blood pump

Abstract

It is an object of the present invention to provide an improved control method and corresponding improved control device for an intravascular blood pump. [Solution] The present invention relates to a control device 100 for controlling blood flow in an intravascular blood pump 50, wherein the blood pump 50 comprises a pump unit 52 having a drive unit 51 for driving the pump unit 52 and is configured to transport blood from a blood inlet 54 towards a blood outlet 56, the control device 100 is configured to operate the blood pump 50 in a selectable zero flow control mode, and a blood flow command signal is selected, the control device 100 comprises a first control device 401 and a second control device 402, the first control device 401 is configured to control the blood flow by adjusting a speed command signal to the drive unit 51, and the second control device 402 is configured to control the drive speed of the drive unit 51.

Description

[Technical Field]

[0001] The present invention relates in detail to a vascular pump, which is an intravascular blood pump for percutaneous insertion into a patient's blood vessels. More specifically, the present invention relates to a specific control method for a percutaneously insertable blood pump, and a corresponding control device, and further to a system comprising the control device and the blood pump. The present invention is configured for intravascular blood pumps and is particularly useful for intravascular blood pumps, but is less relevant to larger blood pumps such as VADs that are placed outside the patient's heart, such as being implanted in the pleural cavity, rather than being placed inside a blood vessel or the heart. [Background technology]

[0002] Ventricular assist devices (VADs) are used to support the function of a patient's heart, either as left ventricular assist devices (LVADs) or right ventricular assist devices (RVADs). Typical VADs are connected to the patient's heart via appropriate conduits and implanted in the patient's thoracic cavity, outside the heart. Intravascular blood pumps for percutaneous insertion typically consist of a catheter and pump unit, inserted into the blood vessels through an access route, such as through the aorta into the left ventricle, and further into the patient's heart. The pump unit may be located at the distal end of the catheter and comprises a blood flow inlet and outlet, with blood flow through the catheter created, for example, by the rotor or impeller of the pump unit. For example, a cannula may extend through the aortic valve, where the blood flow inlet is located at the distal end of the cannula within the left ventricle and the blood flow outlet is located at the proximal end of the cannula within the aorta. By creating blood flow, it overcomes the pressure difference between the inlet and outlet.

[0003] An important aspect of intravascular blood pumps (hereinafter also simply referred to as "blood pumps") is, among other things, the removal of the intravascular blood pump from the patient and, by extension, confirmation that innate cardiac function has recovered. This can be done, for example, by sufficiently reducing the degree of assistance provided by the blood pump, so that the blood pump can finally be removed after it has been determined that the heart has fully recovered. This aspect, namely determining the precise timing for removal, is less critical for larger VADs, such as those typically implanted in the patient's pleural cavity and designed for long-term use.

[0004] To date, as long as an intravascular blood pump is implanted, there are no known physical signals that adequately indicate the state of cardiac recovery. The blood pump assists the heart, but it is impossible to know the function of the heart without assistance. Furthermore, when the blood pump is switched off, regurgitation occurs through the cannula, making it impossible to know the function of the heart without assistance. Regurgitation is a major problem with intravascular blood pumps. This is because the blood pump, or more specifically the pump cannula, extends through cardiac valves such as the aortic valve, creating an open pathway through the valve and causing regurgitation into the heart when the blood pump is not operating. Such outflow does not usually occur with extravascular devices. This is because extravascular devices do not extend through cardiac valves but bypass them, such as VADs placed outside the heart in the thoracic cavity.

[0005] In current technology, the latest pump speed setting is manually reduced stepwise by a physician, for example, one level at a time, based on the experience of a specialist. After the pump speed is reduced, mean aortic pressure is monitored. Some facilities perform ultrasound-based left ventricular volume assessment and continuous cardiac output measurement. If the mean aortic pressure remains stable, it is considered that the heart can take over the work of the blood pump. However, if the mean aortic pressure decreases, it is considered that the heart still requires further assistance, and therefore the pump speed needs to be increased again. Furthermore, before removing the blood pump, a so-called on / off technique is applied. In this way, the pump speed is significantly reduced, for example, over several hours, during which the patient's physiological state and ventricular expansion are particularly observed, which is based, for example, on ultrasound-guided cardiac (ECHO) measurements and / or ventricular angiography. ECHO can provide information about the heart, such as its size and shape, for example, it can provide information on the quantification of internal ventricular size and pumping capacity, enabling the calculation of cardiac output, ejection fraction, and cardiac diastolic function. Ventricular angiography involves injecting a bleeding agent into the ventricles of the heart to measure the amount of blood being pumped. The measurements achieved by ventricular angiography are ejection fraction, stroke volume, and cardiac output.

[0006] If the blood pump is switched off and the heart is still functioning poorly, the unassisted ventricles will expand significantly, resulting in insufficient blood being pumped out of the ventricles during systole, thereby increasing the left ventricular end-diastolic volume and end-diastolic pressure. In other words, the reduced pumping speed puts a strain on the heart, which can be equivalent to a sudden overload on a heart that has not yet recovered. This could potentially set back treatment by several days.

[0007] Therefore, the practical monitoring process before removing the blood pump is, to varying degrees, a trial-and-error procedure, where the pump speed is further reduced if the patient's condition remains stable, and increased again if the patient's condition deteriorates. [Overview of the project] [Problems that the invention aims to solve]

[0008] The object of the present invention is to provide an improved control method for an intravascular blood pump and a corresponding improved control device, and furthermore, a system comprising this control device and an intravascular blood pump, wherein the vascular pump is operated in such a way that it can be confirmed that it is better assessing the state of cardiac recovery. [Means for solving the problem]

[0009] This objective is achieved by the features of each independent claim. Advantageous embodiments and alternative variations are defined in their respective dependent claims.

[0010] For clarity, the following definitions apply herein: The term "cardiac characteristic parameters" is understood to refer to specific values ​​derived from physiological signals that can represent characteristics of the state of the heart, such as load-related parameters like overload or no load, and / or physiological states like frailty, health, or recovery.

[0011] The "human circulatory system" is the organ system that enables the circulation of blood. 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" that goes through the lungs, where oxygen is delivered to the blood; and the systemic circulation, which is the "loop" that goes through the rest of the body to provide oxygen-rich blood.

[0012] The improvements disclosed herein relate to blood pumps having configurable blood flow levels. For example, in the case of a rotary blood pump, the “configurable blood flow level” may be a discrete blood flow level or a continuously configurable blood flow level within a range defined by a minimum blood flow and a maximum blood flow.

[0013] The basic idea of ​​the control devices and corresponding control methods for controlling intravascular blood pumps proposed herein is to realize a mode in which the latest blood flow through the blood pump can be kept very low, preferably zero, compared to its blood flow output capacity. Preferably, the blood flow through the blood pump is maintained between 0 L / min and 1 L / min, more preferably between 0 L / min and 0.5 L / min, between 0 L / min and 0.2 L / min, or even between 0 L / min and 0.1 L / min. Most preferably, the blood flow through the blood pump is maintained at near zero flow. In this case, the blood pump is controlled so as not to produce either positive or negative blood flow. This mode of operation is referred to herein as the “zero flow control mode”. For example, zero flow rate can be established and / or maintained by controlling the drive unit of the blood pump, such as a motor, and more specifically by controlling the latest drive speed of the drive unit, such as a motor, and thereby controlling the flow rate, so that only the latest pressure difference between the blood inlet and blood outlet of the blood pump is compensated.

[0014] In this context, "zero flow rate" should be understood as zero flow rate or very low blood flow. Since the purpose of zero flow rate control mode is to obtain information about the cardiac recovery status, implementing a very low blood flow may suffice. In this context, low blood flows such as a maximum of 0.1 L / min, a maximum of 0.2 L / min, or even a maximum of 0.5 L / min will be considered "zero flow rate." In all cases, "zero flow rate" will not be negative. In other words, zero flow rate does not allow any backflow through the blood pump.

[0015] In this context, an intravascular blood pump for percutaneous insertion comprises a catheter and a pump unit, which are inserted into the patient's heart via a blood vessel, for example, through the aorta into the left ventricle. The pump unit comprises a blood flow inlet and a blood flow outlet, and a cannula, and a drive unit for driving the pump unit creates blood flow through this cannula. For example, the pump unit may have a rotor or impeller driven by a drive unit, for example, a motor, which transports blood from the blood flow inlet to the blood flow outlet. For example, the cannula may extend through the aortic valve, where the blood flow inlet is located at the distal end of the cannula in the left ventricle and the blood flow outlet is located at the proximal end of the cannula in the aorta. The intravascular blood pump can have a maximum outer diameter ranging from approximately 12 French (F) (approximately 4 mm) to approximately 21 French (F) (approximately 7 mm), which are, for example, 12F (approximately 4 mm), 18F (approximately 6 mm), or 21F (approximately 7 mm), and this is typically the maximum outer diameter of the pump unit. The catheter can have an outer diameter less than the outer diameter of the pump unit, for example, 9F (approximately 3 mm).

[0016] Natural cardiac function creates a pressure difference, for example, between the aorta and the left ventricle. For positive blood flow to be created, the blood pump must overcome this pressure difference. If this is not the case, that is, if the pressure created by the blood pump is too low, the existing pressure difference between the aorta and the left ventricle will cause backflow into the left ventricle.

[0017] By applying zero flow control mode, the blood pump assists the heart with little to no assistance, thereby advantageously avoiding backflow; in other words, the blood pump does not allow backflow of blood. For example, in the case of left ventricular assistance, during cardiac diastole, the blood pump does not allow backflow of blood, such as blood returning from the aorta to the left ventricle.

[0018] By applying zero flow control mode, the drive units of the blood pump, such as the rotor or impeller, will still spin. Therefore, the risk of thrombus formation is reduced by the continuously moving parts.

[0019] The zero-flow operation mode is set so that the assistance provided to the heart by the blood pump is essentially zero. "Essentially zero" means that any continuous blood flow must be at least negligible and certainly not negative, meaning that the blood pump does not allow any backflow through it.

[0020] In zero-flow operation mode, the entire task of overcoming the pressure difference between the pressure in an assisted ventricle (such as the left ventricle) and the pressure in an adjacent blood vessel (such as the aorta) is performed solely by the heart. In this way, zero-flow operation mode allows monitoring of one or more appropriate characteristic parameters of the heart that can be used or interpreted as indicators of the state of cardiac recovery.

[0021] Preferably, the blood flow of the blood pump is associated with, for example, the driving speed of a drive unit such as a motor, the current supplied to the drive unit, and / or the pressure difference between the inlet and outlet of the blood pump. This association may be stored in memory, for example, in a reference table, as will be described in more detail later. That is, the command signal value may be stored in the memory of the control device or in memory within the blood pump that is accessible by the control device.

[0022] The first aspect is the blood flow Q of an intravascular blood pump for percutaneous insertion into a patient's blood vessel. pump A control device is provided for controlling (t). The blood pump comprises a pump unit and a drive unit for driving the pump unit, which is configured to transport blood from the blood inlet to the blood outlet. The control device is configured to operate the blood pump in a selectable zero flow control mode, where the blood flow command signal Q pumpset (t) is selected. The control device includes a first control device and a second control device. Here, the first control device adjusts the speed command signal n for the drive unit pump set to control the blood flow Q pump (t) by adjusting, and the second control device is configured to control the driving speed n of the drive unit pump (t). More specifically, the control device is particularly configured to control an intravascular blood pump, or more generally, is configured to control a low-inertia device as will be described in more detail later.

[0023] Preferably, the intravascular blood pump includes a cannula between a blood flow inlet and a blood flow outlet, and the blood flow through the cannula is created by a pump unit. During operation, the cannula can extend through, for example, the aortic valve, during which the blood flow inlet is disposed within the left ventricle and the blood flow outlet is disposed within the aorta.

[0024] For example, the controlled blood flow can be made constant. By compensating the latest pressure difference between the blood flow inlet and the blood flow outlet, the actual blood flow through the blood pump becomes zero flow. That is, in the zero-flow control mode, by controlling the blood flow through the control of the driving speed, the influence of the latest pressure difference between the blood flow outlet and the blood flow inlet is weakened.

[0025] Preferably, the first control device is configured to determine the speed command signal n based on the difference ΔQ between the blood flow command signal Q pump set (t) and the blood flow Q pump (t). In other words, the first control device is configured to compare the actual blood flow Q pump set (t) with the blood flow command signal Q pump set (t) for the purpose of determining the speed command signal n pump (t). pump set (t).

[0026] Preferably, the second control device supplies the drive current I to the drive unit. pump By adjusting (t), the drive speed n pump (t) is configured to control the drive unit. For example, the drive unit may include a motor, specifically an electric motor, and the drive current to be controlled may be the motor current supplied to the motor. Thus, in the case of a rotary drive unit, the command speed signal n of the drive unit pump set (t) and set drive speed n pump set (t) may be the rotational speed. The motor may be located within the pump unit and may be directly or indirectly coupled to the impeller, for example, by mechanical connection or magnetic coupling.

[0027] Preferably, the first and second control devices are part of a cascade control system, where the first control device is an external control device and the second control device is an internal control device. The external control device may be embedded in an external control loop and can manage the blood flow generated by the blood pump by comparing the blood flow command signal with the generated blood flow and by setting the setpoint of the internal control loop, i.e., the blood pump speed command signal. The internal control device is part of an internal control loop and can control the speed of the blood pump by adjusting the motor current accordingly.

[0028] Preferably, the control device controls blood flow Q over a predetermined zero flow control time. pump It is configured to control (t).

[0029] For example, a predetermined zero-flow control time may be set to last for a portion of one cardiac cycle of the assisted heart. In other words, the zero-flow control mode is simply applied for a short period of time "within a beat". In this example, the predetermined zero-flow time is preferably shorter than the duration of the cardiac beating cycle. In this way, information about the heart's recovery status can be collected without overloading the heart in any way, because the duration of time without assistance to the heart is kept to the shortest possible.

[0030] For example, a predetermined zero-flow control time may be set to last for at least one complete cardiac cycle or for a predetermined number of complete, consecutive cardiac cycles.

[0031] Preferably, the control device is configured to synchronize the zero-flow control time with the occurrence of at least one characteristic cardiac cycle event. For example, the start and / or end of the zero-flow control time are synchronized with the occurrence of at least one characteristic cardiac cycle event. In particular, the start and end of the zero-flow control time may be synchronized with the occurrence of two characteristic cardiac cycle events. In this way, the zero-flow control mode can be set to match the time interval of the cardiac cycle, where specific characteristic parameters of the heart can provide particularly useful information that directly or indirectly indicates the state of cardiac recovery.

[0032] For example, a characteristic cardiac cycle event may be aortic valve opening or aortic valve closing. For instance, a control device may be configured to detect aortic valve opening by one of the following: the presence of a state of equilibrium in left ventricular pressure or aortic pressure, the occurrence of an R wave on an electrocardiogram, an ECG, or a signal sent from the patient with the assisted heart.

[0033] Furthermore, the characteristic cardiac cycle event may be mitral valve opening, mitral valve closing, or the occurrence of end-diastolic left ventricular pressure.

[0034] Preferably, the control device is configured to monitor the values ​​of one or more characteristic cardiac parameters. That is, the control device may be configured to monitor one or more characteristic cardiac parameters in the zero-flow control mode each time the zero-flow control mode is applied.

[0035] Preferably, the control device is configured to operate the intravascular blood pump periodically or irregularly in zero flow control mode. The periodic or irregular application of zero flow control mode is performed over a predetermined period, for example, from a portion of one cardiac cycle to up to several days.

[0036] Preferably, the control device is configured to identify trends in the values ​​of one or more characteristic cardiac parameters being monitored. These trends in one or more characteristic cardiac parameters can be used as an indicator of the state of cardiac recovery, or to assist regardless of whether recovery is progressing. This trend can be shown to a physician via the control device's user interface, enabling the physician to make decisions regarding the state of cardiac recovery.

[0037] For example, at least one characteristic parameter of the heart may be arterial blood pressure, measured each time a zero-flow operating mode is established. By applying the zero-flow control mode, arterial blood pressure may decrease. If the pressure drop reaches a limit or shows a limiting decrease, it is indicated that the heart has not recovered and therefore the blood pump cannot be removed. In another example, in zero-flow control mode, arterial blood pressure may remain stable, i.e., only showing a small pressure drop. In such cases, it may be considered that the heart has recovered sufficiently and the blood pump can be removed.

[0038] Preferably, at least one characteristic cardiac parameter is: pulsatile arterial pressure | max -AOP| min , mean arterial pressure, cardiac contractility dLVP(t) / dt| max, cardiac relaxation dLVP(t) / dt| min It is at least one of the following: heart rate (HR).

[0039] The control device uses a sensor to determine blood flow Q pump (t) to measure blood flow Q pump (t) may be configured to calculate or estimate. For example, the pressure difference between the blood flow outlet and the blood flow inlet may be determined by pressure sensors located at the inlet and outlet of the blood pump, i.e., by a pressure sensor that captures the subsequent load of the blood pump and a pressure sensor that captures the preload of the blood pump. The blood pump may also include, or in addition to, a single sensor configured to measure the pressure difference only in a direct manner. Furthermore, in an alternative configuration, the pressure difference between the blood flow outlet and the blood flow inlet may be estimated, measured, or calculated.

[0040] Blood flow Q pump Instead of measuring (t), use a reference table to measure blood flow Q pump (t) may be determined, and this reference table can represent the relationship between blood flow, drive speed, and at least one of the pressure difference between the blood flow outlet and the blood flow inlet and the drive current supplied to the drive unit. Such a reference table may include a set of characteristic curves representing each relationship, which is, for example, a set of curves, each corresponding to a specific pump speed. It will be recognized that other suitable reference tables may also be used, and that the values ​​in the reference tables may be given in a variety of units.

[0041] Data for use in reference tables, such as motor current and blood flow, can be recorded in a test bench assembly by operating a blood pump in a fluid at a given motor speed and a predetermined pump load (pressure difference between the inlet and outlet), while recording the flow produced by the pump. While the motor current and blood flow are being recorded, the pump load may increase over time, for example, from zero load (no pressure difference between the blood flow inlet and outlet, i.e., maximum flow rate) to maximum load (the pump not functioning, i.e., no flow). Such reference tables can be created for multiple different motor speeds. Blood flow Q pump By using such a reference table to determine (t), blood flow Q in particular can be determined. pump Compared to methods for measuring or calculating (t), blood flow Q during blood pump operation pump A more advantageous method for determining (t) can be realized. By using a reference table, blood flow Q can be determined based only on readily available operating parameters of the blood pump. pump (t) is determined. Therefore, sensors to detect patient parameters, such as pressure sensors or flow sensors to detect pressure differences inside the patient's blood vessels, are not required. Furthermore, blood flow Q can be found in the reference table. pump Reading the value for (t) does not require intensive computer calculations.

[0042] However, monitoring one or more appropriate characteristic cardiac parameters by applying a zero-flow control mode for only one heartbeat may not adequately adapt the heart to insufficient assistance from the blood pump. Therefore, the monitored characteristic cardiac parameters may still not adequately represent the true state of cardiac recovery, for example, they may not adequately represent the heart's actual pumping capacity. Thus, it is possible to repeat a single-heartbeat zero-flow control mode across multiple consecutive heartbeat cycles.

[0043] Therefore, a predetermined zero-flow time can be set to last for at least one complete cardiac cycle or for a predetermined number of complete, consecutive cardiac cycles. For example, a predetermined zero-flow time can be set to be part of a single cardiac cycle for up to several hours. In this way, the heart can be fully adapted to a state without assistance from the blood pump, and as a result, the actual state of cardiac recovery can be better observed.

[0044] It is also possible to combine zero flow for a single heartbeat with zero flow over an entire heartbeat cycle. For example, the zero flow control mode may initially be applied for a relatively short period of time, such as over a portion of a single heartbeat cycle, or over 1 to 300 consecutive heartbeat cycles. After innate cardiac function and sufficient recovery are recognized, the zero flow control mode may be applied for a longer period of time, such as over multiple complete heartbeat cycles lasting several minutes, several hours, or even several days.

[0045] A second embodiment provides a system comprising an intravascular blood pump for assisting the heart and a control device according to the first embodiment.

[0046] Preferably, the blood pump is catheter-based, that is, the blood pump preferably comprises a catheter and a pump unit, preferably with the pump unit located at the distal end of the catheter.

[0047] Preferably, the blood pump can be implemented as a rotary blood pump, that is, as a blood pump driven by a rotary motor.

[0048] The blood pump may be catheter-based so as to be directly implanted or placed percutaneously into the heart through the corresponding blood vessel. For example, the blood pump may be one such blood pump, as disclosed in, for example, U.S. Patent No. 5,911,685, which is configured in particular to be temporarily placed or implanted in the patient's left or right heart. As mentioned above, the present invention is particularly useful for intravascular blood pumps and is less relevant to larger VADs that are placed outside the patient's heart, such as being implanted in the pleural cavity, rather than being placed inside a blood vessel or inside the heart.

[0049] Preferably, the blood pump is a low-inertia device. (a) The blood pump is a low-inertia device by having one or more of the following characteristics: (b) The moving parts of the blood pump, specifically rotating parts such as the rotor or impeller, have low mass by being made of a lightweight material such as plastic; (c) The drive unit, such as an electric motor, is positioned near, preferably very close to, and most preferably adjacent to, the moving parts of the pump unit driven by the drive unit, such as the rotor or impeller; (d) If the blood pump is catheter-based, there is no rotary drive cable or rotary drive wire; (e) The coupling or connection part of the drive unit, such as the shaft, to the rotating parts of the pump unit driven by the drive unit is short; and (f) All the moving parts of the blood pump, specifically rotating parts, have a small diameter.

[0050] Low-inertia devices, particularly intravascular blood pumps designed for percutaneous insertion into a patient's blood vessels, have a smaller diameter, especially compared to VADs, which are relatively bulky. All moving parts of an intravascular blood pump are lightweight and located close to the axis of rotation. This allows for very precise control of the pump speed because the rotation of the impeller is only slightly affected by the impeller's inertia. This means there is only a slight delay between the command signal and the actual response of the blood pump. In contrast, VADs designed as centrifugal blood pumps, for example, can be bulky, have a large diameter, and therefore have a large rotor with greater mass, and may not be considered "low-inertia devices."

[0051] One characteristic of low-inertia devices is that reducing the pump speed of a low-inertia device, and specifically rapidly reducing the pump speed, does not require a negative velocity signal (which is usually necessary for large VADs) or other braking commands, but rather reduces the pump speed directly by reducing the motor current, and therefore the blood pump can be put into zero-flow control mode simply by reducing the motor current. This is particularly relevant to control within a single heartbeat, because the cardiac cycle is very short, and the cardiac cycle requires a short reaction time for the moving parts of the blood pump. The reverse is also true; to exit zero-flow control mode, it is equally desirable to rapidly accelerate the moving parts, i.e., to rapidly increase the pump speed.

[0052] For example, when using a low-inertia device in the sense of the present invention, it is possible to significantly increase or decrease the pump speed in a very short time, such as from about 50 ms to about 100 ms, and preferably from 60 ms to 80 ms. In other words, the pump speed can change rapidly or in a "stepwise" manner.

[0053] For example, within the time range described above, the pump speed may be reduced from approximately 35,000 rpm to approximately 10,000 rpm, or in another blood pump, from approximately 51,000 rpm to approximately 25,000 rpm, or vice versa, and the pump speed may be increased accordingly. However, the duration of the pump speed change is also determined by other factors such as blood flow, pressure difference, the intended change in pump speed (i.e., the difference between the pump speed before and after the intended speed change), or timing in the cardiac cycle (due to the acceleration of blood flow during systole and the deceleration of blood flow during diastole).

[0054] The third aspect is the blood flow Q of the intravascular blood pump considered in the first aspect. pump The present invention provides a method for controlling (t). That is, a blood pump comprises a pump unit with a drive unit and is configured to transport blood from a blood inlet to a blood outlet. The method provides: (i) a set blood flow value Q to obtain a control error e(t) in the first closed-loop cycle. pump set (t) Blood flow value Q pump (ii) the set speed value n for the drive means from the control error e(t) pump set The steps are to determine (t), and in the second closed-loop cycle, set the rate value n pump set (t) drive speed n pump By comparing with (t), the drive speed n of the drive unit pump The step of controlling (t) includes the following:

[0055] Preferably, this method controls a set blood flow value Q over a predetermined zero flow control time. pump set The further step includes providing a zero flow mode in which (t) is zero, and preferably further includes setting a predetermined zero flow control time to last for a portion of one cardiac cycle of the assisted heart, or for a portion of at least one full cardiac cycle or a predetermined number of consecutive cardiac cycles and / or full cardiac cycles.

[0056] As explained in more detail above in relation to the control device, this method uses an appropriate reference table to control blood flow Q pump This may include a step to determine or estimate (t).

[0057] Preferably, the first closed-loop cycle is the outer control loop of the cascade control, and the second closed-loop cycle is the inner control loop. Cascade control systems having an outer control loop and an inner control loop are described in more detail above in relation to control devices and are also effective in this method.

[0058] Preferably, this method further includes synchronizing the zero-flow control time with at least one specific characteristic cardiac cycle event.

[0059] Preferably, the start and / or end of the zero-flow control time are synchronized with the occurrence of at least one characteristic cardiac cycle event.

[0060] Preferably, this method further includes monitoring one or more values ​​of characteristic cardiac parameters.

[0061] Preferably, this method further includes identifying trends in one or more monitored values ​​of characteristic cardiac parameters.

[0062] A fourth aspect provides a control device according to the first aspect, configured to perform the method according to the third aspect.

[0063] The functions or capabilities considered on this control device and the corresponding functions and capabilities of this control method may be implemented by corresponding computing units in the hardware and / or software of the control device, or any combination thereof. These computing units may consist of corresponding computer programs having software code to cause the computing unit to perform each required control step. These programmable computing units are generally well known in the art and to those skilled in the art; therefore, there is no need to describe them in detail here. Furthermore, these computing units may include specific dedicated hardware useful for specific functions, such as one or more signal processors for processing and / or analyzing the measured signals considered. In addition, each unit for controlling the speed of the blood pump drive unit may similarly be implemented by its respective software module.

[0064] The corresponding computer program may be stored on a data medium containing the computer program. Alternatively, the computer program may be transmitted in the form of a data stream containing the computer program, for example, over the internet, without requiring a data medium. [Brief explanation of the drawing]

[0065] The present invention will be described below in this specification with reference to the accompanying drawings. [Figure 1] This is a feedback control cylinder. [Figure 2] This figure shows an exemplary blood pump positioned to pass through the aorta, extending through the aortic valve into the left ventricle, along with a block diagram of the control device for the pumping speed of the blood pump. [Figure 3] Figure 1 is a detailed diagram showing an example blood pump. [Figure 4]This is an illustrative graph showing a set of characteristic curves that represent the relationship between the actual pressure difference between the inlet and outlet of a blood pump, the actual pumping speed of the blood pump, and the blood flow produced through the blood pump. [Modes for carrying out the invention]

[0066] Figure 1 is a block diagram of an embodiment of a feedback control loop for blood flow control, implemented as a cascade control system. The control loop comprises an external control device 401 and an internal control device 402. The external control device 401 is embedded in the external control loop and receives the blood flow command signal Q pump set (t) generates blood flow Q pump (t) is used to compare with the setpoint of the internal control loop, i.e., the speed command signal n of the blood pump 50. pump set By setting (t), for example, the blood flow Q generated by the blood pump 50 shown in Figure 3 pump (t) is managed. The internal control device 402 is part of the internal control loop and, accordingly, the motor current I pump By adjusting (t), the speed of the blood pump 50 n pump Control (t).

[0067] In the feedback loop shown in Figure 1, the blood flow Q that is generated is pump (t) is current I pump (t) and velocity n pump (t) and the resulting blood flow Q pump (t) is calculated as an example using a reference table that shows the relationship, for example. Alternatively, or in addition, another reference table may be used to show the pressure difference between the blood pump outlet 56 and the blood pump inlet 54 (see Figure 3) and the velocity n pump (t) and blood flow Q pump It can be used to express the relationship with (t). The resulting blood flow Q pump As another alternative or additional option for acquiring data for (t), a flow sensor may be used.

[0068] This flow control may be a constant value (also called a set value) or a blood flow command signal Q that changes over time. pump set (t) Blood flow Q through blood pump 50 according to (t) pump (t) is managed. A constant blood flow setting value Q pump set (t) may be in the range of [-5...10] L / min, preferably in the range of [0...5] L / min, most preferably 0 L / min, or may be a very small blood flow as zero flow rate.

[0069] One of the aims of the flow control disclosed herein is to monitor the values ​​of characteristic cardiac parameters when using the implanted pump 50, with the aim of determining the state of cardiac recovery while reducing the pump's effect on cardiac function. To this end, the flow control sets the blood flow Q to 0 L / min. pump set (t) or a very small blood flow as zero flow rate can be used.

[0070] It has been found that the inner control loop can have a certain shorter time compared to the outer control loop. In this way, the inner control loop can react more quickly than the outer control loop. In addition, the inner control loop can be achieved at a higher sampling rate than the outer control loop.

[0071] For example, the sampling rate fs of the data within the inner control loop IN However, the range may be [250...10kHz], preferably [1...3kHz], and most preferably 2.5kHz.

[0072] For example, the sampling rate fs of the data within the outer control loop OUT However, the range may be [25...1000] Hz, preferably [100...300] Hz, and most preferably 250 Hz.

[0073] Figures 2 and 3 show an embodiment of a blood pump. This blood pump is an intravascular blood pump configured to be inserted percutaneously into the heart. In the embodiments shown, the blood pump is a microaxial rotary blood pump, which is hereafter referred to as blood pump 50. Such blood pumps are known, for example, from U.S. Patent No. 5,911,685.

[0074] The blood pump 50 is based on a catheter 20, which allows the blood pump 50 to be temporarily introduced into the ventricle of the patient's heart via a blood vessel. In addition to the catheter 20, the blood pump 50 includes a rotary drive unit 51 fixed to the catheter 20. The rotary drive unit 51 is coupled to a pump unit 52 located at a certain axial distance from the rotary drive unit 51.

[0075] A flow cannula 53 is connected to a pump unit 52 at one end and extends from the pump unit 52, having a blood inlet 54 located at its other end. The blood inlet 54 has a soft, flexible tip 55 that is attached to the blood inlet 54.

[0076] The pump unit 52 includes a pump housing with a blood flow outlet 56. Furthermore, the pump unit 52 includes a drive shaft 57 that protrudes from the drive unit 51 into the pump housing of the pump unit 52. The drive shaft 57 drives an impeller 58 as a propulsion element. During the operation of the blood pump 50, blood is drawn in through the blood flow inlet 54, transported through the cannula 53, and discharged through the blood flow outlet 56. The blood flow is created by the rotating impeller 58 driven by the drive unit 51.

[0077] In the embodiment shown, three wires pass through the catheter 20: two signal wires 28A and 28B, and a power supply wire 29 for supplying power to the drive unit 51 of the blood pump 50. The signal wires 28A and 28B and the power supply wire 29 are attached to the control device 100 (Figure 2) at their proximal ends. The signal wires 28A and 28B are associated with their respective blood pressure sensors, each of which comprises its respective corresponding sensor head 30 and 60. The power supply wire 29 provides power to the drive unit 51.

[0078] The drive unit 51 may be a synchronous motor. In the exemplary configuration, the electric motor may comprise multiple motor winding units for driving an impeller 58 coupled to the drive shaft 57. The rotor of the synchronous motor may comprise at least one field winding, or, in the case of a synchronous motor excited by permanent magnets, it may comprise permanent magnets.

[0079] In a preferred embodiment, the blood pump 50 is a catheter-based microaxial rotary blood pump for percutaneous insertion into the patient's heart through the patient's blood vessels. Here, “micro” indicates that it is small enough to allow percutaneous insertion into the heart, for example, into one of the ventricles of the heart, through blood vessels leading to the heart. This further defines the blood pump 50 as an “intravascular” blood pump for percutaneous insertion. Here, “axial” indicates that the pump unit 52 and the drive unit 51 that drives the pump unit 52 are arranged in an axial configuration. Here, “rotary” means that the functionality of the pump is based on the rotational motion of a propulsion element, i.e., an impeller 58, driven by a rotary electric motor of the drive unit 51.

[0080] As discussed above, the blood pump 50 is based on the catheter 20, and the catheter 20 allows for the insertion of the blood pump 50 through a blood vessel. Furthermore, the power supply wire 29 may pass through the catheter 20 to supply power to the drive unit 51 and to supply control signals from, for example, the drive unit 51 and the sensor heads 30 and 60.

[0081] As mentioned above, the present invention is particularly configured for intravascular blood pumps such as the blood pump 50 shown in Figure 3, and is less configured, or even unsuitable, for VADs implanted outside the patient's heart, such as centrifugal blood pumps that are connected to the patient's heart, placed in the thoracic cavity, and operate over a wide range of pump speeds. This is particularly due to inertial effects that significantly affect the function of large VADs, as described herein, although these inertial effects can be avoided in low-inertia devices such as intravascular blood pumps.

[0082] As shown in Figure 2, each signal wire 28A, 28B is connected to a single blood pressure sensor, each equipped with a corresponding sensor head 30 and 60, with each corresponding sensor head 30 and 60 located externally within the housing of the pump unit 52. The sensor head 60 of the first pressure sensor is connected to signal wire 28B and is intended to measure blood pressure at the blood flow outlet 56. The sensor head 30 of the second blood pressure sensor is connected to signal wire 28A and is intended to measure blood pressure at the blood flow inlet 54. Essentially, signals, which may have any appropriate physical origin, such as optical, hydraulic, or electrical origins, and signals captured by the pressure sensors to convey respective information about the pressure at the sensor's location, are transmitted via the respective signal wires 28A, 28B to the corresponding input devices of the data processing unit 110 of the control device 100. In the embodiment shown in Figure 2, the blood pump 50 is positioned in the aorta and further into the left ventricle of the heart via the aortic valve, and as a result, the pressure sensors are positioned so that the aortic pressure AoP(t) is measured by the sensor head 60 and the left ventricular pressure LVP(t) is measured by the sensor head 30.

[0083] The data processing unit 110 is configured to acquire external and internal signals for signal processing, and for signal processing, for example, the generated blood flow Q pump This involves calculating the difference between pressure signals as a basis for estimating (t). External and internal signals can function as control signals for this flow control technique, for signal analysis aimed at detecting the occurrence of characteristic events during the cardiac cycle based on acquired and calculated signals, and for generating a trigger signal σ(t) aimed at starting the velocity command signal generator 120, to name a few.

[0084] As a given embodiment of the flow control method, the speed command signal generator 120 represents the external control device 401 in Figure 1.

[0085] In the illustrated embodiment, the data processing unit 110 is connected via corresponding signal lines to additional measuring devices, which are collectively depicted as 300. In this embodiment, such additional measuring devices are a patient monitoring unit 310 and an electrocardiograph (ECG) 320, but it is clear that these two devices 310 and 320 are merely two examples and not exhaustive, meaning that other measuring devices may be used to provide similarly useful signals. The depicted ECG 320 provides the data processing unit 110 with an ECG signal ECG(t).

[0086] The control device 100 further includes a user interface 200. The user interface 200 is for interacting with the user of the device. The user interface 200 includes a display 210 as an output means and a communication interface 220 as an input means. The display 210 shows the values ​​of setting parameters, the values ​​of monitored parameters such as the measured pressure value, and other information. Furthermore, the communication interface 220 allows the user of the control device 100 to control the control device 100 by changing the setup and settings of the entire system, which consists of the blood pump and the control device 100, for example.

[0087] For the example of the flow control method given here, the setting is the desired pump flow Q in Figure 1. pump set The choice is (t).

[0088] The data processing unit 110 is particularly configured to derive or predict the timing of the occurrence of one or more predetermined characteristic events during the cardiac cycle of the assisted heart. For example, the data processing unit 110 is configured to detect predetermined characteristic cardiac cycle events during the cardiac cycle by real-time analysis of the monitored signal. Alternatively or in addition, predetermined characteristic cardiac cycle events, such as R waves, may be identified by the ECG signal from the ECG 320.

[0089] The occurrence of one or more determined predetermined characteristic events is used to generate one specific trigger signal σ(t) or a series of trigger signals σ(t). The resulting trigger signal σ(t) (or series of trigger signals) is transferred to the speed command signal generator 120, which in turn initiates a modification of the speed command signal provided to the speed control unit 130.

[0090] In the context of the present invention, the speed command signal generator 120 is configured to operate the blood pump 50 in zero flow rate control mode.

[0091] The data processing unit 110 predicts the timing of at least one predetermined characteristic cardiac cycle event in the next cardiac cycle based on stored information regarding characteristic cardiac cycle events that occur during the most recent and / or previous cardiac cycle, and these rate command signals n pump set The previous values ​​of (t) are also configured to be analyzed in a similar manner.

[0092] For example, a characteristic cardiac cycle event may be the onset of cardiac contraction at the start of systole. The detected or predicted occurrence of such a characteristic cardiac cycle event can be used to synchronize a series of applications of specific control techniques for the blood pump 50 over a range of one or more cardiac cycles or over a range of specific time intervals of cardiac cycles.

[0093] In response, the speed command signal generator 120 can be set to, for example, 0 L / min, given a blood flow command signal Q pump set According to (t), the resulting blood flow Q pump (t) is intended to control the speed command signal n to the blood pump 50. pump set It is configured to adjust (t).

[0094] The resulting blood flow Q pumpTo control (t), a speed command signal generator 120 continuously controls the generated blood flow Q pump either in a form that does not interrupt the time for continuously controlling the generated blood flow Q(t) (as a first setup) or in a form of control that performs switching based on an event (as a second setup), and provides an appropriate speed command signal n pump set (t) to a speed control unit 130, and is configured as an outer control device within a cascade control system.

[0095] In the first setup, the command signal generator 120, as part of a cascade blood flow control system that receives external and internal signals from a data processing unit 10, continuously provides a speed command signal n pump set (t) to the speed control unit 130.

[0096] In the second setup, the speed command signal generator 120 operates in the same manner as in the first setup, and here an additional structure is used to switch continuous blood flow control on and off.

[0097] In the zero flow control mode, the speed command signal n pump set (t) is continuously adjusted by a flow control device within an outer control loop. The on / off switching is initiated by at least one trigger signal σ(t) provided by a data processing unit 110.

[0098] When zero flow control is applied only for short time intervals, the second setup is appropriate, and this time interval is specifically short when compared to the duration of one cardiac cycle. In other words, the generated blood flow is controlled using a blood flow command signal Q pump set (t) of 0 L / min only for short time intervals within this cardiac cycle (blood flow control per heartbeat).

[0099] The speed control unit 130 is the speed command signal n pumpset According to (t), a current I is supplied to the drive unit 51 of the blood pump 50 via the power supply wire 29 pump (t) to control the speed n of the blood pump 50 pump (t).

[0100] The latest level of the supplied motor current I pump (t) corresponds, for example, to the current required at that time by the electric motor of the drive unit 51 to establish the target speed level defined by the speed command signal n pump set (t). Measurement signals such as the supplied motor current I pump (t) can be used as representative signals of the internal signals of the control device 100 and provided to the data processing unit 110 for further processing. The blood pump 50 can further communicate with the control unit 100 via the power supply wire 29.

[0101] Basically, in particular, the control device 100 is configured to operate the blood pump 50 in a selectable zero-flow control mode, in which the blood flow Q of the blood pump 50 pump (t) is controlled to attenuate the influence of the changing pressure difference between the blood outlet 56 and the blood inlet 54 due to the heartbeat that can be regarded as a disturbance. By adjusting the speed command signal n pump set (t), the blood flow Q pump (t) is controlled. As proposed in this specification, the control device 100 is configured to control the blood flow Q of the blood pump 50 pump (t), so that the blood pump 50 generates zero blood flow over a predetermined zero-flow control time.

[0102] In the first setup using continuous flow control, a predetermined zero-flow control time is set to last for at least one complete cardiac cycle or for a predetermined number of consecutive complete cardiac cycles. Furthermore, in the first setup, the control device 100 is configured to monitor the value of one or more characteristic cardiac parameters using the implanted blood pump 50. Again, the monitored value of one or more characteristic cardiac parameters can be used as an indicator of the state of cardiac recovery.

[0103] In a second setup using event-based zero-flow control, a predetermined zero-flow control time is set to be a portion of the duration of one cardiac cycle in the heart to which the blood pump 50 is implanted. In this setup, the control device 100 is configured to synchronize the start and end of the zero-flow control time with the occurrence of a specific characteristic cardiac cycle event.

[0104] In particular, the control device 100 controls the blood flow Q through the blood pump 50, either periodically or irregularly. pump (t) can be controlled.

[0105] In certain implementations, the characteristic cardiac cycle event is either the opening or closing of the aortic valve, the opening or closing of the mitral valve, or a specific pressure value as the end-diastolic left ventricular pressure.

[0106] Furthermore, in the second setup, similar to the first setup, the control device 100 is configured to monitor the values ​​of one or more characteristic cardiac parameters of the heart implanted with the blood pump 50 during the zero-flow control time. The monitored values ​​of one or more characteristic cardiac parameters can similarly be used as indicators of the state of cardiac recovery.

[0107] The control device 100 is further configured to identify trends in the values ​​of one or more monitored characteristic parameters. As mentioned above in this specification, these trends may also be interpreted as indicators of the state of cardiac recovery.

[0108] In either case, in order to implement the zero flow control mode, the control device 100 receives the speed command signal n from the blood pump 50. pump set By adjusting (t), blood flow Q pump It is configured to control (t), thereby controlling the drive speed n pump (t) is affected by the changing blood pressure difference between the blood outlet 56 and the blood inlet 54 of the blood pump 50 during the cardiac cycle.

[0109] In particular, the control device 100 controls, for example, the drive speed n pump (t), current I pump (t), and / or the blood flow Q of the blood pump 50 based on a predetermined signal such as the pressure difference between the blood outlet 56 and the blood inlet 54 of the blood pump 50. pump It is configured to determine (t).

[0110] Figure 4 shows the pressure difference ΔP between the blood outlet 56 and the blood inlet 54 of the blood pump 50. pump (t) and the drive speed n of the blood pump 50 pump (t) and the blood flow Q generated by the blood pump 50, for example, through the flow cannula 53 in Figure 3. pump This is an illustrative graph showing a set of characteristic curves that represent the relationship between (t) and (t).

[0111] To achieve zero flow control, the data processing unit 110 uses a known speed n pump (t) A known current I supplied to the pump unit 51 pump (t), and / or the monitored pressure difference ΔP between the blood outlet 56 and the blood inlet 54 of the blood pump 50. pump Based on (t), the blood flow Q generated by the blood pump 50 pump (t) is configured to be continuously determined. Set blood flow value Qpump set (t) may be zero, or at least a positive value close to zero.

[0112] For example, based on Figure 4, the monitored pressure difference ΔP is between the blood outlet 56 and the blood inlet 54 of the blood pump 50. pump In cases where (t) is 60 mmHg, the drive speed n pump (t) is a blood flow Q of approximately 0 L / min pump To generate (t), the speed needs to be approximately 20,000 1 / min (rpm).

[0113] It should be recognized that the values, relationships, and shapes of the curves shown in the characteristic graph of Figure 4 are merely illustrative and may vary depending on the blood pump used, the patient, or other factors. Specifically, every blood pump, or even blood pumps of similar types, may have its own individual characteristic graph; in other words, the reference table may be pump-specific. Furthermore, when implanted in a patient, this characteristic graph may need to be fitted with patient-specific correction factors, which may include a variety of factors such as blood viscosity and the location of the blood pump. By using correction factors, the accuracy of the flow estimation achieved by the reference table can be improved.

[0114] As discussed above, the latest pressure difference ΔP pump (t) can be determined by the pressure sensors of the blood pump 50 (for example, sensors 30 and 60 in Figure 3). Thus, the speed control unit 130 can be controlled, for example, in Figure 4 (where the values ​​discussed above, ΔP pump (t), Q pump (t), and n pump Values ​​can be continuously provided from a storage unit such as a reference table that stores the characteristic curve of (t) representing the relationship between (t). This storage unit may be the read-only memory of the data processing unit 110, or alternatively, a storage chip in the blood pump 50 or a storage chip in its control console 130.

[0115] At least one characteristic cardiac parameter value is at least one of the following: arterial blood pressure, measured each time a zero-flow operating mode is established.

[0116] Preferably, the blood pump 50 is a low-inertia device. This is achieved in particular by having low mass by making the moving parts of the blood pump 50, such as the rotor or impeller, and specifically the rotating parts, out of a lightweight material such as plastic. In addition, the drive unit, such as an electric motor, is positioned near, preferably very close to, and most preferably adjacent to, the components driven by the drive unit, such as the propulsion element, such as the rotor or impeller 58. In addition, even if the blood pump 50 is catheter-based, there is no rotary drive cable or rotary drive wire. In addition, the coupling or connection portion with the propulsion element, such as the rotor or impeller 58, driven by the drive unit 51, i.e., the coupling or connection portion of the drive unit 51, such as the shaft 57, is kept short. In addition, all moving parts of the blood pump 50, specifically the rotating parts, have a small diameter.

[0117] In summary, the zero flow control method proposed herein involves the control device 100 controlling the blood flow Q generated through the blood pump 50 within a cascade control consisting of an outer control loop and an inner control loop. pump (t) controls the blood flow Q generated through the pump unit 50. pump (t) is a speed command signal n to the drive unit 51 of the blood pump 50 located in the outer control loop. pump set (t) is controlled by adjusting the current I pump The drive speed n is achieved by adjusting (t). pump(t) means that it is controlled within the inner control loop. This zero-flow control technique is applied continuously or partially continuously, meaning that the zero-flow control time lasts for one or more complete cardiac cycles or for only a portion of a single cardiac cycle. In cases where a given zero-flow control time lasts for only a portion of the cardiac cycle duration, the zero-flow control time can be synchronized with a heartbeat caused by at least one characteristic event of the cardiac cycle.

Claims

1. Blood flow Q of an intravascular blood pump (50) that is inserted percutaneously into the patient's blood vessels ｐｕｍｐ A control device (100) for controlling (t), wherein the blood pump (50) comprises a pump unit (52) and a drive unit (51) for driving the pump unit, configured to transport blood from a blood inlet (54) toward a blood outlet (56), The control device (100) is configured to operate the blood pump (50) in a selectable zero flow rate control mode, and a blood flow command signal Q between 0 L / min and 1 L / min is received. ｐｕｍｐ ｓｅｔ (t) is selected, and the control device comprises a first control device (401) and a second control device (402), The first control device (401) adjusts the speed command signal n ｐｕｍｐ ｓｅｔ for the drive unit (51) to control the blood flow Q ｐｕｍｐ (t), and is further configured to determine the speed command signal based on the difference ΔQ between the blood flow command signal Q pump set (t) and the blood flow Q pump (t). The second control device (402) controls the drive speed n ｐｕｍｐ ｓｅｔ of the drive unit (51) according to (t) ｐｕｍｐ (t). The control device (100) controls the blood flow Q ｐｕｍｐ (t) is configured to control in the zero flow control mode for a predetermined zero flow control time, and the predetermined zero flow control time is set to last for one complete cardiac cycle of the assisted heart or a portion of such a cardiac cycle. The control device (100) is configured to synchronize the start and / or end of the predetermined zero flow control time with the occurrence of at least one characteristic cardiac cycle event.

2. A control device (100) according to claim 1, wherein the second control device (402) supplies a drive current I to the drive unit (51). ｐｕｍｐ By adjusting (t), the drive speed n ｐｕｍｐ A control device (100) characterized by being configured to control (t).

3. A control device (100) according to claim 1 or 2, characterized in that the first control device (401) and the second control device (402) are part of a cascade control system, the first control device (401) is an external control device, and the second control device (402) is an internal control device.

4. A control device (100) according to any one of claims 1 to 3, wherein the at least one characteristic cardiac cycle event is the opening of the aortic valve or the closing of the aortic valve.

5. A control device (100) according to any one of claims 1 to 4, wherein the control device (100) is configured to monitor the values ​​of one or more characteristic cardiac parameters.

6. A control device (100) according to any one of claims 1 to 5, wherein the control device (100) is configured to operate the blood pump (50) periodically or irregularly in the zero flow rate control mode.

7. A control device (100) according to claim 5, wherein the control device (100) is configured to identify trends in the values ​​of one or more characteristic cardiac parameters to be monitored.

8. A control device (100) according to claim 7, wherein one or more characteristic cardiac parameters are pulsatile AOP of arterial pressure | ｍａｘ - AOP | ｍｉｎ Mean arterial pressure, cardiac contractility dLVP(t) / dt| ｍａｘ Cardiac relaxation dLVP(t) / dt| ｍｉｎ A control device (100) characterized by being at least one of the following: heart rate (HR).

9. A control device (100) according to any one of claims 1 to 8, wherein the control device (100) controls the blood flow Q by means of a sensor. ｐｕｍｐ (t) to be measured, or the blood flow Q ｐｕｍｐ A control device (100) characterized by being configured to calculate or estimate (t).

10. A control device (100) according to any one of claims 1 to 9, wherein the control device (100) controls the blood flow Q ｐｕｍｐ (t) and the drive speed n ｐｕｍｐ (t) and the pressure difference ΔP between the blood outlet (56) and the blood inlet (54). ｐｕｍｐ (t) and the drive current I supplied to the drive unit (51) ｐｕｍｐ Using a reference table that shows the relationship between at least one of (t) and the blood flow Q ｐｕｍｐ A control device (100) characterized by being configured to determine (t).

11. A system comprising an intravascular blood pump (50) for percutaneous insertion into a patient's blood vessel and a control device (100) according to any one of claims 1 to 10.

12. A system according to claim 11, wherein the blood pump (50) has one or more of the following characteristics: the movable parts of the blood pump are made of plastic; the drive unit (51) is located near the movable parts driven by the drive unit (51); and it does not have a rotary drive cable or rotary drive wire.

13. Blood flow Q of an intravascular blood pump (50) that is inserted percutaneously into the patient's blood vessels ｐｕｍｐ A method for controlling (t), wherein the blood pump (50) comprises a pump unit (52) equipped with a drive unit (51) and is configured to transport blood from a blood inlet (54) toward a blood outlet (56), and the method is Set blood flow value Q over a predetermined zero flow control time. ｐｕｍｐ ｓｅｔ The control device (100) provides a zero flow rate control mode in which (t) is between 0 L / min and 1 L / min, In order to obtain the control error e(t) in the first closed-loop cycle, the control device (100) controls the set blood flow value Q ｐｕｍｐ ｓｅｔ (t) is the blood flow value Q ｐｕｍｐ The step of comparing with (t), The control device (100) determines the set speed value n for the driving means from the control error e(t). ｐｕｍｐ ｓｅｔ The step of determining (t), In the second closed-loop cycle, the set speed value n ｐｕｍｐ ｓｅｔ (t) is driven at speed n ｐｕｍｐ By comparing with (t), the control device (100) controls the drive speed n of the drive unit (51). ｐｕｍｐ (t) is controlled by the step, The steps include: the control device (100) setting the predetermined zero flow control time so that it continues for one complete cardiac cycle or a portion of such a cardiac cycle of the assisted heart; The control device (100) synchronizes the predetermined zero flow control time with at least one specific characteristic cardiac cycle event, A method characterized by including

14. A method according to claim 13, characterized in that the first closed-loop cycle is the outer control loop of a cascade control, and the second closed-loop cycle is the inner control loop.

15. The method according to claim 13 or 14, The control device (100) monitors one or more characteristic cardiac parameters. A method characterized by further comprising:

16. The method according to claim 15, The control device (100) identifies a trend in the values ​​of one or more of the characteristic cardiac parameters being monitored. A method characterized by further comprising:

17. A control device (100) according to any one of claims 1 to 10, or a system according to claim 11 or 12, configured to perform the method of any one of claims 13 to 16.

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