Self-adaptive driving method of total artificial heart

Abstract

The invention relates to a self-adaptive driving method of a total artificial heart, which comprises the following steps: in a diastolic period, driving air to flow out of an air cavity of a TAH ventricle, closing an outflow valve of a blood cavity, opening an inflow valve of the blood cavity, enabling blood to enter the TAH ventricle, continuously discharging the air from the TAH ventricle, and entering a systolic period when partial volume of the TAH ventricle is still not filled with the blood; in the systolic period, the inflow valve for driving air to flow into the TAH ventricle air cavity and the blood cavity is closed, the outflow valve is opened, the diaphragm in the TAH ventricle expands upwards to eject the blood out of the TAH ventricle, and the blood in the TAH ventricle is completely ejected along with continuous entering of the compressed air and further rapid increase of the pressure. The full-artificial heart has the advantages that the driving concept of partial filling and complete ejection is adopted, under the condition that parameters of a driver are not adjusted, the cardiac output can adapt to fluctuation changes of the human body vein return blood volume in a self-adaptive mode, and the full-artificial heart has the driving effect of being self-adaptive to the human body.

Description

Technical Field

[0001] The invention belongs to the technical field of biomedical equipment use, and in particular relates to an adaptive driving method for a total artificial heart. Background Art

[0002] As the global population continues to age, the incidence of cardiovascular disease is on the rise, and the terminal course of cardiovascular disease is heart failure, the full name of which is heart failure. According to the "2023 China Heart Failure Industry White Paper", between 2000 and 2015, the prevalence of heart failure patients in my country increased by 44%, with about 500,000 new heart failure patients each year, of which about 5% will progress to refractory end-stage heart failure. In the existing market, heart transplantation is considered the best and most effective treatment option for patients with refractory end-stage heart failure. According to data from my country's heart transplant registration system, as of 2022, there are 72 medical institutions in my country that are qualified for heart transplantation, but due to the extreme shortage of donors, there is still a huge gap between the number of heart transplant surgeries and the number of refractory heart failure patients each year, and only a small number of heart failure patients are expected to receive heart transplantation.

[0003] In the case of an extreme shortage of heart donors, mechanical circulatory support devices are devices that can replace some of the heart's functions, providing effective help to patients with end-stage heart failure and bringing new hope of survival to patients with end-stage heart failure. Its basic principle is to assist or replace the failing heart, complete the body's blood circulation, and enable it to meet the body's hemodynamics.

[0004] Mechanical circulatory support devices include total artificial hearts (TAHs) and ventricular assist systems (VADs). At present, there are no total artificial hearts in clinical use in China, and domestic medical institutions mostly use cardiac assist devices, also known as ventricular assist devices, for the clinical treatment of heart failure.

[0005] The invention patent with application number 2018115611044, application date 2018.12.20, and authorization announcement date 2021.10.08 discloses an indifferent adaptive physiological control method based on the left ventricular assist device LVAD. First, the preload from the left ventricle is measured as the input value of the control system, thereby generating a reference value of the average pump flow required by the patient and a reference value of the pulsation value of the pump flow. The next step is to process the signal, and finally adjust the controller according to the system processing results, and directly control the LVAD through the output current signal to achieve the desired pump speed.

[0006] The invention patent with application number 2024101914475, application date 2024.02.21, and application publication date 2024.05.31 discloses a multi-objective adaptive control method for a heart pump based on the Frank-starling mechanism. This method uses the average pump flow and left ventricular end-diastolic pressure, i.e., preload, obtained by flow and pressure sensors as the input of the Frank-starling module, and establishes an algorithm based on the natural heart Frank-starling mechanism to iteratively calculate the expected pump flow and preload of the regression point, and then uses dual feedback PI to control the pressure and flow to approach the ideal value.

[0007] The above two technical solutions are only applicable to left ventricular assist devices (LVADs), and both are based on theoretical calculations based on measured preload data, and then adaptive flow control is generated by adjusting the operating speed of the LVAD. Both solutions are based on the Frank-Starling curve model for data analysis and calculation, but the Frank-Starling curve will be affected by individual differences. The size, shape, functional state of the heart of different individuals, individual age, health, body fluid and endocrine conditions, individual exercise, rest and other different states will affect the Frank-Starling curve. Therefore, it is difficult to produce an adaptive effect that fully conforms to the individual Frank-Starling curve by only relying on data collection and theoretical data for analysis and calculation.

[0008] In summary, the theoretical algorithms of existing technical solutions all rely on the collection and calculation of native heart preload data. The data analysis process is affected by many factors such as signal acquisition sensitivity, response speed, and control accuracy. It is difficult to provide adaptive feedback on the individual hemodynamic state in real time, and it is not suitable for the drive control of the total artificial heart (TAH). Summary of the invention

[0009] In order to make up for the deficiencies of the prior art, the present invention provides an adaptive driving method for a total artificial heart which has simple control, does not require real-time monitoring of parameters, and does not require additional analysis and calculation.

[0010] The present invention is achieved through the following technical solutions: An adaptive driving method for a total artificial heart is characterized by comprising the following steps: (1) During the diastole, the air is driven to flow out of the TAH ventricular cavity. The gas in the cavity begins to be discharged, the outflow valve of the blood cavity closes, the inflow valve opens, and blood enters the TAH ventricle. At the same time, the gas continues to be discharged from the cavity. When there is still part of the volume of the TAH ventricle that is not filled with blood, it enters the systole. (2) During the systole, air is driven to flow into the TAH ventricular air cavity, and the inflow valve of the blood cavity is closed. When the pressure in the TAH ventricular air cavity overcomes the afterload resistance, the outflow valve is opened, and the diaphragm in the TAH ventricle expands and moves upward, ejecting blood from the TAH ventricle. When the diaphragm in the TAH ventricle can no longer move further, the pressure in the TAH ventricle changes isovolumetrically. As compressed air continues to enter, the pressure in the air cavity increases further and rapidly, completely ejecting the blood in the TAH ventricle.

[0011] Preferably, in step (1), when the amount of venous blood returning to the heart increases, the reserved volume of the TAH ventricle can adaptively increase the filling volume of blood during diastole.

[0012] Preferably, in step (1), the reserved volume is 10%-20% of the total ventricular volume of the TAH.

[0013] Preferably, in step (2), the driving pressure is 30-40 mmHg higher than the arterial pressure to achieve complete ejection.

[0014] Preferably, in step (2), it can be determined that complete ejection has been completed during the systolic period by a sudden increase in the air cavity pressure.

[0015] The beneficial effects of the present invention are as follows: by adopting the driving concept of "partial filling and complete ejection", the cardiac output can adapt to the fluctuation of the human body's venous return blood volume without adjusting the driver parameters, so that the total artificial heart can play a driving effect of adapting to the human body; the control principle is simple and clear, and there is no need to monitor the various mechanism parameters of the human body in real time, nor does it require additional complex analysis and data calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below in conjunction with the accompanying drawings.

[0017] Attached Figure 1 It is a schematic structural diagram of the total artificial heart of the present invention during the systolic period; Attached Figure 2 It is a schematic structural diagram of the total artificial heart of the present invention during diastole; Attached Figure 3 A pressure-time curve diagram of the total artificial heart during the contraction phase of the present invention; Attached Figure 4 A blood filling volume-time curve diagram of the total artificial heart during the diastolic phase of the present invention; In the figure, 1 is the TAH ventricle, 2 is the inflow valve, 3 is the outflow valve, and 4 is the air inlet and outlet. DETAILED DESCRIPTION

[0018] The accompanying drawing is a specific embodiment of the present invention. This embodiment includes two stages, "partial filling" and "complete ejection", which correspond to the diastole and systole of the TAH respectively. In each diastole, the filling volume of the TAH ventricle is kept in a partially filled state; and in each systole, it is ensured that the filled blood can be completely ejected. "Partial filling" reserves a part of the filling space of the TAH ventricle 1 during diastole. When the amount of venous blood returning to the body increases, this part of the reserved space will adaptively increase the filling volume of the TAH ventricle during diastole. "Complete ejection" means that no matter how much blood is filled in the TAH ventricle during diastole, the blood can be completely ejected during systole.

[0019] The cardiac output of the total artificial heart (TAH) = operating frequency × ventricular stroke volume. For example, if the maximum filling capacity of the TAH ventricle is designed to be 70cc, according to the principle of "partial filling", the stroke volume of the TAH ventricle in actual work can be controlled to 50-60cc, and the reserved filling space of 10-20cc of the TAH ventricle is retained. According to the principle of "complete ejection", the driver parameters of the TAH are adjusted to a state where no matter how much the filling volume is, the afterload can be completely overcome to eject all the filling blood. At this time, if the venous return of the human body increases, the stroke volume of the TAH ventricle will also increase (increased to 55-65cc), but because each filling will be completely ejected, the cardiac output of the TAH will increase without modifying the TAH operating frequency; conversely, if the venous return of the human body decreases, the stroke volume of the TAH ventricle will also decrease (reduced to 45-55cc), and the cardiac output will also decrease. At this time, the TAH is in an adaptive working state.

[0020] The adaptive driving method of the total artificial heart of the present invention is adopted, such as Figure 3 As shown in the figure, the typical pressure-time curve shows the changes of the total artificial heart (TAH) during a contraction period. In the AB segment of the pressure curve, air is driven into the ventricular air cavity of the TAH. The pressure of the ventricular air cavity rises rapidly, and the inflow valve of the blood cavity is closed until the ventricular pressure overcomes the afterload resistance and the outflow valve is opened; in the BC segment, the outflow valve is opened, the ventricular septum expands and moves upward, ejecting blood from the ventricle, and the ventricular pressure continues to increase but the slope of the curve decreases; Point C is a marker, indicating that the ventricular septum cannot move further. As the compressed air continues to enter, the ventricular pressure changes in an isochoric manner and the pressure increases further rapidly; the CD segment is a typical sign of complete ejection, which means that the blood in the ventricle has been completely ejected.

[0021] The ventricle then enters diastole under the control of the driver, the intraventricular pressure decreases rapidly, and the pressure curve moves rapidly toward the initial pressure. If the pressure provided by the driver cannot overcome the patient's afterload pressure, the reduction in TAH driving pressure will lead to a decrease in cardiac output and an increase in venous pressure. Complete ejection can increase organ perfusion and reduce blood congestion. Complete ventricular ejection is achieved by providing a driving pressure 30 to 40 mmHg higher than arterial pressure.

[0022] like Figure 4 , the typical flow curve shows the change in the filling volume of the TAH during a diastolic period. In the initial stage AB, the driving air begins to flow out of the TAH ventricle, the gas in the air cavity part of the ventricle begins to be discharged, and the outflow valve of the blood cavity is closed; at point B, the inflow valve opens, blood begins to enter the ventricle, and the gas continues to be discharged from the ventricle. The BD segment is the diastolic period of the TAH, from point B to point D, indicating the filling process of the TAH from the beginning of filling to the beginning of ejection. Point B is the time when filling begins. Integrating the flow curve between point B and point D, that is, the area under the BD segment curve, can obtain the filling volume of the TAH during diastole.

[0023] The state of the flow curve between the BD segments can indicate whether the ventricle is partially filled or fully filled. When the flow curve drops to 0 in the BD segment, it means that the ventricle is fully filled, such as point C. At this time, the cardiac output can be increased by increasing the heart rate. When the heart rate increases, the TAH systolic and diastolic times will be shortened, thereby shortening the distance between points D and B. By adjusting the percentage of contraction, the proportion of systolic period in the cardiac cycle can be adjusted to optimize the filling time of the ventricle. Another method of adjusting the filling volume of the ventricle can also be provided by the vacuum degree in the diastolic period, that is, the negative pressure in the diastolic period of the ventricle will increase the filling volume of the ventricle. In diastole (BD segment), the ventricle cannot be fully filled, that is, the flow curve cannot drop to 0 in the BD segment, such as point E. The state of the flow curve at this time represents the partial filling of the TAH in diastole, and area 5 provides a reserve space for responding to the increase in venous return. When the heart rate of TAH remains unchanged and the amount of venous blood returning to the heart increases, the flow curve in the BD segment will rise, bringing point E closer to point D, thereby increasing the filling volume of the ventricle and the cardiac output will also increase accordingly.

[0024] By adopting the adaptive driving method of the total artificial heart of the present invention, as long as the TAH ventricle is "fully ejected" during the systole period and is not completely filled, i.e. "partially filled" during the diastole period, the TAH can operate along the curve of the Frank-Starling mechanism, and the change in the venous return volume will be converted into the change in cardiac output, thereby enabling the TAH to adapt to the human body's venous return volume without changing other parameters.

Claims

1. An adaptive driving method for a total artificial heart, characterized in that: The following steps are involved: (1) During the diastole, the air is driven to flow out of the TAH ventricular cavity. The gas in the cavity begins to be discharged, the outflow valve of the blood cavity closes, the inflow valve opens, and blood enters the TAH ventricle. At the same time, the gas continues to be discharged from the cavity. When there is still part of the volume of the TAH ventricle that is not filled with blood, it enters the systole. (2) During the systole, air is driven to flow into the TAH ventricular air cavity, and the inflow valve of the blood cavity is closed. When the pressure in the TAH ventricular air cavity overcomes the afterload resistance, the outflow valve is opened, and the diaphragm in the TAH ventricle expands and moves upward, ejecting blood from the TAH ventricle. When the diaphragm in the TAH ventricle can no longer move further, the pressure in the TAH ventricle changes isovolumetrically. As compressed air continues to enter, the pressure in the air cavity increases further and rapidly, completely ejecting the blood in the TAH ventricle.

2. The adaptive driving method of a total artificial heart according to claim 1, characterized in that: In step (1), when the amount of venous blood returning to the heart increases, the reserved volume of the TAH ventricle can adaptively increase the blood filling volume during diastole.

3. The adaptive driving method of a total artificial heart according to claim 1, characterized in that: In step (1), the reserve volume is 10%-20% of the total TAH ventricular volume.

4. The adaptive driving method of a total artificial heart according to claim 1, characterized in that: In step (2), the driving pressure is 30-40 mmHg higher than the arterial pressure to achieve complete ejection.

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