A blood pump to support the heart

Abstract

The invention relates to a blood pump (3) for supporting a heart, comprising a rotor with a conveying element, a rotor drive, a pressure sensor (8), and a regulating device (10) for regulating pressure or a hemodynamic parameter by actuating the rotor drive, wherein the pressure and the hemodynamic parameter are determined, in particular, by means of one or more hemodynamic sensors and / or as a function of operating parameters of the pump (3). The regulating device is suitable for regulating the hemodynamic parameter successively, in particular cyclically, to different target values. By means of such regulation, the blood pump can be operated in an optimized manner and the operation of the blood pump can be deliberately varied to meet the needs of the patient in order to achieve specific goals.

Description

[0001] This application is a divisional application of the invention patent application with the original application number 201680072678.8 (international application number PCT / EP2016 / 076391) (application date: November 2, 2016, invention name: blood pump for supporting the heart). Technical Field

[0002] The invention belongs to the fields of mechanical and electrical engineering and can be used particularly advantageously in the field of medical engineering. Background Art

[0003] Specifically, the present invention relates to a blood pump for supporting the heart in a human patient. Such a pump is employed to support blood delivery from either the right or left ventricle. The pump may be implanted for this purpose or may be positioned external to the patient, wherein, in either case, at least one cannula extends into a chamber of the heart.

[0004] Such pumps are usually implemented as rotary pumps with a pump rotor that supports a conveying element that transports the blood to be conveyed in a radial or axial direction of the rotor. The advantage of such rotary pumps is that pump parameters, such as (for example) the flow rate or the pressure established by the pump, can be controlled or adjusted by means of the speed of the pump. These parameters can also be easily varied by controlling or adjusting the speed. For example, by varying the speed with the aid of control, the blood flow can be varied so that the pump, the ventricles or other areas of the blood flow are flushed, thereby preventing the formation of blood clots. In addition, by varying the speed, the performance of the pump can be controlled so that the remaining heart function and the pressure established thereby can be used to intentionally open the aortic valve.

[0005] In principle, the measurement of the velocity changes required for these effects is unknown to the individual patient, so that during operation, it cannot be ensured that the desired velocity change results will occur.

[0006] Against the background of the prior art, the underlying objective of the present innovation is to create a blood pump and a method of operating the same, with which speed variations can be used to reliably adjust specific hemodynamic parameters. Another objective is to enable more complex measurements when specific hemodynamic parameters have been obtained. Summary of the Invention

[0007] The present invention therefore relates to a blood pump for supporting the heart, which has a rotor with a conveying element and a rotor drive, and has a pressure sensor or other hemodynamic sensor and a regulating device, which regulates the pressure or hemodynamic parameters by actuating the rotor drive, wherein, in particular, the pressure and / or the hemodynamic parameters are determined by means of one or more hemodynamic sensors and / or as a function of operating parameters of the pump.

[0008] With the help of a pressure sensor, the pressure occurring at different locations through which the blood flows or, for example, in the ventricles, or a pressure curve that changes over time can be directly measured at specific times in the cardiac rhythm. Since the precise pressure curve at different locations through which the blood flows or in the ventricles can be recorded periodically with the help of a pressure sensor combined with a processing device and, in particular, a storage device, other hemodynamic parameters can also be determined from the periodic pressure curve, such as the end-diastolic pressure in the ventricles, the pressure pulsatility, the increase or decrease in pressure dP / dt, or even the maximum value of the pressure increase or decrease. In this way, an estimate of the contractility, for example, can be determined as a ratio (slope) in the curve, where the various measured values ​​of the end-diastolic pressure are compared with the maximum dP / dt of the measured pressure curve. max The end-diastolic pressure (EDP) can be varied by changing the speed of the pump, the changes in EDP can be tracked, and the dP / dt during these changes can be measured. max The slope of this curve is an index of contractility independent of preload or afterload.

[0009] In order to be able to perform such a measurement well, the invention can be implemented so that successively (in particular, alternating periodically) different parameter values ​​can be predetermined or can be predetermined as target values ​​for the regulating device for the pressure or hemodynamic parameter. Thus, in the example given above, successively different end-diastolic pressure values ​​can be set by regulating the speed of the pump, and dP / dt can be determined. max This can also happen periodically.

[0010] The end-diastolic pressure is determined based on a periodic pressure curve in the detection area of ​​the pressure sensor, and the speed of the pump is adjusted during a regulation process so that the end-diastolic pressure is adjusted to successively different target values. This regulation sequence can be repeated periodically. The regulation device in the system also including the blood pump is correspondingly adapted to detect or determine the desired hemodynamic pressure parameter and, if necessary, further adjust the pump speed based on deviations from the target value, thereby adjusting the target value.

[0011] Furthermore, provision may be made for providing a detection device for detecting the pressure change per unit time within the detection area of ​​the pressure sensor and for determining the maximum and / or minimum of said value during the cardiac cycle. The pressure change per unit time can be detected using an operational pressure measurement and by determining the pressure change during a specific time period using a processing device. Thus, the value of dP / dt and its maximum and / or minimum values ​​are detected or determined during the cardiac cycle.

[0012] Furthermore, a processing device can be provided that relates the determined maximum value of the pressure variation to an adjusted target pressure parameter (in particular to an end-diastolic pressure that is adjusted or detected as a target value), and in particular determines a ratio from the determined maximum value of the pressure variation and the adjusted target pressure parameter (end-diastolic filling pressure value). This ratio provides a contractility index that is independent of the degree of support in question and the preload and afterload of the ventricle.

[0013] It can also be provided that the processing device is adapted to determine the slope of a line provided by the linear relationship between the determined maximum value of the pressure change and the adjusted target pressure parameter, in particular the end-diastolic pressure.

[0014] Furthermore, in order to implement the innovation, provision can also be made for the processing device to determine the ratio as a function of the difference between two or more maximum values ​​of the pressure variation and a target pressure parameter associated with these values, in particular the end-diastolic pressure.

[0015] Alternatively or in addition, provision can also be made for an echocardiogram to be provided, which is used for performing echocardiographic measurements and is triggered by or synchronized with a change in the control of the rotor drive.

[0016] The echocardiogram can be positioned and configured so that it examines areas of the patient's body that are in direct contact with the flow of blood through the patient's heart (e.g., the spaces / chambers of the heart through which blood flows, portions of connected blood vessels, areas of the heart valves, and even portions of the blood pump).

[0017] By correlating echocardiography with velocity changes, it is possible to detect hemodynamic parameters such as the end-diastolic diameter and end-diastolic volume of the ventricle, and to determine the correlation between the hemodynamic parameters and the pressure parameters while detecting the pressure curve. It is also possible to calculate the maximum change in pressure per unit time dP / dt based on the end-diastolic volume of the heart. max The relationship between the two factors determines the contractility index of a specific ventricle.

[0018] Another advantage of this innovation can be that the regulating device is configured to regulate the rotor drive to a variable target value during operation, such that at least one predetermined characteristic of the time curve of pressure, flow, motor current, or bearing position is achieved. Thus, the operating mode of the regulating device is not limited to attempting to achieve a certain pressure value when controlling the pump, but rather can require a characteristic of a parameter curve (e.g., achieving a maximum value or a specific value of the slope / first derivative or curve shape) as a target value for regulation. Examples of such parameters are the detected ventricular pressure, the flow rate (flow velocity or volumetric flow rate) of blood through the pump, the motor current, the bearing position of the axial bearing of the pump rotor, or variables derived from the time curves of these parameters. During the course of the cardiac cycle, these parameters also undergo periodic events, such that the parameter curve repeats itself during the cycle of cardiac activity. This enables the regulating device to check in each cycle whether the sought target value has been achieved and, if necessary, readjust the control of the pump motor.

[0019] In doing so, it is also possible to systematically vary the target values ​​predetermined for regulation in order to create changing conditions during the operation of the blood pump in a defined manner. This can be achieved, for example, by verifying the opening of the aortic valve due to the detected signal curve and / or hemodynamic variables or operating parameters of the pump. For example, the opening of the aortic valve can be verified using the pressure curve in the ventricle or using the curve of the motor load during the cardiac cycle.

[0020] For example, the pump motor can be controlled so that the pump power is reduced until the preload is sufficient to allow the pressure to build up due to the maintenance of cardiac activity, thereby causing the aortic valve to open. The explanation for this is that when there is sufficient pump power, blood is regularly pumped out of the ventricle by the pump, so that during intensive pumping, the preload of the ventricle may not be sufficient to generate a pressure within the ventricle sufficient to open the aortic valve.

[0021] It is known from the prior art to achieve opening of the aortic valve by regularly reducing the pump power. However, due to a lack of regulation, the extent of the pump power reduction is not individually adjusted, and it may happen that the pump power is reduced more than necessary, so that although the aortic valve is open, the blood delivery by the pump and thus the perfusion of the end organs is low during this period.

[0022] It can also be provided that the regulating device has a first operating state and a second operating state, wherein the first operating state corresponds to a first operation of the pump and the second operating state is arranged to regulate the rotor drive within a certain time period so that the opening of the aortic valve can be confirmed due to the detected signal curve and / or hemodynamic variables or operating parameters of the pump.

[0023] Provision may also be made for switching means to be provided, which switch between the first operating state and the second operating state according to a predetermined time pattern.

[0024] Typically, in the first operating state, optimal support of the patient's cardiac activity by the blood pump occurs. For example, the first operating state can be designed such that, for example, aortic valve opening does not occur or does not occur reliably and regularly. By switching to the second operating state, it is ensured that the aortic valve actually opens due to the change in preload, wherein this aortic valve opening is confirmed by the curves of hemodynamic variables and / or operating parameters of the pump. Thus, it can be ensured that the aortic valve opens, but the pump activity does not drop more than necessary.

[0025] The information obtained using such velocity changes (contractility index, aortic valve opening) is also suitable for adjusting the cardiac support from the blood pump individually for the patient, for example for withdrawing the support of the cardiac pump from the patient.

[0026] It may also be provided that the hemodynamic parameter regulated by the regulating device is the pulsatility of the pressure difference along the pump or the flow rate through the pump. For this purpose, the maximum and minimum values ​​of the pressure and flow rate are determined, the associated values ​​are measured, and the differences are determined. For this purpose, for example, pressure sensors can be provided at the inlet and outlet of the pump.

[0027] The innovation can also be embodied in that a pressure sensor, in particular an absolute pressure sensor or a flow sensor, is directly connected to the regulating device. Sensors of the above-mentioned type detect variables that are directly related to the blood flow. Thus, hemodynamic parameters can be measured directly and additional hemodynamic parameters can be determined. Independently of this, different sensors or sensor devices can be provided that allow the detection of operating parameters of the pump or the rotor, such as current measuring sensors, voltage sensors, speed sensors and / or sensors that detect the axial pressure of the rotor on the axial bearing. For example, the axial load acting on the bearing can be used to estimate the pressure difference generated by the pump. For example, in the case of magnetic bearings, the pressure acting on the axial bearing can be estimated by monitoring the bearing position. In the case of adjustable magnetic bearings, the bearing current required for the bearing regulation can also be used for this purpose.

[0028] Alternatively, a pressure sensor device may be provided for measuring pressure, comprising two pressure sensors, wherein a first pressure sensor is arranged in or on the pump and a second pressure sensor is arranged in a volume not directly connected to the pump, for example, in the chest cavity outside the patient's heart or connected to the atmosphere outside the patient's body. In this way, the pressure measurement in the ventricle or directly in the pump can be corrected for a variable external pressure (e.g., for a variable atmospheric pressure).

[0029] By taking into account the measured extracardiac pressure within the patient's chest cavity, pressure changes caused by the patient's breathing can be calculated and compensated / eliminated by calculation.

[0030] In addition to a blood pump of the type described above, the innovation also relates to a method for operating such a pump, in particular, providing an adjustment device with the aid of a motor drive for intermittently adjusting the pressure or hemodynamic parameters, wherein, in particular, the pressure and / or hemodynamic parameters are determined with the aid of a pressure sensor device and / or a hemodynamic sensor and / or based on operating parameters of the pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The innovation shall be illustrated using the accompanying drawings and described below.

[0032] Figure 1 is a schematic depiction of a heart pump apparatus having a regulating device;

[0033] Figure 2 is a schematic diagram of the pressure curve during the cardiac cycle;

[0034] Figure 3 Two graphs are provided of the pressure curve within the ventricles of the heart and the time derivative of that variable; and

[0035] Figure 4 is the graph depicting the relationship between dP / dt max Graph of end-diastolic pressure. DETAILED DESCRIPTION

[0036] Figure 1 Schematic depiction of a patient's body 1 and a heart 2 to be supported, as well as a rotary pump 3 arranged on the heart. The pump 3 is connected to the patient's heart 2 by means of an inlet cannula 4 and draws blood from the right ventricle to be delivered to a pump outlet 5 and, via an outlet cannula 6, into the aorta 7. A pressure sensor 8 is also provided, which is connected via a line 9 to a regulating device 10. The regulating device 10 has a storage device 10a and an analysis device 10b for analyzing the hemodynamic pressure curve and for deriving or determining parameters therefrom.

[0037] As an alternative to a single measured pressure or pressure curve, a pressure difference measured by two pressure sensors can also be determined as a measured value, for example, the pressure difference between the pump inlet and the pump outlet or the pressure difference between (on the one hand) a location above the pump or in the ventricle and (on the other hand) a location in the chest cavity outside the patient's heart.

[0038] Thus, during one or more cardiac cycles, a detected pressure curve can be detected and stored in the storage device 10a of the regulating device 10. As will be illustrated more precisely below, different characteristic hemodynamic parameters can be determined based on the pressure curve or based on the curve of another variable detected by the load (such as pump load or pump speed), or based on a combination of these parameters. The regulating device can be operated so that a specific hemodynamic parameter value is achieved. The target value of the hemodynamic parameter to be adjusted can be variable and can be changed over time according to a predetermined rule, for example, or it can be repeated periodically. In this way, the pump can also be operated alternately in two different operating states according to a program.

[0039] Can be used Figure 2 Schematic depiction of the pressure curve in the left ventricle of the heart. Time (in seconds) is plotted on the horizontal axis, while pressure (in mmHg) is plotted on the vertical axis. Observation can be started at time t1 shortly after 11.2 seconds, when the pressure in the left ventricle drops (i.e. the ventricle relaxes). After the active diastolic phase, the ventricular filling phase begins, and the ventricular pressure reaches its absolute minimum, which is highlighted by the first marked circle 11. As the ventricle refills, the ventricular pressure rises slowly until the left ventricle contracts in systole. At the start of the isovolumetric contraction, the pressure rises sharply. The end-diastolic filling pressure, marked by circle 12, is in the transition period between the slow increase in diastole and the rapid increase in systole.

[0040] When the patient's physiological load changes, both the minimum diastolic pressure 11 and the end-diastolic filling pressure 19 change. After one or more cardiac cycles, these two values ​​can be easily determined using the analysis device 10b in the control device based on the detected pressure curve. If the pump speed is varied by the control device, the characteristic values ​​(particularly the end-diastolic filling pressure) are also affected.

[0041] Figure 3 Two graphs are depicted, one above the other, wherein the upper graph depicts the pressure curve 15 of the ventricular pressure during the cardiac cycle between the first end diastole and the second end diastole. The ventricular pressure increases to a maximum and then decreases at the end of systole.

[0042] exist Figure 3 The lower graph of the illustration depicts the time derivative dP / dt of the pressure curve depicted in the top graph over the same time period.

[0043] It is obvious that, first, there are two obvious extremes on the left side of the curve 14, namely, the rate of change dP / dt is at its maximum value (dP / dt max In the area on the falling (pressure drop) side, the minimum value of the rate of change dp / dt is also achieved.min In addition to the time positions of the maximum and minimum pressure changes per unit time, the absolute value dP / dt max and dP / dt min It is also significant.

[0044] One use of this innovation is to intentionally vary the end-diastolic pressure (EDP) between different values ​​by changing the speed of the pump and, during these variations, measure the maximum dP / dt max The results show that for different values ​​of pump speed, the end-diastolic pressure and the diagram associated with it (see Figure 4 ) in the maximum value dP / dt max The slope of the straight line is constant and represents the contractility index independent of preload and afterload.

[0045] exist Figure 4 In the example, end-diastolic filling pressure is plotted on the horizontal axis, while the associated value dP / dt is plotted on the vertical axis. max The various measuring points are arranged on an increasing straight line 13 with good approximation.

[0046] Therefore, the measurement requires adjusting the pump to a specific end-diastolic filling pressure, and then determining dP / dt at that pressure. max If such a measurement point is detected, an adjustment is set to a different target value of the corresponding hemodynamic parameter, in particular, the end-diastolic filling pressure, and further measurement points are detected, and so on.

[0047] Another example of the use of the present invention is the reliable opening of the aortic valve by means of a regulated pump. The opening of the aortic valve is confirmed using specific parameters of the curve of the measured left ventricular pressure or using specific variable operating parameters of the pump (e.g., the difference in pressure and / or throughput within the pump, i.e., the amount delivered per unit time).

[0048] In certain situations, it is important that the aortic valve opens regularly. If the aortic valve does not open, ie, opening cannot be detected using analysis of the detected parameters, the pump is readjusted; for example, the pump speed is reduced until the aortic valve opens.

[0049] The advantage of this approach is that the speed is not reduced until the aortic valve actually opens, thus preventing the blood pump from dropping too much.

[0050] Thus, for example, by using small, automatically adjusted speed changes, contractility and other hemodynamic parameters can also be measured with the present invention when using LVADs (left ventricular assist devices) and RVADs (right ventricular assist devices). This reduces the risk to the patient and allows for more frequent control of contractility. In addition, recovery of the supported heart can be quickly determined in this way, increasing the likelihood of withdrawing cardiac support.

[0051] If the present invention is used to achieve regular and reliable opening of the aortic valve, this can help prevent aortic valve insufficiency in LVAD patients. In addition, because deceleration is minimized, it can prevent the patient's body from being short-term short-term blood supply shortage.

[0052] If pulsatility is selected as the control parameter, the natural pulsation of the heart can also be reproduced by the invention by means of pump control. The adjusted pulsation can also be modified periodically.

Claims

1. A blood pump (3) for supporting a heart, comprising a rotor with a conveying element and a rotor drive, a hemodynamic sensor (8), and a regulating device (10) for regulating hemodynamic parameters by controlling the rotor drive, wherein: The regulating device is adapted to cyclically regulate successively a further specific hemodynamic parameter to different target values, wherein the hemodynamic parameter regulated by the regulating device is the pulsatility of the flow rate through the pump, and wherein the regulating device (10) is arranged to regulate the target value to a varying target value during operation of the rotor drive so as to obtain at least one predetermined characteristic of the time curve of the flow.

2. The blood pump according to claim 1, wherein The regulating device (10) is arranged to regulate alternations periodically during operation of the rotor drive, so that the opening of the aortic valve can be confirmed based on detected signal curves and / or hemodynamic variables or operating parameters of the pump (3).

3. The blood pump according to claim 1 or 2, wherein: The regulating device (10) has a first operating state and a second operating state, the first operating state corresponding to a first operation of the pump (3), the second operating state being configured to regulate the rotor drive over a certain period of time so as to confirm the opening of the aortic valve based on the detected signal curve and / or hemodynamic variables or operating parameters of the pump (3).

4. The blood pump according to claim 3, wherein: Switching means are provided for switching between the first operating state and the second operating state according to a predetermined time pattern.

5. The blood pump according to claim 1, wherein The regulating device is configured to detect the pulsatility of a throughflow rate through the pump, the pump being provided for determining maximum and minimum values ​​of the throughflow rate.

6. The blood pump according to claim 1, characterized in that The regulating device is implemented such that the hemodynamic parameter is determined by means of one or more hemodynamic sensors and / or as a function of operating parameters of the pump (3).

7. The blood pump according to claim 1, wherein: The flow sensor is directly connected to the regulating device (10).

8. The blood pump according to claim 1, further comprising a pressure sensor.

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