Plasma ablation system and plasma guide wire
A plasma ablation system includes a plasma guide wire having a conductive first electrode formed on a distal end portion, a catheter having a conductive second electrode formed on a distal end side and a lumen through which the plasma guide wire is inserted, and a radio frequency (RF) generator electrically connected to each of the plasma guide wire and the catheter to output a high frequency electric power to the first electrode and the second electrode. The plasma guide wire can ablate a living body tissue by discharge between the first electrode and the second electrode, and the RF generator outputs the high frequency electric power that is 50 W or higher and 100 W or lower during discharge and pulse-modulated to have a duty ratio of 7.4% or higher and 40.0% or lower.
1 . A plasma ablation system comprising:
a plasma guide wire having an elongated external shape and comprising a conductive first electrode formed on a distal end portion;
a catheter having an elongated external shape and comprising a conductive second electrode formed on a distal end side and a lumen through which the plasma guide wire is inserted; and
a radio frequency (RF) generator electrically connected to each of the plasma guide wire and the catheter to output a high frequency electric power to the first electrode and the second electrode, wherein
the plasma guide wire can ablate a living body tissue by discharge between the first electrode and the second electrode, and
the RF generator outputs the high frequency electric power that is between 50 W and 100 W, inclusive during discharge and pulse-modulated to have a duty ratio of between 7.4% and 40.0%, inclusive.
2 . The plasma ablation system according to claim 1 , wherein the RF generator outputs the high frequency electric power pulse-modulated to have a duty ratio of 9.1% or higher and 13.0% or lower.
3 . The plasma ablation system according to claim 2 , wherein the plasma guide wire has a distal end load of 0.3 gf or higher and 20.0 gf or lower.
4 . The plasma ablation system according to claim 3 , wherein the plasma guide wire includes, in addition to the first electrode, a conductive core shaft having an elongated external shape, a conductive coil body arranged to surround a part of a distal end side of the core shaft, and an insulative covering portion arranged to cover an outer periphery of the coil body, wherein the first electrode fixes each distal end of the core shaft, the coil body, and the covering portion.
5 . The plasma ablation system according to claim 4 , wherein the catheter includes, in addition to the second electrode, a conductive proximal end-side electrode formed on a proximal end side of the catheter and electrically connected to the RF generator, and a conductive connection portion that electrically connects the second electrode with the proximal end-side electrode and is embedded in a thicker wall portion of the catheter.
6 . The plasma ablation system according to claim 5 , wherein the catheter further comprises a mesh-shaped reinforcement portion made of mesh-woven strands and embedded in the thicker wall portion of the catheter.
7 . The plasma ablation system according to claim 6 , wherein
a straight-line distance between the first electrode of the plasma guide wire and the second electrode of the catheter is 10 mm or longer and 50 mm or shorter.
8 . The plasma ablation system according to claim 1 , wherein the plasma guide wire has a distal end load of 0.3 gf or higher and 20.0 gf or lower.
9 . The plasma ablation system according to claim 1 , wherein the plasma guide wire includes, in addition to the first electrode, a conductive core shaft having an elongated external shape, a conductive coil body arranged to surround a part of a distal end side of the core shaft, and an insulative covering portion arranged to cover an outer periphery of the coil body, wherein the first electrode fixes each distal end of the core shaft, the coil body, and the covering portion.
10 . The plasma ablation system according to claim 9 , wherein the coil body is a multi-thread twisted wire coil formed by winding a plurality of twisted wires composed of a plurality of strands twisted together.
11 . The plasma ablation system according to claim 1 , wherein the catheter includes, in addition to the second electrode, a conductive proximal end-side electrode formed on a proximal end side of the catheter and electrically connected to the RF generator, and a conductive connection portion that electrically connects the second electrode with the proximal end-side electrode and is embedded in a thicker wall portion of the catheter.
12 . The plasma ablation system according to claim 11 , wherein the catheter further comprises a reinforcement portion embedded in the thicker wall portion of the catheter.
13 . The plasma ablation system according to claim 12 , wherein the reinforcement portion is made of mesh-woven strands.
14 . The plasma ablation system according to claim 12 , wherein the reinforcement portion includes a conductive material, and the thicker wall portion includes an insulating material between the reinforcement portion and the conductive connection portion.
15 . The plasma ablation system according to claim 11 , wherein the conductive connection portion has a coil shape made of conductive strands spirally wound along a circumferential direction of the catheter.
16 . The plasma ablation system according to claim 12 , wherein the reinforcement portion is closer to the lumen than the conductive connection portion.
17 . The plasma ablation system according to claim 1 , wherein a straight-line distance between the first electrode of the plasma guide wire and the second electrode of the catheter is 10 mm or longer and 50 mm or shorter.
18 . The plasma ablation system according to claim 1 , wherein the RF generator is further configured to output the high frequency electric power with a pulse width of 2 μs.
19 . The plasma ablation system according to claim 1 , wherein the plasma guide wire has a preshaped distal end portion.
20 . The plasma ablation system according to claim 1 , wherein the high frequency electric power is pulse-modulated with a pulse interval between 3 μs and 25 μs, inclusive.