WO2004084990A1

WO2004084990A1 - Heart treatment device and heart treating method

Info

Publication number: WO2004084990A1
Application number: PCT/JP2004/003618
Authority: WO
Inventors: Yoshihito Fukui
Original assignee: Terumo Corporation
Priority date: 2003-03-27
Filing date: 2004-03-18
Publication date: 2004-10-07
Also published as: JP4252833B2; JP2004290536A

Abstract

A heart treatment device for preventing an abrupt change of heart rate caused by stimulation of a vagus nerve by controlling heart stimulation so that the change of heart rate may be in a predetermined range after the stimulation of the vagus nerve. The heart beat interval is monitored in response to heart stimulation and detection of heart systole. The vagus nerve stimulation is controlled according to the monitored heart beat interval, and the interval of heart stimulation is adjusted so that the heart beat interval extension after the vagus nerve stimulation is limited within a predetermined time interval. Thus, an abrupt drop of heart beat rate due to vagus nerve stimulation for suppressing sympathetic hypertonia and thereby mortal arrhythmia is prevented.

Description

Specification

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a heart treatment device and a heart treatment method for slowing down a heart rate decrease caused by vagal nerve stimulation. Background art

Of the sudden deaths, especially those caused by heart disease, are called sudden cardiac deaths, the number of which is about 50,000 annually in the country. The immediate cause of sudden cardiac death is the development of hemodynamically disrupted ventricular tachycardia—ventricular fibrillation, called lethal arrhythmias.

In ventricular tachycardia, the ventricle pulsates abnormally prematurely, and in ventricular fibrillation, the individual muscle fibers constituting the ventricle begin to excite in a chaotic manner, and the entire ventricle trembles little by little. When a fatal arrhythmia occurs, the pump function of the heart is reduced or lost, and it is impossible to pump the necessary blood to the whole body, causing loss of consciousness due to a decrease in cerebral blood flow. Failure to do so may result in death.

Implantable cardioverter defibrillators (ICD) are being used to treat patients with such a risk of sudden cardiac death. ICD performs defibrillation by giving an electric shock to the heart when the occurrence of ventricular tachycardia / ventricular fibrillation is detected. However, ICD is a so-called coping therapy device that operates after a heart abnormality has occurred, and a large electric shock for defibrillation may damage heart tissue.

At this point, cardiac activity is governed by the autonomic nervous system, but the autonomic nervous system has a sympathetic nervous system and a parasympathetic nervous system. Is the vagus nerve. Increased (strained) sympathetic activity increases heart activity (heart rate and cardiac output), and increased vagal activity decreases heart activity (heart rate). Activity in the sympathetic and vagal nerves is usually antagonistic, and the heart is stably controlled to maintain an appropriate resting heart rate, approximately 70 beats Z minutes. That is, when the sympathetic nerve is nervous, it acts on the heart excitably, whereas when the vagus nerve is nervous, it acts on the heart in a depressing manner.

Recently, there has been proposed a cardiac treatment apparatus for treating ventricular arrhythmia by performing electrical stimulation of the vagus nerve using such an action (for example, see Patent Document 1). The cardiac therapy device includes a sensor for detecting neural activity that transmits information from the autonomic nervous system to the heart and a comparator with a threshold that forms a condition for the presence of an arrhythmia. Is output depending on whether or not the neural activity matches the condition. In other words, immediately upon detecting chronic fibrillation or other dangerous tachyarrhythmias from changes in the activity of the autonomic nervous system, it activates the vagus nerve lightly for 5 seconds. Treatment is terminated when a return to the normal state is detected, but when an abnormal condition to the heart is continuously detected, treatment is continued, and a star-shaped sympathetic nerve is added if the sympathetic nerve block is advantageous. It is performed for several seconds in the ganglion.

In addition, a method and apparatus for applying electrical stimulation to the vagus nerve to prevent fatal arrhythmias have been proposed (for example, see Patent Document 2). This device for treating cardiac arrhythmias is intended to prevent or stop cardiac arrhythmias and maintain proper heart function through stimulation of heart tissue and vagus nerve. This cardiac therapy device not only compares the pre-set tachycardia detection interval threshold with the patient's pulsation, but also changes the ST portion (voltage) of the electrocardiogram suggesting acute myocardial ischemia. We also examined other factors related to ventricular tachycardia, By stimulating the vagus nerve on the basis of this, it is possible to suppress tachycardia. The cardiac arrhythmia treatment device includes a means for continuously measuring an electrocardiogram of a patient's heart, a means for detecting a characteristic of the electrocardiogram indicating tachycardia, a means for initializing a memory of a series of characteristics, and one or more Means for providing electrical stimulation to the patient's nervous system, and means for initializing a series of characteristics of the electrocardiogram following delivery of the stimulation action.

[Patent Document 1] Japanese Patent Application Laid-Open No. Hei 8 — 5 2 121

[Patent Document 2]

WO 93/21824 Pan fret (PCT / US 93/00051) Disclosure of the Invention

Electrical stimulation of the vagus nerve causes a decrease in heart rate, but a rapid decrease in heart rate causes discomfort and discomfort to the patient, and also causes arrhythmia by making the refractory period of excitement unstable. There was a problem of making it easier.

The technique described in Patent Document 1 is to address this problem, and when the activation current is supplied to the vagus nerve and the sympathetic nerve, the cardiac activity falls below a predetermined rate. Automatically starts stimulation of the heart, but the above-mentioned predetermined rate, which is the lower limit of the heart rate, can be maintained, but the rapid heart rate in the process of reaching the predetermined rate after vagal nerve stimulation is reached. It was not possible to avoid the drop in numbers, and the above problems could not be solved.

In addition, the one described in Patent Document 2 stimulates the vagus nerve in order to overcome the decrease in heart rate accompanying the stimulation of the vagus nerve, and stimulates the heart so that the patient's heart rate falls within an allowable range. Although the lower limit of the heart rate can be maintained by the heart stimulation, as in the case of Patent Document 1, a sudden heart reaching the lower limit of the heart rate is provided. It was not possible to avoid a decrease in the heart rate, and it did not solve the problem of patient discomfort, discomfort, and susceptibility to arrhythmia.

Therefore, an object of the present invention is to control cardiac stimulation so that a decrease in heart rate is within a predetermined range after vagal nerve stimulation, and to prevent a rapid decrease in heart rate due to vagal nerve stimulation.

In order to solve the above problems and achieve the object of the present invention, a heart treatment apparatus according to the present invention relates to a nerve stimulating means for stimulating a vagus nerve, a heart contraction detecting means for detecting a heart self-contraction, and a self-contraction. Heart rate measuring means for measuring the heart beat based on the detection result; heart stimulating means for stimulating the heart when no heart self-contraction is detected within a predetermined period; and heart rate measuring the heart beat Heart rate comparing means for comparing the output with a predetermined heart rate threshold value; and determining whether or not to perform vagus nerve stimulation based on the output of the heart rate comparing means. The control is performed so as to be changed based on the measured heart rate output.

Also, in the heart treatment apparatus of the present invention, the measured heartbeat output is a heartbeat interval, and the control for changing the predetermined period adds a predetermined time increment to the measured heartbeat interval. It is a feature.

Further, in a preferred embodiment of the heart treatment apparatus according to the present invention, the predetermined time increment is a fixed time interval, or the predetermined time increment corresponds to a fixed decrease in heart rate. It is characterized by

In another preferred aspect of the present invention, the predetermined time interval is a function of the measured heartbeat interval, and the function is a predetermined ratio of the measured heartbeat interval. And

Further, in the heart treatment device of the present invention. It has a limit value, and the predetermined period is adjusted so as not to exceed this limit value.

In addition, the heart treatment method of the present invention includes a step of detecting the heart's self-contraction, a step of measuring the heart beat from the detection result related to the self-contraction, and a step of detecting the heart's self-contraction within a predetermined period. Stimulating the heart if not detected, comparing the heart rate output of the detected heart beat with a predetermined heart rate threshold, and performing vagal nerve stimulation based on the result of the comparison step A step of determining whether or not the vagus nerve is stimulated in the determination step based on the measured heart rate output during a predetermined period. I have.

In a preferred embodiment of the heart treatment method according to the present invention, the measured heartbeat output is a heartbeat interval, and the step of changing the predetermined period based on the measured heartbeat output includes setting the measured heartbeat interval in advance. It is characterized by adding time and minutes.

In a preferred embodiment of the present invention, the predetermined time increment is a fixed time interval or a fixed time interval corresponding to a decrease in heart rate.

In a preferred embodiment of the present invention, the predetermined time increment is a function of the measured heartbeat interval, and the function is a predetermined ratio of the measured heartbeat interval. I have.

According to the present invention, since the heart stimulation is controlled such that the change in heart rate falls within a predetermined range after vagal nerve stimulation, it is possible to prevent a rapid change in heart rate due to vagus nerve stimulation. Become. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram showing a configuration example of a first embodiment of the heart treatment apparatus of the present invention. FIG. 2 is an arrangement diagram of the electrode lead and the stimulating electrode used in the heart treatment apparatus of the present invention on the heart.

FIG. 3 is a flowchart for explaining the operation of the first embodiment of the heart treatment apparatus of the present invention shown in FIG.

FIG. 4 is a block diagram showing a configuration example of a second embodiment of the heart treatment apparatus of the present invention.

FIG. 5 is a flowchart for explaining the operation of the second embodiment of the heart treatment apparatus of the present invention shown in FIG.

FIG. 6 is a timing chart showing the relationship between the vagus nerve stimulation and the ventricular stimulation interval in the second embodiment of the present invention shown in FIG. 4 <FIG. 7 shows the atria shown in FIG. 1 and FIG. FIG. 10 is a block diagram showing a first modified example of the Z ventricular stimulation interval control means.

FIG. 8 is a block diagram showing a second modification of the atrial Z ventricular stimulation interval control means shown in FIGS. 1 and 4. BEST MODE FOR CARRYING OUT THE INVENTION

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

Note that the embodiments described below are preferred specific examples of the present invention, and therefore, various technically preferred limitations are added. However, the scope of the present invention is particularly limited by the following description. It is not limited to these forms unless stated to limit.

First, a first embodiment of the heart treatment apparatus according to the present invention will be described with reference to the block diagram of FIG.

As used herein, the term “event” of the heart is a general term for spontaneous contractions detected in the atrium or ventricle and contractions caused by stimulating the atrium or ventricle. is there.

The heart treatment device 1 of the present invention comprises a stimulus signal to the right ventricle 22 of the heart 21. Ventricular stimulator 2 that generates a signal, a ventricular contraction detector 3 that detects contraction of the right ventricle 2 2, an atrial stimulator 4 that generates a stimulus signal to the right atrium 23 of the heart 2 1, and a right atrium 2 3, an atrial contraction detection unit 5 for detecting contraction, a nerve stimulation unit 6 for generating a nerve stimulation signal for stimulating the vagus nerve 26, a control unit 7 for controlling the interval between nerve stimulation and atrial stimulation, and an atrial contraction. An OR circuit 8 that supplies the detected signal and a signal that triggers atrial stimulation, a heart rate measurement unit 9 that receives the output of the OR circuit 8 and measures the heartbeat interval, and also supplies an output of the OR circuit 8 An atrial stimulation interval timer 10 that is reset and started to measure time; a comparing unit 11 that compares the time measured by the atrial stimulation interval timer 10 with the atrial stimulation interval set by the control unit 7; Control the setting of the vagal nerve 26 stimulation and atrial stimulation intervals Heartbeat threshold storage unit 12 that stores the heartbeat interval threshold of the heartbeat, and a heartbeat comparison unit 13 that compares the heartbeat interval measurement value measured by the heartbeat measurement unit 9 with the heartbeat interval threshold stored in the heartbeat threshold storage unit 12 And an atrioventricular delay timer 14 that starts at the output of the OR circuit 8 and stops at the output of the ventricular contraction detection unit 3, and stores an atrioventricular delay set value that stores a predetermined atrioventricular delay time. It comprises a unit 15 and an atrioventricular delay comparing unit 16 which compares the output of the atrioventricular delay timer 14 with the output of the atrioventricular delay set value storage unit 15.

The ventricular stimulating unit 2 and the ventricular contraction detecting unit 3 are connected to the ventricular stimulating and detecting electrode 18 by a common ventricular electrode lead 17, and the atrial stimulating unit 4 and the atrial contraction detecting unit 5 similarly have the atria. It is connected to an atrial stimulation detection electrode 20 via an electrode lead 19. Ventricular stimulation detecting electrode 18 and atrial stimulation Ζ detecting electrode 20 are arranged in right ventricle 22 and right atrium 23 of heart 21, respectively.

Generally, electrodes for the heart include a myocardial electrode implanted in the heart muscle, so-called myocardium, and a catheter electrode for inserting the electrode through the vena cava to the heart. Figure 2 shows the catheter electrode By way of example, both the ventricular electrode lead 17 and the atrial electrode lead 19 are initially directed from the vena cava to the right atrium 23 of the heart 21. An atrial electrode lead 19 inserted from the vena cava into the right atrium 23 hooks the tip bent in a J-shape into a bag-shaped right atrial appendage protruding from the wall of the right atrium 23. Then, the atrial stimulation / detection electrode 20 is arranged so as to contact the inner wall of the right atrial appendage. Similarly, the ventricular electrode lead 17 which enters the right atrium 23 from the vena cava enters the right ventricle 22 through the atrioventricular valve, and is provided at the distal end of the ventricular electrode lead 17. Stimulation / detection electrode 18 is placed in contact with the bottom of right ventricle 22.

Although not shown in FIG. 2, the nerve stimulating unit 6 is connected to the nerve stimulating electrode 25 via the nerve electrode lead 24, and the nerve stimulating electrode 25 is wound around the vagus nerve 26. Fixed at. The region around which the nerve stimulation electrode 25 is wound is preferably the neck region or the right central position of the lateral carotid artery. The nerve stimulation electrode 25 can be arranged so as to stimulate the vagus nerve 26 adjacent to the blood vessel wall by placing a catheter electrode in the blood vessel. In that case, the subclavian vein is preferable as the placement region.

The control unit 7 for controlling the atrial stimulation interval and the nerve stimulation is roughly divided into a neural stimulation signal control unit 27 for controlling the nerve stimulation unit 6 and an atrial stimulation interval control unit 28 for controlling the atrial stimulation interval. Consists of The atrial stimulation interval control unit 28 stores a limit value as an upper limit of the predetermined atrial stimulation interval, and a fixed time of the predetermined atrial stimulation interval. An increment value storage section 30 for storing the increment; an addition section 31 for adding the time increment stored in the increment value storage section 30 to the heartbeat interval measurement value output from the heart rate measuring means 9; 1 is compared with the limit value of the atrial stimulation interval stored in the limit value storage unit 29 in advance, and the upper limit of the output of the adder unit 31 is limited to the limit value. The output of the limit value limiter 32, the limit value memory 29, the limit value limiter 32 and the heart rate comparator 13 is supplied, and based on the output of the heart rate comparator 13 the limit value memory is 29 and an atrial stimulation interval setting unit 33 that finally selects and sets the atrial stimulation interval from the output of the limit value limiting unit 32.

Hereinafter, the operation of the first embodiment of the heart treatment apparatus of the present invention shown in FIG. 1 will be described.

First, when the atrial contraction detecting unit 5 detects the contraction of the right atrium 23, the atrial contraction detecting unit 5 supplies the output to the OR circuit 8 and also outputs the neural stimulation signal control unit 2 of the control unit 7. Supply 7 As described above, the output of the OR circuit 8 is supplied to the heart rate measuring unit 9, the atrial stimulation interval timer 10 and the atrioventricular delay timer 14, and the heart rate measuring unit 9, the atrial stimulation interval timer 10 and the atrial The timer (time measurement) of the room delay timer 14 is started.

That is, the heart rate measurement unit 9 measures the atrial heart rate interval (event interval) from an atrial event (atrial contraction detection or atrial stimulation) to the next atrial event (atrial contraction detection or atrial stimulation). Then, the heartbeat comparison unit 13 compares the heartbeat interval measured by the heartbeat measurement unit 9 with a heartbeat interval threshold stored in the heartbeat threshold storage unit 12 (for example, a heartbeat interval of 750 ms corresponding to a heart rate of 80). When the measured heartbeat interval falls below this threshold, that is, when the heart rate exceeds 80, an output is obtained from the heartbeat comparison unit 13 and the neural stimulation signal control unit 27 of the control unit 7 and the atrial stimulation It is supplied to the atrial stimulation interval setting section 33 of the interval control section 28.

The output from the atrial contraction detection unit 5 is also supplied to the nerve stimulation signal control unit 27 in addition to the output from the heartbeat comparison unit 13, and the output of the heartbeat comparison unit 13 is received because the heartbeat interval is shortened Activates the neural stimulation signal control unit 27 in relation to the detection of atrial contraction and stimulates the vagus nerve 26 To the nerve stimulating unit 6 as a trigger signal. Then, upon receiving this signal, the nerve stimulating section 6 stimulates the vagus nerve 26 with the nerve electrode lead 24 and the nerve stimulation electrode 25.

When the vagus nerve 26 is stimulated, the heart rate drops sharply, which may increase the incidence of fatal arrhythmias. In other words, as the heart rate decreases, the heartbeat interval measured by the heart rate measurement unit 9 increases. That is, since the measured value of the heart rate measuring unit 9 becomes longer than the threshold value of the heart rate threshold value storage unit 12 due to the decrease in the heart rate, no output is obtained from the heart rate comparing unit 13. Therefore, a signal for stimulating the vagus nerve 26 is not supplied from the heartbeat comparison unit 13 to the nerve stimulation signal control unit 27, and the vagus nerve 26 is not stimulated.

The output of the heart rate measurement unit 9 is supplied to the addition unit 31 of the atrial stimulation interval control unit 28, where the heart rate interval measured by the heart rate measurement unit 9 and the increment value storage unit 30 are stored in advance. The fixed time increment that has been added is added. Then, the added time interval is sent to the limit value limiting unit 32 and compared with the limit value of the atrial stimulation interval stored in the limit value storing unit 29. Then, when the new operation value to which this time is added is smaller than the limit value stored in the limit value storage unit 29, the new operation value is supplied to the atrial stimulation interval setting unit 33. Is done. The atrial stimulation interval setting unit 33 is supplied with the limit value stored in the limit value storage unit 29 and the signal from the heartbeat comparison unit 13 in addition to the new calculated value. When there is an output from 3, that is, when the heartbeat interval measured by the heartbeat measurement unit 9 does not exceed the heartbeat interval threshold stored in the heartbeat threshold storage unit 12 (for example, when the heart rate is 80 or less). In the above, the new calculated value is supplied from the atrial stimulation interval setting unit 33 to the comparison unit 11 as a threshold value for the atrial stimulation interval timer 10. Conversely, when there is no output from the heart rate comparison unit 13, that is, the heartbeat interval measured by the heart rate measurement unit 9 is stored in the heartbeat threshold value storage unit 12. If the heartbeat interval exceeds the threshold value (the heart rate is 80 or less), the new calculated value is not selected and the limit value stored in the limit value storage unit 29 is replaced with the atrial stimulation interval timer 10. The threshold value is output to the atrial stimulation interval setting unit 33 and supplied to the comparison unit 11.

The output of the atrial contraction detecting section 5 is sent to the atrioventricular delay timer 14 via the OR circuit 8, and the atrioventricular delay timer 14 is started. When the time value of the atrioventricular delay timer 14 exceeds a predetermined set value stored in the atrioventricular delay set value storage section 15, an output is obtained from the atrioventricular delay comparison section 16 and Ventricular stimulation is performed by the ventricular stimulator 2. On the other hand, if the ventricle contraction detecting unit 3 detects the ventricular contraction before the time value of the atrioventricular delay timer 14 reaches the set value stored in the atrioventricular delay set value storage unit 15, The delay timer 14 stops counting and no ventricular stimulation is performed.

FIG. 3 is a flowchart for explaining the operation of the first embodiment of the present invention.

Hereinafter, the operation of the present example will be described in detail with reference to the flowchart of FIG. First, the limit value stored in the limit value storage unit 29 of the atrial stimulation interval control unit 28 is set to, for example, a heartbeat interval of 1000 ms corresponding to a heart rate of 60. At this initialization stage, there is no output from the heartbeat comparison unit 13, and 1000 ms set in the limit value storage unit 29 is supplied to the comparison unit 11 as the output of the atrial stimulation interval setting unit 33 ( Step S l).

Next, the atrial stimulation interval timer 10 is started (step S2), and subsequently, the atrial contraction detecting section 5 determines whether or not atrial contraction is detected (step S3). If an atrial contraction is detected in the determination step S3, the heartbeat measurement unit 9 starts measuring the heartbeat interval, that is, measuring the atrial event interval (step S4), and performs atrial stimulation. The interval timer 10 is reset (step S5). Next, in the heart rate comparison unit 13, the atria measured by the heart rate measurement unit 9 It is determined whether the event interval is larger or smaller than a threshold previously stored in the heartbeat threshold storage unit 12, for example, a heartbeat interval of 750 ms corresponding to a heart rate of 80 (step S6). Then, if it is determined that the atrial event interval is, for example, 625 ms and is smaller than the threshold value of 750 ms (that is, when the heart rate exceeds 80), an output is obtained from the heart rate comparing unit 13, The output is sent to the nerve stimulation signal control unit 27 to stimulate the vagus nerve 26 (step S7).

The atrial event interval measured by the heart rate measuring unit 9 is supplied to the adding unit 31 of the atrial stimulating interval control unit 28, where the measured value of the atrial event interval is stored in the partial value storage unit 30. A fixed time increment, for example, 100 ms, stored in the memory is added (step S8). Subsequently, in the limit value limiter 32, it is determined whether or not the calculated value 725ms (625ms + 100ms) added in step S8 is larger than the limit value 1000ms previously stored in the limit value storage unit 29. It is determined (step S9). As in this case, in the determination step S9, the calculated value 725ms to which the time increment is added by the adding unit 31 is smaller than the limit value 1000ms stored in the previously set limit value storage unit 29. At this time, the new calculated value is sent from the limit value limiting section 32 to the atrial stimulation interval setting section 33, and the atrial stimulation interval setting section 33 outputs the output of the heart rate comparing section 13 generated in step S6. (Atrial event interval 625 ms is smaller than threshold 750 ms), and a new calculated value is supplied to comparator 11 as a threshold for atrial stimulation interval timer 10 (step S 10).

In determination step S6, if the atrial event interval measured by the heart rate measuring unit 9 is equal to or greater than the heartbeat interval threshold 750ms stored in the heartbeat threshold storage unit 12 (heart rate is 80 or less), and If the calculated value obtained by adding the time increment by the adding unit 31 in the judgment step S 9 is equal to or greater than the limit value 1000 ms stored in the limit value storage unit 29 (heartbeat interval is 900 ms or more, that is, the heart rate is 66 or less) ) Continues to be the limit 1000ms is supplied to the comparison unit 11 as a threshold value for the atrial stimulation interval timer 10 and the process proceeds to the next step (step S11).

If no atrial contraction is detected in the determination step S3, it is determined whether or not the atrial stimulation interval timer 10 has timed out (step S12). When the atrial stimulation interval timer 10 is timed out, that is, when the time measured by the atrial stimulation interval timer 10 exceeds the limit value (1000 ms) of the atrial stimulation interval set in step S 1 (heart rate) (Equation 60 · or less) is output from the comparing section 11 to the atrial stimulating section 4 to perform atrial stimulation (step S13). At the same time, the output of the comparison unit 11 is supplied to the heart rate measurement unit 9 via the OR circuit 8, and the measurement of the atrial event interval is started (step S14). It is sent to interval timer 10 and reset (step S15).

Next, similarly to the determination step S6, it is determined whether the atrial event interval measured by the heart rate measurement unit 9 is smaller than the heartbeat interval threshold value 750ms set in the heartbeat threshold value storage unit 12 or not. (Step S16). If the measured value of the atrial event interval is stored in the above-mentioned heartbeat threshold storage unit 12 and it is determined that the heartbeat interval threshold is smaller than 750 ms and the heart rate is more than 80, the process proceeds to step S 8. Hereafter, the processing after step S9 is performed. In the determination step S16, if the measured value of the atrial event interval measured by the heart rate measuring unit 9 is equal to or longer than the heartbeat interval threshold value 750ms stored in the heart rate threshold value storage unit 12, the atrial stimulation interval is initially set. The limit value stored in the limit value storage unit 29 remains 1000 ms (step S17), and the process proceeds to the next step.

When an atrial contraction is detected in the atrial contraction detecting section 5 or an output is issued from the comparing means 11 and an atrial stimulation is performed, the detected signal or the stimulating signal passes through the OR circuit 8 and the atrioventricular delay timer 14 To start the time measurement of the atrioventricular delay timer 14 (step S18). Then, it is determined whether or not the ventricle contraction is detected by the ventricle contraction detection unit 3 (step S19). If a ventricular contraction is detected in the decision step S19, the atrioventricular delay timer 14 stops counting (step S20) and returns to the decision step S3. On the other hand, if ventricular contraction is not detected in decision step S 19, whether the atrioventricular delay timer 14 has timed out, that is, the time measured by the atrioventricular delay timer 14, the atrioventricular delay set value storage unit It is determined whether the set value stored in 15 has been exceeded (step S21). Then, when it is determined in the determination step S21 that the atrioventricular delay timer 14 has not timed out, the flow returns to the determination step S19, and when the atrioventricular delay timer 14 has timed out, An output is output from the atrioventricular delay comparing section 16 to the ventricular stimulating section 2 to perform ventricular stimulation (step S22).

Next, a second embodiment of the heart treatment apparatus of the present invention will be described based on the block diagram of FIG. The same parts as those in the first embodiment of the present invention shown in FIG. 1 are denoted by the same reference numerals. In the first embodiment, the stimulation of the vagus nerve 26 is controlled based on the detection of atrial contraction, and the atrial stimulation interval is controlled.In the second embodiment, the detection of ventricular contraction is performed. The heartbeat interval is measured to control the vagus nerve 26 stimulation and the ventricular stimulation interval.

That is, the second embodiment of the present invention is different from the first embodiment in configuration in that the output of the comparison unit 11 is supplied to the ventricle stimulating unit 2 and the output of the ventricular contraction detecting unit 3 is OR circuit 8 And a point supplied to the nerve stimulation signal control unit 27, and a ventricle stimulation interval control unit 28A and a ventricle instead of the atrial stimulation interval control unit 28 and the atrial stimulation interval setting unit 33 in the first embodiment. The point is that a stimulus interval setting section 33 A is provided. As a result, in the first embodiment of the present invention shown in FIG. 1, the atrial stimulating unit 4, the atrial contraction detecting unit 5, the atrioventricular delay timer 14, the atrioventricular delay setting value storage unit 15, the atrioventricular delay comparing unit 16 is from the second embodiment Has been deleted.

The operation of the second embodiment of the heart treatment apparatus of the present invention will be described with reference to the flowchart shown in FIG.

First, the limit value to be stored in the limit value storage unit 29 of the ventricular stimulation interval control unit 28A is set to, for example, a heartbeat interval 1000 ms corresponding to a heart rate 60. At this initialization stage, there is no output from the heart rate comparison unit 13, and 1000 ms set in the limit value storage unit 29 is supplied to the comparison unit 11 as the output of the ventricular stimulation interval setting unit 33 A. (Step S31). Next, the ventricular stimulation interval timer 10A is started (step S32), and subsequently, the ventricular contraction detector 3 determines whether or not ventricle contraction is detected (step S33). ). If a ventricular contraction is detected in the determination step S33, the heartbeat measuring unit 9 starts measuring the heartbeat interval, that is, measuring the ventricular event interval (step S34), and performs the ventricular stimulation. The interval timer 10A is reset (step S35).

Next, it is determined whether or not the ventricular event interval (heartbeat interval) measured by the heartbeat measurement unit 9 has reached the heartbeat interval threshold 750 ms set in the heartbeat threshold storage unit 12 (step S36). When it is determined that the ventricular event interval is smaller than the threshold value 750 ms (heart rate is 80 or more), an output is obtained from the heart rate comparison unit 13, and this output is output to the nerve stimulation signal control unit 27. And the vagus nerve 26 is stimulated (step S37).

The ventricular event interval measured by the heart rate measurement unit 9 is supplied to the addition unit 31 of the ventricular stimulation interval control unit 28A, and the measured value of the ventricular event interval is stored in the increment value storage unit 30. The stored fixed time 100 minutes is added (step S38). Then, in the limit value limiting section 32, it is determined whether or not the calculated value added in step S38 is smaller than the limit value 1000ms stored in advance in the limit value storing section 29. W

Is determined (step S39). In the judgment step S39, if it is judged that the calculated value obtained by adding the time and the minute by the adding unit 31 is smaller than the limit value 1000ms stored in the previously set limit value storage unit 29, The new calculated value is sent from the limit value limiting unit 32 to the ventricular stimulation interval setting unit 33A, and the ventricular stimulation interval setting unit 33A outputs the heart rate comparison unit 13 generated in step S36. The output is obtained (the ventricular event interval is smaller than the heartbeat interval threshold), and the new calculated value is supplied to the comparison unit 11 as a threshold for the ventricular stimulation interval timer 1 OA (step S40). . '

In the determination step S36, if the ventricular event interval measured by the heart rate measurement unit 9 is larger than the heartbeat interval threshold value 750ms stored in the heart rate threshold storage unit 12 (heart rate is 80 or less), In addition, when the calculated value obtained by adding the time increment in the adding unit 31 in the judgment step S39 is larger than the limit value 1000ms stored in the limit value storing unit 29 (heartbeat interval 900ms or more, that is, If the heart rate is 66 or less, the limit value 1000 ms is continuously supplied to the comparison unit 11 as a threshold value for the ventricular stimulation interval timer 10 A, and the process proceeds to the next step (step S 41).

If no ventricular contraction is detected in determination step S33, it is determined whether ventricular stimulation interval timer 10A has timed out (step S42). If the ventricular stimulation interval timer 10A has timed out, that is, if the time measured by the ventricular stimulation interval timer 10A exceeds the limit value 1000ms of the ventricular stimulation interval set in step S31, An output is output from the comparator 11 to the ventricular stimulator 2 to perform ventricular stimulation (step S43). At the same time, the output of the comparison unit 11 is supplied to the heart rate measurement unit 9 via the OR circuit 8, and the measurement of the ventricular event interval is started (step S44). It is sent to the interval timer 1 OA and reset (step S45). Next, similarly to the determination step S36, it is determined whether or not the ventricular event interval measured by the heart rate measuring unit 9 is smaller than the heartbeat interval threshold value 750ms set in the heartbeat threshold value storage unit 12 ( Step S4 6). If it is determined that the measured ventricular event interval is smaller than the heartbeat interval threshold value 750 ms stored in the heartbeat threshold value storage unit 12, the process proceeds to step S 38, and thereafter, proceeds to step S 39. The following processing is performed. In determination step S46, if it is determined that the atrial event interval measured by the heart rate measurement unit 9 is larger than the heartbeat interval threshold 750ms stored in the heart rate threshold storage unit 12, the ventricular stimulation interval is set first. The limit value (1000 ms) stored in the stored limit value storage unit 29 is supplied to the comparison unit 11 (step S47), and the process returns to step S33.

FIG. 6 is a timing chart showing the relationship between the vagus nerve stimulation and the ventricular stimulation interval in the second embodiment of the present invention shown in FIG. 4, the ventricular stimulation interval limit value 1000 ms, the heartbeat interval threshold value 750 ms, and the time. An example is shown in which ventricular stimulation and vagal stimulation are controlled in increments of 100 ms. ₍ If atrial stimulation is used instead of ventricular stimulation, it can be applied to the first embodiment of the present invention shown in FIG. 1. Needless to say.

In the timing chart of FIG. 6, times VI, V2, V3, V4, and V5 represent times when ventricular stimulation is performed, and times R1 and R2 represent times when ventricular contraction is detected.

That is, at time VI, the ventricular stimulation interval timer 10 A is started together with the ventricular stimulation from the ventricular stimulating unit 2. Since no ventricular contraction was detected during the threshold value of the ventricular stimulation interval of 1000 ms, the ventricular stimulation interval timer 10A was determined to have timed out (limit value of 1000 ms), indicating that ventricular stimulation was performed at time V2. ing. Subsequently, at time R1, 850 ms after the ventricular stimulation is performed at time V2, the contraction of the ventricle is detected, and as a result, the ventricular stimulation interval timer 10A is reset. The ventricle measured by the heart rate measurement unit 9 at this time The event interval is 850 ms, which is larger than the heartbeat interval threshold 750 ms, and the vagus nerve 26 is not stimulated because no output is sent to the nerve stimulation signal control unit 27 from the heartbeat comparison unit 13. . The value of 850 ras is supplied to the adding unit 31 from the heart rate measuring unit 9, and this value is added to the fixed time increment 100 ms of the increment value storing unit 30. The added calculated value 950 ms is sent to the limit value limiting section 32, where it is compared with the limit value 1000 ms stored in the limit value storing section 29. Since the calculated value 950 ms is smaller than the limit value 1000 ms', the calculated value 950 ms is supplied to the ventricular stimulation interval setting unit 33 A from the limit value limiting unit 32. On the other hand, although the output from the heart rate comparing section 13 is supplied to the ventricular stimulation interval setting section 33 A, the ventricular event interval measured by the heart rate measuring section 9 is 850 ms, and the heartbeat interval threshold value is 750 ms. Therefore, no output is obtained from the heart rate comparison unit 13. When there is no output from the heart rate comparison unit 13, the ventricular stimulation interval setting unit 33 A selects the limit value 1000 ms of the limit value storage unit 29, and this value is used as the threshold value of the ventricular stimulation interval by the comparison unit 1. Sent to 1.

Next, it is assumed that the heart rate is increased, and the contraction of the regenerated ventricle is detected at time R2 625 ms after the detection of the ventricle at time R1. By detecting the ventricle at this time R2, the ventricular stimulation interval timer 10A is reset. In this case, since the measured ventricular event interval is 625 ms, which is smaller than the heartbeat interval threshold 750 ms, a signal is sent from the heartbeat comparison unit 13 to the nerve stimulation signal control unit 27, and the nerve stimulation unit 6 sends the signal to the vagus nerve. 26 stimulations are performed. At the same time, the addition unit 31 adds the time increment 100 ms stored in the increment value storage unit 30 to the ventricular event interval 625 ms from the heart rate measurement unit 9, and the calculated value 725 ms is used as the limit value limiting unit. Sent to 3 2 In the limit value limiter 3 2, the limit value limiter 3 2 is compared with the limit value 1000 ms stored in the limit value storage unit 29 and the calculated value is smaller than the limit value. The calculated value 725 ms is sent to the ventricular stimulation interval setting unit 33 A as a candidate for the next ventricular stimulation interval. At this time, since the ventricular event interval is 625 ms, which is smaller than the heartbeat interval threshold 750 ms stored in the heartbeat threshold storage unit 12, the output from the heartbeat comparison unit 13 is sent to the ventricular stimulation interval setting unit 33 A. Have been added. Therefore, the ventricular stimulation interval setting unit 33A selects and outputs the calculated value 725ms, and sends it to the comparison unit 11 as a new threshold value of the ventricular stimulation interval.

Next, if no ventricular contraction is detected during the newly set ventricular stimulation interval threshold value of 725 ms, it is determined that the ventricular stimulation interval timer 10A has timed out, and at time V3, which is 725 ms after time R2. As the ventricular stimulation is performed, the ventricular stimulation interval timer 10A is reset. At this time, the measured ventricular event interval is 725 ms, which is lower than the heartbeat interval threshold 750 ms stored in the heartbeat threshold storage unit 12, so the output from the heartbeat comparison unit 13 is the neural stimulation signal control unit 2. 7, but no stimulation of the vagus nerve 26 occurs because no ventricular contraction is detected by the ventricular contraction detector 3. The measured value 725 ms of the heart rate measuring unit 9 is supplied to the adding unit 31, and the adding unit 31 adds the time / minute 100 ms stored in the increment value storing unit 30 to obtain the calculated value 825 ms. It is sent to the ventricular stimulation interval setting unit 33 A via the limit value limiting unit 32 as a candidate for the ventricular stimulation interval. At this time, since the output of the heart rate comparison unit 13 is added to the ventricular stimulation interval setting unit 33 A, the output of the ventricular stimulation interval setting unit 33 A is a calculated value of 825 ms, and this value is a new ventricular stimulation. It is supplied to the comparison means 11 as the interval threshold.

If no ventricular contraction is detected during the new ventricular stimulation interval 825 ms, it is determined that the ventricular stimulation interval timer 10 A has timed out, and the ventricular stimulation is performed at time V4 825 ms after time V3. At the same time, the ventricular stimulation interval timer 10A is reset. Heartbeat at this time Since the ventricular event interval 825 ms measured by the measurement unit 9 is larger than the heartbeat interval threshold 750 ms, there is no output from the heartbeat comparison unit 13 and the vagus nerve 26 is not stimulated. The adder 31 adds the above-mentioned ventricular event interval of 825 ms and a fixed time increment of 100 ms, and sends a new calculated value of 925 ms from the limit value limiter 32 to the ventricular stimulation interval setting unit 33 A. Since the output from the heartbeat comparison unit 13 is not given to the stimulation interval setting unit 33A, the ventricular stimulation interval setting unit 33A selects the limit value 1000ms stored in the limit value storage unit 29, Send to comparison part 1 1. That is, the threshold of the ventricular stimulation interval returns to the limit value of 1000 ms. If no ventricular contraction is detected during 1000 ms from time V4 to time V5, the ventricular stimulation interval timer 10A times out and ventricular stimulation is performed.

FIG. 7 shows a first modification of the atrial stimulation interval control unit 28 and the ventricular stimulation interval control unit 28A in the first embodiment and the second embodiment of the present invention shown in FIGS. 1 and 4. FIG. This modification shows the atrial Z ventricular stimulus interval control unit (28, 28A) when the time increment is a predetermined ratio of the heartbeat interval.

In this modified example, an increment ratio storage section 34 and an increment value calculation section 35 are provided instead of the increment value storage section 30 in FIGS.

Hereinafter, the operation of the atrial / ventricular stimulation interval control section (28, 28A) of the first modified example shown in FIG. 7 will be described. For example, an increment rate of 20% is set in the segment ratio storage section 34. For example, if the event interval of the atrium or ventricle measured by the heart rate measuring section 9 is 600 ms, the increment value calculating section At 35, a time increment of 120ms is calculated by multiplying the value of 600ms from the heart rate measurement unit 9 by 20%. Then, the value of 600 ms from the heart rate measurement unit 9 and the value of 120 ms from the increment value calculation unit 35 are added in the addition unit 31, and a value of 720 ms is output to the limit value restriction unit 32. Limit value control section 32 compares the value of 720 ms with a fixed value of 1000 ms stored in advance in the limit value storage unit 29. In this case, the new calculated value is 720 ms and the threshold value is smaller than the limit value of 1000 ms, so the new calculated value is output from the limit value control unit 32 and the atrial / ventricular stimulation interval setting units 3 3 and 3 3 Sent to A. At this time, since there is an output from the heart rate comparison unit 13, the atrial / ventricular stimulation interval control units 33, 33 A select this new calculated value 720 ms and set it to the new threshold value of the atrial or ventricular stimulation interval. This is supplied to the comparison unit 11.

FIG. 8, like FIG. 7, shows the atrial stimulation interval control unit 28 and the ventricular stimulation interval control unit 28 in the first embodiment and the second embodiment of the present invention shown in FIG. 1 and FIG. FIG. 11 is a block diagram showing a second modification of A. This modification shows the atrial Z ventricular stimulation interval controller (28, 28A) when the time increment is a time interval corresponding to a fixed decrease in heart rate.

According to this modification, the heart rate conversion unit 36 to which the heart rate interval (atrial event interval or ventricular event interval) is supplied from the heart rate measurement unit 9 and a heart rate decrease of, for example, 20 beats per minute are provided. The set value of the reduced heart rate storage unit 37 is subtracted from the output of the heart rate conversion unit 36, and the subtraction unit 38 and the subtraction unit 3 8 A heartbeat interval conversion unit 39 for converting the output into a heartbeat interval is provided.

The operation of the atrial / ventricular stimulation interval controller (28, 28A) shown in FIG. 8 will be described below. In the heart rate decrease storage section 37, a heart rate decrease of 20 beats per minute is set. If the event interval of the atrium or ventricle measured by the heart rate measurement unit 9 is 600 ms, this value is supplied to the heart rate conversion unit 36, and the heart rate per minute 100 (60) s / 600ms). Thereafter, the subtraction unit 38 subtracts the heart rate decrease 20 stored in the heart rate decrease storage unit 37 from the heart rate 100 output from the heart rate conversion unit 36, Heart rate 8 A value of 0 is supplied from the subtraction unit 38 to the heartbeat interval conversion unit 39. The heartbeat interval converter 39 converts the heart rate 80 into a heartbeat interval of 750 ms, and supplies this value to the limit value limiter 32.

Then, the limit value limiting section 32 compares the value of 750 ms output from the heartbeat interval converting section 39 with the limit value 1000 ms stored in the limit value storing section 29. Since this new calculated value 750 ms is smaller than the limit value 1000 ms of the limit value storage unit 29, the limit value limiting unit 32 sends the new calculated value 750 ms to the atrial Z ventricular stimulation interval setting units 33, 33A. . At this time, the atrial / ventricular stimulation interval setting unit 33, 33A receives the output from the heart rate comparison unit 13 and uses the new calculated value 750 ms as the threshold value for the new atrial or ventricular stimulation interval. As described above, the first and second embodiments of the present invention and their modifications have been described. However, the present invention is not limited to the above-described embodiments, and is described in the claims. A wide range of embodiments can be adopted without departing from the scope of the present invention.

As described above, according to the present invention, the heart stimulation interval can be adjusted so that the heart rate change after the vagus nerve stimulation falls within a predetermined range, so that the present invention is also used for vagal nerve stimulation. A rapid change in heart rate can be prevented, and a fatal arrhythmia caused by a rapid change in heart rate can be suppressed.

Claims

The scope of the claims

1. Nerve stimulation means for stimulating the vagus nerve;

Heart contraction detection means for detecting the self-contraction of the heart,

Heartbeat measuring means for measuring the heartbeat from the detection result regarding the self-contraction,

Heart stimulating means for stimulating the heart if no self-contraction of the heart is detected within a predetermined period;

Heart rate comparing means for comparing a heart rate output obtained by measuring the heart beat with a predetermined heart rate threshold;

It is determined whether or not to perform vagal nerve stimulation based on the output of the heartbeat comparison means, and when the vagus nerve stimulation is performed, control is performed such that the predetermined period is changed based on the measured heartbeat output. A heart treatment device characterized by this.

2. The heart treatment device according to claim 1, wherein the measured heartbeat output is a heartbeat interval.

3. The heart treatment apparatus according to claim 2, wherein the control for changing the predetermined period is to add a predetermined time increment to the measured heartbeat interval.

4. The heart treatment device according to claim 3, wherein the predetermined time increment is a fixed time interval.

5. The heart treatment apparatus according to claim 3, wherein the predetermined time increment is a time interval corresponding to a fixed decrease in heart rate.

6. The heart treatment device according to claim 3, wherein the predetermined time increment is a function of the measured heartbeat interval.

7. The cardiac treatment apparatus according to claim 6, wherein the function is a predetermined ratio of the measured heartbeat interval.

8. The first claim, wherein the predetermined period has a limit value, and the predetermined period is adjusted so as not to exceed the limit value. Item 7. A heart treatment device according to item 1.

9. Detecting heart self-systole;

A step of measuring the heart beat from the detection result regarding the self-contraction,

Stimulating the heart if no self-contraction of the heart is detected within a predetermined time period;

Comparing a heart rate output that has detected the heart beat with a predetermined heart rate threshold;

Determining whether to perform vagus nerve stimulation based on the result of the comparison step,

A cardiac treatment method, comprising a step of changing the predetermined period based on the measured heartbeat output when vagus nerve stimulation is performed in the determining step.

10. The method for treating or treating a heart according to claim 9, wherein the measured heartbeat output is a heartbeat interval.

11. The heart according to claim 10, wherein the step of changing the predetermined period based on the measured heartbeat output is to add a predetermined time increment to the measured heartbeat interval. Method of treatment.

12. The method for treating a heart according to claim 11, wherein the predetermined time increment is a fixed time interval.

13. The heart treatment method according to claim 11, wherein the predetermined time 增 minutes is a time interval corresponding to a fixed decrease in heart rate.

14. The method according to claim 11, wherein the predetermined time increment is a function of the measured heart beat interval.

15. The method according to claim 14, wherein the function is a predetermined ratio of the measured heartbeat interval.

16. The predetermined period has a limit value, and the predetermined period is adjusted so as not to exceed the limit value. Heart treatment method according to the paragraph,