Electrode Assemblies for Measuring Impedance

1 . An electrode assembly, comprising:

an electrically-conductive wire, configured for insertion into a blood vessel of a subject;

an electrode surrounding the wire; and

a discontinuous electrically-insulating cover disposed between the wire and the electrode such that the wire lies radially opposite the electrode at a break in the discontinuous electrically-insulating cover.

2 . The electrode assembly according to claim 1 , wherein the electrode is shaped to define a helix.

3 . The electrode assembly according to claim 1 , wherein the electrode comprises a mesh.

4 . The electrode assembly according to claim 1 , wherein the electrode is coupled to the discontinuous electrically-insulating cover.

5 . The electrode assembly according to claim 1 , wherein a length of the break is less than 5 mm.

6 . The electrode assembly according to claim 1 , further comprising a reinforcing tube disposed around the discontinuous electrically-insulating cover.

7 . The electrode assembly according to claim 6 , wherein the reinforcing tube is proximal to the break.

8 . The electrode assembly according to claim 6 , wherein the reinforcing tube is distal to the break.

9 . The electrode assembly according to claim 6 , further comprising another electrode coupled to the reinforcing tube.

10 . The electrode assembly according to claim 1 , wherein the break includes a perforation in the discontinuous electrically-insulating cover.

11 . The electrode assembly according to claim 10 , wherein a surface area of the perforation is less than 0.8 mm 2 .

12 . Apparatus, comprising:

the electrode assembly according to claim 1 ; and

a treatment device, comprising:

a treatment element configured to treat an occlusion in the blood vessel; and

an electrically-insulating tube configured to facilitate delivery of the treatment element to the occlusion by advancing over the electrode assembly.

13 . The apparatus according to claim 12 ,

wherein the occlusion includes a thrombus,

wherein a distal portion of the electrically-insulating tube is shaped to define one or more apertures, and

wherein the treatment element comprises a treatment electrode surrounding the distal portion of the electrically-insulating tube and configured to attract the thrombus when a signal is applied between the treatment electrode and any electrically-conductive element disposed within the electrically-insulating tube, by virtue of an electrical current flowing through the apertures.

14 . The apparatus according to claim 13 ,

wherein the electrically-insulating tube is shaped to define a first lumen and a second lumen,

wherein the treatment element further comprises a return electrode,

wherein the signal is applied between the treatment electrode and the return electrode while the return electrode is disposed within the first lumen, and

wherein the electrically-insulating tube is configured to advance over the electrode assembly while the electrode assembly is disposed within the second lumen.

15 . The apparatus according to claim 14 , wherein the electrically-insulating tube is shaped to define a lateral window opening into the second lumen and disposed between a proximal end of the treatment electrode and a distal end of the treatment electrode.

16 . A method, comprising:

inserting, into a blood vessel of a subject, an electrode assembly including:

a wire,

an electrode surrounding around the wire, and

a discontinuous electrically-insulating cover disposed between the wire and the electrode such that the wire lies radially opposite the electrode at a break in the discontinuous electrically-insulating cover;

subsequently to inserting the electrode assembly, moving the electrode assembly through the blood vessel while monitoring a signal between the electrode and the wire, which results from ions flowing between the wire and the electrode via the break; and

treating an occlusion in the blood vessel responsively to the signal.

17 . The method according to claim 16 , wherein treating the occlusion comprises:

responsively to the signal, positioning a treatment device, which includes an electrically-insulating tube, by advancing the electrically-insulating tube over the electrode assembly; and

using the treatment device, treating the occlusion.

18 . The method according to claim 17 ,

wherein the occlusion includes a thrombus,

wherein the signal is a first signal,

wherein a distal portion of the electrically-insulating tube is shaped to define one or more apertures,

wherein the treatment device further includes a treatment electrode surrounding the distal portion of the electrically-insulating tube such that the apertures are disposed between a proximal end of the treatment electrode and a distal end of the treatment electrode, and

wherein treating the thrombus comprises attracting the thrombus to the treatment electrode by applying a second signal between the treatment electrode and any electrically-conductive element disposed within the electrically-insulating tube, by virtue of an electric current flowing through the apertures.

19 . The method according to claim 18 , wherein treating the thrombus further comprises:

subsequently to a start of the second signal, withdrawing the electrically-insulating tube and the electrode assembly from the blood vessel while the break in the discontinuous electrically-insulating cover is aligned with at least one of the apertures; and

while withdrawing the electrically-insulating tube and the electrode assembly, monitoring the first signal.

20 . The method according to claim 18 , wherein the electrically-conductive element is selected from the group of elements consisting of: the wire, the electrode, and another electrically-conductive element disposed over the wire.

21 . The method according to claim 18 ,

wherein the electrically-insulating tube is shaped to define a first lumen and a second lumen,

wherein the apertures open into the first lumen,

wherein the electrically-conductive element includes a return electrode disposed within the first lumen, and

wherein advancing the electrically-insulating tube over the electrode assembly comprises advancing the electrically-insulating tube over the electrode assembly while the electrode assembly is disposed within the second lumen.

22 . The method according to claim 21 , wherein the electrically-insulating tube is shaped to define a lateral window opening into the second lumen and disposed between a proximal end of the treatment electrode and a distal end of the treatment electrode, and wherein treating the thrombus further comprises:

subsequently to a start of the second signal, withdrawing the electrically-insulating tube and the electrode assembly from the blood vessel while the break in the discontinuous electrically-insulating cover is aligned with the lateral window; and

while withdrawing the electrically-insulating tube and the electrode assembly, monitoring the first signal.

23 . The method according to claim 16 ,

wherein the occlusion includes a thrombus,

wherein the signal is a first signal, and

wherein treating the thrombus comprises:

positioning the electrode assembly responsively to the first signal; and

attracting the thrombus to the electrode by applying a second signal between the electrode and the wire.

24 . The method according to claim 16 , further comprising generating the signal by applying a voltage or current between the electrode and the wire.

25 . The method according to claim 16 ,

wherein the electrode assembly further includes a pair of other electrodes, and

wherein the method further comprises generating the signal by applying a voltage or current between the pair of other electrodes.