A method for calculating the working pressure of a pulsating blood pump

Abstract

The present invention discloses a method for calculating the working pressure of a pulsating blood pump. The calculation method comprises: obtaining working parameters and size parameters according to the technical principle and structure of the pulsating blood pump; calculating the time for a single cycle of blood to be sucked into a diaphragm cavity from the left ventricle and the time for blood to be discharged from the diaphragm cavity to the ascending aorta according to the working parameters; calculating the blood flow rate at different positions along the process of blood sucking into the diaphragm cavity and blood being discharged to the ascending aorta according to the working parameters, size parameters and time; calculating the pressure loss and local pressure loss along the catheter during the process of blood sucking into the diaphragm cavity and blood being discharged to the ascending aorta based on the blood flow rate at different positions; calculating the minimum working pressure of the diaphragm cavity during the process of blood sucking into the diaphragm cavity and the maximum working pressure of the diaphragm cavity during the process of blood being discharged to the ascending aorta according to the law of energy conservation. The calculation method of the present invention can guide the structural optimization design of the pulsating blood pump and the development of the control system.

Description

Technical Field

[0001] The invention relates to a method for calculating the working pressure of a pulsating blood pump, and belongs to the technical field of medical apparatus ventricular assist devices. Background Art

[0002] In recent years, percutaneous mechanical circulatory assist technology has played an important role in the treatment of critical cardiac diseases such as high-risk PCI and cardiogenic shock patients. It includes intraaortic balloon pump (IABP) and interventional ventricular assist pump (Impella), and these two technologies still have room for improvement in assist flow and biocompatibility.

[0003] Patent document CN 220159038 U discloses a circulatory assist device that can provide pulsatile blood flow, which includes a single-lumen catheter, a valve assembly, and an extracorporeal membrane chamber. The single-lumen catheter includes a distal first catheter and a proximal second catheter, the distal end of the first catheter is provided with an inflow window, and the two catheters are connected by a valve assembly, and the valve allows blood to be sucked in axially and flow out laterally. The extracorporeal membrane chamber includes two independent upper and lower accommodating chambers, the blood chamber and the gas chamber are separated by a diaphragm, the gas chamber joint is connected to the extracorporeal pump, and the blood chamber is connected to the second catheter. In clinical use, the distal inflow window of the first catheter is located in the left ventricle, the valve assembly is placed in the ascending aorta, and the extracorporeal pump periodically provides positive and negative pressures. When the pressure is negative, the blood is sucked from the left ventricle into the blood chamber through the valve, and when the pressure is positive, the blood is pumped laterally from the blood chamber to the ascending aorta through the valve assembly.

[0004] The driving gas of the device's extracorporeal pump usually adopts a flow control mode, which requires sufficient working pressure to meet the auxiliary flow requirements. The device's diaphragm cavity volume, catheter inner diameter, valve channel size, pumping frequency and target auxiliary flow will all affect the working pressure of the extracorporeal pump. Due to the irregular structure of the blood cavity and complex flow, the calculation of the internal driving pressure is an urgent problem to be solved. Summary of the invention

[0005] The object of the present invention is to provide a method for calculating the working pressure (internal driving pressure) of a pulsating blood pump, which can guide the structural design optimization and control system development of such devices.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for calculating the working pressure of a pulsatile blood pump comprises the following steps:

[0008] (1) Obtaining working parameters and dimensional parameters based on the technical principle and structure of the pulsatile blood pump;

[0009] (2) according to the working parameters obtained in step (1), calculating the time for a single cycle of blood to be sucked into the membranous cavity from the left ventricle and the time for blood to be discharged from the membranous cavity to the ascending aorta;

[0010] (3) calculating the blood flow rate at different positions along the process of blood being sucked into the membrane cavity and blood being discharged into the ascending aorta according to the working parameters and size parameters obtained in step (1) and the time obtained in step (2);

[0011] (4) based on the blood flow rate obtained in step (3), calculating the pressure loss along the catheter and the local pressure loss during the process of blood being sucked into the membrane cavity and the process of blood being discharged into the ascending aorta;

[0012] (5) Based on the law of conservation of energy, calculate the minimum working pressure of the diaphragm cavity during the process of blood being absorbed into the diaphragm cavity and the maximum working pressure of the diaphragm cavity during the process of blood being discharged into the ascending aorta.

[0013] Furthermore, the pulsating blood pump described in the present invention includes a single-lumen catheter, a valve assembly, an extracorporeal membrane chamber and an extracorporeal control system; the single-lumen catheter includes a distal first catheter and a proximal second catheter, the distal end of the first catheter is provided with an inflow window, and the first catheter and the second catheter are connected by a one-way valve assembly; the extracorporeal membrane chamber includes two independent upper and lower blood chambers and gas chambers, the two chambers are separated by a flexible membrane, the gas chamber is connected to the extracorporeal control system through a tracheal joint, and the blood chamber is connected to the second catheter through a catheter joint; when in use, the inflow window of the first catheter is located in the left ventricle, the one-way valve assembly is located in the ascending aorta, and the extracorporeal control system periodically provides positive and negative pressures, when negative pressure occurs, blood is sucked from the left ventricle into the blood chamber, and when positive pressure occurs, blood is laterally pumped from the blood chamber to the ascending aorta through the one-way valve assembly.

[0014] Furthermore, the working parameters include auxiliary flow Q, pulsation frequency f, single blood suction time a of the diaphragm cavity, and single blood discharge time b; the size parameters include first catheter length 11, second catheter length l2, catheter inner cavity cross-sectional area S1, diaphragm cavity catheter connector inner cavity cross-sectional area S2, valve channel area S3 when blood is sucked into the blood cavity, valve channel area S4 when blood is discharged to the ascending aorta, projection area S5 of blood flow direction in the diaphragm cavity, and left ventricular inner cavity cross-sectional area S6.

[0015] Furthermore, in step (2), the calculation formula for the time for a single cycle of blood to be sucked from the left ventricle into the membrane cavity is:

[0016]

[0017] The calculation formula for the time it takes for blood to be discharged from the membranous cavity to the ascending aorta in a single cycle is:

[0018]

[0019] Wherein, t1 represents the time for a single circulation of blood to be sucked from the left ventricle into the membranous cavity, and t2 represents the time for a single circulation of blood to be discharged from the membranous cavity to the ascending aorta.

[0020] Furthermore, in the step (3), during the process of blood being sucked from the left ventricle into the membrane cavity, the calculation formula for the blood flow rate at different positions along the way from the inner cavity of the left ventricle to the membrane cavity catheter connector is:

[0021]

[0022] Among them, v i It represents the blood flow velocity at different positions from the left ventricular cavity to the membrane cavity connector, S j It indicates the cross-sectional area at different positions from the left ventricular lumen to the membrane-type luminal catheter connector;

[0023] v1=F1(S1) represents the blood flow rate in the catheter during the process of blood being sucked into the membrane cavity.

[0024] v2 = F1 (S2) represents the blood flow rate in the membrane cavity catheter connector during the process of blood being sucked into the membrane cavity,

[0025] v3=F l (S3) represents the blood flow rate inside the valve during the process of blood being sucked into the membrane cavity,

[0026] v4=F1(S6) represents the blood flow rate in the left ventricular cavity during the process of blood being sucked into the membrane cavity;

[0027] In the process of blood being discharged from the membranous cavity to the ascending aorta, the formula for calculating the blood flow rate at various locations along the way from the inner cavity of the membranous cavity to the valve outlet is as follows:

[0028]

[0029] Among them, v k Indicates the blood flow rate from the inside of the membrane cavity to different positions of the valve outlet, S i Indicates the cross-sectional area at different positions from the inner cavity of the diaphragm chamber to the valve outlet;

[0030] v5 = F2 (S1) represents the blood flow rate in the catheter during the process of blood discharge to the ascending aorta,

[0031] v6 = F2 (S2) represents the blood flow rate in the membrane-type lumen catheter connector during the process of blood being discharged into the ascending aorta.

[0032] v7=F2(S4) represents the blood flow rate of the valve outlet during the blood discharge to the ascending aorta.

[0033] v8=F2(S5) represents the blood flow rate in the membranous cavity during the process of blood being discharged into the ascending aorta.

[0034] Furthermore, the left ventricular cavity cross-sectional area S6 is determined according to the left ventricular short-axis cross-sectional area at the end of the left ventricular isovolumetric relaxation period, and the projection area S5 in the blood flow direction of the membrane cavity is determined according to the maximum projection area of ​​the flexible membrane in the moving direction.

[0035] Furthermore, in the step (4), during the process of blood being sucked from the left ventricle into the membrane cavity, the calculation formula for the pressure loss along the catheter and the local pressure loss is as follows:

[0036]

[0037]

[0038] Among them, p f1 is the pressure loss along the catheter during the process of blood being sucked into the membrane cavity, p j1 It represents the local pressure loss of the catheter during the process of blood being sucked into the membrane cavity, and ρ represents the blood density of 1055 kg / m 3 , λ is the loss coefficient along the way, d is the inner diameter of the catheter, ξ1 represents the energy loss coefficient of blood entering the valve, ξ2 represents the energy loss coefficient of blood flowing out of the valve, and ξ3 represents the energy loss coefficient of blood flowing into the catheter connector;

[0039] When blood is discharged from the membranous cavity to the ascending aorta, the calculation formula for the pressure loss along the catheter and the local pressure loss is as follows:

[0040]

[0041]

[0042] Among them, p f2 is the pressure loss along the catheter during the discharge of blood into the ascending aorta, p j2 is the local pressure loss of the catheter during the process of blood being discharged into the ascending aorta, ξ4 represents the energy loss coefficient of blood entering the catheter through the catheter connector, and ξ5 represents the energy loss coefficient of blood flowing through the outflow valve.

[0043] Furthermore, the along-the-way loss coefficient λ and the local loss coefficient ξ are determined by experiments.

[0044] Furthermore, in the step (5), during the process of blood being sucked from the left ventricle into the diaphragm cavity, the minimum pressure inside the diaphragm cavity is calculated by the following formula:

[0045]

[0046] When blood is discharged from the diaphragm cavity to the ascending aorta, the maximum working pressure inside the diaphragm cavity is calculated as follows:

[0047]

[0048] Among them, P1 is the minimum working pressure when blood is sucked into the diaphragm cavity, P2 is the maximum working pressure when the diaphragm cavity discharges blood, LVP is the left ventricular pressure, AOP is the aortic pressure, and y is the safety factor.

[0049] Furthermore, the LVP is determined according to the left ventricular pressure at the end of isovolumetric relaxation, with a value range of 0-10 mmHg, and the aortic pressure AOP is determined according to the aortic pressure at the end of the rapid ejection phase, with a value range of 100-140 mmHg.

[0050] The safety factor y takes into account the influence of the hemodynamic effect and the time interval between the contraction and expansion of the flexible membrane on the working pressure, and has a value range of 1-1.2.

[0051] Beneficial effects of the present invention:

[0052] (1) The present invention calculates the working pressure of the pulsatile pump according to the working parameters and size parameters, which can guide the research and development of the extracorporeal pump control system and ensure that the pulsatile pump can meet the expected flow requirements when it is actually used;

[0053] (2) Through the calculation method of the present invention, researchers can evaluate the effect of the flow area of ​​the catheter or valve assembly on the working pressure of the pulsating pump, thereby guiding the iteration and optimization of the product structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a flow chart of the method for calculating the working pressure of the pulsatile blood pump of the present invention.

[0055] Figure 2 A working principle diagram of a pulsatile blood pump according to an embodiment of the present invention.

[0056] Figure 3 This is a schematic diagram of blood flow when a pulsating pump according to an embodiment of the present invention draws blood into a membrane cavity.

[0057] Figure 4 Schematic diagram of the cross-sectional area of ​​the left ventricular cavity according to an embodiment of the present invention.

[0058] Figure 5 This is a schematic diagram of blood flow when a pulsatile pump discharges blood from a diaphragm cavity to the ascending aorta according to an embodiment of the present invention.

[0059] Figure 6 It is a schematic diagram of the maximum cross-section of the flexible membrane inside the pulsating pump according to an embodiment of the present invention.

[0060] Figure 7 Schematic diagram of the projection area of ​​the flexible membrane inside the pulsatile pump in the direction of blood flow according to an embodiment of the present invention.

[0061] Figure 8 This is a curve diagram of human left ventricular pressure and aortic pressure. DETAILED DESCRIPTION

[0062] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. Those skilled in the art may make various changes or modifications to the present invention after reading the present invention, and these equivalent forms also belong to the scope limited by the appended claims of the present application.

[0063] As the pulsatile blood pump described in the present invention, the pulsatile blood pump structure described in patent document CN 220159038U can be used, such as Figure 2 , 3 As shown in Figure 5, the pulsatile blood pump includes a single-lumen catheter 1, a one-way valve assembly 2, an extracorporeal membrane chamber 3 and an extracorporeal control system 4. The single-lumen catheter 1 includes a first catheter 11 and a second catheter 12. The first catheter 11 is provided with an inflow window at the distal end. The one-way valve assembly 2 is connected between the first catheter 11 and the second catheter 12. The extracorporeal membrane chamber 3 includes two independent blood chambers 31 and gas chambers 32, which are separated by a flexible membrane. The gas chamber 32 is connected to the extracorporeal control system 4 (including the extracorporeal pump) through a tracheal connector 33. The blood chamber 31 is connected to the second catheter 12 through a catheter connector. The single-lumen catheter 1 enters the left ventricle through the delivery sheath 5 through femoral artery puncture. The inflow window at the distal end of the single-lumen catheter 1 is located in the left ventricle. The one-way valve assembly 2 is located in the ascending aorta. Under the action of the extracorporeal control system 4, the flexible membrane is driven to reciprocate, and the volume of the blood chamber changes reciprocatingly, so that blood is axially sucked into the blood chamber through the one-way valve assembly, and then discharged laterally to the ascending aorta through the catheter and the valve, thereby assisting the heart in completing blood circulation.

[0064] Reference Figure 1 , Figure 3-6 As shown, the method for calculating the working pressure of the pulsatile blood pump of the present invention comprises the following steps:

[0065] (1) Obtain working parameters and dimensional parameters based on the technical principle and structure of the pulsatile blood pump.

[0066] In the embodiment of the present invention, the working parameters of the pulsating blood pump include the auxiliary flow rate Q, the pulsating frequency f, the time a for the diaphragm cavity to absorb blood once, and the time b for the diaphragm cavity to discharge blood once; the size parameters include the first catheter length l1, the second catheter length l2, the catheter inner cavity cross-sectional area S1, the diaphragm cavity catheter joint inner cavity cross-sectional area S2, the valve channel area S3 when blood is absorbed into the blood cavity, the valve channel area S4 when blood is discharged to the ascending aorta, the projection area S5 of the blood flow direction in the diaphragm cavity, and the left ventricular inner cavity cross-sectional area S6.

[0067] (2) Based on the working parameters obtained in step (1), calculate the time it takes for blood to be sucked from the left ventricle into the membranous cavity and the time it takes for blood to be discharged from the membranous cavity to the ascending aorta in a single cycle.

[0068] When the pulsatile pump is actually working, the volume of the blood chamber changes repeatedly at a certain frequency, periodically sucking blood from the left ventricle into the blood chamber and then discharging the blood to the ascending aorta. Each cycle includes the above two processes. According to the working frequency f of the pulsatile pump and the time ratio a / b of the diaphragm chamber to absorb and discharge blood, the time for blood to be absorbed from the left ventricle into the diaphragm chamber and the time for blood to be discharged from the diaphragm chamber to the ascending aorta in a single cycle of the blood pump is calculated as follows:

[0069]

[0070] Wherein, t1 represents the time for a single circulation of blood to be sucked from the left ventricle into the membranous cavity, and t2 represents the time for a single circulation of blood to be discharged from the membranous cavity to the ascending aorta.

[0071] (3) Calculating the blood flow rate at different positions along the process of blood being sucked into the membrane cavity and blood being discharged into the ascending aorta based on the working parameters and dimensional parameters obtained in step (1) and the time obtained in step (2).

[0072] like Figure 3 , 4 As shown, in the process of blood being sucked from the left ventricle into the diaphragm cavity in the embodiment of the present invention, the blood reaches the inside of the diaphragm cavity through the left ventricle, the catheter, the valve assembly, and the catheter connector. The flow rate of blood at different positions along the way is different. The flow rate at different positions is calculated by the target flow rate Q, the frequency f, the single suction time, and the cross-sectional area of ​​the local position. The calculation formula is as follows:

[0073]

[0074] Among them, v i It represents the blood flow velocity at different positions from the left ventricular cavity to the membrane cavity connector, S j It represents the cross-sectional area from the left ventricular lumen to the different positions of the membrane-type luminal catheter connector.

[0075] v1=F1(S1) represents the blood flow rate in the catheter during the process of blood being sucked into the membrane cavity.

[0076] v2 = F1 (S2) represents the blood flow rate in the membrane cavity catheter connector during the process of blood being sucked into the membrane cavity,

[0077] v3 = F1 (S3) represents the blood flow rate inside the valve during the process of blood being sucked into the diaphragm cavity.

[0078] v4=F1(S6) represents the blood flow rate in the inner cavity of the left ventricle during the process of blood being sucked into the membrane cavity.

[0079] Reference Figure 4 The left ventricular cavity cross-sectional area S6 is determined according to the left ventricular short-axis cross-sectional area at the end of the left ventricular isovolumetric relaxation period.

[0080] like Figure 5 As shown, in the process of blood being discharged from the diaphragm cavity to the ascending aorta in the embodiment of the present invention, the high-pressure blood inside the diaphragm cavity enters the catheter through the catheter connector, and then is laterally pumped to the aorta through the valve assembly. The flow rate of blood at different positions along the way is different, and the calculation formula is as follows:

[0081]

[0082] Among them, v k Indicates the blood flow rate from the inside of the membrane cavity to different positions of the valve outlet, S j Indicates the cross-sectional area at different positions from the inner cavity of the diaphragm chamber to the valve outlet.

[0083] v5 = F2 (S1) represents the blood flow rate in the catheter during the process of blood discharge to the ascending aorta,

[0084] v6 = F2 (S2) represents the blood flow rate in the membrane-type lumen catheter connector during the process of blood being discharged into the ascending aorta.

[0085] v7=F2(S4) represents the blood flow rate of the valve outlet during the blood discharge to the ascending aorta.

[0086] v8=F2(S5) represents the blood flow rate in the membranous cavity during the process of blood being discharged into the ascending aorta.

[0087] Reference Figure 6 , 7 The projection area S5 of the blood flow direction in the membrane cavity is determined according to the maximum projection area of ​​the flexible membrane in the moving direction.

[0088] (4) Based on the blood flow rate obtained in step (3), calculate the pressure loss along the catheter and the local pressure loss during the process of blood being sucked into the diaphragm cavity and the process of blood being discharged into the ascending aorta.

[0089] The pulsating pump of the embodiment of the present invention drives blood through the pressure difference among the blood chamber, the left ventricle and the aorta. When the gas chamber is at low pressure or negative pressure, blood is sucked from the left ventricle into the blood chamber. When the gas chamber is at positive pressure, the flexible membrane is pushed to move and the blood is discharged from the blood chamber to the ascending aorta. When calculating the working pressure of the membrane chamber, the pressure loss caused by the flow of blood inside the device must be considered, including the pressure loss along the entire catheter and the local pressure loss.

[0090] During the process of blood being sucked from the left ventricle into the membrane cavity, the pressure loss along the catheter and the local pressure loss are calculated using the following formula:

[0091]

[0092]

[0093] Among them, p f1 is the pressure loss along the catheter during the process of blood being sucked into the membrane cavity, p j1 It represents the local pressure loss of the catheter during the process of blood being sucked into the membrane cavity, and ρ represents the blood density of 1055 kg / m 3 , λ is the loss coefficient along the way, d is the inner diameter of the catheter, ξ1 represents the energy loss coefficient of blood entering the valve, ξ2 represents the energy loss coefficient of blood flowing out of the valve, and ξ3 represents the energy loss coefficient of blood flowing into the catheter connector.

[0094] When blood is discharged from the membranous cavity to the ascending aorta, the pressure loss along the catheter and the local pressure loss are calculated as follows:

[0095]

[0096]

[0097] Among them, p f2 is the pressure loss along the catheter during the discharge of blood into the ascending aorta, p j2 is the local pressure loss of the catheter during the process of blood being discharged into the ascending aorta, ξ4 represents the energy loss coefficient of blood entering the catheter through the catheter connector, and ξ5 represents the energy loss coefficient of blood flowing through the outflow valve.

[0098] The along-the-line loss coefficient λ and the local loss coefficient ξ of the embodiment of the present invention are determined through experiments.

[0099] (5) Based on the law of conservation of energy, calculate the minimum working pressure of the diaphragm cavity during the process of blood being absorbed into the diaphragm cavity and the maximum working pressure of the diaphragm cavity during the process of blood being discharged into the ascending aorta.

[0100] In the embodiment of the present invention, the extracorporeal pump of the pulsatile blood pump adopts a capacity control mode, and the working pressure in the diaphragm cavity is related to the flow rate, local pressure loss, left ventricular pressure and aortic pressure.

[0101] In the process of blood being sucked from the left ventricle into the diaphragm cavity, the formula for calculating the minimum working pressure of the diaphragm cavity is as follows:

[0102]

[0103] When blood is discharged from the diaphragm cavity to the ascending aorta, the formula for calculating the maximum working pressure of the diaphragm cavity is as follows:

[0104]

[0105] Among them, P1 is the minimum working pressure when blood is sucked into the diaphragm cavity, P2 is the maximum working pressure when the diaphragm cavity discharges blood, LVP is the left ventricular pressure, AOP is the aortic pressure, and y is the safety factor.

[0106] Reference Figure 8 In the left ventricular pressure curve, the left ventricular pressure is the lowest at the end of the left ventricular isovolumetric relaxation period. The blood cavity needs a lower pressure to meet the flow output requirements. This is the most difficult working condition for blood to be sucked from the left ventricle into the blood cavity. The LVP value range is 0-10mmHg. Preferably, LVP is 0mmHg. Figure 8 The middle aortic pressure curve shows that the aortic pressure is the highest at the end of the rapid ejection period, and the blood cavity needs to provide a greater pressure. At this time, it is the most difficult condition for blood to be discharged from the blood cavity to the ascending aorta. The AOP value range is 100-140 mmHg. Preferably, the AOP is 140 mmHg.

[0107] The embodiment of the present invention reflects the influence of the hemodynamic effect and the time interval between the contraction and expansion of the flexible membrane on the working pressure through the safety factor y, and the value range is 1-1.2. Preferably, y is 1.2 to further ensure the reliability of the calculation.

[0108] Through this calculation method, R&D personnel can quickly calculate the working pressure required to meet the flow output based on the design parameters of the pulsatile blood pump, which is helpful to guide the optimization and iteration of product structure, such as the optimal design of catheter diameter, valve channel size and membrane cavity volume, and can guide the development of pump control systems.

Claims

1. A method for calculating the working pressure of a pulsatile blood pump, characterized in that: The pulsatile blood pump comprises a single-lumen catheter, a valve assembly, an extracorporeal membrane cavity and an extracorporeal control system; the single-lumen catheter comprises a distal first catheter and a proximal second catheter, the distal end of the first catheter is provided with an inflow window, and the first catheter and the second catheter are connected via a one-way valve assembly; the extracorporeal membrane cavity comprises two independent upper and lower blood cavities and gas cavities, the two cavities are separated by a flexible membrane, the gas cavity is connected to the extracorporeal control system via a tracheal joint, and the blood cavity is connected to the second catheter via a catheter joint; the calculation method comprises the following steps: (1) Obtaining working parameters and dimensional parameters based on the technical principle and structure of the pulsatile blood pump; (2) calculating the time for blood to be sucked into the membranous cavity from the left ventricle and the time for blood to be discharged from the membranous cavity to the ascending aorta in a single cycle according to the working parameters obtained in step (1); (3) calculating the blood flow rate at different positions along the process of blood being sucked into the membrane cavity and blood being discharged into the ascending aorta according to the working parameters and size parameters obtained in step (1) and the time obtained in step (2); (4) based on the blood flow rate obtained in step (3), calculating the pressure loss along the catheter and the local pressure loss during the blood absorption into the membrane cavity and the blood discharge into the ascending aorta; (5) Based on the law of conservation of energy, calculate the minimum working pressure of the diaphragm cavity during the process of blood being absorbed into the diaphragm cavity and the maximum working pressure of the diaphragm cavity during the process of blood being discharged into the ascending aorta.

2. The method for calculating the working pressure of a pulsatile blood pump according to claim 1, characterized in that: When the pulsatile blood pump is in use, the inflow window of the first catheter is located in the left ventricle, the one-way valve assembly is located in the ascending aorta, and the extracorporeal control system periodically provides positive and negative pressures. When negative pressure occurs, blood is sucked from the left ventricle into the blood cavity, and when positive pressure occurs, blood is laterally pumped from the blood cavity to the ascending aorta through the one-way valve assembly.

3. The method for calculating the working pressure of a pulsatile blood pump according to claim 2, characterized in that: The working parameters include auxiliary flow Q, pulsation frequency f, single blood suction time a of the diaphragm cavity, and single blood discharge time b; the size parameters include first catheter length l1, second catheter length l2, catheter lumen cross-sectional area S1, diaphragm cavity catheter connector lumen cross-sectional area S2, valve channel area S3 when blood is sucked into the blood cavity, valve channel area S4 when blood is discharged to the ascending aorta, projection area S5 of blood flow direction in the diaphragm cavity, and left ventricular lumen cross-sectional area S6.

4. The method for calculating the working pressure of a pulsatile blood pump according to claim 3, characterized in that: In step (2), the calculation formula for the time for a single cycle of blood to be sucked from the left ventricle into the membrane cavity is: The calculation formula for the time it takes for blood to be discharged from the membranous cavity to the ascending aorta in a single cycle is: Wherein, t1 represents the time for a single circulation of blood to be sucked from the left ventricle into the membranous cavity, and t2 represents the time for a single circulation of blood to be discharged from the membranous cavity to the ascending aorta.

5. The method for calculating the working pressure of a pulsatile blood pump according to claim 4, characterized in that: In the step (3), during the process of blood being sucked from the left ventricle into the membrane cavity, the calculation formula for the blood flow rate at different positions along the left ventricular inner cavity to the membrane cavity catheter connector is: Among them, v i It represents the blood flow velocity at different positions from the left ventricular cavity to the membrane cavity connector, S j It indicates the cross-sectional area at different positions from the left ventricular lumen to the membrane-type luminal catheter connector; v1=F1(S1) represents the blood flow rate in the catheter during the process of blood being sucked into the membrane cavity. v2 = F1 (S2) represents the blood flow rate in the membrane cavity catheter connector during the process of blood being sucked into the membrane cavity, v3 = F1 (S3) represents the blood flow rate inside the valve during the process of blood being sucked into the diaphragm cavity. v4=F1(S6) represents the blood flow rate in the left ventricular cavity during the process of blood being sucked into the membrane cavity; In the process of blood being discharged from the membranous cavity to the ascending aorta, the formula for calculating the blood flow rate at various locations along the way from the inner cavity of the membranous cavity to the valve outlet is as follows: Among them, v k Indicates the blood flow rate from the inside of the membrane cavity to different positions of the valve outlet, S j Indicates the cross-sectional area at different positions from the inner cavity of the diaphragm chamber to the valve outlet; v5 = F2 (S1) represents the blood flow rate in the catheter during the process of blood discharge to the ascending aorta, v6 = F2 (S2) represents the blood flow rate in the membrane-type lumen catheter connector during the process of blood being discharged into the ascending aorta. v7=F2(S4) represents the blood flow rate of the valve outlet during the blood discharge to the ascending aorta. v8=F2(S5) represents the blood flow rate in the membranous cavity during the process of blood being discharged into the ascending aorta.

6. The method for calculating the working pressure of a pulsatile blood pump according to claim 5, characterized in that: The left ventricular lumen cross-sectional area S6 is determined according to the left ventricular short-axis cross-sectional area at the end of the left ventricular isovolumetric relaxation period, and the projection area S5 in the blood flow direction of the membrane cavity is determined according to the maximum projection area of ​​the flexible membrane in the moving direction.

7. The method for calculating the working pressure of a pulsatile blood pump according to claim 5, characterized in that: In the step (4), during the process of blood being sucked from the left ventricle into the membrane cavity, the calculation formulas for the pressure loss along the catheter and the local pressure loss are as follows: Among them, p f1 is the pressure loss along the catheter during the process of blood being sucked into the membrane cavity, p j1 It represents the local pressure loss of the catheter during the process of blood being sucked into the membrane cavity, and ρ represents the blood density of 1055 kg / m 3 , λ is the loss coefficient along the way, d is the inner diameter of the catheter, ξ1 represents the energy loss coefficient of blood entering the valve, ξ2 represents the energy loss coefficient of blood flowing out of the valve, and ξ3 represents the energy loss coefficient of blood flowing into the catheter connector; When blood is discharged from the membranous cavity to the ascending aorta, the calculation formula for the pressure loss along the catheter and the local pressure loss is as follows: Among them, p f2 is the pressure loss along the catheter during the discharge of blood into the ascending aorta, p j2 is the local pressure loss of the catheter during the process of blood being discharged into the ascending aorta, ξ4 represents the energy loss coefficient of blood entering the catheter through the catheter connector, and ξ5 represents the energy loss coefficient of blood flowing through the outflow valve.

8. The method for calculating the working pressure of a pulsatile blood pump according to claim 7, characterized in that: The along-the-way loss coefficient λ and the local loss coefficient ξ are determined through experiments.

9. The method for calculating the working pressure of a pulsatile blood pump according to claim 7, characterized in that: In the step (5), during the process of blood being sucked from the left ventricle into the diaphragm cavity, the minimum working pressure inside the diaphragm cavity is calculated as follows: When blood is discharged from the diaphragm cavity to the ascending aorta, the maximum working pressure inside the diaphragm cavity is calculated as follows: Among them, P1 is the minimum working pressure when blood is sucked into the membrane cavity, P2 is the maximum working pressure when the membrane cavity discharges blood, LVP is the left ventricular pressure, AOP is the aortic pressure, and γ is the safety factor.

10. The method for calculating the working pressure of a pulsatile blood pump according to claim 9, characterized in that: The LVP is determined according to the left ventricular pressure at the end of isovolumetric relaxation, with a value range of 0-10 mmHg; the aortic pressure AOP is determined according to the aortic pressure at the end of the rapid ejection phase, with a value range of 100-140 mmHg; The safety factor γ takes into account the influence of the hemodynamic effect and the time interval between the contraction and expansion of the flexible membrane on the working pressure, and has a value range of 1-1.2.

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