points included in the one or more templates may be increased. The number of points may also be adjusted in accordance with a desired complexity providing a certain confidence level; e.g. 50%, 65%, 80%, 95%, 99% of accuracy, validity, and reliability.

[0122] In other words, once an initial match to one or more templates is established the template will be defined by additional using additional points, increasing the complexity of corresponding selection criteria and subsequent analytics will narrow down the selection of matches with fewer pathological conditions. By repeatedly stepping up the complexity of the definition of the template for clinical evaluation of the root-cause of an identified deviations from a “healthy” depolarization pattern to a probability distribution of potential matches with a few select pathologic conditions may be calculated with increasing accuracy based on an incremental complexity of the available analytical templates of pathological conditions. In case the method is performed by a stand-alone implantable device with treatment options, such as a pacemaker or Implantable Cardioverter Defibrillator (ICD), the method may comprise, in reaction to a determination of the presence of a depolarization pattern(s), instructing the device to an initiate palliative treatment protocol and / or to perform an recommended applicable low-energy no-pain pacing protocol, preferably custom designed for that patient’s lifestyle and medical history.

[0123] In an embodiment, the method further comprises applying one or more pre-processing steps to the at least one measurement prior to performing the step of determining a correlation between the at least one measurement and the one or more templates. In a further embodiment, the one or more pre-processing steps comprise reducing a noise component from the at least one measurement.

[0124] Noise may for example be introduced to the at least one measurement due to transition resistance between the skin and one or more recording (e.g. acquiring) electrodes used to obtain the at least one measurement. For example, when the at least one measurement is an ECG measurement from a heart rate, the noise may cause a deviation from a QRS complex present in the at least one measurement and a true QRS complex in the heart due to transition resistance between the skin and the electrode(s) and the noise may further be present as a distortion of the P wave and T wave in the at least one measurement and may therefore cause deviations when applying a signal definition and / or a respective peak detection to determine a heart-rate (which may be determined based on a plurality of R peaks (each from a different QRS complex) and a respective duration between sequential R peaks). It will be clear that the one or more pre-processing steps may comprise one or more signal processing steps including any mathematics-based signal processing steps. It will further be clear that the one or more pre-processing steps may be hardware implemented and / or software implemented.

[0125] In a further embodiment, the one or more pre-processing steps comprise one or more of: a noise reduction step, an artifact-removal step, a re-sampling step. In a further example, the one or more preprocessing steps are performed in two or more phases, wherein at least a first of the two or more phases is performed on a data acquisition device, such as a stand-alone hear-rate monitor, with which the at least one measurement is obtained, while the other of the two or more phases are performed on a computational device configured to analyze the at least one measurement.

[0126] In a further embodiment, the method further included, digitizing the at least one measurement subsequent to the noise reduction step, and, optionally, applying one or more additional softwarebased noise-reduction techniques to the digitized at least one measurement.

[0127] In an embodiment, the at least one measurement comprises at least one action potential measurement, preferably an electrocardiogram.

[0128] In an example, the at least one action potential measurement (e.g., an electrocardiogram) may be obtained using a data acquisition device configured to monitor cardiac cycles (i.e. a heart rate). The at least one measurement may for example be obtained using a data acquisition comprising one of: an external heart monitor comprising one or more surface electrodes, a wireless heart monitor comprising one or more optical hear rate sensors, an implantable heart monitoring device, such as an implantable loop recorder, a wireless heart monitor, a pacemaker, an implantable cardioverter defibrillator, or another suitable device configured to monitor a heart rate. The measurement may for example comprise a 12-Lead vectoral signal. The data acquisition device may be a stand-alone, implanted or wirelessly routed device.

[0129] In an embodiment, the step of acquiring the at least one measurement comprises acquiring a data-stream, for example a (semi-) live data-stream and the step of determining a correlation comprises, repeatedly determining a correlation between a fragment of the data-stream and the one or more templates and repeatedly determining, for each of the one or more templates, whether the correlation is above or below a predetermined threshold associated with the template, wherein the method further comprises repeatedly generating an output indicative of a match being identified every time a certain correlation exceeds a corresponding predetermined threshold. For example, the method may be applied semi-continuously to subsequent sections of the data-stream over time.

[0130] In a further embodiment, generating the output comprises extracting the identified one or more patterns from the at least one measurement, wherein the output comprises the extracted one or more patterns. An advantage of extracting the identified one or more patterns is that the method may be used to identify and isolate any and all (i.e. most) pathological patterns in parts of the at least one measurement where an anticipated and healthy pattern (e.g. the one or more templates) is temporarily distorted or wherein the at least one measurement has missing identifiable markers in the progression of time. By automatically extracting the identified respective one or more patterns (e.g., applicable pathological depolarization patterns may subsequently be used in a process of planning of prevention of aggravation of the identified clinical concern, as well as planning for treatment and the like. For example, the method may be used to extract a part of the at least one measurement with an apparent absence of a well-defined R-wave depolarization pattern of the cardiac muscle in the at least one measurement.

[0131] In an embodiment, the method further comprises acquiring a data-stream that is indicative of electrical activity of a heart, wherein the method comprises semi-continuously performing the method steps, wherein: the step of acquiring at least one measurement comprises obtaining a subsequent fragment from the data-stream as the at least one measurement; and wherein the step of acquiring one or more templates comprises acquiring one or more first templates that are indicative of a healthy pattern associated with a healthy type of cardiac cycle at a first stage analyzing stage and acquiring one or more second templates that are indicative of a pathological cardiac pattern at a second stage, and wherein the method comprises switching from the first stage to the second stage in reaction to identifying that the at least one measurement comprises a fragment of at least a predetermined length of time in which the healthy pattern is not present. In a preferred embodiment, the method further comprises correlating the fragment with the one or more second templates and determining, for each of the one or more second templates, whether the correlation is above or below a predetermined threshold associated with the template.

[0132] An advantage of this embodiment is that it makes it possible to screen a biological entity under investigation for the risk of developing or the presence of pathological cardiac rhythm conditions by identifying an abandonment of a functional QRS episode, either one single or multiple events. These missing QRS patterns and missing R-wave can be isolated or grouped together in sequences of two or more occurrences. One the missing R-wave has been identified, an associated timeframe may further investigated for deviating patterns using one or more templates representing arrhythmogenic conditions (i.e. templates comprising the pathological cardiac pattern), in specific conditions indicative of the risk for development of Ventricular Fibrillation in the lifetime of the patient. These pathological conditions may be tachycardia, arrhythmias, fibrillation, WolfParkinson-White syndrome, (which may progress into Ventricular Fibrillation), SinusPause, AV-Block (1st, 2nd, 3rd degree), Long (prolonged) QT interval, Left or Right Ventricular Hypertrophy, Bradycardia, Sinus Bradycardia, Supraventricular Tachycardia / Junctional Tachycardia, Right- Axis deviation [Right Ventricular Hypertrophy] , Arrhythmogenic Right Ventricular Dysplasia, Right - or respectively Left Bundle Branch Block, and a broad range of additional arrhythmias with respect to the cardiac depolarisation in particular.

[0133] In an example, the method comprises identifying an early stage of onset to Ventricular Fibrillation prior to an actual full initiation of coarse or fine ventricular fibrillation by identifying one or more patterns in the at least one measurement and providing an advance warning using a monitoring device . It is noted that the actual time-frame of the advanced warning may depend on the monitoring device and / or mechanism-of action in use. For instance, an Implantable Cardioverter Defibrillator (ICD) may conserve energy during its lifetime and perform measurement in 100 second intervals. The latter case may offer opportunities to sense the development of conditions leading up to Ventricular Fibrillation at greater than 100 seconds prior to full development of ventricular fibrillation, i.e. fine ventricular fibrillation, and under conditions specific to the boundary conditions of the patient provide warning marker greater than 100 seconds prior to development of coarse ventricular fibrillation.

[0134] In an embodiment, the method further comprises determining a waveform for an electric stimulation of the organ, wherein the waveform is indicative of a pacing frequency and a pacing voltage amplitude over time, and wherein determining the waveform comprises determining a starting pacing frequency and decreasing the pacing frequency over time.

[0135] The present disclosure further relates to an electronic device for evaluating a cardiac rhythm of a heart comprising a power module, one or more electrodes configured to measure a biological signal corresponding the heart, a processing unit operatively connected to the one or more electrodes and the power module, wherein the processing unit is configured to perform the method for evaluating a cardiac rhythm of a heart in accordance with any of embodiment included in the present disclosure.

[0136] The electronic device has the same advantages and / or effects as described in relation to any method according to the present disclosure.

[0137] Before describing the innovation in detail, it should be understood that the application of the innovation is not limited to the construction details and arrangement of components indicated in the following description or illustrated in the drawings. The innovation may take other forms and be applied or realized in different ways.

[0138] It should further be understood that the wording and terminology used herein is for descriptive purposes and should not be considered restrictive. The use of “including”, “comprising”, “have”, “may comprise”, “may include”, “may have” or “with” and variations thereof in this document should be understood to include corresponding features and their equivalents, but do not exclude existence of additional features. The terms “assembled”, “connected” and “coupled” are used in a broad sense and include both direct and indirect assembly, connection, and coupling. Moreover, the terms “connected” and “coupled” are not limited to physical or mechanical connections or couplings, but may also include electrical, direct, or indirect connections or couplings. Furthermore, electronic communications and notifications can be made by any known means, including direct connections, wireless connections, etc.

[0139] The present disclosure is further illustrated by the following Figures, which show a preferred embodiment of the method and electronic device according to the present disclosure, and are not intended to limit the scope of the present disclosure in any way, wherein: Figure 1: shows a flow diagram of an example of a method according to the present disclosure;

[0140] Figure 2: shows a flow diagram of an example of a part of the method according to the present disclosure;

[0141] Figure 3: shows a schematic overview of a system according to the present disclosure. Figure 4: shows a schematic overview of a device according to the present disclosure;

[0142] Figure 5: shows an example of dataflow in an example of a device according to the present disclosure;

[0143] Figures 6a - 6c: show examples of different measurements and matched filters;

[0144] Figures 7a - 7d: show examples of different waveforms determined according to the present disclosure;

[0145] Figure 8: shows examples on how pacing frequencies may be decreased according to the present disclosure;

[0146] Figure 9a shows an example of a pulse determined with a method according to the present disclosure and figures 9b and 9c show pulses determined using conventional methods;

[0147] Figures 10a and 10b: show examples of pulses for electric stimulations determined / generated in accordance with the present disclosure;

[0148] Figures 11, 12, and 13 show various examples templates used to determine whether a measurement is indicative of an erratic biological signal in accordance with the present disclosure;

[0149] Figure 14 shows various additional examples of biological signals.

[0150] Figure 1 shows an example of determining a waveform in an embodiment of the system, device and / or method. In step S101 one or more measurements are acquired that are indicative for action potential of an organ. For example, in step S101 measurements acquired may be using electrodes configured to obtain measurements of a depolarization rate in the Purkinje system of the heart. It will be understood that the measurements may be acquired (i.e. obtained) via various suitable methods. The measurements may be obtained in real time and / or may be obtained from a memory in which measurements are stored and / or may be obtained from a simulation environment. It will be understood that in a setting wherein a machine learning model is trained to perform one or more steps of the method, measurements may be obtained from a memory and / or a simulation environment. Acquired measurements may further be (at least temporarily) stored in memory. It will be further understood that measurement may be obtained in parallel with other processes being performed, for example parallel to execution of other method steps. E.g. a second measurement may be obtained parallel to preprocessing of a first measurement.

[0151] In (optional) step SI 03 the acquired measurements are preprocessed. Preprocessing step SI 03 may comprise one or more preprocessing steps, which are for example performed by applying one or more of the following functions: amplification, filtration, noise reduction, rectification, smoothing, RMS, band-pass filtering, band-stop filtering, low-pass filtering, high-pass filtering, A / D conversion, Fourier Transformation (and variants thereof such as FFT, DFT, and other suitable variants), discrete wavelet transform, matched filter transform, resampling. It will be clear that the above list is not exhaustive, and that other filtering or preprocessing steps may be applied in order to reduce noise and / or artifacts in the acquired measurements. Step S103 may result in one or more preprocessed derivatives (e.g. variants) of the measurements. It will be clear that step S103 is optional and may be skipped. It will be clear that one or more preprocessing steps may be implemented using one or more, preferably dedicated signal processing, hardware module and / or in one or more software module.In (optional) step S105 one or more frequency patterns in the one or more measurements (and / or preprocessed derivatives thereof) are determined. It is noted that the one or more frequency patterns may represent a rhythm that is associated with the organ. For example, the one or more frequency patterns may represent a heartbeat rhythm.

[0152] In step SI 07 it is determined whether the measurement is indicative for an erratic biological signal, for example, when the measurement corresponds to a heart rhythm, it may be determined that the patient is suffering from a cardiac arrhythmia based on the measurement. For example, the frequency pattern determined in step SI 05 may be one that is indicative of the heart rhythm being too high and / or that is indicative of a cardiac arrhythmia.

[0153] Step SI 07 may further comprise identifying and extracting a subsection of the measurement where an anticipated healthy pattern is, at least temporarily, distorted or has missing identifiable markers in the progression of time.

[0154] When it is determined that the measurement is not indicative for an erratic biological signal, the method may return to step S 101. Alternatively, for example when the heart of the patient requires pacing to function normally, in step SI 15 the heart may be paced with one or more pacing pulses may be determined and / or applied to the heart using a conventional pacing method such as (permanent or temporary) transcutaneous or transvenous pacing. After step SI 15 the method may return to step S 101. It is noted that step SI 15 may also be regarded as determining the waveform but is shown separately to better distinguish the different cases in how the waveform is determined.

[0155] When it is determined in step SI 07 that the measurement is indicative of an erratic biological signal, a waveform is determined in step 109 which is indicative for an electric stimulation that may be used to revert an the out of control organ to normal function. Examples of how step 109 may be implemented are provided below in relation to figures 5 and 6 and in other parts of the present disclosure.

[0156] When the waveform is determined in step 109, it is converted in step Si ll to one or more pacing pulses indicative for pulses with which the patient can be electrically stimulated. At step SI 13 an electric stimulation is applied to the patient, wherein the electric stimulation corresponds to the pacing pulses. It will be clear that step SI 13 is optional or, at least in some cases, not considered to be a part of the method, but is displayed for sake of clarity to make it clear that the method may comprise steps that are taken after an electric stimulation is applied. After the electric stimulation is applied (i.e. delivered to the patient) in step SI 13, method 100 may be repeated by performing step S101 again. Method 1000 may also stop after step Si l l or method 100 may continue with the steps in method 200 (see figure 2).

[0157] Figure 2 shows an example of method 200, which may be performed after a stimulation is applied to the patient in step SI 13. Method 100 and method 200 may be considered to be part of one method. As in method 100, it will be clear that step SI 13 is optional or, at least in some cases, not considered to be a part of the method, but is displayed for sake of clarity to make it clear that the method may comprise steps that are taken after an electric stimulation is applied. After electric stimulation is applied, SI 13, a succeeding measurement is taken S201 in similar fashion to step S101 in method 100, which is optionally also preprocessed in step S203, in similar fashion as preprocessing step SI 03 in method 100. Similarly, in optional step S205 a frequency pattern of the succeeding pattern may be determined in similar fashion as step S205 of method 100. In step S207 it is determined, S207-1), whether the succeeding measurement is indicative of an erratic biological signal (similar to step SI 07) and if so, it is determined, S207-2, whether capture was achieved. Note that if in step S207-1 it is determined that the succeeding measurement is not indicative of an erratic signal, this determination may imply that capture was achieved. When the succeeding measurement is not indicative of an erratic biological signal, method 100 may again be executed, for example starting at step S115 or S101 or method 200 may be aborted.

[0158] In step S207-2 it is determined whether capture was achieved by the electric stimulation of step SI 13. Determining whether capture is achieved may for example be done by observing a difference in the frequency pattern determined in step S105 and the frequency pattern determined in step S205. For example, when the frequency pattern determined in step S205 corresponds to a lower heart rate compared to the frequency pattern determined in step SI 05, it may be concluded that capture was achieved, while when the two frequency patterns a similar (or the frequency pattern determined in step S205 is higher), it may be concluded that capture was not achieved. In another example, it is concluded that capture is achieved when the frequency pattern determined in step S205 corresponds to the pacing frequency that was determined for electric stimulation SI 13 (and likewise determined that capture was not achieved when this is not the case) or by observing a difference between measurements acquired in step S101 and in step S201, wherein the difference is indicative of capture being achieved (or is not achieved).

[0159] When it is determined that capture is achieved in step S207-2, the waveform is determined in step S209 by lowering the pacing frequency S209-1 of the existing waveform and / or by lowering the pacing voltage amplitude S209-2 of the existing waveform. After step S209 method 200 may be repeated. It is noted that step S209 may include converting the waveform to pulses similar to step Si l l in method 100. It will be clear that step SI 13 is optional or, at least in some cases, not considered to be a part of method 200, but is displayed in figure 2 for sake of clarity so that it is clear that method may be executed after an electric stimulation is applied.

[0160] Figure 3 shows system 1000 with processor 1001 and memory 1003, wherein memory 1003 contains instructions to perform one or more steps of methods 100 and / or 200 and wherein processor 1001 is configured to execute methods stored in memory 1003. It will be clear that system 1000 may have other parts and / or modules not shown, such as a communication module, power module etcetera. It may also be clear that system 1000 may be part of a larger system or device, such as an AED device, pacemaker, or an implantable cardioverter defibrillator.

[0161] Figure 4 shows a schematic overview of electronic device 1 , wherein device 1 with electrodes 3 connected with processing module 5 and power module 7. Power module 7 may further be electronically connected to processing module 5 and pacing wires 9. Power module 7 may also be connected to other modules, such as communication module 13, but for sake of clarity these connections are not shown. Processing module 5 may be operatively connected to electrodes 3, power module 7, communication module 13 and storage module 11 and may be configured to control one or more of these modules. It will be clear that device 1 may have other modules not shown. Processing module 5 may have several sub-modules (implemented in either software, hardware, or both), such as preprocessing module 5a, detection module 5b, pulse module 5c and pacing module 5d, that are configured to execute distinct parts of the functionality of device 1. It will be clear that other submodules not shown may exist. Electrodes 3 may have electrode 3a configured to measure action potential activity of an organ of the patient, such as a heart, and may further have electrode 3b which is configured to act as a reference electrode. Alternatively, both electrodes 3a and 3b may be configured to measure action potential activity of the organ. It is clear that electrodes may include other electrodes not shown, such that an even more complete measurement of the organ activity may be obtained. For example, by placing various electrodes in different locations around the heart, the measurement may provide a spatial (e.g. 3D) overview of depolarization activity of the heart muscle. A similar method may be applied to obtain a spatial overview action potential activity from another type of organ). Electrode 3 may be any suitable electrode, wherein the type of electrode may depend on whether device 1 is implantable or an external device.

[0162] Pacing wires 9 may be configured to deliver an electric stimulation to the organ and are configured to be positioned around the organ, preferably at positions at which electric stimulation is optimized, such as the His bundle of the heart, the Left Bundle Branch of the heart, the cardiac Purkinje fibers of the heart, such that a lower pacing voltage amplitude may be used while capture is still achieved. It is noted that pacing wires 9 may exist separately from electrodes 3, but that in other examples, some of electrodes 3 may also be configured to act as pacing wires, next to pacing wires 9 or even replacing the functionality of pacing wires 9 (e.g. device 1 may not having pacing wires 9, but use electrodes 3 to deliver the electric stimulation). Pacing wires 9 may comprise leads 9a and 9b to connect deliver power from power module 7 to the organ.

[0163] Power module 7 may have several energy sources 7a, such as one or more lithium batteries, and may further have one or more capacitors 7b configured to be charged by energy source 7a and are further configured to be controlled by power module 7 and / or processing module 5 to deliver an electric stimulation to the organ via pacing wires 9 and or electrodes 3.

[0164] Communication module 13 is connected to processing module 5 and may have several communication interfaces configured to connect to an external system (not shown), such as Bluetooth 13a or wired connection 13b. It will be clear that any suitable interfaces may exist. The connection with external system (not shown) may for example be used to during operation of device 1, upload information relating to the working of device 1, such as measurements obtained using electrodes 3, detection information from processing module (e.g. information about an erratic signal being determined), information relating to electric stimulations applied to the patient, device status information (e.g. battery energy levels), and any other relevant information that is present, measured, determined and / or otherwise made available on device 1. Communication module 13 may further be configured to download data from the external system to device 1, such as patient information, history pulsing information, updated templates for matched filters, updated machine learning models, updated instructions etc. Storage module 11 may have memory I la to at least temporarily store data and / or instructions (e.g. a Random Access Memory) and drive 1 lb for permanent storage 11b (e.g. older measurements, instructions for processing module, patient information, and other suitable data elements).

[0165] Figure 5 shows an example of dataflow in device 1 during operations thereof. It will be clear that this dataflow is only an example illustration, and that different dataflows and setups may exist. It will further be clear that one or more shown of the shown modules and / or data elements are optional or may be encompassed in other modules. During operation, electrodes 3 may be used to obtain n measurements Ml - Mn, see figure 6 for two examples of measurements. The measurements may have a uniform length or may have a non-uniform length, for example between 1 and 20 seconds, for example 5 or 10 seconds, the length may depend on an average action potential activity of the organ, e.g. the length may be set such that on average measurements Ml -Mn may contain between 3 and 100 depolarization events.

[0166] Measurements Ml - Mn are received / obtained by preprocessing module 5a in which one or more preprocessing steps might be applied to determine k derived signals DI - Dk. It is noted that k may be equal to n or may be smaller or larger than n. It is also noted that one or more of derived signals DI - Dk may be in another representation than measurements Ml - Mn, for example, when compressed sensing is applied, measurement Ml may be represented as vector y with dimension W and may be expressed in a compressed domain as derived signal DI that is constituted by V linear projections of vector x which comprises a linear combination of the native underlying W- dimensional measurement, described as: y = <t>x where is an H X J random (but defined) data matrix, typically referred to as a data acquisition “sensing” matrix and wherein II « JJ defines a compression ratio and wherein preferably sensing data matrix is in compliance with the Restricted Isometry Property “RIP”.

[0167] Derived signals DI - Dk are passed onto (or obtained by) detection module 5b that is configured to determine whether measurements Ml - Mn are indicative of erratic biological signal. During this process, detection module 5b may obtain patient information Pl - Pq from storage module 11. Patient information Pl - Pq may comprise reference signal Pl (e.g. a template) that is representative for a depolarisation-peak of the organ, reference signal Pl may be adjusted to be specifically representative of a typical depolarisation-peak of the specific patient. Reference signal Pl may also be represented in the compressed domain and detection module 5b determines a number of depolarization peaks that is present in derived signal DI, for example by calculating correlations between reference signal Pl and derived signal DI in the compressed domain using a matched filter approach. Reference signals Pl may for example be a vectorized representation of a QRS complex, preferably a QRS complex typical of the patient. A QRS complex is associated with a typical electrocardiogram of the heart and comprises a combination of three deflections that are present in a depolarization event of a left ventricle, right ventricle, and the large ventricular muscle of the heart. The QRS complex comprises a first deflection, known as a Q wave, which is any downward deflection immediately following a so called P wave (associated with atrial depolarization), a second deflection known as a R wave that is an upward deflection following the Q wave, and a third deflection known as a S wave, that is a downward deflection after the R wave. The QRS complex may be used to determine a heartbeat by observing respective duration between sequential R peaks.

[0168] For example, a heartbeat may be detected in measurement Ml by detection module 5b by applying a direct estimator function or an orthogonalized estimator function, based on a matched filter, to DI (which in this example comprise a representation of measurements Ml in the compressed domain using data matrix <b) and template Pl (which in this example is a vectorized representation of a QRS complex in the compressed domain using data matrix <b) to determine possible locations in signal Ml that match the QRS complex and are thus indicative of a ventricular depolarization event.

[0169] It will be clear that peak detection may also be applied to derived signals D2 - Dk and that multiple templates may be used in the peak detection and / or that peak detection may be performed in another suitable manner. Detection module 5b may further determine whether measurements Ml - Mn are indicative of an erratic biological pattern, for example by determining frequency patterns Fl - Fr by dividing the number of detected peaks detected in derived signals DI - Dk with the length of the measurements Ml - Mn to determine a frequency pattern expressed in depolarization events per second (e.g. hertz, Hz) and determine that the measurements are indicative of an erratic biological signal if one or more of the frequency patterns Fl - Fr is above a predetermined threshold.

[0170] Additionally, or alternatively, detection module 5b may determine that the measurements are indicative of an erratic biological signal by determining that a respective duration between detected peaks is irregular.

[0171] Detection module 5b determines that measurements Ml - Mn are indicative of an erratic biological signal, when at least one of the frequency patterns Fl - Fr exceeds a predetermined critical depolarization rate threshold. The predetermined critical depolarization rate threshold may be comprised in patient information Pl - Pq. For example, detection module 5b may identify a plurality of pulses in measurement Ml and determine, based on said pulses, that frequency pattern Fl of measurement Ml is 5 Hz, which corresponds to a heartbeat of 300 beats per minute.

[0172] Detection module 5b (figure 5) may further determine that frequency pattern Fl is above predetermined critical depolarization rate threshold P2 of 3 Hz (which corresponds to a hear beat of 180 beats per minute) and that thus measurement Ml is indicative of an arrhythmia. Detection module 5b may alternatively determine that measurement Ml is indicative of an erratic biological signal by determining that a time between detected peaks is irregular, this is especially clear when considering measurement M101 and M201 in figure 6 which shows irregular time intervals tioi - tin between peaks detected in measurement M101 (that corresponds to an irregular signal) and regular time intervals tsoi - 1305 between peaks detected in measurement M201, meaning M2 is not indicative of an erratic biological signal.

[0173] It will be clear that various other methods may be applied by processing module 5 for preprocessing, for detection of peaks (for example using threshold peak-detection), for determining frequency patterns of measurement Ml - Mn, for determining whether Ml - Mn correspond to erratic biological signals, and any other determination or signal processing step. It will be clear that the steps relating to determining whether the measurement are indicative for an erratic biological signal (e.g. steps S101 - S107) may also performed as a separate method.

[0174] When detection module 5b determines that measurement Ml - Mn are indicative of an erratic biological signal, pacing module 5c may determine one or more waveforms T1 - Tx by, for example, determining a starting pacing frequency and pacing voltage amplitude of waveform Tl. Starting pacing frequency may be for example set to be at 90% of frequency pattern Fl (e.g. pacing occurs at 270 beats per minute). It will be clear that the above percentage is just an example. In another example, the starting pacing frequency may be set to be similar to the predetermined critical depolarization rate threshold. Pacing module 5c may use patient information Pl - Pq to determine waveform Tl. When one or more electric stimulations were already applied to the patient in a predetermined time period (for example, when electric stimulation was applied to the patient in the last minute), the pacing frequency and / or the pacing voltage amplitude may be adjusted by pacing module 5c accordingly, preferably in dependence on a determination whether capture was achieved.

[0175] In an example, when historic pacing information of the patient shows that successful capture achieved when pacing at a rate of 95% of frequency pattern Fl, but capture was not achieved when pacing at a rate of 90% of frequency patterns Fl, the starting pacing frequency may be set to be 92,5% of the frequency patten Fl. It will be clear that more complicated prediction modules may be used that correlate historic pacing frequencies and capture information to determine a suitable starting pacing frequency. The starting pacing voltage amplitude may be a predetermined pacing voltage amplitude, for example between IV to 30V, preferably around 5V or may be determined in dependence of historic voltage amplitude information. Alternatively, when it is determined that a reset pulse is necessary, the pacing voltage amplitude may be set to be in a range of 600V to 1200V, for example 800V, for a single cycle in the waveform Tl. It is noted that multiple waveforms Tl - Tx may be determined at the same time, for example, when several electric stimulations with different amplitudes are to be applied to the organ at the same time but at different to locations. Multiple waveforms Tl - Tx may also refer to parts of a single waveform, wherein the waveform starts at Tl and continuous to Tx. Tl - T(x - 1) may also refer to previous waveforms while waveform Tx is to be determined.

[0176] After waveform Tl is determines, pulse module 5d converts waveform Tl from a sinusoidal form to one or more block pulses Pl - Py, by placing a block pulse at each (local) maximum in waveform Tl. Block pulses may have a set duration, for example between 0.1 milliseconds and 10 milliseconds, and preferably between 0.5 milliseconds and 5 milliseconds, more preferably 0.5 milliseconds when the pulses do not correspond to a reset pulse and 5 milliseconds for a pulse that corresponds to a reset pulse. The pacing voltage amplitudes of block pulses Pl - Py may correspond to the pacing voltage amplitude of waveforms Tl - Tx. Pulses Pl - Py may be send to Power Module 8 which controls capacitor 7b to deliver electric stimulation to the patient in the form of pulses Pl - Py at predetermined moments using pacing wires 9 and / or electrodes 3. It will be understood that other pulse shapes than block pulses may be used. After the electric stimulation is applied, new measurements may be obtained.

[0177] Figure 6 shows two example measurements, measurement M101 (shown in both figure 6 A and 6B) and measurement M201 shown in figure 6C. Measurement M101 is an example of a measurement indicative of an erratic biological signal of a heart, more specifically with a measurement indicative of ventricular fibrillation, showing a rapidly fluctuating signal with pulses (also revered to as peaks) with various amplitudes and irregular intervals between pules. Measurement M201 is an example of a measurement indicative of a “normal” biological signal of the heart of a patient. Measurements may for example be obtained via an Electrocardiogram positioned on the outside of the body of the patient.

[0178] Measurement m 101 (fig 6A) shows a rapidly fluctuating signal with pulses with various amplitudes. For example, pulses (also revered to as peaks) in measurement Ml (which may be identified by detection module 5b) have various amplitudes and the duration between the pulses may vary (e.g. time tlOl between a maximum of the first pulse and the maximum of pulse may be longer relative to the time between the maximum of pulse a third pulse and the maximum of a fourth pulse. On the other hand, measurement m201 (fig. 6C) shows pulses which have a stable amplitude and with a stable duration tl’ between the peaks.

[0179] Pulses in measurements M101 and M201 (indicated using vertical dash-dotted lines) may be identified by, for example, detection module 5b, using a forward matched filter using template mf- 101 (see figure 6A) and a backwards matched filter using template mf-103 (see figure 6B), both templates visualized using arrows. Note that matched filters templates mf-101 and mf-103 are merely shown to aid the user in their understanding in how a template in a matched filter may be used to determine locations of peaks in a measurement by finding correspondences between said templates and parts of measurements. It will be clear that other peak detection methods and / or alternative or additional templates may be employed. It will also be clear that templates mf-101 and mf-103 are only shown at some locations where the detection module may determine that a correspondence exist between the templates mf-101 and mf-103 and the measurements M101 and M201. It will further be clear that matched filters do not need a visual representation of the templates and that properties like shape, size, position, numbers, and other properties of the shown templates mf-101 and mf-103 are primarily chosen such that the figures are clear.

[0180] Detection module 5b may in this example determine that measurement M101 corresponds to an erratic signal by observing a pulse frequency based on the determined pulse locations and / or by observing that one or more duration tioi - tin and tzoi - t2i7 (e.g. interval durations between pulses) are shorter than a pre-determined threshold and / or by observing that there the intervals between the pulses is irregular, e.g. there exist a larger than expected variation between durations tioi - tin and t2oi - t2i7- Detection module 5b may in this example further determine that measurement M201 corresponds to a normal / regular signal by for example observing that durations tsoi - t3os t2i7 (e.g. interval durations between pulses) are of a relative similar length and / or by observing that the pulses are of a similar amplitude. Although forward matched filter with template mf-101 is shown with regard to measurement M201, it will be clear that other templates (such as mfl03) may also be applied.

[0181] Figure 7 shows various waveforms wl - w4 comprising a sinus like waveform with a plurality of pulses indicative that are indicative for electric stimulation (pulses) to be delivered at time t. Waveforms wl - w4 illustrate different variants of how the pacing energy may be reduced over time according to the present disclosure. In waveform wl, shown in figure 7A, both the pacing frequency and the pacing voltage amplitude are both continuously reduced over time to gradually arrive at a desired pacing frequency and pacing voltage amplitude. In waveform w2, shown in figure 7B, the pacing frequency is hold constant until time t4oi, after which it is gradually reduced. The pacing voltage amplitude is kept at a constant level of approximately 6V. In waveform w3, shown in figure 7C, the pacing frequency is reduced in concrete steps between points tun, -5 and (407, while keeping the pacing voltage amplitude at a constant voltage. During the period between t4os and t407 it is determined that the pacing frequency is approximately at the predetermined critical depolarization rate threshold. During the period between t407 and 1409 no pacing is applied, alternatively, the waveform starting from 1409 may start directly after (407. From 1409 the pacing frequency is kept at approximately at the predetermined critical depolarization rate threshold, while the pacing voltage amplitude is gradually reduced. In waveform w4, shown in figure 7D, both the pacing frequency and the pacing voltage amplitude are lowered in discrete steps at times (413, t4i7, t42i , while periods between (411 t4i3, t4i5 - t4i7, t4i9 - t42i.exist in waveform w4 in which there is no pacing.

[0182] Figure 8 shows examples on how pacing frequencies may be decreased over time. Here, dfl and df3 show examples on how pacing energy may be gradually decreased (semi-)continues over time, while df2 and df4 show examples on how the pacing frequency changes when the pacing frequency is decreased in a discrete step-down pattern. Furthermore, df2 and df4 show example on how a stable baseline operating frequency may be maintained after the pacing frequency has been sufficiently decreased, while dfl and df4 show how alternatively pacing may be stopped when the pacing frequency has been sufficiently been decreased.

[0183] Figure 9 shows various pulses suitable for electric stimulation. Figure 9A shows a bi-phasic pulse of an electric stimulations determined based on a waveform determined / obtained using a method / device / system according to the present disclosure, wherein the electric stimulations has a block-like form, starting with a main pulse at voltage Vi(i) with a pacing voltage amplitude of 5 Volts which over a duration tsoi of 0.5 millisecond lowers to slightly lower voltage Vf<i) of around 4.9 Volts, followed by afterpotential pulse starting at voltage Vi(2) of about -1 Volt which over a duration of about 0.25 milliseconds increases towards Voltage Vi(2) to about -0.5 Volt. Note that the respective difference between Vi(i) and Vf<i) and difference between Vi(2) and Vf(2) are mainly due to the nature of how energy is released from capacitors. It will be clear that instead of a bi-phasic pulse shown in figure 9A, a mono-phasic pulse which does not contain the afterpotential pulse may also be used instead in a method / system / device according to the present disclosure. Figures 9B and 9C show pulses of electric stimulations used / generated by conventional implantable cardioverterdefibrillators (ICDs). Figure 9B discloses a bi-phasic pulse of a conventional ICD, which has starting amplitude Vi(i) of approximately 800 Volts and a duration of approximately 5 milliseconds to final amplitude Vf(i>, followed by a negative pulse (afterpotential) of a shorter (compared to t503) duration t505 starting at amplitude Vi(2) of about -400 Volts and increasing towards an amplitude starting at amplitude Vf(2) of about -200 Volts. A conventional ICD may also employ a mono-phasic pulse as shown in figure 9C, which is similar in form to the positive pulse in figure 9B, but which does not have a negative pulse. Comparing the pulse in figure 9A with the pulses in figure 9B and 9C it will be clear that the energy delivered and required by the conventional pulses in figures 9B and 9C is magnitudes larger than the pulse in figure 9A which is determined according to the present disclosure. It will thus also be clear that pulses of figures 9B and 9C are more likely to result in damage to tissue of the organ and / or to pain or at least discomfort experienced by the patient and / or drain the battery quicker. It is noted that other amplitudes as shown in figure 9A may be used in a method / system / device according to the current disclosure.

[0184] Figure 10A provides a visualization showing electric stimulations ESI - ESI 5 generated based on one or more waveforms determined / obtained using a method / system / device in accordance with the current disclosure and their relation with depolarization events dpe 1 - dpe 15 of an organ to which electric stimulations ESI - ESI 5 are applied. Electric stimulations ESI - ESI 5 may be similar to the electric stimulation pulse shown in figure 9A, each with a duration in the range of 0.5 to 2 milliseconds, and wherein ESI has a pacing voltage amplitude of about 20 Volts for its main pulse and an amplitude of about -0.5 Volt for its afterpotential pulse and wherein the pacing voltage amplitudes of each electric stimulation is slightly decreased compared to its predecessor, wherein electric stimulation ES 15 has a pacing voltage amplitude of about 4 Volts for its main pulse. Each electric stimulation ESI - ESI 5 is synchronized to the local maximum of a corresponding depolarization event dpe 1 - dpe 15 of wave dflOl showing a sequence of successful captures in which the depolarization frequency of the organ (represented by distances between the consecutive peaks of depolarization events dpe 1 - dpe 15) slowly decreases and wherein the pacing frequency and pacing amplitude corresponding to each electric stimulation ESI - ES 15 is decreased / lowered relative to its predecessor bringing the depolarization frequency of the organ slowly to a “normal” sustainable rhythm. It is noted that wave dflOl shows a very abstract representation of depolarization events of an organ, such that it is more clear how the electric stimulations are synchronized with the depolarization events. It is noted that the amplitude of the pulse may corresponds to that of the waveform, but that the duration of the pulse may be shorter compared to a cycle duration identified in the waveform

[0185] Figure 10B shows an electric stimulation corresponding to a single bi-phasic reset pulse that is generated using a method / device / system according to the present disclosure and wherein the reset pulse is synchronised with depolarization event dpe 101 such that main pulse Rl-a is synchronized / centred with the maximum of the positive deflection dpe 101-a of depolarization event dpe 101 and wherein afterpotential pulse R 101-b of the reset pulse occurs before the negative deflection dpe 101-b of depolarization event dpe 101. Figures 11 to 13 disclose various examples of templates in accordance with the present disclosure. Figure 11 shows an example of base template 1001 indicative of a healthy QRS pattern represented by points 1003a - 1003j. It is noted that points 1003a - 1003j may be represented as relative values (Volt) relative to a reference point (not shown). The reference point may be adapted in accordance with the at least one measurement. Additionally, base template 1001 may be adjusted to individual template 1005 in dependence of one or more historic measurements from a certain patient, for example by decreasing the relative value of point 1003a by 5% and by increasing the relative value of point 1003i by 10%. Figure 12 shows template 1007 indicating a double peak depolarization pattern associated with a pathological condition. It will be clear that multiple templates may be constructed by modifying a base template, e.g. by mirroring, reversing, stretched etc. of a base template. For example, double peak base template 1007 may be included in the one or more templates in original (forward) forml007, in backwards form 1009 and in mirrored form 1011 (in which base template is flipped in its horizontal). Likewise, figure 13 shows a further example of various templates 1013 includes single peak template 1013 and double peak template 1014 that both have a stretched appearance associated with a deviation of a healthy depolarization pattern.

[0186] It is noted that many variances of the templates may be employed other than those shown in figures 11 0 13. In reference, the following value may be used to indicate when a depolarization pattern in the at least one measurement falls outside the “healthy” range of values, e.g. following may be used to construct the one or more templates: on average a VF pulse is 2 to 3 times longer than an average healthy R-wave, while the amplitude is 25-15% of the R-peak value.

[0187] A R-peak maximum values, for example, in case of a 12 lead ECG.

[0188] - Lead I: 1.5 mV;

[0189] - Lead aVL: 1.0 mV;

[0190] - Lead II, Lead III, respectively aVL: 1.9 mV.

[0191] - It is noted that any lower values are not necessarily pathological, and that actual values may vary between genders, age, activity etc. Lor example, Younger people may present larger amplitudes -

[0192] QRS duration, starting at depolarisation onset of Q, ending after termination of depolarisation of S: on average <0.12 sec for the male gender [+ / -0.02 s, age activity history, etc.] ; potentially 0.13 sec + / - 0.2 sec for the female gender. The R-wave itself may be a brief as 0.035 Seconds, measured from baseline 0 Volt.

[0193] The one or more templates associated with a healthy cardiac cycle may be based on the following averages:

[0194] On-slope of R-wave for healthy individual on average.

[0195] Lead I equivalent: 0.16 V / s - Lead II 0.02 V / s

[0196] Lead III equivalent: 0.08 V / s

[0197] - Lead V2: 0.02 V / s

[0198] - Lead V3: 0.145 V / s

[0199] - Lead V6: 0.052 V / s

[0200] Backward On-slope of R-wave for healthy individual on average.

[0201] - Lead I equivalent: 0.115 V / s

[0202] - Lead II 0.l l V / s

[0203] - Lead III equivalent: 0.055 V / s

[0204] - Lead V2: 0.135 V / s

[0205] - Lead V3: 0.16 V / s

[0206] - Lead V6: 0.037 V / s

[0207] Coarse Ventricular Fibrillation slope, Lead III:

[0208] - Forward: 5.6 E-3 + / - 1.6 E-3 V / s

[0209] - Backward on-slope: 9.4 E-3 + / - 6.2 E-3 V / s

[0210] Fine Ventricular Fibrillation slope, Lead III:

[0211] - Forward: 0.0035 + / - 0.0013 V / s

[0212] - Backward on-slope: 0.004 + / - 0.001 V / s

[0213] It is noted that in conjunction with a determination of potentially pathological slope of a depolarization a ‘one -plus some’ pulse filter may be applied under increasing steps of complexity. The ‘one-plus-some’ filter template may use a predetermined shape format, derived from a plurality of history measurements of VF in a patient cohort that matched a greater that 75% of factors from a large data-base of acquired signals derived from patients in various population groups: age, gender, activity history, medical conditions, prescription drug use, recreation drug use, alcohol use, caffeine intake, etc.

[0214] In an embodiment, the at least one template that is indicative of a pathological cardiac pattern associated with a pathological condition comprises a pattern that is indicative for one of the following:

[0215] 1) 1st degree A V-block

[0216] 2) Atrial Fibrillation

[0217] 3) Atrial Flutter

[0218] 4) Bradycardia

[0219] 5) Complete Right Bundle Branch Block (LBBB) [Purkinje fibers]

[0220] 6) Hypertrophic cardiomyopathy (namely: Left Ventricular Hypertrophy (LVH))

[0221] 7) Incomplete Right Bundle Branch Block (IRBBB) [Purkinje fibers]

[0222] 8) J-point 9) J-60 point

[0223] 10) Left-Axis deviation [Purkinje fibers]

[0224] 11) Left Anterior Fascicular Block (LAFB)

[0225] 12) Left Bundle Branch Block (LBBB) [Purkinje fibers]

[0226] 13) Left Ventricular dysfunction (defined as an LV ejection fraction [LVEF] <35%)

[0227] 14) Low QRS voltages

[0228] 15) Nonspecific Intraventricular conduction disorder

[0229] 16) P-P interval

[0230] 17) P-R interval

[0231] 18) PR segment

[0232] 19) P-wave duration

[0233] 20) P-top amplitude, in reference to QRS

[0234] 21) Pacing Rhythm; SA-node functionality

[0235] 22) Premature Atrial contraction

[0236] 23) Premature Ventricular contraction

[0237] 24) Prolongation of interval; for instance: Long - Q-T interval, S-T segment duration, and P-Q interval.

[0238] 25) Prolongation of P-R interval

[0239] 26) Q-wave abnormalities; e.g. duration, amplitude, deletion / reduction of the follow-on R-wave.

[0240] 27) R-R interval; i.e. derived heart rate

[0241] 28) Right-Axis deviation

[0242] 29) Right Bundle Branch Block (RBBB) [Purkinje fibers]

[0243] 30) Sinus arrhythmia

[0244] 31) Sinus Bradycardia

[0245] 32) Sinus Rhythm

[0246] 33) Sinus Tachycardia

[0247] 34) ST segment

[0248] 35) ST-T segment

[0249] 36) Supraventricular Premature beats

[0250] 37) T-P interval

[0251] 38) T-wave abnormalities

[0252] 39) T-wave inversion

[0253] 40) Ventricular premature beats

[0254] 41) Ventricular Fibrillation; VF, V-Fib The associated pathological conditions associated with the above include but are not limited to one of: a heart attack, an arrhythmia, a heart-failure, a cardiomyopathy, and a heart-valve disease.

[0255] It is noted that, in accordance with the present disclosure, one or more parameters may be determined (and optionally output) that are not shown in figure 14 in reaction to identifying whether the at least one measurement comprises a fragment of at least a predetermined length of time in which the healthy pattern is not present, wherein the one or more parameters comprise one or more of: an on-slope of an individual depolarization wave segment in the fragment; a backward on-slope of a individual depolarization wave segment in the fragment, (wherein the method may comprise investigating the at least one measurement around the fragment backward in); a repetition occurrence and / or a repetition rate of patterns in the at least one signal similar to the pattern in the fragment; an amplitude of a respective pathological replacement depolarization wave segment in the fragment; a Peak-to-Peak interval variability in the at least one measurement, when more than one pathological pattern is identified in the at least one measurement in sequential order; a reference voltage drift (not assuming alternating around Zero Volt), it is noted that specifically Ventricular Fibrillation does not adhere to depolarization around a fixed reference base-line); a sequential pulse count of pulses with a slope that is less steep in comparison to an expected healthy R-wave;

[0256] A special marking of “single-occurrence” depolarization pattern deviating from an established QRS pattern that has been obtained for the patient under observation. It is noted that doing so allows to take into a variability of a QRS pattern for this patient under various personal exercise activities and external influences, such as medication and recreational drugs use as well as external temperature (e.g. hot summer’s day) in consideration.

[0257] Figure 14 provides an overview of various measurements for illustrative purposes, including a “healthy” cardiac cycle 1016 and cardiac cycles 1018a - 1018i showing various pathological conditions, such as course Ventricular Fibration 1018a, fine Ventricular Fibration 1018b, measurement 1018c which included fragment 1020 with in which a QRS pattern is absent.

[0258] The description and drawings merely illustrate the principles of the present disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the present disclosure and are included within its scope. Furthermore, all examples recited in the present disclosure are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the present disclosure and the concepts contributed to the disclosure to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples thereof, are intended to encompass equivalents thereof.

[0259] The functions of the various elements shown in the figures, including any functional blocks labelled as “processors”, may be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared. Moreover, explicit use of the term “processor” or “controller” should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor (DSP) hardware, network processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), read only memory (ROM) for storing software, random access memory (RAM), and non-volatile storage. Other hardware, conventional and / or custom, may also be included. Similarly, any switches shown in the figures are conceptual only. Their function may be carried out through the operation of program logic, through dedicated logic, through the interaction of program control and dedicated logic, or even manually, the particular technique being selectable by the implementer as more specifically understood from the context.

[0260] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative circuitry embodying the principles of the present disclosure. Similarly, it will be appreciated that any flowcharts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer.

[0261] The term "approximately" is used herein as a synonym for the term "circa". To illustrate, the use of the term "approximately" denotes values that are slightly outside the listed values, i.e. plus or minus 10%. Such values therefore fall within the range of designations using the terms "approximately" and "circa".

[0262] It should be noted that the above-mentioned embodiments illustrate rather than limit the present disclosure and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word “comprising” does not exclude the presence of elements or steps not listed in a claim. The word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. The present disclosure can be implemented by means of hardware comprising several distinct elements and by means of a suitably programmed computer. In claims enumerating several means, several of these means can be embodied by one and the same item of hardware. The usage of the words “first”, “second”, “third”, etc. does not indicate any ordering or priority and does not indicate the absence of any further elements that are not explicitly numbered. These words are to be interpreted as names used for convenience. The present disclosure is not limited to the embodiments shown above, but extends also to other embodiments falling within the scope of the appended claims.

Claims

CLAIMS1. Computer implemented method for determining a waveform for an electric stimulation for restoring an erratic biological signal of an organ of a patient, wherein the method comprises:- acquiring a at least one measurement that is indicative of an action potential activity of the organ;- determining whether the at least one measurement is indicative of an erratic biological signal;- in reaction to the at least one measurement being indicative of an erratic biological signal, determining a waveform for an electric stimulation of the organ, wherein the waveform is indicative of a pacing frequency and a pacing voltage amplitude over time, and wherein determining the waveform comprises determining a starting pacing frequency and decreasing the pacing frequency over time.

2. The method according to claim 1, wherein determining the waveform further comprises adjusting the pacing voltage amplitude in dependency of at least the pacing frequency in order to not exceed a predetermined maximum pacing energy.

3. The method according to claim 1 or 2, wherein the method further comprises determining a frequency pattern that corresponds to the at least one measurement.

4. The method according to claim 3, wherein determining that the at least one measurement is indicative of an erratic biological signal comprises determining that the frequency pattern is at least partly associated with a nonfunctional working of the organ and / or body of the organ.

5. The method according to claim 3 or 4, wherein determining the starting pacing frequency comprises determining a repetition rate in a frequency pattern of the at least one measurement, and wherein the starting pacing frequency is in a predetermined range from the repetition rate.

6. The method according to claim 3, 4 or 5, wherein determining the repetition rate comprises identifying a plurality of peaks in the at least one measurement and wherein the repetition rate is a function of a count of the identified peaks and a duration of the at least one measurement.

7. Method according to claim 6, wherein identifying peaks in the at least one measurement comprises applying a matched filter to the at least one measurement.

8. The method according to any of the previous claims, wherein determining the waveform comprises changing the pacing voltage amplitude in reaction to a change in the pacing frequency to maintain a target pacing energy.

9. The method according to any of the previous claims, wherein the pacing voltage amplitude is in a range of 30.0 - 0.1 volt, preferably in a range of 20 - 0.5 volt.

10. Method according to any of the previous claims, wherein determining the waveform comprises using a predetermined pacing voltage amplitude as a starting pacing voltage amplitude, wherein the starting pacing voltage amplitude is preferably in the range of 20.0 to 30.0 Volts.

11. Method according to claim any of the previous claims, wherein decreasing the pacing frequency over time comprises decreasing the pacing frequency towards a target pacing frequency.

12. Method according to any of the previous claims, wherein the target pacing frequency is a predetermined frequency range that associated with a functional operating for the organ.

13. Method according to any of the previous claims, wherein the at least one measurement is obtained over a predetermined time-interval.

14. Method according to any of the previous claims, wherein decreasing the pacing frequency over time comprises decreasing the pacing frequency incrementally in one or more discrete steps.

15. Method according to claim 14, wherein the one or more discrete steps have a predetermined step size or wherein the one or more discrete steps have a step size that is a factor of the previous pacing frequency.

16. Method according to any of the previous claims, wherein decreasing the pacing frequency over time comprises gradually decreasing the pacing frequency.

17. Method according to any of the previous claims, wherein decreasing the pacing frequency over time comprises decreasing the pacing frequency at a linear or a nonlinear rate.

18. Method according to any of the previous claims, the method further comprising acquiring one or more succeeding measurement after the organ has been stimulated with one or more electric pulses that corresponds to at least a part of the waveform and determining whether capture is achieved with said stimulated of the organ by determining that a frequency pattern corresponding to the one or more succeeding measurement is indicative of a capture.

19. Method according to claim 18, wherein determining the waveform further comprises decreasing the pacing energy in reaction to the determination that capture is achieved and / or increasing the pacing energy in reaction to the determination that capture is not achieved.

20. Method according to claim 19, wherein decreasing the pacing energy comprises decreasing the pacing frequency in reaction to the determination that capture is achieved.

21. Method according to claim 19 or 20, wherein increasing the pacing energy comprises increasing the pacing voltage amplitude and / or wherein decreasing the pacing energy comprises decreasing the pacing voltage amplitude.

22. Method according to any of the 18 - 21, wherein determining the waveform comprises adding a reset pulse to the waveform with a voltage amplitude that is higher than the pacing voltage amplitude in reaction to a determination that capture is not achieved, wherein the reset pulse is preferably timed to be at a respective next local maxima in the waveform.

23. Method according to claim 22, wherein the voltage amplitude of the reset pulse is in a range of 100 volt to 1200 volt, preferably in the range of 300 volt tolOOO Volt,and / or wherein the reset pulse has a pulse duration in the range of 1.0 milliseconds to 30.0 milliseconds, preferably in the range 5.0 milliseconds to 20.0 milliseconds.

24. Method according to claim 18 - 23, wherein the method further comprises determining an effectiveness of the electric stimulation to the organ with the electric pulse that correspond to at least a part of the waveform by determining a difference between the frequency pattern corresponding to the at least one measurement and a frequency pattern corresponding to the one or more succeeding measurements.

25. Method according to any of the previous claims, wherein the method further comprises converting at least a part of the waveform to one or more pulses, preferably one or more block pulses, wherein the one or more pulsus are configured to be delivered as an electric pulse pattern for stimulation of the organ and wherein the one or more pulses are configured to be delivered at one or more respective maxima of the waveform.

26. Method according to claim 25, wherein the one or more pulses have a predetermined pulse width, wherein preferably the pulse width is in a range of 0.05 milliseconds to 1.0 milliseconds and even more preferably in a range of 0.3 milliseconds to 0.6 milliseconds.

27. Method according to claim 25 or 26, wherein converting at least a part of the waveform to one or more of pulses comprises converting the waveform to one or more bi-phasic pulses with one or more positive deflections and one or more negative deflection.

28. Method according to claim 27, wherein an amplitude and / or a duration of the one or more positive deflections is greater than an amplitude and / or a duration of the one or more negative deflections, wherein preferably the amplitude of the one or more positive deflections is at least two times greater than the amplitude of the one or more negative deflections.

29. Method according to any of the claims 25- 28, wherein converting at least a part of the waveform to one or more of pulses comprises converting the waveform to one or more mono-phasic pulses with one or more positive deflections and no negative deflections.

30. Method according to any of the previous claims, wherein a target pacing energy is determined in dependence on one or more patient characteristics, wherein the patient characteristics are preferably one or more of: one or more congenital predisposition (i.e. genetic risk-factors), an age, one or more physical health information elements (respective other diseases; viral infections etc.), a treatment database, a gender, one or more known mental and / or physical constraints and limitations, a known exercise routines, a known sporting background, a known chemical abuse history, one or more historic pacing information, one or more historic capture success information, a mammal species type.

31. Method according to any of the previous claims, wherein the patient is a mammal and is preferably one of: a Primate, a Human, an Equidae, an Equus, a Bovine, a Canine, a Rodent, a Feline, a Peccary.

32. Method according to any of the previous claims, wherein the method further comprises applying an electric stimulation to the organ that corresponds to at least a part of the waveform.

33. System for determining an electric stimulation pattern for restoring an erratic biological signal, wherein the system comprises a pacing module configured to execute the method according to any of the previous claims.

34. Electronic device comprising a housing, a power module, one or more electrodes configured to measure an activity of an organ, a processing unit operatively connected to the one or more electrodes and configured to acquire measurements using the one or more electrodes, wherein the measurements are indicative of an action potential of an organ, wherein the processing unit is further configured to execute the method according to any of the claims 1 - 32.

35. Electronic device according to claim 34, wherein the device further comprises a stimulation module operatively connected to the power module and configured to apply an electric stimulation to the organ, wherein the electric stimulation corresponds to at least a part of the waveform.

36. Electronic device according to claim 35, wherein the stimulation module is configured to apply the electric stimulation using the one or more electrodes.

37. Electronic device according to claim 35 or 36, wherein the electric device further comprises one or more pacing wires configured to directly contact tissue of the organ and to deliver electric pulses to said organ and wherein the stimulation module is configured to apply the electric stimulation using the one or more pacing wires.

38. Electronic device according to any of the claims 34 37, wherein the electronic device is configured to be implantable.

39. Electronic device according to any of the claims 34 38, wherein the electronic device is a cardioverter defibrillator.

40. Electronic device according to any of the claims 34 39, wherein the electronic device is a cardiac pacing device, wherein the cardiac pacing device is configured to deliver pacing pulses when no frequency pattern indicative of an erratic biological signal is determined.

41. Electronic device according to any of the claims 34 - 40, wherein the processing unit comprises a programmable chip, preferably an ASIC or FPGA programmable chip.

42. Electronic device according to claim 41, wherein the processing unit comprises a plurality of ASIC and / or FPGA programmable chips, wherein each of the plurality of the programmable chips is configured to apply a distinct matched filter at least one of the at least one measurement in parallel to the other ones of the programmable chips.

43. Computer program comprising instructions which, when executed by a computer, carry out the method according to any of the claims 1 - 32.

44. Computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method according to any of the claims 1 - 32.

45. Computer-readable medium according to claim 44, wherein the instructions are programmed on a programmable chip, preferably an ASIC or FPGA programable chip.

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