Ventricular assist device

Abstract

A control device (100), VAD (50) for controlling the rotational speed (nVAD (t)) of a non-pulsatile ventricular assist device, using an event-based Boron control strategy, wherein the control device is configured to change the rotational speed (nVAD (t)) of the VAD (50) within the cardiac cycle of the assisted heart and to synchronize the change of the rotational speed (nVAD (t)) with the heartbeat by means of at least one sequence of trigger signals ((t)) relating to at least one predetermined characteristic event in the cardiac cycle. Furthermore, a VAD (50) for heart assistance comprises a control device (100) for controlling the VAD, where the VAD is preferably a blood pump, for example based on non-pulsatile rotation of a catheter.

Description

[0001] Case Analysis This application is a divisional application of the patent application filed on August 18, 2017, with international application number PCT / EP2017 / 070953, Chinese national application number CN201780051986.7, and entitled "Ventricular Assist Device". Technical Field

[0002] This invention relates to the field of non-pulsating ventricular assist devices (VADs). In particular, this invention relates to a control device for within-a-beat control of a non-pulsating VAD, such as an intravascular rotary pump, and a VAD comprising a control device for controlling the VAD. Background Technology

[0003] If, despite optimal medical treatment, a patient's heart pumping function remains insufficient, a circulatory assist device (VAD) can be used. A VAD can assist or even replace the heart's inadequate ventricular pumping function by delivering blood in the same manner as the ventricles. To this end, a VAD is typically configured to draw blood from the inlet circulation and eject it back into the outlet circulation. In doing so, the VAD needs to overcome the pressure difference between the outlet and inlet, i.e., the pressure difference between the VAD after loading and before loading.

[0004] A specific example of a VAD is a catheter-based rotary blood pump, which is positioned directly in or implanted in the heart for hours or days to assist cardiac function until recovery. US 5,911,685 A discloses an exemplary intravascular rotary blood pump. However, other types of VADs exist.

[0005] Increased bleeding tendency has been observed in patients receiving cardiac assistance via non-pulsatile blood pumps. This increased bleeding tendency is associated with a deficiency of a specific glycoprotein known as von Willebrand factor (vWF), which is involved in hemostasis.

[0006] The term "cardiac cycle" as used in this article refers to the dynamic behavior of the heart during one heartbeat, including changes in blood pressure and ventricular volume over time, such as those observed in blood pressure and ventricular volume. A heartbeat is defined in this article as beginning with the arousal of atrial contraction and ending before the next atrial contraction, to distinguish between cardiac systole and diastole. The systolic phase of the heart (also known as the ejection phase) is the period between the closure of the mitral valve and the aortic valve. The diastolic phase of the heart (also known as the filling phase) is the period between the closure of the aortic valve and the closure of the mitral valve. The frequency at which the heart completes a cardiac cycle is called heart rate. Summary of the Invention

[0007] One object of the present invention is to provide improved assistance to the circulatory system of patients, by which the observed vWF deficiency can be avoided or at least reduced.

[0008] In particular, one object of the present invention is to provide a smart control device for a VAD, such as a rotary blood pump, which operates the VAD to avoid or at least reduce the side effect of vWF deficiency caused by the application of a non-pulsatile VAD.

[0009] In particular, another object of the present invention is to provide an intelligent control device for a VAD that operates the VAD such that, in addition to avoiding or at least reducing the side effects of using a non-pulsatile VAD, it provides the desired blood pressure, which is related to the patient’s current perfusion needs.

[0010] The inventors have discovered that the aforementioned increased bleeding tendency is reduced when minimal residual pulsation of blood pressure is restored and / or maintained in the circulatory system. Furthermore, sufficient pressure pulsation also appears to support adequate perfusion of the circulatory system's microvascular system.

[0011] Therefore, the main idea of ​​this invention is an event-based Bonne control strategy that extends the control loop for the rotational speed of the VAD by a speed command signal generator for generating a speed command signal to change the rotational speed of the VAD, such that a predetermined minimum pulsation can be achieved in a first setting via open-loop control or in a second setting via closed-loop pressure control in a feedback system, wherein in the first setting the speed command signal alternates between predetermined rotational speed levels, and in the second setting the speed command signal is automatically set for each heartbeat by forming an additional external pressure control loop of cascade control.

[0012] In one specific embodiment, the proposed event-based intrapulsation control strategy for blood pressure can influence the pulsation of a patient's blood pressure by altering blood flow through the VAD during the cardiac cycle. A particular application of this event-based intrapulsation control strategy for blood pressure may be to restore and / or maintain the desired minimum pulsation of arterial blood pressure, thereby avoiding the presumed side effect of VAD application on vWF release. This is supported by the fact that most continuous-flow VADs have been observed to reduce pulsatility and thus lead to a decrease in the vWF phenomenon.

[0013] Therefore, the event-based Bonne control strategy proposed here for the rotational speed of the VAD is particularly useful for avoiding the inherent side effects of non-pulsatile VADs in terms of vWF deficiency. In other words, the specific proposed speed variation for the desired minimum pulsation used to restore and / or maintain blood pressure is not considered a treatment, but rather a feature to eliminate the inherent side effects of non-pulsatile VADs.

[0014] In addition, compared with non-pulsatile cardiac assist, changes in pump rate during the cardiac cycle (hereinafter referred to as “heartbeat” or “pulsation”) produce further beneficial effects, such as improved perfusion of the microvascular system of the circulatory system.

[0015] In the context of the desired minimum pulsation for restoring and / or maintaining arterial blood pressure, the term "pulsation" as used herein is generally understood to refer to the maximum aortic pressure AoP during the h-th cardiac cycle. max (h) With minimum aortic pressure AoP| min (h) The difference between them: AoP (h) = AoP| max (h) – AoP| min (h) In the following text, for the sake of simplicity, all characteristic measurements and calculated values ​​will be referred to as specific first-order values. (j -1) st , j th , ( j +1) st Heartbeat, and so on, or more generally, the h-th heartbeat. This also means the dependence of these values ​​on continuous time t and the specific measurement point k. For example, AoP| max (j) = max k {AoP (t j,k )} for k = 0 … m j Where index j indicates the j-th heartbeat, and for the first measurement point starting from the j-th heartbeat k = 0, and in the next... (j+1) st Before the next heartbeat begins, at the last measurement point k = m j The end signal for all AoP k = 0…m j Calculate the maximum value of the signal AoP from the measured values ​​of the j-th heartbeat.

[0016] And so on. AoP| max (j+1) = max k {AoP (t j+1,k)} for k = 0…m j+1 The inventors hypothesize the need to restore and / or maintain minimal residual pulsation, particularly in the case of VAD-assisted circulatory systems. Therefore, the main idea of ​​this invention is to improve the control of a non-pulsatile VAD such that, during the cardiac cycle, i.e., within one heartbeat, the rotational speed n of the VAD can be changed. VAD (t) This results in the desired minimum pulsation. Its purpose is to restore and / or maintain minimal residual pulsation in the interest artery, i.e., in the aorta with left-sided cardiac assistance. The different types of pulsations are defined below (see also...). Figure 3 a): Physiological (unassisted) pulsation: The desired (auxiliary) minimum pulsation: Pulsation difference: Therefore, the desired minimum pulsation It depends on the maximum and minimum expected aortic pressure during the h-th cardiac cycle, respectively. and Pulsation difference Limited to current physiological (non-auxiliary) pulsations AoP (h) With the expected (auxiliary) minimum pulsation The difference between them.

[0017] In this regard, the inventors further discovered that the predetermined value of the desired minimum pulsation is within The range is [15…30] mmHg, but the desired minimum pulsation can also be higher.

[0018] A further problem discovered by the inventors is that a physical prerequisite that the VAD used in the application disclosed herein must preferably satisfy is the absence of associated inertia. That is, the VAD is preferably a low-inertia device. To date, rotary blood pumps, such as the catheter-based pumps described above with negligible mass moment of inertia, are well-suited for speed control schemes with intramolecular velocity variations while maintaining high energy efficiency (e.g., avoiding heat loss). To achieve specific characteristics of a VAD with a small mass moment of inertia, among other features, namely not only: the movable, especially rotatable, components of the VAD include low-mass rotors or impellers, for example, rotors or impellers made of low-weight materials such as plastics or synthetic materials; a drive unit, such as an electric motor, arranged near the rotor or impeller, preferably very close to it, and most preferably adjacent to it, thereby making the shaft connecting the motor and the rotor or impeller short, thus maintaining its low rotational mass (for example, it is known that having a device with a rotating drive cable or wire for connecting the rotor to the motor is undesirable because the mass of the cable or wire increases the mass to be accelerated or decelerated); all movable, especially rotatable, components have small diameters, so that the resulting component mass moment of inertia remains very small.

[0019] A first aspect of the invention provides a control device that alters the rotational speed (hereinafter simply "speed") of a non-pulsatile VAD during a cardiac cycle relative to event-based physiological conditions. VAD (t) .

[0020] Therefore, the control device can be configured to change the velocity of the VAD during the cardiac cycle of the assisted heart, and in combination with a trigger signal generator, cause the velocity command signal n to be triggered by at least one event sequence related to at least one predetermined characteristic recurring event in the cardiac cycle. VAD (t) The changes are synchronized with the heartbeat. Therefore, the natural cardiac output of the assisted heart can be affected by the VAD-induced blood flow Q. VAD The effect of (t).

[0021] In a particular embodiment, the control device may be configured to adjust the speed command signal n VAD set (t) Continuous predetermined pulse duration pulse (h) Or with the basic speed level n VAD set,basic (t) Compared to heart rate-dependent pulse duration assist (h)To generate the desired minimum pulsation in the benefit artery through the blood flow generated by the VAD during the h-th cardiac cycle. .

[0022] If the VAD is configured for left-sided cardiac assist, the benefiting artery can be at least the aorta. Alternatively, if the VAD is configured for right-sided cardiac assist, the benefiting artery can be at least the pulmonary artery.

[0023] Therefore, the control device can be configured to adjust the speed command signal n of the VAD. VAD set (t) And control the speed of VAD n VAD (t) The minimum pulsation is satisfied as desired by the first or second setting.

[0024] In the first configuration, the control device can be configured in an open-loop manner, for example, by adjusting the speed command signal n via a command signal generator. VAD set (t). In the first setting, the speed command signal n of the VAD is alternated between predetermined speed levels using an event-based command signal generator. VAD set (t) This allows us to obtain the desired minimum pulsation. .

[0025] In the second configuration, the control device can be configured to adjust the speed command signal n using a closed-loop feedback method. VAD set (t), for example, by extending the speed n for VAD with an additional pressure control loop that generates a cascade control strategy. VAD (t) The speed control loop. In the second setting, the speed command signal n VAD set (t) It can be automatically configured in the velocity command signal generator, for example, through an outer loop with a feedback pressure control strategy, so that the desired minimum pulsation of the h-th heartbeat can be achieved while taking into account the boundary conditions of physiological induction. The first setting can also consider the boundary conditions for physiological induction.

[0026] Such boundary conditions could be, for example, limited available blood volume and / or mean arterial blood pressure. Maximum and / or minimum levels. In order for the control device to operate within physiological constraints, it may be necessary to monitor ventricular filling pressure (e.g., using a pressure sensor in the ventricle) or any aspiration events that may occur due to insufficient blood volume (e.g., using a pressure sensor located within or at the VAD inlet to monitor negative inflow pressure associated with aspiration).

[0027] Used to generate speed command signal n VAD set (t) Both the open-loop setting (first setting) and the closed-loop setting (second setting) can be constructed to operate in an event-based manner, and both can be designed to adjust the speed command signal n of the VAD. VAD set (t) Continuous predetermined pulse duration pulse (h) The desired minimum pulsation is generated during the h-th heartbeat. .

[0028] The control device may include a speed n for controlling the VAD. VAD The internal and external control loops of (t) are defined by the structure of the control device, depending on the first or second setting specified above. For the internal (speed) control loop, common high-speed feedback closed-loop control can be used. The focus below will be on the speed command signal n of the VAD used for the internal control loop. VAD set (t) The generation of.

[0029] Preferably, the control device is configured to use at least one sequence of trigger signals associated with at least one predetermined characteristic event in the cardiac cycle. σ(t) Make the speed command signal n VAD set (t) Adjustments, such as the start and / or end of command signal pulses, are synchronized with the heartbeat.

[0030] For example, the control device can be configured to adjust the speed command signal n VAD set (t) This causes the blood pressure in the arterial cavity, which is benefited by the VAD, to increase within a predetermined time interval of the cardiac cycle. Typically, the control device can be configured to set a speed command signal n. VAD set (t) It is used to adjust the VAD rate to a high level during cardiac systole and / or to a low level during cardiac diastole.

[0031] For example, the desired minimal pulsation can be generated simply by changing the velocity during the contraction of the assisted heart. That is, the basic velocity level n can be adjusted before, at, or shortly after the onset of the contraction of the assisted heart. VAD set (t) = n VAD set,basic (h) Increase to target speed level n VAD set (t) = n VAD set,basic (h) + n VAD set (h) To adjust the speed command signal n that limits the target speed level VAD set (t) And it can be reduced back to the basic rate level before, during, or shortly after the end of the heart contraction. VAD set,basic (h) In this way, by increasing the speed difference n VAD set (h) Basic speed level n VAD set,basic (h) The increase in [something] generates a positive velocity pulse during cardiac contraction in the assisted heart.

[0032] Accordingly, the desired minimal pulsation can be generated simply by changing the velocity during diastole of the assisted heart. That is, this can be achieved by adjusting the velocity level from the baseline velocity level n before, at, or shortly after the onset of diastole in the assisted heart. VAD set,basic (h) Reduce to the target speed level n VAD set (t) = n VAD set,basic (h) - n VAD set (h) To adjust the speed command signal n VAD set (t) And the velocity level can be increased back to the baseline velocity level n before or shortly before the end of diastole. VAD set,basic (h)In this way, by reducing the speed difference n VAD set (h) Basic speed level n VAD set,basic (h) The decrease in velocity produces a negative velocity pulse during diastole of the assisted heart.

[0033] However, changes in the velocity command signal during systole or diastole are a common example of velocity variation synchronized with the heartbeat. It should be understood that the desired minimum pulsation... It can be generated by combining positive velocity pulses during cardiac contraction and negative velocity pulses during cardiac diastole.

[0034] Note that the reason for synchronizing the velocity command signal change with the cardiac cycle is to enhance the residual pulsation of a weakened heart, which is due to the primary cardiac contraction during systole. Preferably, the velocity command signal change causes the systolic flow to contribute only to the heart's natural ejection; that is, it is desirable for the heart and VAD to eject blood together.

[0035] Therefore, in the first embodiment, the control device is configured to change the speed command signal n. VAD set (t) To adjust the rate of VAD so that VAD-induced blood flow Q VAD (t) A significant reduction in the diastolic velocity of the VAD and / or a significant increase in the systolic velocity of the heart during the cardiac cycle can achieve the desired restoration and / or maintenance of minimal pulsation. Therefore, the desired minimal pulsation of arterial blood pressure can be restored and maintained. A decrease in the diastolic velocity of the VAD allows for adequate ventricular filling, thus enabling combined systolic ejection from the VAD and the native heart.

[0036] The inventors have discovered that, as the target of the velocity command signal alteration, both the native heart and the VAD preferably provide sufficient peak systolic flow rate so that the total peak flow rate per heartbeat is [missing information]. Q total|max (h) = Q heart|max (h) + Q VAD|max (h) And the total ejection volume per heartbeat (EV). EV (h) = EV heart (h) + EV VAD (h) This results in a sufficient increase in systemic blood pressure during systole. The ability of the native heart to co-eject may depend on ventricular preload, ventricular filling level, cardiac contractility level, and achievable peak VAD flow. The ability of the native heart to co-eject may also depend on the patient's body mass index, or body surface, or vascular compliance and peripheral resistance.

[0037] For example, the average blood flow of a typical patient who is 1.75 meters tall and weighs 75 kilograms is approximately 5 liters per minute. This requirement can be estimated based on a person's body surface area (BSA). A typical patient has a body surface area of ​​approximately 1.9 square meters (based on R.D. Steller's formula, "Simplified calculation of body-surface area," N. Engl. J. Med. 317, No. 17, October 1987, p. 1098). Normal blood flow, standardized to BSA, is approximately 2.6 L / m². 2 At rest, the average blood flow in healthy patients is 5 L / min, resulting in blood pressure ranging from approximately 120 mmHg to 80 mmHg.

[0038] During cardiac systole, the total peak flow rate Q is approximately 8 L / min. total|max (h) is considered sufficient for a person of normal size (BSA 1.9 m). 2 The desired minimum pulsation of approximately 15 mmHg is generated in the process. Therefore, more generally, the total peak flow rate of 8 L / min divided by 1.9 m³ 2 Multiplying this by the patient's actual BSA yields a more suitable peak flow value for the patient. As another example, BSA = 1.6 m 2 Patients can have the same desired minimum pulsation. Among them, only Q is present during cardiac systole. total|max (h) = 6.7 L / min total peak flow rate. More generally, taking into account all the variability in compliance and peripheral resistance, for the vast majority of patients treated with assistive devices, a total peak flow rate between 6 L / min and 10 L / min should be sufficient to achieve at least The target of 15 mmHg is the minimum expected pulsation. Therefore, the peak flow velocity during contraction leads to the total peak flow rate. Q toal|max (h) = Q heart|max (h) + Q VAD|max (h) > 6 L / min…10 L / min, This results in the expected total ejection volume EV(h) = EV heart (h) + EV VAD (h) = 40 ml…70 ml, This allows the desired minimum pulsation to be achieved. > [15…30] mmHg.

[0039] Minimum expected fluctuation It is not a fixed value, but can vary based on the recruitment of vWF. The simulation results highlight the fact that the command signal generator or external pressure control loop can focus on increasing pulsations while accepting decreasing mean aortic pressure, or focus on increasing mean aortic pressure while accepting decreasing pulsations.

[0040] At a normal human heart rate HR≈70 bpm (heart beats per minute), the duration of a cardiac contraction is typically approximately... Systole (h) = 300 ms and varies only slightly with heart rate. Patients in shock are typically characterized, especially by heart rates up to HR ≤ 120 bpm. Therefore, the minimum duration of the cardiac cycle is assumed to be... (h) = 500 ms. Furthermore, in patients with higher heart rates (HR ≥ 120 bpm), the shortened duration of cardiac contraction is assumed to be approximately... Systole (h) = 250 ms.

[0041] Therefore, the predetermined pulse duration of the velocity pulse pulse (h) It is possible pulse (h) = Preferably, within the range of [200… 300] ms pulse (h) = [225…275] ms, optimal choice pulse (h) = 250 ms.

[0042] Alternatively, the predetermined pulse duration of the velocity pulse. pulse (h) The duration of cardiac systole in the assisted heart Systole (h) Within the range of + / - 50% or + / - 100ms.

[0043] Depending on the residual pulsation in the benefit artery, the pulse duration of the velocity pulse can also be adapted to the heart rate, producing a time interval. assist (h) It preferably depends on observations of, for example, the previous heart rate and the duration of the previous systolic phase.

[0044] Additional or alternative speed command signal n VAD set (t) The adjustment can be synchronized with the appearance of the R wave in the patient's electrocardiogram (ECG) signal and / or set to a constant repetition rate, for example, in the case of cardiac arrest.

[0045] In a possible practical implementation, the VAD, for example in the form of a rotary blood pump, may include an actuator for driving the blood pump, such as a rotary electric motor, which generates a VAD-induced blood flow Q. VAD (t) Then, the control device can transmit the speed command signal n VAD set (t) Adjust the speed of the VAD to the target speed level of the rotary motor and control the speed n through feedback closed-loop control. VAD (t) To change the speed of VAD n VAD (t) Therefore, changes in the pulse, i.e., the pulse difference... AoP pulse (h) It can be used with the speed command signal n VAD set (t) The corresponding adjustments are related, for example, through speed difference. n VAD set (h) That is, the speed command signal n of the rotating electric motor VAD set (t) From the basic speed level n VAD set,basic (h) Increase speed difference n VAD set (h) It is used to generate the desired minimum pulsation set by the control device. Therefore, the control device can be configured to change the corresponding higher command speed signal n. VAD set (t) = n VAD set,basic (h) + n VAD set (h) To achieve the desired minimum pulsation .

[0046] Typically, speed difference n VAD set (h) It can also be negative, for example, generating a negative velocity pulse.

[0047] It is worth noting that the obtained pulsation difference can be used as a basis for... AoP pulse (h) Determine the desired speed difference n VAD set (h) It largely depends on the amount of blood delivered to the arterial system within a given unit of time. It is important to understand that any buildup of arterial blood pressure is the end result of blood being ejected into the arterial system within a unit of time, with its inherent compliance and peripheral resistance.

[0048] Preferably, the control device is also configured to adjust the speed command signal n outside the speed change interval. VAD set (t) For example, adjusting the basic speed level n VAD set,basic (h) In order to achieve a predetermined mean arterial blood pressure via VAD Or to prevent any backflow from entering the ventricle through the pump, this is called regurgitant pump flow.

[0049] In further improvements, the control device, particularly in the second closed-loop configuration, can be configured to adjust the speed command signal n both within and outside the speed variation interval. VAD set (t) To achieve the desired minimum pulsation. .

[0050] In a further improvement, the control device can be additionally configured to take into account the average arterial blood pressure per heartbeat. The speed command signal n is adjusted simultaneously as a control constraint. VAD set (t) .

[0051] For example, the control device can be configured to adjust the speed command signal n VAD set (t)To avoid mean arterial blood pressure Drop to the predetermined threshold the following.

[0052] Additionally, the control device can be configured to adjust the speed command signal n. VAD set (t) This allows for a predetermined time interval before the occurrence of a predetermined characteristic event. incr (h) The start of the velocity change interval (or velocity pulse). This means that the velocity change can occur at a time interval prior to the expected or predicted start of, for example, ventricular contraction of an assisted heart. incr (h) This can be triggered by corresponding characteristic events in the cardiac cycle. This can be particularly important because a particular VAD, for example, the dynamic response of a particular pump, may be delayed before providing the desired effect due to pump-specific mechanical and / or hydraulic inertia that requires a waiting time.

[0053] For example, the onset of cardiac contraction, defined, for instance, at the closure of the mitral valve, can be detected based on a corresponding blood pressure signal. For example, if the VAD is configured for left ventricular assist, the corresponding blood pressure signal could be left ventricular pressure.

[0054] For example, atrial contractions preceding ventricular contractions can be detected. Therefore, the event occurs before the systolic contraction event, allowing the pump to accelerate when the start of atrial contraction is used as the event.

[0055] Optionally or additionally, the predetermined event may be the appearance of an R wave in the ECG signal of the assisted heart.

[0056] Considering the fact that the increase in VAD velocity is slowed down by the hydraulic shock of blood to the VAD, the time interval incr (h) This could be useful. Therefore, to increase speed, when blood accelerates too rapidly, a speed command signal n is generated. VAD set (t) Increased speed should be achieved through a smooth trajectory to avoid hemolysis or other undesirable hemodynamic side effects, such as aspiration or cavitation caused by VAD.

[0057] Additionally, the control device can be configured to operate for a predetermined pulse duration. pulse (h) Then the speed command signal n ends VAD set (t) The pulse.

[0058] Alternatively, the control device can be configured to [address the duration of the heart rate-dependent pulse]. assist (h) That is, the heart rate (HR) controlled by the control device. (h) After the adapted pulse duration, the speed command signal n ends. VAD set (t) The pulse. Specifically, the control device can be configured to terminate the velocity command signal n when at least one predetermined characteristic event of the cardiac cycle occurs. VAD set (t) The pulse.

[0059] Additionally, the control device can be configured to operate at a predetermined time interval before or during at least one predetermined characteristic event of the cardiac cycle. red (h) End speed command signal n VAD set (t) The pulse.

[0060] For example, the predetermined characteristic events could be the onset of assisted cardiac diastole and / or the closure of the aortic valve.

[0061] For example, at least one event could be the onset of assisted diastole. Therefore, the control device can be configured to learn of the occurrence of an event based on a signal including information about characteristic events such as the onset of diastole. Thus, the speed command signal n VAD set (t) The pulses can be synchronized, for example, at the time of the maximum pressure drop in the ventricle of the assisted heart. Note that the time of the maximum pressure drop marks the beginning of ventricular diastole (the diastolic moment) following the previous cardiac contraction.

[0062] Alternatively or additionally, the control device may be configured to detect the occurrence of at least one event in each cardiac cycle based on at least one internal signal of the control device. "Internal signal" of the control device here means a signal that is internally available for analysis by the control device, such as a control signal provided by the control device to the VAD.

[0063] For example, at least one internal signal could be a current supplied for actuating the VAD, such as motor current supplied to the VAD. Therefore, the control device can be configured to determine the occurrence of at least one event in each cardiac cycle based on analysis of the current signal and / or its processed version, such as time derivatives, e.g., a first time derivative.

[0064] For example, the VAD could be the aforementioned rotary blood pump. The blood pump may include an actuator, such as a rotary electric motor, for driving a rotary thrust element, such as an impeller, to generate a corresponding blood flow. During the operation of the blood pump, the electric motor consumes motor current to generate a set speed command signal n according to the motor and the rotary thrust element. VAD set (t) To achieve the corresponding target speed level. The desired motor current I used to achieve the target speed. VAD (t) Depends on the current blood pressure difference that the blood pump needs to overcome. p (t) For example, aortic blood pressure (AoP) (t) and left ventricular blood pressure (LVP) (t) The difference between p (t) = AoP (t) – LVP (t) .

[0065] In other words, the current supplied to the blood pump directly corresponds to the current required by the blood pump's motor to achieve the set speed. I VAD (t) = f(n VAD set (t) , p (t) ).

[0066] Therefore, the motor current supplied to the VAD by the control device or the supply unit controlled by the control device can be used as an internal signal to detect the occurrence of at least one event in each cardiac cycle.

[0067] In addition, the control device can also be configured to estimate the current VAD-induced blood flow Q. VAD (t) It is based on the current signal and on known calculation specifications, which is the correlation of pump characteristics between motor current, pump flow rate and pressure difference at a given speed.

[0068] Alternatively or additionally, the control device may be configured to learn of the occurrence of at least one event in each cardiac cycle from at least one external signal provided to the control device. “External signal” herein refers to a signal received by the control device from external sensors, such as one or more blood pressure sensors of a VAD, and / or from external devices such as a patient monitoring unit or an electrocardiograph (ECG). These external signals may be fed into the control device via appropriate interfaces or input terminals to be available in the control device for processing and / or analysis.

[0069] For example, a measurement signal can represent the blood pressure difference between the outlet and inlet of the VAD. p (t) Blood pressure (LVP) in the ventricles of the assisted heart (t) Aortic blood pressure (AoP) adjacent to the assisted heart (t) CVP (cardiac vena cava blood pressure) adjacent to the assisted heart (t) PAP (pulmonary artery blood pressure) adjacent to the assisted heart (t) At least one of them. The waveforms of all these measured signals may contain information describing the timing of specific characteristic events in the cardiac cycle.

[0070] For example, if the VAD is the rotary blood pump discussed above, it may include an inlet for drawing blood from the heart (e.g., from inside the ventricles) and an outlet for spraying blood into a vessel adjacent to the heart, such as a benign artery, which may be the aorta or the pulmonary artery, depending on whether the VAD is inserted on the left or right side of the heart.

[0071] For example, as disclosed in US 5,911,685 A, a VAD may include at least one of a pressure sensor for measuring blood pressure at the VAD inlet, such as ventricular pressure of the assisted heart, and a pressure sensor for measuring blood pressure in blood vessels adjacent to the heart, such as the aorta or pulmonary artery adjacent to the assisted heart. Optionally or additionally, the VAD may include a differential pressure sensor for measuring the differential blood pressure between the VAD outlet and inlet.

[0072] Additionally, the control device can be configured to receive, store, and analyze at least one measurement signal containing information about characteristic points of the cardiac cycle, and can be used to estimate the current working phase of the heart during the cardiac cycle. The control device can then be configured to predict the timing of the recurrence of a specific characteristic during the next cardiac cycle based on information about previous cardiac cycles.

[0073] Basically, in all embodiments, at least one measurement signal may be an ECG signal, a measurement signal representing blood pressure in the left or right ventricle of the heart, or a measurement signal representing blood pressure in the vena cava, aorta, or pulmonary artery adjacent to the heart.

[0074] Therefore, in order to predict the next time of at least one event based on information from previous cardiac cycles, the selected signal may preferably contain information about the cardiac cycle, such that the time of at least one event in each cardiac cycle can be predicted based on the selected measurement signal and events detected during previous cardiac cycles.

[0075] Additionally or alternatively, the control device may be configured to eliminate the effect of VAD on active cardiac assist in the measurement signal from the measurement signal. In particular, the control device may be configured to analyze at least two, preferably independent, measurement signals through data fusion for the purpose of detecting predetermined events in the cardiac cycle, despite the effect of VAD-induced pressure changes on cardiac dynamics.

[0076] In a particular embodiment, the control device may be configured to set the speed of the VAD such that during the diastolic phase of the cardiac cycle of the assisted heart, the amount of blood ejected by the VAD into the benefit artery, such as the aorta or pulmonary artery, is sufficiently low, such that the blood volume is retained in the corresponding ventricle and that the co-ejection of the VAD and the ventricle during cardiac systole results in a preferred minimum peak flow rate, i.e., the minimum peak flow rate is preferably about 6 L / min, more preferably 7 L / min, most preferably 8 L / min or more (as described above).

[0077] Peak systolic flow rate depends largely on the native heart's co-ejection capacity, specifically on ventricular preload, ventricular filling level, cardiac contraction level, and achievable peak VAD flow rate. As mentioned above, the total peak flow rate Q per heartbeat... total|max (h) Total injection volume per heartbeat (EV) (h) This will require a sufficient increase in systemic blood pressure during systole. However, this also depends on the patient's body mass index or surface area, vascular compliance, and peripheral resistance. In other words, in smaller patients, Q... total|max (h) A minimum total peak flow rate of 6 L / min may be sufficient, but a higher total peak flow rate may be required in larger patients (as described above). A particularly high total peak flow rate may be needed if the vascular bed is dilated or wide open.

[0078] Additionally, the control device can be configured to measure only the mean arterial blood pressure obtained with each heartbeat. Not falling to the predetermined threshold The following refers to the adjustment of the velocity command signal n in the form of pulses during the cardiac cycle. VAD set (t) .

[0079] Minimum VAD-induced blood flow Q VAD(h) can correspond to the desired minimum cardiac assistance provided by the VAD to a weakened heart. The idea is that the VAD can be operated to achieve the desired vWF recruitment while ensuring the provision of the desired minimum blood flow. For example, the currently desired blood flow may be related to the patient's current perfusion needs, while taking into account the time period requiring high assistance, such as daytime activity, walking, climbing stairs, etc., in which case the VAD will run at a relatively high average speed. Periods when the patient's perfusion needs are low, such as at rest, while sleeping, etc., can be used to run the VAD at a lower average speed. This will help increase pulsation and assist vWF recruitment while still maintaining a certain level of blood flow support. Of course, more complex schemes are possible, where the current blood flow is relative to a specific, such as average VAD-induced blood flow. Q VAD (h) The corresponding cardiac assist requirements are considered in a continuous manner. Therefore, the control device can be configured to use any available surplus between the currently desired minimum blood flow and the maximum blood flow that the VAD can provide to restore and maintain the residual pulsation presented herein.

[0080] It should be noted that it is also possible to suggest synchronizing velocity changes in a "y in x" manner, i.e., the proposed velocity pulses are generated only in y of x consecutive cardiac cycles. For example, velocity pulses intended to restore or maintain the desired minimum pulsation can be triggered in one of two, three, or four ways, or in two of three, two of four, or two of five ways, i.e., in one cardiac cycle of every two, three, or four consecutive cardiac cycles and in two cardiac cycles of every three, four, or five consecutive cardiac cycles, respectively. This can be particularly beneficial if the heart rate is too high or the level of pump assist in the heart is insufficient. Thus, the enhanced pulsation is provided only intermittently. This has been found to serve perfectly for the purpose of vWF recruitment. For example, the control device can be additionally configured to set the velocity n of the VAD during at least y periods of the other (xy) consecutive cardiac cycles of the assisted heart. VAD (t) This ensures that the average arterial blood pressure per heartbeat remains above a predetermined threshold. ).

[0081] Finally, the aforementioned functions or groups of functions of the control device can be implemented by corresponding computing units, hardware, software, or any combination thereof. Such computing units can be configured by means of corresponding computer programs with software code to enable the computing units to perform their respective required control steps. Such programmable computing units are well known in the art and to those skilled in the art, and therefore need not be described in detail here. Furthermore, the computing units may include specific dedicated hardware useful for particular functions, such as one or more signal processors for processing and / or analyzing, for example, the measurement signals discussed. Additionally, the respective units for controlling the drive speed of the VAD can also be implemented by their respective software modules.

[0082] The corresponding computer program can be stored on a data carrier containing the computer program. Alternatively, the computer program can be transmitted, for example, via the Internet, in the form of a data stream that includes the computer program but does not require a data carrier.

[0083] A second aspect of the invention provides a VAD that includes one of the control devices according to the first aspect of the invention. For example, the VAD may be a rotary blood pump, i.e., a blood pump driven by a rotary electric motor.

[0084] For example, this blood pump can be catheter-based, implanted through a corresponding blood vessel, or placed directly into the heart.

[0085] For example, a VAD can be a blood pump disclosed, for instance, in US 5,911,685, which is specifically designed for temporary placement or implantation in a patient’s left or right heart.

[0086] Preferably, the VAD is a low-inertia device, including but not limited to one or more of the following features: (1) the movable, particularly rotatable, components of the VAD, such as rotors or impellers, may have a low mass made of low-weight materials, such as plastics, synthetic materials, etc.; (2) a drive unit, such as an electric motor, is arranged near, preferably very close to, and most preferably adjacent to, the components driven by the electric motor (e.g., rotors or impellers), and, if based on a conduit, preferably does not have a rotating drive cable or drive line, but rather an electric wire; (3) the coupling or connection (e.g., shaft) of the engine connected to the components driven by the engine (e.g., rotors or impellers) may be short; (4) all movable, particularly rotatable, components of the VAD have a small diameter. Note that the foregoing list of features is not claimed to be complete, i.e., the device may include other or alternative features that make the device a low-inertia device. Attached Figure Description

[0087] The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1An exemplary embodiment of a VAD placed through the aorta and extending through the aortic valve into the left ventricle of the heart is shown, along with a block diagram of an exemplary embodiment of a control device for the VAD; Figure 2 Showing more details Figure 1 A side view of an exemplary VAD; Figure 3 A graph with exemplary signal waveforms is shown, representing a) aortic pressure (AoP(t)), b) left ventricular pressure (LVP(t)), c) ECG (ECG(t)), and d) velocity command signal trajectory (n). VAD set (t) ), and e) the corresponding trigger signal sequence ( (t)) is used to describe in Figure 1 Under the control of the control device, by means of Figure 1 and 2 The principle of VAD restoration and / or maintenance of blood pulsation rate control; Figure 4 The electrical equivalent circuit of an electrical model in the aorta approximating the so-called Windkessel effect is shown; Figure 5 This shows the effect of cardiac blood flow Q. heart (t) and pump blood flow Q pump Results for five different simulation scenarios regarding aortic pressure (t) (top figure) and aortic pressure AoP(t) (bottom figure). Detailed Implementation

[0088] Figure 1 A catheter-based rotary blood pump (hereinafter referred to as "blood pump") on the left hand side is shown, which is described herein as an exemplary embodiment of a VAD. Figure 2 The exemplary blood pump is shown in more detail.

[0089] As stated above, an important physical prerequisite discovered by the inventors of the VAD implementation for the application presented herein is the absence of any associated inertia. Such as Figure 2 The rotary blood pump of the catheter-based pump type shown does not have any associated inertia, which will hinder the implementation of the proposed speed control scheme with Bonne speed modulation.

[0090] The blood pump is based on catheter 10 (catheter-based blood pump), through which it is temporarily introduced into the left ventricle 16 of the heart via the aorta 12 and aortic valve 15. (As...) Figure 2As shown in more detail, in addition to catheter 10, the blood pump also includes a rotary pumping device 50 fixed to the end of catheter tube 20. The rotary pumping device 50 includes an electric motor portion 51 and a pump portion 52 axially distanced therefrom. A flow sleeve 53 is connected to the pump portion 52 at one end, extends from the pump portion 52, and has an inflow cage 54 at its other end. The inflow cage 54 has a flexible, resilient tip 55 attached thereto. The pump portion 52 includes a pump housing with an outlet opening 56. Furthermore, the pumping device 50 includes a drive shaft 57 protruding from the electric motor portion 51 into the pump housing of the pump portion 52. The drive shaft 57 drives an impeller 58 as a thrust element, through which blood can be drawn through the inflow cage 54 and discharged through the outlet opening 56 during blood pump operation.

[0091] When adapted accordingly, for example when a blood pump needs to be placed on the right side of the heart, the pumping device 50 can also pump in reverse. In this respect, and for the sake of completeness, Figure 1 A rotary blood pump is shown as a specific example of a VAD located in the left heart and used to assist the left heart. To assist the right heart, the rotary blood pump of this example can be temporarily introduced into the right heart from the vena cava and located within the right heart, allowing blood to be ejected into the pulmonary artery. In this configuration, the blood pump can be configured to draw blood from the vena cava or the right ventricle and to eject blood into the pulmonary artery. That is, the principles and functions described by a specific embodiment can be accordingly transferred to right-sided cardiac assistance. Therefore, a detailed description is unnecessary.

[0092] exist Figure 1 and Figure 2 In the pumping device 50, three lines—two signal lines 28A and 28B, and a power line 29 for supplying current to the motor section 51—pass through the conduit tube 20 of the conduit 10. The two signal lines 28A and 28B and the power line 29 are connected to the control device 100 at their proximal ends. It goes without saying that additional wiring for further functions may exist; for example, wiring for the cleaning fluid (not shown) may also pass through the conduit tube 20 of the conduit 10 to reach the pumping device 50. Additional wiring can be added based on different sensing technologies.

[0093] like Figure 2As shown, signal lines 28A and 28B are part of a blood pressure sensor, each having a sensor head 30 and 60 located outside the housing of the pump section 52, respectively. The sensor head 60 of the first pressure sensor is associated with signal line 28B. Signal line 28A is connected to and associated with the sensor head 30 of the second blood pressure sensor. For example, the blood pressure sensor can be an optical pressure sensor operating according to the Fabry-Pérot principle as described in US 5 911 685 A, in which case the two signal lines 28A and 28B are optical fibers. However, other pressure sensors can also be used. Essentially, the signals from the pressure sensors carry information about the pressure at the sensor location and can be from any suitable physical source, such as an optical, hydraulic, or electrical source, which is transmitted via the corresponding signal lines 28A and 28B to the corresponding input terminals of the data processing unit 110 of the control device 100. Figure 1 In the example shown, the pressure sensor is configured to measure aortic pressure AoP(t) via sensor head 60 and left ventricular pressure LVP(t) via sensor head 30.

[0094] Data processing unit 110 is configured to acquire all external and internal signals for actual signal processing, including, for example, calculating the difference between two pressure signals as a basis for estimating pump flow, performing signal analysis to detect characteristic events during the cardiac cycle based on the acquired and calculated signals, and generating a series of trigger signals via a trigger signal generator. (t), used to trigger the speed command signal generator 120 (see details below).

[0095] The data processing unit 110 is connected to the additional measuring device 300, such as the patient monitoring unit 310 and the electrocardiograph 320, via corresponding signal lines; these devices are merely two examples, meaning other measuring devices can also provide useful signals and therefore can be used. The electrocardiograph 320 provides the ECG signal ECG(t) to the data processing unit 110.

[0096] The control device 100 also includes a user interface 200, which includes a display 210 and a communication interface 220. The display 210 shows setting parameters, monitoring parameters, such as measured pressure signals, and other information. Furthermore, the communication interface 220 allows a user of the control device 100 to communicate with it, for example, to change settings for the entire system.

[0097] The data processing unit 110 is specifically configured to generate a series of trigger signals by means of a trigger signal generator. Real-time analysis of the current signal value (t) is used to obtain or predict the occurrence time of one or more predefined characteristic events during the cardiac cycle of the assisted heart. The resulting trigger signal sequence... (t) is forwarded to speed command signal generator 120 to trigger a change in speed command signal.

[0098] Furthermore, the data processing unit 110 is also configured to analyze these speed command signals n VAD set (t) The previous value. That is, the data processing unit 110 is also configured to predict the occurrence time of at least one predefined characteristic event in the upcoming cardiac cycle based on stored information about characteristic events that occurred during the current and / or previous cardiac cycles.

[0099] A specific characteristic event of the cardiac cycle can be the initiation of cardiac contraction at the beginning of systole. The occurrence of this detected or predicted characteristic event is used to enable the velocity command signal n proposed in this paper. VAD set (t) An event in which the pulse is synchronized with the cardiac cycle.

[0100] Speed ​​command signal generator 120 is configured to generate and adjust speed command signal n of pumping device 50 VAD set (t) It is provided to the speed control unit 130 as an event-based command signal generator in the feedforward setting (first setting) or for pressure control in the external feedback closed-loop setting (second setting).

[0101] In the first configuration, the speed command signal generator 120 is provided by at least one trigger signal sequence from the data processing unit 110. (t) Triggered. In the second setting, the speed command signal n VAD set (t) Provided by a pressure control algorithm (as command signal generator 120), the pressure control algorithm operates in an external feedback loop and is fed external and internal signals by a data processing unit 110, and at least one trigger signal sequence provided by the data processing unit 110. (t) triggers to achieve the desired minimum pulsation. .

[0102] Therefore, the speed control unit 130 transmits the motor current I through the power line 29 guided through the conduit tube 20. VAD (t) The motor section 51 of the pumping device 50 is supplied according to the speed command signal n. VADset (t) Control the speed of VAD n VAD (t) The supplied motor current I VAD (t) The current level corresponds to the current currently required by the pumping device 50, in order to establish the speed command signal n VAD set (t) The defined target speed level. The pump also communicates with the control unit 100 via power line 29.

[0103] Such as the supplied motor current I VAD (t) The measurement signal is provided to the data processing unit 110 for further processing, and the measurement signal is used as a representative signal of the internal signal of the control device 100.

[0104] According to a first aspect of the invention, the control device 100 is configured to change Figure 1 and Figure 2 The speed of the blood pump, as an exemplary embodiment of a VAD for cardiac assistance.

[0105] The control device 100 is specifically configured to change the speed of the blood pump within the cardiac cycle of the assisted heart through at least one event in each cardiac cycle, resulting in a change in blood flow through the pump, the speed change being synchronized with the heartbeat, and the at least one event being related to a predetermined event in the cardiac cycle. That is, the speed command signal generator 120 can be provided by at least one sequence of trigger signals from the trigger signal generator of the data processing unit 110. (t) Triggering: The trigger signal generator acquires information about at least one specific event during the cardiac cycle, detects its occurrence, and uses the corresponding signal information to set the trigger signal sequence. (t).

[0106] However, it should be noted that providing a trigger signal sequence The trigger signal generator of (t) can rely on multiple events in the cardiac cycle, which are detected and analyzed during each cardiac cycle to obtain the corresponding trigger signal sequence. (t), used to adjust the command signal n VAD set (t) This changes the speed of the blood pump. n VAD (t) .

[0107] As described above, the blood pump includes a rotary pumping device 50, and the impeller's (rotational) speed n VAD (t)Controlled by speed control unit 130. Blood pump speed command signal n VAD set (t) is adjusted by the command signal generator 120.

[0108] According to the first embodiment of the planned change in blood flow generated by the blood pump, the control device 100, in particular the speed command signal generator 120, is configured to adjust the speed command signal n of the rotary pumping device 50. VAD set (t), which makes the final velocity n of VAD VAD (t) is changed to generate VAD-induced blood flow Q VAD (t), which induces a pressure pulse during each cardiac cycle.

[0109] To better understand, Figure 3 An example of the potential effects of velocity changes is shown in the figure. Figure 3 A diagram with an exemplary waveform is shown.

[0110] Figure 3 The waveform in a) represents the aortic pressure signal, which distinguishes physiological (unassisted) aortic pressure (AoP). (t) (Dashed line) and the desired (assisted) aortic pressure (Solid line).

[0111] Figure 3 The waveform in b) represents the signal of left ventricular pressure (LVP(t)) and illustrates characteristic pressure values ​​and / or events during the cardiac cycle that can be used to generate or obtain trigger signal sequences. (t).

[0112] Figure 3 The waveform in c) represents the ECG signal.

[0113] Figure 3 The illustration shows an example in Figure 1 Used under the control of the control device 100 Figure 1 and Figure 2 The principle of blood pumping to restore and maintain pulsating blood pressure.

[0114] to this end, Figure 3 d) shows the speed command signal n VAD set (t) A specific example.

[0115] exist Figure 3 e) shows the corresponding trigger signal sequence. (t).

[0116] Speed ​​command signal n VADset (t) is used for pump speed change, which corresponds to the signal output of speed command signal generator 120 and is forwarded to speed control unit 130. Trigger signal sequence (t) is the basis for event-based speed command signal generation or event-based closed-loop pressure control, which leads to changes in the speed command signal n. VAD set (t), whose changes are synchronized with the heartbeat.

[0117] Command signal n VAD set (t) represents the initial velocity level at the start of the velocity pulse. n VAD set (t) = n VAD set,basic (j) To the increasing speed level n VAD set (t) = n VAD set,basic (j) + n VAD set (j) The speed increases, among which n VAD set (j) This represents the speed difference during the speed pulse.

[0118] exist Figure 3 In this model, the start of the velocity pulse is synchronized with the end of cardiac diastole. Furthermore, it is also shown that at the end of the velocity pulse, the velocity level increases from the initial velocity level. n VAD set (t) = n VAD set,basic (j) + n VAD set (j) Back to basic speed level n VAD set (t) = n VAD set,basic (j) The speed decreased.

[0119] exist Figure 3In this process, the end of the velocity pulse is synchronized with the end of the heart contraction. These velocity changes each represent a possible implementation of the velocity variation for achieving the desired minimum pulsation as described in the general section of this document.

[0120] A decrease in velocity is triggered, resulting in a longer duration of the heart rate-dependent pulse. assist (h) The speed command signal n for the duration of the pulse. VAD set (t) pulse and heart rate HR (h) Adaptation. That is, the instruction signal generator 120 is configured to generate velocity pulses with heart rate-dependent pulse durations.

[0121] Alternatively, a decrease in speed can be triggered to achieve a predetermined pulse duration. pulse (j) Therefore, the command signal generator 120 can be configured to generate pulses with a predetermined pulse duration. pulse (j) The velocity pulse.

[0122] In the example shown ( Figure 3 d) The velocity difference increases at the start of the velocity pulse. n VAD set (j) Increase, at, for example, time point t LVP j,ED The pulse ends at a certain point, and the velocity decreases at the end of the velocity pulse, for example, at time point t. AoP j,ES End of section.

[0123] Preferably, in operation, the speed command signal generator 120 is configured to adjust the speed difference accordingly. n VAD set (h) To control the pulsation ∆AoP(h). As mentioned above, in = [15 … 30] mmHg range. The expected minimum pulsation is considered sufficient to avoid the occurrence of vWF deficiency and / or to improve microvascular perfusion.

[0124] Furthermore, as described above, the data processing unit 110 is configured to measure and / or calculate the current mean arterial blood pressure for each heartbeat. The current value is then provided to the speed command signal generator 120. For this purpose, the speed command signal generator 120 is also configured to adjust the speed command signal n. VAD set(t) To preferably prevent arterial blood pressure from dropping below a predetermined threshold .

[0125] As discussed in the general section, sufficient restoration and / or maintenance of a minimum blood pressure pulsation can be achieved by varying the speed of the rotary pump 50, resulting in a VAD-induced blood flow Q. VAD (t) significantly decreases during cardiac diastole and / or significantly increases during cardiac systole. Therefore, in a particular embodiment, the velocity command signal generator 120 is configured to adjust the velocity command signal n. VAD set (t) This results in a low volume of blood ejected into the aorta (or pulmonary artery) during diastole in the assisted heart's cardiac cycle, allowing a predetermined amount to remain in the left (right) ventricle, and enabling the rotary pump 50 to co-eject an appropriate volume of blood with the left (right) ventricle during systole. In other words, the reduced diastolic velocity also allows for adequate cardiac filling, making it possible for blood from both the rotary pump 50 and the native heart to be co-ejected during systole. Regarding this, the inventors have discovered that the pump and the native heart should induce a total peak flow Q during systole. total|max (h) = Q heart|max (h) + Q pump|max (h) > 6 L / min…10 L / min, This results in a total ejection volume EV(h) = EV heart (h) + EV pump (h) = 40…70 ml, This achieves the desired minimum pulsation. 15…30 mmHg. However, the target requires a minimum pulsation. It won't be a fixed value, but can vary based on the recruitment of vWF. Furthermore, if the weakened heart's natural pulse is already higher than the desired minimum pulse, the pulse will certainly not necessarily decrease.

[0126] The inventors have verified the value of Q, the peak flow rate of the pump and the heart per heartbeat, using a mathematical model of the electrical equivalent circuit. pump | max (h) and Q heart | max (h), and the corresponding total injection volume EV of the pump and heart for each heartbeat. pump (h) and EV heart (h) The model used is as follows: Figure 4 As shown.

[0127] Figure 4 The circuit diagram shows an electrical model that approximates the dynamics of the so-called Windkessel effect in the aorta when the heart ejects blood. The electrical model consists of a resistor (R1 = 0.05 ohms) and a capacitor (C2 = 1.7 F), the former representing the resistance of the aortic valve and connected in series with another resistor (R2 = 1.32 ohms) representing the peripheral arterial system, which represents arterial compliance. Furthermore, in this model, the (residual) cardiac output Q is assumed to be constant. heart (h) Blood flow Q of the pump pump (h) As a current source. Using the standard Impella pump. ® 5.0 represents a rotary blood pump; for more details, see: Catanho et al., “Model of Aortic Blood Flow Using the Windkessel Effect”, Beng 221, Mathematical Methods in Bioengineering, Report, 2012.

[0128] Figure 5 The results for five different simulation scenarios are shown. The table below displays the results for the five different simulation scenarios, with total blood flow including heartbeats and corresponding pulses. j (Q total (j) ) and( AoP (j) Additional information.

[0129] exist Figure 5 In the middle, from left to right, the scenarios ① to ⑤ are as follows: Scenario 1 - "Healthy Heart": Assuming native heart function, resulting in peak cardiac flow Q heart | max (j) =15 L / min, pulsation is AoP (j) = 40 mmHg (120 / 80 mmHg), which has a common mean aortic blood pressure = 105.4 mmHg.

[0130] Scenario ② - "Weak Heart, Unassisted": Cardiac function is reduced to one-third of its original capacity, resulting in a decrease in peak cardiac flow Q. heart | max(j) = 5.4 L / min, very low pulsation AoP (j) = 14.5 mmHg (42 / 28 mmHg), which has a non-physiologically low mean aortic blood pressure. = 36.8 mmHg without an implanted pump.

[0131] Scenario 3 - "Complete Unloading (P4)": The weakened heart is assisted by a pump of speed level P4 to generate maximum flow, resulting in a total peak flow of Q. total | max (j) = Q heart | max (j) + Q pump | max (j) = 8.5 L / min, moderate pulsation AoP (j) = 17.2 mmHg (96 / 79 mmHg), which has the physiological mean aortic blood pressure. = 89.8 mmHg.

[0132] Scenario 4 - "Low Pulsation P4 / P2": The weakened heart is assisted by a pump whose velocity varies with the systolic velocity (P4) of Scenario 3 and the low diastolic velocity (P2), resulting in a total peak flow rate Q. total | max (j) = Q heart | max (j) +Q pump | max (j) = 8.5 L / min and the lower mean aortic pressure in case ③ = 70.6 mmHg is a relatively high moderate pulsation AoP (j) = 20.4 mmHg (78 / 58 mmHg).

[0133] Scenario 5 - "High Pulsation P9 / P2": A weakened heart is assisted by a pump whose velocity varies with the highest possible velocity during systole (P9) and the low velocity during diastole (P2), resulting in a high total peak flow rate Q. total | max (j) = Q heart | max(j) + Q pump | max (j) = 10.3 L / min and at moderate mean aortic pressure The highest possible pulsation at 85.2 mmHg AoP (j) = 27.4 mmHg (95 / 69 mmHg).

[0134] It should be noted that in cases ③-⑤, it is assumed that the heart ejects the same amount of fluid during cardiac contraction, despite the different degrees of diastolic unloading of the pump. In summary, the simulation results highlight the fact that velocity variations can be concentrated in increasing pulsations while receiving decreasing mean aortic pressure, or concentrated in increasing mean aortic pressure while receiving decreasing pulsations. Physical and physiological limitations, such as very low inertia and hemolysis, are taken into account here.

[0135] Specifically, the data processing unit 110 is configured to trigger the speed command signal generator 120, causing the speed command signal n VAD set (t) The pulse is detected or predicted at the start and / or end of at least one predetermined event in the cardiac cycle. At least one trigger signal sequence is generated by the trigger signal generator of the data processing unit 110. (t) is provided to the speed command signal generator 120.

[0136] In the preferred embodiment and as Figure 3 As shown, the speed command signal generator 120 is configured to generate a signal at a predetermined time interval before a characteristic event of the cardiac cycle occurs. incr (h) Initialize speed command signal n VAD set (t) With the increase of [something], it is used to generate a trigger signal sequence. The basis of (t). Trigger signal sequence (t) can be used to moderately change the pump speed to avoid suction, blood damage, etc., or to allow the pump speed to be increased in a timely manner to address the phase shift problem between speed changes and the resulting pressure changes (vascular compliance and blood inertia), for cardiac contraction combined with jet.

[0137] exist Figure 3 In the example shown, the onset time of left ventricular contraction is used as the trigger signal sequence generated by the trigger signal generator. (t) represents the characteristic time considered. Left ventricular contraction begins immediately after the appearance of the R wave in the corresponding ECG signal. Therefore, the velocity command signal generator 120 can be configured to obtain a trigger signal sequence based on the ECG signal. (t), which is provided to the data processing unit 110. The data processing unit 110 can be configured to receive ECG signals from the (external) ECG device 320 and generate a trigger signal sequence by means of a trigger signal generator. (t).

[0138] As described above, the data processing unit 110 can use another measurement signal to generate a trigger signal sequence. (t), indicating that, for example, the onset of left ventricular contraction can be used as an event that occurs before the start of the cardiac systolic ejection phase. For example, in Figure 3 In b), some eigenvalues ​​and times are labeled as left ventricular pressure (LVP). (t) An example of a signal, namely the minimum value LVP. min (j) Maximum LVP min (j) Its maximum change over time dLVP (j) / dt| max , and its minimum change over time dLVP (j) / dt| min .

[0139] In summary, the speed command signal generator 120 utilizes at least one trigger signal sequence provided by the data processing unit 110. (t) makes the speed command signal n VAD set (t) The adjustment is synchronized with the cardiac cycle, so that the velocity pulse is initialized before the onset of ventricular systole and / or before the appearance of the R wave in the ECG signal.

[0140] Used to initialize the speed command signal n VAD set (t) Increased scheduled time interval incr (h) It can be set to, for example, approximately incr (h) = 150 ms, preferably incr (h) = 100 ms, most preferably, before the relevant characteristic events in the cardiac cycle. incr (h)≤ 100 ms. The inventors further discovered that this can be achieved through a predetermined time interval. incr (h Ensuring that blood flow does not accelerate too rapidly is considered to reduce the possibility of blood injury and / or undesirable hemodynamic effects. Therefore, the velocity command signal generator 120 is configured to adjust the velocity command signal n. VAD set (t) This makes the speed n of VAD VAD (t) Change smoothly.

[0141] As a specific example, Figure 3 d) shows the speed n for linearly increasing or decreasing VAD. VAD (t) The speed command signal n of the ramp VAD set (t), but it can also be in other forms, such as exponential increase or decrease in speed.

[0142] Finally, the speed command signal generator 120 is configured to transmit the speed n of the VAD. VAD (t) Adjust back to the initial speed level n VAD set,basic (t) To the predetermined pulse duration pulse (h) Then the current velocity pulse ends.

[0143] Optionally or additionally, the speed command signal generator 120 is configured to adjust the speed command signal n VAD set (t) Used to change the velocity n of VAD when a predetermined characteristic event of the cardiac cycle occurs. VAD (t) To end the current velocity pulse.

[0144] In a preferred embodiment, the predetermined event is the initiation of assisted cardiac diastole and / or aortic valve closure. Alternatively, it may be considered to initialize the velocity command signal n before, during, or after a predetermined characteristic event in the cardiac cycle. VAD set (t) The reduced predetermined time interval red (h) Preferably, the trigger used to terminate the velocity pulse is a sequence of trigger signals. (t) is a part of the time interval before the onset of ventricular diastole by the data processing unit 110. red (h) Provided. Preferably, the trigger signal is based on a prediction of the onset of ventricular diastole detected during a previous cardiac cycle.

[0145] For example, when left ventricular pressure (LVP) (t) Drops below aortic pressure AoP (t) When, or correspondingly, when the pressure difference between the inflow cage 54 and the outlet opening 56 of the flow sleeve 53 becomes less than zero, the closure of the aortic valve can be determined.

[0146] The data processing unit 110 is also configured to obtain a trigger signal sequence from at least one signal. (t), the at least one signal includes information relating to the closure of the aortic valve of the assisted heart, which is a characteristic event in the cardiac cycle.

[0147] For example, a useful signal could be a measurement of the left ventricular pressure (LVP(t)) of the assisted heart and / or the aortic pressure (AoP(t)) adjacent to the assisted heart. If the blood pump is configured for assistance and placed on the right side of the heart, the signal could be a measurement of the blood pressure (CVP(t)) in the vena cava adjacent to the assisted heart and / or the right ventricular pressure (RVP(t)) and / or the blood pressure (PAP(t)) in the pulmonary artery adjacent to the assisted heart.

[0148] Data processing unit 110 is configured to receive the required motor current I from the speed control unit 130 supplied to the rotary pumping device 50. VAD (t) Derivation of trigger signal sequence (t). As discussed elsewhere in this article, the required motor current I VAD (t) This reflects the energy required for the rotary pumping device 50 to maintain a set speed value. Therefore, the command signal generator 120 can be configured using a corresponding trigger signal sequence provided by the data processing unit 110. (t) Triggered.

[0149] Preferably, the data processing unit 110 is configured to receive, store, and analyze at least one measurement signal containing characteristic information of the circulatory system and the cardiac cycle, so as to predict at least one event in each heartbeat based on the analysis results of previous cardiac cycles. Most preferably, the data processing unit 110 is configured to analyze at least two measurement signals to filter the effects of pressure changes caused by the pump, thereby enabling reliable detection of characteristic events in the cardiac cycle.

Claims

1. A control device (100) for controlling the rotational speed of a non-pulsatile ventricular assist device (VAD) (50) via an event-based intrapulse control strategy. n VAD (t) ), wherein the control device (100) is configured to change the rotational speed of the VAD (50) during the cardiac cycle of the assisted heart. n VAD (t) ), and through at least one trigger signal sequence associated with at least one predetermined characteristic event in the cardiac cycle ( (t) causes the rotational speed ( n VAD (t) The change in ) is synchronized with the heartbeat of the assisted heart, wherein, The control device (100) is configured to obtain the at least one trigger signal sequence from the current supplied to the actuator of the VAD (50). (t)) one of which, wherein the control device (100) is configured to distinguish due to the rotational speed of the VAD (50) n VAD (t) The changes in current caused by the change in the assisted heart and the changes in current caused by the assisted heart going through the cardiac cycle.

2. The control device (100) according to claim 1, wherein, The control device (100) is configured to obtain the at least one trigger signal sequence from at least one signal, which is a processed measurement signal. (t)), wherein the processed measurement signal represents at least one of the following physical quantities: the blood pressure difference between the outlet of the VAD (50) for blood ejection and the inlet of the VAD (50) for blood intake, the blood pressure in the ventricle of the assisted heart, the blood pressure in the aorta adjacent to the assisted heart, the blood pressure in the vena cava adjacent to the assisted heart, and the blood pressure in the pulmonary artery adjacent to the assisted heart.

3. The control device (100) according to claim 1 or 2, wherein, The control device (100) is configured to determine characteristic information about the circulatory system within the cardiac cycle based on at least one of at least one processed measurement signal, and to obtain or predict at least one predetermined characteristic event of the upcoming cardiac cycle based on the characteristic information determined during a previous cardiac cycle.

4. The control device (100) according to claim 3, wherein, The control device (100) is configured to determine the rotational speed of the VAD (50) from at least two processed measurement signals when the event is obtained or predicted. n VAD (t) The impact of changes in ( ).

5. The control device (100) according to claim 1 or 2, wherein, The control device (100) is configured to increase the rotational speed of the VAD (50) during the contraction of the assisted heart. n VAD (t) ) and / or reduce the rotational speed of the VAD (50) during diastole of the assisted heart. n VAD (t) ).

6. The control device (100) according to claim 5, wherein the control device (100) is configured to be relative to a basic speed level n in each case. VAD set,basic (t) And increasing or decreasing the rotational speed ( n VAD (t) ).

7. The control device (100) according to claim 1 or 2, wherein, The control device (100) is configured to change the rotational speed of the VAD (50) only when the average VAD-induced blood flow can be set to be higher than the current desired minimum blood flow requirement of the assisted heart.

8. A VAD (50) for cardiac assistance, comprising a control device (100) according to any one of claims 1 to 7, wherein the VAD is a non-pulsating rotary blood pump.

9. The VAD (50) according to claim 8, wherein the blood pump is catheter-based.

10. The VAD (50) of claim 8, wherein the VAD (50) is a low-inertia device comprising one or more of the following features: movable or rotatable components of the VAD (50) having a low mass made of a low-weight material; a drive mechanism arranged near or adjacent to the engine-driven components; and all movable or rotatable components of the VAD having a small diameter.

11. The VAD (50) according to claim 10, wherein at least one of the movable or rotatable component and the engine-driven component is a rotor or impeller.

12. The VAD (50) according to claim 10, wherein the low-weight material is plastic.

13. The VAD (50) according to claim 10, wherein the driving device is an electric motor.

14. The VAD (50) according to claim 10, wherein the drive device, if based on a conduit, does not have a rotary drive cable or drive line.

15. A control device (100) for controlling the rotational speed of a non-pulsatile ventricular assist device (VAD) (50) via an event-based intrapulse control strategy. n VAD (t) ), wherein the control device (100) is configured to change the rotational speed of the VAD (50) during the cardiac cycle of the assisted heart. n VAD (t) ), and through at least one trigger signal sequence associated with at least one predetermined characteristic event in the cardiac cycle ( (t) causes the rotational speed ( n VAD (t) The change in the assisted heart is synchronized with the heartbeat of the assisted heart, wherein the control device (100) is configured to obtain the at least one trigger signal sequence from at least one signal as a processed measurement signal. (t)), wherein the processed measurement signal represents the blood pressure difference between the outlet of the VAD (50) for blood ejection and the inlet of the VAD (50) for blood intake.

16. The control device (100) according to claim 15, wherein, The control device (100) is configured to determine characteristic information about the circulatory system within the cardiac cycle based on at least one of at least one processed measurement signal, and to obtain or predict at least one predetermined characteristic event of the upcoming cardiac cycle based on the characteristic information determined during a previous cardiac cycle.

17. The control device (100) according to claim 16, wherein, The control device (100) is configured to determine the rotational speed of the VAD (50) from at least two processed measurement signals when the event is obtained or predicted. n VAD (t) The impact of changes in ( ).

18. The control device (100) according to any one of claims 15 to 17, wherein, The control device (100) is configured to increase the rotational speed of the VAD (50) during the contraction of the assisted heart. n VAD (t) ) and reduce the rotational speed of the VAD (50) during the diastole of the assisted heart. n VAD (t) ).

19. The control device (100) according to claim 18, wherein the control device (100) is configured in each case relative to a basic speed level n. VAD set,basic (t) And increase and / or decrease the rotational speed ( n VAD (t) ).

20. The control device (100) according to any one of claims 15 to 17, wherein, The control device (100) is configured to change the rotational speed of the VAD (50) only when the average VAD-induced blood flow can be set to be higher than the current desired minimum blood flow requirement of the assisted heart.

21. A VAD (50) for cardiac assistance, comprising a control device (100) according to any one of claims 15 to 20, wherein the VAD is a non-pulsating rotary blood pump.

22. The VAD (50) of claim 21, wherein the blood pump is catheter-based.

23. The VAD (50) of claim 21, wherein the VAD (50) is a low-inertia device comprising one or more of the following features: movable or rotatable parts of the VAD (50) having a low mass made of a low-weight material; a drive mechanism arranged near or adjacent to the engine-driven parts; and all movable or rotatable parts of the VAD having a small diameter.

24. The VAD (50) according to claim 23, wherein at least one of the movable or rotatable component and the engine-driven component is a rotor or impeller.

25. The VAD (50) according to claim 23, wherein the low-weight material is plastic.

26. The VAD (50) according to claim 23, wherein the driving device is an electric motor.

27. The VAD (50) according to claim 23, wherein the drive device, if based on a conduit, does not have a rotary drive cable or drive line.

28. A control device (100) for controlling the rotational speed of a non-pulsatile ventricular assist device (VAD) (50) via an event-based intrapulse control strategy. n VAD (t) ), wherein the control device (100) is configured to change the rotational speed of the VAD (50) during the cardiac cycle of the assisted heart. n VAD (t) ), and through at least one trigger signal sequence associated with at least one predetermined characteristic event in the cardiac cycle ( (t) causes the rotational speed ( n VAD (t) The change in ) is synchronized with the heartbeat of the assisted heart, wherein, The control device (100) is configured to change the rotational speed of the VAD (50) only when the average VAD-induced blood flow can be set to be higher than the current desired minimum blood flow requirement of the assisted heart.

29. The control device (100) according to claim 28, wherein, The control device (100) is configured to determine characteristic information about the circulatory system within the cardiac cycle based on at least one of at least one processed measurement signal, and to obtain or predict at least one predetermined characteristic event of the upcoming cardiac cycle based on the characteristic information determined during a previous cardiac cycle.

30. The control device (100) according to claim 29, wherein, The control device (100) is configured to determine the rotational speed of the VAD (50) from at least two processed measurement signals when the event is obtained or predicted. n VAD (t) The impact of changes in ( ).

31. A VAD (50) for cardiac assistance, comprising a control device (100) according to any one of claims 28 to 30, wherein the VAD is a non-pulsating rotary blood pump.

32. The VAD (50) according to claim 31, wherein the blood pump is catheter-based.

33. The VAD (50) of claim 31, wherein the VAD (50) is a low-inertia device comprising one or more of the following features: movable or rotatable components of the VAD (50) having a low mass made of a low-weight material; a drive mechanism arranged near or adjacent to the engine-driven components; and all movable or rotatable components of the VAD having a small diameter.

34. The VAD (50) according to claim 33, wherein at least one of the movable or rotatable component and the engine-driven component is a rotor or impeller.

35. The VAD (50) according to claim 33, wherein the low-weight material is plastic.

36. The VAD (50) according to claim 33, wherein the driving device is an electric motor.

37. The VAD (50) according to claim 33, wherein the drive device, if based on a conduit, does not have a rotary drive cable or drive line.

38. A control device (100) for controlling the rotational speed of a non-pulsatile ventricular assist device (VAD) (50) via an event-based intrapulse control strategy. n VAD (t) The control device (100) is configured to base its position on the current non-auxiliary physiological pulsation in the benefit artery during the cardiac cycle. AoP (h) ) and the predetermined pulsation in the benefit artery during the cardiac cycle. The difference in pulsation between ( AoP pulse (h) ) Change the rotational speed of the VAD (50) during the cardiac cycle of the assisted heart ( n VAD (t) ), and through at least one trigger signal sequence associated with at least one predetermined characteristic event in the cardiac cycle ( (t) causes the rotational speed ( n VAD (t) The change in ) is synchronized with the heartbeat of the assisted heart, wherein, The control device (100) is configured to change the rotational speed of the VAD (50). n VAD (t) To restore or maintain or restore and maintain at least the predetermined desired minimum pulsation in the benefit artery during the cardiac cycle. ), and through the at least one trigger signal sequence ( (t) synchronizes the start and / or end of the velocity change.

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