JPH11151304A - Cardiac pacemaker - Google Patents

Abstract

(57) [Summary] [Problem] To appropriately control a heartbeat according to a state required for a heart function. SOLUTION: A pulse wave detecting unit 10 for detecting a pulse wave waveform,
First, the systole of the heart is specified from the pulse wave waveform, and the ejection time t _4, which may be equivalent to the time corresponding to the systole, is obtained. The rising time t ₁ of the ejection wave, which is a waveform indicating the pressure characteristic of the arterial vascular system accompanying the pumped blood, is obtained. Third, the normalization time is obtained by normalizing the rising time t ₁ with the ejection time t _4. t ₁ /
t comprises ₄ systolic particular, the waveform analyzer 20 to determine the, on the basis of the normalized time t ₁ / t _4, the signal generating unit 30a for generating a pacemaker signal serving pacing pulses of the heart.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention analyzes a waveform showing a pressure characteristic of an arterial vasculature associated with blood pumped out of a heart from a pulse wave waveform corresponding to a systole of the heart, and converts the waveform. The present invention relates to a cardiac pacemaker that determines a prescribed index and controls the heart rate of a patient based on the index.

[0002]

2. Description of the Related Art Generally, in a normal heart, the sinus node located at the upper surface of the junction between the superior vena cava and the right atrium generates regular stimulation for pacing. And this stimulus
First, the atrial muscle is excited and contracted, and is conducted to the working myocardium of the ventricle via the intra-atrial conduction path and the atrioventricular node, causing the ventricle to contract. However, the conduction of the stimulus at the atrioventricular node is very slow, 10 cm per second, so that the ventricle contracts after the atrial contraction.

In a complete atrioventricular block, stimulation is not transmitted from the atrium to the ventricle, and thus, in theory, only the inside of the atrium repeatedly contracts. By the supplemental rhythm, a heart rate (heart rate) of about 20 to 40 beats / minute is maintained. In general, when the heart rate decreases, the amount of stroke per stroke increases accordingly, and a kind of compensation function is performed such that the amount of blood pumped per unit time becomes a certain amount or more. However, when the number of beats falls below 40 beats / minute, the compensation function no longer works. For this reason, a sufficient amount of blood may not be secured, causing not only dizziness and loss of consciousness due to cerebral ischemia, but also the risk of maintaining life. In the case of the sinus dysfunction syndrome, the heartbeat is lost for several seconds to nearly 10 seconds due to sinus arrest, sinus bradycardia, and sinoatrial block, so that blood flow to the brain may be temporarily interrupted. However, even in such cases, it is necessary to secure a minimum heart rate.
For this reason, a cardiac pacemaker is applied.

[0004] On the other hand, in a healthy person, the heart rate decreases during rest and increases during exercise. Here, if the heart rate by the cardiac pacemaker is constant, it becomes excessive at rest,
Conversely, it is too small during exercise, so it is hard to say that it is physiological. Therefore, a conventional cardiac pacemaker secures a minimum heart rate and performs cardiac pacing according to a physiological condition. Such a cardiac pacemaker first detects a signal indicating a physical activity from a living body, as described in Japanese Unexamined Patent Publication No. Hei 3-4289 and Japanese Examined Patent Publication No. Hei 6-47025. Then, a physiological variable, generally a respiratory rate (respiratory rate) is determined from the detected signal,
Then, a pacing pulse (pacemaker signal) as a stimulation signal to the heart is generated in accordance with the physiological variable. In the above publication, physiological acceleration, body acceleration, body temperature, pH, PO _2, etc. are listed as physiological variables.

[0005]

However, when examining the relationship between the state of physical activity obtained from physiological variables and the state of cardiac function required in the living body, it is found that the two do not always correspond to each other. Conceivable. For example, when the respiratory rate is decreased by consciously taking a deep breath, the state of physical activity obtained from the respiratory rate as a physiological variable changes, but the state of cardiac function required in the living body does not change. Because it is considered. Therefore, the conventional cardiac pacemaker only controls the heartbeat according to the state of the physical activity of the living body, and does not control the heartbeat according to the state required for the heart function. Did not do properly.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cardiac pacemaker capable of appropriately controlling a heartbeat according to a state required for cardiac function. It is in.

[0007]

According to the present invention, there is provided a pulse wave detecting means for detecting a pulse wave waveform, and a systole specifying means for specifying a systole of the heart from the pulse wave waveform. And, among the systolic pulse wave waveforms specified by the systole specifying means, a waveform indicating a pressure characteristic of the arterial vascular system associated with blood pumped from the heart is analyzed, and an index defining the waveform is obtained. It is characterized by comprising analyzing means for calculating, and signal generating means for generating a pacemaker signal of the heart based on the index calculated by the analyzing means.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <1: Theoretical Basis> First, before describing the cardiac pacemaker according to the embodiment, the theoretical basis in the present invention will be described.

First, the relationship between the motion of the heart and the blood pressure waveform will be described. FIG. 6A shows an electrocardiographic waveform. In general, a portion from point R to an end point U of a T wave in the figure is called a ventricular systole, and a portion from point U to the next R point is ventricular diastole. Is said to be a period. Here, during the ventricular systole, the contraction of the ventricle does not occur uniformly, but becomes slow as the contraction progresses from the outside to the inside.
Therefore, the blood pressure waveform at the aortic root immediately after the heart has an upwardly convex shape during the period from opening to closing of the aortic valve, as shown in FIG.

Here, it goes without saying that the heart pumps blood by repeating contraction and expansion. Here, the time during which blood flows out of the heart by one cycle of contraction and expansion, that is, the time from opening of the aortic valve to closing, is referred to as ejection time. The ejection time tends to become shorter as the beat rate becomes higher due to exercise or the like. This is the result of the release of catecholamines such as adrenaline, which means that the contractile force of the heart muscle is increased. In addition, as the ejection time becomes longer, the stroke volume flowing out of the heart tends to increase due to one cycle of contraction and expansion. Now, when a person exercises, etc., it is necessary to supply a large amount of oxygen to the heart muscle and skeletal muscles, so the product of the pulse rate and the output volume,
That is, the amount of blood pumped out of the heart per unit time increases. Here, as the number of beats increases, the ejection time becomes shorter, and consequently the amount of ejection becomes smaller. However, since the rate of increase in the number of beats exceeds the rate of decrease in the amount of stroke, the product of the number of beats and the amount of stroke increases as a whole.

Next, at the aortic root, a blood pressure waveform (FIG. 6)
FIG. 3C shows an example of a pulse wave waveform given to a peripheral portion (for example, a radial artery) by (b). This shape is caused by the first ejection of blood from the heart, which causes a first wave called an ejection wave, and subsequently, a regression wave due to reflection at a blood vessel bifurcation near the heart. A second wave occurs,
After this, it is considered that a notch is produced due to the aortic valve closure, and a third wave called a notch wave appears. Strictly speaking, there is a slight time lag from the R point of the electrocardiographic waveform to the opening of the aortic valve, but in the pulse waveform, the area from the lowest blood pressure value to the notch corresponds to the ventricular systole, It can be considered that the period from to the point where the blood pressure value is lowest in the next cycle corresponds to the ventricular diastole, and similarly, the period corresponding to the ventricular systole in the pulse wave waveform can be considered to be the ejection time. Here, in the pulse wave waveform, the point corresponding to the aortic valve release is the minimum minimum point of the blood pressure value, and the point corresponding to the aortic valve closure in the pulse wave waveform is the first point from the minimum point in the time series. This is the third minimum point that appears thirdly, and is the second minimum point from the minimum minimum point in terms of the blood pressure value. Although the pulse wave waveform shown in FIG. 3C is actually delayed in time from the aortic blood pressure waveform shown in FIG. 3B, this time delay is ignored here for the sake of explanation. The phases are aligned.

Next, the pulse waveform shown in FIG. The pulse wave waveform detected in the peripheral part is, as it were, a blood pressure wave that has passed through a closed system composed of a pulsatile pump heart and a vascular system as a conduit. Therefore, first, the pump function of the heart, that is, In addition to being defined by the cardiac function status, secondly, it is affected by blood vessel diameter, blood vessel contraction / extension, blood viscosity resistance, and the like. Therefore, by detecting and analyzing the pulse wave waveform, it is possible to evaluate the state of cardiac function, including the state of the arterial vasculature in the subject (patient).
it is conceivable that.

Here, in order to evaluate the state of cardiac function, it is examined which part of the pulse waveform should be focused. First, as described above, since the contraction of the ventricle does not occur uniformly, the blood waveform pumped from the heart becomes maximum during the ventricular systole as shown in FIG.
On the other hand, blood pumped from the heart reaches the peripheral part under the influence of the arterial vasculature. For this reason, it is considered that the ejection wave shown in FIG. 9C is a waveform that appears in the peripheral portion due to the influence of the arterial vasculature on the blood pressure wave pumped by the contraction of the ventricle. That is, the ejection wave is a waveform indicating the pressure characteristics of the arterial vasculature associated with blood pumped by contraction of the ventricle. Therefore, if the heart function fluctuates, the pressure wave of the pumped blood changes, and the effect first appears in the ejection wave of the pulse waveform, so the heart function state is evaluated by the pulse waveform. To do so, attention should be paid to the ejection wave that appears first during a period corresponding to the ventricular systole.

Next, the characteristics of the blood pressure wave emitted by the contraction of the ventricle will be considered. In general, when the heart enlarges, even if the ventricle contracts, its inner volume does not change much. For this reason, the blood is no longer sharply pumped out of the heart, and it is considered that the rising time of the ejection wave is prolonged. Similarly, even if the contractile force of the myocardium decreases for some reason, the rise time of the ejection wave is considered to be prolonged. Therefore, in order to evaluate the cardiac function state by the pulse waveform, it is considered that it is effective to use, as an index, the rise time of the ejection wave that appears first in a period corresponding to the ventricular systole.

However, it is generally considered that the pressure characteristics of the pumped blood are different for each individual. Therefore, regardless of the evaluation for the same subject, the mutual evaluation for a plurality of subjects is not considered. Not considered appropriate. On the other hand, the ejection volume of the blood flowing out of the heart by one cycle of contraction and expansion depends on the ejection time as described above. It is considered to be affected by the ejection time. Therefore, for the rise time of the ejection wave in the pulse wave waveform, a value (normalized time) normalized by the ejection time that can be considered as the time corresponding to the ventricular systole,
It is considered optimal to use it as an index for evaluation.

Here, the effectiveness of this index will be examined with reference to the actual measurement results. FIG. 8 shows the number of beats when the heart transplanter and the healthy subject take a sitting posture, a supine posture, and an upright posture, respectively, and the ejection time t ₄ for the rising time t ₁ of the ejection wave in the pulse wave waveform. Value t ₁ /
_{5 is} a table showing t ₄ [%], respectively, based on the results of measurements in Australia by Dr. Kazuo Kamibaba, one of the inventors of the present application. As shown in this figure, the pulse rate of the healthy person corresponds to the load in each posture, and has the highest value in the upright posture with the highest load. As described above, the pulse rate changes according to the amount of blood to be pumped out of the heart, and thus can be said to be an index of the contractile force required for the myocardium at that time. However, as shown in the figure, the heart rate of the heart transplant recipient is almost constant irrespective of each posture. This phenomenon also applies to those who have trouble in conduction of stimulation to the atria and ventricles and have to rely on a pacemaker to control the heartbeat. Thus, for those who cannot control the heart rate according to the amount of blood to be pumped out of the heart, the heart rate is, of course, not sufficient as an indicator of the contractile force required of the myocardium.

On the other hand, the index used in this embodiment, that is, the normalized rise time t ₁ / t ₄ of the ejection wave in the pulse wave waveform is not only in the healthy person but also in the heart transplant person. It has a change characteristic similar to the pulse rate of a healthy person. For this reason, the rising normalization time t ₁ / t ₄ of the ejection wave is extremely useful as an index for evaluating a cardiac function state not only in a healthy person but also in a person who cannot control the pulse rate such as a heart transplanter. It turns out that it is.

By the way, the present inventor simulates the behavior of the arterial vascular system from the aortic root to the peripheral part by using an electric model in order to determine the state of circulation (blood circulation) in a non-invasive manner. A technique for approximately calculating parameters related to circulatory dynamics such as viscous drag and compliance has been proposed (Japanese Patent Laid-Open No. 6-205747: Title of invention "Pulse wave analyzer", PCT / JP96 / 03211: Title of invention) Refer to "Biological condition measuring device"). In short, this technology is based on the fact that when an electrical signal corresponding to the pressure wave at the aortic root of a subject is given to an electrical model simulating the behavior of the arterial vasculature, the response waveform is actually detected. By determining the value of each element constituting the electrical model so as to match the obtained pulse waveform, the parameters of the circulatory dynamics corresponding to each element are approximately calculated. As the electrical model, there are a four-element lumped parameter model as shown in FIG. 9A and a five-element lumped parameter model as shown in FIG. 9B. In particular, regarding the latter five-element lumped parameter model, among the factors that determine the behavior of the circulatory dynamics of the human body, the inertia due to blood in the central part and the blood vessel due to blood viscosity in the central part used in the four-element lumped parameter model Resistance (viscous resistance), peripheral blood vessel compliance (viscoelasticity), and peripheral blood vessel resistance (viscous resistance), these parameters are added to the above four parameters. Is modeled as an electric circuit.

Hereinafter, the correspondence between each element constituting the lumped parameter model and each parameter will be described. Capacitance C _c : aortic compliance [cm ⁵ / dyn] Electric resistance R _c : vascular resistance due to blood viscosity at central part of arterial system [dyn · s / cm ⁵ ] Inductance L: inertia due to blood at central part of arterial system [Dyn · s ² / cm ⁵ ] Capacitance C: vascular compliance at the peripheral part of the arterial system [cm ⁵ / dyn] Electric resistance R _p : vascular resistance due to blood viscosity at the peripheral part of the arterial system [dyn · s / cm] ⁵ ]

The currents i and i flowing through the lumped parameter model
_p, i _c, i _s is blood flowing through the respective units, each corresponding [cm ⁵ /
s]. Among them, the current i corresponds to the aortic flow, current i _s is equivalent to blood flow pumped out from the left ventricle. The input voltage e corresponds to the left ventricular pressure [dyn / cm ² ], and the voltage v ₁ corresponds to the pressure [dyn / cm ² ] at the aortic root. Further, the terminal voltage v _p of the capacitance C corresponds to the pressure [dyn / cm ² ] at the radial artery. In addition, the diode D is equivalent to an aortic valve, and is turned on (in a state where the valve is open) during a period corresponding to the systole of the ventricle, and is turned off (when the valve is closed) during a period corresponding to diastole. State).

As described above, the arterial vasculature from the aortic root to the peripheral part can be simulated using an electric model shown in FIGS. 9A and 9B. Therefore, this time, the ejection wave, which is the first wave in the ventricular systole, will be examined based on the concept of treating the arterial vascular system as the electric model. The blood pressure waveform at the aortic root during the ventricular systole is a single gentle wave having a convex shape as shown in FIG. 6B, whereas the pulse wave waveform at the peripheral portion during the ventricular systole is As shown in FIG. 3C, there are two waves consisting of an ejection wave and a tide wave. Considering this phenomenon by replacing the above electric model with the electric model, if an electric signal corresponding to the waveform of FIG. 2B is applied as a pulse to the input terminal of the electric model, A first wave responsive to an input pulse and a transient second
It means that a wave has appeared. From this, it can be said that the load of the vascular artery has not only a simple resistance but also a characteristic of following a transient change. Further, the ejection wave corresponding to the first wave is generated when the power supply is operating, that is, when the aortic valve is open, when the power supply of the heart is connected to the load of the arterial vasculature. It can be said that it directly corresponds to an input pulse which is a blood waveform emitted from the heart. Moreover, since the input pulse here is determined by the function of the power source itself, the ejection wave is directly related to the function of the myocardium, even if the concept of treating the arterial vascular system with an electrical model is used. Can be said. Therefore,
It is considered that the cardiac function can be evaluated not only by the rise time of the ejection wave but also by time-frequency analysis of the components and the like.

An embodiment of the present invention will be described with reference to the drawings based on such a theoretical premise.

<2: First Embodiment> First, a cardiac pacemaker according to a first embodiment will be described. The cardiac pacemaker according to the present embodiment is applied to a patient who does not generate a self-heartbeat or a patient whose heart rate is extremely low (20 to 40 beats / minute) even if there is a self-heartbeat, to secure the minimum heart rate. While pacing is performed, the pacing is described in detail based on the above-described theoretical grounds. First, a pulse wave waveform is detected from a patient, and second, a ventricular systole is detected from the pulse wave waveform. Thirdly, among the pulse wave waveforms of the ventricular systole, the waveform of the ejection wave corresponding to the pulsation is analyzed to calculate an index that defines the ejection wave. Pacing is performed. Here, in the present embodiment, among the above-mentioned ones, the rising normalization time of the ejection wave is used as an index for defining the ejection wave.

<2-1: Functional Configuration of Embodiment> FIG.
(A) is a block diagram showing a functional configuration of a cardiac pacemaker 1a according to the present embodiment. In this figure, a pulse wave detector 10 detects a pulse wave waveform in a peripheral portion of a patient (for example, a radial artery or a fingertip), and outputs a detection signal as MH. Next, the systolic period specifying / waveform analyzing unit 20 analyzes the signal MH detected by the pulse wave detecting unit 10 to specify a ventricular systolic period, and obtains a rising time and an ejecting time of the ejection wave,
The former is gradually reduced by the latter, and the rise normalized time of the ejection wave is calculated.

The signal generator 30a generates a pulse signal having a frequency corresponding to the normalized rise time of the ejection wave as a pacing pulse in principle. However,
The lower limit of the frequency of the pacing pulse is set to about 0.67 Hz (corresponding to 40 beats / minute) so as not to fall below this lower limit frequency. Similarly, the upper limit of the frequency of the pulse is set to 2.5 Hz (corresponding to 150 beats / minute) so as not to exceed the upper limit. It is desirable that the configuration can be set individually.
For this purpose, an element for setting the lower limit and the upper limit frequency may be added to the signal generator 30a, or the calculated normalized time may be set so that the lower limit (upper limit) frequency falls below (exceeds) the lower limit (upper limit) frequency. If so, it is conceivable to add an element for correcting the normalized time to be output to the systolic period specifying / waveform analysis unit 20. Further, a pulse signal is generated at a frequency corresponding to the rising normalized time of the ejection wave. For example, first, the systolic phase specifying / waveform analyzing unit 2
Second, a voltage signal corresponding to the normalized time is output for 0, and second, the signal generator 30a is configured as a VCO (voltage controlled oscillator) that controls the pulse generation frequency according to the voltage signal. It is possible.

The pacing pulse generated by the signal generator 30a is guided to the electrode 31 fixed to the heart via the conducting wire 32 to generate a heartbeat of the patient.

<2-1-1: Configuration of Pulse Wave Detector> Here, an example of the configuration of the pulse wave detector 10 will be described with reference to FIG. As shown in FIG.
It comprises an ED 12, a phototransistor 13, and the like. Among them, the LED 12 is arranged at a position for irradiating the peripheral part of the patient, for example, the vascular tissue of the radial artery, and the phototransistor 13 receives the reflected light by the vascular tissue among the irradiation light from the LED 12. Placed in Therefore, when the switch SW is turned on and the power supply voltage is applied, the light is emitted from the LED 12 to the vascular tissue, and the reflected light is received by the phototransistor 13. On this occasion,
It is desirable that the phototransistor 13 does not directly receive the irradiation light from the LED 12. The voltage obtained by converting the photocurrent of the phototransistor 12 into a voltage is output as the signal MH of the pulse wave detector 10.

Here, the emission wavelength of the LED 12 is selected near the absorption wavelength peak of hemoglobin in blood. Therefore, the light receiving level changes according to the blood flow. Accordingly, the pulse wave waveform is detected by detecting the light receiving level. In addition, as the LED 12, In
GaN-based (indium-gallium-nitrogen-based) blue LE
D is preferred. The emission spectrum of the blue LED has an emission peak at, for example, 450 nm, and its emission wavelength range is from 350 nm to 600 nm. In this case, a GaAsP-based (gallium-
Arsenic-phosphorus) may be used. The light-receiving wavelength region of the phototransistor 13 has, for example, a main sensitivity region of 3
300 nm in the range from 00 nm to 600 nm
There is also a sensitivity region below m. When such a blue LED and a phototransistor are combined, a pulse wave is detected in a wavelength region from 300 nm to 600 nm, which is an overlapping region thereof, resulting in the following advantages.

First, of the light included in the external light, light having a wavelength region of 700 nm or less tends to hardly penetrate the finger tissue. Therefore, the external light is not covered with the sensor fixing band. , Does not reach the phototransistor 33 via the finger tissue, and only light in a wavelength region that does not affect detection reaches the phototransistor 33. On the other hand, since light in a wavelength region lower than 300 nm is almost absorbed by the skin surface, even if the light receiving wavelength region is set to 700 nm or less, the substantial light receiving wavelength region is 300 nm to 700 nm.
nm. Therefore, the influence of external light can be suppressed without covering the finger in a large scale. In addition, hemoglobin in blood has a large absorption coefficient for light having a wavelength of 300 nm to 700 nm, and is several times to about 100 times or more larger than the absorption coefficient for light having a wavelength of 880 nm. Therefore, as in this example, in accordance with the absorption characteristics of hemoglobin, the wavelength region where the absorption characteristics are large (300 n
When the light of (m to 700 nm) is used as the detection light, the detection value changes with high sensitivity according to the change in blood volume, so that the S / N ratio of the pulse wave waveform MH based on the change in blood volume can be increased.

<2-1-2: Configuration of Systolic Period Identifying / Waveform Analysis Unit> Next, the details of the systolic period identifying / waveform analyzing unit 20 will be described. First, the systolic period specifying / waveform analyzing unit 20 extracts a waveform parameter for specifying the shape of the pulse wave waveform. Here, the waveform parameters are determined as shown in FIG. That is, the waveform parameter is a time t ₆ from a rising peak point P0 of one beat (hereinafter, this rising time is referred to as a pulse wave start time) to a rising peak point P6 of the next beat, and peak points sequentially appearing in the pulse wave waveform. (maximum point and minimum point) P1 to P5 of the blood pressure value (difference) y ₁
~y _5, and, from the peak point of the pulse wave start point P0 (the minimum minimal point) is defined as the elapsed time t ₁ ~t ₅ to each peak point P1~P5 appears. In this case, the rising time of the ejection wave is equivalent to t ₁ in terms of waveform parameters, and the ejection time which can be considered as the time corresponding to ventricular systole corresponds to t ₄ in terms of waveform parameters. . Further, y _{1 to} y ₅ each indicate a relative blood pressure value based on the blood pressure value at the peak point P0.

Here, the systolic period specifying / waveform analyzing unit 20
In specifying the waveform parameters, the peak points P0 and P0
4, which necessarily means identifying ventricular systole and ventricular diastole. That is, since the peak point P0 corresponds to the start point of the rising of the ejection wave, obtaining this means specifying the start point of the ventricular systole (end point of the ventricular diastole).
4 corresponds to a notch associated with aortic valve closure, which means that the end point of ventricular systole (start point of ventricular diastole) is specified. Therefore, the systolic period specifying / waveform analyzing unit 20 necessarily has a function of specifying the ventricular systolic period and the ventricular diastolic period.

Next, details of the systolic period specifying / waveform analyzing section 20 will be described. FIG. 3 is a block diagram showing the detailed configuration. In the figure, a microcomputer 201
Controls each component, and has a register (not shown) inside. The waveform memory 202 is constituted by a RAM or the like, and sequentially stores the value of the signal MH supplied via the A / D converter 203 and the low-pass filter 204, that is, the waveform value W of the signal indicating the pulse wave component. The waveform value address counter 205 counts the sampling clock φ while the microcomputer 201 outputs the waveform sampling instruction START, and outputs the count result as the waveform value address ADR1 (write address) of the waveform value W. Things. This waveform value address ADR1 is monitored by the microcomputer 201. The selector 206 selects an address to the waveform memory 202. When the microcomputer 201 does not output the select signal S1, the selector 206 selects the waveform value address ADR1 output from the waveform value address counter 205. , When the select signal S1 is output, the microcomputer 2
01 selects the read address ADR4 output.

On the other hand, the differentiating circuit 211 time-differentiates the waveform value W sequentially output from the low-pass filter 204 and outputs the result. The zero cross detection circuit 212 outputs a zero cross detection pulse Z when the time derivative of the waveform value W becomes zero due to the waveform value W becoming a local maximum value or a local minimum value. More specifically, the zero cross detection circuit 21
2 are the peak points P0 to P of the waveform parameters shown in FIG.
6 is a circuit provided for detecting the signal No. 6 and outputs a zero cross detection pulse Z when a waveform value W corresponding to these peak points is input.

Next, the peak address counter 213
Waveform sampling instruction ST by microcomputer 201
While the ART is being output, the zero-cross detection pulse Z is counted, and the count result is used as the peak address ADR.
2 is output. Moving average calculation circuit 214
Accumulates the time derivative of the waveform value W output by the differentiating circuit 211 up to the present time for a predetermined number in the past, calculates the average value thereof, and expresses the result as the slope of the pulse wave up to the present time. It is output as inclination information SLP.

The peak information memory 215 is provided for storing the peak information shown in FIG. 4, and details of the contents are as follows. The waveform value address ADR1 is the waveform value address output from the waveform value address counter 205 when the waveform value W output from the low-pass filter 204 has reached a maximum value or a minimum value. In other words, this is the address where the waveform value W corresponding to the local maximum value or the local minimum value is written in the waveform memory 202. Peak type B / T This is information indicating whether the waveform value W written to the waveform value address ADR1 is a local maximum value T (Top) or a local minimum value B (Bottom). Waveform value W is a waveform value corresponding to the maximum value or the minimum value. Stroke information STRK is a change in waveform value from the immediately preceding peak value to the peak value. Slope information SLP This is the average value of the time derivative of a predetermined number of waveform values in the past up to the peak value.

The systolic phase specifying / waveform analyzing section 20 configured as described above analyzes the signal MH, specifies waveform parameters, obtains the rising time and the running time of the ejection wave by the operation described later, and furthermore, , And the normalization time t ₁ / t ₄ of the ejection wave is calculated.

<2-2: Operation of First Embodiment> Next, the operation of the cardiac pacemaker according to the embodiment shown in FIG. 1 will be described.

First, in the pulse wave detecting section 10 (see FIG. 2), when the switch SW is turned on and light is emitted from the LED 12, the irradiated light is reflected in accordance with the blood flow in the blood vessel. The light is received by the phototransistor 13. Therefore, the result of converting the photocurrent of the phototransistor 12 into a voltage indicates a change in blood flow in a blood vessel, that is, a pulse wave waveform, which is output as a signal MH, and the systolic phase identification / waveform analysis unit 20 Will be supplied.

<2-2-1: Operation of systolic period specifying / waveform analyzing unit> Here, the systolic period specifying / waveform analyzing unit 2 shown in FIG.
The operation of 0 will be described. Systolic identification and waveform analysis unit 2
0 has to get a pulse waveform to identify waveform parameters, further determines the time t ₁ and time t _4, until calculates the normalized time t ₁ / t _4, carried out in a plurality of stages. Thus, the operation of the systolic period specifying / waveform analyzing unit 20 will be described in each stage.

<2-2-1-1: Accumulation of Pulse Waveform and Collection of Peak Information> First, in the systolic period specifying / waveform analyzing section 20, the signal MH is stored in the waveform memory 2 in FIG.
02, and the peak information of the pulse waveform indicated by the signal MH is collected. This operation is executed in the following manner. First, when the microcomputer 201 outputs a signal START instructing the start of pulse waveform acquisition, the reset of the waveform value address counter 205 and the peak address counter 213 is released. As a result, the counting of the sampling clock φ is started by the waveform value address counter 205, and the waveform value address ADR1, which is the count value, is
The data is supplied to the waveform memory 202 via the selector 206 as a write address. Then, a signal M indicating the pulse wave component
H is input to the A / D converter 203, and is sequentially converted into a digital signal according to the sampling clock φ, and is sequentially output as a waveform value W via the low-pass filter 204. The waveform values W output in this manner are sequentially supplied to the waveform memory 202, and are written into the storage area specified by the waveform value address ADR1 at that time. By the above operation, for example, a series of waveform values W in the pulse waveform illustrated in FIG.

On the other hand, in parallel with the accumulation operation, the collection of the peak information and the writing to the peak information memory 205 are executed as follows. First, the pulse wave detector 1
The waveform value W of the signal MH due to 0 is time-differentiated by the differentiating circuit 211, and the result is supplied to the zero-cross detecting circuit 212 and the moving average calculating circuit 214, respectively. Each time the time differential value of the waveform value W is supplied in this way, the moving average calculation circuit 214 calculates the average value (ie, moving average value) of a predetermined number of time differential values in the past, and slopes the calculation result. Output as information SLP. Here, a positive value is output as the slope information SLP when the waveform value W is rising or has finished rising and has reached the maximum state, and when the waveform value W has fallen or has finished falling and has reached the minimum state, the slope information SLP has been displayed. S
A negative value is output as LP.

For example, when the pulse wave waveform shown in FIG. 5 is output from the low-pass filter 204, the peak point P'1 is the maximum point, and therefore, zero is obtained as the time differentiation by the differentiation circuit 211.
Output from Therefore, the zero cross detection pulse Z is
It is output by the zero cross detection circuit 212. As a result, by the microcomputer 201, the waveform value address ADR1, the waveform value W, which is the count value of the waveform value address counter 205 at that time, the peak address ADR2 (in this case, ADR2 = 0) which is the count value of the peak address counter, and the slope The information SLP is captured. Further, the peak address ADR2, which is the count value of the peak address counter 203, becomes "1" by outputting the zero cross detection pulse Z.

On the other hand, the microcomputer 201 determines the peak type B based on the sign of the acquired inclination information SLP.
/ T is created. Thus, the waveform value W of the peak point P'1
Is output, the inclination information SL at that time is output.
Since P has a positive value, the microcomputer 201
Is the value of the peak information B / T as "T" corresponding to the maximum point. Then, the microcomputer 201 designates the peak address ADR2 (ADR2 = 0 in this case) fetched from the peak address counter 213 as the write address ADR3 as it is, and obtains the waveform value W and the waveform value W.
Value address ADR1, peak type B /
T, the slope information SLP is written to the peak information memory 215 as the first peak information. When the peak information is written for the first time, the stroke information STRK is not created or written because there is no previous peak information.

Thereafter, in the pulse waveform shown in FIG. 5, the waveform value W corresponding to the peak point P'2 is
04, the zero-cross detection pulse Z is output in the same manner as described above, and the waveform value address ADR1, the waveform value W,
Peak address ADR2 (= 1), slope information SLP (<
0) is taken in by the microcomputer 201. Then, similarly to the above, the microcomputer 201
Thus, the peak type B / T is determined based on the inclination information SLP. Here, since the peak point P'2 is a minimum point, the slope information SLP at that time becomes a negative value,
The value of the peak information B / T is “B” corresponding to the minimum point. Further, the microcomputer 201 supplies an address smaller by “1” than the peak address ADR2 to the peak information memory 215 as the read address ADR3. As a result, the first written waveform value W is read. And the microcomputer 2
01, the difference between the waveform value W fetched this time from the low-pass filter 204 and the first waveform value W read from the peak information memory 215 is calculated, and stroke information STRK is obtained. The peak type B / T and stroke information STRK obtained in this manner are used together with the waveform value address ADR1, the waveform value W, and the inclination information SLP as the peak information memory 21 as the second peak information.
5 is written to the storage area corresponding to the peak address ADR3 = 1. Thereafter, the same operation is performed when the peak points P′3, P′4,... Are detected. Then, at a predetermined timing, the microcomputer 201 stops outputting the waveform collection instruction START, and the collection of the waveform value W and the peak information ends.

<2-2-1-2: Specifying the Pulse Waveform for One Beat> Even if the peak information of the peak points P'1 to P'1 of the pulse wave waveform illustrated in FIG. This does not mean that the waveform parameters determined in FIG. 7 have been obtained.
In other words, the waveform parameters correspond to the waveform parameters determined in FIG. 7 only after specifying one pulse waveform shown in FIG. Therefore, it is necessary to specify a pulse waveform for one beat from the collected peak information of the peak points P′1. This specific processing is executed as follows.

First, in this specification, the characteristic of the pulse wave waveform, that is, the blood pressure value of the pulse wave waveform becomes the lowest at the peak point P0 corresponding to the start point of the ventricular systole, and corresponds to the ejection wave immediately thereafter. The characteristic that the peak value is highest at the peak point P1 is used. Therefore, the microcomputer 201 sequentially reads the inclination information SLP and the stroke information STRK corresponding to each peak point P′1, P′2,... From the peak information memory 215. Next, the microcomputer 201 sets each stroke information STR
The stroke information corresponding to the positive slope is selected from K (that is, the corresponding slope information SLP has a positive value). Just extract. That is,
First, the microcomputer 201 first selects a peak point, which is a local maximum point, and secondly, extracts a peak point having a large change from the immediately preceding peak point from the peak point. Here, a predetermined number of peak points is extracted, which is intended to examine a plurality of periods.

Next, the microcomputer 201 specifies the information corresponding to the median from the stroke information STRK corresponding to the extracted peak point. This gives 1
Stroke information corresponding to the rising part of the pulse waveform of the beat (for example, the part indicated by reference numeral STRKM in FIG. 5) is specified. Note that this specification is based on the premise that peak information has been collected for pulse wave waveforms for a plurality of cycles, and is intended to exclude those considered to be measurement abnormalities. And the microcomputer 201
Is "1" from the peak address of the stroke information.
The peak point corresponding to the immediately preceding peak address is defined as the peak point P0 of the waveform parameter, and the peak points corresponding to the following peak addresses are sequentially identified as P1 to P1 of the waveform parameter.
Identify as 6. For example, referring to FIG.
The peak point P'6 located immediately before the RKM is specified as a peak point P0 serving as a waveform parameter calculation reference, and the following peak points P'7 to P'12 are sequentially specified as waveform parameters P1 to P6. You.

The peak point P4 corresponding to the ventricular diastole
In specifying from to P6 (P0), the following characteristics of the pulse waveform may be used. That is, the blood pressure value of the pulse wave waveform is the peak point P4 corresponding to the start point of the ventricular diastole.
In the above, the second minimum value from the bottom of the detected peak points may be specified as the peak point P4 by using the feature having the second smallest minimum value. Due to individual differences and physical condition, there is a case where the retreat wave does not clearly appear in the pulse wave waveform. In this case, the peak points P2 and P3 due to the tidal wave cannot be specified, but the peak point P4 can be specified by determining the magnitude of the value to be the second minimum value from the bottom.

<2-2-1-3: Calculation of Waveform Parameters> The microcomputer 201 calculates each waveform parameter by referring to each peak information corresponding to the pulse waveform for one beat. For example, the peak points P'6 to P'12
When the peak points P0 to P6 serving as the reference of the waveform parameters are specified, they are obtained as follows. Waveform value W of the peak point P'6~P'11 of blood pressure values y ₁ ~y ₅ Peak Information
It is multiplied by coefficients, respectively, and y ₁ ~y _5. This coefficient is determined by the sensitivity of the pulse wave detector 10, the characteristics of the A / D converter 203, the circuit configuration of the low-pass filter 204, and the like. Subtracting the waveform address corresponding to peak point P'6 from the waveform address corresponding to the time t ₁ peak point P'7, it calculates the t ₁ multiplied by the cycle of the sampling clock φ with respect to the results. Similar to the time t ₂ ~t ₆ above t _1, respectively calculated on the basis of the waveform address difference between each corresponding peak point. The microcomputer 201 stores each waveform parameter obtained as described above in an internal register.

[0050] <2-2-1-4: calculation of the normalized time t ₁ / t _4> microcomputer 201, the first, read from the internal register, the t ₁ and t ₄ of each waveform parameters respectively, Second, dividing the read t ₁ by t ₄ ,
And outputs as the rising normalized time ejection wave t ₁ / t _4.

As described above, when the normalized time t ₁ / t ₄ is calculated by the systolic phase specifying / waveform analyzing section 20, the signal generating section 30a sets the calculated normalized time t ₁ / t ₄ to The frequency of the pacing pulse is determined accordingly. For example, the calculated normalized time t ₁ / t ₄ is equal 34.8 [%]
A pulse signal as a pacing pulse is generated at a rate of 87 times per minute (see FIG. 8). After the pulse signal is amplified by an amplifier (not shown),
2 to an electrode 31 attached to the heart.

As described above, according to the cardiac pacemaker according to the present embodiment, the cardiac pacing is performed by analyzing the pulse wave waveform to obtain an index indicating the cardiac function status, and generating a pulse signal having a frequency corresponding to the index. Is performed, it is possible to appropriately control the heart rate according to the load required for the heart function.

In the first embodiment, the rise normalized time t ₁ / t ₄ of the ejection wave in the pulse waveform is used as an index for evaluating the cardiac function status. If you don't want to evaluate it,
The rising time t ₁ of the ejection wave may be used. Also, the rising time t ₁ of the ejection wave and its normalized time t ₁ / t
_In addition to ₄ , as described above, the analysis result obtained by performing time-frequency analysis of the component of the ejection wave and the like also serves as an index indicating the cardiac function state, so that cardiac pacing is performed according to the analysis result A configuration may be used.

<3: Second Embodiment> Next, a second embodiment of the present invention will be described.
A cardiac pacemaker according to the embodiment will be described. In the first embodiment described above, the signal MH detected by the pulse wave detector 10 has been described as indicating a pulse waveform. However, if the patient lives daily, regardless of the absolute rest, a component (body motion component) associated with the activity is superimposed on the signal detected by the pulse wave detection unit 10, and the waveform parameter specific, thus, it is envisioned that adversely affect the calculation of the normalized time t ₁ / t _4. Further, as the index for cardiac functional status, in addition to the normalized time as an indicator for defining the ejection wave t ₁ / t _4, respiratory rate and body acceleration is also important. Therefore, in the cardiac pacemaker according to the second embodiment, the first, by removing the components due to the daily activity from the signal MH by pulse wave detector 10, an accurate calculation of the normalized time t ₁ / t ₄ Plan, second
In addition to the normalized time t ₁ / t _4, taking into account also the respiratory rate and body acceleration, is performed cardiac pacing.

FIG. 10 is a block diagram showing a functional configuration of the cardiac pacemaker 1b according to the present embodiment. In this figure, the same components as those of the cardiac pacemaker 1a according to the first embodiment shown in FIG. 1A are denoted by the same reference numerals, and description thereof will be omitted.

<3-1: Removal of Body Motion Component> First, a configuration for removing a body motion component of a patient will be described. The body motion detection unit 40 is configured by, for example, an acceleration sensor and the like, detects the movement of the patient's body, and outputs a detection signal TH thereof. The waveform processing unit 41 is configured by a low-pass filter or the like, and performs a waveform shaping process on the signal TH to obtain a signal MHt indicating a body motion component. The body motion component removing unit 42 subtracts the signal MHt indicating the body motion component from the signal MH ′ on which the body motion component is superimposed, and outputs a signal M indicating the pulse wave component.
H is output.

The cardiac pacemaker 1b according to the present embodiment
Processes the pulse waveform detected from the patient, but when the patient is not in a resting state, the signal detected by the pulse wave detector 10 includes a signal MH indicating a pulse wave component,
The signal MHt indicating the body motion component of the patient is also superimposed. That is, in this case, the signal output from the pulse wave detection unit 10 does not accurately indicate the pulse wave waveform of the patient.

On the other hand, since the blood flow is affected by blood vessels and tissues, the body movement component MHt included in the signal MH ′ on which the body movement component is superimposed is not the signal TH indicating the body movement of the patient, but the signal TH. Is thought to be a dull one. For this reason, the signal TH directly indicating the patient's body motion is waveform-shaped by the waveform processing unit 41 to obtain a signal MHt indicating the body motion component, and this is subtracted from the signal MH 'by the pulse wave detection unit 10. Thus, the signal MH indicating only the pulse wave component is obtained by removing the body motion component. Then, the systole specifying / waveform analyzing unit 20 in the present embodiment specifies the waveform parameter from the signal MH indicating only the pulse wave component, and obtains the rising time t ₁ and the ejection time t ₄ of the ejection wave,
Since calculating the normalized time t ₁ / t _4, so that the influence of the body movement is eliminated. Note that the format of the low-pass filter, the number of stages, the constant, and the like in the waveform processing unit 41 are determined from actually measured data.

<3-2: Calculation of Respiratory Rate> Next, a configuration for calculating the respiratory rate will be described. Respiratory rate detector 5
0 is for obtaining the respiration rate from the signal MH indicating the pulse wave component. First, the premise for that will be described. FIG.
FIG. 1 is a diagram showing the relationship between the electrocardiogram and the blood pressure in the peripheral part, and the fluctuation of the blood pressure. In general, a blood pressure change appearing in a peripheral portion such as a radial artery is defined as a change for each beat in a ventricular systole and a ventricular diastole, and corresponds to a change in an RR interval in an electrocardiogram. Here, the RR interval is a time interval between the R point of the electrocardiogram and the R point of the next heartbeat.

Here, when a spectrum analysis of blood pressure fluctuation is executed, it is known that this fluctuation is composed of waves of a plurality of frequencies. These waves are classified into the following three types of fluctuation components. -HF (High Frequency) component, which is a fluctuation that matches respiration-LF (Low Frequency), which fluctuates in a cycle of about 10 seconds
Component ・ Trend that fluctuates at a frequency lower than the measurement limit (Tren
d)

FIG. 12A shows the RR of the measured pulse waveform.
The waveform of the variation of the interval and the waveform of each variation component when this variation waveform is decomposed into the three frequency components are shown. FIG. 2B shows the result of performing a spectrum analysis on the fluctuation waveform of the RR interval shown in FIG. As can be seen from FIG.
Peaks are seen at two frequencies around 25 Hz. Here, the former is the LF component, and the latter is the HF component. Note that the trend component is below the measurement limit and cannot be read from the figure.

The respiratory rate detecting section 50 specifies the HF component among the components constituting the blood pressure fluctuation, and detects the respiratory rate per unit time from the frequency thereof. To determine the respiratory rate. Specifically, the respiratory rate detecting unit 50 first obtains the RR interval between adjacent pulse waves from the signal MH indicating the pulse wave waveform, and secondly,
Interpolating the obtained discrete values of the RR interval by an appropriate method,
Third, an FFT (Fast Fourier Transform) process is performed on the interpolated curve to obtain a spectral component. Fourth, among the obtained spectral components, a large frequency component is specified as an HF component. The reciprocal of the peak frequency of the HF component is obtained, and this is appropriately converted to obtain the respiratory rate. For example, as shown in FIG.
When the peak frequency of the HF component is specified as 0.25 Hz, the cycle is 4 seconds, and the respiration rate per minute is detected as 15 times. The respiratory rate thus obtained is
Since the cardiac pacing of decisions, along with the normalized time as an indicator for defining the ejection wave t ₁ / t _4, is supplied to the signal generating unit 30b.

<3-3: Detection of Body Acceleration> Next, a configuration for detecting body acceleration will be described. As described above, the signal TH from the body motion detection unit 40 is the body acceleration itself directly indicating the body motion of the patient. Since this body acceleration is a powerful judgment material for cardiac pacing, the signal generation unit 30 b
Supplied to

[0064] <3-4: In addition to the index, cardiac pacing considering respiration rate and body accelerations> Next, the signal generating unit 30b in this embodiment, normalized time t ₁ / t _4, respiratory rate and body acceleration Are appropriately weighted, and a pulse signal having a frequency corresponding to the result is generated as a pacing pulse. Note that the weighting may be configured to be appropriately changeable by providing a switch or the like. Also,
The signal generator 30b is also the signal generator 30a of the first embodiment.
Similarly to the above, it is preferable to add a configuration for setting the lower limit and the lower limit frequency of the pulse signal.

As described above, according to the cardiac pacemaker according to the present embodiment, the ventricular systole and the waveform parameters are specified from the signal from which the components associated with the living activity have been removed, so that the normalized time t ₁ / t _4. Is more accurately determined, and
Also in consideration of other respiratory rate and body accelerations of the normalized time t ₁ / t _4, since determining the frequency of the pulse signal, it is possible to perform cardiac pacing better.

<4: Third Embodiment> Next, a third embodiment of the present invention will be described.
A cardiac pacemaker according to the embodiment will be described. In the above-described first and second embodiments, a case has been described in which the present invention is applied to a patient who does not generate a self-heartbeat, or a patient whose heart rate is extremely low even if there is a self-heartbeat. Here, in a patient who does not generate a self-heartbeat, naturally, competition between the self-heartbeat and a cardiac pacemaker does not occur. If the self-heart rate is extremely low, a heartbeat is generated by the cardiac pacemaker before the self-heart rate, so that no competition occurs. However, in the sinus dysfunction syndrome, a spontaneous heartbeat occurs unless the heartbeat is lost, and it is necessary to supply a pacing pulse to such a patient regardless of the spontaneous heartbeat. It will trigger arrhythmias such as heart beats and ventricular fibrillation. Therefore, in the cardiac pacemaker according to the third embodiment, a pacing pulse is generated while taking into consideration the occurrence of a self-heartbeat, thereby preventing occurrence of arrhythmia.

<4-1: Configuration of Third Embodiment> FIG.
FIG. 2 is a block diagram showing a functional configuration of the cardiac pacemaker 1c according to the present embodiment. In this figure, FIG.
The same components as those of the cardiac pacemaker 1a shown in FIG. In the figure, the target heart rate interval calculation unit 60c is for calculating heart beat interval corresponding to the normalized time t ₁ / t ₄ (the period) as a target value. For this calculation, for example, the relationship in FIG. 8 is obtained in advance as a function, and the heartbeat interval is calculated using the normalized time t ₁ / t ₄ as an argument, or the relationship in FIG. A method of converting the time t ₁ / t ₄ to obtain the heartbeat interval or the like can be considered. On the other hand, the heartbeat time measurement unit 70 detects the patient's heartbeat via the conductor 32 and measures the elapsed time from the immediately preceding heartbeat. Also, the signal generator 30c
Is different from the signal generators 30a and 30b that generate pacing pulses at a predetermined frequency, and generates one pacing pulse when the elapsed time from the previous heartbeat matches the cycle of the target value.

<4-3: Operation of Third Embodiment> Next, the operation of the cardiac pacemaker 1c will be described with reference to FIG. In the figure, a point a indicates a point in time when the pacing pulse PP is supplied by the signal generator 30c. Therefore, immediately after that, a heartbeat by the cardiac pacemaker appears. The elapsed time from the point a is calculated by the heartbeat time measurement unit 7
On the other hand, when the elapsed time reaches the target value, the pacing pulse is supplied again by the signal generating unit 30c for one shot. Accordingly, the distance from points a and b, i.e., the interval of the heartbeat by the heart pacemaker would then be determined in accordance with the normalized time t ₁ / t _4.

Now, in terms of the interval from point a to point b,
Next, it is supposed that pacing should be performed at the point c, but the self-beating QRS has occurred at the point c ′ before that. For this reason,
In the heartbeat time measurement unit 70, the measurement from the point b up to now is reset, and the measurement is newly started based on the point c '. Therefore, the elapsed time does not reach the target value in the signal generator 30c, and as a result, no pacing pulse is supplied at the point c '. Then, at the point d where the elapsed time from the point c ′ reaches the target value, one pacing pulse is supplied. The same applies to point e where the elapsed time from point d has reached the target value. Next, pacing should be performed at the point f, but if the self-heart rate QRS occurs again at the point f ′ before that, the measurement from the point e is reset and a new f No pacing pulse is supplied at point f 'because the measurement is started with reference to point'.

As described above, according to the cardiac pacemaker according to the present embodiment, if the heart rate is controlled in accordance with the normalized rise time of the ejection wave, which is an index indicating the cardiac function state, and the self-heart rate is generated, Since the heartbeat is generated based on the time of occurrence, the conflict between the self-heartbeat and the cardiac pacemaker is avoided, and the occurrence of arrhythmia in the patient can be prevented.

In the signal generator 30c, the first
As in the signal generating section 30a of the embodiment, a pacing pulse is generated while securing at least 40 minutes / beat. As such a configuration, an element for setting the upper limit interval may be added to the signal generator 30c, or if the interval serving as the target value exceeds the upper limit interval, an element for correcting this and outputting It may be added to the target heartbeat interval calculation unit 60c.

<5: Fourth Embodiment> Next, a fourth embodiment of the present invention will be described.
A cardiac pacemaker according to the embodiment will be described. This embodiment is an improvement of the third embodiment, and the relationship is the first.
This is the same as the relationship with the second embodiment.

FIG. 15 is a block diagram showing a functional configuration of the cardiac pacemaker 1d according to the present embodiment. In this figure, the same components as those in FIGS. 10 and 13 are denoted by the same reference numerals, and description thereof will be omitted. In the figure, the target heartbeat interval calculation unit 60d calculates a normalized time t
₁ / t ₄ , the respiration rate and the body acceleration are appropriately weighted, and the heartbeat interval corresponding to the result is calculated as a target value. Therefore, according to the cardiac pacemaker according to the present embodiment, since the signal components have been removed due to daily activity, so identifying the ventricular systolic and waveform parameters, normalized time t ₁ / t ₄ is determined more accurately , in addition, the cardiac pacing that takes into account also the other respiratory rate and body acceleration of the normalized time t ₁ / t _4, it becomes possible to perform to avoid a conflict with the self-heart rate.

<6: External Configuration of Embodiment> Next, some examples of the configuration of the cardiac pacemaker according to the above-described first to fourth embodiments will be described. Since the cardiac pacemaker continuously performs the cardiac pacing of the wearer, it is desirable that the cardiac pacemaker be configured to be worn daily without any trouble. Such a configuration may be one that imitates a form such as a wristwatch type or an accessory, or one that is incorporated as a part of its function, as described below.

<6-1: Wristwatch Type A> First, an example of a configuration in which the heart pacemaker according to the embodiment is a wristwatch type will be described with reference to FIG. As shown in FIGS. 1A and 1B, a cardiac pacemaker is mainly composed of a device main body 100 having a wristwatch structure.
0 is connected to a pulse wave detecting unit 10 (see FIG. 2) via a cable 101, and to a conducting wire 32 for guiding a pacing pulse. Of these, the device body 1
At 00, a wristband 102 is attached.
More specifically, the wristband 102 is wrapped around the patient's left arm from 12 o'clock, and the other end is fixed at 6 o'clock on the main body 100. In the 6 o'clock direction of the device main body 100,
Further, a connector section 103 is provided. A connector piece 104 serving as an end of the cable 101 is detachably attached to the connector section 103.

On the other hand, the pulse wave detector 10 is attached to the base of the patient's index finger while being shielded from light by the sensor fixing band 11, as shown in FIG. As described above, when the pulse wave detector 10 is attached to the base of the finger, the length of the cable 101 can be shortened.
Also, when the distribution of body temperature from the palm to the fingertip is measured, when the temperature is cold, the temperature at the fingertip drops significantly, whereas the temperature at the root of the finger does not drop relatively. Therefore, if the pulse wave detector 10 is attached to the base of the finger, even when going out on a cold day,
A pulse wave waveform can be accurately detected. In addition, a display unit 110 composed of a liquid crystal panel is provided on the front side of the apparatus main body 100, and displays a setting state, a current time, a heart rate, and the like.

On the other hand, an acceleration sensor is incorporated inside the apparatus main body 100, and detects a body movement caused by a swing of the patient's arm or a vertical movement of the body. That is, this acceleration sensor corresponds to the body motion detection unit 40 in the second and fourth embodiments. A CPU for controlling various calculations and conversions is provided inside the apparatus main body 100 (not shown), and also serves as the microcomputer 201 in FIG. Further, button switches SW1 and SW for performing various operations and setting the upper and lower limits of the pacing pulse are provided on the outer peripheral portion of the apparatus main body 100.
2 are provided.

<6-2: Wristwatch Type B> Next, another example of the configuration when the heart pacemaker is a wristwatch type will be described with reference to FIG. In this configuration, the pulse waveform of the patient is detected by using a pressure sensor, instead of being photoelectrically detected by an LED or a phototransistor as shown in FIG. As shown in FIG. 1A, a pair of bands 102,
The elastic rubber 131 of the pressure sensor 130 is provided to protrude from the tightening side of one of the fasteners 120. Band 1 provided with fastener 120
02 has a structure in which an FPC (Flexible Printed Circuit) substrate is covered with a soft plastic in order to supply a detection signal from the pressure sensor 130 (details are not shown).

In use, as shown in FIG. 9B, the device main body 100 having a wristwatch structure is moved to the patient so that the elastic rubber 131 provided on the fastener 120 is located near the radial artery 140. Is wound around the left arm 150. For this reason, a pulse wave can be constantly detected. In addition,
This winding does not differ from the usual use state of the wristwatch. When the elastic rubber 131 is pressed in the vicinity of the radial artery 140 of the patient in this manner, the blood flow fluctuation (that is, pulse wave) of the artery is detected via the elastic rubber 131 by the pressure sensor 13.
0, and the pressure sensor 130 detects this as blood pressure.

<6-3: Necklace Type> The cardiac pacemaker according to the embodiment may be a necklace type as shown in FIG. In this figure, the pressure sensor 130 is provided at the tip of the cable 101. For example, as shown in FIG.
It is attached to the carotid artery of the patient using, for example. In FIG. 18, a main part of the device is incorporated in a device main body 100 shaped like a broach having a hollow portion, and a switch SW is provided on the front surface thereof.
1, SW2 is provided, and a lower part thereof is connected to a conductor 32 for guiding a pacing pulse. A part of the cable 101 is embedded in the chain 160, and a signal MH output from the pressure sensor 130 is output.
Is supplied to the apparatus main body 100.

<6-4: Eyeglass Type> As an example of the form of the cardiac pacemaker according to the embodiment, an eyeglass type shown in FIG. 20 can be considered. As shown in this figure, the apparatus main body 100 is attached to a vine 181 of glasses, the switches SW1 and SW2 described above are provided on the upper surface thereof, and a conducting wire 32 for guiding a pacing pulse is provided on the lower surface thereof. It is connected. On the other hand, the pressure sensor 130 is electrically connected to the apparatus main body 100 via the cable 101, and is attached to the carotid artery like a necklace.

<6-5: Card Type> As another embodiment, a card type as shown in FIG. 21 can be considered. The card-type apparatus main body 100 is, for example, housed in a left breast pocket of a patient. The pressure sensor 130 is electrically connected to the apparatus main body 100 via the cable 101, and is attached to the carotid artery of the patient as in the case of necklaces and glasses.

<6-6: Pedometer Type> Further, as another embodiment, a pedometer type as shown in FIG. The pedometer device main body 100 is attached to a patient's waist belt 191 as shown in FIG. The pressure sensor 130 is connected via the cable 101 to
It is electrically connected to the apparatus main body 100, is fixed to the femoral artery at the hip joint of the patient by an adhesive tape, and is further protected by the supporter 192.

[0084]

As described above, according to the present invention, the heart rate can be appropriately controlled according to the state required for the heart function.

[Brief description of the drawings]

FIG. 1A is a block diagram illustrating a configuration of a cardiac pacemaker according to a first embodiment of the present invention, and FIG. 1B is a diagram illustrating a rising time t ₁ of an ejection wave and a time t ₄ corresponding to a systole. This is for explaining the normalized time t ₁ / t ₄ normalized by.

FIG. 2 is a diagram showing a configuration of a pulse wave detector according to the embodiment.

FIG. 3 is a block diagram showing a detailed configuration of a systolic period specifying / waveform analyzing unit in the embodiment.

FIG. 4 is a diagram for explaining storage contents of a peak information memory;

FIG. 5 is a diagram illustrating an example of a pulse waveform stored in a waveform memory.

6A is an electrocardiogram, FIG. 6B is a diagram showing an aortic blood pressure waveform, and FIG. 6C is a diagram showing a pulse wave waveform in a peripheral portion.

FIG. 7 is a diagram for explaining correspondence between a pulse waveform and a waveform parameter;

FIG. 8 is a chart for explaining usefulness of an index used in the present embodiment.

FIG. 9A is a circuit diagram showing a configuration of a four-element lumped parameter model simulating a human arterial vasculature;
(B) is a circuit diagram showing a configuration of a five-element lumped parameter model.

FIG. 10 is a block diagram illustrating a configuration of a cardiac pacemaker according to a second embodiment of the present invention.

FIG. 11 is a diagram showing a relationship between an electrocardiogram and blood pressure fluctuation.

12A is a diagram illustrating a relationship between a change in an RR interval and a frequency component constituting the change, and FIG.
It is a figure showing the result of having performed spectrum analysis about the fluctuation waveform of RR interval.

FIG. 13 is a block diagram showing a configuration of a cardiac pacemaker according to a third embodiment of the present invention.

FIG. 14 is a diagram for explaining the operation of the embodiment.

FIG. 15 is a block diagram showing a configuration of a cardiac pacemaker according to a fourth embodiment of the present invention.

FIGS. 16 (a) and (b) are views showing the external configuration when the configuration of the embodiment is a wristwatch type.

FIG. 17 (a) is a diagram showing an external configuration when the configuration of the embodiment is another wristwatch type, and FIG. 17 (b) is a diagram showing a mounted state thereof.

FIG. 18 is a diagram illustrating an external configuration when the configuration of the embodiment is a necklace type.

FIG. 19 is a diagram showing a state in which a pulse wave detection unit is attached to a carotid artery.

FIG. 20 is a diagram illustrating an external configuration when the configuration of the embodiment is a spectacle type.

FIG. 21 is a diagram illustrating an external configuration when the configuration of the embodiment is a card type.

FIG. 22A is a diagram showing an external configuration when the configuration of the embodiment is a pedometer, and FIG. 22B is a diagram showing a mounted state thereof.

[Explanation of symbols]

10 pulse wave detecting section (pulse wave detecting means), 20 systolic phase specifying / waveform analyzing section (systolic phase specifying means, analyzing means), 30a, 30b, 30c ... signal generating section (signal generating means), 40 body movement detecting section (body movement detecting means, variable detecting means), 42 body moving component removing section (body moving component removing means), 50 respiratory rate detecting section (variable detecting means), 70 ... Heart rate measuring unit (heart rate detecting means)

Claims (13)

[Claims] 1. A pulse wave detecting means for detecting a pulse wave waveform, a systole specifying means for specifying a systole of the heart from the pulse waveform, and a systolic pulse wave waveform specified by the systolic specifying means. Analyzing means for analyzing a waveform indicating a pressure characteristic of an arterial vascular system associated with blood pumped from the heart, and calculating an index defining the waveform; based on the index calculated by the analyzing means Signal generating means for generating a cardiac pacemaker signal. 2. The cardiac pacemaker according to claim 1, wherein the waveform indicating the pressure characteristic is a waveform that appears first in the systole specified by the systole specifying means. 3. The systolic phase specifying means detects a minimum point of a pulse wave waveform for at least one cycle or more, and corresponds to a valve closing from a minimum point corresponding to opening of the aortic valve of the heart in the pulse wave waveform. 2. The cardiac pacemaker according to claim 1, wherein up to the minimum point is specified as a systole of the heart. 4. The system according to claim 3, wherein the systolic phase specifying means sets the second one of the detected minimum points from the bottom to the point corresponding to the aortic valve closure of the heart. Heart pacemaker. 5. The systolic phase specifying means sets a point having a minimum value among the detected minimum points as a minimum point corresponding to aortic valve opening of the heart, and counting from the minimum minimum point. 4. The cardiac pacemaker according to claim 3, wherein the third minimum point that appears is a point corresponding to aortic valve closure of the heart. 6. The apparatus further comprises setting means for setting a lower limit frequency or an upper limit interval of the heartbeat, wherein the signal generating means does not fall below the lower limit frequency set by the setting means or does not exceed the upper limit interval. 2. The cardiac pacemaker of claim 1, further comprising: generating a cardiac pacemaker signal. 7. The apparatus further includes variable detection means for detecting a physiological variable of a living body, wherein the signal generation means is based on the physiological variable detected by the variable detection means together with the index calculated by the analysis means. 2. The cardiac pacemaker according to claim 1, wherein the cardiac pacemaker signal is generated. 8. A body movement detecting means for detecting a body movement waveform indicating a body movement, a body movement component existing in the pulse wave waveform is generated from the body movement waveform, and the body movement component is detected from the pulse wave waveform. 2. The cardiac pacemaker according to claim 1, further comprising a body movement component removing unit that removes and supplies the body motion component to the systolic period specifying unit. 9. The apparatus further comprises heart rate detecting means for detecting a heart rate, wherein the signal generating means generates a heart pacemaker signal so as not to cause a conflict with the self-heart rate detected by the heart rate detecting means. The cardiac pacemaker according to claim 1, wherein 10. The analysis unit calculates a rise time of the waveform indicating the pressure characteristic as an index that defines the waveform, and the signal generation unit calculates a rise time based on the rise time analyzed by the analysis unit. The cardiac pacemaker of claim 1, wherein the cardiac pacemaker signal is generated. 11. An index defining a waveform obtained by normalizing a rise time of a waveform representing the pressure characteristic by a time corresponding to a systole of the heart specified by the systole specifying means. 2. The cardiac pacemaker according to claim 1, wherein the signal generator generates a cardiac pacemaker signal based on the rise time normalized by the analyzer. 3. 12. The analysis means detects a minimum point of a pulse wave waveform for at least one cycle or more, and detects a minimum point in the pulse wave waveform from a minimum point corresponding to aortic valve opening of the heart in the pulse wave waveform. 11. The method according to claim 10, wherein a time to reach a maximum point at which a high blood pressure value is reached is detected as a rise time of a pulse wave waveform.
2. The cardiac pacemaker according to 1. 13. The analysis means detects a minimum point of the pulse wave waveform for at least one cycle or more, and appears immediately after the minimum point corresponding to the aortic valve opening of the heart in the pulse wave waveform. 12. The cardiac pacemaker according to claim 10, wherein a time to reach a maximum point is detected as a rise time of a pulse wave waveform.