Controllers and methods for artificial hearts

Abstract

This invention relates to a controller unit (100) and method for controlling a cardiac prosthesis (200). The prosthesis includes: at least one pump section (202, 203, 602, 702); an inlet (210, 610, 710) connected to said at least one pump section; an outlet (213, 613, 713) connected to said at least one pump section; a pressure sensor (231; 232) configured to measure the pressure of fluid flowing from the inlet to the outlet; and a pump actuator (221, 222) configured to induce the flow of fluid. The controller unit further includes a memory and a processing unit, wherein the controller unit is configured to: obtain a pressure value from the pressure sensor; obtain a desired pressure value of the fluid flowing into the pump; calculate an error signal equal to the difference between the desired pressure value and the measured pressure; and control the output of the pump by controlling the pump stroke rate and / or the pump stroke volume such that the measured pressure is close to or equal to the desired pressure.

Description

Technical Field

[0001] Generally, the present invention relates to control methods and devices for artificial hearts, and more particularly to the response of artificial heart systems to changing physiological needs, and includes mechanisms for regulating the imbalance of actual flow between pulmonary and systemic circulation. Background Technology

[0002] Despite steady progress in developing permanent artificial hearts for long-term transplantation to replace failing natural hearts in patients, several issues remain to be addressed. These include control strategies to address varying physiological needs in tethered artificial heart systems, and mechanisms to regulate flow imbalances between pulmonary and systemic circulation.

[0003] The difference in cardiac output between the left and right sides is well documented. Physiologically, the left side of the heart pumps a greater volume of blood than the right side. This difference is primarily attributed to a circulatory pathway known as bronchial shunt. This flow originates in the left arterial system, passes through the bronchial tissue, and then returns directly to the left atrium. This difference, where left-side flow is always greater than right-side flow, typically appears to be as high as about ten percent of cardiac output. Artificial heart systems must account for this inherent physiological circulatory imbalance. Furthermore, sources of flow imbalance can be created. For example, a flow imbalance can be introduced by the regurgitation difference between artificial valves placed on the left and right sides. Artificial heart systems must also account for these types of circulatory imbalances.

[0004] The same applicant disclosed a blood pumping device in WO 2016 / 020219, comprising at least a first pump and a second pump, and disclosing left and right pump actuation devices for inducing blood flow in the body's circulatory system. Each pump includes an upper chamber with an inlet passage and a lower chamber with an outlet passage. The upper and lower chambers are separated by a movable valve plane provided with a valve. The pump actuation device is configured to apply movement to the valve plane in an upward and downward direction between the upper and lower chambers in response to a control signal from a control unit, such that when the valve plane moves in the upward direction, the valves provided on the valve plane are in an open position, allowing blood to flow from the upper chamber to the lower chamber, and when the valve plane moves in the downward direction, the valves are in a closed position, and blood is discharged from the lower chamber through the outlet passage. A pouch-like portion is provided at the bottom of the lower chamber.

[0005] Figure 1A cross-sectional schematic diagram of a blood pumping device 1, as disclosed in WO 2016 / 020219, is shown, which has four chambers. The four-chamber blood pumping device 1 includes two pumps, a first pump 2 and a second pump 3, and first and second pump actuators for inducing blood flow in the body's circulatory system. The first pump 2 and the second pump 3 are structurally identical. Each pump includes an upper chamber 9 and a lower chamber 12. The upper chamber 9 has an inlet passage (not shown) that allows blood to enter the upper chamber 9. The upper chamber corresponds to the atrium of a natural heart. The lower chamber 12 is provided with an outlet passage (not shown) that allows blood to leave the lower chamber 12. The lower chamber 12 corresponds to the ventricle of a natural heart. The upper chamber 9 and the lower chamber 12 are separated using a movable valve plane 7. The valve plane corresponds to the atrioventricular (AV) plane (i.e., the plane of fibrous tissue) between the atria and ventricles of a natural heart. Valve 14 is arranged in valve plane 7, corresponding to either the tricuspid or mitral valve, depending on whether it is located in a pump that functions in the pulmonary circuit or the aortic circuit. The bottom of the lower chamber 12 is advantageously designed to have a shape similar to the anatomical shape of the central ventricle in a natural heart. In the four-chamber blood pumping device 1, the bottom of the lower chamber 12 has a pouch-like shape, which is designed to mimic the internal shape of the central ventricle in a natural heart. Blood flow (arrow) from the upper chamber 9 through valve 14 into the lower chamber 12 impacts a stopping surface at the bottom of the pouch-like shape and stops abruptly, at which the blood flow abruptly changes direction and continues along the outlet passage (not shown). The curvature inside the pouch-like portion at the bottom of the lower chamber 12 forms a curvature of approximately 90°–340°, more preferably between 100°–300°, more preferably between 105°–200°, and most preferably between 110°–150°, which is similar to the curvature within the ventricles of a natural heart. Subsequently, blood continues to flow into the outlet channel. The cross-section of the pouch-like portion at the bottom of the lower chamber 12 advantageously has a triangular shape to allow blood to flow optimally from the lower chamber 12 into the outlet channel. As in a natural heart, the triangular cross-section facilitates the formation of a flow channel within the lumen of the lower chamber 12, allowing blood to reach the stopping surface of the pouch-like portion from different angles, stop, change direction, enter the outlet channel, and subsequently exit the blood pumping device through the outlet valve. Alternatively, the cross-section of the internal structure of the lower chamber 12 may have an elliptical or circular cross-section. The inner wall at the bottom of the lower chamber 12 and the outlet channel are advantageously provided with rough surfaces to mimic trabeculae, i.e., muscular ridges that intersect and protrude from the inner wall of the ventricles of a natural heart. These rough surfaces are lined with ridges and protrusions that protrude from the surface of the lower chamber 12 by approximately 0.01 mm to 3 mm, preferably at least 0.5 mm to 2 mm. The outlet channel and bottom of the lower chamber 12 may also have smooth surfaces. The outlet channel from the lower chamber 12 may also have a continuously decreasing diameter, similar to the design of the outlet of the ventricle in a natural heart.

[0006] WO 2017 / 137486, filed by the same applicant, relates to a blood pump housing device designed to enclose and protect a total artificial heart (TAH) upon implantation in a subject. The blood pump housing device includes a first and a second artificial heart pump receiving portion configured to receive and partially enclose the first and second artificial heart pumps of the TAH, and a first and actuation enclosed portion configured to partially accommodate the first and second pump actuators. The artificial heart pump receiving portion and the pump actuator enclosed portion are arranged to be connected to each other in a leak-free manner. Summary of the Invention

[0007] A control device and method are needed to automatically control the heart rate and stroke volume of at least each blood pump device, particularly the aforementioned pump devices.

[0008] The present invention also provides an artificial heart system that responds to changing physiological needs and includes a mechanism for regulating the actual flow imbalance between pulmonary and systemic circulation.

[0009] For these reasons, a method for controlling a cardiac prosthesis is provided. The cardiac prosthesis includes: at least one pump unit; an inlet connected to the at least one pump unit; an outlet connected to the at least one pump unit; a pressure sensor configured to measure the pressure of fluid flowing from the inlet to the outlet; a pump actuator configured to induce fluid flow; and a controller unit. The method includes the steps of: obtaining a pressure value from the pressure sensor; obtaining a desired pressure value of the fluid flowing into the pump; calculating an error signal equal to the error signal of the difference between the desired pressure value and the measured pressure; and controlling the pump output by controlling the pump actuator to control the pump stroke rate and / or pump stroke volume, such that the measured pressure is close to or equal to the desired pressure. In one embodiment, the fluid is blood. The output may be cardiac output. According to one embodiment, the pump includes a chamber corresponding to one of the right or left atrium.

[0010] In one embodiment, the cardiac prosthesis may include two similar pumps. These two pumps are connected to the systemic circulation and the pulmonary circulation, respectively, and are independently controlled by setting a limit on the cardiac output of the pump connected to the pulmonary circulation. Therefore, the method further includes the steps of: obtaining the cardiac output of the pump connected to the systemic circulation; given the cardiac output of the pump connected to the systemic circulation, setting a limit on the cardiac output of the pump connected to the pulmonary circulation, wherein the limit is updated as the cardiac output of the pump connected to the systemic circulation changes; and providing a control signal to the pump actuator.

[0011] In one embodiment, two pumps are connected to the systemic and pulmonary circulations, respectively, with desired cardiac output, and the stroke volume and stroke rate of the two pumps are obtained. The method includes the following steps: obtaining the desired cardiac output of either pump; using the desired cardiac output of both pumps, finding the stroke rate; given the obtained stroke rate, obtaining the stroke volume of either pump such that the product of the stroke rate and the stroke volume equals each desired cardiac output; and providing a control signal to the pump actuator.

[0012] In one embodiment, a pressure sensor is arranged in communication with the chamber. In an alternative embodiment, pressure is measured at a location between the opening of the inlet and the end of the chamber forming the atrium. One embodiment includes measuring the pressure within the thoracic cavity as a reference pressure.

[0013] In one embodiment, the controller unit is configured to detect whether atrial pressure decreases or intrathoracic pressure increases, i.e., an aspiration event, and to take action to prevent low atrial pressure or increased intrathoracic pressure. Therefore, the controller unit compares the averaged atrial pressure received from a pressure sensor during one stroke with a desired atrial pressure, and detects an aspiration event when the average atrial pressure drops significantly below the desired pressure. In a further step, the atrial pressure is averaged during the cycle to reduce noise and prevent false detection of aspiration events, and once the control unit detects an aspiration event, an inactivity period is set during which no aspiration events are detected. The method also includes, once an aspiration event is detected, performing a gradual increase in the desired atrial pressure to prevent further aspiration events and generating an alarm.

[0014] The present invention also relates to a controller unit for controlling a cardiac prosthesis. The prosthesis includes: at least one pump section; an inlet connected to the at least one pump section; an outlet connected to the at least one pump section; a pressure sensor configured to measure the pressure of fluid flowing from the inlet to the outlet; a pump actuator configured to induce fluid flow; a memory; and a processing unit. The controller unit is configured to obtain pressure values ​​from the pressure sensor.

[0015] The desired pressure of the fluid flowing into the pump is obtained, an error signal is calculated, which is equal to the difference between the desired pressure and the measured pressure, and the pump output is controlled by controlling the pump stroke rate and / or pump stroke volume, so that the measured pressure is close to or equal to the desired pressure. In an alternative embodiment, the controller unit includes the following functional blocks:

[0016] The flow control function block is configured to determine the corrected flow limit and the desired atrial pressure as inputs to maintain cardiac output within a certain range; the cardiac output determination function block determines the cardiac output of any pump to control the atrial pressure and determine the heart rate: wherein the heart rate and cardiac output of any pump provide the stroke volume of any pump.

[0017] In one embodiment, the cardiac prosthesis includes a first pump and a second pump, and the controller unit is configured to maintain a sufficiently low flow rate of the first pump such that the second pump does not reach its maximum flow rate. In an alternative embodiment, the cardiac prosthesis includes two similar pumps connected to the systemic circulation and the pulmonary circulation, respectively, and these two pumps are independently controlled by setting a limit on the cardiac output of the pump connected to the pulmonary circulation. The controller unit is further configured to: acquire the cardiac output of the pump connected to the systemic circulation; give a cardiac output of the pump connected to the systemic circulation; set a limit on the cardiac output of the pump connected to the pulmonary circulation, wherein the limit is updated as the cardiac output of the pump connected to the systemic circulation changes; and provide a control signal to the pump actuator.

[0018] In one embodiment, the cardiac prosthesis includes two similar pumps connected to the systemic and pulmonary circulations, respectively, with a desired cardiac output. The stroke volume and stroke rate of the two pumps are obtained. The controller unit is further configured to obtain the desired cardiac output of either pump.

[0019] The stroke rate is calculated using the desired cardiac output of the two pumps; given the obtained stroke rate, the stroke volume of either pump is obtained such that the product of the stroke rate and the stroke volume equals each desired cardiac output; and a control signal is provided to the pump actuator.

[0020] According to one embodiment, the controller unit includes a signal receiver for receiving signals and detecting whether atrial pressure has decreased or thoracic pressure has increased, i.e., an aspiration event, and performing actions to prevent low atrial pressure or increased thoracic pressure. In one embodiment, the processing unit of the controller unit is configured to compare atrial pressure received from a pressure sensor and averaged over a stroke with a desired atrial pressure, and to detect an aspiration event when the average atrial pressure drops significantly below the desired pressure. In another embodiment, the processing unit of the controller unit is configured to average atrial pressure over a stroke to reduce noise and prevent false detection of aspiration events, and to set an inactive period during which aspiration events are not detected once the control unit detects an aspiration event. In one embodiment, once an aspiration event is detected, the controller unit is configured to progressively increase the desired atrial pressure to prevent further aspiration events and generate an alarm.

[0021] The present invention also relates to a cardiac prosthesis comprising a controller unit as described above.

[0022] The present invention also relates to a pressure sensor for use in a cardiac prosthesis. The prosthesis includes: a housing having a superstructure and a body, an inlet, an outlet, and a chamber located between the inlet and the outlet. The pressure sensor includes: a flexible membrane covering an opening in the superstructure or body, a pressure-transmitting medium, a conduit containing the pressure-transmitting medium, and a pressure-sensitive sensor.

[0023] The present invention also relates to cardiac prostheses that include such pressure sensors. Attached Figure Description

[0024] Referring to the accompanying drawings, elements with the same reference numerals may represent similar elements herein.

[0025] Figure 1 This is a view of a four-chamber blood pump device based on existing technology;

[0026] Figure 2 This is a schematic diagram of the control device according to the present invention connected to a blood pumping device;

[0027] Figure 3 This is a functional block diagram of the control unit according to the present invention;

[0028] Figure 4a and Figure 4b This is a schematic diagram of a PID controller according to one aspect of the present invention;

[0029] Figure 5 This is an exemplary ratio diagram between heart rate and blood flow;

[0030] Figure 6 This is a perspective view of an artificial heart according to one embodiment;

[0031] Figure 7a This is a cross-sectional view of the pump of an artificial heart according to an embodiment of the present invention, and Figure 7b yes Figure 7a Enlarged view of the circled area;

[0032] Figure 8 This is a schematic diagram of the control unit according to the present invention;

[0033] Figure 9 A perspective view of an embodiment of a pump that forms part of a heart prosthesis is shown;

[0034] Figure 10 It shows Figure 9 A cross-sectional view of the pump; and

[0035] Figure 11 This is a schematic diagram of the cross-section of the chest and thoracic cavity. Detailed Implementation

[0036] The following detailed description refers to the accompanying drawings. The same reference numerals in different drawings may identify the same or similar elements.

[0037] The term artificial heart used in this article refers to a pumping device that can be attached to a subject.

[0038] As used herein, the term “stroke volume” refers to a specific amount of fluid discharged within a specific time interval, and the term “heart rate” as used herein refers to the rate at which a pump discharges a certain amount of fluid.

[0039] As used herein, the terms “right atrium” or “left atrium” refer to a compartment within the pump housing into which fluid is supplied and discharged.

[0040] The following describes control devices and methods for setting the heart rate and stroke volume of an artificial heart in any half, particularly those described in WO 2016 / 020219 or WO 2017 / 137486. However, it should be understood that the devices and methods according to the invention can be applied to any pumping device having a fluid-passing chamber. With necessary modifications, the controllers and methods described herein can also be used for cardiac assist pumps.

[0041] Figure 2 A schematic control unit 100 and a blood pump device 200 according to an exemplary embodiment of the present invention are shown. The blood pump 200 includes a first pump 202 and a second pump 203, and a first pump actuator 221 and a second pump actuator 222 for inducing blood flow. Each pump includes an upper chamber 209 having an inlet passage 210 and a lower chamber 212 having an outlet passage 213. The upper and lower chambers are separated by a movable valve plane 207 provided with a valve 214. Each pump actuator 221, 222 is configured to apply movement to the valve plane 207 in an upward and downward direction between the upper and lower chambers in response to a control signal from the control unit 100, such that when the valve plane 207 moves in the upward direction, the valve 214 is in an open position, allowing blood in the upper chamber 209 to flow from the inlet 210 into the lower chamber 212, and when the valve plane moves in the downward direction, the valve is in a closed position, and blood is discharged from the lower chamber 212 through the outlet passage 213. Preferably, the bottom of the lower chamber 212 is provided with a bag-shaped portion (not shown, but...). Figure 1 (Illustrated schematically).

[0042] Actuators 221 and 222 may include a magnetic or electromagnetic motor or any other suitable drive system that can receive signals and drive or displace the pumping section directly or in conjunction with a gearbox (not shown).

[0043] The blood pump system includes pressure sensors 231 and 232. The sensors and their functions are described in more detail below. The pressure sensors are configured to measure the average atrial pressure during each heartbeat. This averaging helps reduce any noise in the measurement signal.

[0044] During respiration, the pressure within the thoracic cavity constantly changes. Since the pressure within the thoracic cavity affects the pressure within the atria (209), it is desirable to also measure the pressure within the thoracic cavity (reference pressure). This allows for compensation for changes in the pressure within the thoracic cavity. The pressure within the thoracic cavity can be measured in the following ways:

[0045] 1. Use a pressure sensor mounted inside the pump but designed to measure pressure within the thoracic cavity.

[0046] 2. Use a separate pressure sensor placed inside the chest cavity and connected to the pump via a wire, or

[0047] 3. Place the pressure sensor outside the chest cavity, but inside the chest wall and just behind the pleura (the innermost layer in the chest wall).

[0048] Therefore, the pressure sensor can be connected to the pleura, which will act as a natural, flexible membrane between the pleural cavity and the pressure sensor. For both right and left pumps, using a single pressure sensor to measure intrathoracic pressure is sufficient to eliminate any influence from breathing, and the measurement is taken outside the heart itself. This is in... Figure 11 It is displayed in the middle.

[0049] Figure 11 This is a schematic diagram of a cross-section of the human chest and thoracic cavity.

[0050] Reference numerals 501 represent the ribs, 502 the skin, 503 the superficial fascia, 504 the intercostal muscles, 505 the parietal pleura, 506 the pleural cavity, 507 the visceral pleura, and 508 the lungs.

[0051] In this application, pressure sensor 510 is arranged between a plurality of ribs 501 and in contact with parietal pleura 505 to measure pressure in pleural cavity 506. Electrical connections extending outward through tissue are not shown. Pressure sensor may also be arranged near costal cartilage. Pressure sensor 510 functions in a similar manner to the pressure sensor described, but the electronics, sensor element, flexible diaphragm, and pressure transmission medium are arranged in a housing.

[0052] The control unit 100 has input signals from pressure sensors 231 and 232 and output signals to pump actuators 221 and 222. Signals can be received and supplied directly or via an interface, wirelessly or via wired connection. A power supply 110 can be connected to or integrated into the control unit 100.

[0053] Figure 3 A schematic diagram and functional blocks of an exemplary control unit 100 are illustrated. According to this embodiment, the control unit 100 may include the following functional blocks:

[0054] - Right atrial cardiac output control 101

[0055] - Left atrial cardiac output controlled at 102.

[0056] - Flow control block 103, and

[0057] - Process block 104.

[0058] The main function of the control unit 100 is to set the heart rate and stroke volume of either half of the blood pump 200 (i.e., the left pump and the right pump) to values ​​suitable for the subject's current physiological state.

[0059] The control problem can be solved by breaking it down into a complex number of subproblems, including:

[0060] - Flow control: It determines the corrected flow limit and the desired atrial pressure, which will serve as input to maintain cardiac output within the appropriate range. It allows the prosthesis operator to manually set the desired atrial pressure, thus enabling control over the desired atrial pressure.

[0061] - Determine the cardiac output of any pump to control atrial pressure: This is done independently, with no interdependence between the pumps.

[0062] - Determine the heart rate: The heart rate and cardiac output of either pump (calculated in the previous step) will in turn provide the stroke volume for either pump.

[0063] The inputs to a function block include:

[0064] -Right atrial pressure (RAP), measured by pressure sensor 231 in the right atrium and sent to (right) ventricular output control 101; and

[0065] -Left Atrium Pressure (LAP) is measured by pressure sensor 232 in the left atrium and sent to (left) ventricular output control 102.

[0066] The cardiac output of any pump can be determined using only atrial pressure as input.

[0067] As mentioned above, the stroke volume can be calculated as the stroke length multiplied by a constant, and therefore may not match the actual stroke volume pumped. This means that the reported flow rate is also only an approximation.

[0068] Function block flow control 103 determines the flow limit and desired atrial pressure. The flow limit is the boundary of the right pump's cardiac output.

[0069] The purpose of flow control is to keep the flow rate of the right pump 202 low enough so that the left pump 203 never reaches its maximum flow rate. If this happens, i.e., the maximum flow rate is reached, the left pump cannot maintain the left atrial pressure (LAP) within limits, which carries the risk of pulmonary edema. Limiting the capacity of the right pump may result in an increase in right atrial pressure (RAP); however, this can be considered acceptable. Higher right atrial pressure (RAP) also increases central venous pressure (CVP), which helps reduce venous return. Flow control block 103 receives output from left ventricular output control 102 and sets the limits for desired right atrial pressure (Desired RAP), desired left atrial pressure (Desired LAP), and right ventricular output.

[0070] Even given the same heart rate and stroke length, the actual flow rate of either half of the pump (i.e., 202 and 203) may depend on various factors, such as outflow and inflow pressures. For this reason, the flow limit of the right pump (202) cannot be set to a constant but needs to be dynamically changed.

[0071] The following parameters can be considered:

[0072] Flow status: Flow status is a variable determined by the flow rate of the left pump 203. Table 1 shows some example values ​​for different flow statuses and the left pump flow rate (in liters per minute):

[0073] Traffic Status Left pump flow rate (liters / minute) extreme ＞6.3 high 6-6.3 normal 5-6 Low ＜4

[0074] Table 1

[0075] Flow Limit: The flow limit is the maximum permissible core output of the right pump. The following rules may apply:

[0076] - When transitioning from a low-flow or normal-flow state to a high-flow or extreme state (see Table 1), the flow limit can be set to be equal to the current right ventricular output. This is the only state transition that directly causes a change in the flow limit.

[0077] - The flow limit is constant when the flow is high.

[0078] - Under extreme flow conditions, the flow limit will decrease at a constant rate, but will not be set below half of the maximum heart output.

[0079] - When in low flow or normal flow conditions: The flow limit increases at a constant rate if and only if the output of the right pump is limited by the flow limit.

[0080] - The rate at which traffic limits are reduced may be faster than the rate at which they are increased.

[0081] - The limit must not be set higher than the maximum cardiac output.

[0082] - The limit should not be less than half of the maximum cardiac output.

[0083] Desired atrial pressure: Under low flow conditions, the desired atrial pressure can be reduced to help improve venous return.

[0084] During low-flow conditions, the desired atrial pressure can be determined by the left flow rate and can be set according to Table 2, which shows exemplary values ​​for the desired left atrial pressure and desired right atrial pressure (in millimeters of mercury) relative to the left flow rate (liters / minute):

[0085]

[0086] Table 2

[0087] An alert can be generated if low or extreme traffic conditions are detected.

[0088] Therefore, the flow control block 103 receives the output from the left atrial output control 102 and sets the desired right atrial pressure (RAP), desired left atrial pressure (LAP), and limits for right atrial output.

[0089] The right-side pump cardiac output control 101 receives the right atrial pressure (RAP), the desired right atrial pressure (RAP), and a limit on the right-side cardiac output, and outputs the cardiac output of the right-side pump. The left-side pump cardiac output control 101 receives the left atrial pressure (LAP) and the desired left atrial pressure (LAP), and outputs the cardiac output of the left-side pump. This will be described further below.

[0090] Processing block 104 uses the right heart output level and the left heart output level to generate the corrected stroke volume, heart rate and left stroke volume provided by the controller to the pump actuator.

[0091] In one embodiment, cardiac output is controlled by a proportional-integral-derivative (PID) controller, which controls the derivative of cardiac output to keep the actual atrial pressure close to (preferably equal to) the desired atrial pressure. This is in Figure 4a It is shown schematically in the diagram.

[0092] Figure 4bThis is a simplified diagram of a PID controller, where it is assumed that the derivative and integral cancel each other out. This eliminates the need for numerical derivations that may introduce noise. The PID controller continuously calculates the error value e(t) as the difference between the desired setpoint (SP) and the measured process variable (PV), and corrects for it based on the proportional (P), integral (I), and derivative (D) values. Thus, SP is the desired atrial pressure, and PV is the cardiac output.

[0093] The measured atrial pressure is subtracted from the expected atrial pressure to produce the error value e(t). The calculated error signal e(t) is truncated before being fed to the PID controller. This prevents the controller from "overreacting" if there is a large difference between the expected and actual atrial pressures, which could occur briefly. The error is simply multiplied by the P, I, and D actions. The resulting "error control actions" are then summed, integrated, and output as the (left or right) cardiac output.

[0094] In one embodiment, two pumps 202 and 203 may be connected to the systemic circulation and the pulmonary circulation, respectively. Both can be independently controlled by setting a limit on the cardiac output of the pump connected to the pulmonary circulation. Thus, given the cardiac output of the pump connected to the systemic circulation, an appropriate limit on the cardiac output of the pump connected to the pulmonary circulation is obtained, and the limit is updated as the cardiac output of the pump connected to the systemic circulation changes.

[0095] In another embodiment, two pumps may be connected to the systemic and pulmonary circulations, respectively, each with a desired cardiac output. Appropriate stroke volumes and stroke rates for both pumps are obtained; the desired cardiac output for either pump is obtained; using the desired cardiac outputs of both pumps, an appropriate stroke rate is found, and given the obtained stroke rate, a suitable stroke volume is obtained for either pump such that the product of the stroke rate and either stroke volume equals either desired cardiac output.

[0096] The heart rate function integrated in function block 104 uses two inputs: left ventricular output Q. left And right heart output Q right It outputs heart rate (HR) and left stroke volume (SV). left and right stroke volume SV right The following system of equations needs to be solved:

[0097] Q left =HR*SV left

[0098] Q right =HR*SV right

[0099] The heart rate process is limited by several factors:

[0100] Maximum heart rate,

[0101] Minimum heart rate,

[0102] Maximum stroke volume,

[0103] Minimum stroke volume,

[0104] This means that there are maximum and minimum cardiac outputs.

[0105] When the flow rate (Q) left and Q right When the flow rate is very low, the stroke volume should also be very low. Only when the flow rate is high should the stroke volume be set close to the maximum value.

[0106] Figure 5 The graph showing heart rate (beats / minute) and blood flow (liters / minute) can be interpreted as: finding a blood flow equal to Q at the same altitude (same heart rate). left and Q right The two points.

[0107] To simplify the terminology, Q big It is Q left and Q right The maximum value of Q, and Q small It is the minimum value.

[0108] You can use the function f, such as Figure 5 As shown, this is a reasonable heart rate to achieve Q. The function f is given only as an example, and other functions can be used. Figure 5 The curve f(Q) in the figure may remain high even when relatively far to the left. This means that during periods of low flow (which may occur when the patient has a small blood volume due to, for example, dehydration or bleeding), the heart rate remains relatively high and the stroke volume remains low, which constitutes a type of tachycardia.

[0109] Heart rate (HR) will be:

[0110] HR=f(Q small )

[0111] Assignment:

[0112] SV small =Q small / HR

[0113] SV big =Q big / HR

[0114] Unless this requires SV big >SV maxIn this case, set the heart rate based on the maximum flow rate:

[0115] HR = Q big / SV max

[0116] The aforementioned values, heart rate, and stroke volume are truncated to maintain them within their limits.

[0117] The controller unit 100 converts the HR and SV values ​​into control signals and provides them directly or indirectly to the actuators 221 and 222.

[0118] The controller unit 100 may be an implanted or integrated microcomputer or electronic chip. The microcomputer can provide control signals to the pump actuator to change its pumping behavior. If, for some reason, the microcomputer does not receive any input information, the pump actuator can continue at a constant level of behavior.

[0119] In some cases, atrial pressure may become too low, or chest pressure may become too high (e.g., due to assisted ventilation or other reasons). In such situations, the atria and / or connected veins may collapse. This can completely or partially obstruct blood flow to the pump (this can occur on either pump alone). This is known as an aspiration event.

[0120] The controller unit of this invention can detect these events and take measures to prevent them.

[0121] The control unit detects aspiration events by comparing the averaged atrial pressure received from the pressure sensor during one stroke with the expected atrial pressure. Aspiration events are detected if the average atrial pressure drops significantly below the expected pressure (by a certain margin, possibly on the order of tens of millimeters of mercury).

[0122] Atrial pressure is averaged over a period of time (e.g., approximately half a second to one second) to reduce noise and prevent false detections (detecting aspiration when it is not present). Once the control unit detects an aspiration event, an inactivity period (in seconds) is set during which no aspiration event will be detected. This is to avoid detecting the same aspiration event multiple times.

[0123] The specific values ​​for the atrial pressure detection margin and the duration of the inactivity period can be set to different values. The detection margin is on the order of tens of millimeters of mercury (mmHg), and the inactivity period is approximately a few seconds.

[0124] Once an aspiration event is detected, the desired atrial pressure can be gradually increased (on the order of one or a few millimeters of mercury) to prevent further aspiration events. The increase in desired atrial pressure can be appropriately selected.

[0125] Once a suction event is detected, it can be reported to the device's user interface.

[0126] Figure 6 One embodiment of the pump 602 of an artificial heart (prosthesis) according to an embodiment of the present invention is shown, comprising a cylindrical housing 660, an upper chamber 609 within the housing, an inlet channel 610, an outlet channel 613, a pump actuator housing 661, a pressure sensor housing 662, a pressure transmission medium conduit 663, and a sensor cover 664.

[0127] Figure 7a This is a schematic diagram of the cross-section of the replacement pump 702. Figure 7b This is an enlarged view of the enclosure including sensor 732.

[0128] The sensor structure 732 includes an opening, namely a reservoir 738 within the wall of the upper chamber 709, a flexible film 733, a conduit 763, an electrical sensor 734, a circuit board 735, a pressure transmission medium 736, and an attachment device 737.

[0129] The pressure sensor 734 may include a small microelectromechanical system (MEMS) sensor arranged on a circuit board 735 (PCB) along with corresponding electronics. The conduit 763 may include a metal cylinder or the like and is attached to the electronic circuitry from one side in a manner that directly connects the conduit's inner lumen 7631 and communicates with the MEMS sensor 734. As previously described, the pressure sensor's pressure receiving portion is arranged in the left atrium 709 and the right pump atrium (or the upper half of each pump). The inner lumen 7631 of the conduit 763 is connected directly or via another cylindrical structure (assembly tube) to the flexible diaphragm 733 of the atrial wall 709 of each pump to extend the length of the lumen, enabling and satisfying assembly of the pump with the pressure sensor. The flexible diaphragm 733 is arranged as part of the inner wall of the housing and as part of a reservoir 738 containing the pressure transmission medium 736. The wall of the assembly tube may be made of rigid plastic or metal. The connection between the lumen of the catheter or assembly tube 763 and the membrane 733 of the atrial wall is sealed in a leak-free manner, for example, using adhesives or sealing gaskets. The catheter 763 and reservoir 738 may be filled with a biocompatible, implantable oil, such as medical graded silicone oil, as the pressure transmission medium 763. The reservoir 738 may be part of the catheter 763, having the same dimensions or slightly different. Devices may be mounted on the lumen of the metal catheter or assembly tube to facilitate oil filling, and other devices may be connected to the lumen of the metal cylindrical lumen or assembly tube to facilitate air venting during lumen filling with the pressure transmission medium.

[0130] During operation, when the membrane 733 of the atrial wall 760 is affected by the pressure of blood within the atrium 709 of each pump, the flexible membrane 733 either bulges when the pressure within the atrium increases, or bends inward into the atrial cavity when the pressure decreases. Thus, the pressure transmission medium within the lumen of the reservoir and catheter 763 is compressed or expanded due to the pressure within the atrium 709. Pressure is transmitted from the membrane to the surface of the sensor 734 within the catheter 763. Therefore, the sensitive surface of the MEMS sensor 734 is affected by pressure changes in the pressure transmission medium, and the MEMS sensor converts the pressure into a digital value and generates an electrical signal representing the pressure, which is then provided to the controller unit 100.

[0131] According to this exemplary embodiment, the sensor assembly is constructed to utilize space and employ available space within the pump housing. Therefore, the sensor structure described above is one example of a sensor, and other sensors can also be used in the pump; for example, the entire sensor can be arranged within the atrial wall. Pressure measurement can also be performed between the inlet opening and the end of the chamber forming the atrium.

[0132] Many of the prior examples relate to pulsating pumps or positive displacement pumps; however, the methods and control units of the present invention are equally applicable to systems with different types of pumps (e.g., centrifugal pumps). Centrifugal pumps may include one or more of the following types: canning pumps, radial pumps, side-channel pumps, regenerative turbine pumps, axial pumps, and diagonal pumps. Positive displacement pumps may include one or more of the following types: metering pumps, screw pumps, gear pumps, multi-screw pumps, piston diaphragm pumps, plunger and piston pumps, rotary cam pumps, vacuum pumps, and hose pumps.

[0133] Figure 8 This is an illustration of an exemplary controller unit 100 in which the methods described herein can be implemented. The controller unit 100 may include a bus 110, a processor 120, a memory 130, a read-only memory (ROM) 140, a storage device 150, an input device 160, an output device 170, and a communication interface 180. The bus 110 allows communication between components of the controller unit 100. The controller unit 100 may also include one or more power supplies (not shown). Those skilled in the art will recognize that the controller unit 100 can be configured in a variety of other ways and may include other or different elements.

[0134] Processor 120 may include any type of processor or microprocessor that interprets and executes instructions. Processor 120 may also include logic capable of decoding media files and generating output to, for example, a speaker, display, etc. Memory 130 may include random access memory (RAM) or other dynamic storage devices that store information and instructions executed by processor 120. Memory 130 may also be used to store temporary variables or other intermediate information during the execution of instructions by processor 120.

[0135] ROM 140 may include a conventional ROM device and / or another static storage device that stores static information and instructions of processor 120. Storage device 150 may include a disk, solid-state drive, or optical disk and its corresponding drive, and / or some other type of recording medium and its corresponding drive for storing information and instructions. Storage device 150 may also include a flash memory (e.g., electrically erasable programmable read-only memory (EEPROM)) device for storing information and instructions.

[0136] Input device 160 may include one or more conventional mechanisms that allow users to input information into controller unit 100, such as a keyboard, keypad, arrow keys, mouse, pen, voice recognition, touchscreen, and / or biometric recognition mechanisms. Output device 170 may include one or more conventional mechanisms that output information to the user, including a display, printer, one or more speakers, etc. Communication interface 180 may include any transceiver-like mechanism that enables controller unit 100 to communicate with other devices and / or systems. For example, communication interface 180 may include a modem or an Ethernet interface to a local area network (LAN). Alternatively or additionally, communication interface 180 may include other mechanisms for communicating via a network, such as a wireless network. For example, communication interface may include a radio frequency (RF) transmitter and receiver, and one or more antennas for transmitting and receiving RF data.

[0137] The controller unit 100 according to the present invention, as previously described, provides a platform. According to an exemplary embodiment, the controller unit 100 can perform various processes in response to processor 120 executing a sequence of instructions contained in memory 130. Such instructions may be read into memory 130 from another computer-readable medium, such as storage device 150, or from a separate device via communication interface 180. It should be understood that the computer-readable medium may include one or more memory devices or carrier waves. Executing the sequence of instructions contained in memory 130 causes processor 120 to perform the actions already described. In alternative embodiments, hardwired circuitry may be used instead of or in combination with software instructions to implement aspects consistent with the present invention. Therefore, the present invention is not limited to any particular combination of hardware circuitry and software.

[0138] Figure 9 and Figure 10 Show in 3D Figure 7a The pump, which is a further enhancement of the pump of the same applicant's prior art, is therefore part of an enhanced artificial heart. Figure 10 yes Figure 9A cross-sectional view. This embodiment includes a first blood receiving portion 702 of an artificial heart and a drive / actuator system 750 to drive / actuate the artificial heart to generate a pumping mechanism. The artificial heart mainly consists of two pumps 702, a left pump and a right pump (not shown). Each pump includes a blood receiving portion and a drive / actuator system. The blood receiving portion is assembled to the drive system in a simple manner by screws, glue, or assembly. The blood receiving portion includes an artificial atrium 709 and an artificial ventricle 712. Between the artificial atrium 709 and the artificial ventricle 712 is a connecting cylinder 720, which is a one-way valve corresponding to the mitral valve on the left side of the natural heart and the tricuspid valve on the right side of the natural heart. This connecting cylinder may be made of a flexible blood-compatible material, such as polyurethane, silicone, or any other blood-compatible material.

[0139] Each atrium 709 is primarily composed of an atrial covering wall, which consists mainly of two layers: a rigid outer layer and a flexible inner layer. The rigid outer layer 7091 is advantageously made of rigid polyurethane, rigid silicone, a biocompatible metal such as titanium or stainless steel, or any other biocompatible rigid material. The inner layer is a flexible blood-compatible membrane 7092 made of polyurethane, silicone, or any other blood-compatible material. The inner flexible membrane is an extension of the flexible atrial membrane, which is an extension of the flexible membrane 7093, which lines the inner surface of the atrioventricular-cylinder (AV-cylinder) 720, and is an extension of the flexible ventricular membrane 7121. Additionally, there is an atrial protective flexible membrane 7094 protecting the atrial flexible membrane 7092. Furthermore, there is an atrial assembly ring 721, which is rigid and made of rigid polyurethane, rigid silicone, a biocompatible metal such as titanium or stainless steel, or any other biocompatible rigid material. The atrial mounting ring is attached to the upper edge of the drive / actuation system by screws, glue, or a combination thereof. The atrium has an inlet opening 710 to allow blood to flow into the atrium. The pressure window 7641 has a diameter of, for example, at least 5-30 mm, and may be circular, elliptical, or any other shape. The walls of the pressure window consist only of a flexible membrane, without a rigid wall layer. As described above, this pressure window is part of the pressure sensor structure.

[0140] Each ventricle 712 is primarily composed of a ventricular lining wall, which consists mainly of two layers: an outer rigid layer made of rigid polyurethane, rigid silicone, a biocompatible metal such as titanium or stainless steel, or any other biocompatible rigid material; and an inner flexible blood-compatible membrane 7121 made of polyurethane, silicone, or any other blood-compatible material. This inner flexible membrane is an extension of a flexible ventricular membrane 7093, which is lined on the inner surface of the atrioventricular-cylinder 720. Additionally, there is a ventricular protective flexible membrane 7095 protecting the ventricular flexible membrane 7121. Furthermore, there is a ventricular assembly ring 722, which is rigid and made of rigid polyurethane, rigid silicone, a biocompatible metal such as titanium or stainless steel, or any other biocompatible rigid material. The ventricular assembly ring is attached to the lower edge of the drive / actuation system by screws, glue, or a combination thereof.

[0141] The drive / actuator system 750, housed within a housing 762, comprises a gearbox 753 and a motor 751. The housing is made of a rigid, biocompatible plastic material, such as polyetheretherketone (PEEK) and any other biocompatible plastic material or biocompatible metal. The housing encloses the gearbox and motor. The gearbox consists of multiple gears and a metal shaft. The motor is a brushless motor type or any other type of motor with or without an encoder. The motor 751 is arranged within the pump housing between the outlet 713 and the pump. A gasket 760 may be arranged between the outlet 713 housing and the motor 751. The gasket 760 is made of a material with good thermal conductivity, such that when blood (or other fluid) flows through the outlet pipe 700, heat from the drive mechanism is transferred to the blood through the gasket 760 and the wall of the outlet 713, thereby transferring and reducing heat from the drive mechanism.

[0142] The drive / actuation system has a central, cylindrical, enclosed atrioventricular cylinder 720, made of a rigid plastic biocompatible material (such as rigid polyurethane, rigid silicone) or a biocompatible metal (such as titanium, stainless steel) or any other biocompatible rigid material. The atrioventricular cylinder is lined with a flexible membrane 7093, which is an extension of the flexible atrial membrane 7092 and the flexible ventricular membrane 7021. The atrioventricular cylinder encloses a valve 714. There are two racks, 725 and 726, one on each side of the atrioventricular cylinder 720. Each rack is hinged to a gear in a gearbox 753 for actuation in both upward and downward directions.

[0143] There may be wires (not shown) that connect to the drive / actuation system to supply power and control signals to the motor. Additionally, there may be a covering membrane (not shown), a layer of biocompatible plastic material, such as polyurethane or silicone, enclosing the entire drive / actuation system, through which the wires connected to the motor and the conduits for the pressure sensor pass.

[0144] It should be noted that the word "comprising" does not exclude the presence of other elements or steps besides those listed, and the words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements. It should also be noted that any reference numerals do not limit the scope of the claims, the invention can be implemented at least in part by hardware and software, and several "apparatus," "units," or "devices" can be represented by the same hardware.

[0145] The embodiments mentioned and described above are given as examples only and should not limit the invention. Other solutions, uses, purposes, and functions within the scope of the invention claimed in the following patent claims will be apparent to those skilled in the art.

[0146] The various embodiments of the invention described herein are described in the general context of method steps or processes that may be implemented in one embodiment by a computer program product contained in a computer-readable medium, including computer-executable instructions, such as program code, that are executed by a computer in a networked environment. The computer-readable medium may include removable and non-removable storage devices, including but not limited to read-only memory (ROM), random access memory (RAM), optical disc (CD), digital versatile optical disc (DVD), solid-state drives, etc. Typically, program modules may include routines, programs, objects, components, data structures, etc., that perform a particular task or implement a particular abstract data type. The computer-executable instructions, associated data structures, and program modules represent examples of program code for performing steps of the methods disclosed herein. A particular sequence of such executable instructions or associated data structures represents examples of corresponding actions for implementing the functions described in these steps or processes.

[0147] The software and network implementations of various embodiments of the present invention can be accomplished using standard programming techniques with rule-based logic and other logic to perform various database search steps or processes, association steps or processes, comparison steps or processes, and decision steps or processes. It should be noted that, as used herein and in the appended claims, the terms "component" and "module" are intended to encompass implementations using one or more lines of software code, and / or hardware implementations, and / or devices for receiving manual input.

[0148] The foregoing description of embodiments of the present invention is presented for purposes of illustration and description. The description is not intended to be exhaustive, nor does it limit the embodiments of the invention to the precise forms disclosed. Modifications and variations can be made in accordance with the foregoing teachings, or may be obtained from practice of various embodiments of the invention. The embodiments discussed herein were chosen and described to explain the principles and nature of the various embodiments of the invention and their practical application, enabling those skilled in the art to utilize the invention in the various embodiments and make various modifications suitable for the particular intended use. The features of the embodiments described herein can be combined in all possible combinations of methods, apparatus, modules, systems, and computer program products.

Claims

1. A total artificial heart controller unit configured to control a total artificial heart, the total artificial heart including an artificial heart prosthesis, comprising: A first pump section and a second pump section, each pump section comprising a first chamber and a second chamber; The first pump unit is configured to connect to the pulmonary circulation and the second pump unit is configured to connect to the systemic circulation; The inlet of the first chamber in each pump unit is connected to the outlet of the second chamber; Pump actuator, configured to drive the flow of fluid within each pump section; as well as A pressure sensor is installed between the inlet and outlet of each pump section, which is configured to measure the pressure value of the fluid flowing from the inlet to the outlet; The controller unit is configured as follows: Pressure values ​​are received from pressure sensors in each pump section; Obtain the expected stress value; The cardiac output of each pump unit is determined by using the pressure of the first chamber of each pump unit as input. Determine the flow limit and the desired pressure value of the first chamber, wherein the flow limit is the limit of the cardiac output of the first pump section; as well as The flow limit of the first pump and the desired pressure value of the first chamber are controlled based on the cardiac output of the second pump section.

2. The total artificial heart controller unit according to claim 1, comprising the following functional blocks: The flow control function block is configured to calculate the flow limit and the desired pressure value as inputs to keep the output within the range. A cardiac output determination function block configured to determine the cardiac output of at least one pump unit to control the pressure in the first chamber; and Pump stroke rate function block.

3. The total artificial heart controller unit according to claim 1, wherein, The controller unit is configured to maintain the flow rate of the first pump at a first level, so that the second pump does not reach the maximum flow rate level.

4. The total artificial heart controller unit according to claim 1, wherein each pump is independently controlled, and a limit is set on the cardiac output of the pump connected to the pulmonary circulation, the controller unit is further configured to: Obtain the cardiac output of the pump unit connected to the systemic circulation. Given the cardiac output of the pump unit connected to the systemic circulation, a limit is set for the cardiac output of the pump unit connected to the pulmonary circulation, wherein... The limit is updated as the cardiac output of the pump unit connected to the systemic circulation changes; and A control signal is provided to the pump actuator.

5. The total artificial heart controller unit according to claim 1, wherein, Having a defined output, the stroke volume and stroke rate of the two pumps are obtained, and the controller unit is further configured to: Obtain the specific cardiac output of each pump section. The stroke rate is calculated using the determined core output of the two pump sections. Given the obtained stroke rate, the stroke volume of each pump section is obtained such that the product of the stroke rate and the stroke volume is equal to the respective determined cardiac output. and A control signal is provided to the pump actuator of the pump section.

6. The total artificial heart controller unit according to claim 1, comprising a signal receiver for receiving signals to detect whether atrial pressure has decreased or intrathoracic pressure has increased, and performing actions to prevent low atrial pressure or increased intrathoracic pressure.

7. The total artificial heart controller unit according to claim 6, wherein, The controller unit is configured to compare the pressure value of the first chamber, which is averaged over a stroke and received from the pressure sensor, with a desired pressure value, and detect a suction event when the average pressure value of the first chamber drops below the desired pressure by a certain margin.

8. The total artificial heart controller unit according to claim 7, wherein, The controller unit is configured to: average the pressure value of the first chamber during the cycle process to reduce noise and prevent false detection of aspiration events, and once the control unit detects a aspiration event, set an inactive period during which aspiration events are not detected.

9. The total artificial heart controller unit according to claim 8, wherein, Once a suction event is detected, the controller unit is configured to gradually increase the pressure in the determined first chamber to prevent further suction events and generate an alarm.

10. The total artificial heart controller unit according to claim 1, wherein, The fluid is blood.

11. The total artificial heart controller unit according to claim 1, wherein, The first chamber corresponds to either the right atrium or the left atrium.

12. The total artificial heart controller unit according to claim 11, wherein, The pressure sensor is arranged to communicate with the first chamber.

13. The total artificial heart controller unit according to claim 1, wherein, The pressure sensor is configured to measure pressure at a location between the opening at the inlet and the end of the chamber forming the atrium.

14. The total artificial heart controller unit according to claim 1, wherein, The pressure sensor is configured to measure the pressure within the pump chamber to characterize the pleural pressure as a reference pressure.

15. The total artificial heart controller unit according to claim 1, wherein, The control unit includes a PID controller.

16. A total artificial heart prosthesis, comprising the controller unit according to claim 1.

17. A total artificial heart pressure sensor configured to connect to a controller unit according to claim 1, the pressure sensor comprising: A flexible membrane covers the opening portion of the body of the pressure sensor. Pressure transmission medium, The conduit including the pressure transmission medium, and Pressure-sensitive sensor.

18. A cardiac prosthesis comprising the pressure sensor of claim 17 and configured to connect to the total artificial heart controller unit of claim 1.

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