Method and device for monitoring and optimizing a temporal trigger stability by means of a p-wave and / or t-wave

Abstract

The present invention relates to devices for monitoring and optimizing a temporal trigger stability of an extracorporeal circulation support means and also open-loop and closed-loop control units for extracorporeal circulation support means comprising such a device and corresponding methods. Accordingly, a method is proposed for monitoring and optimizing a temporal trigger stability of an extracorporeal circulation support means, comprising the following steps: receiving an ECG signal from a supported patient over a given time period; determining P-waves, R-waves and T-waves from the received ECG signal; and determining a given trigger signal from the ECG signal of a current cardiac cycle, taking account of at least one detected P-wave and / or at least one detected T-wave.

Description

[0001] Applicant:

[0002] Xenios AG

[0003] Offenburg University of Applied Sciences

[0004] Method and device for monitoring and optimizing temporal trigger stability using P- and / or T-wave

[0005] Technical area

[0006] The present invention relates to methods for monitoring and optimizing a temporal trigger stability of extracorporeal circulatory support and corresponding devices.

[0007] State of the art

[0008] To stabilize a patient's condition in the event of failure of the heart's pumping capacity or pumping function, extracorporeal circulatory support systems have been developed that provide mechanical support. They can be quickly connected to the circulatory system. They can improve blood flow and perfusion to the organs, including the coronary arteries, and prevent a hypoxic state. For example, a blood pump can be connected to a venous access via a venous cannula and to an arterial access via an arterial cannula for aspirating or pumping blood. Blood flow can be provided from one side with a low pressure, for example via an oxygenator, to a side with a higher pressure, thereby supporting the patient's circulation.

[0009] To control extracorporeal support, measurement signals from an electrocardiogram (ECG) can be recorded and used, allowing characteristic amplitudes to be determined for different phases of the cardiac cycle. For example, an R-wave characteristic of the systolic phase of the cardiac cycle can usually be easily distinguished from other phases of the cardiac cycle. The R-wave can be used in the form of an R-trigger and with a predetermined latency to control a blood pump in a successive diastolic phase.

[0010] Extracorporeal circulatory support can be provided for both spontaneous and paced cardiac rhythms. Paced cardiac rhythms can involve excitatory electrical stimulation of the heart using a pacemaker (PM), implantable cardioverter / defibrillator (ICD), cardiac resynchronization therapy (CRT), or non-excitatory electrical stimulation of the heart using cardiac contractility modulation (CCM), as well as a combination of excitatory and non-excitatory electrical stimulation of the heart. In all cases, cardiac arrhythmias can occur during the support period, which can affect the ECG signal. For example, atrioventricular conduction disturbances, ventricular bundle branch blocks, or even bradycardic or tachycardic phases of the cardiac rhythm can distort the ECG signal to such an extent that an electrophysiological or pathophysiological change occurs in the ECG signal.This can significantly alter the ECG signal pattern. Detection of an R wave, which is necessary for circulatory support, can thus be impaired or even made more difficult.

[0011] Accordingly, uncertainty regarding correct detection may arise, particularly if the R-wave is not clearly visible in the ECG signal and / or cannot be clearly detected due to the fixed parameters. Consequently, an R-wave may not be detected or may be detected at a time that does not coincide with the actual physiological time of ventricles depolarization. This significantly compromises extracorporeal circulatory support, as a support pulse may not be delivered at all or at the intended time during the diastolic phase of the heart.

[0012] Furthermore, stimulation-related disturbances in the ECG signal can occur if cardiac stimulation is planned for the patient in addition to extracorporeal circulatory support. Stimulation pulses can be delivered, for example, within the QRS complex of a given cardiac cycle, possibly with different stimulation amplitudes, stimulation pulse durations, and stimulation forms, including multiple positive and negative stimulation pulses. In this case, a corresponding R-wave cannot be detected, or an amplitude change in the ECG signal is inadvertently detected as an R-wave. Even in these cases, extracorporeal circulatory support cannot be provided with the desired stability required by the patient.Accordingly, there is a need to improve the verification of the temporal trigger stability of extracorporeal circulatory support, preferably under different physiological and / or clinical conditions, and to optimize the temporal electrical trigger stability during circulatory support.

[0013] Based on the known prior art, it is an object of the present invention to enable improved testing and optimization of the temporal trigger stability of extracorporeal circulatory support.

[0014] The problem is solved by the independent claims. Advantageous further developments emerge from the subclaims, the description, and the figures.

[0015] Accordingly, a method for monitoring and optimising a temporal trigger stability of extracorporeal circulatory support is proposed, comprising the steps:

[0016] Receiving an ECG signal from a supported patient over a specified period of time;

[0017] Determining P-waves, R-waves, and T-waves from the received ECG signal; and

[0018] Determining a predetermined trigger signal from the ECG signal of a current cardiac cycle taking into account at least one detected P wave and / or at least one detected T wave.

[0019] Typically, for extracorporeal circulatory support systems, only one R-wave or R-wave is recorded from each cardiac cycle. At most, an additional signal from the QRS complex encompassing the R-wave is detected. As previously described, this results in uncertainty regarding the correct detection of an R-wave, particularly in the event of cardiac arrhythmias that affect the ECG signal. For example, an R-wave may be recorded at the wrong time. In this case, an amplitude change is recorded that physiologically does not correspond to the R-wave. Or, no R-wave may be detected in the ECG signal. Furthermore, two R-waves may be recorded with only one ventricular depolarization, for example, with a pronounced delta wave at the beginning of the QRS complex in Wolff-Parkinson-White syndrome and intermittent right and left bundle branch blocks.As a result, control of extracorporeal circulatory support cannot be ensured with the desired reliability and precision.

[0020] By considering an additional P wave and / or T wave, the invention takes another factor into account when determining the trigger signal, significantly improving the reliability and precision of correctly detecting the trigger signal. For example, a successive sequence of a P wave, R wave, and T wave within a cardiac cycle already indicates that the R wave was detected between the P wave and the T wave. In this case, it can be ruled out that an artifact, i.e., a wave outside the PT time interval, is mistakenly interpreted as an R wave.

[0021] Furthermore, the detection of a P wave, for example, allows one to conclude that atrial depolarization has occurred. An additional and inverted P wave after an R wave, for example during ventricular stimulation, can be used to infer retrograde conduction between the ventricle and atrium. However, an inverted P wave before an R wave can indicate a left atrial heart rhythm with possible sinus bradycardia. Atrial fibrillation, in which a P wave is typically not detected, can usually be ruled out. If a P wave can be detected, it can be assumed that a detected R wave was triggered due to conduction in the AV node. It cannot therefore be assumed that a signal detected as an R wave was triggered by an escape rhythm.

[0022] Recording the T wave can also serve to confirm a previous excitation. The detection of a T wave and two R waves in one cardiac output can indicate bundle branch blocks due to a widening of the QRS complex, for example, due to a pronounced delta wave, and can lead to so-called "double counting." 1 For example, in the absence of a T wave but with the detection of an R wave, an ineffective right and / or left ventricular pacing pulse may be present. In this case, the detected R wave does not correspond to ventricular depolarization. In such cases, the R wave should not be used as a trigger signal.

[0023] Conversely, a T wave determined for the current cardiac cycle can, for example, confirm the validity of a trigger signal determined as a P wave or, in particular, as an R wave. For example, an R wave can initially be determined as a trigger signal, but this can only definitively serve as a trigger signal if a (normal) T wave has been successively determined in the current cardiac cycle. In such a case, a delay time for an actuation signal for extracorporeal circulatory support can be defined based on the R wave, for example to activate a blood pump in a subsequent diastolic phase, whereby the actuation signal can accordingly only be output if the T wave was detected in the current cardiac cycle. In particular, the actuation signal can then be output immediately after the T wave or, alternatively, already when a slope is detected at the beginning of a T wave.Alternatively, the T wave itself can be determined as the trigger signal, for example, if a P wave and / or R wave were previously determined in the current cardiac cycle and a corresponding delay time after the P wave or R wave for the actuation signal coincides with the T wave. This allows, for example, the actuation of a blood pump for extracorporeal circulatory support to coincide directly with the beginning of the diastolic phase or the end of the systolic phase.

[0024] In this way, trigger stability can be automatically optimized and, if necessary, adjusted based on the detected P wave and / or T wave, for example, by adjusting the control / regulation of circulatory support accordingly. Any variability in the EKC signal can be detected and taken into account based on the detected P wave and / or T wave. If it is determined that no trigger signal could be determined, or if it is determined based on the detected P wave and / or T wave that a specific trigger signal may be faulty, a corresponding signal or warning signal can be output.

[0025] However, if the detected P wave and / or T wave confirms that the trigger signal can be determined or that a correct trigger signal has been determined, an actuation signal and / or control signal for extracorporeal circulatory support can be output based on the trigger signal, preferably with a predefined delay time. It can also be specified that input or confirmation can be requested from medical personnel.

[0026] The predetermined period of time can be defined in particular by the treatment duration or a (periodic) portion of the treatment duration, so that the ECG signal is preferably received continuously during treatment of the patient. The period of time can also comprise at least the current cardiac cycle and at least one previous cardiac cycle, preferably at least two to five previous cardiac cycles. The received ECG signals can be buffered in particular for a predetermined number of cardiac cycles, for example in a working memory, in order to facilitate the determination of the trigger signal and / or any necessary evaluation of the ECG signal. In this case, a sliding buffering of successive cardiac cycles can be provided, so that the current cardiac cycle and the predetermined number of previous cardiac cycles are always continuously available.The P wave and / or the T wave can be recorded for the current cardiac cycle and / or for at least one previous cardiac cycle, preferably at least or exclusively the immediately previous cardiac cycle.

[0027] Preferably, the P wave is recorded at least for the current cardiac cycle. This also enables immediate confirmation or adjustment of the trigger signal to be determined for the current cardiac cycle. In other words, high-resolution temporal monitoring and, if necessary, adjustment of the trigger signal to be determined can be provided. As described above, a T wave for the current cardiac cycle can also provide feedback with regard to an already determined or emitted trigger signal. For example, this can be achieved by an end of the T wave that coincides with the end of the systolic phase or the beginning of the diastolic phase, indicating a time of potential administration of a support pulse. In this way, it can be determined, for example, whether the trigger signal was recorded at the correct time or whether a delay time for the support pulse was correctly set.

[0028] Alternatively or additionally, a P wave and / or a T wave can also be recorded for one or more previous cardiac cycles. This allows any changes in the ECG signal curve to be detected before the current cardiac cycle. This further improves the accuracy of P wave and T wave recording and the determination of the trigger signal for the current cardiac cycle. Changes in the T wave for the current cardiac cycle can also be taken into account in this way. If a T wave (and / or P wave) is absent from a previous cardiac cycle, for example, a warning signal can be issued.

[0029] Accordingly, it can be provided that the P wave is determined at least for the current cardiac cycle and a T wave is determined at least for the immediately preceding cardiac cycle. In this way, it can be determined from the previous cardiac cycle whether a planned repolarization or a normal course of the previous cardiac cycle has taken place. Furthermore, this ensures that there is no fusion of the P wave of the current cardiac cycle with the preceding T wave. In this way, for example, the validity of a specific P wave and / or a subsequently determined R wave can be improved or confirmed, so that the P wave or R wave of the current cardiac cycle can be determined as the trigger signal.

[0030] Furthermore, by detecting a microvolt T-wave alternans over multiple cardiac events using T-wave signal averaging, ventricular repolarization can be determined and monitored, and used to optimize the assist pulse. This allows trigger problems during ST-segment elevation or depression to be detected and eliminated.

[0031] In addition to recording P-waves, R-waves, and T-waves in the time domain, learning-based methods of biosignal processing and biosignal analysis can be applied using a machine learning model such as linear regression, support vector regression, neural network, support vector machine, nearest neighbor, feed-forward neural network (FFNN), recurrent neural network (RNN), and long short-term memory (LSTM). This can further increase temporal trigger stability during extracorporeal circulatory support. With the learning-based methods, statistical parameters such as mean, median, standard deviation, percentile, skewing, and kurtosis can be determined. Furthermore, parameters in the frequency domain for the P-wave, T-wave, and R-wave can be determined.

[0032] The ECG signal corresponding to the respective P wave and / or T wave can be statistically evaluated and, for example, averaged or standardized for the corresponding cardiac cycles. This allows minor changes in the ECG signal curve to be given less weight. It can also be planned that the P wave and / or T wave, for example, be recorded (exclusively) for an immediately preceding cardiac cycle. This allows any variations in the ECG signal to be taken into account in real time for the current cardiac cycle – similar to recording for the current cardiac cycle.

[0033] Preferably, the trigger signal is determined based on a PR time interval between the P wave and the R wave of a respective cardiac cycle. The determination of the predefined trigger signal and / or the predefined trigger signal to be determined can be adjusted if a threshold value predefined for the PR time interval is exceeded. In other words, if the threshold value is exceeded, the type of acquisition can be adjusted, for example by adjusting parameters for the acquisition such as minima, maxima, gradients, and / or time intervals for the predefined trigger signal, for example the R wave. Likewise, the predefined trigger signal to be determined itself can be adjusted so that, for example, instead of a previously determined R wave for the current cardiac cycle or the subsequent cardiac cycle, a P wave or T wave is to be determined as the trigger signal.The type of amplitude change characteristic of a cardiac cycle phase, which is to be determined as a trigger signal, can be adjusted accordingly. As described above, the detection of a P-wave alone can be advantageous. For example, atrial fibrillation can be diagnosed or regularly ruled out. Furthermore, it can be determined whether atrial fibrillation occurs intermittently. Accordingly, any escape rhythm and the associated lower heart rate can be taken into account. Furthermore, an analysis of the morphology of the P-wave can help distinguish between, for example, sinus rhythm and left atrial rhythm, as well as retrograde conduction between the ventricle and atrium.

[0034] However, the PR time interval can also be used to detect other cardiac pathologies affecting excitation, such as atrioventricular conduction disturbances, ventricular bundle branch blocks, and / or additional conduction pathways between the atrium and ventricle, known as Kent pathways, with increased reliability. Exceeding the corresponding threshold may indicate atrioventricular block. If the corresponding threshold is undercut, a patent Wolff-Parkinson-White syndrome (WWP syndrome) with additional antegrade conduction between the atrium and ventricle via a Kent fiber may be present, causing a change and lengthening of the QRS complex. Furthermore, a combination of maximum pre-excitation of the QRS complex via the Kent fiber and a Mahaim fiber, which may lie between the atrioventricular node (AV node) and right ventricular myocardium, can alter the electrocardiographic time intervals.A prolonged PR interval can, on the one hand, cause the P wave to merge with the preceding T wave. This can make it more difficult to detect the P wave or the T wave without appropriate adjustment of the detection. On the other hand, such a prolongation of the PR interval can also be accompanied by a broadening or electrophysiological change in the QRS complex. This can mean that an R wave may not be detected. However, if the R wave is to be determined as a trigger signal, the prolongation of the PR interval can be associated with a reduced stability of the trigger signal. Taking the PR interval into account is also advantageous because the PR-R interval describes the beginning of the systolic phase of the cardiac cycle. If a prolongation of the PR interval orIf the corresponding threshold is detected, a different trigger signal, such as a P wave instead of the previously determined R wave, can be specified for the current cardiac cycle, or at least for the subsequent cardiac cycle, to ensure the desired trigger stability. The PR time interval is specified above and below as a criterion. Alternatively, a PQ time interval can also be considered in the event that the Q wave is to be (clearly) recorded in the ECG signal in addition to the R wave.

[0035] Preferably, the detection of the P wave, R wave, and / or T wave for the current cardiac cycle is adjusted as soon as a predefined threshold for the PR time interval is exceeded for at least one previous cardiac cycle. As described above, if the PR time interval is prolonged, the P wave may merge into the T wave. Detection of the P wave and / or T wave may be more difficult. A widening of the QRS complex or an electrophysiological change in the QRS complex may also be present. For example, the amplitude of the R wave may be reduced, or the R wave may even be absent. Adjusting the detection allows the detection for the current cardiac cycle to be adapted to the cardiac disease pattern.

[0036] The acquisition can be adjusted, for example, to allow for different slope values ​​or acquisition times to be recorded. A respective bandpass filter can also be changed. An alternative ECG lead can be selected for the respective acquisition. The ECG lead can, for example, be spatially and / or anatomically separated from the previously used ECG lead. Furthermore, multiple ECG leads can be considered for signal optimization. The corresponding ECG signals can be processed using "signal averaging," for example, and preferably averaged.

[0037] The threshold for the PR time interval is preferably at least 120 ms, particularly in the absence of antegrade conduction via a Kent pathway. The threshold for the PR time interval is shortened to as little as a few milliseconds with antegrade conduction via the Kent pathway. The end of the P wave and the beginning of the QRS complex can also be superposed with a 0 ms RQ time interval. A threshold for the PR interval with antegrade conduction via the Kent pathway is preferably between 0 and 120 ms, depending on the severity of the delta wave and the selected ECG lead. In this way, it can be determined whether the PR time interval is highly likely to be non-physiological and, for example, corresponds to a first-degree AV block. The threshold for the PR time interval is preferably between 150 ms and 400 ms; in particular, the threshold can be between 200 ms and 300 ms.Such a threshold may, for example, correspond to first-degree or second-degree AV block. If the threshold is exceeded, a change in the QRS complex and impaired R-wave detection may be present. Analysis of the PR intervals and P-wave morphology can be used to evaluate 1° AV block, 11° type 1 "Wenckebach" AV block, 11° type 2 "Mobitz" AV block, and 1IP AV block, as well as sinus atrial block. Such atrioventricular biosignal analysis can further support the temporal stability of R-triggering.

[0038] Without atrioventricular conduction disturbances and without antegrade conduction between the atrium and ventricle via an additional Kent pathway, the PQ interval can be in the range of 120 ms to 200 ms, and the threshold can be selected accordingly. The threshold can also depend on the cardiac cycle duration and / or the heart rate. At a higher heart rate in the physiological state, a shorter PQ interval is to be expected. Accordingly, the threshold for the PQ interval can correspond to at least 20 percent of the cardiac cycle duration, preferably at least 30 percent or at least 35 percent. The threshold for the PQ interval can, for example, be less than 200 ms, but should be higher than the respective patient-specific (patho)physiological value, in particular, it should be at least 10% higher than the patient's (patho)physiological value (e.g.180 ms compared to a (patho)physiological patient value of 160 ms). Possible changes in the PR time interval due to a bradycardic or tachycardic state can be taken into account in this way.

[0039] During ventricular pacing with pacemakers, retrograde conduction from the ventricle to the atrium can also occur, generating an additional P wave with altered P wave morphology, for example, P wave inhibition. This retrograde P wave can particularly influence the pacing behavior of a dual-chamber pacemaker and R-triggering. The RP time interval with a retrograde conduction time of, for example, 200 ms to 300 ms can lead to premature ventricular pacing and thus to a tachycardic heart rhythm with corresponding effects on hemodynamics and fluctuating RR time intervals. The detection of P waves and determination of PR and RP intervals thus advantageously enables the evaluation of intermittent or permanent retrograde conduction between the ventricle and atrium to optimize the temporal stability of R-triggering.

[0040] For example, to give less weight to individual, rare, and / or less prominent "outliers," the PR time interval and / or RP time interval can also be averaged for at least two cardiac cycles. The time intervals between the respective P waves and R waves of the respective cardiac cycles are averaged accordingly, so that at least two PR time intervals (RP time intervals) are averaged. Preferably, PR time intervals and / or RP time intervals of successive cardiac cycles are averaged. For example, a mean with a standard deviation can be determined for several cardiac cycles, or a median can be determined based on a histogram. An adjustment of the acquisition and / or the trigger signal to be determined can thus only be made, for example, if the mean, standard deviation, or median exceeds a corresponding statistical threshold.Advantageously, this means that minor and / or temporary changes do not immediately trigger a corresponding parameter adjustment. Any impact on circulatory support resulting from such an adjustment can be adjusted accordingly.

[0041] However, the number of PR and / or RP intervals to be averaged can be kept low, for example, limited to two to five cardiac cycles. Only when the threshold is exceeded can it be validated whether a pathological change and / or retrograde conduction from the ventricle to the atrium is actually present. Nevertheless, rapid adjustment of the acquisition and / or the trigger signal to be determined can be provided.

[0042] Preferably, the PR time interval and / or RP time interval are compared for at least two successive cardiac cycles. The determination of the predefined trigger signal and / or the predefined trigger signal to be determined can be adjusted with a successive extension of the PR time interval and / or RP time interval.

[0043] A gradual prolongation of the PR interval can occur, for example, due to a Wenckebach block. A gradual prolongation of the RP interval can occur, for example, due to retrograde Wenckebach behavior. For example, the PR interval can be prolonged for two to three consecutive cardiac cycles. Under such circumstances, conduction fails; an R wave or ventricular excitation does not occur. In the case of a Wenckebach block, for example, every second or every third P wave can be conducted. This pathophysiology can mean that the R wave should be omitted and the P wave can be used as a trigger signal instead.

[0044] Such a successive prolongation can occur in particular if the corresponding threshold is also exceeded. The prolongation can be determined, for example, based on an absolute difference value or in relation to the previous cardiac cycle. For example, the prolongation can be 50 ms to 100 ms and / or at least 20 percent. The trigger signal can alternatively or additionally be determined based on an RT time interval between an R wave (or several P waves in the case of retrograde conduction between the ventricle and atrium) and a T wave of a respective cardiac cycle. Preferably, the determination of the predetermined trigger signal and / or the predetermined trigger signal to be determined is adjusted when a threshold value predetermined for the RT time interval is exceeded.

[0045] Considering the RT interval, or analogously the QT interval, also allows for the detection of cardiac disorders affecting excitation, such as ventricular reversal disorders with and without bundle branch blocks, with increased detection reliability. For example, a prolongation of the RT interval can occur due to a fusion of the T wave with a successive P wave and / or due to a widening of the QRS complex. These changes in the QRS complex can be caused, for example, by additional conduction pathways between the atrium and ventricle, so-called antegrade conducting Kent pathways. The Kent pathways can lie in the valve plane of the right and / or left heart and conduct continuously or intermittently antegrade or retrograde.With antegrade conduction via, for example, a left cardiac lateral Kent pathway, the so-called delta wave occurs, with corresponding widening of the QRS complex and a shortening of the PR interval. In Wolff-Parkinson-White syndrome, the so-called WPW syndrome, the additional antegrade conduction via the Kent pathway leads to premature excitation of the left ventricle with a widening of the QRS complex. A detected shortened PR interval may indicate a patent WPW syndrome with a widening of the QRS complex.

[0046] Exceeding the threshold for the RT time interval can serve as an indicator of a pathological condition and, for example, enable early adjustment of the acquisition and / or the trigger signal to be determined. Trigger stability can therefore be significantly improved even in the event of cardiac arrhythmias. As described above, the acquisition and consideration of the T wave can not only improve trigger stability per se, for example, by allowing for verification of excitation. It also enables the RT time interval to provide more precise adjustment of the trigger signal to a given pathophysiological condition.

[0047] In some heart diseases or cardiac arrhythmias, a shortening of the T wave can occur. Although the threshold preferably represents an upper time limit, it can also include a lower time limit. For example, the threshold can be defined by a range that should normally neither be exceeded nor undercut. Preferably, the detection of the P wave, R wave, and / or T wave for the current cardiac cycle is adjusted if a predefined threshold for the RT time interval is exceeded in at least one previous cardiac cycle.

[0048] The T wave occurs at the end of the systolic phase and is located after the P wave and R wave. This allows for optimized detection for a subsequent cardiac cycle. For example, if the RT interval is extended, a P wave from a current cardiac cycle may merge into the T wave of the immediately preceding cardiac cycle. Accordingly, more precise detection of the P wave may be necessary, for example, by changing a parameter, such as a predefined frequency range for the P wave.

[0049] Preferably, the threshold for the RT time interval is at least 350 ms. Similar to the described PR time interval, this allows non-physiological RT time intervals, which may require an adjustment of the acquisition and / or the trigger signal to be determined, to be detected and taken into account.

[0050] The threshold for the RT time interval can also be set to at least 450 ms. In this way, the occurrence of certain types of cardiac arrhythmias, for example in the case of AV block, can be detected and taken into account when determining the trigger signal. As described above for the PR time interval, the threshold can also depend on the cardiac cycle duration and / or the heart rate. It should be noted that with a higher heart rate in the physiological state, a shorter QT time interval and a correspondingly shorter RT time interval can be expected. Thus, the threshold for the RT time interval can correspond to at least 35 percent of the cardiac cycle duration, preferably at least 40 percent or even at least 45 percent.

[0051] The RT time interval can be averaged for at least two cardiac cycles, as described above with regard to the PR time interval.

[0052] Therefore, simply detecting the T wave can enable monitoring of the current cardiac cycle. The RT time interval also allows for the detection of potential pathophysiological changes. Furthermore, the T wave profile can also be taken into account, for example, to detect cardiac arrhythmias. Thus, the determination of the predefined trigger signal, the predefined trigger signal to be determined, and / or the detection of the P wave, R wave, and / or T wave for the current cardiac cycle can be preferentially adjusted if the amplitude of the T wave has a negative value for at least one previous cardiac cycle or is negative overall. In particular, this can provide adjustment for a subsequent cardiac cycle. If the amplitude is negative or significantly flattened, this finding may be an indication of bundle branch block of the cardiac conduction system.

[0053] Preferably, the trigger signal is determined based on a QRS time interval between a Q wave and an S wave of a respective cardiac cycle. The determination of the predetermined trigger signal and / or the predetermined trigger signal to be determined can be adjusted if a threshold value predetermined for the QRS time interval is exceeded. Alternatively or additionally, the detection of the P wave, R wave, and / or T wave for the current cardiac cycle can be adjusted if a threshold value predetermined for the QRS time interval is exceeded for at least one previous cardiac cycle.

[0054] Due to cardiac arrhythmias, and particularly in the case of an atrioventricular bundle branch block, for example, the QRS complex may become broadened or lengthened, or the ECG signal waveform within the QRS complex may be significantly altered. For example, the R wave may not occur or may occur with a significantly lower amplitude than usual. If the threshold for the QRS time interval is exceeded, this circumstance – for example due to a bundle branch block – may prevent the determination of a trigger signal within the QRS complex, such as an R wave. In such a case, an alternative amplitude change, preferably a P wave, can be determined as the trigger signal. Any parameter values ​​required for the recording can also be adjusted to optimize the recording for subsequent cardiac cycles.For example, a frequency range set for the detection of the QRS complex can be adjusted and / or a lower threshold can be set for the detection of an R-wave.

[0055] The threshold for the QRS interval is preferably at least 120 ms. This allows physiological values, particularly those between 90 ms and 110 ms, to be excluded and a cardiac arrhythmia to be detected or confirmed.

[0056] The PR time interval, RT time interval, or QRS time interval described above can each individually improve trigger stability and thus extracorporeal circulatory support. However, at least two of these time intervals are preferably taken into account when determining the trigger signal. In this way, any cardiac arrhythmia can be detected more accurately and even anticipated for the control / regulation of extracorporeal circulatory support. The PR time interval, RT time interval, and QRS time interval are preferably taken into account in combination. The time intervals can preferably together form an ECG signature. The detection of the P wave, R wave, and T wave and the determination of the respective time intervals are carried out automatically, for example, by computer-implementing the method.The method can be executed by a processor of an ECG device or by a control unit for extracorporeal circulatory support. In this way, adjustments to the acquisition can be made automatically, provided, or suggested. Trigger stability can thus be continuously monitored and improved.

[0057] A threshold value for one or more time intervals within a given cardiac cycle and / or the specified trigger signal can be based on a pathological ECG signature. For example, a threshold value for a PR interval can be specified for a cardiac arrhythmia, such as in the case of a first-degree AV block. Under such circumstances, it can also be provided that, for example, a P wave is defined as the trigger signal instead of an R wave. The pathological signature characteristic of a specific cardiac condition can thus, if necessary, specify an ECG signal profile or the duration of one or more specific time intervals.

[0058] The pathological ECG signature can be predefined and / or determined for the current cardiac cycle based on time intervals recorded in previous cardiac cycles. For example, a pathological ECG signature can be preset for extracorporeal circulatory support of a patient, allowing trigger stability for circulatory support to be optimized initially. For example, the ECG signal of the supported patient can be compared with the preset pathological ECG signature using appropriate threshold values ​​for specific time intervals, such as the PR time interval.

[0059] However, the pathological ECG signature can also be determined based on the ECG signals from previous cardiac cycles. Corresponding thresholds can be determined by online analysis of the ECG signals during a current circulatory support session, for example, using statistical evaluation and learning-based methods in the time and frequency domain. For example, time intervals, such as the PR time interval and / or the RT time interval, of successive cardiac cycles can be recorded and determined as a histogram, mean, or median with standard deviations or percentiles, as well as skewness and kurtosis (kurtosis).

[0060] For example, ECG signals can be evaluated online during an ongoing extracorporeal circulatory support and optionally used for learning-based methods. The ECG signal can be received immediately after acquisition and preferably continuously. The initially acquired data can be validated and annotated during the acquisition of the ECG signal and the extracorporeal circulatory support. They can then be used to determine one or more threshold values ​​for successive cardiac cycles. The evaluation or analysis of the data can also be carried out at a later time or with a delay during the extracorporeal circulatory support in order to achieve a "near-line" 1 ' analysis. Learning-based methods can include linear regression, support vector machine (SVM), artificial neural network, feed-forward neural network (FFNN), recurrent neural network (RNN), and long-term memory (LSTM).

[0061] The ECG signal and the corresponding data can be buffered at least partially or completely, preferably for a predefined time period. In this way, for example, an evaluation unit can take the patient's own ECG signal into account when determining the trigger signal and / or a respective threshold value. This can increase or improve the accuracy of monitoring and, if necessary, the placement of the trigger signal.

[0062] Furthermore, a trigger signal to be determined can be specified based on the previous cardiac cycles. For example, a P-wave or an R-wave can be specified as the trigger signal, provided that the recorded PP time intervals or RR time intervals could be recorded consistently and with little deviation in a minimum number of (possibly consecutive) cardiac cycles.

[0063] Determination of the pathological ECG signature based on previous cardiac cycles may also be provided in addition to a preset ECG signature in order to advantageously enable monitoring of trigger stability immediately after determination and, at the same time, immediate adaptation to patient-specific circumstances.

[0064] Finally, the time intervals recorded from the previous cardiac cycles can also be compared with an offline evaluated dataset containing ECG signals from supported patients who have a pathological finding common to the patient being treated. The ECG signature that shows the best possible match with an ECG signal from the dataset can be specified as a parameter, whereby learning-based methods can also be used to determine the match.

[0065] The offline stored dataset can, for example, be annotated for the P waves, R waves, and T waves to improve the accuracy of the recorded time intervals. Using the annotated data, statistically optimized thresholds can be specified for the time intervals used, corresponding to the respective pathology. Alternatively or additionally, suitable frequency ranges for the P waves, R waves, and T waves and / or suitable amplitude values ​​can be specified, so that a comparison of the patient's ECG signal with the dataset enables increased agreement.

[0066] For each cardiological pathology, a time interval range, frequency range, and / or amplitude range and / or a trigger signal to be determined within a defined time interval, e.g., the RT time interval, can be specified. The time interval used can be selected, in particular, from the PR time interval, the RT time interval, and / or the QRS time interval.

[0067] To improve the accuracy of detecting amplitude changes in the ECG signal, the P wave, R wave, and / or T wave can be detected after passing through a bandpass filter. The frequency range for the P wave is preferably between 5 Hz and 20 Hz, for the R wave preferably between 10 Hz and 25 Hz, and / or for the T wave preferably between 1 Hz and 5 Hz. The invention has recognized that the detection of the respective amplitude changes can be significantly improved by processing the ECG signal using the aforementioned frequency ranges. Should the detection need to be adjusted during the course of circulatory support, for example, due to a threshold value being exceeded for a specific time interval within the cardiac cycle, one or more frequency ranges provided for detection can be adjusted accordingly.

[0068] To control / regulate extracorporeal circulatory support, an R-wave or R-peak is typically determined from the respective cardiac cycle to serve as a suitable trigger signal. As described above, under certain pathophysiological conditions, the detection of the R-wave, for example, may occur at the wrong time or may even be prevented, for example, if a different amplitude change than the R-wave is detected. Such circumstances can also occur, for example, if the patient's heart is stimulated and the stimulus causes an artifact in the ECG signal. Therefore, an R-wave may not provide the desired or required trigger stability for extracorporeal circulatory support in certain cardiac conditions.

[0069] In such a case, the predefined trigger signal may indeed be an R-wave. By taking into account the at least one detected P-wave and / or the at least one detected T-wave, a P-wave or a T-wave, an alternative or additional trigger signal can be selected. The R-wave can therefore be preset as the trigger signal. However, the trigger signal can be adjusted, for example, if a threshold value for a PR time interval is exceeded. This allows a P-wave, for example, to be used as the trigger signal for at least one subsequent cardiac cycle. In this way, it can be ensured that a trigger signal can be determined and used with sufficient stability even in the event of distortions or changes in the ECG signal.

[0070] The use of the P wave also has the advantage that the trigger signal can be adapted to the current cardiac cycle, for example, based on the PR interval of the current cardiac cycle. The P wave and the PR interval do not collide or overlap with a subsequent diastolic phase. A trigger signal can be algorithmically provided or output with a suitably predefined delay time to control / regulate extracorporeal circulatory support during a subsequent diastolic phase. This is achieved even if an R wave could not be detected or could not be detected with sufficient reliability.

[0071] Preferably, based on the determined trigger signal, a signal for extracorporeal circulatory support is output with a delay time. The delay time can be specified taking into account the at least one detected P wave and / or the at least one detected T wave.

[0072] The circulatory support signal can, for example, be a control / regulation signal for extracorporeal circulatory support, such as for a blood pump. For example, the delay time can be adjusted if the PR time interval and / or a QRS time interval are prolonged. This ensures that the signal is not inadvertently delivered during an unintended cardiac cycle phase. Adjusting the delay time can potentially prevent the extracorporeal circulatory support from delivering a support pulse during a systolic phase of the cardiac cycle.

[0073] Furthermore, it can also be provided that the delay time is automatically adjusted or automatically suggested depending on the trigger signal to be determined. This procedure can be advantageous, for example, if the trigger signal to be determined is changed, for example a P wave is determined instead of an R wave. A predetermined delay time may no longer be sufficient to prevent superimposition or intersection with a systolic phase, so the delay time must be adjusted. In this case, an R-wave-based delay time can be extended, for example, by the PR time interval or alternatively by a PQ time interval. If neither a Q wave nor aIf neither a P wave nor an R wave could be detected, the delay time can be adjusted in the event of disturbances in excitation and / or conduction and / or stimulation of the heart, for example, by incorporating a hemodynamic sensor. Complex electrical and hemodynamic cardiac situations can arise that require adjustment of the delay time, which can be influenced in particular by the electromechanical coupling. For example, electromechanical decoupling of the heart results in electrical excitation of the heart without mechanical contraction of the heart. However, the hemodynamic sensor can provide another alternative or a redundant system to enable optimized triggering even in such cases.

[0074] The delay time for the current cardiac cycle can also be determined from a recorded QT interval from at least one previous cardiac cycle. The QT interval can be normalized using a heart rate determined from the ECG signal.

[0075] The QT interval corresponds to the period of the cardiac cycle from the beginning of the Q wave of the QRS complex to the end of the successive T wave. The time of the end of the T wave physiologically corresponds to the closure of the aortic valves and marks the end of systole or the beginning of diastole. Taking the QT interval into account proves advantageous because, according to a rule of thumb, this interval also roughly corresponds to the duration of the subsequent diastole. The delay time and duration of a support pulse can be adjusted to the desired time for delivery of the trigger signal in the respective cardiac cycle phase.

[0076] Normalizing and / or considering heart rate has the advantage that the QT interval typically depends on the patient's heart rate. It is expected that a change in the QT interval will be accompanied by a change in heart rate. Conversely, this makes it particularly advantageous to determine a heart rate-optimized delay time. A standardized QT interval therefore already takes the variable heart rate into account. A delay time can be selected using the "Framingham formula" to represent the heart rate-based QT interval. In this way, a (theoretical) delay time for the current cardiac cycle can be calculated using standardized values ​​and the current heart rate. Standardized values ​​can be based on empirical values ​​and, for example, can be specified based on previous data sets that were previously evaluated and validated offline.The delay time can be calculated, for example, using the following variant of the “Framingham form”:.

[0077] Delay time = 380 - 154 x (1 - 60 / heart rate) During right ventricular pacing (RVP) of the heart, the QT interval can be advantageously determined using the stimulus T-time. In rate-adaptive pacemakers, the RVP T-time can be determined by measuring the RVP T-time to control the pacing rate during exercise.

[0078] The heart rate is preferably determined by the time interval between two R waves of successive cardiac cycles or by the time interval between two P waves of successive cardiac cycles, i.e., by a so-called RR interval or PP interval. In this way, the heart rate of the current cardiac cycle can also be taken into account. The delay time can thus be determined and optimized for each cardiac cycle. It is corrected almost automatically if the heart rate changes. If the systolic phase shortens, for example, due to an increase in heart rate, the delay time can be adjusted accordingly. In this way, a corresponding shortening of the QT interval due to an increase in heart rate can be taken into account when determining the delay time.

[0079] The trigger signal can therefore be delivered with increased probability at a time that does not fall within the systolic phase. Afterload can thus be reduced or even largely avoided. If the P wave is determined as the trigger signal, a PQ time interval or PR time interval can be extrapolated to the delay time in addition to the heart rate-optimized delay time. For example, an automatic correction of the delay time can be provided after a change in the trigger signal.

[0080] Alternatively, a delay time can be determined using the so-called "left ventricular ejection time" (LVET) using impedance cardiography, with the end of the LVET time interval indicating closure of the aortic valve.

[0081] Furthermore, a device for monitoring and optimizing temporal trigger stability of extracorporeal circulatory support is proposed, comprising (i) an interface for receiving an ECG signal of a supported patient over a predetermined period of time, and (ii) an evaluation unit configured to determine P waves, R waves, and T waves from the received ECG signal. The evaluation unit is advantageously configured to determine a predetermined trigger signal from the ECG signal of a current cardiac cycle, taking into account at least one detected P wave and / or at least one detected T wave. In particular, the device can be configured to carry out the inventive method described above. The ECG signal of the supported patient can be received via an interface of the device.The ECG signal can be processed using a working memory and / or stored on a storage medium. For example, the ECG signal can be communicatively connected to the evaluation unit via the interface. The evaluation unit can comprise both a working memory and a storage medium. ECG signals from various spatially separated ECG leads are preferably received via the interface. Multiple ECG signals can also be received. The evaluation unit is therefore advantageously configured to evaluate the ECG signals in order to determine the P waves, R waves, and T waves, as well as the trigger signal.

[0082] The aforementioned device is preferably designed as part of an ECG device. However, it can also be communicatively connected to at least one ECG device via one or more of the above-described interfaces. The device is preferably integrated into a control and regulation unit for extracorporeal circulatory support. The control and regulation unit can be configured to output a control and / or regulation signal for the extracorporeal circulatory support at a predetermined time after a specific trigger signal and with a predetermined delay time, taking into account the at least one P wave and / or the at least one T wave.

[0083] In the control and regulation unit, the device can preferably be provided as an integrated ECG device or attached to the control and regulation unit as an ECG device. Thus, the control and regulation unit can be used independently of other components and can be designed compactly. The ECG device is preferably integrated into a single housing of a system for extracorporeal circulatory support, for example, in a sensor box in the form of an ECG card or an ECG module.

[0084] The control and regulation unit can further be housed in a console, which has a user interface for entering and reading system settings, in particular parameters of the blood pump of an extracorporeal circulatory support system and / or the ECG device. For example, the console can comprise a touchscreen and / or a display with a keyboard, which can be operated by a user. The control and regulation unit preferably operates, actuates, controls, regulates, and monitors the blood pump. It enables synchronization of the blood pump with the cardiac cycle and, in particular, the patient's provided trigger signal.

[0085] Further advantages as well as possible embodiments and further developments of the methods have already been described in detail with regard to the control and regulation unit described above, so a repeated description of the corresponding aspects is omitted to avoid redundancies. However, the corresponding disclosure content continues to apply to this subject matter.

[0086] Short description of the characters

[0087] Preferred further embodiments of the invention are explained in more detail by the following description of the figures.

[0088] Figure 1 shows an electrocardiographic trace of an ECG signal for successive cardiac cycles in the physiological state;

[0089] Figure 2 shows the electrocardiographic course of the ECG signal according to Figure 1 with annotated ECG features;

[0090] Figure 3 shows a change in the electrocardiographic course with additional antegrade conduction via a Kent pathway in a WPW syndrome;

[0091] Figure 4 shows a change in the electrocardiographic course in atrioventricular re-entry tachycardia (AVRT) with a retrogradely conducting Kent pathway;

[0092] Figure 5 shows a change in the electrocardiographic course similar to that shown in Figure 4 with an intermittent right bundle branch block; and

[0093] Figure 6 shows an advantageous embodiment of a device according to the invention.

[0094] Detailed description of preferred embodiments

[0095] Preferred embodiments are described below with reference to the figures. Identical, similar, or equivalent elements in the different figures are provided with identical reference numerals, and a repeated description of these elements is partially omitted to avoid redundancies.

[0096] Figure 1 shows an ECG signal waveform for two successive cardiac cycles over a given time. This represents a physiological waveform. The respective cardiac cycle phases are color-coded. Accordingly, each cardiac cycle begins with the depolarization of the atrium, known as the P wave, which is characterized in this case by the amplitude change preceding the characteristic R wave with a current value of almost 0.1 mV.

[0097] This is followed by a characteristic and clearly recognizable R wave or R peak for each cardiac cycle, each with an amplitude, in this case with a current value of approximately 1 mV. The R wave, which is usually easily detectable in a physiological state, is caused by the depolarization of the ventricle, which marks the beginning of the systolic phase. The R wave is preceded by a Q wave; it is followed by an S wave, each with a less negative current value. Together, these amplitude changes form the so-called QRS complex.

[0098] After the contraction of the ventricle or after the excitation induced by the R wave, the repolarization or reversal of excitation of the ventricle occurs in the T wave, whereby the respective amplitude in this case has a current value / of approximately 0.1 mV and an overall positive current value.

[0099] In the present example, the ECG signal was obtained from ECG lead I for two cardiac events in sinus rhythm. Normal atrioventricular conduction (AV conduction) is observed.

[0100] In Figure 2, some characteristic features of the two cardiac actions shown in Figure 1 were automatically recorded or determined. Based on these features, specific time intervals and amplitude changes for the respective cardiac cycle can be determined. A trigger signal can be determined or adjusted if necessary by comparing them with predefined threshold values.

[0101] In the present example, the beginning and end of the P wave, the position of the R wave, the beginning and end of the QRS complex, and the beginning and end of the T wave were automatically recorded. The recording was carried out, in particular, through advantageous processing of the ECG signal using suitable bandpass filters. A bandpass filter between 10 Hz and 25 Hz was used for the QRS complex, a bandpass filter between 5 Hz and 20 Hz for the P wave, and a bandpass filter between 1 Hz and 5 Hz for the T wave. Using the expected frequency range and, if applicable, an expected maximum heart rate and / or an expected duration of the respective ECG feature or amplitude change, the corresponding features in the ECG signal can be advantageously recorded automatically, for example, using an appropriately configured feature extraction. Based on the annotated cardiac cycles, time intervals, e.g.The PR interval, the QRS interval, and the RT interval or QT interval are determined. In this example, the PR interval is between 170 ms and 185 ms, the QRS interval is between 95 ms and 110 ms, and the QT interval or RT interval is between approximately 385 ms and 435 ms. The time intervals can take on individual values ​​for each cardiac cycle and can vary depending on the heart rate.

[0102] Based on the determined time intervals and a comparison with appropriately predefined thresholds, the trigger signal to be determined and / or the detection of the P-wave, R-wave, and / or T-wave can be adjusted, for example, if the respective threshold is exceeded. In any case, a trigger signal can be determined with increased reliability. This can significantly improve trigger stability for extracorporeal circulatory support.

[0103] If a predefined threshold is exceeded, a finding of a cardiac arrhythmia, such as an atrioventricular block or bundle branch block, may be present. As described above, this can lead to failure of conduction. Ventricular depolarization may not occur or may not be adequately detected for a given cardiac cycle.

[0104] For example, an R-wave of lower amplitude, as indicated by the lowercase "r," may occur, or there may be no R-wave at all. A double R-wave (of lower amplitude) and / or a Q-wave of lower amplitude and / or an S-wave of lower amplitude may also occur.

[0105] Examples of bundle branch blocks are an (in)complete right bundle branch block or left bundle branch block. These can occur intermittently or non-intermittently. An AV block can be characterized in particular by a double R wave in the QRS complex, for example in the form of an M-shaped Rs-R' curve. Such a curve can depend on the respective ECG lead and, for example, in the case of a left bundle branch block, can be formed in ECG leads I, V5 and / or V6. A positive amplitude value can be present for the R wave in ECG leads I, aVI, V5 and / or V6, while a negative amplitude value can occur for the R wave in ECG leads III, aVR, aVF, V1, V2 and / or V3.In the case of a right bundle branch block, the S wave can be deeper and / or wider, for example in ECG leads I, aVL, V5 and / or V6, and / or the R wave can be higher, wider and in particular split, for example in ECG leads III, aVL, V1 and / or V2. Based on the course of the ECG signal and / or respective amplitude changes within the QRS complex, forms of cardiac arrhythmias can thus be identified and taken into account when determining the trigger signal. This procedure is preferably carried out in addition to taking into account the at least one P wave and / or T wave.

[0106] Instead of a bundle branch block or a conduction block, a left anterior or left posterior hemiblock may also occur. A bifascicular block may also be present, for example, a right bundle branch block with a corresponding hemiblock. These pathophysiologies can be diagnosed based on the P wave, T wave, and / or QRS complex, as described above, and taken into account when determining the trigger signal. Furthermore, ventricular and / or supraventricular conduction disturbances (bradycardic or tachycardic) may be present.

[0107] Figure 3 shows an electrocardiographic trace for several ECG leads, namely the surface ECG leads III, V1, and V6, with a right ventricular ECG RV34 also shown in the lower section. The upper markers each define a time interval of 1000 ms.

[0108] The ECG trace corresponds to a pathological course in Wolff-Parkinson-White syndrome (WPW syndrome) with additional antegrade conduction via a Kent pathway. It can be seen that the additional antegrade conduction occurs intermittently, namely during the first and third cardiac beats. Accordingly, the additional premature conduction between the atrium and ventricle leads to a shortening of the PQ interval. A ventricular extrasystole can also be seen in the second cardiac beat. To correctly detect the R wave, a corresponding PQ interval or PR interval can be shortened, or a corresponding threshold value can be adjusted, thus enabling stable triggering based on a detected R wave even in such a pathological course.

[0109] Figure 4 shows an electrocardiographic trace in a case of another cardiological pathology, namely atrioventricular re-entry tachycardia (AVRT) with a retrogradely conducting Kent pathway. As in Figure 3, a narrow QRS complex is present in this case. The ECG trace was recorded without right bundle branch block and without left bundle branch block for surface ECG leads I, II, III, V1, and V6. A right atrial ECG HRA34 is also shown in the lower section. As in Figure 3, the upper markers also define a time interval of 1000 ms each.

[0110] In the case of an intermittent right bundle branch block, the ECG waveform changes accordingly, as shown in Figure 5. The figure shows how the QRS complex widens when a right bundle branch block occurs. This effect is most noticeable in ECG leads I and V1. Accordingly, detecting such a widening of the QRS complex can not only determine or confirm a pathological course, but also allow for adjustments to the scheduled time intervals, for example, to support or facilitate future R-wave detection.

[0111] QRS time intervals or frequency ranges can be analyzed in the ECG in case of right bundle branch block as shown in Figures 1 and 2.

[0112] Figure 6 schematically shows a device 10 for monitoring temporal trigger stability according to the present invention. In this embodiment, the device 10 is designed as an ECG module. ECG signals can be received via an interface 12 and signals can be transmitted to other devices or apparatuses without requiring any special coupling. Thus, the interface can enable communicative coupling with an extracorporeal circulatory support system or an extracorporeal circulatory support device. It can also be designed together with an interface of a control and regulation unit.

[0113] The device 10 can optionally be designed as an ECG device that can be integrated into or attached to a control and regulation unit, thus providing a control and regulation unit for an extracorporeal circulatory support device that can be used independently of the provision of other components and has a compact design. Preferably, the device 10 can be integrated into a single housing of a system for extracorporeal circulatory support, for example, in a sensor box.

[0114] An ECG signal 14 from a patient receiving circulatory support can be received via the interface 12. The corresponding data can be temporarily stored in a working memory and optionally stored in a memory 18 of the device 10. The ECG signal 14 is forwarded from the interface 12 or via the working memory to an evaluation unit 16. The evaluation unit 16 is also communicatively connected to the memory 18. It is configured to receive or read out at least one pathological ECG signature 20 with evaluated ECG signals corresponding to a respective pathology or corresponding threshold values ​​or parameter values, and to compare the ECG signal 14 with the at least one ECG signature 20.

[0115] The ECG signature 20 can be selected based on the best possible superposition, for example, with the statistically largest possible superposition of an averaged PR time interval, QRS time interval, and / or RT time interval of multiple ECG signals 14. This can serve as the basis for subsequent cardiac cycles when determining a trigger signal 22 and / or when detecting the P wave, R wave, and / or T wave. In other words, suitable threshold values ​​and / or frequency ranges for the respective time interval from the pathological ECG signature 20 can be used and form the basis for further processing and use of the ECG signal 14. In particular, based on the selected pathological ECG signature, a trigger signal 22 can be determined or selected from the ECG signal 14 for subsequent cardiac cycles, which can be used to control and synchronize a blood pump of extracorporeal circulatory support.For this purpose, the trigger signal 22 can be forwarded to the interface 12 or provided there. At this interface 12, the trigger signal 22 can then be retrieved or received, for example, by a control and regulation unit.

[0116] Should one or more threshold values ​​for subsequent cardiac cycles be exceeded or should threshold ranges specified based on the pathological ECG signature 20 not be (regularly) met, the evaluation unit 16 can again compare with data sets stored "offline" in the memory 18 and thus with further pathological ECG signatures 20 in order to optimize the method again and further improve trigger stability. Such a process can be scheduled periodically. However, it preferably occurs continuously so that any changes in the ECG signal 14 can be detected and taken into account as quickly as possible.

[0117] Where applicable, all individual features presented in the embodiments may be combined and / or exchanged without departing from the subject matter of the invention.

[0118] List of reference symbols

[0119] 10 Device

[0120] 12 Interface

[0121] 14 ECG signal

[0122] 16 Evaluation unit

[0123] 18 storage

[0124] 20 pathological ECG signature

[0125] 22 Trigger signal

Claims

Claims 1 . A method for monitoring and optimizing a temporal trigger stability of extracorporeal circulatory support, comprising the steps: Receiving an ECG signal from a supported patient over a specified period of time; Determining P-waves, R-waves, and T-waves from the received ECG signal; and Determining a predetermined trigger signal from the ECG signal of a current cardiac cycle taking into account at least one detected P wave and / or at least one detected T wave.

2. Method according to claim 1, wherein the P-wave and / or T-wave is detected for the current cardiac cycle and / or for at least one preceding cardiac cycle, preferably at least or exclusively the immediately preceding cardiac cycle.

3. The method according to claim 2, wherein the P wave is detected at least for the current cardiac cycle and the T wave is detected at least for the immediately preceding cardiac cycle.

4. The method according to claim 1, 2 or 3, wherein the trigger signal is determined based on a P-R time interval between the P wave and the R wave of a respective cardiac cycle.

5. The method according to claim 4, wherein the determination of the predetermined trigger signal and / or the predetermined trigger signal to be determined is / are adjusted when a threshold value predetermined for the PR time interval is exceeded.

6. The method according to claim 5, wherein the adaptation of the predetermined trigger signal to be determined is a change from an R-wave to a P-wave or from a P-wave to an R-wave as the trigger signal.

7. The method according to any one of claims 4 to 6, wherein the detection of the P-wave, R-wave and / or T-wave for the current cardiac cycle is adjusted if a threshold value predetermined for the PR time interval is exceeded for at least one previous respective cardiac cycle.

8. The method according to any one of claims 5 to 7, wherein the threshold value for the PR time interval is at least 150 ms.

9. The method according to claim 8, wherein the threshold value for the PR time interval is between 150 ms and 400 ms, preferably between 200 ms and 300 ms.

10. The method according to any one of claims 5 to 9, wherein the threshold value for the PR time interval corresponds to at least 20 percent of the cardiac cycle duration, preferably at least 30 percent or at least 35 percent.

11. The method according to any one of claims 4 to 10, wherein the PR time interval is averaged for at least two cardiac cycles.

12. The method according to any one of claims 4 to 11, wherein the PR time interval is compared for at least two successive cardiac cycles and wherein the determination of the predetermined trigger signal and / or the predetermined trigger signal to be determined is / are adapted upon a successive prolongation of the PR time interval.

13. The method according to any one of the preceding claims, wherein the trigger signal is determined based on an RT time interval between an R-wave and a T-wave of a respective cardiac cycle.

14. The method according to claim 13, wherein the determination of the predetermined trigger signal and / or the predetermined trigger signal to be determined is / are adjusted when a threshold value predetermined for the RT time interval is exceeded.

15. The method according to claim 13 or 14, wherein the detection of the P-wave, R-wave and / or T-wave for the current cardiac cycle is adjusted if a threshold value predetermined for the RT time interval is exceeded for at least one previous respective cardiac cycle.

16. The method according to claim 14 or 15, wherein the threshold value for the RT time interval is at least 350 ms.

17. The method of claim 16, wherein the threshold value for the RT time interval is at least 450 ms.

18. The method according to any one of claims 14 to 17, wherein the threshold value for the RT time interval corresponds to at least 35 percent of the cardiac cycle duration, preferably at least 40 percent or at least 45 percent.

19. The method according to any one of claims 13 to 18, wherein the RT time interval is averaged from at least two cardiac cycles.

20. The method according to any one of the preceding claims, wherein the determining of the predetermined trigger signal, the predetermined trigger signal to be determined and / or the detection of the P-wave, R-wave and / or T-wave is adapted for the current cardiac cycle if an amplitude of the T-wave for at least one previous cardiac cycle comprises a negative value or is negative overall.

21. Method according to one of the preceding claims, wherein the trigger signal is determined based on a QRS time interval between a Q wave and an S wave of a respective cardiac cycle, wherein the determination of the predetermined trigger signal and / or the predetermined trigger signal to be determined is adapted when a threshold value predetermined for the QRS time interval is exceeded, and / or wherein the detection of the P wave, R wave and / or T wave for the current cardiac cycle is adapted when a threshold value predetermined for the QRS time interval is exceeded for at least one previous respective cardiac cycle.

22. The method according to claim 21, wherein the threshold value for the QRS time interval is at least 120 ms.

23. Method according to one of the preceding claims, wherein a threshold value for one or more time intervals within a respective cardiac cycle and / or the predetermined trigger signal is based on a pathological ECG signature.

24. The method according to claim 23, wherein the pathological ECG signature is predetermined and / or determined for the current cardiac cycle based on time intervals acquired from previous cardiac cycles.

25. The method according to claim 24, wherein the time intervals acquired from the previous cardiac cycles are compared with an "offline" evaluated data set containing ECG signals from assisted patients with a corresponding patient pathology, and wherein the ECG signature is specified based on a best possible match with an ECG signal from the data set.

26. The method according to claim 25, wherein for each known pathology, a time interval range, frequency range, and / or amplitude range and / or a trigger signal to be determined is specified for a respective time interval.

27. Method according to one of the preceding claims, wherein the P-wave, the R-wave and / or the T-wave are detected by means of a bandpass filter, wherein a frequency range for the P-wave is preferably between 5 Hz and 20 Hz, for the R-wave is preferably between 10 Hz and 25 Hz and / or for the T-wave is preferably between 1 Hz and 5 Hz.

28. Method according to one of the preceding claims, wherein the predetermined trigger signal is an R-wave and by taking into account the at least one detected P-wave and / or the at least one detected T-wave, a P-wave or T-wave is selected as the trigger signal to be determined.

29. Method according to one of the preceding claims, wherein, based on the determined trigger signal, a signal for the extracorporeal circulatory support is output with a delay time, wherein the delay time is predetermined taking into account the at least one detected P-wave and / or the at least one detected T-wave.

30. The method according to claim 29, wherein the delay time for the current cardiac cycle is determined based on a detected QT time from at least one previous cardiac cycle and wherein the QT time is normalized and / or taken into account based on a heart rate determined from the ECG signal.

31. Device (10) for monitoring and optimizing a temporal trigger stability of extracorporeal circulatory support, comprising an interface (12) for receiving an ECG signal (14) of a supported patient over a predetermined period of time, and an evaluation unit (16) which is configured to determine P-waves, R-waves, and T-waves from the received ECG signal (14), wherein the evaluation unit (16) is further configured to determine a predetermined trigger signal (22) from the ECG signal (14) of a current cardiac cycle, taking into account at least one detected P wave and / or at least one detected T wave.

32. Device (10) according to claim 31, which is arranged to carry out the method according to one of claims 2 to 30.

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