RU2734142C1 - Device and method for biventricular bypass of heart - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: group of inventions relates to medical equipment. Biventricular cardiac bypass (BCB) system comprises left and right rotary blood pumps connected to the pump control unit. Pump control unit ensures constant rotation speed of impeller of every pump. Inlet line of each pump comprises actuator made in form of hydraulic resistance with drive connected to drive control unit. Latter includes a unit for setting frequency and duty ratio of operation of actuators. Drive control unit has the possibility of regulating blood flow at the output of each rotary pump due to complete opening or partial overlapping of the lumen of the inlet main line. Disclosed are versions of the BCB method, in which the BCB system is used. In one version, the left pump inlet line is connected to the left ventricle of the heart, and its outlet line to the aorta; an inlet main line of the right pump to the right ventricle of the heart, and its output main line to the pulmonary artery. In the alternative version, the left pump inlet line is connected to the left atrium, its exit line to the aorta, the right pump inlet line to the right atrium, and its outlet line to the pulmonary artery.

EFFECT: technical result is providing physiological pulsatile flow and pressure in aorta and pulmonary artery at constant preset speed of impeller of left and right BCB pumps, improvement of intra-pump hydrodynamics, possibility to use rotary pumps for bypass of left ventricle of heart without using additional hydraulic resistance in right pump.

4 cl, 4 dwg

Description

FIELD OF TECHNOLOGY

The invention relates to medical technology, in particular to extracorporeal and implantable mechanical circulatory support devices (MPC), based on the use of non-pulsating flow pumps (NNP).

LEVEL OF TECHNOLOGY

The IPC method with the use of NNP, built on the principle of centrifugal, axial and roller devices, has taken a 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 flow pumps (NPP), due primarily to their small size, high energy efficiency, greater reliability and resource. This technology is successfully used in isolated left ventricular failure with a high patient survival rate (85% in the first year of implantation).

The optimistic picture of the treatment of patients with TSF, however, is clouded by a rather unfavorable prognosis for the use of left ventricular bypass systems (LV) in patients with concomitant right ventricular failure (more than 30%), which significantly affects the results of this method and requires the use of biventricular cardiac bypass methods (Biofeedback).

The development of methods and means of biofeedback is directly related to work in the development of methods and means of LV LV.

Devices that can be used to provide biofeedback include:

1. Implantable pump for LV and extracorporeal pump for right ventricular bypass (RV);

2. Extracorporeal biofeedback systems based on volumetric pulsating pumps;

3. Implantable biofeedback systems based on NNP.

Currently, in clinical practice, the extracorporeal biofeedback system EXCOR (Berlin Heart AEG, Germany) is mainly used, which represents two NPP pumps with a pneumatic drive. Taking into account the instability of the heart rate in bilateral heart failure, the system does not provide for the cardiac synchronization mode. The widespread introduction of this system into clinical practice was limited due to the relatively low reliability and a large percentage of strokes caused by pump thrombosis. Despite these inherent disadvantages of GMP, this system is currently the only one approved for clinical use in the United States in young children with TSF.

With the introduction into clinical practice of new miniature pumps and, in particular, centrifugal pumps HeartWare HVAD, CoreAide, it became possible to implant them in older children. However, the use of these pumps was limited to individual cases due to thrombosis of the right pump, which is associated with the low-pulsating nature of the flow of these pumps. Nevertheless, in recent years, implantable rotary pumps have begun to be developed for both artificial hearts and biofeedbacks.

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

Known device (US 2013331934 A1) of the centrifugal type, which 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, as well as the design of the impeller for the left and right channels, taking into account the fact that the peripheral resistance of the systemic and pulmonary circulation is significantly different.

Known device (US 8870951 B1), which provides automatic regulation of the blood flow for the left and right pumps, as well as maintaining the pressure balance by minimizing pressure gradients using high sensitivity of the pH to changes in blood flow and pressure.

Described are other NNP systems that can be used for biofeedback based on the principle of modulation of the impeller rotation speed (US 2011178361 Al, US 9579435 B2, US 9345824 B2). The disadvantage of pumps with modulation of the impeller rotation speed is the inertia of the drive, which does not allow obtaining a given amplitude of flow pulses. In addition, the variable rotor speed of the pumps increases the intra-pump shear stresses, resulting in increased blood trauma.

As a prototype, we have chosen the device and method of biofeedback described in the article Krabatsch T, Potapov E, Stepanenko A, Schweiger M, Kukucka M et al. Circulation .: Biventricular circulatory support with two miniaturized implantable assist devices. Circulation 2011 124 (11) Suppl: S179-S186.

The biofeedback system is based on the connection of the left and right centrifugal LNP (HeartWare HVAD) according to the scheme: left ventricle - aorta and right ventricle - pulmonary artery. The control unit for each pump regulates the rotation speed of the impeller of each pump. The main disadvantage of this system is the non-pulsating blood flow at the outlet of the right and left pump, which negatively affects organ microcirculation. The absence of intra-pump pulsation increases the likelihood of thrombus formation in pumps.

In addition, since pulmonary arterial resistance of the pulmonary circulation is approximately 6 times less than the arterial resistance of the large circle, for these pumps, the performance of which is calculated for use in LV systems, to maintain a relatively high rotor speed of the pump and reduce the likelihood of thrombosis when using the pump in the OPZh system, additional hydraulic resistance is installed in series with the right pump. At the same time, the energy consumption for the operation of the right pump is practically equal to the energy consumption of the left pump, which ultimately leads to an increase in the total energy consumption of the biofeedback system and a reduction in the autonomous operation of the system from batteries.

SUMMARY OF THE INVENTION

A biofeedback system is proposed, containing left and right rotary pumps (RN) of blood (RNP), connected with a pump control unit. The pump control unit provides a constant speed of rotation of the impeller of each pump. The input line of each pump contains an actuator (A) made in the form of a hydraulic resistance with a drive connected to the drive control unit. The latter includes a block 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 by completely opening or partially blocking the lumen of the inlet line.

In the biofeedback system, electromechanical, electro-pneumatic or electro-hydraulic drives can be used.

A biofeedback method is also proposed, in which a patented biofeedback system is used. In this case, the input line of the left pump is connected to the left ventricle of the heart, and its output line to the aorta; the input line of the right pump is connected to the right ventricle of the heart, and its output line to the pulmonary artery.

Another BFB method is proposed, in which a patented BFB system is used. In this case, the input line of the left pump is connected to the left atrium, and its output line to the aorta, the input line of the right pump is connected to the right atrium, and its output line to the pulmonary artery.

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

The peculiarity of the inclusion of actuators in the input lines of the pumps is that the main energy for the operation of the actuator is spent at low pressure at the inlet of the left and right pumps of the biofeedback (in the atria), which helps to reduce energy consumption for the operation of active controlled resistance, which also significantly reduces its weight - overall characteristics for the implementation of the implantable biofeedback option.

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

- 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 BFB pumps;

- improvement of the intra-pump hydrodynamics due to the generation of a pulsating flow in the right and left pumps of the biofeedback without changing the speed of the pump rotor revolutions, which is especially important for the right-hand biofeedback pump in terms of reducing the likelihood of thrombus formation in it

- the possibility of using previously developed LV intended for LV LV without the use of additional hydraulic resistance in the right pump, which creates the basis for creating a low-power implantable biofeedback system.

BRIEF DESCRIPTION OF DRAWINGS

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

in fig. 1 shows a diagram of the proposed biofeedback system, which generates a pulsating flow in the left and right pump when the right pump is connected according to the "right atrium - pulmonary artery" scheme and the left pump according to the "left atrium - aorta" scheme;

in fig. 2 shows a diagram of the proposed biofeedback system, which generates a pulsating flow in the left and right pump when the right pump is connected according to the "right ventricle - pulmonary artery" scheme and the left pump according to the "left ventricle - aorta" scheme;

in fig. 3 shows a diagram of pressures and flow rates obtained on a two-circle hydrodynamic stand when the left and right LV of the biofeedback system operate in a non-pulsating mode;

in fig. 4 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 of the biofeedback system operate in a pulsating mode using the installation of the RN-A system in the inlet line.

The figures indicate the following positions: 1 - rotary pump for replacing the left ventricle, 2 - rotary pump for replacing the right ventricle, 3 - hydraulic resistance at the inlet of the left pump, 4 - hydraulic resistance at the inlet of the right pump, 5 - hydraulic resistance drive for the left pump , 6 - hydraulic resistance drive for the right pump, 7 - actuator (A) for the left pump, 8 - actuator (A) for the right pump, 9 - inlet line of the left pump, 10 - inlet line of the right pump, 11 - actuator drives control unit , 12 - pump control unit, 13 - left pump outlet line, 14 - right pump outlet line, 15 - left atrium, 16 - right atrium, 17 - aorta, 18 - pulmonary artery, 19 - left ventricle, 20 - right ventricle, Р _ad - pressure in the aorta, Р _la - pressure in the pulmonary artery, Р _лж - pressure in the left ventricle, Р _pzh - pressure in the right ventricle, Р _lp - pressure in the left atrium, P _pp - pressure in the right m atrium, Q _ao - flow rate in the aorta, Q _la - flow rate in the pulmonary artery, Q _n - flow rate in the pump.

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 flow generation in the biofeedback system.

The patented device (Fig. 1) contains the left and right PH 1, 2 with a pump control unit 12, which determines a given constant speed of rotation of the impeller of each pump. In the input lines 9 and 10, respectively, of the left and right PH 1, 2, A 7, 8 are installed, each of which contains a variable hydraulic resistance 3, 4 with its own drive 5, 6. Drives 5, 6 of each actuator 7, 8 are connected to the control unit drives 11, which provides a given frequency and duty cycle of output pulses of flow and pressure at the output of the left PH 1 and right PH 2.

The 11 drive control unit provides full opening or partial closure of the inlet lines 9 and 10, respectively, of the left and right PH 1, 2, regulating the blood flow at the outlet of each rotary pump.

In the first version, the input line 9 of the left PH1 and the input line 10 of the right PH 2 are connected, respectively, to the left 15 and right 16 atria, and the output lines 13 and 14 of the left PH 1 and right PH 2 are connected, respectively, to the aorta 17 and the pulmonary artery eighteen.

In the second version, the input line 9 of the left PH1 and the input line 10 of the right PH 2 are connected, respectively, to the left 19 and right 20 ventricles, and the output line 13 of the left PH 1 and the output line 14 of the right PH 2 are connected, respectively, to the aorta 17 and the pulmonary arteries 18.

In the phase of generation of the increased amplitude of the output flow of the pumps A 7 and A 8, the gaps of the input line 9, the input line 10 for the left 1 and right 2 PH are completely opened, and in the phase of generation of the reduced amplitude of the output flow of the pumps A 7 and A 8 partially overlap the lumens of the input lines ...

Thus, the drive control unit 11 provides a given frequency and duration of blood flow and pressure pulses for the left and right PH 1 and 2, respectively.

In some cases, in order to maintain the systemic ejection in conditions of TSN, it is necessary to increase the RN productivity, which can lead to the closure of the aortic and pulmonary valves. In these conditions, with prolonged operation of the biofeedback system, there is a risk of developing insufficiency of the outlet heart valves. Therefore, in order to exclude the development of dysfunction of the aortic and pulmonary heart valves in the present biofeedback system, it can be possible to temporarily reduce the performance of the pumps with a given period. The algorithm for using this mode, including the frequency and duration of pump shutdown, can be set by the operator

To confirm the possibility of realizing the declared purpose and achieving the indicated technical result, we present the following experimental data obtained on a two-circular hydrodynamic stand when connecting the input line of the left and right pumps, respectively, to the left and right ventricles, and the output line of the left and right pumps, respectively, to the aorta and pulmonary artery.

Rotaflow centrifugal pumps (Maquet AEG, Germany) were used as pumps on the hydrodynamic stand, the productivity of which was 5 l / min. In this case, the aortic and pulmonary reservoirs, imitating, respectively, the aorta and pulmonary artery, are containers filled with fluid with an air cushion. The air cushion determines the elasticity of the vessels (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 were simulated by open reservoirs.

Thus, as shown by the studies on the hydrodynamic stand, the work of the proposed biofeedback system using the RN-A system for the left and right pumps creates conditions for the generation of a pulsating flow in the large and pulmonary circulation.

The obtained comparative effect of operating the system in a pulsed mode versus a non-pulsed mode is shown in FIG. 3, 4. As can be seen from the diagram, in FIG. 4 in simulators of the aorta and pulmonary artery, physiological pulsating pressure of blood pressure (pressure in the aortic reservoir 111/76 mm Hg) and PA (pressure in the pulmonary reservoir 19/13 mm Hg) is created with pulsating 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 (4)

1. System of biventricular bypass of the heart, containing left and right rotary blood pumps connected to the pump control unit, providing a given speed of rotation of the impeller of each pump constant, while the input line of each pump contains an actuator made in the form of a hydraulic resistance with a drive connected to a drive control unit including a 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 outlet of each rotary pump by completely opening or partially blocking the lumen of the inlet line. 2. The system of claim. 1, which uses an electromechanical, electro-pneumatic or electro-hydraulic drive. 3. The method of biventricular bypass of the heart, which uses the system according to claim 1, connecting the input line of the left pump to the left ventricle of the heart, the output line of the left pump to the aorta; the inlet line of the right pump to the right ventricle of the heart, and the outlet line of the right pump to the pulmonary artery. 4. The method of biventricular bypass of the heart, which uses the system according to claim 1, connecting the input line of the left pump to the left atrium, the output line of the left pump to the aorta, the input line of the right pump to the right atrium, and the output line of the right pump to the pulmonary artery.

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