WO2015049966A1

WO2015049966A1 - Method for detecting movement of neurostimulation electrode, neurostimulation electrode, and neurostimulation system

Info

Publication number: WO2015049966A1
Application number: PCT/JP2014/074049
Authority: WO
Inventors: 萌後藤
Original assignee: オリンパス株式会社
Priority date: 2013-10-02
Filing date: 2014-09-11
Publication date: 2015-04-09

Abstract

Provided is a method for detecting movement of a neurostimulation electrode which is intravascularly implanted, in which an electrocardiogram waveform is obtained at the neurostimulation electrode and whether the neurostimulation electrode moved is determined on the basis of the electrocardiogram waveform.

Description

Neural stimulation electrode movement detection method, neural stimulation electrode, and neural stimulation system

The present invention relates to a method for detecting movement of a nerve stimulation electrode, more specifically, a method for detecting movement of a nerve stimulation electrode that preferably detects movement after placement of the nerve stimulation electrode, and a nerve stimulation electrode to which the method can be preferably applied, and It relates to a nerve stimulation system. This application claims priority based on Japanese Patent Application No. 2013-207527 filed on October 2, 2013, the contents of which are incorporated herein by reference.

Conventionally, as a method for treating tachycardia, a method of adjusting the heart rate by stimulating the vagus nerve which is one of parasympathetic nerves is known. Patent Document 1 describes a medical device used for such treatment.

The medical device described in Patent Document 1 includes a cylindrical main body or an arched spring that can be expanded in a blood vessel, and the cylindrical main body or the arched spring is expanded in the blood vessel to be placed in the blood vessel.

Special table 2007-535984

Since the nerve stimulation electrode placed in the blood vessel stimulates the nerve through the blood vessel wall, the nerve stimulation electrode is placed in a position where nerve stimulation can be performed as preferably as possible in the blood vessel in consideration of the position of the nerve parallel to the blood vessel.
However, the nerve stimulation electrode may move after placement due to the patient's body movement or the conscious or unconscious removal operation by the patient. When the nerve stimulation electrode is moved, a suitable electrical stimulation cannot be performed due to a change in the positional relationship between the nerve stimulation electrode and the nerve, and appropriate measures such as correction of the indwelling position should be taken immediately. The medical device described in Patent Document 1 has a problem that even if the nerve stimulation electrode moves after placement, the movement cannot be detected.

The present invention has been made in view of the above-described problems, and an object thereof is to provide a movement detection method for a nerve stimulation electrode that can suitably detect movement of the nerve stimulation electrode in a blood vessel. .
Another object of the present invention is to provide a nerve stimulation electrode and a nerve stimulation system capable of suitably detecting movement using the movement detection method.

According to the first aspect of the present invention, in the method for detecting movement of a nerve stimulation electrode placed in a blood vessel, an electrocardiogram waveform is acquired by the nerve stimulation electrode, and the nerve stimulation electrode is based on the electrocardiogram waveform. It is determined whether or not it has moved.

According to a second aspect of the present invention, in the nerve stimulation electrode movement detection method according to the first aspect, the electrocardiogram waveform is compared with a reference waveform prepared in advance, and the nerve stimulation electrode is placed in the heart. You may determine whether it moved to the approaching direction.

According to the third aspect of the present invention, in the nerve stimulation electrode movement detection method according to the second aspect, when the maximum value of the P wave or the R wave in the electrocardiographic waveform is equal to or greater than a predetermined threshold value. It may be determined that the nerve stimulation electrode has moved in a direction approaching the heart.

According to the fourth aspect of the present invention, in the nerve stimulation electrode movement detection method according to the second aspect, the magnitude relationship between the maximum values of the P wave and the R wave in the electrocardiogram waveform is the P wave in the reference waveform. When the magnitude relationship of the maximum value of the R wave is reversed, it may be determined that the nerve stimulation electrode has moved in a direction approaching the heart.

According to a fifth aspect of the present invention, in the nerve stimulation electrode movement detection method according to the first aspect, when the baseline of the electrocardiographic waveform changes to a non-linear shape, the nerve stimulation electrode is a heart. It may be determined that it has moved in a direction approaching.

According to a sixth aspect of the present invention, in the nerve stimulation electrode movement detection method according to the first aspect, when the P wave in the electrocardiographic waveform has a shape having a plurality of peaks, the nerve stimulation electrode is You may determine with having moved to the direction which approaches the heart.

According to the seventh aspect of the present invention, the nerve stimulation electrode placed in the blood vessel has an urging member that can be elastically deformed, and is provided in the indwelling portion locked in the blood vessel. A stimulation unit to which a stimulation signal for stimulating the nerve is applied, and an electrocardiographic waveform acquisition unit having a relative position with respect to the stimulation unit.

According to an eighth aspect of the present invention, in the nerve stimulation electrode according to the seventh aspect, the stimulation unit has three or more electrodes arranged apart from each other in the longitudinal direction of the nerve stimulation electrode. May be.

According to a ninth aspect of the present invention, in the nerve stimulation electrode according to the seventh or eighth aspect, the electrocardiographic waveform acquisition unit has at least two electrodes, and the two electrodes are the nerves. You may arrange | position so that the said stimulation part may not be pinched | interposed in the longitudinal direction of a stimulation electrode.

According to a tenth aspect of the present invention, a nerve stimulation system includes a nerve stimulation electrode according to any one of the seventh aspect to the ninth aspect and an electrocardiogram acquired by the electrocardiographic waveform acquisition unit. And an analysis unit that determines whether or not the stimulation unit has moved based on a shape.

According to the eleventh aspect of the present invention, the nerve stimulation system is acquired by the nerve stimulation electrode according to the eighth aspect, the stimulation generation unit that generates the stimulation signal, and the electrocardiographic waveform acquisition unit. An analysis unit that determines whether or not the stimulation unit has moved based on an electrocardiogram waveform, and a control unit that controls the stimulation generation unit based on the determination of the analysis unit. When the analysis unit determines that the stimulation unit has moved, the control unit changes a combination of electrodes to which the stimulation signal is applied among the electrodes of the stimulation unit.

According to the movement detection method of the nerve stimulation electrode of the present invention, movement of the nerve stimulation electrode in the blood vessel can be suitably detected.
Moreover, according to the nerve stimulation electrode and nerve stimulation system of this invention, the movement of a nerve stimulation electrode can be detected suitably using the movement detection method of this invention.

It is a mimetic diagram showing composition of a nerve stimulation system provided with a nerve stimulation electrode concerning a first embodiment of the present invention. It is a schematic diagram which shows the nerve stimulation electrode which concerns on 1st embodiment of this invention indwelled in the blood vessel connected to the heart. It is an example of the electrocardiogram waveform acquired in the electrocardiogram waveform acquisition part of the nerve stimulation electrode which concerns on 1st embodiment of this invention. It is an example of the electrocardiogram waveform acquired in the electrocardiogram waveform acquisition part of the nerve stimulation electrode which concerns on 1st embodiment of this invention. It is an example of the electrocardiogram waveform acquired in the electrocardiogram waveform acquisition part of the nerve stimulation electrode which concerns on 1st embodiment of this invention. It is a flowchart which shows the flow of the determination in the analysis part of the nerve stimulation electrode which concerns on 1st embodiment of this invention. It is an example of the electrocardiogram waveform acquired in the electrocardiogram waveform acquisition part of the nerve stimulation electrode which concerns on 1st embodiment of this invention. It is an example of the electrocardiogram waveform acquired in the electrocardiogram waveform acquisition part of the nerve stimulation electrode which concerns on 1st embodiment of this invention. It is an example of the electrocardiogram waveform acquired in the electrocardiogram waveform acquisition part of the nerve stimulation electrode which concerns on 1st embodiment of this invention. It is a schematic diagram which shows the state by which the nerve stimulation electrode which concerns on 2nd embodiment of this invention was detained in the blood vessel. It is a schematic diagram which shows the state which the nerve stimulation electrode which concerns on 2nd embodiment of this invention moved within the blood vessel. It is a schematic diagram which shows the state by which the nerve stimulation electrode which concerns on 3rd embodiment of this invention was detained in the blood vessel.

A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic diagram showing a nerve stimulation system 1 including the nerve stimulation electrode of the present embodiment. The nerve stimulation system 1 is a system that treats tachycardia, chronic heart failure, and the like by stimulating the vagus nerve. The nerve stimulation system 1 includes a stimulation generator 10 and a stimulation lead (neural stimulation electrode) 20. The stimulation generator 10 generates a nerve stimulation signal based on a predetermined parameter. A stimulation lead (neural stimulation electrode) 20 is connected to the stimulation generator 10 and placed in the blood vessel.

The stimulus generator 10 includes a stimulus generator 11, an analyzer 12, and a controller 13. The stimulus generator 11 generates a stimulus signal. The analysis unit 12 analyzes the electrocardiogram waveform acquired by the stimulation lead 20. The controller 13 is connected to the stimulus generator 11 and the analyzer 12 and controls the stimulus generator 10 as a whole. The stimulus signal generated by the stimulus generator 11 is sent to the stimulus lead 20. The analysis unit 12 analyzes the electrocardiogram waveform sent from the stimulation lead 20 and repeatedly determines whether the stimulation lead 20 has moved after placement. The flow of determination in the analysis unit 12 will be described later.

FIG. 2 is a schematic diagram showing the stimulation lead 20 placed in the superior vena cava Sv, which is a blood vessel connected to the heart Ht. The stimulation lead 20 includes an indwelling unit 21, a conducting wire unit 26, a stimulation unit 31, and an electrocardiographic waveform acquisition unit 36. The indwelling part 21 is locked in the blood vessel. The conducting wire part 26 connects the indwelling part 21 and the stimulus generator 10. The stimulation part 31 has a pair of

electrodes

32 and 33 to which a stimulation signal is applied. The electrocardiogram waveform acquisition unit 36 includes a pair of

electrodes

37 and 38 different from the stimulation unit 31.

The indwelling part 21 includes an urging member 22 that can be elastically deformed. When the stimulation lead 20 is introduced into the blood vessel, the biasing member 22 is deformed and can be accommodated inside an introducer or the like. The biasing member 22 has a shape that can be expanded into a shape before deformation and locked in the blood vessel when no external force is applied. The material of the urging member 22 can be selected from various shape memory alloys in consideration of biocompatibility. The surface of the urging member 22 may be coated or surface-treated for the purpose of enhancing biocompatibility or suppressing thrombus formation.

The conducting wire portion 26 is formed by covering a conducting wire made of a conductor with an insulating material, and can be selected from various known materials in consideration of biocompatibility and the like.

The pair of

electrodes

32 and 33 of the stimulation unit 31 are attached to the indwelling unit 21 with their conductive surfaces exposed, and a stimulation signal is applied between the pair of

electrodes

32 and 33. The pair of

electrodes

32 and 33 may be provided on the same urging member, or may be provided on different urging members.
The

electrodes

32 and 33 of the stimulation part 31 are connected to the conductor part 26 by wiring (not shown) provided along the biasing member 22.

The basic structure of the pair of

electrodes

37 and 38 of the electrocardiogram waveform acquisition unit 36 and the connection mode of the lead wire unit 26 are generally the same as those of the

electrodes

32 and 33 of the stimulation unit 31, and all four electrodes are connected to other electrodes. Insulation is ensured. Of the pair of

electrodes

37, 38, one electrode 37 is provided on the biasing member 22 located at the distal end portion of the indwelling portion 21. The other electrode 38 is provided on the outer peripheral surface of the conducting wire portion 26 and is located on the proximal side with respect to the indwelling portion 21. That is, the pair of

electrodes

37 and 38 of the electrocardiogram waveform acquisition unit 36 have a positional relationship such that the pair of

electrodes

32 and 33 of the stimulation unit 31 are sandwiched from both sides in the longitudinal direction of the stimulation lead 20.
The electrode 38 is not necessarily present on the conducting wire portion 26 and may be provided on the urging member 22. Even if comprised in this way, the structure which pinches | interposes the electrode pair of the stimulation part 31 is maintained.

In the conductor part 26, the range from the connection part of the indwelling part 21 and the conductor part 26 to the part where the electrode 38 is provided is not easily bent by a core rod or the like so that a substantially straight state is maintained. It is configured. As a result, the electrocardiographic waveform acquisition unit 36 does not substantially move relative to the indwelling unit 21 and the stimulation unit 31 provided in the indwelling unit 21 except for a slight displacement accompanying the deformation of the biasing member 22. It is configured.

When using the nerve stimulation system 1 configured as described above, the stimulation lead 20 is first introduced into the patient's blood vessel using an introducer or the like. Next, the stimulation lead 20 is placed in the blood vessel by expanding the placement portion 21 at the target position and locking it in the blood vessel. After the stimulation lead 20 is placed, the stimulation generator 10 is operated at a predetermined timing, and a stimulation signal is applied from the stimulation unit 31 to the nerve Vn through the blood vessel wall to perform nerve stimulation treatment for the patient.

After the placement of the stimulation lead 20, the electrocardiographic waveform of the patient is acquired by the electrocardiographic waveform acquisition unit 36 continuously or intermittently. The acquired electrocardiogram waveform is transmitted to the analysis unit 12 of the stimulus generator 10. The analysis unit 12 analyzes the electrocardiogram waveform for the presence / absence and type of abnormality related to the size of the electrocardiogram waveform, so that the stimulation lead 20, particularly the indwelling unit 21 and the stimulation unit 31 provided in the indwelling unit 21 after placement. It is determined whether or not has moved.

Since various settings are possible for the information contained in the electrocardiogram waveform used for the determination in the analysis unit 12, some typical examples will be described below.

An example of the first determination criterion is a value of a specific parameter in the electrocardiogram waveform such as the magnitude (particularly the maximum value) of the P wave and / or the R wave.
The upper side of FIG. 3 is an example of a general electrocardiogram waveform acquired with electrodes placed on the body surface, and the lower side is acquired by the electrocardiogram waveform acquisition unit 36 of the stimulation lead 20 placed in the blood vessel. It is an example of an electrocardiogram waveform. The same applies to FIGS. In general, the electrocardiographic waveform increases as shown in the lower part of FIG. 4 when the acquired electrode approaches the heart, and decreases as shown in the lower part of FIG. 5 when moving away from the heart. Therefore, the value of an arbitrary parameter of the electrocardiogram waveform is compared with a parameter of a standard electrocardiogram waveform (hereinafter sometimes referred to as a “reference waveform”), and the difference between the two is equal to or greater than a predetermined value or ratio. It is possible to determine whether or not the stimulating unit 31 has moved by analyzing whether or not there is the analysis unit 12. As the parameter, for example, the maximum value of a certain wave such as the maximum value of the R wave or the maximum value of the P wave, or the amplitude represented by the difference between the maximum value and the minimum value of the P wave or QRS wave is used. However, it is not limited to this.

FIG. 6 is a flowchart illustrating an example of a determination flow in the analysis unit 12 in a case where determination is performed using the maximum value of the R wave, and illustrates one mode of the nerve stimulation electrode movement detection method of the present invention. Yes.
First, in step S10, the analysis part 12 acquires the maximum value of the R wave in the acquired electrocardiogram waveform. Next, in step S20, the analysis unit 12 determines whether or not the maximum value of the acquired R wave exceeds 1.2 times (a predetermined threshold) the maximum value of the R wave in the reference waveform. When the determination in step S20 is Yes, the process proceeds to step S21, and the analysis unit 12 determines that the stimulation unit 31 has moved in a direction approaching the heart and ends the process. If the determination in step S20 is No, the process proceeds to step S30.

Next, in step S30, the analysis unit 12 determines whether or not the acquired maximum value of the R wave is less than 0.8 times the maximum value of the R wave in the reference waveform similar to the standard electrocardiogram waveform. judge. When the determination in step S30 is Yes, the process proceeds to step S31, and the analysis unit 12 determines that the stimulation unit 31 has moved in the direction away from the heart and ends the process. When determination in step S30 is No, a process progresses to step S32, an analysis part determines with the stimulation part 31 not moving, and complete | finishes a process.

In the determination flow described above, step S20 for determining whether or not the stimulating unit 31 has moved in a direction approaching the heart, and step S30 for determining whether or not the stimulating unit 31 has moved in a direction away from the heart, May be reversed. Further, the threshold values in steps S20 and S30 may be changed as appropriate.
Further, the parameter used for the determination may be replaced with another parameter, or the determination may be performed by combining a plurality of parameters.

Also, as the reference waveform that is a criterion for determination, an electrocardiographic waveform acquired by the electrocardiographic waveform acquisition unit immediately after placement may be stored in a storage unit (not shown) of the stimulation generator 10 and used. In addition, an average electrocardiogram waveform at a standard indwelling position in neurostimulation treatment or a parameter value in the electrocardiogram waveform may be stored in advance in the stimulation generator 10 as a reference waveform.

As an example of the next determination criterion, attention is focused on the shape change of the electrocardiographic waveform.
In the electrocardiogram waveform shown on the lower side of FIG. 7, the maximum value of the P wave is larger than the maximum value of the R wave, and the magnitude relationship of the maximum value is reversed from that of the electrocardiogram waveform shown on the upper side. This is a result that the atrial action potential acquired by the electrocardiogram waveform acquisition unit 36 is acquired larger than the action potential of the ventricle because the stimulation unit 31 has approached the atrium considerably. Therefore, immediately after the placement, the maximum value of the R wave is larger than the maximum value of the P wave, but if the shape of the electrocardiographic waveform is changed so that the maximum value of the P wave becomes larger than the maximum value of the R wave after that, It can be determined that the stimulation unit 31 has moved in a direction approaching the heart.
The reversal of the magnitude relationship may be compared with a reference waveform, or the magnitude relation may be monitored at all times to capture the event of reversal.

In the electrocardiogram waveform shown in the lower side of FIG. 8, the base line of the electrocardiogram waveform is not linear like the standard electrocardiogram waveform, and the maximum value of the electrocardiogram waveform fluctuates periodically. All waveforms including the R wave and the R wave fluctuate up and down. This indicates that as a result of the indwelling portion 21 entering the atrium, the locking by the biasing member does not work, and the stimulation portion 31 is moved by the blood flow in the atrium. Therefore, it can be determined that the stimulation unit 31 has moved in a direction approaching the heart due to the base line changing to a non-linear shape.

In the electrocardiographic waveform shown on the lower side of FIG. 9, a plurality of peaks are observed in the P wave. This is presumably because the action potential of the right atrium and the action potential of the left atrium were partially separated and acquired by the electrocardiogram waveform acquisition unit 36 as a result of the stimulation unit 31 approaching the atrium considerably. Therefore, it can be determined that the stimulation unit 31 has moved in the direction approaching the heart due to the appearance of the P wave having such a shape.
When using the determination criteria shown in FIG. 8 and FIG. 9, comparison with the reference waveform is not necessarily required.

In addition, although not shown, it is also possible to determine whether or not the stimulating unit 31 has moved based on the presence or absence of a part or all of the ECG waveform. This is because, as the stimulation unit 31 approaches the heart, the heart potential vector with respect to the electrocardiogram waveform acquisition unit 36 changes, and therefore the presence or absence of movement of the stimulation unit 31 in the direction of approaching the heart mainly. It is suitable for the determination.

Furthermore, the acquired electrocardiogram waveform and the reference waveform can be compared as a whole. In this case, for example, the electrocardiogram waveform for 3 beats acquired by the electrocardiogram waveform acquisition unit 36 is processed as point sequence data, and the correlation coefficient with the reference waveform for 3 beats is calculated. Then, it is possible to determine whether or not the stimulation unit 31 has moved by setting a predetermined threshold value for the correlation coefficient. The determination based on the correlation coefficient is merely an example of an overall comparison, and other known various methods can also be used.
It is also possible to combine a plurality of types of determination criteria described above.

As described above, according to the nerve stimulation electrode movement detection method according to the embodiment of the present invention, it is determined whether or not the nerve stimulation electrode has moved based on the electrocardiogram waveform acquired by the nerve stimulation electrode. . Therefore, it is possible to easily detect the movement of the nerve stimulation electrode without requiring a special parameter for movement detection and without requiring a special configuration for the parameter.

Further, according to the stimulation lead 20 of the present embodiment, the electrocardiographic waveform acquisition unit 36 is provided separately from the stimulation unit 31 that performs nerve stimulation. The electrocardiographic waveform acquisition unit 36 is substantially held in a relative position with respect to the stimulation unit 31 provided in the indwelling unit 21. Therefore, by performing the above-described movement detection method based on the electrocardiogram waveform acquired by the electrocardiogram waveform acquisition unit 36, it is possible to suitably detect the movement of the indwelling unit 21 and the stimulation unit 31 after the indwelling. Furthermore, by providing the electrocardiogram waveform acquisition unit 36 separately from the stimulation unit 31, an electrocardiogram waveform can be acquired independently of nerve stimulation.

In the method for detecting movement of the nerve stimulation electrode of the present invention, when acquisition of an electrocardiogram waveform is performed while shifting the timing from nerve stimulation, a part of the stimulation unit can be used as an electrocardiogram waveform acquisition unit, and the configuration can be simplified. It is preferable because of its advantages. On the other hand, when an electrocardiogram waveform is acquired simultaneously with the nerve stimulation, an electrocardiogram waveform to which the noise of the nerve stimulation is added is acquired and affects the determination accuracy. A specific method of shifting the timing between the neural stimulation and the acquisition of the electrocardiographic waveform can be set as appropriate. For example, since normal nerve stimulation is performed for each unit in which stimulation for a certain period of time and pause for a certain period of time are set, an electrocardiogram waveform may be acquired at the time of pause, or when stimulation is being performed However, an electrocardiographic waveform may be acquired between pulses of the stimulation signal. Any of these methods can reduce noise caused by the stimulus signal.

In the nerve stimulation system 1 according to the present embodiment including the stimulation lead 20 and the control unit 13, when the movement of the stimulation lead 20 is detected, the control unit 13 can perform various processes. Suitable treatment can be performed by the treatment.

The first example of processing by the control unit 13 is notification to a patient, a medical staff, or the like. For example, sound, light, vibration or the like is generated in the stimulus generation device 10, a signal is transmitted to a biological monitor or a remote monitoring device connected to the patient, a predetermined display is performed, or a nurse call is performed, Calling a preset contact or sending an email. As a result, a person who has recognized the notification can take appropriate measures such as correcting the position of the stimulation unit.

A second example of the processing of the control unit 13 is modification of the stimulus signal generated by the stimulus generation unit 11. For example, stop of stimulation (pulse unit or one set unit of stimulation and pause), increase / decrease of stimulation energy, and the like. The stimulation energy can be increased or decreased by adjusting the current value, voltage value, pulse width, frequency, duration, etc. of the stimulation signal. Further, although slightly different from these, an example in which the action on the heart is suppressed by synchronizing the timing of applying the stimulation signal with the refractory period of the heart when the stimulating unit 31 approaches the heart is also this example. include.

The third example of the processing of the control unit 13 is recording of detection contents. For example, the detection content can be stored in a storage unit or the like every time a predetermined interval or movement is detected, and output after removal of the nerve stimulation system, thereby making it possible to grasp the movement of the indwelling stimulation unit. At this time, you may memorize | store together also about the various processes of the control part 13 performed with the movement of a stimulation part.

Then, 2nd embodiment of this invention is described with reference to FIG. 10 and FIG. The difference between the present embodiment and the first embodiment is the configuration of the stimulation unit and the processing of the control unit.
In the following description, components that are the same as those already described are assigned the same reference numerals, and redundant descriptions are omitted.

FIG. 10 is a schematic diagram showing the stimulation lead 50 in the present embodiment. In the stimulation lead 50, the stimulation unit 51 includes three

electrodes

52, 53, and 54. Each of the

electrodes

52, 53, 54 is attached to the biasing member 22 with an interval in the longitudinal direction of the stimulation lead 50.

The nerve stimulation system of this embodiment provided with the stimulation lead 50 has the same effect as the nerve stimulation system 1 described above. In this nerve stimulation system, as shown in FIG. 10, nerve stimulation is performed using the

electrodes

52 and 53, which are the two electrodes on the distal end side, among the electrodes of the stimulation unit 51 in the initial setting. When the analysis unit 12 determines that the indwelling unit 21 has moved in the direction approaching the heart, the control unit 13 selects two electrodes 53 on the proximal end side as shown in FIG. Switch to 54. By this switching, a part of the movement of the indwelling part 21 is absorbed, and the position of the two electrodes to which the stimulation signal is applied in the blood vessel is preferably suppressed from greatly changing from the state before the movement.

According to the stimulation lead 50 of the present embodiment, since the stimulation unit 51 includes the three

electrodes

52, 53, and 54, the combination of the two electrodes to which the stimulation signal is applied among the three electrodes is appropriately changed. Thus, even when the stimulation unit moves, a suitable nerve stimulation treatment can be performed. In the nerve stimulation system according to the present embodiment including the stimulation lead 50, the control unit 13 applies the stimulation signal when the analysis unit 12 detects that the stimulation unit 51 has moved in the direction approaching the heart. Since the electrodes to be switched are moved within a certain range, the nerve stimulation treatment can be preferably continued without adjusting the position of the stimulation lead.

In the present embodiment, the number of electrodes in the stimulation unit is not limited to three, and may be four or more. With this configuration, in addition to the case where the stimulation unit moves in a direction approaching the heart, the treatment is continued without adjusting the position of the stimulation lead even when the stimulation unit moves in a direction away from the heart. be able to.

A third embodiment of the present invention will be described with reference to FIG. The difference between this embodiment and each of the above-described embodiments is the configuration of the electrocardiogram waveform acquisition unit and the processing of the control unit.

FIG. 12 is a schematic diagram showing the stimulation lead 60 in the present embodiment. In the stimulation lead 60, the electrocardiographic waveform acquisition unit 61 includes a third electrode 62 in addition to the pair of

electrodes

37 and 38. The third electrode 62 is attached between the pair of

electrodes

37 and 38 in the longitudinal direction of the stimulation lead 60 and at a position closer to the proximal end than the stimulation unit 31.

In the nerve stimulation system according to the present embodiment including the stimulation lead 60, the control unit 13 switches the electrodes for acquiring the electrocardiogram waveform according to the acquisition timing of the electrocardiogram waveform. That is, an electrocardiographic waveform is acquired between the pair of

electrodes

37 and 38 when nerve stimulation is not performed. When the stimulation signal is applied to the stimulation unit 31, an electrocardiographic waveform is acquired between the two

electrodes

62 and 38 that are further from the heart Ht than the stimulation unit 31. When the position of the stimulating unit 31 is the same, the electrocardiographic waveform acquired between the

electrodes

37 and 38 is different from the electrocardiographic waveform acquired between the

electrodes

62 and 38, and thus the reference used in the analyzing unit 12 A waveform is also prepared for each electrocardiogram waveform and is used properly in the determination.

According to the stimulation lead 60 and the nerve stimulation system including the stimulation lead 60 of the present embodiment, the same effects as those of the nerve stimulation system 1 described above can be obtained. In addition, since the electrocardiogram waveform acquisition unit 61 includes the three

electrodes

37, 38, and 62, the stimulation unit 31 is stimulated by appropriately selecting two electrodes that acquire an electrocardiogram waveform from the three electrodes. Even when a signal is applied, it is possible to reduce noise due to the stimulation signal and obtain a suitable electrocardiogram waveform. As a result, it is possible to monitor the movement of the stimulator in real time without interruption.

In the present embodiment, the number of electrodes of the electrocardiogram waveform acquisition unit is not limited to three, and may be four or more. However, as described above, since the electrocardiographic waveform changes when the selected electrodes are different, it is preferable to prepare a reference waveform for each necessary combination of electrodes from the viewpoint of highly accurate movement detection.
Moreover, if the number of electrodes of the electrocardiogram waveform acquisition unit is set to two and the two electrodes are arranged so as not to sandwich the stimulation unit in the longitudinal direction of the nerve stimulation electrode, noise can be constantly reduced. Is possible.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to these examples. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit of the present invention. The present invention is not limited to the above description, but is limited only by the scope of the appended claims.

Each of the above embodiments can provide a movement detection method for a nerve stimulation electrode that preferably detects movement of the nerve stimulation electrode in a blood vessel, and the movement of the nerve stimulation electrode is preferably performed using the movement detection method for the nerve stimulation electrode. It is possible to provide a nerve stimulation electrode and a nerve stimulation system for detecting the above.

DESCRIPTION OF SYMBOLS 1 Neural stimulation system 11 Stimulation production | generation part 12 Analysis part 13

Control part

20, 50, 60 Stimulation lead (neural stimulation electrode)
21 indwelling part 22 urging

member

31, 51 stimulating

part

32, 33, 52, 53, 54 electrode (electrode of stimulating part)
36, 61 Electrocardiogram

waveform acquisition unit

37, 38, 62 Electrode (electrode of the electrocardiogram waveform acquisition unit)

Claims

A method of detecting movement of a nerve stimulation electrode placed in a blood vessel,
Obtain an electrocardiogram waveform with the nerve stimulation electrode,
A method for detecting movement of a nerve stimulation electrode that determines whether or not the nerve stimulation electrode has moved based on the electrocardiogram waveform.
The method for detecting movement of a nerve stimulation electrode according to claim 1, wherein the electrocardiogram waveform is compared with a reference waveform prepared in advance to determine whether or not the nerve stimulation electrode has moved in a direction approaching the heart.
3. The nerve stimulation electrode according to claim 2, wherein when the maximum value of the P wave or the R wave in the electrocardiogram waveform is equal to or greater than a predetermined threshold, it is determined that the nerve stimulation electrode has moved in a direction approaching the heart. Movement detection method.
When the magnitude relationship between the maximum values of the P wave and the R wave in the electrocardiogram waveform is reversed with the magnitude relationship between the maximum values of the P wave and the R wave in the reference waveform, the nerve stimulation electrode approaches the heart. The method for detecting movement of the nerve stimulation electrode according to claim 2, wherein it is determined that the movement has occurred.
The method for detecting movement of a nerve stimulation electrode according to claim 1, wherein when the baseline of the electrocardiographic waveform changes to a non-linear shape, it is determined that the nerve stimulation electrode has moved in a direction approaching the heart.
The method for detecting movement of a nerve stimulation electrode according to claim 1, wherein when the P wave in the electrocardiogram waveform has a shape having a plurality of peaks, it is determined that the nerve stimulation electrode has moved in a direction approaching the heart.
A nerve stimulation electrode placed in a blood vessel,
An indwelling portion having an elastically deformable biasing member and locked in the blood vessel;
A stimulation unit provided in the indwelling unit to which a stimulation signal for stimulating nerves is applied;
An electrocardiographic waveform acquisition unit in which a relative position is held with respect to the stimulation unit;
A nerve stimulation electrode comprising:
The nerve stimulation electrode according to claim 7, wherein the stimulation unit includes three or more electrodes arranged apart from each other in the longitudinal direction of the nerve stimulation electrode.
The electrocardiogram waveform acquisition unit has at least two electrodes, and the two electrodes are arranged so as not to sandwich the stimulation unit in the longitudinal direction of the nerve stimulation electrode. The nerve stimulation electrode as described.
The nerve stimulation electrode according to any one of claims 7 to 9,
An analysis unit for determining whether the stimulation unit has moved based on the electrocardiogram waveform acquired by the electrocardiogram waveform acquisition unit;
A neural stimulation system comprising:
The nerve stimulation electrode according to claim 8,
A stimulus generator for generating the stimulus signal;
An analysis unit for determining whether the stimulation unit has moved based on the electrocardiogram waveform acquired by the electrocardiogram waveform acquisition unit;
A control unit that controls the stimulus generation unit based on the determination of the analysis unit;
With
The nerve stimulation system in which the control unit changes a combination of electrodes to which the stimulation signal is applied among the electrodes of the stimulation unit when the analysis unit determines that the stimulation unit has moved.