Control of ventricular assist devices

Abstract

To provide an improved control device for a VAD, such as an intravascular blood pump.SOLUTION: A control device includes an input configured to receive at least one measuring signal related to a physiological condition of the circulatory system of a patient receiving heart assistance by a VAD, where the control device is configured to derive an actual value of at least one characteristic parameter of the heart from one or more of the at least one measuring signal and to provide a refined actual value of the at least one characteristic parameter in which effects of physiologically caused fluctuations are eliminated or reduced. The control device further includes an output configured to output an updated setting value for the speed level, where the control device is configured to produce the updated setting value based on the refined actual value and a predeterminable set-point value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the field of ventricular assist devices. In particular, the present invention relates to a control device for controlling a ventricular assist device (VAD), such as an intravascular rotary blood pump, and to a VAD equipped with a control device for controlling the VAD. [Background technology]

[0002] If a patient's heart's pumping function is insufficient despite the best medical treatment, the circulatory system can be assisted with a VAD (Vascular Adapter). A VAD can assist, or even replace, the inadequate pumping function of the heart's ventricles by delivering blood in parallel with them. For this purpose, a VAD is typically configured to take in blood from the circulation at the inlet and eject it back into the circulation at the outlet. In doing so, the VAD must overcome the actual pressure difference between the outlet and the inlet, i.e., between the VAD's afterload and preload.

[0003] One exemplary embodiment of a VAD is a catheter-based rotary blood pump, which is configured to be placed or implanted directly in the heart for several hours or days to assist cardiac function until recovery. For example, U.S. Patent No. 5911685A discloses a non-pulsating intravascular rotary blood pump. However, other types of VADs also exist. The intravascular rotary blood pump known from U.S. Patent No. 5911685A includes two pressure sensors for measuring ambient blood pressure at each of its respective locations after the blood pump has been implanted in the heart.

[0004] For example, in an intensive care unit, ventilation, or respiratory support, may be provided to patients with insufficient cardiac function who are receiving VAD (ventilator-aided discharge) support. Respiratory support is provided through ventilation to the outside, resulting in the patient's rhythmic expansion and contraction of the lungs. This ventilation to the outside also causes a corresponding change in intrathoracic pressure. The change in intrathoracic pressure results in corresponding fluctuations in cardiovascular and / or intracardiac pressure. In particular, intrathoracic pressure is higher during inspiration (expansion) than during expiration (contraction).

[0005] In a normal operating room or coronary intensive care unit, conscious patients receiving cardiac support may breathe autonomously. In this case, the effects described above are reversed; that is, intrathoracic pressure during inspiration is lower than during expiration.

[0006] In the exemplary context discussed above, it was found that the pressure changes described resulted in fluctuations in the measured vascular and / or intracardiac pressures. As a possible consequence, these fluctuations may affect the stability of blood pump rate control. Furthermore, the detection or avoidance of events such as negative pressure may be impaired. It should be noted that these are only two specific examples of how fluctuations in monitored vascular and / or intracardiac measurement signals may affect VAD control. Furthermore, assisted or autonomous respiration, described as a possible cause, is also just one example. Other examples of physiologically occurring fluctuations include pressure changes resulting from intra-aortic balloon pump therapy, external counterpulsation therapy, or changes in the patient's body position, such as to the Trendelenburg position. [Overview of the project] [Problems that the invention aims to solve]

[0007] There is a need for improved control devices for VADs such as intravascular blood pumps, and corresponding VADs equipped with such control devices, wherein physiologically occurring variability in one or more measurement signals obtained from a patient receiving cardiac assistance by the VAD has been improved in its control, particularly in relation to the control of the VAD speed, which is related to the blood flow produced by the VAD, such as the rotational speed of a rotary intravascular blood pump. Furthermore, there is a desire to provide a method for obtaining a refined actual value of at least one characteristic parameter of the heart, in which the effect of physiologically occurring variability in one or more measurement signals from which the actual value is derived is eliminated or at least reduced. Furthermore, there is a need for a method for controlling the VAD speed level based on the refined actual value. [Means for solving the problem]

[0008] This objective is achieved by the features of the independent claims. Each dependent claim specifies advantageous embodiments and further developments.

[0009] The fundamental idea behind the improvements presented herein is to eliminate or at least reduce physiologically occurring variability in the actual values ​​derived from at least one cardiac characteristic parameter that can be used to control VAD speed, for example, the speed of a rotary pump in an intravascular blood pump. In particular, instability, e.g., fluctuations, of a controlled VAD speed controlled by closed-loop control can be avoided or at least reduced. For example, end-diastolic left ventricular pressure may be used as a cardiac characteristic parameter in a patient receiving cardiac assistance by a VAD. Based on this, the VAD speed may be automatically adjusted by closed-loop control so that the monitored end-diastolic left ventricular pressure achieves a desired setpoint value. Other characteristic parameters may also be used in controlling the VAD speed. It has been found that physiologically occurring variability exists in the measured signal, which obscures the "true" actual value of the characteristic parameter derived therefrom. This can, for example, lead to instability in the controlled VAD speed. For example, end-diastolic left ventricular pressure, monitored as one characteristic parameter, is affected by the patient's autonomous or assisted breathing, and consequently, the control of VAD rate is also affected. By eliminating or at least reducing these physiologically occurring fluctuations, the controlled VAD rate becomes more stable. Thus, it has been proposed to make available the "true" actual value of at least one characteristic parameter of the heart.

[0010] For clarity, the following definitions are used herein.

[0011] The term "cardiac characteristic parameter" should be understood as a specific value derived from physiological signals that can characterize the state of the heart, for example, with respect to load conditions such as overload or unloading, and / or physiological states such as weakened, strong, or recovering.

[0012] The "circulatory system" is the organ system that enables blood to circulate. The essential components of the human circulatory system are the heart, blood, and blood vessels. The circulatory system includes the pulmonary circulation, which is the "loop" through the lungs that supplies oxygen to the blood, and the systemic circulation, which is the "loop" through the rest of the body that provides oxygenated blood.

[0013] The first aspect relates to a control device for a ventricular assist device (VAD) having a configurable rate level, and specific embodiments and further developments thereof are described below herein. The “configurable rate level” may be individual rate levels, for example, specific individual rotational speeds of a rotary blood pump, or continuously configurable rate levels within a range defined by minimum and maximum rates. The rate level is related to the blood flow rate produced by the VAD and, therefore, the amount of assistance provided to the heart. However, since the actual pressure difference between the inlet and outlet of the VAD also affects the blood flow rate produced at a particular VAD rate, there is not necessarily a direct relationship between the VAD rate and the blood flow rate produced.

[0014] The control device comprises at least one input section configured to receive at least one measurement signal. The at least one measurement signal represents or includes information about at least one physiological value (also called a quantity) related to the circulatory system of a patient receiving cardiac assistance by a VAD.

[0015] The control device is configured to derive an actual value of at least one characteristic parameter of the heart from at least one measurement signal, i.e., at least one characteristic parameter may also be derived from two or more measurement signals.

[0016] The control device is further configured to provide a refined actual value of at least one characteristic parameter, on which physiologically occurring variations are eliminated or reduced. The refined actual value is, according to the above considerations, a “true” actual value of one or more measurement signals on which at least one characteristic parameter is based, that is not obscured by physiologically occurring variations.

[0017] The control device further includes an output section configured to output an updated setting value for the VAD speed level. Preferably, the control device is configured to generate an updated setpoint based on the current refined actual value of at least one characteristic parameter and its preset setpoint value. For example, to this end, the control device may implement closed-loop control in which at least one characteristic parameter is controlled by adjusting the speed level of the VAD so that the monitored characteristic parameter achieves a predetermined setpoint value.

[0018] Preferably, the control device is configured to process at least one measurement signal and / or the actual value of at least one characteristic parameter to provide a refined actual value of at least one characteristic parameter.

[0019] For this purpose, the control device may be configured to process multiple actual values ​​of a characteristic parameter within a moving time interval. The time interval preferably includes the current actual value and further historical values ​​of the characteristic parameter; that is, the time interval begins in the past and ends at the point in time when the current actual value of the characteristic parameter is reached. Preferably, the time interval is configurable by the user of the control device or adjustable by the control device.

[0020] Multiple actual values ​​of at least one characteristic parameter may be stored as a time series of actual values ​​of the characteristic parameter. This time series may include a limited number of actual values ​​of at least one characteristic parameter. Preferably, the limited number of actual values ​​of the characteristic parameter may correspond to values ​​belonging to the current travel time interval, which include the current actual value of the characteristic parameter and further historical or past values ​​within the current time interval. The time interval ends with the current actual value and goes back only a predefined time frame. Further historical values ​​within the time interval may include all actual values ​​of at least one characteristic parameter located within the time interval. However, the time series may simply include the values ​​of the characteristic parameter within the time interval, every other, every two, or every four, etc. Thus, the time series includes a continuous column or sequence of actual values.

[0021] In certain embodiments, the current refined actual value of a characteristic parameter is a moving average of the current actual value of the characteristic parameter and further historical or past values ​​within a moving time interval. Additionally or alternatively, the current refined actual value of a characteristic parameter may be based on a moving average of at least one measurement signal from which the characteristic parameter is derived.

[0022] In certain applications, physiologically occurring variations in characteristic parameters may be caused by fluctuations in the patient's intrathoracic pressure. These pressure fluctuations may also be due to the patient's assisted or autonomous breathing. More specifically, when the patient is receiving respiratory support through pulmonary ventilation, the fluctuations may correlate with respiratory rate or ventilatory rate. Fluctuations may also occur for other reasons. For example, physiologically occurring fluctuations can be caused by intra-aortic balloon pumps (IABP), external counterpulsation (ECP) therapy, or changes in the patient's body position, such as changing the body to the Trendelenburg position, but these are just a few examples.

[0023] In short, IABP is a mechanical device that improves oxygen perfusion to the myocardium while simultaneously increasing cardiac output. IABP may consist of a cylindrical balloon placed in the aorta, and its inflation and deflation are controlled to beat in the opposite direction to the heart's beat. ECP is a procedure performed on the patient using air cuffs attached to the legs, which inflate and deflate at a timing based on the patient's electrocardiogram, ideally inflating at the start of diastole and deflating at the start of systole. ECP is similar to IABP because it increases the pressure in the aorta while the heart is relaxed during diastole. In the Trendelenburg position, the body is laid flat on the back with the feet 15-30 degrees higher than the head, while in contrast, the reverse Trendelenburg position, the body is tilted in the opposite direction.

[0024] For this purpose, the control device may be configured to determine, based on the actual historical values ​​of at least one measured signal and / or characteristic parameter, the frequency of physiologically occurring variability that correlates with the rate of respiration or ventilation that should be eliminated or at least reduced. For example, the rate of respiration or ventilation may be detected by measuring the time interval in which minimum or maximum values ​​appear in the measured signal. For example, the ventilation rate VF (or similarly, the respiratory rate) may be calculated from the time interval between consecutive maximum (or minimum) values ​​of at least one measured signal or at least one characteristic parameter.

[0025] For example, if the measured signal is left ventricular pressure (LVP), the characteristic parameter is defined as end-diastolic left ventricular pressure (EDLVP). In this case, the actual respiratory rate (VF) is the reference value used, e.g., the time of occurrence of left ventricular pressure (LVP) or end-diastolic left ventricular pressure (EDLVP). k-1 , and the time of reappearance t k In, VF=( t k、EDLVP、max -t k-1、EDLVP、max ) -1 , and / or VF=( tk、LVP、max -t k-1、EDLVP、max )-1 , It can be determined as follows.

[0026] To eliminate or reduce physiologically occurring variations, the control device may be configured to process a sequence of actual values ​​of one or more of the at least one measurement signal and / or at least one characteristic parameter by applying a moving average filter. The moving average filter may have a size related to the periodicity of the physiologically occurring variations to be eliminated. Alternatively or additionally, the control device may be configured to process a sequence of actual values ​​of one or more of the at least one measurement signal and / or at least one characteristic parameter by applying a high-pass filter having a characterization cutoff frequency related to the physiologically occurring variations to be eliminated.

[0027] For example, in exemplary applications where physiologically occurring fluctuations are related to respiration, the periodicity of the fluctuations correlates with the respiratory rate or ventilation rate. Therefore, the moving average filter may have a size related to the respiratory rate or ventilation rate; that is, the size of the moving average filter can define the time interval.

[0028] At least one measurement signal may be at least one pressure in the patient's circulatory system. For example, at least one measurement signal may be at least one of the patient's left ventricular pressure (LVP), aortic pressure (AoP), central venous pressure (CVP), pulmonary artery pressure (PAP), and ECG signal, but these are just some preferred examples.

[0029] A specific value of vascular blood pressure and / or intracardiac blood pressure at a given event in the cardiac cycle may be used as at least one characteristic parameter.

[0030] In a further development form, at least one characteristic parameter may be derived from at least two specific values of the vascular blood pressure and / or the intracardiac blood pressure at a predetermined event of the cardiac cycle. For example, at least one characteristic parameter may be the pressure gradient between two intracardiac pressures at two specific events during one cardiac cycle.

[0031] For example, at least one characteristic parameter is here the time point t OMV at which the mitral valve opens, followed by CMV the time point t at which the mitral valve closes, and the filling gradient FG of the left ventricular pressure LVP during the cardiac cycle's cardiac diastolic phase defined between them.

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[0032] Based on the filling gradient FG as at least one characteristic parameter, the control device may be configured to generate an updated setpoint such that the filling gradient is positive and approaches or is maintained near zero. Most preferably, the control device is configured to maintain the filling gradient at zero.

[0033] As an alternative or in addition, at least one characteristic parameter may be the diastolic relaxation or systolic contraction of the heart.

[0034] Systolic contraction is defined as the positive quotient obtained by dividing the difference in left ventricular pressure values observed at the moment of mitral valve closure and the moment of aortic valve opening by the time span between them, that is, the time elapsed from mitral valve closure to aortic valve opening.

[0035] Diastolic relaxation is defined as the quotient obtained by dividing the difference in left ventricular pressure observed at the moment of aortic valve closure and the moment of mitral valve opening by the time span between these two moments, i.e., the time elapsed from aortic valve closure to mitral valve opening.

[0036] Furthermore, the control device may be further configured to calculate the actual heart rate based on the time interval between the occurrence and subsequent recurrence of at least one characteristic parameter.

[0037] Additionally or alternatively, the control device may be configured to calculate the actual blood flow generated by the VAD as one specific characteristic parameter.

[0038] With regard to updating setpoints, the control device may be configured to generate an updated setpoint whenever at least one refined actual value of at least one characteristic parameter deviates a predetermined distance from the corresponding preset setpoint value. Alternatively, the control device may be configured to update the setpoint when a new refined actual value of the characteristic parameter is generated. Alternatively, the control device may be configured to update the setpoint periodically, i.e., at a predetermined update interval.

[0039] The second aspect relates to a VAD for assisting a patient's heart.

[0040] The VAD comprises, i.e., is connected to or coupled to, any one of the control devices described according to the first embodiment above.

[0041] In certain exemplary preferred embodiments, the VAD is a non-pulsating rotary blood pump. The blood pump is preferably a catheter-based blood pump. Most preferably, the VAD is a low-inertia device characterized by one or more of the following features (a) to (c): (a) the moving, especially rotating, parts of the VAD, e.g., rotor or impeller, have low mass by being made of a low-weight material, e.g., plastic; (b) the driving means, such as an electric motor, is located near, preferably very close to, most preferably adjacent to, the motor-driven parts, e.g., rotor or impeller, and, if catheter-based, preferably does not have a rotary drive cable; (c) the coupling or connection of the motor to the motor-driven parts, e.g., rotor or impeller, e.g., the shaft is short; all the moving, especially rotating, parts of the VAD are small in diameter.

[0042] For example, a control device for a VAD, such as the one described according to the first embodiment, can be particularly useful when connected to a catheter-based rotary blood pump, as it can directly control the blood flow through it based on at least one determined characteristic parameter. Such a blood pump is known, for example, by U.S. Patent No. 5,911,685A. In this context, the control device is a so-called pump control device for controlling the rotational speed, or speed level, of the blood pump.

[0043] Basically, such blood pumps are placed in the left or right heart for temporary placement or implantation. In the case of left-sided cardiac support, the blood pump is positioned so that it is ultimately located inside the left ventricle of the patient's heart via the aorta, with the cannula protruding through the opening of the aortic valve, allowing the pumping device to pump blood from the left ventricle through the cannula into the aorta via the aortic valve.

[0044] In alternative right-sided cardiac support, the blood pump is positioned in the vena cava anterior to the right heart, so that its cannula protrudes through the opening of the tricuspid valve, bridging the right atrium and right ventricle, and the pumping device delivers blood flow through the cannula directly from the vena cava into the pulmonary artery.

[0045] For example, the pump device may comprise a motor section and a pump section fixed to the distal end of the motor section. However, other configurations are also possible, such as one in which the motor is distal to the outlet of the pump section. The pump section may further comprise a tubular pump housing having a propulsion element, such as an impeller, rotating inside. The propulsion element may be mounted on a motor shaft protruding from the motor section. Alternatively, other methods of coupling the motor to the drive unit are possible, such as magnetic coupling between a rotating sealed motor and a propulsion element such as an impeller. A flow cannula may extend from the distal end of the pump section, adapted to allow blood to be drawn through the pump device during operation of the blood pump, or to be ejected when the pumping direction of the pump flow is reversed.

[0046] Regarding the configuration of the control device, the control device may implement a data acquisition unit having at least one input for receiving external and internal signals. For example, one input may be configured to receive at least one measurement signal, which may be, for example, a vascular pressure signal or an intracardiac pressure signal.

[0047] At least one measurement signal may be collected internally by one or more sensors, which may be, for example, sensors that can be integrated into or on the VAD, or sensors that can be implanted in the patient. Alternatively or additionally, at least one measurement signal may be collected externally, for example, by an additional monitoring system.

[0048] It should be noted that "external" here refers to signals that are outside the system comprising the control device and the VAD. On the other hand, "internal" refers to signals that are already present in the control device and / or the VAD, or that are provided by the components of the control device and / or the VAD.

[0049] Furthermore, the control device may have, be connected to, or coupled to a user interface comprising input and output means. For example, the input means may be one or more input devices, such as keys and / or buttons that are pressed and / or rotary buttons that are rotated. The output means may be a display device for displaying information such as configuration information about the control device, or operating data of the control device and / or VAD. In particular, the input and output means may be partially or completely integrated as a single entity, such as a touchscreen device. Input signals from the input devices may be transferred to a data acquisition unit and further used, for example, as configuration data about the control device.

[0050] For example, the user interface may be configured to allow the user to select a specific parameter from at least one characteristic parameter to be used for controlling the speed level of the VAD. Furthermore, the user interface may provide corresponding input means configured to allow the user to define corresponding setpoint values ​​for at least the characteristic parameters, and these setpoint values ​​may be selectable by the user as needed. That is, the setpoint values ​​are pre-configurable by the user. Alternatively or additionally, input of setpoint values ​​may be provided by other internal units of the control device itself. Such other internal units may be configured to perform signal processing and / or analysis, such as the data processing units discussed below herein. Alternatively or additionally, setpoint values ​​may be provided by an expert system unit.

[0051] The control device has an output section configured to output updated setting values. It should be noted that "output" does not necessarily mean that the signal is output by the control device to another external entity. "Output" can also be the output section of a specific part within the control device, for example, a unit implemented inside the control device that is configured to perform a specific function or capability.

[0052] As described above, in the context of an exemplary catheter-based rotary blood pump as an exemplary embodiment of a VAD, the speed level setting of the VAD may be the rotational speed setting of the pump device of the blood pump. For example, the rotational speed setting may correspond to the rotational speed that the rotating propulsion element driven by the electric motor of the pump device should establish.

[0053] Regarding the acquisition of measurement signals, for example, at least two pressure sensors may be placed on or incorporated into the VAD such that one sensor detects the pressure at the VAD inlet, i.e., the preload, and the other sensor detects the pressure at the VAD outlet, i.e., the afterload. Alternatively or additionally, the VAD may include a pressure sensor capable of detecting the actual pressure difference between the preload and the afterload.

[0054] At least one pressure sensor may be implemented by any suitable pressure sensor. Preferably, one or more pressure sensors are read out, i.e., sampled or pulled, at a frequency of at least about 250 Hz.

[0055] For example, when the VAD is positioned in conjunction with left-sided cardiac assistance, the VAD may include a first pressure sensor located at the inlet, which will be positioned within the left ventricle when the VAD is deployed within the left heart. The pressure sensor can be used to generate a measurement signal representing left ventricular pressure as at least one physical value. Additional and alternative blood pressures representing physical values ​​related to the circulatory system may be aortic pressure (AoP). Thus, additionally or alternatively, the VAD may include a pressure sensor located at the outlet, which will be positioned within the aorta when the blood pump is deployed within the left heart. With respect to left-sided cardiac assistance, preferably at least one characteristic parameter may be at least one of the following: aortic pressure value observable at the moment of aortic valve closure, aortic pressure value observable at the moment of aortic valve opening, end-diastolic left ventricular pressure observable at the moment of mitral valve closure, and left ventricular pressure observable at the moment of mitral valve opening. Furthermore, possible characteristic parameters may be the cardiac pressure gradients, e.g., filling gradient, diastolic relaxation, and systolic contraction, as discussed above.

[0056] Correspondingly, when the VAD is positioned to accommodate cardiac support on the right side, the inlet of the VAD may be located in the superior vena cava or the right ventricle, and the outlet may be located in the pulmonary artery; therefore, the physical quantities associated with the circulatory system may be central venous pressure (CVP) and / or pulmonary artery pressure (PAP). Characteristic parameters may be derived accordingly in relation to cardiac support on the left side, as discussed above.

[0057] It is useful to note that other devices can also serve as sources that provide useful measurement signals representing physical values ​​related to the circulatory system. For example, such sensors may include electrodes of an electrocardiogram (ECG) device, which can be attached to the patient's skin, for instance. Such ECG signals provided by an ECG device may be used as a measurement signal representing one physical value related to the circulatory system.

[0058] A control device may comprise at least one arithmetic unit for implementing internal units configured for the internal functions or functionalities of the control device. The arithmetic unit may comprise any combination of hardware and software. That is, the arithmetic unit may comprise programmable hardware which may comprise a corresponding computer program which includes software code for causing programmable hardware to perform each required step of a particular function or functionality of the control device, such as those described herein. Programmable arithmetic units are generally known in the art and to those skilled in the art, and therefore no further explanation is needed.

[0059] Naturally, the arithmetic unit may include specific dedicated hardware with hardcoded specific functions, such as a field-programmable gate array (FPGA), and / or one or more dedicated processors, such as a signal processor for processing and / or analyzing at least one measurement signal. In this regard, the control device may structurally consist of hardware units and / or software modules, each implementing its respective functional unit that cooperates in controlling the speed of the VAD. For simplicity, it is assumed that all the functions and functionalities described herein are collectively performed by the control device. In this specification, specific functions of the control device are described with reference to dedicated units implemented in or by the control device and configured for specific functions or functionalities, but it should be noted that, in general, the association between specific functions or functionalities and specific units may be adapted as needed.

[0060] Firstly, the control device may implement the data acquisition unit described above. The data acquisition unit may be configured to collect signals measured externally and internally. Secondly, the control device may implement a signal processing unit. The signal processing unit may be configured to derive characteristic parameters by processing at least the measured signals. For example, the signal processing unit may be configured to determine end-diastolic left ventricular pressure as at least one characteristic parameter from measured signals over time representing left ventricular pressure. Alternatively or additionally, the signal processing unit may be further configured to generate further values ​​that can be used as characteristic parameters based on at least one derived characteristic parameter and / or at least one measured signal. Thirdly, the control device may implement a signal analysis unit. The signal analysis unit may be configured to analyze external and internal signals and / or at least one characteristic parameter over time. For example, the signal analysis unit may be configured to predict the next occurrence of a particular event in the cardiac cycle of the assisted heart. For example, such an event may be at that point in time, and the next occurrence of aortic valve closure is expected. Furthermore, the signal analysis unit may be configured to process the actual values ​​of at least one measured signal and / or at least one characteristic parameter discussed above to provide their refined actual values. Fourth, the control device may implement a speed command unit. Generally, the speed command unit may be configured to provide a speed command signal to the VAD indicating a speed level to be established by the VAD's motor, such as the electric motor of an exemplary rotary blood pump. Sixth, the control device may implement a motor control unit, although the motor control unit may be external to the control device. The motor control unit may be configured to adjust the speed level of the VAD according to a current speed command signal to establish a speed according to the current actual set value of the speed.For example, in the context of a rotary blood pump, the motor control unit may be configured to adjust the speed of the rotary blood pump by changing the power supplied to the electric motor of the blood pump. For example, the motor control unit may adjust the electric motor current supplied to the motor of the blood pump. Finally, the signal processing unit and signal analysis unit may be implemented by a single unit, such as a data processing unit.

[0061] As discussed above, the signal processing unit and / or signal analysis unit may be configured to determine at least one characteristic parameter based on the derivative of the corresponding measured signal.

[0062] For example, the characteristic parameter may be the left ventricular pressure at end-diastolic pressure. For this purpose, the control device measures the left ventricular pressure LVP as intracardiac pressure LVP signal. meas The system may be configured to use the first and / or second derivatives of the measured signal representing left ventricular pressure (EDLVP). Furthermore, at least one characteristic parameter may be the end-diastolic left ventricular pressure (EDLVP), which may be detected by sampling or data extraction based on the first and / or second derivatives of the measured signal representing left ventricular pressure. For this purpose, the actual value of EDLVP is used with the measured signal LVP. meas and / or measurement signal LVP meas It may also be derived based on the derivative d / dt of . Alternatively, additional signals may be used.

[0063] For example, the actual value of EDLVP, the measured signal LVP meas It may be detected based on the first derivative of the measurement signal LVP. meas We can also differentiate it with respect to time, i.e., dLVP meas The first derivative is dLVP. meas / dt is a predetermined threshold v threshold When it reaches or exceeds this, and / or when other favorable conditions are in effect, this particular point in time t k In the actual EDLVP(t k The value can be determined.

[0064] For example, a predetermined threshold v threshold This may be set individually for a specific patient, for example, by ECG. For example, the control device may measure the LVP signal. meas It may be configured to compare with the ECG signal or a trigger signal based thereon. For example, EDLVP can be detected shortly after the R wave occurs in the corresponding ECG signal. Threshold v threshold This is the first derivative dLVP of the ECG signal when the R wave appears or shortly thereafter. meas It may be adjusted accordingly to match / dt, i.e., the first derivative dLVP. meas A specific value of / dt can be set based on another signal, such as an ECG signal.

[0065] Alternatively, the actual value of EDLVP may be determined by employing only the ECG signal. For example, the control device may be configured to monitor the ECG signal for the R wave, which occurs approximately simultaneously with the occurrence of EDLVP. Alternatively, the control device may simply receive and use a trigger signal indicating the occurrence of the R wave to determine the actual value of LVP as the current actual value of EDLVP.

[0066] The calculation of the actual blood flow rate produced by the VAD may be as follows: for example, in the context of a rotary blood pump as an exemplary VAD, the control device may be configured to calculate the actual blood flow rate through the blood pump based on the actual pressure difference between the inlet and outlet of the blood pump, the actual speed of the blood pump, and the power supplied to the blood pump. Preferably, for this purpose, the control device may have access to a set of characteristic curves that represent the relationships between these parameters, which are stored. The set of characteristic curves may be stored in the memory of the calculation unit or in memory in the blood pump that is accessible to the calculation unit. For example, the set of characteristic curves may be stored in the form of a lookup table.

[0067] The present invention will be described below with reference to the attached drawings. [Brief explanation of the drawing]

[0068] [Figure 1] This figure shows a simplified block diagram of an embodiment of a catheter-based intravascular blood pump, as an example of a VAD, and a control device for the blood pump, which is routed through the aorta, through the aortic valve of the heart, and into the left ventricle. [Figure 2] Figure 1 is a side view of the VAD, including some details. [Figure 3] This figure shows the control device in Figure 1 within the application context for patients receiving cardiac support via a VAD and respiratory support via a pulmonary ventilation device. [Figure 4A] This figure shows the physiologically occurring fluctuations (Figure 4C) caused by lung ventilation, based on the detected end-diastolic pressure value (Figure 4A) and end-diastolic pressure signal. In this case, the physiologically occurring fluctuations are reduced (Figure 4A), and the rotation speed of the blood pump (Figure 4B) is under the control of the control device. [Figure 4B] This figure shows the physiologically occurring fluctuations (Figure 4C) caused by lung ventilation, based on the detected end-diastolic pressure value (Figure 4A) and end-diastolic pressure signal. In this case, the physiologically occurring fluctuations are reduced (Figure 4A), and the rotation speed of the blood pump (Figure 4B) is under the control of the control device. [Figure 4C] This figure shows the physiologically occurring fluctuations (Figure 4C) caused by lung ventilation, based on the detected end-diastolic pressure value (Figure 4A) and end-diastolic pressure signal. In this case, the physiologically occurring fluctuations are reduced (Figure 4A), and the rotation speed of the blood pump (Figure 4B) is under the control of the control device. [Figure 5A] This figure shows the detection of end-diastolic pressure values ​​in the left ventricular pressure signal. [Figure 5B] This figure shows the detection of end-diastolic pressure values ​​in the left ventricular pressure signal. [Figure 6A] This figure shows charts illustrating left ventricular pressure signals for two cardiac cycles, including pressure gradients such as the filling gradient (Figure 6B), systolic contraction, and diastolic relaxation. [Figure 6B] This figure shows a diagram illustrating the filling gradient, especially without VAD assistance. [Figure 6C] This figure shows the effect of speed level control based on the fill gradient. [Figure 7] Figure 6C further illustrates the auxiliary effect of the VAD with several pV loops. [Figure 8] This figure shows a characteristic curve illustrating the relationship between the actual pressure difference ΔPpump between preload and afterload in a rotary blood pump, the actual blood pump speed npump, and the corresponding blood flow rate Qpump produced by the blood pump. [Modes for carrying out the invention]

[0069] Referring now to Figures 1 and 2, Figure 1 shows a catheter-based rotary blood pump (hereinafter referred to as the "blood pump") on the left, which is described herein as an exemplary embodiment of a VAD, and this exemplary blood pump is shown in more detail in Figure 2.

[0070] The blood pump is based on a catheter 10, which allows the blood pump to be temporarily introduced into the left ventricle 16 through the aorta 12 and aortic valve 15 of the heart. As shown in more detail in Figure 2, in addition to the catheter 10, the blood pump includes a rotary pump device 50 fixed to the end of the catheter tube 20. The rotary pump device 50 includes a motor section 51 and a pump section 52 located at an axial distance therefrom. A flow cannula 53 extends from the pump section 52, connected at one end to the pump section 52, with an inlet cage 54 located at the other end. The inlet cage 54 is fitted with a flexible tip 55. The pump section 52 includes a pump housing with an outlet opening 56. Furthermore, the pump device 50 includes a drive shaft 57 protruding from the motor section 51 into the pump housing of the pump section 52. The drive shaft 57 drives an impeller 58 as a propulsion element, thereby enabling the rotary pump device to draw blood through the inlet cage 54 and discharge it through the outlet opening 56 during operation.

[0071] The pump device 50 can also deliver blood in the opposite direction if appropriately adapted, which is necessary, for example, when the blood pump is installed in the right heart. In this regard, for completeness, Figure 1 shows a rotary blood pump as one specific example of a VAD positioned in the left heart for its assistance. For assistance to the right heart, the rotary blood pump in this example may be positioned in the right heart so that blood is introduced from the superior vena cava into the right heart and ejected into the pulmonary artery. In this configuration, the blood pump may be configured to draw blood from the superior vena cava or the right ventricle and to eject that blood into the pulmonary artery. That is, the principle and functionality described by this particular embodiment are appropriately adapted for cardiac assistance on the right side. Therefore, further explanation is not necessary.

[0072] In Figures 1 and 2, three lines—two signal lines 28A and 28B and a power supply line 29 for supplying current to the motor area 51—pass through the catheter tube 20 of catheter 10 to the pump device 50. The two signal lines 28A and 28B and the power supply line 29 are attached to the control device 100 at their proximal ends. Needless to say, additional lines for further functions may be present, for example, a line for purge fluid (not shown) may also pass through the catheter tube 20 of catheter 10 to the pump device 50. Additional lines may be added based on different sensing techniques.

[0073] As shown in Figure 2, signal lines 28A and 28B are part of the blood pressure sensor and have corresponding sensor heads 30 and 60, respectively, which are located externally on the housing of the pump area 52. The sensor head 60 of the first pressure sensor is associated with signal line 28B. Signal line 28A is associated with and connected to the sensor head 30 of the second blood pressure sensor. The blood pressure sensor may be an optical pressure sensor that operates according to the Fabry-Perot principle, such as described in U.S. Patent No. 5911685A, where the two signal lines 28A and 28B are optical fibers. However, other pressure sensors may be used instead. Essentially, the signals from the pressure sensors, each carrying information about the pressure at the sensor location and of any preferred physical origin, such as optical, hydraulic, or electrical, are transmitted via the respective signal lines 28A and 28B to the corresponding inputs of the data processing unit 110 of the control device 100. In the example shown in Figure 1, the pressure sensors are arranged such that aortic pressure (AoP) is measured by sensor head 60 and left ventricular pressure (LVP) is measured by sensor head 30.

[0074] The data processing unit 110 receives the corresponding aortic pressure AoP measurement signal AoP via the input unit 101. meas and left ventricular pressure (LVP) measurement signal LVP meas It is connected to the respective signal lines 28A and 28B for receiving signals.

[0075] The data processing unit 110 is configured to acquire external and internal signals for signal analysis, such as calculating the difference between two pressure signals as a basis for estimating pump flow rate, and for signal processing, such as deriving the actual value of at least one characteristic parameter σ, for example, the end-diastolic left ventricular pressure EDLVP or filling gradient FG of the heart, which will be transferred to the speed command signal generation unit 120.

[0076] The data processing unit 110 is connected to an additional measuring device 300, such as an electrocardiogram (ECG) 310, via corresponding signal lines in the input sections 102 and 103. The ECG 310 provides the data processing unit 110 with an ECG signal. Device 310 is illustrative and non-limiting; other external measuring devices, such as device 320, can also supply useful signals and may be used.

[0077] The control device 100 further comprises a user interface 200, which includes a display 210 as an output means and an input device 220 such as a keyboard or buttons as an input means. The display device 210 and the input device 220 are partially integrated into one in the form of a touchscreen device. The display 210 can display setting parameters, monitored parameters such as the pressure signal to be measured, and other information such as a setting menu. In particular, it can display the refined actual value of at least one characteristic parameter σ, e.g., EDLVP * or FG * This may be displayed to the user via the display device 210. Furthermore, the user interface 220 allows users of the control device 100 and VAD to interact with the control device 100, for example, by changing desired settings of the system.

[0078] Furthermore, refined actual values ​​of at least one characteristic parameter σ, e.g., EDLVP, are available, where the effects of physiologically occurring variations are eliminated or reduced.* FG * This is provided in the output unit 104 for external use as needed.

[0079] The data processing unit 110 also calculates the refined actual value of at least one characteristic parameter σ, e.g., EDLVP * or FG * It is also configured to provide the refined actual value of at least one characteristic parameter σ, which is transferred to the speed command signal generation unit 120.

[0080] The speed command signal generation unit 120 generates the actual speed command signal n VAD set It is configured to generate and adjust, i.e., update, the speed command signal n and supply it to the speed control unit 130. VAD set This is provided by the instruction signal generation unit 120, which operates in an external feedback loop to which the refined actual value of at least one characteristic parameter σ is continuously supplied.

[0081] The command signal generation unit 120 also generates a corresponding setpoint value SP for at least one characteristic parameter σ, for example, EDLVP. set or FG set The setpoint value SP is also provided by the data processing unit 110. The command signal generation unit 120 generates a refined actual value of at least one characteristic parameter σ, for example, EDLVP. * or FG * Based on the error signal ERR (see Figure 3) corresponding to the actual difference between the actual setpoint value SP and the actual speed command signal n VAD set It is configured to generate the actual speed command signal n. VAD set The actual speed command signal n may be generated based on the error signal in the form of a proportional-differential-integral (PID) control device 125 (see Figure 3), or any other alternative control device such as a fuzzy control device. VAD setThis is then transferred to the speed control unit 130.

[0082] In response, the speed control unit 130 receives the speed command signal n VAD set According to this, the speed of VAD n VAD The motor current I is controlled via a power supply line 29 extending through the catheter tube 20, referring to a rotary blood pump as an example VAD. VAD The motor current I is supplied to the motor area 51 of the pump device 50. VAD The actual level is when the pump device 50 receives the actual speed command signal n VAD set It corresponds to the current required to establish the target speed level defined by [the relevant parameter]. The pump device 50 may communicate with the control unit 100 via the power supply line 29, i.e., it may provide a signal corresponding to the actual rotational speed.

[0083] Supplied motor current I VAD The measurement signal is an example of an internal signal to the control device 100, which is also provided to the data processing unit 110 for further processing and use.

[0084] According to the first embodiment, the control device 100 for the pump device 50 as an embodiment of a VAD with a settable speed level measures the left ventricular pressure (LVP) signal LVP, which represents a physical value related to the circulatory system of a patient receiving cardiac assistance by the VAD. meas It includes an input unit 101 configured to receive data.

[0085] The control device 100 has refined actual values ​​EDLVP of at least one characteristic parameter, in which physiologically occurring variations are eliminated or at least reduced. * or FG * It is configured to provide the measurement signal LVP. For this purpose, in the embodiment shown, the data processing unit 110 provides the measurement signal LVP. measIt is configured to derive the actual value of EDLVP as the actual value of at least one characteristic parameter σ of the heart.

[0086] The data processing unit 110 processes the measurement signal LVP. meas Alternatively, refined actual EDLVP or FG is obtained by processing actual EDLVP or FG to eliminate physiologically occurring variations. * or FG * It is further configured to provide the refined actual value EDLVP of at least one characteristic parameter σ. * or FG * This is then transferred to the speed instruction unit 120.

[0087] The speed command unit 120 then outputs the correspondingly updated speed command signal n in the output unit 105. VAD set This is provided to the motor control unit 130 as the current setting value.

[0088] The motor control unit 130 controls the pump device 50 when it receives a speed command signal n VAD set The corresponding motor current I required to establish a target speed level as defined by VAD To supply.

[0089] Figure 3 shows an embodiment of the application of the improved control device 100 from Figure 1 in the context of patient P receiving cardiac support from VAD50 and respiratory support from pulmonary ventilation device 70.

[0090] First, on the right side of Figure 3, the dashed box depicts patient P. Furthermore, box H depicts patient P's heart. For simplicity, the lower half of box H corresponds to the left ventricle 16, within which the flow cannula 53 with the inflow cage 54 of the pump device 50 shown in Figures 1 and 2, as well as one of the pressure sensors, sensor head 30, are located. The motor section 51, pump section 52, and pump housing 56 are located in the aorta, downstream of the aortic valve 15. The motor section 51 of the pump device 50 provides the pumping speed of the pump device 50. The motor current I required is supplied via the power supply line 29 by the motor control unit 130 of the control device 100. VAD By supplying the refined actual value EDLVP as at least one characteristic parameter σ, * or FG * Based on this, the speed of the VAD can be controlled.

[0091] Within box P, there is further shown a box representing patient P's lungs L. In this example, patient P, who has insufficient cardiac function, receives cardiac support from a pump device 50 and further ventilatory support to the lungs L from a ventilation device 70.

[0092] During ventilation, the lungs (L) expand and contract. This affects the pressure inside the patient's (P) pleural cavity, resulting in synchronous fluctuations in intracardiac pressure. Therefore, the measured left ventricular pressure (LVP) includes the corresponding physiologically occurring fluctuations. The ventilation pressure sensor 72 controls the control device 100, which monitors the ventilation pressure VentP meas The ventilation pressure sensor 72 receives the pressure signal, which is the measurement signal.

[0093] The data processing unit 110 of the control device 100 processes the received measurement signal LVP meas The refined actual value EDLVP of the characteristic parameter σ is obtained by continuously processing the signal to which physiologically occurring variations are eliminated or at least reduced. * or FG *It is configured to generate the received ventilation pressure VentP meas It is configured to continuously perform signal processing on the measurement signal.

[0094] For controlling the pump speed of the pump device 50, the data processing unit 110 receives the corresponding measurement signal LVP meas The system is configured to derive the actual value of EDLVP detected or derived from it. Refined actual value of EDLVP as characteristic parameter σ EDLVP * or FG * This is transferred to the speed instruction unit 120. The speed instruction unit 120 receives a configurable setpoint value SP for EDLVP or FG, for example, EDLVP set or FG set A comparison is made with the corresponding speed command signal n supplied to the motor control unit 130. VAD set The system is configured to generate a certain value, after which the motor control unit 130 adjusts the motor current supplied to the electric motor of the pump device 50 accordingly.

[0095] As shown in Figures 5A and 5B, for this purpose, the data processing unit 110 processes the left ventricular pressure measurement signal LVP meas The first derivative of dLVP meas The system is configured to determine the actual value EDLVP based on FV, which is the filtered (or smoothed) version of / dt.

[0096] For example, the left ventricular pressure measurement signal LVP meas The first derivative of dLVP meas / dt is a predetermined threshold v threshold When it is determined that this is equal (and / or that further conditions are valid), the actual value of the current LVP is determined to be the actual value of the EDLVP.

[0097] As an alternative or in addition, the control device 100 may use the ECG signal provided by the ECG device 310. In this case, the data processing unit 110 is configured to check whether the ECG signal indicates an R wave as a further condition. Further, in the case of the ECG signal, the control device 100 is configured to adjust a predetermined threshold value v based on the R wave occurring in the ECG signal so that the actual value of EDLVP can be determined based on the first derivative of LVP as considered above. meas In the operation of the VAD, the control of the blood pump speed level is based on the refined actual value EDLVP of EDLVP and the corresponding setpoint value SP. The speed command unit 120 is configured to calculate an error signal ERR based on the refined actual value EDLVP and the setpoint value SP. The speed command unit 120 is further configured to generate a correspondingly updated speed command signal n supplied to the motor control unit 130 based on the error signal ERR in the manner of a PID controller 125. threshold The control principle regarding the speed level of the VAD based on LVP as a measurement signal representing a physical quantity related to the circulatory system considered above can be modified to be based on any one or more other measurement signals representing physical quantities related to the circulatory system. For example, another or further vascular pressure and / or intracardiac pressure, such as aortic pressure AoP, central venous pressure CVP, and / or pulmonary artery pressure PAP for heart assistance on the right side, as well as the ECG signal may be used.

[0098] As described above, due to ventilation, the lung L expands and contracts by the ventilation device 70. This affects the pressure in the patient P's thoracic cavity, and as a result, the measurement signal LVP * * VAD set

[0099]

[0100] meas ​​​​Corresponding variations occur. As a result, the EDLVP derived in the inhalation phase increases in the inhalation phase and decreases in the exhalation phase. This causes corresponding physiologically occurring variations in the control of the speed level of the VAD.

[0101] Figures 4A to 4C show the variations of the actually derived EDLVP with induced ventilation. In Figure 4A, the measurement signal LVP meas (solid line) is drawn, and the actually derived EDLVP is marked with triangles. Figure 4C shows the ventilation pressure VentP that causes the corresponding variations of the EDLVP values over time.

[0102] To eliminate these physiologically occurring variations, as a first method, the data processing unit 110 is configured to apply an average filter to the actually derived EDLVP.

[0103] Regarding the configuration of the average filter, the data processing unit 110 may be configured to continuously, or sometimes, or periodically determine the ventilation frequency VF based on the measurement signal of the ventilation pressure VentP meas .

[0104] It has been found that the reciprocal value of the ventilation frequency VF, that is, the filter size (or filter window) corresponding to 1 / VF, is effective in compensating for the effect of ventilation. In other words, the data processing unit 110 can be configured to calculate the actual average value of the actually derived EDLVP during the time interval related to the ventilation frequency VF for each time point. For example, the time interval may be defined by the reciprocal value of the ventilation frequency VF, or n times that value, that is

Number

[0105] Alternatively, the data processing unit 110 may be configured to calculate the ventilation rate VF by the time interval between two consecutive maximum or minimum values ​​of the actual EDLVP, as already discussed herein.

[0106] Alternatively, instead of a moving average filter, the filter applied may be a high-pass filter having a characteristic cutoff frequency set to eliminate physiologically occurring variations that should be excluded. In particular, the control device may be configured to set the characteristic cutoff frequency of the high-pass filter to a determined ventilation rate VF.

[0107] With regard to the rate level control of the VAD, the signal processing unit 110 of the control device 100 is configured to determine the start and end of systole and diastole, respectively. The implemented value detection algorithm is based on the measured signals of left ventricular pressure (LVP) and / or aortic pressure (AoP), which will be broadly described below. Based on the determined start and end of systole and diastole, respectively, the systolic rate and diastole rate can be calculated accordingly.

[0108] Figure 6A shows diagrams of the left ventricle pressure LVP and the aorta pressure AoP during two cardiac cycles j and j+1 to illustrate the cardiac filling gradient FG, systolic contraction SC, and diastolic relaxation DR. These pressure gradients FG, SC, and DR may be used as characteristic parameters in controlling the rate level of the VAD (Ventricular Adaptive Disorder) (alternatively or additionally).

[0109] As used herein, the term “cardiac cycle” encompasses the dynamic behavior of the heart during a single heartbeat, including, for example, time-dependent changes in blood pressure and ventricular volume. Herein, a heartbeat is defined as beginning with the evocation of an atrial contraction and ending immediately before the next atrial contraction, distinguishing between systole and diastole. The cardiac systole (also called the ejection phase) is the phase between the closure of the mitral valve and the closure of the aortic valve. The cardiac diastole (also called the filling phase) is the phase between the closure of the aortic valve and the closure of the mitral valve for the next cardiac cycle. The frequency with which the heart undergoes a cardiac cycle is known as the heart rate.

[0110] Points 1 through 4 in Figure 6A mark specific characteristic events in each of the two shown cardiac cycles j and j+1, namely mitral valve closure (point 1, CMV), aortic valve opening (point 2, OAV), aortic valve closure (point 3, COV), and mitral valve opening (point 4, OMV). The following discussion is based on cardiac cycle j.

[0111] Therefore, the pressure gradient of the left ventricular pressure (LVP) during the cardiac contraction phase of the cardiac cycle between mitral valve closure (point 1) and aortic valve opening (point 2) is:

number

[0112] The pressure gradient of the left ventricular pressure (LVP) during the diastolic phase of the cardiac cycle between aortic valve closure (point 3, COV) and mitral valve opening (point 4, OMV) is:

number

[0113] Finally, the pressure gradient of the left ventricular pressure (LVP) during the diastolic phase of the cardiac cycle between mitral valve opening in cardiac cycle j (point 4, OMV) and mitral valve closure in the subsequent cardiac cycle j+1 (point 1, CMV) is:

number

[0114] Figures 6B and 6C illustrate the effect of controlling the VAD rate based on monitoring the filling gradient FG as at least one characteristic parameter σ. For this purpose, the data processing unit 110 is configured to calculate the quotient obtained by dividing the difference between the left ventricular pressure value observed at the moment of mitral valve opening in the ending cardiac cycle j, as discussed above, and the left ventricular pressure value observed at the moment of mitral valve closure in the subsequent cardiac cycle j+1, by the time span between them.

[0115] Figure 6B depicts the LVP waveform of a failing heart that is still under load, i.e., not receiving sufficient assistance from the application of a VAD. The left ventricle is stiff instead of relaxing properly, and as a result, blood cannot properly fill the left ventricle. This can be identified by the filling gradient FG (dotted line in Figure 6B) being positively sloped, i.e., greater than zero.

[0116] Figure 6C illustrates the effect of well-tuned cardiac assistance by a VAD, where VAD rate control is based on monitoring the filling gradient FG and the correspondingly tuned VAD rate, ensuring that the amount of assistance the VAD provides to the heart is such that the filling gradient is positive and not negative to avoid negative pressure. Monitoring the filling gradient FG and keeping it close to zero or equal to it is intended to indicate a suitable amount of cardiac assistance to unload a weakened heart and support cardiac recovery.

[0117] Figure 7 further illustrates the effect of cardiac assistance by the pump device 50 on fluctuations in left ventricular pressure LVP and absolute left ventricular volume LVV during a single cardiac cycle, based on the filling gradient FG (Figure 6) as at least one characteristic parameter σ, which is called the characteristic pV loop.

[0118] The effect on the shape and position of the assisting cardiac pV loop correlates with the amount of assistance provided by the VAD, and, for example, with the blood pump rate in the case of an exemplary blood pump. It should be noted that there is no linear relationship between the VAD rate and the blood flow rate produced, and between the assistance provided, since the blood flow rate produced by the VAD pump device is affected by the pressure difference between the VAD's afterload and preload. However, it is broadly true that the amount of assistance increases with increasing the VAD rate.

[0119] The diagram in Figure 7 begins with no VAD support (corresponding to Figure 6B), which is reflected in the tall pV loops (thick lines) located in the center and further to the right of the diagram. As support from the VAD, i.e., the pump device 50, is increased, the center of the spirally connected pV loop waveforms shifts to the left of the diagram, and simultaneously, the area of ​​each pV loop gradually decreases. The area of ​​the pV loops reflects the actual work produced by the heart itself, i.e., the actual load placed on the heart. Thus, Figure 7 shows the unloading of the heart by the pump device 50. The guideline is not to unload the heart with the assistance provided by the VAD. The guideline is to find, maintain, and adjust the actual amount of assistance so that the heart is unloaded to a degree that is just enough to support its recovery.

[0120] This can be done based on the velocity level control proposed herein, using preferred characteristic parameters σ, such as the filling gradient FG, which was examined and explained in relation to Figure 6.

[0121] For completeness, the absolute volume of the left ventricle V is measured using an echocardiography device. LV It is known that monitoring may be beneficial.

[0122] Figure 8 shows the actual pressure difference ΔP between the preload and afterload of an exemplary intravascular rotating blood pump, such as the VAD example used herein. pump And the actual blood pump speed n pump And the blood flow Q through the blood pump pump This is an exemplary diagram showing a set of characteristic curves representing the relationship between [the two points].

[0123] Actual blood flow Q through the blood pump pump Based on the set of characteristic curves, the actual pressure difference ΔP pump and the actual pump speed n pump function Q pump =f(ΔP pump ,n pump ) The actual pressure difference ΔP can be calculated as follows: pump This can be determined by the pressure sensors 30 and 60 in Figure 2. The actual blood pump speed is known to the data processing unit 110, and in particular to the speed command unit 120 and / or motor control unit 130. Thus, the actual blood flow rate Q pump This can be verified by the data processing unit 110. The value ΔP described by the set of characteristic curves shown in Figure 8, which was discussed above. pump Q pump , and n pump The relationships between them can be stored as a lookup table in a memory device within the control device 100, for example, in the read-only memory of the data processing unit 110, or in a memory device on a chip in the blood pump or motor control unit 130.

[0124] Further Embodiments The present invention relates in particular to the following embodiments, as defined in the following numbered sections.

[0125] 1. A control device (100) for a ventricular assist device (VAD) (50) with a settable rate level, wherein the control device (100) measures at least one measurement signal (LVP) associated with the physiological state of the circulatory system of a patient (P) receiving cardiac assistance from the VAD (50). meas The control device (100) includes an input section (101) configured to receive ), and the control device (100) receives at least one measurement signal (LVP meas To derive the actual value (EDLVP;FG) of at least one characteristic parameter of the heart (H) from one or more of the following, and to derive the refined actual value (EDLVP;FG) of at least one characteristic parameter from which physiologically occurring variations have been eliminated. * FG * The control device (100) is configured to provide the updated speed level setting (n VAD set The control device (100) includes an output section (105) configured to output a refined actual value (EDLVP), and the control device (100) has an output section (105) configured to output a refined actual value (EDLVP).* FG * ) and pre-configurable setpoint values ​​(EDLVP set FG set The updated setting value (n) is based on ) VAD set A control device (100) is configured to generate ).

[0126] 2. The control device (100) receives at least one measurement signal (LVP meas Process one or more of the time series of the actual values ​​(EDLVP, FG) and / or the refined actual values ​​(EDLVP * FG * A control device (100) as described in item 1, configured to provide ).

[0127] 3. The control device (100) is configured to process multiple actual values ​​(EDLVP;FG) within a moving time interval, including the current actual value (EDLVP;FG) and further actual historical values, as described in item 1 or 2.

[0128] 4. Refined Actual Values ​​(EDLVP) * FG * ) is a moving average of multiple actual values ​​(EDLVP;FG) and / or at least one measured signal (LVP meas A control device (100) described in any one of items 1 to 3, which is based on one or more moving averages of the following:

[0129] 5. The control device (100) receives at least one measurement signal (LVP meas A control device (100) as described in any one of items 1 to 4, configured to determine respiration or ventilation rate (VF) based on measured signals of ) and / or continuous actual values ​​(EDLVP;FG) and / or ventilation pressure.

[0130] 6. The control device (100) is By applying a moving average filter having a size related to the periodicity of physiologically occurring variations to be excluded or reduced, at least one measured signal (LVP) meas To process one or more of the sequences of the actual values ​​(EDLVP;FG) and / or, By applying a high-pass filter with a characterization cutoff frequency associated with physiologically occurring variations that should be excluded or reduced, at least one measurement signal (LVP) can be filtered. meas A control device (100) described in any one of items 1 to 5, configured to process a sequence of one or more of the following or actual values ​​(EDLVP;FG).

[0131] 7. At least one measurement signal (LVP meas A control device (100) according to any one of items 1 to 6, wherein at least one of the following is at least one pressure in the patient's circulatory system, namely, at least one of the patient's left ventricular pressure (LVP), aortic pressure (AoP), central venous pressure (CVP), pulmonary artery pressure (PAP), and / or ECG signal.

[0132] 8. A control device (100) according to any one of items 1 to 7, wherein at least one characteristic parameter is at least one of the following: a specific value of vascular pressure and / or intracardiac pressure at a given event of the cardiac cycle, or a pressure gradient (SC, DR, FG) between two intracardiac pressures at two specific events in a single cardiac cycle.

[0133] 9. At least one characteristic parameter is the filling gradient of left ventricular pressure (LVP) during the diastolic phase of the cardiac cycle between mitral valve opening (OMV) and mitral valve closure (CMV).

number

number

number

[0134] 10. The control device (100) is To calculate the actual heart rate based on the time interval between the occurrence of at least one characteristic parameter (EDLVP;FG) and its subsequent recurrence, and / or, A control device (100) described in any one of items 1 to 9, further configured to calculate the actual blood flow generated by the VAD(50).

[0135] 11. The control device (100) is a refined real value (EDLVP * FG * ) and the corresponding setpoint value (EDLVP set FG set Whenever a predetermined difference exists between (n) and the updated setting value, VAD set ) is configured to generate, and / or The control device (100) uses a new refined real value (EDLVP) * FG * When ) is generated, the setting value (n VAD set ) is configured to update, and / or The control device (100) sets the set value (n VAD set ) is configured to be updated periodically at a predetermined frequency. A control device (100) described in any one of items 1 through 10. 12. The control device (100) is a refined real value (EDLVP * FG *) to be displayed on the display (210), and / or refined actual values ​​(EDLVP * A control device (100) according to any one of items 1 to 10, configured to provide the output section (104) of the control device (100).

[0136] 13. A cardiac assist VAD (50) comprising a control device (100) as described in any one of items 1 to 12, VAD(50) is preferably a non-pulsating rotary blood pump. More preferably, the blood pump is catheter-based, Most preferably, the VAD(50) is a low-inertia device characterized by one or more of the following: the moving, especially rotating, parts of the VAD, e.g., rotor or impeller, having low mass by being made of a low-weight material, e.g., plastic; the drive means, such as an electric motor, being located near, preferably very close to, most preferably adjacent to, the motor-driven parts, e.g., rotor or impeller, and, if catheter-based, preferably without a rotary drive cable; the coupling or connection of the motor to the motor-driven parts, e.g., rotor or impeller, e.g., having a short shaft; and all the moving, especially rotating, parts of the VAD being small in diameter; the VAD(50).

[0137] 14. A method for obtaining a refined actual value of at least one characteristic parameter of the heart (H), At least one measured signal (LVP) associated with the physiological state of the patient's (P) circulatory system meas ) receiving, At least one measurement signal (LVP meas Derive the actual value (EDLVP;FG) of at least one characteristic parameter of the heart (H) from one or more of the following: Actual value (EDLVP; FG) or at least one measurement signal (LVP) meas) Process one or more of the following to obtain refined actual values ​​(EDLVP) in which physiologically occurring variability is eliminated or reduced. * FG * A method that includes providing )

[0138] 15. A ventricular assist device with a settable rate level, a method for controlling the rate level of a VAD(50), Obtain a refined actual value of at least one characteristic parameter of the heart (H) by the method described in item 14, Refined actual values ​​(EDLVP) * FG * ) and pre-configurable setpoint values ​​(EDLVP set FG set Based on this, the updated speed level setting (n VAD set A method that includes generating ).

[0139] 16. At least one measurement signal (LVP meas Process one or more of the time series of the actual values ​​(EDLVP, FG) and refine the actual values ​​(EDLVP * FG * The method of item 14, further comprising providing ).

[0140] 17. The method of item 14 or 15, further comprising processing multiple actual values ​​(EDLVP;FG) within a moving time interval, including the current actual value (EDLVP;FG) and further actual historical values.

[0141] 18. At least one measurement signal (LVP meas The method according to any one of items 14 to 17, further comprising determining the patient's (P) respiratory rate or ventilation rate (VF) based on the measured signals of ) and / or continuous actual values ​​(EDLVP;FG) and / or ventilation pressure.

[0142] 19. By applying a moving average filter having a size related to the periodicity of physiologically occurring variations to be reduced or eliminated, at least one measured signal (LVP meas Processing a sequence of one or more of the following or actual values ​​(EDLVP;FG), and / or By applying a high-pass filter with a characterization cutoff frequency associated with physiologically occurring variations to be excluded or reduced, at least one measurement signal (LVP) can be filtered. meas Processing a sequence of one or more of the following or the actual value (EDLVP;FG), The method described in any one of items 14 through 18, further including the method described in any one of items 14 through 18.

[0143] 20. At least one measurement signal (LVP meas The method according to any one of items 14 to 19, wherein at least one of the following is at least one pressure in the patient's circulatory system, namely, at least one of the patient's left ventricular pressure (LVP), aortic pressure (AoP), central venous pressure (CVP), pulmonary artery pressure (PAP), and / or ECG signals.

[0144] 21. The method according to any one of items 14 to 20, wherein at least one characteristic parameter is at least one of the following: a specific value of vascular pressure and / or intracardiac pressure at a given event of a cardiac cycle, or a pressure gradient between two intracardiac pressures at two specific events in a single cardiac cycle.

[0145] 22. At least one characteristic parameter is the filling gradient of left ventricular pressure (LVP) during the diastolic phase of the cardiac cycle between mitral valve opening (OMV) and mitral valve closure (CMV).

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[0146] 23. The method according to any one of items 14 to 21, further comprising calculating the actual heart rate based on the time interval between the occurrence of at least one actual value (EDLVP;FG) and a subsequent recurrence, and / or calculating the actual blood flow produced by the VAD(50).

[0147] 24. Refined Actual Values ​​(EDLVP) * FG * ) and the corresponding setpoint value (EDLVP set FG set Whenever a predetermined difference exists between ) and the set value (n VAD set ) to update, and / or, New refined actual values ​​(EDLVP) * FG * When the setting value (n VAD set ) to update, and / or Set value (n VAD set ) to be updated periodically at a predetermined frequency. The method described in any one of items 14 through 23, further including the method described in any one of items 14 through 23.

[0148] 25. A control device (100) as described in any one of items 1 to 12 or a method as described in any one of items 14 to 24, wherein the physiologically occurring fluctuations to be eliminated or reduced correlate with at least one of the following: pressure fluctuations in the patient's (P) thoracic cavity, pressure fluctuations caused by the patient's (P) autonomous or assisted breathing, pressure fluctuations caused by an intra-aortic balloon pump in the patient's aorta, pressure fluctuations caused by an external counterpulsation therapy applied to the patient, or pressure fluctuations caused by a change in the patient's position, such as the Trendelenburg position.

Claims

1. A control device (100) for a ventricular assist device, VAD (50), capable of setting a speed level, wherein the control device (100) is for a patient (P) receiving heart assistance by the VAD (50), and is related to at least one measurement signal (LVP ｍｅａｓ ) of the physiological state of the circulatory system, and includes an input unit (101) configured to receive the signal; the control device (100) is based on one or more of the at least one measurement signal (LVP ｍｅａｓ ) to derive the actual value (EDLVP; FG) of at least one characteristic parameter of the heart (H), and to provide a refined actual value (EDLVP ＊ ; FG ＊ ) of the at least one characteristic parameter in which the effect of physiologically occurring variations is excluded or reduced; the control device (100) further includes an output unit (105) configured to output an updated set value (n ＶＡＤ ｓｅｔ ) of the speed level, and the control device (100) is configured to generate the updated set value (n ＊ ; FG ＊ ) based on the refined actual value (EDLVP ｓｅｔ ; FG ｓｅｔ ) and a presettable set point value (EDLVP ＶＡＤ ｓｅｔ ), and the at least one characteristic parameter includes a pressure gradient (SC, DR, FG) between two intracardiac pressures at two specific events during one cardiac cycle, that is, the difference in left ventricular pressure values observed at the moment of mitral valve closure and the moment of aortic valve opening, divided by the time span between them, and is defined as a positive quotient of systolic contraction (SC). The control device (100) is characterized in that it includes such a pressure gradient.

2. A control device (100) according to claim 1, wherein the at least one measurement signal (LVP ｍｅａｓ ) processing one or more of the above and the actual value (EDLVP, FG) to process the refined actual value (EDLVP ＊ FG ＊ A control device (100) characterized by being configured to provide ).

3. A control device (100) according to claim 1 or 2, characterized in that it is configured to process a plurality of actual values ​​(EDLVP; FG) within a moving time interval including a current actual value (EDLVP; FG) and further actual historical values.

4. A control device (100) according to any one of claims 1 to 3, wherein the refined actual value (EDLVP ＊ FG ＊ A control device (100) characterized in that the function is a moving average of multiple actual values ​​(EDLVP; FG).

5. A control device (100) according to any one of claims 1 to 4, wherein the refined actual value (EDLVP ＊ FG ＊ ) is the at least one measurement signal (LVP ｍｅａｓ A control device (100) characterized by being based on a moving average of ).

6. A control device (100) according to any one of claims 1 to 5, wherein the at least one measurement signal (LVP ｍｅａｓ A control device (100) is configured to determine the respiratory or respiratory rate (VF) based on at least one of the following: the actual historical value (EDLVP; FG) and the ventilation pressure measurement signal.

7. A control device (100) according to any one of claims 1 to 6, By applying a moving average filter having a size related to the periodicity of the physiologically occurring fluctuations to be excluded, the at least one measurement signal (LVP ｍｅａｓ The process involves processing a sequence of one or more of the above-mentioned signals (LVP) or the actual value (EDLVP; FG), and applying a high-pass filter having a characterization cutoff frequency associated with the physiologically occurring variation to be excluded, thereby processing the sequence of at least one of the measured signals (LVP) ｍｅａｓ A control device (100) characterized by being configured to perform at least one of the following: processing one or more of the above or the above actual value (EDLVP; FG).

8. A control device (100) according to any one of claims 1 to 7, wherein the at least one measurement signal (LVP ｍｅａｓ A control device (100) characterized in that at least one of the following is at least one pressure in the patient's circulatory system, namely, at least one of left ventricular pressure (LVP), aortic pressure (AoP), central venous pressure (CVP), and pulmonary artery pressure (PAP).

9. A control device (100) according to any one of claims 1 to 8, wherein the at least one measurement signal (LVP ｍｅａｓ A control device (100) characterized in that at least one of the following is the patient's ECG signal.

10. A control device (100) according to any one of claims 1 to 9, wherein the at least one characteristic parameter is at least one of a specific value of vascular pressure at a predetermined event of the cardiac cycle, a specific value of intracardiac pressure at a predetermined event of the cardiac cycle, and a pressure gradient (SC, DR, FG) between two intracardiac pressures at two specific events in one cardiac cycle, wherein the pressure gradient (SC, DR, FG) is a filling gradient (FG) or a diastolic relaxation pressure gradient (DR).

11. A control device (100) according to claim 10, wherein the filling gradient (FG) is the filling gradient of left ventricular pressure (LVP) during the diastolic phase of the cardiac cycle between mitral valve opening (OMV) and mitral valve closure (CMV). [Math 1] And this is [Math 2] Defined as such, the control device (100) controls the filling gradient. [Math 3] The updated setting value (n) is positive and close to zero or maintained there. ＶＡＤ ｓｅｔ A control device (100) characterized by being configured to generate ).

12. A control device (100) according to claim 10, wherein the filling gradient (FG) is the filling gradient of left ventricular pressure (LVP) during the diastolic phase of the cardiac cycle between mitral valve opening (OMV) and mitral valve closure (CMV). [Math 4] And this is [Math 5] Defined as such, the control device (100) controls the filling gradient. [Math 6] The updated setting value (n) is set to zero or kept at zero. ＶＡＤ ｓｅｔ A control device (100) characterized by being configured to generate ).

13. A control device (100) according to any one of claims 1 to 12, The actual heart rate is determined based on the time interval between the occurrence and subsequent recurrence of one of the aforementioned at least one characteristic parameter (EDLVP; FG), A control device (100) is further configured to calculate at least one of the actual blood flow rate generated by the VAD (50) and .

14. A control device (100) according to any one of claims 1 to 13, wherein the refined actual value (EDLVP ＊ FG ＊ ) and the aforementioned setpoint value (EDLVP ｓｅｔ FG ｓｅｔ Whenever a predetermined difference exists between (n) and the updated setting value, ＶＡＤ ｓｅｔ To generate ) New refined actual values ​​(EDLVP) ＊ FG ＊ When the above setting value (n ＶＡＤ ｓｅｔ ) to update, and The aforementioned setting value (n ＶＡＤ ｓｅｔ It is configured to perform at least one of the following: updating ) periodically at a predetermined frequency. A control device (100) characterized by the following.

15. A control device (100) according to any one of claims 1 to 13, wherein the refined actual value (EDLVP ＊ FG ＊ ) to be displayed on the display (210), and the refined actual value (EDLVP ＊ FG ＊ A control device (100) is configured to perform at least one of the following: providing a signal at an output unit (104).

16. A cardiac assist device (VAD) (50) comprising a control device (100) according to any one of claims 1 to 15.

17. A VAD (50) according to claim 16, characterized in that it is a non-pulsating rotary blood pump.

18. A VAD (50) according to claim 17, wherein the blood pump is catheter-based.

19. A VAD (50) according to any one of claims 16 to 18, A VAD (50) is a low-inertia device characterized by having one or more of the following features: the moving or rotating parts of the VAD have low mass by being made of a low-weight material; the drive means are located near or adjacent to the motor-driven parts; the coupling or connection between the motor-driven parts and the motor is short; and all the moving or rotating parts of the VAD are small in diameter.

20. A VAD (50) according to claim 19, characterized in that at least one of the moving part, the rotating part, and the part driven by the motor is a rotor or an impeller.

21. A VAD (50) according to claim 19 or 20, wherein the low-weight material is plastic.

22. A VAD (50) according to any one of claims 19 to 21, wherein the driving means is an electric motor.

23. A VAD (50) according to any one of claims 19 to 22, wherein the VAD (50) is catheter-based, the driving means is characterized in that it does not have a driveable rotating cable.

24. A VAD (50) according to any one of claims 19 to 23, wherein the coupling portion or the connecting portion is an axis.

25. A method for obtaining a refined actual value (EDLVP*; FG*) of at least one characteristic parameter of the heart (H), At least one measurement signal (LVP) associated with the physiological state of the patient's (P) circulatory system ｍｅａｓ ) receiving, The at least one measurement signal (LVP ｍｅａｓ Deriving an actual value (EDLVP;FG) of at least one characteristic parameter of the heart (H) based on one or more of the following: the at least one characteristic parameter includes a pressure gradient (SC, DR, FG) between two intracardiac pressures at two specific events in a single cardiac cycle, i.e., a systolic pressure gradient (SC) defined as a positive quotient obtained by dividing the difference in left ventricular pressure observed at the moment of mitral valve closure and the moment of aortic valve opening by the time span between these two points. The actual value (EDLVP; FG) or the at least one measurement signal (LVP ｍｅａｓ ) Process one or more of the above to obtain refined actual values ​​(EDLVP) in which physiologically occurring variations are eliminated or reduced. ＊ FG ＊ A method characterized by providing ).

26. The method according to claim 25, wherein the at least one measurement signal (LVP ｍｅａｓ The sequence of one or more of the above or the actual values ​​(EDLVP, FG) is processed to refine the actual values ​​(EDLVP ＊ FG ＊ A method characterized by further comprising providing ).

27. A method according to claim 25 or 26, further comprising processing a plurality of actual values ​​(EDLVP; FG) within a moving time interval, including a current actual value (EDLVP; FG) and further actual historical values.

28. A method according to any one of claims 25 to 27, wherein the at least one measurement signal (LVP ｍｅａｓ A method further comprising determining the respiration or ventilation rate (VF) of the patient (P) based on one or more of the following: ), continuous actual values ​​(EDLVP; FG), and ventilation pressure measurement signals.

29. A method according to any one of claims 25 to 28, wherein the at least one measurement signal (LVP) is reduced by applying a moving average filter having a size related to the periodicity of the physiologically occurring fluctuations to be excluded or reduced. ｍｅａｓ Processing a sequence of one or more of the above or the actual value (EDLVP; FG), By applying a high-pass filter having a characterization cutoff frequency associated with the physiologically occurring variation to be excluded or reduced, the at least one measurement signal (LVP ｍｅａｓ A method characterized by further comprising processing one or more of the above or the sequence of the actual value (EDLVP; FG).

30. A method according to any one of claims 25 to 29, wherein the at least one measurement signal (LVP ｍｅａｓ A method characterized in that at least one of the following is at least one pressure in the patient's circulatory system, namely, at least one of left ventricular pressure (LVP), aortic pressure (AoP), central venous pressure (CVP), and pulmonary artery pressure (PAP).

31. A method according to any one of claims 25 to 29, wherein the at least one measurement signal (LVP ｍｅａｓ A method characterized in that at least one of the following is the patient's ECG signal.

32. A method according to any one of claims 25 to 31, wherein the at least one characteristic parameter further includes at least one of a specific value of vascular pressure at a predetermined event of a cardiac cycle, a specific value of intracardiac pressure at a predetermined event of a cardiac cycle, and a pressure gradient (SC, DR, FG) between two intracardiac pressures at two specific events in a single cardiac cycle, wherein the pressure gradient (SC, DR, FG) is a filling gradient (FG) or a diastolic relaxation gradient (DR).

33. A method according to any one of claims 25 to 32, wherein the at least one characteristic parameter is the filling gradient of left ventricular pressure (LVP) during the diastolic phase of the cardiac cycle between mitral valve opening (OMV) and mitral valve closure (CMV). [Number 7] (FG) is this [Number 8] A method characterized by being configured to be defined as follows.

34. A method according to any one of claims 25 to 32, wherein the at least one characteristic parameter is the filling gradient of left ventricular pressure (LVP) during the diastolic phase of the cardiac cycle between mitral valve opening (OMV) and mitral valve closure (CMV). [Number 9] (FG) is this [Number 10] A method characterized by being defined as follows.

35. A method according to any one of claims 25 to 34, comprising calculating the actual heart rate based on the time interval between the occurrence of one of the at least one actual values ​​(EDLVP; FG) and its subsequent recurrence, A method further comprising at least one of the following: calculating the actual blood flow generated by a ventricular assist device, or a VAD (50).

36. Updated setting values ​​(n) for controlling the speed level of a ventricular assist device with adjustable speed level, VAD(50) ＶＡＤ ｓｅｔ A method for obtaining ) Obtaining a refined actual value of at least one characteristic parameter of the heart (H) by the method described in any one of claims 25 to 35, The refined actual value (EDLVP ＊ FG ＊ ) and pre-configurable setting point values ​​(EDLVP ｓｅｔ Based on the updated setting value (n) of the speed level, ＶＡＤ ｓｅｔ A method characterized by generating ) and including .

37. The method according to claim 36, wherein the set value (n VAD set) is updated whenever a predetermined difference exists between the refined actual value (EDLVP*; FG*) and the set point value (EDLVP set; FG set), The setting value (n VAD set) is updated when a new, refined actual value (EDLVP*; FG*) is generated. A method characterized by further comprising at least one of the following: periodically updating the set value (n VAD set) at a predetermined frequency.

38. A method according to any one of claims 25 to 37, characterized in that the physiological fluctuations to be eliminated or reduced correlate with at least one of the following: pressure fluctuations within the thoracic cavity of the patient (P), pressure fluctuations caused by the patient (P)'s autonomous or assisted respiration, pressure fluctuations caused by an intra-aortic balloon pump in the patient's aorta, pressure fluctuations caused by an external counterpulsion therapy applied to the patient, or pressure fluctuations caused by changes in the patient's body position.

39. A control device (100) according to any one of claims 1 to 15, wherein the physiological fluctuations to be eliminated or reduced are correlated with at least one of the following: pressure fluctuations in the thoracic cavity of the patient (P), pressure fluctuations caused by the patient (P)'s autonomous or assisted breathing, pressure fluctuations caused by an intra-aortic balloon pump in the patient's aorta, pressure fluctuations caused by an external counterpulsion therapy applied to the patient, and pressure fluctuations caused by changes in the patient's body position.

40. A control device (100) according to claim 39, characterized in that the change in the patient's body position is a change to the Trendelenburg position.

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