Electrode catheter and medical device

Abstract

This electrode catheter comprises: a shaft 6; and a catheter electrode 10 provided in a distal-end-side region 6D of the shaft 6 and configured to apply a voltage to biological tissue. The shaft 6 has a small-diameter portion 44 in a proximal-end-side region 6P of the shaft 6 located on the proximal end side with respect to the catheter electrode 10. In the state where the shaft 6 is inserted into a blood vessel of a patient through a sheath 4, the small-diameter portion 44 extends within the sheath 4 and has a smaller diameter than the distal-end-side region 6D extending outside the sheath 4.

Description

Electrode Catheter and Medical Device

[0001] The present disclosure relates to an electrode catheter and a medical device.

[0002] Conventionally, a defibrillation catheter that is inserted into a heart chamber and used for defibrillation is known (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2010-63708

[0004] An electrode catheter including a defibrillation catheter is often inserted into a blood vessel of a patient via a sheath that has been percutaneously inserted into the patient's blood vessel in advance. Additionally, in a procedure for inserting an electrode catheter into a patient's blood vessel, blood collection may be performed to determine the state of blood and the like.

[0005] The present inventors have studied performing blood collection using a sheath and have come to recognize the following problems. That is, when blood collection is performed with the electrode catheter inserted into the sheath, blood needs to pass through the gap between the sheath and the electrode catheter. However, high-viscosity blood is less likely to flow through the gap, which can make blood collection difficult. Accordingly, it is conceivable to reduce the diameter of the electrode catheter to widen the gap between the sheath and the electrode catheter. However, in this case, the rigidity and consequently the operability of the electrode catheter decrease, which can make insertion of the electrode catheter into the blood vessel difficult.

[0006] The present disclosure has been made in view of these circumstances, and an object thereof is to provide a technique that enables blood collection using a sheath while suppressing a decrease in the operability of the electrode catheter.

[0007] One aspect of the present disclosure is an electrode catheter. The electrode catheter includes a shaft, and a catheter electrode provided in a distal end region of the shaft for applying a voltage to a living tissue. The shaft has, in a proximal end region located closer to the proximal end of the shaft than the catheter electrode, a small-diameter portion that extends inside the sheath when the shaft is inserted into the patient's blood vessel via the sheath and has a smaller diameter than the diameter of the distal end region extending outside the sheath.

[0008] Another aspect of the present disclosure is a medical device. This medical device comprises an electrode catheter as described above and a sheath through which the electrode catheter is inserted. The sheath has a tip that is inserted into the patient's blood vessel to serve as the insertion port for the electrode catheter, and a small diameter portion that extends into the sheath when the electrode catheter is inserted into the blood vessel through the sheath, and a port on the proximal end to which a blood aspirator is connected, and blood flows from the blood vessel to the port side through the gap between the inner surface of the sheath and the outer surface of the small diameter portion.

[0009] Another aspect of the present disclosure is an electrode catheter. This electrode catheter comprises a shaft and a catheter electrode provided at the tip of the shaft for applying a voltage to biological tissue. The shaft has a narrow portion at the proximal end, located on the proximal end side of the shaft relative to the catheter electrode, with a diameter smaller than the diameter of the tip portion.

[0010] Any combination of the above components, as well as any conversion of the expressions of this disclosure between methods, apparatus, systems, etc., are also valid forms of this disclosure.

[0011] According to this disclosure, it is possible to enable blood collection using a sheath while suppressing a decrease in the operability of the electrode catheter.

[0012] This is a schematic diagram of a medical device according to an embodiment. Figure 2(A) is a cross-sectional view along the line B-B in Figure 1. Figure 2(B) is a cross-sectional view along the line C-C in Figure 1. This is a schematic diagram showing the electrode catheter inserted into the sheath.

[0013] The present disclosure will be described below with reference to the drawings, based on preferred embodiments. The embodiments are illustrative and not limiting, and not all features or combinations thereof described in the embodiments are necessarily essential to the present disclosure. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant descriptions are omitted where appropriate. The scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and are not to be interpreted restrictively unless otherwise specified. Furthermore, where terms such as "first," "second," etc. are used in this specification or claims, unless otherwise specified, these terms do not indicate any order or importance, but are used to distinguish one configuration from another. In addition, some components that are not important for explaining the embodiments are omitted in each drawing.

[0014] Figure 1 is a schematic diagram of a medical device 1 according to an embodiment. Note that the small diameter portion 44 is not shown in Figure 1. The medical device 1 comprises an electrode catheter 2 and a sheath 4. The electrode catheter 2 is inserted through the sheath 4. The sheath 4 is a flexible tubular member. The sheath 4 can be made of a known flexible material containing resins such as polytetrafluoroethylene (PTFE) or polyether block amide (PEBAX). The tip end of the sheath 4 is inserted into the patient's blood vessel prior to the electrode catheter 2, and the opening at the proximal end becomes the insertion port for the electrode catheter 2. The sheath 4 expands the blood vessel and assists in the insertion of the electrode catheter 2 into the blood vessel. The length of the sheath 4 is, for example, 100 mm or more and 900 mm or less. The diameter of the sheath 4 is, for example, 4Fr (1.33 mm), 5Fr (1.67 mm), 6Fr (2.0 mm), or 7Fr (2.33 mm).

[0015] The electrode catheter 2 in this embodiment is a defibrillation catheter that is inserted into the patient's heart chamber to perform defibrillation. However, the electrode catheter 2 and medical device 1 may be used for procedures other than defibrillation. The electrode catheter 2 comprises a shaft 6, a handle 8, and a catheter electrode 10.

[0016] The shaft 6 is, for example, an insulating tubular member having a multi-lumen structure, with at least its tip being inserted into the patient's heart chamber. The shaft 6 may also have a single-lumen structure. The shaft 6 can be made of known flexible materials, including resins such as polyether block amide (PEBAX), polyolefin, polyamide, polyurethane, nylon, and polyester.

[0017] The shaft 6 of this embodiment includes a tip region 6D and a proximal region 6P. The tip region 6D is the region from the tip of the shaft 6 to the proximal end of the catheter electrode 10 located at the most proximal end of the shaft 6. The proximal region 6P is located on the proximal end side of the shaft 6 beyond the catheter electrode 10 located at the most proximal end of the shaft 6. The catheter electrode 10 that serves as the reference for the range of the proximal region 6P is an electrode for applying voltage to biological tissue. For example, the catheter electrode 10 is an electrode that applies voltage to biological tissue to treat or have a therapeutic effect on biological tissue. As an example, the proximal end of the tip region 6D and the tip of the proximal region 6P are connected to each other. Also, a handle 8 is connected to the proximal end of the proximal region 6P. The length of the shaft 6 is, for example, 600 mm or more and 1500 mm or less, and as an example, 800 mm. The length of the tip region 6D is, for example, 50 mm or more and 300 mm or less, and as an example, 230 mm. The length of the proximal region 6P is, for example, 400 mm or more and 1300 mm or less, and is 570 mm as an example.

[0018] The handle 8 is connected to the proximal end of the shaft 6 and is positioned outside the body when the electrode catheter 2 is in use, and is grasped and operated by the user. The handle 8 has a handle body 12 and an operating part 14. The handle body 12 has a connector (not shown). An external power supply (not shown) is electrically connected to the connector. The operating part 14 can rotate in the direction of arrow A1. The connector may be separate from the handle 8. In this case, the connector may be positioned on the proximal end side of the electrode catheter 2, such as by being connected to the handle 8 by a cable.

[0019] The catheter electrode 10 is provided in the tip-side region 6D of the shaft 6. The catheter electrode 10 is made of, for example, a metal or an alloy thereof with good conductivity and contrast properties for X-rays. For example, the catheter electrode 10 is ring-shaped and extends around the entire circumference of the shaft 6. The outer diameter of the catheter electrode 10 is substantially the same as the outer diameter of the tip-side region 6D. The outer diameter of the tip-side region 6D is substantially uniform throughout, except for the portion where the catheter electrode 10 is provided. The portion where the catheter electrode 10 is provided is recessed by the thickness of the catheter electrode 10. The catheter electrode 10 may also be shaped to extend along a portion of the circumferential direction of the shaft 6. The electrode catheter 2 of this embodiment has a plurality of catheter electrodes 10. For example, the plurality of catheter electrodes 10 can be divided into a first electrode group G1 and a second electrode group G2. The first electrode group G1 and the second electrode group G2 each include a plurality of catheter electrodes 10. The first electrode group G1 is positioned closer to the tip than the second electrode group G2 in the tip-side region 6D.

[0020] In each electrode group, multiple catheter electrodes 10 are arranged at predetermined intervals in the axial direction of the shaft 6. In the example shown in Figure 1, the first electrode group G1 and the second electrode group G2 each contain eight catheter electrodes 10, but the number of catheter electrodes 10 belonging to each electrode group can be set as appropriate. The first electrode group G1 and the second electrode group G2 are arranged with a larger spacing than the spacing between adjacent catheter electrodes 10 within each electrode group.

[0021] The catheter electrodes 10 belonging to the first electrode group G1 and the catheter electrodes 10 belonging to the second electrode group G2 are electrodes to which a voltage for defibrillation is applied. DC voltages of different polarities are applied to the first electrode group G1 and the second electrode group G2. For example, when intracardiac defibrillation is performed with electrode catheter 2, the first electrode group G1 is placed in the coronary sinus (CS), and the second electrode group G2 is placed in the right atrium (RA).

[0022] In this embodiment, a non-applied electrode 11, which is not used to apply voltage to biological tissue, is provided on the proximal end side of the shaft 6, i.e., in the proximal end region 6P, relative to the catheter electrode 10. The non-applied electrode 11 includes, for example, electrodes for EP (Electrophysiology Study) and electrodes for measuring reference impedance. For example, the non-applied electrode 11 is an electrode that does not apply voltage to biological tissue for treating or having a therapeutic effect on biological tissue. The reference impedance is the impedance that serves as the reference point, or zero point, when determining contact between the catheter electrode 10 for ablation or voltage application to biological tissue and biological tissue. The non-applied electrode 11 can be made of the same material as the catheter electrode 10 and may have a similar shape. The outer diameter of the proximal end region 6P is substantially uniform throughout, except for the portion where the non-applied electrode 11 is provided. The portion where the non-applied electrode 11 is provided is recessed by the thickness of the non-applied electrode 11.

[0023] The electrode catheter 2 of this embodiment has a third electrode group G3 that includes a plurality of non-applied electrodes 11. In the example shown in Figure 1, the third electrode group G3 includes four non-applied electrodes 11, but the number of non-applied electrodes 11 belonging to the third electrode group G3 can be set as appropriate. The third electrode group G3 is arranged in the vicinity of the second electrode group G2. The second electrode group G2 and the third electrode group G3 are arranged with a larger gap between them than the gap between adjacent catheter electrodes 10 in the second electrode group G2 and the gap between adjacent non-applied electrodes 11 in the third electrode group G3. One example of a non-applied electrode 11 belonging to the third electrode group G3 is an electrode for EP testing. In addition, a non-applied electrode 11 for measuring reference impedance, which is placed outside the cardiac chamber, may be arranged proximal to the third electrode group G3. Furthermore, a non-applied electrode 11 may also be placed between the first electrode group G1 and the second electrode group G2.

[0024] Figure 2(A) is a cross-sectional view along the line B-B in Figure 1. Figure 2(B) is a cross-sectional view along the line C-C in Figure 1. As an example, the shaft 6 has an inner tube 16 and an outer tube 18. The outer tube 18 covers the outer surface of the inner tube 16. The inner tube 16 and the outer tube 18 are each made of the known flexible material described above.

[0025] In the base end region 6P, a reinforcing member 20 is provided at the interface between the inner tube 16 and the outer tube 18. As a result, the base end region 6P has higher bending rigidity than the tip end region 6D. In this disclosure, "high bending rigidity" means that the bending load measured by a three-point bending test, in which the distance between the supports of the test piece is 70 mm and a bending load is applied at the midpoint to produce a deflection of 10 mm, is large.

[0026] The reinforcing member 20 has a known structure such as a braided blade or a coil. Examples of materials for the reinforcing member 20 include metals such as tungsten, stainless steel, and nickel-titanium, and resins such as nylon, polyetherketone (PEEK), and liquid crystal polymer. The braided blade or coil may be made of round wire or flat wire. Flat wire allows the reinforcing member 20 to be thinner than round wire. This makes it easier to provide the small diameter section 44, which will be described later. The rigidity of the reinforcing member 20, which may decrease due to its thinness, can be maintained by widening the width of the flat wire, increasing the spacing between adjacent flat wires, or increasing the number of flat wires that make up the reinforcing member 20. In addition to, or instead of, laying the reinforcing member 20, the bending rigidity of the base end region 6P may be increased compared to the bending rigidity of the tip end region 6D by differences in the hardness of the materials that make up the inner tube 16 and the outer tube 18, or by embedding known plate springs or rod springs inside the inner tube 16.

[0027] In this embodiment, the tip region 6D is not provided with a reinforcing member 20. The base region 6P is made of a resin with higher hardness than the tip region 6D and is provided with a reinforcing member 20. As a result, the bending rigidity of the base region 6P is higher than that of the tip region 6D. Alternatively, a reinforcing member 20 with lower strength than the reinforcing member 20 provided in the base region 6P may be provided in the tip region 6D.

[0028] The shaft 6 has a plurality of lumens 22 extending from the tip region 6D to the base region 6P. As an example, the shaft 6 has a first lumen 24, a second lumen 26, a third lumen 28, and a fourth lumen 30. Each lumen 22 is formed by a lumen tube 32 embedded in the inner tube 16 of the tip region 6D and the inner tube 16 of the base region 6P. Each lumen 22 extends from the base end of the base region 6P to the tip of the tip region 6D. The lumen tube 32 can be made of known materials including fluororesins such as perfluoroalkyl vinyl ether copolymer (PFA) and polytetrafluoroethylene (PTFE).

[0029] Multiple first lead wires 34 are inserted through the first lumen 24. The tip end of each first lead wire 34 is electrically connected to each catheter electrode 10 belonging to the first electrode group G1 through side holes (not shown) formed in the side walls of the lumen tube 32, inner tube 16, and outer tube 18. The proximal end of each first lead wire 34 is electrically connected to a power supply via a connector on the handle body 12. Each first lead wire 34 has a structure in which, for example, the outer surface of a metal conductor is covered with a resin such as polyimide.

[0030] Multiple second lead wires 36 are inserted through the second lumen 26. The tip end of each second lead wire 36 is electrically connected to each catheter electrode 10 belonging to the second electrode group G2 through side holes (not shown) formed in the side walls of the lumen tube 32, inner tube 16, and outer tube 18. The proximal end of each second lead wire 36 is electrically connected to the power supply via a connector on the handle body 12. Each second lead wire 36 has a structure in which, for example, the outer surface of a metal conductor is covered with a resin such as polyimide.

[0031] By inserting multiple first lead wires 34 into the first lumen 24 and multiple second lead wires 36 into the second lumen 26, the multiple first lead wires 34 and the multiple second lead wires 36 can be insulated from each other. This makes it possible to more reliably prevent short circuits from occurring between the first lead wires 34 and the second lead wires 36.

[0032] Multiple third lead wires 38 are inserted through the third lumen 28. The tip end of each third lead wire 38 is electrically connected to each non-applied electrode 11 belonging to the third electrode group G3 through side holes (not shown) formed in the side walls of the lumen tube 32, inner tube 16, and outer tube 18. The base end of each third lead wire 38 is electrically connected to an external electrocardiograph or the like (not shown) via a connector on the handle body 12. Each third lead wire 38 has a structure in which, for example, the outer surface of a metal conductor is covered with a resin such as polyimide.

[0033] An operating wire 40 is inserted through the fourth lumen 30. The operating wire 40 is made of a metal such as stainless steel or a Ni-Ti superelastic alloy. The operating wire 40 may also be made of a high-strength non-conductive wire. The tip end of the operating wire 40 is fixed to a tip 42 (see Figure 1) attached to the tip of the shaft 6. The base end of the operating wire 40 is fixed to the operating section 14. The fourth lumen 30 and the operating wire 40 are eccentric with respect to the central axis of the inner tube 16. The operating wire 40 is slidable in the axial direction of the shaft 6 within the fourth lumen 30. When the user of the electrode catheter 2 rotates the operating section 14 in the direction of arrow A1 shown in Figure 1, the operating wire 40 is pulled toward the base end of the shaft 6. As a result, the tip end of the shaft 6 is curved in the direction of arrow A shown in Figure 1. The electrode catheter 2 may also be configured to have multiple operating wires 40 so that the tip end of the shaft 6 can be curved in multiple directions. Furthermore, the electrode catheter 2 may be configured without a manipulative wire 40, so that bending operations are not performed. Also, the tip 42 may be used as an electrode by connecting a lead wire.

[0034] Figure 3 is a schematic diagram showing the electrode catheter 2 inserted into the sheath 4. The shaft 6 in this embodiment has a narrow-diameter section 44 in the proximal region 6P. The narrow-diameter section 44 has a diameter smaller than the diameter of the tip region 6D. For example, the diameter of the narrow-diameter section 44 is smaller than the diameter of any part of the tip region 6D of the shaft 6. The diameter of each part, in other words, the outer diameter, is, for example, the average value of the diameters at multiple measurement points arranged at equal intervals in the axial direction of the shaft 6. The diameter of the tip region 6D is, for example, 6 Fr (2.0 mm) or less. The diameter of the narrow-diameter section 44 is, for example, 5.7 Fr (1.9 mm) or less, or 5.4 Fr (1.8 mm) or less. Also, the diameter of the narrow-diameter section 44 may be 5% or more smaller than the diameter of the tip region 6D, or 10% or more smaller.

[0035] For example, the narrow-diameter portion 44 can be formed by making the outer tube 18 in the portion of the base end region 6P where the narrow-diameter portion 44 is provided thinner than the outer tube 18 in the tip end region 6D. Alternatively, the narrow-diameter portion 44 can also be formed by reducing the diameter of the inner tube 16. When reducing the dimensions of the outer tube 18 or inner tube 16, the reinforcing member 20 may be thinned as needed. The reduction in rigidity of the base end region 6P due to the provision of the narrow-diameter portion 44 can be compensated for by the reinforcing member 20 or by selecting the hardness of the material constituting the base end region 6P. The inner diameter of the sheath 4 is large enough for the tip end region 6D to be inserted.

[0036] The narrow-diameter portion 44 extends within the sheath 4 when the shaft 6 is inserted into the patient's blood vessel via the sheath 4. The tip-side region 6D extends outside the sheath 4, passing through the sheath 4, when the shaft 6 is inserted into the blood vessel via the sheath 4. The length of the narrow-diameter portion 44 in the axial direction of the shaft 6, that is, the extent of the narrow-diameter portion 44, is, for example, longer than the length of the sheath 4 and may encompass the entire proximal-side region 6P, or it may extend from the proximal end to partway along the proximal-side region 6P. In this embodiment, the narrow-diameter portion 44 is positioned on the proximal side of the shaft 6 relative to the third electrode group G3, which consists of a plurality of non-applied electrodes 11. Therefore, the shaft 6 has a step that gradually narrows from the tip side to the proximal side, at least from the proximal side of the catheter electrode 10 located at the most proximal end, and in this embodiment, from the proximal side of the third electrode group G3, and the thickness from this step toward the proximal end is substantially uniform.

[0037] For example, a shaft 6 in which the entire base-side region 6P is a narrow-diameter portion 44 can be formed as follows. That is, a tip-side shaft corresponding to the tip-side region 6D and a base-side shaft corresponding to the base-side region 6P are manufactured. The diameter of the tip-side shaft is, for example, 6Fr, and the diameter of the base-side shaft is, for example, 5.4Fr. Next, the base end of the tip-side shaft and the tip of the base-side shaft are brought together, and a heat-shrinkable tube is placed over the boundary between them. Then, the heat-shrinkable tube is melted by heating, connecting the tip-side shaft and the base-side shaft to each other. This gives the shaft 6. The surface of the boundary between the tip-side shaft and the base-side shaft is smoothly continuous due to the fusion of the heat-shrinkable tube.

[0038] A port 46 is provided at the proximal end of the sheath 4. A blood aspiration device 100, such as a syringe, is connected to the port 46. When negative pressure is applied to the inside of the sheath 4 through the port 46 by the blood aspiration device 100, blood flows from the blood vessel to the port 46 side through the gap 48 between the inner circumferential surface of the sheath 4 and the outer circumferential surface of the narrow diameter portion 44. This allows blood collection to be performed using the sheath 4. A hemostatic valve for passing the electrode catheter 2 is provided at the proximal end of the sheath 4. This prevents blood from flowing towards the handle 8 side of the electrode catheter 2 during blood collection.

[0039] The reason why blood sampling is necessary during defibrillation is as follows: In other words, the need for defibrillation means that the heart is not functioning properly. When the heart does not function properly, blood is not pumped properly throughout the body, increasing the risk of blood clot formation. Blood clots can travel through the blood vessels and cause conditions such as cerebral infarction, pulmonary embolism, and myocardial infarction. Therefore, when performing defibrillation, it is necessary to pay attention to the formation of blood clots. Although it is necessary to pay attention to the formation of blood clots in procedures other than defibrillation, which involves inserting electrode catheter 2 into the body, particular caution is required in the case of defibrillation.

[0040] Normally, anticoagulants such as heparin are administered to patients to prevent the formation of blood clots. However, excessively suppressing blood clotting increases the risk of being unable to stop bleeding in the event of an injury. Therefore, it is necessary to appropriately manage the blood's clotting ability. For these reasons, it may be necessary to collect blood at regular time intervals during a procedure. In the case of conventional electrode catheters that do not have a thin diameter section 44, it is necessary to increase the size of the sheath relative to the electrode catheter, insert an additional sheath for blood collection, or withdraw the electrode catheter each time blood is collected and reinsert it after blood collection is complete. In this case, the operator's effort is significant, and the patient's body is burdened. In contrast, with the medical device 1 according to this embodiment, blood can be collected using the sheath 4 with the electrode catheter 2 inserted, while maintaining the operability of the electrode catheter 2. Therefore, the operator's effort and the burden on the patient's body can be reduced.

[0041] As described above, the electrode catheter 2 of this embodiment has a small diameter portion 44 on the shaft 6. The small diameter portion 44 extends into the sheath 4 when the electrode catheter 2 is in use. This allows the gap 48 between the sheath 4 and the shaft 6 to be widened. Therefore, the negative pressure required for blood aspiration can be reduced, making blood collection easier.

[0042] Furthermore, because the shaft 6 is locally narrowed by the narrow-diameter section 44, the thickness of the tip region 6D can be maintained. If the tip region 6D is narrowed, the rigidity of the section between the first electrode group G1 and the second electrode group G2 decreases significantly compared to the rigidity of the section where each electrode group is positioned. In this case, when an external force is applied to the tip region 6D, that section becomes more prone to breaking. In contrast, by providing a narrow-diameter section 44 in the proximal region 6P to maintain the thickness of the tip region 6D, such breakage of the tip region 6D can be suppressed. Therefore, it is possible to suppress a decrease in the ease of inserting the electrode catheter 2 into a blood vessel and the stability when the tip region 6D is placed in the cardiac chamber. In addition, by maintaining the thickness of the tip region 6D, the catheter electrode 10 can be stably maintained in contact with the myocardium. This enables stable acquisition of potential information and more reliable defibrillation. On the other hand, the proximal region 6P is the part that mainly contributes to the transmission of force in the axial direction of the shaft 6. Therefore, as long as kink resistance, operability, and pushability are ensured, a thin profile is not a problem. Thus, a thin diameter section 44 can be easily installed in the base end region 6P.

[0043] Therefore, according to this embodiment, blood collection using the sheath 4 is possible while suppressing a decrease in the operability of the electrode catheter 2. Furthermore, in this embodiment, the bending rigidity of the proximal region 6P is higher than that of the distal region 6D. This further improves the operability when inserting the electrode catheter 2 into a blood vessel.

[0044] The embodiments of the present disclosure have been described in detail above. The above-described embodiments are merely illustrative of specific examples for carrying out the present disclosure. The contents of the embodiments do not limit the technical scope of the present disclosure, and many design changes such as alteration, addition, or deletion of constituent elements can be made without departing from the spirit of the present disclosure defined in the claims. A new embodiment to which a design change is added has the respective effects of the combined embodiments and modifications. In the above-described embodiments, the contents where such design changes are possible are emphasized by adding notations such as "of the present embodiment" and "in the present embodiment", but design changes are permitted even for contents without such notations. Any combination of the constituent elements included in each embodiment is also effective as an aspect of the present disclosure. The hatching applied to cross-sections in the drawings does not limit the material of the hatched object.

[0045] The embodiments may be specified by the following items. [Item 1] An electrode catheter (2) comprising a shaft (6) and a catheter electrode (10) provided on the tip region (6D) of the shaft (6) for applying voltage to biological tissue, wherein the shaft (6) has a proximal region (6P) located on the proximal end side of the shaft (6) from the catheter electrode (10), and a small diameter portion (44) that extends within the sheath (4) when the shaft (6) is inserted into the patient's blood vessel via the sheath (4) and has a smaller diameter than the diameter of the tip region (6D) that extends outside the sheath (4). [Item 2] The electrode catheter (2) of Item 1, wherein the proximal region (6P) has higher bending rigidity than the tip region (6D). [Item 3] The electrode catheter (2) is a defibrillation catheter inserted into the cardiac chamber to perform defibrillation, and comprises a first electrode group (G1) including multiple catheter electrodes (10), and a second electrode group (G2) including multiple catheter electrodes (10) and positioned more proximal to the first electrode group (G1) in the distal region (6D), the electrode catheter (2) of item 1 or 2. [Item 4] The shaft (6) has multiple lumens (22) extending from the distal region (6D) to the proximal region (6P), the electrode catheter (2) of item 1 to 3. [Item 5] An electrode catheter (2) according to any of Items 1 to 4, wherein a non-applied electrode (11) is provided on the shaft (6) on the proximal end side of the shaft (6) from the catheter electrode (10), and the narrow diameter portion (44) is located on the proximal end side of the shaft (6) from the non-applied electrode (11). [Item 6] A medical device (1) comprising an electrode catheter (2) according to any of Items 1 to 5, and a sheath (4) through which the electrode catheter (2) is inserted, wherein the tip of the sheath (4) is inserted into the patient's blood vessel to serve as the insertion port for the electrode catheter (2), and with the electrode catheter (2) inserted into the blood vessel via the sheath (4), a small diameter portion (44) extends within the sheath (4), and the proximal end has a port (46) to which a blood aspirator (100) is connected, and blood flows from the blood vessel to the port (46) through the gap between the inner circumferential surface of the sheath (4) and the outer circumferential surface of the small diameter portion (44).[Item 7] An electrode catheter (2) comprising a shaft (6) and a catheter electrode (10) provided on the tip region (6D) of the shaft (6) for applying voltage to biological tissue, wherein the shaft (6) has a narrow diameter portion (44) in the proximal region (6P) located on the proximal end side of the shaft (6) from the catheter electrode (10), the narrow diameter portion having a smaller diameter than the diameter of the tip region (6D).

[0046] This disclosure can be used in electrode catheters and medical devices.

[0047] 1 Medical device, 2 Electrode catheter, 4 Sheath, 6 Shaft, 6D Proximal region, 6P Proximal region, 10 Catheter electrode, 22 Lumen, 44 Thin section, 46 Port, 48 Gap.

Claims

1. An electrode catheter comprising a shaft and a catheter electrode provided at the tip of the shaft for applying voltage to biological tissue, wherein the shaft has a small diameter portion at the proximal end of the shaft, located on the proximal end side of the shaft from the catheter electrode, the proximal portion extending within the sheath when the shaft is inserted into the patient's blood vessel via the sheath, and having a smaller diameter than the diameter of the tip of the shaft that extends outside the sheath.

2. The electrode catheter according to claim 1, wherein the proximal region has higher bending rigidity than the tip region.

3. The electrode catheter is a defibrillation catheter inserted into the cardiac chamber to perform defibrillation, and comprises a first electrode group including a plurality of catheter electrodes, and a second electrode group including a plurality of catheter electrodes and positioned more proximal to the first electrode group in the tip region, according to claim 1 or 2.

4. The electrode catheter according to claim 1 or 2, wherein the shaft has a plurality of lumens extending from the tip region to the proximal region.

5. The electrode catheter according to claim 1 or 2, wherein a non-applied electrode, which is not used to apply voltage to biological tissue, is provided on the shaft on the proximal end side of the shaft from the catheter electrode, and the small diameter portion is located on the proximal end side of the shaft from the non-applied electrode.

6. A medical device comprising: an electrode catheter according to claim 1 or 2; and a sheath through which the electrode catheter is inserted, wherein the tip of the sheath is inserted into a patient's blood vessel to serve as an insertion port for the electrode catheter, the small diameter portion extends within the sheath when the electrode catheter is inserted into the blood vessel via the sheath, and the proximal end has a port to which a blood aspirator is connected, and blood flows from the blood vessel to the port through a gap between the inner circumferential surface of the sheath and the outer circumferential surface of the small diameter portion.

7. An electrode catheter comprising a shaft and a catheter electrode provided at the tip of the shaft for applying a voltage to biological tissue, wherein the shaft has a small diameter portion at the proximal end of the shaft, located on the proximal end side of the shaft relative to the catheter electrode, the proximal end portion having a smaller diameter than the diameter of the tip of the shaft.

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