JP6950337B2 - In-vivo potential measuring instrument and in-vivo potential measuring system - Google Patents

Description

The present invention includes an in-vivo potential measuring device that is inserted into an organ of a living body and measures the potential of a predetermined portion on the inner wall surface of the organ, an in-vivo potential measuring method, and an in-vivo potential measuring device. In vivo potential measurement system.

A catheter is inserted into an organ such as a blood vessel to inspect and treat a lesion.

One of the treatments using a catheter is a catheter ablation treatment with a balloon. In this treatment, a balloon is attached to the tip of a catheter, the balloon is inflated by injecting liquid into the balloon, and then the liquid in the balloon is warmed by a high-frequency current to cauterize the organ in contact with the surface of the balloon. For example, it is applied to the treatment of atrial fibrillation.

According to this treatment, since the balloon has a flexible spherical shape, the outer peripheral surface of the inflated balloon is ring-shaped on the inner wall surface near the junction between the left atrium and the pulmonary vein, which is the treatment site for atrial fibrillation. Since they can be brought into contact with each other, the area around the pulmonary veins can be cauterized at one time.

On the other hand, after cauterizing an organ by ablation treatment, the potential of the organ near the cauterization is measured in order to confirm the cauterizing effect. For example, in Patent Document 1, a catheter having a plurality of electrodes for measuring potential at the tip is inserted into an organ, and each electrode is brought into contact with an organ near cauterization to obtain the potential of the portion where each electrode is in contact. The method of measurement is described.

Japanese Patent No. 5870694

6 (a) to 6 (c) show a method of cauterizing an organ in contact with a balloon using a catheter with a balloon and then measuring the potential of an organ near the cauterization using a conventional electrode for measuring potential. It is a figure which showed. Here, as a site to be cauterized, the vicinity of the junction between the left atrium and the pulmonary vein, which is a treatment site for atrial fibrillation, will be described as an example.

As shown in FIG. 6A, a catheter 10 having a balloon 30 attached to the tip is inserted in the vicinity of the junction between the left atrium 50 and the pulmonary vein 51. Then, by injecting the liquid 21 into the balloon 30, the balloon 30 is inflated so that the outer peripheral surface of the balloon 30 is brought into contact with the inner peripheral surface of the organ 52 in a ring shape. Reference numeral 60 indicates an abnormal electrical signal source that is the origin of atrial fibrillation.

Next, as shown in FIG. 6B, a high-frequency current is passed through the electrode 20 to warm the liquid 21 in the balloon 30, thereby cauterizing the organ 52 in contact with the surface of the balloon 30. As a result, a cauterized site (cauterized site) 61 is formed at the site of the organ in contact with the balloon 30.

Next, as shown in FIG. 6C, the catheter with a balloon 10 is pulled out, and the catheter 100 having a plurality of electrodes (Lasso electrodes) 110 for potential measurement at the tip is inserted to the vicinity of the cauterization site 61. Then, a plurality of electrodes 110 are brought into contact with the organ 52, and the potential of the contacted portion is measured.

However, when the ring-shaped electrode 110 as shown in FIG. 6C is used, the potential of the portion where the plurality of electrodes 110 are in contact is intermittently measured, so that the potential of the portion between the electrodes is not measured. ..

On the other hand, since the conduction path of the abnormal electrical signal in atrial fibrillation extends around the pulmonary vein 51, in order to cut off the conduction path of the abnormal electrical signal, all the sites where the surface of the balloon 30 contacts in a ring shape are all. Needs to be cauterized. Therefore, even if there is a part that could not be cauterized (non-cauterized part), if the plurality of electrodes 110 are not in contact with the non-cauterized part, the potential of the part that is not in contact is not measured. As a result, the existence of the uncauterized portion may be overlooked, so that the cauterizing effect cannot be confirmed accurately.

Further, since the ring-shaped electrode 110 is not sufficiently flexible, the comb is too flexible and is excessively deformed, so that it is difficult to bring all the electrodes 110 into contact with the organ 52. If some of the electrodes 110 are not in contact with the organ 52, the potential of the non-contact portion is not measured, and the existence of the uncauterized portion may be overlooked.

Further, as shown in FIG. 6C, the portion in contact with the ring-shaped electrode 110 may be displaced from the ablation portion 61. In this case, since the ring-shaped electrode 110 measures the potential of the portion deviated from the cauterization portion 61, the cauterization effect cannot be confirmed accurately.

Further, after cauterizing with the balloon 30, it is necessary to temporarily remove the catheter 10 with the balloon 30 and insert a new catheter 100 having a ring-shaped electrode 110, so that it takes a long time to confirm the cauterizing effect. It will take. In addition, the risk of air entering the organ increases due to the insertion and removal of the catheters 10 and 110.

The present invention has been made in view of the above problems, and its main purpose is to accurately measure the potential of the cauterized part when the circumference of the inner wall surface of the organ is cauterized by ablation treatment or the like. The purpose is to provide a potential measuring instrument.

The in-vivo potential measuring instrument according to the present invention is an in-vivo potential measuring instrument that is inserted into an organ of a living body to measure the potential of a predetermined portion on the inner wall surface of the organ, and is an insulating member and an insulating member. It is characterized by having an electrode arranged inside, and measuring the potential of the contacted portion with the electrode in a state where the outer peripheral surface of the insulating member is in contact with the inner wall surface of the organ.

According to the present invention, it is possible to provide an in-vivo potential measuring instrument capable of accurately measuring the potential of a cauterized portion when cauterizing the periphery of the inner wall surface of an organ by ablation treatment or the like.

It is a figure which showed typically the structure of the in-vivo potential measuring instrument in one Embodiment of this invention. It is a figure which showed typically the state which the outer peripheral surface of the insulating member was in contact with the inner wall surface of an organ. It is an equivalent circuit diagram which showed the method of measuring the electric potential of the part where the outer peripheral surface of an insulating member came into contact with the inner wall surface of an organ by the electrode arranged in the insulating member. In (a) to (c), after cauterizing the inner wall surface of the organ using the insulating member, the potential of the contacted portion is measured in a state where the outer peripheral surface of the insulating member is in contact with the inner wall surface of the organ. , It is a figure explaining the method of measuring with the electrode arranged in the insulating member. It is a graph which showed the waveform of the voltage measured by the amplifier before and after cauterization, respectively. (A) to (c) show a method of cauterizing an organ in contact with a balloon using a catheter with a balloon, and then measuring the potential of an organ near the cauterization using a conventional electrode for measuring potential. It is a figure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments. Further, it can be appropriately changed as long as it does not deviate from the range in which the effect of the present invention is exhibited.

FIG. 1 is a diagram schematically showing a configuration of an in-vivo potential measuring instrument according to an embodiment of the present invention. The in-vivo potential measuring instrument in the present invention is inserted into an organ of a living body to measure the potential of a predetermined portion on the inner wall surface of the organ. In the present embodiment, catheter ablation for atrial fibrillation In the treatment, a case of measuring the potential at the ablation site after ablation will be described as an example.

As shown in FIG. 1, the in-vivo potential measuring instrument according to the present embodiment includes an insulating member 30 whose outer peripheral surface is deformable or expandable, and an electrode 20 arranged in the insulating member 30. .. As the insulating member 30, for example, a balloon having a hollow bag shape can be used. Further, a catheter with a balloon in which a hollow tubular flexible member (catheter) 10 is connected to the insulating member 30 may be used.

In FIG. 1, by injecting a conductive fluid 21 into the insulating member 30, the outer peripheral surface of the insulating member 30 is formed between the left atrium 50 and the pulmonary vein 51, which are treatment sites for atrial fibrillation. It shows a state in which the inner wall surface of the organ 52 in the vicinity of the junction is in contact with the inner wall surface in a ring shape. Here, the conductive fluid 21 can be injected from the outside via, for example, a hollow tubular flexible member (catheter) 10. Further, as the conductive fluid 21, for example, physiological saline or the like can be used.

In the in-vivo potential measuring instrument of the present embodiment, as shown in FIG. 1, in a state where the outer peripheral surface of the insulating member 30 is in contact with the inner wall surface of the organ 52 in a ring shape, the potential of the contacted portion is measured. It is measured by the electrode 20 arranged in the insulating member 30.

As shown in FIG. 1, the potential of the portion in contact with the insulating member 30 is the same as that of the electrode 20 arranged in the insulating member 30 by attaching the reference ground electrode 71 to the surface 72 of the living body. The voltage between the ground electrode 71 and the ground electrode 71 can be measured by amplifying the voltage with an amplifier 70 arranged outside the living body.

Further, in the insulating member 30 of the present embodiment, a high-frequency current is applied to the electrodes 20 arranged in the insulating member 30 in a state where the outer peripheral surface of the insulating member 30 is in contact with the inner wall surface of the organ. By heating the fluid 21, it may also have a function of cauterizing a portion in contact with the insulating member (ablation function).

Next, in the present embodiment, the principle of measuring the electric potential in the living body will be described with reference to FIGS. 2 and 3.

FIG. 2 is a diagram schematically showing a state in which the outer peripheral surface of the insulating member 30 is in contact with the inner wall surface of the organ 52. Here, since the fluid 21 injected into the insulating member 30 has conductivity, the potential of the inner peripheral surface of the insulating member 30 in contact with the fluid 21 is the insulating member. It is considered to be substantially the same as the potential of the electrode 20 arranged in 30. Therefore, as shown in FIG. 2, the electrode 20 and the inner wall surface of the organ 52 form the capacitance-coupled electrode 80 with the insulating member 30 interposed therebetween.

FIG. 3 is an equivalent circuit diagram showing a method of measuring the potential of a portion where the outer peripheral surface of the insulating member 30 contacts the inner wall surface of the organ 52 with an electrode 20 arranged in the insulating member 30. .. Here, Vb is a potential measured at a portion where the insulating member 30 is in contact with the inner wall surface of the organ 52, and Ce is a capacitance between the electrode 20 and the organ 52. In addition, Vb is measured at the contact site by transmitting the center of gravity potentials of a plurality of potentials around the organ 52. Further, a reference ground electrode 71 is attached to the surface 72 of the living body, and the voltage between the electrode 20 and the ground electrode 71 is amplified by the amplifier 70 and measured as an output voltage Vout. Further, Cin is the input capacitance of the amplifier 70, and Rin is the input resistance of the amplifier 70.

In the equivalent circuit shown in FIG. 3, the following equation (1) holds from Kirchhoff's second law.

Here, Zce is the impedance of the capacitance between the electrode and the organ, and Zcin is the impedance of the input capacitance of the amplifier.

Further, in the closed loop circuit of the amplifier 70, the following equation (2) holds according to Kirchhoff's first law.

_{When i 2} is solved using the equations (1) and (2), the following equation (3) is obtained.

Further, from Ohm's law, the following equation (4) holds.

By substituting the equation (3) into the equation (4), the following equation (5) is obtained.

The first and second terms of the denominator of the equation (5) are expressed as equations (6) and (7), respectively.

By substituting the equations (6) and (7) into the equation (5), the following equation (8) is obtained.

Here, when the input capacitance Cin of the amplifier 70 is sufficiently small and the input resistance Rin is sufficiently large, that is, when the following equations (9) and (10) hold, the equation (8) is expressed by the following equation. It is expressed as (11).

That is, the voltage Vout measured by the amplifier 70 coincides with the potential Vb of the portion where the insulating member 30 contacts the inner wall surface of the organ 52. Thereby, the potential Vb of the portion where the insulating member 30 comes into contact with the inner wall surface of the organ 52 can be easily measured by the amplifier 70.

By the way, the capacitance Ce between the electrode and the organ shown in FIG. 2 is as shown in the following equation (12), where S is the contact area between the insulating member 30 and the organ and d is the thickness of the insulating member 30. It is represented by.

Here, ε ₀ is the permittivity of the vacuum (8.855 × ^10-12 [F / m]), and ε _r is the relative permittivity of the insulating member 30.

Therefore, when the potential Vb of the portion where the insulating member 30 contacts the inner wall surface of the organ 52 is obtained by using the formula (11), the thickness d of the insulating member 30 is set so as to be satisfied by the formula (9). Is preferable.

For example, assuming that the input capacitance Cin of the amplifier 70 is 10 pF, the contact area S between the insulating member 30 and the organ is 1000 mm ² , and the relative permittivity ε _r of the insulating member 30 is 5 (for example, in the case of polyurethane), the equation ( From 9), d <45 μm. Therefore, the thickness d of the insulating member 30 is typically preferably 40 μm or less, and more preferably 10 μm or less.

Further, in order to obtain the potential Vb of the portion where the insulating member 30 contacts the inner wall surface of the organ 52 using the equation (11), the input resistance Rin of the amplifier 70 is set so as to be satisfied by the equation (10). It is preferable to do so.

For example, the input capacitance C of the amplifier 70 is 10 pF, the capacitance Ce between the electrode and the organ is 1000 pF (Cin / Ce = 0.01), and the potential band f of the portion where the insulating member 30 contacts the inner wall surface of the organ 52. Assuming that (jw = 2πf) is 100 Hz, Rin> 0.2 GΩ from the equation (10). Therefore, the input resistance Rin of the amplifier 70 is typically preferably 1 GΩ or more.

Next, referring to FIGS. 4A to 4C, the inner wall surface of the organ is cauterized using the insulating member 30 in the present embodiment, and then the outer peripheral surface of the insulating member 30 is formed inside the organ. A method of measuring the potential of the contacted portion with the electrode 20 arranged in the insulating member 30 in the state of being in contact with the wall surface will be described. Here, as a site to be cauterized, the vicinity of the junction between the left atrium and the pulmonary vein, which is a treatment site for atrial fibrillation, will be described as an example.

First, as shown in FIG. 4A, a flexible member (catheter) 10 having an insulating member (balloon) 30 attached to the tip thereof is inserted in the vicinity of the junction between the left atrium 50 and the pulmonary vein 51. Then, by injecting the conductive fluid 21 into the insulating member 30, the insulating member 30 is inflated, and the outer peripheral surface of the insulating member 30 is brought into contact with the inner peripheral surface of the organ 52 in a ring shape. .. Reference numeral 60 indicates an abnormal electrical signal source that is the origin of atrial fibrillation.

4 (b) and 4 (c) show an organ 52 in contact with the surface of the insulating member 30 by applying a high-frequency current to the electrode 20 to heat the fluid 21 in the insulating member 30. Shows the state after cauterization. Here, FIG. 4B shows a state in which sufficient cauterization was not performed around the organ 52, and a portion that was not cauterized (non-cauterized portion) remained. On the other hand, FIG. 4C shows a state in which sufficient cauterization is performed around the organ 52 to form a cauterized portion (cauterized portion) 61.

In the state shown in FIG. 4B, when the potential of the portion where the outer peripheral surface of the insulating member 30 is in contact is measured by the electrode 20 arranged in the insulating member 30, all the portions in contact in a ring shape are measured. Since the potential of the above is superimposed, the potential on which the potential at the uncauterized portion is superimposed is measured. Therefore, in this case, it can be confirmed that the cauterization by the ablation treatment was insufficient.

On the other hand, in the state shown in FIG. 4C, when the potential of the portion where the outer peripheral surface of the insulating member 30 is in contact is measured by the electrode 20 arranged in the insulating member 30, the potential at the uncauterized portion is measured. It is not superimposed and measured. Therefore, in this case, it can be confirmed that the cauterization by the ablation treatment was sufficient.

According to the present embodiment, after cauterizing the organ 52 by ablation treatment, when measuring the potential of the organ near the cauterization, the outer peripheral surface of the insulating member 30 is in contact with the inner wall surface of the organ 52 in a ring shape. Since the potential of the contacted portion is measured by the electrode 20 arranged in the insulating member 30, the potential of the organ 52 near the ablation can be reliably measured over the surroundings. As a result, when there is an uncauterized portion, the potential at the uncauterized portion can be measured as an superimposed potential. As a result, the existence of the uncauterized portion is not overlooked, so that the cauterizing effect can be surely confirmed.

Further, since the outer peripheral surface of the insulating member 30 is made of a material that can be deformed or expanded, the outer peripheral surface of the insulating member 30 can be easily changed to the inner wall surface of the organ 52 according to the shape of the organ 52. Can be contacted in a ring shape. As a result, the electric potential of the organ 52 near the cauterization can be reliably measured over the surrounding area. As a result, if there is an uncauterized part, the cauterizing effect can be surely confirmed without overlooking the existence.

Further, the insulating member 30 has a function of applying a high-frequency current to the electrode 20 to cauterize the portion in contact with the insulating member 30, so that the potential of the organ 52 near the cauterization is located at the same position as the cauterized portion. Can be measured, so the cauterization effect can be confirmed accurately.

Further, by measuring the potential of the organ 52 near the cauterization with a capacitance-coupled electrode formed by sandwiching the electrode 20 and the organ 52 with the insulating member 30, the potential over the surroundings is measured at once. be able to.

Further, by forming the insulating member 30 with a balloon made of a hollow bag shape, the film thickness of the insulating member 30 becomes constant, so that the electric potential around the organ 52 can be measured without variation.

Further, when measuring the potential of the organ 52 near the cauterization, it is not necessary to insert and remove the insulating member 30, so that the cauterization effect can be confirmed in a short time. In addition, the risk of air entering the organ 52 due to the insertion and removal of the insulating member 30 can be reduced.

Further, in the present embodiment, the in-vivo potential measuring instrument that measures the potential of a predetermined portion on the inner wall surface of the organ has a simple configuration in which electrodes are arranged in an insulating member, thereby achieving biocompatibility and safety. It is possible to realize an excellent in-vivo potential measuring instrument.

The in-vivo potential measuring method in the present embodiment is an in-vivo potential measuring method for measuring the potential of a predetermined portion on the inner wall surface of an organ of a living body, and includes the following steps (A) to (C).

(A) A step of inserting a hollow bag-shaped insulating member into a living organ using a hollow tubular flexible member coupled to the insulating member (B) Flexibility in the insulating member. A step of injecting a conductive fluid through the member to bring the outer peripheral surface of the insulating member into contact with the inner wall surface of the organ (C) A step of measuring the potential of the contacted portion with an electrode. The in-vivo potential measuring system includes an in-vivo potential measuring device shown in FIG. 1 and an amplifier 70 that amplifies the potential detected by the electrode 20.

Using the in-vivo potential measuring device in the present embodiment, after cauterizing the organ by ablation treatment, the potential of the organ near the cauterization was measured, and a demonstration experiment was conducted to confirm the cauterizing effect.

The demonstration experiment was conducted using an animal (pig), and by inserting a catheter with a balloon and injecting a mixed solution of physiological saline and contrast medium into the balloon, the outer peripheral surface of the balloon was formed around the inner circumference of the ablation target site. The surface was brought into contact with the surface in a ring shape. In the demonstration experiment, a spherical polyurethane balloon having a diameter of 20 mm and a thickness of 0.02 mm was used.

In this state, the potential of the inner wall surface of the ablation site with which the balloon was in contact was measured using an electrode placed inside the balloon. The reference ground electrode was attached to the body surface of the animal, and the voltage between the electrode placed in the balloon and the ground electrode was amplified by an amplifier and measured. The input capacitance of the amplifier used was 1 pF, and the input resistance was 10000 GΩ (10 TΩ).

Next, while maintaining this state, a high-frequency current is applied to the electrodes in the balloon to heat the mixed solution of physiological saline and contrast medium in the balloon to about 70 ° C., thereby contacting the surface of the balloon. The part of the balloon was cauterized. Then, by the same method as above, the potential of the portion where the balloon was in contact was measured using the electrodes arranged in the balloon.

FIG. 5 is a graph showing the waveforms of the voltages measured by the amplifier before and after cauterization, respectively. The waveforms (dotted lines) indicated by arrow B are the waveforms before cauterization and the waveforms indicated by arrow A (dotted lines). The solid line) shows the waveform after cauterization. In addition, each waveform shows the addition average of 14 beats.

As shown in FIG. 5, it can be seen that in the waveform before cauterization, the potential waveform to be cauterized indicated by the arrow P disappears in the waveform after cauterization. As a result, it was confirmed that all the parts where the surface of the balloon was in contact with each other in a ring shape were cauterized over the surrounding area.

Although the present invention has been described above in terms of preferred embodiments, such a description is not a limitation, and of course, various modifications can be made. For example, in the above embodiment, the hollow bag-shaped balloon has been described as an example of the insulating member 30, but the present invention is not limited to this, and the electrode 20 for potential measurement is coated with the insulating member 30. May be good. Further, the electrode 20 for measuring the potential may be coated with the insulating member 30 via the conductive fluid 21.

Further, in the above embodiment, an example of measuring the potential of an organ near the ablation after cauterization of the organ by the ablation treatment has been described, but in order to diagnose the condition of the lesion before the ablation treatment, the vicinity of the lesion is used. It can also be applied when measuring the potential of the organs of. Further, during the cauterization of the organ by the ablation treatment, the potential of the organ near the cauterization may be measured in order to monitor the state of the cauterization. In this case, the energization of the high-frequency current to the electrode 20 and the measurement of the electric potential using the electrode 20 may be alternately performed in a time-divided manner.

Further, in the above embodiment, the example in which the reference ground electrode 71 is arranged on the surface of the living body has been described, but the ground electrode 71 may be arranged inside the living body. As a result, the living body itself has a shielding effect, so that the electric potential of the organ can be measured in a state where noise is reduced. For example, the ground electrode 71 may be attached to the tip of the catheter. Further, a plurality of reference ground electrodes 71 may be arranged on the body surface or inside the body, or a virtual ground electrode may be calculated from the plurality of ground electrodes.

Further, in the above embodiment, in a state where the outer peripheral surface of the insulating member 30 is in contact with the inner wall surface of the organ in a ring shape, the potential of the contacted portion is measured by the electrode 20 arranged in the insulating member 30. An example of measurement has been described, but the present invention is not limited to this, and the insulating member 30 is pressed against a flat surface portion, and the potential of the contacted portion is measured by the electrode 20 arranged in the insulating member 30. You may. For example, the insulating member 30 is pressed against the flat inner wall surface of the organ, and the insulating member 30 is deformed so as to follow the surface shape of the flat portion, and the potential of the contacted portion is measured in the contacted state. It may be measured by the electrode 20.

Further, in the above embodiment, an example of applying the in-vivo potential measuring device to a scene of measuring the potential of an organ near the ablation after ablation of the organ by ablation treatment has been described, but the present invention is not limited to this, and diagnosis and treatment are not limited to this. Or, in order to confirm the therapeutic effect, the insulating member 30 can be inserted into an organ of a living body and applied to any situation where the potential of a predetermined portion on the inner wall surface of the organ is measured.

10 Hollow tubular flexible member (catheter)
20 electrodes
21 Conductive fluid
30 Insulating member (balloon)
52 organs
61 Cauterization site
70 amplifier
71 Ground electrode

Claims (9)

An in-vivo potential measuring instrument that is inserted into an organ of a living body and measures the potential of a predetermined part on the inner wall surface of the organ.
Hollow bag-shaped insulating member and
The conductive fluid injected into the insulating member and
An electrode disposed in said fluid,
With
Wherein the electrode and the inner wall surface of the front Symbol organs, through the fluid, across the insulating member, constitutes a capacitive coupling electrodes,
The insulating member was brought into contact with the insulating member by applying a high-frequency current to the electrode to heat the conductive fluid in a state where the outer peripheral surface of the insulating member was in contact with the inner wall surface of the organ. It also has the function of cauterizing the part,
An in-vivo potential measuring instrument that measures the potential of the contacted portion with the electrode in a state where the outer peripheral surface of the insulating member is in contact with the inner wall surface of the organ in a ring shape. The in-vivo potential measuring instrument according to claim 1, wherein the insulating member is composed of a member whose outer peripheral surface is deformable or expandable along the shape of the contacted portion. A hollow tubular flexible member coupled to the insulating member is further provided.
The in-vivo potential measuring instrument according to claim 1, wherein a conductive fluid is injected into the insulating member via the flexible member. The in-vivo potential measuring instrument according to claim 1 or 2 , wherein the potential of the contacted portion is measured by measuring the voltage between the electrode and the reference ground electrode. The potential of the contacted portion is measured by amplifying the potential detected by the electrode with an amplifier arranged outside the living body.
When the capacitance of the insulating member at the contacted portion is Ce and the input capacitance of the amplifier is Cin, the thickness of the insulating member is set to satisfy Cin / Ce <0.01. The in-vivo potential measuring instrument according to any one of claims 1 to 4. The potential of the contacted portion is measured by amplifying the potential detected by the electrode with an amplifier arranged outside the living body.
When the capacitance of the insulating member at the contacted portion is Ce and the potential band of the predetermined portion on the inner wall surface of the organ is f, the input resistance Rin of the amplifier is 1 / (2πfCeRin) <0.01. The in-vivo potential measuring instrument according to any one of claims 1 to 4 , which is set to satisfy the above conditions. The in-vivo potential measuring instrument according to claim 3 , wherein the insulating member and the flexible member are composed of a catheter with a balloon. The in-vivo potential measuring instrument according to claim 4 , wherein the reference ground electrode is arranged inside the living body. The in-vivo potential measuring instrument according to any one of claims 1 to 7.
An in vivo potential measurement system including an amplifier that amplifies the potential detected by the electrodes.

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