Self-adaptive driving method of total artificial heartTechnical Field
The invention belongs to the technical field of biomedical equipment, and particularly relates to a self-adaptive driving method of a full artificial heart.
Background
With the increasing degree of global population aging, the incidence of cardiovascular disease is in an ascending stage, and the final course of cardiovascular disease is heart failure, which is known as heart failure. According to the data of 2023 white paper of heart failure industry, the prevalence rate of heart failure patients in China is increased by 44% in 2000 to 2015, and about 50 ten thousand new heart failure patients exist each year, wherein about 5% of patients can progress to refractory end-stage heart failure. The existing market considers the heart-moving vegetation as the best and effective treatment scheme for refractory end-stage heart failure patients. According to the data of the heart transplantation registration system in China, 72 medical institutions in China have heart transplantation qualification by 2022, but due to the extreme shortage of donors, a huge gap exists between the number of heart transplantation operations per year and the number of refractory heart failure patients, and only a small part of heart failure patients are expected to receive heart transplantation operations.
In the case of an extremely deficient heart donor, the mechanical circulatory support device is a device which can replace part of the heart function, can provide effective help for patients with end-stage heart failure and brings new living hopes for patients with end-stage heart failure. The basic principle is to assist or replace a failed heart to complete the blood circulation of a human body so as to enable the heart to meet the hemodynamics of the human body.
Mechanical circulatory support devices include Total Artificial Hearts (TAHs) and Ventricular Assist Systems (VADs). At present, no fully artificial heart is clinically used in China, and heart auxiliary devices are mostly adopted in clinical application of domestic medical institutions for treating heart failure, and are also called ventricular auxiliary devices.
The patent application number 2018115611044, application day 2018.12.20 and issued publication day 2021.10.08 disclose a non-differential self-adaptive physiological control method based on a left ventricular assist device LVAD, wherein the reference value of the average pump flow and the reference value of the pulsation value of the pump flow required by a patient are generated by measuring the preload from the left ventricle as the input value of a control system. And processing the signal, and finally adjusting the controller through a system processing result, and directly controlling the LVAD through the output current signal so as to achieve the desired pump rotating speed.
The invention patent of application number 2024101914475, application date 2024.02.21 and application publication date 2024.05.31 discloses a heart pump multi-target self-adaptive control method based on a Frank-starling mechanism, wherein average pump flow obtained through flow and pressure sensors and left ventricular end diastole pressure, namely preload, are input as Frank-starling modules, expected pump flow and preload of regression points are calculated through iterative calculation according to a natural heart Frank-starling mechanism, and double feedback PI is used for controlling pressure and flow to approach ideal values.
Both of the above solutions are only applicable to Left Ventricular Assist Devices (LVADs) and are both theoretically calculated based on measured preload data, and then an adaptive flow control is generated by adjusting the operating speed of the LVAD. Both schemes are based on the Frank-starling curve model for data analysis and calculation, but the Frank-starling curve is affected by the difference among individuals, the size, shape and functional state of the heart of different individuals, the age, health condition, body fluid and endocrine condition of individuals, and the different states of movement, rest and the like of individuals can affect the Frank-starling curve, so that the analysis and calculation are only carried out by data acquisition and theoretical data, and the adaptability effect which completely accords with the Frank-starling curve of the individuals is difficult to generate.
In summary, the theoretical algorithm in the prior art relies on the acquisition and calculation of the preload data of the native heart, the analysis process of the data is affected by various factors such as signal acquisition sensitivity, response speed, control accuracy and the like, and the adaptive feedback of the state of the individual hemodynamics is difficult to carry out in real time, and is not suitable for the driving control of the Total Artificial Heart (TAH).
Disclosure of Invention
The invention provides a self-adaptive driving method of a full artificial heart, which is simple to control, does not need to monitor parameters in real time and does not need additional analysis and calculation in order to make up the defects of the prior art.
The invention is realized by the following technical scheme:
the self-adaptive driving method of the total artificial heart is characterized by comprising the following steps of:
(1) In diastole, driving air to flow out of the TAH ventricular air cavity, discharging the air in the air cavity part, closing the outflow valve of the blood cavity, opening the inflow valve, and allowing blood to enter the TAH ventricle, and continuously discharging the air from the air cavity, wherein the TAH ventricle enters systole when the partial volume of the TAH ventricle is still not filled with the blood;
(2) In the systolic period, driving air flows into the TAH ventricle cavity, the inflow valve of the blood cavity is closed, when the pressure in the TAH ventricle cavity overcomes afterload resistance, the outflow valve is opened, the diaphragm in the TAH ventricle expands upwards to move, blood is ejected out of the TAH ventricle, when the diaphragm in the TAH ventricle can not move any further, at the moment, the pressure in the TAH ventricle changes in an isovolumetric manner, and as compressed air continues to enter, the pressure in the air cavity further increases rapidly, and the blood in the TAH ventricle is ejected completely.
Preferably, in step (1), the reserved volume of the TAH ventricle is capable of adaptively increasing the filling amount of the diastolic blood when the venous return blood volume of the human body is increased.
Preferably, in step (1), the reserved volume is 10% -20% of the total volume of the TAH ventricle.
Preferably, in step (2), the driving pressure is 30-40mmHg higher than the arterial pressure to achieve complete ejection.
Preferably, in step (2), it can be judged that complete ejection has been completed during the systolic phase by a sudden increase in the air cavity pressure.
The invention has the beneficial effects that the driving concept of 'partially filling and completely ejecting blood' is adopted, so that the cardiac output can be self-adapted to the fluctuation and change of the venous return blood volume of the human body under the condition of not adjusting the parameters of the driver, the fully artificial heart has the driving effect of self-adapting to the human body, the control principle is simple and clear, various mechanism parameters of the human body do not need to be monitored in real time, and additional complex analysis and data calculation are also not needed.
Drawings
The invention is further described below with reference to the accompanying drawings.
FIG. 1 is a schematic diagram of the structure of the full artificial heart in systole;
FIG. 2 is a schematic diagram of the structure of the full artificial diastole of the present invention;
FIG. 3 is a graph of pressure versus time for the systolic phase of the total artificial heart of the present invention;
FIG. 4 is a graph of blood fill volume versus time for the diastolic phase of the full artificial heart of the present invention;
In the figure, 1TAH chamber, 2 inflow valve, 3 outflow valve, 4 air inlet and outlet.
Detailed Description
The drawings illustrate one embodiment of the invention. This embodiment includes two phases, a "partial fill" and a "complete ejection", corresponding to the diastolic and systolic phases of TAH, respectively. The filling amount of the TAH ventricle is kept at a partially filled state during each diastole, while it is ensured that the filled blood is completely ejected during each systole. The partial filling ensures that a part of filling space is reserved in the diastolic phase of the TAH ventricle 1, and when the venous return blood volume of the human body is increased, the filling volume of the diastolic phase of the TAH ventricle is adaptively increased by the reserved space. By "fully ejected" is meant that the TAH ventricle can fully eject blood during systole, regardless of how much of it fills during diastole.
Cardiac output = operating frequency x ventricular volume per beat of Total Artificial Heart (TAH). For example, if the maximum filling capacity of the TAH ventricle design is 70cc, according to the principle of partial filling, the filling amount of each beat of the TAH ventricle in actual work can be controlled to be 50-60 cc, and 10-20 cc of reserved filling space of the TAH ventricle is reserved. In accordance with the principle of "complete ejection", the actuator parameters of the TAH are adjusted to completely overcome the condition that the whole filling blood is ejected by the afterload, regardless of the filling amount. At this time, if the venous return blood volume of the human body is increased, the filling amount of each beat of the TAH ventricle is increased (to 55-65 cc), but since each filling is completely ejected, the cardiac output of the TAH is increased without modifying the working frequency of the TAH, otherwise, if the venous return blood volume of the human body is reduced, the filling amount of each beat of the TAH ventricle is also reduced (to 45-55 cc), and the cardiac output is also reduced, and the TAH is in a self-adaptive working state.
With the adaptive driving method of the total artificial heart of the present invention, as shown in fig. three, a typical pressure time curve shows the variation of the Total Artificial Heart (TAH) during a systole. The pressure curve is characterized in that air is driven to flow into a TAH (total internal pressure) ventricular air cavity in an A-B section of the pressure curve, the pressure in the ventricular air cavity is rapidly increased, an inflow valve of a blood cavity is closed until the pressure in the ventricle overcomes afterload resistance, an outflow valve is opened, in a B-C section, an intraventricular diaphragm is opened to expand and move upwards to eject blood out of the ventricle, the pressure in the ventricle is continuously increased but the slope of the curve is reduced, a point C is a marker bit and marks that the intraventricular diaphragm cannot move any further, the pressure in the ventricle is in isovolumetric change along with the continuous entry of compressed air, the pressure is further rapidly increased, and a C-D section is a typical mark of complete ejection of the intraventricular blood at the moment.
The ventricles then enter diastole under driver control, the pressure in the ventricles rapidly decreasing, and the pressure profile moving rapidly towards the initial pressure. If the pressure provided by the driver is not able to overcome the patient's afterload pressure, it may result in a decrease in cardiac output and an increase in venous pressure due to a decrease in TAH driving pressure. Complete ejection can increase organ perfusion and reduce blood stasis. The complete ejection of the ventricles is achieved by providing a driving pressure 30-40 mmhg higher than the arterial pressure.
As shown in fig. four, the typical flow curve shows the change in TAH filling during one diastole. In the initial phase A-B, the driving air starts to flow out of the TAH ventricle, the gas in the air cavity part of the ventricle starts to be discharged, the outflow valve of the blood cavity is closed, and at the point B, the inflow valve is opened, the blood starts to enter the ventricle, and the gas continues to be discharged from the ventricle. Segment B-D is the diastolic phase of TAH, from point B to point D, indicating the filling process of TAH from the beginning of filling to before ejection of blood. The point B is the time of starting filling, and the filling quantity of the TAH diastole can be obtained by integrating the flow curve between the point B and the point D, namely the area under the B-D section curve.
The state of the flow curve between the B-D segments can show whether it is partially filled or completely filled. When the flow curve decreases to 0 in the B-D segment, which represents that the heart chamber has been completely filled, such as at point C, the cardiac output can be increased by increasing the heart rate. And when the heart rate increases, the TAH systolic period and diastolic period are shortened, so that the distance between the point D and the point B is shortened. The rate of systole can be adjusted by adjusting the percentage of systole, thereby optimizing the filling time of the ventricles. Another way of regulating the ventricular filling can also be provided by the vacuum level during diastole, i.e. the negative pressure during diastole will increase the ventricular filling. During diastole (B-D), the ventricle cannot fill completely, i.e. the flow profile cannot drop to 0, e.g. E, in B-D, the flow profile state at which it is representative of the partial filling of TAH during diastole, region 5 providing a reserve for responding to an increase in venous return blood volume. When the heart rate of the TAH is unchanged and the venous return blood volume is increased, the flow curve in the B-D section is lifted, so that the E point is close to the D point, the filling volume of the ventricle is increased, and the cardiac output is also increased.
By adopting the self-adaptive driving method of the total artificial heart, as long as the TAH ventricle is completely ejected in the systolic period and is not completely filled in the diastolic period, namely, is partially filled, the TAH can run along the curve of the Frank-Starling mechanism, and the change of the venous return blood volume can be converted into the change of the cardiac output, so that the TAH can realize the self-adaptation of the venous return blood volume of a human body under the condition that other parameters are not required to be changed.