Patent Publication Number: US-2007100380-A1

Title: Heart treatment equipment and heart treatment method

Description:
TECHNICAL FIELD  
      The present invention relates to heart treatment equipment carrying out prevention and treatment of a fatal arrhythmia and more particularly relates to heart treatment equipment and a heart treatment method in which it is possible to carry out a control of a tachyarrhythmia prevention treatment method after an anti-tachyarrhythmia treatment.  
     BACKGROUND ART  
      A sudden death especially caused by a heart disease is called a heart sudden death and the number thereof reaches about annual 50,000 people within the country. The direct cause of the heart sudden death is a generation of the ventricular tachycardia which causes a failure of the hemodynamics or the ventricular fibrillation and which is called a fatal arrhythmia. In a ventricular tachycardia, the ventricle beats convulsively and abnormally rapidly and in a ventricular fibrillation, each of the muscle fibers which constitute the ventricle starts excitement disorderedly and will be in a condition of only trembling little by little as a whole ventricle. When a fatal arrhythmia occurs, the pumping function of the heart lowers or disappears and it becomes impossible to send out the required blood to the whole body, so that an atypical absence is caused in accordance with the decrease of the cerebral blood flow and a death might be caused unless an immediately appropriate treatment is conducted.  
      For a patient having a risk of such a heart sudden death, a treatment which implants an implantable cardiac defibrillator (ICD) is carried out. When an occurrence of a ventricular tachycardia or a ventricular fibrillation is detected, the ICD gives an electroshock to the heart such that a defibrillation is carried out. However, the ICD is medical treatment equipment which is to say a countermeasure therapy operating after an abnormality occurs in the heart and in addition, there is a fear that it may give a large load to the heart tissue caused by the defibrillation.  
      Now, the heart activity is put under the control of an autonomic nerve system and the autonomic nerve system has a sympathetic nerve system and a parasympathetic nerve system where the parasympathetic nerve system of the heart is a vagus nerve. The heart activity (heart rate and cardiac output) increases when the activity of the sympathetic nerve increases (under tension) and the heart activity (heart rate) decreases when the activity of the vagus nerve increases. The activities of the sympathetic nerve and the vagus nerve are usually antagonistic each other, but when the sympathetic nerve tension is accentuated excessively and its balance becomes off-balanced, arrhythmia becomes easy to occur caused by accentuation of automaticity or shortening of a refractory period in a heart muscle or in an excitation conducting system and particularly for a patient of an organic heart disease such as myocardial infarction or cardiomyopathy, a possibility of a fatal arrhythmia occurrence is to be heightened by a combination of organic lesion of the heart and accentuation of a sympathetic nerve tension.  
      As a method for preventing occurrence (generation) of such a fatal arrhythmia, there has been attempted a method in which an excessive sympathetic nerve tension is blocked directly from being transmitted to the heart by stimulating the sympathetic nerve electrically, a method in which the sympathetic nerve tension is repressed antagonistic by stimulating the vagus nerve electrically, or a trial in which a lesion portion which caused an organic change is restructured by stimulating a nerve growth in a sinus node or a ventricle muscle after applying stimulation of a level which does not increase the heart rate and the blood pressure to a ganglion stellatum which is a sympathetic nerve.  
      There was already proposed in the past, based on such a principle, effective heart treatment equipment particularly for defibrillation in which necessary energy is low with respect to tachyarrhythmia prevention and acute treatment by a nerve stimulation (for example, see Patent Reference 1). This heart treatment equipment supplies a preventative activation current to the vagus nerve and at the same time supplies a repression current to the sympathetic nerve, and the vagus nerve is lightly activated for 5 seconds immediately after a chronic fibrillation or other dangerous tachyarrhythmia is detected. Then, the medical treatment will be finished when detecting a return to a usual condition and when it is desirable for continuously detecting an abnormal condition relating to the heart, the treatment is continued. Then, if it is advantageous to block transmission (conduction) of a sympathetic nerve excitement from the brain, this block is carried out additionally in the ganglion stellatum for a few seconds. Nevertheless, in a case when an abnormal state of the heart is detected, an electroshock is supplied by a conventional method.  
      There was also proposed a method and equipment in which an electric stimulation is applied to the right ganglion stellatum in order to prevent a fatal arrhythmia (for example, see Patent Reference 2). Equipment for preventing a fatal arrhythmia described in the Patent Reference 2 is equipment in which a risk of arrhythmia occurrence is to be reduced by applying a stimulation of a level which does not increase the heart rate and the blood pressure to the right ganglion stellatum, wherein nerve stimulation energy is adjusted to be under a threshold of a nerve stimulation which increases the heart rate or the blood pressure and nevertheless, in a case when arrhythmia occurrence (generation) is detected, a corresponding arrhythmia termination treatment is to be supplied.  
      [Patent Reference 1] Jap. laid-open patent publication H8-38625  
      [Patent Reference 2] Specification of U.S. Pat. No. 6,487,450  
      However, the heart treatment equipment described in the Patent Reference 1 is not provided with a structure for reducing or stopping the activation current with respect to the vagus nerve or a repression current with respect to the sympathetic nerve after supplying an electroshock to the heart, so that there was a problem with deterioration of hemodynamics, recurrence of a fatal arrhythmia, induction of supraventricular arrhythmia such as atrial fibrillation or the like and the like.  
      Also, the arrhythmia treatment equipment described in the Patent Reference 2 is not provided with a control structure for reducing the nerve stimulation energy or for stopping the nerve stimulation subsequently to the arrhythmia termination treatment, so that it is not enough to solve a problem with deterioration of hemodynamics, recurrence of a fatal arrhythmia, induction of supraventricular arrhythmia such as atrial fibrillation or the like and the like similarly as the heart treatment equipment described in the Patent Reference 1.  
     DISCLOSURE OF THE INVENTION  
      Taking a fact that the heart is in an unstable state after an anti-tachyarrhythmia treatment into consideration and in view of the aforesaid problem with deterioration of hemodynamics, recurrence of a fatal arrhythmia and induction of supraventricular arrhythmia such as atrial fibrillation or the like if a preventive therapy which affects suppressively with respect to the heart is applied under such a situation, the present invention has an object to offer heart treatment equipment and a heart treatment method in which it is possible to deactivate the tachyarrhythmia prevention treatment or to shift to a mode of a small nerve stimulation energy in response to tachyarrhythmia detection or confirmation of tachyarrhythmia continuation.  
      In order to solve aforesaid problems and to accomplish objects of the present invention, the heart treatment equipment of the present invention includes tachyarrhythmia prevention means for preventing occurrence of tachyarrhythmia; tachyarrhythmia detection means for detecting the occurrence of tachyarrhythmia; tachyarrhythmia termination means supplying anti-tachyarrhythmia treatment for terminating the tachyarrhythmia in response to the tachyarrhythmia detection means; and control means for connecting the tachyarrhythmia prevention means and the tachyarrhythmia detection means, wherein the control means executes a control for deactvating the tachyarrhythmia prevention means in its operation in response to the tachyarrhythmia detection means.  
      Also, according to a feature of the heart treatment equipment of the present invention, there are provided with tachyarrhythmia prevention means for preventing occurrence of tachyarrhythmia; tachyarrhythmia detection means for detecting the occurrence of tachyarrhythmia; tachyarrhythmia confirmation means for confirming that the tachyarrhythmia continues in response to the tachyarrhythmia detection means; tachyarrhythmia termination means supplying anti-tachyarrhythmia treatment for terminating the tachyarrhythmia in response to the tachyarrhythmia confirmation means; and control means for connecting the tachyarrhythmia prevention means and the tachyarrhythmia confirmation means, wherein the control means executes a control for deactivating the tachyarrhythmia prevention means in its operation in response to the tachyarrhythmia confirmation means.  
      According to a preferable mode of the present invention, it has a feature for the tachyarrhythmia prevention means such that nerve stimulation means for stimulating a sympathetic nerve(ganglion stellatum) or nerve stimulation means for stimulating a parasympathetic nerve (vagus nerve) is included and particularly, the stimulation of the sympathetic nerve is a stimulation having a level which does not increase the heart rate and the blood pressure or is a stimulation which blocks transmission of the sympathetic nerve excitement and also, the stimulation of the parasympathetic nerve is a stimulation which activates the parasympathetic nerve excitement.  
      Also, according to a preferable mode of the present invention, it has a feature for an anti-tachyarrhythmia treatment which the tachyarrhythmia termination means supplies such that at least one of anti-tachyarrhythmia pacing, cardioversion and defibrillation is included. Then, further, according to a preferable mode of the present invention, there are provided with bradycardia detection means for detecting occurrence of bradycardia and bradycardia treatment means for generating a heart stimulation pulse in response to the bradycardia detection means.  
      Further, according to a preferable mode of the present invention, it has a feature such that timing means for clocking a predetermined time is included and the timing means is to set a clocking time in conformity with the anti-tachyarrhythmia treatment in response to the supply of the anti-tachyarrhythmia treatment by means of the tachyarrhythmia termination means.  
      Also, according to a preferable mode of the present invention, it has a feature such that there is provided with tachyarrhythmia termination confirmation means for confirming whether or not the tachyarrhythmia is terminated by the tachyarrhythmia termination means and a tachyarrhythmia prevention treatment is carried out by the control means after the timing means carried out clocking of a predetermined time in response to aforesaid tachyarrhythmia termination confirmation means.  
      Also, according to a preferable mode of the present invention, it has a feature such that there is provided with tachyarrhythmia termination confirmation means for confirming whether or not tachyarrhythmia terminated by the tachyarrhythmia termination means and tachyarrhythmia prevention treatment is to be carried out by the control means after clocking a time period in conformity with a supplied anti-tachyarrhythmia treatment in response to the tachyarrhythmia termination confirmation means or after the measured heart rate exceeds a predetermined threshold.  
      Also, the present invention has a feature such that there are provided with tachyarrhythmia prevention means for preventing occurrence of tachyarrhythmia by a nerve stimulation; tachyarrhythmia detection means for detecting the occurrence of tachyarrhythmia; tachyarrhythmia termination means supplying anti-tachyarrhythmia treatment for terminating the tachyarrhythmia in response to tachyarrhythmia confirmation means; and control means for connecting the tachyarrhythmia prevention means and the tachyarrhythmia confirmation means, wherein the nerve stimulation by the tachyarrhythmia prevention means operates at least in a first operation mode and a second operation mode and at the same time, nerve stimulation energy of the second operation mode is set to be lower than nerve stimulation energy of the first operation mode such that the control means is to operate the tachyarrhythmia prevention means in the second operation mode in response to the tachyarrhythmia detection means.  
      Also, the present invention has a feature such that there are provided with tachyarrhythmia prevention means for preventing occurrence of tachyarrhythmia by a nerve stimulation; tachyarrhythmia detection means for detecting the occurrence of tachyarrhythmia; tachyarrhythmia confirmation means for confirming that aforesaid tachyarrhythmia continues in response to the tachyarrhythmia detection means; tachyarrhythmia termination means supplying anti-tachyarrhythmia treatment for terminating aforesaid tachyarrhythmia in response to tachyarrhythmia confirmation means; and control means for connecting the tachyarrhythmia prevention means and aforesaid tachyarrhythmia confirmation means, wherein the nerve stimulation by the tachyarrhythmia prevention means operates at least in a first operation mode and a second operation mode and at the same time, nerve stimulation energy of the second operation mode is set to be lower than nerve stimulation energy of the first operation mode such that the control means is to operate the tachyarrhythmia prevention means in the second operation mode in response to the tachyarrhythmia detection means.  
      It should be noted in connection with the technical feature in the above-mentioned heart treatment equipment that the present invention is offered as an invention of a heart treatment method which has similar features.  
      According to the present invention, there is provided with a structure for reducing or stopping activation current with respect to a vagus nerve or repression current with respect to a sympathetic nerve after an electroshock supply to the heart such as cardioversion, defibrillation or the like, so that it is possible to prevent deterioration of hemodynamics, recurrence of fatal arrhythmia and induction of supraventricular arrhythmia such as atrial fibrillation or the like. Also, tachyarrhythmia prevention treatment is canceled or is shifted to a mode having a smaller nerve stimulation energy in response to tachyarrhythmia detection or continuation confirmation of tachyarrhythmia, so that it is possible for a patient having a risk of heart sudden death to receive a moderate preventive treatment of fatal arrhythmia such as tachyarrhytmia or the like. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       FIG. 1  is a block diagram showing a constitutional example of a first exemplified embodiment according to heart treatment equipment of the present invention;  
       FIG. 2  is an arrangement diagram of an electrode lead and a stimulation electrode to a heart, which are used in the heart treatment equipment of the present invention;  
       FIG. 3 a  flow diagram for explaining operation of the first exemplified embodiment according to the present invention;  
       FIG. 4 a  flow diagram also for explaining operation of the first exemplified embodiment according to the present invention;  
       FIG. 5  is a block diagram showing a constitutional example of a second exemplified embodiment according to the heart treatment equipment of the present invention;  
       FIG. 6 a  flow diagram for explaining operation of the second exemplified embodiment according to the present invention;  
       FIG. 7 a  flow diagram also for explaining operation of the second exemplified embodiment according to the present invention;  
       FIG. 8  is a block diagram showing a constitutional example of a third exemplified embodiment according to the heart treatment equipment of the present invention;  
       FIG. 9 a  flow diagram for explaining operation of the third exemplified embodiment according to the present invention;  
       FIG. 10 a  flow diagram also for explaining operation of the third exemplified embodiment according to the present invention;  
       FIG. 11  is a block diagram showing a constitutional example of a fourth exemplified embodiment according to the heart treatment equipment of the present invention;  
       FIG. 12 a  flow diagram for explaining operation of the fourth exemplified embodiment according to the present invention;  
       FIG. 13 a  flow diagram also for explaining operation of the fourth exemplified embodiment according to the present invention;  
       FIG. 14  is a block diagram showing a constitutional example of a fifth exemplified embodiment according to the heart treatment equipment of the present invention;  
       FIG. 15 a  flow diagram for explaining operation of the fifth exemplified embodiment according to the present invention; and  
       FIG. 16  is a flow diagram also for explaining operation of the fifth exemplified embodiment according to the present invention. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
      Hereinafter, a first exemplified embodiment of the heart treatment equipment according to the present invention will be explained with reference to the block diagram shown in  FIG. 1 .  
      Heart treatment equipment  1  of the present invention is constituted by a heart contraction detection unit  2  for detecting contraction of a heart  38 , a tachyarrhythmia detection unit  3  for observing an output of the heart contraction detection unit  2  full-time and for detecting tachyarrhythmia, a tachyarrhythmia confirmation unit  4  for confirming continuous detection of the tachyarrhythmia, a tachyarrhythmia termination confirmation unit  5  for confirming that the tachyarrhythmia terminated by an anti-tachyarrhythmia treatment, a tachyarrhythmia prevention unit  6  for preventing the tachyarrhythmia by stimulating a vagus nerve  41  or a ganglion stellatum  44  of a sympathetic nerve  45 , a control unit  7  for carrying out a control for deactivating or activating the operation of the tachyarrhythmia prevention unit  6 , a timing unit  8  for determining a switching timing of the operation of the tachyarrhythmia prevention unit  6  by means of the control unit  7 , a bradycardia treatment unit  9  for carrying out bradycardia treatment when bradycardia was detected by the heart contraction detection unit  2 , a pacing pulse generation unit  10  for receiving a signal from the bradycardia treatment unit  9  and for generating a pacing pulse, a shock pulse generation unit  11  for applying a shock pulse to the heart  38 , and a tachyarrhythmia termination unit  12  for supplying a signal for terminating the tachyarrhythmia to the pacing pulse generation unit  10  and the shock pulse generation unit  11 .  
      The tachyarrhythmia prevention unit  6  is constituted by two means of a sympathetic nerve stimulation unit  13  for supplying a stimulation signal to the ganglion stellatum  44  and a parasympathetic nerve stimulation unit  14  for supplying a stimulation signal to the vagus nerve  41  and is operated by a tachyarrhythmia prevention program. Then, a sympathetic nerve stimulation unit  13  is constituted by a blocking stimulation unit  15  and a sub-threshold stimulation unit  16  and a parasympathetic nerve stimulation unit  14  is constituted by an activating stimulation unit  17 . Here, the blocking stimulation unit  15  is a unit for preventing accentuation of sympathetic nerve tension which heightens a risk of a tachyarrhythmia occurrence from being transmitted from the brain to the heart  38  and the sub-threshold stimulation unit  16  is a unit for restructuring the heart  38  to an organ characteristic in which tachyarrhythmia is seldom caused by applying a weak stimulation of a level which does not increase a heart rate or a blood pressure to the ganglion stellatum  44  with respect to the heart  38  having an organ characteristic in which it is easy for tachyarrhythmia to occur particularly such as after a myocardial infarction and by stimulating a nerve figuration in a sinus node (not shown) or a ventricle muscle. Usually, the sub-threshold stimulation unit  16  is operated and the blocking stimulation unit  15  will be operated in order to block it in a case when accentuation of a sympathetic nerve tension such as a heart rate increase or the like is detected. On the other hand, an activating stimulation unit  17  of a parasympathetic nerve stimulation unit  14  stimulates the vagus nerve  41  by a detection of a sympathetic nerve tension accentuation such as a heart rate increase or the like and represses the sympathetic nerve tension antagonistically and at the same time, reduces a risk of tachyarrhythmia occurrence by lowering oxygen consumption of the heart  38  after lowering the heart rate.  
      The control unit  7  is constituted by a deactivation unit  18  configured to cancel the preventive treatment by the tachyarrhythmia prevention unit  6  based on receiving a signal from the tachyarrhythmia detection unit  3  or the tachyarrhythmia confirmation unit  4  and an activation unit  19  for carrying out the preventive treatment by the tachyarrhythmia prevention unit  6  according to a signal from the timing unit  8 . Outputs of the deactivation unit  18  and the activation unit  19  are supplied to any one of the blocking stimulation unit  15 , the sub-threshold stimulation unit  16  and the activating stimulation unit  17  in the tachyarrhythmia prevention unit  6 .  
      Also, the timing unit  8  is constituted by a tachyarrhythmia preventing treatment change-over timer  20  for starting clocking by an output the tachyarrhythmia termination confirmation unit  5  which confirms termination of the tachyarrhythmia, a change-over time memory unit  21  for storing a period from the termination confirmation of the tachyarrhythmia until the tachyarrhythmia preventing treatment is started, and a comparator unit  22  for emanating an output with respect to the activation unit  19  of the control unit  7  when the clocking time of the tachyarrhythmia preventing treatment change-over timer  20  reaches the time period stored in the change-over time memory unit  21 .  
      The bradycardia treatment unit  9  is a so-called a pacemaker and is constituted by a first bradycardia treatment unit  23  for carrying out a bradycardia treatment at a normal time, a second bradycardia treatment unit  24  for carrying out a bradycardia treatment after the tachyarrhythmia termination in which a stimulation parameter of a stimulation rate, a stimulation volatage or the like is different from that in the first bradycardia treatment unit  23 , a bradycardia treatment change-over timer  25  for starting clocking by an output of the tachyarrhythmia termination confirmation unit  5 , a bradycardia treatment change-over time memory unit  26  for storing time at which the bradycardia treatment after the tachyarrhythmia termination is changed-over from the second bradycardia treatment unit  24  to the first bradycardia treatment unit  23 , a comparator unit  27  for emanating an output when the clocking time of the bradycardia treatment change-over timer  25  reaches the time stored in the bradycardia treatment change-over time memory unit  26 , and a bradycardia treatment selection unit  28  for receiving the output from the comparator unit  27  and for changing-over from the second bradycardia treatment unit  24  to the first bradycardia treatment unit  23 .  
      Also, the tachyarrhythmia termination unit  12  is constituted by an anti-tachyarrhythmia pacing unit  30  which is effective for a slow tachycardia, a cardioversion unit  31  for carrying out direct-current power distribution in synchronism with heart contraction detection with respect to a rapid tachycardia, a defibrillation unit  32  for carrying out direct-current power distribution with respect to fibrillation and an anti-tachyarrhythmia treatment output change-over unit  33  for selecting either one of the anti-tachyarrhythmia pacing unit  30 , the cardioversion unit  31  and the defibrillation unit  32  according to the output of the tachyarrhythmia detecton unit  3 .  
      Here, the anti-tachyarrhythmia pacing unit  30  is a unit for stimulating the heart  38  at a rate higher than the detected tachyarrhythmia rate with respect to a relatively slow tachycardia after a predetermined coupling time from a heart contraction detection and the stimulation of the heart  38  is carried out by being connected to the pacing pulse generation unit  10  through the anti-tachyarrhythmia treatment output change-over unit  33 . Also, the cardioversion unit  31  is a unit for carrying out direct-current power distribution with respect to a relatively rapid tachycardia in synchronism with the heart contraction detection and the direct-current power distribution is carried out by being connected to the shock pulse generation unit  11  through the anti-tachyarrhythmia treatment output change-over unit  33 . Then, the defibrillation unit  32  is a unit for carrying out direct-current power distribution with respect to fibrillation and at that time, if it is possible, the direct-current power distribution is to be carried out in synchronism with the heart contraction detection. This direct-current power distribution, similarly as the cardioversion, is carried out by being connected to the shock pulse generation unit  11  through the anti-tachyarrhythmia treatment output change-over unit  33 . In this manner, the anti-tachyarrhythmia treatment output change-over unit  33  is change-over means for being responsive to the output of the tachyarrhythmia detection unit  3  and for carrying out a connection by changing-over the selected treatment to the pacing pulse generation unit  10  or the shock pulse generation unit  11 .  
      Here, the pacing pulse generation unit  10  is a unit for generating a stimulation output for the bradycardia treatment and the anti-tachyarrhythmia pacing treatment and usually, a pulse having pulse width of 1 msec and amplitude of 10V at the maximum is emanated. Since the stimulation threshold becomes high during the tachyarrhythmia, the stimulation output of the anti-tachyarrhythmia pacing treatment is set to be higher than that of a usual bradycardia treatment. Also, the shock pulse generation unit  11  is a unit to be used as a stimulation output of the cardioversion treatment and the defibrillation treatment and usually, energy of 0.1 to 5 joule for the cardioversion or energy of 30 joule at the maximum for the defibrillation is emanated as a monophasic or biphasic pulse having pulse width of 6 msec. Usually, a biphasic pulse which is superior for efficiency of the defibrillation is selected. A voltage of approximately 700 volts at the maximum is applied for the defibrillation treatment.  
      The heart contraction detection unit  2  and the pacing pulse generation unit  10  are connected to a heart stimulation/detection electrode  35  through a common heart electrode lead  34  and the shock pulse generation unit  11  is connected with an electrode  37  for supplying a shock pulse through a heart electrode lead  36 .  FIG. 2  shows an arrangement relation of the heart stimulation/detection electrode  35  and the electrode  37  for supplying a shock pulse in the heart.  FIG. 2  is an example in which the heart stimulation/detection electrode  35  and the electrode  37  for supplying a shock pulse are arranged by means of a catheter electrode. The catheter electrode is introduced from the large vein to the right atrium of the heart  38 , enters into the right ventricle passing through the auriculoventricular valve and the tip portion thereof is placed therein so as to be contacted with the lowermost portion of the right ventricle. This catheter electrode is covered by a sheath such as silicon, urethane or the like which has biocompatibility and the heart electrode lead  34  and the heart electrode lead  36  which are insulated electrically each other pass through the inside thereof. The heart stimulation/detection electrode  35  is arranged at the tip portion of the catheter electrode and connected with the heart electrode lead  34 . Also, the electrodes  37  for supplying a shock pulse each of which has a large surface area are arranged at a portion on which the catheter electrode is positioned in the right ventricle and in the right atrium to the large vein and they are connected with the heart electrode lead  36 . The electrode  37  for supplying a shock pulse is constituted as a coil shaped structure and it can be placed flexibly even in a heart.  
      In the example of this  FIG. 2 , owing to a fact that the heart detection electrode  35  arranged at the lowermost portion in the right ventricle observes the heart activity full-time, ventricular tachycardia or ventricular fibrillation is detected, and an anti-tachyarrhythmia pacing treatment is to be carried out with respect to a slow ventricular tachycardia through the heart stimulation electrode  35  arranged at the lowermost portion in the right ventricle and a cardioversion treatment or a defibrillation treatment is to be carried out with respect to a rapid ventricular tachycardia or a ventricular fibrillation by the shock pulse generation unit  11  between two apart electrodes of the electrodes  37  for supplying a shock pulse or between the electrode  37  for supplying a shock pulse and a case which is not shown of the heart treatment equipment  1 .  
      Also, it may be constituted such that the supraventricular tachycardia or the atrial fibrillation is detected by arranging the heart stimulation/detection electrode  35  and the electrode  37  for supplying a shock pulse within the atrium and an anti-tachyarrhythmia pacing treatment is to be carried out with respect to a slow supraventricular tachycardia through the heart stimulation electrode  35  arranged in the right atrium and a cardioversion treatment or a defibrillation treatment is to be carried out with respect to a rapid supraventricular tachycardia or an atrial fibrillation by the shock pulse generation unit  11  between the electrode  37  for supplying a shock pulse and a case which is not shown of the heart treatment equipment  1 .  
      In addition, the parasympathetic nerve stimulation unit  14  of the tachyarrhythmia prevention unit  6  is connected to a vagus nerve stimulation electrode  40  by way of a parasympathetic nerve electrode lead  39  and also, the sympathetic nerve stimulation unit  13  is connected to a sympathetic nerve stimulation electrode  43  through a sympathetic nerve electrode lead  42 . The vagus nerve stimulation electrode  40  is fixed in a state that it is wound around the vagus nerve  41 . A right central position of a neck portion region or an external carotid artery is preferable for a region on which the vagus nerve stimulation electrode  40  is wound around. Also, the sympathetic nerve stimulation electrode  43  is fixed by being wound around a body portion which is a thick portion of the ganglion stellatum  44  having a flat star shape. In addition, it is also possible to stimulate by winding it directly around the heart nerve  45  coming out of the ganglion stellatum  44 .  
      Hereinafter, it will be explained with respect to the operation of the first embodiment of the heart treatment equipment according to the present invention shown in  FIG. 1 . First, a heart (ventricle) contraction is detected by the heart contraction detection unit  2 . The heart contraction information detected by the heart contraction detection unit  2  is transmitted to the tachyarrhythmia detection unit  3 , the tachyarrhythmia confirmation unit  4  and the tachyarrhythmia termination confirmation unit  5  and at the same time, it is supplied to the bradycardia treatment unit  9 , the tachyarrhythmia prevention unit  6  and the tachyarrhythmia termination unit  12 .  
      The tachyarrhythmia detection unit  3  observes the output of the heart contraction detection unit  2 , detects a tachyarrhythmia and at the same time, makes a classification depending on the degree of the tachyarrhythmia, and an anti-tachyarrhythmia treatment corresponding to the situation of the classified tachyarrhythmia is to be selected. More specifically, the tachyarrhythmia which is heartbeats of a predetermined rate or more and is detected by the tachyarrhythmia detection unit  3  is further classified into a tachycardia and a fibrillation according to the degree of its rate. Then, further, the tachycardia is classified into a slow tachycardia and a rapid tachycardia, and there are applied an anti-tachyarrhythmia pacing treatment for the slow tachycardia, a cardioversion treatment for the rapid tachycardia and a defibrillation treatment for the fibrillation correspondingly. With respect to the correspondence making of the tachyarrhythmia detection/classify/treatment method, it is also possible to add criterion such as rate stability (whether or not the tachyarrhythmia rate is stable), suddenness (whether or not the tachyarrhythmia was caused suddenly), an electrocardiogram configuration (QRS width) or the like. When a corresponding anti-tachyarrhythmia treatment is selected according to the detection/classification of the tachyarrhythmia, a switching instruction to a selected anti-tachyarrhythmia treatment is transmitted from the tachyarrhythmia detection unit  3  with respect to the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12 . Then, in a case when the selected anti-tachyarrhythmia treatment is an anti-tachyarrhythmia pacing, an output is transmitted from the anti-tachyarrhythmia treatment output change-over unit  33  with respect to the pacing pulse generation unit  10  and at the same time, an output is also transmitted with respect to the tachyarrhythmia termination confirmation unit  5  and a tachyarrhythmia termination confirmation is carried out.  
      As described above, when a rapid tachycardia is detected by the tachyarrhythmia detection unit  3 , a cardioversion treatment is to be applied and when a fibrillation is detected, a defibrillation treatment is to be applied and, in this case, a process is requested in which the output of the heart contraction detection unit  2  is observed and it is confirmed by the tachyarrhythmia confirmation unit  4  whether or not the detected tachyarrhythmia continues during a period until a predetermined amount of energy corresponding to the cardioversion treatment or the defibrillation treatment is charged in a capacitor which is not shown in the shock pulse generation unit  11 . Generally, 1 to 2 seconds are required for the charging time by the cardioversion treatment and 7 to 9 seconds for the defibrillation treatment. Then, only in a case when it is confirmed that the tachyarrhythmia continues until a time point at which the charging to the capacitor in the shock pulse generation unit  11  is completed, an execution instruction of the cardioversion treatment or the defibrillation treatment is transmitted from the tachyarrhythmia confirmation unit  4  with respect to the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  and at the same time, an instruction is transmitted with respect to the deactivation unit  18  of the control unit  7  so as to deactivate the tachyarrhythmia prevention unit  6 . On the other hand, when a spontaneous termination of the detected tachyarrhythmia is confirmed, an instruction for releasing the selected cardioversion treatment or defibrillation treatment is transmitted with respect to the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12 .  
      The tachyarrhythmia termination confirmation unit  5  receives a signal showing an execution of a selected anti-tachyarrhythmia treatment from the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12 , observes the output of the heart contraction detection unit  2  and when it is confirmed that the detected tachyarrhythmia terminated, the tachyarrhythmia preventing treatment change-over timer  20  of the timing unit  8  and the bradycardia treatment change-over timer  25  of the bradycardia treatment unit  9  are made to start thereby.  
      When receiving a instruction for deactivating tachyarrhythmia prevention from the tachyarrhythmia detection unit  3  or the tachyarrhythmia confirmation unit  4 , the deactivation unit  18  of the control unit  7  emanates a signal to the tachyarrhythmia prevention unit  6 , and the stimulation to the vagus nerve  41  by the activating stimulation unit  17  and the stimulation to the ganglion stellatum  44  by the blocking stimulation unit  15  and the sub-threshold stimulation unit  16  are made to stop thereby.  
      Also, the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  obtains an output from the tachyarrhythmia detection unit  3  or the tachyarrhythmia confirmation unit  4 , selects any one of the anti-tachyarrhythmia pacing treatment, the cardioversion treatment and the defibrillation treatment in response to the tachyarrhythmia classification detected by the tachyarrhythmia detection unit  3  and in case of an anti-tachyarrhythmia pacing treatment, it supplies an output of the anti-tachyarrhythmia pacing unit  30  to the pacing pulse generation unit  10 . Then, when the instruction from the tachyarrhythmia detection unit  3  is a cardioversion treatment or a defibrillation treatment, the anti-tachyarrhythmia treatment output change-over unit  33  selects an output of the cardioversion unit  31  or the defibrillation unit  32  and supplies it to the shock pulse generation unit  11 .  
      In a case when the anti-tachyarrhythmia pacing treatment is selected, the anti-tachyarrhythmia treatment output change-over unit  33  connects the anti-tachyarrhythmia pacing unit  30  to the pacing pulse generation unit  10  and starts an anti-tachyarrhythmia pacing treatment at once. In a case when a cardioversion or a defibrillation treatment is selected, the cardioversion unit  31  or the defibrillation unit  32  is connected to the shock pulse generation unit  11 , an amount of energy corresponding to each treatment is set in the shock pulse generation unit  11  and charging is started. When it is transmitted from the tachyarrhythmia confirmation unit  4  during the charging operation or after completion of the charging that the tachyarrhythmia termination is confirmed, a charging stop instruction and an instruction of internal discharge are carried out with respect to the shock pulse generation unit  11 . Then, the connection between the cardioversion unit  31  or the defibrillation unit  32  and the shock pulse generation unit  11  is to be released. On the other hand, when it is confirmed in the tachyarrhythmia confirmation unit  4  that the tachyarrhythmia continues after the charging completion in the shock pulse generation unit  11 , an instruction for carrying out direct-current power distribution to the heart  38  is transmitted with respect to the shock pulse generation unit  11 .  
      Next, the bradycardia treatment unit  9  is a unit for carrying out a usual bradycardia treatment and a bradycardia treatment after a tachyarrhythmia termination confirmation differently and the first bradycardia treatment unit  23  is used for the usual bradycardia treatment. More specifically, the first bradycardia treatment unit  23  has a function of a usual pacemaker for carrying out a stimulation of the heart  38  by a predetermined rate in a case when the output of the heart contraction detection unit  2  goes under the predetermined rate. The stimulation of the heart  38  in this case is carried out by the pacing pulse generation unit  10  through the bradycardia treatment selection unit  28 .  
      Also, the bradycardia treatment after the tachyarrhythmia termination confirmation is carried out by the second bradycardia treatment unit  24 . In the second bradycardia treatment unit  24 , the stimulation output thereof is set to be high as compared with that of a usual bradycardia treatment carried out in the first bradycardia treatment unit  23  by being preparing for an increase of a stimulation threshold of the heart  38  (necessary stimulation energy for beating the heart  38 ) after an anti-tachyarrhythmia treatment. Also, it is also possible to set the stimulation rate to be high for an early recovery of hemodynamics after an anti-tachyarrhythmia treatment. Further, it is constituted for preventing tachyarrhythmia recurrence by heart stimulation just after a tachyarrhythmia termination such that it can be set for the bradycardia treatment to be started at whichever time point after the tachyarrhythmia termination.  
      The change over of the first bradycardia treatment unit  23  and the second bradycardia treatment unit  24  is carried out by the bradycardia treatment selection unit  28 . More specifically, when a signal from the tachyarrhythmia termination confirmation unit  5  is supplied to the bradycardia treatment change-over timer  25 , the bradycardia treatment change-over timer  25  resets the clocking content until that moment and starts clocking. In synchronism with the start of this bradycardia treatment change-over timer  25 , the bradycardia treatment selection unit  28  selects the second bradycardia treatment unit  24  in order to apply a necessary bradycardia treatment after a tachyarrhythmia termination confirmation. Then, when the clocking time of the bradycardia treatment change-over timer  25  reaches the time stored in the bradycardia treatment change-over time memory unit  26 , the comparator unit  27  emanates an output and receiving this output, the bradycardia treatment selection unit  28  changes-over from the second bradycardia treatment unit  24  again to the first bradycardia treatment unit  23  which is a usual bradycardia treatment. Also, the output signal of the comparator unit  27  is also supplied to the bradycardia treatment change-over timer  25 , it stops the clocking of the bradycardia treatment change-over timer  25  and at the same time resets the clocking content thereof.  
      Next, the operation of the timing unit  8  will be explained. First, when a tachyarrhythmia termination confirmation signal from the tachyarrhythmia termination confirmation unit  5  is supplied to the tachyarrhythmia preventing treatment change-over timer  20  of the timing unit  8 , the tachyarrhythmia preventing treatment change-over timer  20  resets the clocking content until that moment and starts the clocking. Then, when the tachyarrhythmia preventing treatment change-over timer  20  makes clocking of a predetermined time after a tacyarrhythmia termiantion confirmation, that is, the time stored in the change-over time memory unit  21 , the comparator unit  22  emanates an output to the activation unit  19  of the control unit  7 , a tacyarrhythmia prevention treatment by the tachyarrhythmia prevention unit  6  is restarted. At that time, the output signal of the comparator unit  22  is also supplied to the tachyarrhythmia preventing treatment change-over timer  20 , so that the clocking of the tachyarrhythmia preventing treatment change-over timer  20  is stopped and at the same time, its clocking content is reset.  
      Hereinafter, the operation of the first exemplified embodiment according to the present invention will be explained in detail by using flow diagrams shown in  FIG. 3  and  FIG. 4 .  
      First, as shown in  FIG. 3 , a tachyarrhythmia preventing treatment program of the tachyarrhythmia prevention unit  6  is activated by a signal from the activation unit  19  of the control unit  7  (step S 1 ) and at the same time, “True” is written in an tachyarrhythmia preventing treatment activation flag, which is not shown, of the tachyarrhythmia prevention unit  6  (step S 2 ). Next, in the timing unit  8 , the tachyarrhythmia preventing treatment change-over timer  20  is stopped/reset (step S 3 ), in the bradycardia treatment unit  9 , the first bradycardia treatment mode of the first bradycardia treatment unit  23  is selected by the bradycardia treatment selection unit  28  (step S 4 ) and at the same time, the bradycardia treatment change-over timer  25  is stopped/reset (step S 5 ).  
      Next, in the heart contraction detection unit  2 , it is judged whether or not a bradycardia was detected (step S 6 ) and in a case when a bradycardia was detected, a bradycardia treatment is supplied by the pacing pulse generation unit  10  with respect to the heart  38  (step S 7 ). In a case in judgment step S 6  when a bradycardia was not detected, it is judged in the tachyarrhythmia detection unit  3  subsequently whether or not a tachyarrhythmia was detected (step S 8 ) and in a case when a tachyarrhythmia was detected, a signal is transmitted to the tachyarrhythmia termination unit  12  and a tachyarrhythmia terminating treatment corresponding to the detected tachyarrhythmia is selected among the anti-tachyarrhythmia pacing, the cardioversion and the defibrillation (step S 9 ). Thereafter, the flow proceeds to  1 A of  FIG. 4 .  
      In a case when a bradycardia treatment was supplied in step S 7  or when a tachyarrhythmia was not detected in judgment step S 8 , it is judged whether or not the tachyarrhythmia preventing treatment change-over timer  20  of the timing unit  8  is timeout (step S 10 ). In a case when the tachyarrhythmia preventing treatment change-over timer  20  is timeout, that is, in a case when the tachyarrhythmia preventing treatment change-over timer  20  made clocking beyond the time stored in the change-over time memory unit  21 , a signal is transmitted to the activation unit  19  of the control unit  7  so as to activate the tachyarrhythmia preventing treatment program (step S 11 ) and at the same time, “True” is written in the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  (step S 12 ), and subsequently, the tachyarrhythmia preventing treatment change-over timer  20  is stopped/reset (step S 13 ).  
      Next, in a case when it is judged in judgment step S 10  that the tachyarrhythmia preventing treatment change-over timer  20  is not timeout and after the tachyarrhythmia preventing treatment change-over timer  20  is stopped/reset in step S 13 , it is judged whether or not the bradycardia treatment change-over timer  25  in the bradycardia treatment unit  9  is timeout, that is, whether or not the bradycardia treatment change-over timer  25  made clocking beyond the time stored in the bradycardia treatment change-over time memory unit  26  (step S 14 ).  
      Then, when it is judged that the bradycardia treatment change-over timer  25  is timeout, the flow returns to the selection of the first bradycardia treatment mode in step S 4  and in a case when the bradycardia treatment change-over timer  25  is not timeout, a new bradycardia detection is waited for in judgment step S 6 .  
      Next, it will be explained with respect to the operation of the first exemplified embodiment according to the present invention after the tachyarrhythmia terminating treatment was selected in step S 9  according to a flow diagram of  FIG. 4 .  
      First, it is judged whether or not an anti-tachyarrhythmia pacing treatment is selected for the anti-tachyarrhythmia treatment (tachyarrhythmia terminating treatment) in the tachyarrhythmia termination unit  12  (step S 15 ). In a case when the anti-tachyarrhythmia pacing treatment is selected, the deactivation unit  18  of the control unit  7  is operated so as to deactivate the tachyarrhythmia preventing treatment of the tachyarrhythmia prevention unit  6  (step S 16 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  (step S 17 ), and subsequently, the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the anti-tachyarrhythmia pacing unit  30  and the pacing pulse generation unit  10  and an anti-tachyarrhythmia pacing is supplied with respect to the heart  38  (step S 18 ).  
      In a case when an anti-tachyarrhythmia pacing is not selected in judgment step S 15 , it is judged next whether or not a cardioversion treatment is selected (step S 19 ). In a case when the cardioversion treatment is selected, the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the cardioversion unit  31  and the shock pulse generation unit  11  and charging of a predetermined amount of energy corresponding to the cardioversion treatment is carried out with respect to a capacitor of the shock pulse generation unit  11 . In the tachyarrhythmia confirmation unit  4 , it is confirmed for a period until the charging to this capacitor is completed whether or not the tachyarrhythmia is continuing (step S 20 ). Then, in a case when the tachyarrhythmia is confirmed to be continuing, a signal is transmitted from the deactivation unit  18  of the control unit  7  to the tachyarrhythmia prevention unit  6  and the tachyarrhythmia preventing treatment program is stopped (step S 21 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  (step S 22 ), and subsequently, a cardioversion treatment by the cardioversion unit  31  which was connected by the anti-tachyarrhythmia treatment output change-over unit  33  is supplied to the heart  38  through the shock pulse generation unit  11  (step S 23 ).  
      When the anti-tachyarrhythmia pacing treatment is not selected in judgment step S 15  and when the cardioversion treatment is not selected in judgment step S 19 , that is, when a defibrillation treatment is selected (step S 24 ), the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the defibrillation unit  32  and the shock pulse generation unit  11  and charging of a predetermined amount of energy corresponding to the defibrillation treatment is carried out with respect to a capacitor of the shock pulse generation unit  11 . In the tachyarrhythmia confirmation unit  4 , it is confirmed for a period until the charging to this capacitor is completed whether or not the tachyarrhythmia is continuing (step S 25 ). Then, in a case when the tachyarrhythmia is confirmed to be continuing, the deactivation unit  18  of the control unit  7  is operated and the tachyarrhythmia preventing treatment of the tachyarrhythmia prevention unit  6  is stopped (step S 26 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  (step S 27 ), and subsequently, a defibrillation treatment by the defibrillation unit  32  which was connected by the anti-tachyarrhythmia treatment output change-over unit  33  is supplied to the heart  38  through the shock pulse generation unit  11  (step S 28 ).  
      Next, after the anti-tachyarrhythmia pacing treatment in step S 18 , the cardioversion treatment in step S 23  or the defibrillation treatment in step S 28  is supplied with respect to the heart  38 , it is judged in the tachyarrhythmia termination confirmation unit  5  whether or not the tachyarrhythmia was terminated (step S 29 ). Then, in a case when the tachyarrhythmia is confirmed to be terminated, the tachyarrhythmia preventing treatment change-over timer  20  of the timing unit  8  is reset/started (step S 30 ), and subsequently, the bradycardia treatment change-over timer  25  of the bradycardia treatment unit  9  is reset/started (step S 31 ) and at the same time, a second bradycardia treatment mode of the second bradycardia treatment unit  24  is selected by the bradycardia treatment selection unit  28  (step S 32 ) and the flow returns to judgment step S 10  in  FIG. 3 .  
      In a case when termination of the tachyarrhythmia is not confirmed in judgment step S 29 , the flow returns to step S 9  in  FIG. 3  and selection of the tachyarrhythmia terminating treatment is again carried out, but in the selection of this tachyarrhythmia termination treatment, augmentation of the applied energy, change of the tachyarrhythmia terminating treatment method (for example, treatment method change from cardioversion to defibrillation) or the like is carried out in a stepwise manner according to a predetermined treatment plan.  
      In a case when continuation of the tachyarrhythmia is not confirmed in judgment step S 20  and judgment step S 25 , that is, in a case when the tachyarrhythmia terminated spontaneously amid the charging to the capacitor of the shock pulse generation unit  11 , stop of the charging, internal discharge of the charging energy and releasing of the connection of the cardioversion unit  31  of the tachyarrhythmia termination unit  12  or the defibrillation unit  32  and the shock pulse generation unit  11  are carried out and at the same time, it is judged whether or not the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  is “True” (step S 33 ). Then, in a case when the tachyarrhythmia preventing treatment activation flag is “True”, that is, when the tachyarrhythmia preventing treatment of the tachyarrhythmia prevention unit  6  is activated, the flow returns to judgment step S 10  in  FIG. 3  and in a case when the tachyarrhythmia preventing treatment activation flag is not “True”, that is, when the tachyarrhythmia preventing treatment of the tachyarrhythmia prevention unit  6  is not activated, it is assumed that the possibility that the heart is still in an unstable situation is high so that processes subsequent to step S 30 , which are sequences after the tachyarrhythmia termination is carried out through the tachyarrhythmia termination confirmation unit  5 .  
       FIG. 5  is a block constitutional diagram showing a second exemplified embodiment of the heart treatment equipment according to the present invention. The portion which is different from that of the first exemplified embodiment shown in  FIG. 1  lies in the constitution of the timing unit  8 . Other constitutions are same as those of the block constitutional diagram in  FIG. 1 , so that the same reference numerals are put thereon and the explanation thereof will be omitted.  
      In the first exemplified embodiment of the present invention, the time period from the confirmation of the tachyarrhythmia termination to the restart of the tachyarrhythmia preventing treatment is stored in the change-over time memory unit  21  without relation to the tachyarrhythmia situation, but in the second exemplified embodiment of the present invention, the time period from the confirmation of aforesaid tachyarrhythmia termination to restart of the tachyarrhythmia preventing treatment is distinguished in three steps depending on the tachyarrhythmia situation. More specifically, the timing unit  8  in the second exemplified embodiment of the present invention is constituted by a tachyarrhythmia preventing treatment change-over timer  20  which starts clocking according to the output of the tachyarrthmia termination confirmation unit  5 , a first period memory unit  46  which stores a time period from the tachyarrhythmia termination confirmation after the anti-tachyarrhythmia treatment by the anti-tachyarrhythmia pacing treatment until the tachyarrhythmia prevention unit  6  is activated, a second period memory unit  47  which stores a time period from the tachyarrhythmia termination confirmation after the anti-tachyarrhythmia treatment the cardioversion treatment until the tachyarrhythmia prevention unit  6  is activated, a third period memory unit  48  which stores a time period from the tachyarrhythmia termination confirmation after the anti-tachyarrhythmia treatment by the defibrillation treatment until the tachyarrhythmia prevention unit  6  is activated, a change-over time selection unit  49  for selecting any one of aforesaid first period memory unit  46  to the third period memory unit  48  depending on the tachyarrhythmia situation detected by the tachyarrhythmia detection unit  3  and for supplying it to the comparator unit  22 , and a comparator unit  22  for comparing aforesaid selected changing-over time and the time which the tachyarrhythmia preventing treatment change-over timer  20  makes clocking and for supplying a signal to the activation unit  19  of the control unit  7  in a case when the time clocked in the tachyarrhythmia preventing treatment change-over timer  20  exceeds aforesaid selected stored time.  
      Usually, the stored value of the third period memory unit  48  which is a changing-over time with respect to the defibrillation treatment is set to be longer than the stored values of the second period memory unit  47  with respect to the cardioversion and of the first period memory unit  46  with respect to the anti-tachyarrhythmia pacing treatment and also, the stored value of the second period memory unit  47  which is a changing-over time with respect to the cardioversion treatment is set to be longer than the stored value of the first period memory unit  46  with respect to the anti-tachyarrhythmia pacing. This is because it can be considered such that the stronger energy is applied to the heart, the longer the time period in which the heart is unstable becomes.  
      According to the second exemplified embodiment of the present invention, when a tachyarrhythmia is detected in the tachyarrhythmia detection unit  3 , any one is selected among the first period memory unit  46 , the second period memory unit  47  and the third period memory unit  48  by the change-over time selection unit  49  depending on the tachyarrhythmia situation and the selected time is made to be a threshold of the comparator unit  22 . Thereafter, when the tachyarrhythmia termination is confirmed in the tachyarrhythmia termination confirmation unit  5 , the tachyarrhythmia preventing treatment change-over timer  20  starts clocking and when it reaches aforesaid selected threshold, the comparator unit  22  emanates an output to the activation unit  19  of the control unit  7  so as to restart the tachyarrhythmia preventing treatment by the tachyarrhythmia prevention unit  6 .  
      Hereinafter, it will be explained with respect to the operation of the second exemplified embodiment of the present invention in detail according to  FIG. 6  and  FIG. 7 . The flow diagram of  FIG. 6  is same as the flow diagram of  FIG. 3 , but reference numerals of respective steps therein are made to be different from those of the first exemplified embodiment, so that it will be explained also by including the repetitive portions thereof.  
      First, the tachyarrhythmia preventing treatment of the tachyarrhythmia prevention unit  6  is activated by the signal from the activation unit  19  of the control unit  7  (step S 34 ) and at the same time, “True” is written in the tachyarrhythmia preventing treatment activation flag, which is not shown, of the tachyarrhythmia prevention unit  6  (step S 35 ). Next, in the timing unit  8 , the tachyarrhythmia preventing treatment change-over timer  20  is stopped/reset (step S 36 ) and in the bradycardia treatment unit  9 , the first bradycardia treatment mode of the first bradycardia treatment unit  23  is selected by the bradycardia treatment selection unit  28  (step S 37 ) and at the same time, the bradycardia treatment change-over timer  25  is stopped/reset (step S 38 ).  
      Next, it is judged whether or not a bradycardia was detected in the heart contraction detection unit  2  (step S 39 ) and in a case when a bradycardia was detected, a bradycardia treatment is supplied by the pacing pulse generation unit  10  with respect to the heart  38  (step S 40 ). In a case when a bradycardia was not detected in judgment step S 39 , it is judged subsequently whether or not a tachyarrhythmia was detected in the tachyarrhythmia detection unit  3  (step S 41 ) and in a case when a tachyarrhythmia was detected, a signal is transmitted to the tachyarrhythmia termination unit  12  and a tachyarrhythmia terminating treatment corresponding to the detected tachyarrhythmia is selected among the anti-tachyarrhythmia pacing, the cardioversion and the defibrillation (step S 42 ). Thereafter, the flow proceeds to  2 A of  FIG. 7 .  
      In a case when a bradycardia treatment is supplied in step S 40  or a tachyarrhythmia was not detected in judgment step S 41 , it is judged whether or not the tachyarrhythmia preventing treatment change-over timer  20  of the timing unit  8  is timeout (step S 43 ). In a case when the tachyarrhythmia preventing treatment change-over timer  20  is timeout, that is, in a case when the tachyarrhythmia preventing treatment change-over timer  20  made clocking beyond the time stored in any one of the first period memory unit  46 , the second period memory unit  47  or the third period memory unit  48  which is selected by the change-over time selection unit  49 , a signal is transmitted to the activation unit  19  of the control unit  7  so as to activate the tachyarrhythmia preventing treatment program (step S 44 ) and at the same time, “True” is written in the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  (step S 45 ), and subsequently, the tachyarrhythmia preventing treatment change-over timer  20  is stopped/reset (step S 46 ).  
      Next, in a case when it is judged in judgment step S 43  that the tachyarrhythmia preventing treatment change-over timer  20  is not timeout and after the tachyarrhythmia preventing treatment change-over timer  20  was stopped/reset in step S 46 , it is judged whether or not the bradycardia treatment change-over timer  25  in the bradycardia treatment unit  9  is timeout, that is, whether or not the bradycardia treatment change-over timer  25  made clocking beyond the time stored in the bradycardia treatment change-over time memory unit  26  (step S 47 ).  
      Then, when it is judged that the bradycardia treatment change-over timer  25  is timeout, the flow returns to the selection of the first bradycardia treatment mode in step S 37  and in a case when the bradycardia treatment change-over timer  25  is not timeout, a new bradycardia detection is waited for in judgment step S 39 .  
      Next, it will be explained with respect to the operation of the second exemplified embodiment of the present invention after the selection of the tachyarrhythmia terminating treatment was carried out in step S 42  according to a flow diagram of  FIG. 7 .  
      First, it is judged whether or not an anti-tachyarrhythmia pacing treatment is selected as the anti-tachyarrhythmia treatment (tachyarrhythmia terminating treatment) in the tachyarrhythmia termination unit  12  (step S 48 ). In a case when the anti-tachyarrhythmia pacing treatment is selected, the deactivation unit  18  of the control unit  7  is operated so as to deavtivate the tachyarrhythmia preventing treatment program of the tachyarrhythmia prevention unit  6  (step S 49 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  (step S 50 ), and subsequently, the change-over time selection unit  49  of the timing unit  8  selects the time stored in the first period memory unit  46  as a threshold time of the tachyarrhythmia preventing treatment change-over timer  20  (step S 51 ) and thereafter, the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the anti-tachyarrhythmia pacing unit  30  and the pacing pulse generation unit  10  and supplies anti-tachyarrhythmia pacing with respect to the heart  38  (step S 52 ).  
      In a case when the anti-tachyarrhythmia pacing is not selected in judgment step S 48 , it is judged next whether or not a cardioversion treatment is selected (step S 53 ). In a case when the cardioversion treatment is selected, the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the cardioversion unit  31  and the shock pulse generation unit  11  and charging of a predetermined amount of energy corresponding to the cardioversion treatment is carried out with respect to the capacitor of the shock pulse generation unit  11 . It is confirmed during the period until the charging to the capacitor is completed in the tachyarrhythmia confirmation unit  4  whether or not the tachyarrhythmia is continuing (step S 54 ). Then, in a case when it was confirmed that the tachyarrhythmia is continuing, a signal is transmitted from the deactivation unit  18  of the control unit  7  to the tachyarrhythmia prevention unit  6  so as to deactivate the tachyarrhythmia preventing treatment program (step S 55 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  (step S 56 ), and subsequently, the change-over time selection unit  49  of the timing unit  8  selects the time stored in the second period memory unit  47  as the threshold time of the tachyarrhythmia preventing treatment change-over timer  20  (step S 57 ) and thereafter, a cardioversion treatment by the cardioversion unit  31  is supplied to the heart  38  through the shock pulse generation unit  11  (step S 58 ).  
      When the anti-tachyarrhythmia pacing treatment is not selected in judgment step s 48  and when the cardioversion treatment is not selected in judgment step S 53  either, that is, when the defibrillation treatment is selected (step S 59 ), the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the defibrillation unit  32  and the shock pulse generation unit  11  and charging of a predetermined amount of energy corresponding to the defibrillation treatment is carried out with respect to the capacitor of the shock pulse generation unit  11 . It is confirmed whether or not the tachyarrhythmia is continuing in the tachyarrhythmia confirmation unit  4  during the period until the charging to the capacitor is completed (step S 60 ). Then, in a case when it is confirmed that the tachyarrhythmia is continuing, the deactivation unit  18  of the control unit  7  is operated so as to deactivate the tachyarrhythmia preventing treatment program of the tachyarrhythmia prevention unit  6  (step S 61 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  (step S 62 ), and subsequently, the change-over time selection unit  49  of the timing unit  8  selects the time stored in the third period memory unit  48  as the threshold time of the tachyarrhythmia preventing treatment change-over timer  20  (step S 63 ) and thereafter, a defibrillation treatment by the defibrillation unit  32  is supplied to the heart  38  through the shock pulse generation unit  11  (step S 64 ).  
      Next, after the anti-tachyarrhythmia pacing treatment of step S 52 , the cardioversion treatment of step S 58  or the defibrillation treatment of step S 64  is supplied with respect to the heart  38 , it is judged in the tachyarrhythmia termination confirmation unit  5  whether or not the tachyarrhythmia is terminated (step S 65 ). Then, in a case when it is confirmed that the tachyarrhythmia terminated, the tachyarrhythmia preventing treatment change-over timer  20  of the timing unit  8  is reset/started (step S 66 ) and subsequently, the bradycardia treatment change-over timer  25  of the bradycardia treatment unit  9  is reset/started(step S 67 ) and at the same time, the second bradycardia treatment mode of the second bradycardia treatment unit  24  is selected by the bradycardia treatment selection unit  28  (step S 68 ) and the flow returns to judgment step S 43  of  FIG. 6 .  
      In a case when the tachyarrhythmia termination is not confirmed in judgment step S 65 , the flow returns to step S 42  of  FIG. 6  and selection of the tachyarrhythmia terminating treatment is again carried out, but in this selection of the tachyarrhythmia terminating treatment, augmentation of the applied energy, change of the tachyarrhythmia terminating treatment method or the like is carried out in a stepwise manner according to a predetermined treatment plan.  
      In a case when continuation of the tachyarrhythmia is not confirmed in judgment step S 54  and judgment step S 60 , that is, in a case when the tachyarrhythmia terminated spontaneously amid the charging to the capacitor of the shock pulse generation unit  11 , releasing of charging stop, internal discharge of the charging energy and connection between the cardioversion unit  31  of the tachyarrhythmia termination unit  12  or the defibrillation unit  32  and the shock pulse generation unit  11  are carried out and at the same time, it is judged whether or not the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  is “True” (step S 69 ). Then, in a case when the tachyarrhythmia preventing treatment activation flag is “True”, that is, when the tachyarrhythmia preventing treatment of the tachyarrhythmia prevention unit  6  is activated, the flow returns to judgment step S 43  of  FIG. 6 . On the other hand, in a case when the tachyarrhythmia preventing treatment activation flag is not “True”, that is, when the tachyarrhythmia preventing treatment of the tachyarrhythmia prevention unit  6  is not activated, it is assumed that the possibility that the heart is still in an unstable situation is high so that processes subsequent to step S 66 , which are sequences after the tachyarrhythmia termination are carried out through the tachyarrhythmia termination confirmation unit  5 . At that time, in the change-over time selection unit  49  of the timing unit  8 , selection of any one of the first period memory unit  46 , the second period memory unit  47  and the third period memory unit  48  corresponding to the tachyarrhythmia terminating treatment carried out just before is maintained and activation of the tachyarrhythmia preventing treatment of the tachyarrhythmia prevention unit  6  is controlled according to the time stored in this selected memory unit.  
       FIG. 8  is a block constitutional diagram showing a third exemplified embodiment of the heart treatment equipment according to the present invention. Portions which are different from those of the first exemplified embodiment of the present invention shown in  FIG. 1  and those of the second exemplified embodiment shown in  FIG. 5  lie in that a heartbeat measuring unit  50  is provided instead of the timing unit  8 . Other constitutional portions are same as those of the block constitutional diagrams of  FIG. 1  and  FIG. 5 , so that the same reference numerals are put thereon and the explanation thereof will be omitted.  
      More specifically, the heartbeat measuring unit  50  of the third exemplified embodiment according to the present invention is constituted by a heart rate measuring unit  51  supplied with an output of the heart contraction detection unit  2  and an output of the tachyarrhythmia termination confirmation unit  5 , a heart rate threshold memory unit  52  for storing a predetermined heart rate threshold and a comparator unit  53  for emanating an output to the activation unit  19  of the control unit  7  when the measured value of the heart rate measuring unit  51  reaches the heart rate threshold stored in the heart rate threshold memory unit  52 .  
      Then, the heart rate measuring unit  51  measures the heart rate detected by the heart contraction detection unit  2  after the tachyarrhythmia termination confirmation of the tachyarrhythmia termination confirmation unit  5  and when the measured numeric value reaches the heart rate threshold stored in the heart rate threshold memory unit  52 , the comparator unit  53  transmits an output to the activation unit  19  and depending thereon, the tachyarrhythmia prevention unit  6  is activated and the tachyarrhythmia preventing treatment is carried out.  
      Hereinafter, it will be explained in detail with respect to the operation of the third exemplified embodiment of the present invention according to  FIG. 9  and  FIG. 10 .  
      First, the tachyarrhythmia preventing treatment program of the tachyarrhythmia prevention unit  6  is actiated by the signal from the activation unit  19  of the control unit  7  (step S 70 ) and at the same time, “True” is written in the tachyarrhythmia preventing treatment activation flag, which is not shown, of the tachyarrhythmia prevention unit  6  (step S 71 ). Then, in the bradycardia treatment unit  9 , the first bradycardia treatment mode of the first bradycardia treatment unit  23  is selected by the bradycardia treatment selection unit  28  (step S 72 ) and at the same time, the bradycardia treatment change-over timer  25  is stopped/reset (step S 73 ).  
      Next, it is judged in the heart contraction detection unit  2  whether or not a bradycardia was detected (step S 74 ) and in a case when a bradycardia was detected, a bradycardia treatment is supplied by the pacing pulse generation unit  10  with respect to the heart  38  (step S 75 ). In a case when a bradycardia was not detected in judgment step S 74 , it is judged subsequently whether or not a tachyarrhythmia was detected in the tachyarrhythmia detection unit  3  (step S 76 ) and in a case when a tachyarrhythmia was detected, a signal is transmitted to the tachyarrhythmia termination unit  12 , a tachyarrhythmia terminating treatment corresponding to the detected tachyarrhythmia is selected among the anti-tachyarrhythmia pacing, the cardioversion and the defibrillation (step S 77 ), and the flow proceeds to  3 A of  FIG. 10 .  
      In a case when a bradycardia treatment was supplied in step S 75  or a tachyarrhythmia was not detected in judgment step S 76 , it is judged whether or not the tachyarrhythmia preventing treatment activation flag in the tachyarrhythmia prevention unit  6  is “True” (step S 78 ). Then, in a case when the tachyarrhythmia preventing treatment activation flag is not “True”, that is, when the tachyarrhythmia prevention treatment of the tachyarrhythmia prevention unit  6  is not activated, a heart rate measurement is carried out by the heart rate measuring unit  51  of the heartbeat measuring unit  50  (step S 79 ) and it is judged whether or not this measured heart rate is bigger than the heart rate threshold stored in the heart rate threshold memory unit  52  (step S 80 ).  
      Then, when the measured heart rate is bigger than the heart rate threshold, a control signal is transmitted to the activation unit  19  of the control unit  7  and the tachyarrhythmia preventing treatment of the tachyarrhythmia prevention unit  6  is carried out (step S 81 ) and at the same time, the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  is change to “True” (step S 82 ).  
      Next, in a case when the tachyarrhythmia preventing treatment activation flag was “True” in judgment step S 78 , in a case when it was judged in judgment step S 80  that the measured heart rate is not bigger than the heart rate threshold and in a case when tachyarrhythmia preventing treatment was activated in step S 81  and the tachyarrhythmia preventing treatment activation flag was changed to “True” in step S 82 , it is judged whether or not the bradycardia treatment change-over timer  25  in the bradycardia treatment unit  9  is timeout, that is, whether or not the bradycardia treatment change-over timer  25  made clocking beyond the time stored in the bradycardia treatment change-over time memory unit  26  (step S 83 ).  
      Then, when it is judged that the bradycardia treatment change-over timer  25  is timeout, the flow returns to the selection of the first bradycardia treatment mode in step S 72  and in a case when the bradycardia treatment change-over timer  25  is not timeout, a new bradycardia detection is waited for in judgment step S 74 .  
      Next, it will be explained with respect to the operation of the third exemplified embodiment of the present invention after the selection of the tachyarrhythmia terminating treatment was carried out in the step S 77  (after  3 A) according to the flow diagram of  FIG. 10 .  
      First, it is judged whether or not an anti-tachyarrhythmia pacing treatment is selected as an anti-tachyarrhythmia treatment (tachyarrhythmia terminating treatment) in the tachyarrhythmia termination unit  12  (step S 84 ). In a case when an anti-tachyarrhythmia pacing treatment is selected, the deactivation unit  18  of the control unit  7  is operated so as to deactivate the tachyarrhythmia preventing treatment program of the tachyarrhythmia prevention unit  6  (step S 85 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  (step S 86 ) and subsequently, the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the anti-tachyarrhythmia pacing unit  30  and the pacing pulse generation unit  10  and an anti-tachyarrhythmia pacing is supplied with respect to the heart  38  (step S 87 ).  
      In a case when the anti-tachyarrhythmia pacing is not selected in judgment step S 84 , it is judged next whether or not a cardioversion treatment is selected (step S 88 ). In a case when the cardioversion treatment is selected, the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the cardioversion unit  31  and the shock pulse generation unit  11  and charging of a predetermined amount of energy corresponding to the cardioversion treatment is carried out with respect to the capacitor of the shock pulse generation unit  11 . It is confirmed whether or not the tachyarrhythmia is continuing in the tachyarrhythmia confirmation unit  4  during the period until the charging to the capacitor is completed (step S 89 ). Then, in a case when it was confirmed that the tachyarrhythmia is continuing, a signal is transmitted from the deactivation unit  18  of the control unit  7  to the tachyarrhythmia prevention unit  6  so as to deactivate the tachyarrhythmia preventing treatment program (step S 90 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  (step S 91 ) and subsequently, a cardioversion treatment by the cardioversion unit  31  which was connected by the anti-tachyarrhythmia treatment output change-over unit  33  is supplied to the heart  38  through the shock pulse generation unit  11  (step S 92 ).  
      When the anti-tachyarrhythmia pacing treatment is not selected in judgment step S 84  and when the cardioversion treatment is not selected in judgment step S 88  either, that is, when the defibrillation treatment is selected (step S 93 ), the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the defibrillation unit  32  and the shock pulse generation unit  11  and charging of a predetermined amount of energy corresponding to the defibrillation treatment is carried out with respect to the capacitor of the shock pulse generation unit  11 . It is confirmed whether or not the tachyarrhythmia is continuing in the tachyarrhythmia confirmation unit  4  during the period until the charging to the capacitor is completed (step S 94 ). Then, in a case when it was confirmed that the tachyarrhythmia is continuing, the tachyarrhythmia preventing treatment of the tachyarrhythmia prevention unit  6  is canceled by operating the deactivation unit  18  of the control unit  7  (step S 95 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  (step S 96 ) and subsequently, a defibrillation treatment by the defibrillation unit  32  which was connected by the anti-tachyarrhythmia treatment output change-over unit  33  is supplied to the heart  38  through the shock pulse generation unit  11  (step S 97 ).  
      Next, after the anti-tachyarrhythmia pacing treatment of step S 87 , the cardioversion treatment of step S 92  or the defibrillation treatment of step S 97  is supplied with respect to the heart  38 , it is judged in the tachyarrhythmia termination confirmation unit  5  whether or not the tachyarrhythmia is terminated (step S 98 ). Then, in a case when it is confirmed that the tachyarrhythmia terminated, the bradycardia treatment change-over timer  25  of the bradycardia treatment unit  9  is reset/started (step S 99 ) and at the same time, the second bradycardia treatment mode of the second bradycardia treatment unit  24  is selected by the bradycardia treatment selection unit  28  (step S 100 ) and the flow returns to judgment step S 78  of  FIG. 9 .  
      In a case when the tachyarrhythmia termination is not confirmed in judgment step S 98 , the flow returns to step S 77  of  FIG. 9  and selection of the tachyarrhythmia terminating treatment is again carried out, but in this selection of the tachyarrhythmia terminating treatment, augmentation of the applied energy, change of the tachyarrhythmia terminating treatment method or the like is carried out in a stepwise manner according to a predetermined treatment plan.  
      In a case when continuation of the tachyarrhythmia is not confirmed in judgment step S 89  and judgment step S 94 , that is, in a case when the tachyarrhythmia terminated spontaneously amid the charging to the capacitor of the shock pulse generation unit  11 , releasing of charging stop, internal discharge of the charging energy and connection between the cardioversion unit  31  of the tachyarrhythmia termination unit  12  or the defibrillation unit  32  and the shock pulse generation unit  11  are carried out and at the same time, it is judged whether or not the tachyarrhythmia preventing treatment activation flag of the tachyarrhythmia prevention unit  6  is “True” (step S 101 ). Then, in a case when the tachyarrhythmia preventing treatment activation flag is “True”, that is, when the tachyarrhythmia preventing treatment of the tachyarrhythmia prevention unit  6  is activated, the flow returns to judgment step S 83  of  FIG. 9  and in a case when the tachyarrhythmia preventing treatment activation flag is not “True”, that is, when the tachyarrhythmia preventing treatment program of the tachyarrhythmia prevention unit  6  is not activated, it is assumed that the possibility that the heart is still in an unstable situation is high so that processes subsequent to step S 99 , which are sequences after the tachyarrhythmia termination are carried out through the tachyarrhythmia termination confirmation unit  5 .  
       FIG. 11  is a block constitutional diagram showing a fourth exemplified embodiment of the heart treatment equipment according to the present invention. Portions which are different from those of the first exemplified embodiment of the present invention shown in  FIG. 1  lie in the constitutions of the tachyarrhythmia prevention unit  6  and the control unit  7 . More specifically, the tachyarrhythmia prevention unit  6  in this example is constituted for carrying out only vagus nerve stimulation and there is not provided with means for stimulating a sympathetic nerve such as a ganglion stellatum block or the like. Other constitutions are same as those of the block constitutional diagrams of  FIG. 1 , so that the same reference numerals are put thereon and the explanation thereof will be omitted.  
      As shown in  FIG. 11 , in the fourth exemplified embodiment of the present invention, a vagus nerve stimulation and tachyarrhythmia prevention unit  55  is used instead of the tachyarrhythmia prevention unit  6  of the first exemplified embodiment. It is possible for the vagus nerve stimulation and tachyarrhythmia prevention unit  55  to generate a plurality of stimulations having different stimulation frequencies with respect to the vagus nerve  41 . More specifically, the vagus nerve stimulation and tachyarrhythmia prevention unit  55  of this example is constituted by a first operation mode stimulation frequency memory unit  56  for storing stimulation frequency f 1  of the first operation mode, a second operation mode stimulation frequency memory unit  57  for storing stimulation frequency f 2  of a second operation mode the frequency of which is lower than the stimulation frequency f 1  of the first operation mode, a selection unit  58  for selecting either one of the stimulation frequency f 1  of the first mode and the stimulation frequency f 2  of the second mode, a nerve stimulation parameter setting unit  59  for setting the stimulation frequency selected by the selection unit  58  to a nerve stimulation signal parameter, a nerve stimulation control unit  60  for receiving an output of the heart contraction detection unit  2  and for controlling the stimulation of the vagus nerve  41 , and a nerve stimulation unit  61  for being controlled by the nerve stimulation control unit  60  and for generating a nerve stimulation signal using the parameter which is set by the nerve stimulation parameter setting unit  59  with respect to the vagus nerve  41 .  
      Also, the control unit  7  is constituted by a first control unit  62  for controlling the selection unit  58  of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  in response to outputs of the tachyarrhythmia detection unit  3  and the tachyarrhythmia confirmation unit  4  and a second control unit  63  for receiving an output from the comparator unit  22  of the timing unit  8  and for supplying a signal to the selection unit  58  of the vagus nerve stimulation and tachyarrhythmia prevention unit  55 .  
      It is programmed according to the fourth exemplified embodiment of the present invention shown in this  FIG. 11  such that the selection unit  58  of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  will select the second operation mode stimulation frequency f 2  by the first control unit  62  of the control unit  7  on an occasion of the tachyarrhythmia detection by the tachyarrhythmia detection unit  3  or the tachyarrhythmia confirmation unit  4  and the stimulation of the vagus nerve  41  will be carried out by a relatively weak energy. However, when the tachyarrhythmia termination is confirmed in the tachyarrhythmia termination confirmation unit  5  and the time stored in the change-over time memory unit  21  elapses after the tachyarrhythmia preventing treatment change-over timer  20  starts clocking, an output is emanated from the comparator unit  22  to the second control unit  63  of the control unit  7  and the selection unit  58  of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  selects the stimulation frequency f 1  of the first operation mode. Then, it is constituted in this case such that the stimulation of the vagus nerve  41  is to be carried out by a relatively strong energy.  
      It should be noted in this example that a constitution for shifting to a mode of small stimulation energy is employed by changing only the stimulation frequency among the nerve stimulation signal parameters in response to the tachyarrhythmia detection, but it is not obsessed with this mode and it is also possible to shift to a mode of small stimulation energy by changing at least one of stimulation frequency, pulse width, a number of pulses, pulse current, pulse voltage, delay time, rest time and repetition times or a plurality of parameters selected from these for the nerve stimulation signal parameter.  
      Hereinafter, it will be explained with respect to the operation of the fourth exemplified embodiment of the present invention in detail according to  FIG. 12  and  FIG. 13 .  
      First, the selection unit  58  of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  selects the stimulation frequency f 1  of the first operation mode as an initial value and stimulation of the vagus nerve  41  is carried out by a stimulation waveform having relatively high energy (step S 102 ). Next, “True” is written in the tachyarrhythmia preventing treatment mode flag, which is not shown, of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  (step S 103 ). Then, the tachyarrhythmia preventing treatment change-over timer  20  is stopped/reset in the timing unit  8  (step S 104 ), the first bradycardia treatment mode of the first bradycardia treatment unit  23  is selected by the bradycardia treatment selection unit  28  in the bradycardia treatment unit  9  (step S 105 ) and at the same time, the bradycardia treatment change-over timer  25  is stopped/reset (step S 106 ).  
      Next, it is judged whether or not a bradycardia was detected in the heart contraction detection unit  2  (step S 107 ) and in a case when a bradycardia was detected, a bradycardia treatment is supplied by the pacing pulse generation unit  10  with respect to the heart  38  (step S 108 ). In a case when a bradycardia was not detected in judgment step S 107 , it is judged subsequently whether or not a tachyarrhythmia was detected in the tachyarrhythmia detection unit  3  (step S 109 ) and in a case when a tachyarrhythmia was detected, a signal is transmitted to the tachyarrhythmia termination unit  12  and a tachyarrhythmia terminating treatment corresponding to the detected tachyarrhythmia is selected among the anti-tachyarrhythmia pacing, the cardioversion and the defibrillation (step S 110 ) Thereafter, the flow proceeds to  4 A of  FIG. 13 .  
      In a case when a bradycardia treatment is supplied in step S 108  or a tachyarrhythmia was not detected in judgment step S 109 , it is judged whether or not the tachyarrhythmia preventing treatment change-over timer  20  of the timing unit  8  is timeout (step S 111 ). In a case when the tachyarrhythmia preventing treatment change-over timer  20  is timeout, that is, in a case when the tachyarrhythmia preventing treatment change-over timer  20  made clocking beyond the time stored in change-over time memory unit  21 , a signal is transmitted to the selection unit  58  through the second control unit  63  of the control unit  7  and the stimulation frequency f 1  of the first operation mode is selected so as to give a relatively strong stimulation to the vagus nerve  41  (step S 112 ) and at the same time, “True” is written in the tachyarrhythmia preventing treatment mode flag of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  (step S 113 ), and subsequently, the tachyarrhythmia preventing treatment change-over timer  20  is stopped/reset (step S 114 ).  
      Next, in a case when it is judged in judgment step S 111  that the tachyarrhythmia preventing treatment change-over timer  20  is not timeout and after the tachyarrhythmia preventing treatment change-over timer  20  was stopped/reset in step S 114 , it is judged whether or not the bradycardia treatment change-over timer  25  in the bradycardia treatment unit  9  is timeout, that is, whether or not the bradycardia treatment change-over timer  25  made clocking beyond the time stored in the bradycardia treatment change-over time memory unit  26  (step S 115 ).  
      Then, when it is judged that the bradycardia treatment change-over timer  25  is timeout, the flow returns to the selection of the first bradycardia treatment mode in step S 105  and in a case when the bradycardia treatment change-over timer  25  is not timeout, a new bradycardia detection is waited for in judgment step S 107 .  
      Next, it will be explained with respect to the operation of the fourth exemplified embodiment of the present invention after the selection of the tachyarrhythmia terminating treatment was carried out in the step S 110  (after  4 A) according to the flow diagram of  FIG. 13 .  
      First, it is judged whether or not an anti-tachyarrhythmia pacing treatment is selected as an anti-tachyarrhythmia treatment (tachyarrhythmia terminating treatment) in the tachyarrhythmia termination unit  12  (step S 116 ). In a case when an anti-tachyarrhythmia pacing treatment is selected, the first control unit  62  of the control unit  7  is activated so as to select the stimulation frequency f 2  of the second operation mode in the selection unit  58  of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  (step S 117 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment mode flag of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  (step S 118 ) and subsequently, the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the anti-tachyarrhythmia pacing unit  30  and the pacing pulse generation unit  10  and an anti-tachyarrhythmia pacing is supplied with respect to the heart  38  (step S 119 ).  
      In a case when the anti-tachyarrhythmia pacing is not selected in judgment step S 116 , it is judged next whether or not a cardioversion treatment is selected (step S 120 ). In a case when the cardioversion treatment is selected, the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the cardioversion unit  31  and the shock pulse generation unit  11  and charging of a predetermined amount of energy corresponding to the cardioversion treatment is carried out with respect to the capacitor of the shock pulse generation unit  11 . It is confirmed whether or not the tachyarrhythmia is continuing in the tachyarrhythmia confirmation unit  4  during the period until the charging to the capacitor is completed (step S 121 ). Then, in a case when it was confirmed that the tachyarrhythmia is continuing, a signal is transmitted from the first control unit  62  of the control unit  7  to the selection unit  58  of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  and the stimulation frequency f 2  of the second operation mode is selected by the selection unit  58  (step S 122 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment mode flag of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  (step S 123 ) and subsequently, a cardioversion treatment by the cardioversion unit  31  which was connected by the anti-tachyarrhythmia treatment output change-over unit  33  is supplied to the heart  38  through the shock pulse generation unit  11  (step S 124 ).  
      When the anti-tachyarrhythmia pacing treatment is not selected in judgment step S 116  and when the cardioversion treatment is not selected in judgment step S 120  either, that is, when the defibrillation treatment is selected (step S 125 ), the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the defibrillation unit  32  and the shock pulse generation unit  11  and charging of a predetermined amount of energy corresponding to the defibrillation treatment is carried out with respect to the capacitor of the shock pulse generation unit  11 . It is confirmed whether or not the tachyarrhythmia is continuing in the tachyarrhythmia confirmation unit  4  during the period until the charging to the capacitor is completed (step S 126 ). Then, in a case when it was confirmed that the tachyarrhythmia is continuing, a signal is transmitted to the selection unit  58  of the vagus nerve stimulation and tacharrhythmia prevention unit  55  by the first control unit  62  of the control unit  7  and the stimulation frequency f 2  of the second operation mode is selected (step S 127 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment mode flag of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  (step S 128 ) and subsequently, a defibrillation treatment by the defibrillation unit  32  which was connected by the anti-tachyarrhythmia treatment output change-over unit  33  is supplied to the heart  38  through the shock pulse generation unit  11  (step S 129 ).  
      Next, after the anti-tachyarrhythmia pacing treatment of step S 119 , the cardioversion treatment of step S 124  or the defibrillation treatment of step S 129  is supplied with respect to the heart  38 , it is judged in the tachyarrhythmia termination confirmation unit  5  whether or not the tachyarrhythmia is terminated (step S 130 ). Then, in a case when it is confirmed that the tachyarrhythmia terminated, the tachyarrhythmia preventing treatment change-over timer  20  of the timing unit  8  is reset/started (step S 131 ) and subsequently, the bradycardia treatment change-over timer  25  of the bradycardia treatment unit  9  is reset/started (step S 132 ) and at the same time, the second bradycardia treatment mode of the second bradycardia treatment unit  24  is selected by the bradycardia treatment selection unit  28  (step S 133 ) and the flow returns to judgment step S 111  of  FIG. 12 .  
      In a case when the tachyarrhythmia termination is not confirmed in judgment step S 130 , the flow returns to step S 110  of  FIG. 12  and selection of the tachyarrhythmia terminating treatment is again carried out, but in this selection of the tachyarrhythmia terminating treatment, augmentation of the applied energy, change of the tacharrhythmia terminating treatment method or the like is carried out in a stepwise manner according to a predetermined treatment plan.  
      In a case when continuation of the tachyarrhythmia is not confirmed in judgment step S 121  and judgment step S 126 , that is, in a case when the tachyarrhythmia terminated spontaneously amid the charging to the capacitor of the shock pulse generation unit  11 , releasing of charging stop, internal discharge of the charging energy and connection between the cardioversion unit  31  of the tachyarrhythmia termination unit  12  or the defibrillation unit  32  and the shock pulse generation unit  11  are carried out and at the same time, it is judged whether or not the tachyarrhythmia preventing treatment mode flag of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  is “True” (step S 134 ). Then, in a case when the tachyarrhythmia preventing treatment mode flag is “True”, that is, when the stimulation frequency f 1  of the first operation mode is selected in the tachyarrhythmia preventing treatment of the vagus nerve stimulation and tachyarrhythmia prevention unit  55 , the flow returns to judgment step S 111  of  FIG. 12  and in a case when the tachyarrhythmia preventing treatment mode flag is not “True”, that is, when the stimulation frequency f 2  of the second operation mode is selected in the tachyarrhythmia preventing treatment of the vagus nerve stimulation and tachyarrhythmia prevention unit  55 , the tachyarrhythmia preventing treatment program of the tachyarrhythmia prevention unit  6  is not activated, it is assumed that the possibility that the heart is still in an unstable situation is high so that processes subsequent to step S 131 , which are sequences after the tachyarrhythmia termination are carried out through the tachyarrhythmia termination confirmation unit  5 .  
       FIG. 14  is a block constitutional diagram showing a fifth exemplified embodiment of the heart treatment equipment according to the present invention. The constitution of the fifth exemplified embodiment of the present invention is approximately equal to the constitution of the fourth exemplified embodiment of the present invention shown in  FIG. 11  and the constitutional difference thereof lies in that while the first operation mode stimulation frequency is fixed to f 1  in the fourth exemplified embodiment, the stimulation frequency of the first operation mode in the fifth exemplified embodiment is made to vary in a range of f 1  to f 2  (f 1 &gt;f 2 ) as to the output of the heart contraction detection unit  2 . Also, the stimulation frequency f 3  of the second operation mode is made to be a further lower frequency than f 2 . Constitutions other than the aforesaid constitutional portions are same as those of the block constitutional diagrams of  FIG. 11 , so that the same reference numerals are put thereon and the explanation thereof will be omitted.  
      It should be noted in this example that a constitution for shifting to a mode of small stimulation energy is employed by changing only the stimulation frequency among the nerve stimulation signal parameters in response to the tachyarrhythmia detection, but it is not obsessed with this mode and it is also possible to shift to a mode of small stimulation energy by changing at least one of stimulation frequency, pulse width, a number of pulses, pulse current, pulse voltage, delay time, rest time and repetition times or a plurality of parameters selected from these for the nerve stimulation signal parameter.  
      Hereinafter, it will be explained with respect to the operation of the fifth exemplified embodiment of the present invention in detail according to  FIG. 15  and  FIG. 16 . There are many repetitive portions in this explanation with respect to the explanations of the flow diagrams in  FIG. 13  and  FIG. 14 , but reference numerals of respective processes therein are changed, so that they will be explained repetitively.  
      First, the selection unit  58  of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  selects the stimulation frequency (f 1  to f 2 ) of the first operation mode as an initial value and stimulation of the vagus nerve  41  is carried out by a stimulation waveform having relatively high energy in this frequency range (step S 135 ). Next, “True” is written in the tachyarrhythmia preventing treatment mode flag, which is not shown, of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  (step S 136 ). Then, the tachyarrhythmia preventing treatment change-over timer  20  is stopped/reset in the timing unit  8  (step S 137 ), the first bradycardia treatment mode of the first bradycardia treatment unit  23  is selected by the bradycardia treatment selection unit  28  in the bradycardia treatment unit  9  (step S 138 ) and at the same time, the bradycardia treatment change-over timer  25  is stopped/reset (step S 139 ).  
      Next, it is judged whether or not a bradycardia was detected in the heart contraction detection unit  2  (step S 140 ) and in a case when a bradycardia was detected, a bradycardia treatment is supplied by the pacing pulse generation unit  10  with respect to the heart  38  (step S 141 ). In a case when a bradycardia was not detected in judgment step S 140 , it is judged subsequently whether or not a tachyarrhythmia was detected in the tachyarrhythmia detection unit  3  (step S 142 ) and in a case when a tachyarrhythmia was detected, a signal is transmitted to the tachyarrhythmia termination unit  12  and a tachyarrhythmia terminating treatment corresponding to the detected tachyarrhythmia is selected among the anti-tachyarrhythmia pacing, the cardioversion and the defibrillation (step S 143 ). Thereafter, the flow proceeds to  5 A of  FIG. 16 .  
      In a case when a bradycardia treatment is supplied in step S 141  or a tachyarrhythmia was not detected in judgment step S 142 , it is judged whether or not the tachyarrhythmia preventing treatment change-over timer  20  of the timing unit  8  is timeout (step S 144 ). In a case when the tachyarrhythmia preventing treatment change-over timer  20  is timeout, that is, in a case when the tachyarrhythmia preventing treatment change-over timer  20  made clocking beyond the time stored in change-over time memory unit  21 , a signal is transmitted to the selection unit  58  through the second control unit  63  of the control unit  7  and the stimulation frequency (f 1  to f 2 ) of the first operation mode is selected so as to give a relatively strong stimulation to the vagus nerve  41  (step S 145 ) and at the same time, “True” is written in the tachyarrhythmia preventing treatment mode flag of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  (step S 146 ), and subsequently, the tachyarrhythmia preventing treatment change-over timer  20  is stopped/reset (step S 147 ).  
      Next, in a case when it is judged in judgment step S 144  that the tachyarrhythmia preventing treatment change-over timer  20  is not timeout and after the tachyarrhythmia preventing treatment change-over timer  20  was stopped/reset in step S 147 , it is judged whether or not the bradycardia treatment change-over timer  25  in the bradycardia treatment unit  9  is timeout, that is, whether or not the bradycardia treatment change-over timer  25  made clocking beyond the time stored in the bradycardia treatment change-over time memory unit  26  (step S 148 ).  
      Then, when it is judged that the bradycardia treatment change-over timer  25  is timeout, the flow returns to the selection of the first bradycardia treatment mode in step S 138  and in a case when the bradycardia treatment change-over timer  25  is not timeout, a new bradycardia detection is waited for in judgment step S 140 .  
      Next, it will be explained with respect to the operation of the fifth exemplified embodiment of the present invention after the selection of the tachyarrhythmia terminating treatment was carried out in the step S 143  (after  5 A) according to the flow diagram of  FIG. 16 .  
      First, it is judged whether or not an anti-tachyarrhythmia pacing treatment is selected as an anti-tachyarrhythmia treatment (tachyarrhythmia terminating treatment) in the tachyarrhythmia termination unit  12  (step S 149 ). In a case when an anti-tachyarrhythmia pacing treatment is selected, the first control unit  62  of the control unit  7  is activated so as to select the stimulation frequency f 3  of the second operation mode in the selection unit  58  of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  (step S 150 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment mode flag of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  (step S 151 ) and subsequently, the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the anti-tachyarrhythmia pacing unit  30  and the pacing pulse generation unit  10  and an anti-tachyarrhythmia pacing is supplied with respect to the heart  38  (step S 152 ).  
      In a case when the anti-tachyarrhythmia pacing is not selected in judgment step S 149 , it is judged next whether or not a cardioversion treatment is selected (step S 153 ). In a case when the cardioversion treatment is selected, the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the cardioversion unit  31  and the shock pulse generation unit  11  and charging of a predetermined amount of energy corresponding to the cardioversion treatment is carried out with respect to the capacitor of the shock pulse generation unit  11 . It is confirmed whether or not the tachyarrhythmia is continuing in the tachyarrhythmia confirmation unit  4  during the period until the charging to the capacitor is completed (step S 154 ). Then, in a case when it was confirmed that the tachyarrhythmia is continuing, a signal is transmitted from the first control unit  62  of the control unit  7  to the selection unit  58  of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  and the stimulation frequency f 3  of the second operation mode is selected by the selection unit  58  (step S 155 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment mode flag of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  (step S 156 ) and subsequently, a cardioversion treatment by the cardioversion unit  31  which was connected by the anti-tachyarrhythmia treatment output change-over unit  33  is supplied to the heart  38  through the shock pulse generation unit  11  (step S 157 ).  
      When the anti-tachyarrhythmia pacing treatment is not selected in judgment step S 149  and when the cardioversion treatment is not selected in judgment step S 153  either, that is, when the defibrillation treatment is selected (step S 158 ), the anti-tachyarrhythmia treatment output change-over unit  33  of the tachyarrhythmia termination unit  12  connects the defibrillation unit  32  and the shock pulse generation unit  11  and charging of a predetermined amount of energy corresponding to the defibrillation treatment is carried out with respect to the capacitor of the shock pulse generation unit  11 . It is confirmed whether or not the tachyarrhythmia is continuing in the tachyarrhythmia confirmation unit  4  during the period until the charging to the capacitor is completed (step S 159 ). Then, in a case when it was confirmed that the tachyarrhythmia is continuing, a signal is transmitted to the selection unit  58  of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  by the first control unit  62  of the control unit  7  and the stimulation frequency f 3  of the second operation mode is selected (step S 160 ) and at the same time, “False” is written in the tachyarrhythmia preventing treatment mode flag of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  (step S 161 ) and subsequently, a defibrillation treatment by the defibrillation unit  32  which was connected by the anti-tachyarrhythmia treatment output change-over unit  33  is supplied to the heart  38  through the shock pulse generation unit  11  (step S 162 ).  
      Next, after the anti-tachyarrhythmia pacing treatment of step S 152 , the cardioversion treatment of step S 157  or the defibrillation treatment of step S 162  is supplied with respect to the heart  38 , it is judged in the tachyarrhythmia termination confirmation unit  5  whether or not the tachyarrhythmia is terminated (step S 163 ). Then, in a case when it is confirmed that the tachyarrhythmia terminated, the tachyarrhythmia preventing treatment change-over timer  20  of the timing unit  8  is reset/started (step S 164 ) and subsequently, the bradycardia treatment change-over timer  25  of the bradycardia treatment unit  9  is reset/started (step S 165 ) and at the same time, the second bradycardia treatment mode of the second bradycardia treatment unit  24  is selected by the bradycardia treatment selection unit  28  (step S 166 ) and the flow returns to judgment step S 144  of  FIG. 15 .  
      In a case when the tachyarrhythmia termination is not confirmed in judgment step S 163 , the flow returns to step S 143  of  FIG. 15  and selection of the tachyarrhythmia terminating treatment is again carried out, but in this selection of the tachyarrhythmia terminating treatment, augmentation of the applied energy, change of the tachyarrhythmia terminating treatment method or the like is carried out in a stepwise manner according to a predetermined treatment plan.  
      In a case when continuation of the tachyarrhythmia is not confirmed in judgment step S 154  and judgment step S 159 , that is, in a case when the tachyarrhythmia terminated spontaneously amid the charging to the capacitor of the shock pulse generation unit  11 , releasing of charging stop, internal discharge of the charging energy and connection between the cardioversion unit  31  of the tachyarrhythmia termination unit  12  or the defibrillation unit  32  and the shock pulse generation unit  11  are carried out and at the same time, it is judged whether or not the tachyarrhythmia preventing treatment mode flag of the vagus nerve stimulation and tachyarrhythmia prevention unit  55  is “True” (step S 167 ). Then, in a case when the tachyarrhythmia preventing treatment mode flag is “True”, that is, when the stimulation frequency (f 1  to f 2 ) of the first operation mode is selected in the tachyarrhythmia preventing treatment of the vagus nerve stimulation and tachyarrhythmia prevention unit  55 , the flow returns to judgment step S 144  of  FIG. 15  and in a case when the tachyarrhythmia preventing treatment mode flag is not “True”, that is, when the stimulation frequency f 3  of the second operation mode is selected in the tachyarrhythmia preventing treatment of the vagus nerve stimulation and tachyarrhythmia prevention unit  55 , the tachyarrhythmia preventing treatment program of the tachyarrhythmia prevention unit  6  is not activated, it is assumed that the possibility that the heart is still in an unstable situation is high so that processes subsequent to step S 164 , which are sequences after the tachyarrhythmia termination are carried out through the tachyarrhythmia termination confirmation unit  5 .  
      As described above, the explanations of the constitutions and the operations of the first to the fifth exemplified embodiments according to the present invention were carried out, but it is needless to say that the present invention includes exemplified embodiments other than aforesaid embodiments without being obsessed with those exemplified embodiments and in a scope without departing from the description of the claims.  
      As explained in the above, according to the heart treatment equipment of the present invention, there is provided with a control structure for reducing or stopping the activation current with respect to the vagus nerve or a repression current with respect to the sympathetic nerve after an arrhythmia treatment such as an electroshock to the heart by the cardioversion treatment, the defibrillation treatment or the like and it is constituted such that the tachyarrhythmia preventing treatment is made to cancel or it is made possible to shift to a mode in which the nerve stimulation energy is smaller in response to the confirmation of the tachyarrhythmia detection or the tachyarrhythmia continuation, so that it is possible to solve a problem with deterioration of hemodynamics, recurrence of a fatal arrhythmia, induction of supraventricular arrhythmia such as atrial fibrillation or the like and the like.