WO2024052141A1

WO2024052141A1 - Controller for an extracorporeal circulatory support in cardiac stimulation

Info

Publication number: WO2024052141A1
Application number: PCT/EP2023/073429
Authority: WO
Inventors: Matthias Heinke; Johannes Hörth
Original assignee: Xenios Ag; Hochschule für Technik, Wirtschaft und Medien Offenburg
Priority date: 2022-09-06
Filing date: 2023-08-25
Publication date: 2024-03-14
Also published as: DE102022003277A1

Abstract

The invention relates to a method for the open-loop/closed-loop control of an extracorporeal circulatory support of a patient receiving at least periodic cardiac stimulation, and corresponding devices and systems. A corresponding method is also provided for the open-loop/closed-loop control of an extracorporeal circulatory support of a patient receiving at least periodic cardiac stimulation, comprising the following steps: receiving (10) an ECG signal of a supported patient over a predefined time period; detecting 12) one or more stimulation signals (20) of the supported patient; and evaluating the ECG signal to identify (16) at least one change (22) in amplitude characterising a cardiac cycle phase and provide (18) a trigger signal for the extracorporeal circulatory support based on the identified at least one amplitude change (22). According to the invention, the detection (12) of the at least one stimulation signal (20) occurs with a scanning frequency of at least 1 kHz.

Description

Control for extracorporeal circulatory support during cardiac stimulation

Technical area

The present invention relates to methods for controlling/regulating extracorporeal circulatory support for a patient who is at least temporarily stimulated by the heart, as well as corresponding devices and systems.

State of the art

If the heart's pumping performance or pumping function fails, cardiogenic shock can occur. Due to a reduction in cardiac output or cardiac output, reduced perfusion or blood flow to the end organs, such as the brain, kidneys, and the vascular system in general, can occur. There is an acute lack of blood supply in the tissue and organs and thus a lack of oxygen, also known as hypoxia, which can lead to end organ damage.

In order to stabilize the patient's condition, circulatory support systems have been developed which provide mechanical support and can be quickly connected to the circulatory system. They can improve blood flow and perfusion of organs, including the coronary arteries, and avoid a hypoxic state. For example, a blood pump can be connected to a venous access using a venous cannula and an arterial access using an arterial cannula for sucking or pumping the blood in order to allow blood flow from one side with a low pressure, for example via an oxygenator, to one side to provide with a higher pressure. In this way, the patient's circulation is supported.

However, the complexity and dynamics of the patient's own heart action require precise timing and coordination of the extracorporeal support. This is how it is done for example, the blood flow in the heart's coronary arteries, which normally supply the heart muscle with sufficient oxygen, generally in diastole of the cardiac cycle. If the filling pressure at the end of systole or at the beginning of diastole in the left ventricle is as low as possible, the coronary arteries can expand their lumen as much as possible in order to increase the blood flow rate and oxygen supply. Appropriate emptying of the left ventricle is therefore necessary. Accordingly, the extracorporeal circulatory support for perfusion of the coronary arteries should be controlled in such a way that perfusion preferably occurs at the beginning of diastole, while perfusion should be avoided during systole.

To control extracorporeal support, measurement signals from an electrocardiogram (ECG) can be recorded and used. Corresponding characteristic amplitudes can be determined in this way for different cardiac cycle phases. For example, an R wave or R wave that is characteristic of the systolic phase of the cardiac cycle can usually be easily distinguished from other phases of the cardiac cycle, for example in a QRS complex. The R wave can be used, with a predetermined latency, to control a blood pump in a successive diastolic phase.

In order to support the patient's cardiac action, one or more stimulation pulses can also be provided using a cardiac pacemaker. However, signal interference can occur in the ECG signal provided, which makes it difficult to determine the corresponding amplitudes from the ECG signal. For example, as a result of a stimulation pulse, signal levels can be detected which mask the patient's own ECG signal and/or cause a corresponding change in amplitude. In both cases, synchronization cannot occur with sufficient security for the patient.

Accordingly, the task is to improve the accuracy of the detection of a characteristic amplitude change and to enable control of extracorporeal support, especially when the patient's heart is being stimulated.

Presentation of the invention

According to the invention, it was recognized that stimulation signals from a pacemaker are often provided shortly before or within a QRS complex of the patient's own heart action in order to support or even enable the excitation required for the heart action. If a control of the extracorporeal circulatory support uses a characteristic amplitude within this interval as a trigger signal, such an approach can result in either the failure to determine a patient's own amplitude relevant to the control or inadvertently one Amplitude change is recorded and taken into account in the control, which does not correspond to the characteristic amplitude change. Accordingly, the extracorporeal circulatory support may be activated at the wrong time, ie not in the intended cardiac cycle phase, or not at all.

It was also recognized that stimulation signals in the ECG signal cannot be clearly detected and/or conclusions about the presence of a stimulation signal in the ECG signal cannot be drawn in a timely manner or in a reliable manner for the control.

Based on the known prior art, it is therefore an object of the present invention to enable improved detection of the patient's own heart actions in the ECG signal for extracorporeal circulatory support and during cardiac stimulation of the patient.

The task is solved by the independent claims. Advantageous further developments result from the subclaims, the description and the figures.

Accordingly, a method for controlling/regulating extracorporeal circulatory support for a patient who is at least temporarily cardiac stimulated is proposed, comprising the steps:

receiving an ECG signal from a supported patient over a predetermined period of time;

detecting one or more stimulation signals from the supported patient; and

Evaluating the ECG signal to identify at least one amplitude change characteristic of a cardiac cycle phase and providing a trigger signal for extracorporeal circulatory support based on the identified at least one amplitude change.

According to the invention, the at least one stimulation signal is advantageously detected with a sampling frequency of at least 1 kHz.

Typically, ECG signals are provided with a sampling frequency between approximately 200 Hz and 400 Hz, with the temporal resolution being too low for the detection of stimulation pulses, in general, but especially in a reliable manner. However, due to the high sampling frequency proposed according to the invention, stimulation pulses with a short stimulation duration can also be recorded. For example, if the stimulation duration is approximately 1 ms or more, all stimulation pulses can be recorded clearly and reliably become. The identification of the stimulation pulse and the corresponding point in time in the respective cardiac cycle is no longer dependent on any manual identification of an anomaly or distortion in the ECG signal, but can be done clearly and with greater accuracy. The identification can be carried out, for example, based on a corresponding signal level and, if necessary, duration of the stimulation pulse. The voltage provided for a respective stimulation pulse usually differs clearly from the patient's own signal levels of the respective cardiac action.

If the stimulation duration is less than 1 ms, a provided stimulation pulse may not be recorded for every cardiac cycle, but, for example, for every second cardiac cycle. By statistically evaluating and monitoring the time intervals between the detected stimulation pulses, a time for a non-detected stimulation pulse can also be determined with a certain degree of accuracy, for example by means of interpolation.

By detecting the stimulation pulse or its time in a respective cardiac cycle, the stimulation pulse can simultaneously be taken into account in the ECG signal for determining the amplitude change. A characteristic amplitude change, which is used as a corresponding trigger signal for the control/regulation of the extracorporeal circulatory support, can be determined more precisely. This is because the signal heights in the ECG signal at the time of the stimulation signal and immediately afterwards can be taken into account to determine the amplitude change. Any distortions in the ECG signal, which would otherwise be recognized as a characteristic change in amplitude but are actually attributable to the stimulation signal, can be recognized as such.

Preferably, the amplitude change is identified based on the at least one stimulation signal. Based on the time of the stimulation signal, for example, a predetermined signal height can be provided for a predetermined immediately subsequent time period or time or the corresponding signal height of the ECG signal can be overwritten.

In this way, a modified or corrected ECG signal is provided. The predetermined signal height preferably corresponds to a normal value, which can be determined, for example, based on stored empirical values for a respective phase of the cardiac cycle. As a result, the determination of the characteristic amplitude change can be determined with improved temporal accuracy by taking into account a potential distortion of the ECG signal on the one hand and a normalization of the signal heights on the other hand, so that stability of a control can be guaranteed. Alternatively or in addition to overwriting the signal heights with a predetermined signal height, it can also be provided that the ECG signal comprises a signal height from at least two ECG leads for each point in time, the corresponding signal heights being averaged or added for the predetermined immediately following period of time to provide a correction for any distortion that occurs - based on the patient's own signal levels.

Accordingly, the ECG signal can comprise at least a first measurement signal from a first ECG lead and a second measurement signal from a second ECG lead. The first and second ECG leads are preferably spatially separated from one another and are selectively selected. The spatial or anatomical spacing can already ensure that the distance to the stimulation pulse is improved and that corresponding interference signals can thus be largely avoided. At least two data points are also available for each point in time of the specified immediately following period of time. Averaging or adding as part of a (spatial) signal averaging technique consequently makes it possible to correct the distortion of the ECG signal caused by the stimulation signal.

It can also be provided that the signal heights for the specified immediately following period of time are hidden or not taken into account when determining the amplitude change. As a result, the existing number of data points for determining the respective amplitude change can be reduced if necessary. It is ensured that the amplitude change is largely free of interference signals and the corresponding point in time in the respective cardiac cycle can be determined more precisely.

The “predetermined immediately subsequent period of time” is preferably between 2 ms and 40 ms, particularly preferably between 6 ms and 10 ms. The “predetermined subsequent period of time” preferably corresponds to a period of time which hides an amplitude or a distorted signal height due to the stimulation signal. In this way, the ECG signal to be provided does not contain any significant interference signals because these can be filtered out accordingly. A "blanking" can be provided. Furthermore, the predetermined immediately following time period is selected such that the characteristic amplitude change of an ECG signal or a specific cardiac cycle phase is still reflected in the ECG signal and is therefore not overwritten with the predetermined signal height. For example, This ensures that a QRS complex of an ECG signal and in particular an R wave or R wave, which can be used as a trigger signal for controlling the extracorporeal circulatory support, is present in the ECG signal provided. The stimulation pulse can be a unipolar stimulation pulse or a bipolar stimulation pulse. Combipolar stimulations or multi-phase stimulation pulses can also be provided, for example in cardiac contractility modulation. The type of stimulation pulse can be taken into account when detecting or identifying the stimulation signal and/or the predetermined, immediately following time period.

By taking the stimulation signal into account when identifying the amplitude change, the control signal for the extracorporeal circulatory support can thus be output or provided with increased temporal accuracy.

For improved detection of the stimulation signal, the sampling frequency for the stimulation signal is preferably in the range between 2 kHz and 100 kHz. In particular, the sampling frequency can be at least 5 kHz. In this way, stimulation signals or stimulation pulses with a very short duration, for example 0.2 ms or 0.4 ms, can be sufficiently detected. Thanks to the high-resolution temporal recording, stimulation signals can be better identified and processed, so that cardiac useful signals can be better distinguished from the stimulation signals. The temporal resolution enables a morphology or a course of the respective stimulation signal to be recorded in order to support this distinction and also the effect of the stimulation signal on the ECG signal. The relatively high sampling frequency can reduce distortions in the useful signal, for example in the native QRS complex.

Although the detection of the stimulation signal can also take place independently of the received ECG signal, the at least one stimulation signal is preferably detected by evaluating the received ECG signal. The ECG signal is provided with a corresponding sampling frequency. The sampling frequency for the stimulation signal advantageously corresponds to the sampling frequency of the ECG signal, so that the ECG signal has a sampling frequency of at least

1 kHz is received. The ECG signal with a sampling frequency of at least is preferred

2 kHz or at least 5 kHz provided or received.

If the stimulation signal is recorded separately, for example by means of an oscillator connected to the patient, the sampling frequency can even be significantly above 100 kHz and, for example, in the range between 1 MHz and 3 MHz. This high-resolution capture can then be processed. For example, the sampling rate can be reduced and/or low-pass filtering can be applied. The resulting signal can, for example, be embedded in the ECG signal or displayed overlaying it.

For a usual duration of a stimulation pulse, the sampling frequency in the range between 1 kHz and 20 kHz will typically be sufficient, with the sampling frequency of the ECG signal can also be in this range for practical reasons. This can simplify both the processing of the signal and the complexity of an ECG card and reduce energy consumption.

The sampling frequency can preferably be in the range between 5 kHz and 10 kHz for pacemaker pulses with pulse widths between approximately 0.4 ms and 2 ms, for example in the case of cardiac resynchronization therapy. The pulse width of the right atrium can be, for example, about 0.4 ms, the right ventricle about 0.5 ms and the left ventricle about 2.0 ms.

A higher sampling frequency in the range from 10 kHz to 20 kHz can advantageously be selected for pacemaker pulses and "spinal cord stimulation" (SCS) with pulse widths less than or equal to 0.3 ms, for example if a pacemaker with automatic stimulation threshold adjustment for the right atrium and right Ventricle is used. Such a sampling frequency can also be selected for the detection of stimulation pulses from other stimulating implants with a small pulse width or pulse duration similar to an SCS stimulation pulse.

A sampling frequency in the range between 1 kHz and 5 kHz provides improved detection accuracy in the case of stimulation pulses with longer pulse widths, for example between about 2 ms and 20 ms, for example in the case of left atrial stimulation of about 10 ms and/or left ventricular stimulation of about 20 ms, especially in the case of transesophageal stimulation.

Furthermore, it can be provided that the ECG signal is received from several ECG leads and the at least one stimulation signal is detected - based on an evaluation for at least two ECG leads. In this way, possible interference signals can be largely avoided, for example by averaging or summing the ECG measurement signals. In this way, the identification of the time of stimulation can be supported. Finally, a certain redundancy can also be provided for the detection of the at least one stimulation signal if, for example, the stimulation signal cannot be derived from every ECG measurement signal, for example due to the selected sampling frequency and/or the spatial distance of the respective ECG lead.

The at least one stimulation signal can be identified, for example, based on a detected or determined duration and/or slope of the signal, preferably the duration and the slope. Corresponding threshold values can be provided which, when exceeded, indicate the presence of a stimulation signal. The slope can be determined more precisely at a higher sampling frequency, in particular in that Correspondingly more potential data points or signal heights can be taken into account when recording or evaluating.

In order to support the identification of the at least one stimulation signal, the at least one stimulation signal can be identified - based on ECG signals and/or stimulation signals evaluated offline. One or more data sets with evaluated and verified data can be provided if the times of the respective stimulation pulses have been clearly determined. Based on this data, for example, certain signal heights or signal curves or slopes that characterize the stimulation signal can be taken into account during identification and thus make it easier. This enables a clear assignment of the stimulation pulse to one or more specific times in the ECG signal.

Based on empirical values, it can also be taken into account that the drop in the stimulation pulse can change depending on the state of charge of the pacemaker battery and if the resistance of the electrodes and the tissue changes. For example, the drop in the stimulation pulse can increase with reduced battery voltage and increased internal resistance of the battery.

The evaluated signals are preferably based on clinical data and/or simulated data. The data can, for example, be provided with and without cardiac stimulation, whereby the cardiac stimulation can be permanent or temporary. Furthermore, the data can be provided not only from circulatory support systems, but also from other cardiovascular systems. In particular, the evaluated signals can include clinical data. This allows signal heights and signal curves to be taken into account, which cannot be achieved using simulations or emulations, so that the evaluated data more closely corresponds to the real stimulation signals and/or ECG signals.

In order to make it easier to identify the stimulation signal or the time of the stimulation pulse, the at least one stimulation signal can be identified - based on an evaluation in the time domain and spectral domain and/or a statistical evaluation. An evaluation in the time and spectral range can be carried out, for example, based on a frequency distribution, whereby the occurrence of a stimulation pulse can be identified by recording it in several higher frequency ranges at a given time. A probability of a potentially present and detected stimulation pulse can also be determined, for example based on the signal progression within a respective cardiac cycle or between successive cardiac cycles, the point in time in the respective cardiac cycle, and/or by interpolation of detected stimulation signals or stimulation pulses. In this way, the accuracy of identifying the time at which a stimulation pulse is delivered can be further increased.

The duration, height and frequency of the stimulation pulses are generally set specifically for the patient. They are typically at least partially dictated by the configuration of a pacemaker. For some patients, stimulation pulses lasting up to 2 ms can be delivered, while for other patients, stimulation pulses with a duration of only 0.4 ms can be delivered. The height of the stimulation pulse can be between 0.5 V and 7 V, for example. Finally, the type and frequency of the stimulation pulse can vary individually for patients. For example, unipolar stimulation or bipolar stimulation can take place and/or a stimulation pulse can be delivered for every cardiac cycle or every second cardiac cycle.

In order to adapt the sampling frequency for the detection of the stimulation signal to the clinical circumstances, it can be provided that an initial sampling frequency for the detection of the stimulation signal is set based on information received from a cardiac pacemaker of the supported patient. This makes it possible, for example, to set a required minimum time resolution for detecting the stimulation signal. In this way, compatibility with the respective pacemaker can be guaranteed and the recording settings can be adapted to the pacemaker. This is particularly advantageous if the method is designed for different pacemakers and can therefore or should be optimized based on the information received.

The information therefore preferably includes a configuration of the pacemaker, a set operating mode of the pacemaker and/or a type, signal level and/or duration of one or more stimulation pulses to be delivered. In particular, the duration of the stimulation pulses can be particularly advantageous for the initial sampling frequency. This is because it can be ensured that a sufficient sampling frequency is provided for the respective stimulation pulses and that all stimulation pulses can be reliably recorded.

The sampling frequency for acquiring the stimulation signal can be set iteratively for successively acquired stimulation signals. For example, if it is determined for the respective cardiac cycle that no stimulation pulse was detected, although this would have been expected based on the course, the sampling frequency can be increased in order to detect subsequent stimulation pulses with increased probability. A set temporal resolution may also not be necessary if this is indicated, for example, by the duration of the stimulation pulses and the acquisition rate. Around the To reduce computing capacity and/or energy consumption, the sampling frequency can be reduced in such cases.

The sampling frequency can be increased or reduced, for example, as a percentage of the set sampling frequency, for example in steps between one percent and five percent. Alternatively, an absolute frequency value can be provided, for example between 100 Hz and 500 Hz, whereby the absolute frequency value can be dynamically adjusted at very high initial sampling frequencies in order to accelerate a potential effect of the adjustment.

The sampling frequency for detecting the stimulation signal can preferably be set depending on a determined stability of the trigger signal and/or identification of the amplitude change. In this way, the control/regulation of the extracorporeal circulatory support can also be optimized, for example, under changing conditions and during operation of the extracorporeal circulatory support. For example, if a distortion is detected in the EKC signal but no stimulation signal is detected, the sampling frequency for detecting the stimulation signal can be increased accordingly, if necessary even briefly. This can ensure that a stimulation signal can be detected in the next cardiac cycle if a stimulation signal could not previously be detected or could not be detected sufficiently due to a sampling frequency that was too low.

A trigger time interval can also change due to an unrecognized stimulation signal and/or a distortion in the ECG signal can be inadvertently recognized as a characteristic amplitude change, which changes the trigger stability. However, the sudden absence of a stimulation signal in an expected time interval could also have been caused by a change in the operating mode or the patient condition or therapy. Such changes can be taken into account by monitoring the determined stability of the trigger signal and/or change in amplitude and adjusting the sampling frequency accordingly.

The sampling frequency for detecting the stimulation signal can also be set depending on a slope, signal level and/or duration determined for the at least one stimulation signal. The sampling frequency for detecting the stimulation signal is preferably set depending on a morphology and/or a course of the stimulation signal, which is determined, for example, based on the slope, signal height and/or duration of the at least one evaluated stimulation signal.

For example, for a detected stimulation pulse, it can be recognized that no end of the stimulation pulse was detected. The sampling frequency can then be increased be carried out in order to completely capture a successive stimulation pulse and to enable a corresponding correction of the ECG signal.

Conversely, the sampling frequency can also be reduced if it has been determined that the duration of the detected stimulation signal exceeds a predetermined threshold and a set temporal resolution for the detection can be reduced with regard to the duration of the stimulation signal and the determination of the amplitude change.

An adjustment can also be made if, for example, an initial sampling frequency has been set based on information from the pacemaker, but should now be corrected based on the selected operating mode. Such an adjustment can preferably take place automatically, in particular iteratively, as described above.

The method and in particular the (automatic) setting of the sampling frequency can also be used to test ECG signal-controlled extracorporeal circulatory support devices. For example, time intervals between characteristic amplitude changes recorded from the ECG signal, e.g. B. R-R trigger intervals can be compared with the corresponding results when using the high-resolution sampling frequency according to the invention for the stimulation signals in order to determine whether an adjustment of the sampling frequency might be necessary.

A pacemaker configuration of a pacemaker to be used can also be taken into account. Should an adjustment of the sampling frequency be made, either for the ECG signal or for a separate acquisition of the stimulation signal, this can be optimized and adjusted accordingly in order to ensure compatibility of the extracorporeal circulatory support device with the pacemaker to be used or used.

Typically, ECG signals are provided with a sampling rate between 200 Hz and 400 Hz, meaning that stimulation signals with a duration of less than 5 ms or 2.5 ms cannot be reliably recorded. If stimulation pulses with a duration of more than 2.5 ms are delivered, they can in principle be recorded for the ECG signal without adjusting the sampling frequency. However, for a duration of, for example, 1 ms or 0.4 ms, an increase in the sampling frequency to at least 1 kHz or 2.5 kHz may be advantageous. However, the sampling frequency is preferably set even higher in order to take into account fluctuations in the pulse duration or the potential occurrence of interference signals and/or to provide a certain safety redundancy during the detection. The sampling frequency can therefore be increased to 5 kHz, for example. It can be seen that cardiac stimulation or the stimulation pulse can be carried out individually for a patient using a variety of cardiological support functions. Not only external pacemakers or implanted pacemakers, but also an implanted cardioverter, an implanted defibrillator, or cardiac resynchronization therapy can be provided for simulation or as a pulse generator.

In addition to a method for controlling/regulating extracorporeal circulatory support, a method and a device for testing and/or adjusting a device for controlling/regulating extracorporeal circulatory support for use in at least temporarily heart-stimulated patients are also proposed.

According to a further aspect of the invention, a device for controlling/regulating extracorporeal circulatory support of a patient who is at least temporarily stimulated by the heart is proposed, comprising an interface for receiving an ECG signal from a supported patient over a predetermined period of time and an evaluation unit which is set up for this purpose, at least one to identify the amplitude change in the received ECG signal that is characteristic of a cardiac cycle phase. The device is set up to detect one or more stimulation signals from the supported patient and to provide a trigger signal for extracorporeal circulatory support based on the identified at least one amplitude change. According to the invention, the interface is set up to retrieve the at least one stimulation signal with a sampling frequency of advantageously at least 1 kHz.

The device preferably comprises a control and regulation unit, which can be communicatively coupled to an ECG device of the supported patient to adjust the sampling frequency and which is set up to provide the trigger signal, preferably by means of the interface.

In particular, the device can be set up to carry out the method according to the invention described above.

The device can, for example, be communicatively coupled directly to at least one ECG lead or also to an ECG device by means of the interface in order to receive recorded ECG signals. The device is preferably designed as (part of a) control and regulation unit and includes an ECG device or is designed as part of an ECG device. The device can preferably be accommodated together with an ECG device or a sensor box in a single housing of a system for extracorporeal circulatory support. The at least one stimulation signal can be detected via a communicatively coupled but separate device, for example by means of an oscillator. More preferably, however, the stimulation signal is determined or identified in the received ECG signal. This allows the system to be more compact and designed as an independent unit. The device can be coupled to the extracorporeal circulation support or a corresponding system, for example via the same interface.

The ECG measurement signals have a recorded signal height and accordingly form data points which can be processed or evaluated using the evaluation unit. The evaluation unit can, for example, be designed as an integrated computing module and include logic in order to evaluate the received signals and determine a characteristic change in amplitude and an emitted stimulation pulse. The signals can be recorded by the evaluation unit at least for a specific time period or for the entire predetermined period of time or longer, for example by means of a coupled or integrated storage medium or in a volatile main memory.

Furthermore, a circulatory support device is proposed, which includes the device described above for controlling/regulating extracorporeal circulatory support.

The circulatory support device can be designed as part of a system for extracorporeal circulatory support of a patient, the system comprising the device for extracorporeal circulatory support. The device typically includes a blood pump fluidly connectable to a venous patient access and an arterial patient access and designed to provide blood flow from the venous patient access to the arterial patient access, and an ECG device.

The control/regulation device is communicatively coupled to the circulatory support device and is set up to output a control and regulation signal for adjusting the blood pump at a predetermined time after the at least one amplitude change. The control device operates, actuates, controls, regulates and monitors the blood pump and enables the blood pump to be synchronized with the cardiac cycle of the respective patient.

Issuing the control signal or control signal for the extracorporeal circulatory support can result in an immediate setting of a corresponding parameter or operating parameter of a coupled extracorporeal circulatory support device. For example, in this way one or more can be used in an extracorporeal system Circulation support existing pump drives or pump heads for blood pumps, for example non-occlusive blood pumps, are controlled or regulated. A desired blood flow rate for a corresponding cardiac cycle phase can thus be provided based on the ECG signal if the ECG signal has been processed and spectrally corrected based on the detected stimulation signal.

The blood pump may be connectable to a venous access via a venous cannula and to an arterial access via an arterial cannula for suction or delivery of blood to provide blood flow from a side with a low pressure to a side with a higher pressure. The blood can be passed through a membrane oxygenator to prepare the blood accordingly. The blood pump is preferably designed as a disposable or disposable item and is preferably fluidly separated from the respective pump drive and can be easily coupled, for example via a magnetic coupling. The control device actuates the motor of the pump drive by outputting the corresponding signal and can thus cause a change in the speed of the blood pump.

Short description of the characters

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

Figure 1 shows a schematic representation of a process sequence according to the invention;

Figure 2A shows a unipolar right ventricular stimulation signal with effective ventricular stimulation in ECG lead V5;

Figure 2B shows a unipolar right ventricular stimulation signal with effective ventricular stimulation in ECG lead V2;

Figure 3A shows a high-resolution cardiac pacemaker stimulation pulse;

Figure 3B shows the stimulation pulse according to Figure 3A in the time and spectral domain;

Figures 4A and 4B show different representations of a recorded ECG signal and a corresponding stimulation signal during bipolar cardiac stimulation; and

Figure 5 shows an electrocardiographic course of two spatially separated ECG leads with a high-resolution temporal recording of the ECG signal. Detailed description of preferred embodiments

Preferred exemplary embodiments are described below with reference to the figures. Identical, similar or identical elements are provided with identical reference numbers in the different figures. Reference to these elements is sometimes omitted in order to avoid multiple attributions.

1 schematically shows a method sequence according to the invention for controlling/regulating extracorporeal circulatory support for a patient who is at least temporarily cardiac stimulated. Accordingly, in step 10 an ECG signal or an ECG measurement signal from one or more ECG leads is received, for example for a predetermined time or continuously for successive cardiac cycles. The ECG signal contains signal heights for each data point, so that a corresponding measurement value is provided for each successive point in time in the ECG signal. The signal levels together form an electrocardiogram, which makes it possible to graphically depict and, if necessary, monitor the different cardiac cycle phases for each heart action of the patient.

Furthermore, in step 12 at least one stimulation signal from the supported patient is detected. With permanent cardiac stimulation, stimulation signals are preferably present for each cardiac cycle. With temporary stimulation, for example, every second or third heart action can be supported or even made possible in the first place by means of a stimulation pulse, preferably by means of a cardiac pacemaker. The detection in step 12A and - as shown with the dashed lines - can take place separately from the ECG signal provided, for example by means of an oscillator. In the present case, however, the at least one stimulation signal is detected from the received ECG signal.

Such parallel detection or identification from the ECG signal is made possible in the present case by providing and retrieving or receiving the ECG signal with a sampling frequency of at least 1 kHz. In particular, the sampling frequency can be at least 5 kHz, so that very short stimulation pulses with a duration of at least 0.2 ms can be reliably recorded. The stimulation pulse can preferably be identified based on the comparatively high voltage or amplitude change and/or the short duration or even a course of the corresponding signal heights in the ECG signal.

Once the respective stimulation pulse has been identified, the ECG signal can be processed in step 14, for example by hiding the immediately following data points or overwriting them with a predetermined value or signal curve. The now processed ECG signal, which no longer represents the stimulation signal recorded in step 12 or does not represent it significantly as an interference signal, is then converted into one for a specific one in step 16 Cardiac cycle phase characteristic amplitude change identified. This is preferably the so-called R wave in the QRS complex of the cardiac cycle, which fundamentally enables a clear and temporally stable assignment of the corresponding point in time to the systolic phase.

The identified, characteristic amplitude change, in particular the R wave, serves as the basis for providing a trigger signal for the extracorporeal circulatory support in step 18. As explained above, the trigger signal can, for example, be a control and/or regulation signal for an extracorporeal circulatory support device with temporal stability provide.

Accordingly, the control and/or regulation signal can be output with a predetermined latency, for example to activate a blood pump in a specific cardiac cycle phase and to promote extracorporeal blood flow. In this way, for example, improved blood flow to the coronary arteries can be provided within a diastolic phase. For example, one or more amplitude changes can be determined which are characteristic of an R wave in the respective cardiac cycle. The control and regulation signal can be output as an R trigger signal. Hiding or “blanking” the stimulation signals or interference signals makes it possible for control to be provided even when signal levels are present, which would otherwise, for example, cause a reset and prevent detection of an amplitude change.

Figures 2A and 2B show electrocardiographic curves of two spatially separated ECG leads during unipolar cardiac stimulation. In the present example, unipolar right ventricular cardiac stimulation takes place in cases of atrial fibrillation. It can be seen that the ECG signal has become severely distorted due to the stimulation pulse, both for the chest lead V5 (Figure 2A) and the chest lead V2 (Figure 2B). This is because the first strong change in amplitude does not correspond to the patient's own heart action, but rather is caused by the stimulation signal 20. The patient's subsequent amplitude change in the ECG signal is accordingly not recognized as a characteristic amplitude change 22, although an R wave would have been expected as a trigger signal at this point in time.

However, for an evaluation module, the amplitude change 20 caused by the stimulation signal 20 cannot be sufficiently distinguished from the native ECG signal, especially since the temporal resolution of the detection is not sufficient for this. The ECG signal was provided with a typical sampling frequency between 200 Hz and 400 Hz, in the present case at a frequency of 360 Hz. For a typical stimulation duration of, for example, 0.4 ms, the corresponding signal level cannot be clearly and reliably detected. A high-resolution temporal recording of a stimulation signal according to the invention is shown in FIGS. 3A and 3B. In the example shown, the stimulation signal was provided using a separate oscillator with a sampling frequency of 2.5 MHz. The stimulation pulse shown was provided by a cardiac pacemaker in VVI mode and has a stimulation amplitude of 1 V with a stimulation pulse duration of 0.4 ms, as was clearly recorded according to FIG. 3A. In Figure 3B, the stimulation pulse is further shown in the time and spectral domain. It can be seen that the amplitude changes corresponding to the stimulation pulse and shown in Figure 3A concentrate on the times -0.4 ms and 0 ms. The high temporal resolution also enables the morphology of the stimulation pulse to be preserved and the corresponding course to be recorded and determined. This enables even more precise processing of the ECG signal and determination of the characteristic amplitude change.

Corresponding representations of a recorded ECG signal and a corresponding stimulation signal are shown in Figures 4A and 4B, the signals (ECG lead I) being recorded during bipolar right ventricular cardiac stimulation of a pacemaker in VVI mode. The sampling frequency, as provided according to the invention, is (at least) 1000 Hz or 1 kHz. It can be seen from Figure 4A how a corresponding spike for the stimulation signal could be detected in the ECG signal.

The evaluation in the time and spectral range shown in FIG. 4B can also serve as a further basis for identifying the time of the stimulation pulse. The frequency distribution in particular suggests corresponding strong amplitude changes.

Figure 5 shows an electrocardiographic course of two spatially separated ECG leads I and II with a high-resolution temporal recording of the ECG signal, in the present case at 5000 Hz, and with VVI cardiac stimulation. In this example, stimulation pulses with an amplitude of 1 V and a duration of 0.4 ms are also delivered. Compared to FIG. 4A (and also FIGS. 2A and 2B), the stimulation signals 20 have now been clearly recorded and can be clearly identified. Furthermore, potential distortion in the ECG signal can be significantly reduced due to the high temporal resolution, so that the characteristic amplitude change 22, in this case the R wave, can be determined with increased reliability and stability.

Although ECG leads I and II are shown in the present case, additional or alternative ECG leads may be selected for receiving the ECG signal, for example transthoracic ECG leads III, aVR, aVL, aVF, V1, V2, V3, V4 , V5, and V6 or bipolar transesophageal ECG leads Oeso 12 and Oeso 34. The number and type of However, derivations are not to be viewed as limiting, so that in principle any selection of ECG derivations can be made to determine the amplitude change and to detect the at least one stimulation pulse. A spatially separate acquisition of measurement signals can thus take place, both within an anatomical area and for different anatomical areas, in order to reduce interference due to the stimulation pulses 20 in the ECG signal provided.

To the extent applicable, all individual features shown in the exemplary embodiments can be combined and/or exchanged with one another without departing from the scope of the invention.

Reference symbol list

10 Receiving an ECG signal

12 Acquiring a stimulation signal

12A Providing a stimulation signal 14 Processing the ECG signal

16 Identifying an amplitude change

18 Providing a trigger signal

20 stimulation signal

22 characteristic amplitude change

Claims

Claims Method for controlling/regulating extracorporeal circulatory support for a patient who is at least temporarily cardiac stimulated, comprising the steps:

Receiving (10) an ECG signal from a supported patient over a predetermined period of time;

Detecting (12) one or more stimulation signals (20) of the supported patient; and

Evaluating the ECG signal to identify (16) at least one amplitude change (22) characteristic of a cardiac cycle phase and providing (18) a trigger signal for extracorporeal circulatory support based on the identified at least one amplitude change (22), wherein detecting (12) the at least a stimulation signal (20) takes place with a sampling frequency of at least 1 kHz. Method according to claim 1, wherein the amplitude change (22) is identified based on the at least one stimulation signal (20). A method according to claim 1 or 2, wherein the sampling frequency for the stimulation signal (20) is in the range of 2 kHz to 100 kHz. A method according to claim 3, wherein the sampling frequency is at least 5 kHz. Method according to one of the preceding claims, wherein the at least one stimulation signal (20) is detected by evaluating the received ECG signal, the ECG signal being provided with a corresponding sampling frequency. Method according to claim 5, wherein the ECG signal is received from several ECG leads and the at least one stimulation signal (20) is detected based on an evaluation for at least two ECG leads. Method according to one of the preceding claims, wherein the at least one stimulation signal (20) is identified based on ECG signals and/or stimulation signals evaluated offline.

. Method according to claim 7, wherein the signals are based on clinical data and/or simulated data. . Method according to one of the preceding claims, wherein the at least one stimulation signal (20) is identified based on an evaluation in the time domain and spectral domain and/or a statistical evaluation. 0. Method according to one of the preceding claims, wherein an initial sampling frequency for detecting the stimulation signal (20) is set based on received information from a cardiac pacemaker of the supported patient. 1. The method according to claim 10, wherein the information comprises a configuration of the pacemaker, a set operating mode of the pacemaker and / or a type, signal level and / or duration of one or more stimulation pulses to be delivered. 2. Method according to one of the preceding claims, wherein the sampling frequency for detecting the stimulation signal (20) is set iteratively for successively detected stimulation signals (20). 3. Method according to one of the preceding claims, wherein the sampling frequency for detecting the stimulation signal (20) is set depending on a determined stability of the trigger signal and / or identification (16) of the amplitude change. 4. Method according to one of the preceding claims, wherein the sampling frequency for detecting the stimulation signal (20) is set as a function of a slope, signal level and/or duration determined for the at least one stimulation signal (20). 5. The method according to claim 14, wherein a morphology and / or a course of the stimulation signal (20) is determined based on the slope, signal level and / or duration of the at least one evaluated stimulation signal (20) and the sampling frequency for the detection of the stimulation signal (20) in Depending on the morphology and / or the course is set. 6. Device for controlling extracorporeal circulatory support of a patient who is at least temporarily cardiac stimulated, comprising an interface for receiving an ECG signal from a supported patient over a predetermined period of time, and an evaluation unit which is set up to identify at least one amplitude change in the received ECG signal that is characteristic of a cardiac cycle phase, the device being set up to detect one or more stimulation signals of the supported patient and a trigger signal for the extracorporeal circulatory support based on the identified to provide at least one amplitude change, the interface being set up to retrieve the at least one stimulation signal with a sampling frequency of at least 1 kHz. Device according to claim 16, comprising a control and regulation unit, which can be communicatively coupled to an ECG device of the supported patient to adjust the sampling frequency and which is set up to provide the trigger signal, preferably by means of the interface. Device according to claim 16 or 1 7, which is set up to carry out the method according to one of claims 1 to 15. Circulation support device, comprising a device according to one of claims 16 to 18.