System for Predicting at Least One Cardiological Dysfunction in an Individual

Abstract

A system is described for predicting at least one cardiological dysfunction in an individual, having a means for providing an ECG which has a number n of time-synchronized ECG traces, each comprising a chronological sequence of time signals representing a sinus rhythm of the individual's heartbeat, to which at least one P wave, a QRS complex and a T wave can be assigned in chronological order. A selection means selects at least two ECG traces from the n ECG traces, an analysis unit analyses the selected ECG traces as follows: a) determining an isoelectric signal level, b) determining a first point in time chronologically before the QRS complex, c) determining a second point in time chronologically after the first point in time and chronologically before the QRS complex, d) carrying out the determining steps a) to c) for all selected ECG traces, e) determining an earliest first point in time from all the first points in time determined for the respective selected ECG traces and a latest second point in time from all the second points in time determined for the respective selected ECG traces, f) determining a time interval delimited by the earliest first point in time and latest second point in time.

Claims

1.-14. (canceled)

15. A system for predicting at least one cardiological dysfunction in an individual comprising: means for preparing an ECG recording for an individual having a number n of time-synchronized ECG traces which each comprise a chronological sequence of time signals representing sinus rhythm of a heartbeat of the individual to which at least one P wave, a ventricular QRS complex and a T wave can be assigned in chronological order; a selection means for selecting at least two ECG traces from the number n of time-synchronized ECG traces based on a first decision criterion; an analysis unit which respectively analyses the selected ECG traces as follows: a) determining an isoelectric signal level based on the chronological sequences of time signals from one of the at least two selected ECG traces; b) determining a first point in time which is chronologically before the QRS ventricular complex from which time intervals of the selected at least two ECG traces have a signal level deviating from the isoelectric signal level; c) determining a second point in time which chronologically follows the first point in time and which is chronologically before the QRS ventricular complex, at which, starting from a signal level, deviates from the isoelectric signal level at which the time signal for the selected ECG trace returns to the isoelectric signal level; d) implementing the determining steps a) to c) for all of the selected at least two ECG traces; e) determining an earliest first point in time from all of the first points in time determined from the selected at least two ECG traces and a latest second point in time from all second points in time determined from the selected at least two ECG traces; and f) determining time intervals delimited by an earliest first point in time and latest second point in time corresponding to a known P wave duration; and a comparator which determines a discrepancy between a known P wave duration and a reference value and which generates a signal based on a second decision criterion.

16. The system as claimed in claim 15, wherein: the means for preparing of the ECG recording is a) a digital 12-lead ECG recording device, or is b) a storage medium in which the n ECG traces are stored in digital form, or is c) a body surface ECG recording system which has n multiple electrodes for recording electrical cardiac stimuli.

17. The system as claimed in claim 15, wherein: the means for preparing the ECG of an individual provides the n ECG traces at a scanning frequency of at least 500 Hz.

18. The system as claimed in claim 16, wherein: the scanning frequency is at least 1000 Hz.

19. The system as claimed in claim 15, wherein: the means for preparing the ECG of an individual provides n amplified ECG traces, in which the n ECG traces which are recorded for the individual are amplified by an amplification factor of at least 4 with respect to the signal level associated with the time signals.

20. The system as claimed in claim 19, wherein: the amplification factor is at least 8.

21. The system as claimed in claim 15, wherein: prior to determination of step a), the analysis unit overlays and averages time signals from a sequence of at least two sinus rhythms of a heartbeat of the individual to obtain time-synchronized time signals for each selected ECG trace which represent a sinus rhythm of the heartbeat of the individual and which form a basis for performing steps a) to f).

22. The system as claimed in claim 15, comprising: a reference time signal model of a sinus rhythm P wave forms a basis for the first decision criterion implemented by the selection means, which modeled sinus rhythm P wave is compared with the ECG traces by pattern recognition, and the selection means selects ECG traces aiding a pre-specified degree of similarity.

23. The system as claimed in claim 15, wherein: the analysis unit evaluates the selected at least two ECG traces for determining the first and second points in time by steps of: determining the first point in time at which the signal level of the time signal deviates from the isoelectric signal level to a positive larger signal level at which the time signals following a first time interval immediately adjacent to the first point in time have a positive increasing signal level; and determining the second point in time at which the time signals which lie in a second time interval adjacent to the second point in time are at the isoelectric signal level or are delimited by starting of the ventricular complex.

24. The system as claimed in claim 23, wherein: the first time interval is between 40 ms and 80 ms, and the second time interval measures at least 4 ms when the isoelectric signal level is present.

25. The system as claimed in claim 15, wherein: the means for preparing an ECG recording comprises n=12 ECG leads corresponding to 12 standard ECG leads according to Einthoven, Goldberger and Wilson as follows: I, II, III, aVR, aVL, aVF, V1-V6.

26. The system as claimed in claim 25, wherein: the second decision criterion implemented by the selection means selects from the n ECG traces based on at least one of the following criteria; and in order to determine the first point in time, at least two of the following ECG traces are taken into account: II, III, aVF, aVR, V1, V2; and in order to determine the second point in time, at least two of the following ECG traces are taken into account: II, III, aVR, aVL, aVF, V2 to V6.

27. The system as claimed in claim 15, wherein: the means for preparing the individual's ECG uses at least 3 ECG traces; and the second decision criterion implemented in the selection means selects from the 3 ECG traces based on at least one of the following criteria: determining the first and second points in time by at least two of the following ECG traces being taken into account: inferior, lateral, inferolateral, superolateral or anterior ECG traces are associated with ECG electrodes respectively applied to opposite sides of a zero potential line of a field of the heart.

28. The system as claimed in claim 15, wherein: when the second decision criterion is based on a maximum time interval Δtmax for which: 100≤Δtmax≤140 ms, and in which the determined P wave duration is more than Δtmax, the comparator generates the signal.

29. The system as claimed in claim 15, comprising: an integrator for generating an integrated value based of the first and second points in time which are chronologically delimiting of determined P wave duration over a chronological sequence of time signals within the P wave duration; and the comparator or another comparator compares the integrated value with a reference value and generates the signal based of a third decision criterion.

30. The system as claimed in claim 15, comprising: an integrator for generating an integrated value based on the first and second points in time which are chronologically delimiting of determined P wave duration over a chronological sequence of the time signals within the P wave duration; a divider for dividing a maximum or mean P wave amplitude from a P wave or a selected fraction thereof by a determined total P wave duration or a selected P wave fraction and determines a ratio thereof; and the comparator or additional comparator compares the ratio with a reference value and generates the signal based on a third decision criterion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The invention will now be described in a manner which does not limit the general inventive concept, with the aid of exemplary embodiments and by way of example with reference to the drawings, in which:

[0034] FIG. 1a shows a diagrammatic representation of a system of invention for predicting at least one cardiological dysfunction;

[0035] FIG. 1b shows the sinus rhythm of a heartbeat of an individual; and

[0036] FIGS. 2a-d shows ECG recordings, each with twelve ECG traces, each for four different individuals.

DETAILED DESCRIPTION OF THE INVENTION

[0037] FIG. 1a diagrammatically shows the conformation of the components of the system of the invention for predicting at least one cardiological dysfunction in an individual. The means 1 for the preparation of a person's or individual's ECG, typically which is in the form of a digital n-lead ECG recording device, shows the electrical stimulation potential of the person's heart which can be associated with defined spatial cardiological regions, depending on the ECG trace. Standard ECG recording devices have a total of n=12 ECG traces 2 which have the following designations according to Einthoven, Goldberger and Wilson: I, II, III, aVR, aVL, aVF, V1 to V6.

[0038] Each of the individual ECG traces 2 has digitally recorded time signals which reflect the sinus rhythm 3 of the cardiac stimuli. FIG. 1b shows the conventional morphology of a sinus rhythm 3, which is composed of a chronological sequence of at least the P wave, a subsequent QRS complex as well as a finishing T wave. The system of the invention determines the P wave duration PWD of the person highly accurately, whereupon for the first time, dependable predictions regarding the risk of stroke in a person can be made with a reliability of at least 80%. In this regard, the chronological start t1 as well as the chronological end t2 of the P wave must be determined very accurately and without errors. This provides that the means 1 for the preparation of the ECG recorded for the individual provides the n ECG traces 2 at a scanning frequency of at least 500 Hz, which is preferably at least 1000 Hz. In the case of a scanning frequency of 1000 Hz, one time signal per millisecond can be acquired. If smaller temporal resolution is required, a digital electrocardiographic recording would have to be carried out at a correspondingly higher scanning frequency. Scanning frequencies of 2000 Hz or 5000 Hz are particularly desirable.

[0039] Furthermore, advantageously, the means 1 for the preparation of a person's ECG provides the n ECG traces 2 in an amplified form, in which the n ECG traces 2 are amplified by an amplification factor of at least 4, which preferably is at least 8, with respect to the signal level associated with the time signals, both in the time axis (x axis) as well as in the voltage-amplitude axis (y axis). Additionally, the amplification of the time axis is important in order to permit exact measurements. In this regard, the time axis speed is at least 100 mm/sec and preferably 200 mm/sec.

[0040] The n ECG traces 2 which have been digitally acquired and optionally processed in the aforementioned manner using signalling technology are fed to a computer-based selection means 4 in the form of a digital data set, which selects those ECG traces 2′ from the number n of ECG traces 2 on the basis of a first decision criterion E1, by means of which a chronological determination of the respective first point in time t1 as well as the second point in time t2 which is as accurate as possible can be made.

[0041] In order to determine the first point in time t1, which defines the start of the P wave, first, the isoelectric signal level ISO has to be determined. In a time domain which is located chronologically before the QRS complex, the start of the P wave corresponds to that point in time t1 at which the signal level of the time signal is distinguishable from the isoelectric signal level ISO by a technically verifiable signal level which rises positively from the isoelectric signal level. Preferably, this technically verifiable signal level is raised above the isoelectric signal level by twice the amount of the signal level. Directly at this technically verifiable signal level which is raised above the isoelectric signal level, the chronologically subsequent time signals which lie within a first time interval Δt1 immediately adjacent to the first point in time t1 must respectively have a positive increasing or, in the case of a reverse curve profile, negative reducing signal level. Typically, the first time interval corresponds to a maximum of half the P wave duration, in which the P wave increases positively. Preferably, the first time interval should therefore be between 40 ms and 80 ms.

[0042] In order to determine the second point in time t2, the time signals lying within a second time interval which is adjacent to the second point in time t2 should return to the isoelectric time signal level ISO. The isoelectric time interval Δt2 which is adjacent to the second point in time t2 should be at least 4 ms.

[0043] Advantageously again, the metrologically detected sinus rhythm is compared with a reference time signal model or a set of reference time signal models in the context of a software-supported pattern recognition. A pattern recognition of this type recognises the typical morphology of a sinus rhythm P wave within the respective metrologically detected ECG traces. If, however, the pattern recognition leads to a negative result, then the corresponding ECG trace is not suitable for accurately determining the chronological start as well as the chronological end of the P wave. Currently, the following characteristics are considered to be morphologically relevant criteria: [0044] 1. If the P wave has a monophase negative or negative-positive deflection in the I lead, then there is no sinus rhythm present and the analysis cannot be carried out. [0045] 2. If the P wave has a monophase positive deflection in the aVR lead, then there is no sinus rhythm present and the analysis cannot be carried out. [0046] 3. If the signal to noise ratio is more than 0.2 in one of the 12 leads even after averaging at least 2-1000 beats, then no analysis can be carried out in this lead. [0047] 4. The P wave morphology is compared within each of the 12 ECG traces among the 10 (to 1000) consecutively recorded P waves. The most frequent, that is dominant repetitive P wave morphology is determined. If the P wave morphology deviates from the “dominant” P wave morphology by more than 15% in at least one lead, then these defective morphologies are not used for the analysis.

[0048] The aforementioned cases provide criteria for carrying out the analysis, respectively in the absence of the criteria described in 1 and 2, and in order to exclude leads which are not suitable for the determination of the P wave duration from the analysis.

[0049] The following P wave characteristics are associated with the presence or absence of left atrial fibrosis (left atrial cardiomyopathy): [0050] 1. No suspicion of fibrosis in the left atrium (LA) is present if the sinus P wave morphology in the inferior II, III, aVF leads is monophase positive and the P wave duration is less than 143 ms in women and less than 154 ms in men. [0051] 2. Fibrosis in the left atrium (LA) is present if the total duration of the sinus P wave from the selected leads is more than 143 ms in women and more than 153 ms in men. [0052] 3. LA fibrosis is present if the sinus P wave morphology is positive-negative in two out of three II, III, aVF leads and in fact independent of the P wave duration. [0053] 4. A pronounced LA fibrosis is present if the sinus P wave morphology has a late P component. In these cases, there is a monophase positive P wave in the II, III, aVF leads which is followed by an isoelectric interval which in turn is followed by a chronologically offset P component in two of the following leads: I, aVL, aVR, V1-V6. The total P wave duration including the late component is as a rule more than 170 ms.

[0054] The ECG traces 2′ which are selected with the aid of the selection means 4, which may comprise at least two ECG traces, however a maximum of all n ECG traces, are fed to a processor-based analysis unit 5 which analyses the ECG traces 2′ in order to accurately determine the first and second points in time t1, t2. The respective chronological start as well as the chronological end of the P wave is accurately determined for all of the selected ECG traces 2′. Because of the time-synchronicity of all of the ECG traces, the respective earliest first point in time out of all of the first points in time determined from the respective selected ECG traces as well as the respective latest second point in time out of all of the second points in time determined from the respective selected ECG traces are determined. The respective earliest first as well as the latest second point in time define the actual chronological start as well as the chronological end of the P wave and therefore determine the exact P wave duration PWD. The exact P wave duration PWD determined in the context of the analysis unit 5 is fed to a comparator 6 which determines the discrepancy between the determined P wave duration PWD and a reference value and generates a signal 7 on the basis of a second decision criterion E2. In the case in which the determined P wave duration PWD is more than a maximum predetermined time interval Δtmax, then the comparator 6 generates the signal 7. Typically, the maximum time interval Δtmax is a region between 100 and 140 ms.

[0055] FIGS. 2a to d respectively show images from twelve-lead electrocardiograms from individuals with different levels of atrial cardiomyopathies. The individual ECG traces correspond to the following standard ECG leads: I, II, III, aVR, aVL, aVF, V1 to V6.

[0056] In the context of investigations carried out by the Applicant on patients with pulmonary vein isolation (PVI), in whom despite PVI, persistent atrial fibrillation (AF) occurs, it has become clear that arrhythmogenic slower conductive sites form or have been formed within and at the boundary regions of the left atrial low voltage substrate. Thus, an advanced left atrial low voltage substrate correlates with a reduced activation rate for the left atrium, that is electrical stimulation signal propagation, which is initiated at the sinus node and which propagates over the right and left atrium in the direction of the AV node, characterized by a longer duration of the P wave duration recorded with the aid of a 12-lead ECG.

[0057] FIGS. 2a to d show respective 12-lead surface ECGs of patients which are representative of different degrees of severity as regards the formation of arrhythmogenic fibrosis-rich slower conductive sites within the left atrial low voltage substrate. Furthermore, the tops of FIGS. 2a-d show the respective signal levels for two intracardiac catheter leads which respectively mark the actual chronological end of the P wave as a reference signal.

[0058] FIG. 2a shows the ECG of a non-critical patient with a heart with no noteworthy stimulation signal propagation delays in the left atrium without regions of scarring/fibrosis. The P wave is characterized in the II, III, aVF, V2-V6 ECG leads as a P wave with a normal morphology, in the form of a positive P wave. For an exact determination of the P wave duration, in this case 133 ms, the ECG II lead is used for determining the chronological start of the P wave, i.e. the first point in time t1, and the V4 ECG lead to establish the chronological end of the P wave, i.e. the second point in time.

[0059] FIG. 2b shows an ECG of a patient with the beginning of fibrotic tissue changes in the left atrium, which on the one hand lead to a change in the developing P wave morphology, by way of a multi-peaked wave profile. See the II, III, aVF ECG leads, as well as a lengthening of the P wave duration, in this case 174 ms. In this case, for an exact determination of the P wave duration, the I & V2 ECG leads serve for the determination of the chronological start of the P wave, that is the first point in time t1, as well as the V5 ECG lead for establishing the chronological end of the P wave, that is the second point in time.

[0060] FIG. 2c shows an ECG of a patient with advanced fibrotic tissue changes in the left atrium which lead to a decreasing stimulation signal propagation and above all to only poorly detectable signals, so that in many ECG traces, the clarity of the P wave in the left atrium is not detectable or only very poorly detectable. An exact analysis of the ECG leads shows up terminal P wave fractions in the I, aVL, V3-V6 leads which are only visualizable with substantial amplification. Here, for an exact determination of the P wave duration, the V4 ECG lead served for the determination of the chronological start of the P wave, that is the first point in time t1, as well as the I ECG lead for establishing the chronological end of the P wave, that is the second point in time. In this case, the P wave duration is 172 ms.

[0061] FIG. 2d shows an ECG of a patient with very advanced fibrotic tissue changes in the left atrium. This leads to a greatly reduced and weakly developed stimulation propagation. An exact analysis of the ECG leads shows P wave fractions in the I, V5 leads which are only visualizable with substantial amplification. Here, for an exact determination of the P wave duration, the V5 ECG lead serves for the determination of the chronological start of the P wave, that is the first point in time t1, as well as the I, V4-V6 ECG leads for establishing the chronological end of the P wave, that is the second point in time. In this case, the P wave duration is 160 ms.

[0062] The foregoing examples illustrate the difficulty and hence established necessity of accurately determining the P wave duration. As an example, in the case of a patient with an ECG in accordance with FIGS. 2c and 2d, a determination of the chronological end t2 of the P wave which was chronologically too early would lead to a seriously erroneous diagnosis, especially in those cases where time signals characterized by a low signal level chronologically after the monophase P wave configuration are not observed during a surface analysis, and so the P wave duration would be determined as being too short. In such a case, the diagnosis for the patient would be completely wrongly assessed as being of no risk to the health.

[0063] In the context of the digital signal evaluation on the basis of the analysis unit of the invention, which accurately evaluates the signal level of the time signals on signal level variations in the region of twice the signal level compared with the isoelectric signal level, atrial cardiac activities associated with the P wave can be accurately detected and be used as a basis for establishing the chronological end of the P wave.

LIST OF REFERENCE NUMERALS

[0064] 1 means for providing an ECG for an individual [0065] 2 ECG trace [0066] 3 sinus rhythm of a heartbeat [0067] 4 selection means [0068] 5 analysis unit [0069] 6 comparator [0070] 7 signal [0071] 2′ selected ECG traces [0072] E1 first decision criterion [0073] E2 second decision criterion [0074] PWD pulse wave duration [0075] ISO isoelectric signal level [0076] t1 first point in time [0077] t2 second point in time [0078] Δt.sub.1 first time interval [0079] Δt.sub.2 second time interval