RU2732084C1 - Artificial heart - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medical equipment, namely to extracorporeal and implantable devices of mechanical support of blood circulation. Artificial heart comprises left and right rotary pumps. Each pump is connected to the pump control unit, which provides the specified pump rotation speed constant. Inlet line of each pump comprises actuator made in the form of controlled active hydraulic resistance with drive connected to drive control unit including frequency and duty cycle unit of operation of actuators. Drive control unit has the possibility of regulating blood flow at the pump outlet, providing pulsation of the blood flow and pressure due to complete opening and partial overlapping of the lumen of the inlet main line.

EFFECT: technical result is to create a physiological pulsatile flow and pressure in the aorta and pulmonary artery at a constant preset speed of the impeller of the left and right pumps.

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Description

The invention relates to medical technology, namely to extracorporeal and implantable mechanical circulatory support devices (BMC) based on the use of rotary blood pumps (RN) or non-pulsating flow pumps.

TECHNOLOGY LEVEL

The BMD method using RN, built on the principle of centrifugal, axial and roller devices, has taken the leading direction (94%) in the world clinical practice for the treatment of patients with terminal heart failure (TSF). This is due to the significant advantages of these pumps in comparison with pulsating pumps, due primarily to their small size, high energy efficiency, greater reliability and service life. This technology is successfully used in isolated left ventricular failure with a high patient survival rate (85% in the first year of implantation).

However, in more than 30% of cases, patients with TSF have bilateral heart failure and the survival rate of these patients is much lower. Therefore, the solution to this problem is either biventricular bypass or implantation of an artificial heart (IC) (Sunagawa G, Horvath DJ, Karimo JH, Moazami N. et al. Future Prospects for the Total Artificial Heart // J Expert Review of Medical Device. 2016. pp: l-29).

Currently, in clinical practice, the only pulsating IC device is SynCardia TAN (CardioWest Inc), which is two pulsating implantable artificial heart ventricles with external electric pneumatic drives and a power supply system. The widespread introduction of this technology in clinical practice was limited by the same drawbacks, which put into the background the system of mechanical support of blood circulation using volumetric pulsating pumps: lower reliability and resource, relatively large dimensions of the IC, which did not allow the creation of a fully implantable IC system.

The clinical use of the Abioco ™ TAN (Abiomed Inc) implantable electromechanical pulsating IC has been limited to a few cases. One of the reasons for this was the high cost of the system and the relatively low reliability and resource. Therefore, in recent years, the attention of IS developers has been directed to the use of LV, due to their advantages over pulsating flow pumps. In this case, the right and left LV could be located in the same housing and be driven by one contactless DC motor. Equally important is the lower cost of such an IP.

The first applications as an implantable IS of two RNs, which operated in a non-pulsating mode, creating a non-physiological non-pulsating flow in the body, also did not receive clinical implementation.

Known device IS (US 2014172087 A1) of the centrifugal type, the rotor of the electric motor which rotates two impellers to supply blood to the large and small circle of blood circulation.

Known device IS (US 2013331934 A1) of the centrifugal type. The device has an impeller on one side of the impeller and, accordingly, an impeller on the other side of the impeller. This invention describes a method for controlling the system and the design of the impeller for the left and right channels, taking into account the differences in the peripheral resistance of the systemic and pulmonary circulation.

Known IC device (US 9192702 B2), which discloses the technology of IC control using an embedded microcontroller, which regulates the speed of the motor in response to hemodynamic changes in blood pressure during physical activity of the patient.

Known device IS (US 8870951 B1), which provides automatic regulation of blood flows for the left and right pumps and maintains the pressure balance by minimizing pressure gradients using high sensitivity of blood flow to pressure in the PH.

Described are other LV systems that can be used for ICs with modulation of the impeller rotation speed (US 2011178361 A1, US 9579435 B2, US 9345824 B2).

The disadvantages of pumps with modulation of the impeller rotation speed are associated with the fact that the amplitude of the generated flow pulses is limited due to the inertia of the drive. In addition, the variable rotor speed of the pumps increases the in-pump shear stress, which increases the likelihood of injury to the blood in the pump. In addition, for use in these systems as ICs of LV structures, previously developed for left ventricular bypass, a significant reworking of pump control units is required.

As a prototype, we have chosen an IC, which is described in RU 2665179. The proposed IC contains a left and right LV, each of which is connected to a pump control unit, which maintains a given constant rotation speed of the pump impeller. To each of the pumps in parallel to the input and output lines with the help of tees is connected a channel of controlled blood circulation, containing a valve connected to a control unit, including a unit for setting the frequency and duty cycle. The valve control unit, by means of a hydraulic resistance, has the ability to independently regulate the blood flow in each recirculation channel, with the ability to partially overlap and open its lumen.

Despite the efficiency of this system in terms of generating a pulsating flow, its main disadvantage is the need to introduce an additional recirculation loop with inlet and outlet tees, which increases the contact area of blood with a foreign surface and can be an additional source of thrombus formation and blood trauma. In addition, the blood flow in the recirculation loop is not involved in the total circulation of blood circulation, which leads to the need to increase the total volume of blood pumped by the pump and, as a result, can lead to additional blood trauma. A controlled valve installed in the recirculation channel, when closed, requires a relatively large power to operate and maintain a given gap under conditions of relatively high blood pressure, which, together with the introduction of additional recirculation circuits into the design, limits the possibility of creating an implantable IC system based on this design.

SUMMARY OF THE INVENTION

An artificial heart is proposed, which contains left and right rotary blood pumps, each of which is connected to a pump control unit, which provides a given speed of rotation of the pump impeller constant. The input line of each pump contains an actuator made in the form of a hydraulic resistance with a drive connected to the drive control unit, which includes a unit for setting the frequency and duty cycle of the actuators. In this case, the drive control unit has the ability to regulate the blood flow at the outlet of each rotary pump, providing pulsation of the blood flow due to the complete opening and partial blocking of the lumen of the inlet line.

Actuators can use electromechanical, electro-pneumatic or electro-hydraulic actuators.

Thus, the input line of each pump contains an actuator made in the form of a variable hydraulic resistance with a drive connected to the drive control unit.

The hydraulic filter with the help of the actuator drive partially blocks or opens the lumen of the inlet lines of the left and right pumps. The drive control unit determines the frequency and duty cycle of the actuator drive and, accordingly, the frequency and duty cycle of blood flow pulses at the output of each pump.

Thus, a pulsating flow is generated at the output of the left and right rotary IC pump, which determines the pulse pressure in the aorta and pulmonary artery.

The peculiarity of the inclusion of actuators in the inlet lines of the pumps is that the main energy for the functioning of the actuator is spent at the moment of low pressure at the inlet of the left and right IS pumps (in the artificial atria). Therefore, the energy intensity of the active controlled resistance is quite low, which will significantly reduce its weight, dimensions and energy characteristics for the implementation of the implantable IC version.

The technical result achieved by the implementation of the present invention consists in:

- reducing the area of a foreign contact surface, potentially dangerous for thrombus formation and blood trauma, and simplifying the IC design;

- reducing the energy costs required for the operation of the system, which allows, while simplifying the design of the IC pulsator, to reduce the weight and dimensions for the implementation of a fully implantable IC;

- creation of a physiological pulsating flow and pressure in the aorta and pulmonary artery at a constant set speed of the impeller of the left and right IS pumps;

- improvement of intra-pump hydrodynamics due to the generation of a pulsating flow in the right and left IS pumps without changing the pump rotor speed, which is especially critical for the right IS pump in terms of reducing the likelihood of thrombosis in it.

- prevention of conditions for the appearance of a dangerous rarefaction mode and regurgitation in the diastolic phase at increased pump rotor speed;

- the possibility of implementing IS based on previously developed implantable designs of rotary pumps designed for left ventricular bypass.

BRIEF DESCRIPTION OF DRAWINGS

The essence of the invention is illustrated in the figures, where:

in fig. 1 shows a diagram of the proposed IC providing the generation of a pulsating flow in the left and right LV IC;

in fig. 2 shows a diagram of pressures and flow rates for the systemic and pulmonary circulation, obtained on a two-circle hydrodynamic stand, when the left and right LV IS in non-pulsating mode without the LV system - actuator (A);

in fig. 3 shows a diagram of pressures and flow rates for the systemic and pulmonary circulation, obtained on a two-circle hydrodynamic stand, when the left and right LV IS in a pulsating mode using the installation of the RN-A system in the inlet line.

The figures indicate the following positions: 1 - left PH for replacing the left ventricle, 2 - PH for replacing the right ventricle, 3 - hydraulic resistance at the inlet of the left PH, 4 - hydraulic resistance at the inlet of the right PH, 5 - drive A of the left PH, 6 - drive A of the right PH, 7 - A of the left PH, 8 - A of the right PH, 9 - control unit for actuator drives, 10 - input line of the left PH, 11 - input line of the right PH, 12 - artificial left atrium, 13 - artificial right atrium, 14 - aorta, 15 - pulmonary artery, 16 - pump control unit, P _ad - pressure in the aorta, P _la - pressure in the pulmonary artery, Q _ao - flow rate in the aorta, Q _la - flow rate in the pulmonary artery.

DISCLOSURE OF THE INVENTION

Using the example of the connection diagram of the left and right LV shown in Fig. 1, we will consider the principle of pulse blood flow generation in IC.

The patented device (Fig. 1) contains a left and right 1.2 PH (axial or centrifugal) with a pump control unit 16, which determines the set speed of rotation of the impeller of each pump. In the input lines of the left and right PH 10.11, A 7 and 8 are installed, respectively. Each A contains a variable hydraulic resistance: A 7 of the left PH contains a hydraulic resistance 3 and its own drive 5; A 8 of the right PH contains a hydraulic resistance 4 and its own drive 6. In this case, the drives 5 and 6 of each actuator 7 and 8 are connected to the drive control unit 9. The latter provides a given frequency and duty cycle of the output pulses of flow and blood pressure at the output of the left PH 1 and the right PH 2.

To implement the IS mode, the input and output of the right PH 2 are connected extracorporeally or intracorporeally according to the "artificial right atrium - pulmonary artery" scheme, and the left PH 1 according to the "artificial left atrium - aorta" scheme.

The drive control unit 9 provides full opening and partial overlap of the input lines 10 and 11 of the left PH 1 and right PH 2. Accordingly, the pulse flow is formed at the pump outlet and, consequently, the physiological pulse flow and pressure in the arterial reservoirs of the systemic and pulmonary circulation.

The input line 10 of the left RN 1 is connected to the left artificial atrium 12, and the input line 11 of the right RN 2 is connected to the right artificial atrium 13.

The output line of the left PH 1 (not indicated in the figures) is connected to the aorta 14; the output line of the right PH 2 (not indicated in the figures) is connected to the pulmonary artery 15.

In the phase of generation of an increased amplitude of the output flow of pumps (systole) A 7 and A 8 completely open the lumens of the input lines for the left 1 and right 2 PH, and in the phase of generation of a reduced amplitude of the output flow of the pumps (diastole) A 7 and A 8 partially overlap the lumens of the input highways.

Thus, the control unit for drives A 9 provides the set frequency and duration of the flow and pressure pulses for the left and right PH 1 and 2, respectively.

To confirm the possibility of realizing the declared purpose and achieving the specified technical result, we present the following experimental data obtained on a two-circle hydrodynamic stand.

Rotaflow centrifugal pumps (Maquet AEG, Germany) with a capacity of 5 l / min were used as pumps on the hydrodynamic stand. The aortic and pulmonary reservoirs, mimicking the aorta and pulmonary artery, are containers filled with fluid with an air cushion, which determine the elasticity of the vessels of the aortic and pulmonary reservoirs (for the pulmonary artery, the elasticity is 5.7 ml / mm Hg and for the aorta the elasticity of the aortic reservoir is 2 ml / mm Hg). Hydraulic resistance was used as peripheral resistance (for the pulmonary circulation 0.4 mm Hg / ml / s and for the systemic circulation 1.2 mm Hg / ml / s). The left and right atria are containers open to the atmosphere. Taking into account the bronchial discharge, the average fluid flow in the left canal was set at 0.1-0.2 l / min more than the fluid flow in the right canal by. In an IC operating environment, this cost difference is necessary to prevent pulmonary edema.

Thus, as shown by studies on a hydrodynamic stand, the operation of the proposed IC using the RN-A system creates conditions for the generation of a pulsating flow in the large and small circles of blood circulation.

For comparison, FIG. 2 shows a diagram of pressures and flow rates of fluid in the large and small circles of blood circulation during the operation of the RN in a non-pulsating mode. The obtained effect of the operation of the IS system using the RN-A systems is shown in the diagram (Fig. 3). As can be seen from this diagram, in simulators of the aorta and pulmonary artery, physiological pulsating pressure is created in the aorta (pressure in the aortic reservoir 111/76 mm Hg) and pulmonary artery (pressure in the pulmonary reservoir 19/13 mm Hg) during pulsation fluid flow in the systemic circulation ΔQ _l = 6.9 l / min and ΔQ _p = 8.8 l / min in the pulmonary circulation, which contributes to the creation of conditions for intra-pump hydrodynamics, preventing the formation of stagnation and recirculation zones in the cavities of the left and right PH.

Claims (2)

1. An artificial heart containing left and right rotary blood pumps, each of which is connected to a pump control unit, which provides a given speed of rotation of the pump impeller constant; the input line of each rotary pump contains an actuator made in the form of a controlled active hydraulic resistance with a drive connected to the drive control unit, including the unit for setting the frequency and duty cycle of the actuators, while the drive control unit has the ability to regulate the blood flow at the output of each rotary pump, providing pulsation of the blood flow due to the complete opening and partial blocking of the lumen of the inlet line. 2. An artificial heart according to claim 1, wherein electromechanical, electro-pneumatic or electro-hydraulic drives are used.

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