KR101249264B1 - Ventricular assist device having impedance analysis apparatus - Google Patents

Abstract

The present invention relates to a ventricular assist device, and more particularly to a ventricular assist device having an impedance measuring device capable of measuring the amount of ejection and ejection timing. According to the present invention, there is provided a ventricular assist device including a first conduit, a second conduit through which blood flows, and a blood pump for pumping blood, wherein the incision portion of the first biological tissue and the blood pump are allowed to flow. A first conduit including a connecting tube for connecting, and a first electrode coupled to the connecting tube and in contact with an incision of the first biological tissue to transmit an electrical signal to the first biological tissue; A second electrode spaced apart from the first electrode with the first biological tissue interposed therebetween so as to measure the impedance by blood flowing inside the first biological tissue to which the first conduit is coupled; An impedance measuring device for measuring impedance between the first electrode and the second electrode; It is provided with a ventricular assist device having an impedance measuring device comprising a; control device for receiving a signal from the impedance measuring device to control the operation of the blood pump.

Description

Ventricular assist device having an impedance measuring device {Ventricular assist device having impedance analysis apparatus}

The present invention relates to a ventricular assist device, and more particularly to a ventricular assist device having an impedance measuring device capable of measuring the amount of ejection and ejection timing.

Ventricular Assist Device (VAD) is generally used in patients with heart failure who have no medical effect or are difficult to treat with surgical open heart surgery. It is used to replace the function of the ventricles until the heart is transplanted, or to reduce the load on the heart and induce recovery.

Ventricular assist devices are classified into implantable type ventricular assist devices and extracoporeal type ventricular assist devices according to the implanted area, and LVAD and right ventricular assist devices (RVAD) depending on the assisting heart site. ) And biventricular assist device (BiVAD). Many left ventricular assists are used. In addition, it can be classified into pneumatic type (electric type) and electric (electric type) according to the difference in the way of supplying the power source by another classification method. The electric type is subdivided into electrohydraulic type and electromechanical type. In addition, according to the driving method can be classified into pulsatile type (non-pulsatile type) according to the presence of pulsation (pulsation) when the blood is ejected. The implantable biventricular assist device can be viewed as an artificial heart, but is distinct from a fully transplantable artificial heart in which the natural heart is removed and blood circulation is achieved only by the artificial heart.

Conventional ventricular assist devices can measure or estimate their own blood output, but because the patient's cardiac output, the overall blood circulation is unknown, there was a problem that can not be optimal control according to the physiological situation of the patient. When using ventricular assist devices, the optimal blood flow supplied by ventricular assist devices varies according to the patient's physiological conditions. However, conventional ventricular assist devices have been difficult to have suitable measuring devices for predicting the patient's physiological changes. If the blood supply of the ventricular assist device is too large, blood vessels or heart tissue around the inlet catheter may be narrowed or damaged. If the blood supply of the ventricular assist device is too small, the effect of assisting the heart is reduced. In addition, if the ventricular assist device simultaneously beats while the heart is beating (co-pulsation), the heart muscle may be damaged due to the heavy load on the heart muscle. Therefore, it was necessary to develop a measurement technique that can be easily applied to existing ventricular assist devices while measuring the amount of cardiac output and the timing of cardiac ejection.

The present invention is to improve the above-described problems, by installing an electrode in the conduit used in the ventricular assist device, by measuring the impedance between the heart and the aorta, ventricular assist device that can easily measure the amount of ejection and ejection timing The purpose is to provide.

According to the present invention, there is provided a ventricular assist device including a first conduit, a second conduit through which blood flows, and a blood pump for pumping blood, wherein the incision portion of the first biological tissue and the blood pump are allowed to flow. A first conduit coupled to the first connecting tube and the first connecting tube, the first conduit including a first electrode contacting an incision of the first biological tissue and transmitting an electrical signal to the first biological tissue; A second electrode spaced apart from the first electrode with the first biological tissue interposed therebetween so as to measure the impedance by blood flowing inside the first biological tissue in which the conduit is coupled; and the first electrode Impedance measuring device for measuring the impedance between the second electrode and the impedance, characterized in that it comprises a control device for controlling the operation of the blood pump receives a signal from the impedance measuring device The ventricular assist device having values suit is provided.

Ventricular assist device provided with a cardiac output amount and cardiac output timing device according to the present invention has the following effects.

First, by measuring the impedance, it is possible to predict the blood flow rate and the blood ejection time of the patient, it is possible to optimally control the physiological situation of the patient. That is, when the circulation of the overall blood flow decreases, the blood flow rate of the ventricular assist device is lowered, thereby preventing blood vessels from contracting or damaging due to excessive blood flow inhalation, and avoiding blood ejection of the ventricular assist device during cardiac ejection, thereby simultaneously pulsating This can minimize the load on the patient's heart.

Second, by measuring the impedance of the current path leading to the patient's blood vessels, aortic valve, heart, it is possible to determine whether the valve is opened or closed.

Third, it is possible to measure and monitor the long-term patient's heart rhythm and valve movement without the need for specialists, and to discover real-time risk factors.

1 is a conceptual diagram of a ventricular assist device having an impedance measuring device according to an embodiment of the present invention.
FIG. 2 is a side view showing a first conduit of the ventricular assist device shown in FIG. 1.
3 to 5 show changes in aortic blood flow, arterial pressure, ECG, and impedance values when the ejection volumes of the ventricular assist devices are 0.5, 1.0, and 1.5 L / min.
6 is an enlarged view of a portion of FIG. 5.
7 is a flow chart showing the steps of measuring the opening and closing time and cardiac output of the heart valve through the change of the impedance value.
8 is a flow chart showing the steps of controlling the ventricular assist device using the opening and closing time and cardiac output measurement value of the heart valve.
9 to 11 illustrate first conduits of a ventricular assist device having an impedance measurement device according to other embodiments of the present invention.
12 and 13 are views illustrating an installation state of electrodes of a ventricular assist device having an impedance measuring device according to other exemplary embodiments of the present invention.

Hereinafter, with reference to the accompanying drawings, it will be described in detail an embodiment of the present invention. 1 is a conceptual diagram of a ventricular assist device having an impedance measuring device according to an embodiment of the present invention.

Referring to Figure 1, the ventricular assist device with an impedance measuring device according to an embodiment of the present invention is connected to a ventricle (1) corresponding to an example of the first biological tissue, similar to the general ventricular assist device 1) connects the first conduit into which blood in the blood flows, the blood pump 3 connected to the first conduit to pump blood, the blood pump 3 and the aorta 2 corresponding to one example of the second biological tissue. And a second conduit for delivering the blood ejected from the blood pump 3 to the aorta 2.

FIG. 2 is a side view showing a first conduit of the ventricular assist device shown in FIG. 1. Since the second conduit has the same configuration as the first conduit, only the first conduit will be described. Referring to FIG. 2, the first conduit is a long tube that is empty inside so that blood can flow. The first conduit includes a first connecting tube 10a and a conductive sheet 20 attached to the surface of the first connecting tube 10a. The conductive sheet 20 corresponds to an example of the first electrode. The first connector 10a may be made of a flexible material, but elasticity capable of contraction and expansion to function as an bypass conduit (AAC) that reduces the load on the heart when not used as a ventricular assist device. It is more preferable that the material is composed of. In addition, the first connector 10a is preferably made of a biopolymer material having excellent blood compatibility and excellent durability, for example, medical polyurethane.

The conductive sheet 20 is attached to the surface of the first connecting pipe 10a and connected to the impedance measuring device 6 through the conductive wire 30. The conductive sheet 20 is made of Ag / AgCl, Pt (platinum), Au (gold) or other electrode material. The conductive sheet 20 has a first connector 10a and a second connector 10b inserted into the ventricle 1 and the aorta 2 through incisions of biological tissues such as the ventricle 1 and the aorta 2, respectively. When attached, it is attached to a position where it can come into contact with the end face of the incision.

The blood pump 3 can be classified into a pneumatic type and an electric type. The electric type is subdivided into electrohydraulic type and electromechanical type. The blood pump 3 stores the blood flowing in the first connecting pipe 10a and expands and compresses the blood bag and the blood bag flowing out of the second connecting pipe 10b to allow the blood to flow. Air, electric devices. Since the blood pump 3 may use a well-known apparatus, detailed description is abbreviate | omitted.

Referring to FIG. 1, a ventricular assist device having an impedance measuring device according to an embodiment of the present invention receives a signal from an impedance measuring device 6 and an impedance measuring device and controls a blood pump 3 ( It further includes 4).

The impedance measuring apparatus 6 is connected to the conductive sheet 20 through the conductive wire 30. The impedance measuring device 6 includes a power supply device capable of applying a high frequency alternating current. In the power supply, high-frequency alternating current is generated, which is applied to the heart through the electrodes. When a sinusoidal high frequency current (30 kHz, 0.2 mA) was applied between the heart and blood vessels in a patient using a ventricular assist device, it was confirmed that the current had no effect on nerves, muscles and heart tissues. The high-frequency current generated by the power supply generates high-frequency voltages that pass in proportion to the impedance of the heart and blood vessels as they pass through the heart and blood vessels. Impedance measuring device measures the change of impedance value by measuring and recording the high frequency voltage caused by the change of impedance due to heartbeat.

3 to 5 show changes in aortic blood flow, arterial pressure, ECG, and impedance values when the ejection volumes of the ventricular assist devices are 0.5, 1.0, and 1.5 L / min. In animal experiments with 40 kg of pigs, the first and second conduits with electrodes attached to Shenzhen and the aorta of the left ventricle were measured. Changes in aortic blood flow were measured using an ultrasonic flowmeter installed in the aortic arch.

As can be seen in Figures 3 to 5, the impedance value was changed according to the valve of the heart opening and closing, blood volume in the ventricles, blood volume in the aorta. The opening and closing of the heart valve can be confirmed by aortic pressure. When the heart contracts and the aortic valve is open, the impedance has a minimum value and the impedance has the maximum value when the arterial pressure is the lowest with the heart valve closed. Impedance decreased and increased as the valve of the heart opened and closed. In particular, it was confirmed that the inflection point occurred during the impedance change due to the valve movement.

6 is an enlarged view of a portion of FIG. 5. In section 1, impedance increases due to ventricular contraction, and in section 2, impedance decreases due to dilation of the artery. Section 3 is a section in which the slope of the impedance is changed due to the closing of the aortic valve. Section 4 is a section in which impedance decreases due to the expansion of the ventricles. After the minimum value, section 5 stops the expansion of the ventricles and constricts blood vessels to increase impedance. In section 6, the impedance decreases due to atrial contraction, further expansion of the ventricles, and temporary opening of the aortic valve. In section 7, the aortic valve is closed and the impedance increases as the aorta contracts. In section 8, the impedance decreases with the opening of the aortic valve. As such, the impedance value changes according to the timing of opening and closing of the heart valve and contraction and expansion of the heart. Therefore, the heart valve timing and cardiac output can be measured by changing the impedance value. 7 is a flow chart showing the steps of measuring the opening and closing time and cardiac output of the heart valve through the change of the impedance value.

Referring to Figure 7, an example of calculating the opening and closing time and cardiac output of the heart valve through the impedance measurement will be described. First, the maximum value I _max and the time T _max of the impedance I are measured. The maximum value of impedance I _max is due to the minimal contraction of the ventricles. Next, the inflection point and time T ₁ are measured by differentiating the impedance (I) value. The inflection point between the maximum value (I _max ) and the minimum value (I _min ) of the impedance is caused by the closing of the heart valve. Next, the minimum value of impedance I _min and the time T _min are measured. The minimum value of impedance I _min is due to the maximum expansion of the ventricles. Next, the impedance (I) value is differentiated to measure the inflection point and time (T ₂ ) again. The inflection point after the minimum value (I _min ) is caused by the opening of the heart valve.

The cardiac output amount CO may be obtained by multiplying the difference between the maximum value I _max and the minimum value I _min and the product of the heart rate HR by multiplying an appropriate proportional constant C. Heart rate HR is the interval between the opening or closing of the heart valve (T ₂ ) (T ₁ ) or the time between reaching the maximum value (T _max ) or reaching the minimum value (T _min ) of the impedance. Can be measured at intervals.

The control device 4 processes the signal measured by the impedance measuring device 6 through the microcontroller unit, and controls the blood pump 3. 8 is a flow chart showing the steps of controlling the ventricular assist device using the opening and closing time and cardiac output measurement value of the heart valve. As shown in FIG. 8, the cardiac output amount and the total blood flow circulating amount may be compared with a value multiplied by the constant P1, and the ventricular assist device may be controlled in consideration of the opening and closing time of the heart valve. That is, the control device lowers the blood flow rate of the ventricular assist device when the circulation of the overall blood flow decreases, thereby preventing blood vessels from contracting or damaging due to excessive blood flow inhalation, and avoiding blood ejection of the ventricular assist device during cardiac ejection. The blood pump 3 can be optimally controlled in such a way as to minimize the load on the patient's heart.

9 to 11 illustrate first conduits of a ventricular assist device having an impedance measurement device according to other embodiments of the present invention. Since the second conduit has the same configuration as the first conduit, only the first conduit will be described. Referring to FIG. 9, the first conduit according to the present exemplary embodiment includes the first connecting tube 10a and the hollow electrode 40 corresponding to another example of the first electrode. Since the first connection pipe 10a is the same as the embodiment of FIG. 2, description thereof will be omitted and only the hollow electrode 40 will be described. The hollow electrode 40 has a cylindrical shape in which a hollow 41 into which the connection pipe 10 can be inserted is formed. The periphery of the hollow electrode 40 is formed with a receiving groove 42 that can accommodate the incision of the biological tissue. When the hollow electrode 40 is inserted through the incision of the biological tissue, the incision of the biological tissue is inserted into the receiving groove 42. The connector 10 is inserted into the biological tissue through the hollow 41 of the hollow electrode 40. Inside the receiving groove 42 of the hollow electrode, a conductive layer 43 made of an electrode material such as Ag / AgCl, Pt (platinum), Au (gold) is formed, and the conductive layer 43 is formed of a conductive wire ( 30 is connected to the impedance measuring device (6). The entire hollow electrode may be made of an electrode material without forming a separate conductive layer.

Referring to FIG. 10, the first conduit of the ventricular assist device provided with the impedance measuring device according to the present embodiment includes an electrode 50 having a first connecting pipe 11 a, a body part 51, and a fixing part 54. ). The electrode 50 corresponds to another example of the first electrode. The body portion 51 is formed with a hollow (not shown) through which blood can flow, and similarly to the second embodiment, a receiving groove 52 is formed in the circumference to accommodate the incision of the biological tissue. In the drawing, a through hole 53 through which blood can pass is formed at one end of the body 51, and a fixing part 54 extending from the body 51 is formed at one end of the body 51. The fixing part 54 is inserted into the connecting pipe 11 and serves to connect the electrode 50 and the connecting pipe 11, and a protrusion 55 is formed to prevent the connecting part from being easily separated.

 Referring to FIG. 11, the first conduit of the ventricular assist device provided with the defibrillation device according to the present embodiment includes a connection tube, a body portion 61, and a fixing portion 62 divided into an insertion portion 12a and a connection portion 13a. And an electrode 60 with 64. The electrode 60 corresponds to another example of the first electrode. The body portion 61 is formed with a hollow (not shown) through which blood can flow, and the outer surface is in close contact with the incision of the biological tissue. The fixing parts 62 and 64 extend from the body part 61 to the left and the right sides, respectively, and protrusions 63 and 65 are formed to prevent separation from the insertion part 12a and the connection part 13a. have. One end of the insertion portion 12a is connected to the left fixing portion 62, the other end of the insertion portion is inserted into the inside of the biological tissue, and one end of the connecting portion 13a is connected to the right fixing portion 64, and the other end of the ventricular assist device. (Not shown).

12 and 13 are views illustrating an installation state of electrodes according to other embodiments of the present invention. As can be seen in Figures 12 and 13, instead of installing the second electrode in the second connector (10b), the electrode 21 can be attached to the body near the aorta, and the implantable electrode (22) near the artery in the body. ) Can also be installed.

In the above, the present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications can be made by those skilled in the art within the technical idea of the present invention. Is obvious.

1: ventricle 2: aorta
3: blood pump 4: controller
6: impedance measuring device 10a: first connector
10b: second connector 20: conductive sheet
30: conductor 40: hollow electrode
50, 60: electrode

Claims (11)

A ventricular assist device comprising a first conduit through which blood flows, a second conduit, and a blood pump for pumping blood,
The first connecting tube connecting the incision of the first biological tissue and the blood pump and the first connecting tube to allow blood to flow, and contacting a cross section of the incision of the first biological tissue to the first biological tissue. A first conduit comprising a first electrode for transmitting an electrical signal;
A second electrode spaced apart from the first electrode with the first biological tissue interposed therebetween so as to measure the impedance by blood flowing inside the first biological tissue to which the first conduit is coupled;
An impedance measuring device for measuring impedance between the first electrode and the second electrode;
Ventricular assist device having an impedance measuring device, characterized in that it comprises a control device for receiving a signal from the impedance measuring device to control the operation of the blood pump. The method of claim 1,
The second conduit includes a second connecting tube connecting the incision of the second biological tissue and the blood pump so that blood flows,
The second electrode is coupled to the second connecting tube and ventricular assist device having an impedance measuring device, characterized in that the contact with the end surface of the incision of the second biological tissue. The method of claim 1,
Wherein the second electrode comprises:
Ventricular assist device provided with an impedance measuring device, characterized in that the electrode patch attached to the skin. The method of claim 1,
Wherein the second electrode comprises:
Ventricular assist device provided with an impedance measuring device, characterized in that the implantable electrode installed in the body. The method of claim 1,
The first electrode,
Ventricular assist device provided with an impedance measuring device, characterized in that the conductive sheet attached to the surface of the first connector. The method of claim 1,
The first electrode,
A hollow is formed inside the first connector tube can be inserted, the outer surface is a ventricular assist device having an impedance measuring device, characterized in that the hollow electrode in close contact with the incision of the first biological tissue. The method according to claim 6,
Ventricular assist device provided with an impedance measuring device, characterized in that the receiving groove for accommodating the incision of the first biological tissue is formed around the outer surface of the hollow electrode. The method of claim 1,
The first electrode,
The hollow is formed inside the blood flow, the outer surface is in close contact with the incision of the first biological tissue, the body portion inserted into the first biological tissue, and extends from the body portion, A ventricular assist device having an impedance measuring device, characterized in that the connector-type electrode comprising a fixed portion, which is inserted into and fixed to the connector. 9. The method of claim 8,
Ventricular assist device having an impedance measuring device, characterized in that the receiving groove is formed around the outer surface of the body portion for receiving the incision of the first biological tissue. The method of claim 1,
The first electrode,
A hollow is formed inside the blood flow, the outer surface includes a body portion in close contact with the incision of the first biological tissue and fixing portions extending from the body portion to the upstream and downstream, respectively,
The first connector,
One end is connected to the fixing part and the other end is inserted into the insertion portion of the inside of the first biological tissue and the other end is connected to the other fixing part and the other end is connected to the blood pump Ventricular assist device with measurement device. The method of claim 10,
Ventricular assist device having an impedance measuring device, characterized in that the receiving groove is formed around the outer surface of the body portion for receiving the incision of the first biological tissue.

Images