Patent Description:
When atrial fibrillation occurs during cardiac catheterization surgery, electrical defibrillation needs to be performed.

The present applicant proposes, as a catheter for performing such defibrillation in a cardiac cavity, an intracardiac defibrillation catheter comprising an insulating tube member that has a multi-lumen structure, a handle that is connected to a proximal end of the tube member, a first DC electrode group that is made up of a plurality of ring-shaped electrodes mounted at a distal end portion of the tube member, a second DC electrode group that is made up of a plurality of ring-shaped electrodes spaced apart toward a proximal end side from the first DC electrode group and mounted at the distal end portion of the tube member, a first lead wire group that is made up of lead wires connected to each of the electrodes constituting the first DC electrode group, a second lead wire group that is made up of lead wires connected to each of the electrodes constituting the second DC electrode group, and an operating wire that, for flexing the distal end portion of the tube member and deflecting a distal end of the catheter, is eccentric with respect to a center axis of the tube member and extends in the tube member and has a rear end that can be operated by being pulled. The first lead wire group, the second lead wire group, and the operating wire respectively extend in different lumens of the tube member. When defibrillation is performed, voltages having polarities that differ from each other are applied to the first DC electrode group and the second DC electrode group (refer to Patent Literature <NUM> below).

By inserting a distal end portion of the intracardiac defibrillation catheter having such a structure from a superior vena cava into a right atrium, and by further inserting the distal end portion of the intracardiac defibrillation catheter into an opening of a coronary sinus (coronary sinus ostium) that exists at the lower back wall of the right atrium, the intracardiac defibrillation catheter is disposed so that the first DC electrode group is positioned in the coronary sinus and the second DC electrode group is positioned in the right atrium, after which voltages having polarities that differ from each other are applied to the first DC electrode group and the second DC electrode group. This makes it possible to apply electrical energy sufficient and required for defibrillation to a heart undergoing atrial fibrillation.

In addition, in recent years, the manipulation of inserting a distal end portion of an intracardiac defibrillation catheter from an inferior vena cava into a right atrium, forming a loop in the right atrium by the inserted distal end portion, and then inserting the distal end portion into a coronary sinus ostium has been performed. Such a manipulation (an approach from the inferior vena cava) has an invasiveness that is lower than the invasiveness of the manipulation of inserting an intracardiac defibrillation catheter from a superior vena cava into the right atrium and into the coronary sinus ostium (an approach from the superior vena cava), and is preferable from the viewpoint of postoperative appearance.

Conventionally, in order to realize good operability, intracardiac defibrillation catheters have been constituted so that the hardness of an insulating tube member increases stepwise from a distal end side toward a proximal end side (refer to, for example, paragraph [<NUM>] of Patent Literature below). Further relevant prior art is described in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

However, it cannot be necessarily said that the operability in conventional intracardiac defibrillation catheters is good.

The present invention has been made based on such circumstances, and an object of the present invention is to provide an intracardiac defibrillation catheter that excels in operability, in particular, operability when a distal end portion of the catheter made by mounting a first electrode group is inserted into a coronary sinus.

To this end, the present inventor has assiduously conducted studies repeatedly, and found out that, in a defibrillation catheter, since electrode groups (first electrode group and second electrode group) made by closely arranging ring-shaped electrodes having a wide width are mounted at a distal end portion of a tube member, the operability cannot be improved by merely increasing stepwise the hardness of the tube member from a distal end side toward a proximal end side, and good operability can be exhibited only after increasing stepwise from the distal end side toward the proximal end side the rigidity as a shaft at which electrodes (electrode groups) are mounted. Based on this finding, the present invention has been completed.

In particular it is provided an intracardiac defibrillation catheter having the features defined in claim <NUM>. That is, an intracardiac defibrillation catheter of the present invention is a catheter that comprises an insulating tube member that is made up of a distal end side tube and a proximal end side tube, a handle that is connected to a proximal end of the tube member, a first DC electrode group that is made up of a plurality of ring-shaped electrodes mounted at the distal end side tube of the tube member, and a second DC electrode group that is made up of a plurality ring-shaped electrodes spaced apart toward a proximal end side from the first DC electrode group and mounted at the distal end side tube, the catheter performing defibrillation in a cardiac cavity by applying voltages having polarities that differ from each other to the first DC electrode group and the second DC electrode group, wherein, with regard to each of a first shaft portion to a fifth shaft portion below, when a three-point bending test is performed with a distance between fulcra being <NUM> and a flexing amount that results from applying a bending load to an intermediate point of the distance being <NUM>, bending loads L1 to L5 measured for each of the shaft portions have a relationship of L1 < L2 < L3 < L4 < L5.

According to the intracardiac defibrillation catheter having such a structure, since the bending rigidity as a shaft at which the electrodes (electrode groups) are mounted increases stepwise from a distal end side toward the proximal end side, it is possible to exhibit excellent operability.

In the intracardiac defibrillation catheter of the present invention, it is preferable that a bending load L1 of the first shaft portion be <NUM> gf or less, and a bending load L4 of the fourth shaft portion be <NUM> gf or greater (<NUM> gf = <NUM> N).

The first shaft portion whose bending load L1 is <NUM> gf or less has bendability and, in particular, excels in insertability into a coronary sinus.

In addition, when the bending load L4 of the fourth shaft portion is <NUM> gf or greater, it is possible to clearly set a change (an increase) in the bending rigidity from the first shaft portion to the fourth shaft portion.

In the intracardiac defibrillation catheter of the present invention, it is preferable that, when a surface hardness of the distal end side tube that constitutes the first shaft portion is H1 and a surface hardness of the distal end side tube that constitutes the second shaft portion is H2, a difference between H2 and H1 be 16D to 35D, in particular, 20D to 30D.

When the hardness difference between H2 and H1 is 16D or greater, the bending rigidity in the second shaft portion at which an electrode group is not mounted can be reliably made larger than the bending rigidity in the first shaft portion that is made by mounting the first DC electrode group.

In addition, when the hardness difference is within 35D, it is possible to prevent the bending rigidity in the second shaft portion from becoming too large.

As a result, it is possible to further improve the operability, in particular, the operability when the distal end portion that is made by mounting the first DC electrode group is inserted into a coronary sinus.

Further, it is preferable that, when a surface hardness of the distal end side tube that constitutes the third shaft portion is H3 and a surface hardness of the distal end side tube that constitutes the fourth shaft portion is H4, a difference between H4 and H3 is 2D to 16D, in particular, 5D to 10D.

When the hardness difference between H4 and H3 is 2D or greater, the bending rigidity in the fourth shaft portion at which an electrode group is not mounted can be reliably made larger than the bending rigidity in the third shaft portion that is made by mounting the second DC electrode group.

In addition, when the hardness difference is within 16D, it is possible to prevent the bending rigidity in the fourth shaft portion from becoming too large.

As a result, it is possible to further improve the operability.

The intracardiac defibrillation catheter of the present invention excels in operability, in particular, operability when a tube portion at which the first DC electrode group is mounted is inserted into a coronary sinus.

A defibrillation catheter <NUM> of this embodiment shown in <FIG> is a catheter that comprises an insulating tube member <NUM> that is made up of a distal end side tube <NUM> and a proximal end side tube <NUM>, a control handle <NUM> that is connected to a proximal end of the tube member <NUM>, a distal end tip <NUM> that is fixed to a distal end of the tube member <NUM>, a first DC electrode group <NUM> that is made up of eight ring-shaped electrodes <NUM> mounted at the distal end side tube <NUM> of the tube member <NUM>, a second DC electrode group <NUM> that is made up of eight ring-shaped electrodes <NUM> spaced apart toward a proximal end side from the first DC electrode group <NUM> and mounted at the distal end side tube <NUM>, four ring-shaped electrodes <NUM> for measuring electrical potential that are mounted at the distal end side tube <NUM> on a proximal end side of the second DC electrode group <NUM>, a first lead wire group <NUM> that is made up of eight lead wires <NUM> connected to each of the electrodes <NUM> constituting the first DC electrode group <NUM>, a second lead wire group <NUM> that is made up of eight lead wires <NUM> connected to each of the electrodes <NUM> constituting the second DC electrode group <NUM>, four lead wires <NUM> that are connected to each of the ring-shaped electrodes <NUM> for measuring electrical potential, and an operating wire <NUM> that, for flexing a distal end portion of the tube member <NUM>, is eccentric with respect to a center axis of the tube member <NUM> and extends in the tube member <NUM>, has a distal end that is connected and fixed to the distal end tip <NUM>, and has a rear end that can be operated by being pulled. The catheter performs defibrillation in a cardiac cavity by applying voltages having polarities that differ from each other between the first DC electrode group <NUM> and the second DC electrode group <NUM>,
wherein with regard to each of a first shaft portion <NUM> that extends from a distal end of a catheter shaft to a proximal end position of the first DC electrode group <NUM>, a second shaft portion <NUM> that extends from the proximal end position of the first DC electrode group <NUM> to a distal end position of the second DC electrode group <NUM>, a third shaft portion <NUM> that extends from the distal end position of the second DC electrode group <NUM> to a proximal end position of the second DC electrode group <NUM>, a fourth shaft portion <NUM> that extends from the proximal end position of the second DC electrode group <NUM> to a proximal end position of the distal end side tube <NUM>, and a fifth shaft portion <NUM> that is made from the proximal end side tube <NUM>, when a three-point bending test is performed with the distance between fulcra being <NUM> and the flexing amount that results from applying a bending load to an intermediate point of the distance being <NUM>, bending loads L1, L2, L3, L4, and L5 measured for the first shaft portion <NUM>, the second shaft portion <NUM>, the third shaft portion <NUM>, the fourth shaft portion <NUM>, and the fifth shaft portion <NUM>, respectively, have the relationship of L1 < L2 < L3 < L4 < L5.

The defibrillation catheter <NUM> of the embodiment comprises the tube member <NUM>, the control handle <NUM>, the distal end tip <NUM>, the first DC electrode group <NUM>, the second DC electrode group <NUM>, the electrodes <NUM> for measuring electrical potential, the first lead wire group <NUM>, the second lead wire group <NUM>, the lead wires <NUM>, and the operating wire <NUM>.

The tube member <NUM> that constitutes the defibrillation catheter <NUM> is made up of the distal end side tube <NUM> and the proximal end side tube <NUM>, and is an insulating tube member that has a multi-lumen structure.

The outside diameter of the tube member <NUM> (the distal end side tube <NUM> and the proximal end side tube <NUM>) is, for example, <NUM> to <NUM>, with a preferred example being <NUM>.

The effective length of the tube member <NUM> is, for example, <NUM> to <NUM>, with a preferred example being <NUM>.

The length of the distal end side tube <NUM> is, for example, <NUM> to <NUM>, with a preferred example being <NUM>.

The length of the proximal end side tube <NUM> is, for example, <NUM> to <NUM>, with a preferred example being <NUM>.

As shown in <FIG>, the distal end side tube <NUM> that constitutes the tube member <NUM> comprises an inner part <NUM> and an outer part <NUM> that covers the inner part <NUM>.

As shown in <FIG>, the proximal end side tube <NUM> that constitutes the tube member <NUM> comprises an inner part <NUM>, an outer part <NUM> that covers the inner part <NUM>, and a braid <NUM> that is embedded in the outer part <NUM>.

Resin that constitutes each of the inner part <NUM> and the outer part <NUM> of the distal end side tube <NUM> and resin that constitutes each of the inner part <NUM> and the outer part <NUM> of the proximal end side tube <NUM> can be a thermoplastic polyamide-based elastomer, such as polyether block amide (PEBAX) or nylon.

The braid <NUM> that constitutes the proximal end side tube <NUM> can be a metal material, such as stainless steel, or a resin material, such as PEEK.

It is preferable that the hardness of the resin that constitutes the inner part <NUM> of the distal end side tube <NUM> and the hardness of the resin that constitutes the inner part <NUM> of the proximal end side tube <NUM> be 25D to 74D, with a preferred example being 63D. The hardness of the inner part <NUM> and the hardness of the inner part <NUM> may be the same as or may differ from each other.

As shown in <FIG> and <FIG>, four lumens <NUM> to <NUM> are each formed by being partitioned by a lumen tube <NUM> made of fluorine-based resin at the tube member <NUM> (the distal end side tube <NUM> and the proximal end side tube <NUM>).

The fluorine-based resin that constitutes the lumen tube <NUM> can be perfluoroalkyl vinyl ether copolymer (PFA) or polytetrafluoroethylene (PTFE).

The hardness of the resin that constitutes the outer part <NUM> of the distal end side tube <NUM> and the hardness of the resin that constitutes the outer part <NUM> of the proximal end side tube <NUM> (the surface hardness of the tube member <NUM>) increase stepwise from a distal end side toward the proximal end side.

Here, an example of a change in the hardness of the resin that constitutes the outer part <NUM> and a change in the hardness of the resin that constitutes the outer part <NUM> is one in which, when the shaft of the defibrillation catheter <NUM> is divided into the first shaft portion <NUM> that extends from the distal end of the catheter shaft to the proximal end position of the first DC electrode group <NUM> (the electrode <NUM> at a proximal-most end), the second shaft portion <NUM> that extends from the proximal end position of the first DC electrode group <NUM> to the distal end position of the second DC electrode group <NUM> (the electrode <NUM> at a distal-most end), the third shaft portion <NUM> that extends from the distal end position of the second DC electrode group <NUM> to the proximal end position of the second DC electrode group <NUM> (the electrode <NUM> at a proximal-most end), the fourth shaft portion <NUM> that extends from the proximal end position of the second DC electrode group <NUM> to the proximal end position of the distal end side tube <NUM> (a distal end position of the proximal end side tube <NUM>), and the fifth shaft portion <NUM> that is made from the proximal end side tube <NUM> (and that extends from the distal end position of the proximal end side tube <NUM> to a strain relief <NUM>), the hardness (H1) of the resin that constitutes the outer part <NUM> in the first shaft portion <NUM> is 40D, the hardness (H2) of the resin that constitutes the outer part <NUM> in the second shaft portion <NUM> is 63D, the hardness (H3) of the resin that constitutes the outer part <NUM> in the third shaft portion <NUM> is 63D, the hardness (H4) of the resin that constitutes the outer part <NUM> in the fourth shaft portion <NUM> is 72D, and the hardness (H5) of the resin that constitutes the outer part <NUM> in the fifth shaft portion <NUM> is 74D.

Note that a change in the hardness of the resin that constitutes the outer part <NUM> and the hardness of the resin that constitutes the outer part <NUM> is not limited to the example above as long as the relationship of H1 < H2 ≤ H3 < H4 < H5 is established and the relationship of L1 < L2 < L3 < L4 < L5 described below can be established.

In addition, the hardness of a boundary region between shaft portions that are adjacent to each other may change with a gradient.

The difference between the hardness (H2) and the hardness (H1) is preferably 16D to 35D and particularly preferably 20D to 30D.

When the hardness difference is 16D or greater, the bending rigidity of the second shaft portion <NUM> at which an electrode group is not mounted can be reliably made greater than the bending rigidity of the first shaft portion <NUM> that is made by mounting the first DC electrode group <NUM>.

In addition, when the hardness difference is within 35D, it is possible to prevent the bending rigidity of the second shaft portion <NUM> from becoming too large.

The difference between the hardness (H4) and the hardness (H3) is preferably 2D to 16D and particularly preferably 5D to 10D.

When the difference is 2D or greater, the bending rigidity of the fourth shaft portion <NUM> at which an electrode group is not mounted can be reliably made greater than the bending rigidity of the third shaft portion <NUM> at which the second DC electrode group <NUM> is mounted.

In addition, when the hardness difference is within 16D, it is possible to prevent the bending rigidity of the fourth shaft portion <NUM> from becoming too large.

The length of the first shaft portion <NUM> of the defibrillation catheter <NUM> is, for example, <NUM> to <NUM>, with a preferred example being <NUM>.

The length of the second shaft portion <NUM> is, for example, <NUM> to <NUM>, with a preferred example being <NUM>.

The length of the third shaft portion <NUM> is, for example, <NUM> to <NUM>, with a preferred example being <NUM>.

The length of the fourth shaft portion <NUM> is, for example, <NUM> to <NUM>, with a preferred example being <NUM>.

The length of the fifth shaft portion <NUM> is, for example, <NUM> to <NUM>, with a preferred example being <NUM>.

As shown in <FIG>, the control handle <NUM> that constitutes the defibrillation catheter <NUM> has a handle body <NUM>, a rotation operating part <NUM>, and the strain relief <NUM>.

By rotating the rotation operating part <NUM> in the direction of arrow A1 in <FIG>, it is possible to pull the rear end of the operating wire <NUM> described below.

The first DC electrode group <NUM> is mounted at the distal end side tube <NUM> (a structural portion of the first shaft portion <NUM>) that constitutes the tube member <NUM>.

In addition, the second DC electrode group <NUM> is mounted at the distal end side tube <NUM> (a structural portion of the third shaft portion <NUM>).

In the present invention, "electrode group" refers to an assembly of a plurality of electrodes that are mounted at narrow intervals (for example, <NUM> or less) with the same pole being constituted (with the same polarity), or for the same purpose.

The first DC electrode group is made by mounting, in a distal end portion of the tube member, a plurality of electrodes that constitute the same pole (negative pole or positive pole) at narrow intervals. Here, the number of electrodes that constitute the first DC electrode group, though differing depending upon the width of the electrodes and the arrangement interval of the electrodes, is, for example, <NUM> to <NUM>, and is preferably <NUM> to <NUM>.

In the present embodiment, the first DC electrode group <NUM> is constituted by eight ring-shaped electrodes <NUM>. The electrodes <NUM> that constitute the first DC electrode group <NUM> are connected to terminals of the same pole in a direct-current power supply device through the lead wires (the lead wires <NUM> that constitute the first lead wire group <NUM> shown in <FIG> and <FIG>) and a connector that is built in a proximal end portion of the control handle <NUM>.

Here, it is preferable that the width (the length in an axial direction) of electrode <NUM> be <NUM> to <NUM>, with a preferred example being <NUM> mm.

When the width of electrode <NUM> is too narrow, the heat generation amount when a voltage is applied becomes too large, and surrounding tissue may be damaged. On the other hand, when the width of electrode <NUM> is too wide, a portion in the tube member <NUM> at which the first DC electrode group <NUM> is mounted may lose its flexibility/bendability, or the sensitivity with which electrical potential information is detected may be reduced when the electrodes <NUM> are used for measuring electrical potential as described below.

It is preferable that the mounting interval between the electrodes <NUM> (the separation distance between the electrodes that are adjacent to each other) be <NUM> to <NUM>, with a preferred example being <NUM>.

When using the intracardiac defibrillation catheter <NUM> (when the intracardiac defibrillation catheter <NUM> is disposed in a cardiac cavity), the first DC electrode group <NUM> is positioned in a coronary sinus (CS).

The second DC electrode group is made by mounting at narrow intervals, in the distal end portion of the tube member spaced apart toward the proximal end side from the mounting position of the first DC electrode group, a plurality of electrodes that constitute a pole (positive pole or negative pole) opposite to that of the first DC electrode group. Here, the number of electrodes that constitute the second DC electrode group, though differing depending upon the width of the electrodes and the arrangement interval of the electrodes, is, for example, <NUM> to <NUM>, and is preferably <NUM> to <NUM>.

In the present embodiment, the second DC electrode group <NUM> is constituted by eight ring-shaped electrodes <NUM>. The electrodes <NUM> that constitute the second DC electrode group <NUM> are connected to terminals having the same pole (terminals having a pole that is opposite to that of the terminals to which the first DC electrode group <NUM> is connected) in a direct-current power supply device through the lead wires (the lead wires <NUM> that constitute the second lead wire group <NUM> shown in <FIG>) and a connector that is built in the proximal end portion of the control handle <NUM>.

Therefore, voltages having polarities that differ from each other are applied to the first DC electrode group <NUM> (the electrodes <NUM>) and the second DC electrode group <NUM> (the electrodes <NUM>), and the first DC electrode group <NUM> and the second DC electrode group <NUM> become electrode groups having polarities that differ from each other (when one of the electrode groups has a negative pole, the other electrode group has a positive pole).

Here, it is preferable that the width (the length in an axial direction) of electrode <NUM> be <NUM> to <NUM>, with a preferred example being <NUM>.

When the width of electrode <NUM> is too narrow, the heat generation amount when a voltage is applied becomes too large, and surrounding tissue may be damaged. On the other hand, when the width of electrode <NUM> is too wide, a portion of the tube member <NUM> at which the second DC electrode group <NUM> is mounted may lose its flexibility/bendability, or the sensitivity with which electrical potential information is detected may be reduced when the electrodes <NUM> are used for measuring electrical potential as described below.

When using the intracardiac defibrillation catheter <NUM> (when the intracardiac defibrillation catheter <NUM> is disposed in a cardiac cavity), the second DC electrode group <NUM> is positioned in a right atrium (RA).

Note that the electrodes that constitute the first DC electrode group <NUM> and the electrodes that constitute the second DC electrode group can be used for measuring electrical potential.

Four electrodes <NUM> are mounted for measuring electrical potential at the distal end side tube <NUM> (a structural portion of the fourth shaft portion <NUM>) on the proximal end side of the second DC electrode group <NUM>.

The electrodes <NUM> that are mounted on the proximal end side of the second DC electrode group <NUM> are connected to an electrocardiograph through the lead wires (the lead wires <NUM> shown in <FIG>) and a connector that is built in the proximal end portion of the control handle <NUM>.

When the width of electrode <NUM> is too wide, the measurement accuracy of a cardiac potential is reduced, and it becomes difficult to identify the site of occurrence of an abnormal potential.

The distal end tip <NUM> is mounted at the distal end of the tube member <NUM>.

A lead wire is not connected to the distal end tip <NUM>, and, in the present embodiment, the distal end tip <NUM> is not used as an electrode. However, by connecting a lead wire, the distal end tip <NUM> can also be used as an electrode. The constituent material of the distal end tip <NUM> is, for example, a metal material, such as platinum or stainless steel, or various resin materials, and is not particularly limited.

In order to realize good contrast property with respect to X rays, it is preferable that the electrodes <NUM> that constitute the first DC electrode group <NUM>, the electrodes <NUM> that constitute the second DC electrode group <NUM>, and the electrodes <NUM> for measuring electrical potential be made of platinum or a platinum-based alloy.

The first lead wire group <NUM> shown in <FIG> and <FIG> is an assembly of eight lead wires <NUM> that are connected to each of the eight electrodes <NUM> that constitute the first DC electrode group <NUM>.

By the first lead wire group <NUM> (the lead wires <NUM>), each of the eight electrodes <NUM> that constitute the first DC electrode group <NUM> can be electrically connected to the direct-current power supply device.

The eight electrodes <NUM> that constitute the first DC electrode group <NUM> are connected to the respective different lead wires <NUM>. Each of the lead wires <NUM> is, at a distal end thereof, welded to an inner peripheral surface of electrode <NUM>, and enters a first lumen <NUM> from a side hole that is formed in a tubular wall of the tube member <NUM>. The eight lead wires <NUM> that have entered the first lumen <NUM> extend to the first lumen <NUM> as the first lead wire group <NUM> and enter the inside of the control handle <NUM>.

The second lead wire group <NUM> shown in <FIG> is an assembly of eight lead wires <NUM> that are connected to each of the eight electrodes <NUM> that constitute the second DC electrode group <NUM>.

By the second lead wire group <NUM> (the lead wires <NUM>), each of the eight electrodes <NUM> that constitute the second DC electrode group <NUM> can be electrically connected to the direct-current power supply device.

The eight electrodes <NUM> that constitute the second DC electrode group <NUM> are connected to the respective different lead wires <NUM>. Each of the lead wires <NUM> is, at a distal end thereof, welded to an inner peripheral surface of electrode <NUM>, and enters a second lumen <NUM> from a side hole that is formed in a tubular wall of the tube member <NUM>. The eight lead wires <NUM> that have entered the second lumen <NUM> extend to the second lumen <NUM> as the second lead wire group <NUM> and enter the inside of the control handle <NUM>.

As described above, the first lead wire group <NUM> (the eight lead wires <NUM>) extends in the first lumen <NUM> and the second lead wire group <NUM> (the eight lead wires <NUM>) extends in the second lumen <NUM>, whereby the first lead wire group <NUM> and the second lead wire group <NUM> can be insulated and isolated from each other in the tube member. Therefore, when a voltage required for intracardiac defibrillation is applied, it is possible to reliably prevent occurrence of a short circuit between the first lead wire group <NUM> (the first DC electrode group <NUM>) and the second lead wire group <NUM> (the second DC electrode group <NUM>).

The four lead wires <NUM> shown in <FIG> are, respectively, connected to the four electrodes <NUM> for measuring electrical potential.

The four lead wires <NUM> are, at respective distal ends thereof, welded to an inner peripheral surface of electrode <NUM>, and enter a third lumen <NUM> from a side hole that is formed in a tubular wall of the tube member <NUM>, extend to the third lumen <NUM>, and enter the inside of the control handle <NUM>. By the lead wires <NUM>, each of the electrodes <NUM> can be connected to an electrocardiograph.

The lead wires <NUM>, the lead wires <NUM>, and the lead wires <NUM> are all made up of a resin coated wire in which an outer peripheral surface of a metal conductive wire is coated with resin, such as polyimide. Here, the film thickness of the coating resin is approximately <NUM> to <NUM>.

The defibrillation catheter <NUM> of the present embodiment comprises the operating wire <NUM> for flexing the distal end portion of the tube member <NUM>.

Although the operating wire <NUM> is constituted by stainless steel or a Ni-Ti-based super-elastic alloy, the operating wire <NUM> does not necessarily need to be constituted by a metal, and may be constituted by, for example, a high-strength non-conductive wire.

As shown in <FIG> and <FIG>, the operating wire <NUM> is inserted so as to be movable in a tube axis direction in the fourth lumen <NUM> of the tube member <NUM>.

A distal end of the operating wire <NUM> is connected and fixed to the distal end tip <NUM> with solder filled in an internal space of the distal end tip <NUM>.

A rear end of the operating wire <NUM> is connected and fixed to the rotation operating part <NUM> of the control handle <NUM> and can be operated by being pulled.

By rotating the rotation operating part <NUM> in the direction of arrow A1 in <FIG>, the rear end of the operating wire <NUM> is pulled to make it possible to flex the distal end portion of the tube member <NUM> in the direction of arrow A in <FIG>.

The defibrillation catheter <NUM> of the present embodiment is constituted so that the bending rigidity of the shaft is increased stepwise from the distal end side toward the proximal end side.

Specifically, with regard to each of the first shaft portion <NUM>, the second shaft portion <NUM>, the third shaft portion <NUM>, the fourth shaft portion <NUM>, and the fifth shaft portion <NUM> of the defibrillation catheter <NUM>, when a three-point bending test is performed with the distance between fulcra being <NUM> and the flexing amount that results from applying a bending load to an intermediate point of the distance being <NUM>, the bending loads L1 to L5 measured for each of the shaft portions have the relationship of L1 < L2 < L3 < L4 < L5.

In this way, by increasing the surface hardness of the tube member <NUM> (the hardness of the resin that constitutes the outer part <NUM> of the distal end side tube <NUM> and the hardness of the resin that constitutes the outer part <NUM> of the proximal end side tube <NUM>) stepwise from the distal end side toward the proximal end side and by causing the bending rigidity of the shaft at which the electrodes (the electrode groups) are mounted to increase stepwise from the distal end side toward the proximal end side, it is possible to remarkably improve the operability compared with the operability of conventional defibrillation catheters.

In the defibrillation catheter <NUM>, it is preferable that the value of the bending load L1 of the first shaft portion <NUM> that results from the three-point bending test above be <NUM> gf or less.

The first shaft portion <NUM> whose bending load L1 is <NUM> gf or less has good flexibility/bendability, and, in particular, excels in insertability into a coronary sinus.

In addition, it is preferable that the bending load L4 of the fourth shaft portion <NUM> that results from the three-point bending test above be <NUM> gf or greater.

When the value of the bending load L4 of the fourth shaft portion <NUM> is <NUM> gf or greater, it is possible to clearly set a change (an increase) in the bending rigidity from the first shaft portion <NUM> to the fourth shaft portion <NUM>.

Although one embodiment of the present invention has been described above, the defibrillation catheter of the present invention is not limited to such embodiments and can be variously changed.

For example, the defibrillation catheter of the present invention may be a bi-directional type that comprises two operating wires.

In addition, the tube member that constitutes the defibrillation catheter of the present invention may be a single lumen structure.

Defibrillation catheters <NUM> of the present embodiment having a form such as that shown in <FIG> and the specifications given below were manufactured.

Two defibrillation catheters <NUM> having the structure above were prepared (Examples <NUM> and <NUM>), and a three-point bending test was performed on each of the defibrillation catheters <NUM> to measure the bending loads L1 to L5 of the respective first shaft portion <NUM> to fifth shaft portion <NUM>.

As the three-point bending test, two supports were disposed with a separation distance between the two supports (distance between fulcra) being <NUM>, and a shaft was placed on the supports so that each shaft portion whose bending load was to be measured was positioned at an intermediate point between the two supports. Next, a bending load in a direction perpendicular to an axial direction of the shaft was applied to a position on the shaft, placed on the supports, corresponding to the intermediate point between the supports, to determine the relationship between the flexing amount, being a displacement in the perpendicular direction, and the magnitude of the bending load measured by a load meter and to measure the bending load of the shaft (each shaft portion to be measured) when the flexing amount became <NUM>. Here, the test was performed at room temperature and the flexing speed was <NUM>/min.

Note that, regarding the first shaft portion <NUM> and the third shaft portion <NUM>, a bending load was applied to each of the first shaft portion <NUM> and the third shaft portion <NUM> from the ring-shaped electrodes that constitute the electrode groups.

Note that, in the "three-point bending test" prescribed in the present invention, as long as a shaft portion whose bending load is to be measured is positioned at the intermediate point between the two supports, shaft portions that are adjacent to the shaft portion to be measured may be positioned on the two supports.

On the other hand, three commercially available defibrillation catheters were prepared (Comparative Examples <NUM> to <NUM>), and bending loads L1 to L5 were measured in the same way as described above.

The results are shown in Table <NUM> below and <FIG>.

As shown in Table <NUM> and <FIG>, the defibrillation catheters <NUM> of Examples <NUM> and <NUM> are such that the shaft bending rigidity increases stepwise from the distal end side toward the proximal end side (the relationship of L1 < L2 < L3 < L4 < L5 is established).

In addition, the defibrillation catheters <NUM> of Examples <NUM> and <NUM> excelled in operability when the first DC electrode group <NUM> was disposed in a coronary sinus and the second DC electrode group <NUM> was disposed in a right atrium.

In contrast, in the defibrillation catheter of Comparative Example <NUM>, the bending rigidity in the second shaft portion was lower than the bending rigidity of the first shaft portion and the bending rigidity in the fifth shaft portion was lower than the bending rigidity of the fourth shaft portion; in the defibrillation catheter of Comparative Example <NUM>, the bending rigidity in the third shaft portion was lower than the bending rigidity of the second shaft portion; and, in the defibrillation catheter of Comparative Example <NUM>, the bending rigidity in the fifth shaft portion was lower than the bending rigidity of the fourth shaft portion.

The defibrillation catheters of Comparative Examples <NUM> to <NUM> were inferior in operability due to a kink occurring easily between shaft portions whose relationship between the bending rigidities were reversed.

Claim 1:
An intracardiac defibrillation catheter (<NUM>) having a shaft and comprising an insulating tube member (<NUM>) that is made up of a distal end side tube (<NUM>) and a proximal end side tube (<NUM>), a handle (<NUM>) that is connected to a proximal end of the tube member (<NUM>), a first electrode group (<NUM>) that is made up of a plurality of ring-shaped electrodes (<NUM>) mounted at the distal end side tube (<NUM>) of the tube member (<NUM>), and a second electrode group (<NUM>) that is made up of a plurality of ring-shaped electrodes (<NUM>) spaced apart toward a proximal end side from the first electrode group (<NUM>) and mounted at the distal end side tube (<NUM>),
the catheter (<NUM>) being configured to perform defibrillation in a cardiac cavity by applying voltages having polarities that differ from each other to the first electrode group (<NUM>) and the second electrode group (<NUM>), wherein, with regard to each of a first shaft portion (<NUM>), a second shaft portion (<NUM>), a third shaft portion (<NUM>), a fourth shaft portion (<NUM>), and a fifth shaft portion (<NUM>), when a three-point bending test is performed with a distance between fulcra being <NUM> and a flexing amount that results from applying a bending load to an intermediate point of the distance being <NUM>, bending loads L1 to L5 measured for each of the first to fifth shaft portions (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) have a relationship of L1 < L2 < L3 < L4 < L5, wherein
- the first shaft portion (<NUM>) is a shaft portion that extends from a distal end of a catheter shaft of the intracardiac defibrillation catheter (<NUM>) to a proximal end position of the first electrode group (<NUM>),
- the second shaft portion (<NUM>) is a shaft portion that extends from the proximal end position of the first electrode group (<NUM>) to a distal end position of the second electrode group (<NUM>),
- the third shaft portion (<NUM>) is a shaft portion that extends from the distal end position of the second electrode group (<NUM>) to a proximal end position of the second electrode group (<NUM>),
- the fourth shaft portion (<NUM>) is a shaft portion that extends from the proximal end position of the second electrode group (<NUM>) to a proximal end position of the distal end side tube (<NUM>),
- and the fifth shaft portion (<NUM>) is a shaft portion that extends along the proximal end side tube (<NUM>).