JP2014023869A - Cardiac stimulation examining system, and cardiac stimulation examining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cardiac stimulation examining apparatus capable of obtaining an accurate electrocardiographic waveform in a short time even if an afterpotential of a large value occurs.SOLUTION: An afterpotential estimation part 150 estimates an afterpotential S(t12) at a second point of time later than a first point of time, on the basis of both biological impedance calculated by a biological impedance calculation part 140 and detected voltage V(t11) at the first point of time detected by a voltage detection part 120. An electrocardiographic waveform calculation part 160 obtains an electrocardiographic waveform on the basis of a difference between detected voltage V(t12) at the second point of time detected by the voltage detection part 120 and the afterpotential S(t12) at the second point of time estimated by the afterpotential estimation part 150.

Description

  The present invention relates to a cardiac stimulation examination system and a cardiac stimulation examination method.

  Conventionally, in order to test whether the heart's stimulation conduction system is normal or not, an electrical stimulation pulse is output to an electrode catheter mounted on a living body, and the biological reaction obtained at that time is obtained via the electrode catheter. Thus, there is a cardiac stimulation examination system that obtains an electrocardiogram waveform (intracardiac electrogram). This type of cardiac stimulation inspection system is disclosed in Patent Documents 1 to 3, for example.

  Briefly described, the cardiac stimulation examination system includes a cardiac electrical stimulation apparatus that outputs electrical stimulation pulses to the electrode catheter, and a cardiac catheter examination apparatus that measures an electrocardiographic waveform based on the voltage of the electrode catheter. The cardiac electrical stimulation device intentionally induces an arrhythmia or stops the arrhythmia by applying an electrical stimulation pulse through an electrode catheter. The cardiac catheter inspection device measures an electrocardiographic waveform by acquiring a response voltage from a living body that appears immediately after a stimulus is applied by the cardiac electrical stimulation device via an electrode catheter.

  Here, as disclosed in Patent Document 1 and Patent Document 2, when an electrical stimulation pulse is applied to a living body by a cardiac electrical stimulation device, a post-potential due to polarization is generated. The post-potential becomes a large value immediately after the electrical stimulation pulse is applied, but gradually decreases due to discharge (discharge). When the posterior potential is very large compared to the ECG waveform, the ECG waveform is masked by the posterior potential, so the ECG waveform can actually be acquired because the posterior potential is attenuated to a sufficiently small value. This is because the influence of the mask due to the rear potential is reduced.

U.S. Pat. No. 4,498,478 JP 2002-516732 A JP-A-6-154182

  By the way, the magnitude of the post-potential is determined by the amplitude and pulse width of the electrical stimulation pulse. That is, as the amplitude increases and the pulse width increases, the rear potential increases. When the post-potential increases, naturally, the time until an electrocardiographic waveform can be acquired also increases.

  At present, the electrical stimulation pulse has a voltage of several volts to several tens of volts and a pulse width of about 10 [msec]. Incidentally, the voltage of the electrocardiographic waveform to be measured is several millivolts.

  At present, for example, the electrocardiographic waveform has a baseline level of 50 [msec] or less within ± 1 [mV] under a stimulation condition where the electrical stimulation pulse has an amplitude of 5 V and a pulse width of 1 [msec]. The accuracy is required as the performance of the cardiac stimulation examination system, and is actually realized.

  By the way, depending on the part of the heart to be inspected, there is a part where the response to the electrical stimulation is dull. In order to inspect such a part, it is effective to increase the amplitude and pulse width of the electrical stimulation pulse. . For example, an electrical stimulation pulse having a large energy such as an amplitude of 30 V and a pulse width of 10 [msec] may be used.

  When an electrical stimulus of such a large energy is given, naturally the posterior potential is also increased, and the time until the posterior potential is attenuated to such an extent that an electrocardiographic waveform can be acquired also becomes longer. On the other hand, usually, the time from application of a certain electrical stimulation pulse to application of the next electrical stimulation pulse (that is, the interval between electrical stimulation pulses) is determined to be 100 [msec], for example. For this reason, the electrocardiogram waveform must be measured within 100 [msec]. However, if the post-potential is large, the electrocardiogram waveform may not be measured within that time.

  A method of extracting the electrocardiogram by removing the posterior potential with a high-pass filter is also conceivable, but even in this case, if the posterior potential is at a much higher level than the electrocardiogram waveform, the accuracy of It takes a long time to obtain a good filtering result.

  An object of the present invention is to provide a cardiac stimulation examination system and a cardiac stimulation examination method capable of obtaining an accurate electrocardiographic waveform in a short time even when a large potential after potential is generated.

One aspect of the cardiac stimulation testing system of the present invention is:
A cardiac stimulation examination system for measuring an electrocardiogram waveform by applying an electrical stimulation pulse to a living body via an electrode catheter, and obtaining a response voltage from the living body that appears thereafter via the electrode catheter,
An electrical stimulation pulse generation unit that generates an electrical stimulation pulse and outputs the electrical stimulation pulse to the electrode catheter mounted on a living body;
A voltage detection unit for detecting a voltage appearing in the electrode catheter after an electrical stimulation pulse is output to the electrode catheter;
Based on the voltage of the electrode catheter and the current of the electrode catheter, a bioimpedance calculation unit that calculates the impedance of the living body to which the electrode catheter is attached;
Based on the bioelectrical impedance calculated by the bioelectrical impedance calculation unit and the detection voltage at the first time detected by the voltage detection unit, a post-potential at a second time after the first time A post-potential estimation unit for estimating
An electrocardiogram that obtains an electrocardiographic waveform based on the difference between the detected voltage at the second time point detected by the voltage detector and the post-potential at the second time point estimated by the post-potential estimator. A shape calculator,
It comprises.

One aspect of the cardiac stimulation test method of the present invention is:
A cardiac stimulation examination method used in a cardiac stimulation examination system for measuring an electrocardiogram waveform by applying an electrical stimulation pulse to a living body via an electrode catheter and acquiring a response voltage from the living body appearing thereafter via the electrode catheter Because
Outputting electrical stimulation pulses to the living body;
Calculating the impedance of the living body;
Estimating a postpotential of a second time point after the first time point based on the calculated bioelectrical impedance and the detection voltage of the electrode catheter at the first time point;
Obtaining an electrocardiographic waveform based on the difference between the detected voltage of the electrode catheter at the second time point and the estimated postpotential of the second time point;
including.

  According to the present invention, an accurate electrocardiographic waveform can be obtained in a short time without waiting until the value of the post-potential becomes sufficiently small even when a large post-potential is generated.

FIG. 1A is an equivalent circuit for explaining a principle configuration of a cardiac stimulation examination system, FIG. 1A is a diagram showing a state at the time of stimulation, and FIG. 1B is a diagram showing a state at the time of discharge. The figure which shows the mode of the measurement voltage V obtained by a cardiac stimulation test | inspection system The figure which shows the whole structure of a cardiac stimulation inspection system Block diagram showing the basic configuration of the cardiac stimulation test system

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(1) Principle Before describing the configuration of the embodiment, the principle of the present invention will be described.

  1A and 1B are equivalent circuits for explaining the principle configuration of the cardiac stimulation examination system. FIG. 1A shows a state during stimulation, and FIG. 1B shows a state during discharge.

  The equivalent circuit of FIG. 1 is divided into a circuit side and a living body side with electrode catheters (electrode leads) T1 and T2 attached to the living body as a boundary. The circuit side is the cardiac stimulation test system 10, and the living body side is the living body model 20.

  The cardiac stimulation test system 10 can be represented by using an electrical stimulation pulse generation unit 11, a charge storage capacitor Ca, an internal resistance Ra, and switches 12 and 13. The biological model 20 can be represented using a resistance Rs and a capacitor Cs.

  At the time of stimulation shown in FIG. 1A, after the switch 12 is connected to the terminal a side and the switch 13 is turned OFF, the stimulation pulse generated by the electrical stimulation pulse generation unit 11 is accumulated by the charge storage capacitor Ca. , And supplied to the biological model 20.

  On the other hand, at the time of discharging shown in FIG. 1B, the switch 12 is connected to the terminal b side and the switch 13 is turned on, whereby the charge accumulated in the capacitor Cs of the biological model 20 is discharged. At the time of this discharge, the electrocardiographic waveform is measured by measuring the voltage V between the electrode leads T1 and T2.

  FIG. 2 shows the state of the measurement voltage V obtained by the cardiac stimulation test system 10. The period from the time point t1 to the time point t2 is a period in which the cardiac stimulation inspection system 10 is in the state of FIG. 1A, and the period from the time point t3 to the time point t4 is a period in which the cardiac stimulation inspection system 10 is in the state of FIG. Yes, the period from the time point t4 to the time point t5 is a period in which the cardiac stimulation test system 10 is in the state of FIG. 1A. The cardiac stimulation examination system 10 measures the voltage V between the electrode leads T1 and T2 during the discharge period while repeating stimulation and discharge in this way.

  The voltage during the discharge period decays with time. Here, the voltage in the discharge period includes an afterpotential generated due to polarization due to electrical stimulation and an electrocardiographic waveform that is an evoked reaction of the heart due to electrical stimulation. Of these, the electrocardiogram waveform is the waveform to be measured. Immediately after the stimulation, the value of the posterior potential is very large compared to the electrocardiogram waveform, and the posterior potential masks the electrocardiogram waveform. Therefore, conventionally, the electrocardiographic waveform is measured after the value of the post-potential becomes sufficiently small. Actually, the dynamic range of the measurement system is set to the order of several millivolts, and the electrocardiogram waveform (response waveform from the heart) that appears in the order of several millivolts is measured after the value of the back potential becomes sufficiently small. It has become.

  On the other hand, in the present invention, the post-potential decay curve at the time of discharge is estimated by calculation, and the post-potential is removed by calculating the difference value between the decay curve estimated value and the actual measured value. Get an electrocardiogram. As a result, an electrocardiographic waveform can be obtained without waiting until the value of the post-potential becomes sufficiently small.

The attenuation curve estimated value S (t) can be estimated by the following equation.

  Here, A in the formula (1) indicates the start voltage of the rear potential or the maximum voltage of the rear potential as shown in FIG. 2 (here, the maximum voltage means that the absolute value of the voltage is maximum). . Note that the value of A does not have to be the starting voltage of the post-potential. However, if the value of A is the starting voltage of the post-potential, an electrocardiographic waveform can be obtained in the shortest time.

  τ is the time constant of the decay curve S (t), and this time constant τ is determined by the total impedance of the bioelectrical impedance and the impedance of the discharge circuit (Ca, Ra in FIG. 1). The bioelectrical impedance Z can be obtained from the voltage V and the current I between the electrode catheters T1 and T2. That is, it is obtained by Z = V / I. Next, the time constant τ can be obtained by adding the impedance of the discharge circuit to the bioelectrical impedance. Thus, the attenuation curve estimated value S (t) when the time t has elapsed from the time t3 can be obtained from the measurement voltage A at a certain time t3 and the bioelectrical impedance Z. Since this attenuation curve estimated value S (t) is calculated based on the measured voltage A at the time when the ratio of the rear potential to the electrocardiogram waveform is very large, it can be approximated as the estimated value of the rear potential. Here, since the bioimpedance Z varies depending on the variation of the mounting position of the electrode catheter, it is desirable to obtain it every time a stimulus is applied.

  Then, the post-potential component included in the measurement value V (t) is removed by subtracting the post-potential estimation value S (t) from the actual measurement value V (t) when the time t has elapsed from the time point t3. And an electrocardiogram waveform can be obtained. As a result, an electrocardiographic waveform can be obtained immediately after the post-potential appears without waiting for the post-potential to sufficiently attenuate.

(2) Configuration FIG. 3 shows the overall configuration of the cardiac stimulation examination system. The cardiac stimulation examination system 100 includes a cardiac electrical stimulation apparatus 102 and a cardiac catheter examination apparatus 103. The cardiac electrical stimulation device 102 generates an electrical stimulation pulse and outputs the electrical stimulation pulse to the electrode catheter 101 (101-1 to 101-n) attached to the living body. The cardiac catheter test apparatus 103 measures an electrocardiographic waveform based on the voltage of the electrode catheter 101 (101-1 to 101-n). In addition, the cardiac electrical stimulation device 102 and the cardiac catheter test device 103 are connected by a cable so that they can transmit and receive each other's information.

  FIG. 4 is a block diagram showing a basic configuration of the cardiac stimulation examination system 100. As shown in FIG. FIG. 4 shows only characteristic elements in the present embodiment. 4, the electrical stimulation pulse generation unit 110 is provided in the cardiac electrical stimulation device 102, and the electrocardiographic waveform calculation unit 160 is provided in the cardiac catheter examination device 103. The voltage detection unit 120, the current detection unit 130, the bioelectrical impedance calculation unit 140, and the posterior potential estimation unit 150 may be provided on the cardiac electrical stimulation device 102 side or may be provided on the cardiac catheter test device 103 side. Regardless of which side is provided, the result information may be transmitted and received between the apparatuses.

  The electrical stimulation pulse generation unit 110 generates an electrical stimulation pulse and outputs the electrical stimulation pulse to the electrode catheter 101 attached to the living body. The electrical stimulation pulse generation unit 110 corresponds to the part indicated by reference numeral 11 in FIG.

  The voltage detection unit 120 detects a voltage that appears in the electrode catheter 101 after the electrical stimulation pulse is output to the electrode catheter 101. The voltage detector 120 detects the voltage between the electrode catheters T1 and T2 in FIG. 1, for example. Here, the voltage detection unit 120 is configured to have a dynamic range capable of detecting the maximum value of the post-potential that is assumed to occur. In other words, the voltage detector provided in a general cardiac stimulation examination system is configured to have a dynamic range of several millivolts for the purpose of detecting an electrocardiographic waveform having a level of several millivolts. The voltage detection unit 120 of the present embodiment is configured to have a wide dynamic range so that the maximum value of the rear potential can be detected. In practice, the voltage detector 120 is configured to have a dynamic range of several volts. The voltage detection unit 120 digitally converts the detected voltage value and outputs it.

  The current detection unit 130 detects a current flowing through the electrode catheter 101. The current detection unit 130 can be realized, for example, by connecting a current detection resistor whose one end is grounded to the electrode catheter T2 of FIG. The current detection unit 130 digitally converts the detected current value and outputs it.

  The bioelectrical impedance calculation unit 140 calculates the impedance of the living body to which the electrode catheter 101 is attached based on the voltage of the electrode catheter 101 and the current of the electrode catheter 101. That is, the impedance of the biological model 20 shown in FIG. 1 is calculated.

The post-potential estimation unit 150 calculates a time constant τ from the total impedance of the bioelectrical impedance Z calculated by the bioelectrical impedance calculation unit 140 and the impedance of the discharge circuit. Then, the post-potential estimation unit 150 uses the time constant τ and the detection voltage V (t11) detected at the first time point t11 detected by the voltage detection unit 120 to change the first potential after the first time point t11. The potential after time t12 of 2 is estimated. In other words, the post-potential estimation unit 150 is based on the bioelectrical impedance Z calculated by the bioelectrical impedance calculation unit 140 and the detection voltage V (t11) at the first time point t11 detected by the voltage detection unit 120. The post-potential of the second time point t12 after the first time point t11 is estimated. Here, in the above-described principle section, the case where the first time point t11 is the time point t3 in FIG. 2, that is, the case where the first time point t11 is the start point of the rear potential has been described. Therefore, the detection voltage V (t11) at the first time point t11 corresponds to the voltage A in FIG. However, the first time t11 does not necessarily need to coincide with the start time of the post-potential. Specifically, the post-potential estimation unit 150 estimates the post-potential S (t12) of the second time point t12 by the following formula using Formula (1).

  The electrocardiogram waveform calculation unit 160 detects the detected voltage V (t12) at the second time point t12 detected by the voltage detection unit 120 and the post-potential S (t12) of the second time point t12 estimated by the post-potential estimation unit 150. ) And an electrocardiogram waveform is obtained based on the difference. The electrocardiogram waveform obtained by the electrocardiogram waveform calculation unit 160 is output to the monitor and / or printer as an intracardiac electrocardiogram.

  By doing so, an electrocardiographic waveform can be obtained without waiting until the value of the post-potential becomes sufficiently small. Therefore, even when the electrical stimulation pulse generator 110 applies electrical stimulation with large energy and the starting voltage of the post-potential increases, the electrocardiographic waveform can be recognized and obtained within a predetermined time. .

As described above, according to the present embodiment,
<I> Calculate the impedance of the living body,
<Ii> Based on this bioimpedance and the detection voltage V (t11) of the electrode catheter 101 (T1, T2) at the first time point t11, the post-potential of the second time point t12 after the first time point t11. Estimate
<Iii> Based on the difference between the detected voltage V (t12) of the electrode catheter 101 (T1, T2) at the second time point t12 and the post-potential S (t12) at the second time point t12, Get shape,
By doing so, an accurate electrocardiographic waveform can be obtained in a short time without waiting until the value of the post-potential becomes sufficiently small even when a large post-potential is generated.

  In the above-described embodiment, the impedance of the living body to which the electrode catheter 101 (T1, T2) is attached is based on the voltage of the electrode catheter 101 (T1, T2) and the current of the electrode catheter 101 (T1, T2). However, it is not always necessary to directly detect the voltage and current from the electrode catheter 101 (T1, T2). The voltage and current corresponding to the voltage and current are detected by the cardiac electrical stimulation device 102 or the cardiac catheter test device. What is necessary is just to acquire in any part of 103 inside.

  In the above-described embodiment, the case where the estimation formulas (1) and (2) are used has been described. However, other estimation formulas may be used. In short, based on the bioelectrical impedance calculated by the bioelectrical impedance calculation unit 140 and the detection voltage at the first time detected by the voltage detection unit 120, the second time after the first time is calculated. An estimation formula that can estimate the post-potential may be used.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and can be changed without departing from the gist thereof.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to, for example, a cardiac stimulation test apparatus for obtaining an intracardiac electrocardiogram.

DESCRIPTION OF SYMBOLS 10,100 Cardiac stimulation test system 11,110 Electrical stimulation pulse generation part 12,13 Switch 20 Biological model 101, T1, T2 Electrode catheter 102 Cardiac electrical stimulation apparatus 103 Cardiac catheter test apparatus 120 Voltage detection part 130 Current detection part 140 Bioimpedance Calculation unit 150 Post-potential estimation unit 160 ECG waveform calculation unit

Claims (4)

A cardiac stimulation examination system for measuring an electrocardiogram waveform by applying an electrical stimulation pulse to a living body via an electrode catheter, and obtaining a response voltage from the living body that appears thereafter via the electrode catheter,
Generating an electrical stimulation pulse and outputting the electrical stimulation pulse to the electrode catheter mounted on a living body;
A voltage detection unit for detecting a voltage appearing in the electrode catheter after an electrical stimulation pulse is output to the electrode catheter;
Based on the voltage of the electrode catheter and the current of the electrode catheter, a bioimpedance calculation unit that calculates the impedance of the living body to which the electrode catheter is attached;
Based on the bioelectrical impedance calculated by the bioelectrical impedance calculation unit and the detection voltage at the first time detected by the voltage detection unit, a post-potential at a second time after the first time A post-potential estimation unit for estimating
An electrocardiogram that obtains an electrocardiographic waveform based on the difference between the detected voltage at the second time point detected by the voltage detector and the post-potential at the second time point estimated by the post-potential estimator. A shape calculator,
A cardiac stimulation examination system comprising: The detection voltage at the first time point is a start voltage of the post-potential.
The cardiac stimulation test system according to claim 1. The voltage detection unit has a dynamic range in which the maximum value of the rear potential can be detected.
The cardiac stimulation test system according to claim 1 or 2. A cardiac stimulation examination method used in a cardiac stimulation examination system for measuring an electrocardiogram waveform by applying an electrical stimulation pulse to a living body via an electrode catheter and acquiring a response voltage from the living body appearing thereafter via the electrode catheter Because
Outputting electrical stimulation pulses to the living body;
Calculating the impedance of the living body;
Estimating a postpotential of a second time point after the first time point based on the calculated bioelectrical impedance and the detection voltage of the electrode catheter at the first time point;
Obtaining an electrocardiographic waveform based on the difference between the detected voltage of the electrode catheter at the second time point and the estimated postpotential of the second time point;
A method for examining cardiac stimulation.

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