RU2665178C1 - Device and method for controlling the blood flow of rotary pumps - Google Patents

Abstract

FIELD: medicine.SUBSTANCE: group of inventions relates to medical technology, namely to extracorporeal and implantable devices, methods of mechanical circulation support, based on the use of non-pulsating flow pumps. Mechanical circulation support system includes at least one non-pulsed flow pump with a pump control unit to maintain a constant rotational speed of the impeller of the pump, and a channel for controlled recirculation of blood connected parallel to the pump from one side to the inlet of the pump's main line and, on the other, to the outlet part of the pump's main line. Channel is provided with a valve that is connected to the valve control unit containing the cardiosynchronization unit. Cardiosynchronization unit is configured to control the flow of blood with partial or complete overlap and opening the lumen of the channel for controlled recirculation of blood in accordance with the phases of the cardiac cycle in the modes of pulsation or counterpulsation with the heart of the patient. Methods for the mechanical support of blood circulation using the system are disclosed.EFFECT: technical result consists in improving intra-pump hemodynamics and minimizing blood trauma, recirculation and stagnation zones.10 cl, 1 tbl, 3 dwg

Description

FIELD OF TECHNOLOGY

This invention relates to medical equipment, namely to extracorporeal and implantable devices for mechanical support of blood circulation (MPC), based on the use of rotary pumps or non-pulsating flow pumps (NNP), can be used during auxiliary blood circulation.

BACKGROUND

The IPC method using non-pulsating flow pumps (NPS), built on the principle of centrifugal and axial devices, has taken a leading direction (94%) in the global clinical practice for the treatment of patients with terminal heart failure (TSN). This is due to the significant advantages of these pumps compared to pulsating pumps, due primarily to their small size, high energy efficiency, greater reliability and resource.

Along with fairly optimistic forecasts for the use of this technology, the extensive clinical practice of using NNP has revealed a number of shortcomings that require a review of their management strategy.

In almost all clinical IPC systems built on the basis of implantable NNP, the main control strategy is based on maintaining the operator's speed of the pump rotor. At the same time, a pulsating flow is formed at the pump outlet.

As shown by numerous clinical studies, an increase in pump speed is accompanied by non-surgical bleeding, valve problems, and a decrease in myocardial unloading compared to pulsating pumps. It is known that sufficient, adequate myocardial unloading is the main factor in restoring the contractility of one’s own myocardium.

The use of NNP in the mode of increased revolutions of the pump rotor, necessary to maintain systemic circulation, often leads to a rarefaction at the pump inlet, which can lead to tissue damage in the cannula, displacement of the interventricular septum, impaired right ventricular function, arrhythmia, cardiac ischemia and hemolysis.

On the other hand, the lower limit of the rotational speed of the NNP rotor is the regime in which the conditions of regurgitation of blood flow from the aorta to the LV arise in the diastolic phase, which creates unfavorable conditions for filling the right ventricle and, ultimately, leads to right ventricular failure. Another negative phenomenon associated with the use of NNP is the likelihood of developing aortic valve insufficiency (AK) due to the high transvalvular gradient, which affects the structure of cells and, ultimately, leads to the formation of adhesions, incomplete opening and thrombosis of AK.

To solve this complex of problems, a concept was proposed for converting the mode of setting constant RPE to a mode of generating pulsating pulses synchronized with the work of your own heart (l. Pirbodaghi T, Asgari S. Cotter C. Physiologic and hematologic concerns of rotary blood pumps: what needs to be improved? // Heart Fail Rev 2014; 19: 259-266; Rotary pumps and diminished pulsatility: do we need a pulse? ASAIO J. 2013 Jul-Aug; 59 (4): 355-66; Kishimoto S, Date K, Arakawa M, Takewa Y, Nishimura T, Tsukiya T et al. Influence of a novel electrocardiogram-synchronized rotational-speed-change system of an implantable continuous-flow left ventricular assist device (EVAHEART) on hemolytic performance. J Artif Organs. 2014; 17 (4): 373-377).

The implementation of this concept in known systems is based on providing a pulsating mode due to the modulation of the RPM engine speed.

A device is known (US 7850594, B2), which contains a rotary pump with a drive providing a pulsating pump mode synchronously with the work of the heart. Moreover, the cardiac cycle is determined from the ripple index of the back EMF of the non-contact DC motor.

A device is known (WO 2009150893, A1), which consists of a detector for the outgoing signals of the heart cycle, a rotary pump control unit that controls the rotor speed synchronized with the heart cycle.

An implanted rotary pump connected to the body according to the “ventricle-artery” scheme (US 2017080138, A1) is described. The device includes a pump drive and a sensor for electrophysiological signals, such as an electrogram. In this case, the sensor is connected to the pump drive to control it cardiosynchronized in the mode of pulsation and counterpulsation. Getting the heart cycle in this case is based on averaging two or more heart cycles.

Other MPC systems using NNP with cardiosynchronized modulation of the impeller rotation speed are described (US 9579435, B2; US 9345824, B2).

As a prototype, we have chosen a device and method for controlling NNP in the IPC system described in US 8864644, B2. The prototype device contains an auxiliary pump of a rotary type, connected according to the scheme of the ventricle-artery. The device includes a drive, which for synchronization with the cardiac cycle periodically changes the frequency of rotation of the pump rotor according to the signals received from the electrogram sensor.

The disadvantage of the above devices, including the prototype, is the periodic change in the speed of rotation of the impeller of the pump synchronized with the frequency of the heart cycle, which can lead to blood injury.

In addition, the inertia of the engine-pump system reduces the efficiency of the heart pump. These devices are not universal and their implementation requires substantial refinement of the control units of the existing MPC systems using NNP (axial and centrifugal pumps).

SUMMARY OF THE INVENTION

An IPC system is proposed, including at least one pump NNP with a pump control unit that maintains a constant speed of rotation of the impeller of the pump, and a channel for adjustable blood recirculation. The latter is connected in parallel with the input and output lines of the pump and is equipped with a valve that is connected to the valve control unit, which receives signals from the cardiosynchronization unit. The latter is made with the possibility of regulating the blood flow with partial or complete closure and opening of the lumen of the blood recirculation channel in accordance with the phases of the cardiac cycle in the modes of pulsation or counterpulsation with the patient's heart.

The adjustable blood recirculation channel is connected to the input and output lines of the pump through the first and second tees, respectively, while the input of the first tee is connected to the input line of the ventricle of the heart or the left atrium, and the output of the second tee is connected to the artery.

The adjustable blood recirculation channel is made in the form of an elastic tube or vascular prosthesis.

In the IPC system, an electromechanical valve can be used.

The cardiac synchronization unit can be connected to an ECG recording unit or a cardioverter.

The cardiosynchronization unit can be connected to the pump control unit with the possibility of receiving signals from the reverse electromotive force (EMF) of the pump control unit.

In the MPC system, a mechanical valve can be used, which works according to the pressure drop at the inlet and outlet of the channel for controlled blood recirculation, so that during the systole the valve is closed, and during diastole it is open, realizing a mode of heart pulsation.

A method for mechanical support of blood circulation is also proposed, in which the IPC system is used extracorporeally or intracorporeally, connecting to the patient according to the “ventricle-artery” scheme, providing a mode of pulsation with the patient’s heart.

In the particular case, when connected according to the “left ventricle-aorta” scheme, the regime of periodically opening the channel for controlled blood recirculation can be implemented, in which at intervals of 30 seconds to 1 minute the channel for controlled blood recirculation is open for at least five cardiac cycles.

A method for mechanical support of blood circulation is proposed, in which the IPC system is connected extracorporeally or intracorporeally to the patient according to the “left atrium-aorta” scheme, providing a mode of counterpulsation with the patient’s heart.

The technical result achieved by the implementation of this group of inventions is:

- improving the internal pump hydrodynamics, minimizing blood trauma and blood recirculation and stagnation zones, which are potentially dangerous for thrombosis, by generating a pulsating flow at the outlet of the pump-shunt system without changing the speed of rotation of the pump impeller;

- reducing the work of the heart in the mode of pulsation due to the high speed compared to the pump operating modes with a periodic change in the speed of rotation of the pump rotor within the cardiac cycle;

- the universality of the proposed IPC, in which a pump of any design can be used as the basic NNP.

Thus, as a result of the proposed group of inventions, the stability of the internal pump hydrodynamics is ensured, blood trauma and thrombosis are minimized in MPC systems based on NNP due to their generation of a physiological pulsating flow at the outlet of the pump-shunt system without changing the speed of rotation of the pump impeller.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated in the figures, where

on. FIG. 1 shows a diagram of the generation of a pulsating flow in IPC systems using NNP and a shunt with a controlled valve;

in FIG. 2 shows a diagram of a single-circular hydrodynamic stand simulating a large circle of blood circulation with NNP and connecting a shunt with a valve;

in FIG. Figure 3 shows the pressure and flow diagram obtained on a hydrodynamic bench, when simulating heart failure, where - A) pump operation without a shunt, B) pump operation with a shunt (Rao - pressure in the aorta, Ppr - pressure in the atrium, Qн - flow in the pump , Qc is the system consumption.)

MODES FOR CARRYING OUT THE INVENTION

A patented device, the circuit of which is presented in FIG. 1 contains NNP 1 (axial or centrifugal), while the outlet and the inlet of the pump through the tees are connected by a fluid recirculation channel - a shunt (elastic tube or vascular prosthesis) 2 with an electromechanical valve (EM) 3 installed on it, connected to the valve control unit 4. In this case, the valve control unit 4 is connected to the cardiosynchronization unit 5, which is connected to the ECG recording unit 6.

A controlled blood recirculation channel or shunt 2 is connected to the pump using two tees, the input of the first tee is connected through the tube system to the left or right ventricle, or the left atrium, and the input of the second tee is connected through the tube system to the corresponding artery or aorta (connection according to the schemes “ left ventricle-aorta ”,“ right ventricle-pulmonary artery ”,“ left atrium-aorta ”)

In another embodiment, the cardiac synchronization unit 5 is connected to the pump control unit 7.

In a third embodiment, the cardiosynchroization unit is connected to a cardioverter (implantable pacemaker).

In the fourth embodiment, a mechanical valve is used as valve 3.

The operation of this design can be described as follows.

In the first version of connecting the system, the pump 1-shunt 2 according to the “ventricle-artery” scheme, due to the cardiosynchronization unit 5, receiving signals from the ECG recording unit 6, or the cardioverter, or by the signals of the back emf received from the pump control unit 4, to the systole valve 3 partially or completely blocks the shunt 2, increasing the blood flow at the outlet of the system, and in the diastole phase, valve 3 partially or completely opens the shunt 2, reducing the blood flow to the artery.

Thus, at the system output, pump 1-shunt 2 i.e. a pressure close to physiological pulsation is formed in the artery. At the same time, due to an increase in the blood flow to systole, the afterload of the heart ventricle, which is one of the main factors in the recovery of the myocardium, is more efficiently compared to NNP in the usual non-pulsating mode.

In addition, the mode of operation of the pump 1-shunt 2 system with a minimum blood flow to the diastole helps to eliminate dangerous conditions when the NNP is in non-pulsating mode associated with the occurrence of rarefaction at the pump inlet and reverse blood regurgitation from the artery into the ventricle.

In the second embodiment, when connecting the pump according to the “left atrium-aorta” scheme with the pump 1-shunt 2 system, valve 3 opens the blood flow through shunt 2 into the systole and closes the blood flow through the shunt into the diastole, creating conditions of increased diastolic pressure (counterpulsation mode), which contributes to an increase in coronary blood flow.

In the third option, when the NNP is turned on according to the “ventricle-aorta” scheme, a mechanical valve 3 is installed in the shunt 2, which operates according to the pressure drop at the inlet and outlet of the adjustable blood recirculation channel so that the valve is closed during systole and the valve is open during diastole, realizing the mode of ripple with your own heart.

In the option of including NNP according to the “ventricular-aorta” scheme, the valve 3 control unit provides for the mode of periodic opening of shunt 2: with a frequency of 30 seconds to 1 minute with a duration of at least 5 cardiac cycles. This mode creates the conditions for the periodic functioning of the arterial valve, which in the conditions of heart failure during NNP operation can close, while prolonged closure of the arterial valve can lead to its insufficiency.

For specialists in the field of cardiology, it should be obvious that various modifications and changes can be made to the present invention without departing from the essence or scope of the claims, which are not reflected in the above embodiments of the invention.

We present the results of an experiment confirming the possibility of implementing the stated purpose and achieving the specified technical result.

The operation of the proposed IPC system can be illustrated in FIG. 2., where the hydrodynamic stand of the circulatory system is presented, in which the input of the pump 1-shunt 2 system is connected to the simulator of the ventricle of the heart (IZHS), and the output to the aortic reservoir 8, then the total blood flow from the IZH and system 1-shunt 2 pump passes through peripheral resistance 9 and atrium 10, the output of which is connected to the input of IZHS, driven by a pneumatic actuator 11. At the same time, the working conditions of the pediatric IZHS with systemic blood flow in simulating heart failure equal to 1 l / min were reproduced.

The recirculation loop or shunt 2 is connected in parallel to the pump 1 and contains a pneumatic valve 3, which operates from the same pneumatic actuator 11.

Thus, during the systole of the IZHS, the overpressure is simultaneously supplied to the IZHS and the pneumatic valve 3 and closes the recirculation channel. In this case, pump 2 operates in the set constant rotor speed mode, and the recirculation channel (shunt 2) with pre-valve 3 into the systolic phase blocks the fluid flow through the shunt. The total flow of fluid (blood) into the aortic reservoir 7 into the systole is determined by the operation of the IZH and the pump system 1-shunt 2, which creates a relatively high blood flow in it to the systole. In this case, the amplitude of the blood flow into the aortic reservoir 8 mainly depends on the set rotational speed of the pump 2 rotor. During diastole, the pneumatic valve 3 opens, recirculating the fluid flow through the shunt and reducing the blood flow to zero in the diastole. Thus, the operation of the pump 1-shunt 2 system creates conditions for increased systolic blood flow and minimizes diastolic flow, which contributes to an increase in pulse pressure in the aortic reservoir 8 compared to standard operation of pump 1 without shunt 2. An additional effect of increased systolic blood flow through the pump system -shunt contributes to a relatively greater decrease in pressure in the ventricle of the heart (on the hydraulic stand of IZhS), i.e. more effective reduction of afterload.

The resulting effect of the operation of the pump 1-shunt 2 system is shown in the pressure and flow diagram in FIG. 3.

As can be seen from the diagram, the pulse pressure in the aorta during the operation of the pump system with the shunt 2 and valve 3 is significantly higher than the pulse pressure in the aorta during the NNP operation without the shunt 2 system and valve 3.

The fluid flow curve in the pump Qн during the operation of the pump-shunt system has a large pulsation, due to which the internal pump hydrodynamics minimizes the formation of stagnation and recirculation zones that are dangerous for thrombosis.

The curve of the systemic fluid flow into the aortic reservoir Qc is also more pulsating than when the pump was operated without a shunt,

In this work, the working conditions of the MPC systems were reproduced at the hydrodynamic bench when modeling cardiac insufficiency in children with a systemic output of 1 l / min. 6 tests were carried out using the domestic children's pump DON and pump ROTAFLOW (Germany).

The comparative data obtained at the hydraulic bench are summarized in table 1.

As can be seen from table 1, the pulsating pressure in the aortic reservoir 8 increases compared to the pump without a shunt by 1.7 times while maintaining the total flow of fluid (blood), and the pressure in the left ventricle (LV) decreases by 1.35 times, which indicates about effective unloading of LV.

Claims (10)

1. The system of mechanical support of blood circulation, including at least one non-pulsating flow pump with a pump control unit that maintains a constant speed of rotation of the impeller of the pump, and a channel for adjustable blood recirculation, connected in parallel to the pump on the one hand to the input part of the pump line, and on the other - to the output of the pump main, the channel is equipped with a valve that is connected to a valve control unit containing a cardiosynchronization unit, the latter being made with the ability to regulate blood flow with partial or complete closure and opening of the lumen of the channel for adjustable blood recirculation in accordance with the phases of the cardiac cycle in the modes of pulsation or counterpulsation with the patient's heart. 2. The system of claim 1, wherein the adjustable blood recirculation channel is configured to connect to the input and output parts of the pump line through the first and second tees, respectively, while the input of the first tee is configured to connect to the ventricle of the heart or left atrium, and the output the second tee - to the artery. 3. The system of claim 1, wherein the controlled blood recirculation channel is an elastic tube or vascular prosthesis. 4. The system of claim 1, wherein the valve is used with an electromechanical actuator. 5. The system of claim 1, wherein the cardiosynchronization unit is connected to an ECG recording unit or cardioverter. 6. The system according to claim 1, in which the cardiac synchronization unit is connected to the pump control unit with the possibility of receiving signals from the reverse electromotive force of the pump control unit. 7. The system according to claim 1, in which a mechanical valve is used, which operates according to the differential pressure at the inlet and outlet of the channel for controlled blood recirculation, so that during the systole the valve is closed, and during the diastole it is open, realizing a mode of pulsation with the patient’s heart . 8. The method of mechanical support of blood circulation, in which the system according to any one of paragraphs. 1 or 7 are used extracorporeally or intracorporeally, connecting to the patient according to the “ventricle-artery” scheme, providing a mode of pulsation with the patient’s heart. 9. The method of mechanical support of blood circulation according to claim 8, in which, when connected according to the "left ventricle - aorta" scheme, the regime of periodically opening the channel of controlled blood recirculation is implemented, in which the channel of controlled blood recirculation is open for an interval of 30 seconds to 1 minute for a period of at least five heart cycles. 10. A method of mechanically supporting blood circulation, in which the system according to claim 1 is connected extracorporeally or intracorporeally to the patient according to the “left atrium-aorta” scheme, providing a mode of counterpulsation with the patient’s heart.

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