Laser Applicator Having Electrodes

Abstract

A laser applicator includes an elongate catheter, which contains at least one peripherally closed lumen, and a light guide, which extends along the catheter and has an outcoupling region in a distal end section of the catheter. The laser applicator has at least one electrode at a distance defined in relation to the outcoupling region such that the position of the outcoupling region in relation to surrounding tissue can be sensed.

Claims

1. A laser applicator comprising an elongate catheter which contains at least one peripherally closed lumen, and a light guide, which extends along the catheter and has an outcoupling region in a distal end section of the catheter, wherein said laser applicator has at least one electrode at a distance defined in relation to the outcoupling region such that the position of the outcoupling region in relation to surrounding tissue can be sensed.

2. The laser applicator of claim 1, wherein the electrode has a con-tact surface exposed to the outside.

3. The laser applicator of claim 2, wherein the electrode has a contact surface exposed to the outside only in the region of a partial circumference, so as to allow the determination of the relative position of rotation of the outcoupling region with respect to contacted tissue, the outcoupling region also extending only over a partial circumference in the circumferential direction of the catheter.

4. The laser applicator of claim 1, wherein the electrode is arranged in the region of the distal end section.

5. The laser applicator of claim 1, wherein at least one electrode is arranged distally of the outcoupling region.

6. The laser applicator of claim 1, wherein two electrodes are arranged on sides of the outcoupling region opposing each other in the longitudinal direction of the catheter, so as to be able to sense the position of the outcoupling region in the longitudinal direction of the catheter with respect to surrounding tissue.

7. The laser applicator of claim 1, wherein on the side of the laser catheter opposite the outcoupling portion, at least one electrode is arranged which is conductive to the outside only over a partial circumference of the catheter.

8. The laser applicator of claim 1, wherein at least one electrode is formed to extend circumferentially in the circumferential direction of the catheter and, for a part of the circumference, is covered with an insulator towards the outside.

9. The laser applicator of claim 8, wherein at least two electrodes, which are formed to extend circumferentially in the circumferential direction and covered with an insulator towards the outside for a part of the circumference, are arranged at a distance from each other so as to allow the determination of the torsion of the catheter between the two electrodes.

10. The laser applicator of claim 1, wherein an evaluation means is provided for receiving and evaluating the electric signal, the evaluation means being electrically connected with each electrode.

11. The laser applicator of claim 1, wherein proximally and/or distally of the outcoupling region an electrode is respective arranged on the same side of the catheter as the outcoupling region.

12. The laser applicator of claim 11, wherein the electrodes arranged proximally and distally of the outcoupling region cover the same circumference as the outcoupling region.

13. The laser applicator of claim 1, wherein a fully circumferentially extending annular electrode and/or an electrode covering the distal end face of the catheter are arranged at the distal end of the catheter.

14. A method for determining the relative position of the outcoupling region of a laser applicator according to claim 1, with respect to material electrically contacted by the electrodes, comprising the following steps: measuring the electric potential or an electric current of the electrode, comparing the measured value to a reference value or to a previous measuring value, and determining, based on the comparison, whether the electrode electrically contacts electrically conductive material.

15. The method of claim 14, wherein the reference value is a value that corresponds to a case in which the electrode is in contact with an electric insulator, e.g. air, or to a case in which the electrode is in contact with electrically conductive material, e.g. biological tissue or water.

Description

[0017] An embodiment of the invention will be explained in detail hereunder. In the Figures:

[0018] FIG. 1 is a schematic illustration of the general structure of the light guide,

[0019] FIG. 2 is a cross section along line II-II in the midsection of the catheter in FIG. 1,

[0020] FIG. 3 is a cross section along line III-III in the distal end section of the catheter in FIG. 1,

[0021] FIG. 4 is a perspective view of another embodiment and

[0022] FIG. 5 is a top plan view on the other embodiment in the direction of the arrow V in FIG. 4.

[0023] The laser applicator illustrated in the Figures is described for most of its details in DE 10 2008 058 148 A1, the disclosure of which is incorporated into the present description by reference. In the Figures the following elements are identified by reference numerals:

[0024] 10 catheter

[0025] 10a section

[0026] 10b midsection, sections

[0027] 10c end section

[0028] 12 catheter body

[0029] 12a catheter body

[0030] 13 groove

[0031] 13a flanks

[0032] 13b flanks

[0033] 13c base

[0034] 14 lumen

[0035] 15 cooling channels

[0036] 16 cooling channels

[0037] 20 light guide

[0038] 21 core

[0039] 22 sleeve

[0040] 23 protective sheath

[0041] 25 adhesive

[0042] 26 covering tube

[0043] 26a covering tube

[0044] 30 shaping wire

[0045] 31 reflection layer

[0046] 33 material

[0047] 35 outlet bores

[0048] 36 outlet bores

[0049] 37 catheter splice site

[0050] 38 tube splice site

[0051] 40 outcoupling region

[0052] 41 openings

[0053] The disclosure beyond DE 10 2008 058 148 A1 will be explained in the following:

[0054] The length of the outcoupling region in the longitudinal direction of the catheter is identified by the reference numeral 40 in FIG. 1. An annular electrode 102, 104 is arranged proximally of the outcoupling region 40 and distally of the outcoupling region 40, respectively. The annular electrodes 102, 104 are characterized in that they are formed along the circumference of the laser applicator with an electric contact surface 106 so as to be electrically conductive over the entire circumference. Based on the measuring signals of the two annular electrodes 102, 104, it is possible to determine the position of the outcoupling region 40 in the longitudinal direction of the catheter with respect to tissue contacted by the electrodes 102, 104. Further, these annular electrodes are visible in radioscopy and mark the beginning and the end of the outcouplig region 40.

[0055] Moreover, a point electrode 108, 110 is arranged proximally and distally of the outcoupling region, respectively. In the circumferential direction of the catheter, the contact surfaces of the two point electrodes 108, 110 are on the same position if the catheter is not twisted. In this case, the relative angle between the two radial lines from the centre of the catheter through the centre of the respective electrode 108, 110 is 0 degrees. As soon as the catheter is twisted by torsion, the relative angle of rotation between the two electrodes 108, 110 changes. If this angle of rotation differs from 0, the catheter experiences torsion. The degree of the torsion of the catheter may be detected by means of the point detectors 108, 110.

[0056] The term point electrode presently generally denotes a single electrode, wherein the term point should not be understood in a mathematical sense. Rather, point electrode refers to an electrode that is to pick up the signal at a single point or in a closely confined region of the tissue. The point electrode may be of a circular or disc-shaped design.

[0057] In the side of the catheter opposite the outcoupling region 40 further electrodes 112, 114, 116 are arranged which each cover only a partial circumference of the catheter in an electrically conductive manner. Using these electrodes 112, 114, 116 it is possible to determine the relative angle of rotation of the outcoupling region 40 with respect to the tissue contacted by the electrodes 112, 114, 116. In particular, these electrodes 112, 114, 116 serve to determine the contact of the outcoupling region 40 with tissue, such as heart muscle tissue. This is because the electrodes on the rear of the outcoupling region should not be in contact with tissue, as long as the outcoupling region is in contact with tissue.

[0058] In the embodiment of FIGS. 4 and 5 two electrodes 112, 114 are arranged at a distance from each other on the side of the catheter opposite the outcoupling region 40. These electrodes are each designed as annular electrodes that cover the circumference mot covered by the outcoupling region 40. The circumference portion of the outcoupling region 40 is thus cutout in each of the two electrodes 112, 114. If one of the electrodes 112, 114 sends an electric signal due to contact with tissue, this may be seen as an indication that, in the region of the respective electrode, the outcoupling region 40 has no contact with tissue.

[0059] Further, an electrode 108 is arranged proximally of the outcoupling region 40 and another electrode 110 is arranged distally of the outcoupling region 40 on e same side of the catheter as the outcoupling region 40. The two electrodes 108, 110 each cover the same circumferential section of the catheter as the outcoupling region 40. If both electrodes 108, 110 send an electric signal caused by contact with tissue, this may be seen as an indication that the outcoupling region 40 situated therebetween is also in contact with tissue.

[0060] In the embodiment shown in FIG. 5, a distal end electrode 120 is formed as a full electrode at the distal end of the catheter. This means that the electrode 120 entirely covers the distal end face of the catheter. The electrode 120 of this embodiment is of a spherical-cap shape so as to form a blunt catheter end.

[0061] Proximally of the full electrode 120, an annular electrode 122 is arranged at a small distance of a few millimeters (less than 1 cm). The annular electrode 120 is a full electrode covering the full circumference of the catheter.