JP6626256B2 - Method for detecting movement of nerve stimulation electrode and nerve stimulation system - Google Patents

Description

  The present invention relates to a method for detecting movement of a nerve stimulation electrode, and more particularly, to a method for detecting movement of a nerve stimulation electrode for suitably detecting movement after placement of the nerve stimulation electrode, and a nerve stimulation system to which the method can be suitably applied. .

Conventionally, as one method of tachycardia treatment, it has been known to stimulate a vagus nerve, which is one of parasympathetic nerves, to regulate a heart rate. Patent Literature 1 describes a nerve stimulation electrode which is a medical device used for such treatment.
The nerve stimulation electrode includes a lead anchor and an electrode (stimulation electrode) at the tip of the lead body. The lead body is formed by providing a plurality of conductors including wires and coils with an insulator such as a biocompatible insulating polymer such as silicone or polyurethane.
The lead anchor has a plurality of struts and is configured to expand from a folded configuration to an expanded configuration. When in the expanded configuration, the lead anchor presses the electrode against the vessel wall of the blood vessel.

JP 2010-516405 A

The nerve stimulation electrode to be placed in the blood vessel is placed at a position where nerve stimulation can be performed as suitably as possible in the blood vessel in consideration of the position of the nerve running in parallel with the blood vessel in order to stimulate the nerve through the blood vessel by the electrode. .
The nerve stimulation electrode may move after being placed due to body movement of the patient, conscious or unconscious removal operation of the patient, and the like. If the nerve stimulation electrode moves, a suitable electrical stimulation cannot be performed due to a change in the positional relationship with the nerve, so that appropriate measures such as correction of the indwelling position should be taken immediately. However, the nerve stimulation electrode described in Patent Literature 1 has a problem that the movement cannot be detected even if the electrode moves after being placed.

  The present invention has been made in view of such problems, and a method for detecting the movement of a nerve stimulation electrode that can suitably detect movement of a nerve stimulation electrode placed in a blood vessel along a blood vessel, It is another object of the present invention to provide a nerve stimulation system to which the method can be suitably applied.

In order to solve the above problems, the present invention proposes the following means.
The method for detecting movement of a nerve stimulation electrode of the present invention is a method for detecting movement of a nerve stimulation electrode placed in a blood vessel of a living body, wherein the nerve stimulation electrode is positioned in the blood vessel, and the blood detected at a reference time is detected. The measured value of the biological signal is stored as a reference measured value of the biological signal, and while the nerve stimulation electrode is placed in the blood vessel, the measured value of the detected biological signal is compared with the stored measured value of the reference biological signal. And determining whether the nerve stimulation electrode has moved along the blood vessel.
A nerve stimulation system according to the present invention includes an elastically deformable urging member, an indwelling unit to be locked in a blood vessel of a living body, and a pair provided to the urging member, to which a stimulation signal for stimulating a nerve is applied. A stimulation unit having a stimulation electrode, and a nerve stimulation electrode including a detection unit that detects a biological signal about blood when placed in the blood vessel, and the detection unit detects at a reference time when an instruction is input. A storage unit that stores a reference biological signal measurement value that is a measurement value of the biological signal, and compares the measurement value of the biological signal and the reference biological signal measurement value that are detected by the detection unit. And a determining unit that determines whether or not the blood vessel has moved along the blood vessel.

Another method for detecting the movement of a nerve stimulation electrode of the present invention is a method for detecting movement of a nerve stimulation electrode to be placed in a blood vessel of a living body, wherein the nerve stimulation electrode is positioned in the blood vessel, and the nerve stimulation electrode is The measured value of the amount of deformation detected at a reference time for the elastically deformable urging member is stored as a reference deformation amount measured value, and while the nerve stimulation electrode is placed in the blood vessel, the deformation of the urging member to be detected is detected. The measured value of the amount and the stored measured value of the reference deformation amount are compared to determine whether the nerve stimulation electrode has moved along the blood vessel.
Another nerve stimulation system of the present invention has an urging member that can be elastically deformed, and is provided on the indwelling unit that is locked in a blood vessel of a living body, and the urging member is provided with a stimulation signal for stimulating nerves. A stimulating unit having a pair of stimulating electrodes, and a nerve stimulating electrode including a detecting unit that detects the amount of deformation of the urging member when placed in the blood vessel, and the detection at a reference time when an instruction is input. A storage unit that stores a reference deformation amount measurement value that is a measurement value of the deformation amount detected by the unit, and compares the measurement value of the deformation amount and the reference deformation amount measurement value that the detection unit detects, A determination unit that determines whether the indwelling unit has moved along the blood vessel.

The detection unit may include a pair of or more measurement electrodes for detecting blood impedance or blood conductivity as the biological signal .
The detection unit may include a flow rate sensor for detecting a blood flow rate as the biological signal .
The detection unit may include a strain sensor provided on the urging member .

  ADVANTAGE OF THE INVENTION According to the movement detection method and the nerve stimulation system of the nerve stimulation electrode of the present invention, the movement of the nerve stimulation electrode placed in the blood vessel along the blood vessel can be suitably detected.

It is a block diagram of a nerve stimulation system of a first embodiment of the present invention. It is a schematic diagram which shows the stimulation lead of the same nerve stimulation system indwelled in the blood vessel connected to the heart. It is a schematic diagram showing a stimulation lead of a nerve stimulation system in a modification of the first embodiment of the present invention. It is a schematic diagram showing a stimulation lead of a nerve stimulation system in a modification of the first embodiment of the present invention. It is a schematic diagram showing a stimulation lead of a nerve stimulation system in a modification of the first embodiment of the present invention. It is a schematic diagram showing the stimulation lead of the nerve stimulation system of the second embodiment of the present invention. It is a mimetic diagram showing the stimulation lead of the nerve stimulation system in the modification of a 2nd embodiment of the present invention. It is a schematic diagram showing the stimulation lead of the nerve stimulation system of the third embodiment of the present invention. It is a schematic diagram showing the stimulation lead of the nerve stimulation system of the fourth embodiment of the present invention. It is a schematic diagram showing a stimulation lead of a nerve stimulation system according to a fifth embodiment of the present invention.

(1st Embodiment)
Hereinafter, a first embodiment of a nerve stimulation system according to the present invention will be described with reference to FIGS. 1 to 5.
As shown in FIGS. 1 and 2, the nerve stimulation system 1 includes a stimulation lead (neural stimulation electrode) 10 and a stimulation generator 40 connected to the stimulation lead 10.

The stimulation lead 10 includes an elastically deformable urging member 21, a detention unit 20 locked in the superior vena cava (blood vessel) Sv of the patient (living body) P, and a stimulus provided on the urging member 21. It has a unit 25 and a biological signal acquisition unit (detection unit) 30 that detects bioimpedance (biological signal) when placed in the superior vena cava Sv.
In the present embodiment, a plurality of biasing members 21 are provided at intervals around a reference line C parallel to the longitudinal direction of the stimulation lead 10. Although not shown in detail, the urging member 21 has a support wire and a coating covering the outer peripheral surface of the support wire. The support wire can be selected from various shape memory alloys and the like in consideration of biocompatibility. The coating is formed of, for example, a resin such as polyurethane, and is used for the purpose of enhancing biocompatibility and suppressing thrombus formation. As described above, the urging member 21 is formed of an elastically deformable material.

Each of the urging members 21 is arranged such that the distal end portion and the proximal end portion in the longitudinal direction are disposed on the reference line C, and the central portion in the longitudinal direction is separated from the reference line C. Each urging member 21 has a distal end connected to each other, and a proximal end connected to each other.
Each of the urging members 21 is elastically deformable so as to approach the reference line C when inserted into an introducer or the like. When inserted beyond the introducer, it can be deformed away from the reference line C by its own elastic force.

The stimulating unit 25 has a pair of stimulating electrodes 26 and 27 to which a stimulating signal for stimulating the vagus nerve (nerve) Vn is applied. In the present embodiment, each of the stimulation electrodes 26 and 27 is mounted on the opposite side to the reference line C at the center of one biasing member 21 so that the conductive surface is exposed to the outside. Each of the stimulating electrodes 26 and 27 is connected to a later-described conducting wire portion 35 by a wiring (not shown) provided along the urging member 21.
In the present embodiment, the pair of stimulating electrodes 26 and 27 are attached to one urging member 21, but the pair of stimulating electrodes 26 and 27 may be attached to different urging members 21 respectively.

The biological signal acquisition unit 30 has a pair of measurement electrodes 31 and 32 for detecting a biological impedance. In this case, since the detection of the bioelectrical impedance is performed by a known two-terminal method, the larger the electrode area of the measurement electrodes 31 and 32 is, the better.
The measurement electrode 31 is attached to the tip of the biasing member 21, and the measurement electrode 32 is attached to the tip of the conductor 35.
The basic structure of the pair of measurement electrodes 31 and 32 and the manner of connection with the biasing member 21 and the conductor 35 are substantially the same as those of the stimulation electrodes 26 and 27, and all four electrodes have insulation properties with the other electrodes. Is secured. The measurement electrodes 31 and 32 are arranged so as to sandwich the stimulation electrodes 26 and 27 in a direction along the reference line C.
The measurement electrode 32 does not necessarily need to be attached to the conductor 35, and may be attached to the urging member 21. The measurement electrodes 31 and 32 may be arranged so as not to sandwich the stimulation electrodes 26 and 27 in the direction along the reference line C.

The stimulating lead 10 is joined to a distal end of a conducting wire portion 35 extending in the longitudinal direction, and is connected to the stimulus generator 40 by the conducting wire portion 35. The conductor portion 35 is formed by covering a conductor made of a conductor with an insulating material, and can be selected from various known materials in consideration of biocompatibility and the like.
Note that a core rod (not shown) is arranged in the conductive wire portion 35 within a range from a connection portion with the detention portion 20 to a portion where the measurement electrode 32 is provided. As a result, the portion of the conductive wire portion 35 in this range is not easily bent, and a substantially linear state is maintained. As a result, the biological signal acquisition unit 30 does not substantially move relative to the indwelling unit 20 and the stimulating unit 25 provided in the indwelling unit 20 except for a slight displacement accompanying the deformation of the urging member 21.

  As shown in FIG. 1, the stimulus generator 40 includes a casing 41, a switch 42 attached to an outer surface of the casing 41, a stimulus generator 43 built in the casing 41 to generate a stimulus signal, and measurement electrodes 31 and 32. A storage unit 44 for storing one of the measured values of the bioimpedance detected in step 4 as a reference bioimpedance measurement value (reference biosignal measurement value), and determines whether the indwelling unit 20 has moved along the superior vena cava Sv. And a control unit 46 that is connected to the switch 42, the stimulus generation unit 43, the storage unit 44, and the determination unit 45 and controls the entire stimulus generation device 40.

As the switch 42, a switch having a known configuration that is normally in an OFF state in which the contacts are cut off and is in an ON state in which the contacts are conductive when a button is pressed is appropriately selected and used. be able to. The switch 42 is used by a user such as an operator to input an instruction by switching from an OFF state to an ON state.
The stimulus generation unit 43 can generate a stimulus signal that is an electrical stimulus using a constant current method or a constant voltage method. The stimulus signal generated by the stimulus generation unit 43 is sent to the stimulus unit 25 of the stimulus lead 10.

The storage unit 44 has a memory (not shown), and stores the reference bioimpedance measurement value in this memory.
The determination unit 45 has an arithmetic element and a memory (not shown). The memory stores a control program for the arithmetic element, a threshold value that is a positive number for bioimpedance, and the like. The operation element of the determination unit 45 compares the measured value of the bioelectrical impedance detected by the measurement electrodes 31 and 32 with the measured value of the standard bioelectrical impedance stored in the storage unit 44, and determines that the indwelling unit 20 has the superior vena cava Sv. It is determined whether it has moved along. The result determined by the determination unit 45 is displayed on a display unit 47 such as a liquid crystal panel attached to the outer surface of the casing 41.

More specifically, when the measured value of the bioimpedance is equal to or greater than the reference bioimpedance measured value plus the threshold value, the determination unit 45 sends a signal to the display unit 47 via the control unit 46. This causes the display unit 47 to display a warning indicating that the measured value of the bioelectrical impedance is too large. On the other hand, when the measured value of the bioimpedance is equal to or smaller than the value obtained by subtracting the threshold value from the measured value of the reference bioimpedance, the determination unit 45 sends a signal to the display unit 47 and displays a warning indicating that the measured value of the bioimpedance is too small. Let it. The determination unit 45 causes the display unit 47 to display a warning and, at the same time, stops the stimulus signal generated by the stimulus generation unit 43.
This determination by the determination unit 45 is repeatedly performed at intervals of, for example, several seconds.

  Next, the stimulation lead 10 of the nerve stimulation system 1 configured as described above is placed in the superior vena cava Sv shown in FIG. 2, and after the placement, the movement of the stimulation lead 10 with respect to the superior vena cava Sv is detected. A method of detecting the movement of the stimulation lead 10 will be described. In general, the superior vena cava Sv increases in inner diameter as it approaches the right atrium Ht1 of the heart Ht, and the amount of blood stored in the vicinity increases as it approaches the right atrium Ht1. The right atrium Ht1 contains more blood in the vicinity than the superior vena cava Sv. The outer diameter of the indwelling unit 20 in the natural state is set to be larger than the inner diameter of the superior vena cava Sv.

First, the user incises the vicinity of the neck of the patient P (not shown in detail) to form an opening (not shown). A known introducer or the like is attached to this opening, and the stimulation lead 10 of the nerve stimulation system 1 is introduced from the indwelling unit 20 side. At this time, the position of the stimulating lead 10 is confirmed while confirming the position of the support wire of the indwelling section 20 and the position of the conducting wire of the conducting section 35 under X-rays. Since each of the urging members 21 of the retaining section 20 is formed of an elastically deformable material, the retaining section 20 can be inserted into the introducer.
When the indwelling unit 20 is introduced into the superior vena cava Sv, since the outer diameter of the indwelling unit 20 is set as described above, each of the urging members 21 and the stimulation electrodes 26 of the inferior vena cava 20 27 contact.

The stimulus generator 43 of the stimulus generator 40 generates a stimulus signal. The generated stimulation signal is applied between the stimulation electrodes 26 and 27. The stimulation lead 10 is rotated around the reference line C with respect to the superior vena cava Sv by manipulating the proximal end of the conducting wire portion 35 protruding outside the patient P from the introducer, or along the superior vena cava Sv. While pushing and pulling, the heart rate is measured by an electrocardiograph or the like attached to the patient P. The stimulation electrodes 26 and 27 are arranged so as to approach and face the vagus nerve Vn, and when the stimulation signal transmitted from the stimulation electrodes 26 and 27 to the vagus nerve Vn increases, the heart rate of the patient P decreases most. .
The user places the indwelling unit 20 in the superior vena cava Sv such that the heart rate is the lowest, that is, the stimulation electrodes 26 and 27 face the vagus nerve Vn and the stimulation electrodes 26 and 27 approach the vagus nerve Vn. Is positioned around the reference line C and the position along the superior vena cava Sv.

When the positioning of the indwelling section 20 with respect to the superior vena cava Sv is completed, the user presses the switch 42. The measurement electrodes 31 and 32 detect the bioimpedance, and the measured value of the bioimpedance at the reference time when the user presses the switch 42 and inputs the instruction is stored in the storage unit 44 as the reference bioimpedance measured value.
The stimulation lead 10 is placed in the superior vena cava Sv in a state where the indwelling section 20 is in contact with and locked to the superior vena cava Sv. In this example, the stimulus generator 40 is placed outside the body of the patient P during the placement.

After the stimulation lead 10 is placed, a stimulation signal is applied by the stimulation electrodes 26 and 27 at a predetermined timing to stimulate the vagus nerve Vn through the wall of the superior vena cava Sv, thereby performing a nerve stimulation treatment for the patient P.
In parallel with this, the measurement electrodes 31 and 32 detect the bioimpedance at every interval time. The determination unit 45 compares the measured value of the bioimpedance with the reference bioimpedance measured value stored in the storage unit 44 to determine whether the indwelling unit 20 has moved along the superior vena cava Sv.

When the indwelling unit 20 moves toward the right atrium Ht1 along the superior vena cava Sv, the amount of blood stored near the indwelling unit 20 increases. Since the impedance of a liquid such as blood is smaller than that of a solid such as a muscle, the measured value of the bioimpedance becomes smaller when the indwelling unit 20 moves to the right atrium Ht1. When the measured value of the bioimpedance is equal to or less than the value obtained by subtracting the threshold value stored in its own memory from the measured value of the bioimpedance, the measured value of the bioimpedance is too small on the display unit 47, That is, a warning indicating that the placement section 20 has moved to the right atrium Ht1 is displayed.
On the other hand, when the indwelling unit 20 moves to the opposite side of the right atrium Ht1 along the superior vena cava Sv, that is, to the head side, the amount of blood accommodated in the vicinity of the indwelling unit 20 decreases, so that the bioimpedance measurement The value increases. When the measured value of the bioimpedance is equal to or greater than the value obtained by adding the threshold value stored in its own memory from the measured value of the bioimpedance, the measured value of the bioimpedance is too large on the display unit 47, That is, a warning indicating that the detention unit 20 has moved to the head side is displayed.

  The determination unit 45 causes the display unit 47 to display a warning and, at the same time, stops the stimulus signal generated by the stimulus generation unit 43.

  The user who has watched the warning displayed on the display unit 47 operates the base end of the conductor 35 according to the content of the warning, and adjusts the position of the indwelling unit 20 along the superior vena cava Sv. By operating the control unit 46, the generation of the stimulus signal by the stimulus generation unit 43 is restarted.

As described above, according to the method for detecting the movement of the stimulation lead 10 and the nerve stimulation system 1 of the present embodiment, the user sets the position along the superior vena cava Sv of the indwelling unit 20 when the stimulation lead 10 is introduced. Position. At the reference time when the user inputs an instruction with the switch 42, the measured value of the bioimpedance is stored in the storage unit 44 as the measured value of the bioimpedance.
The determination unit 45 compares the measured value of the bioelectrical impedance by the measurement electrodes 31 and 32 with the reference bioelectrical impedance measured value stored in the storage unit 44, and determines whether the stimulation lead 10 has moved along the superior vena cava Sv. Therefore, the movement of the stimulation lead 10 along the superior vena cava Sv can be suitably detected.

In the present embodiment, a measurement electrode 32 attached to the conductor 35 may be provided as in the nerve stimulation system 1A shown in FIG. When the stimulation lead 10 is indwelled, the measurement electrode 32 is arranged in a blood vessel in a portion of the neck P1 of the patient P just below the skin.
With such a configuration, it is possible to measure a change in bioimpedance due to a change in the distance between the measurement electrode 32 and the inner wall of the blood vessel due to body movement or the like, with the measurement electrode 32 serving as a reference.

As in the nerve stimulation system 1B shown in FIG. 4, the biological signal acquisition unit 50 may be configured to have a pair of measurement electrodes 51 and 52 in addition to the pair of measurement electrodes 31 and 32. In this example, the measurement electrodes 51 and 52 are attached to one urging member 21. The measurement electrodes 51 and 52 are arranged so as to be sandwiched between the measurement electrodes 31 and 32 in the direction along the reference line C. In this case, the bioimpedance is detected by a known four-terminal method. For example, a current is applied by the measurement electrodes 31 and 32, and a potential difference is measured by the measurement electrodes 51 and 52. The bioelectrical impedance is detected from the measured potential difference.
By configuring the nerve stimulation system 1B in this manner, the number of measurement electrodes included in the biological signal acquisition unit 50 becomes four, but the biological impedance can be measured more accurately.

In the nerve stimulation system 1B, a change in blood conductivity due to a change in blood composition may be measured using measurement electrodes that are close to each other.
For example, the measurement by the two-terminal method by the combination of the measurement electrodes 31 and 51 of the nerve stimulation system 1C shown in FIG. 5 or the measurement by the two-terminal method by the combination of the measurement electrodes 32 and 52 may be used. Then, the influence of a change in blood composition on the bioelectrical impedance measured using the four-terminal method is corrected. The distance between the measurement electrodes for measuring the change in blood conductivity is desirably as short as possible to avoid the influence of impedance other than blood. Specifically, it is desirable that the distance between the measurement electrode 31 and the measurement electrode 51 and the distance between the measurement electrode 32 and the measurement electrode 52 be as short as possible.
The nerve stimulation system 1C may not include the measurement electrodes 51 and 52, and may be configured so that the stimulation electrodes 26 and 27 also serve as the measurement electrodes. With this configuration, the nerve stimulation system 1C can be downsized.

In the nerve stimulation system 1, a new measurement electrode is provided near the measurement electrode 32 in the conducting wire portion 35, and the biological impedance is measured by the two-terminal method using the newly provided measurement electrode and the measurement electrode 32. Changes in blood conductivity due to changes in composition may be measured. Then, the bioelectrical impedance measured by the measurement electrodes 31 and 32 is corrected.
The amount of blood around the indwelling section 20 may be measured using a known dual frequency method, and the bioelectrical impedance measured by the measurement electrodes 31 and 32 may be corrected based on the measurement result.

(2nd Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. 6 and 7, but the same parts as those in the above embodiment will be denoted by the same reference numerals, and description thereof will be omitted. Only different points will be described. explain.
As shown in FIG. 6, the present nerve stimulation system 2 is a pressure sensor for detecting an intravascular pressure (blood pressure, biological signal) instead of the biological signal acquisition unit 30 of the nerve stimulation system 1 of the first embodiment. 56, a biological signal acquisition unit 55 having a pressure conversion unit 57 built in the casing 41 and a connection tube 58 connecting the pressure sensor 56 and the pressure conversion unit 57.

The pressure sensor 56 is formed of a known balloon, and is attached to the base end of each of the urging members 21 of the indwelling section 20. The pressure converter 57 can supply a fluid such as a physiological saline to the pressure sensor 56 via the connection tube 58.
By the pressure acting on the pressure conversion unit 57 via the pressure sensor 56 and the connection tube 58, the pressure conversion unit 57 can measure the intravascular pressure at the portion where the pressure sensor 56 is attached.

A method of detecting the movement of the stimulation lead 60 of the present embodiment for detecting the movement of the stimulation lead 60 of the nerve stimulation system 2 thus configured and placed in the superior vena cava Sv will be described.
Generally, as the superior vena cava Sv approaches the right atrium Ht1 of the heart Ht, the venous pressure decreases and the pressure fluctuation of the venous pressure increases.

When the positioning of the indwelling section 20 with respect to the superior vena cava Sv is completed, the user presses the switch 42. The biological signal acquisition unit 55 detects the venous pressure, and the measured value of the venous pressure at the reference time when the user presses the switch 42 and inputs the instruction is stored in the storage unit 44 as the reference vein pressure measured value.
When the stimulation lead 60 is placed in the superior vena cava Sv, the biological signal acquisition unit 55 detects the venous pressure at every interval time. The determination unit 45 compares the measured value of the venous pressure with the reference vein pressure measured value stored in the storage unit 44 to determine whether the indwelling unit 20 has moved along the superior vena cava Sv.
More specifically, when the measured value of the venous pressure is equal to or less than the value obtained by subtracting the threshold value stored in its own memory from the measured value of the venous pressure, the determination unit 45 displays the measured value of the venous pressure on the display unit 47. Is too low, that is, a warning indicating that the placement section 20 has moved to the right atrium Ht1 side is displayed. On the other hand, when the measured value of the venous pressure is equal to or greater than the value obtained by adding the threshold value stored in the memory of the own device to the measured value of the venous pressure, the determination unit 45 displays the measured value of the venous pressure on the display unit 47. A warning is displayed that indicates that the detention unit 20 has moved to the head side.
The determination unit 45 causes the display unit 47 to display a warning and, at the same time, stops the stimulus signal generated by the stimulus generation unit 43.

The venous pressure is fluctuated by respiration. However, by aligning the timing of pressure measurement at the end of expiration of breathing, canceling fluctuations in venous pressure due to breathing, and measuring fluctuations in venous pressure due to movement of the indwelling section 20, more accurate detection of movement of the indwelling section 20 Can be.
Variations in venous pressure also occur depending on the body position. In order to cancel the fluctuation of the venous pressure due to the posture change, the nerve stimulation system 2 may include an acceleration sensor. By detecting that the position of the patient P is the same by the acceleration sensor and comparing the change in the venous pressure in the same position, the change in the venous pressure due to the movement of the indwelling unit 20 can be more accurately detected.

As described above, according to the movement detection method of the stimulation lead 60 and the nerve stimulation system 2 of the present embodiment, the movement of the stimulation lead 60 along the superior vena cava Sv can be suitably detected.
In the present embodiment, the movement of the indwelling unit 20 is detected by the measured value of the venous pressure, but may be detected by the fluctuation of the venous pressure.

In the present embodiment, as in the nerve stimulation system 2A shown in FIG. 7, the biological signal acquisition unit 55 may be configured to include a second pressure sensor 59 different from the pressure sensor 56. The second pressure sensor 59 is connected to the pressure conversion unit 57 via a connection tube (not shown).
The second pressure sensor 59 is disposed in a blood vessel in a portion immediately below the skin of the neck P1 of the patient P when the stimulation lead 60 is placed. The biological signal acquisition unit 55 can measure the venous pressure with the pressure sensor 56 and the second pressure sensor 59, respectively.

  In the nerve stimulation system 2A configured as described above, even if the stimulation lead 60 moves along the superior vena cava Sv, the second pressure sensor 59 is disposed in the blood vessel of the patient P just below the skin of the neck P1. State is maintained. The venous pressure in the blood vessel just below the skin of the neck P1 is hardly affected by the movement along the blood vessel. On the other hand, when the patient P is surprised or the like, the venous pressure of the patient P rises almost equally as a whole, although temporarily. By using the difference between the measured value of the venous pressure by the pressure sensor 56 and the measured value of the venous pressure by the second pressure sensor 59 instead of the measured value of the venous pressure by the pressure sensor 56, the venous pressure is temporarily increased. Influence can be suppressed, and the movement of the stimulation lead 60 along the superior vena cava Sv can be detected more appropriately.

In the nerve stimulation system 2 of the present embodiment, the pressure sensor 56 may be configured by using a piezoelectric element instead of being formed by a balloon.
The nerve stimulation system 2 may detect the body position by the acceleration sensor, and may store, for example, a difference between the first pressure sensor and the second pressure sensor in the standing position and the lying position. By canceling the pressure change due to the body position based on the stored difference, the pressure change due to the movement of the detention unit 20 can be accurately detected.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. 8, but the same portions as those in the above embodiment will be denoted by the same reference numerals, and description thereof will be omitted. Only different points will be described.
As shown in FIG. 8, the nerve stimulation system 3 includes a flow rate sensor 66 for detecting a blood flow rate (biological signal) instead of the biological signal acquisition unit 30 of the nerve stimulation system 1 of the first embodiment. A biological signal acquisition unit 65 is provided. As the flow rate sensor 66, a known configuration capable of detecting the blood flow rate can be appropriately selected and used.
The flow rate sensor 66 is attached to the base end of each of the urging members 21 of the detention unit 20.

A method for detecting the movement of the stimulation lead 70 of the present embodiment for detecting the movement of the stimulation lead 70 of the nerve stimulation system 3 thus configured and placed in the superior vena cava Sv will be described.
In general, in the superior vena cava Sv, the blood flow velocity decreases as the heart Ht approaches the right atrium Ht1.

When the positioning of the indwelling section 20 with respect to the superior vena cava Sv is completed, the user presses the switch 42. The biological signal acquisition unit 65 detects the blood flow velocity, and the measured value of the blood flow velocity at the reference time when the user presses the switch 42 and inputs the instruction is stored in the storage unit 44 as the reference blood flow velocity measurement value.
When the stimulation lead 70 is placed in the superior vena cava Sv, the biological signal acquisition unit 65 detects the flow rate of blood at every interval time. The determination unit 45 compares the measured value of the blood flow rate with the reference blood flow rate measurement value stored in the storage unit 44 to determine whether the indwelling unit 20 has moved along the superior vena cava Sv. I do.

More specifically, when the measured value of the blood flow rate is equal to or less than the value obtained by subtracting the threshold value stored in its own memory from the reference blood flow rate measured value, the determination unit 45 displays the blood flow rate on the display unit 47. Is displayed, a warning indicating that the indwelling unit 20 has moved to the right atrium Ht1 side is displayed. On the other hand, when the measured value of the blood flow velocity is equal to or more than the value obtained by adding the threshold value stored in its own memory from the reference blood flow velocity measured value, the determination unit 45 displays the measured blood flow velocity on the display unit 47. A warning indicating that the value is too fast, that is, that the detention unit 20 has moved to the head side is displayed.
The determination unit 45 causes the display unit 47 to display a warning and, at the same time, stops the stimulus signal generated by the stimulus generation unit 43.

In addition, the flow velocity of the blood in a vein fluctuates by respiration. However, by aligning the timing of pressure measurement at the end of expiration of respiration, canceling fluctuations in blood flow velocity due to respiration, and measuring fluctuations in blood flow velocity due to movement of the indwelling section 20, the movement of the indwelling section 20 is more accurate. Can be detected.
In addition, the blood flow velocity in the vein varies depending on the body position. The nerve stimulation system 3 may include an acceleration sensor in order to cancel the fluctuation of the blood flow velocity due to the posture change. By detecting that the position of the patient P is the same by the acceleration sensor and comparing the change in the blood flow velocity in the same position, the change in the blood flow velocity due to the movement of the indwelling unit 20 can be more accurately detected. it can.

As described above, according to the movement detecting method of the stimulation lead 70 and the nerve stimulation system 3 of the present embodiment, the movement of the stimulation lead 70 along the superior vena cava Sv can be suitably detected.
In the present embodiment, when the stimulation lead 70 is indwelled, the biological signal acquisition unit 65 may include a second flow rate sensor disposed in a blood vessel just below the skin of the neck P1 of the patient P. The blood flow velocity in the blood vessel in the portion of the neck P1 just below the skin is hardly affected by the movement along the blood vessel. On the other hand, when the patient P is surprised or the like, the blood flow rate of the patient P rises almost temporarily overall as a whole. By using the difference between the measured value of the blood flow rate by the flow rate sensor 66 and the measured value of the blood flow rate by the second flow rate sensor instead of the measured value of the blood flow rate by the flow rate sensor 66, the temporary Therefore, the movement of the stimulation lead 70 along the superior vena cava Sv can be more appropriately detected.

  The body position may be detected by an acceleration sensor, and for example, a difference between the first flow velocity sensor and the second flow velocity sensor in both the standing position and the lying position may be stored. By canceling the change in the flow velocity due to the body position based on the stored difference, the change in the flow velocity due to the movement of the detention unit 20 can be accurately detected.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. 9, but the same portions as those in the above embodiment will be denoted by the same reference numerals, and description thereof will be omitted. Only different points will be described.
As illustrated in FIG. 9, the nerve stimulation system 4 includes a detection unit including a strain sensor 76 that detects a deformation amount of the urging member 21 instead of the biological signal acquisition unit 30 of the nerve stimulation system 1 of the first embodiment. 75 is provided.
As the strain sensor 76, a sensor having a known configuration can be appropriately selected and used. The strain sensor 76 is attached to the urging member 21 with an adhesive or the like.

A method of detecting the movement of the stimulation lead 80 of the present embodiment configured to detect the movement of the stimulation lead 80 of the nerve stimulation system 4 thus configured and placed in the superior vena cava Sv will be described.
When the positioning of the indwelling section 20 with respect to the superior vena cava Sv is completed, the user presses the switch 42. The detector 75 detects the amount of deformation (strain) of the urging member 21, and the measured value of the amount of deformation of the urging member 21 at the reference time when the user presses the switch 42 and inputs an instruction is used as a reference deformation amount measured value. It is stored in the storage unit 44.
When the stimulation lead 80 is placed in the superior vena cava Sv, the detection unit 75 detects the amount of deformation of the urging member 21 at every interval time. The determination unit 45 compares the measured value of the deformation amount of the urging member 21 with the measured reference deformation amount stored in the storage unit 44, and determines whether the indwelling unit 20 has moved along the superior vena cava Sv. Is determined.

More specifically, when the measured value of the amount of deformation of the urging member 21 becomes equal to or less than the value obtained by subtracting the threshold value stored in its own memory from the measured value of the amount of deformation of the urging member 21, the determination unit 45 displays the display unit 47. A warning is displayed indicating that the measured value of the amount of deformation of the urging member 21 is too small, that is, that the indwelling unit 20 has moved to the right atrium Ht1. Generally, since the inner diameter of the superior vena cava Sv increases as it approaches the right atrium Ht1 of the heart Ht, when the indwelling unit 20 moves toward the right atrium Ht1, the amount of deformation of the urging member 21 decreases. Here, even if the inner diameter of the blood vessel changes momentarily due to body movement, etc., if the numerical value of the deformation amount is not continuous or changes suddenly, the rate of change is measured. Alternatively, the determination can be made by making a comparison every measurement time, so that accurate determination can be maintained.
On the other hand, when the measured value of the deformation amount of the urging member 21 becomes equal to or more than the value obtained by adding the threshold value stored in its own memory from the reference deformation amount measured value, the determination unit 45 urges the display unit 47. A warning is displayed indicating that the measured value of the deformation amount of the member 21 is too large, that is, that the placement section 20 has moved to the head side.
The determination unit 45 causes the display unit 47 to display a warning and, at the same time, stops the stimulus signal generated by the stimulus generation unit 43.

  As described above, according to the movement detecting method of the stimulation lead 80 and the nerve stimulation system 4 of the present embodiment, the movement of the stimulation lead 80 along the superior vena cava Sv can be suitably detected.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described with reference to FIG. 10, but the same parts as those in the above embodiment will be denoted by the same reference numerals, and the description thereof will be omitted, and only different points will be described.
As shown in FIG. 10, the present nerve stimulation system 5 is an acceleration sensor that detects the acceleration of the indwelling unit 20 instead of the biological signal acquisition unit 30, the switch 42, and the storage unit 44 of the nerve stimulation system 1 of the first embodiment. A detection unit 85 having an 86 is provided. That is, the switch 42 and the storage unit 44 are not provided in the nerve stimulation system 5.
The acceleration sensor 86 preferably has a known configuration capable of measuring a six-component force. The six-component force means forces parallel to three axes orthogonal to each other fixed to the acceleration sensor 86 and moments around each axis.
The acceleration sensor 86 is attached to the urging member 21 of the retaining section 20 with an adhesive or the like.

A method of detecting the movement of the stimulation lead 90 of the present embodiment for detecting the movement of the stimulation lead 90 of the nerve stimulation system 5 thus configured and placed in the superior vena cava Sv will be described.
When the positioning of the placement section 20 with respect to the superior vena cava Sv is completed, the user places the stimulation lead 90 in the superior vena cava Sv.
The detecting unit 85 detects the acceleration of the indwelling unit 20 at every interval time. The determination unit 45 compares the measured value of the acceleration of the indwelling unit 20 with a threshold stored in its own memory, and determines whether the indwelling unit 20 has moved with respect to the superior vena cava Sv. For example, if either the size of the combined three forces or the size of the combined three moments is equal to or greater than the threshold, it is determined that the indwelling unit 20 has moved with respect to the superior vena cava Sv.
In this case, the determination unit 45 determines that the measured value of the acceleration of the indwelling unit 20 is too large on the display unit 47, that is, the indwelling unit 20 has moved in any axial direction or around the superior vena cava Sv. Display a warning indicating that
The determination unit 45 causes the display unit 47 to display a warning and, at the same time, stops the stimulus signal generated by the stimulus generation unit 43.

In the present embodiment, the determination unit 45 can detect not only movement in the direction along the superior vena cava Sv of the stimulation lead 90 but also movement or rotation in any direction in the three-dimensional space.
As described above, according to the method for detecting the movement of the stimulation lead 90 and the nerve stimulation system 5 of the present embodiment, the movement and rotation of the stimulation lead 90 in any direction with respect to the superior vena cava Sv can be suitably detected. .

In this embodiment, the detection unit 85 may be configured to include a second acceleration sensor different from the acceleration sensor 86. The second acceleration sensor is provided in the stimulus generator 40. The stimulus generator 40 is fixed to the body surface, for example, the chest, so that the position with respect to the heart Ht does not change due to body movement. The second acceleration sensor may be provided at the tip of the conductor 35 or the like.
By using the difference between the measured value of the acceleration of the detention unit 20 by the acceleration sensor 86 and the measured value of the acceleration by the second acceleration sensor instead of the measured value of the acceleration of the detention unit 20 by the acceleration sensor 86, the stimulation by the body movement is performed. The acceleration of the lead 90 can be separated from the acceleration of the stimulation lead 90 with respect to the superior vena cava Sv. Therefore, the acceleration of the stimulation lead 90 with respect to the superior vena cava Sv can be detected more accurately.

As described above, the first to fifth embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the configuration is within the scope of the present invention. Changes, combinations, etc. are also included. Further, it goes without saying that each of the configurations shown in each embodiment can be appropriately combined and used.
For example, in the first to fifth embodiments, the display unit 47 is provided in the nerve stimulation system, and a warning is displayed on the display unit 47 according to the determination result of the determination unit 45 to alert the user and Then, the stimulus signal generated by the stimulus generation unit 43 was stopped. However, the nerve stimulation system 1 may be provided with a speaker instead of the display unit 47, and the user may be alerted by the sound emitted from the speaker. Further, the stimulation signal generated by the stimulation generation unit 43 may be simply stopped without providing the display unit 47 in the nerve stimulation system 1.

The case where the stimulation lead is placed in the superior vena cava Sv has been described. However, the blood vessel in which the stimulation lead is placed is not limited to the superior vena cava Sv, and may be a vein or artery other than the superior vena cava Sv. For example, a stimulation lead may be placed in the popliteal vein to apply a stimulation signal to a nerve, such as the peroneal nerve.
Biosignals such as bioimpedance, blood pressure, and blood flow rate were detected to determine whether the stimulation lead moved relative to the superior vena cava Sv. However, the biological signal used to determine the movement of the stimulation lead is not limited to this, and any biological signal generated by the living body such as an electrocardiographic waveform can be used.

1, 1A, 1B, 1C, 2, 2A, 3, 4, 5 Nerve stimulation system 10, 60, 70, 80, 90 Stimulation lead (nerve stimulation electrode)
Reference Signs List 20 indwelling unit 21 urging member 25 stimulating unit 26, 27 stimulating electrode 30, 50, 55, 65 biological signal acquisition unit (detection unit)
31, 32, 51, 52 Measurement electrode 44 Storage unit 45 Judgment unit 56 Pressure sensor 66 Flow velocity sensor 75, 85 Detection unit 76 Strain sensor 86 Acceleration sensor P Patient (living body)
Sv Superior vena cava (blood vessel)

Claims (5)

An indwelling portion having an elastically deformable biasing member and locked in a blood vessel of a living body,
A stimulating unit provided on the urging member and having a pair of stimulating electrodes to which a stimulating signal for stimulating a nerve is applied;
And, a nerve stimulation electrode including a detection unit that detects a biological signal about blood when placed in the blood vessel,
A storage unit that stores a reference biological signal measurement value that is a measurement value of the biological signal detected by the detection unit at a reference time when an instruction is input,
A determination unit that compares the measurement value of the biological signal detected by the detection unit with the reference biological signal measurement value, and determines whether the indwelling unit has moved along the blood vessel.
A nerve stimulation system comprising: An indwelling portion having an elastically deformable biasing member and locked in a blood vessel of a living body,
A stimulating unit provided on the urging member and having a pair of stimulating electrodes to which a stimulating signal for stimulating a nerve is applied;
And, a nerve stimulation electrode including a detection unit that detects the amount of deformation of the biasing member when placed in the blood vessel,
A storage unit that stores a reference deformation amount measurement value that is a measurement value of the deformation amount detected by the detection unit at a reference time when an instruction is input,
A determination unit that compares the measurement value of the deformation amount detected by the detection unit with the reference deformation amount measurement value and determines whether the indwelling unit has moved along the blood vessel.
A nerve stimulation system comprising: The nerve stimulation system according to claim 1 ,
The detection unit has a pair or more measurement electrodes for detecting blood impedance or blood conductivity as the biological signal. The nerve stimulation system according to claim 1 ,
The detection unit has a flow rate sensor for detecting a blood flow rate as the biological signal. The nerve stimulation system according to claim 2 ,
The detection unit has a strain sensor provided on the urging member.

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