KR101630124B1 - Heart Monitoring Method of Ventricular assist device Patients - Google Patents

Abstract

The present invention relates to a method of monitoring a heart function of a patient with a ventricular assist device, and more specifically, to a method of sensing the occurrence of an abnormal contraction of the heart to a patient with a ventricular assist device including an implantable electrode installed on the cardiac apex and the aorta. The method comprises: a step A of extracting a ventricular impedance change value in a systole based on a first information on a ventricular impedance measured by the implantable electrode and a second information on electrocardiogram; a step B of extracting a ventricular impedance change prediction value in the systole based on a third information on a blood suction time and a blood suction amount per hour measured by the ventricular assist device and the second information measured in the step A; and a step C of comparing the ventricular impedance change value extracted in the step A to the ventricular impedance change prediction value extracted in the step B to monitor the heart function of the patient. Here, the method may provide results having further improved accuracy in determining whether an abnormal contraction of the heart has occurred in a patient with a ventricular assist device.

Description

[0001] The present invention relates to a method for monitoring heart function of a patient who has implanted a ventricular assist device

The present invention relates to a method for monitoring cardiac function in patients with transplantation of a ventricular assist device for early diagnosis of possible heart disease.

Conventional ventricular assist devices (VADs) have been used as a device to assist or replace the function of the ventricle in a cross-over manner at a previous stage of heart transplantation for the treatment of patients with heart disease, There is also an increasing trend of permanent use of such ventricular assist devices.

In addition, studies have shown that patients with transplanted ventricular assist devices may have additional cardiac disease, such as arrhythmias, resulting in a lower survival rate for patients transplanted with ventricular assist devices.

Accordingly, there is a need in the art for early detection of the occurrence of additional heart disease such as arrhythmia in patients transplanted with ventricular assist devices, and information on the cardiac function status of patients transplanted with such ventricular assist devices The inventor of the present invention has been able to acquire heart condition information including impedances at the same time as supporting the ventricular function through the prior art based on the "ventricular assist device equipped with impedance measuring device " of Korean Patent Registration No. 10-1249264 I have presented a ventricular assist device.

However, cardiac status information, such as electrocardiograms, measured from conductive members including electrodes implanted in conjunction with ventricular assist devices, may include noise from complexly installed leads and devices, and information And as a result, there is a problem in that it is not possible to determine early on whether or not an additional heart disease has occurred correctly.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and it is an object of the present invention to provide a method and apparatus for diagnosing heart diseases, In order to improve the accuracy of the method.

In order to achieve the above object, the present invention provides a method for monitoring cardiac function in a patient who has implanted a ventricular assist device, which includes abnormal cardiac contraction in a patient implanted with a ventricular assist device including an implantable electrode capable of being installed on the aorta and the aorta A method for sensing a ventricular impedance change value in a cardiac systole based on first information on a ventricular impedance measured from the electrode and second information on an electrocardiogram; Extracting a predicted value of a ventricular impedance change in a cardiac systolic based on third information on a blood suction time and an amount of suction per hour measured through the ventricular assist device and second information measured through the step A; And a step C of comparing the ventricular impedance change value extracted through the step A and the ventricular impedance change predicted value extracted through the step B to monitor the cardiac function of the patient.

In the step C, it is determined that an abnormal heart contraction occurs when the change in the ventricular impedance extracted through the step A is equal to or less than a half of the predicted value of the ventricular impedance variation extracted through the step B.

In addition, the step A may further include: A-1 step of acquiring the first information and the second information from the electrode; A-2 step of extracting an impedance at a time of depolarization of the ventricle based on the first information and the second information obtained through the step A-1; A-3 step of extracting the impedance at the time of repolarization of the ventricle based on the first information and the second information obtained through the step A-1; And a step A-4 of calculating the change in the cardiac systolic impedance in the cardiac systolic through the difference between the impedance extracted through step A-2 and the impedance extracted through step A-3.

The step (B) may further include: (B-1) acquiring the third information from the ventricular assist device; Based on the third information obtained in the step B-1, the second information obtained in the step A-1, and the fourth information on the average cardiac output per hour of the patient, Step B-2 for measuring volume reduction; And (B-3) extracting the predicted value of the ventricular impedance change by predicting the degree of change in the ventricular impedance in the cardiac systolic based on the ventricular volume reduction amount measured in the step B-2. .

The step B may further include a B-4 step of filtering the predicted value of the ventricular impedance variation extracted through the step B-3 through a moving average filter.

In addition, the amount of ventricular volume reduction in the cardiac systole of the step B-2 is measured using the following equation (1).

[Equation 1]

(LV volume decrease _{RT period} is the ventricular volume reduction in the systolic, Total Flow is the mean cardiac output per hour, Inflow _VAD is the hourly blood intake to the ventricular assist device, HR is the heart rate, and t _{RT period} is the ventricular assist device Blood inhalation time)

According to the present invention, the following effects can be obtained.

First, patients with implanted ventricular assist devices can be provided with improved accuracy in determining abnormal cardiac contractions.

Second, the ability to monitor cardiac function in patients with transplanted ventricular assist devices allows early detection of additional heart disease, such as arrhythmias.

1 is a flowchart illustrating a method for monitoring cardiac function in a patient transplanted with a ventricular assist device according to the present invention.
FIG. 2 is a flowchart showing detailed steps of extracting a change value of a ventricular impedance change in a cardiac function monitoring method of a patient who has implanted a ventricular assist device according to the present invention.
FIG. 3 is a flowchart illustrating detailed steps of extracting a predicted value of a ventricular impedance change in a cardiac function monitoring method of a patient who has implanted a ventricular assist device according to the present invention.
4 is a conceptual diagram briefly showing a configuration of a cardiac function monitoring system of a patient implanted with a ventricular assist device.
5 is a flow chart illustrating a flow of a method for monitoring cardiac function in a patient transplanted with a ventricular assist device in accordance with the present invention in a cardiac function monitoring system of a patient implanted with a ventricular assist device.
6 is a graph showing the results of the ventricular impedance measurement through the step of extracting the ventricular impedance change value.
FIG. 7 is a graph showing the electrocardiogram measurement result through the step of extracting the change in the ventricular impedance.
8 is a graph showing a result of measuring the change in the ventricular impedance of the ventricular systolic phase through the step of extracting the ventricular impedance change value.
9 is a graph showing an average blood ejection amount per hour in the aorta extracted based on the average cardiac output per hour stored in the ventricular impedance change predictive value extraction step.
10 is a graph showing a result of measurement of the blood suction amount per hour into the ventricular assist device through the step of extracting the predicted value of the ventricular impedance change.
11 is a graph showing the predicted value of the ventricular impedance change value of the ventricular systolic phase through the step of extracting the predicted value of the ventricular impedance change.
12 is a graph showing the calculation results of the ratio of the measurement result shown in FIG. 8 and the prediction result shown in FIG.

The preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings, in which the technical parts already known will be omitted or compressed for the sake of brevity.

Description of the cardiac function monitoring system of a patient implanted with ventricular assist device

4 and 5, a cardiac function monitoring system for a patient implanted with a ventricular assist device 20 to which a heart function monitoring method of a patient implanted with the ventricular assist device 20 of the present invention is applied will be described. The system includes a ventricular assist device (20) including an implantable electrode (10) attachable to the aorta and the aorta; And a cardiac function monitoring device 100.

A ventricular assist device (20) is a medical device that is implanted in the body to supplement or replace the function of the ventricle to overcome the circulation problem of blood caused by a heart disease which causes deterioration of the ventricular function. It is possible to minimize the load applied to the heart by sucking it out into the aorta.

4, the ventricular assist device 20 is connected to a separate incision formed in the left ventricle as shown in FIG. 4, and is connected to a first conduit for sucking blood expelled by contraction of the left ventricle, And a second conduit connected to a separate incision formed in the first conduit and the second conduit for draining the blood sucked through the first conduit into the aorta. The implantable electrode 10 is formed at the end of the first conduit and the second conduit, It is installed in the aorta and the aorta corresponding to the site.

In addition, the implantable electrode 10 provided at each site is connected to the cardiac monitoring apparatus 100, which will be described below, through a lead 15 to transmit a biometric signal indicating the cardiac state measured from each region, The device 20 is connected to the cardiac function monitoring device 100, which will be described below, via a connection line 25 to convey information about the blood suction to the ventricular assist device 20, which is measured by itself.

The cardiac function monitoring device 100 includes cardiac condition related information (information about blood suction to the vital signs and ventricular assist device) provided from the ventricular assist device 20 including an implantable electrode 10 that is attachable to the heart and the aorta ) To monitor cardiac function.

Here, the cardiac function monitoring apparatus 100 includes a first detection unit 110 as shown in FIG. 4; A second detection unit (120); And an inspection unit (130).

First, as shown in FIG. 5, the first detection unit 110 receives bio-signals such as the ventricular impedance and the electrocardiogram measured through the implantable electrodes 10 installed in the heart and the aorta (S110) The ventricular impedance change value at the ventricular systolic period indicating the degree of impedance change from the time of depolarization to the timing of ventricular repolarization is extracted (S120 to S140).

Next, the second detection unit 120 receives information on the blood suction time and the suction amount per hour measured by the ventricular assist device 20 (step S210), as shown in FIG. 5 (S115) based on the received information on the electrocardiogram received through the first detection unit 110, and predicts the degree of impedance change from the time of ventricular depolarization to the timing of ventricular repolarization based on the received information, thereby extracting a predicted value of the ventricular impedance change in the ventricular systolic (S220 to S240).

5, the inspection unit 130 compares the ventricular impedance change value extracted by the first detection unit 110 with the predicted value of the ventricular impedance change extracted by the second detection unit 120, If the value is less than half of the predicted value of the impedance change, the ventricular assist device 20 monitors the cardiac function of the transplanted patient by determining that the abnormal cardiac contraction has occurred.

Thus, the cardiac monitoring apparatus 100 can accurately and early diagnose a heart disease such as an arrhythmia which may additionally occur in a patient implanted with the ventricular assist device 20. [

Explanation of how to monitor cardiac function in patients implanted with ventricular assist device

The following will describe how the cardiac function monitoring method of a patient who transplanted the ventricular assist device 20 of the present invention using the heart function monitoring system of the patient transplanted with the above-described ventricular assist device 20 is described below with reference to FIGS. 3 will be described in detail with reference to the flowchart of Fig.

As an embodiment of each step of the present invention, a description of each step is supplemented with reference to the graphs of FIGS. 6 to 12 showing the results of measurement of each information on the animal experiment conducted do.

This animal experiment was performed by inserting a ventricular assist device (LibraHeart I) equipped with a ventricular-ECG amplifier, a ventricular-ECG measuring electrode, and a separate impedance measuring device into Yorkshire, Each process was performed.

1. Extracting the value of the ventricular impedance change value <S100>

In this step, based on the ventricular impedance (first information) measured through the implantable electrode 10 installed in the heart and the aorta, and the electrocardiogram (second information) measured through the implantable electrode 10 installed in the heart and the aorta The value of the change in the ventricular impedance at the ventricular systolic phase indicating the degree of impedance change from the time of ventricular depolarization to the timing of ventricular repolarization is extracted.

More specifically, in this step, the ventricular impedance change value extraction step (S100, step A) includes the ventricular impedance and electrocardiogram acquisition steps (steps S110 and A-1) as shown in FIG. An impedance extraction step at the time of ventricular depolarization (S120, step A-2); An impedance extraction step at the time of ventricular repolarization (S130, step A-3); And the step of calculating the degree of change in the ventricular impedance (steps S140 and A-4). Also, the flow of such a step is preferably performed in the first detection unit 110 in the cardiac function monitoring apparatus 100 described above.

First, the ventricular impedance (first information) and the electrocardiogram (second information) measured from the implantable electrodes 10 installed in the heart and the aorta are acquired and acquired in the ventricular impedance and electrocardiogram acquisition steps (steps S110 and A-1) .

Here, the results measured based on the heartbeat over time through a separate experiment on the ventricular impedance (first information) measured from the implantable electrode 10 change as shown in FIG.

In addition, a result of measuring the electrocardiogram (second information) measured from the implantable electrode 10 on the basis of the heartbeat over time through a separate experiment changes as shown in FIG.

Thereafter, in the impedance extraction step (S120, step A-2) at the time of ventricular depolarization, based on the first information and the second information acquired through the step S110, a time point at which ventricular depolarization occurs on the electrocardiogram (QRS complex ), And more specifically, the impedance value at the R-wave point, which is the highest point in the QRS complex, is extracted. Here, it is preferable to use the Tompkins method to detect the time point (QRS Complex) at which ventricular depolarization occurs on the electrocardiogram.

Thereafter, in the impedance extraction step (steps S130 and A-3) at the time of the heart stem re-polarization, based on the first information and the second information acquired through the step S110, a time point at which the ventricular re- A point having a positive value greater than or equal to a threshold value within a time range of 50 to 450 msec from the occurrence of the complex). More specifically, the impedance value at the highest point of the T-wave is extracted.

Finally, the step of calculating the degree of ventricular impedance change (steps S140 and A-4) calculates the difference between the impedance at the time of ventricular depolarization extracted at the preceding two steps (S120 and S130) and the impedance at the time of ventricular repolarization, The process of calculating the change in the ventricular impedance in the ventricular systolic period (RT period) is performed.

The calculated change in the ventricular impedance can be represented as shown in FIG. 8. Based on the results shown in FIGS. 6 and 7, among the impedance values shown in FIG. 6, Period), which can be obtained by measuring the degree of change.

2. Extracting predicted values of ventricular impedance changes <S200>

In this step, information on the blood suction time and the amount of suction per hour (third information) measured to the ventricular assist device 20 measured through the ventricular assist device 20, and information on the blood suction time measured through the implantable electrode 10 installed on the aorta and the aorta Based on the electrocardiogram (second information), we predict the degree of impedance change from the ventricular depolarization point to the time of ventricular repolarization to extract the estimated value of the ventricular impedance change in the ventricular systolic phase.

More specifically, the step of extracting the predicted value of the ventricular impedance change (step S200, step B) may include acquiring the blood suction-related information of the ventricular assist device (steps S210 and B-1) as shown in FIG. A volume reduction amount measurement step of the ventricle (S220, step B-2); A step of predicting the degree of change of the ventricular impedance (S230, step B-3); And a filtering step (steps S240 and B-4). Also, it is preferable that the flow of this step is performed in the second detection unit 120 in the cardiac function monitoring apparatus 100 described above.

First, in the blood suction-related information acquisition step (steps S210 and B-1) of the ventricular assist device, information on the blood suction time and the suction amount per hour measured by the ventricular assist device 20 Information).

Here, the blood suction time to the ventricular assist device 20 measured from the ventricular assist device 20 and the information on the amount of suction per hour (third information) are measured separately from the heartbeat measured over time The results for the inhalation volume change as shown in FIG.

Thereafter, in the step of measuring the amount of volume reduction of the ventricle (steps S220 and B-2), the third information acquired through the step S210 and the cardiac information transmitted from the first detection unit 110 through a separate process (S115) (Second information) measured through the implantable electrode 10 installed in the aorta and the mean cardiac output (fourth information) per hour of the patient transplanted with the previously stored ventricular assist device 20 (fourth information) RT period).

Here, the average cardiac output (fourth information) per hour of the patient implanted with the ventricular assist device 20 is the information that is stored after being measured through a thermal dilution method or an ultrasonic blood flow meter. The result of the measurement of the blood flow rate of the aorta, which is measured based on the fourth information, is used as shown in Fig.

In addition, the amount of ventricular volume reduction during the cardiac systole (RT period) can be calculated in relation to the amount of blood ejected through the ventricle. The heart of the patient transplanted with the ventricular assist device 20 is excreted through the ventricle The amount of blood suction into the ventricular assist device 20 and the amount of blood flow into the aorta are required because the lost blood is delivered not to the ventricular assist device 20 but to some aorta.

Therefore, the amount of ventricular volume reduction in the cardiac systolic period (RT period) is calculated through the following equation (1), and as shown in Equation (1), the blood suction amount per hour from the average cardiac output per hour to the ventricular assist device To calculate the blood flow rate per hour into the aorta. This is because the average cardiac output per hour measured by the thermodilution method is generally measured in the pulmonary artery, indicating the total volume of blood ejected from the ventricle.

[Equation 1]

(Wherein, _{R -T} LV volume decrease _period is ventricular volume decrease in systolic heart, Total Flow is the mean cardiac output, _VAD Inflow per hour blood intake, HR is the heart rate, t _{RT period} of a ventricular assist device ventricular assist device per hour Lt; / RTI &gt;

Therefore, when the second detection unit 120 stores information on the blood flow rate to the aorta per hour, it can be calculated through the following equation (2).

&Quot; (2) &quot;

(Where LV volume decrease _{R -T period} is the ventricular volume reduction in the systolic heart, Flow_aortic valve is the blood flow to the aorta per hour, Inflow_VAD is the hourly blood inhalation volume to the ventricular assist device, R-Wave is the ventricular depolarization timing T- Is the time of ventricular repolarization, and t is time)

That is, in this step (S220), the amount of blood that has been accurately transferred to the aorta and the ventricular assist device (20) is measured to measure the degree of decrease in the ventricular volume.

Thereafter, the degree of change in the ventricular impedance in the cardiac systole is predicted based on the amount of decrease in the ventricular volume calculated through the step S230 of measuring the amount of volume reduction of the ventricle in the step of predicting the degree of change in the ventricular impedance (steps S230 and B-3) The predicted value of the change in the ventricular impedance at the systole is extracted.

In other words, since the volume of the ventricle in the systole of the heart decreases for the release of blood, and as a result the amount of impedance increases, the degree of change in the volume of the ventricle due to changes in the blood flow is the basis for predicting the degree of impedance change .

That is, in the step of predicting the degree of change in the ventricular impedance (steps S230 and B-3), the amount of change in the impedance can be predicted by applying an appropriate proportional coefficient to the ventricular volume reduction amount calculated through the ventricle volume reduction step S220. As a result, the result of extracting the predicted amount of impedance change through a separate experiment changes as shown by blue in FIG. The results of FIG. 11 are based on the results of the heart viscosity shown in FIG. 7 and the results of estimating the amount of decrease in the ventricular volume calculated from the results of the amount of blood moved from the ventricles per hour shown in FIGS. 9 and 10 to be.

Finally, in the filtering step S240 and step B-4, the predicted value of the change in the ventricular impedance in the cardiac systole extracted in the preceding step S130 is filtered through a moving average filter, A correction process is performed so as to have the correction coefficient.

Here, the predicted value of the change in the ventricular impedance in the cardiac systole subjected to the filtering process is derived as shown in Fig. 11 in red.

3. Cardiac function monitoring phase <S300>

In this step, the ventricular impedance change value and the ventricular impedance change predicted value extracted in the cardiac systole extracted by the first detection unit 110 and the ventricular impedance change predicted value extraction step (steps S200 and B) are extracted through the ventricular impedance change value extraction step 2 detection unit 120 compares the predicted value of the change in the ventricular impedance in the cardiac systole and monitors the cardiac function of the patient.

5, the cardiac function monitoring step S300 (step C) receives the change in the heartbeat impedance in the cardiac systole extracted by the first detection unit 110 (S150 ), And all steps of the above step are performed in the examination unit 130 in the cardiac function monitoring apparatus 100 that receives the predicted value of the ventricular impedance change in the cardiac systole extracted by the second detection unit 120 (S250) desirable.

Generally measured ventricular impedance changes have a positive correlation to the volume change of the heart, but for patients transplanted with ventricular assist device 20, the volume change of the heart is simply the amount of blood moving from the left heart to the aorta, The impedance of the ventricular assist device 20 is not related to the generation of the impedance due to the ventricular assist device 20 but the amount of blood that is inhaled and returned to the aorta and the impedance due to the blood are not considered, It is difficult to distinguish whether it is due to normal cardiac contraction or not.

Therefore, in this step, the ventricular impedance change value extracted through the ventricular impedance change value extracting step (S100) is compared with the predicted value of the ventricular impedance change extracted through the ventricular impedance change predicted value extracting step (S200), so that the change of the ventricular impedance changes the ventricular impedance change If it is less than half the predicted value, it is judged that abnormal heart contraction has occurred.

In other words, when the ratio of the ventricular impedance change value to the predicted value of the ventricular impedance change is less than 0.5, it is judged that the contraction of the ventricle is lower than the actual predicted value, so that additional heart disease due to abnormal contraction occurred The result of the comparison between the change in the ventricular impedance and the predicted value of the change in the ventricular impedance is shown in FIG. 12. As shown in FIG. 12, in the two portions determined as the reference threshold value of 0.5 And arrhythmia such as premature ventricular contraction (PVC) occurred.

As a result, the cardiac function monitoring method of a patient transplanted with the ventricular assist device 20 of the present invention is not limited to the basic blood flow path of the heart in patients implanted with the ventricular assist device 20 due to the occurrence of heart disease By monitoring the cardiac function by comparing the change in the ventricular impedance of the cardiac systole measured in consideration of the blood flow on the separate bypass path formed through the ventricular assist device 20 and the predicted value of the predicted value of the ventricular impedance change of the systolic heart, It is possible to perform more accurate and realistic cardiac function monitoring so that the onset of additional heart disease due to implantation of the ventricular assist device 20 can be diagnosed early.

The embodiments disclosed in the present invention are not intended to limit the scope of the present invention but to limit the scope of the technical idea of the present invention. The scope of protection is to be construed in accordance with the following claims, and all technical ideas within the scope of equivalents thereof should be construed as being included in the scope of the present invention.

A: Aorta
LV: Left ventricle
10: electrode 15: lead
20: ventricular assist device 25: connection line
100: Cardiac function monitoring device
110: first detection unit
120: second detection unit
130: Inspection unit

Claims (6)

CLAIMS 1. A method for detecting abnormal cardiac contraction in a patient transplanted with a ventricular assist device comprising an implantable electrode capable of being installed on the aorta and the aorta,
An A step of extracting a change value of a ventricular impedance in a cardiac systole based on first information on a ventricular impedance measured from the electrode and second information on an electrocardiogram;
Extracting a predicted value of a ventricular impedance change in a cardiac systolic based on third information on a blood suction time and an amount of suction per hour measured through the ventricular assist device and second information measured through the step A; And
And a step C for monitoring cardiac function of the patient by comparing the ventricular impedance change value extracted through the step A and the ventricular impedance change predictive value extracted through the step B,
A method for monitoring cardiac function in a patient transplanted with a ventricular assist device.
The method according to claim 1,
The step C is a step of determining that an abnormal heart contraction occurs when the change in the ventricular impedance extracted through the step A is equal to or less than half of the predicted value of the ventricular impedance variation extracted through the step B,
A method for monitoring cardiac function in a patient transplanted with a ventricular assist device.
The method of claim 1,
In the step A,
A-1 step of obtaining the first information and the second information from the electrode;
A-2 step of extracting an impedance at a time of depolarization of the ventricle based on the first information and the second information obtained through the step A-1;
A-3 step of extracting the impedance at the time of repolarization of the ventricle based on the first information and the second information obtained through the step A-1; And
And a step A-4 of calculating a change in the ventricular impedance in the cardiac systolic through the difference between the impedance extracted in the step A-2 and the impedance extracted in the step A-3.
A method for monitoring cardiac function in a patient transplanted with a ventricular assist device.
The method of claim 3,
In the step B,
B-1 step of acquiring the third information from the ventricular assist device;
Based on the third information obtained in the step B-1, the second information obtained in the step A-1, and the fourth information on the average cardiac output per hour of the patient, Step B-2 for measuring volume reduction; And
B-3 step of predicting the degree of change in the ventricular impedance in the systolic heart based on the ventricular volume reduction measured in the step B-2 and extracting the predicted value of the ventricular impedance change; &Lt; RTI ID = 0.0 &gt;
A method for monitoring cardiac function in a patient transplanted with a ventricular assist device.
5. The method of claim 4,
In the step B,
And a B-4 step of filtering the predicted value of the ventricular impedance change extracted through the step B-3 through a moving average filter
A method for monitoring cardiac function in a patient transplanted with a ventricular assist device.
5. The method of claim 4,
The amount of ventricular volume reduction in the cardiac systole of the step B-2 is measured using the following equation (1)
A method for monitoring cardiac function in a patient transplanted with a ventricular assist device.
[Equation 1]

(Wherein, _{R -T} LV volume decrease _period is ventricular volume decrease in systolic heart, Total Flow is the mean cardiac output, _VAD Inflow per hour blood intake, HR is the heart rate, t _{RT period} of a ventricular assist device ventricular assist device per hour Lt; / RTI &gt;

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